WO2014105986A1

WO2014105986A1 - Electroactive article including modified electroactive layer

Info

Publication number: WO2014105986A1
Application number: PCT/US2013/077869
Authority: WO
Inventors: Kent R. LARSON; Michael RABIDEAU
Original assignee: Dow Corning Corporation
Priority date: 2012-12-28
Filing date: 2013-12-26
Publication date: 2014-07-03
Also published as: TW201442861A

Abstract

An electroactive article comprises a first electrode layer. The electroactive article further comprises a modified electroactive layer disposed adjacent and substantially parallel to the first electrode layer. The electroactive article also comprises a second electrode layer disposed adjacent and substantially parallel to the modified electroactive layer.

Description

ELECTROACTIVE ARTICLE INCLUDING MODIFIED

ELECTROACTIVE LAYER

FIELD OF THE INVENTION

[0001] The present invention generally relates to an electroactive article and, more specifically, to an electroactive article including a modified electroactive layer.

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] However, conventional electroactive polymers are expensive and, moreover, end uses and applications of conventional electroactive polymers are limited. For example, some conventional electroactive polymers cannot withstand elevated temperatures. Other conventional electroactive polymers are not suitable for biological applications, e.g. as artificial muscles or other prosthetics for the human body. Further, methods of preparing conventional electroactive articles including such conventional electroactive polymers are time consuming.

SUMMARY OF THE INVENTION AND ADVANTAGES

[0004] The present invention provides an electroactive article. The electroactive article comprises a first electrode layer. The electroactive article further comprises a modified electroactive layer disposed adjacent and substantially parallel to the first electrode layer. The electroactive article also comprises a second electrode layer disposed adjacent and substantially parallel to the modified electroactive layer such that the modified electroactive layer is sandwiched between the first and second electrode layers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Other advantages and aspects of this invention may be described in the following detailed description when considered in connection with the accompanying drawings wherein:

[0006] Figure 1 is a schematic cross-sectional view of one embodiment of an electroactive article.

DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention provides an electroactive article having excellent physical properties that is suitable for use in many diverse applications and end uses. [0008] The electroactive article comprises a first electrode layer and a second electrode layer. A modified electroactive layer is disposed substantially parallel and adjacent to the first and second electrode layers. Said differently, as shown in Figure 1, which illustrates a schematic cross-sectional view of one embodiment of the invention, the modified electroactive layer 14 is sandwiched between the first and second electrode layers 12, 16 of the electroactive article 10. The modified electroactive layer is generally in contact with both the first and second electrode layers. 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.

[0009] The first and second electrode layers of the electroactive article may comprise any electrically conductive material and may be the same as or different from one another. For example, the first and/or second electrode layers may comprise a metal or alloy foil. Alternatively, the first and/or second electrode layers may be formed from, for example, physical vapor deposition or chemical vapor deposition. The thicknesses of the first and second electrode layers are typically selected based on the application or end use in which the electroactive article is utilized and these thicknesses may be the same as or different from one another.

[0010] The modified electroactive layer is generally formed from an electroactive polymer. The electroactive polymer utilized to form the modified 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.

[0011] In certain embodiments, the modified electroactive layer is formed from a silicone composition. When the modified electroactive layer is formed from the silicone composition, the silicone composition is generally cured, or cross-linked, to form the modified electroactive layer. To this end, the silicone composition may be 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. [0012] Independent of the particular silicone composition utilized to form the modified electroactive layer, the electroactive layer may comprise any combination of siloxane units, i.e., the electroactive layer may comprise any combination of RaSiO^ units, i.e., M units, R₂S1O_2/2 units, i.e., D units, RS1O_3/2 units, i.e., T units, and S1O_4/2 units, i.e., Q units, where R is typically a substituted or unsubstituted hydrocarbyl group. For example, the electroactive layer is typically elastomeric and may comprise a rubber, a gel, a resin, or combinations thereof, i.e., the electroactive layer may be continuous or discontinuous in terms of its composition. For example, when the modified electroactive layer comprises a rubber or a gel, the silicone composition utilized to form the modified electroactive layer generally comprises at least one polymer including repeating D units, i.e., a linear or branched polymer. When the modified electroactive layer comprises a resin, the silicone composition utilized to form the modified electroactive layer generally includes a silicone resin having T and/or Q units.

[0013] Certain embodiments in which the modified electroactive layer is formed from a silicone composition and in which the modified electroactive layer has a resinous structure are described below.

