Infra-red spectra of perfluorinated cation-exchanged membranes

Assignment of the i.r. spectrum of Nafion cation exchange membranes was made possible by use of i.r. absorption and reflectance (ATR) spectroscopy. Shifts in the water and sulphonic vibrations occurring upon exchange of various counterions were compared with those occurring in a polyethylene sulphonic acid and polystyrene sulphonic acid membrane. The type of binding of the cations and the possibility of cluster formation are discussed. A dimeric iron unit FeOFe was identified in the Nafion membrane.