Preparation and application of the thermo-/pH-/ ion-sensitive semi-IPN hydrogel based on chitosan

Chitosan based hydrogels with multiple stimulus responses have broad application prospects in many fields. Considering the advantages of semi interpenetrating network (IPN) technology and the special temperature and ion responsiveness of polymers containing zwitterionic groups, a semi-IPN hydrogel was prepared through in situ free radical polymerization of N,N-dimethyl acrylamide and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide with polyethylene glycol dimethacrylate as a crosslinker and carboxymethyl chitosan as filler. The gel mass fraction and swelling ratio were measured, and the preparation conditions were optimized. The result indicated that the hydrogel possessed a unique thermo-/pH-/ ion-sensitive behavior. The swelling ratio increased with the increase of temperature and ion concentration, and showed a decreasing trend with the increase in pH. In addition, the hydrogel was stable when the stimuli changed. Adsorption behavior of the hydrogel to Eosin Y (EY) was systematically investigated. The adsorption process can be described well by the pseudo-second-order kinetic model and Langmuir isotherm model, indicating that it was a chemical adsorption. The experiments indicated that the hydrogel exhibited good antifouling and reusability features. Therefore, the semi-IPN hydrogel with antifouling properties and thermo-/pH-/ion-sensitivity can be easily manufactured is expected to find applications in water treatment fields.