Dresden 2011 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Colloids and Complex Liquids I - Structure

CPP 25.1: Topical Talk

Wednesday, March 16, 2011, 10:30–11:00, ZEU 222

From elementary building blocks towards colloidal molecules — Claudia Simone Wagner and •Alexander Wittemann — Physikalische Chemie I, Universität Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany.

We report on the fabrication of clusters and binary colloidal composites made from organic and inorganic nanoparticles. Control over the assembly of nanoscale functional building units is of great significance to practical applications, but is also interesting from a more fundamental point of view of understanding the self-assembly of nanostructured materials. Joining together different spherical nanoparticles in a defined manner allows control over the shape, composition and surface roughness of the nanocomposites. If the constituents consist of different materials, the resulting heteroaggregates feature both compositional and interfacial anisotropy, offering unprecedented perspectives for rationally designed functional colloids, which are of fundamental importance to a broad range of applications including sensing, photonic, and electronic devices. The preparation of the clusters is based on the agglomeration of particles that are dispersed in an emulsion. The droplet size distribution in the emulsion is controlled by ultrasound. The particles adsorb on the surface of the emulsion droplets (Pickering effect) and coagulate in a well-defined way during the evaporation of the (dispersed) oil phase. Using this method one can produce clusters with colloidal dimensions (<400nm). We will report on the shapes and yield of these clusters using electron microscopy, scattering methods, and differential centrifugal sedimentation.