Nematic Liquid-Crystal Colloids

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.

SPR Effect Controlled by an Electric Field in a Tapered Optical Fiber Surrounded by a Low Refractive Index Nematic Liquid Crystal

“…The use of LC (as an external medium) possesses anisotropic properties and by the application of an electric field, it is possible to change the molecules orientation and, eventually, influence on the light transmission [22,23]. As it is presented in Figure 2, the liquid crystal (LC) molecules possess two different refractive indices: ordinary (n o ) and extraordinary (n e ), in relation to the measuring axis.…”

Nontrivial topological defects of micro-rods immersed in nematics and their phototuning

“…Both the anchoring competition and geometrical curvatures of surfaces can trigger the inhomogeneous topological texture in space. 1–7 The long-range orientational order of NLCs determines how far the orientational constraints imposed by each surface effectively propagate into the bulk. This characterization length is typically in the micrometer scale for rod-type thermotropic NLCs.…”

Nonequilibrium Dynamics of a Magnetic Nanocapsule in a Nematic Liquid Crystal

“…The order parameter S and the so-called director field describe the degree of order and the average molecular orientation of the nematic state, respectively. When doped with colloidal particles (CPs), nematic liquid crystals become enormously interesting due to fundamental and technological reasons [ 2 , 3 , 4 ]. CPs induce strong deformations on that depend on the colloidal shape and size and on the anchoring conditions that colloidal surfaces impose on liquid crystal molecules [ 5 ].…”