Effect of bulky groups on gas transport properties of semifluorinated poly(ether amide)s containing pyridine moiety

A series of processable new aromatic polyamides (PAs) were prepared by the reaction of a new diacid monomer namely, 2,6-bis[3'-trifluoromethy1-4'(4 ''-carboxyphenoxy)benzyl]pyridine and previously reported four diamines monomers. The synthesized PAs showed high thermal stability (up to 468 degrees C in air, for 10% weight loss), high glass transition temperature (243-254 degrees C) and tensile strength up to 95 MPa. The membranes prepared from these polymers were investigated for their gas permeability for four different gases CH4, N-2, O-2 and CO2. The PA membranes showed high gas permeability (P-CO2 up to 81 and P-O2 up to 20 barrer) and high permselectivity (P-CO2/P-CH4 up to 47.50 and P-O2/P-N2 up to 6.9). The gas transport properties have been correlated with the polymer structures and fractional free volume (FFV). (C) 2015 Elsevier Ltd. All rights reserved.