[0014] In various embodiments when the modified electroactive layer is formed from a hydrosilylation-curable silicone composition, the hydrosilylation-curable silicone composition comprises a resin (A), a cross-linking agent (B), and a hydrosilylation 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 R1 is a Ci to C \Q hydrocarbyl group or a Ci to C \Q halogen-substituted hydrocarbyl group, both free of aliphatic unsaturation, and R2 is R¹, 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.

[0015] The Ci to Ci Q hydrocarbyl group and Ci to Ci Q halogen-substituted hydrocarbyl group represented by R1 more typically have from 1 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 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 .

[0016] The alkenyl groups represented by R^, 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, 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 R^ in the silicone resin are alkenyl groups. In another embodiment, R^ 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 R^ 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.

[0017] According to a first embodiment, the silicone resin (A) has the formula:

(RlR¾SiO l/2)w(R²2Si0₂/₂)x (R²Si0₃/2)y(Si04/2)_z (I) wherein R1 and R^ 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.

[0018] 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.

[0019] 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.

[0020] 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 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.

[0021] 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. [0022] 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.

[0023] 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.

[0024] 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).

[0025] 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.

[0026] The organohydrogensilane can be a monosilane, disilane, trisilane, or polysilane.

When R2 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, l,3,5-trimethyl-l,3,5-trisilane, poly(methylsilylene)phenylene, and poly(methylsilylene)methylene. When R2 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.

[0027] The organohydrogensilane can also have the formula:

HR^Si-R^SiR^H (ΠΙ) wherein R¹ is as defined and exemplified above and R3 is a hydrocarbylene group free of aliphatic unsaturation havin a formula selected from the following structures:

wherein g is from 1 to 6.

[0028] Specific examples of organohydrogensilanes having the formula (III), wherein R1 and R3 are as described and exemplified above include, but are not limited to, organohydrogensilanes having a formula selected from the following structures:

[0029] The organohydrogensiloxane can be a disiloxane, trisiloxane, or polysiloxane.

Examples of organosiloxanes suitable for use as the cross-linking agent (B) when 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.

[0030] 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.

[0031] 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 R1R4₂SIO I/₂ 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.

[0032] The group represented by R4 is either R1 or an organosilylalkyl group having at least one silicon-bonded hydrogen atom. Examples of organosilylalkyl groups represented by

R4 include, but are not limited to, groups having a formula selected from the following structures:

-CH₂CH₂Me₂Si ft SiMe₂H

-CH₂CH₂MePhSi ft / SiPh₂H

CH₂CH₂SiMe₂H, -CH₂CH₂SiMe₂C_nH_2nSiMe₂H, -CH₂CH₂SiMe₂C_nH_2nSiMePhH, -CH₂CH₂SiMePhH, -CH₂CH₂SiPh2H, -CH2CH₂SiMePhC_nH2nSiPh2H,

-CH2CH2SiMePhC_nH2_nSiMe₂H, -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 in the organohydrogenpolysiloxane resin are organosilylalkyl groups having at least one silicon-bonded hydrogen atom. As used herein, the mol% of organosilylalkyl groups in 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 R4 groups in the resin, multiplied by 100.

[0033] 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.

[0034] Specific examples of organohydrogenpolysiloxane resins represent by formula

(IV) above include, but are not limited to, resins having the following formulae:

((HMe₂SiC₆H4SiMe₂CH2CH2)2MeSiO i/2)o.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)

Me₂Si0₁/2)o.06(P^hSi03/₂)o.86>

wherein Me is methyl, Ph is phenyl, Cgl 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.

[0035] Specific examples of organohydrogenpolysiloxane resins include, but are not limited to, resins having the following formulae:

((HMe₂SiC₆H4SiMe₂CH2CH2)2MeSiO i/2)o.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)0.66' ((HMe2SiC₆H4SiMe2CH2CH₂)2MeSiOi/2)0.15(PhSiO3/2)0.75(SiO4/2)0.10₅ and ((HMe2SiC₆H4SiMe2CH2CH2)2MeSiO₁/2)0.08((^HMe2SiC6H4SiMe₂CH2CH2)

Me2SiOi /2)0.06(Pⁿ iO3/2)().86' ^wnere Me is methyl, Ph is phenyl, CgH4 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.

[0036] 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.

[0037] 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)

[0038] 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.

[0039] 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 1 ,3-diethenyl- 1 , 1 ,3,3-tetramethyldisiloxane.

[0040] 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.

[0041] 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.

[0042] 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 .

