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Updated: Oct 3, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Chiral conformational fluctuations soften the twist elasticity of nematics
1Department of Applied Physics and Science Education, Eindhoven University of Technology, 5612 AE Eindhoven, The Netherlands.
Abstract:
Achiral nematogens may exhibit transient chiral states that interconvert by thermal fluctuations due to low energetic barriers between left- and right-handed twisted conformations. Allowing for a thermodynamic equilibrium between the mirror-image enantiomers and accounting for favorable chiral interactions between like enantiomeric species, we show by mean-field theory that a mechanical twist deformation in a slab geometry deracemizes such compounds. This, in turn, leads to a softening of the twist elastic response of the nematic. We find that the twist elastic constant vanishes at a second order transition to a state where cholesteric phases with opposite handedness and enantiomeric excess coexist. Even though this transition is usually hidden by a transition to, e.g., a crystalline state, we predict that the twist constant could develop an unusual temperature dependence due to pretransitional effects.
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