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Enhanced gel formation in binary mixtures of nanocolloids with short-range attraction

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posted on 2018-12-10, 11:02 authored by James L. Harden, Hongyu Guo, Martine Bertrand, Tyler Shendruk, Subramanian Ramakrishnan, Robert L. Leheny
© 2018 Author(s). Colloidal suspensions transform between fluid and disordered solid states as parameters such as the colloid volume fraction and the strength and nature of the colloidal interactions are varied. Seemingly subtle changes in the characteristics of the colloids can markedly alter the mechanical rigidity and flow behavior of these soft composite materials. This sensitivity creates both a scientific challenge and an opportunity for designing suspensions for specific applications. In this paper, we report a novel mechanism of gel formation in mixtures of weakly attractive nanocolloids with modest size ratio. Employing a combination of x-ray photon correlation spectroscopy, rheometry, and molecular dynamics simulations, we find that gels are stable at remarkably weaker attraction in mixtures with size ratio near two than in the corresponding monodisperse suspensions. In contrast with depletion-driven gelation at larger size ratio, gel formation in the mixtures is triggered by microphase demixing of the species into dense regions of immobile smaller colloids surrounded by clusters of mobile larger colloids that is not predicted by mean-field thermodynamic considerations. These results point to a new route for tailoring nanostructured colloidal solids through judicious combination of interparticle interaction and size distribution.

History

School

  • Science

Department

  • Mathematical Sciences

Published in

Journal of Chemical Physics

Volume

148

Issue

4

Citation

HARDEN, J.L. ... et al., 2018. Enhanced gel formation in binary mixtures of nanocolloids with short-range attraction. Journal of Chemical Physics, 148: 044902.

Publisher

© American Institute of Physics

Version

  • VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

2018-01-01

Publication date

2018-01-25

Notes

This paper was published in the journal Journal of Chemical Physics and is also available at https://doi.org/10.1063/1.5007038.

ISSN

0021-9606

Language

  • en

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