Arrested demixing opens route to bigels

Varrato, Francesco and Michele, Lorenzo Di and Belushkin, Maxim and Dorsaz, Nicolas and Nathan, Simon H. and Eiser, Erika and Foffi, Giuseppe (2012) Arrested demixing opens route to bigels. Proceedings of the National Academy of Sciences. ISSN 0027-8424, 1091-6490 DOI 10.1073/pnas.1214971109

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Abstract

Understanding and, ultimately, controlling the properties of amorphous materials is one of the key goals of material science. Among the different amorphous structures, a very important role is played by colloidal gels. It has been only recently understood that colloidal gels are the result of the interplay between phase separation and arrest. When short-ranged attractive colloids are quenched into the phase-separating region, density fluctuations are arrested and this results in ramified amorphous space-spanning structures that are capable of sustaining mechanical stress. We present a mechanism of aggregation through arrested demixing in binary colloidal mixtures, which leads to the formation of a yet unexplored class of materials––bigels. This material is obtained by tuning interspecies interactions. Using a computer model, we investigate the phase behavior and the structural properties of these bigels. We show the topological similarities and the geometrical differences between these binary, interpenetrating, arrested structures and their well-known monodisperse counterparts, colloidal gels. Our findings are supported by confocal microscopy experiments performed on mixtures of DNA-coated colloids. The mechanism of bigel formation is a generalization of arrested phase separation and is therefore universal.

Item Type: Article
Uncontrolled Keywords: 2012AREP; IA64;
Subjects: 99 - Other
Divisions: 99 - Other
Journal or Publication Title: Proceedings of the National Academy of Sciences
Identification Number: 10.1073/pnas.1214971109
Depositing User: Sarah Humbert
Date Deposited: 21 Dec 2012 16:29
Last Modified: 23 Jul 2013 10:05
URI: http://eprints.esc.cam.ac.uk/id/eprint/2641

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