The Chiral Twist-Bend Nematic Phase (N*TB)

Rebecca Walker (Corresponding Author), Damian Pociecha, John Mervyn David Storey, Ewa Gorecka, Corrie Thomas Imrie

Research output: Contribution to journalArticle

Abstract

The twist-bend nematic, NTB, phase has been observed for chiral material in which chirality is introduced through a branched 2-methylbutyl terminal tail. The chiral twist-bend nematic phase, N*TB, is completely miscible with the NTB phase of the standard achiral material, CB6OCB. The N*TB phase exhibits optical textures with lower birefringence than those observed for the achiral NTB phase, suggesting an additional mechanism of averaging molecular orientations. The N*-N*TB transition temperatures for the chiral materials are higher than the NTB-N transition temperatures seen for the corresponding racemic materials. This suggests the double degeneracy of helical twist sense in the N*TB phase is removed by the intrinsic molecular chirality. A square lattice pattern is observed in the N* phase over a temperature range of several degrees above N*TB- N phase transition, which may be attributed to a non-monotonic dependence of bend elastic constant.

Original languageEnglish
JournalChemistry : a European Journal
Early online date19 Jul 2019
DOIs
Publication statusE-pub ahead of print - 19 Jul 2019

Fingerprint

Chirality
Superconducting transition temperature
Molecular orientation
Elastic constants
Birefringence
Textures
Phase transitions
Temperature

Keywords

  • liquid crystals
  • chirality
  • spontaneous symmetry breaking
  • twist-bend nematic phase

Cite this

The Chiral Twist-Bend Nematic Phase (N*TB). / Walker, Rebecca (Corresponding Author); Pociecha, Damian; Storey, John Mervyn David; Gorecka, Ewa; Imrie, Corrie Thomas.

In: Chemistry : a European Journal, 19.07.2019.

Research output: Contribution to journalArticle

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abstract = "The twist-bend nematic, NTB, phase has been observed for chiral material in which chirality is introduced through a branched 2-methylbutyl terminal tail. The chiral twist-bend nematic phase, N*TB, is completely miscible with the NTB phase of the standard achiral material, CB6OCB. The N*TB phase exhibits optical textures with lower birefringence than those observed for the achiral NTB phase, suggesting an additional mechanism of averaging molecular orientations. The N*-N*TB transition temperatures for the chiral materials are higher than the NTB-N transition temperatures seen for the corresponding racemic materials. This suggests the double degeneracy of helical twist sense in the N*TB phase is removed by the intrinsic molecular chirality. A square lattice pattern is observed in the N* phase over a temperature range of several degrees above N*TB- N phase transition, which may be attributed to a non-monotonic dependence of bend elastic constant.",
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N2 - The twist-bend nematic, NTB, phase has been observed for chiral material in which chirality is introduced through a branched 2-methylbutyl terminal tail. The chiral twist-bend nematic phase, N*TB, is completely miscible with the NTB phase of the standard achiral material, CB6OCB. The N*TB phase exhibits optical textures with lower birefringence than those observed for the achiral NTB phase, suggesting an additional mechanism of averaging molecular orientations. The N*-N*TB transition temperatures for the chiral materials are higher than the NTB-N transition temperatures seen for the corresponding racemic materials. This suggests the double degeneracy of helical twist sense in the N*TB phase is removed by the intrinsic molecular chirality. A square lattice pattern is observed in the N* phase over a temperature range of several degrees above N*TB- N phase transition, which may be attributed to a non-monotonic dependence of bend elastic constant.

AB - The twist-bend nematic, NTB, phase has been observed for chiral material in which chirality is introduced through a branched 2-methylbutyl terminal tail. The chiral twist-bend nematic phase, N*TB, is completely miscible with the NTB phase of the standard achiral material, CB6OCB. The N*TB phase exhibits optical textures with lower birefringence than those observed for the achiral NTB phase, suggesting an additional mechanism of averaging molecular orientations. The N*-N*TB transition temperatures for the chiral materials are higher than the NTB-N transition temperatures seen for the corresponding racemic materials. This suggests the double degeneracy of helical twist sense in the N*TB phase is removed by the intrinsic molecular chirality. A square lattice pattern is observed in the N* phase over a temperature range of several degrees above N*TB- N phase transition, which may be attributed to a non-monotonic dependence of bend elastic constant.

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