Gas Permeability and Selectivity of Poly(Organophosphazene) Membranes

Abstract

Abstract The gas permeabilities and selectivities were determined for some poly(organophosphazene) membranes. It was found that [NP(OC6H2Et-p)2]n had the highest selectivity for nitrogen or hydrogen, and [NP(OCH2CF3)2]n had the highest selectivity for carbon dioxide or helium gas. Selectivity was not dependent on the glass transition temperatures and dielectric constants of the membranes. Increasing the gas permeability tended to accompany an increasing dielectric constant. The activation energy of gas permeability for some membranes was measured at various temperatures. The results showed that the magnitude of the activation energy was not related to the covalent radii or dielectric constant of such gases as H2, N2, O2, CO2, and He.