Polyimide ionomer containing superacid groups

A novel sulfonated polyimide (SPI) copolymer containing pendant perfluorosulfonic acid groups was synthesized and their properties were investigated. 2‐(2,4‐Diaminophenoxy)‐1,1,2,2‐tetrafluoroethanesulfonic acid ( 5 ) was synthesized from 2,4‐diaminophenol dihydrochloride via acetylation, perfluoroalkylation, and sulfonation. Polycondensation of 1,4,5,8‐naphthalenetetracarboxylic dianhydride, monomer 5 , and 3,5‐bis(4‐aminophenyl)‐1H‐1,2,4‐triazole gave the title polyimide 6 . The obtained polyimide copolymer 6 was soluble in polar organic solvents and its chemical structure and ion exchange capacity were confirmed by 1 H and 19 F NMR spectra. The copolymer 6 was thermally stable up to ca . 180°C and showed 6.6 × 10 −4  S cm −1 of the proton conductivity at 80°C in water. Copyright © 2011 John Wiley & Sons, Ltd.