Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.91: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

Lamellar phase of polyectrolyte chains adsorbed onto oppositely charged lipid monolayers — •Jens-Uwe Günther, Heiko Ahrens, Olaf Soltwedel, and Christiane A. Helm — Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17487 Greifswald, Germany

At the air-water interface, the polyanion PSS (Poly styrene sulfonate) is adsorbed onto positively charged TAP or DODAB monolayers (1,2-Dipalmitoyl-3-Trimethylammonium-Propane, dioctadecyammonium bromide), respectively. By compressing the lipid monolayer, the surface charge is varied. In-plane order is investigated with grazing incidence X-ray diffraction, the lipid phases with fluorescence microscopy. When the alkyl chains of DODAB and TAB are ordered, an additional superstructure peak of the aligned PSS chains is observed provided the PSS concentration is 1 mM or less. For DODAB in the fluid phase, PSS in a lamellar phase with a much wider spacing is found. On decrease of the PSS concentration, the spacing of the chains is larger, since the monolayer charge is no longer compensated. The influence of the kind of counterion as well as the polymer length is less pronounced. If the PSS concentration or the ion concentration is larger than 1 mM no chain ordering is observed, suggesting that both large intra- and interchain electrostatic interactions are necessary to obtain a lamellar polyelectrolyte phase.