WO2014105981A1 - Method of preparing electroactive article and electroactive article formed in accordance therewith - Google Patents

Method of preparing electroactive article and electroactive article formed in accordance therewith Download PDF

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Publication number
WO2014105981A1
WO2014105981A1 PCT/US2013/077858 US2013077858W WO2014105981A1 WO 2014105981 A1 WO2014105981 A1 WO 2014105981A1 US 2013077858 W US2013077858 W US 2013077858W WO 2014105981 A1 WO2014105981 A1 WO 2014105981A1
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WIPO (PCT)
Prior art keywords
electroactive
alternatively
electrode layer
silicone
electrode layers
Prior art date
Application number
PCT/US2013/077858
Other languages
French (fr)
Inventor
Kent R. LARSON
Michael RABIDEAU
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Dow Corning Corporation
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Publication of WO2014105981A1 publication Critical patent/WO2014105981A1/en

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/098—Forming organic materials

Definitions

  • the present invention generally relates to a method of preparing an electroactive article and, more specifically, to a method of preparing an electroactive article having excellent mechanical properties and to the electroactive article formed in accordance therewith.
  • Electroactive polymers are known in the art and are characterized by their ability to change in configuration (e.g. size and/or shape) upon application of an electric field. For example, electroactive polymers exhibit a change in configuration when disposed between two electrodes and when a potential difference is applied between the two electrodes.
  • the present invention provides a method of preparing an electroactive article.
  • the method comprises the step of providing a first electrode layer.
  • the method further comprises the step of forming an electroactive layer adjacent and substantially parallel to the first electrode layer.
  • the method comprises the step of forming a second electrode layer disposed adjacent and substantially parallel to the electroactive layer, thereby preparing the electroactive article.
  • the present invention also provides the electroactive article formed in accordance with the method. BRIEF DESCRIPTION OF THE DRAWINGS
  • Figure 1 is a schematic cross-sectional view of one embodiment of an electroactive article.
  • the present invention provides a method of preparing an electroactive article.
  • the electroactive article has excellent physical properties and is suitable for use in many diverse applications and end uses.
  • the method comprises the step of providing a first electrode layer.
  • the method further comprises forming an electroactive layer adjacent and substantially parallel to the first electrode layer.
  • the method comprises the step of forming a second electrode layer disposed adjacent and substantially parallel to the electroactive layer, thereby preparing the electroactive article.
  • the first electrode layer 16 and the second electrode layer 12 generally sandwich the electroactive layer 14 in the electroactive article 10.
  • the electroactive article may include further layers, e.g. the electroactive article may include an additional electroactive layer adjacent either or both of the first and second electrode layers, with additional electrode layers being disposed adjacent any additional electroactive layers.
  • the first electrode layer, the electroactive layer, and/or the second electrode layer may be separately formed such that the method comprising combining or assembling the respective layers to prepare the electroactive article, e.g. in a roll-to-roll process.
  • the electroactive layer is formed from an electroactive polymer.
  • the electroactive polymer utilized to form the electroactive layer may be any polymer having electroactive properties.
  • specific examples of the electroactive polymer include a dielectric electroactive polymer, a ferroelectric polymer, an electrostrictive graft polyol, a liquid crystalline polymer, an ionic electroactive polymer, an electrorheological fluid, an ionic polymer-metal composite, etc.
  • One specific examples of an electroactive layer suitable for the instant method is disclosed in co-pending U.S. Patent Application Ser. No. 61/746,584, which is entitled "ELECTRO ACTIVE ARTICLE INCLUDING MODIFIED ELECTRO ACTIVE LAYER" is incorporated by reference herein in its entirety.
  • the first electrode layer may be provided by purchasing or otherwise obtaining the first electrode layer. Alternatively, the first electrode layer may be formed in the instant method.
  • the first and second electrode layers may be the same as or different from one another. To this end, the first and second electrode layers are described collectively below, although it is to be appreciated that the first and second electrode layers may be independently selected from the various embodiments of the first and second electrode layers below.
  • the first electrode layer can function as an anode or cathode in the electroactive article, and, similarly, the second electrode layer can function as an anode or cathode in the electroactive article.
  • the first and/or second electrode layers may be transparent or nontransparent to light in the visible region of the electromagnetic spectrum.
  • transparent means the particular layer (e.g., the first and/or second electrode layer) or component has a percent transmittance of at least 30%, alternatively at least 60%, alternatively at least 80%, for light in the visible region (e.g. at a wavelength of from 400 to 700 nm) of the electromagnetic spectrum.
  • nontransparent means the particular layer or component has a percent transmittance less than 30% for light in the visible region of the electromagnetic spectrum.
  • the first and second electrode layers may independently comprise any material that is electrically conductive.
  • the first and/or second electrode layers comprise a metal, alloy, or metal oxide.
  • Such materials include as indium oxide, tin oxide, zinc oxide, indium tin oxide (ITO), indium zinc oxide, antimony tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, nickel, gold, steel, titanium, covar, invar, tantalum, brass, niobium, carbon nanotubes, graphite, and combinations thereof or composites thereof.
  • the first electrode layer may alternatively or further comprise any other alloy or composite, such as Mg-Al, Ag-Mg, Al-Li, In-Mg, and Al-Ca.
  • the first and/or second electrode layers may be formed from an electrically conductive polymer or from a composition including an electrically conductive additive, e.g. a filler, which forms a cured product that is electrically conductive.
  • an electrically conductive additive e.g. a filler
  • the composition may be cured to form an elastomer, a foam, a gel, a rubber, a resin, etc. so long as the cured product is electrically conductive.
  • the first electrode layer may be provided or formed on a substrate.
  • the first electrode layer may be provided or formed on a release liner, and the release liner may be removed or separately from the electroactive article after its formation or the release liner may be removed or separated from the first electrode layer prior to or during the preparation of the electroactive article.
  • the first electrode layer may be physically and/or chemically bonded or adhered to the substrate, e.g. the release liner, such that the first electrode layer is bonded to the substrate even after the electroactive article is formed via the instant method.
  • the substrate may comprise a rigid or flexible material.
  • suitable materials that may be used to form the substrate include, but are not limited to, quartz; fused quartz; aluminum oxide; ceramics; glass; polyolefins such as polyethylene, polypropylene, polystyrene, and polyethyleneterephthalate; fluorocarbon polymers such as polytetrafluoroethylene and polyvinylfluoride; polyamides such as Nylon; polyimides; polyesters such as poly(methyl methacrylate), poly(ethylene 2,6- naphthalenedicarboxylate), and polyethylene terephthalate; epoxy resins; polyethers; polycarbonates; polysulfones; and polyether sulfones.
  • the presence of absence of the substrate is generally determined based on, among other factors, the rigidity of the first electrode layer as well as whether the first electrode layer is formed or otherwise provided.
  • the first electrode layer when the first electrode layer is sufficiently rigid, e.g. a metal or alloy sheet or foil, the first electrode layer may be utilized as the substrate for the formation of the electroactive layer thereon.
  • the substrate may be utilized even when the first electrode layer comprises a metal or alloy sheet or foil.
  • the first electrode layer has a thickness that does not provide for amble rigidity for forming the electroactive layer thereon without further support from the substrate.
  • the first electrode layer is generally formed on the substrate, although the first electrode layer may optionally be removed or separated from the substrate prior to forming the electroactive layer on the first electrode layer.
  • the first and/or second electrode layers may be formed via a deposition apparatus.
  • the deposition apparatus comprises a physical vapor deposition apparatus.
  • the deposition apparatus is typically selected from a sputtering apparatus, an atomic layer deposition apparatus, and a DC magnetron sputtering apparatus.
  • the sputtering apparatus may be, for example, an ion-beam sputtering apparatus, a reactive sputtering apparatus, an ion- assisted sputtering apparatus, etc.
  • the second electrode layer may be formed on the electroactive layer via the deposition apparatus.
  • the first and/or second electrode layers have electrical conductivity attributable to at least one conductive fiber.
  • the conductive fiber(s) may be embedded in a host matrix, e.g. any polymeric, cellular, and/or elastomeric matrix.
  • the host matrix may be, but is not required to be, electrically conductive. However, when the host matrix is utilized, the conductive fiber(s) is generally present at opposing major surfaces of the first and/or second electrodes for transferring an electrical current therebetween.
  • the host matrix is formed from a silicone composition.
  • the conductive fiber(s) may comprise a plurality of conductive fibers, alternatively a single conductive fiber.
  • the conductive fiber(s) of the first and/or second electrode layers may be woven or nonwoven.
  • the conductive fiber(s) may be made from a single material, alternatively from a blend of two or more different materials. The blend of materials may be homogenous, alternatively heterogeneous.
  • the conductive fiber(s) may comprise combinations and/or composites of certain materials. For example, different conductive fibers within the first and/or second electrode layers may independently comprise different materials.
  • the single conductive fiber when a single conductive fiber is employed in the first and/or second electrode layers, the single conductive fiber may vary in its composition.
  • the conductive fiber(s) of the first and/or second electrode layers may independently be porous or non-porous, optionally having one or more porous or non- porous coatings.
  • the conductive fiber(s) of the first and/or second electrode layers may be woven, nonwoven, or combinations thereof.
  • the conductive fiber(s) of the first and/or second electrode layers may be interlaced with one another such that certain conductive fiber(s) (or portions of conductive fiber(s)) are substantially parallel with one another (or with another portion of the same conductive fiber) and certain conductive fiber(s) (or portions of conductive fiber(s)) are substantially perpendicular to one another (or to another portion of the same conductive fiber).
  • the angles between certain conductive fiber(s) may be other than perpendicular, e.g.
  • the conductive fiber(s) of the first and/or second electrode layers are woven, the conductive fiber(s) generally have a defined pattern. Typically, such woven conductive fiber(s) are referred to as a cloth.
  • the conductive fiber(s) of the first and/or second electrode layers are nonwoven, the conductive fiber(s) of the first and/or second electrode layers are generally entangled with one another such that the first and/or second electrode layers includes a web of conductive fiber(s) that are bonded together mechanically, thermally, and/or chemically without a defined pattern. Adjacent conductive fibers that are in contact with one another may be fused to one another (e.g.
  • non-woven conductive fibers are referred to as a mat or a roving.
  • the conductive fiber(s) may be loose and individual conductive fiber(s) that are not bonded together mechanically, thermally, and/or chemically.
  • the conductive fiber(s) may also be characterized by features including shape, dimension, surface area, surface roughness, construction, etc. One or more of these features may be uniform or non-uniform.
  • the dimensions of the conductive fiber(s), particularly a thickness of the conductive fiber(s), are generally selected based on a desired physical property of the first and/or second electrode layers.
  • the first and/or second electrode layers are sufficiently thin such that the electroactive article is flexible, in which case the conductive fiber(s) generally have a comparatively small thickness.
  • the conductive fiber(s) may comprise nanofibers having at least one dimension of less than about 100 nanometers (nm). Generally, this dimension refers to a greatest dimension perpendicular to a length of the conductive fiber(s).
  • the conductive fiber(s) may independently have a cross-sectional shape that is elliptical, spherical, square, rectangular, or other various shapes.
  • the conductive fiber construction in cross-section may be mono-component, alternatively multi-component.
  • the multi-component fibers may be bicomponent, alternatively 3- component or more.
  • the bicomponent fibers may have a cross-section that is sheath- core, matrix-fibril, islands-in-the-sea, or side-by-side.
  • the conductive fiber(s) may optionally be heat-treated prior to use to remove any organic or other contaminants.
  • the conductive fiber(s) may be heated in air at an elevated temperature, for example, 575 °C, for a suitable period of time, for example 2 hours.
  • the composition of the conductive fiber(s) is generally selected based on the desired physical properties of the first and/or second electrode layers and may comprise any conductive material that may be utilized to form conductive fiber(s).
  • the conductive fiber(s) may comprise a non-conductive material in addition to a conductive material.
  • natural or synthetic fibers which are non-conductive may be impregnated or coated with a conductive material, e.g. a carbon or metal-based material, to impart the natural or synthetic fiber(s) with electrical conductivity.
  • the conductive fiber(s) may be wholly conductive, i.e., the conductive fiber(s) may be free from non-conductive material.
  • the conductive fiber(s) of the first and/or second electrode layers may be formed via known methods, e.g. the conductive fiber(s) may be purchased or otherwise obtained or may be formed, for example, from spinning. In certain embodiments, the conductive fiber(s) may be spun via dry spinning, melt spinning, extrusion spinning, direct spinning, gel spinning, electrospinning, and/or drawing.
  • the conductive fiber(s) may be utilized to form the first and/or second electrode layers in various methods.
  • the conductive fiber(s) may be formed or otherwise disposed on the substrate (e.g. the release liner) to provide the first electrode layer.
  • the conductive fiber(s) may be embedded or otherwise incorporated into a film or composition which is utilized to form the host matrix.
  • the silicone composition may be disposed on a substrate to form a silicone film, and the conductive fiber(s) may be disposed, incorporated, or otherwise embedded in the silicone film.
  • the conductive fiber(s) may have sufficient rigidity such that no substrate is required (with our without the host matrix).
  • the conductive fiber(s) may be formed or otherwise disposed on the electroactive layer to form the second electrode layer.
  • the electroactive layer may be in an uncured or cured state prior to forming or disposing the conductive fiber(s) thereon to form the second electrode layer.
  • the conductive fiber(s) may be electrospun directly onto the electroactive layer to form the second electrode layer on the electroactive layer, i.e., the electroactive layer may act as the substrate or wafer for the electrospinning process.
  • the conductive fiber(s) may be electrospun onto a surrogate wafer and subsequently transferred or disposed on the electroactive layer.
  • the conductive fiber(s) may be formed or obtained from methods other then electrospinning, such as when the conductive fiber(s) are woven, in which case the conductive fiber(s) may be disposed on the electroactive layer in any manner to form the second electrode layer.
  • the conductive fiber(s) may be embedded or otherwise incorporated into a film or composition which is utilized to form the host matrix.
  • the conductive fiber(s) may be impregnated with the silicone composition, as introduced above.
  • the conductive fiber(s) may be impregnated with the silicone composition using a variety of methods.
  • the silicone composition may be applied to the release liner or other substrate to form a silicone film.
  • the silicone composition can be applied to the release liner using conventional coating techniques, such as spin coating, dipping, spraying, brushing, or screen- printing.
  • the silicone composition is typically applied to the release liner in an amount sufficient to embed the conductive fiber(s) therein.
  • the release liner may optionally have a corrugated surface to impart the first electrode layer with a particular surface roughness or corrugation. Further, the release liner may be coated or uncoated, and may include conductive fiber(s), fillers, or other additives thereon which may be imparted into the surface of the first electrode layer once separated from the release liner.
  • the conductive fiber(s) may be embedded in the silicone film, thereby forming an embedded silicone film.
  • the conductive fiber(s) may be embedded in the silicone film by simply disposing the conductive fiber(s) on the silicone film and allowing the silicone composition to saturate the conductive fiber(s). However, the conductive fiber(s) may be first deposited on the release liner, followed by the application of the silicone composition onto the conductive fiber(s). In another embodiment, when the conductive fiber(s) comprise a woven or nonwoven fabric, the conductive fiber(s) may be impregnated with the silicone composition by passing the conductive fiber(s) through the silicone composition without the use of the release liner.
  • the conductive fiber(s) are typically passed through the silicone composition at a rate of from 1 to 1,000 cm/s at room temperature (-23 + 2 °C).
  • the conductive fiber(s) are formed by electrospinning.
  • the silicone film may act as the substrate or wafer for the electrospinning process such that the electrospun fibers are deposited directly onto the silicone film to form the first electrode layer.
  • the electrospun fibers may be formed and subsequently disposed in or on the silicone film. While numerous different compositions may be utilized to electrospun conductive fibers, one such example is disclosed in U.S. Patent No. 8,262,980, which is incorporated by reference herein in its entirety.
  • the embedded silicone film may be degassed to form a degassed embedded silicone film.
  • the embedded silicone film may be degassed by subjecting it to a vacuum at a temperature of from room temperature (-23 + 2 °C) to 60 °C, for a period of time sufficient to remove entrapped air.
  • the embedded silicone film can typically be degassed by subjecting the embedded silicone film to a pressure of from 1,000 to 20,000 Pa for 5 to 60 minutes at room temperature.
  • an additional amount of the silicone composition may be applied to the degassed embedded silicone film to form an impregnated silicone film.
  • the silicone composition can be applied to the degassed embedded silicone film using conventional methods, as described above. Additional and sequential cycles of degassing and application of silicone composition may also be carried out.
  • the impregnated silicone film may also be compressed to remove excess silicone composition and/or entrapped air, and to reduce the thickness of the impregnated silicone film.
  • the impregnated silicone film can be compressed using conventional equipment such as a stainless steel roller, hydraulic press, rubber roller, or laminating roll set.
  • the impregnated silicone film is typically compressed at a pressure of from 1,000 Pa to 10 MPa and at a temperature of from room temperature (-23 + 2 °C) to 50 °C.
  • the silicone composition in the impregnated silicone film is cured to form the first electrode layer.
  • the silicone composition may be cured once the respective layers are combined to prepare the electroactive article, or the silicone composition may be cured or partially cured prior to combining the respective layers to prepare the electroactive article.
  • "Cured,” as defined herein, means that the silicone composition, which can be in the form of the component parts, a mixture, a solution, or a blend, is exposed to room temperature air, heated at elevated temperatures, or exposed to UV, electron beam, or microwave radiation. Heating can occur using any known conventional means such as by placing the silicone composition or, in this case, the impregnated silicone film, into an air circulating oven.
  • the impregnated silicone film can be heated at atmospheric, sub-atmospheric, or supra- atmospheric pressure.
  • the impregnated silicone film is typically heated at a temperature of from room temperature (-23 + 2 °C) to 250 °C, alternatively from room temperature to 200 °C, alternatively from room temperature to 150 °C, at atmospheric pressure.
  • the impregnated silicone film is heated for a length of time sufficient to cure (cross-link) the silicone composition.
  • the impregnated silicone film is typically heated at a temperature of from 150 to 200 °C for a period of from 0.1 to 3 hours.
  • impregnated silicone film can be heated in a vacuum at a temperature of from 100 to 200 °C and a pressure of from 1,000 to 20,000 Pa for a time of from 0.5 to 3 hours to form the reinforced silicone film.
  • the impregnated silicone film can be heated in the vacuum using a conventional vacuum bagging process.
  • a bleeder e.g., polyester
  • a breather e.g., nylon, polyester
  • a vacuum bagging film e.g., nylon
  • a vacuum e.g., 1,000 Pa
  • the silicone composition may be cured to form the host matrix, and then the conductive fiber(s) may be disposed on or embedded in the host matrix to form the first electrode layer.
  • the second electrode layer comprises the host matrix
  • the second electrode layer may be formed from the same method described above with respect to the first electrode layer.
  • the silicone composition may be applied to the electroactive layer, which acts as the substrate for forming the second electrode layer thereon.
  • the second electrode layer may be formed on its own substrate or release liner instead of on the electroactive layer. The second electrode layer may be separated or removed from the release liner before or after preparation of the electroactive article.
  • a foamed article may be utilized in or as the first and/or second electrode layers.
  • the foamed article may be formed from an electrically conductive composition, or the foamed article may be impregnated with or otherwise contain an electrically conductive additive, e.g. an electrically conductive filler, to impart the foamed article with electrical conductivity.
  • an electrically conductive additive e.g. an electrically conductive filler
  • the foamed article is open-celled.
  • open-celled foams include polyurethane, polyisocyanurate, polyurea, silicone, etc. Such open-celled foamed articles are known in the art.
  • open-celled foamed articles comprising polyurethane may be formed by reacting an isocyanate and a polyol in the presence of a blowing agent, which may be a chemical and/or a physical plowing agent.
  • a blowing agent which may be a chemical and/or a physical plowing agent.
  • the first and/or second electrode layers may be formed from the methods described above relating to the conductive fiber(s).
  • the first and/or second electrode layers may be formed in the presence of the electrically conductive additive, or the electrically conductive additive may be introduced into a foamed article to form the first and/or second electrode.
  • a carrier solvent or curable composition comprising the electrically conductive additive may be disposed on or in the foamed article such that the carrier solvent or curable composition fills at least a portion of the open cells of the foamed article.
  • a colloidal suspension comprising the electrically conductive additive may be utilized.
  • the carrier solvent may optionally be volatilized and removed from the first and/or second electrodes, leaving the electrically conductive additives in the open cells of the first and/or second electrode layers.
  • the curable composition may be cured such that the cured product including the electrically conductive additive forms a continuous phase through the open cells of the first and/or second electrode layers.
  • the foamed article may be passed through, submerged, or disposed in the carrier solvent or curable composition such that the carrier solvent or curable composition at least partially fills the voids defined by the open cells of the foamed article.
  • the foamed article may independently span an entire thickness of the first and/or second electrode layers, respectively.
  • the foamed article may be encapsulated by a host matrix, such as the host matrix described above, in which case the foamed article of the first and/or second electrode layers do not present any open cells at any surface of the first and/or second electrode layers.
  • the foamed article may be present in the first and/or second electrode layers such that the foamed article is not encapsulated within the first and/or second electrode layers.
  • the first and/or second electrode layers may comprise the foamed article at one or more surfaces of the first and/or second electrode layers, which generally introduces a surface roughness to the first and/or second electrode layers.
  • electrically conductive fillers suitable for forming the first and/or second electrode layers include aluminum nitride, aluminum oxide, aluminum trihydrate, barium titanate, beryllium oxide, boron nitride, carbon fibers, diamond, graphite, magnesium hydroxide, magnesium oxide, metal particulate, onyx, silicon carbide, tungsten carbide, zinc oxide, and a combination thereof.
