Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: INTERNAL SYMPOSIUM Scattering Experiments I
CPP 10.2: Talk
Tuesday, March 27, 2007, 10:00–10:15, H37
Glass-Forming Microemulsions and Liquid Dynamics in Soft Confinement — •Thomas Blochowicz1, Tinka Spehr1, Annika Fricke1, Martin Müller1, Bernhard Frick2, and Bernd Stühn1 — 1TU-Darmstadt, Germany — 2ILL, Grenoble, France
Recently glass forming liquids have been investigated subject to nanoscale geometrical confinements of various kinds, in order to access changes in the molecular dynamics when the confinement comes close to a characteristic lengthscale of cooperative motion. Most experiments were performed with glass formers confined in nanopores in case of which, however, actual finite size effects are superposed with pressure effects or interactions with the confining walls. A different situation can be found in microemulsions, where, droplets of a hydrophillic substance are stabilized by surfactant molecules in a hydrophobic environement. When the substances involved are chosen properly vitrification in a so-called "soft confinement" can be observed. In our particular case we study droplets of glycerol in a matrix of toluene and m-xylene stabilized by the ionic surfactant AOT. The temperature dependent structure of these systems is investigated by small-angle X-ray and neutron scattering, whereas for the dynamical behaviour quasielastic neutron scattering techniques are particularly useful due to their nanoscale spatial resolution. We present time-of-flight and backscattering measurements to access the dynamics of glycerol inside the emulsion droplets. As compared to bulk glycerol pronounced acceleration of the dynamics is observed whereas comparison of core and shell dynamics of the micelles yields almost identical behaviour.