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arXiv · 2003.07607

Tuning the rheological behavior of colloidal gels through competing interactions

José Ruiz-Franco·Fabrizio Camerin·Nicoletta Gnan·Emanuela Zaccarelli
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Abstract

We study colloidal gels formed by competing electrostatic repulsion and short-range attraction by means of extensive numerical simulations under external shear. We show that, upon varying the repulsion strength, the gel structure and its viscoelastic properties can be largely tuned. In particular, the gel fractal dimension can be either increased or decreased with respect to mechanical equilibrium conditions. Unexpectedly, gels with stronger repulsion, despite being mechanically stiffer, are found to be less viscous with respect to purely attractive ones. We provide a microscopic explanation of these findings in terms of the influence of an underlying phase separation. Our results allow for the design of colloidal gels with desired structure and viscoelastic response by means of additional electrostatic interactions, easily controllable in experiments.

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José Ruiz-Franco, Fabrizio Camerin, Nicoletta Gnan, Emanuela Zaccarelli. 2020-03-17. Tuning the rheological behavior of colloidal gels through competing interactions. https://doi.org/10.1103/physrevmaterials.4.045601

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