Preparation, characterization and end group reactions of perfluoroalkanoic fluorides from radiation induced degradation of poly (tetrafluoroethylene)

Abstract

The macromolecular perfluorinated compounds of formula I CF 3(CF 2) nCOF, n=15−200, are synthesized by radiation-induced partial degradation of poly(tetrafluoroethylene) according to −(CF 2 n+mCF 2) n+m − ▪ + COF 2+CF 3(CF 2CF 2) n− In addition, derivatives of these products were easily prepared by terminal group reactions to anionic, cationic, non-ionic or crosslinked structures. ▪ In the purely ionogenic degradation products 3 the acid groups should have an increasing influence on the structure-property relationships (dissociation and sorption behaviour, ion-exchange capacity) with decreasing molecular weight. A thin layer of carboxylic groups near the surface is connected with a chemical inert non-swellable polymer. Crystallinity, melting behaviour, and composition of the derivatives can be varied. First investigations of the chemistry of perfluoroalkanoic fluorides and electrochemical characterization with regard to type and number of functional groups, investigations of stability, transport behaviour, and changes in the surface load by adsorption experiments of the particles point to interesting exchange properties and film-former properties of these perfluorinated ionomers.