The determination of molecular parameters from dielectric measurements on nematic liquid crystals
The determination of molecular parameters from dielectric measurements on nematic liquid crystals
bThe physical properties of liquid crystal phases (mesophases) depend in a very sensitive manner on the structure of the constituent liquid crystal-forming molecules (mesogens). Thus a small change in molecular structure can result in a dramatic change in the corresponding liquid crystal properties. The dielectric responses of materials reflect the electric properties of molecules, and so analysis of dielectric measurements on liquid crystals in terms of molecular properties should lead to the development of structure/property relationships for such mesophases. This paper explores the problems of determining molecular parameters from dielectric measurements on nematic liquid crystals. Specifically, the difficulties in defining the internal electric field and knowing the value of the order parameter are addressed. Experimental results on a range of liquid crystals show that short range correlations are important in determining both the dielectric and optical response of nematic liquid crystals. It is concluded therefore that more sophisticated molecular theories, which take account of molecular shape and volume, need to be developed before reliable structure/property relationships can be established for liquid crystals.
dipole association, light-scattering, relaxation, theorie, mesogens, systems, solvent, phase, field
1379-1387
Dunmur, D.A.
d10d31b4-e7ac-4a9d-9cfc-b53f1b1a35a7
2005
Dunmur, D.A.
d10d31b4-e7ac-4a9d-9cfc-b53f1b1a35a7
Dunmur, D.A.
(2005)
The determination of molecular parameters from dielectric measurements on nematic liquid crystals.
Liquid Crystals, 32 (11-12), .
(doi:10.1080/02678290500124684).
Abstract
bThe physical properties of liquid crystal phases (mesophases) depend in a very sensitive manner on the structure of the constituent liquid crystal-forming molecules (mesogens). Thus a small change in molecular structure can result in a dramatic change in the corresponding liquid crystal properties. The dielectric responses of materials reflect the electric properties of molecules, and so analysis of dielectric measurements on liquid crystals in terms of molecular properties should lead to the development of structure/property relationships for such mesophases. This paper explores the problems of determining molecular parameters from dielectric measurements on nematic liquid crystals. Specifically, the difficulties in defining the internal electric field and knowing the value of the order parameter are addressed. Experimental results on a range of liquid crystals show that short range correlations are important in determining both the dielectric and optical response of nematic liquid crystals. It is concluded therefore that more sophisticated molecular theories, which take account of molecular shape and volume, need to be developed before reliable structure/property relationships can be established for liquid crystals.
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Published date: 2005
Keywords:
dipole association, light-scattering, relaxation, theorie, mesogens, systems, solvent, phase, field
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Local EPrints ID: 44426
URI: http://eprints.soton.ac.uk/id/eprint/44426
ISSN: 1366-5855
PURE UUID: 1c520f57-c887-4ca8-ab37-06a8c3038764
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Date deposited: 01 Mar 2007
Last modified: 15 Mar 2024 09:04
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D.A. Dunmur
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