Water sorption characteristics in moderately hydrophilic polymers, Part 1: Effect of polar groups concentration and temperature in water sorption in aromatic polysulfones

The water equilibrium concentration has been determined for three aromatic polysulfones differentiated essentially by the sulfone concentration, in the 0-0.9 activity range, at temperatures of 50, 60, and 70 degrees C, using a dynamic vapor sorption apparatus. In all the cases, Henry's law was obeyed. The corresponding solubility S and heat of dissolution H-s were determined and their relationships with structure were investigated. The fact that S increases nonlinearly with the sulfone concentration and that H-s is also an increasing function of the latter leads one to abandon classical approaches to polymer-water interactions and propose a model in which water is doubly bonded. Then, S depends on the distribution of distances between polar groups, characterized by a function P(r) and H-s depends on both P(r) and the hydrogen bond potential U(r). (C) 2008 Wiley Periodicals, Inc.