Synthesis of hybrid methacrylate-silicone-cyclohexanepoxide monomers and the study of their UV induced polymerization

The synthesis of two hybrid methacrylate-silicone-epoxycyclohexane monomers is described. These monomers were prepared by sequential hydrosilation reactions attaching first the 4-vinyl- 1-cyclohexene 1,2-epoxide, using the Wilkinson catalyst, and then the allyl methacrylate in the presence of chloroplatinic acid as catalyst for the hydrosilation reaction. The reactivity of these monomers was evaluated by RT-Fr-IR finding that the methacrylate groups can be photopolymerized concomitantly with the epoxide groups using only a diaryliodonium salt as photoinitiator, in air-free conditions. The addition of a free radical photoinitiator helps to overcome the oxygen inhibition when the radical photopolymerization is performed in air. The films obtained from these monomers were almost totally crosslinked with T-g's of 54 and 31 degrees C for EM2Si and EM4Si, respectively. It was found that the film made with the monomer with a longer siloxane chain exhibited a higher contact angle as a direct result of the higher hydrophobic surface. (C) 2006 Elsevier B.V. All rights reserved.