A polyarylene copolymer which comprises (A) from 60 to 3 mol % aromatic compound units having a main chain containing one or more electron-withdrawing groups therein and (B) from 40 to 97 mol % aromatic compound units having a main chain containing no electron-withdrawing groups therein (provided that...http://www.google.de/patents/US6555626?utm_source=gb-gplus-sharePatent US6555626 - Polyarylene copolymers and proton-conductive membrane
