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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 10: Wetting, Fluidics and Liquids at Interfaces and Surfaces I (joint session CPP/DY)

CPP 10.4: Vortrag

Montag, 17. März 2025, 17:00–17:15, H34

Removing particles from hydrophobic surfaces by single water drops — •Franziska Sabath, Stefanie Kirschner, and Doris Vollmer — Max Planck Institute for Polymer Research, 55128 Mainz, Germany

The accumulation of dust on surfaces is a well-known phenomenon in everyday life, for example on windows and solar panels. Both manual cleaning and self-cleaning of hydrophobic surfaces with water can restore the properties of soiled surfaces. However, it is not yet understood how particles are removed by a water drop and which forces play a role for successfully removing the particles. We investigated the removal of two or more particles from hydrophobic coatings by a single water drop. For this purpose, we used a confocal microscope with a sliding drop setup. This implies that the particles was moved at constant velocity while the drop is hold in position by a blade. The sliding drop and the way in which the particles are picked up and pulled along by the water drop can be imaged. From the deflection of the blade, we can determine the force required to pull the particles along with the drop. Here, we focus on the removal of spherical model particles and the impact of drop volume, particles size and particle velocity on the particle removal. At low velocities the particles remain attached to the drop. With increasing velocity we observe that the particle detachment becomes more likely. In case of particle detachment, we observe a correlative effect: after the second particle has reached the rear side of the drop, both particles can detach together.