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Updated: Mar 24, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Similarities and differences between molecular order in the nematic and twist-bend nematic phases of a symmetric
J W Emsley1, M Lelli2, H Joy3
1Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UK. jwe@soton.ac.uk.
Abstract:
The order parameter, Szz, where z is the para axis of the difluoroterphenyl groups in DTC5C9, has been obtained from chemical shift anisotropies measured by (13)C - {(1)H} NMR experiments at temperatures throughout the nematic, NU, and twist-bend nematic, NTB, phases shown by this compound. The order parameter temperature profiles are unusual in having a maximum value in the NU phase and then decreasing until the NTB phase is reached. There is a small discontinuity (∼2%) in Szz at TNNTB and then a gradual decrease until a new phase appears. This behaviour is interpreted as revealing a temperature-dependent tilting of local directors in both phases away from the applied magnetic field direction. In the enantiomorphic twist-bend phase this tilt is consistent with the structure of the phase as a helical arrangement of local directors, whilst in the high-temperature non-chiral nematic the tilt must involve a non-chiral arrangement. It is proposed that in both phases the tilting of directors has a common origin in the bent shape of the molecules.
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