Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 1: Focus: Amphiphilic Systems I
CPP 1.1: Hauptvortrag
Montag, 23. März 2009, 10:45–11:15, ZEU 222
How to make mesoscopic single-crystals — •Stephan Förster1, Steffen Fischer1, Kathrin Zielske1, Peter Lindner2, Andreas Timmann3, and Stephan Roth3 — 1Institut für Physikalische Chemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany — 2Institut-Laue-Langevin, 6 rue Jules Horowitz, F- 38042 Grenoble Cedex 9, France — 3DESY (HASYLAB), Notkestrasse 85, 22603 Hamburg, Germany
Amphiphilic molecules can spontaneously assemble into micelles that can further assemble into cubic superlattices. The local order of these lattices is remarkably high on length scales of up to several hundred nanometers. However, on macroscopic scales the resulting materials contain many defects and have a multi-domain structure with random orientations so that samples are macroscopically isotropic.
For many applications it would be highly desirable to have well-defined macroscopic single crystals. This can be achieved by the application of external fields such as shear. Using in-situ SAXS- and SANS-experiments we have investigated how random multi-domain structures can be arranged into single crystals. Single crystals are prepared with unit cells in the range of 10 to 100 nm showing more than 100 Bragg-Peaks. We observe that the orientation pathways show many similarities to the plastic flow behaviour of metals. These pathways can also be used to prepare magnetic and semiconductor nanoparticle superlattices with very high quality and tunable unit cell dimensions.