Perfluorocarboxylate polymer preparation

This chapter summarizes the preparation and the fabrication of perfluorocarboxylate polymers and their fundamental properties including those of the ionized salt-type membranes. The application of Flemion in chlor-alkali electrolysis is also described. 

Perfluorocarboxylate polymers were prepared by copolymerization of tetrafluoroethylene and carboxylated perfluorovinyl ether. 

Methods of preparing the polymers have been reviewed (Young, 1972) but no one method is at present wholly satisfactory. Probably the most thoroughly studied method involves the ring closure of poly(imidoylamidine) with, for example, the anhydride of a perfluorocarboxylic acid. 

Multilayer membranes with perfluorocarboxylic and per-lluorosulfonic acid groups can be prepared by lamination of two different films containing the respective polymers " or by chemical conversion of perfluorosulfonic acid to perfluorocarboxylic acid. " The latter method is preferred to achieve the desired thickness of 5-10 fim of the carboxylic add pendant group. 

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