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CPP: Chemische Physik und Polymerphysik

CPP 29: POSTER: Polymer physics

CPP 29.13: Poster

Dienstag, 8. März 2005, 16:30–18:30, Poster TU D

Formation of Large PEE-Domains in PEE₂₁₂−PEO₁₁₂ Diblock Copolymer Monolayers: Shift of the PEO-Desorption Transition — •Alexander Wesemann¹, Heiko Ahrens¹, Stephan Förster² und Christiane A. Helm¹ — ¹Angewandte Physik, Uni Greifswald, 17487 Greifwald — ²Physikalische Chemie, Uni Hamburg, 20146 Hamburg

PEE₂₁₂−PEO₁₁₂ diblock copolymer monolayers are studied at the air-water interface. At large molecular areas, with X-ray reflectivity PEE domains are observed, which are partly immersed into the water. The domain thickness increases on compression (28 to 40 Å). With off-specular X-ray reflectivity, an average domain radius of 750 Å is found, but there are also smaller domains. Due to the space constraints, most PEO-blocks form a brush beneath the PEE domains. Only a few PEO-blocks form a corona surrounding the domains and adsorb flatly onto the air-water interface. When the domain area fraction is 95%, the onset of the PEO desorption transition is found at the typical pressure of 9 mN/m. Yet, it occurs at 6 Ų/EO-monomer, 50 % of the value found usually. Apparently, the thickness of the PEE-domains is determined by the forces from the two interfaces, not by the PEO-block.