Tuning the free volume of polynorbornene-based membranes by blending 6FDA-durene to improve H2 permselectivity

Abstract

Homogeneous blend membranes of polynorbornene and 2,2′-bis(3,4′-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA)-durene were prepared to improve H2 permselectivity. The thermal properties and gas permselectivity of membranes with different polynorbornene/6FDA-durene blending ratios were investigated. The structural changes due to blending result in increased permeability derived from an increase in the fractional free volume of polymer blends with increasing glass transition temperature. Moreover, an increase in the 6FDA-durene content in the blends improved gas permeation, diffusivity, and solubility. The prepared blend membranes showed excellent gas permeation properties, namely, high gas permeability for H2 (14–971 Barrer) and high H2/N2 (α=13–46) and H2/CO (α=10–29) permselectivities.