Eur. Phys. J. E (2006) 20: 237-242
https://doi.org/10.1140/epje/i2006-10017-1

Regular Article

Colloidal particles at a nematic-isotropic interface: Effects of confinement

¹ Liquid Crystal Institute, Kent State University, 44242, Kent, OH, USA
² University of Colorado at Colorado Springs, 80933, Colorado Springs, CO, USA
³ Max-Plank Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
⁴ Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569, Stuttgart, Germany
⁵ Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany
⁶ Institute of Physics, Prospect Nauky 46, 03039, Kyiv, Ukraine

^* e-mail: miko@fluids.mpi-stuttgart.mpg.de

Received: 9 January 2006
Accepted: 6 June 2006
Published online: 22 June 2006

Abstract

When captured by a flat nematic-isotropic interface, colloidal particles can be dragged by it. As a result spatially periodic structures may appear, with the period depending on particle mass, size, and interface velocity (J.L. West, A. Glushchenko, G.X. Liao, Y. Reznikov, D. Andrienko, M.P. Allen, Phys. Rev. E 66, 012702 (2002)). If liquid crystal is sandwiched between two substrates, the interface takes a wedge-like shape, accommodating the interface-substrate contact angle and minimizing the director distortions on its nematic side. Correspondingly, particles move along complex trajectories: they are first captured by the interface and then “glide” towards its vertex point. Our experiments quantify this scenario, and numerical minimization of the Landau-de Gennes free energy allows for a qualitative description of the interfacial structure and the drag force.