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Issue 19, 2016
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Gravitational collapse of depletion-induced colloidal gels

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Abstract

We study the ageing and ultimate gravitational collapse of colloidal gels in which the interparticle attraction is induced by non-adsorbing polymers via the depletion effect. The gels are formed through arrested spinodal decomposition, whereby the dense phase arrests into an attractive glass. We map the experimental state diagram onto a theoretical one obtained from computer simulations and theoretical calculations. Discrepancies between the experimental and simulated gel regions in the state diagram can be explained by the particle size and density dependence of the boundary below which the gel is not strong enough to resist gravitational stress. Visual observations show that gravitational collapse of the gels falls into two distinct regimes as the colloid and polymer concentrations are varied, with gels at low colloid concentrations showing the onset of rapid collapse after a delay time. Magnetic resonance imaging (MRI) was used to provide quantitative, spatio-temporally resolved measurements of the solid volume fraction in these rapidly collapsing gels. We find that during the delay time, a dense region builds up at the top of the sample. The rapid collapse is initiated when the gel structure is no longer able to support this dense layer.

Graphical abstract: Gravitational collapse of depletion-induced colloidal gels

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Publication details

The article was received on 26 Oct 2015, accepted on 11 Mar 2016 and first published on 11 Mar 2016


Article type: Paper
DOI: 10.1039/C5SM02651B
Citation: Soft Matter, 2016,12, 4300-4308
  • Open access: Creative Commons BY license
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    Gravitational collapse of depletion-induced colloidal gels

    R. Harich, T. W. Blythe, M. Hermes, E. Zaccarelli, A. J. Sederman, L. F. Gladden and W. C. K. Poon, Soft Matter, 2016, 12, 4300
    DOI: 10.1039/C5SM02651B

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