Berlin 2001 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 19: Poster: New Methods, Thin Polymer Films, Monolayers
CPP 19.30: Poster
Thursday, April 5, 2001, 12:30–15:00, AT1
Contact angle and line tension of fluid nanostructures — •Thomas Becker, Frieder Mugele, and Stephan Herminghaus — Universitaet Ulm, Angewandte Physik, Albert Einstein Allee 11, D-89069 Ulm
We used atomic force microscopy to image nanoscopic liquid droplets. We measured the contact angle of hexaethyleneglycol on homogeneous substrates and on substrates with laterally structured wettability. We found deviations from the drop profile calculated by Joanny and de Gennes [1], which can be related to the three phase contact line tension τ. The line tension at the edge of the droplets was determined using two independent approaches. Both the modified Young equation and the effective interface potential yield a value of τ ≈ 10−10N [2], in agreement with theoretical predictions. We used model functions for the effective interface potential and optimized the parameters to minimize the deviation between the experimental profiles and the ones calculated from the model potentials. We found that the dominant molecular interactions in the present system are not van der Waals, but decay exponentially.
[1] J.F. Joanny, P.G. de Gennes, J. Chem. Phys. 81 (1984) 552 [2] T. Pompe, S. Herminghaus, Phys. Rev. Lett. 85 (2000) 1930