Copolymerization of methyl methacrylate with unsaturated esters of granular starch

Methyl methacrylate readily copolymerizes with methacrylate ester groups present at a degree of substitution of about 0.1 in granular starch. This is shown by ( 1 ) over 50% grafting efficiency by initiation with azoisobutyronitrile; ( 2 ) higher grafting efficiency with than without the methacrylate groups when initiation is by peroxide; ( 3 ) crosslinked structure of the copolymers obtained; ( 4 ) crosslinks which persist in the PMMA recovered after acid hydrolysis to remove starch. By the same set of criteria, maleate half‐ester groups in granular starch copolymerize with methyl methacrylate hardly at all.