Thermally treated polyaniline/polybenzimidazole blend membranes: Structural changes and gas transport properties

Polyaniline/polybenzimidazole (PANI/PBI) blend membranes with various ratios of PANI/PBI were prepared by the solution casting method. The resulting free-standing membranes were subsequently doped with hydrochloric acid. In the next step, the membranes were heated up to 600 °C in an inert nitrogen atmosphere. FTIR spectroscopy and Raman scattering show the conversion of the blend to a nitrogen-containing carbon-like material. The permeability and sorption properties with respect to H2, O2, N2, CH4, and CO2 were determined. The separation qualities of the thermally treated PANI/PBI blend membranes significantly exceed those of non-thermally treated membranes. The permeation properties show a strong dependence on the PANI concentration in the blend and on its doping. The best separation performance for H2/N2, CO2/N2, and CO2/CH4 is obtained with the thermally treated undoped PANI/PBI 20/80 blend membrane.