Pervaporation Membranes Based on Interpolyelectrolyte Complexes of an Aromatic Copolyamide Containing Sulfonate and Carboxy Groups

Abstract

Film membranes were prepared from interpolyelectrolyte complexes of various aliphatic polyamines with a copolyamide synthesized from isophthalic dichloride and two diamines: disodium 4,4′-diaminobiphenyl-2,2′-disulfonate and 4,4′-diaminodiphenylmethane-2,2′-dicarboxylic acid. The mechanical and sorption properties of the membranes and their performance in pervaporation separation of the water-isopropanol mixture were studied. The possibility of thermal cross-linking of the materials was demonstrated. The effect of the amidation on the physicochemical and mass-exchange properties of the film samples was examined. The variation of the separation characteristics of the membranes depending on the copolyamide composition was considered. With respect to the combination of separation and transport properties, the interpolymer systems containing the copolyimide with low (7 mol %) content of units with carboxy groups are of most interest. An increase in the fraction of carboxyl-containing units in the polyanion leads to an increase in the permeability of the materials with a significant decrease in their selectivity. The tensile strength of the film samples prepared from copolyamide-containing interpolyelectrolyte complexes is 54–92 MPa.