Controlled grafting of poly(vinyl acetate) onto starch via RAFT polymerization

A structure-exact starch-based xanthate agent was prepared and used as chain transfer agent to mediate RAFT polymerization of vinyl acetate, which offered a convenient way to well control the structure and composition of starch-g-poly(vinyl acetate). The structures of the intermediate and the polymer were verified with FTIR and 1H-NMR. Gel permeation chromatography measurement results indicated that the polymerization was performed as expected. It was found that the relationship between number average molecular weight and monomer conversion was linear. The polydispersity index of grafted side-chain ranged from 1.19 to 1.53 and most of them were around 1.2. There was one more degradation stage appeared on the thermogravimetric analysis profile of starch-g-poly(vinyl acetate) than that of starch. TEM observation exhibited that the product was able to self-assemble into micelles in aqueous solution, which suggested the copolymer was amphiphilic. Both the thermal and amphiphilic properties demonstrated the starch-g-poly(vinyl acetate) was successfully synthesized as well. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012