A Comparison of Perfluorinated Carboxylate and Sulfonate Ion Exchange Polymers: II . Sorption and Transport Properties in Concentrated Solution Environments

Abstract

Various properties of a perfluorinated carboxylate polymer film have been studied in concentrated and solution environments at elevated temperatures. Electrolyte and water sorption measurements reveal relatively constant electrolyte uptake but decreasing water sorption with increasing solution concentration. The apparent of the carboxylate exchange sites was found to be 1.9. Sodium ion self‐diffusion in the polymer was measured as a function of solution pH and concentration. Several differences in the diffusional properties of the carboxylate vs. Nafion sulfonate polymer films were found and are discussed in terms of ion pairing phenomena. Transport numbers for Na⁺ and in these polymers at high current densities were measured and are discussed in terms of the nature of ion transport in these polymers.