Anomalous Dielectric Behavior of Nanoconfined Electrolytic Solutions
Abstract
We report an anomalous dielectric effect of electrolytes under cylindrical nanoconfinement. In bulk phase, the decrease in the water dielectric constant ( ) with increasing salt concentration is well known, and is due to dielectric saturation. From molecular dynamic simulations of confined water and NaCl solutions, we show a dielectric anisotropy and an unexpected increase in ? of NaCl solutions with respect to the confined pure liquid until a critical concentration is reached. We infer that this striking dielectric behavior results from the interplay between the effect of confinement and that of ions on the water hydrogen bonding network.