Phase equilibria in polymer/solvent systems

A survey for the osmotic equilibrium between solution and a pure solvent as well as for the swelling pressure eqilibrium between a gel and pure solvent is given, where phase transitions of the pure component are allowed to occur. The equilibrium temperature/concentration curves are presented for constant osmotic and swelling pressure respectively in the different phase ranges for crystalline, liquid and gaseous solvent. The calculated equilibrium curves for soluble and slightly crosslinked substances based on results of the system PEO/water are very similar and intersect at the transition temperature. The same holds for the temperature dependence of the osmotic and swelling pressure respectively at constant composition. In principle, the findings are in agreement with experimental results found in synthetic polymer/solvent systems and those found in plant cells.