  • the electrically conductive filler may comprise a metallic filler, an inorganic filler, a meltable filler, or a combination thereof.
  • Metallic fillers include particles of metals and particles of metals having layers on the surfaces of the particles. These layers may are typically electrically conductive themselves.
  • Suitable metallic fillers are exemplified by particles of metals selected from the group consisting of aluminum, copper, gold, nickel, silver, and combinations thereof, and alternatively aluminum.
  • Suitable metallic fillers are further exemplified by particles of the metals listed above having layers on their surfaces selected from the group consisting of aluminum nitride, aluminum oxide, copper oxide, nickel oxide, silver oxide, and combinations thereof.
  • the metallic filler may comprise aluminum particles having aluminum oxide layers on their surfaces.
  • meltable fillers may comprise Bi, Ga, In, Sn, or an alloy thereof.
  • the meltable filler may optionally further comprise Ag, Au, Cd, Cu, Pb, Sb, Zn, or a combination thereof.
  • suitable meltable fillers include Ga, In-Bi-Sn alloys, Sn-In-Zn alloys, Sn-In-Ag alloys, Sn-Ag-Bi alloys, Sn-Bi-Cu-Ag alloys, Sn- Ag-Cu-Sb alloys, Sn-Ag-Cu alloys, Sn-Ag alloys, Sn-Ag-Cu-Zn alloys, and combinations thereof.
  • the meltable filler may have a melting point ranging from 50 °C to 250 °C, alternatively 150 °C to 225 °C.
  • the meltable filler may be a eutectic alloy, a non-eutectic alloy, or a pure metal.
  • the electrically conductive filler may comprise non- electrically conductive fillers, e.g. inorganic fillers, having an electrically conductive layer disposed about the non-electrically conductive fillers.
  • the electrically conductive layer imparts electrical conductivity to the otherwise non- electrically conductive filler.
  • the shape and size of the electrically conductive filler is not specifically restricted, however, rounded or spherical particles may prevent viscosity increase to an undesirable level upon high loading of the electrically conductive filler.
  • the thermally conductive filler particles may have a desired aspect ratio for advantageous orientation within the first and/or second electrode layers.
  • the electrically conductive filler may be utilized as a single electrically conductive filler or a combination of two or more electrically conductive fillers that differ in at least one property such as particle shape, average particle size, particle size distribution, and type of filler.
  • the average particle size of the electrically conductive filler will depend on various factors including the type of electrically conductive filler selected and the particular amount utilized. Similarly, the amount of the electrically conductive filler utilized depends on various factors including the cure mechanism selected for the curable composition, if utilized.
  • the curable composition when electrically conductive fillers are utilized in a curable composition, the curable composition may be cured as a potential difference is applied to orient the electrically conductive fillers within the first and/or second electrode layers.
  • the curable composition may be cured as a magnetic field is adjacent to or applied to the curable composition for advantageously orienting the electrically conductive fillers, particularly when such electrically conductive fillers are magnetic, e.g. para-magnetic.
  • Such an applied field may have beneficial results in the first and/or second electrode layers in at least one axis thereof contingent upon an orientation of the electrically conductive fillers therein.
  • the host matrix of the first and/or second electrode layers is formed from a silicone composition.
  • the curable composition referenced above may similarly comprise a silicone composition.
  • silicones are dielectric, conductive fiber(s) and/or electrically conductive additives are incorporated therein, as described above.
  • Various embodiments relating to specific silicone compositions suitable for the instant method are described below.
  • the silicone composition is generally cured, or cross-linked, to form the first and/or second electrode layers.
  • the silicone composition may be independently selected from a peroxide-curable silicone composition, a condensation-curable silicone composition, an epoxy-curable silicone composition, an ultraviolet radiation-curable silicone composition, a high-energy radiation-curable silicone composition, and a hydrosilylation-curable silicone composition.
  • the first and/or second electrode layers may comprise any combination of siloxane units, i.e., the first and/or second electrode layers may comprise any combination of R ⁇ SiC ⁇ units, i.e., M units, R2S1O2/2 units, i.e., D units, RS1O3/2 units, i.e., T units, and S1O 4 /2 units, i.e., Q units, where R is typically a substituted or unsubstituted hydrocarbyl group.
  • the silicone composition utilized to form the first and/or second electrode layers generally comprises at least one polymer including repeating D units, i.e., a linear or branched polymer.
  • the silicone composition utilized to form the first and/or second electrode layers generally includes a silicone resin having T and/or Q units.
  • first and/or second electrode layers is formed from a silicone composition and in which the first and/or second electrode layers has a resinous structure are described below.
  • the hydrosilylation- curable silicone composition comprises a resin (A), a cross-linking agent (B), and a hydro silylation catalyst (C).
  • the silicone resin (A) has silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in each molecule.
  • the silicone resin (A) is typically a copolymer including R3 ⁇ 4i03/2 units, i.e., T units, and/or S1O4/2 units, i.e., Q units, in combination with RlR3 ⁇ 4SiOi /2 units, i.e., M units, and/or R3 ⁇ 4Si02/2 units, i.e., D units, wherein is a Ci to CI Q hydrocarbyl group or a Ci to C I Q halogen-substituted hydrocarbyl group, both free of aliphatic unsaturation, and R2 IS
  • the silicone resin can be a DT resin, an MT resin, an MDT resin, a DTQ resin, an MTQ resin, an MDTQ resin, a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin.
  • free of aliphatic unsaturation means the hydrocarbyl or halo gen- substituted hydrocarbyl group does not contain an aliphatic carbon-carbon double bond or carbon-carbon triple bond.
  • the Ci to C Q hydrocarbyl group and Ci to C Q halogen-substituted hydrocarbyl group represented by R1 more typically have from 1 to 6 carbon atoms.
  • Acyclic hydrocarbyl and halo gen- substituted hydrocarbyl groups containing at least 3 carbon atoms can have a branched or unbranched structure.
  • hydrocarbyl groups represented by R1 include, but are not limited to, alkyl groups, such as methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1- dimethylethyl, pentyl, 1-methylbutyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl, nonyl, and decyl; cycloalkyl groups, such as cyclopentyl, cyclohexyl, and methylcyclohexyl; aryl groups, such as phenyl and naphthyl; alkaryl groups, such as tolyl and xylyl; and aralkyl groups, such as benzyl and phenethyl.
  • alkyl groups such as methyl, e
  • halogen-substituted hydrocarbyl groups represented by R1 include, but are not limited to, 3,3,3- trifluoropropyl, 3-chloropropyl, chlorophenyl, dichlorophenyl, 2,2,2-trifluoroethyl, 2,2,3,3-tetrafluoropropyl, and 2,2,3,3,4,4,5,5-octafluoropentyl.
  • the alkenyl groups represented by R 2 typically have from 2 to 10 carbon atoms, alternatively from 2 to 6 carbon atoms, and are exemplified by, for example, vinyl, allyl, butenyl, hexenyl, and octenyl.
  • R 2 is predominantly the alkenyl group. In this embodiment, typically at least 50 mol , alternatively at least
  • R 2 is predominantly hydrogen.
  • typically at least 50 mol , alternatively at least 65 mol , alternatively at least 80 mol , of the groups represented by R 2 in the silicone resin are hydrogen.
  • the mol of hydrogen in R2 is defined as a ratio of the number of moles of silicon-bonded hydrogen in the silicone resin to the total number of moles of the R 2 groups in the resin, multiplied by 100.
  • the silicone resin (A) has the formula:
  • the silicone resin represented by formula (I) has an average of at least two silicon-bonded alkenyl groups per molecule. More specifically, the subscript w typically has a value of from 0 to 0.9, alternatively from 0.02 to 0.75, alternatively from 0.05 to 0.3. The subscript x typically has a value of from 0 to 0.9, alternatively from 0 to 0.45, alternatively from 0 to 0.25.
  • the subscript y typically has a value of from 0 to 0.99, alternatively from 0.25 to 0.8, alternatively from 0.5 to 0.8.
  • the subscript z typically has a value of from 0 to 0.85, alternatively from 0 to 0.25, alternatively from 0 to 0.15.
  • the ratio y+z/(w+x+y+z) is typically from 0.1 to 0.99, alternatively from 0.5 to 0.95, alternatively from 0.65 to 0.9.
  • the ratio w+x/(w+x+y+z) is typically from 0.01 to 0.90, alternatively from 0.05 to 0.5, alternatively from 0.1 to 0.35.
  • silicone resins represented by formula (I) above include resins having the following formulae:
  • silicone resins represented by formula (I) above include resins having the following formulae: (HMe 2 SiOi/2)0.25(PhSiO3/ 2 )0.75> (HMeSi0 2 /2)o.3(PhSi03/2)o.6(MeSi03/ 2 )o.l, and (Me3SiOi/2)0. l(H 2 SiO2/2)0.l(MeSiO3/2)0.4(PhSiO3/2)0.4,
  • the silicone resin represented by formula (I) typically has a number- average molecular weight (M n ) of from 500 to 50,000, alternatively from 500 to
  • the viscosity of the silicone resin represented by formula (I) at 25 °C is typically from 0.01 to 100,000 Pa s, alternatively from 0.1 to 10,000 Pa s, alternatively from 1 to 100 Pa- s.
  • the silicone resin represented by formula (I) typically includes less than 10% (w/w), alternatively less than 5% (w/w), alternatively less than 2% (w/w), of silicon-bonded hydroxy groups, as determined by ⁇ Si NMR.
  • the hydrosilylation-curable silicone composition further includes a cross-linking agent (B) having silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups capable of reacting with the silicon-bonded alkenyl groups or silicon- bonded hydrogen atoms in the silicone resin.
  • the cross-linking agent (B) has an average of at least two silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups per molecule, alternatively at least three silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups per molecule per molecule.
  • the silicone resin (A) includes silicon-bonded alkenyl groups and the cross-linking agent (B) includes silicon-bonded hydrogen atoms.
  • Cross -linking occurs when the sum of the average number of alkenyl groups per molecule in the silicone resin (A) and the average number of silicon-bonded hydrogen atoms per molecule in the cross-linking agent (B) is greater than four.
  • the cross- linking agent (B) is present in an amount sufficient to cure the silicone resin (A).
  • the cross-linking agent (B) is typically an organosilicon compound and may be further defined as an organohydrogensilane, an organohydrogensiloxane, or a combination thereof.
  • the structure of the organosilicon compound can be linear, branched, cyclic, or resinous.
  • the silicon- bonded hydrogen atoms can be located at terminal, pendant, or at both terminal and pendant positions.
  • Cyclosilanes and cyclosiloxanes typically have from 3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms.
  • the organohydrogensilane can be a monosilane, disilane, trisilane, or polysilane.
  • specific examples of organohydrogensilanes that are suitable for purposes of the present invention include, but are not limited to, diphenylsilane, 2-chloroethylsilane, bis[(p- dimethylsilyl)phenyl] ether, 1,4-dimethyldisilylethane, 1,3,5- tris(dimethylsilyl)benzene, 1 ,3,5-trimethyl- 1 ,3,5-trisilane, poly(methylsilylene)phenylene, and poly(methylsilylene)methylene.
  • specific examples of organohydrogensilanes that are suitable for purposes of the present invention include, but are not limited to, silanes having the following formulae:
  • the organohydrogensilane can also have the formula:
  • g is from 1 to 6.
  • organohydrogensilanes having the formula (III), wherein R1 and R ⁇ are as described and exemplified above include, but are not limited to, organohydrogensilanes having a formula selected from the following structures:
  • the organohydrogensiloxane can be a disiloxane, trisiloxane, or polysiloxane.
  • organosiloxanes suitable for use as the cross-linking agent can be a disiloxane, trisiloxane, or polysiloxane. Examples of organosiloxanes suitable for use as the cross-linking agent
  • organohydrogensiloxanes that are suitable for purposes of the present invention when R2 is predominantly the alkenyl group include 1 , 1 ,3,3-tetramethyldisiloxane, 1 , 1 ,3,3-tetraphenyldisiloxane, phenyltris(dimethylsiloxy)silane, 1,3,5-trimethylcyclotrisiloxane, a trimethylsiloxy- terminated poly(methylhydrogensiloxane), a trimethylsiloxy- terminated poly(dimethylsiloxane/methylhydrogensiloxane), a dimethylhydrogensiloxy- terminated poly(methylhydrogensiloxane), and a resin including HMe 2 SiOi / 2 units,
  • the organohydrogensiloxane can also be an organohydrogenpolysiloxane resin.
  • the organohydrogenpolysiloxane resin is typically a copolymer including R4si03/ 2 units, i.e., T units, and/or Si04/ 2 units, i.e., Q units, in combination with R!R ⁇ SIO I ⁇ units, i.e., M units, and/or R42SI02/2 units, i.e., D units, wherein R1 is as described and exemplified above.
  • the organohydrogenpolysiloxane resin can be a DT resin, an MT resin, an MDT resin, a DTQ resin, an MTQ resin, an MDTQ resin, a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin.
  • the group represented by R ⁇ is either R1 or an organosilylalkyl group having at least one silicon-bonded hydrogen atom.
  • organosilylalkyl groups represented by R ⁇ include, but are not limited to, groups having a formula selected from the following structures:
  • organohydrogenpolysiloxane resin typically has the formula:
  • organohydrogenpolysiloxane resins represent by formula (IV) above include, but are not limited to, resins having the following formulae:
  • Me is methyl
  • Ph is phenyl
  • Cglfy denotes a para-phenylene group
  • the numerical subscripts outside the parenthesis denote mole fractions.
  • organohydrogenpolysiloxane resins include, but are not limited to, resins having the following formulae:
  • the cross-linking agent (B) can be a single organosilicon compound or a mixture comprising two or more different organosilicon compounds, each as described above.
  • the cross-linking agent (B) can be a single organohydrogensilane, a mixture of two different organohydrogensilanes, a single organohydrogensiloxane, a mixture of two different organohydrogensiloxanes, or a mixture of an organohydrogensilane and an organohydrogensiloxane.
  • the cross-linking agent (B) can be a mixture comprising the organohydrogenpolysiloxane resin having the formula (IV) in an amount of at least 0.5% (w/w), alternatively at least 50% (w/w), alternatively at least 75% (w/w), based on the total weight of the cross-linking agent (B), with the cross-linking agent (B) further comprising an organohydrogensilane and/or organohydrogensiloxane, the latter different from the organohydrogenpolysiloxane resin.
  • cross-link the silicone resin (A).
  • the exact amount of cross-linking agent (B) depends on the desired extent of cure.
  • the concentration of cross-linking agent (B) is typically sufficient to provide from 0.4 to 2 moles of silicon-bonded hydrogen atoms, alternatively from 0.8 to 1.5 moles of silicon-bonded hydrogen atoms, alternatively from 0.9 to 1.1 moles of silicon-bonded hydrogen atoms, per mole of alkenyl groups in silicone resin (A)
  • Hydrosilylation catalyst (C) includes at least one hydrosilylation catalyst that promotes the reaction between silicone resin (A) and cross-linking agent (B).
  • the hydrosilylation catalyst (C) can be any of the well-known hydrosilylation catalysts comprising a platinum group metal (i.e., platinum, rhodium, ruthenium, palladium, osmium and iridium) or a compound containing a platinum group metal.
  • the platinum group metal is platinum, based on its high activity in hydrosilylation reactions.
  • hydrosilylation catalysts suitable for (C) include the complexes of chloroplatinic acid and certain vinyl-containing organosiloxanes disclosed by Willing in U.S. Pat. No. 3,419,593, the portions of which address hydrosilylation catalysts are hereby incorporated by reference.
  • a catalyst of this type is the reaction product of chloroplatinic acid and l,3-diethenyl-l,l,3,3-tetramethyldisiloxane.
  • the hydrosilylation catalyst can also be a supported hydrosilylation catalyst comprising a solid support having a platinum group metal on the surface thereof.
  • a supported catalyst can be conveniently separated from the organohydrogenpolysiloxane resin represented by formula (IV), for example, by filtering the reaction mixture.
  • supported catalysts include, but are not limited to, platinum on carbon, palladium on carbon, ruthenium on carbon, rhodium on carbon, platinum on silica, palladium on silica, platinum on alumina, palladium on alumina, and ruthenium on alumina.
  • the hydrosilylation catalyst (C) can also be a microencapsulated platinum group metal-containing catalyst comprising a platinum group metal encapsulated in a thermoplastic resin.
  • Hydrosilylation-curable silicone compositions including microencapsulated hydrosilylation catalysts are stable for extended periods of time, typically several months or longer, under ambient conditions, yet cure relatively rapidly at temperatures above the melting or softening point of the thermoplastic resin(s).
  • Microencapsulated hydrosilylation catalysts and methods of preparing them are well known in the art, as exemplified in U.S. Pat. No. 4,766,176 and the references cited therein, and U.S. Pat. No. 5,017,654.
  • the hydrosilylation catalyst (C) can be a single catalyst or a mixture comprising two or more different catalysts that differ in at least one property, such as structure, form, platinum group metal, complexing ligand, and thermoplastic resin.
  • the hydrosilylation catalyst (C) may be at least one photoactivated hydrosilylation catalyst.
  • the photoactivated hydrosilylation catalyst can be any hydrosilylation catalyst capable of catalyzing the hydrosilylation of the silicone resin (A) and the cross-linking agent (B) upon exposure to radiation having a wavelength of from 150 to 800 nm.
  • the photoactivated hydrosilylation catalyst can be any of the well-known hydrosilylation catalysts comprising a platinum group metal or a compound containing a platinum group metal.
  • the platinum group metals include platinum, rhodium, ruthenium, palladium, osmium, and iridium. Typically, the platinum group metal is platinum, based on its high activity in hydrosilylation reactions.
  • the suitability of particular photoactivated hydrosilylation catalysts for use in the silicone composition of the present invention can be readily determined by routine experimentation.
  • photoactivated hydrosilylation catalysts suitable for purposes of the present invention include, but are not limited to, platinum(II) ⁇ - diketonate complexes such as platinum(II) bis(2,4-pentanedioate), platinum(II) bis(2,4-hexanedioate), platinum(II) bis(2,4-heptanedioate), platinum(II) bis(l-phenyl- 1,3-butanedioate, platinum(II) bis(l,3-diphenyl-l,3-propanedioate), platinum(II) bis( 1,1,1 ,5,5,5-hexafluoro-2,4-pentanedioate); ⁇ -cyclopentadienyl)trialkylplatinum complexes, such as (Cp)trimethylplatinum, (Cp)ethyldimethylplatinum, (Cp)triethylplatinum,
  • ⁇ -diolefin)(o-aryl)platinum complexes such as ( ⁇ -1,5- cyclooctadienyl)diphenylplatinum, ⁇ - 1 ,3,5,7-cyclooctatetraenyl)diphenylplatinum,
  • the photoactivated hydro silylation catalyst is a Pt(II) D-diketonate complex and more typically the catalyst is platinum(II) bis(2,4-pentanedioate).
  • the hydrosilylation catalyst (C) can be a single photoactivated hydrosilylation catalyst or a mixture comprising two or more different photoactivated hydrosilylation catalysts.
  • the concentration of the hydrosilylation catalyst (C) is sufficient to catalyze the addition reaction of the silicone resin (A) and the cross-linking agent (B).
  • the concentration of the hydrosilylation catalyst (C) is sufficient to provide typically from 0.1 to 1000 ppm of platinum group metal, alternatively from 0.5 to 100 ppm of platinum group metal, alternatively from 1 to 25 ppm of platinum group metal, based on the combined weight of the silicone resin (A) and the cross-linking agent (B).
  • the hydrosilylation-curable silicone composition further includes (D) a silicone rubber having a formula selected from the group of (i)
  • (D)(i) include, but are not limited to, silicone rubbers having the following formulae: ViMe 2 SiO(Me 2 SiO) a SiMe2Vi, ViMe 2 SiO(Ph 2 SiO) a SiMe2Vi, and
  • Silicone rubber (D)(i) can be a single silicone rubber or a mixture comprising two or more different silicone rubbers that each satisfy the formula for (D)(i).
  • silicone rubbers suitable for use as silicone rubber (D)(ii) include, but are not limited to, silicone rubbers having the following formulae:
  • Component (D)(ii) can be a single silicone rubber or a mixture comprising two or more different silicone rubbers that each satisfy the formula for (D)(ii).
  • the mole ratio of silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in the silicone rubber (D) to silicon-bonded alkenyl groups in the silicone resin (A) is typically from 0.01 to 0.5, alternatively from 0.05 to 0.4, alternatively from 0.1 to 0.3.
  • the concentration of the cross- linking agent (B) is such that the ratio of the number of moles of silicon-bonded hydrogen atoms in the cross-linking agent (B) to the sum of the number of moles of silicon-bonded alkenyl groups in the silicone resin (A) and the silicone rubber (D)(i) is typically from 0.4 to 2, alternatively from 0.8 to 1.5, alternatively from 0.9 to 1.1.
  • the concentration of the cross- linking agent (B) is such that the ratio of the sum of the number of moles of silicon- bonded hydrogen atoms in the cross-linking agent (B) and the silicone rubber (D)(ii) to the number of moles of silicon-bonded alkenyl groups in the silicone resin (A) is typically from 0.4 to 2, alternatively from 0.8 to 1.5, alternatively from 0.9 to 1.1.
