Synthesis of poly(vinyl acetate-co dibutyl maleate)-b-poly(dimethylsiloxane) block terpolymers by iodine transfer radical polymerization

Iodine transfer radical homo- and copolymerization (ITP and ITCP) of vinyl acetate (VAc) with dibutyl maleate (DBM) in bulk, initiated by 2,2׳-azobis(isobutyronitrile) (AIBN) at 80 oC, has been successfully performed in the presence of an ω-iodo-poly(dimethylsiloxane) (PDMS) macrotransfer agent. The formation of a diblock copolymer PDMS-b-PVAc and block terpolymer PDMS-b-P(VAc-co-DBM) has been evidenced by 1H-NMR and gel permeation chromatography (GPC) analyses. 1H-NMR results showed that the iodo-terminated chain ends were unstable and decomposed to aldehyde moieties. Moreover, GPC results showed this degradation in the copolymerization of Vac and DBM caused block terpolymer PDMS-b-P(VAc-co-DBM) and copolymer of VAc/DBM were simultaneously formed. In comparison of ITP of Vac/DBM with ethyl iodoacetate as transfer agent different bihavior was observed in ITP of Vac/DBM with PDMS. It was found that increase the amount of DBM in the initial feed caused to conversion and molecular weight increased while molecular weight distribution decreased.