Patent ID: 8318832

Claim:
A polymer that comprises: (a) one or more alkoxyalkyl methacrylate monomers and/or one or more alkoxyalkyl acrylate monomers that are incorporated in the polymer, wherein at least one of the monomers incorporated into the polymer is ethoxyethyl methacrylate; (b) one or more hydroxyalkyl methacrylate monomers and/or one or more hydroxyalkyl acrylate monomers that are incorporated in the polymer; and (c) one or more crosslinking agents that are incorporated in the polymer, wherein the total combined weight of the one or more alkoxyalkyl methacrylate monomers and the one or more alkoxyalkyl acrylate monomers ranges from 87 percent to 98 percent based on the total weight of the dry polymer, and the total combined weight of the one or more hydroxyalkyl methacrylate monomers and the one or more hydroxyalkyl acrylate monomers ranges from 1.5 percent to 12 percent based on the total weight of the dry polymer, (c1) wherein the one or more crosslinking agents comprises an incorporated di-functional methacrylate and/or di-functional acrylate crosslinking agent in an amount ranging from 0.085 percent to 0.2 percent based on the total weight of the dry polymer; (c2) an incorporated multi-functional methacrylate and/or multifunctional acrylate crosslinking agent in an amount ranging from 0.4 percent to 1 percent based on the total weight of the dry polymer; wherein the ratio of c1 di-functional to c2 multi-functional crosslinking agents is 1:4 to 1:6, and wherein the polymer is prepared by polymerization without solvent and in a mold.