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Abstract

Described is a polymerizable organic composition comprising: (a) a radically polymerizable gel-free prepolymer of (i) at least one first polymerizable monomer having at least two radically polymerizable ethylenically unsaturated groups, e.g., divinyl benzene, and (ii) at least one first polythiol monomer having at least two thiol groups, e.g., thioglycerol bis(mercaptoacetate); and (b) at least one second polymerizable monomer having at least two radically polymerizable ethylenically unsaturated groups, e.g., divinyl benzene and/or methacrylic anhydride, the first and second radically polymerizable monomers each being substantially free of norbornene groups. The molar equivalent ratio of ethylenically unsaturated groups of (a)(i) to the thiol groups of (a)(ii) is no greater than 1:1. The described polymerizable composition has reduced shrinkage, and a polymerizate prepared therefrom has a refractive index of at least 1.57 and an Abbe number of at least 33.

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First Claim