Dresden 2014 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 25: Glasses and Glass Transition II (Joint Session with CPP and DY)
DF 25.3: Vortrag
Donnerstag, 3. April 2014, 16:00–16:15, ZEU 114
Glassy Dynamics of Collapsed Isolated Polymer Chains — •Martin Tress1, Emmanuel Urandu Mapesa1, Manfred Reiche2, and Friedrich Kremer1 — 1Universität Leipzig — 2MPI für Mikrostrukturphysik, Halle
While structure and conformation of condensed, isolated low molecular weight and polymeric molecules are well explored, knowledge concerning their dynamics, as measured in a broad spectral range and at widely varying temperatures is sparse. To overcome this, Broadband Dielectric Spectroscopy is combined with nano-structured electrodes having 35 nm separation and the dynamics of collopsed isolated poly(2-vinylpyridine) (P2VP) globules is measured. The collapsed globule conformation is revealed by Atomic Force Microscopy scans of the identical samples with an average globule volume corresponding to the estimate for a single chain (using the molecular weight and bulk density). Hence, for the first time the dynamic glass transition of condensed isolated polymer chains is directly measured and found to be bulk-like; only segments close (< 0.5 nm) to the substrate are weakly slowed down. The observation of bulk-like dynamics is in full accord with the length scale on which the dynamic glass transition is to be expected. In contrast, the emersion of new, slower relaxation modes is attributed to attractive interactions of the P2VP segments with the supporting silica surface, a finding which is corroborated by complementary infrared experiments. Our approach paves the way for numerous experiments on the dynamics of isolated molecules.