Wetting

Wetting is a common phenomenon and important for applications such as printing, coating, painting, Condensation & evaporation in heat transfer, powder dispersion, particle adhesion, drop impact and imbibition. Still our understanding of wetting is quite poor. Many processes, such as the sliding of a drop down a tilted plane, cannot be predicted quantitatively. The aim of our research is:

to predict static and dynamic wetting and to provide quantitative understanding
to control wetting of surfaces. We aim for surfaces with desired wetting properties based on preparation methods which are simple, environmentally friendly (e.g. fluorine free), and lead to chemically and mechanically robust surfaces.
to characterize solid surfaces by measuring wetting properties.

In particular, we work on the following topics:

Super liquid-repellent surfaces: Werner Steffen, Hans-Jürgen Butt

William S. Y. Wong, Abhinav Naga, Lukas Hauer, Philipp Baumli, Hoimar Bauer, Katharina I. Hegner, Maria D'Acunzi, Anke Kaltbeitzel, Hans-Jürgen Butt, and Doris Vollmer, "Super liquid repellent surfaces for anti-foaming and froth management," Nature Communications 12 (1), 5358 (2021). doi.org/10.1038/s41467-021-25556-w

Lubricant impregnated surfaces: Doris Vollmer, Hans-Jürgen Butt

Philipp Baumli, Maria D'Acunzi, Katharina I. Hegner, Abhinav Naga, William S. Y. Wong, Hans-Jürgen Butt, and Doris Vollmer, "The challenge of lubricant-replenishment on lubricant-impregnated surfaces," Advances in Colloid and Interface Science 287, 102329 (2021). doi.org/10.1016/j.cis.2020.102329

Jie Liu, Yuling Sun, Xiaoteng Zhou, Xiaomei Li, Michael Kappl, Werner Steffen, and Hans-Jürgen Butt, "One-Step Synthesis of a Durable and Liquid-Repellent Poly(dimethylsiloxane) Coating," Advanced Materials , 2100237 (2021). doi.org/10.1002/adma.202100237

Surface with low sliding angle: Hans-Jürgen Butt

Drop adhesion forces instrument: Rüdiger Berger, Doris Vollmer, Hans-Jürgen Butt

Nan Gao, Florian Geyer, Dominik W. Pilat, Sanghyuk Wooh, Doris Vollmer, Hans-Jürgen Butt, and Rüdiger Berger, "How drops start sliding over solid surfaces," Nature Physics 14 (2), 191-196 (2018). doi.org/10.1038/nphys4305

Chirag Hinduja, Alexandre Laroche, Sajiad Shumaly, Y. Wang, Doris Vollmer, Hans-Jürgen Butt & Rüdiger Berger, “Scanning drop adhesion force microscopy”, Langmuir 38, 14635−14643 (2022) doi.org/10.1021/acs.langmuir.2c02046

Contact angle hysteresis: Hans-Jürgen Butt, Rüdiger Berger, Michael Kappl, Werner Steffen

Alexandre Laroche, Abhinav Naga, Chirag Hinduja, Azadeh A. Sharifi, Alexander Saal, H. Kim, Nan Gao, Sanghyuk Wooh, Hans-Jürgen Butt, Rüdiger Berger & Doris Vollmer, ”Tuning drop friction”, Droplets, e42 (2023) doi.org/10.1002/dro2.42

Hans-Jürgen Butt, Jie Liu, Kaloian Koynov, Benedikt Straub, Chirag Hinduja, Ilia Roismann, Rüdiger Berger, Xiaomei Li, Doris Vollmer, Werner Steffen, and Michael Kappl, "Contact angle hysteresis," Current Opinion in Colloid & Interface Science 59, 101574 (2022). doi.org/10.1016/j.cocis.2022.101574

Adaptive wetting: Hans-Jürgen Butt, Rüdiger Berger, Doris Vollmer

Hans-Jürgen Butt, Rüdiger Berger, Werner Steffen, Doris Vollmer, and Stefan A. L. Weber, "Adaptive Wetting-Adaptation in Wetting," Langmuir 34 (38), 11292-11304 (2018). doi.org/10.1021/acs.langmuir.8b01783

Xiaomei Li, K. Auepattana-Aumrung, Hans-Jürgen Butt, Daniel Crespy & Rüdiger Berger, “Fast-release kinetics of pH-responsive polymers detected by dynamic contact angles”, J. Chem. Phys. 2023, submitted 18.1.2023

Effect of surface defects: Rüdiger Berger, Kaloian Koynov, Hans-Jürgen Butt

Alexander Saal, Benedikt B. Straub, Hans-Jürgen Butt, and Rüdiger Berger, "Pinning forces of sliding drops at defects," Europhys. Lett. 139 (4), 47001 (2022). doi.org/10.1209/0295-5075/ac7acf