Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 30: Poster: Focus: Wetting on smooth and rough surfaces: From spreading to superhydrophobicity
CPP 30.11: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
Influence of subsurface interactions on the dynamic contact angle of liquids on mixed organic monolayers — David Polster1 and •Harald Graaf2 — 1Department of Physics, University of Konstanz, D-78464 Konstanz, Germany — 2nanoMA (Center for nanostructured Materials and Analytics), Chemnitz University of Technology, D-09107 Chemnitz, Germany
The functionalisation of surfaces by organic monolayers is a well known way to influence the surface properties e.g. the adhesion forces. Mixed monolayers consisting of similar molecules with two or more various headgroups can tune the obtained surface properties like the hydrophobicity. In the present study silicon surfaces are modified by alkene molecules. By using two different alkenes mixed monolayers of various ratios the hydrophilizity of the surface can be tuned. A water ring formation around single and double ester groups increase the effective hydrophilic area, which leads to a deviation from the expected change in static contact angle measurements.[1] In a recent study we found on such mixed monolayers a hysteresis of the dynamic contact angle of different liquids.[2] Several approaches are discussed in literatur the hysteresis (and also differences in wetting and dewetting energies) partially to long range interactions between the liquid and the underlying silicon, which is very reasonable as the monolayer thickness is only about two nanometers.
[1] Polster et al. Langmuir 26 (2010) 8301, [2] Polster et al. Appl.Surf.Sci. DOI 10.1016/j.apsusc.2012.10.128