Effect of introducing a cationic system into a thiol-ene photopolymerizable formulation

Hybrid materials derived from a thiol-ene and cationic polymerization were obtained from concomitant polymerization. The hybrid materials were cured by both photopolymerization and thermally induced polymerization. The kinetics of the photopolymerization were measured using time resolved-IR and optical pyrometry. The nucleophilic character of the polysulfide obtained initially in the thiol-ene polymerization inhibited the development of the cationic photoinitiated polymerization of epoxy monomers. Besides, the epoxide groups underwent a proton catalyzed addition reaction with the thiols to form new sulfides groups in the reaction mixture. It is proposed that the formed sulfides can terminate the growing polyether chains forming dormant species like trialkylsulfonium salts. These salts promote the thermal polymerization of the epoxy monomer in a post treatment, producing hard and transparent materials. (c) 2007 Wiley Periodicals, Inc.