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Weiche Materie Poster: Do., 13:00–15:30 D-P331
Template-directed formation of ordered colloidal assemblies
Thomas Geue 1 , Patrick Huber 1 , Beate Reinhold 2 , Knut Morawetz 2 , Ullrich
Pietsch 3 , Marcus Textor 4
1 Laboratory for Neutron Scattering, ETH Zurich PSI, CH-5232 Villigen, Switzerland –
2 Institute of Physics, University of Potsdam, D-14415 Potsdam, Germany – 3 University
of Siegen, FB7 Solid State Physics, D-57068Siegen, Germany – 4 Materials Science
Dept., ETH Zurich, CH-8093 Zurich, Switzerland
The investigated ordered colloidal assemblies are three-dimensional periodic structures
formed from small polystyrene spheres suspended in solution. These assemblies attract
considerable attention when used as optical filters, switches and materials with photonic
band gaps.
Unluckily, a broad application of ordered colloidal assemblies is greatly restricted
by numerous difficulties in the formation of large area ordered crystalline assemblies
with uniform crystal orientation. We here present an approach using a holographically
manufactured template made from a photopolymer which is pre-structured. The
aim of these templates is to allow the growing of ordered colloidal assemblies by slow
sedimentation to direct the crystallization of colloids towards bulky crystals and to
allow a tailoring of the final lattice structure, orientation and size of the final colloidal
assemblies. The understanding of the sedimentation process is hereby of great importance.
Although there are optical [2,3] and confocal [4] microscopy well established as
is-situ investigation techniques, both methods are limited. On the one hand optical
microscopy is suitable investigating large particles in 2 dimensions while the confocal
microscopy requires fluorescence labeled specimen for the observation. The methods
are, moreover, more or less limited to describe surface phenomena only.
To fully monitor the crystallization process in 3 dimensions, X-ray reflectometry and
in-situ small angle X-ray scattering under grazing incidence as well as transmission geometry
were used to describe the phenomena taking place on the formation of colloidal
layering. These techniques are rarely used to investigated the formation of ordered
colloidal assemblies so far [5].
[1] Blaaderen, A. van, Ruel, R., Wiltzius, P. Nature, 385(1997) 321
[2] Dushkin, C. D. et al.. Colloid Polym. Sci., 277 (1999) 914
[3] Yin, Y. et al. J. Am. Chem. Soc., 123 (2001) 8718
[4] Hoogenboom, J. P., Vergeer, P., Blaaderen, A. van J. Chem. Phys., 11 (2003) 3371
[5] Narayanan, S., Wang, J., Lin, X.-M. Phys. Rev. Lett., 93 (2004) 135503