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ZERO ELECTRIC-FIELD GRADIENT MIXTURES FOR THE ELUCIDATION OF ORIENTATIONAL MECHANISMS

TitleZERO ELECTRIC-FIELD GRADIENT MIXTURES FOR THE ELUCIDATION OF ORIENTATIONAL MECHANISMS
Publication TypeJournal Article
Year of Publication1993
AuthorsBarnhoorn, JBS, de Lange, CA, Burnell, EE
JournalLiquid Crystals
Volume13
Pagination319-343
Date PublishedMar
Type of ArticleArticle
ISBN Number0267-8292
KeywordsANISOTROPIC ENVIRONMENTS, METHANES, MOLECULES, NEMATIC LIQUID-CRYSTALS, NMR, ORDER, SIZE, SOLUTES, SOLVENTS
Abstract

A novel zero electric field gradient nematic liquid crystal made up from two nematic liquid crystal components is employed as a solvent for a series of molecules ranging from small molecules to mesogens themselves. Nuclear magnetic resonance is used to determine the degree of order of the solute and solvent molecules. Results are compared to those obtained for two completely different zero electric field gradient nematic mixtures. The comparison strongly indicates that for a variety of molecules largely differing in size, shape and flexibility their degree of order can be described by a single orientation mechanism. This mechanism can be adequately modelled by a simple phenomenological mean field model based on the size and shape anisotropy of the dissolved species. The use of zero electric field gradient mixtures in combination with this mean field model allows the prediction of solute order parameters at approximately the 10 per cent level.

URL<Go to ISI>://A1993KX19100001