Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Wetting, Micro and nanofluidics II
CPP 39.2: Vortrag
Freitag, 30. März 2012, 09:45–10:00, C 243
Impact of polystyrene chain length on the instability of a dewetting liquid front — •Sabrina Haefner1, Matthias Lessel1, Ludovic Marquant1, Oliver Bäumchen2, and Karin Jacobs1 — 1Saarland University, Experimental Physics, D-66041 Saarbrücken, Germany — 2McMasters University, Dept. of Physics & Astronomy, Hamilton, ON, Canada
A water cylinder in air is breaking up in droplets, seeking to minimize its surface energy. This phenomenon is known as Rayleigh-Plateau-instability. A liquid front of a dewetting liquid film is a similar geometry and hence also subject to the Rayleigh-Plateau-instability. For polymer melts Marquant et al. have shown the influence on the instability by the type of solid/liquid boundary condition ('slip' or 'no slip'). Bäumchen et al. have shown in a recent study, that in thin polystyrene (PS) films slippage can be induced by only exceeding a certain chain length of the polymer. Combining both things, we are interested in the impact of chain-length-induced slippage on the Rayleigh-Plateau-instability of a dewetting front. As substrates an amorphous fluoropolymer (AF1600) layer was prepared on smooth Si wafers entailing nearly no-slip conditions for PS chain length under 35 kg/mol. With increasing slip length the instability sets in at lower dewetted distances. At a certain molecular weight (higher slippage) this is reversed and the instability then develops only after larger dewetted distances. This effect can be explained by the rim profile of the liquid front, which is strongly influenced by the type of boundary condition.