  • the hydro silylation- curable silicone composition comprises (A ⁇ ) a rubber- modified silicone resin prepared by reacting the silicone resin (A) and at least one silicone rubber (D)(iii) selected from rubbers having the following formulae: R 1 R 2 2SiO(R 2 2SiO)dSiR 2 2R 1 >
  • R 1 and R 5 are as defined and exemplified above and c and d each have a value of from 4 to 1000, alternatively from 10 to 500, alternatively from 10 to 50, in the presence of the hydro silylation catalyst (c) and, optionally, an organic solvent, provided the silicone resin (A) has an average of at least two silicon-bonded alkenyl groups per molecule, the silicone rubber (D)(iii) has an average of at least two silicon- bonded hydrogen atoms per molecule, and the mole ratio of silicon-bonded hydrogen atoms in the silicone rubber (D)(iii) to silicon-bonded alkenyl groups in silicone resin (A) is from 0.01 to 0.5.
  • At least one silicone rubber it is meant that only one of the rubbers represented by the formulae are necessary for (D)(iii), and that combinations of the rubbers represented by the formulae may be used.
  • organic solvent is present, the rubber- modified silicone resin (A ⁇ ) is miscible in the organic solvent and does not form a precipitate or suspension.
  • the hydrosilylation-curable silicone composition of the present invention can comprise additional ingredients, as known in the art.
  • additional ingredients include, but are not limited to, hydrosilylation catalyst inhibitors, such as 3-methyl-3-penten-l-yne, 3,5-dimethyl-3-hexen-l-yne, 3,5- dimethyl- l-hexyn-3-ol, 1-ethynyl- 1-cyclohexanol, 2-phenyl-3-butyn-2-ol, vinylcyclosiloxanes, and triphenylphosphine; adhesion promoters, such as the adhesion promoters taught in U.S. Patent Nos.
  • the first and/or second electrode layers are formed from a condensation-curable silicone composition.
  • the condensation-curable silicone composition typically includes a silicone resin (A ⁇ ) having silicon-bonded hydrogen atoms, silicon-bonded hydroxy groups, and/or silicon-bonded hydrolysable groups, optionally, a cross-linking agent ( ⁇ ) having silicon-bonded hydrolysable groups, and, optionally, a condensation catalyst (C ⁇ ).
  • the condensation curable silicone resin (A ⁇ ) is typically a copolymer comprising RlSi0 3 /2 units, i.e., T units, and/or S1O4/2 units, i.e., Q units, in combination with RIR ⁇ SIOI / ⁇ units, i.e., M units, and/or R62S1O2/2 units, i.e., D units, wherein R1 is set forth above, R ⁇ is R1, - H, -OH, or a hydrolysable group.
  • the silicone resin can be a DT resin, an MT resin, an MDT resin, a DTQ resin, an MTQ resin, an MDTQ resin, a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin.
  • the silicone resin (A ⁇ ) has the formula:
  • R ⁇ and R ⁇ are defined and exemplified above, w' is from 0 to 0.8, alternatively from 0.02 to 0.75, alternatively from 0.05 to 0.3, x' is from 0 to 0.95, alternatively from 0.05 to 0.8, alternatively from 0.1 to 0.3, y' is from 0 to 1, alternatively from 0.25 to 0.8, alternatively from 0.5 to 0.8, and z' is from 0 to 0.99, alternatively from 0.2 to 0.8, alternatively from 0.4 to 0.6.
  • the silicone resin (A ⁇ ) has an average of at least two silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable groups per molecule.
  • hydrolysable group means the silicon-bonded group reacts with water in the absence of a catalyst at any temperature from room temperature (-23 + 2 °C) to 100 °C within several minutes, for example thirty minutes, to form a silanol (Si-OH) group.
  • Examples of hydrolysable groups represented by R ⁇ include, but are not limited to, -CI, -Br, -OR 7 ,
  • the hydrocarbyl and halogen-substituted hydrocarbyl groups represented by R 7 typically have from 1 to 8 carbon atoms, alternatively from 3 to 6 carbon atoms.
  • Acyclic hydrocarbyl and halogen-substituted hydrocarbyl groups containing at least 3 carbon atoms can have a branched or unbranched structure.
  • hydrocarbyl groups represented by include, but are not limited to, unbranched and branched alkyl, such as methyl, ethyl, propyl, 1-methylethyl, butyl, 1- methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 1- ethylpropyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, and octyl; cycloalkyl, such as cyclopentyl, cyclohexyl, and methylcyclohexyl; phenyl; alkaryl, such as tolyl and xylyl; aralkyl, such as benzyl and phenethyl; alkenyl, such as vinyl, allyl, and propenyl; arylalkenyl, such as s
  • the groups in the silicone resin (A 2 ) are hydrogen, hydroxy, or a hydrolysable group.
  • the mol% of groups in is defined as a ratio of the number of moles of silicon-bonded groups in the silicone resin (A 2 ) to the total number of moles of the R6 groups in the silicone resin (A 2 ), multiplied by 100.
  • (A 2 ) include, but are not limited to, cured silicone resins having the following formulae:
  • the silicone resin (A 2 ) represented by formula (V) typically has a number- average molecular weight (M n ) of from 500 to 50,000.
  • the silicone resin (A 2 ) may have a M n of at least 300, alternatively
  • the viscosity of the silicone resin (A 2 ) at 25 °C is typically from 0.01
  • Pa s to solid alternatively from 0.1 to 100,000 Pa s, alternatively from 1 to 1,000 Pa s.
  • the silicone resin (A 2 ) can have the same formula (V) as set forth above, but with different values for the subscripts x and z and with the proviso that the sum of R6S1O3/2 units and S1O4/2 units is greater than zero and with the further proviso that the silicone resin (A 2 ) of the second embodiment contains at least two silicon-bonded hydrogen atoms, at least two silicon-bonded hydroxy groups, or at least two silicon-bonded hydrolysable groups per molecule.
  • x' typically has a value of from 0 to 0.6, alternatively from 0 to 0.45, alternatively from 0 to 0.25
  • z' typically has a value of from 0 to 0.35, alternatively from 0 to 0.25, alternatively from 0 to 0.15
  • the sum of y'+z' is greater than zero and is typically from 0.2 to 0.99, alternatively from 0.5 to 0.95, alternatively from 0.65 to 0.9.
  • the sum of w'+x' can be zero but is typically from 0.01 to 0.80, alternatively from 0.05 to 0.5, alternatively from 0.1 to
  • 1 mol% to 30 mol%, alternatively 1 to 15 mol%, of the groups in the silicone resin (A 2 ) of the second embodiment are hydrogen, hydroxy, or a hydrolysable group.
  • condensation curable silicone resins (A 2 ) of the second embodiment include, but are not limited to, silicone resins having the following formulae: (Me(MeO)Si 2 /2)x'( eSi03/2) y ', (Ph(HO)Si0 2 /2)x'(PhSi03/2) y ',
  • condensation curable silicone resins (A 2 ) of the second embodiment include, but are not limited to, silicone resins having the following formulae:
  • the condensation curable silicone resin (A 2 ) of the second embodiment typically has a number- average molecular weight (M n ) of from
  • condensation curable silicone resin (A) may have a M n of from 500 to 10,000, alternatively 800 to 3,000, where the molecular weight is determined by gel permeation chromatography employing a refractive index detector and silicone resin (MQ) standards.
  • the viscosity of the condensation curable silicone resin (A 2 ) of the second embodiment at 25 °C is typically from 0.01 Pa- s to a solid, alternatively from 0.1 to 10,000 Pa s, alternatively from 1 to 100 Pa s.
  • the condensation curable silicone resin (A) represented by formula (V) typically includes less than 20% (w/w), alternatively less than 10% (w/w), alternatively less than 2% (w/w), of silicon-bonded hydroxy groups, as determined by ⁇ Si NMR.
  • silicone resins (A ⁇ ) represented by formula (V) are well known in the art; many of these resins are commercially available. Silicone resins (A ⁇ ) represented by formula (V) are typically prepared by cohydrolyzing the appropriate mixture of chlorosilane precursors in an organic solvent, such as toluene.
  • a silicone resin including RIR ⁇ SIO I / ⁇ units and R6S1O3/2 units can be prepared by cohydrolyzing a first compound having the formula RIR ⁇ SICI and a second compound having the formula R6S1CI3 in toluene, where R1 and R ⁇ are as defined and exemplified above.
  • the cohydrolyzing process is described above in terms of the hydro silylation-curable silicone composition.
  • the cohydrolyzed reactants can be further "bodied” to a desired extent to control the amount of crosslinkable groups and viscosity.
  • the silicone resins (A ⁇ ) represented by formula (V) can be further treated with a condensation catalyst in an organic solvent to reduce the content of silicon-bonded hydroxy groups.
  • OC(0)CH 3 , -N(CH 3 ) 2 , NHCOCH3, and -SCH3, can be co-hydrolyzed to form the silicone resin (A ⁇ ).
  • the properties of the silicone resin (A ⁇ ) depend on the types of first and second compounds, the mole ratio of first and second compounds, the degree of condensation, and the processing conditions.
  • the Q units in formula (V) can be in the form of discrete particles in the silicone resin (A ⁇ ).
  • the particle size is typically from 1 nm to 20 ⁇ . Examples of these particles include, but are not limited to, silica (S1O4/2) particles of 15 nm in diameter.
  • the condensation-curable silicone composition comprises a rubber-modified silicone resin (A ⁇ ) prepared by reacting an organosilicon compound selected from (i) a silicone resin having the formula (RlR6 2 SiOi/2) w '(R 6 2Si02/2)x'(R 6 Si0 3 /2)y'(Si04/2) z ', ( ⁇ ) hydrolysable precursors of (i), and (iii) a silicone rubber having the formula in the presence of water, (iv) a condensation catalyst, and (v) an organic solvent, wherein R1 and R6 are as defined and exemplified above, R8 is R1 or a hydrolysable group, m is from 2 to 1,000, alternatively from 4 to 500, alternatively from 8 to 400, and w', x', y', and z' are as defined and exemplified above.
  • organosilicon compound selected from (i) a silicone resin having the formula (RlR6 2 SiOi/2) w
  • Silicone resin (i) has an average of at least two silicon-bonded hydroxy or hydrolysable groups per molecule.
  • the silicone rubber (iii) has an average of at least two silicon-bonded hydrolysable groups per molecule.
  • the mole ratio of silicon-bonded hydrolysable groups in the silicone rubber (iii) to silicon-bonded hydroxy or hydrolysable groups in the silicone resin (i) is from 0.01 to 1.5, alternatively from 0.05 to 0.8, alternatively from 0.2 to 0.5.
  • the condensation-curable silicone composition can further comprise the cross-linking agent (B ⁇ ).
  • the cross-linking agent (B ⁇ ) can have the formula R ⁇ qSiX ⁇ q, wherein R ⁇ is C to Cg hydrocarbyl or C to Cg halogen- substituted hydrocarbyl, X is a hydrolysable group, and q is 0 or 1.
  • R ⁇ is C to Cg hydrocarbyl or C to Cg halogen- substituted hydrocarbyl
  • X is a hydrolysable group
  • q is 0 or 1.
  • the hydrocarbyl and halogen-substituted hydrocarbyl groups represented by R ⁇ , and the hydrolysable groups represented by X are as described and exemplified above.
  • cross-linking agents (B ⁇ ) include, but are not limited to, alkoxy silanes such as MeSi(OCH3)3, CH3Si(OCH2CH3)3,
  • CH 2 CHSi(OCH 3 ) 3
  • CH2 CHCH 2 Si(OCH 3 )3, CF 3 CH2CH2Si(OCH 3 ) 3 ,
  • CH 2 CHSi(OCH2CH 2 OCH3)3
  • CH 2 CHCH2Si(OCH2CH 2 OCH3)3
  • CH2 CHSi(OCOCH3)3; organoiminooxysilanes such as CE ⁇ SifO-
  • the cross-linking agent ( ⁇ ⁇ ) can be a single silane or a mixture of two or more different silanes, each as described above. Also, methods of preparing tri- and tetra-functional silanes are well known in the art; many of these silanes are commercially available.
  • the concentration of the cross-linking agent (B ⁇ ) in the condensation-curable silicone composition is sufficient to cure (cross-link) the condensation-curable silicone resin.
  • the exact amount of the cross-linking agent (B ⁇ ) depends on the desired extent of cure, which generally increases as the ratio of the number of moles of silicon-bonded hydrolysable groups in the cross-linking agent
  • the concentration of the cross-linking agent ( ⁇ ⁇ ) is sufficient to provide from 0.2 to 4 moles of silicon- bonded hydrolysable groups per mole of silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable groups in the silicone resin (A ⁇ ).
  • the optimum amount of the cross-linking agent ( ⁇ ⁇ ) can be readily determined by routine experimentation.
  • Condensation catalyst (C ⁇ ) can be any condensation catalyst typically used to promote condensation of silicon-bonded hydroxy (silanol) groups to form Si- O-Si linkages.
  • condensation catalysts include, but are not limited to, amines; and complexes of lead, tin, zinc, and iron with carboxylic acids.
  • the condensation catalyst (C ⁇ ) can be selected from tin(II) and tin(IV) compounds such as tin dilaurate, tin dioctoate, and tetrabutyl tin; and titanium compounds such as titanium tetrabutoxide.
  • the concentration of the condensation catalyst (C ⁇ ) is typically from 0.1 to 10% (w/w), alternatively from 0.5 to 5% (w/w), alternatively from 1 to 3% (w/w), based on the total weight of the silicone resin (A ⁇ ).
  • the condensation-curable silicone composition includes the condensation catalyst (C ⁇ )
  • the condensation-curable silicone composition is typically a two-part composition where the silicone resin (A ⁇ ) and condensation catalyst (C ⁇ ) are in separate parts.
  • the condensation-curable silicone composition of the present invention can comprise additional ingredients, as known in the art and as described above for the hydrosilylation-curable silicone composition.
  • the first and/or second electrode layers are formed from a free radical-curable silicone composition.
  • free radical- curable silicone compositions include peroxide-curable silicone compositions, radiation-curable silicone compositions containing a free radical photoinitiator, and high energy radiation-curable silicone compositions.
  • the free radical- curable silicone composition comprises a silicone resin (A ⁇ ) and, optionally, a cross- linking agent (B ⁇ ) and/or a free radical initiator (C ⁇ ) (e.g., a free radical photoinitiator or organic peroxide).
  • the silicone resin (A ⁇ ) can be any silicone resin that can be cured (i.e., cross-linked) by at least one method selected from (i) exposing the silicone resin to radiation having a wavelength of from 150 to 800 nm in the presence of a free radical photoinitiator, (ii) heating the silicone resin (A ⁇ ) in the presence of an organic peroxide, and (iii) exposing the silicone resin (A ⁇ ) to an electron beam.
  • the silicone resin (A ⁇ ) is typically a copolymer containing T siloxane units and/or Q siloxane units in combination with M and/or D siloxane units.
  • the silicone resin (A ⁇ ) may have the formula
  • R ⁇ alkenyl groups represented by R ⁇ , which may be the same or different, are as defined and exemplified in the description of R2 above.
  • the alkynyl groups represented by R ⁇ typically have from 2 to about 10 carbon atoms, alternatively from 2 to 6 carbon atoms, and are exemplified by, but are not limited to, ethynyl, propynyl, butynyl, hexynyl, and octynyl.
  • the silicone resin (A ⁇ ) typically has a number-average molecular weight (M n ) of at least 300, alternatively from 500 to 10,000, alternatively from 1,000 to 3,000, where the molecular weight is determined by gel permeation chromatography employing a refractive index detector and silicone resin (MQ) standards.
  • M n number-average molecular weight
  • the silicone resin (A ⁇ ) can contain less than 10% (w/w), alternatively less than 5% (w/w), alternatively less than 2% (w/w), of silicon-bonded hydroxy groups, as determined by ⁇ Si NMR.
  • silicone resins (A ⁇ ) that are suitable for purposes of the present invention include, but are not limited to, silicone resins having the following formulae:
  • the free radical-curable silicone composition of the present method can comprise additional ingredients including, but not limited to, silicone rubbers; unsaturated compounds; free radical initiators; organic solvents; UV stabilizers; sensitizers; dyes; flame retardants; antioxidants; fillers, such as reinforcing fillers, extending fillers, and conductive fillers; and adhesion promoters.
  • the free radical-curable silicone composition can further comprise an unsaturated compound selected from (i) at least one organosilicon compound having at least one silicon-bonded alkenyl group per molecule, (ii) at least one organic compound having at least one aliphatic carbon-carbon double bond per molecule, and (iii) mixtures comprising (i) and (ii), wherein the unsaturated compound has a molecular weight less than 500.
  • the unsaturated compound has a molecular weight of less than 400 or less than 300.
  • the unsaturated compound can have a linear, branched, or cyclic structure.
  • the organosilicon compound (i) can be an organosilane or an organosiloxane.
  • the organosilane can be a monosilane, disilane, trisilane, or polysilane.
  • the organosiloxane can be a disiloxane, trisiloxane, or polysiloxane.
  • Cyclosilanes and cyclosiloxanes typically have from 3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms.
  • the silicon-bonded alkenyl group(s) can be located at terminal, pendant, or at both terminal and pendant positions.
  • organosilanes include, but are not limited to, silanes having the following formulae:
  • organosiloxanes include, but are not limited to, siloxanes having the following formulae:
  • the organic compound can be any organic compound containing at least one aliphatic carbon-carbon double bond per molecule, provided the compound does not prevent the silicone resin (A ⁇ ) from curing to form a silicone resin film.
  • the organic compound can be an alkene, a diene, a triene, or a polyene. Further, in acyclic organic compounds, the carbon-carbon double bond(s) can be located at terminal, pendant, or at both terminal and pendant positions.
  • the organic compound can contain one or more functional groups other than the aliphatic carbon-carbon double bond.
  • the organic compound can be in a liquid or solid state at room temperature. Also, the organic compound can be soluble, partially soluble, or insoluble in the free-radical curable silicone composition.
  • the normal boiling point of the organic compound which depends on the molecular weight, structure, and number and nature of functional groups in the compound, can vary over a wide range. Typically, the organic compound has a normal boiling point greater than the cure temperature of the composition. Otherwise, appreciable amounts of the organic compound may be removed by volatilization during cure.
  • organic compounds containing aliphatic carbon-carbon double bonds include, but are not limited to, 1,4-divinylbenzene, 1,3- hexadienylbenzene, and 1,2-diethenylcyclobutane.
  • the unsaturated compound can be a single unsaturated compound or a mixture comprising two or more different unsaturated compounds, each as described above.
  • the unsaturated compound can be a single organosilane, a mixture of two different organosilanes, a single organosiloxane, a mixture of two different organosiloxanes, a mixture of an organosilane and an organosiloxane, a single organic compound, a mixture of two different organic compounds, a mixture of an organosilane and an organic compound, or a mixture of an organosiloxane and an organic compound.
  • the free radical initiator is typically a free radical photoinitiator or an organic peroxide. Further, the free radical photoinitiator can be any free radical photoinitiator capable of initiating cure (cross-linking) of the silicone resin upon exposure to radiation having a wavelength of from 200 to 800 nm.
  • free radical photoinitiators include, but are not limited to, benzophenone; 4,4'-bis(dimethylamino)benzophenone; halogenated benzophenones; acetophenone; D -hydroxyacetophenone; chloro acetophenones, such as dichloroacetophenones and trichloroacetophenones; dialkoxyacetophenones, such as 2,2-diethoxyacetophenone; D -hydoxyalkylphenones, such as 2-hydroxy-2-methyl- l- phenyl- l-propanone and 1-hydroxycyclohexyl phenyl ketone; ⁇ - aminoalkylphenones, such as 2-methyl-4'-(methylthio)-2-morpholiniopropiophenone; benzoin; benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether, and benzoin isobutyl ether; benz
  • the free radical photoinitiator can also be a polysilane, such as the phenylmethylpolysilanes defined by West in U.S. Pat. No. 4,260,780, the disclosure of which as it relates to the phenylmethylpolysilanes is hereby incorporated by reference; the aminated methylpolysilanes defined by Baney et al. in U.S. Pat. No. 4,314,956, the disclosure of which is hereby incorporated by reference as it relates to aminated methylpolysilanes; the methylpolysilanes defined by Peterson et al. in U.S. Pat. No.
  • the free radical photoinitiator can be a single free radical photoinitiator or a mixture comprising two or more different free radical photoinitiators.
  • the concentration of the free radical photoinitiator is typically from 0.1 to 6% (w/w), alternatively from 1 to 3% (w/w), based on the weight of the silicone resin (A ⁇ ).
  • the free radical initiator can also be an organic peroxide.
  • organic peroxides include, diaroyl peroxides such as dibenzoyl peroxide, di-p- chlorobenzoyl peroxide, and bis-2,4-dichlorobenzoyl peroxide; dialkyl peroxides such as di-t-butyl peroxide and 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane; diaralkyl peroxides such as dicumyl peroxide; alkyl aralkyl peroxides such as t-butyl cumyl peroxide and l,4-bis(t-butylperoxyisopropyl)benzene; and alkyl aroyl peroxides such as t-butyl perbenzoate, t-butyl peracetate, and t-butyl peroctoate.
  • the organic peroxide can be a single peroxide or a mixture comprising two or more different organic peroxides.
  • concentration of the organic peroxide is typically from 0.1 to 5% (w/w), alternatively from 0.2 to 2% (w/w), based on the weight of the silicone resin (A ⁇ ).
  • the free radical-curable silicone composition can further comprise at least one organic solvent.
  • the organic solvent can be any aprotic or dipolar aprotic organic solvent that does not react with the silicone resin (A ⁇ ) or additional ingredient(s) and is miscible with the silicone resin (A ⁇ ).
