Physicochemical characterization of chemical hydrogels based on PVA

In this paper, we report on the physicochemical characterization of hydroge ls recently obtained by crosslinking poly (vinylalcohol), PVA, with teleche lic PVA (telPVA, bearing terminal aldehydic groups) via acetalization in aq ueous solution. These gels were studied by equilibrium swelling, compressio n modulus measurements, and proton relaxometry experiments. Swelling and co mpression modulus data allow to estimate the average molecular weight of PV A chain between crosslinks, the average mesh size of the networks, and the polymer-solvent interaction parameter chi(1). The average mesh size of PVA- telPVA compares well with domain dimensions of diffusionally confined water as detected by NMR relaxometry. Proton relaxometry also showed different n etwork domains in which water is compartmentalized, indicating a complex he terogeneity. The study of the temperature behavior of the nuclear spin-spin relaxation times of the confined water was also considered. (C) 1999 John Wiley & Sons, Inc.