Effect of dimethyl sulfoxide on synthesis of thermoplastic cellulose-Graft-Poly(L-lactide) Copolymer using ionic liquid as reaction media

In this study, ring-opening graft polymerization of L-lactide onto cellulose was carried out homogeneously in ionic liquid (IL)/dimethyl sulfoxide (DMSO) co-solvent as a reaction media. Through the effective control of high viscosity and steric hindrance caused by the interaction between the IL and the hydroxyl group of cellulose by adding DMSO as a co-solvent, cellulose-graft-poly(Llactide) (Cell-g-PLLA) copolymer with higher substitution efficiency was successfully prepared, at relatively low concentration of L-lactide. The maximum values of molar substitution, degree of lactyl substitution, and degree of polymerization of poly(L-lactide) in the copolymer were 3.76, 1.74, and 2.16, respectively, determined by 1H-NMR. The prepared cell-g-PLLA copolymers showed thermal plasticization with a glass transition temperature of 155C. In addition, the thermal processibility could be improved as the amount of grafted PLLA in the copolymer increased.