Interaction of epoxy and vinyl ethers during photoinitiated cationic polymerization

A kinetic study of the independent and simultaneous photoinitiated cationic polymerization of a number of epoxide and vinyl (enol) ether monomer pairs was conducted. The results show that, although no appreciable copolymeriza tion takes place, these monomers undergo complex interactions with one anot her. These interactions are highly dependent on the epoxide monomer employe d. In all cases, the rate of epoxide ring-opening polymerization is acceler ated, whereas that of the vinyl ether is depressed. When highly reactive cy cloaliphatic epoxides are subjected to photoinitiated cationic polymerizati on in the presence of vinyl ethers, the two polymerizations proceed in a se quential fashion, with the vinyl ether polymerization taking place after th e epoxide polymerization is essentially complete. A mechanism involving an equilibration between alkoxy-carbenium and oxonium ions has been proposed t o explain the results. In addition, the free-radical-induced decomposition of the diaryliodonium salt photoinitiator also takes place, leading to a de crease in the induction period. (C) 1999 John Wiley & Sons, Inc.