Controlled preparation of physical cross-linked starch-g-PVA hydrogel

Physically cross-linked starch-g-PVA hydrogels with controllable grafted branch length were prepared. Polyvinyl acetate (PVAc) was grafted onto starch via radical copolymerization. The molecular weight of PVAc was tailored using the chain transfer reaction. In consequence, the branch length of starch-g-PVA, which derived from starch-g-PVAc, could be easily controlled. In this paper, the viscosity average molecular weight of grafted PVA segment ranged from 1.3×104 to 7.2×104. The structure of grafted copolymers was verified with FTIR. XRD analysis showed the crystallinity of starch-g-PVA was lower than that of starch. Starch-g-PVA hydrogels were obtained by freezing and thawing. It was found that the swelling ratio of hydrogels increased with the molecular weight of PVA.