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Physical properties of some novel nematic bimesogens for the flexoelectric effect

Schott, C and Perkins, SP and Coles, HJ (2001) Physical properties of some novel nematic bimesogens for the flexoelectric effect. Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals, 366. pp. 715-724. ISSN 1058-725X

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Abstract

In a chiral nematic liquid crystal, the flexoelectric effect consists of a fast and linear coupling with an applied electric field. One difficulty to overcome is the unwinding of the helix that occurs at higher fields due to dielectric coupling. The use of bimesogens, which possess very low molecular dielectric anisotropy can improve flexoelectric characteristics. New bimesogen compounds have recently been synthesised that exhibit switching angles of 45° for applied fields of about 9 V.μm-1. In this paper, results from dielectric, electro-optic and dynamic light scattering measurements are reported for the new bimesogenic mixture. The dielectric anisotropy Δε changes sign with temperature and its values range between -0.2 and 0.3 for the temperature range studied. For Δε weakly positive, no electric field Freedericksz transition could be induced but Williams domains are observed instead. The large decrease in the bend elastic constant to viscosity coefficient ratio is attributed to a large increase in the bend viscosity coefficient. © 2001 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint, a member of the Taylor & Francis Group.

Item Type: Article
Uncontrolled Keywords: Bimesogens Dielectric anisotropy Dynamic light scattering Visco-elastic properties Williams domains
Subjects: UNSPECIFIED
Divisions: Div B > Photonics
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 12:01
Last Modified: 08 Dec 2014 02:30
DOI: