CYCLODEXTRIN MODIFIED SILICONE COMPOSITION

FIELD OF THE INVENTION

[0001] The present invention relates to a modified silicone composition, and to the sflicone rubber produced therefrom by curing. More particularly, the present invention relates to a silicone composition having cyckxkxlrin or their derivatives covalently bonded to the sflicone to create a crosslinked hydrophilic silicone rubber.

BACKGROUND

[0002] Traditionally, cured silicone rubber compositions exhibit hydrophobic properties. The hydrophobic nature of these compositions makes traditional silicone rubber compositions advantageous in many applications. However, many applications exist where hydrophilic properties are desired. The moisture management capabilities provided by hydrophilic compositions is desired in skin contact and medical applications (e.g., wound care applications) to keep and draw moisture, sweat and exudates away from the body. Hydrophilic materials also exhfcit a low coefficient of friction useful in applications such as catheters. The resistance to protein adhesion provided by hydrophilic materials is beneficial in body implants and other types of medical devices. Hydrophilic materials are also advantageous in anti-static articles.

[0003] To take advantage of the properties of silicone rubber compositions treatments have been developed to impart hydrophilic properties. A common method for making silicone rubber hydrophilic is plasma treating the surface of the silicone rubber. While this treatment provides hydrophilic properties to the surface of the silicone rubber, the treatment is not permanent and is only effective on the surface of the sflicone rubber. Another method is to provide a hydrophilic coating on the silicone rubber, but this treatment is ineffective as well due to de lamination issues.

[0004] Additionally, US 2002/160139 disclosed a surface modified polymer and a surface covalently bonded to the surface modifying compound. Formation of the covalent bond between the polymer and the surface modifying compound is achieved by reacting an intrinsic functional group that is present in the polymer and the functional group of the surface modifying compound By using a polymer having an intrinsic functional group, a separate surface activation step is avoided Thus, the material has a hydrophilic surface while the bulk of the material remains hydrophobic. Accordingly, this material does not a Dow for the uptake of moisture through the material and moisture can thus not be removed effectively.

[0005] Other examples for making these types of materials use incorporation of polye there to the silicone rubbers. For example, Brook et al reported the synthesis and characterization of protein rejecting PDMS-based rubbers that were prepared by incorporating asymmetric PEO (bearing a methyl group on one end and a functional triethoxysilyl group on the other) into PDMS during rubber formation using classic room temperature vulcanization (RTV) chemistry and further described their potential for use as biomaterials. (Chen, H., Brook, M.A., Sheardown, H., Biomaterials, 2004, 25(12), 2273-82.) It has been shown that the incorporation of polyethylene oxide) into the silicone rubber was able to reduce the protein adsorption. However, incorporation of poly(aIkyk:ne oxides) results in possible harmful impurities, and may result in skin irritation. As a result, many industries avoid the use of polyoxyalkyknes, either as units covalently bonded to a polymer, or separately, as non-ionic surfactants.

[0006] Cyclodextrins (“CD”) have been used as an additive or a carrier in rubber curing formulations. U.S. Publication No. 2005/260905 discloses the use of cyclodextrin as carriers far different additives in polymeric matrix for use in textile finishing material. Although, the cyclodextrin may be part of a crosslinked network, the formulation does not produce a hydrophilic rubber.

[0007] CN 106349705 discloses a high temperature resistant and high flame- retardant silicone rubber cable sheathing material formed by using beta cyclodextrin as one of the components. While the cyclodextrin may be crosslinked, the product does not exhibit hydrophilic properties.

[0008] Cyclodextrins (‘CD”) have been used in rubber curing formulations to provide hydrophilic properties to silicone rubbers. US 5,391,592 discloses a contact lens made by reacting CD modified with alkenyl groups with SiH containing silicones to produce a lipophilic CD-sflicone polymer. The modified CD disclosed no longer contain exclusively free hydroxy groups; rather, some or all of the groups are etherified. Thus, these materials are expected to provide little or no hydrophilic ity. in addition, the lipophilic materials obtained are also not expected to exhibit reduced protein adsorbing properties limiting their application. [0009] Thus, based on the disadvantages still present in the prior art, there is still a need for a crosslinked silicone rubber with hydrophilic properties throughout the bulk of the material, for manufacturing products with moisture control properties, with a tow coefficient of friction with respect to polar or wet surfaces (e.g., skin), and biocompatibility. There is also a need m the art for conveniently producing a crosslinked silicone rubber with hydrophilic properties while avoiding potentially harmful inpurities.

SUMMARY OF THE INVENTION

[0010] It has now been surprisingly and unexpectedly ds covered that silicone rubbers prepared by cross-linking one or more modified cyclodextrin derivatives in a hydros fly lation reaction with one or more organopolysiloxa ne materials in the presence of a noble metal (e.g., platinum) catalyst, form stable, cured hydrophilic silicone rubbers. The cyclodextrin cavity remains useful for“guest-host” complexes, despite being a constituent of a three-dimensional polymer matrix. Other components such as fillers, plasticizers, pigments, and other additives can be added as required. The inventive hydrophilic rubber can be useful for encapsulation and release of cosmetic or pharmaceutical actives, medical devices, transdermal drug delivery patches/device, wound care materials, low friction materials, body implants, wet seals, water absorbing foams and other applications requiring a biocompatible hydrophilic rubber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIGURE 1 illustrates schematically one embodiment of the hydrophilic crosslinked s flic one rubber of the present invention;

[0012] FIGURE 2 illustrates schematically the formation of undecenoyl modified cyclodextrin for use in the hydrophilic crosslinked silicone rubber of the present invention;

[0013] FIGURE 3 illustrates schematically one embodiment of the hydrophilic crosslinked silicone rubber of the present invention; and

[0014] FIGURE 4 illustrates schematically one embodiment of the hydrophilic crosslinked silicone rubber of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0015] The inventive hydrophilic crosslinked silicone rubbers (X) are produced in a hydrosilylation reaction between one or more reactants including aliphatic unsaturation such as ethylenic or ethytynic unsaturation, and one or more reactants including Si-H functionality (“silicone-bonded hydrogen”). The reaction is catalyzed by a hydrosilyiation catalyst, which may be, for example, a platinum compound or complex. At feast one reactant must contain a covalently bonded cyclodextrin moiety, for example a cyclodextrin derivative containing ethylenic or ethytynic unsaturation; a silicone (organopotysiloxane) reactant containing hydr os ilylat ion-reaction functionality, to which one or more cyckxtextrin groups are covalently bonded; or a silane or silicone bearing silicon bonded hydrogen to which a cyclodextrin moiety B covalently bonded.

