Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: POSTER: Colloids and Nanoparticles

CPP 9.24: Poster

Monday, March 26, 2007, 16:00–18:00, Poster B

Ultra Small Angle X-Ray Scattering Investigation of Colloidal Crystals in Latex Films — •Rainer Gehrke and Stephan Volkher Roth — HASYLAB at DESY, Notkestr. 85, D-22603 Hamburg, Germany

Films obtained from coagulated dispersions of core-shell particles with a rigid thermoplastic core (polystyrene) and a soft elastomeric shell (polymethyl methacrylate-polyethylacrylate) form partially ordered structures which behave like photonic crystals [1]. This behaviour depends on the size of the particles. Samples with different particle size ranging from 200 nm to 300 nm have been characterized by means of Ultra Small Angle X-ray Scattering using synchrotron radiation at HASYLAB beamline BW4. In a layer near the film surface the particles form a regular fcc lattice with the (111) netplanes parallel to the surface. This ordering causes Bragg-like reflections in the scattering pattern. The material in-between the layers shows a scattering contribution caused by strong distance correlation without orientational ordering. From the scattering patterns obtained for different angles between the incoming X-ray beam and the film surface information about the degree of orientational ordering can be derived.

[1] T. Ruhl, G.P. Hellmann, Macromol. Chem. Phys. 202, 3502 (2001)