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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Microswimmers and Fluid Physics of Life (joint session DY/CPP)

CPP 38.9: Talk

Wednesday, March 29, 2023, 17:15–17:30, MOL 213

Induced capillary dipoles in floating particle assemblies — •Megan Delens, Ylona Collard, and Nicolas Vandewalle — GRASP, Institut de Physique B5a, Université de Liège, Liège, BE

Capillary-driven self-assembly is a common fabrication method that consists in placing floating particles onto a liquid-air interface. The attractive capillary interaction between particles is due to the local deformations of the interface which can be described via so-called capillary charges. When the particles are spherical and far from each other, the menisci are planar circles and can be described by monopolar capillary charges. The capillary interaction is then approximately found by assuming that the charges carried by individual spheres may be linearly superposed. However, when particles are close together, we experimentally observed that the attraction is enhanced and becomes far more complex. Indeed, the contact lines start to tilt and the superposition principle no longer holds. For these situations, we propose to additionally consider induced capillary dipoles to describe the menisci, therefore, providing an extra attraction between particles at short distances. This effect is enhanced when particles have different sizes such that binary self-assemblies may reveal unusual local ordering.