[0016] Embodiments of the inventive hydrophilic crosslinked silicone rubber (X) comprising, besides component (E):

[0017] at least one each of compound (A), (B), and (D), or

[0018] at least one each of compound (A), (B), (C), and (D), or

[0019] at least one (C) and (D)

[0020] where

[0021] (A) is an organic compound or an organosilicon compound, containing at least two radicals with aliphatic carbon-carbon multiple bonds,

[0022] (B) is an organosilicon compound, containing at least two Si-bonded hydrogen atoms,

[0023] (C) is an organosilicon compound, containing SiC-bonded radicals with aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms,

[0024] (D) is a hydrosilylation catalyst, and

[0025] (E) is a cyclodextrin (which may be a mixture of cyclodextrins) modified to include at least one aliphatically unsaturated group such as one containing ethyknic or ethylymc unsaturation, or at least one SiH group, or a combination of at feast one aliphatically unsaturated group such as one containing ethylenic or ethytynic unsaturation and at feast one SiH group. [0026] The additkm-cross linking silicone compositions according to the invention may be single -component silicone compositions or else two- or multi-component silicone compositions.

[0027] In two-component compositions, the individual components of the compositions according to the invention can contain all of the constituents in any desired combination, generally with the proviso that one component does not simultaneously comprise sfloxanes with an aliphatic multiple bond, sibxanes with Si-bonded hydrogen and catalyst, Le. essentially not simultaneously the constituents (A), (B) and (D) or (C) and (D). However, the compositions according to the invention are preferably single -component compositions.

[0028] As is known, the compounds (A) and (B) or (C) used in the compositions according to the invention are selected such that a crosslinking is possible. Thus, for example, compound (A) has at least two aliphatically unsaturated radicals and (B) has at least three Si- bonded hydrogen atoms, or compound (A) has at least three aliphatically unsaturated radicals and sibxane (B) has at least two Si-bonded hydrogen atoms, or else instead of compound (A) and (B), sibxane (C) is used which has aliphatically unsaturated radicals and Si-bonded hydrogen atoms in the aforementioned ratios.

[0029] The compound (A) used according to the invention can be a silicon-free organic compound with preferably at bast two aliphatically unsaturated groups and can be an organosfficon compound with preferably at bast two alpha tic ally unsaturated groups, or else mixtures thereof.

[0030] Examples of silicon-free organic compounds (A) are 133- trivinylcyc lohexane, 23-dimethyl- 1,3-butadiene, 7-methyl-3-methylene-l ,6-octadiene, 2- methyl- 13-butadiene, 13-hexa diene, 1,7-octa diene, 4,7-methylene-4,7,8,9-tetrahydroindene, methylcyclopentadiene , 5-vinyl-2-norbornene, bicyclo[2.2. l]hepta-2, 5-diene, 13- diisopropenylbenzene, vinyTgroup-containing polybutadiene, 1 ,4~diviny lcyc lohexane , .13,5- triallylbenzene, 133-trivinylbenzene, 1,2,4-trivinyl-cyc lohexane, 13.5- triisopropenylbenzene, 1,4-diviny benzene, 3-methyl- heptadiene-( 1,5), 3-phenyl-hexa diene - (.1,5), 3-vinyl-hexadiene-(l 3) and 43-dime thy 1-43-diethyloctadiene-(l ,7), N,N '-methylene - bisacrylamide, 1 ,1 ,l-tris(hydroxymethyI)propane triacrylate, 1,1,1- tris(hydroxymethyI)propane trimethaciylate, tripropylene glycol diacrylate, diallyi ether, dialfylamme, diallyi carbonate, N,N'-dialtyturea, trialiylamine, tris(2-methylallyl)amine, 2,4,6- triaflyloxy- 13^-triazine, triallyl-s-tr iazine-2 ,4,6( 1 H,3 H ,5H )-tr ione , diallyi mabnate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, poly(propyiene glycol) dimethacrylate.

[0031] In addition-crosslinking crosslinked silicone rubber (X), constituent (A) may include at least one aliphaticaily unsaturated organosilicon compound, in which case all aliphatically unsaturated organosilicon compounds used to date in addition-crosslinking compositions may be employed, such as, for example, silicone polymers, copolymers and resins with vinyl functionality, silicone block copolymers with urea segments, silicone block copolymers with amide segments and/or imide segments and/or ester/amide segments and/or polystyrene segments and/or sihrylene segments and/or c arbor ane segments and silicone graft copolymers with ether groups.

[0032] The organosilicon compounds (A) that have SiC-bonded radicals with aliphatic carbon-c arbon-muh f le bonds used are preferably Bnear or branched organopolysiloxanes of units of the general formula (I)

[0033] where

[0034] R ⁴ , independently of one another, are an organic or inorganic radical free from alpha tic carbon-carbon-multip le bonds,

[0035] R ⁵ , independently of one another, are a monovalent, substituted or unsubstituted, SiC-bonded hydrocarbon radical with at least one aliphatic carbon-carbon- multiple bond,

[00361

[00371

[0038] with the proviso that the sum a+b is less than or equal to 3 and at least 2 radicals R ³ are present per molecule.

[0039] Radicals R ⁴ may be mono- or polyvalent radicals, with the polyvalent radicals, such as, for example, bivalent, trivalent and tetra valent radicals, then joining together several, for example two, three or four, sitoxy units of the formula (I). [0040] Further examples of R ⁴ are the monovalent radicals—

and SiC-bonded, substituted or unsubstituted hydrocarbon radicals

which may be interrupted with oxygen atoms or the group— C(0)— , and also bivalent radicals Si-bonded on both sides according to formula (II). If radicals R ⁴ are SiC-bonded substituted hydrocarbon radicals, preferred substituents are halogen atoms, phosphorus -contain ing radicals, cyano radicals,—

Here, R ⁶ are, independently of one another, hydrogen or a monovalent hydrocarbon radical having 1 to 20 carbon atoms, and Ph is the phenyl radical.

