Statistical mechanical theories of the anchoring transition and related phenomena in liquid crystals
Statistical mechanical theories of the anchoring transition and related phenomena in liquid crystals
We have generalised earlier work on anchoring of nematic liquid crystals by Sullivan, and Sluckin and Poniewierski. Microscopic expressions have been obtained for the anchoring energy of pure and mixed liquid crystals in contact with (a) a solid aligning surface; (b) immiscible one- and two-component isotropic media. Possible anchoring phase diagrams of a binary liquid crystal mixture at an aligning solid substrate have been calculated for a simple liquid crystal model. These may exhibit re-entrant conical anchoring for not too unrealistic values of the molecular parameters. The theory was then extended to take into account the adsorption of a non-nematic impurity at the nematic-solid interface. This was achieved by decoupling adsorption and anchoring, and using the Cahn theory of wetting to treat the former. The anchoring angle has been calculated over the whole concentration range of the impurity, in the partial wetting regime, and in the near saturation region, in the complete wetting regime. Anchoring transitions have been found which are fairly temperature-independent (`universal'), as seen in real systems.
We have used Landau-de Gennes theory to study anchoring at the interface between a nematic liquid crystal and a smooth solid substrate. In contrast to earlier work, we allow for a spatially varying tilt angle. We have found that temperature-driven anchoring transitions akin to those observed experimentally can obtain either as a result of the change in the surface order parameter or due to competition between the ordering effects of the solid surface and the nascent isotropic-nematic interface as TNI is approached, in the regime of complete wetting by the isotropic phase. Predictions have also been made for the experimentally observable values of the anchoring energy.
University of Southampton
Teixeira, Paulo Ivo Cortez
1993
Teixeira, Paulo Ivo Cortez
Teixeira, Paulo Ivo Cortez
(1993)
Statistical mechanical theories of the anchoring transition and related phenomena in liquid crystals.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
We have generalised earlier work on anchoring of nematic liquid crystals by Sullivan, and Sluckin and Poniewierski. Microscopic expressions have been obtained for the anchoring energy of pure and mixed liquid crystals in contact with (a) a solid aligning surface; (b) immiscible one- and two-component isotropic media. Possible anchoring phase diagrams of a binary liquid crystal mixture at an aligning solid substrate have been calculated for a simple liquid crystal model. These may exhibit re-entrant conical anchoring for not too unrealistic values of the molecular parameters. The theory was then extended to take into account the adsorption of a non-nematic impurity at the nematic-solid interface. This was achieved by decoupling adsorption and anchoring, and using the Cahn theory of wetting to treat the former. The anchoring angle has been calculated over the whole concentration range of the impurity, in the partial wetting regime, and in the near saturation region, in the complete wetting regime. Anchoring transitions have been found which are fairly temperature-independent (`universal'), as seen in real systems.
We have used Landau-de Gennes theory to study anchoring at the interface between a nematic liquid crystal and a smooth solid substrate. In contrast to earlier work, we allow for a spatially varying tilt angle. We have found that temperature-driven anchoring transitions akin to those observed experimentally can obtain either as a result of the change in the surface order parameter or due to competition between the ordering effects of the solid surface and the nascent isotropic-nematic interface as TNI is approached, in the regime of complete wetting by the isotropic phase. Predictions have also been made for the experimentally observable values of the anchoring energy.
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Published date: 1993
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Local EPrints ID: 462200
URI: http://eprints.soton.ac.uk/id/eprint/462200
PURE UUID: 77369a44-02bd-4064-b7bb-ae3ee683e692
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Date deposited: 04 Jul 2022 19:03
Last modified: 04 Jul 2022 19:03
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Author:
Paulo Ivo Cortez Teixeira
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