Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Colloids and Complex Fluids I (joint session BP/CPP/DY, organized by CPP)

CPP 24.4: Vortrag

Dienstag, 21. März 2017, 12:15–12:30, ZEU 255

From criticality to gelation in sticky spheres — David Richard^1,2, Thomas Speck¹, and •Cristopher Patrick Royall² — ¹Institut fur Physik, Johannes Gutenberg-Universitat, Mainz, Germany — ²HH Wills Physics Laboratory, Tyndall Avenue, Brisol, United Kingdom

Understanding the mechanism of dynamical arrest in liquids is a long standing challenge. Even for simple fluids, such as sticky spheres, an arrested gel can occur when the system is quenched sufficiently fast such that it cannot relax to equilibrium. For many systems the gelation arises at the gas-liquid phase boundary, forming a rigid but dilute network of bonded particles. In this study, we look at the critical behavior of sticky spheres combining confocal microscopy of colloid-polymer mixtures and Monte Carlo simulations of the square-well model. The mapping between those two is achieved via tracking colloids at the single-particle level and fitting pair distribution functions to the simulation data. We then compare the local structure via the topological cluster classification (TCC) method to identify locally favored structures (LFSs) along the critical path. We observe a very good agreement between experiments and simulations, where the growth of highly ordered structures are triggered even far away from the phase boundary. We discuss the link of those LFSs to the global percolating bond network.