[0041] Examples of radicals R ⁴ are alkyl radicals such as the methyl, ethyl, n- propyl, isopropyl, n-butyL isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and tert-pentyl radicals, hexyl radicals such as the n-hexyl radical, heptyl radicals suchas the n-heptyl radical, octyl radicals such as the n-octyl radical and isooctyl radicals such as the 2,2,4- trimethy lpent y 1 radical, nonyl radicals such as the n-nonyl radical, decyl radicals such as the n-decyl radical, dodecyl radicals such as the n-dodecyl radical, and octadecyl radicals such as the n-octadecyl radical, cycloalkyl radicals such as the cyclopentyl, cyclohexyl, cycloheptyl and methykyclohexyl radicals, aryl radicals such as the phenyl, naphthyl, anthryl and phenanthryl radicals, alkaryl radicals such as the o-, m-, and p-totyrl radicals, xylyl radicals and ethyiphenyl radicals, and aralkyl radicals such as the benzyl radical, and the a- and the b-phenykthyl radicals.

[0042] Examples of substituted radicals R ⁴ are haloalkyl radicals, such as the 333- trifboro-n-propyl radical, the 2333'3\2'-hexailuoroiso propyl radical, the heptafluoroisopropyl radical, haloaryl radicals, such as the 0-, m- and p-chlorophenyl radical,

corresponds to the meaning given for them above and o and p are identical or different integers between 0 and 10.

[0043] Examples of R ⁴ being divalent radicals Si-bonded on both sides according to formula (I) are those which are derived from the monovalent examples specified above for radical R ⁴ by virtue of the fact that an additional bonding takes place by substitution of a hydrogen atom. Examples of such radicals are—

where x is 0 or 1, and Ph, o and p have the meaning

specified above.

[0044] Preferably, radical R ⁴ is a monovalent SiC -bonded, optionally substituted hydrocarbon radical having 1 to 18 carbon atoms free from aliphatic carbon-carbon-multiple bonds, more preferably a monovalent SiC -bonded hydrocarbon radical having 1 to 6 carbon atoms free from aliphatic carbon-carbon-multiple bonds, and in particular the methyl or phenyl radical.

[0045] Radical R ⁵ may be any desired groups accessible to an addition reaction (hydrosifylation) with an SiH-functional compound.

[0046] If radicals R ⁶ are SiC -bonded, substituted hydrocarbon radicals, the substituents are preferably halogen atoms, cyano radicals and — OR ⁶ , where R ⁶ has the aforementioned meaning.

[0047] Preferably, radicals R ⁵ are alkenyl and alkynyl groups having 2 to 16 carbon atoms, such as vinyl, allyi, methaflyl 1 -propenyL 5-hexenyl, ethynyl, butadienyl, hexadienyl, cyctopentenyl, cyclopentadienyl, cyclohexenyl vinylcyclohexylethyl, divinylcyc tohexy le t hy 1 , norbomenyl, viny phenyl and styryl radicals, with vinyl, allyi and hexeny! radicals being most preferably used.

[0048] The molecular weight of the constituent (A) can vary within wide limits, for example between 10 ² and 10 ⁶ gZmol. Thus, the constituent (A) can be, for example, a relatively low molecular weight alkenyl-functional oligosiloxane, such as 1,2- divinyketramethyldisiloxane, but also a highly polymeric pofydimethylsiloxane which has chain-positioned or terminal Sir-bonded vinyl groups, e.g. with a molecular weight of 10 ⁵ g/mol (number-average determined by means of NMR). The structure of the molecules forming the constituent (A) is also not fixed; in particular, the structure of a more highly molecular, le. oligomeric or polymeric siloxane, may be linear, cyclic, branched or else re sin- like, networklike. Linear and cyclic polysiloxanes are preferably composed of units of the formulae and where R ⁴ and R ⁵ have the meanings given

above. Branched and network-like polysiloxanes additionally contain trifunctional and'or tetrafunctional units, with those of the formulae and being preferred.

Mixtures of different siloxanes satisfying the criteria of constituent (A) can of course ako be used.

[0049] As component (A), particular preference is given to the use of vinyl- functional, essentially linear polydiorganosiloxanes with a viscosity of 0.01 to 500,000 Pa s, more preferably from 0.1 to 100,000 Pa s, in each case at 25° C.

[0050] As organosilicon compound(s) (B), it is possible to use all hydrogen- functional organosflicon compounds which have ako hitherto been used in addition - crosslinkable compositions.

[0051] The organopolysiloxanes (B) that have Si-bonded hydrogen atoms are preferably linear, cyclic or branched organopolysiloxanes of units of the general formula (II).

[0052]

[0053]

[0054]

[0055]

[0056] with the proviso that the sum of c+d is less than or equal to 3 and at least two Si-bonded hydrogen atoms are present per molecule.

[0057] Preferably, the organopolysiloxane (B) used according to the invention comprise Si-bonded hydrogen in the range from 0.04 to 1.7 percent by weight, based on the total weight of the organopolys iloxane (B).

[0058] The molecular weight of the constituent (B) can likewise vary within wide limits, for example between 10 ² and 10 ⁶ g/ ^' moL Thus, the constituent (B) can for example be a relatively low molecular weight SiH-functional oligosiloxane, such as tetramethyldisiloxane, but also a highly polymeric polydimethylsiloxane that has chain-positioned or terminal SiH- groups, or a silicone resin that has SiH -groups.

[0059] The structure of the molecules forming the constituent (B) k ako not fixed; in particular, the structure of a more highly molecular, ie. oligomeric or polymeric SiH- containing sfloxane may be linear, cyclic, branched or eke resin-like, network- like. Linear and cyclic polysilo xanes (B) are preferably composed of units of the formulae R^SOia, where R ⁴ has the meaning given above. Branched and

network-like polysilo xanes additionally comprise trifunctional and/or tetra functional units , preference being given to those of the formulae where R ⁴ has the

meaning given above.

[0060] It is of course also possible to use mixtures of different sfloxanes meeting the criteria of constituent (B). In particular, the molecules forming the constituent (B) can optionally additionally also contain aliphatical!y unsaturated groups in addition to the obligatory SiH-groups. Particular preference is given to the use of low molecular weight SiH- functional compounds such as tetrakis(dimethyls ilox y)s ilane and tetramethylcyclotetrasitoxane, as well as more highly molecular, SiH -containing siloxanes, such as poly(hydrogenmethy])siloxanes and poly(dmethylhydrogenmethyl)siloxanes with a viscosity at 25° C. of from 10 to 10,000 mPa-s, or analogous SiH -containing compounds in which some of the methyl groups are replaced by 33,3-trifhioropropyl or phenyl groups.

