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Siegel der Universität
Department für Chemie - Arbeitsgruppe Prof. Strey

Polymerdecorated surfactant-bilayer

Verena Posselt, Oktober 2009:

Self-assembly of amphiphilic molecules is influenced by polymeric guest-molecules in microemulsions (efficiency-boosting-effect) as well as in complex biological lipid?membranes. In this work the influence of polymers on binary systems containing water and a non?ionic surfactant as model systems for biological membranes is systematically investigated. Adding small amounts of stickerpolymers of the type n-dodecylpolyoxyethylene (C12En) to aqueous systems of n-alkylpolyglycolether (CiEj) both the diluted lamellar Lα and L3-phase can be expanded to ultra-low concentrations or even induced in simple surfactant-systems. Small angle neutron (SANS), small angle X-ray (SAXS) and light back scattering measurements were performed. The scattering data was analyzed using predefined structure models and the model-free generalized indirect Fourier Transformation (GIFT) and yielded the bilayer thickness, the Caillè-parameter and the bilayer repeat distance. By adding polymer the bilayer repeat distance decreases, which can be explained by the decreasing undulations as a result of the increasing bending rigidity κ. Quantitative analysis indicates an increase of the bending rigidity caused by decoration of the bilayer with the polymer. Furthermore it could be shown that the effect of the polymer on the bending rigidity depends not only on the surface coverage but also on the size of the hydrophilic moiety of the polymer. Neutron?spin?echo (NSE)?measurements confirm that the membrane dynamics slow due to the influence of the polymer. Analyzing the dynamic scattering function the bending rigidity can also be obtained. The values agree with the bending rigidity determined from the scattering experiments.


AIF-Projekt 14832: Produktgewinnung und Katalysatorrückführung bei Reaktionsführung in Mizellaren Systemen und Mikroemulsionen: Nutzung der Mischungslücke der Systeme für extraktive Trennoperationen.