Spiro[fluorene-9,9′-xanthene] containing fluorinated poly(ether amide)s: Synthesis, characterization and gas transport properties

A new diamine monomer, 2',7'-bis-[2 ''-trifluoromethyl 4 ''-(4 '''-aminophenyl)phenoxyl-spiro[fluorene-9,9'-xanthene] was successfully used to synthesize several polyamides (PM) for membrane-based gas separation applications. All synthesized polymers were soluble in organic solvents, exhibited high molecular weight, high thermal stability (up to 483 degrees C and 519 degrees C in air and nitrogen respectively, for 10% weight loss) and high glass transition temperature (273-289 degrees C). The optically transparent membranes (lambda(cut-off) >= 364 nm) from these PM showed tensile strength up to 88 MPa with elongation at break up to 12%. In general, the membranes prepared from these polymers showed very good combination of permeability and permselectivity for a pair of gases. It has been attempted to draw a structure-property correlationship between the chemical structures of the polymers and their gas transport properties on the basis of their FFV, glass transition temperatures, intersegmental distance and dielectric constant values. (C) 2015 Elsevier Ltd. All rights reserved.