Twist-bend nematic phase in cyanobiphenyls and difluoroterphenyls bimesogens

Panov, Vitaly P.; Vij, Jagdish K.; Mehl, Georg H.

Abstract

The paper reviews assignment of the low-temperature nematic phase observed in simple bimesogenic or dimeric systems based on cyanobiphenyls and difluoroterphenyls to the twist-bend nematic phase, NTB, using a range of experimental techniques. These include DSC, X-rays, Polarising Microscopy, electro-optics, birefringence and measurements of the electroclinic effect arising from flexoelectricity. An emphasis is laid on the observations of the chiral domains of opposite handedness at zero field in an otherwise achiral liquid crystalline system in this phase. These observations are a direct consequence of the structure of the twist-bend phase predicted by Ivan Dozov for achiral bent core molecules. The paper reviews the electro-optic phenomena and the observed electroclinic effect and how these observations assign it as the NTB phase. Results of the nanoscale helical pitch measurements using freeze-fracture microscopy are reviewed and discussed briefly. Results of the measurements of elastic constants especially close to the N–NTB transition are also reviewed.

Citation

Panov, V. P., Vij, J. K., & Mehl, G. H. (2017). Twist-bend nematic phase in cyanobiphenyls and difluoroterphenyls bimesogens. Liquid crystals, 44(1), 147-159. https://doi.org/10.1080/02678292.2016.1254289

• Journal Article Type: Article
• Acceptance Date: Nov 20, 2016
• Online Publication Date: Nov 20, 2016
• Publication Date: Jan 2, 2017
• Deposit Date: Nov 24, 2016
• Publicly Available Date: Nov 24, 2016
• Journal: Liquid crystals
• Print ISSN: 0267-8292
• Electronic ISSN: 1366-5855
• Publisher: Taylor and Francis
• Peer Reviewed: Peer Reviewed
• Volume: 44
• Issue: 1
• Pages: 147-159
• DOI: https://doi.org/10.1080/02678292.2016.1254289
• Keywords: Twist bend nematic phase; Dimers; Nematic liquid crystals; Electroclinic effect; Flexoelectricity
• Public URL: https://hull-repository.worktribe.com/output/445593
• Publisher URL: http://www.tandfonline.com/doi/full/10.1080/02678292.2016.1254289
• Additional Information: This is an Accepted Manuscript of an article published by Taylor & Francis in Liquid crystals on 20/11/2016, available online: http://wwww.tandfonline.com/10.1080/02678292.2016.1254289