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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Poster Session I

CPP 24.15: Poster

Montag, 16. März 2020, 17:30–19:30, P3

Hierarchical assembly of non-spherical colloids by critical Casimir forces — •Timo Knippenberg, Jakob Steindl, Tian Li, and Clemens Bechinger — FB Physik, Universität Konstanz

Recent experiments demonstrated the use of critical Casimir forces in the context of spherical colloidal aggregation processes. Such forces arise due to the geometrical confinement of a critical mixture. Critical Casimir induced particle assembly essentially takes advantage of the fact, that the strength of such forces strongly depends on the temperature of the fluid and the adsorption preference of the colloidal particles. Here, we experimentally study the aggregation of semi-disk like particles under the influence of critical Casimir forces. We observe a preferential attraction between the flat facets of the particles which leads to their assembly into disk-shaped aggregates. At larger particle densities, the assembled disks form a hexagonal lattice. This hierarchical assembly process is explained by the strong curvature dependence of critical Casimir forces which leads to a strong alignment of non-spherical particles. This alignment strongly depends on the particle thickness which has been systematically varied in our experiments.