Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Micro and Nano Fluidics I: Structured Substrates

CPP 17.5: Talk

Wednesday, March 28, 2007, 15:15–15:30, H37

Line tension effects for liquid droplets on circular surface domains — •Pedro Blecua, Jan Kierfeld, and Reinhard Lipowsky — Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany

We study the morphologies of single liquid droplets wetting a substrate in the presence of a line tension of the three phase contact line. On a homogeneous substrate the line tension leads to a discontinuous unbinding of the droplet if its volume is decreased below a critical value. For a droplet wetting a structured surface with a circular domain, a line tension contrast gives rise to discontinuous depinning transitions of the contact line at the domain boundary as a function of the droplet volume, which can be studied analytically for axisymmetric droplet shapes. We calculate the corresponding free energy bifurcation diagram. Numerical minimization of the droplet free energy shows that line tension contrasts can stabilize non-axisymmetric droplet shapes thus modifying the bifurcation diagram.