Dynamics of Pyrrolidinium-Based Ionic Liquids under Confinement. I. Analysis of Dielectric Permittivity

Dielectric spectroscopy of geometrically confined ionic liquids is an effective approach to study how finite size and interfacial effects modify the conductivity behavior. An ideal geometry for such experiments are pores or channels that run parallel to the electric field lines, as in this case, no Maxwell-Wagner-type effect is assumed to interfere with a straightforward data analysis. However, the permittivity of such channels in anodized alumina membranes filled with the ionic liquid shows the hallmark of significant Maxwell-Wagner-type polarization. This work provides a simple model that explains this lack of low-frequency conductivity, assuming air pockets to be located between the liquid and the electrode. A correction of the observed data according to this model provides an improved definition of the dc-conductivity levels.