Gas permeability in rubbery polyphosphazene membranes

✍ Scribed by Christopher J. Orme; John R. Klaehn; Mason K. Harrup; Thomas A. Luther; Eric S. Peterson; Frederick F. Stewart

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 544 KB
• Volume: 280
• Category: Article
• ISSN: 0376-7388
• DOI: 10.1016/j.memsci.2006.01.009

✦ Synopsis

The synthesis, characterization, and gas permeability of 10 new polyphosphazenes has been studied. Additionally, the first gas permeation data has been collected on hydrolytically unstable poly [bis-(chloro)phosphazene]. Gases used in this study include CO 2 , CH 4 , O 2 , N 2 , H 2 , and Ar. CO 2 was the most permeable gas through any of the phosphazenes and a direct correlation between the T g of the polymer and CO 2 transport was noted with permeability increasing with decreasing polymer T g . To a lesser degree, permeability of all the other gases studied also yielded increases with decreasing polymer T g . The trend observed for these new polymers was further supported by published data for other phosphazenes. Furthermore, permeability data for all gases were found to correlate to the gas condensability and the gas critical pressures, except for hydrogen, suggesting that the nature of the gas is also a significant factor for permeation through rubbery phosphazene membranes. Ideal separation factors (α) for the CO 2 /H 2 and CO 2 /CH 4 gas pairs were calculated. For CO 2 /CH 4 , no increase in α was observed with decreasing T g , however increases in α were noted for the CO 2 /H 2 pair.