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DY: Fachverband Dynamik und Statistische Physik
DY 25: General Session to the Symposium: Interplay of Substrate Adaptivity and Wetting Dynamics from Soft Matter to Biology (joint session CPP/DY)
DY 25.1: Talk
Wednesday, September 7, 2022, 09:30–09:45, H39
Adaptive two capacitor model to describe slide electrification in moving water drops — •Pravash Bista1, Amy Z. Stetten1, William S.Y Wong1, Hans-Jürgen Butt1, and Stefan A.L. Weber1,2 — 1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany — 2Johannes Gutenberg University, Department of Physics, Staudingerweg 10, 55128 Mainz, Germany
Slide electrification is a contact-charge separation where neutral water drops slide over a neutral hydrophobic surface, accumulating and leaving behind a net charge. The accumulated drop charge for successive sliding drops decreases and eventually reaches a steady state. On hydrophobic and hydrophilic mixed surfaces, even a polarity flipping of drop charge depending on a drop rate was observed. Here, we describe this effect in terms of a voltage generated at the three-phase contact line. This voltage moves charges between capacitors, one formed by the drop combined with the solid surface and one on the solid-surface. By introducing an adaptation of the voltage upon water contact, we can model drop charge experiments on different surfaces, including more exotic ones with drop-rate-dependent charge polarity. Thus, the adaptive two capacitor model enables new insights into the molecular details of the charge separation mechanism.