Synthesis of perfluorinated membranes

Among the cation permeable perfluorinated membranes previously mentioned, only the perfluorosulphonic membranes are proton conductors. Their synthesis is described in this chapter .  

These membranes are produced by Du Pont de Nemours (USA) under the registered trademark Nafion. To synthesize Nafion , tetrafluoroethylene is reacted with SO3 to form a cyclic sulphone. After rearrangement, the sulphone can then be reacted with hexafluoropropylene epoxide to produce sulphonylfluoride adducts, with m 1 

When these adducts are heated with sodium carbonate, a sulphonylfluoride vinylether is formed. This vinylether is then copolymerized with tetra-fluoroethylene to form XR resin 

This high molecular weight polymer is melt fabricable and can be processed into various forms, such as sheets or tubes, by standard methods. By hydrolysis, this resin is converted into Nalion perfluorosul-phonic polymer 

---