Aromatische Polyimid und Gastrennung

摘要

An aromatic polyimide having a recurring unit of the formula (I): wherein Ar is a divalent aromatic group having one or two benzene rings which has a sulfanate group of -SO3H, -SO3M, and -SO3N(L)4 on the ring, wherein M is an alkali metal and L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, is favorably employed in the form of a semipermeable film for gas separation.