Abstract
Sodium ion, cesium ion, and water self‐diffusion coefficients in a perfluorinated carboxylate polymer film have been measured. Results are compared to those obtained for a perfluorinated sulfonate polymer, Nafion. Both cation and water diffusion coefficients are very large in these materials in relation to the equilibrium amounts of sorbed water. The carboxylate polymer shows larger diffusion coefficients but smaller water sorption, compared to Nafion. Infrared results indicate significant changes in the state of sorbed water between the two materials. Results are discussed in terms of the ion clustered morphology of these ion exchange polymers.