[0043] Specific examples of photoactivated hydrosilylation catalysts suitable for purposes of the present invention include, but are not limited to, platinum(II) β-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( 1 ,3-diphenyl- 1 ,3-propanedioate), platinum(II) bis( 1 , 1 , 1 ,5,5,5-hexafluoro-2,4-pentanedioate) ; (η-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 PtfCgf^NNNOCI^^, Ptfp-CN-CglfyNNNOCgHi ι ]

Pt[p-H3COC₆H4NNNOC₆H_n]₄, Pt[p-CH₃(CH2)_x-C₆H₄NNNOCH3]4, 1,5- cyclooctadiene.Pt[p-CN-C6H4NNNOC6Hn]2, l,5-cyclooctadiene.Pt[p-CH30- C6H₄NNNOCH₃]₂, [(CgHs^P^Rhfp-CN-Cgi NNNOCgHi i], and Pd[p-CH₃(CH2)_X— CgH4NNNOCH3]2, where x is 1, 3, 5, 11, or 17; ^-diolefin)(o-aryl)platinum complexes, such as (T|4- 1 ,5-cyclooctadienyl)diphenylplatinum, T|4- 1 ,3,5,7-cyclooctatetraenyl)diphenylplatinum, (^-2,5-norboradienyl)diphenylplatinum, (r|4- 1 ,5-cyclooctadienyl)bis-(4- dimethylaminophenyl)platinum, ^4-l,5-cyclooctadienyl)bis-(4-acetylphenyl)platinum, and (r|4- l,5-cyclooctadienyl)bis-(4-trifluormethylphenyl)platinum. Typically, the photoactivated hydrosilylation catalyst is a Pt(II) β-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.

[0044] 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). [0045] Optionally, the hydrosilylation-curable silicone composition further includes (D) a silicone rubber having a formula selected from the group of (i) RlR2₂SiO(R2₂SiO)_aSiR2₂Rl and (ii) R⁵R¹2SiO(R¹R⁵SiO)bSiR¹2R⁵; wherein R¹ and R² are as defined and exemplified above, R5 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.

[0046] 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).

[0047] 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).

[0048] 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.

[0049] 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.

[0050] 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.

[0051] In another embodiment of the present invention, the hydrosilylation-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:

R⁵R¹ ₂SiO(R¹R⁵SiO)_cSiR¹ ₂R⁵, and R!R^S XR^SiC dSiR^R¹,

wherein R1 and R^ 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.

[0052] 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, hydro silylation 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-l-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; antioxidants; heat stabilizers; UV stabilizers; flame retardants; flow control additives; and diluents, such as organic solvents and reactive diluents.

[0053] In other embodiments, the modified electroactive layer is formed from a condensation-curable silicone composition. The condensation-curable silicone composition typically includes a silicone resin (A²) 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 (A²) is typically a copolymer comprising RIS1O3/2 units, i.e., T units, and/or S1O4/2 units, i.e., Q units, in combination with RlR^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.

[0054] According to one embodiment, the silicone resin (A²) has the formula:

(RlR62SiOi/2)_w'(R⁶2Si02/2)x'(R⁶Si0₃/2)y'(Si04/2)_z' (V) wherein R!and R⁶ 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 (A²) 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 C₈ hydrocarbyl or Ci to C₈ halogen- substituted hydrocarbyl.

[0055] 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 R⁷ 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 R⁷ include, but are not limited to, 3,3,3-trifluoropropyl, 3-chloropropyl, chlorophenyl, and dichlorophenyl.

[0056] Typically, at least 1 mol%, alternatively at least 5 mol%, alternatively at least 10 mol% of the groups R^ in the silicone resin (A²) are hydrogen, hydroxy, or a hydrolysable group. As used herein, the mol% of groups in R^ 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 R^ groups in the silicone resin (A²), multiplied by 100.

[0057] 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 . (PhSiO₃/2)0.7(Ph(MeO)SiO2/2)0.3.

(Me₃SiOi/2)0.8(SiO4/2)0.15(HOSiO3/2)0.05₅

(MeSiO3/2)0.67(PhSiO₃/2)0.23(Ph(HO)SiO2/2)0.b

(MeSiO3/2)0 5(PhSiO₃/2)0 4(P HO^^

(PhSiO₃/2)0.3(Ph(HO)SiO₂/2)0. l(M^

2/2)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.

[0058] As set forth above, the silicone resin (A^) represented by formula (V) typically has a number- average molecular weight (M_n) of from 500 to 50,000. Alternatively, the silicone resin (A^) may have a M_n 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.

[0059] The viscosity of the silicone resin (A^) 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.

[0060] In a second embodiment, the silicone resin (A^) 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 R6si03/2 units and S1O4/2 units is greater than zero and with the further proviso that the silicone resin (A^) 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 (A^) 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 (A^) of the second embodiment are hydrogen, hydroxy, or a hydrolysable group.

