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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Poster Session III

CPP 50.49: Poster

Dienstag, 17. März 2020, 14:00–16:00, P1C

Photo-Switchable Arylazopyrazole Phosphonic Acid SAMs on Al2O3 — •Christian Honnigfort and Björn Braunschweig — Institute of Physical Chemistry and Center for Soft Nanoscience SoN, University of Münster, Germany

The great interest in smart surfaces that can change their wetting behaviour on demand arises from their potential applications for self-cleaning surfaces, tunable lenses or microfluidics. Using light as a stimulus to change the wetting behaviour allows the spatio temporal confinement of the external stimulus. One way to exploit this is the decoration of surfaces with photo-responsive SAMs, e.g. phosphonic acids on Al2O3 surfaces. Here we used arylazopyrazole-functionalized phosphonic acids to induce the formation of photoresponsive SAMs on Al2O3. We show that the wetting behaviour can be changed reversibly with Δ Θ = 8 ^∘ . The quantitative description of these wetting dynamics is still challenging. While contact angle measurements can quantify the changes in the macroscopic wetting behaviour the application of inherently interface specific sum-frequency generation spectroscopy can provide information on the wetting dynamics on a molecular level for instance by observing C-H and O-H stretching vibrations under different light irradiations. It allows to quantify the degree of ordering within the monolayer and to gain information on the interfacial water structure.