Viscoelectric Effects in Nanochannel Electrokinetics

Electrokinetic transport behavior in nanochannels is different to that in larger-sized channels. Molecular dynamics (MD) simulations in nanochannels have demonstrated two poorly understood phenomena which are not observed in microchannels, being the decreases of (i) average electroosmotic mobility at high surface charge density and (ii) channel conductance at high salt concentrations, as the surface charge is increased. However, current electric double layer (EDL) models do not capture these results. Here we provide evidence that this inconsistency primarily arises from the neglect of viscoelectric (VE) effects in conventional electrokinetic continuum models. We propose a modified continuum model that includes the concepts of a VE immobile layer and a viscoelectric layer (VEL) and that reproduces the above-mentioned nanochannel-specific phenomena. It is shown that the theoretical VE coefficient, estimated based on previous MD results (2.3 × 10–16 m2/V2), is close to previous experimental estimates (5–10 ×...