Optically clear reinforced silicone elastomers of high optical

Abstract

Optically clear, reinforced cross-linked silicone elastomers of the invention contain 12 to 18 mol percent of aryl substituted siloxane units of the formula R.sub.4 R.sub.5 -SiO, end blockers containing silioxane units of the formula R.sub.1 R.sub.2 R.sub.3 -S:O.sub.0.5, and dialkyl siloxane units of the formula R.sub.6 R.sub.7 -SiO. R.sub.1 and .sub.2 are alkyl, aryl or substituted alkyl or substituted aryl groups, and R.sub.3 is an alkenyl group. R.sub.4 and R.sub.5 are phenyl or mono lower alkyl substituted phenyl groups. R.sub.6 and R.sub.7 are methyl or ethyl groups. The polymer has a degree of polymerization between 100 to 2000, and preferably approximately 250. The polymer also contains trimethyl silyl treated silica as a reinforcer in the weight ration of approximately 15 to 45 parts of reinforcer to 100 parts of the polymer. After cross-linking, the polymer has properties of an optical refractive index which is at least 1.44, a type A durometer hardness of at least 35, tensile strength of at least 500 psi and tear strength of at least 20 pli. The foregoing properties render the cross-linked polymer especially suitable for forming the bodies of intraocular lenses.