Thermally driven rotation of cholesteric droplets dispersed in an immiscible liquid

Abstract

We have demonstrated the thermally driven rotation of cholesteric (Ch) droplets in glycerol for the first time. When an emulsion consisting of glycerol medium and dispersed Ch droplets was introduced into the gap between two hydrophilic glass substrates and a temperature gradient was applied in the direction perpendicular to the substrates, the Ch droplets exhibited steady unidirectional rotation (the Lehmann rotation) under an optical microscope. Since the moderate temperature gradient does not induce mass transport in the thin immiscible emulsion, the steady rotation of the droplets should be directly driven by the heat flux through pure thermomechanical coupling.