Soft Matter. 2014 Aug 14;10(30):5489-502. doi: 10.1039/c4sm00959b.

Disclination lines at homogeneous and heterogeneous colloids immersed in a chiral liquid crystal.

Soft matter

Michael Melle, Sergej Schlotthauer, Carol K Hall, Enrique Diaz-Herrera, Martin Schoen

PMID: 24954626 DOI: 10.1039/c4sm00959b

Abstract

In the present work we perform Monte Carlo simulations in the isothermal-isobaric ensemble to study defect topologies formed in a cholesteric liquid crystal due to the presence of a spherical colloidal particle. Topological defects arise because of the competition between anchoring at the colloidal surface and the local director. We consider homogeneous colloids with either local homeotropic or planar anchoring to validate our model by comparison with earlier lattice Boltzmann studies. Furthermore, we perform simulations of a colloid in a twisted nematic cell and discuss the difference between induced and intrinsic chirality on the formation of topological defects. We present a simple geometrical argument capable of describing the complex three-dimensional topology of disclination lines evolving near the surface of the colloid. The presence of a Janus colloid in a cholesteric host fluid reveals a rich variety of defect structures. Using the Frank free energy we analyze these defects quantitatively indicating a preferred orientation of the Janus colloid relative to the cholesteric helix.

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't
• Research Support, U.S. Gov't, Non-P.H.S.