[0061] Examples of condensation curable silicone resins (A^) of the second embodiment include, but are not limited to, silicone resins having the following formulae: (Me(MeO)Si₂/2)x'(MeSi0₃/2) , (Ph(HO)Si0₂/2)x'(PhSi0₃/2) , (Me3Si0₁/2)_w CH3COOSi03/2) (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) (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.

[0062] Specific examples of condensation curable silicone resins (A^) of the second embodiment include, but are not limited to, silicone resins having the following formulae:

(Me(MeO)Si₂/2)0.05(^Me3^SiOl/2)0.75(^Si°4/2)0.2'

(Ph(HO)SiO2/2)0.09(MeSiO3/2)0.67(PhSiO₃/2)0.24,

(Ph(MeO)SiO₂/2)0.05(MeSiO₃/2)0 5(PhS^

(PhMe(MeO)SiO₁/2)0.02(PhSiO3/2)0 (MeSiO3/2)0 5(PhSiO3/2)0 (PhMeSiO2/2)0.03^nd

(Ph(HO)SiO2/2)0.04(PhMe(MeO)SiO_1/2)0.03(P^hSiO3/2)0.36(^MeSiO3/2)0.l(P^hMe

SiO2/2)0.47

[0063] As set forth above, the condensation curable silicone resin (A^) of the second embodiment typically has a number- average molecular weight (M_n) of from 500 to 50,000.

Alternatively, the 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.

[0064] The viscosity of the condensation curable silicone resin (A^) 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 ^ i NMR. [0065] 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 R!R^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 R6 are as defined and exemplified above. The cohydrolyzing process is described above in terms of the hydrosilylation-curable silicone composition. The cohydrolyzed reactants can be further "bodied" to a desired extent to control the amount of crosslinkable groups and viscosity.

[0066] 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.

[0067] 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.

[0068] 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

(R¹R6₂SiOi/2)_w'(R⁶2Si02/2)x'(R⁶Si03/2)y'(Si0₄/2)_z', (ii) 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. 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.

[0069] 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^qSiX4_q, wherein is Ci to Cg hydrocarbyl or Ci 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.

[0070] 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(OCH₂CH₂OCH₃)₃, CF₃CH₂CH₂Si(OCH₂CH₂OCH₃)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 CH₃Si[0-N=C(CH₃)CH₂CH₃]₃, Si[0-N=C(CH₃)CH₂CH₃]₄, and CH₂=CHSi[0-N=C(CH₃)CH₂CH₃]₃; organoacetamidosilanes such as

CH Si[NHC(=0)CH ] and C6H₅Si[NHC(=0)CH ] ; amino silanes such as CH Si[NH(s-

C4Hc))]₃ and CH₃Si(NHCgHi i )₃; and organoaminooxysilanes.

[0071] The cross-linking agent (B^) 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.

[0072] When present, the concentration of the cross-linking agent (β ΐ) 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 ¹) 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 (B^) 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 (βΐ) can be readily determined by routine experimentation.

[0073] 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.

[0074] 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^).

[0075] 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.

[0076] 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.

[0077] In yet another embodiment, the modified electroactive layer is 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).

[0078] The silicone resin (A⁴) 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 (A⁴) in the presence of an organic peroxide, and (iii) exposing the silicone resin

(A⁴) to an electron beam. The silicone resin (A⁴) is typically a copolymer containing T siloxane units and/or Q siloxane units in combination with M and/or D siloxane units.

[0079] For example, the silicone resin (A⁴) may have the formula

(R¹R⁹2SiOi/2)_W"(R⁹2Si02/2)x"(R⁹Si03/2)y"(Si04/2)_z", wherein R¹ is as defined and exemplified above, R⁹ 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.

[0080] The alkenyl groups represented by R⁹, which may be the same or different, are as defined and exemplified in the description of R2 above.

[0081] The alkynyl groups represented by R⁹, 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.

[0082] The silicone resin (A⁴) 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.

[0083] The silicone resin (A⁴) 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

²⁹Si NMR.

[0084] Specific examples of silicone resins (A⁴) 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, ( iMe₂SiOi/2)o.25(PhSi03/2)₀.75₅ (ViMe₂SiO_1/2)0.25(MeSiO3_/2)0.25(PhSiO_3/2)0.50₅ ( iMe2Si0_1/2)o.l5(PhSi0_3/2)o.75 (Si0₄/₂)o.l, and (Vi2MeSiOi 2)o.l5( iMe₂SiOi 2)o.l(PhSi03 2)o.75.

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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 .

[0092] 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.

[0093] 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.

[0094] 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. [0095] 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.

