Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 1: Supramolecular Aggregates
CPP 1.8: Vortrag
Montag, 26. März 2007, 11:45–12:00, H37
Grazing incident scattering for the investigation of crystallisation in micellar systems — •Max Wolff1, Andreas Magerl2, and Hartmut Zabel1 — 1Lehrstuhl für Festkörperphysik/EP IV, Ruhr-Universität Bochum, 44780 Bochum, Germany — 2Lehrstuhl für Kristallographie und Strukturphysik, Universität Erlangen-Nürnberg, 91058 Erlangen, Gemrany
Small angle scattering is known to provide information on the structural arrangement of block polymers. In highly dilute systems the conformation of the monomers is accessible from the radial intensity distribution. For higher concentrations micelles may appear and in the case of crystallisation usually an isotropic three dimensional powder is formed. From the resulting Debey-Scherrer rings it is difficult to determine the crystallographic structure. One way out is to introduce anisotropy by the application of shear. However, shear may affect the structure. Alternatively, by use of near surface small angle scattering, the ordering can be investigated close to the solid-liquid interface. We extracted detailed information on the crystallization of Pluronic (PEO-PPO-PEO) micelles solved in water in the vicinity of a solid substrate. We find the crystalline structure dependent on the chemical termination of the substrate as well as on the history of the sample. In addition we generally find large crystallites when entering into a crystalline phase from a liquid one that shrink in size further away from the phase boundary.
We acknowledge financial support by the BMBF grant no.: ADAM ZAE8BO and the DFG within the priority program SPP 1164.