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DY: Fachverband Dynamik und Statistische Physik
DY 13: Wetting, Fluidics and Liquids at Interfaces and Surfaces (joint session CPP/DY)
DY 13.10: Vortrag
Dienstag, 2. April 2019, 12:15–12:30, H13
Direct observation of gas meniscus formation on a superhydrophobic surface — •Doris Vollmer1, Mimmi Eriksson2, Agne Swerin2, Hannu Teisala1, Michael Kappl1, and Hans-Jürgen Butt1 — 1MPI for Polymer Research, Mainz, Germany — 2RISE Research Institutes of Sweden, Stockholm, Sweden
The formation of a bridging gas meniscus via cavitation or nanobubbles is considered the most likely origin of the long-range attractive forces measured between hydrophobic surfaces in aqueous solution. On a superhydrophobic surface a thin air layer is present and influences the interaction. Here, we report time and space resolved imaging of the formation and growth of a gas meniscus during force measurements between a superhydrophobic surface and a hydrophobic microsphere immersed in water. This is achieved by combining laser scanning confocal microscopy and colloidal probe force microscopy. The configuration allows determination of the volume and shape of the meniscus, together with direct calculation of the Young-Laplace capillary pressure. The long-range attractive interactions acting on separation are due to meniscus formation and volume growth as air is pulled from the surface layer.