Formation and dynamics of the aggregates of cholesteric double-twist cylinders

Abstract

We succeeded in driving the unidirectional rigid-body rotation of cholesteric (Ch) double-twist cylinder (DTC) droplets under a heat flux along the cylindrical symmetry axis. To directly observe the rigid-body rotation of DTC droplets, in each of which the center of the rotation and the symmetry axis of the structure correspond, we fabricated DTC aggregates that comprise several DTCs with intact structures. Given a steady heat flux, the DTC aggregates metastabilized by the shape and the surface anchoring show a unidirectional rigid-body rotation with a constant angular velocity. The rotational direction is determined by the molecular chirality and the direction of the heat flux, and the rotational velocity increases with the temperature gradient and decreases with the aggregation number N of the DTCs as 1 + 2/sin²(π/N). The behavior agrees with a simple model based on the linear phenomenological equation.