Reentrant Phase Behavior in Active Colloids with Attraction

TL;DR

This study investigates how activity influences phase behavior in self-propelled colloids with attraction, revealing a reentrant phase transition with distinct kinetic regimes, supported by simulations and a kinetic model.

Contribution

It introduces a kinetic model explaining reentrant phase behavior in active colloids with attraction, supported by simulation results.

Findings

Phase-separated states occur at both low and high activity levels.

A homogeneous active fluid exists at intermediate activity levels.

Kinetic behaviors include nucleation, growth, and complex coarsening.

Abstract

Motivated by recent experiments, we study a system of self-propelled colloids that experience short-range attractive interactions and are confined to a surface. Using simulations we find that the phase behavior for such a system is reentrant as a function of activity: phase-separated states exist in both the low- and high-activity regimes, with a homogeneous active fluid in between. To understand the physical origins of reentrance, we develop a kinetic model for the system's steady-state dynamics whose solution captures the main features of the phase behavior. We also describe the varied kinetics of phase separation, which range from the familiar nucleation and growth of clusters to the complex coarsening of active particle gels.