  • organic solvents include, but are not limited to, saturated aliphatic hydrocarbons such as n- pentane, hexane, n-heptane, isooctane and dodecane; cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene; cyclic ethers such as tetrahydrofuran (THF) and dioxane; ketones such as methyl isobutyl ketone (MIBK); halogenated alkanes such as trichloroethane; and halogenated aromatic hydrocarbons such as bromobenzene and chlorobenzene.
  • the organic solvent can be a single organic solvent or a mixture comprising two or more different organic solvents, as described above.
  • the concentration of the organic solvent is typically from 0 to 99%
  • the free-radical curable silicone composition described above contains one or more additional ingredients, for example, a free radical initiator
  • the composition can be a one-part composition comprising the silicone resin and optional ingredient(s) in a single part, or a multi-part composition comprising the components in two or more parts.
  • Another suitable silicone composition suitable for forming the first and/or second electrode layers comprises cyclic dihydrogenpolysiloxanes, which have a weight-average molecular weight ranging in value from 1,500 to 1,000,000, are liquid at room temperature (-23 + 2 °C), and comprise H2S1O2/2 units.
  • the cyclic dihydrogenpolysiloxanes can be produced by subjecting dichlorosilane (H2S1CI2) to hydrolysis/condensation in a mixture of a non-polar organic solvent and water and removing volatile cyclic dihydrogenpolysiloxanes from the formed cyclic dihydrogenpolysiloxanes.
  • the hydrogenpolysiloxanes typically have a weight- average molecular weight ranging in value from 500 to 1,000,000 and are liquid at temperatures of 120 °C or less.
  • the hydrogenpolysiloxanes have the above-mentioned siloxane unit formulas in mole fractions of x'", y'", and z'", which does not imply an arrangement in the order of the above-mentioned siloxane units.
  • siloxane units are arranged randomly in the hydrogenpolysiloxanes, there may be cases in which some block portions are present, but the rest of the units are arranged in a random fashion.
  • [H2S1O2/2] units are always present, there may be linear blocks, but because there are always [HS1O3/2] units and/or [S1O4/2] units, the molecular structure is at least branched and may be network- or cage-like as well, i.e. it could be a resin.
  • the hydrogenpolysiloxanes have [S1O4/2] units, the degree of branching increases even more.
  • the above-mentioned cyclic dihydrogenpolysiloxanes and hydrogenpolysiloxanes may also be cured by high-energy irradiation. Electron beams and X-rays are representative examples of such irradiation. The amount of electron beam irradiation is typically not less than 3 Gry.
  • any of the silicone compositions described above may be modified such that a cured product of the respective silicone composition is a gel or a rubber as opposed to a resin.
  • Such modifications generally relate to replacing the silicone resin of each respective silicone composition with a silicone polymer, i.e., replacing a three dimensional networked resin with a linear or branched polymer.
  • Gels and rubbers are distinguishable from resins in view of the elastic nature and low cross-link density of gels and rubbers, which is attributable to the general absence of T and/or Q units in the cured product. Gels have a much lesser crosslink density than rubbers.
  • the cure mechanisms are generally similar between gels, rubbers, and resins.
  • One example of a gel is disclosed in U.S. Pat. No. 6,031,025, which is incorporated by reference herein in its entirety.
  • the thermally conductive additives of this gel may be utilized or replaced with alternative fillers, or the gel may be free from such fillers.
  • the first and/or second electrode layers may further comprise at least one filler, e.g. a reinforcing and/or extending filler, for improving mechanical properties of the first and/or second electrode layers.
  • the at least one filler may be selected from inorganic fillers in particulate form, such as silica, alumina, calcium carbonate, and mica.
  • the first and/or second electrode layers include silica particles, e.g. silica nanoparticles.
  • silica nanoparticles are fumed silica nanoparticles.
  • Examples of useful commercially available unmodified silica starting materials include nano-sized colloidal silicas available under the product designations NALCO 1040, 1042, 1050, 1060, 2326, 2327, and 2329 colloidal silica from Nalco Chemical Co., Naperville, Illinois, Aerosil® from Degussa, Ludox® from DuPont, Snowtex® from Nissan Chemical, Levasil® from Bayer, or Sylysia® from Fuji Silysia Chemical.
  • Suitable fumed silicas include for example, products commercially available from DeGussa AG, (Hanau, Germany) under the trade designation, "Aerosil series OX 50", as well as product numbers-130,- 150, and-200.
  • Fumed silicas are also commercially available from Cabot Corp., Tuscola, I, under the Bade designations CAB O-SPERSE 2095", “CAB-O-SPERSE A 105", and "CAB-O-SIL M5".
  • Those skilled in the art are aware of different well- established processes to access particles in different sizes, with different physical properties and with different compositions such as flame-hydrolysis (Aerosil- Process), plasma-process, arc -process and hot-wall reactor-process for gas-phase or solid-phase reactions or ionic-exchange processes and precipitation processes for solution-based reactions.
  • the silica nanoparticles may be in the form of a colloidal dispersion.
  • the silica nanoparticles thus may be dispersed in a polar solvent such as methanol, ethanol, isopropyl alcohol (IPA), ketones such as methyl isobutyl ketone, water, acetic acid, diols and trials such as propylene glycol, 2-methyl-l,3-propane diol HOCH 2 CH(CH3)CH 2 OH, 1,2-hexanediol CH3(CH 2 )3CH(OH)CH 2 OH, and glycerol; glycerol esters such as glyceryl triacetate (triacetin), glyceryl tripropionate (tripropionin), and glyceryl tributyrate (tributyrin); and polyglycols such as polyethylene glycols and polypropylene glycols, among which are PPG- 14 butyl ether C4Hc)(OCH(CH3)CH 2 ) 1 40H.
  • a polar solvent such as m
  • the silica nanoparticles can also be dispersed in a non-polar solvent such as toluene, benzene, xylene, etc.
  • a non-polar solvent such as toluene, benzene, xylene, etc.
  • the silica particle size typically ranges from 1 to 1000 nm, or alternatively from 1 to 100 nm, or alternatively from 5 to 30 nm.
  • the silica nanoparticles can be a single type of silica nanoparticles or a mixture comprising at least two different types of silica nanoparticles.
  • silica nanoparticles may be of pure silicon dioxide, or they may contain a certain amount of impurities such as AI2O3, ZnO, and/or cations such as Na + , K ++ , Ca ++ , Mg ++ , etc.
  • the at least one filler need not be a nanoparticle or a silica.
  • the at least one filler is exemplified by reinforcing and/or extending fillers such as, alumina, calcium carbonate (e.g., fumed, ground, and/or precipitated), diatomaceous earth, quartz, silica (e.g., fumed, ground, and/or precipitated), talc, zinc oxide, chopped fiber such as chopped KEVLAR®, or a combination thereof.
  • fillers such as, alumina, calcium carbonate (e.g., fumed, ground, and/or precipitated), diatomaceous earth, quartz, silica (e.g., fumed, ground, and/or precipitated), talc, zinc oxide, chopped fiber such as chopped KEVLAR®, or a combination thereof.
  • the inclusion of certain fillers may pose some adverse reactions with certain silicone compositions (for example, those containing hydrolyzable groups).
  • the at least one filler may optionally be surface treated with a filler treating agent.
  • the at least one filler may be surface treated prior to incorporation into the first and/or second electrode layers or the at least one filler may be surface treated in situ.
  • the amount of the filler treating agent utilized to treat the at least one filler may vary depending on various factors including the type and amounts of fillers utilized and whether the filler is treated with filler treating agent in situ or pretreated before being combined the silicone composition.
  • the filler treating agent may comprise a silane such as an alkoxysilane, an alkoxy-functional oligosiloxane, a cyclic polyorganosiloxane, a hydroxyl- functional oligosiloxane such as a dimethyl siloxane or methyl phenyl siloxane, a stearate, or a fatty acid.
  • a silane such as an alkoxysilane, an alkoxy-functional oligosiloxane, a cyclic polyorganosiloxane, a hydroxyl- functional oligosiloxane such as a dimethyl siloxane or methyl phenyl siloxane, a stearate, or a fatty acid.
  • Alkoxysilane filler treating agents are exemplified by, for example, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, phenyltrimethoxysilane, phenylethyltrimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and a combination thereof.
  • Alkoxy-functional oligosiloxanes can also be used as filler treating agents.
  • Alkoxy-functional oligosiloxanes and methods for their preparation are known in the art.
  • suitable alkoxy-functional oligosiloxanes include those of the formula In this formula, subscript q' is
  • Each RIO can be independently selected from saturated and unsaturated monovalent hydrocarbon groups of 1 to 10 carbon atoms.
  • Each RH can be a saturated or unsaturated monovalent hydrocarbon group having at least 11 carbon atoms.
  • Each R 12 can be an alkyl group.
  • silazanes may be utilized as the filler treating agent, either discretely or in combination with, for example, alkoxysilanes.
  • the filler treating agent can be any of the organosilicon compounds typically used to treat silica fillers.
  • the first and/or second electrode layers may independently comprise any combination of conductive fibers, foamed articles, electrically conductive additives, and fillers, contingent on the desired physical properties of the first and/or second electrode layers.
  • the load of each of these components within the first and/or second electrode layers in contingent on numerous factors, e.g. whether the first and/or second electrode layers are formed from the silicone composition, the presence or absence of other components, and the desired conductive properties of the first and/or second electrode layers.
  • the instant method may be carried out as a batch, semi-batch, or continuous process.
  • the first electrode layer, the electroactive layer, and the second electrode layer are sequentially formed, i.e., the electroactive layer is formed on the first electrode layer, and then the second electrode layer is formed on the electroactive layer.
  • the first electrode layer, the electroactive layer, and/or the second electrode layer are separately formed and assembled or otherwise laminated to form the electroactive article.
  • the instant method is generally referred to as a roll-to-roll or reel-to-reel fabrication method.
  • the first electrode layer and the second electrode layer may be separately formed on release liners.
  • one of the first and/or second electrode layers may be formed on a release liner.
  • the electroactive layer may be formed on a release liner or on the first and/or second electrode layer.
  • the various layers i.e., the first electrode layer, the second electrode layer, and the electroactive layer
  • the electroactive article may be cut into a desired size contingent on the end use of the electroactive article.
  • the electroactive article formed via the instant method may be utilized in diverse applications, particularly those which require conversion between mechanical and electrical energy. Specific examples of such applications or end uses include robotics, pumps, speakers, general automation, disk drives, and prosthetic devices.
  • the first and/or second electrode layers are formed from the silicone composition, and when the first and/or second electrode layers comprise the conductive fiber(s) and/or the electrically conductive additive, the first and/or second electrode layers have excellent physical and mechanical properties, including flexibility and elongation.
  • any ranges and subranges relied upon in describing various embodiments of the present invention independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein.
  • One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present invention, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on.
  • a range "of from 0.1 to 0.9" may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims.
  • a range such as "at least,” “greater than,” “less than,” “no more than,” and the like, it is to be understood that such language includes subranges and/or an upper or lower limit.
  • a range of "at least 10" inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims.
  • an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims.
  • a range "of from 1 to 9" includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1, which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.

Abstract

A method of preparing an electroactive article comprises the step of providing a first electrode layer. The method further comprises the step of forming an electroactive layer adjacent and substantially parallel to the first electrode layer. Finally, the method comprises the step of forming a second electrode layer disposed adjacent and substantially parallel to the electroactive layer, thereby preparing the electroactive article.

Description

METHOD OF PREPARING ELECTROACTIVE ARTICLE
AND ELECTROACTIVE ARTICLE FORMED IN ACCORDANCE THEREWITH
FIELD OF THE INVENTION
[0001] The present invention generally relates to a method of preparing an electroactive article and, more specifically, to a method of preparing an electroactive article having excellent mechanical properties and to the electroactive article formed in accordance therewith.
DESCRIPTION OF THE RELATED ART
[0002] Electroactive polymers are known in the art and are characterized by their ability to change in configuration (e.g. size and/or shape) upon application of an electric field. For example, electroactive polymers exhibit a change in configuration when disposed between two electrodes and when a potential difference is applied between the two electrodes.
[0003] Methods of preparing electroactive articles or devices with electroactive polymers are also known in the art. For example, conventional methods often dispose an electroactive polymer between two layers of metal, which act as electrodes. However, such conventional methods are time consuming, expensive, and limited with respect to output. For example, conventional methods of preparing electroactive articles are generally batch processes and each electroactive article is individually and separately prepared.
SUMMARY OF THE INVENTION AND ADVANTAGES
[0004] The present invention provides a method of preparing an electroactive article. The method comprises the step of providing a first electrode layer. The method further comprises the step of forming an electroactive layer adjacent and substantially parallel to the first electrode layer. Finally, the method comprises the step of forming a second electrode layer disposed adjacent and substantially parallel to the electroactive layer, thereby preparing the electroactive article.
[0005] The present invention also provides the electroactive article formed in accordance with the method. BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Other advantages and aspects of this invention may be described in the following detailed description when considered in connection with the accompanying drawings wherein:
[0007] Figure 1 is a schematic cross-sectional view of one embodiment of an electroactive article.
DETAILED DESCRIPTION OF THE INVENTION
[0008] The present invention provides a method of preparing an electroactive article. The electroactive article has excellent physical properties and is suitable for use in many diverse applications and end uses.
[0009] The method comprises the step of providing a first electrode layer.
The method further comprises forming an electroactive layer adjacent and substantially parallel to the first electrode layer. Finally, the method comprises the step of forming a second electrode layer disposed adjacent and substantially parallel to the electroactive layer, thereby preparing the electroactive article. For example, as illustrated in Figure 1, the first electrode layer 16 and the second electrode layer 12 generally sandwich the electroactive layer 14 in the electroactive article 10. If desired, the electroactive article may include further layers, e.g. the electroactive article may include an additional electroactive layer adjacent either or both of the first and second electrode layers, with additional electrode layers being disposed adjacent any additional electroactive layers.
[0010] As described in greater detail below, the first electrode layer, the electroactive layer, and/or the second electrode layer may be separately formed such that the method comprising combining or assembling the respective layers to prepare the electroactive article, e.g. in a roll-to-roll process.
[0011] In certain embodiments, the electroactive layer is formed from an electroactive polymer. The electroactive polymer utilized to form the electroactive layer may be any polymer having electroactive properties. For example, specific examples of the electroactive polymer include a dielectric electroactive polymer, a ferroelectric polymer, an electrostrictive graft polyol, a liquid crystalline polymer, an ionic electroactive polymer, an electrorheological fluid, an ionic polymer-metal composite, etc. One specific examples of an electroactive layer suitable for the instant method is disclosed in co-pending U.S. Patent Application Ser. No. 61/746,584, which is entitled "ELECTRO ACTIVE ARTICLE INCLUDING MODIFIED ELECTRO ACTIVE LAYER" is incorporated by reference herein in its entirety.
[0012] The first electrode layer may be provided by purchasing or otherwise obtaining the first electrode layer. Alternatively, the first electrode layer may be formed in the instant method. The first and second electrode layers may be the same as or different from one another. To this end, the first and second electrode layers are described collectively below, although it is to be appreciated that the first and second electrode layers may be independently selected from the various embodiments of the first and second electrode layers below.
[0013] The first electrode layer can function as an anode or cathode in the electroactive article, and, similarly, the second electrode layer can function as an anode or cathode in the electroactive article. The first and/or second electrode layers may be transparent or nontransparent to light in the visible region of the electromagnetic spectrum. As used herein, the term "transparent" means the particular layer (e.g., the first and/or second electrode layer) or component has a percent transmittance of at least 30%, alternatively at least 60%, alternatively at least 80%, for light in the visible region (e.g. at a wavelength of from 400 to 700 nm) of the electromagnetic spectrum. Also, as used herein, the term "nontransparent" means the particular layer or component has a percent transmittance less than 30% for light in the visible region of the electromagnetic spectrum.
[0014] Regardless of whether the first electrode layer functions as the anode or the cathode (and thus regardless of whether the second electrode layer functions as the anode or the cathode) in the electroactive article, the first and second electrode layers may independently comprise any material that is electrically conductive. For example, in certain embodiments, the first and/or second electrode layers comprise a metal, alloy, or metal oxide. Specific examples of such materials include as indium oxide, tin oxide, zinc oxide, indium tin oxide (ITO), indium zinc oxide, antimony tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, nickel, gold, steel, titanium, covar, invar, tantalum, brass, niobium, carbon nanotubes, graphite, and combinations thereof or composites thereof.
[0015] The first electrode layer may alternatively or further comprise any other alloy or composite, such as Mg-Al, Ag-Mg, Al-Li, In-Mg, and Al-Ca. Alternatively still, the first and/or second electrode layers may be formed from an electrically conductive polymer or from a composition including an electrically conductive additive, e.g. a filler, which forms a cured product that is electrically conductive. As described in greater detail below, when a composition is utilized to form the first and/or second electrode layers, the composition may be cured to form an elastomer, a foam, a gel, a rubber, a resin, etc. so long as the cured product is electrically conductive.
[0016] In certain embodiments, the first electrode layer may be provided or formed on a substrate. For example, the first electrode layer may be provided or formed on a release liner, and the release liner may be removed or separately from the electroactive article after its formation or the release liner may be removed or separated from the first electrode layer prior to or during the preparation of the electroactive article. Alternatively, the first electrode layer may be physically and/or chemically bonded or adhered to the substrate, e.g. the release liner, such that the first electrode layer is bonded to the substrate even after the electroactive article is formed via the instant method.
[0017] In various alternative embodiments including the substrate, the substrate may comprise a rigid or flexible material. Examples of suitable materials that may be used to form the substrate include, but are not limited to, quartz; fused quartz; aluminum oxide; ceramics; glass; polyolefins such as polyethylene, polypropylene, polystyrene, and polyethyleneterephthalate; fluorocarbon polymers such as polytetrafluoroethylene and polyvinylfluoride; polyamides such as Nylon; polyimides; polyesters such as poly(methyl methacrylate), poly(ethylene 2,6- naphthalenedicarboxylate), and polyethylene terephthalate; epoxy resins; polyethers; polycarbonates; polysulfones; and polyether sulfones.
[0018] The presence of absence of the substrate is generally determined based on, among other factors, the rigidity of the first electrode layer as well as whether the first electrode layer is formed or otherwise provided. For example, when the first electrode layer is sufficiently rigid, e.g. a metal or alloy sheet or foil, the first electrode layer may be utilized as the substrate for the formation of the electroactive layer thereon. Alternatively, the substrate may be utilized even when the first electrode layer comprises a metal or alloy sheet or foil. For example, in certain embodiments, the first electrode layer has a thickness that does not provide for amble rigidity for forming the electroactive layer thereon without further support from the substrate. Further, when the first electrode layer is formed in the instant method, the first electrode layer is generally formed on the substrate, although the first electrode layer may optionally be removed or separated from the substrate prior to forming the electroactive layer on the first electrode layer.
[0019] In certain embodiments, the first and/or second electrode layers may be formed via a deposition apparatus. The deposition apparatus comprises a physical vapor deposition apparatus. In these embodiments, the deposition apparatus is typically selected from a sputtering apparatus, an atomic layer deposition apparatus, and a DC magnetron sputtering apparatus. The sputtering apparatus may be, for example, an ion-beam sputtering apparatus, a reactive sputtering apparatus, an ion- assisted sputtering apparatus, etc. For example, in certain embodiments, the second electrode layer may be formed on the electroactive layer via the deposition apparatus.
[0020] In certain embodiments, the first and/or second electrode layers have electrical conductivity attributable to at least one conductive fiber. The conductive fiber(s) may be embedded in a host matrix, e.g. any polymeric, cellular, and/or elastomeric matrix. The host matrix may be, but is not required to be, electrically conductive. However, when the host matrix is utilized, the conductive fiber(s) is generally present at opposing major surfaces of the first and/or second electrodes for transferring an electrical current therebetween. In certain embodiments, the host matrix is formed from a silicone composition.
[0021] When the first and/or second electrode layers comprise the conductive fiber(s), the conductive fiber(s) may comprise a plurality of conductive fibers, alternatively a single conductive fiber. The conductive fiber(s) of the first and/or second electrode layers may be woven or nonwoven. The conductive fiber(s) may be made from a single material, alternatively from a blend of two or more different materials. The blend of materials may be homogenous, alternatively heterogeneous. Moreover, the conductive fiber(s) may comprise combinations and/or composites of certain materials. For example, different conductive fibers within the first and/or second electrode layers may independently comprise different materials. Further, when a single conductive fiber is employed in the first and/or second electrode layers, the single conductive fiber may vary in its composition. [0022] The conductive fiber(s) of the first and/or second electrode layers may independently be porous or non-porous, optionally having one or more porous or non- porous coatings.
[0023] As introduced above, the conductive fiber(s) of the first and/or second electrode layers may be woven, nonwoven, or combinations thereof. For example, when the conductive fiber(s) of the first and/or second electrode layers are woven, the conductive fiber(s) of the first and/or second electrode layers may be interlaced with one another such that certain conductive fiber(s) (or portions of conductive fiber(s)) are substantially parallel with one another (or with another portion of the same conductive fiber) and certain conductive fiber(s) (or portions of conductive fiber(s)) are substantially perpendicular to one another (or to another portion of the same conductive fiber). Alternatively, the angles between certain conductive fiber(s) may be other than perpendicular, e.g. acute and/or obtuse. Accordingly, when the conductive fiber(s) of the first and/or second electrode layers are woven, the conductive fiber(s) generally have a defined pattern. Typically, such woven conductive fiber(s) are referred to as a cloth. Alternatively, when the conductive fiber(s) of the first and/or second electrode layers are nonwoven, the conductive fiber(s) of the first and/or second electrode layers are generally entangled with one another such that the first and/or second electrode layers includes a web of conductive fiber(s) that are bonded together mechanically, thermally, and/or chemically without a defined pattern. Adjacent conductive fibers that are in contact with one another may be fused to one another (e.g. at their nodes), alternatively in contact with one another but not fused or otherwise bonded to one another, or combinations thereof. Generally, such non-woven conductive fibers are referred to as a mat or a roving. Alternatively still, the conductive fiber(s) may be loose and individual conductive fiber(s) that are not bonded together mechanically, thermally, and/or chemically.
