Synthesis and properties of graft copolymers based on poly(3-hydroxybutyrate) macromonomers.

Graft copolymers of poly(methyl methacrylate) with poly(3-hydroxybutyrate), PHB, segments as long side chains were prepared by the macromonomer method. PHB macromonomers were prepared from the esterification of oligomers with 2-hydroxyethyl methacrylate at their carboxylic acid end. Esterification products displayed low polydispersity indices (ca. 1.2) and a functionality of over 83%, with a Mn of 2,020. Using free radical polymerization methods, the macromonomers were copolymerized with methyl methacrylate to yield graft (comb type) copolymers at different comonomer feed ratios. The graft copolymers contained from 0.5 to 14 mol-% of PHB blocks, with a glass transition temperature decreasing from 100 to 3 degrees C.