Poly(tetrafluoroethylene-co-perfluorovinyl ether sulfonamide) for anion exchange membranes

Abstract

A soluble perfluorinated polymer poly(tetrafluoroethylene-co-perfluorovinyl ether sulfonamide) (PFSO₂NH₂) was successfully synthesized and used for preparation of perfluorinated anion exchange membranes (AEMs). PFSO₂NH₂ is soluble in many solvents and has excellent alkaline stability. The perfluorinated AEM (PFSO₂NH–MGMC–OH) which was synthesized by the reaction of PFSO₂NH₂ with 4-methyl-4-glycidylmorpholin-4-ium chloride (MGMC) exhibits a hydroxide conductivity of 60.4 mS cm⁻¹ at 80 °C and 13.8 mS cm⁻¹ at 30 °C, respectively. The transport numbers of the membrane are 0.91 for Cl⁻ and 0.06 for Na⁺. The membrane shows good alkaline stability that it maintained 80.1% hydroxide conductivity and 85.6% ion exchange capacity (IEC) values after immersion in 8 M KOH over 30 days at 60 °C. This soluble PFSO₂NH₂ with high thermal and alkaline stability could be used as a precursor for other perfluorinated functional polymers and membranes.