Berlin 2008 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 27: Micro and Nano Fluidics II: Slipping + soft objects in flow
CPP 27.3: Talk
Thursday, February 28, 2008, 14:30–14:45, C 264
Dewetting dynamics of thin polymer films on viscoelastic substrates — •Konstantina Kostourou1, Dirk Peschka2, Andreas Münch3, Barbara Wagner4, Stephan Herminghaus1, and Ralf Seemann1,5 — 1MPIDS, D-37073 Göttingen — 2Humboldt-University, D-12489 Berlin — 3University of Nottingham, Nottingham, NG7 2RD, UK — 4Weierstrass Institute, D-10117 Berlin — 5Saarland University, D-66041 Saarbrücken
The dewetting of thin liquid polystyrene (PS) films on viscoelastic substrates (PDMS and molten PMMA) is studied both experimentally and theoretically. The dewetting dynamics is found to be slower for smaller substrate elastic moduli. To explore how the dynamics is influenced by the viscoelasticity of the substrate we investigate the shape of the dewetting rim profile and the deformation of the underlying substrate. In case of PMMA substrates we remove the PS using a selective solvent and image the deformation directly on the frozen PMMA. The deformation of rubbery PDMS substrates is reversible. We therefore, lift off the PS from the substrate and image its deformation, which is frozen into the "bottom side" of the dewetting profiles. These techniques even allow to image the deformation of the substrate at the three phase contact line, which is pulled upwards. By quantifying the substrate deformation caused by PS droplets we can derive the elastic modulus of the PDMS substrates in agreement with bulk measurements. We find characteristic rim shapes and deformations of the substrate depending on the elastic modulus and the viscosity of the underlying substrate.