Mechanistic study of the light-induced copolymerization of maleimide/vinyl ether systems

Abstract

Real-time infrared spectroscopy was used to monitor the high-speed copolymerization of N-subsituted alkyl maleimide (MI) and vinyl ether (VE) mixtures upon UV exposure, with or without photoinitiator. The monomer feed composition was shown to play a decisive role on the polymerization kinetics of each monomer. When VE is in excess, the two monomers disappear at similar rates to yield an alternating copolymer. When MI is in excess, the copolymerization and the MI homopolymerization occur simultaneously to yield a copolymer with isolated VE units. The reaction scheme proposed to account for the kinetic data is based on the homopolymerization of donor-acceptor complex, with the VE . radicals acting as the main propagating species. The kinetic chain length was evaluated from quantum yield measurements performed under controlled initiation conditions and found to be on the order of 10 3 . The propagation rate constant of the VE/MI copolymerization was calculated to be twice that of the MI homopolymerization.