[0061] Constituent (B) is preferably present in the crosslinkable silicone compositions according to the invention in an amount such that the molar ratio of SiH-groups to aliphatically unsaturated groups from (A) is 0.1 to 20, more preferably between 1.0 and 5.0.

[0062] The components (A) and (B) used according to the invention are standard commercial products and/or can be prepared by processes customary in chemistry.

[0063] Instead of component (A) and (B), the silicone compositions according to the invention can comprise organopolysiloxanes (C) which simultaneously have aliphatic c arbon-carbon-muhiple bonds and Si-bonded hydrogen atoms. The silicone compositions according to the invention canafeo comprise all three components (A), (B) and (C).

[0064] If siloxanes (C) are used, these are preferably those of units of the general formulae (HI), (IV) and (V)

[0065] where

10066]

[0067]

10068]

10069]

[0070] with the proviso that at least 2 radicals R ^$ and at least 2 Si-bonded hydrogen atoms are present per molecule.

[0071] Examples of organopolysiloxanes (C) are those made from SO4.2, R ⁴ 3$iOi /2, and RSHSiOi/2 units, so-called MQ resins, where these resins can additionally

contain 2 and R units, as wefl as linear organopolysiloxanes essentially consisting of unis where R ⁴ and R ⁵ have the aforementioned meaning.

[0072] The organopolysiloxanes (C) preferably have an average vkcosity of from

0.01 to 500,000 Pa s, more preferably 0.1 to 100,000 Pa-s, in each case at 25° C. Organopolysiloxanes (C) can be prepared by methods customary in chemktry.

[0073] As hydrosilylation catalyst (D), it k possible to use all catalysts known to the prior art Component (D)may be a platinum group metal, for example platinum, rhodium, ruthenium, palladium, osmium or iridium, an organometallic compound or a combination thereof. Examples of component (D) are compounds such as hexachk>rop!atinic(lV) acid, platinum dichloride, platinum acetylacetonate and complexes of these compounds which are encapsulated in a matrix or a core/shell-like structure.

[0074] Platinum complexes with low molecular weight organopolysiloxanes include 13-diethenyl- 1,133-tetramethyldisiloxane complexes with platinum. Further examples are platinum phosphite complexes, platinum phosphine complexes or alky platinum complexes. These compounds may be encapsulated in a resin matrix.

[0075] Component (E) k a cyclodextrin (which may be a mixture of cyclodextrins) modified to include at least one aliphatically unsaturated group such as one containing ethylenic or ethylynic unsaturation. The cyclodextrin may also include an SiH functional group or SiH functionality and at least one aliphatically unsaturated group. Cyclodextrins are cyclic oligosaccharides constructed of w units of a-(l,4)-linked anhydroglucose unite, where w k generally from 6-10. The common cyclodextrins coitain 6, 7, a 8 anhydrogbcose units, and are referred to, respectively, as a-cyckxlextrin, b-cyclodextrin, and g -cyclodextrin, often abbreviated as a-CD, b-CD, and g-CD. Such cyclodextrins and others where w ¹ 6, 7, or B, are produced by the enzymatic conversion (“digestion”) of starch and are readily commercially available.

[0076] Due to their structure, CDs have a hydrophobic interior. Numerous molecules can enter this cavity and form stable complexes, often in stoichiometric ratios, but not always 1:1 ratios. Whether a particular molecule can be a guest molecule in suchhost/guest complexes is not always predictable, but depends upon the molecular structure of the guest molecule, its physical size, presence or absence of polar groups, etc. The cavity size of CDs increases from a to g, and larger molecules are generally more easily complexed by the CDs with larger cavities and vice versa. The complexes formed are reversible, in that the guest molecules may often be“liberated” quite easily, and it has been found that sane molecules which are notoriously thermally or oxidatively sensitive, curcumin and fish oils being examples, are rendered much more stable by being incorporated into cyclodextrin complexes . In addition, the liberated molecules may be released at a controlled rate to increase effectiveness in various applications. The guest molecules may include natural oils, pharmaceutical products, cosmetic or personal care actives, biocides, insecticides, fungicides, herbicides, pheromones, fragrances, flavorings, pigments, drugs, pharmaceutical active compounds, antigens, active compounds for antistatic finishing or flame-retardant finishing, stabilizers (UV), dyestuffs, etc.

[0077] The solubility of cyclodextrins in water is limited, and with respect to the most common cyclodextrins, a-CD, b-CD, and g-CD, ranges from 18 mg/ml for b-CD to 232 mg/ml for g-CD. Thus, CDs are much less soluble in water and polar solvents than other saccharides and oligosaccharides.

[0078] The hydrophilic crosslinked silicone rubber (X) of the present invention are prepared by incorporating cyclodextrin moieties into the rubber through a hydrosilylation reaction. There are various methods of accomplishing this. In ate method, a cyclodextrin (which may be a mixture of cyclodextrins) is modified to contain at least one aliphatic ally unsaturated group such as one containing ethylenic a ethylynic unsaturation (A). On average, the cyclodextrin can contain from 1 to 24 carbon-carbon multiple bonds, preferably 1 to 16 carbon-carbon multiple bonds, more preferably 1 to 8 carbon-carbon multiple bonds, even more preferably 1 to 3 carbon-carbon multiple bonds, still more preferably 1 to 2 carbon-carbon multiple bonds, yet more preferably from 1 to 2 or less than 2 multiple braids, and most preferably, 1 carbon-carbon multiple bond.

[0079] The organic groups which contain the carbon-carbon multiple bonds may be, and preferably are, simple alkenyl groups linked to the CDs by an ether linkage, may be a (meth)acrylate group, a maleate or fumarate group, or the Kke. Such groups may be covalently bound to one of the CD hydroxyl oxygens through arty suitable linking group, such as but not limited to, ether, ester, urethane, and urea groups. An example of unsaturation could also be a vinyl silyl group connected to the CD directly or through a tinker. The remaining unreacted CD hydroxyl groups may remain as free hydroxyl groups, or may have been derivatized or may be previously or subsequently derivatized with other groups not containing ethytenic or ethylynic unsaturation, such as methyl groups, acetate groups, etc. Derivatized CDs containing such modifying groups and other modifying groups are widely available and can be used as starting materials to form the CDs containing carbon-carbon multiple bonds.

