Issue 28, 2015

Rheology and dynamics of colloidal superballs

Abstract

Recent advances in colloidal synthesis make it possible to generate a wide array of precisely controlled, non-spherical particles. This provides a unique opportunity to probe the role that particle shape plays in the dynamics of colloidal suspensions, particularly at higher volume fractions, where particle interactions are important. We examine the role of particle shape by characterizing both the bulk rheology and micro-scale diffusion in a suspension of pseudo-cubic silica superballs. Working with these well-characterized shaped colloids, we can disentangle shape effects in the hydrodynamics of isolated particles from shape-mediated particle interactions. We find that the hydrodynamic properties of isolated superballs are marginally different from comparably sized hard spheres. However, shape-mediated interactions modify the suspension microstructure, leading to significant differences in the self-diffusion of the superballs. While this excluded volume interaction can be captured with a rescaling of the superball volume fraction, we observe qualitative differences in the shear thickening behavior of moderately concentrated superball suspensions that defy simple rescaling onto hard sphere results. This study helps to define the unknowns associated with the effects of shape on the rheology and dynamics of colloidal solutions.

Graphical abstract: Rheology and dynamics of colloidal superballs

Supplementary files

Article information

Article type
Paper
Submitted
27 Mar 2015
Accepted
08 Jun 2015
First published
09 Jun 2015

Soft Matter, 2015,11, 5656-5665

Author version available

Rheology and dynamics of colloidal superballs

J. R. Royer, G. L. Burton, D. L. Blair and S. D. Hudson, Soft Matter, 2015, 11, 5656 DOI: 10.1039/C5SM00729A

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