LIVING FREE-RADICAL POLYMERIZATION IN WATER USING DITHIOESTER AS CHAIN TRANSFER AGENT

Butyl methacryle(BMA), butyl acrylate(BA) and vinyl acetate(VAc) were polymerized by controlled/living radical polymerization in water using reversible addition fragmentation chain transfer(RAFT process). 1 phenylethyl dithiobenzoate (PhC(S)SCH(CH 3)Ph) was selected as dithioester chain transfer agent, 2,2′ azobis(2 cyanopropane)(AIBN) and ammonium peroxysulfate(APS) were used as initiator respectively. The best ratio of chain transfer agent to initiator for controlling polymer molecular weight and molecular weight distribution was 3.3 ～ 4.0 . The living character of the RAFT process in water was also indicated by the narrow polydispersity product( 1.1 ～ 1.3 ), a linear molecular weight conversion profile, the predictability of the molecular weight from the ratio of monomer consumed to chain transfer agent. By contrast, AIBN was more effective than APS for living radical polymerization in water using reversible addition fragmentation chain transfer, VAc did not polymerize well in this system. The effects of the ratio of chain transfer agent to initiator, surfactants and the amount used on the polymer molecular weight and molecular weight distribution were discussed.