[0024] The conductive fiber(s) may also be characterized by features including shape, dimension, surface area, surface roughness, construction, etc. One or more of these features may be uniform or non-uniform. The dimensions of the conductive fiber(s), particularly a thickness of the conductive fiber(s), are generally selected based on a desired physical property of the first and/or second electrode layers. For example, in certain embodiments, the first and/or second electrode layers are sufficiently thin such that the electroactive article is flexible, in which case the conductive fiber(s) generally have a comparatively small thickness. Alternatively still, the conductive fiber(s) may comprise nanofibers having at least one dimension of less than about 100 nanometers (nm). Generally, this dimension refers to a greatest dimension perpendicular to a length of the conductive fiber(s).
[0025] The conductive fiber(s) may independently have a cross-sectional shape that is elliptical, spherical, square, rectangular, or other various shapes. The conductive fiber construction in cross-section may be mono-component, alternatively multi-component. The multi-component fibers may be bicomponent, alternatively 3- component or more. The bicomponent fibers may have a cross-section that is sheath- core, matrix-fibril, islands-in-the-sea, or side-by-side.
[0026] The conductive fiber(s) may optionally be heat-treated prior to use to remove any organic or other contaminants. For example, the conductive fiber(s) may be heated in air at an elevated temperature, for example, 575 °C, for a suitable period of time, for example 2 hours.
[0027] The composition of the conductive fiber(s) is generally selected based on the desired physical properties of the first and/or second electrode layers and may comprise any conductive material that may be utilized to form conductive fiber(s). Moreover, the conductive fiber(s) may comprise a non-conductive material in addition to a conductive material. For example, natural or synthetic fibers which are non-conductive may be impregnated or coated with a conductive material, e.g. a carbon or metal-based material, to impart the natural or synthetic fiber(s) with electrical conductivity. Alternatively, the conductive fiber(s) may be wholly conductive, i.e., the conductive fiber(s) may be free from non-conductive material.
[0028] The conductive fiber(s) of the first and/or second electrode layers may be formed via known methods, e.g. the conductive fiber(s) may be purchased or otherwise obtained or may be formed, for example, from spinning. In certain embodiments, the conductive fiber(s) may be spun via dry spinning, melt spinning, extrusion spinning, direct spinning, gel spinning, electrospinning, and/or drawing.
[0029] The conductive fiber(s) may be utilized to form the first and/or second electrode layers in various methods.
[0030] In various embodiments when the first electrode layer comprises the conductive fiber(s), the conductive fiber(s) may be formed or otherwise disposed on the substrate (e.g. the release liner) to provide the first electrode layer. When the fist electrode layer comprises the host matrix, the conductive fiber(s) may be embedded or otherwise incorporated into a film or composition which is utilized to form the host matrix. For example, when the host matrix is utilized and is formed from the silicone composition, the silicone composition may be disposed on a substrate to form a silicone film, and the conductive fiber(s) may be disposed, incorporated, or otherwise embedded in the silicone film. Alternatively still, the conductive fiber(s) may have sufficient rigidity such that no substrate is required (with our without the host matrix). Various embodiments of forming the first electrode layer with the conductive fiber(s) are described in greater detail below.
[0031] In various embodiments when the second electrode layer comprises the conductive fiber(s), the conductive fiber(s) may be formed or otherwise disposed on the electroactive layer to form the second electrode layer. Depending on the particular electroactive layer utilized, the electroactive layer may be in an uncured or cured state prior to forming or disposing the conductive fiber(s) thereon to form the second electrode layer. As one example, the conductive fiber(s) may be electrospun directly onto the electroactive layer to form the second electrode layer on the electroactive layer, i.e., the electroactive layer may act as the substrate or wafer for the electrospinning process. Alternatively, the conductive fiber(s) may be electrospun onto a surrogate wafer and subsequently transferred or disposed on the electroactive layer. Alternatively still, the conductive fiber(s) may be formed or obtained from methods other then electrospinning, such as when the conductive fiber(s) are woven, in which case the conductive fiber(s) may be disposed on the electroactive layer in any manner to form the second electrode layer. When the second electrode layer comprises the host matrix, the conductive fiber(s) may be embedded or otherwise incorporated into a film or composition which is utilized to form the host matrix. Various embodiments of forming the second electrode layer with the conductive fiber(s) are described in greater detail below.
[0032] For example, in certain embodiments in which the first and/or second electrode layers include the host matrix, and when the host matrix is formed from the silicone composition, the conductive fiber(s) may be impregnated with the silicone composition, as introduced above. The conductive fiber(s) may be impregnated with the silicone composition using a variety of methods. [0033] For example, with respect to the first electrode layer, the silicone composition may be applied to the release liner or other substrate to form a silicone film. The silicone composition can be applied to the release liner using conventional coating techniques, such as spin coating, dipping, spraying, brushing, or screen- printing. The silicone composition is typically applied to the release liner in an amount sufficient to embed the conductive fiber(s) therein. The release liner may optionally have a corrugated surface to impart the first electrode layer with a particular surface roughness or corrugation. Further, the release liner may be coated or uncoated, and may include conductive fiber(s), fillers, or other additives thereon which may be imparted into the surface of the first electrode layer once separated from the release liner.
[0034] The conductive fiber(s) may be embedded in the silicone film, thereby forming an embedded silicone film. The conductive fiber(s) may be embedded in the silicone film by simply disposing the conductive fiber(s) on the silicone film and allowing the silicone composition to saturate the conductive fiber(s). However, the conductive fiber(s) may be first deposited on the release liner, followed by the application of the silicone composition onto the conductive fiber(s). In another embodiment, when the conductive fiber(s) comprise a woven or nonwoven fabric, the conductive fiber(s) may be impregnated with the silicone composition by passing the conductive fiber(s) through the silicone composition without the use of the release liner. The conductive fiber(s) are typically passed through the silicone composition at a rate of from 1 to 1,000 cm/s at room temperature (-23 + 2 °C). In other embodiments, the conductive fiber(s) are formed by electrospinning. The silicone film may act as the substrate or wafer for the electrospinning process such that the electrospun fibers are deposited directly onto the silicone film to form the first electrode layer. Alternatively, the electrospun fibers may be formed and subsequently disposed in or on the silicone film. While numerous different compositions may be utilized to electrospun conductive fibers, one such example is disclosed in U.S. Patent No. 8,262,980, which is incorporated by reference herein in its entirety.
[0035] The embedded silicone film may be degassed to form a degassed embedded silicone film. The embedded silicone film may be degassed by subjecting it to a vacuum at a temperature of from room temperature (-23 + 2 °C) to 60 °C, for a period of time sufficient to remove entrapped air. For example, the embedded silicone film can typically be degassed by subjecting the embedded silicone film to a pressure of from 1,000 to 20,000 Pa for 5 to 60 minutes at room temperature.
[0036] After degassing, if desired, an additional amount of the silicone composition may be applied to the degassed embedded silicone film to form an impregnated silicone film. The silicone composition can be applied to the degassed embedded silicone film using conventional methods, as described above. Additional and sequential cycles of degassing and application of silicone composition may also be carried out.
[0037] The impregnated silicone film may also be compressed to remove excess silicone composition and/or entrapped air, and to reduce the thickness of the impregnated silicone film. The impregnated silicone film can be compressed using conventional equipment such as a stainless steel roller, hydraulic press, rubber roller, or laminating roll set. The impregnated silicone film is typically compressed at a pressure of from 1,000 Pa to 10 MPa and at a temperature of from room temperature (-23 + 2 °C) to 50 °C.
[0038] Typically, the silicone composition in the impregnated silicone film is cured to form the first electrode layer. The silicone composition may be cured once the respective layers are combined to prepare the electroactive article, or the silicone composition may be cured or partially cured prior to combining the respective layers to prepare the electroactive article. "Cured," as defined herein, means that the silicone composition, which can be in the form of the component parts, a mixture, a solution, or a blend, is exposed to room temperature air, heated at elevated temperatures, or exposed to UV, electron beam, or microwave radiation. Heating can occur using any known conventional means such as by placing the silicone composition or, in this case, the impregnated silicone film, into an air circulating oven. The impregnated silicone film can be heated at atmospheric, sub-atmospheric, or supra- atmospheric pressure. The impregnated silicone film is typically heated at a temperature of from room temperature (-23 + 2 °C) to 250 °C, alternatively from room temperature to 200 °C, alternatively from room temperature to 150 °C, at atmospheric pressure. The impregnated silicone film is heated for a length of time sufficient to cure (cross-link) the silicone composition. For example, the impregnated silicone film is typically heated at a temperature of from 150 to 200 °C for a period of from 0.1 to 3 hours. [0039] Alternatively, impregnated silicone film can be heated in a vacuum at a temperature of from 100 to 200 °C and a pressure of from 1,000 to 20,000 Pa for a time of from 0.5 to 3 hours to form the reinforced silicone film. The impregnated silicone film can be heated in the vacuum using a conventional vacuum bagging process. In a typical process, a bleeder (e.g., polyester) is applied over the impregnated silicone film, a breather (e.g., nylon, polyester) is applied over the bleeder, a vacuum bagging film (e.g., nylon) equipped with a vacuum nozzle is applied over the breather, the assembly is sealed with tape, a vacuum (e.g., 1,000 Pa) is applied to the sealed assembly, and the evacuated bag is heated as described above.
[0040] Alternatively to the methods described above, the silicone composition may be cured to form the host matrix, and then the conductive fiber(s) may be disposed on or embedded in the host matrix to form the first electrode layer.
[0041] When the second electrode layer comprises the host matrix, and when the host matrix is formed from the silicone composition, the second electrode layer may be formed from the same method described above with respect to the first electrode layer. However, instead of the release liner, the silicone composition may be applied to the electroactive layer, which acts as the substrate for forming the second electrode layer thereon. Alternatively, the second electrode layer may be formed on its own substrate or release liner instead of on the electroactive layer. The second electrode layer may be separated or removed from the release liner before or after preparation of the electroactive article.
[0042] Alternatively or in addition to the fiber(s), a foamed article may be utilized in or as the first and/or second electrode layers. The foamed article may be formed from an electrically conductive composition, or the foamed article may be impregnated with or otherwise contain an electrically conductive additive, e.g. an electrically conductive filler, to impart the foamed article with electrical conductivity. Generally, when the foamed article is not electrically conductive in the absence of such electrically conductive additives, the foamed article is open-celled. Specific examples of open-celled foams include polyurethane, polyisocyanurate, polyurea, silicone, etc. Such open-celled foamed articles are known in the art. For example, open-celled foamed articles comprising polyurethane may be formed by reacting an isocyanate and a polyol in the presence of a blowing agent, which may be a chemical and/or a physical plowing agent. [0043] One example of a foam that is electrically conductive is disclosed in
U.S. Patent No. 4,572,917, which is incorporated by reference herein in its entirety.
[0044] When the first and/or second electrode layers comprise an open-celled structure, the first and/or second electrode layers may be formed from the methods described above relating to the conductive fiber(s). For example, the first and/or second electrode layers may be formed in the presence of the electrically conductive additive, or the electrically conductive additive may be introduced into a foamed article to form the first and/or second electrode. For example, a carrier solvent or curable composition comprising the electrically conductive additive may be disposed on or in the foamed article such that the carrier solvent or curable composition fills at least a portion of the open cells of the foamed article. For example, a colloidal suspension comprising the electrically conductive additive may be utilized. The carrier solvent may optionally be volatilized and removed from the first and/or second electrodes, leaving the electrically conductive additives in the open cells of the first and/or second electrode layers. When the curable composition is utilized, the curable composition may be cured such that the cured product including the electrically conductive additive forms a continuous phase through the open cells of the first and/or second electrode layers. Alternatively, the foamed article may be passed through, submerged, or disposed in the carrier solvent or curable composition such that the carrier solvent or curable composition at least partially fills the voids defined by the open cells of the foamed article.
[0045] When the first and/or second electrode layers comprise the foamed article, the foamed article may independently span an entire thickness of the first and/or second electrode layers, respectively. Alternatively, the foamed article may be encapsulated by a host matrix, such as the host matrix described above, in which case the foamed article of the first and/or second electrode layers do not present any open cells at any surface of the first and/or second electrode layers. Alternatively still, the foamed article may be present in the first and/or second electrode layers such that the foamed article is not encapsulated within the first and/or second electrode layers. For example, the first and/or second electrode layers may comprise the foamed article at one or more surfaces of the first and/or second electrode layers, which generally introduces a surface roughness to the first and/or second electrode layers. [0046] Specific examples of electrically conductive fillers suitable for forming the first and/or second electrode layers include aluminum nitride, aluminum oxide, aluminum trihydrate, barium titanate, beryllium oxide, boron nitride, carbon fibers, diamond, graphite, magnesium hydroxide, magnesium oxide, metal particulate, onyx, silicon carbide, tungsten carbide, zinc oxide, and a combination thereof. The electrically conductive filler may comprise a metallic filler, an inorganic filler, a meltable filler, or a combination thereof. Metallic fillers include particles of metals and particles of metals having layers on the surfaces of the particles. These layers may are typically electrically conductive themselves. Suitable metallic fillers are exemplified by particles of metals selected from the group consisting of aluminum, copper, gold, nickel, silver, and combinations thereof, and alternatively aluminum. Suitable metallic fillers are further exemplified by particles of the metals listed above having layers on their surfaces selected from the group consisting of aluminum nitride, aluminum oxide, copper oxide, nickel oxide, silver oxide, and combinations thereof. For example, the metallic filler may comprise aluminum particles having aluminum oxide layers on their surfaces.
[0047] Meltable fillers may comprise Bi, Ga, In, Sn, or an alloy thereof. The meltable filler may optionally further comprise Ag, Au, Cd, Cu, Pb, Sb, Zn, or a combination thereof. Examples of suitable meltable fillers include Ga, In-Bi-Sn alloys, Sn-In-Zn alloys, Sn-In-Ag alloys, Sn-Ag-Bi alloys, Sn-Bi-Cu-Ag alloys, Sn- Ag-Cu-Sb alloys, Sn-Ag-Cu alloys, Sn-Ag alloys, Sn-Ag-Cu-Zn alloys, and combinations thereof. The meltable filler may have a melting point ranging from 50 °C to 250 °C, alternatively 150 °C to 225 °C. The meltable filler may be a eutectic alloy, a non-eutectic alloy, or a pure metal.
[0048] Alternatively, the electrically conductive filler may comprise non- electrically conductive fillers, e.g. inorganic fillers, having an electrically conductive layer disposed about the non-electrically conductive fillers. In such embodiments, the electrically conductive layer imparts electrical conductivity to the otherwise non- electrically conductive filler.
[0049] The shape and size of the electrically conductive filler is not specifically restricted, however, rounded or spherical particles may prevent viscosity increase to an undesirable level upon high loading of the electrically conductive filler. The thermally conductive filler particles may have a desired aspect ratio for advantageous orientation within the first and/or second electrode layers.
[0050] The electrically conductive filler may be utilized as a single electrically conductive filler or a combination of two or more electrically conductive fillers that differ in at least one property such as particle shape, average particle size, particle size distribution, and type of filler.
[0051] The average particle size of the electrically conductive filler will depend on various factors including the type of electrically conductive filler selected and the particular amount utilized. Similarly, the amount of the electrically conductive filler utilized depends on various factors including the cure mechanism selected for the curable composition, if utilized.
[0052] If desired, when electrically conductive fillers are utilized in a curable composition, the curable composition may be cured as a potential difference is applied to orient the electrically conductive fillers within the first and/or second electrode layers. Alternatively or in addition, the curable composition may be cured as a magnetic field is adjacent to or applied to the curable composition for advantageously orienting the electrically conductive fillers, particularly when such electrically conductive fillers are magnetic, e.g. para-magnetic. Such an applied field may have beneficial results in the first and/or second electrode layers in at least one axis thereof contingent upon an orientation of the electrically conductive fillers therein.
[0053] As introduced above, in certain embodiments, the host matrix of the first and/or second electrode layers is formed from a silicone composition. The curable composition referenced above may similarly comprise a silicone composition. Generally, because silicones are dielectric, conductive fiber(s) and/or electrically conductive additives are incorporated therein, as described above. Various embodiments relating to specific silicone compositions suitable for the instant method are described below.
[0054] When the first and/or second electrode layers are formed from the silicone composition, the silicone composition is generally cured, or cross-linked, to form the first and/or second electrode layers. To this end, the silicone composition may be independently selected from a peroxide-curable silicone composition, a condensation-curable silicone composition, an epoxy-curable silicone composition, an ultraviolet radiation-curable silicone composition, a high-energy radiation-curable silicone composition, and a hydrosilylation-curable silicone composition.
[0055] Independent of the particular silicone composition utilized to form the first and/or second electrode layers, the first and/or second electrode layers may comprise any combination of siloxane units, i.e., the first and/or second electrode layers may comprise any combination of R^SiC^ units, i.e., M units, R2S1O2/2 units, i.e., D units, RS1O3/2 units, i.e., T units, and S1O4/2 units, i.e., Q units, where R is typically a substituted or unsubstituted hydrocarbyl group. When the first and/or second electrode layers comprises a rubber or a gel, the silicone composition utilized to form the first and/or second electrode layers generally comprises at least one polymer including repeating D units, i.e., a linear or branched polymer. When the first and/or second electrode layers comprise a resin, the silicone composition utilized to form the first and/or second electrode layers generally includes a silicone resin having T and/or Q units.
[0056] Certain embodiments in which the first and/or second electrode layers is formed from a silicone composition and in which the first and/or second electrode layers has a resinous structure are described below.
[0057] In various embodiments when the first and/or second electrode layers is formed from a hydrosilylation-curable silicone composition, the hydrosilylation- curable silicone composition comprises a resin (A), a cross-linking agent (B), and a hydro silylation catalyst (C). The silicone resin (A) has silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in each molecule. The silicone resin (A) is typically a copolymer including R¾i03/2 units, i.e., T units, and/or S1O4/2 units, i.e., Q units, in combination with RlR¾SiOi /2 units, i.e., M units, and/or R¾Si02/2 units, i.e., D units, wherein is a Ci to CI Q hydrocarbyl group or a Ci to C I Q halogen-substituted hydrocarbyl group, both free of aliphatic unsaturation, and R2 IS
Rl , an alkenyl group, or hydrogen. For example, the silicone resin can be a DT resin, an MT resin, an MDT resin, a DTQ resin, an MTQ resin, an MDTQ resin, a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin. As used herein, the term "free of aliphatic unsaturation" means the hydrocarbyl or halo gen- substituted hydrocarbyl group does not contain an aliphatic carbon-carbon double bond or carbon-carbon triple bond. [0058] The Ci to C Q hydrocarbyl group and Ci to C Q halogen-substituted hydrocarbyl group represented by R1 more typically have from 1 to 6 carbon atoms. Acyclic hydrocarbyl and halo gen- substituted hydrocarbyl groups containing at least 3 carbon atoms can have a branched or unbranched structure. Examples of hydrocarbyl groups represented by R1 include, but are not limited to, alkyl groups, such as methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1- dimethylethyl, pentyl, 1-methylbutyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl, nonyl, and decyl; cycloalkyl groups, such as cyclopentyl, cyclohexyl, and methylcyclohexyl; aryl groups, such as phenyl and naphthyl; alkaryl groups, such as tolyl and xylyl; and aralkyl groups, such as benzyl and phenethyl. Examples of halogen-substituted hydrocarbyl groups represented by R1 include, but are not limited to, 3,3,3- trifluoropropyl, 3-chloropropyl, chlorophenyl, dichlorophenyl, 2,2,2-trifluoroethyl, 2,2,3,3-tetrafluoropropyl, and 2,2,3,3,4,4,5,5-octafluoropentyl.
[0059] The alkenyl groups represented by R2, which may be the same or different within the silicone resin, typically have from 2 to 10 carbon atoms, alternatively from 2 to 6 carbon atoms, and are exemplified by, for example, vinyl, allyl, butenyl, hexenyl, and octenyl. In one embodiment, R2 is predominantly the alkenyl group. In this embodiment, typically at least 50 mol , alternatively at least
65 mol , alternatively at least 80 mol , of the groups represented by R2 in the silicone resin are alkenyl groups. In another embodiment, R2 is predominantly hydrogen. In this embodiment, typically at least 50 mol , alternatively at least 65 mol , alternatively at least 80 mol , of the groups represented by R2 in the silicone resin are hydrogen. The mol of hydrogen in R2 is defined as a ratio of the number of moles of silicon-bonded hydrogen in the silicone resin to the total number of moles of the R2 groups in the resin, multiplied by 100.
[0060] According to a first embodiment, the silicone resin (A) has the formula:
(RlR22Si01/2)w(R22Si02/2)x (R2Si03/2)y(Si04/2)z (I) wherein R1 and R2 are as described and exemplified above and w, x, y, and z are mole fractions. Typically, the silicone resin represented by formula (I) has an average of at least two silicon-bonded alkenyl groups per molecule. More specifically, the subscript w typically has a value of from 0 to 0.9, alternatively from 0.02 to 0.75, alternatively from 0.05 to 0.3. The subscript x typically has a value of from 0 to 0.9, alternatively from 0 to 0.45, alternatively from 0 to 0.25. The subscript y typically has a value of from 0 to 0.99, alternatively from 0.25 to 0.8, alternatively from 0.5 to 0.8. The subscript z typically has a value of from 0 to 0.85, alternatively from 0 to 0.25, alternatively from 0 to 0.15. Also, the ratio y+z/(w+x+y+z) is typically from 0.1 to 0.99, alternatively from 0.5 to 0.95, alternatively from 0.65 to 0.9. Further, the ratio w+x/(w+x+y+z) is typically from 0.01 to 0.90, alternatively from 0.05 to 0.5, alternatively from 0.1 to 0.35.
