The impact of the interfacial Kapitza resistance on colloidal thermophoresis

Abstract: Thermal gradients impart thermophoretic forces on colloidal particles, pushing colloids towards cold or hot regions, a phenomenon called thermophoresis. Current theoretical approaches relate the Soret coefficient to local changes in the interfacial tension around the colloid, which lead to fluid flow around the colloid surface. The Kapitza resistance, a key variable in the description of interfacial heat transport, is an experimentally accessible property that modifies interfacial thermal fields. Here, we introduce a theoretical approach that describes colloid thermophoretic forces by incorporating explicitly Kapitza resistance effects. Our formulation can be used to monitor the dependence of thermophoresis on the interfacial thermal resistance. We show that the resistance modifies the thermal field around the colloids and identify experimental conditions where the Kapitza resistance influences the thermophoretic forces. We validate our theoretical approach by implementing a non-equilibrium molecular dynamics model of a colloid suspended in a solvent.