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CPP: Chemische Physik und Polymerphysik

CPP 11: Colloids and Nanoparticles I

CPP 11.5: Talk

Monday, March 8, 2004, 15:00–15:15, H 39

ORDERING OF COLLOIDS USING A POLYMER SURFACE RELIEF GRATING — •B. Reinhold, Th. Geue, K. Morawetz, M. Saphiannikova, and J. Grenzer — University of Potsdam, Institute of Physics, Am Neuen Palais 10, 14469 Potsdam, Germany

Crystalline ordering of monodisperse colloidal spheres is of great interest for many applications. The preparation of large two dimensional colloidal domains often fails. The aim of this work was to initiate colloidal ordering on patterned substrate. Two methods were tested: The first method was the gravity sedimentation of colloids from dispersions and the second one was the LB-technique. For preparation we have chosen 420 nm sized spheres. The spheres were deposited on a polymer surface relief gratings (SRG) with a period between d=700 nm and d=900 nm. This grating was produced at room temperature by a holographic exposure of an amorphous polymer film containing azobenzene-side chains to visible light at a wavelength of about 488 nm.

The influence of the SRG on the ordering of spheres was investiagted by AFM and by grazing incidence x-ray small angle scattering (GISAX). The LB-technique was found less effective than the gravity-sedimentation method. Using the latter we could prepare samples with a nearly monolayer covering (AFM).The GISAX measurement confirms that we produced an almost homogeneous covering over a large sample area (2 mm X 2 mm). Almost no agglomeration of colloidal spheres was observed.