Gas transport properties of aromatic polyamides containing adamantyl moiety

In this work we report the synthesis of a new diamine monomer, 1-adamantylmethyl[3,5-bis-{2′-trifluoromethyl-4′-(4″-aminophenyl)phenoxy}]benzoate and its polymerization with four different diacids. The monomer and the prepared poly(ether amide)s (PAs) were characterized by elemental analyses, NMR, and FTIR techniques. The polymers were further characterized by GPC and thermal techniques and the mechanical properties of the films prepared from these polymers are also reported. The permeability of CH4, N2, O2 and CO2 through these PA membranes was investigated at three different temperatures (35, 45 and 55 °C) under an applied upstream pressure of 3.5 bar. The PA 9B containing hexafluoroisopropylidene moiety exhibited highest permselectivity in the series (for, O2/N2=8.2 and CO2/CH4=41.7) whereas PA 9A containing tert-butyl moiety exhibited highest gas permeability (image=34 and image=9.5). The gas transport properties have been correlated with the polymer structures with respect to their glass transition temperature, chain packing and dielectric constant values. The activation energies of the permeation and diffusion processes were calculated.