Heat-flux-driven Rotation of Cholesteric Droplets Dispersed in Glycerol

Micron-sized cholesteric droplets dispersed in glycerol exhibit steady rigid rotation under a uniform temperature gradient about the axis parallel to the gradient. The rotational velocity is linear to the temperature gradient, and the chirality inversion reverses the rotational direction. The result clearly contrasts previous studies showing that cholesteric droplets in immiscible liquids such as glycerol and water never rotated under a temperature gradient. We demonstrated the steady and continuous rotation of the cholesteric droplets driven by a heat flux by hydrophilizing the substrate surface to adsorb the glycerol molecules. The thermomechanical coupling constant was found to be divide v divide >= 3 x 10-7 N m-1 K-1.