A comparative and systematic thermodynamic study of aqueous solutions and hydrogels of homo- and copolymers of poly(vinyl alcohol)

Abstract

Accurate measurements of the thermodynamic activity of the solvent were performed on aqueous solutions and chemically cross-linked hydrogels of poly(vinyl alcohol) and its statistical poly(vinyl alcohol, vinyl acetate) co-polymers in the range of moderate polymer concentrations. A test of the theories has revealed that only a certain type of two-membered equation for the network part of the solvent chemical potential was appropriate to get reasonable values for the Flory–Huggins interaction parameter as a function of both the degree of cross-linking and polymer volume fraction. The strong effect of the network structure on the χ parameter as well as the gradual transition in the thermodynamic properties of the systems is discussed in detail.