Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 28: Biological Systems

CPP 28.3: Talk

Friday, March 31, 2006, 11:00–11:15, ZEU Lich

Thin Casein films as prepared by spin-coating: Influence of film thickness and of pH — •P. Müller-Buschbaum¹, R. Gebhardt¹, E. Maurer¹, E. Bauer¹, R. Gehrke², and W. Doster¹ — ¹TU München, Physik-Department E13, James-Franck-Str. 1, D-85747 Garching, Germany — ²HASYLAB at DESY, Notkestr. 85, D-22603 Hamburg, Germany

Casein films are successfully prepared by spin-coating water based casein solution on base treated glass surfaces. The film structure is investigated in real space by optical microscopy and atomic force microscopy and in reciprocal space by grazing incidence small angle X-ray scattering (GISAXS). Due to the changed electrostatic repulsion, with increasing pH value the size of the casein micelles increases. Dynamic light scattering confirms good agreement of the micelle size in solution and building a bulk like casein film as determined with GISAXS. As long as homogeneous casein films are producible, with decreasing film thickness the micelle size is reduced. At the moderate pressure introduced by spin-coating the micelles rearrange in a more compact size.