[0080] In the context of the present invention, a“cyclodextrin derivative” is a cyclodextrin which has been derivatized by groups which are not reactive in a hydrosilylation reaction. Such groups include, but are not limited to, groups such as those previously mentioned, e.g. hydrocarbon and hydrocarbonoxy groups containing no aliphatic unsaturation. By a“modified cyclodextrin” herein is meant a cyclodextrin or cyclodextrin derivative which has been modified (functionalized) to contain a group having aliphatic unsaturation which can participate in a hydrosilylation reaction, or to contain a silyl or polyorganosiloxyl group containing silicon-bonded hydrogen.

[0081] Methods for introducing groups containing carbon-carbon multiple bonds onto CDs are known or easily formulated by a chemist. For example, the methods disclosed in M. Yin etaL, CHROMATOGRAPH1A(2003), VoL 58, p. 301, may be used. Othermethods include esterification of CD hydroxyl groups by means of an unsaturated carboxylic acid chloride, esterification by reacting with an unsaturated carboxylic acid such as (meth)aciylic acid; by esterification by reaction with an unsaturated anhydride such as maleic anhydride or acrylic anhydride; by urethanization by reaction with an unsaturated isocyanate such as vinyl isocyanate, allyl isocyanate, or isocyanatoethyl(meth)acrylate or isocyanatopropy](meth)acrylate; by reaction with an unsaturated epoxy compound, and by other reactions known to the art The number of carbon-carbon multiple bond-containing groups of the unsaturated CD (E) is limited by the number of free hydroxyl groups in principle but may also be limited in practice by steric effects. Of course, the higher the number of aliphatically unsaturated groups, the more derivatizing reagent must be used, resulting in higher cost.

[0082] A further method of incorporating CD groups by hydrosilylation is to prepare an organ opolys i loxane which is reactive in a hydrosilylation reaction by virtue of the presence of aliphatic unsaturation and/or Si-H functionality as an intermediate product, and which contains one or more covalently bonded CD groups on average. For example, an organopolysiloxane containing Si-vinyl groups or Si-H groups and ako containing a species reactive with a CD or with a CD derivative may be reacted with the CD to covalently bond the CD to the organopolysiloxane. For non-derivatized CDs or CDs which have been partially derivatized with non-interfering groups such as alkyl groups or acetyl groups, suitable reactive groups on the organopolysiloxanes include anhydride groups such as those derived from maleic anhydride, succinic anhydride, terephthalic anhydride, and phthalic anhydride groups, and other groups reactive with hydroxyl groups, such as isocyanate or epoxy groups.

[0083] If the CD has been derivatized with a group which is reactive in hydrosilylation, e.g. an aliphatically unsaturated group or a group bearing or containing an Si- H group, then an organopolys iloxane bearing complementarily reactive groups in stoichiometric excess can be used. For example, a derivatized CD bearing an aliphatically unsaturated group can be reacted with an organopolysiloxane bearing, for example, four Si-H groups, in a 1:1 mol ratio. The hydros ily la ted product will contain, on average, one CD moiety per molecule, and w¾ on average, contain three unreacted Si-H groups to be subsequently reacted to form the rubber.

[0084] Preferably, the which will participate in the reaction to form a rubber

will be CDs which have been derivatized to contain, on average, one or more aliphatically unsaturated groups, or the CD will have been covalently bonded to an organopolysiloxane bearing aliphatically unsaturated groups.

[0085] If the CD-containing component is an organopolysiloxane bearing Si-H groups or ethylenicaBy unsaturated groups, then the amount of CD moieties in the final hydrophilic crosslinked silicone rubber (X) product may be limited due to selection of the proper portions of organopolysiloxanes necessary to result in rubber formation. With“free” CDs modified to contain an aliphatically unsaturated group, the reaction k simpler, more economical, and the CD content may be varied over an extremely wide range. [0086] To catalyze the hydrosflylatkm reaction of the components (A), (B), and(E) the concentration of component (D) is sufficient to reach acceptable cure for the application. The amount of component (D) can be between 0.1 and 1000 parte per million (ppm), 0.5 and 100 ppm or 1 and 25 ppm of the platinum group metal, depending on the total weight of the component. The curing rate may be low if the constituent of the platinum group metal is below 1 ppm. The use of more than 100 ppm of the platinum group metal is uneconomical or can reduce the stability of the adhesive formulation.

[0087] The inventive hydrophilic crosslinked silicone rubber (X) may optionally include additives such as strengthening fillers as component (F). Component (F) may include fumed or precipitated silicas with BET surface areas of at least 50 m ² /g, as well as carbon blacks and activated carbons such as furnace black and acetylene black, with preference being given to fumed and precipitated silicas with BET surface areas of at least 50 m ² /g. The specified silica fillers can have a hydrophilic character or be hydrophobized by known processes. The content of actively strengthening filler (F) in the crosslinkable composition according to the invention is in the range from 0 to 70% by weight, preferably 0 to 50% by weight.

[0088] Preferably, the crosslinkable silicone compositions according to the invention are characterized in that the filler (F) has been surface-treated. The surface treatment is achieved by processes known in the prior art for the hydrophobization of finely divided fillers. The hydrophobization can take place, for example, either pries· to the incorporation into the poiyorganosiloxane or else in the presence of a potyorganosiloxane according to the in-situ process. Both processes can be carried out either in the batch process or else continuously. Hydrophobizing agents preferably used are org&nosilicon compounds which are able to react with the filler surface to form covalent bonds or are permanently physically absorbed onto the filler surface. Examples of hydrophobizing agents are alkylchlorosilanes such as methykrichlorosilane, dimethyldkh loros ilane, trimethylchlorosilane, octyltrichloros ilane, octadecyhrichloros ilane , octyhnethyldichloros ilane, octadecyhnethyldichloros ilane, octyldimethylchlorosilane, octadecyldimethylchloros ilane and tert-butytiimethylchloros ilane; a!ky!alkoxys ilanes such as dimethyldimethoxys ilane, dimethyldiethoxysilane, trimethyimethoxysilane and trimethylethoxys ilane; trimethylsilanol; cyclic d»rgano(poly)s iloxanes such as octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane; linear diorganopotys iloxanes such as dimethylpolys iloxa ne s with trimethylsiloxy end groups, and dimethylpolys iloxanes with silanol or a!koxy end groups; disilazanes such as hexaalkyldisilazanes, in particular hexamethyldisilazane, diviny htetramethyldisilazane , bis(trifluoropropy l)tetramethy ldisilazane; cyclic dimethylsilazanes, such as hexamethylcyclotrisilazane. It is also possible to use mixtures of the hydrophobizing agents specified above. In order to increase the rate of the hydrophobization, catalytic ally active additives, such as, for example, amines, metal hydroxides and water, can also optionally be added.

