Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 19: Dynamics I
CPP 19.3: Vortrag
Dienstag, 8. März 2005, 10:15–10:30, TU C230
Pattern formation in thin polystyrene films — •Anatoli Serghei1, Heiko Huth2, Christoph Schick2, and Friedrich Kremer1 — 1University of Leipzig, Institute for experimental physics I, Linnestr. 5, 04103 Leipzig — 2Universität Rostock, Fachbereich Physik, Universitätsplatz 3, 18051 Rostock
Thin polystyrene films (ranging from 30 nm to 300 nm, prepared in a sandwich geometry between two Aluminum electrodes) exhibit in ambient air at temperatures above the glass transition (i.e. 180 C) a pattern formation, while in a pure nitrogen atmosphere and in vacuum their geometry remains unchanged. This finding indicates an enhanced sample mobility in ambient air in comparison to that in a nitrogen atmosphere or in vacuum. As proven by Broadband Dielectric Spectroscopy, capacitive dilatometry and temperature modulated calorimetry, this effect is caused by an increase in time of the average relaxation rate of the dynamic glass transition and a corresponding reduction of the glass transition temperature Tg. Measurements by Infrared Spectroscopy reveal that the origin of this phenomenon is a decrease of the average molecular weight as a consequence of oxygen-induced chain scissions in ambient air.
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