Synthesis, characterization and gas transport properties of cardo bis(phenylphenyl)fluorene based semifluorinated poly(ether amide)s

Abstract

Here we report the synthesis and properties of a series of processable poly(ether amide)s (PAs) having the bis(phenylphenyl)fluorene moiety prepared from a new diamine monomer, 9,9-bis-[3-phenyl-4-{2′-trifluoromethyl-4′-(4′′-aminophenyl) phenoxy}phenyl]fluorene. Analogous PAs having the bis(phenyl)fluorene moiety have also been prepared from the diamine 9,9-bis-[4-{2′-trifluoromethyl-4′-(4′′-aminophenyl) phenoxy} phenyl]fluorene for comparative purposes. The synthesized PAs exhibited high thermal stability (up to 517 °C and 539 °C in air and nitrogen respectively, for 10% weight loss), high glass transition temperature (272–299 °C) and high tensile strength up to 117 MPa. The optically transparent membranes (λ_cut-off ≥ 368 nm) from these PAs showed high gas permeability in barrer (P_CO2 up to 67.42 and P_O2 up to 15) and high permselectivity (P_CO2/P_CH4 up to 88.37 and P_O2/P_N2 up to 10.84); especially for the O₂/N₂ gas pair the PAs surpass or touch the present upper boundary limit of 2008 drawn by Robeson. The effect of the bis(phenylphenyl)fluorene moiety and diacid moieties in PAs on the dielectric values, thermal, mechanical, optical and gas transport properties were correlated.