NMR study of a novel chitosan-based hydrogel

Chemical gels are obtained by reacting chitosan with 1,1,3,3-tetramethoxypropane (TMP, a "masked" dialdehyde) and then reducing the polymeric Schiff-base networks with an excess of cyanoborohydride (NaBH3CN). The gels have been characterized by means of three different 13C magic angle spinning NMR techniques: cross-polarization, cross-polarization with a simultaneous phase inversion and single pulse excitation. In this way we obtained spectra containing sufficiently resolved information for structural analysis. A quantitative evaluation of the cross-linking degree of chitosan¯TMP networks is thus attainable.