Synthesis and characterization of fluorinated polyionomers. Part I: polyperfluoro-sulfonylethoxy propylene vinyl ether sulfonimides containing aryl sulfonic acids

Abstract

The synthesis and chemistry associated with the preparation of polysulfonimide polyionomers containing aryl sulfonic acids with high charge densities and various solubilities is reported. Homopolymers of perfluoro-sulfonylethoxy propylene vinyl ether (PSEPVE) are prepared by free radical polymerization and functionalized with sulfonyl chlorides of benzene, terphenyl, and triphenylene. The nature of the pendant group has been found to have a substantial impact on solution properties. In particular, water solubility is easily attained in the poly(PSEPVE) benzene sulfonimide, while the incorporation of bulky, rigid aromatic groups in the poly(PSEPVE) triphenylene sulfonimide disulfonic acid product allowed it to retain water insolubility with high charge density (∼2 meq. H⁺ per g). Perfluoropolysulfonimide gel network polymers are also prepared utilizing similar chemistry. Thermal stabilities upon boiling in an aqueous solution are established by monitoring charge density and changes in the ¹⁹F NMR spectra of the ionomers.