NMR and the mobility of water in polysaccharide gels.

An analysis of the possible modes of motion of water molecules in polysaccharide gels indicates that the interpretation of NMR results does not require the supposition of a class of 'bound water' with highly perturbed motional states. There may, however, be water molecules associated with junction zones in the gels whose motions are restricted either by incorporation into the molecular secondary structure or as interstitial water in crystallites. Hydration and dehydration effects as well as the phenomenon of non-freezing water may all be explained within a framework of well understood processes. It is concluded that there is no requirement to appeal to 'bound water' to explain any of the properties of water in polysaccharide gels.