Theoretical and numerical study of the phase diagram of patchy colloids: ordered and disordered patch arrangements

TL;DR

This study combines theoretical and numerical methods to analyze how patch arrangements on colloids influence their phase behavior, revealing that patchiness significantly alters the gas-liquid coexistence region.

Contribution

It provides a comprehensive evaluation of the phase diagram for patchy particles with ordered and disordered site arrangements, using Wertheim theory and Monte Carlo simulations.

Findings

Patchiness reduces the gas-liquid coexistence region as the number of sites decreases.

Ordered and disordered patch arrangements significantly affect the phase diagram.

Theoretical predictions align with simulation results for critical points and coexistence lines.

Abstract

We report theoretical and numerical evaluations of the phase diagram for a model of patchy particles. Specifically we study hard-spheres whose surface is decorated by a small number f of identical sites ("sticky spots'') interacting via a short-range square-well attraction. We theoretically evaluate, solving the Wertheim theory, the location of the critical point and the gas-liquid coexistence line for several values of f and compare them to results of Gibbs and Grand Canonical Monte Carlo simulations. We study both ordered and disordered arrangements of the sites on the hard-sphere surface and confirm that patchiness has a strong effect on the phase diagram: the gas-liquid coexistence region in the temperature-density plane is significantly reduced as f decreases. We also theoretically evaluate the locus of specific heat maxima and the percolation line.