Colloidal particles in liquid crystal films and at interfaces

Abstract

This mini-review discusses the recent contribution of theoretical and computational physics as well as experimental efforts to the understanding of the behavior of colloidal particles in confined geometries and at liquid crystalline interfaces. Theoretical approaches used to study trapping, long-and short-range interactions, and assembly of solid particles and liquid inclusions are outlined. As an example, an interaction of a spherical colloidal particle with a nematic-isotropic interface and a pair interaction potential between two colloids at this interface are obtained by minimizing the Landau-de Gennes free energy functional using the finite-element method with adaptive meshes.

Transport of particles in liquid crystals

“…A rough estimate of the order of magnitude of the elastic energy associated with the director distortions around a strongly anchored micron-size particle placed in an otherwise uniform nematic cell, is 56 . Forces of the same nature are also responsible for attraction of colloidal particles to (particle-free) distortions and defects in the director field in nematics 47,57,58 , smectics [59][60][61] and blue phases 62 , for trapping and ordering of particles at the LC surfaces [63][64][65][66] , and even for symmetry-breaking that enables transport phenomena such as nonlinear electrophoresis in LCs 45,67 . As discussed in the next…”

“…Anisotropic arrangements can be also staged at the interfaces, involving an isotropic medium and various LC phases, such as nematic [63][64][65]161 , cholesteric 58,66 , and smectic 59,61,162 . Trapping and dragging colloids by moving isotropic-LC interface offers another interesting mechanism of transport 163 .…”

Liquid crystal boojum-colloids

“…Controlling the self-assembly of colloidal particles is an important aspect of pure and applied colloid science. In this context, assembling novel structures in liquid crystal (LC) matrices has become a very active field of research as a result of important theoretical and experimental advances [1][2][3]. LCs are characterized by anisotropic mechanical and optical properties due to the long-range orientational molecular ordering.…”

Topological defects around a spherical nanoparticle in nematic liquid crystal: Coarse-grained molecular dynamics simulations

“…[10][11][12][13] To be more specific, direct experimental measurements were performed by Poulin et al 14 Continuum theory, where one minimizes the Frank-Oseen 10,15,16 or the Landau-de Gennes free energy, 17 was developed, including the use of various ansatz functions. 16,18 Monte Carlo [19][20][21] as well as molecular dynamics [22][23][24] simulations have been conducted using a range of models.…”