Regensburg 2022 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 7: Wetting, Fluidics and Liquids at Interfaces and Surfaces

CPP 7.4: Vortrag

Montag, 5. September 2022, 11:45–12:00, H39

How often a Drops Sticks and Slips at a Wetting Transition — Chirag Hinduja¹, Alexandre Laroche^1,2, Sajjad Shumaly¹, Yujiao Wang^3,4, Doris Vollmer¹, Hans-Jürgen Butt¹, and •Rüdiger Berger¹ — ¹Max Planck Institute for Polymer Research, 55128 Mainz, Germany — ²University of Zurich, 8057 Zurich, Switzerland — ³Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China — ⁴University of Chinese Academy of Sciences, Beijing 100049, China

We will discuss forces of sliding drops at a sharp wetting transitions featuring no topographic variation. Such surfaces with different wetting properties were made from chemical vapor deposition of trichlorootcylsilane (OTS) and tri-chloro(perfluoro) octylsilane (PFOCTS). We observed that drops sliding from an area of low to high contact angle hysteresis exhibit two force maxima. The drop motion is characterized by pinning of the advancing and receding contact lines, respectively. Accordingly, the motion of the drop follows two stick-slip processes. Drops sliding from an area of high to low contact angle hysteresis exhibit a single local force maximum, a single stick process, but two slip processes.

Sliding forces of drops were measured by a novel tool named scanning Drop Adhesion Force Instrument (sDAFI) which we use to image, locate and characterize wetting properties of cm-large areas with a resolution down to the micrometer-scale.