Thermodynamic properties of poly(vinyl alcohol) and poly(vinyl alcohol-vinyl acetate) hydrogels

Osmotic and light scattering observations are reported for chemically cross-linked poly(vinyl alcohol) and poly(vinyl alcohol-vinyl acetate) hydrogels and the corresponding semidilute polymer solutions. The osmotic contribution of the network polymer is obtained from swelling pressure and shear modulus measurements. The free energy of mixing in the cross-linked polymer is found to be significantly smaller than that of the polymer solution at the same concentration. SANS and static light scattering measurements indicate the presence of large-scale static structures in the systems