[0061] When is predominantly the alkenyl group, specific examples of silicone resins represented by formula (I) above include resins having the following formulae:
(Vi2MeSiOi/2)0.25(PhSiO3/2)0.75, ( iMe2SiOi/2)o.25(PhSi03/2)o.75, (ViMe2SiOi/2)0.25(MeSiO3/2)0.25(PhSiO3/2)0.50'
(ViMe2SiO1/2)0.15(PhSiO3/2)0.75(SiO4/2)0. b and (Vi2MeSiO1/2)0.15(ViMe2SiO1/2)0.l(PhSiO3/2)0.75'
wherein Me is methyl, Vi is vinyl, Ph is phenyl, and the numerical subscripts outside the parenthesis denote mole fractions corresponding to either w, x, y, or z as described above for formula (I). The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[0062] When is predominantly hydrogen, specific examples of silicone resins represented by formula (I) above include resins having the following formulae: (HMe2SiOi/2)0.25(PhSiO3/2)0.75> (HMeSi02/2)o.3(PhSi03/2)o.6(MeSi03/2)o.l, and (Me3SiOi/2)0. l(H2SiO2/2)0.l(MeSiO3/2)0.4(PhSiO3/2)0.4,
wherein Me is methyl, Ph is phenyl, and the numerical subscripts outside the parenthesis denote mole fractions. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[0063] The silicone resin represented by formula (I) typically has a number- average molecular weight (Mn) of from 500 to 50,000, alternatively from 500 to
10,000, alternatively 1,000 to 3,000, where the molecular weight is determined by gel permeation chromatography employing a low angle laser light scattering detector, or a refractive index detector and silicone resin (MQ) standards.
[0064] The viscosity of the silicone resin represented by formula (I) at 25 °C is typically from 0.01 to 100,000 Pa s, alternatively from 0.1 to 10,000 Pa s, alternatively from 1 to 100 Pa- s.
[0065] The silicone resin represented by formula (I) typically includes less than 10% (w/w), alternatively less than 5% (w/w), alternatively less than 2% (w/w), of silicon-bonded hydroxy groups, as determined by ^Si NMR.
[0066] The hydrosilylation-curable silicone composition further includes a cross-linking agent (B) having silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups capable of reacting with the silicon-bonded alkenyl groups or silicon- bonded hydrogen atoms in the silicone resin. The cross-linking agent (B) has an average of at least two silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups per molecule, alternatively at least three silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups per molecule per molecule.
[0067] Generally, the silicone resin (A) includes silicon-bonded alkenyl groups and the cross-linking agent (B) includes silicon-bonded hydrogen atoms. Cross -linking occurs when the sum of the average number of alkenyl groups per molecule in the silicone resin (A) and the average number of silicon-bonded hydrogen atoms per molecule in the cross-linking agent (B) is greater than four. The cross- linking agent (B) is present in an amount sufficient to cure the silicone resin (A).
[0068] The cross-linking agent (B) is typically an organosilicon compound and may be further defined as an organohydrogensilane, an organohydrogensiloxane, or a combination thereof. The structure of the organosilicon compound can be linear, branched, cyclic, or resinous. In acyclic polysilanes and polysiloxanes, the silicon- bonded hydrogen atoms can be located at terminal, pendant, or at both terminal and pendant positions. Cyclosilanes and cyclosiloxanes typically have from 3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms.
[0069] The organohydrogensilane can be a monosilane, disilane, trisilane, or polysilane. When is predominantly the alkenyl group, specific examples of organohydrogensilanes that are suitable for purposes of the present invention include, but are not limited to, diphenylsilane, 2-chloroethylsilane, bis[(p- dimethylsilyl)phenyl] ether, 1,4-dimethyldisilylethane, 1,3,5- tris(dimethylsilyl)benzene, 1 ,3,5-trimethyl- 1 ,3,5-trisilane, poly(methylsilylene)phenylene, and poly(methylsilylene)methylene. When is predominantly hydrogen, specific examples of organohydrogensilanes that are suitable for purposes of the present invention include, but are not limited to, silanes having the following formulae:
Vi4Si, PhSiVi3, MeSiVi3, PhMeSiVi2, Ph2SiVi2, and PhSi(CH2CH=CH2)3, wherein Me is methyl, Ph is phenyl, and Vi is vinyl.
[0070] The organohydrogensilane can also have the formula:
HR^Si-RS-SiR^H (III) wherein R1 is as defined and exemplified above and R3 is a hydrocarbylene group free of ali hatic unsaturation having a formula selected from the following structures:
Figure imgf000020_0001
wherein g is from 1 to 6.
[0071] Specific examples of organohydrogensilanes having the formula (III), wherein R1 and R^ are as described and exemplified above include, but are not limited to, organohydrogensilanes having a formula selected from the following structures:
Figure imgf000021_0001
[0072] The organohydrogensiloxane can be a disiloxane, trisiloxane, or polysiloxane. Examples of organosiloxanes suitable for use as the cross-linking agent
(B) when R2 is predominantly hydrogen include, but are not limited to, siloxanes having the following formulae:
PhSi(OSiMe2H)3, Si(OSiMe2H)4, MeSi(OSiMe2H)3, and Ph2Si(OSiMe2H)2, wherein Me is methyl, and Ph is phenyl.
[0073] Specific examples of organohydrogensiloxanes that are suitable for purposes of the present invention when R2 is predominantly the alkenyl group include 1 , 1 ,3,3-tetramethyldisiloxane, 1 , 1 ,3,3-tetraphenyldisiloxane, phenyltris(dimethylsiloxy)silane, 1,3,5-trimethylcyclotrisiloxane, a trimethylsiloxy- terminated poly(methylhydrogensiloxane), a trimethylsiloxy- terminated poly(dimethylsiloxane/methylhydrogensiloxane), a dimethylhydrogensiloxy- terminated poly(methylhydrogensiloxane), and a resin including HMe2SiOi /2 units,
Me3SiOi /2 units, and Si04/2 units, wherein Me is methyl.
[0074] The organohydrogensiloxane can also be an organohydrogenpolysiloxane resin. The organohydrogenpolysiloxane resin is typically a copolymer including R4si03/2 units, i.e., T units, and/or Si04/2 units, i.e., Q units, in combination with R!R^SIO I^ units, i.e., M units, and/or R42SI02/2 units, i.e., D units, wherein R1 is as described and exemplified above. For example, the organohydrogenpolysiloxane resin can be a DT resin, an MT resin, an MDT resin, a DTQ resin, an MTQ resin, an MDTQ resin, a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin.
[0075] The group represented by R^ is either R1 or an organosilylalkyl group having at least one silicon-bonded hydrogen atom. Examples of organosilylalkyl groups represented by R^ include, but are not limited to, groups having a formula selected from the following structures:
Figure imgf000022_0001
-CH2CH2MePhSi- / X -SiPh2H
Figure imgf000022_0002
CH2CH2SiMe2CnH2nSiMe2H, -CH2CH2SiMe2CnH2nSiMePhH,
-CH2CH2SiMePhH, -CH2CH2SiPh2H, -CH2CH2SiMePhCnH2nSiPh2H,
-CH2CH2SiMePhCnH2nSiMe2H, -CH2CH2SiMePhOSiMePhH, and
-CH2CH2SiMePhOSiPh(OSiMePhH)25
wherein Me is methyl, Ph is phenyl, and the subscript n has a value of from 2 to 10. Typically, at least 50 mol%, alternatively at least 65 mol%, alternatively at least 80 mol% of the groups represented by R4 in the organohydrogenpolysiloxane resin are organosilylalkyl groups having at least one silicon-bonded hydrogen atom. As used herein, the mol% of organosilylalkyl groups in R4 is defined as a ratio of the number of moles of silicon-bonded organosilylalkyl groups in the silicone resin to the total number of moles of the R^ groups in the resin, multiplied by 100. [0076] The organohydrogenpolysiloxane resin typically has the formula:
(RlR42SiOi/2)w(R42Si02/2)x(R4Si03/2)y(Si04/2)z (IV) wherein R1, R4 ,w, x, y, and z are each as defined and exemplified above.
[0077] Specific examples of organohydrogenpolysiloxane resins represent by formula (IV) above include, but are not limited to, resins having the following formulae:
((HMe2SiC6H4SiMe2CH2CH2)2MeSiO1/2)0.12(PhSiO3/2)0.88,
((HMe2SiC6H4SiMe2CH2CH2)2MeSiOi/2)0.17(PhSiO3/2)0.835
((HMe2SiC6H4SiMe2CH2CH2)2MeSiOi/2)0.17(MeSiO3/2)0.17(PhSiO3/2)0.665 ((HMe2SiC6H4SiMe2CH2CH2)2MeSiO1/2)0.15(PhSiO3/2)0.75(SiO4/2)0.10' and ((HMe2SiC6H4SiMe2CH2CH2)2MeSiO1/2)0.08((HMe2SiC6H4SiMe2CH2CH2)
Me2SiOi/2)0.06(PhSiO3/2)0.86>
wherein Me is methyl, Ph is phenyl, Cglfy denotes a para-phenylene group, and the numerical subscripts outside the parenthesis denote mole fractions. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[0078] Specific examples of organohydrogenpolysiloxane resins include, but are not limited to, resins having the following formulae:
((HMe2SiC6H4SiMe2CH2CH2)2MeSiOi/2)0.12(PhSiO3/2)0.88,
((HMe2SiC6H4SiMe2CH2CH2)2MeSiO1/2)0.17(PhSiO3/2)0.83'
((HMe2SiC6H4SiMe2CH2CH2)2MeSiO1/2)0.17(MeSiO3/2)0.17(PhSiO3/2)0.66' ((HMe2SiC6H4SiMe2CH2CH2)2MeSiOi/2)0.15(PhSiO3/2)0.75(SiO4/2)0.105 and ((HMe2SiC6H4SiMe2CH2CH2)2MeSiOi/2)0.08((HMe2SiC6H4SiMe2CH2CH2) Me2SiOi /2)0.06(Pn iO3/2)().86' wnere Me is methyl, Ph is phenyl, Cglfy denotes a para-phenylene group, and the numerical subscripts outside the parenthesis denote mole fractions. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[0079] The cross-linking agent (B) can be a single organosilicon compound or a mixture comprising two or more different organosilicon compounds, each as described above. For example, the cross-linking agent (B) can be a single organohydrogensilane, a mixture of two different organohydrogensilanes, a single organohydrogensiloxane, a mixture of two different organohydrogensiloxanes, or a mixture of an organohydrogensilane and an organohydrogensiloxane. In particular, the cross-linking agent (B) can be a mixture comprising the organohydrogenpolysiloxane resin having the formula (IV) in an amount of at least 0.5% (w/w), alternatively at least 50% (w/w), alternatively at least 75% (w/w), based on the total weight of the cross-linking agent (B), with the cross-linking agent (B) further comprising an organohydrogensilane and/or organohydrogensiloxane, the latter different from the organohydrogenpolysiloxane resin.
[0080] The concentration of cross-linking agent (B) is sufficient to cure
(cross-link) the silicone resin (A). The exact amount of cross-linking agent (B) depends on the desired extent of cure. The concentration of cross-linking agent (B) is typically sufficient to provide from 0.4 to 2 moles of silicon-bonded hydrogen atoms, alternatively from 0.8 to 1.5 moles of silicon-bonded hydrogen atoms, alternatively from 0.9 to 1.1 moles of silicon-bonded hydrogen atoms, per mole of alkenyl groups in silicone resin (A)
[0081] Hydrosilylation catalyst (C) includes at least one hydrosilylation catalyst that promotes the reaction between silicone resin (A) and cross-linking agent (B). The hydrosilylation catalyst (C) can be any of the well-known hydrosilylation catalysts comprising a platinum group metal (i.e., platinum, rhodium, ruthenium, palladium, osmium and iridium) or a compound containing a platinum group metal. Typically, the platinum group metal is platinum, based on its high activity in hydrosilylation reactions.
[0001] Specific hydrosilylation catalysts suitable for (C) include the complexes of chloroplatinic acid and certain vinyl-containing organosiloxanes disclosed by Willing in U.S. Pat. No. 3,419,593, the portions of which address hydrosilylation catalysts are hereby incorporated by reference. A catalyst of this type is the reaction product of chloroplatinic acid and l,3-diethenyl-l,l,3,3-tetramethyldisiloxane.
[0002] The hydrosilylation catalyst can also be a supported hydrosilylation catalyst comprising a solid support having a platinum group metal on the surface thereof. A supported catalyst can be conveniently separated from the organohydrogenpolysiloxane resin represented by formula (IV), for example, by filtering the reaction mixture. Examples of supported catalysts include, but are not limited to, platinum on carbon, palladium on carbon, ruthenium on carbon, rhodium on carbon, platinum on silica, palladium on silica, platinum on alumina, palladium on alumina, and ruthenium on alumina.
[0082] In addition or alternatively, the hydrosilylation catalyst (C) can also be a microencapsulated platinum group metal-containing catalyst comprising a platinum group metal encapsulated in a thermoplastic resin. Hydrosilylation-curable silicone compositions including microencapsulated hydrosilylation catalysts are stable for extended periods of time, typically several months or longer, under ambient conditions, yet cure relatively rapidly at temperatures above the melting or softening point of the thermoplastic resin(s). Microencapsulated hydrosilylation catalysts and methods of preparing them are well known in the art, as exemplified in U.S. Pat. No. 4,766,176 and the references cited therein, and U.S. Pat. No. 5,017,654. The hydrosilylation catalyst (C) can be a single catalyst or a mixture comprising two or more different catalysts that differ in at least one property, such as structure, form, platinum group metal, complexing ligand, and thermoplastic resin.
[0083] In another embodiment, the hydrosilylation catalyst (C) may be at least one photoactivated hydrosilylation catalyst. The photoactivated hydrosilylation catalyst can be any hydrosilylation catalyst capable of catalyzing the hydrosilylation of the silicone resin (A) and the cross-linking agent (B) upon exposure to radiation having a wavelength of from 150 to 800 nm. The photoactivated hydrosilylation catalyst can be any of the well-known hydrosilylation catalysts comprising a platinum group metal or a compound containing a platinum group metal. The platinum group metals include platinum, rhodium, ruthenium, palladium, osmium, and iridium. Typically, the platinum group metal is platinum, based on its high activity in hydrosilylation reactions. The suitability of particular photoactivated hydrosilylation catalysts for use in the silicone composition of the present invention can be readily determined by routine experimentation.
[0084] Specific examples of photoactivated hydrosilylation catalysts suitable for purposes of the present invention include, but are not limited to, platinum(II)□ - diketonate complexes such as platinum(II) bis(2,4-pentanedioate), platinum(II) bis(2,4-hexanedioate), platinum(II) bis(2,4-heptanedioate), platinum(II) bis(l-phenyl- 1,3-butanedioate, platinum(II) bis(l,3-diphenyl-l,3-propanedioate), platinum(II) bis( 1,1,1 ,5,5,5-hexafluoro-2,4-pentanedioate); ^-cyclopentadienyl)trialkylplatinum complexes, such as (Cp)trimethylplatinum, (Cp)ethyldimethylplatinum, (Cp)triethylplatinum, (chloro-Cp)trimethylplatinum, and (trimethylsilyl- Cp)trimethylplatinum, where Cp represents cyclopentadienyl; triazene oxide- transition metal complexes, such as
Figure imgf000026_0001
Pt[p-CN-
C6H4NNNOC6Hn]4, Pt[p-H3COC6H4NNNOC6H1 1]4, Pt[p-CH3(CH2)X-
C6H4NNNOCH3]4, l,5-cyclooctadiene.Pt[p-CN-C6H4NNNOC6Hi i ]2, 1,5- cyclooctadiene.Pt[p-CH30-C6H4NNNOCH3]2, [(C6H5)3P]3Rh[p-CN-
C6H4NNNOC6Hi i], and Pd[p-CH3(CH2)X— C6H4NNNOCH3]2, where x is 1, 3, 5,
11, or 17; ^-diolefin)(o-aryl)platinum complexes, such as (η^-1,5- cyclooctadienyl)diphenylplatinum, η^- 1 ,3,5,7-cyclooctatetraenyl)diphenylplatinum,
(r|4-2,5-norboradienyl)diphenylplatinum, (η^- 1 ,5-cyclooctadienyl)bis-(4- dimethylaminophenyl)platinum, (r|4- l,5-cyclooctadienyl)bis-(4- acetylphenyl)platinum, and (r|4-l,5-cyclooctadienyl)bis-(4- trifluormethylphenyl)platinum. Typically, the photoactivated hydro silylation catalyst is a Pt(II) D-diketonate complex and more typically the catalyst is platinum(II) bis(2,4-pentanedioate). The hydrosilylation catalyst (C) can be a single photoactivated hydrosilylation catalyst or a mixture comprising two or more different photoactivated hydrosilylation catalysts.
[0085] The concentration of the hydrosilylation catalyst (C) is sufficient to catalyze the addition reaction of the silicone resin (A) and the cross-linking agent (B). The concentration of the hydrosilylation catalyst (C) is sufficient to provide typically from 0.1 to 1000 ppm of platinum group metal, alternatively from 0.5 to 100 ppm of platinum group metal, alternatively from 1 to 25 ppm of platinum group metal, based on the combined weight of the silicone resin (A) and the cross-linking agent (B).
[0086] Optionally, the hydrosilylation-curable silicone composition further includes (D) a silicone rubber having a formula selected from the group of (i)
R1R2 2SiO(R2 2SiO)aSiR2 2R1 and (ii)
Figure imgf000026_0002
wherein R1 and R2 are as defined and exemplified above, R^ is R1 or -H, subscripts a and b each have a value of from 1 to 4, alternatively from 2 to 4, alternatively from 2 to 3, and w, x, y, and z are also as defined and exemplified above, provided the silicone resin and the silicone rubber (D)(i) each have an average of at least two silicon-bonded alkenyl groups per molecule, the silicone rubber (D)(ii) has an average of at least two silicon- bonded hydrogen atoms per molecule, and the mole ratio of silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in the silicone rubber (D) to silicon-bonded alkenyl groups in the silicone resin (A) is from 0.01 to 0.5.
[0087] Specific examples of silicone rubbers suitable for use as component
(D)(i) include, but are not limited to, silicone rubbers having the following formulae: ViMe2SiO(Me2SiO)aSiMe2Vi, ViMe2SiO(Ph2SiO)aSiMe2Vi, and
ViMe2SiO(PhMeSiO)a SiMe2Vi,
wherein Me is methyl, Ph is phenyl, Vi is vinyl, and the subscript a has a value of from 1 to 4. Silicone rubber (D)(i) can be a single silicone rubber or a mixture comprising two or more different silicone rubbers that each satisfy the formula for (D)(i).
[0088] Specific examples of silicone rubbers suitable for use as silicone rubber (D)(ii) include, but are not limited to, silicone rubbers having the following formulae:
HMe2SiO(Me2SiO)bSiMe2H, HMe2SiO(Ph2SiO)bSiMe2H, HMe2SiO(PhMeSiO)b SiMe2H, and HMe2SiO(Ph2SiO)2(Me2SiO)2SiMe2H,
wherein Me is methyl, Ph is phenyl, and the subscript b has a value of from 1 to 4. Component (D)(ii) can be a single silicone rubber or a mixture comprising two or more different silicone rubbers that each satisfy the formula for (D)(ii).
[0089] The mole ratio of silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in the silicone rubber (D) to silicon-bonded alkenyl groups in the silicone resin (A) is typically from 0.01 to 0.5, alternatively from 0.05 to 0.4, alternatively from 0.1 to 0.3.
[0090] When the silicone rubber (D) is (D)(i), the concentration of the cross- linking agent (B) is such that the ratio of the number of moles of silicon-bonded hydrogen atoms in the cross-linking agent (B) to the sum of the number of moles of silicon-bonded alkenyl groups in the silicone resin (A) and the silicone rubber (D)(i) is typically from 0.4 to 2, alternatively from 0.8 to 1.5, alternatively from 0.9 to 1.1. Furthermore, when the silicone rubber (D) is (D)(ii), the concentration of the cross- linking agent (B) is such that the ratio of the sum of the number of moles of silicon- bonded hydrogen atoms in the cross-linking agent (B) and the silicone rubber (D)(ii) to the number of moles of silicon-bonded alkenyl groups in the silicone resin (A) is typically from 0.4 to 2, alternatively from 0.8 to 1.5, alternatively from 0.9 to 1.1.
[0091] Methods of preparing silicone rubbers containing silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms are well known in the art; many of these compounds are commercially available.
[0092] In another embodiment of the present invention, the hydro silylation- curable silicone composition comprises (A^) a rubber- modified silicone resin prepared by reacting the silicone resin (A) and at least one silicone rubber (D)(iii) selected from rubbers having the following formulae:
Figure imgf000028_0001
R 1 R22SiO(R22SiO)dSiR22R 1 >
wherein R1 and R5 are as defined and exemplified above and c and d each have a value of from 4 to 1000, alternatively from 10 to 500, alternatively from 10 to 50, in the presence of the hydro silylation catalyst (c) and, optionally, an organic solvent, provided the silicone resin (A) has an average of at least two silicon-bonded alkenyl groups per molecule, the silicone rubber (D)(iii) has an average of at least two silicon- bonded hydrogen atoms per molecule, and the mole ratio of silicon-bonded hydrogen atoms in the silicone rubber (D)(iii) to silicon-bonded alkenyl groups in silicone resin (A) is from 0.01 to 0.5. By "at least one silicone rubber", it is meant that only one of the rubbers represented by the formulae are necessary for (D)(iii), and that combinations of the rubbers represented by the formulae may be used. When organic solvent is present, the rubber- modified silicone resin (A^) is miscible in the organic solvent and does not form a precipitate or suspension.
