Computer simulation of dipolar-depletion colloids

Abstract

An experimental colloid-polymer mixture with an applied external electric field is subject to an induced dipole interaction and an effective attraction due to depletion of polymer in between close-approaching colloidal spheres. The electric field strength and polymer concentration affect the strength of these interactions and thus lead to distinct phase transitions and, more generally, a variation in local order with these parameters. A computational system replicating the experiment is developed to examine the static properties of the colloid, with greater spatial resolution in the direction of polarisation and increased control of parameters compared to experiment. Such an approach is adopted to attempt to resolve the question of decreased local order at high-polymer, high-field state points past a certain threshold, before which local order was observed to increase.