[0096] Examples of free radical photoinitiators include, but are not limited to, benzophenone; 4,4'-bis(dimethylamino)benzophenone; halogenated benzophenones; acetophenone; cc-hydroxyacetophenone; chloro acetophenones, such as dichloroacetophenones and trichloroacetophenones; dialkoxyacetophenones, such as 2,2-diethoxyacetophenone; cc- hydoxyalkylphenones, such as 2-hydroxy-2-methyl- l -phenyl- 1-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 -oximinoketones, such as 1 -phenyl- l,2-propanedione-2-(O-ethoxycarbonyl)oxime.

[0097] 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.

[0098] 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^).

[0099] 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.

[00100] 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

(A4).

[00101] 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.

[00102] 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.

[00103] 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.

[00104] Another suitable silicone composition suitable for forming the modified electroactive layer 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.

[00105] Another suitable silicone composition suitable for forming the modified electroactive layer comprises hydrogenpolysiloxanes having a siloxane unit formula of [H2Si02/2]x"'[HSi03/2]y"' [SiO^lz'" 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.

[00106] When z'" = 0 in the siloxane unit formula [H2Si02/2]x"'[HSi03/2]y"'[SiC>4/2]_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.

[00107] When y'" = 0 in the siloxane unit formula [H2Si02/2]x"'[HSi03/2]y"'[SiC>4/2]_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.

[00108] 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.

[00109] 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. [00110] 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.

[00111] The modified electroactive layer has at least one property that is modified as compared to an electroactive layer that is not modified (but otherwise formed from the same composition). The modification of the electroactive layer may occur in situ during formation of the electroactive layer such that the electroactive layer does not exist in an unmodified form. Alternatively, the electroactive layer may be first formed and subsequently modified to form the modified electroactive layer.

[00112] The modified electroactive layer is characterized by having at least one modified property. The modified property may be a physical property, a chemical property, or combinations thereof. For example, the modified electroactive layer may have modified dielectric properties, coefficient of thermal expansion properties, tensile strength properties, modulus properties, surface roughness properties, electric field properties, etc. relative to an electroactive layer that is not modified.

[00113] For example, in certain embodiments, the modified electroactive layer is modified via at least one fiber, which is typically embedded in the modified electroactive layer, although the at least one fiber may be physically and/or chemically bonded to a surface of the modified electroactive layer in addition or alternatively to being embedded or partially embedded therein.

[00114] In these embodiments, the modified electroactive layer comprises a plurality of fibers, alternatively a single fiber. The fiber(s) of the modified electroactive layer may be woven or nonwoven. The 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 fiber(s) may comprise combinations and/or composites of certain materials. For example, different fibers within the modified electroactive layer may independently comprise different materials. Further, when a single fiber is employed in the modified electroactive layer, the single fiber may vary in its composition.

[00115] The fiber(s) of the modified electroactive layer may independently be porous or non-porous, optionally having one or more porous or non-porous coatings.

[00116] The fiber(s) of the modified electroactive layer may be woven, nonwoven, or combinations thereof. For example, when the fiber(s) of the modified electroactive layer are woven, the fiber(s) of the modified electroactive layer may be interlaced with one another such that certain fiber(s) (or portions of fiber(s)) are substantially parallel with one another (or with another portion of the same fiber) and certain fiber(s) (or portions of fiber(s)) are substantially perpendicular to one another (or to another portion of the same fiber). Alternatively, the angles between certain fiber(s) may be other than perpendicular, e.g. acute or obtuse. Accordingly, when the fiber(s) of the modified electroactive layer are woven, the fiber(s) generally have a defined pattern. Typically, such woven fiber(s) are referred to as a cloth. Alternatively, when the fiber(s) of the modified electroactive layer are nonwoven, the fiber(s) of the modified electroactive layer are generally entangled with one another such that the modified electroactive layer includes a web of fiber(s) that are bonded together mechanically, thermally, and/or chemically without a defined pattern. Adjacent 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 fibers are referred to as a mat or a roving. Alternatively still, the fiber(s) may be loose and individual fiber(s) that are not bonded together mechanically, thermally, and/or chemically.

[00117] The 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 fiber(s), particularly a thickness of the fiber(s), are generally selected based on a desired physical property modification of the modified electroactive layer. For example, in certain embodiments, the modified electroactive layer generally has a thickness of from about 0.5 to about 3 microns, in which case the fiber(s) generally have at least one dimension less than the thickness of the modified electroactive layer. Alternatively still, the 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 fiber(s).

[00118] The fiber(s) may independently have a cross-sectional shape that is elliptical, spherical, square, rectangular, or other various shapes. The 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.

[00119] The fiber(s) may be heat-treated prior to use to remove any organic or other contaminants. For example, 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.

