Synthesis and characterization of pH/temperature-sensitive hydrogels based on chitosan derivative

Abstract

A series of pH/temperature-sensitive hydrogels composed of maleilated chitosan (MC) and N-isopropylacrylamide (NIPAAm) were prepared and characterized with respect to their swelling behaviors, change of lower critical solution temperature (LCST). These hydrogels showed broad pH-sensitivities below 32 degreesC, but above that temperature exhibited sharp pH-dependent phase transition behaviors which depended on the content of MC in the hydrogels. The change of ratio of NIPAAm to MC in weight did not affect LCST significantly, while it affected equilibrium water content (EWC) at high pH region. The hydrogels also exhibited a typical of reversibility depending on temperature and pH.