Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 60: Pattern Formation (Joint Session with DY)

BP 60.6: Vortrag

Donnerstag, 10. März 2016, 11:15–11:30, H46

Self-assembly in colloidal systems with tunable particle interactions — •Hauke Carstensen, Vassilios Kapaklis, and Max Wolff — Dept of Physics & Astronomy, Box 516, SE-751 20 Uppsala, Sweden

We present a system that allows tunable magnetic self-assembly of microbeads. Two types of beads, magnetic and non-magnetic ones, are dispersed in a ferrofluid (FF), which alters their effective magnetic behaviour. By changing the FF concentration, the interactions between the beads can be tuned. The particles are confined in two dimensions. Depending on the interaction and the particle composition, lattices like square or hexagonal are assembled. Additionally, in less dense conditions metastable structures like branching chains are observed. The samples are analysed by transmission optical microscopy and images are taken in a scanning mode. Sets of images can be stitched together to create large scale maps of each sample. The particle positions are extracted by image analysis. Phases are detected via characteristic angles and lattice constants. A phase diagram is created by combining the observed phases with the particle interactions and the sample compositions. This can be applied to the fundamental understanding of colloidal crystal formation and chain formation in magnetorheological fluids.