How properties of interacting depletant particles control aggregation of hard-sphere colloids

Abstract

We present a numerical study of the effective potential V_eff between two hard-sphere colloids dispersed in an implicit solvent in the presence of interacting depletant particles, for several values of temperature and depletant density, approaching the depletant gas-liquid critical point. We investigate the stability of a system of particles interacting via the pair-wise additive V_eff to evaluate the locus of colloidal aggregation in the phase-diagram of the depletant, and its dependence on the colloids size. We assess how the excluded volume depletion forces are modified by depletant attraction and discuss under which conditions critical fluctuations of the depletant, in the form of critical Casimir forces, can be used to effectively manipulate colloidal aggregation.