Aromatic Polyimide Membranes with -Butyl and Carboxylic Side Groups for Gas Separation Applications-Covalent Crosslinking Study.

A set of aromatic copolyimides was obtained by reaction of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), and mixtures of the diamines 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di--butylbenzene (CFTBAPB) and 3,5-diamino benzoic acid (DABA). These polymers were characterized and compared with the homopolymer derived from 6FDA and CFTBAPB. All copolyimides showed high molecular weight values and good mechanical properties.