Polyaniline/polybenzimidazole blends: Characterisation of its physico-chemical properties and gas separation behaviour

• Novel polymer blend based on polyaniline (PANI) and polybenzimidazole (PBI).
• Spectroscopic studies revealed strong interaction between PANI and PBI.
• Very high ideal selectivities of the following gas pairs H2/N2, O2/N2 and CO2/N2.
• Doping of blend with HCl has significant effect on gas transport properties.
• Sorption capacities decreased with higher amount of PANI and upon doping.

Novel polymer blends were prepared by casting blend solutions of polyaniline (PANI) and polybenzimidazole (PBI) at various ratios. Prepared blends were amorphous and had good film homogeneity without defects. From mechanical analysis it was found that tensile strength diminishes with increasing content of PANI. WAXS analysis disclosed the amorphous structure of PANI/PBI blends. IR spectra indicate clearly the presence of PANI in PBI matrix and NMR spectra revealed significant interactions of PBI with PANI. Permeability, diffusion, solubility coefficients and sorption capacities of all measured gases (H2, O2, CH4, N2, CO2 and water vapour) decreased with increasing PANI content whereas ideal selectivities increased for all observed gas pairs. Doping of blends with hydrochloric acid led to a significant decrease in permeabilities and sorption capacities while selectivities slightly increased.

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