Hydroxyethyl chitosan-g-poly(acrylic acid-co-sodium acrylate) superabsorbent polymers

A novel hydroxyethyl chitosan-g-poly (acrylic acid-co-Sodium Acrylate) (HECTS-g-(PAA-co-PSA)) superabsorbent polymer was prepared through graft copolymerization of acrylic acid and sodium acrylate onto the chain of hydroxyethyl chitosan. The structure of the polymer was characterized by FTIR. By studying the water absorption of the polymer synthesized under different conditions, the optimal conditions for synthesizing the polymer with the highest swelling ratio was defined. This superabsorbent polymer was further treated by the solvent precipitation method and by the freeze-drying method. We found that the water absorption rate of the treated polymer was greatly increased and the microstructure of the treated polymer was changed from small pores to loose macro pores. The swelling processes of the polymers before and after modification fit first-order dynamic processes. The amount of the residual acrylic acid was greatly decreased after treatments.