Short Side Chain Aquivion Perfluorinated Sulfonated Proton-Conductive Membranes: Transport and Mechanical Properties

Resumo

Data on the water uptake, proton conductivity, diffusion permeability, cation transport selectivity, and mechanical properties of short side chain Aquivion sulfonated perfluoropolymer membranes with an equivalent weight of 870 and 965 have been described. Properties of the membranes have been compared with those of a long side chain Nafion 212 membrane (equivalent weight of 1100). An increase in the equivalent weight leads to an increase in the sorption exchange capacity and water uptake of the membranes and a decrease in their proton conductivity. The conductivity of the Aquivion membrane with an equivalent weight of 870 is 1.4–1.5 times higher than that of the Nafion 212 membrane; it reaches 13.6 mS/cm in contact with water and 1.0 mS/cm at a relative humidity of 32% at 25°C. Diffusion permeability and cation transport selectivity exhibit a nonmonotonic dependence on the equivalent weight of the material. The lowest diffusion permeability, the highest Na⁺ cation transport selectivity (99.5%), and the best mechanical properties have been found for the Aquivion membrane with an equivalent weight of 965, which is characterized by the highest degree of crystallinity.