Cross-linked sulphonated polymers and their preparation process

Process for cross-linking sulfonyl groups of a sulfonated polymer wherein at least a fraction of the cross-linking bonds bear an ionic charge, the process comprising contacting the polymer with the cross-linking agent allowing the reaction between two sulfonyl groups from adjacent polymeric chains to form the cross-linking bonds,

• wherein the cross-linking bonds are of the type:
• P—SO2—Y−(M+)—SO2—P′;
• or
• P—SO2(M+)Y−SO2—(Q—SO2)r—Y−(M+)SO2—P′
• wherein
• P and P′ are the same or different and are part of a polymeric chain;
• Y comprises N or CR wherein R comprises H, CN, F, SO2R3, C1-20 alkyl substituted or unsubstituted;
• C1-20 aryl substituted or unsubstituted;
• C1-20 alkylene substituted or unsubstituted, wherein the substituent comprises one or more halogen, and wherein the substituted chain comprises one or more substituent F, SO2R, aza, oxa, thia or dioxathia;
• R3 comprises F, C1-20 alkyl substituted or unsubstituted;
• C1-20 aryl substituted or unsubstituted;
• C1-20 alkylene substituted or unsubstituted, wherein the substituent comprises one or more halogens;
• M+ comprises an inorganic or organic cation;
• Q comprises a divalent radical C1-20 alkyl, C1-20 oxaalkyl, C1-20 azaalkyl, C1-20 thiaalkyl, C1-20 aryl or C1-20 alkylaryl, each being optionally substituted by one or more halogens, and wherein the chain may comprise one or more substituents oxa, aza, or thia;
• r is 0 or 1;
• and
• the divalent radical and the sulfonated polymer are partially or completely fluorinated.