Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: Poster: Colloids and Complex Liquids

CPP 16.10: Poster

Tuesday, March 27, 2012, 18:15–20:45, Poster A

Dynamics in disconnected lamellar phases — •Stefan Wellert¹, Matthias Karg², Lukasz Szymanski³, and Cosima Stubenrauch³ — ¹TU Berlin, Str.d. 17.Juni 124, 10623 Berlin, Germany — ²University of Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany — ³University of Stuttgart, Pfaffenwaldring 35, 70569 Stuttgart, Germany

This contribution discusses the results of a neutron spin-echo (NSE) experiment addressing the dynamics in disconnected lamellar phases. (Pseudo)binary water-CiEj-type surfactant systems were investigated. The combination of a surfactant forming a continuous lamellar phase extending to low surfactant concentrations with a surfactant forming a lamellar phase only at high concentrations results in a disconnected lamellar phase. Regarding the stabilization of the lamellar phase in the dilute and the concentrated regime, respectively, it is known that the dilute lamellar phases, where the interlamellar distances are larger than the membrane thickness, are stabilized by membrane undulations. In the case of the concentrated lamellar phases, attractive van der Waals and repulsive steric forces are the stabilizing mechanisms. It was shown that the disconnection only takes place if the distance between two bilayers is similar to the thickness of the bilayers and it was argued that the disconnection is tuneable by the rigidity of the monolayer. In this combined small angle neutron scattering and NSE experiment we discuss the influence of the structure factor on the dynamics. By applying the theoretical approach of Zilman and Granek we determine the bending elasticity constants.