Electrospun Ionomeric Fibers With Anion Conducting Properties

Anion conductive nanofiber mats from FAA-3 ionomers are obtained by electrospinning. Depending on the solvent used in the precursor solution, nanofibers with either nonhollow cylindrical or flat ribbon-like cross-sections are prepared. The anion conductivity and water uptake of the ionomeric nanofiber mats are measured as a function of the relative humidity in the 10-90% range and compared to that of a solid membrane cast from the same ionomer. In addition, the anion conductivity of an isolated single fiber of the ionomer is measured for the first time. The anion conductivity of the electrospun single fiber is found to be higher than that of the mats, which is, in turn, one order of magnitude higher than that of the solid ionomer membrane. The higher conductivity of the mats relative to the solid membrane (in both in-plane and through-plane directions) is found to be related to the variation in water uptake, which stems from the morphological distinctions. These results increase the understanding of the electrospinning process of ionomers, toward the development and design of new anion conductive ionomer fibers, useful for high performance electrochemical devices.