Dresden 2003 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 22: POSTER C
CPP 22.54: Poster
Donnerstag, 27. März 2003, 12:00–14:00, ZEU/250
Molecular Dynamics in Thin Films of Poly(dimethyl siloxane) (PDMS) of Various Preparation — •Lutz Hartmann1, Friedrich Kremer1, Pierril Pouret2, and Liliane Léger2 — 1University of Leipzig, Department of Physics, Linnéstrasse 5, D-04103 Leipzig, Germany — 2Laboratoire de Physique de la Matière Condensée, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05 France
Broadband dielectric spectroscopy (10−1 Hz-106 Hz) is used to study the molecular dynamics in thin grafted and spin cast films of PDMS with thicknesses d below and above the radius of gyration Rg in the temperature range between 120 K and 300 K. For grafted films it is found for d<Rg that the α-relaxation becomes faster by up to 2 orders of magnitude compared with the bulk. For d>Rg the dynamics is well comparable to that of the bulk. In spin cast films (d<40 nm) which are quenched in liquid nitrogen it is found that the α-relaxation splits up into two processes: one corresponds to the α-relaxation of the bulk, the second is again faster and is assigned to the α-relaxation in a surface layer of the PDMS film.