Regensburg 2002 – wissenschaftliches Programm
SYPF 1.9: Hauptvortrag
Donnerstag, 14. März 2002, 14:30–15:00, H37
Structure formation and molecular dynamics in thin polymer films — •S. Herminghaus — Lehrstuhl für Angewandte Physik, Universität Ulm, Albert Einstein Ring 11, 89081 Ulm, Germany
The fundamental processes involved in structure formation upon dewetting are elucidated with polystyrene films as a model system. Nucleation (both heterogeneous and thermal) and spinodal dewetting are identified, as well as characteristic features of later stages of structure evolution. It is shown that viscoelastic effects may play a substantial role and qualitatively change the evolving patterns. The latter can thereby be exploited to derive the rheological properties of the dewetting film, thus providing a kind of nanoscale rheometer. We find that the viscosity of thin polystyrene films is strongly reduced with respect to the bulk, in accordance with corresponding findings concerning the glass transition temperature. A continuum model is proposed which might serve to explain this puzzling effect.