Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Poster: Colloids and Complex Liquids

CPP 38.7: Poster

Mittwoch, 16. März 2011, 17:00–19:00, P2

Confocal Microscopy of Colloidal Aggregates under Shearing — •Jennifer Wenzl, Miao Wang, Marcel Roth, and Günter K. Auernhammer — Max-Plack Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz

Colloidal dispersions show a rich variety of phenomena and can therefore also act as model systems for granular matter. To infer the macroscopic behavior of granular material from interactions between single particles, detailed informations about the mechanical and structural properties are necessary. This is realized in particular with a large translational shear between parallel plates with simultaneous observation by a confocal microscope. Therewith we obtain three dimensional coordinates and trajectories of every particle in the imaged volume with high resolution. The shearing is done via a piezo-controlled cell, which enables the positioning of the shear plates with nanometer accuracy. The sample thickness is variable up to 160 µm on a micrometer scale and can be verified by confocal images. As a model system we use fluorescent core-shell silica particles in cis-decaline, as they show a weak aggregation. In this presentation we address the following questions. How do particles or aggregates deform under shear or compression? Do particles slide past each other or do they roll off under external shearing forces? How are forces transmitted in colloidal films?