Dresden 2006 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 24: Poster presentation

DS 24.4: Poster

Dienstag, 28. März 2006, 15:00–17:30, P2

Domain shape dynamics and local viscosity in stratifying foam films — •Peter Heinig — MPI für Dynamik und Selbstorganisation, Bunsenstr. 10, 37073 Göttingen

For the development of microfluidic devices (the lab on a chip) the effect of an interface on bulk parameters, as viscosity, is an issue of great importance. Nevertheless experimental results on local viscosity are rare and partially contradictory. We studied the domain shape dynamics in a foam film composed of oppositely charged surfactant and polyelectrolyte. These films thin in stepwise fashion: circular domains of lower film thickness are formed, expand and coalesce until they cover the whole film surface. On the one hand we analyzed the shape relaxation of coalescing domains and retreating stripes, on the other hand the dynamics of domain growth. Both kinds of dynamic events represent independent ways for measuring local film viscosity. We found consistent results and an increase of film viscosity of almost two orders of magnitude compared to bulk. The effect can be explained by strong interactions between surfactant and polyelectrolyte.