![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
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.
Graphical Abstract
Acknowledgements
We thank Yuri Panarin, Reshma Balachandran, Jang-Kun Song, S. P. Sreenilayam, G. R. Luckhurst and John W. Goodby for fruitful discussions. Work was supported by Award No. 13/US/I2866 from the Science Foundation of Ireland as part of the US–Ireland Research and Development Partnership programme jointly administered with the United States National Science Foundation: [Grant Number NSF-DMR-1410649].
Disclosure statement
No potential conflict of interest was reported by the authors.