A study on grafting poly(1,4-dioxan-2-one) onto starch via 2,4-tolylene diisocyanate

A new biodegradable copolymer of starch-graft-poly(1,4-dioxan-2-one) (starch-g-PPDO) was synthesized by solution polymerization in dimethyl sulfoxide using 2,4-tolylene diisocyanate (TDI) as a coupling agent. The length of PPDO graft chains can be controlled easily by using the prepolymers of PPDO with different molecular weights. The copolymers were prepared by two-step reactions. First, the isocyanate–terminated intermediate (PPDO–NCO) was prepared by introducing one NCO group of TDI onto the hydroxyl end-group of PPDO; second, PPDO–NCO was grafted onto corn starch chains by the reaction between the unreacted NCO group and the hydroxyls of starch, and then, starch-graft-PPDO was obtained. The chemical structure of PPDO–NCO and graft copolymers was confirmed by using FT-IR and 1H NMR, and the thermal properties of the copolymers were investigated by DSC and TG.