SOLUTION BEHAVIOR OF POLYETHYLENE OXIDE IN WATER AS A FUNCTION OF TEMPERATURE AND PRESSURE

A model of the solution behavior for hydrosoluble polymers [based on a model of Matsuyama and Tanaka, Phys. Rev, Lett. 65, 341 (1990)] is in troduced that accounts for hydrogen bonding of solvent molecules onto polymer chains. In the limit of small volume fraction of H-bonded solv ent molecules, the resulting free energy has the standard Flory-Huggin s form with a good solvent contribution to the effective chi parameter coming from the fraction of solvents H-bonded to the chain. This simp le theory is capable of semiquantitatively, explaining the experimenta l temperature-concentration (T-phi) and temperature-pressure (T-P) pha se diagrams of polyethylene oxide in water.