Grafting of N-isopropyl Acrylamide onto Bacterial Polyhydroxybutrate/Hydroxyvalerate Copolymers

This work deals with the grafting of N-isopropyl acrylamide (IPA) onto poly (3-hydroxybutyrate-3-hydroxyvalerate), (PHBV) (5.4 mole % 3-hydroxyvalerate), using benzoyl peroxide as free radical initiators. The effect of N-isopropyl acrylamide and initiator concentrations and reaction time on the degree of grafting has been investigated. The maximum degree of grafting was 82%. The grafted products were characterized by FTIR, (HNMR)-H-1, DSC, wide-angle X-ray diffraction and TGA analysis. The DSC results showed that the cold crystallization temperature from the glassy state increased with increasing the extent of grafting, while the Tg and Tm are not affected significantly. TGA analysis revealed that grafting of the host PHBV polymer did not affect much its onset decomposition temperature. The Grafted products swell in aqueous solution and the swelling is controlled by the extent of grafting, temperature, and pH. The biodegradability of PHBV and its graft copolymers solutioncast films was investigated in active soil. The results indicated that the introduction of the hydrophilic PVP and PIPA graft chains enhanced the biodegradability of PHBV.