Dresden 2020 – wissenschaftliches Programm
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SYDW 1.4: Hauptvortrag
Donnerstag, 19. März 2020, 16:45–17:15, HSZ 02
Liquid-liquid Dewetting: From Spinodal Breakup to Dewetting Morphologies and Rates — •Ralf Seemann1, Stefan Bommer1, Roghayeh Shiri1, Sebastian Jachalski2, Dirk Peschka2, and Barbara Wagner2 — 1Saarland University, D-66123 Saarbücken — 2Weierstrass Institute, D-10117 Berlin
The spinodal dewetting of liquid polystyrene (PS) from liquid polymethylmethacrylate (PMMA) is explored. Both polymers can be considered as Newtonian liquids with equal viscosities at dewetting temperatures. Provided the thickness of the liquid PMMA substrate is sufficiently large, the observed spinodal pattern is independent from PMMA film thickness. Because of the smaller interfacial tension of the buried interface compared to the PS-air interface and the large mobility, a very short spinodal wavelength develops with a larger amplitude of the buried interface than that of the free PS-air interface. The spinodal pattern of PMMA-PS and PS-air interface are anti-correlation and the wavelength is in quantitative agreement with theoretical predictions from thin film models. For a later dewetting stage, when dewetting rims have formed with sizes in the range of the PMMA film thickness, characteristic profiles of both the PMMA-PS and the PS-air interface develop, which depend on PMMA/PS thickness ratio. The dewetting rates, however, do not obey any well-defined scaling behavior and are close to linear. Based on the agreement of experimental results with theoretical predictions, we use the numerical simulations to predict local flow fields and the energy dissipation that otherwise would be inaccessible to experiments.