Characterization of gas transport in selected rubbery amorphous polyphosphazene membranes

Gas permeabilities for six different gases have been evaluated for a series of closely related polyphosphazenes. Polyphosphazenes are attractive polym ers for use as gas separation membranes due to their inherent chemical, the rmal, acid radiation stability. Additionally, polyphosphazenes may be tailo red for specific chemical affinities. In this report, polyphosphazenes with three different pendant groups with varied hydrophilicity were characteriz ed for gas permeation. All polymers were characterized as having modest per meabilities for methane, oxygen, nitrogen, helium, and hydrogen. These gase s were not observed to have a significant interaction with the polymer stru cture and transport is attributed to segmental chain motion. Carbon dioxide was found to have a significant intermolecular interaction with the polyme r and the permeability was observed to be proportional to the percentage of hydrophilic 2-(2-methoxyethoxy)ethanol on the backbone. Thus, we report a promising method for the development of CO2 selective membranes. (C) 2001 E lsevier Science B.V. All rights reserved.