Eur. Phys. J. Special Topics 189, 173–180 (2010) c  EDP Sciences, Springer-Verlag 2010 DOI: 10.1140/epjst/e2010-01320-2 T HE EUROPEAN P HYSICAL JOURNAL SPECIAL TOPICS Regular Article Glassy dynamics in nanometer thin layers of polystyrene E.U. Mapesa 1 , M. Erber 2 , M. Tress 1 , K.-J. Eichhorn 2 , A. Serghei 3 , B. Voit 2 , and F. Kremer 1, a 1 Institute for Experimental Physics I, Leipzig University, Leipzig, Germany 2 Leibniz Institute of Polymer Research, Dresden, Germany 3 University of Massachusets Amherst, Amherst MA, USA Received 01 September 2010 / Received in final form 14 September 2010 Published online 12 November 2010 Abstract. Broadband Dielectric Spectroscopy (BDS) and Ellipsome- try are combined to study the glassy dynamics of nanometric layers (≥ 5nm) of polystyrene. For the former, two types of sample arrange- ment are applied, that is, the conventional method where evaporated metal electrodes are used and a novel technique in which insulating silica nanostructures serve as spacers between highly conducting doped silicon counter electrodes. Within the limits of the experimental accuracy (±2K) both approaches, BDS and Ellipsometry, deliver the coinciding result that – compared to the bulk – the glassy dynamics is not shifted. Furthermore the dielectric measurements do not indicate any broadening of the relaxation time distribution function, independent of the sample geometry employed. 1 Introduction The nature of molecular dynamics in glass formers in geometrical confinement contin- ues to draw great scientific attention [1–30] and controversy. On the one hand is the view, best exemplified by de Gennes’ sliding model [1], that the chain loops coming in contact with the free interface exhibit enhanced mobility, and hence a reduction in the glass transition temperature of the system. On the other hand are findings [2–9] that strongly suggest that the length scale of geometrical confinement is limited to just about 3 polymer segments which translates to ∼ 0.5nm. For example, in a calorimetric study [2] using high heating (20 – 200 K/ms) and cooling (1–2 K/ms) rates, no appreciable thickness-dependence of the glass transition temperature was observed down to 3nm-thin films. However, a recent study [10] by ellipsometry re- ported tremendous reductions in T g values for PS films measured in different ambients and assigned this trend to “an intrinsic property of the confined material”. Similar conclusions were made in [11–19]. The aim of this work is to study the molecular dynamics of polystyrene in thin film confinement by two experimental techniques – BDS and Ellipsometry. Further, a e-mail: kremer@physik.uni-leipzig.de