[0089] The hydrophobization can take place, for example, in one step using one hydrophobizing agent or a mixture of several hydrophobizing agents, but also using one or more hydrophobizing agents in several steps.

[0090] As a consequence of a surface treatment, preferred fillers (F) have a carbon content of at least 0.01 to at most 20% by weight, preferably between 0.1 and 10% by weight, and more preferably between 0.5 to 5% by weight. Particular preference is given to crosslinkable silicone compositions which are characterized in that the filler (F) is a surface - treated silica having 0.01 to 2% by weight of Si-bonded, aliphatically unsaturated groups. For example, these may be Si-bonded vinyl groups. In the silicone composition according to the invention, the constituent (F) is used preferably as an individual filler or likewise preferably as a mixture of several finely divided fillers.

[0091] The silicone conopositions according to the invention can, if desired, may include further additives (G) in a fraction of up to 70% by weight, preferably 0.0001 to 40% by weight These additives (G) may be e.g. inactive fillers, resin-like polyorganosiloxanes which are different from the siloxanes (A), (B), and (C) and may include fungicides, fragrances, rheological additives, inhibitors and stabilizers for the targeted adjustment of processing time, onset temperature and crosslinking rate, corrosion inhibitors, oxidation inhibitors, Kght protection agents, flame retardants and agents for influencing the electrical properties, dispersion auxiliaries, solvents, adhesion promoters, pigments, dyes, plasticizers, organic polymers, heat stabilizers etc. These include additives such as quartz flour, diatomaceous earth, clays, chalk, lilhopone, graphite, metal oxides, metal carbonates, metal sulfates, metal salts of carboxylic acids, metal dusts, fibers, such as glass fibers, plastic fibers, plastic powders, metal dusts, dyes, pigments, etc.

[0092] Moreover, these fillers may be heat-conducting or electrically conducting. Examples of heat-conducting fillers are aluminum nitride; aluminum oxide; barium titanate; beryllium oxide; boron nitride; diamond; graphite; magnesium oxide; particulate metals such as, copper, gold, nickel or silver; silicon carbide; tungsten carbide; zinc oxide, and combinations thereof. Heat-conducting fillers are known in the prior art and are commercially available. For example, CB-A20S and Al-43-Me are aluminum oxide fillers in different particle sizes which are commercially available from Showa-Denko, and AA-04, AA-2 and AA18 are aluminum oxide fillers which are commercially available from Sumitomo Chemical Company. Silver fillers are commercially available from Metalor Technologies U.S.A. Carp, of Attleboro, Mass., U.S.A. Boron nitride fillers are commercial^ available from Advanced Ceramics Corporation, Cleveland, Ohio, U.S.A. It is also possible to use a combination of fillers with different particle sizes and different particle size distribution.

[0093] The silicone composition can additionally optionally comprise a solvent (H). However, it should be ensured that the solvent (H) has no disadvantageous effects on the overall system, and that the solvent (H) has no disadvantages with respect to skin contact and curing. Suitable solvents (H) are known in the prior art and are commercially available. The solvent (H) can be, for example, an organic solvent having 3 to 20 carbon atoms. Non-limiting examples of solvents (H) include aliphatic hydrocarbons such as nonane, decalin and dodecane; aromatic hydrocarbons such as mesitylene, xylene and toluene; esters such as ethyl acetate and butyrolactone; ethers such as n-butyl ether and polyethylene glycol monomethyl ether; ketones such as methyl isobutyl ketone and methyl pentyl ketone; silicone fluids such as linear, branched and cyclic polydimethy Is iloxa nes, and combinations of these solvents. The optimum concentration of a specific solvent (H) in the silicone composition can be determined easily by means of routine experiments. Depending on the weight of the compound, the amount of solvent (H) can be between 0 and 95% or between 1 and 95%. In some embodiments, it is desired to a volatile solvent such that after initial curing, the resulting hydrophilic silicone rubber may include from about 0 to about 5 weight percent based on the total weight of all components of the silicone rubber, and preferably from 0% to 1%, and more preferably from 0% to about .1%.

[0094] The hydrophilic crosslinked silicone rubber (X) may optionally include hydros flyation inhibitors and stabilizers (I). Inhibitors and stabilizers (1) serve for the targeted adjustment of the processing time, onset temperature and crosslinking rate of the silicone compositions according to the invention. These inhibitors and stabilizers have been known for a long time in the prior art. Examples of customary inhibitors are acetylenic alcohols, such as 1 -ethynyl-l-cyelohexanol, 2-methyl-3-butyn-2-ol and 3,5-dimethyl- l-hexyn-3-ol, 3-methyl- 1 - dodecyn-3-ol, polymethylvinylcyc lositoxanes such as 1,3,5, 7- tetravinyltetramethyltetracyclosiloxane, low molecular weight silicone oils with methylvinyl- SiOi/2 groups and/or RavinySiOi^ end groups, such as divinyltetrametiiyldisiloxane, tetravinyldimethy ldis iloxane , trialkyl cyanurates, alkyl maleates, such as diallyl maleates, dimethyl male ate and diethyl maleate, alkyl fumarates, such as diallyl fumarate and diethylfumarate, organic hydroperoxides such as cumene hydroperoxide, tert-butyl hydroperoxide and pinane hydroperoxide, organic peroxides, organic sulfoxides, organic amines, diamines and amides, phosphates and phosphites, nitriles, triazoles, diaziridines and oximes. The effect of these inhibitor additives depends on their chemical structure, meaning that the concentration has to be determined individually. Inhibitors and inhibitor mixtures are preferably added in a quantitative fraction of from 0.00001% to 5%, based on the total weight of the mixture, preferably 0.00005 to 2% and more preferably 0.0001 to 1%.