[00120] The composition of the fiber(s) is generally selected based on the desired physical properties of the modified electroactive layer. For example, in certain embodiments, the fiber(s) are utilized to modify the dielectric properties of the modified electroactive layer. To this end, the fiber(s) may comprise a conductor, an insulator, or a dielectric material, or the fiber(s) may comprise combinations of such materials. Specific examples of fiber(s) that are suitable for purposes of the present invention include, but are not limited to, reinforcements comprising glass fibers; quartz fibers; graphite fibers; nylon fibers; polyester fibers; aramid fibers, such as Kevlar® and Nomex®; polyethylene fibers; polypropylene fibers; and silicon carbide fibers. The fiber(s) may independently be selected from natural fibers, synthetic fibers, metallic fibers, carbon fibers, mineral fibers, cellulose fibers, polymer fibers, ceramic fibers, etc.

[00121] The fiber(s) of the modified electroactive layer may be formed via known methods, e.g. the fiber(s) may be purchased or otherwise obtained or may be formed, for example, from spinning. For example, the fiber(s) may be spun via dry spinning, melt spinning, extrusion spinning, direct spinning, gel spinning, electro spinning, and/or drawing.

[00122] The fiber(s) may be utilized to form the modified electroactive layer in various methods. For example, the fiber(s) may be impregnated with the silicone composition. The fiber(s) may be impregnated with the silicone composition using a variety of methods. For example, the silicone composition may be applied to a release liner 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 fiber(s) therein. The release liner can be any rigid or flexible material having a surface from which the modified electroactive layer can be removed without damage by delamination after the silicone composition is cured. Examples of release liners include, but are not limited to, nylon, polyethyleneterephthalate, and polyimide. The release liner may optionally have a corrugated surface to impart the modified electroactive layer with a particular surface roughness or corrugation. Further, the release liner may be coated or uncoated, and may include fiber(s), fillers, or other additives thereon which may be imparted into the surface of the modified electroactive layer once separated from the release liner.

[00123] The fiber(s) may be embedded in the silicone film, thereby forming an embedded silicone film. The fiber(s) may be embedded in the silicone film by simply placing the fiber(s) on the silicone film and allowing the silicone composition to saturate the fiber(s). However, the fiber(s) may be first deposited on the release liner, followed by the application of the silicone composition onto the fiber(s). In another embodiment, when the fiber(s) comprise a woven or nonwoven fabric, the fiber(s) may be impregnated with the silicone composition by passing the fiber(s) through the silicone composition without the use of the release liner. The 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 fiber(s) are formed by electro spinning. The silicone film may act as the substrate or wafer for the electro spinning process such that the electrospun fibers are deposited directly onto the silicone film. Alternatively, the electrospun fibers may be formed and subsequently disposed in or on the silicone film.

[00124] 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.

[00125] 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. [00126] 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.

[00127] Typically, the silicone composition in the impregnated silicone film is cured to form the modified electroactive layer. "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.

[00128] 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.

[00129] In certain embodiments, the fiber(s) may comprise piezoelectric fibers, such as those disclosed in U.S. Pat. No. 5,869,189, which is incorporated by reference herein in its entirety. In other embodiments, the fiber(s) may comprise microfibers, such as those disclosed in U.S. Pat. No. 6,680,114, which is incorporated by reference herein in its entirety. [00130] Alternatively or in addition to the fiber(s), a foamed article may be utilized in or as the modified electroactive layer. For example, a silicone composition may be foamed itself such that, once cured, the modified electroactive layer comprises a foamed silicone, typically a foamed silicone elastomer. Alternatively, a foamed article may be utilized in lieu of the fiber(s). For example, an open-celled foamed article may be impregnated with the silicone composition such that, once cured, the modified electroactive layer comprises a continuous silicone phase throughout the open cells of the open-celled foamed article. The open-celled foamed article may comprise, for example, a polyurethane, a polyisocyanurate, a polyurea, 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.

[00131] When the modified electroactive layer comprises an open-celled structure, the modified electroactive layer may be formed from the methods described above relating to the fiber(s). For example, the modified electroactive layer may be formed by disposing a silicone composition on a substrate, e.g. the release liner, to form the silicone film, imbedding a foamed article into the silicone film, and curing the silicone film or optionally adding an additional amount of the silicone composition to the foamed article and then curing the silicone composition and the silicone film. Alternatively, the foamed article may be placed onto a substrate in the absence of a silicone film, and the silicone composition may be disposed on the foamed article such that the silicone composition fills at least a portion of the open cells of the foamed article, followed by curing of the silicone composition. Alternatively still, the foamed article may be passed through or disposed in the silicone composition such that the silicone composition at least partially fills the voids defined by the open cells of the foamed article. In such embodiments, the foamed article may act as a carrier for the silicone composition.

