Synthesis and properties of hydrogels based on chitosan and poly(vinyl alcohol) crosslinked by genipin

Semi-interpenetrating polymeric networks of chitosan and poly( vinyl alcohol) [PVA] were prepared by varying the ratio of the constituents. The hydrogels were crosslinked using genipin, a naturally occurring nontoxic cross-linking agent. The swelling behavior of these hydrogels was studied by immersing the films in deionized water at various temperatures and in buffer solutions of different pH. The states of water in the hydrogels, swollen at 25 degrees C and pH 7, were determined using Differential Scanning Calorimetry (DSC). The swelling behavior of the gels was found to be dependent on temperature and pH of the medium. The amount of freezing water in the swollen hydrogels increased, whereas the amount of nonfreezing bound water remained more or less the same with increasing PVA concentration.