[0095] The reaction temperature of the inventive hydrophilic silicone rubber (X) is preferably from room temperature to about 220°C, more preferably 50 - 2Q0°C, and most preferably from 50 - 190°C. The particular temperature used may reflect thermal sensitivities of ingredients used. In general, lower temperatures require longer reaction times and/or greater amounts of catalyst, and vice versa. At temperatures in the range of 70 - 90°C, the reaction generally takes several minutes to several hours. At temperatures in the range of 160 ~190°C, the reaction generally takes seconds.

[0096] The amounts of reactants (A), (B), and (E), and optionally (C) can be varied with respect to each other, as long asa cured rubber is produced. For example, greater amounts of the cyclodextrin-containing component (E) confer greater hydrophilic ity and water absorption properties. The amounts of aliphaticaily unsaturated components, e.g. components (E) (when component (E) is aliphatical!y unsaturated) and (A) relative to the amount of crosslinker (B) are dependent upon the molecular weight and functionality of the respective components. In general, to achieve crosslinking as opposed to only chain extension, the sum of the average functionality of the aliphatically unsaturated components and the average functionality of the Si-H functional components should be > 4, preferably > 5. With the exception of the cyclodextrin component (E), ft is desirable that the average functionality of the other reactive components each be greater than 2. If the total average functionality is not high enough, or if the average functionality of components (A) and/or (B) is/are not high enough, then a cured rubber cannot be formed due to inadequate crosslinking. The relative amounts are able to be determined by one of ordinary skill in the art. Further guidance may be found in U.S. patents, 5,391,592, 5,811,487, 6365,670, 6,423322, and 6,881,416, which are incorporated herein by reference. It should be noted that if the CD component (E) contains more than one aiiphaticaiiy unsaturated group, then this component may also contribute to crosslinking, and thus the functionalities of components (A) and/or (B)may be reduced.

[0097] The inventive hydrophilic crosslinked silicone rubber (X) is useful in a variety of applications where hydrophilic properties are desired. The water uptake of the inventive silicone rubber can be adjusted depending on the application need. In some embodiments, the water uptake of the inventive silicone rubber may be between 3% and about 1000%, more preferably between 20% and 500%, and in other embodiments preferably between 50% and about 350%.

[0098] The inventive silicone rubbers having hydrophilic properties are useful for a variety of applications that require moisture control, low coefficients of friction and resistance to protein adhesion. These properties are useful in wound care, catheters, body implants and other medical devices, as well as other products that desire the advantages of silicone rubber and hydrophilic properties, The use of silicone rubber also allows for a variety of manufacturing methods to be employed, such as molding, injection molding, thin film, coating, and 3D printing processes.

[0099] In applications, such as drug delivery the present application may utilize the cavity present in the CD. The CD can form stable complexes, where a guest molecule B hosted in the cavity in the CD. The complexes that are formed are reversible such that the guest molecule may be released from the CD in a controlled manner. Accordingly, the inventive hydrophilic silicone rubber composition disclosed herein can be used to host a drug for delivery and release this drug in a controlled manner for effective delivery.

[0100] However, many applications exist where hydrophilic properties are desired. The moisture management capabilities provided by the inventive hydrophilic compositions is desired in skin contact and medical applications (e.g., wound care applications) to keep and draw moisture, sweat and exudates away from the body. The inventive ydrophilic materials also exhibit a low coefficient of friction useful in applications such as catheters. The resistance to protein adhesion provided by hydrophilic materials is beneficial in body implants and other types of medical devices. Hydrophilic materials are also advantageous in anti-static articles.

[0101] In one embodiment, the inventive hydrophilic crosslinked silicone rubber is made by reacting an Si-H containing silicone with undecenoyl modified cyclodextrin to provide a cross-linked structure; a simplified scheme B shown in Figure 1. [0102] The undecenoyl modified cyclodextrin can be made by reacting some of the OH groups of a cyclodextrin with undecanoyl chloride as shown in Figure 2.

[0103] The starting cyclodextrin can be a modified or unmodified o, b, g cyclodextrin. An example of unmodified b cyclodextrin is CAVAMAX* W7 from Wacker Chemie AG. An example of modified b cyclodextrin is CAVASOL* W7 M from Wacker Chemie AG, which is a methyl modified b cyclodextrin (1.6-1.9 OH groups per glycoside unit are nxxlified with methyl groups); structure is shown below:

[0104] An example of SH containing silicone is poly(dimethylsiloxane-co - methylhydros iloxane) having the formula MDxD^M, where x +y = approx.140; xy = approx.

2:1.

[0105] In another exemplary embodiment of the hydrophilic crosslinked silicone rubber, a cyclodextrin is first modified by reacting with a vinyl silicone containing anhydride functionality. This process results in a CD derivative where the CD unit is connected to the vinyl silicone unit through an ester bond. This modified cyclodextrin is used in a crosslinking composition, afeo containing an SiH functional silicone, to form a cured rubber as shown in Figure 3.

[0106] In still another exemplary embodiment, an aBkene modified cyclodextrin (e.g., the undecenoyl modified cyclodextrin discussed above) is first reacted with excess amount of a hydrido functionalized silicone to produce a cyclodextrin derivative that has pendant SiH groups. This modified cyclodextrin is used in hydrosilylation reaction with a vinyl silicone to produce crosslinked rubber as shown in Figure 4.

[0107] The crosslinked silicone rubber (X) made according to the invention are hydrophilic as demonstrated by absorption of water during the water uptake test as well as lower values of contact angles. Similar compositions that do not include cyclodextrin do not exhibit hydrophilic ity or have much lower hydrophilicity and wateruptake. Also, compositions that do not use reactive cyclodextrin components experience separation of cyclodextrin from the composition matrix when immersed in water.

[0108] Synthesis Examples:

[0109] For Examples 1, 2 and 3 undecenoyl modified methyl b-cyclodextrin CH- 18 was used, which was prepared by modifying methyl b -cyclodextrin CAVASOL ^® W7 M obtained from Wacker Chemie AG.

