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Lecture F. Kremer


10 March 2010 FWN-Building 5111.0022, Nijenborgh 4, 9747 AG, Groningen
Speaker: Prof. Dr. F. Kremer
Affiliation: Leipzig University, Institute for Experimental Physics I, Leipzig, Germany
Title: Glassy dynamics and glass transition in thin polymer layers of PMMA deposited on different substrates
Date: Wed Mar 10, 2010
Start: 16.00
Location: FWN-Building 5111.0022
Host: Katja Loos
Telephone: +31 50 363 6867


Broadband Dielectric Spectroscopy (BDS) and spectroscopic Vis-Ellipsometry are combined to study glassy dynamics and the glass-transition of thin ( 10 nm) layers of  atactic poly(methylmethacrylate) (PMMA) prepared under identical conditions. In order to unravel  a possible effect of the underlying substrate, the interfacial interactions are systematically modified ranging from strong attractive interactions for covalently bonded PMMA brushes with high grafting densities and for native silicon oxide (SiOx) to weak  and strong repulsive interactions as realized by Au-coated and  silanized  SiOx–surfaces, respectively. Down to layer thicknesses 10 nm and independently from the  substrate used, both methods  deliver -within the experimental accuracy ( 1.0 K for BDS and 2 K for Ellipsometry) - the coinciding result that the glassy dynamics and the glass transition are not altered due to the geometrical confinement in the thin polymer layers. The results are discussed with respect to the highly controversial literature and explained on the basis of the nature of the  (dynamic) glass transition.

Last modified:22 October 2012 2.30 p.m.