GAS SEPARATION PROPERTIES OF AROMATIC POLYAMIDES WITH SULFONE GROUPS

The gas transport properties of three aromatic polyisophthalamides bas ed on isophthaloyl chlorides and 4,4'-diaminodiphenylsulfone are repor ted at 35 degrees C. The effects of bulky t-butyl and phthalimide subs tituents, at the 5 position of the isophthaloyl chloride moiety, on CO 2, CH4, O-2, N-2, H-2 and He permeability, solubility and diffusivity were determined and correlated with chain packing and thermal properti es of the polymers. Gas permeability was higher in substituted polyiso phthalamides than in the unsubstituted analogue. Polymers containing t he pendent t-butyl substituent have substantially higher permeability than polymers bearing the phthalimide substituent, despite the fact th at the phthalimide substituent appears to be more bulky than the t-but yl group, based on van der Waals volume estimations. The strong polari ty of the phthalimide moiety may act to increase chain-chain cohesive forces, which would tend to enhance chain packing, thereby reducing th e packing-disrupting ability of the bulky phthalimide group. The perme ability increase of the substituted polymers was accompanied by a perm selectivity decrease.