Simulation study of nonergodicity transitions: Gelation in colloidal systems with short-range attractions

Antonio M. Puertas, Matthias Fuchs, and Michael E. Cates
Phys. Rev. E 67, 031406 – Published 26 March 2003
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Abstract

Computer simulations were used to study the gel transition occurring in colloidal systems with short-range attractions. A colloid-polymer mixture was modeled and the results were compared with mode coupling theory (MCT) expectations and with the results for other systems (hard-spheres system and Lennard-Jones system). The self-intermediate scattering function and the mean squared displacement were used as the main dynamical quantities. Two different colloid packing fractions have been studied. For the lower packing fraction, α-scaling holds and the wave-vector analysis of the correlation function shows that gelation is a regular nonergodicity transition within MCT. The leading mechanism for the novel nonergodicity transition is identified as the bond formation caused by the short-range attraction. The time scale and diffusion coefficient also show qualitatively the expected behavior, although different exponents are found for the power-law divergences of these two quantities. The non-Gaussian parameter was also studied and a very large correction to Gaussian behavior was found. The system with higher colloid packing fraction shows indications of a nearby high-order singularity, causing α scaling to fail, but the general expectations for nonergodicity transitions still hold.

  • Received 31 October 2002

DOI:https://doi.org/10.1103/PhysRevE.67.031406

©2003 American Physical Society

Authors & Affiliations

Antonio M. Puertas

  • Department of Physics, University of Almeria, 04120 Almeria, Spain

Matthias Fuchs

  • Institut Charles Sadron, 67083 Strasbourg Cedex, France

Michael E. Cates

  • School of Physics, University of Edinburgh, JCMB Kings Buildings, Edinburgh EH9 3JZ, United Kingdom

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Vol. 67, Iss. 3 — March 2003

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