Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: POSTERS Driven Soft Matter

CPP 20.3: Poster

Mittwoch, 27. Februar 2008, 16:00–18:30, Poster A

Growth instabilities of thin colloidal crystals prepared by convective self assembly. — José Marqués-Hueso and •Hans Joachim Schöpe — Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudinger Weg 7, 55099 Mainz, Deutschland

Colloidal particles have proved to be a suitable precursor to the formation of nanoscaled materials. More explicitly, crystalline arrays of colloidal particles (synthetic opals) show interesting optical properties with potential application as new types of optical gratings or optical filters. They further serve as a starting material of 3D photonic band gap materials. Their performance heavily relies on the material quality. One of the less studied defects in the case of colloidal crystals produced by vertical deposition is the modulation of the film thickness. Often a near regular periodic horizontal modulation in the thickness of the crystalline film can be observed. In our manuscript we present the first systematic measurements of the thickness modulation as a function of the volume fraction and the salt concentration of the suspension, of the tilting angle of the substrate, of the substrate material and of the pulling speed. We observe a variation of the growth velocity suggesting an inconstant behavior of the meniscus with a stick-slip motion like observed in simple droplet drying experiments. We suggest that a stick-slip motion of the meniscus during the evaporation process can explain the stripes morphology in the case of colloidal crystals.