Influence of Anions on Proton-Conducting Membranes Based on Neutralized Nafion 117, Triethylammonium Methanesulfonate, and Triethylammonium Perfluorobutanesulfonate. 1. Synthesis and Properties

The effect of the anion structure of proton-conducting ionic liquid dopants on the properties of a Nafion 117 membrane, neutralized by triethylammonium, is described. The synthesis and the properties of proton-conducting membranes doped with triethylammonium methanesulfonate (TMS) or triethylammonium perfluorobutanesulfonate (TPFBu) ionic liquids are described. The properties of the doped membranes were investigated by thermogravimetric analysis, differential scanning calorimetry, and dynamic-mechanical analysis. The key findings are that the uptake of the ionic liquid is ca. 25 and 40 wt % for TMS and TPFBu, respectively, and these ionic liquid dopants extend the membranes thermal stability to 140°C. Information concerning the structure and the interactions between the membrane components was obtained by Fourier transform infrared spectroscopy.