Field-controlled columnar and planar patterning of cholesteric colloids

TL;DR

This study demonstrates how time-dependent electric fields can precisely control the patterning and self-assembly of colloidal particles in cholesteric liquid crystals, enabling the creation of complex and metastable structures.

Contribution

It introduces a method to manipulate colloidal arrangements in cholesteric liquid crystals using tailored electric fields, revealing pathways to diverse metastable states and new patterning techniques.

Findings

Electric fields can drive colloids into various metastable structures.

Patterning can be controlled by field amplitude and shape.

Reversible switching between structures is achievable.

Abstract

We study how dispersions of colloidal particles in a cholesteric liquid crystal behave under a time-dependent electric field. By controlling the amplitude and shape of the applied field wave, we show that the system can be reproducibly driven out of equilibrium through different kinetic pathways and navigated through a glassy-like free energy landscape encompassing many competing metastable equilibria. Such states range from simple Saturn rings to complex structures featuring amorphous defect networks, or stacks of disclination loops. A non-equilibrium electric field can also trigger the alignment of particles into columnar arrays, through defect-mediated force impulses, or their repositioning within a plane. Our results are promising in terms of providing new avenues towards controlled patterning and self-assembly of soft colloid-liquid crystal composite materials.