Starch-graft-poly(methyl acrylate) copolymer: the new approach to synthesis and copolymer characterization

The two-stage method for poly(methyl acrylate) grafting starch using triethylborane and 1,4-benzoquinone has been developed. The first stage was borylation of alcohol groups of starch. The second stage was polymerization of methyl acrylate in the inhibitor - 1,4-benzoquinone - presence accompanied by the SH2-substitution at the boron atom. The advantages of developed method were the homogeneity of the process, the high yield of graft-copolymer, the possibility to control of chain length of synthetic polymer, and the absence of homopolymer in the final product. The molecular weight characteristics of starch-graft-poly(methyl acrylate) copolymer was determined by gel-permeation chromatography. The evidence of the graft-copolymer formation was 11B nuclear magnetic resonance data and its glass-transition temperature. The resulting graft-copolymer has an amphiphilic nature and a high thermal stability compared to the corresponding homopolymers (starch and poly(methyl acrylate)). According to the calculated values of the surface Gibbs energy the surface of starch-graft-poly(methyl acrylate) films is characterized as a high-energy surface.