Preparation of corn starch-g-polystyrene copolymer in ionic liquid: 1-Ethyl-3-methylimidazolium acetate

• The dissolution of corn starch in the ionic liquid [EMIM]Ac was studied.
• Starch-grafted polystyrene copolymer was prepared in [EMIM]Ac via free radical polymerization.
• Grafting percentages of up to 113.9% were achieved.
• The graft-copolymer presented good thermostability.

The copolymer of starch grafted with polystyrene (starch-g-PS) was synthesized with high grafting percentage by utilizing the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) as solvent and potassium persulfate as initiator. The effect of various parameters upon the polymerization were studied including: initiator concentration, styrene:starch weight ratio, the reaction time and temperature. Grafting percentages were calculated using an FT-IR calibration method, with values up to 114%. The resulting copolymer was characterized using FT-IR, SEM, WAXD and TGA, which demonstrated that polystyrene side chains were evenly distributed on the starch backbone. Our results indicate that ionic liquid dissolution of starch, prior to polystyrene grafting, is a versatile methodology for the synthesis of amphiphilic, polysaccharide-based graft copolymers, having high grafting percent.