[00132] When the modified electroactive layer comprises the foamed article, the foamed article may span an entire thickness of the modified electroactive layer, the foamed article may be encapsulated within the modified electroactive layer such that the open cells are not present at any surface of the modified electroactive layer, or the foamed article may be present in the modified electroactive layer such that the foamed article is not encapsulated within the modified electroactive layer. For example, the modified electroactive layer may comprise the foamed article at one or more surfaces of the modified electroactive layer, which generally introduces a surface roughness to the modified electroactive layer.

[00133] In other embodiments, the modified electroactive layer comprises at least one filler. The modified electroactive layer may comprise the at least one filler in combination with the fiber(s) and/or foamed article described above or in the absence of the fiber(s) and/or foamed article described above.

[00134] The at least one filler is typically mixed into the silicone composition using conventional mixing methods prior to curing the silicone composition and prior to forming a film from the silicone composition on the release liner.

[00135] 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 modified electroactive layer includes 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 A105", 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.

[00136] 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 (IP A), ketones such as methyl isobutyl ketone, water, acetic acid, diols and trials such as propylene glycol, 2-methyl-l,3-propane diol HOCH2CH(CH3)CH20H, 1,2-hexanediol

CH3(CH2)3CH(OH)CH20H, 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 C4H9(OCH(CH3)CH2)i 4OH. Alternatively, the silica nanoparticles can also be dispersed in a non-polar solvent such as toluene, benzene, xylene, etc.

[00137] 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.

[00138] 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.

[00139] 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 modified electroactive layer or the at least one filler may be surface treated in situ.

[00140] 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.

[00141] 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.

[00142] Alkoxysilane filler treating agents are exemplified by, for example, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, phenyltrimethoxysilane, phenylethyltrimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and a combination thereof. [00143] 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

(R¹⁰O)q'Si(OSiR¹⁰2R^{1 1})(4-q')- In this formula, subscript q' is 1, 2, or 3, alternatively q' is 3.

Each R!O 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.

[00144] Alternatively, silazanes may be utilized as the filler treating agent, either discretely or in combination with, for example, alkoxysilanes.

[00145] 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 dimethylsiloxane 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

[00146] In certain embodiments, the at least one filler may be a thermally conductive filler and/or an electrically conductive filler. The thermally conductive filler may be both thermally conductive and electrically conductive. Alternatively, the thermally conductive filler may be thermally conductive but electrically insulating. The thermally conductive filler may be selected from the group consisting of 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 thermally 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 be, for example, metal nitride layers or metal oxide layers on the surfaces of the particles. 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.

[00147] Metal fillers can be treated with alkylthiols such as octadecyl mercaptan and others, and fatty acids such as oleic acid, stearic acid, titanates, titanate coupling agents, zirconate coupling agents, and a combination thereof.

[00148] Inorganic fillers are exemplified by onyx; aluminum trihydrate, metal oxides such as aluminum oxide, beryllium oxide, magnesium oxide, and zinc oxide; nitrides such as aluminum nitride and boron nitride; carbides such as silicon carbide and tungsten carbide; and combinations thereof. Alternatively, inorganic fillers are exemplified by aluminum oxide, zinc oxide, and combinations thereof. 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. Meltable fillers are commercially available.

[00149] For example, meltable fillers may be obtained from Indium Corporation of

America, Utica, N.Y., U.S.A.; Arconium, Providence, R.I., U.S.A.; and AIM Solder, Cranston, R.I., U.S.A. Aluminum fillers are commercially available, for example, from Toyal America, Inc. of Naperville, Illinois, U.S.A. and Valimet Inc., of Stockton, California, U.S.A. Silver filler is commercially available from Metalor Technologies U.S.A. Corp. of Attleboro, Massachusetts, U.S.A.

[00150] Thermally conductive fillers are known in the art and commercially available, for example, in U.S. Patent 6,169,142, which is incorporated by reference herein in its entirety. For example, CB-A20S and Al-43-Me are aluminum oxide fillers of differing particle sizes commercially available from Showa-Denko, and AA-04, AA-2, and AA18 are aluminum oxide fillers commercially available from Sumitomo Chemical Company. Zinc oxides, such as zinc oxides having trademarks KADOX® and XX®, are commercially available from Zinc Corporation of America of Monaca, Pennsylvania, U.S.A.

[00151] The shape of the thermally conductive filler particles is not specifically restricted, however, rounded or spherical particles may prevent viscosity increase to an undesirable level upon high loading of the thermally conductive filler in the composition. The thermally conductive filler particles may have a desired aspect ratio for advantageous orientation within the modified electroactive layer.

