Dresden 2017 – wissenschaftliches Programm
CPP 37.6: Vortrag
Mittwoch, 22. März 2017, 12:00–12:15, ZEU 255
Dynamics of Ethanol/Water mixtures studied by Dielectric spectroscopy — •Alexander Matt, Laura Vietze, and Bernd Stühn — Institut für Festkörperphysik, Technische Universität Darmstadt, D-64289, Germany
Water and alcohol mixtures have been an important part in studying the hydrogen bond network in water and the influence of guest molecules on the network. Since Ethanol is soluble in water at all concentrations it is well suited to act as a disturbance to the water network. In this work we use Ethanol, because of it is structural similarity to Poly(ethylene glycol), the only polyether soluble in water.
Ethanol and water mixtures form an eutectic system . We use Differential Scanning Calorimetry in order to observe melting processes as well as glass transition temperatures. This method allows us to determine the eutectic phase diagram. In order to study the dynamics above, below and at phase transition temperatures Broadband Dielectric Spectroscopy is used. Measuring in the high frequency range between 200 MHz and 50 GHz both pure water and pure alcohol dynamics can be investigated  as well as their interplay. Results show, that adding small amounts of alcohol to water slows down the water dynamics and that the interaction between the Ethanol molecules has an influence as well. The results of both measurement techniques are compared and used to understand the influence of temperature and Ethanol concentration on the mixture.  K. Takaizumi et. al., J. Solution Chem. 26, 927(1997)  R. Böhmer et. al., Physics Report 545, 125(2014)