Synthesis and characterization of thermo- and pH- sensitive hydrogels based on Chitosan-grafted N-isopropylacrylamide via γ-radiation

Thermo- and pH-sensitive hydrogels were prepared by graft copolymerization of chitosan (CS) and N-isopropylacrylamide via γ-radiation. The effects of monomer concentration and irradiation dose on grafting percentage and grafting efficiency were studied. The graft copolymers were characterized by 13C CP/MAS NMR and thermogravimetric analysis. The pH and thermosensitivity and swelling properties of the hydrogels were investigated. The results showed that the grafting percentage and grafting efficiency increased with the increase of monomer concentration and total irradiation dose. The highest grafting percentage is 620%, the lower critical solution temperature (LCST) of this hydrogel is about 28 °C.