Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Wetting, Micro and nanofluidics I

CPP 36.1: Topical Talk

Donnerstag, 29. März 2012, 15:00–15:30, C 264

From superhydrophobic to superamphiphobic coatings: How to tune wetting — •Doris Vollmer, Xu Deng, Lena Mammen, Periklis Papadopoulos, and Hans-Jürgen Butt — MPI for Polymer Research, Mainz, Germany

Many surfaces in nature are superhydrophobic, for example lotus leaves. Microscopic pockets of air are trapped beneath the water drops. This composite interface leads to an increase in the macroscopic contact angle and a reduced contact angle hysteresis [1]. However, the addition of an organic liquid such as alcohol or oil, decreases the interfacial tension sufficiently to induce homogeneous wetting. Drops, initially resting on air pockets, pass the transition to complete wetting (Wenzel state). Coatings that are simultaneously superhydrophobic and superoleophobic, i.e. superamphiphobic, are rare. For superamphiphobicity, surface roughness, low surface energy and topography are essential. We designed a transparent superamphiphobic using candle soot as a template [2]. Soot consists of a fractal-like assembly of nano-spheres. Convex small-scale roughness can provide a sufficient energy barrier against wetting, even if the Wenzel state is the thermodynamic equilibrium state. Finally, we discuss the coating resistance against drop impact.

[1] D'Acunzi, L. Mammen, M. Singh, X. Deng, M. Roth, G.K. Auernhammer, H.-J. Butt, and D. Vollmer, Faraday Discus. 146 (2010), 35.

[2] X. Deng, L. Mammen, H.-J. Butt, and D. Vollmer; Transformation of black candle soot into a transparent robust superamphiphobic coating, Science in press.