Synthesis of activated monomers for cationic photopolymerization

A series of novel cationically photopolymerizable epoxide and vinyl ether monomers bearing substituted benzyl ether groups were prepared. Monomers with one methoxy, methylenedioxy, and three methoxy groups on the aromatic ring of the benzyl ether group were synthesized by straightforward methods. Kinetic studies using real-time infrared spectroscopy of the cationic photopolymerizations of these novel monomers showed that those monomers with one and two electron-donating substituents exhibit elevated rates of photopolymerization. A mechanism has been proposed involving a redox interaction between the monomer and the photoinitiator to account for the observed results. Photoinduced chain decomposition of the photoinitiator gives rise to photoamplification effect that generates a large number of carbocation species that initiate polymerization.