Radical polymerization kinetics of poly(ethylene oxide) macromonomers

Radical polymerization of poly(ethylene oxide) macromonomers carrying a methoxy group on the one end and a p-vinylbenzyl or a (p-vinylphenyl)butyl group on the other end was investigated in benzene and water. The overall rate of polymerization was found to be more than 50 times higher in water than that in benzene. Apparent rate constants of propagation and termination were evaluated based on ESR measurements under irradiation, while initiator efficiency was estimated from inhibition period measurements. Very rapid polymerization in water was then reasonably attributed to a combined result of locally concentrated propagating radicals and monomers in their micellar organization, together with high initiator efficiency, enhanced rate of propagation, and reduced rate of termination there.