Topology-dependent self-structure mediation and efficient energy conversion in heat-flux-driven rotors of cholesteric droplets

• Published in: Nature communications 2018-01, Vol.9 (1), p.432-11, Article 432
• Main Authors: Yoshioka, Jun, Araoka, Fumito
• Format: Article
• Language: English
• Subjects: 639/301; 639/301/923/919; 639/766/189; Cholesteric liquid crystals; Coexistence; Crystals; Dispersion; Droplets; Energy conversion; Energy Transfer; Fluctuations; Heat; Heat flux; Hot Temperature; Humanities and Social Sciences; Liquid crystals; Liquid Crystals - chemistry; multidisciplinary; Phase transitions; Rotating liquids; Rotation; Rotors; Science; Science (multidisciplinary); Topology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-02910-z

When heat flux is applied to a chiral liquid crystal, unidirectional rotation is induced around the flux axis, as first discovered by Otto Lehmann in 1900. In recent years, this heat-flux-induced phenomenon has been studied mostly in droplets of cholesteric liquid crystals undergoing phase transition from the isotropic to cholesteric phase, i.e., in the coexistence region, which occurs over a very narrow temperature range. Here, we report that the heat-flux-induced rotation can be stabilised by the use of a dispersion system, in which the cholesteric droplets are dispersed in a viscous and poorly miscible isotropic solvent. Interestingly, the phenomenon is found to be topology dependent. Moreover, the rotation is not only stable but also more efficient than that in the known systems. We describe in detail how the dynamics of the heat-flux-induced rotation are altered in the present dispersion system. The Lehmann effect describes the spontaneous rotation of cholesteric liquid crystals in response to heat input. Here, the authors stabilise it by dispersing cholesteric droplets into a poorly miscible solvent and show dependences of rotation speed and conversion efficiency on the topological states.