Structure formation from mesoscopic soft particles

A. Fernández-Nieves, J. S. van Duijneveldt, A. Fernández-Barbero, B. Vincent, and F. J. de las Nieves
Phys. Rev. E 64, 051603 – Published 22 October 2001
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Abstract

In this work, the aggregation of mesoscopic gel particles (soft colloids) has been experimentally investigated. The interaction between particles was controlled through the addition of salt, above the critical coagulation concentration, resulting in aggregation with finite bond energies. Attention has been paid to the structure of the clusters formed in the process as well as to the aggregation kinetics. The results indicate that the clusters are fractal and the kinetics of aggregation can be described through the dynamic scaling solution of the Smoluchowski equation. As the energy minimum increases in depth the resultant clusters pass from a very compact structure to typical diffusion-limited cluster aggregation (DLCA) fractal dimension values. In addition, the kinetics of growth change from those observed in reaction controlled aggregation to DLCA. These results can be explained within the framework of a reversible growth model, arising from the fact that aggregation takes place in an energy minimum of restricted depth. Moreover, they show that structure and kinetics decouple for such a soft sphere system, in contrast to what is encountered for DLCA and reaction-limited processes. Finally, an unexpected return to a reaction controlled aggregation kinetics was observed for sufficiently deep energy minima, which could be due to the polymerlike particularities of the soft particles considered in this work.

  • Received 10 April 2001

DOI:https://doi.org/10.1103/PhysRevE.64.051603

©2001 American Physical Society

Authors & Affiliations

A. Fernández-Nieves1, J. S. van Duijneveldt2, A. Fernández-Barbero1, B. Vincent2, and F. J. de las Nieves1,*

  • 1Group of Complex Fluids Physics, Department of Applied Physics, University of Almería, 04120 Almería, Spain
  • 2School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom

  • *Author to whom correspondence should be addressed. Email address: fjnieves@ual.es

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Vol. 64, Iss. 5 — November 2001

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