A new approach to chemically modified carboxymethyl chitosan and study of its moisture-absorption and moisture-retention abilities

A new approach to prepare chemically modified carboxymethyl chitosan (CM) derivatives was reported, from which initially CM was prepared from chitosan, then N-quaternary ammonium group was introduced by the reaction of CM with 2,3-epoxypropyl trimethylammonium. The structures of the derivatives were characterized by FTIR, XRD, C-13-NMR, and gel permeation chromatography. The capability of moisture-absorption and moisture-retention was investigated. It was found that the moisture-absorption and moisture-retention ability of the new derivatives quaternized carboxymethyl chitosan (CMQ) are higher than not only that of CM but also that of chitosan quaternary (Q) and carboxymethyl group and quaternary ammonium group are in synergistic effect. Relationships between molecular structures (including degree of substitution of carboxymethylation group, degree of substitution of quaternary group, and molar mass) and functions of CMQ were also studied. The moisture absorption kinetics of CMQ was discussed and the diffusion of water molecules in it looks likely to be non-Fickian type. (c) 2006 Wiley Periodicals, Inc.