Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Micro and Nano Fluidics I: Structured Substrates
CPP 17.3: Vortrag
Mittwoch, 28. März 2007, 14:45–15:00, H37
Manipulation of wetting morphologies in triangular grooves — •Krishnacharya Khare1, Martin Brinkmann1, Bruce M. Law2, Stephan Herminghaus1, and Ralf Seemann1 — 1Max Planck Institute for Dynamics and Self-Organization, D-37073 Göttingen — 2Department of Physics, Kansas State University, USA
Wetting behavior of liquids in triangular grooves is studied experimentally and theoretically. For contact angles smaller than 90 degree minus half the opening angle of the groove, the liquid forms filaments with negative mean curvature extended along the entire length of the groove. For larger contact angles, liquid either forms elongated filaments of finite length and positive mean curvature or drop-like morphologies. Electrowetting is used to vary the contact angle and to switch between these morphologies. In this way, liquid filaments can be pulled out of a large feeding drop forming elongated filaments in prefabricated grooves. When being quenched from the filling to the non-filling regime the liquid filaments undergo dynamic instability and break up into isolated droplets with a preferred distance. This preferred droplet distance compares favorably with a straight forward theoretical model assuming the instability to be driven by the local variation of the Laplace pressure with filament width. This instability may be viewed as a generalization of the Rayleigh-Plateau instability and resembles the spinodal instability of thin films.