Proton transference number of PFSA ionomer membranes

The cation transference number of the novel XUS (Dow Chemical) ionomer membrane was measured by the employment of protonic conducting solution electrodes. The limiting values of the equivalent conductivity of H+ and OH- at various solution concentrations were obtained by extrapolation to yield the membrane proton transference number. The result of 81% was compared to that of NAFIONR and aqueous solution to show an inverse relationship between the transference number and the size of the environment accommodating the water molecules, which constitutes some understanding of the ionic conducting mechanism.