Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 35: Interfaces

CPP 35.3: Vortrag

Freitag, 29. Februar 2008, 11:15–11:30, C 130

Reversible activation of a polyelectrolyte brush — V. Papaefthimiou¹, J.-U. Günther², C. A. Helm², S. Förster³, G. H. Findenegg¹, and •R. Steitz⁴ — ¹Technische Universität Berlin — ²Ernst-Moritz-Arndt-Universität Greifswald — ³Universität Hamburg — ⁴Hahn-Meitner-Institut Berlin

Polyelectrolytes anchored on surfaces are important in various applications and are also a challenging topic for fundamental studies. In this work, a monolayer of the PEE114PSS83 [(poly(ethyl ethylene)114 poly(styrene sulfonic acid)83] diblock copolymer was transferred from the air/water interface to a deuterated polystyrene coated silicon (dPS/Si) surface, for evaluation as a tunable polyelectrolyte-brush containing system. The grafting density of the polymer film was controlled by changing the lateral pressure during the depositions. X-Ray Reflectivity and AFM measurements showed that a homogeneous layer of the block copolymer was formed, whose thickness (maximum 8 nm) increased with increasing grafting density. Neutron reflectivity studies against aqueous solutions revealed a hydrophobic PEE layer attached on the dPS/Si surface, and a carpet/brush polystyrene sulfonate (PSS) double layer in water. The effect of salt concentration on the brush nanostructure was investigated in aqueous solutions containing 0-1 M NaCl. It was found that the brush thickness decreases for salt concentrations above 0.1 M. In addition, reversible activation of the brush by changing the ionic strength of the subphase was demonstrated. These results confirm a potential use as a stimuli-responsive polymer for both fundamental studies and biological applications.