EPR study of the polydomain structure of the twist-bend nematic phase of CB9CB in the bulk

ABSTRACT

EPR spin probe spectra of the liquid crystal phases exhibited, in the bulk, by the 1″,9″-bis(4-cyanobiphenyl-4’-yl)nonane (CB9CB) bent-shape dimer showed that, on cooling from the isotropic phase, this material forms a uniaxial nematic phase with a uniform director macroscopically aligned along the spectrometer field. Upon further cooling, a transition into the twist-bend nematic phase is observed after a biphasic region of approximately 4 K. In this lower temperature nematic phase, the director does not appear to be macroscopically aligned. The non-uniform director distribution is modelled as a collection of monodomains tilted with respect to the magnetic field and orientationally distributed around the tilt direction.

Graphical Abstract

KEYWORDS:

• Bent-shaped bimesogenic liquid-crystals
• dimers
• orientational order
• dynamics

Acknowledgments

The authors thank MIUR, the University of Bologna and the CINFO Computer Center, University of Camerino for support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Project BIND, funded under FP7-ICT [grant number 216025].