Clusters in Colloidal Dispersions with a Short-Range Depletion Attraction: Thermodynamic Identification and Morphology

Published

July 15, 2022

Author(s)

Fernando Soto-Bustamante, Nestor E. Valadez-Perez, Yun Liu, Ramon Castaneda-Priego, Marco Laurati

Abstract

Hypothesis: Particle aggregation is ubiquitous for many colloidal systems, and drives the phase separation or the formation of materials with a highly heterogeneous largescale structure, such as gels, porous media and attractive glasses. While the macroscopic properties of such materials strongly depend on the shape and size of these particle aggregates, the morphology and underlining aggregation physical mechanisms are far from being fully understood. Recently, it has been proposed that for reversible colloidal aggregation, the cluster morphology is determined by a single variable, namely,the reduced second virial coefficient, B^∗₂. Experiments: We examined this proposal by performing confocal microscopy experiments and simulations on a large collection of short-ranged attractive colloidal systems with different values of the attraction strength and range. Findings: We show that in all cases a connection between the colloidal cluster morphology and B^∗₂ can be established. This physical scenario holds at all investigated thermodynamic conditions, namely, in the liquid state, in the metastable region and in non-equilibrium conditions. Without exceptions, our findings show that the connection between reversible colloidal aggregation and the so-called extended law of corresponding states can be firmly established. Additionally, we confirm that in all regions of the state diagram, distinct populations of small and large clusters with different fractal dimensions are present.

Citation

Journal of Colloid and Interface Science

Volume

618

Pub Type

Journals

Keywords

Clusters, sticky hard sphere, confocal, morphology

Citation

Soto-Bustamante, F. , Valadez-Perez, N. , Liu, Y. , Castaneda-Priego, R. and Laurati, M. (2022), Clusters in Colloidal Dispersions with a Short-Range Depletion Attraction: Thermodynamic Identification and Morphology, Journal of Colloid and Interface Science (Accessed October 20, 2025)