Issue 17, 2017

Effects of vertical confinement on gelation and sedimentation of colloids

Abstract

We consider the sedimentation of a colloidal gel under confinement in the direction of gravity. The confinement allows us to compare directly experiments and computer simulations, for the same system size in the vertical direction. The confinement also leads to qualitatively different behaviour compared to bulk systems: in large systems gelation suppresses sedimentation, but for small systems sedimentation is enhanced relative to non-gelling suspensions, although the rate of sedimentation is reduced when the strength of the attraction between the colloids is strong. We map interaction parameters between a model experimental system (observed in real space) and computer simulations. Remarkably, we find that when simulating the system using Brownian dynamics in which hydrodynamic interactions between the particles are neglected, we find that sedimentation occurs on the same timescale as the experiments. An analysis of local structure in the simulations showed similar behaviour to gelation in the absence of gravity.

Graphical abstract: Effects of vertical confinement on gelation and sedimentation of colloids

Article information

Article type
Paper
Submitted
29 Sep 2016
Accepted
28 Mar 2017
First published
12 Apr 2017

Soft Matter, 2017,13, 3230-3239

Effects of vertical confinement on gelation and sedimentation of colloids

A. Razali, C. J. Fullerton, F. Turci, J. E. Hallett, R. L. Jack and C. P. Royall, Soft Matter, 2017, 13, 3230 DOI: 10.1039/C6SM02221A

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