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Wall-colloid interaction in nematic solvents: external field effects

TitleWall-colloid interaction in nematic solvents: external field effects
Publication TypeJournal Article
Year of Publication2009
AuthorsSokolovska, TG, Patey, GN
JournalJournal of Physics-Condensed Matter
Volume21
Pagination5
Date PublishedJun
Type of ArticleArticle
ISBN Number0953-8984
KeywordsFORCES, LIQUID-CRYSTALS, PARTICLES, TOPOLOGICAL DEFECTS
Abstract

We propose a molecular theory of colloid-wall interactions in nematic media that predicts a new effective force acting on colloidal particles in the presence of an external field. In contrast to the so-called ’image’ interaction that is always repulsive at long distances, the force identified here can be attractive or repulsive, depending on the type of anchoring at the wall and colloidal surfaces. The effective force on a colloidal particle decreases with distance s from the wall as exp(-s/xi), where xi is a magnetic (electric) coherence length. At weak fields the force is proportional to (Sigma/xi)(3) for ’quadrupolar’ colloids and to (Sigma/xi)(2) for ’dipoles’, where Sigma is the colloidal diameter. A brief discussion of recent experiments in the light of our findings is presented.

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