Di-tert-butyl containing semifluorinated poly(ether amide)s: Synthesis, characterization and gas transport properties

A newly designed diamine monomer, 1,4-bis-[{2′-trifluoromethyl 4′-(4″-aminophenyl)phenoxy}]2,5-di-t-butylbenzene, was successfully used to synthesize several polyamides (PAs) for membrane-based gas separation applications. All the synthesized polymers were soluble in many organic solvents and exhibited high molecular weight, high thermal stability (up to 431 °C and 466 °C in air and nitrogen respectively, for 10% weight loss) and high glass transition temperature (275–286 °C). Membranes obtained from these PAs were optically transparent (λcut-off=372–400 nm) and showed tensile strength up to 107 MPa. In general all the membranes showed very high permeability and high permselectivity for a pair of gases. The gas transport properties of the polymers have been correlated with their FFV interchain distance (d-spacing), diffusivity, solubility, and dielectric constant values.