Ion conducting membrane for electrochemical applications

An ion-conducting membrane for electrochemical applications is based on aromatic polyimide or copolyimide polymers. An ion-conducting membrane for electrochemical applications is based on aromatic polyimide or copolyimide polymers comprising units of formula (1). B = formula (2),(3), pyridyl or pyrimidinyl; R = H, phenyl, a phosphonic acid group or at least one phosphonic acid group containing chain; A = naphthalene group of formula (4)-(6) forming 6 atom rings with the neighboring imide groups; X = CO, O, C(CF3)2 or SO2.