Wetting

Drops on an inclined plane

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:

Dynamic Wetting: Rüdiger Berger, Katrin- Amann-Winkel, Michael Kappl, Werner Steffen, Hans-Jürgen Butt

  1. Li, X., F. Bodziony, M. Yin, H. Marschall, R. Berger & H.-J. Butt: Kinetic drop friction. Nature Communications 2023, 14, 4571;  DOI: 10.1038/s41467-023-40289-8
  2. Kraft, L., J. Lucht, F. Berner, H. Hoeppe, T. Eklund, Y. Liu, M. Osterhoff, F. Westermeier, W. Roseker, T. Salditt, H.-J. Butt & K. Amann-Winkel: Dynamic contact angles on moving fibers measured by X-ray holography. Langmuir 2026, DOI: 10.1021/acs.langmuir.5c03213

AI to Analyse Drop Motion on Surfaces: Rüdiger Berger, Hans-Jürgen Butt

  1. Shumaly, S., F. Darvish, X. Li, O. Kukharenko, W. Steffen, Y.H. Guo, H.-J. Butt & R. Berger: Estimating sliding drop width via side-view features using recurrent neural networks. Scientific Reports 2024, 14, 12033, DOI: 10.1038/s41598-024-62194-w

Superhydrophobic Membranes for Water Treatment: Michael Kappl, Hans-Jürgen Butt

  1. Hou, Y., P. Shah, V. Constantoudis, E. Gogolides, M. Kappl & H.-J. Butt: A super liquid-repellent hierarchical porous membrane for efficient water desalination. Nature Communications 2023, 14, 6886, doi.org/10.1038/s41467-023-42204-7
  2. Sosa, M., I.K. Levi, H.-J. Butt & M. Kappl: Nanofilament-coated membranes with enhanced scaling and biofouling resistance for membrane distillation. ACS Applied Materials & Interfaces 2025, 17, 24588-24600, doi.org/10.1021/acsami.5c01758

Lubricant impregnated surfaces: Doris Vollmer, Hans-Jürgen Butt

  1. Naga, Abhinav, Michael Rennick, Lukas Hauer, William S. Y. Wong, Azadeh Sharifi -Aghili, Doris Vollmer, Halim Kusumaatmaja, “Direct visualization of viscous dissipation and wetting ridge geometry on lubricant-infused surfaces,“ Communications Physics 7:306 (2024). DOI: 10.1038/s42005-024-01795-3
  2. Hauer, Lukas, Zhuoyun Cai, Artem Skabeev, Doris Vollmer, Jonathan T. Pham, “Phase Separation in Wetting Ridges of Sliding Drops on Soft and Swollen Surfaces.” Phys. Rev. Lett., 130, 058205 (2023) DOI: 10.1103/PhysRevLett.130.058205

Easy-to-clean surfaces: Doris Vollmer

  1. Hegner, K.I., C. Hinduja, H.-J. Butt & D. Vollmer: Fluorine-free super-liquid-repellent surfaces: Pushing the limits of PDMS. Nano Letters 2023, 23, 3116-3121 DOI: 10.1021/acs.nanolett.2c03779
  2. Karakaya, Tarik, Said Albarqawi, Franziska Sabath, Azadeh Sharifi-Aghili, Emre Yavuz, Doris Vollmer, “Silica SolGel Coatings for Solar Panels: Drop Friction and Particle Adhesion” ACS Applied Materials & Interfaces. xxx (2026) DOI: 10.1021/acsami.5c22794

Drop Friction Force Instrument (DoFFI): Rüdiger Berger, Doris Vollmer, Hans-Jürgen Butt

  1. Gao, Nan, 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
  2. Hinduja, Chirag, Hans-Jürgen Butt, Rüdiger Berger, Slide electrification of drops at low velocities. Soft Matter 20 (15), S. 3349 - 3358 (2024). doi.org/10.1039/D4SM00019F
  3. Naga, Abhinav, Liam R. J. Scarratt, Chiara Neto, Periklis Papadopoulos, Doris Vollmer, “Drop Friction and Failure on Superhydrophobic and Slippery Surfaces” ACS Nano 19, 18902 (2025) DOI: 10.1021/acsnano.5c01142

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

  1. Laroche, Alexandre, 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: 10.1002/dro2.42
  2. Butt, H.-J., R. Berger, J. de Coninck & R. Tadmor: Drop friction. Nature Reviews Physics 2025, 7, 425–438. DOI: 10.1038/s42254-025-00841-5.
  3. Abhinav Naga, Liam R. J. Scarratt, Chiara Neto, Periklis Papadopoulos, Doris Vollmer, “Drop Friction and Failure on Superhydrophobic and Slippery Surfaces” ACS Nano 19, 18902 (2025) DOI: 10.1021/acsnano.5c01142

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

  1. Butt, Hans-Jürgen, Rüdiger Berger, Werner Steffen, Doris Vollmer, and Stefan A. L. Weber, "Adaptive Wetting-Adaptation in Wetting," Langmuir 34 (38), 11292-11304 (2018). DOI: 10.1021/acs.langmuir.8b01783
  2. Leibauer, Benjamin, Andres de los Santos Pereira, Diego Fernando Dorado Daza, Y. Wang, A.S. Hazrah, Ognen Pop-Georgievski, Hans-Jürgen Butt, Rüdiger Berger, Wetting of Surface Grafted Hydrophilic‐b‐Hydrophobic Block Copolymer Brushes. Advanced Functional Materials 35 (24), 2419443 (2025). DOI: 10.1002/adfm.202419443

Surface defects: Rüdiger Berger, Kaloian Koynov, Hans-Jürgen Butt

  1. Saal, Alexander, Benedikt B. Straub, Hans-Jürgen Butt, and Rüdiger Berger, "Pinning forces of sliding drops at defects," Europhys. Lett. 139 (4), 47001 (2022). DOI: 10.1209/0295-5075/ac7acf
  2. Xiang, Y., B. Straub, D. Cortes, H.-J. Butt & K. Koynov: When contact lines remember: Surface charge and the evolving interaction with defects. Droplet 2025, e70039, DOI: 10.1002/dro2.70039
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