Hans-Jurgen Butt

Director for Experimental Physics of Interfaces, Max-Planck-Institute of Polymer Research in Mainz

"Contact Angle Hysteresis"

Abstract:

Wetting of a solid surface by a liquid is quantified by the advancing and receding contact angles. The advancing contact angle is always larger than the receding contact angle. The difference between the two is called contact angle hysteresis. Contact angle hysteresis influences our daily life. It, for example, prevents frictionless sliding of sessile drops. Sliding without resistance may be an advantage to keep windows, windscreens or glasses clean, but it would make many applications such as printing or coating extremely difficult. From the fundamental point of view, contact angle hysteresis prohibits us from measuring the equilibrium contact angle and thus impedes and easy link to theory via Young’s equation. In the presentation, effects leading to contact angle hysteresis will be discussed including some effects, which have only been realized recently, such as adaption. Contact angle hysteresis is directly linked to the mobility of sessile drops on surfaces. Therefore, sliding of drops on super liquid-repellent and lubricant infused surface will be analyzed.

Bio:

Hans-Jürgen Butt studied physics in Hamburg and Göttingen, Germany. Then he went to the Max-Planck-Institute of Biophysics in Frankfurt. After receiving his Ph.D. in 1989 he went as a post-doc to Santa Barbara, California, using the newly developed atomic force microscope. From 1990-95 he spent as a researcher back in Germany at the Max-Planck-Institute for Biophysics. In 1996 he became associate professor for physical chemistry at the University Mainz, three years later full professor at the University of Siegen. Two years later he joined the Max-Planck-Institute of Polymer Research in Mainz and became director for experimental physics of interfaces. The research focus is on physics of soft matter interfaces. Hans-Jürgen Butt is married and has three children.