Electrostatic Interactions of Colloidal Particles Straddling a Fluid-Fluid Interface.

Colloidal particles can irreversibility adsorb and exhibit finite contact angles at a fluid-fluid interface (Binks 2002). Such particle laden interfaces are often encountered in applications involving multiphase systems such as foams, drops and bubbles where the particles are added as stabilizing agents or can be present naturally as impurities (Binks 2017). These particles can modify the rheology of the fluid interface and can introduce additional physics (such as aggregation, interfacial undulations etc.) especially under the presence of interparticle interactions. The presence of an applied electric field or charges on the particle surface can lead to the well-established electrostatic interactions that are often studied in the asymptotic limit of dilute surface concentrations of particles (Danov and Kralchevsky 2006). Here we present a more detailed look at the electrostatic interactions between two spherical particles for arbitrary finite separations under the presence of an electric field. We investigate in detail the effect of the contact angles and the dielectric properties of the particles along with that of the fluid media. These results can prove beneficial in improving the current models (Laal-Dehghani and Christopher 2019) for simulating particle laden interfaces.