GAS SORPTION AND DIFFUSION IN HYDROGEN-BONDED POLYMERS .2. POLYETHERSULFONE POLYHYDROXYETHER BLENDS

The gas sorption behavior of CO2, C2H6, and CH4, and the gas transport behavior of CO2 and CH4, were examined for polyethersulfone (PES), polyhydroxyether, and four miscible blends containing 20, 40, 60, and 80 wt % PES. The 40 wt % PES blend exhibited the lowest sorption levels and the lowest permeabilities for all of the gases. Application of the dual-mode sorption model revealed negative deviations for the Henry's law parameter k(D) that were larger than those observed for blends relying on van der Waals or simple polar interactions. Also, the magnitude of the blend interaction parameter obtained from the gas sorption data and the volume of mixing were both more negative in the hydrogen-bonded blend. Diffusion coefficients at infinite dilution and from the dual mode/partial immobilization model exhibited minima at 40 wt % PES, as did the fractional free volume, a measure of chain packing ability. (C) 1994 John Wiley & Sons, Inc.