Dresden 2003 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 22: POSTER C
CPP 22.61: Poster
Donnerstag, 27. März 2003, 12:00–14:00, ZEU/250
Investigation of ultrathin polystyrene films — •A. Götzendorfer, P. Müller-Buschbaum, and W. Petry — TU München Physik Department LS E13, James-Franck-Str.1, 85747 Garching
By varying the polymer concentration used for the spin-coating, the smallest achievable thickness of a polystyrene film on top of a Si(100) surfaces covered with its native oxide layer is searched. X-ray reflectivity measurements yield the film thickness of the films right after preparation. A linear relation between the polymer concentration and the resulting film thickness down to 1/5 Rg was observed. If the polymer concentration is decreased below a critical value the substrate is not covered homogeneously any more, but surface structures with typical length scales in the nanometer range are observed. The topography of these surfaces was imaged using atomic force microscopy. In addition grazing incidence small angle x-ray scattering measurements were carried out to obtain prominent in-plane length scales. It was noticed that for concentrations slightly larger than the critical concentration initially homogeneous films destabilize with age. This observation suggests a dramatic drop of the glass transition temperature of polystyrene to about room temperature in films of this thickness.