  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.
