Frequency dependent deformation of liquid crystal droplets in an external electric field

TL;DR

This study investigates how liquid crystal droplets deform under alternating electric fields at different frequencies, revealing frequency-dependent shape changes explained by dielectric and conductivity effects.

Contribution

It provides a quantitative model combining leaky dielectric theory and field screening to explain frequency-dependent droplet deformation in liquid crystals.

Findings

Droplets remain spherical at low and high frequencies.

Significant flattening occurs at intermediate frequencies.

Model accurately predicts deformation behavior.

Abstract

Nematic drops suspended in the isotropic phase of the same substance were subjected to alternating electrical fields of varying frequency. The system was carefully kept in the isotropic-nematic coexistance region, which was broadened due to small amounts of non-mesogenic additives. Whereas the droplets remained spherical at low (order of 10 Hz) and high frequencies (in the kHz range), at intermediate frequencies, we observed a marked flattening of the droplet in the plane perpendicular to the applied field. The deformation of the liquid crystal (LC) droplets occurred both in substances with positive and negative dielectric anisotropy. The experimental data can be quantitatively modelled with a combination of the leaky dielectric model and screening of the applied electric field due to the finite conductivity.