Cluster Formation in One-Patch Colloids: Low Coverage Results

We perform Monte Carlo simulations of a simple one-patch colloidal model to investigate the cluster formation and the phase behavior of the system on changing the width of the patch. We investigate the parameter region where the coverage (defined as the ratio between attractive and total surface) varies from 50% (the Janus case) to zero (hard-sphere). Simulation results indicate that on decreasing the coverage, particles self-assemble into clusters of different shapes, from micelles close to the Janus case, to one and two dimensional aggregates (wires and lamellae) for smaller coverage. Close to the hard-sphere limit, small micelles and dimers dominate the scene. We never find evidence of a gas-liquid (colloidal-rich/colloidal-poor) phase separation: it confirms that self-assembly into clusters which expose to their neighbors mostly repulsive surfaces suppresses phase separation and stabilizes cluster phases.