HYDROGELS BASED ON HYDROPHILIC SIDE-CHAIN SILOXANES

Methacrylate end-capped diethylene glycol propyl methyl ether, 5-hexyl -1,2-diol, and 8-propyloxy-1,2-propane diol side-chain siloxanes were evaluated for potential use as hydrogels for contact lens application. The preparation of the methacrylate end-capped ether, hexane diol, an d propane diol side-chain siloxanes was accomplished in two relatively simple synthetic steps: The first step consisted of the acid-catalyze d co-ring opening polymerization of octamethylcyclotetrasiloxane, tetr amethylcyclotetrasiloxane, and 1-3-bis-methacryloylbutyltetramethyldis iloxane ,followed by a platinum-catalyzed hydrosilation with (in separ ate experiments) diethylene glycol allyl methyl ether, trimethylsilyl protected 3-allyloxy-1,2-propane diol, and trimethylsilyl protected 5- hexene-1,8-diol. The trimethylsilyl protecting group was removed using a 10% 0.1N HCl solution in X-propanol. Radical polymerization of the methacrylate end-capped ether, hexane, and propane diol side-chain sil oxanes with hydrophilic monomers, such as dimethylacrylamide, and a st rengthening agent, isobornylmethacrylate, resulted in transparent hydr ogels possessing a wide range of water contents, high oxygen permeabil ity, and a low modulus of elasticity and, for the propane diol sidecha in siloxanes, excellent hydrolytic stability. The ether side-chain sil oxane-based hydrogels exhibited poor hydrolytic stability. (C) 1995 Jo hn Wiley and Sons, Inc.