Nematic Liquid-Crystal Colloids.

Igor Muševič

doi:10.3390/ma11010024

Abstract

This article provides a concise review of a new state of colloidal matter called nematic liquid-crystal colloids. These colloids are obtained by dispersing microparticles of different shapes in a nematic liquid crystal that acts as a solvent for the dispersed particles. The microparticles induce a local deformation of the liquid crystal, which then generates topological defects and long-range forces between the neighboring particles. The colloidal forces in nematic colloids are much stronger than the forces in ordinary colloids in isotropic solvents, exceeding thousands of kBT per micrometer-sized particle. Of special interest are the topological defects in nematic colloids, which appear in many fascinating forms, such as singular points, closed loops, multitudes of interlinked and knotted loops or soliton-like structures. The richness of the topological phenomena and the possibility to design and control topological defects with laser tweezers make colloids in nematic liquid crystals an excellent playground for testing the basic theorems of topology.

Highlights

The director can have an arbitrary direction in space, but in reality it always points along some preferred direction, because the liquid crystal is usually confined to a measuring cell
We have presented the rich topology of a nematic liquid crystal around a spherical or Colloids: and Koch-Star
We have presented the rich topology of a nematic liquid crystal around a spherical or of the nematic liquid crystal

Summary

Introduction

Θ is the angle between the long axis of a selected molecule and the average direction of the orientation, the director n. If the nematic liquid crystal is heated above a certain temperature, the orientational order is suddenly and completely lost and there is a first-order phase transition into the isotropic state of the nematic liquid crystal. In this isotropic phase, the nematic liquid crystal behaves as an ordinary liquid with complete orientational disorder, and S = 0

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Conclusion