Coexistence of nonequilibrium phases in assemblies of driven nematic colloids

TL;DR

This study combines experiments, theory, and simulations to explore how driven colloidal particles in a nematic liquid crystal can form coexisting nonequilibrium phases, revealing insights into active matter organization.

Contribution

It introduces a comprehensive model and experimental approach to understand phase coexistence and pressure in driven colloidal systems within nematic liquid crystals.

Findings

Measured non-equilibrium equation of state for driven colloids

Simulations accurately reproduce observed phase coexistence

Identified long-range electrostatic and hydrodynamic interactions as key factors

Abstract

We combine experiments, theory, and simulations to investigate the coexistence of nonequilibrium phases emerging from interacting colloidal particles that are electrokinetically propelled in a nematic liquid crystal solvent. We directly determine the mechanical pressure within the radial assemblies and measure a non-equilibrium equation of state for this athermal driven system. A generic model combines phoretic propulsion with the interplay between electrostatic effects and liquid-crystal-mediated hydrodynamics, which are effectively cast into a long-range interparticle repulsion, while elasticity plays a subdominant role. Simulations based on this model explain the observed collective organization process and phase coexistence quantitatively. Our colloidal assemblies provide an experimental test-bed to investigate the fundamental role of phoretic pressure in the organization of driven out-of-equilibrium matter.