Synthesis and cationic photopolymerization of monomers based on nopol

Starting with nopol [(R)-(−)-2-(2′-hydroxyethyl)-6,6-dimethyl-8-oxatricyclo[3.1.1.12,3]octane, I] as a substrate, two new, interesting monomers, allyl nopol ether epoxide III and nopol 1-propenyl ether epoxide IV, were prepared. The photoinitiated cationic polymerizations of these two monomers as well as several other model compounds were studied using real-time infrared spectroscopy. Surprisingly, the rates of epoxide ring-opening polymerization of both monomers were enhanced as compared to those of the model compounds. Two different mechanisms which involve the free radical induced decomposition of the diaryliodonium salt photoinitiator were proposed to explain the rate acceleration effects.