New reverse osmosis membrane materials with higher resistance to chlorine

Copolyamides were prepared from mixed diamine components of 3,3′- or 4,4′-diaminodiphenylsulfone, piperazine, and dichlorides such as isophthaloyl or terephthaloyl. The obtained copolyamides are random copolymers, which have good solubilities in organic solvents and good mechanical properties, even in water. The asymmetric membranes prepared from the copolyamides [ex: 4I-PIP(20)] not only have more excellent reverse osmosis performance, but also higher chlorine resistance than NOMEX-type aromatic polyamide. New membrane materials with excellent reverse osmosis performance and higher chlorine resistance than the NOMEX-type aromatic polyamide could be demonstrated successfully.