Absence of logarithmic attraction between colloids trapped at the interface of droplets: comment on 'Capillary attraction of charged particles at a curved liquid interface' by Alois Wurger

摘要

The possibility of long-ranged attractions between colloids trapped at fluid interfaces is a topic of current interest. The absence of a logarithmic capillary attraction in a flat interface has been demonstrated recently as a consequence of mechanical isolation (see, e.g., ref. [1] and references therein). We have extended this conclusion to the likewise experimentally relevant case of a spherical interface [2, 3]. The corresponding proof is very general (e.g., valid beyond the small-deformation regime, independent of the detailed colloid-interface interaction) and relies only on the condition of mechanical equilibrium. However, ref. [4] reaches the opposite conclusion based on a free energy model for small deformations. Here we demonstrate that actually several errors invalidate this conclusion and thus this Comment provides an independent confirmation of refs. [2, 3] in the context of a simpler modelNote1.