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Splay-bend elasticity of a nematic liquid crystal with T-shaped molecules

P. Sathyanarayana1, M. C. Varia2, A. K. Prajapati2, B. Kundu1,*, V. S. S. Sastry1, and S. Dhara1,†

  • 1School of Physics, University of Hyderabad, Hyderabad 500046, India
  • 2Department of Applied Chemistry, Faculty of Technology and Engineering, M. S. University of Baroda, Vadodara 390001, India

  • *Present address: Liquid Crystal Institute, Tokyo University of Science, Yamaguchi, Japan.
  • †Corresponding author; sdsp@uohyd.ernet.in
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Phys. Rev. E 82, 050701(R) – Published 10 November, 2010

DOI: https://doi.org/10.1103/PhysRevE.82.050701

Abstract

We measured the splay (K11) and bend (K33) elastic constants in the nematic phase of a liquid crystal with T-shaped molecules. We find that the ratio, K33/K11≃1 in the entire nematic range except very close to the nematic to Sm-A (SN) transition. Both K33 and K11 show pretransitional divergence as the SN transition is approached from higher temperature. The ratio, K33/K11 suggests that the length (L) to effective width (D) ratio (i.e., L/D) is significantly smaller due to the presence of long and flexible lateral group, compared to that of rigid rodlike molecules. It is argued that apart from the extra contribution to the elasticity the long and flexible lateral group also has a significant contribution to the suppression of the splay fluctuations in the onset of smectic short-range fluctuation. The structure of the Sm-A phase is investigated by using small angle x-ray diffraction, and a possible arrangement of the molecules in the Sm-A layer is proposed.

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Outline

Information

Phys. Rev. E 82, 050701(R)– Published 10 November, 2010
  • Received 14 April 2010

© 2010 American Physical Society

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