Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Colloids and Complex Liquids II

CPP 36.12: Vortrag

Mittwoch, 2. April 2014, 18:00–18:15, ZEU 114

Melting liquid and crystalline droplets in rod-sphere dispersions by shear flow — •Donald Guu¹, Minne Pavlik Lettinga^1,2, and Jan Karel George Dhont^1,3 — ¹Forschungszentrum Juelich, Institute of Complex Systems 3, Leo-Brandt-Str, 52425 Juelich, Germany — ²Department of Physics and Astronomy, Laboratory for Acoustics and Thermal Physics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium — ³Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf, Germany

We determined the phase behavior of an ideal rod*sphere mixture consisting of fd-virus, which are mono-disperse colloidal rods, and density matched mono-disperse polystyrene spheres, using a combination of diffuse wave spectroscopy and optical microscopy. Equilibrium phase diagrams were mapped out for various L/R ratios, where L is length of the rod and R is the sphere radius. At high L/R we observe droplets of a liquid phase of the spherical particles, while at lower L/R we obtained clusters which are crystalline. We studied the susceptibility of the droplets to shear flow, using a counter rotating cone-plate shear cell mounted on a fast confocal microscope. We observed a shear rate dependent melting of the structures, which is a function of the location in the equilibrium phase diagram of the sheared mixture. We show that the melting of liquid droplets takes place via another mechanism than for the crystalline clusters.