Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Polymer dynamics
CPP 21.13: Vortrag
Dienstag, 17. März 2015, 12:45–13:00, C 264
Glassy dynamics of Poly(2-Vinyl-Pyridine) brushes with varying grafting density — •Nils Neubauer1, René Winkler2, Martin Tress1, Petra Uhlmann2, Manfred Reiche3, and Friedrich Kremer1 — 1Molecular Physics, Institute of Experimental Physics I, Leipzig University, 04103 Leipzig, Germany — 2Nanostructured Materials, Leibniz-Institut für Polymerforschung Dresden e.V., 01069 Dresden, Germany — 3Experimental Department II, Max Planck Institute of Microstructure Physics, 06120 Halle (Saale), Germany
The molecular dynamics of poly(2-vinyl-pyridine)(P2VP) brushes is measured by Broadband Dielectric Spectroscopy (BDS) in a wide temperature (250 K – 440 K) and broad spectral (0.1 Hz – 1 MHz) range. This is realized using nanostructured highly conductive silicon electrodes being separated by silica spacers as small as 35 nm. A “grafting-to”-method is applied to prepare the P2VP-brushes with five different grafting densities (0.03 nm−2 – 0.12 nm−2), covering the “true-brush” regime with highly stretched coils and the mushroom-to-brush transition regime. The film thickness ranges between 1.8 to 7.1 (± 0.2) nm. Two relaxations are observed, an Arrhenius-like process being attributed to fluctuations in the poly(glycidyl methacrylate) (PGMA) linker used for the grafting reaction and the segmental dynamics (dynamic glass transition) of the P2VP brushes. The latter is characterized by a Vogel-Fulcher-Tammann dependence similar to bulk P2VP. The results can be comprehended considering the length scale on which the dynamic glass transition (≤ 1 nm) takes place.