Gas transport and structural features of sulfonated poly(phenylene oxide)

Abstract

The effect of ionomer structure on gas transport properties of membranes was investigated. For this purpose physical and transport properties of poly(phenylene oxide) (PPO) and its sulfonated derivative (SPPO) were compared. SPPO has a more rigid structure and a lower free volume, which determines low gas permeability and high permselectivity. Gas transport properties of two types of SPPO—PPO composite membranes with top layers prepared from solutions in methanol or N,N-dimethylacet-amide (DMA) were investigated. The use of SPPO solution in DMA leads to the formation of membranes with higher gas permeability. It was shown that DMA is a morphologically active solvent for SPPO. Strong complexes of SPPO with DMA are formed in solution and retained upon transition into the condensed state. The plasticizing effect of DMA on SPPO determines the high gas permeability of the membranes and is in agreement with their mechanical properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1439–1443, 1997