[0093] The hydrosilylation-curable silicone composition of the present invention can comprise additional ingredients, as known in the art. Examples of additional ingredients include, but are not limited to, hydrosilylation catalyst inhibitors, such as 3-methyl-3-penten-l-yne, 3,5-dimethyl-3-hexen-l-yne, 3,5- dimethyl- l-hexyn-3-ol, 1-ethynyl- 1-cyclohexanol, 2-phenyl-3-butyn-2-ol, vinylcyclosiloxanes, and triphenylphosphine; adhesion promoters, such as the adhesion promoters taught in U.S. Patent Nos. 4,087,585 and 5,194,649; dyes; pigments; anti- oxidants; heat stabilizers; UV stabilizers; flame retardants; flow control additives; and diluents, such as organic solvents and reactive diluents. [0094] In other embodiments, the first and/or second electrode layers are formed from a condensation-curable silicone composition. The condensation-curable silicone composition typically includes a silicone resin (A^) having silicon-bonded hydrogen atoms, silicon-bonded hydroxy groups, and/or silicon-bonded hydrolysable groups, optionally, a cross-linking agent (βΐ) having silicon-bonded hydrolysable groups, and, optionally, a condensation catalyst (C^). The condensation curable silicone resin (A^) is typically a copolymer comprising RlSi03/2 units, i.e., T units, and/or S1O4/2 units, i.e., Q units, in combination with RIR^SIOI /^ units, i.e., M units, and/or R62S1O2/2 units, i.e., D units, wherein R1 is set forth above, R^ is R1, - H, -OH, or a hydrolysable group. For example, the silicone resin can be a DT resin, an MT resin, an MDT resin, a DTQ resin, an MTQ resin, an MDTQ resin, a DQ resin, an MQ resin, a DTQ resin, an MTQ resin, or an MDQ resin.
[0095] According to one embodiment, the silicone resin (A^) has the formula:
(RlR62SiOi/2)w'(R62Si02/2)x'(R6Si03/2)y'(Si04/2)z' (V) wherein R^and R^ are defined and exemplified above, w' is from 0 to 0.8, alternatively from 0.02 to 0.75, alternatively from 0.05 to 0.3, x' is from 0 to 0.95, alternatively from 0.05 to 0.8, alternatively from 0.1 to 0.3, y' is from 0 to 1, alternatively from 0.25 to 0.8, alternatively from 0.5 to 0.8, and z' is from 0 to 0.99, alternatively from 0.2 to 0.8, alternatively from 0.4 to 0.6. The silicone resin (A^) has an average of at least two silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable groups per molecule. As used herein the term "hydrolysable group" means the silicon-bonded group reacts with water in the absence of a catalyst at any temperature from room temperature (-23 + 2 °C) to 100 °C within several minutes, for example thirty minutes, to form a silanol (Si-OH) group. Examples of hydrolysable groups represented by R^ include, but are not limited to, -CI, -Br, -OR7,
-OCH2CH2OR7, CH3C(=0)0-, Et(Me)C=N-0-, CH3C(=0)N(CH3)-, and -ONH2, wherein R7 is Ci to Cg hydrocarbyl or Ci to Cg halogen-substituted hydrocarbyl.
[0096] The hydrocarbyl and halogen-substituted hydrocarbyl groups represented by R7 typically have from 1 to 8 carbon atoms, alternatively from 3 to 6 carbon atoms. Acyclic hydrocarbyl and halogen-substituted hydrocarbyl groups containing at least 3 carbon atoms can have a branched or unbranched structure.
Examples of hydrocarbyl groups represented by include, but are not limited to, unbranched and branched alkyl, such as methyl, ethyl, propyl, 1-methylethyl, butyl, 1- methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 1- ethylpropyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, and octyl; cycloalkyl, such as cyclopentyl, cyclohexyl, and methylcyclohexyl; phenyl; alkaryl, such as tolyl and xylyl; aralkyl, such as benzyl and phenethyl; alkenyl, such as vinyl, allyl, and propenyl; arylalkenyl, such as styryl; and alkynyl, such as ethynyl and propynyl. Examples of halogen-substituted hydrocarbyl groups represented by include, but are not limited to, 3,3,3-trifluoropropyl, 3- chloropropyl, chlorophenyl, and dichlorophenyl.
[0097] Typically, at least 1 mol%, alternatively at least 5 mol%, alternatively at least 10 mol% of the groups in the silicone resin (A2) are hydrogen, hydroxy, or a hydrolysable group. As used herein, the mol% of groups in is defined as a ratio of the number of moles of silicon-bonded groups in the silicone resin (A2) to the total number of moles of the R6 groups in the silicone resin (A2), multiplied by 100.
[0098] Specific examples of cured silicone resins formed from silicone resin
(A2) include, but are not limited to, cured silicone resins having the following formulae:
(MeSiO3/2)0.9(Me(HO)SiO2/2)0.1. (PhSiO3/2)0.7(Ph(MeO)SiO2/2)0.3.
(Me3Si01/2)o.8(Si04/2)o.i5(HOSi03/2)o.05,
(MeSiO3/2)0.67(PhSiO3/2)0.23(Ph(HO)SiO2/2)0.b
(MeSiO3/2)0.45(PhSiO3/2)0.24(PhW^
05'
(PhSiO3/2)0.3(Ph(HO)SiO2/2)0.l(MeSiO3/2)0.4(Me(HO)SiO2/2)0.05(PhSiO3/2)0.1 (PhMeSiO2/2)0.05> and
(PhSiO3/2)0.3(Ph(MeO)SiO2/2)0. l(MeSiO3/2)0. l(PhMeSiO2/2)0.55
wherein Me is methyl, Ph is phenyl, the numerical subscripts outside the parenthesis denote mole fractions, and the subscript n has a value such that the silicone resin typically has a number-average molecular weight of from 500 to 50,000. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[0099] As set forth above, the silicone resin (A2) represented by formula (V) typically has a number- average molecular weight (Mn) of from 500 to 50,000.
Alternatively, the silicone resin (A2) may have a Mn of at least 300, alternatively
1,000 to 3,000, where the molecular weight is determined by gel permeation chromatography employing a low angle laser light scattering detector, or a refractive index detector and silicone resin (MQ) standards.
[00100] The viscosity of the silicone resin (A2) at 25 °C is typically from 0.01
Pa s to solid, alternatively from 0.1 to 100,000 Pa s, alternatively from 1 to 1,000 Pa s.
[00101] In a second embodiment, the silicone resin (A2) can have the same formula (V) as set forth above, but with different values for the subscripts x and z and with the proviso that the sum of R6S1O3/2 units and S1O4/2 units is greater than zero and with the further proviso that the silicone resin (A2) of the second embodiment contains at least two silicon-bonded hydrogen atoms, at least two silicon-bonded hydroxy groups, or at least two silicon-bonded hydrolysable groups per molecule.
More specifically, for the silicone resin (A2) of the second embodiment, w', y', R1, and R6 remain the same as set forth above, x' typically has a value of from 0 to 0.6, alternatively from 0 to 0.45, alternatively from 0 to 0.25, z' typically has a value of from 0 to 0.35, alternatively from 0 to 0.25, alternatively from 0 to 0.15, and the sum of y'+z' is greater than zero and is typically from 0.2 to 0.99, alternatively from 0.5 to 0.95, alternatively from 0.65 to 0.9. Further, the sum of w'+x' can be zero but is typically from 0.01 to 0.80, alternatively from 0.05 to 0.5, alternatively from 0.1 to
0.35. Typically, 1 mol% to 30 mol%, alternatively 1 to 15 mol%, of the groups in the silicone resin (A2) of the second embodiment are hydrogen, hydroxy, or a hydrolysable group.
[00102] Examples of condensation curable silicone resins (A2) of the second embodiment include, but are not limited to, silicone resins having the following formulae: (Me(MeO)Si2/2)x'( eSi03/2)y', (Ph(HO)Si02/2)x'(PhSi03/2)y',
(Me3SiOi/2)w'(CH3COOSi03/2)y'(Si04/2)z% (Ph(MeO)Si02/2)x'(MeSi03/2)y'(PhSi03/2)y',
(Ph(MeO)(HO)SiOi/2)w'(MeSi03/2)y'(PhSi03/2)y'(Ph2Si02/2)x'(PhMeSi02/2)x%
(PhMe(MeO)SiOi/2)w'(Ph(HO)Si02/2)x'(MeSi03/2)y'(PhSi03/2)y'(PhMeSi02/2)x% and (Ph(HO)Si02/2)x'(PhSi03/2)y'(MeSi03/2)y'(PhMeSi02/2)x'
wherein Me is methyl, Ph is phenyl, wherein w', x', y', and z' are as defined above, and the subscript y' has a value such that the silicone resin has a number-average molecular weight of from 500 to 50,000. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[00103] Specific examples of condensation curable silicone resins (A2) of the second embodiment include, but are not limited to, silicone resins having the following formulae:
(Me(MeO)Si2/2)0.05(Me3SiOl/2)0.75(Si°4/2)0.2'
(Ph(HO)SiO2/2)0.09(MeSiO3/2)0.67(PhSiO3/2)0.245
(Ph(MeO)SiO2/2)0.05(MeSiO3/2)0.45(PhSiO3/2)0.35(Ph2SiO2/2)0.l(PhMeSiO2/2) 0.05'
(PhMe(MeO)SiO1/2)0.02(PhSiO3/2)0.4(MeSiO3/2)0.45(PhSiO3/2)0.l(PhMeSiO2/2) 0.03' and
(Ph(HO)SiO2/2)0.04(PhMe(MeO)SiOi/2)0.03(PhSiO3/2)0.36(MeSiO3/2)0.l(PhMe SiO2/2)0.47
wherein Me is methyl, Ph is phenyl, and the numerical subscripts outside the parenthesis denote mole fractions. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[00104] As set forth above, the condensation curable silicone resin (A2) of the second embodiment typically has a number- average molecular weight (Mn) of from
500 to 50,000. Alternatively, the condensation curable silicone resin (A) may have a Mn of from 500 to 10,000, alternatively 800 to 3,000, where the molecular weight is determined by gel permeation chromatography employing a refractive index detector and silicone resin (MQ) standards.
[00105] The viscosity of the condensation curable silicone resin (A2) of the second embodiment at 25 °C is typically from 0.01 Pa- s to a solid, alternatively from 0.1 to 10,000 Pa s, alternatively from 1 to 100 Pa s. The condensation curable silicone resin (A) represented by formula (V) typically includes less than 20% (w/w), alternatively less than 10% (w/w), alternatively less than 2% (w/w), of silicon-bonded hydroxy groups, as determined by ^Si NMR.
[00106] Methods of preparing silicone resins (A^) represented by formula (V) are well known in the art; many of these resins are commercially available. Silicone resins (A^) represented by formula (V) are typically prepared by cohydrolyzing the appropriate mixture of chlorosilane precursors in an organic solvent, such as toluene.
For example, a silicone resin including RIR^SIO I /^ units and R6S1O3/2 units can be prepared by cohydrolyzing a first compound having the formula RIR^SICI and a second compound having the formula R6S1CI3 in toluene, where R1 and R^ are as defined and exemplified above. The cohydrolyzing process is described above in terms of the hydro silylation-curable silicone composition. The cohydrolyzed reactants can be further "bodied" to a desired extent to control the amount of crosslinkable groups and viscosity.
[00107] If desired, the silicone resins (A^) represented by formula (V) can be further treated with a condensation catalyst in an organic solvent to reduce the content of silicon-bonded hydroxy groups. Alternatively, first or second compounds containing hydrolysable groups other than chloro groups, such -Br, -I, -OCH3, -
OC(0)CH3, -N(CH3)2, NHCOCH3, and -SCH3, can be co-hydrolyzed to form the silicone resin (A^). The properties of the silicone resin (A^) depend on the types of first and second compounds, the mole ratio of first and second compounds, the degree of condensation, and the processing conditions.
[00108] The Q units in formula (V) can be in the form of discrete particles in the silicone resin (A^). The particle size is typically from 1 nm to 20 μιη. Examples of these particles include, but are not limited to, silica (S1O4/2) particles of 15 nm in diameter.
[00109] In another embodiment, the condensation-curable silicone composition comprises a rubber-modified silicone resin (A^) prepared by reacting an organosilicon compound selected from (i) a silicone resin having the formula (RlR62SiOi/2)w'(R62Si02/2)x'(R6Si03/2)y'(Si04/2)z', (ϋ) hydrolysable precursors of (i), and (iii) a silicone rubber having the formula
Figure imgf000034_0001
in the presence of water, (iv) a condensation catalyst, and (v) an organic solvent, wherein R1 and R6 are as defined and exemplified above, R8 is R1 or a hydrolysable group, m is from 2 to 1,000, alternatively from 4 to 500, alternatively from 8 to 400, and w', x', y', and z' are as defined and exemplified above. Silicone resin (i) has an average of at least two silicon-bonded hydroxy or hydrolysable groups per molecule. The silicone rubber (iii) has an average of at least two silicon-bonded hydrolysable groups per molecule. The mole ratio of silicon-bonded hydrolysable groups in the silicone rubber (iii) to silicon-bonded hydroxy or hydrolysable groups in the silicone resin (i) is from 0.01 to 1.5, alternatively from 0.05 to 0.8, alternatively from 0.2 to 0.5.
[00110] As set forth above, the condensation-curable silicone composition can further comprise the cross-linking agent (B^). The cross-linking agent (B^) can have the formula R^qSiX^q, wherein R^ is C to Cg hydrocarbyl or C to Cg halogen- substituted hydrocarbyl, X is a hydrolysable group, and q is 0 or 1. The hydrocarbyl and halogen-substituted hydrocarbyl groups represented by R^, and the hydrolysable groups represented by X, are as described and exemplified above.
[00111] Specific examples of cross-linking agents (B^) include, but are not limited to, alkoxy silanes such as MeSi(OCH3)3, CH3Si(OCH2CH3)3,
CH3Si(OCH2CH2CH3)3, CH3Si[0(CH2)3CH3]3, CH3CH2Si(OCH2CH3)3,
C6H5Si(OCH3)3, C6H5CH2Si(OCH3)3, C6H5Si(OCH2CH3)3,
CH2=CHSi(OCH3)3, CH2=CHCH2Si(OCH3)3, CF3CH2CH2Si(OCH3)3,
CH3Si(OCH2CH20CH3)3, CF3CH2CH2Si(OCH2CH20CH3)3,
CH2=CHSi(OCH2CH2OCH3)3, CH2=CHCH2Si(OCH2CH2OCH3)3,
C6H5Si(OCH2CH2OCH3)3, Si(OCH3)45 Si(OC2H5)4, and Si(OC3H7)4; organoacetoxysilanes such as CH3Si(OCOCH3)3, CH3CH2Si(OCOCH3)3, and
CH2=CHSi(OCOCH3)3; organoiminooxysilanes such as CE^SifO-
N=C(CH3)CH2CH3]3, Si[0-N=C(CH3)CH2CH3]4, and CH2=CHSi[0-
N=C(CH3)CH2CH3]3; organoacetamidosilanes such as CH3Si[NHC(=0)CH3]3 and C6H5Si[NHC(=0)CH3]3; amino silanes such as CH3Si[NH(s-C4H9)]3 and CH3Si(NHCgHi 1 )3; and organoaminooxysilanes.
[00112] The cross-linking agent (β ΐ) can be a single silane or a mixture of two or more different silanes, each as described above. Also, methods of preparing tri- and tetra-functional silanes are well known in the art; many of these silanes are commercially available.
[00113] When present, the concentration of the cross-linking agent (B ^) in the condensation-curable silicone composition is sufficient to cure (cross-link) the condensation-curable silicone resin. The exact amount of the cross-linking agent (B ^) depends on the desired extent of cure, which generally increases as the ratio of the number of moles of silicon-bonded hydrolysable groups in the cross-linking agent
(βΐ) to the number of moles of silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable groups in the silicone resin (A^) increases. Typically, the concentration of the cross-linking agent (β ΐ) is sufficient to provide from 0.2 to 4 moles of silicon- bonded hydrolysable groups per mole of silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable groups in the silicone resin (A^). The optimum amount of the cross-linking agent (β ΐ) can be readily determined by routine experimentation.
[00114] Condensation catalyst (C^) can be any condensation catalyst typically used to promote condensation of silicon-bonded hydroxy (silanol) groups to form Si- O-Si linkages. Examples of condensation catalysts include, but are not limited to, amines; and complexes of lead, tin, zinc, and iron with carboxylic acids. In particular, the condensation catalyst (C^) can be selected from tin(II) and tin(IV) compounds such as tin dilaurate, tin dioctoate, and tetrabutyl tin; and titanium compounds such as titanium tetrabutoxide.
[00115] When present, the concentration of the condensation catalyst (C^) is typically from 0.1 to 10% (w/w), alternatively from 0.5 to 5% (w/w), alternatively from 1 to 3% (w/w), based on the total weight of the silicone resin (A^).
[00116] When the condensation-curable silicone composition includes the condensation catalyst (C^), the condensation-curable silicone composition is typically a two-part composition where the silicone resin (A^) and condensation catalyst (C^) are in separate parts. [00117] The condensation-curable silicone composition of the present invention can comprise additional ingredients, as known in the art and as described above for the hydrosilylation-curable silicone composition.
[00118] In yet another embodiment, the first and/or second electrode layers are formed from a free radical-curable silicone composition. Examples of free radical- curable silicone compositions include peroxide-curable silicone compositions, radiation-curable silicone compositions containing a free radical photoinitiator, and high energy radiation-curable silicone compositions. Typically, the free radical- curable silicone composition comprises a silicone resin (A^) and, optionally, a cross- linking agent (B^) and/or a free radical initiator (C^ ) (e.g., a free radical photoinitiator or organic peroxide).
[00119] The silicone resin (A^) can be any silicone resin that can be cured (i.e., cross-linked) by at least one method selected from (i) exposing the silicone resin to radiation having a wavelength of from 150 to 800 nm in the presence of a free radical photoinitiator, (ii) heating the silicone resin (A^) in the presence of an organic peroxide, and (iii) exposing the silicone resin (A^) to an electron beam. The silicone resin (A^) is typically a copolymer containing T siloxane units and/or Q siloxane units in combination with M and/or D siloxane units.
[00120] For example, the silicone resin (A^) may have the formula
(R1R92SiOi/2)W"(R92Si02/2)x"(R9Si03/2)y"(Si04/2)z", wherein R1 is as defined and exemplified above, R^ is R1, alkenyl, or alkynyl, w" is from 0 to 0.99, x" is from 0 to 0.99, y" is from 0 to 0.99, z" is from 0 to 0.85, and w"+x"+y"+z" = 1·
[00121] The alkenyl groups represented by R^, which may be the same or different, are as defined and exemplified in the description of R2 above.
[00122] The alkynyl groups represented by R^, which may be the same or different, typically have from 2 to about 10 carbon atoms, alternatively from 2 to 6 carbon atoms, and are exemplified by, but are not limited to, ethynyl, propynyl, butynyl, hexynyl, and octynyl.
[00123] The silicone resin (A^) typically has a number-average molecular weight (Mn) of at least 300, alternatively from 500 to 10,000, alternatively from 1,000 to 3,000, where the molecular weight is determined by gel permeation chromatography employing a refractive index detector and silicone resin (MQ) standards.
[00124] The silicone resin (A^) can contain less than 10% (w/w), alternatively less than 5% (w/w), alternatively less than 2% (w/w), of silicon-bonded hydroxy groups, as determined by ^Si NMR.
[00125] Specific examples of silicone resins (A^) that are suitable for purposes of the present invention include, but are not limited to, silicone resins having the following formulae:
(Vi2MeSiOi/2)0.25(PhSiO3/2)0.75, (ViMe2SiOi/2)o 5(PhSi03/2)o.75, (ViMe2Si01/2)o.25(MeSi03/2)o.25(PhSi03/2)o.505
(ViMe2Si01/2)o.i5(PhSi03/2)o.75 (Si04/2)o.l> and
(Vi2MeSiOi/2)o.l5(ViMe2SiOi/2)o. l(PhSi03/2)o.755
wherein Me is methyl, Vi is vinyl, Ph is phenyl, and the numerical subscripts outside the parenthesis denote mole fractions. The sequence of units in the preceding formulae is not to be viewed in any way as limiting to the scope of the invention.
[00126] The free radical-curable silicone composition of the present method can comprise additional ingredients including, but not limited to, silicone rubbers; unsaturated compounds; free radical initiators; organic solvents; UV stabilizers; sensitizers; dyes; flame retardants; antioxidants; fillers, such as reinforcing fillers, extending fillers, and conductive fillers; and adhesion promoters.
[00127] The free radical-curable silicone composition can further comprise an unsaturated compound selected from (i) at least one organosilicon compound having at least one silicon-bonded alkenyl group per molecule, (ii) at least one organic compound having at least one aliphatic carbon-carbon double bond per molecule, and (iii) mixtures comprising (i) and (ii), wherein the unsaturated compound has a molecular weight less than 500. Alternatively, the unsaturated compound has a molecular weight of less than 400 or less than 300. Also, the unsaturated compound can have a linear, branched, or cyclic structure.
