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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Poster: Charged Soft Matter

CPP 22.4: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

Influence of the surface chemistry on the coexistence of flatly and brush-like physisorbed chains in poly(styrene-sulfonate) layers — •Stephan Block¹, Frank Lawrenz², and Christiane A. Helm² — ¹ZIK HIKE - Zentrum für Innovationskompetenz Humorale Immunreaktionen bei kardiovaskulären Erkrankungen, Fleischmannstr. 42 - 44, D-17487 Greifswald, Germany — ²Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17487 Greifswald, Germany

AFM with a colloidal probe as a tip is used to measure the surface forces and to image sodium poly(styrene sulfonate) (PSS) layers which are physisorbed to different surfaces in the presence of NaCl solutions with an ionic strength ranging between 0 M and 1 M NaCl. Colloidal probe tapping mode imaging shows that domains of PSS brushes coexist with flatly adsorbed PSS. Interestingly, this coexistence is observed on hydrophobic (e.g. HOPG, silanized silica) as well as hydrophilic surfaces (e.g. PEI on silicon, PAH on mica). The surface forces can be described as a superposition of electrostatic and steric forces, the former originating from the flatly adsorbed PSS and the latter from the brushes. This indicates that a heterogeneous layer structure seems to be a general phenomenon for physisorbed PSS layers and has to be regarded in studies concerning the adsorption behavior of polyelectrolytes.