Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 11: POSTER Disperse Polymer Systems

CPP 11.13: Poster

Dienstag, 28. März 2006, 17:00–19:00, P3

Interface fluctuations, membrane elasticity and renormalization effects in microemulsions — •Olaf Holderer, Henrich Frielinghaus, Dmytro Byelov, Michael Monkenbusch, Jürgen Allgaier, and Dieter Richter — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, D-52425 Jülich

Neutron spin echo (NSE) spectroscopy is a well-suited method for studying the dynamic properties of microemulsions, consisting of oil, water and a surfactant. Here, the focus is set to bicontinuous microemulsions, having equal amounts of water and oil and varying surfactant concentration. The dynamic properties of the surfactant membrane are tuned by the addition of diblock copolymers or homopolymers. Structural parameters as the characteristic distance or correlation length in bicontinuous microemulsions are obtained by small angle neutron scattering (SANS). The renormalized bending modulus is obtained from the SANS experiments by matching the Gaussian random fields theory with a Ginzburg-Landau approach. NSE experiments are evaluated by numerically integrating S(q,t) from the Zilman-Granek theory, where the bending modulus is the only free fitting parameter. It is shown that the analysis of the dynamics gives a direct access to the ”bare” membrane bending moduls κ, which is compared to the renormalized one as obtained from SANS. The difference between the two ways of determining κ is the renormalization factor, as predicted by theory.