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DY: Fachverband Dynamik und Statistische Physik

DY 46: Poster: Wetting, Nano- and Microfluidics

DY 46.10: Poster

Mittwoch, 9. März 2016, 18:15–21:00, Poster B2

Mechanical properties of highly porous super liquid-repellent surfaces — •Maxime Paven, Regina Fuchs, Doris Vollmer, Michael Kappl, and Hans-Jürgen Butt — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

The poor mechanical properties of highly porous materials restrict their utilization for a wide range of applications such as light weighted, insulating or super liquid-repellent coatings. Especially, the design principles of super liquid-repellent surfaces aim at maximizing roughness at the nano or micrometer scale, making them inherently mechanically weak. To find a balance between repellency and stability investigation of the surfaces*s mechanical properties is essential. Here, we use atomic force microscopy, colloidal probe, nanoindentation, and pencil scratching to investigate the mechanical properties of super liquid-repellent surfaces prepared by soot templating. We varied the reaction paramteres, i.e. the thickness of the template-stabilizing silica shell and the sintering temperature to investigate their influence on the wetting and mechanical properties. Sintering at 1000 °C increased the effective elastic modulus of the surface by more than an order of magnitude. Sintering at 1150 °C led to a smoothening of the porous silica network and the effective elastic modulus increased by up to five orders of magnitude. At the same time, however, for droplets of n-hexadecane the roll-off angle increased and the receding contact angle decreased. This emphasizes the delicate balance of stability and repellency for super liquid-repellent surfaces.