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 25.5: Vortrag
Donnerstag, 3. April 2014, 16:45–17:00, ZEU 114
Effects of soft confinement on the glass dynamics of glycerol, studied by deuteron NMR — •Michael Lannert1, Markus Rosenstihl1, Thomas Blochowicz2, Bernd Stühn2, and Michael Vogel1 — 1Institut für Festkörperphysik, Hochschulstraße 6, 64289 TU Darmstadt — 2Institut für Festkörperphysik, Hochschulstraße 8, 64289 TU Darmstadt
The dynamics of glycerol in a microemulsion with droplet diameters ranging from 2nm to 9nm were investigated by deuteron NMR in the temperature range 150K - 330K. While previous studies of liquid dynamics in confinement mostly used solid matrices, microemulsion droplets formed by AOT surfactants and toluol/m-xylol provide a soft confinement. Deuteron NMR longitudinal (T1) and transversal (T2) spin relaxation times, solid echo spectra, and two time correlation functions were recorded. High temperature dynamics are independent from droplet diameter and a Vogel-Fulcher-Tamann temperature dependence was observed. The line shape transition occurs at 240K for all studied droplet sizes, but is broader in confinement than in bulk, indicating a broadening of the distribution of correlation times. Time constants obtained from the measured correlation functions exhibit a weaker, Arrhenius temperature dependence. Detailed analysis suggests that the reorientation results from the rotational diffusion of whole droplets rather than individual molecules.