Understanding hydrated polymers: the perspective of NMR

This review examines the divergent views in the literature on the role of water in hydrated polymers, specifically the origin of non-freezable water. One approach, based largely on site-specific information furnished by NMR invokes binding sites in the host polymer matrix as a principal source of bound or non-freezable water; the second approach is based on the thermodynamics of metastable, non-equilibrium states in the hydrated polymer without the necessity of binding sites. There is merit in both approaches: and they are not mutually exclusive. The situation is further exacerbated with a proliferation of terminology that is both technique and temperature dependent. Despite these difficulties, the behaviour of water has several generic features that are common to a wide variety of hydrated polymeric and nonpolymeric systems. The advantages of a multi-technique approach in unravelling the intricacies of polymer-water interactions cannot be over-emphasised. (C) 1999 Elsevier Science B.V. All rights reserved.