[0110]

[0111]

follows:

[0112] Pyridine (253.6 g) was added into a 500 mL round-bottomed flask, stared with a magnetic stirrer, and heated to 65 ^* C. Methyl b-cyclodextrin CAVASOL ^® W7 M (54.8 g, 41.8 mmol, dried in a desiccator prior to use) was added to the flask over 10 min with continuous stirring. A slightly turbid mixture was formed. The mixture was heated to 65 ° C, and undecenoyl chloride (31.0 g, 151 mmol) was added drop-wise over 1 h at 65 ° C. After the addition was complete, the reaction mixture was left stirring under heating at 65 °C for 3 hours. After 3 hours, the reaction mixture was cooled down to room temperature, poured into 1 L water, stirred and allowed to settle. The aqueous layer was decanted off from the top, and the dark brown bottom layer was further washed repeatedly with 1 ,5 L water to get a viscous liquid. The viscous material was thoroughly dried under reduced pressure to obtain a glassy material, which was ground to obtain 50.7 g of off-white powder. The Ή HMR analysis confirmed the product to be undecenoyl modified methyl b-CD. The approximate structure (0.38 undecenoyl group cm average per glycoside unit, Iodine number: 48.5 g iodine/lOO g sample) is shown below:

[0113] Measurement of water uptake for cured rubber:

[0114] A weighted sample of cured rubber was placed in deionized water and container was covered to prevent evaporation or contamination. After at least twenty-four (24) hours, the sample was removed from the water, gently patted dry with a paper towel to remove excess droplets on the surface and weighed to determine the change in mass. The water uptake results are reported as the change in mass divided by the original sample mass, in weight percent

[0115] Contact angle measurement:

[0116] Contact angles for water droplets were measured with a Data Physics OCA 50 measuring device. The values represent the average of three measurements with the standard deviation indicated in the parentheses. [0117] TABLE I: Examples of the inventive hydrophilic crossiinked silicone rubber and comparative example.

[0118] 1 pre-dissolved in 5.60 g ethyl acetate to make 50% w/w solution.

[0119] ² pre-dissotved in 2.81 g ethyl acetate to make 70% w/w solution.

[0120] ³ pre-dissolved in 2.60 g ethyl acetate to make 70% w/w solution.

[0121] ⁴ vinyl terminated polydimethybiloxane with average viscosity of 980 mPa.s and average vinyl content of 0.90 mol%.

[0122] ⁵ divinyl tetramethyl disiloxane platinum complex diluted in vinyl terminated polysilo xane (1% w/w Pt content)

[0123] For inventive example 5, a vinyl silicone functionalized cyclodextrin SB125 was used, which was synthesized by reacting CAVASOL® W7 M and an anhydride functional vinyl silicone (PY2920) having the following approximate structure:

[0124] Synthesis of vinyl silicone linked cyclodextrin derivative SB 125:

[0125] CAVA SOL* W7 M 10.0 g (7.63 mmol), dimethyl aminopyridine (DMAP, 0.19 g, 1.53 mmol) and anhydride functional vinyl sflicone PY2920 (128.5 g) were dissolved in dichloromethane (300 mL) and mixed for 48 h. Water (100 mL) was added to the mixture, and the mixture was extracted three times with 10% NaHS04 solution (150 mL each time). The combined dichloromethane layer was dried over sodium sulfate, filtered and the solvent was removed under reduced pressure to obtain a pale yellow opaque viscous liquid (Yield: 76.9 g). The product was characterized by Ή NMR and 1R. Iodine number: 7.7 g iodine/100 g material

[0126] TABLE II: Examples of the inventive hydrophilic crosslinked silicone rubber and comparative example.

[0127] 1 divinyl tetramethyl disfloxane platinum complex diluted in vinyl terminated polysfloxane (1% w/w Pt content)

[0128] For example 7, a silicone hydride functionalized cyclodextrin CH23-2 was used, which was synthesized by reacting undecenqyl modified methyl b -cyclodextrin CH-18 and a hydride terminated silicone (XL27) having the following approximate structure: H- (SiMcaOXSiMea-H (x ~50); 0.053 weight % Si-bound H.

[0129] Synthesis of Si-H functionalized cyclodextrin derivative CH23-2:

[0130] Undecenoyl methyl b-cyckxiextrin CH-18 (10.0 g, 19.7 mmol vinyl groups), prepared according to the previously mentioned method, and toluene (230 mL) were mixed with a magnetic stirrer until the CD dissolved. The mixture was heated to 60 °C and Platinum Catalyst (0.2831 g), at 1% w/wPt content was added. XL27 (75.6 g, 39.4 mmol silicon bound hydrogen) was added with stirring, and the mixture was heated at 80 °C for 2.5 h. The golden solution was cooled to room temperature and the solvent was removed under reduced pressure with a rotary evaporator to get the product as a light brown viscous fluid (44.9 g). The ^l H NMR indicated complete reaction of the vinyl groups. Because of the stoichiometric excess of SiH used during the reaction, the modified CD derivative contains residual SiH functionality on the silicone chain. This intermediate was used for example 7.

[0131] TABLE III: Examples of the inventive hydrophilic crosslinked silicone rubber and comparative example.

[0132] ¹ a small amount of toluene was used to dilute the CD derivative CH 23-2.

[0133] ² vinyl terminated polydimethy Is iloxane with average viscosity of 325 mPa.s and average vinyl content of 1.45 mol%.

[0134] ³ divinyl tetramethyl disiloxane platinum complex diluted in vinyl terminated polysiloxane (1% w/w Pt content)

[0135] The modified cyclodextrin derivatives were mixed with various siloxanes having terminal or pendant SiH groups or siloxanes containing vinyl groups under different conditions, and the resulting mixtures were cured by using a platinum containing catalyst. The cyclodextrin derivative was dissolved in a volatile solvent in some cases; the solvent got removed at elevated temperature during the curing process. Different mixing and curing conditions are shown in Table 1. The mixing was usually done in a Speedmixer™ or a Dispermat™, and the curing was done by pouring the mixture in an aluminum Petri dish and placing in an oven or a vacuum oven.

[0136] It can be seen from the above tables that inventive Examples 1, 2, 3, 5, and 7 provided cured material with hydrophilicity as shown by water uptake. Comparative Example 4, which was without any cyclodextrin incorporation , showed no hydrophilicily. Comparative Example 8 that used unmodified CAVA SOL* W7 M did not produce a cured material, and water uptake was not measured. Comparative Example 6 that used unmodified CAVASOL* W7 M produced a cured but inhomogeneous material, however, the cyclodextrin started to separate out after immersion in waterbecause it was not chemically bound to the rubber matrix. Also, in general, the inventive examples show lower water contact angles relative to the comparative examples, which is indicative of their hydrophilic properties.

[0137] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative bass for teaching one skilled in the art to variously employ the present invention.

[0138] While exemplary embodiments are described above, it is not intended that these embodiments describe a 11 possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.