Regensburg 2016 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 56: Wetting, Nano- and Microfluidics II (joint session CPP/DY)

DY 56.6: Talk

Thursday, March 10, 2016, 16:15–16:30, H42

Lateral Adhesion Forces at Solid-Liquid Interfaces — •Nan Gao, Florian Geyer, Sanghyuk Wooh, Dominik Pilat, Doris Vollmer, Hans-Jürgen Butt, and Rüdiger Berger — Max Planck Institute for Polymer Research, Mainz, Germany

Using a laser deflection system we investigate lateral adhesion forces at solid-liquid interfaces. Our set-up consists of a laser, a deflectable capillary, and a position sensitive detector (PSD). Substrates of TiO2 nanopillars with various spacing distances between the nanopillars are used to regulate surface wettabilities. Drops of liquid resting on the nanopillar substrates have different lateral adhesion forces due to the surface wettabilities. In order to measure the forces at the solid-liquid interfaces, the drops are moved laterally against the substrates using the deflectable capillary. A laser beam incident on the capillary is reflected to the PSD, which instantly generates electric signals according to the lateral adhesion forces. With assistance of optical imaging, we have been able to resolve the drop motion synchronised to the force measurement. Our measurements have demonstrated that the instantaneous lateral adhesion forces at the solid-liquid interfaces are determined by the front and rear contact angles as well as the contact width. The values are in good agreement with theoretical predictions.