Dresden 2014 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 38: Glasses and Glass Transition - Part II (joint session CPP/ DY/DF)

DY 38.3: 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.