Berlin 2018 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Poster Session III

CPP 33.22: Poster

Tuesday, March 13, 2018, 14:00–16:00, Poster C

Non-Equilibrium States of Sticky Colloidal Particles: Phase Separation and Dynamical Arrest — •Jan Hansen, Carolyn J. Moll, Florian Platten, and Stefan U. Egelhaaf — Condensed Matter Physics Laboratory, Heinrich Heine University, Düsseldorf, Germany

Soft materials can form amorphous solids, e.g. gels and glasses, which are relevant for such diverse fields as food engineering, pharmaceutical industry and materials science. To analyze the non-equilibrium states of colloidal particles interacting via short-ranged attractions, we use a perfectly monodisperse suspension of nearly spherical particles, namely globular proteins (lysozyme). The metastable gas-liquid binodal, the attractive glass line and the second virial coefficient B₂ for various solution conditions, i.e. salt concentrations, have been determined by optical microscopy, centrifugation experiments and light scattering. If the temperature axis of the binodals is expressed in terms of B₂, data obtained under various conditions fall onto a master curve, as suggested by the corresponding states law. For colloids with short-ranged attractions, gelation has previously been related to gas-liquid phase separation and a universal state diagram has been proposed if scaled by B₂. However, this is in contrast to our findings. Arrest lines for different salt concentrations overlap within experimental errors, whereas they do not overlap if the temperature axis is replaced by B₂. This indicates that the binodals are not sensitive to the details of the potential, but can be described by one integral parameter, i.e. B₂, whereas the arrest line appears governed by its attractive part.