Hydrogels based on hydrophilic side‐chain siloxanes

Abstract

AbstractMethacrylate end‐capped diethylene glycol propyl methyl ether, 5‐hexyl‐1,2‐diol, and 3‐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, and propane diol side‐chain siloxanes was accomplished in two relatively simple synthetic steps: The first step consisted of the acid‐catalyzed co‐ring opening polymerization of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, and 1‐3‐bis‐methacryloyl‐butyltetramethyldisiloxane, followed by a platinum‐catalyzed hydrosilation with (in separate experiments) diethylene glycol allyl methyl ether, trimethylsilyl protected 3‐allyloxy‐1,2‐propane diol, and trimethylsilyl protected 5‐hexene‐1,2‐diol. The trimethylsilyl protecting groups was removed using a 10% 0.1N HCl solution in 2‐propanol. Radical polymerization of the methacrylate end‐capped ether, hexane, and propane diol side‐chain siloxanes with hydrophilic monomers, such as dimethylacrylamide, and a strengthening agent, isobornylmethacrylate, resulted in transparent hydrogels possessing a wide range of water contents, high oxygen permeability, and a low modulus of elasticity and, for the propane diol side‐chain siloxanes, excellent hydrolytic stability. The ether side‐chain siloxane‐based hydrogels exhibited poor hydrolytic stability. © 1995 John Wiley & Sons, Inc.