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CPP: Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes
CPP 18.29: Poster
Wednesday, April 4, 2001, 12:30–15:00, AT1
PEE-PEO Diblockcopolymer Monolayers at the Water Surface — •Alexander Wesemann1, Heiko Ahrens1, Roland Steitz2, Irina Estrella-Lopez2, Stephan Förster3, and Christiane A. Helm1 — 1Institut für Angewandte Physik, EMAU-Greifswald — 2Hahn-Meitner-Institut Berlin — 3Institus für Physikalische Chemie, Universität Hamburg
The phase behavior of amphiphilic blockcopolymer monolayers consisting of hydrophilic poly(ethyleneoxide) (PEO) and hydrophobic poly(ethylethylene) (PEE) is investigated on the water surface. The monolayers are characterized with isotherms, X-ray- and neutron reflection — the latter methods are based on complementary contrast mechanisms. Thermodynmaically, a first order phase transition is found, which can be explained by the subtle interplay between the PEE and PEO blocks. X-ray reflection at low anchoring densities indicates PEE surface micelles, at high anchoring densities a nm thick melt with a thickness proportional to the anchoring density is observed. Neutron reflection shows a rich phase behavior of the PEO block: a desorption transition from a flat configuration to a mushroom and at higher lateral densities to a brush phase is found. The effect of the respective chain lengths varied between 100 and 800 monomer units as well as dynamic effects are discussed.