Eur. Phys. J. E (2019) 42: 99
https://doi.org/10.1140/epje/i2019-11867-x

Regular Article

A thermomechanical coupling in cholesteric liquid crystals: Unidirectional rotation of double-twist cylinders driven by heat flux

¹ Faculty of Science and Engineering, Waseda University, Tokyo, Japan
² Kagami Memorial Research Institute for Material Science and Technology, Waseda University, Tokyo, Japan

^* e-mail: tabe@waseda.jp

Received: 14 March 2019
Accepted: 16 July 2019
Published online: 9 August 2019

Abstract

We made aggregates of cholesteric liquid crystalline Cylinders with Double-Twist orientational structure (DTC) and investigated their rigid-body rotation under a temperature gradient, focusing on how the rotational speed should depend on the cylinder size. The experimental results showed that the angular velocity of the DTC aggregates linearly increased with the height of the cylinders and was inversely proportional to the base area. With a phenomenological equation, we analyzed the torque caused by the heat flux and its balance with the viscous friction, and found that the simple analysis well explained the size-dependence of the rotation of the DTC aggregates. The coupling constant between the heat flux and the torque to drive the rigid-body rotation was in the same order of magnitude as that for the director rotation.