Reversal in Thermally Driven Rotation of Chiral Liquid Crystal Droplets

For chiral liquid crystals that express topologically protected defects and thermally driven mechanical rotation, the size- and temperature-driven reversal of the rotational direction of their droplets was demonstrated even under a fixed temperature gradient. This unconventional reversal indicates the dependence of thermomechanical coupling on the molecular orientational order, this dependence is justified through an examination of the size, temperature, and molecular structure as well as by phenomenological arguments on the order parameter.