[00152] The thermally conductive filler may be utilized as a single thermally conductive filler or a combination of two or more thermally conductive fillers that differ in at least one property such as particle shape, average particle size, particle size distribution, and type of filler. For example, it may be desirable to use a combination of inorganic fillers, such as a first aluminum oxide having a larger average particle size and a second aluminum oxide having a smaller average particle size. Alternatively, it may be desirable, for example, to use a combination of an aluminum oxide having a larger average particle size with a zinc oxide having a smaller average particle size. Alternatively, it may be desirable to use combinations of metallic fillers, such as a first aluminum having a larger average particle size and a second aluminum having a smaller average particle size. Alternatively, it may be desirable to use combinations of metallic and inorganic fillers, such as a combination of aluminum and aluminum oxide fillers; a combination of aluminum and zinc oxide fillers; or a combination of aluminum, aluminum oxide, and zinc oxide fillers. Use of a first filler having a larger average particle size and a second filler having a smaller average particle size than the first filler may improve packing efficiency, may reduce viscosity, and may enhance heat transfer.

[00153] The average particle size of the thermally conductive filler will depend on various factors including the type of thermally conductive filler selected and the exact amount added to the silicone composition.

[00154] The amount of the thermally conductive filler in the composition depends on various factors including the cure mechanism selected for the curable silicone composition and the specific thermally conductive filler selected. [00155] If desired, when electrically conductive fillers are utilized, the silicone composition may be cured as a potential difference is applied to the silicone film including the electrically conductive fillers. Such an application of the potential difference may advantageously orient the electrically conductive fillers within the modified electroactive layer. Alternatively or in addition, the silicone composition may be cured as a magnetic field is adjacent to or applied to the silicone composition for advantageously orienting the electrically conductive fillers, particularly when such electrically conductive fillers are magnetic, e.g. paramagnetic. Such an applied field may have beneficial results in the modified electroactive layer in at least one axis thereof contingent upon an orientation of the electrically conductive fillers therein.

[00156] The modified electroactive layer may further comprise any additive for modifying a physical property, e.g. dielectric properties, of the modified electroactive layer. For example, the modified electroactive layer may further comprise a polymeric surfactant, such as those disclosed in U.S. Pat. No. 7,744,778, which is incorporated by reference herein in its entirety. Alternatively or in addition, the modified electroactive layer may comprise an electromagnetic radiation absorbing material, such as those disclosed in U.S. Pat. No. 5,389,434, which is incorporated by reference herein in its entirety. Further, the modified electroactive layer may comprise any of the additives disclosed in U.S. Pat. No. 6,812,624, which is incorporated by reference herein in its entirety.

[00157] The modified electroactive layer may comprise any combination of fibers, foamed articles, and fillers, contingent on the desired physical properties of the modified electroactive layer.

[00158] The electroactive article of the invention 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.

[00159] 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.

[00160] 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. An electroactive article, comprising:

a first electrode layer;

a modified electroactive layer disposed adjacent and substantially parallel to said first electrode layer; and

a second electrode layer disposed adjacent and substantially parallel to said modified electroactive layer such that said modified electroactive layer is sandwiched between said first and second electrode layers.

2. The electroactive article of claim 1 wherein said modified electroactive layer is formed from a silicone composition.

3. The electroactive article of claim 2 wherein said silicone composition is 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.

4. The electroactive article of any one of claims 2 and 3 wherein said silicone composition comprises a silicone resin.

5. The electroactive article of claim 4 wherein said silicone resin comprises T and/or Q units.

6. The electroactive article of any one of claims 1-3 wherein said modified electroactive layer comprises an elastomer.

7. The electroactive article of any one preceding claim wherein said modified electroactive layer comprises at least one fiber.

8. The electroactive article of any one preceding claim wherein said modified electroactive layer comprises a foam.

9. The electroactive article of claim 8 wherein said foam of said modified electroactive layer has an open-celled structure.

10. The electroactive article of claim 9 wherein said modified electroactive layer comprises a continuous silicone phase throughout the open-celled structure of said foam.

11. The electroactive article of any one preceding claim wherein said modified electroactive layer comprises at least one filler.

12. The electroactive article of claim 11 wherein said at least filler comprises an electrically conductive filler.

13. The electroactive article of any one preceding claim wherein said first and second electrode layers are the same as one another.

14. The electroactive article of any one preceding claim wherein said first and second electrode layers comprise a metal or alloy foil.

15. The electroactive article of any one preceding claim wherein said first and second electrode layers are formed via physical vapor deposition or chemical vapor deposition.