Issue 13, 2013

The elastic and optical properties of a bent-core thiadiazole nematic liquid crystal: the role of the bend angle

Abstract

The elastic and optical properties of a bent-core thiadiazole nematic liquid crystal are reported. The system exhibits unusually large values of birefringence (∼0.4), which can be partly attributed to significant conjugation in the molecular structure. It is found that the splay (K11), twist (K22) and bend (K33) elastic constants, determined from studies of the Freedericksz transition, satisfy K33 > K11 > K22 across the wide nematic range studied. Such behaviour is analogous to that commonly observed in calamitic nematic liquid crystals but is in contrast to all other bent-core nematic materials reported to date where it is found that K33 < K11. Such a result questions some of the current explanations that have been put forward to explain the elastic behaviour of bent-core materials. Using a molecular field theory, combined with DFT calculations of the molecular structure, we can ascribe the different elastic behaviour to the value of the bend angle in the molecular core. This angle is shown to play a subtle and substantial role in determining the physical properties of bent-core nematic liquid crystals.

Graphical abstract: The elastic and optical properties of a bent-core thiadiazole nematic liquid crystal: the role of the bend angle

Article information

Article type
Paper
Submitted
14 ธ.ค. 2555
Accepted
22 ม.ค. 2556
First published
22 ม.ค. 2556

J. Mater. Chem. C, 2013,1, 2416-2425

The elastic and optical properties of a bent-core thiadiazole nematic liquid crystal: the role of the bend angle

S. Kaur, L. Tian, H. Liu, C. Greco, A. Ferrarini, J. Seltmann, M. Lehmann and H. F. Gleeson, J. Mater. Chem. C, 2013, 1, 2416 DOI: 10.1039/C3TC00852E

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