[00128] The organosilicon compound (i) can be an organosilane or an organosiloxane. The organosilane can be a monosilane, disilane, trisilane, or polysilane. Similarly, the organosiloxane can be a disiloxane, trisiloxane, or polysiloxane. Cyclosilanes and cyclosiloxanes typically have from 3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms. In acyclic polysilanes and polysiloxanes, the silicon-bonded alkenyl group(s) can be located at terminal, pendant, or at both terminal and pendant positions.
[00129] Specific examples of organosilanes include, but are not limited to, silanes having the following formulae:
Vi4Si, PhSiVi3, MeSiVi3, PhMeSiVi2, Ph2SiVi2, and PhSi(CH2CH=CH2)3, wherein Me is methyl, Ph is phenyl, and Vi is vinyl.
[00130] Specific examples of organosiloxanes include, but are not limited to, siloxanes having the following formulae:
PhSi(OSiMe2Vi)3, Si(OSiMe2Vi)4, MeSi(OSiMe2Vi)3, and Ph2Si(OSiMe2Vi)2, wherein Me is methyl, Vi is vinyl, and Ph is phenyl.
[00131] The organic compound can be any organic compound containing at least one aliphatic carbon-carbon double bond per molecule, provided the compound does not prevent the silicone resin (A^) from curing to form a silicone resin film. The organic compound can be an alkene, a diene, a triene, or a polyene. Further, in acyclic organic compounds, the carbon-carbon double bond(s) can be located at terminal, pendant, or at both terminal and pendant positions.
[00132] The organic compound can contain one or more functional groups other than the aliphatic carbon-carbon double bond. Examples of suitable functional groups include, but are not limited to, -0-, >C=0, -CHO, -C02-, -C≡N, -N02,
>C=C<, -C≡C-, -F, -CI, -Br, and -I. The suitability of a particular unsaturated organic compound for use in the free-radical curable silicone composition of the present invention can be readily determined by routine experimentation.
[00133] The organic compound can be in a liquid or solid state at room temperature. Also, the organic compound can be soluble, partially soluble, or insoluble in the free-radical curable silicone composition. The normal boiling point of the organic compound, which depends on the molecular weight, structure, and number and nature of functional groups in the compound, can vary over a wide range. Typically, the organic compound has a normal boiling point greater than the cure temperature of the composition. Otherwise, appreciable amounts of the organic compound may be removed by volatilization during cure. [00134] Examples of organic compounds containing aliphatic carbon-carbon double bonds include, but are not limited to, 1,4-divinylbenzene, 1,3- hexadienylbenzene, and 1,2-diethenylcyclobutane.
[00135] The unsaturated compound can be a single unsaturated compound or a mixture comprising two or more different unsaturated compounds, each as described above. For example, the unsaturated compound can be a single organosilane, a mixture of two different organosilanes, a single organosiloxane, a mixture of two different organosiloxanes, a mixture of an organosilane and an organosiloxane, a single organic compound, a mixture of two different organic compounds, a mixture of an organosilane and an organic compound, or a mixture of an organosiloxane and an organic compound.
[00136] The free radical initiator is typically a free radical photoinitiator or an organic peroxide. Further, the free radical photoinitiator can be any free radical photoinitiator capable of initiating cure (cross-linking) of the silicone resin upon exposure to radiation having a wavelength of from 200 to 800 nm.
[00137] Examples of free radical photoinitiators include, but are not limited to, benzophenone; 4,4'-bis(dimethylamino)benzophenone; halogenated benzophenones; acetophenone; D -hydroxyacetophenone; chloro acetophenones, such as dichloroacetophenones and trichloroacetophenones; dialkoxyacetophenones, such as 2,2-diethoxyacetophenone; D -hydoxyalkylphenones, such as 2-hydroxy-2-methyl- l- phenyl- l-propanone and 1-hydroxycyclohexyl phenyl ketone; □- aminoalkylphenones, such as 2-methyl-4'-(methylthio)-2-morpholiniopropiophenone; benzoin; benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether, and benzoin isobutyl ether; benzil ketals, such as 2,2-dimethoxy-2-phenylacetophenone; acylphosphinoxides, such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide; xanthone derivatives; thioxanthone derivatives; fluorenone derivatives; methyl phenyl glyoxylate; acetonaphthone; anthraquinone derivatives; sufonyl chlorides of aromatic compounds; and O-acyl D -oximinoketones, such as 1 -phenyl- l,2-propanedione-2-(O- ethoxycarbonyl)oxime.
[00138] The free radical photoinitiator can also be a polysilane, such as the phenylmethylpolysilanes defined by West in U.S. Pat. No. 4,260,780, the disclosure of which as it relates to the phenylmethylpolysilanes is hereby incorporated by reference; the aminated methylpolysilanes defined by Baney et al. in U.S. Pat. No. 4,314,956, the disclosure of which is hereby incorporated by reference as it relates to aminated methylpolysilanes; the methylpolysilanes defined by Peterson et al. in U.S. Pat. No. 4,276,424, the disclosure of which is hereby incorporated by reference as it relates to methylpolysilanes; and the polysilastyrene defined by West et al. in U.S. Pat. No. 4,324,901, the disclosure of which is hereby incorporated by reference as it relates to polysilastyrene.
[00139] The free radical photoinitiator can be a single free radical photoinitiator or a mixture comprising two or more different free radical photoinitiators. The concentration of the free radical photoinitiator is typically from 0.1 to 6% (w/w), alternatively from 1 to 3% (w/w), based on the weight of the silicone resin (A^).
[00140] The free radical initiator can also be an organic peroxide. Examples of organic peroxides include, diaroyl peroxides such as dibenzoyl peroxide, di-p- chlorobenzoyl peroxide, and bis-2,4-dichlorobenzoyl peroxide; dialkyl peroxides such as di-t-butyl peroxide and 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane; diaralkyl peroxides such as dicumyl peroxide; alkyl aralkyl peroxides such as t-butyl cumyl peroxide and l,4-bis(t-butylperoxyisopropyl)benzene; and alkyl aroyl peroxides such as t-butyl perbenzoate, t-butyl peracetate, and t-butyl peroctoate.
[00141] The organic peroxide can be a single peroxide or a mixture comprising two or more different organic peroxides. The concentration of the organic peroxide is typically from 0.1 to 5% (w/w), alternatively from 0.2 to 2% (w/w), based on the weight of the silicone resin (A^).
[00142] The free radical-curable silicone composition can further comprise at least one organic solvent. The organic solvent can be any aprotic or dipolar aprotic organic solvent that does not react with the silicone resin (A^) or additional ingredient(s) and is miscible with the silicone resin (A^). Examples of organic solvents include, but are not limited to, saturated aliphatic hydrocarbons such as n- pentane, hexane, n-heptane, isooctane and dodecane; cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene; cyclic ethers such as tetrahydrofuran (THF) and dioxane; ketones such as methyl isobutyl ketone (MIBK); halogenated alkanes such as trichloroethane; and halogenated aromatic hydrocarbons such as bromobenzene and chlorobenzene. The organic solvent can be a single organic solvent or a mixture comprising two or more different organic solvents, as described above.
[00143] The concentration of the organic solvent is typically from 0 to 99%
(w/w), alternatively from 30 to 80% (w/w), alternatively from 45 to 60% (w/w), based on the total weight of the free radical-curable silicone composition.
[00144] When the free-radical curable silicone composition described above contains one or more additional ingredients, for example, a free radical initiator, the composition can be a one-part composition comprising the silicone resin and optional ingredient(s) in a single part, or a multi-part composition comprising the components in two or more parts.
[00145] Another suitable silicone composition suitable for forming the first and/or second electrode layers comprises cyclic dihydrogenpolysiloxanes, which have a weight-average molecular weight ranging in value from 1,500 to 1,000,000, are liquid at room temperature (-23 + 2 °C), and comprise H2S1O2/2 units. The cyclic dihydrogenpolysiloxanes can be produced by subjecting dichlorosilane (H2S1CI2) to hydrolysis/condensation in a mixture of a non-polar organic solvent and water and removing volatile cyclic dihydrogenpolysiloxanes from the formed cyclic dihydrogenpolysiloxanes.
[00146] Another suitable silicone composition suitable for forming the first and/or second electrode layers comprises hydrogenpolysiloxanes having a siloxane unit formula of [H2Si02/2]x"'[HSiC>3/2]y'" [SiC>4/2]z'" where x'", y'", and z'" represent mole fractions, 0.12 < x'" < 1.0, 0 < y'" < 0.88, 0 < z'" < 0.30, y'" and z'" are not simultaneously 0, and x'" + y'" + z'" = 1. The hydrogenpolysiloxanes typically have a weight- average molecular weight ranging in value from 500 to 1,000,000 and are liquid at temperatures of 120 °C or less.
[00147] When z'" = 0 in the siloxane unit formula
[H2Si02/2]x"'[HSi03/2]y"'[Si04/2]z"', the hydrogenpolysiloxanes is described by the siloxane unit formula [H2Si02/2]x"'[HSi03/2]y"' wherein x'" and y'" represent mole fractions as set forth above and x'" + y'" = 1. When z'" = 0, typically 0.15 < x'" < 1.0 and 0 < y'" < 0.85.
[00148] When y'" = 0 in the siloxane unit formula
[H2Si02/2]x"'[HSi03/2]y"'[Si04/2]z"', the hydrogenpolysiloxanes is described by the siloxane unit formula [H2Si02/2]x"'[Si04/2]z"' wherein x'" and z'" represent mole fractions as set forth above and x'" + z'" = 1. When y'" = 0, typically 0.15 < x'" <1.0 and 0 < z"' < 0.15.
[00149] On average, the hydrogenpolysiloxanes have the above-mentioned siloxane unit formulas in mole fractions of x'", y'", and z'", which does not imply an arrangement in the order of the above-mentioned siloxane units. When siloxane units are arranged randomly in the hydrogenpolysiloxanes, there may be cases in which some block portions are present, but the rest of the units are arranged in a random fashion. Since [H2S1O2/2] units are always present, there may be linear blocks, but because there are always [HS1O3/2] units and/or [S1O4/2] units, the molecular structure is at least branched and may be network- or cage-like as well, i.e. it could be a resin. When the hydrogenpolysiloxanes have [S1O4/2] units, the degree of branching increases even more.
[00150] The above-mentioned cyclic dihydrogenpolysiloxanes and hydrogenpolysiloxanes may also be cured by high-energy irradiation. Electron beams and X-rays are representative examples of such irradiation. The amount of electron beam irradiation is typically not less than 3 Gry.
[00151] Any of the silicone compositions described above may be modified such that a cured product of the respective silicone composition is a gel or a rubber as opposed to a resin. Such modifications generally relate to replacing the silicone resin of each respective silicone composition with a silicone polymer, i.e., replacing a three dimensional networked resin with a linear or branched polymer. Gels and rubbers are distinguishable from resins in view of the elastic nature and low cross-link density of gels and rubbers, which is attributable to the general absence of T and/or Q units in the cured product. Gels have a much lesser crosslink density than rubbers. However, the cure mechanisms are generally similar between gels, rubbers, and resins. One example of a gel is disclosed in U.S. Pat. No. 6,031,025, which is incorporated by reference herein in its entirety. The thermally conductive additives of this gel may be utilized or replaced with alternative fillers, or the gel may be free from such fillers.
[00152] If desired, in addition to any conductive fiber(s) and/or electrically conductive additive, the first and/or second electrode layers may further comprise at least one filler, e.g. a reinforcing and/or extending filler, for improving mechanical properties of the first and/or second electrode layers.
[00153] The at least one filler may be selected from inorganic fillers in particulate form, such as silica, alumina, calcium carbonate, and mica. In one embodiment, for example, the first and/or second electrode layers include silica particles, e.g. silica nanoparticles. One particularly useful form of silica nanoparticles are fumed silica nanoparticles. Examples of useful commercially available unmodified silica starting materials include nano-sized colloidal silicas available under the product designations NALCO 1040, 1042, 1050, 1060, 2326, 2327, and 2329 colloidal silica from Nalco Chemical Co., Naperville, Illinois, Aerosil® from Degussa, Ludox® from DuPont, Snowtex® from Nissan Chemical, Levasil® from Bayer, or Sylysia® from Fuji Silysia Chemical. Suitable fumed silicas include for example, products commercially available from DeGussa AG, (Hanau, Germany) under the trade designation, "Aerosil series OX 50", as well as product numbers-130,- 150, and-200. Fumed silicas are also commercially available from Cabot Corp., Tuscola, I, under the Bade designations CAB O-SPERSE 2095", "CAB-O-SPERSE A 105", and "CAB-O-SIL M5". Those skilled in the art are aware of different well- established processes to access particles in different sizes, with different physical properties and with different compositions such as flame-hydrolysis (Aerosil- Process), plasma-process, arc -process and hot-wall reactor-process for gas-phase or solid-phase reactions or ionic-exchange processes and precipitation processes for solution-based reactions.
[00154] The silica nanoparticles may be in the form of a colloidal dispersion.
The silica nanoparticles thus may be dispersed in a polar solvent such as methanol, ethanol, isopropyl alcohol (IPA), ketones such as methyl isobutyl ketone, water, acetic acid, diols and trials such as propylene glycol, 2-methyl-l,3-propane diol HOCH2CH(CH3)CH2OH, 1,2-hexanediol CH3(CH2)3CH(OH)CH2OH, and glycerol; glycerol esters such as glyceryl triacetate (triacetin), glyceryl tripropionate (tripropionin), and glyceryl tributyrate (tributyrin); and polyglycols such as polyethylene glycols and polypropylene glycols, among which are PPG- 14 butyl ether C4Hc)(OCH(CH3)CH2)140H. Alternatively, the silica nanoparticles can also be dispersed in a non-polar solvent such as toluene, benzene, xylene, etc. [00155] The silica particle size typically ranges from 1 to 1000 nm, or alternatively from 1 to 100 nm, or alternatively from 5 to 30 nm. The silica nanoparticles can be a single type of silica nanoparticles or a mixture comprising at least two different types of silica nanoparticles. It is known that silica nanoparticles may be of pure silicon dioxide, or they may contain a certain amount of impurities such as AI2O3, ZnO, and/or cations such as Na+, K++, Ca++, Mg++, etc.
[00156] However, the at least one filler need not be a nanoparticle or a silica.
For example, the at least one filler is exemplified by reinforcing and/or extending fillers such as, alumina, calcium carbonate (e.g., fumed, ground, and/or precipitated), diatomaceous earth, quartz, silica (e.g., fumed, ground, and/or precipitated), talc, zinc oxide, chopped fiber such as chopped KEVLAR®, or a combination thereof.
[00157] The inclusion of certain fillers may pose some adverse reactions with certain silicone compositions (for example, those containing hydrolyzable groups). To combat this problem, the at least one filler may optionally be surface treated with a filler treating agent. The at least one filler may be surface treated prior to incorporation into the first and/or second electrode layers or the at least one filler may be surface treated in situ.
[00158] The amount of the filler treating agent utilized to treat the at least one filler may vary depending on various factors including the type and amounts of fillers utilized and whether the filler is treated with filler treating agent in situ or pretreated before being combined the silicone composition.
[00159] The filler treating agent may comprise a silane such as an alkoxysilane, an alkoxy-functional oligosiloxane, a cyclic polyorganosiloxane, a hydroxyl- functional oligosiloxane such as a dimethyl siloxane or methyl phenyl siloxane, a stearate, or a fatty acid.
[00160] Alkoxysilane filler treating agents are exemplified by, for example, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, phenyltrimethoxysilane, phenylethyltrimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and a combination thereof.
[00161] Alkoxy-functional oligosiloxanes can also be used as filler treating agents. Alkoxy-functional oligosiloxanes and methods for their preparation are known in the art. For example, suitable alkoxy-functional oligosiloxanes include those of the formula
Figure imgf000045_0001
In this formula, subscript q' is
1, 2, or 3, alternatively q' is 3. Each RIO can be independently selected from saturated and unsaturated monovalent hydrocarbon groups of 1 to 10 carbon atoms.
Each RH can be a saturated or unsaturated monovalent hydrocarbon group having at least 11 carbon atoms. Each R12 can be an alkyl group.
[00162] Alternatively, silazanes may be utilized as the filler treating agent, either discretely or in combination with, for example, alkoxysilanes.
[00163] Alternatively still, the filler treating agent can be any of the organosilicon compounds typically used to treat silica fillers. Examples of organosilicon compounds include, but are not limited to, organochlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, and trimethyl monochlorosilane; organosiloxanes such as hydroxy-endblocked dimethyl siloxane oligomer, hexamethyldisiloxane, and tetramethyldivinyldisiloxane; organosilazanes such as hexamethyldisilazane and hexamethylcyclotrisilazane; and organoalkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3- glycidoxypropyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane. Examples of stearates include calcium stearate. Examples of fatty acids include stearic acid, oleic acid, palmitic acid, tallow, coconut oil, and combinations thereof
[00164] The first and/or second electrode layers may independently comprise any combination of conductive fibers, foamed articles, electrically conductive additives, and fillers, contingent on the desired physical properties of the first and/or second electrode layers. The load of each of these components within the first and/or second electrode layers in contingent on numerous factors, e.g. whether the first and/or second electrode layers are formed from the silicone composition, the presence or absence of other components, and the desired conductive properties of the first and/or second electrode layers.
[00165] The instant method may be carried out as a batch, semi-batch, or continuous process. In certain embodiments, the first electrode layer, the electroactive layer, and the second electrode layer are sequentially formed, i.e., the electroactive layer is formed on the first electrode layer, and then the second electrode layer is formed on the electroactive layer. [00166] In other embodiments, the first electrode layer, the electroactive layer, and/or the second electrode layer are separately formed and assembled or otherwise laminated to form the electroactive article. In these embodiments, the instant method is generally referred to as a roll-to-roll or reel-to-reel fabrication method.
[00167] For example, in the roll-to-roll fabrication method, the first electrode layer and the second electrode layer may be separately formed on release liners. Alternatively, one of the first and/or second electrode layers may be formed on a release liner. Similarly, the electroactive layer may be formed on a release liner or on the first and/or second electrode layer. The various layers (i.e., the first electrode layer, the second electrode layer, and the electroactive layer) may be separated from their respective release liners and laminated to form the electroactive article. Such a method provides an efficient method having a high output. Once the electroactive article is laminated from the various layers, the electroactive article may be cut into a desired size contingent on the end use of the electroactive article.
[00168] The electroactive article formed via the instant method may be utilized in diverse applications, particularly those which require conversion between mechanical and electrical energy. Specific examples of such applications or end uses include robotics, pumps, speakers, general automation, disk drives, and prosthetic devices. When the first and/or second electrode layers are formed from the silicone composition, and when the first and/or second electrode layers comprise the conductive fiber(s) and/or the electrically conductive additive, the first and/or second electrode layers have excellent physical and mechanical properties, including flexibility and elongation.
[00169] It is to be understood that the appended claims are not limited to express and particular compounds, compositions, or methods described in the detailed description, which may vary between particular embodiments which fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, different, special, and/or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims. [00170] Further, any ranges and subranges relied upon in describing various embodiments of the present invention independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein. One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present invention, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range "of from 0.1 to 0.9" may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as "at least," "greater than," "less than," "no more than," and the like, it is to be understood that such language includes subranges and/or an upper or lower limit. As another example, a range of "at least 10" inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range "of from 1 to 9" includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1, which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.

Claims

CLAIMS What is claimed is:
1. A method of preparing an electroactive article, said method comprising the steps of:
providing a first electrode layer;
forming an electroactive layer adjacent and substantially parallel to the first electrode layer; and
forming a second electrode layer disposed adjacent and substantially parallel to the electroactive layer such that the electroactive layer is sandwiched between the first and second electrode layers, thereby preparing the electroactive article.
2. The method of claim 1 wherein the step of providing the first electrode layer comprises forming the first electrode layer on a substrate.
3. The method of claim 2 wherein the substrate comprises a release liner.
4. The method of any one preceding claim wherein the first electrode layer is the same as the second electrode layer.
5. The method of any one of claims 1-3 wherein the first electrode layer is different from the second electrode layer.
6. The method of any one preceding claim wherein the second electrode layer comprises electrically conductive electrospun fibers.
7. The method of any one of claims 1-5 wherein the second electrode layer is formed via physical vapor deposition.
8. The method of any one of claims 1-5 wherein at least one of the first and second electrode layers is formed from a silicone composition selected from a peroxide-curable silicone composition, a condensation-curable silicone composition, an epoxy-curable silicone composition, an ultraviolet radiation-curable silicone composition, a high-energy radiation-curable silicone composition, and a hydrosilylation-curable silicone composition.
9. The method of claim 8 wherein the silicone composition comprises a silicone resin comprising T and/or Q units.
10. The method of any one of claims 1-5, 8 and 9 wherein at least one of the first and second electrode layers comprises a foam.
11. The electroactive article of claim 10 wherein the foam of the at least one of the first and second electrode layers has an open-celled structure with a continuous silicone phase throughout the open-celled structure of the foam.
12. The method of any one of claims 1-5 and 7-11 wherein at least one of the first and second electrode layers comprises at least one conductive fiber.
13. The method of any one of claims 1-5 and 7-12 wherein at least one of the first and second electrode layers comprises an electrically conductive filler.
14. The method of any one preceding claim further defined as a roll-to-roll process.
15. An electroactive article formed in accordance with the method of any one preceding claim.
PCT/US2013/077858 2012-12-28 2013-12-26 Method of preparing electroactive article and electroactive article formed in accordance therewith WO2014105981A1 (en)

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