The invention concerns novel ion-exchanging membranes, the method for preparing them and their uses. The membranes are made up of a polymer obtained from a monomer or a bifunctional mixture of monomers of general formula [T-SO2-Y-SO2T']- M-+. Moreover said polymers are useful in electrochemical cells, in a chlorine-sodium electrolysis process, as separator in an electrochemical preparation of organic and inorganic compounds, as separator between an aqueous phase and an organic phase, or as catalyst for Diels-Alder additions, Friedel-Craft reactions, aldol condensations, cationic polymerisation, and acetal formation.