Effective diffusivity of nanoscale ion–water clusters within ion-exchange membranes determined by a novel mechano-electrical technique

This study reports a new method to determine the effective diffusivity of nanoscale ion–water clusters within ion-exchange membranes by means of osmo-electric techniques. The reported method is to induce osmo-electric motion (endo-ionic in nature) within ion-exchange membranes, when a normal load is applied, so as to produce a voltage across the thickness of the membrane. A materials testing system was used to apply a set of consistent pure compressive loads of 200 and 350 N across the surface of an ion-exchange membrane, NafionTM, 2×2 cm2 strip. The maximum output voltage for pressures of 200 N load (73 psi) and 350 N (127 psi) was 80 and 108 mV in amplitude, respectively. The dynamic behavior of induced voltages was also obtained and analyzed based upon the ion–water transport mobility aspect.