Electric field-induced giant columns of polarized water molecules

Abstract

In confined nanoscale structures, such as nanopores or nanotubes, the polar characteristic of water can be evident; while in bulk or droplet form, it is masked by the statistical molecular arrangements dictated by free energy minimization. In this paper, we show that, under an applied electric field, the polar character of water molecules enables the formation of macroscopic scale columns of water vapor penetrating through a silicone oil bath. These columns are up to 60 μm in length and tens of microns in cross-sectional dimension. We have directly visualized such columns by using water-soluble fluorescent molecules dispersed in silicone oil. The polar nature of columns is evidenced by the measured giant electrorheological effect that correlates with the application of an electric field. We present a phenomenological theory to support our observations and show that the experimental data are consistent with a state of highly aligned water molecular dipoles within each column.