Osmotic Compressibility and Mechanical Moduli of Swollen Polymeric Networks

The thermodynamics of polymeric networks subject to the action of a solvent is reviewed. Expressions for the osmotic compressibility and elastic moduli (bulk and shear) of the swollen network are derived in relation to the molecular characteristics of the system. The dependence of the osmotic compressibility on the equilibrium degree of swelling and the solvent quality is investigated. A strong dependence of osmotic compressibility on the nature of the solvent is emphasized. Predictions of the theory are compared with scaling arguments and results of experiments on swollen PVAc networks.