The synthesis of PHA‐g‐(PTHF‐b‐PMMA) multiblock/graft copolymers by combination of cationic and radical polymerization

Abstract A new and promising method for the diversification of microbial polyesters based on chemical modifications is introduced. Poly(3‐hydroxy alkanoate)‐ g ‐(poly(tetrahydrofuran)‐ b ‐poly(methyl methacrylate)) (PHA‐ g ‐(PTHF‐ b ‐PMMA)) multigraft copolymers were synthesized by the combination of cationic and free radical polymerization. PHA‐ g ‐PTHF graft copolymer was obtained by the cationic polymerization of THF initiated by the carbonium cations generated from the chlorinated PHAs, poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate) (PHBV), and poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyhexanoate) (PHBHx) in the presence of AgSbF 6 . Therefore, PHA‐ g ‐PTHF graft copolymers with hydroxyl ends were produced. In the presence of Ce +4 salt, these hydroxyl ends of the graft copolymer can initiate the redox polymerization of MMA to obtain PHA‐ g ‐(PTHF‐ b ‐PMMA) multigraft copolymer. Polymers obtained were purified by fractional precipitation. In this manner, their γ‐values (volume ratio of nonsolvent to the solvent) were also determined. Their molecular weights were determined by GPC technique. The structures were elucidated using 1 H‐NMR and FTIR spectroscopy. Thermal analyses of the products were carried out using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009