Dresden 2006 – wissenschaftliches Programm
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SYNP: Nonequilibrium Phenomena in Soft Condensed Matter
SYNP 1: Noneqilibrium Phenomena in Soft Condensed Matter
SYNP 1.1: Hauptvortrag
Dienstag, 28. März 2006, 09:30–10:00, HSZ 04
Rising plumes, layering transitions and squeeze-out patterns in soap films — •Steffen Berg1,2 and Sandra M. Troian1 — 1Dept. of Chemical Eng., Princeton University, Princeton, NJ, USA — 2Shell International Exploration and Production B.V., Kesslerpark 1, 2288 GS Rijswijk (ZH), The Netherlands
In free-standing microscale soap films containing surfactant micelles an instability near the film borders creates moving patterns that resemble rising ”lava plumes” [1]. Our recent studies indicate that these moving patterns contribute to the drainage dynamics as a rate-determining mechanism impacting on the scaling exponent of the film thickness as function of time h(t) [2]. Aqueous nanofilms comprised of micelle-polymer complexes under confinement reveal two novel instabilities linked to the degree of association. The first, triggered by the final thinning transition, generates constant growth fractal patterns whose dimension correlates with the bulk viscosity. A mapping to the Saffman-Taylor instability [3] reveals the critical viscosity contrast for phase segregation. A secondary instability for high polymer molecular weights causes the fractal phase to self-assemble into a macroscopic array of flattened nanodroplets with distinct 4-fold packing symmetry.
[1] K. J. Mysels, K. Shinoda and S. Frankel Soap Films, Studies of Their Thinning; Pergamon Press: New York, 1959.
[2] S. Berg, E. A. Adelizzi and S. M. Troian, Langmuir 21, 3867 (2005).
[3] P. G. Saffman and G. I. Taylor, Proc. Roy. Soc. London, Ser. A 245, 312 (1958).