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Issue 1, 2016
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Connecting structure, dynamics and viscosity in sheared soft colloidal liquids: a medley of anisotropic fluctuations

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Abstract

Structural distortion and relaxation are central to any liquid flow. Their full understanding requires simultaneous probing of the mechanical as well as structural and dynamical response. We provide the first full dynamical measurement of the transient structure using combined coherent X-ray scattering and rheology on electrostatically interacting colloidal fluids. We find a stress overshoot during the start-up of shear which is due to the strong anisotropic overstretching and compression of nearest-neighbor distances. The rheological response is reflected in uncorrelated entropy-driven intensity fluctuations. While the structural distortion under steady shear is well described by Smoluchowski theory, we find an increase of the particle dynamics beyond the trivial contribution of flow. After the cessation of shear, the full fluid microstructure and dynamics are restored, both on the structural relaxation timescale. We thus find unique structure-dynamics relations in liquid flow, responsible for the macroscopic rheological behavior of the system.

Graphical abstract: Connecting structure, dynamics and viscosity in sheared soft colloidal liquids: a medley of anisotropic fluctuations

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Publication details

The article was received on 10 Jul 2015, accepted on 26 Sep 2015 and first published on 09 Oct 2015


Article type: Paper
DOI: 10.1039/C5SM01707F
Author version available: Download Author version (PDF)
Citation: Soft Matter, 2016,12, 171-180
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    Connecting structure, dynamics and viscosity in sheared soft colloidal liquids: a medley of anisotropic fluctuations

    F. Westermeier, D. Pennicard, H. Hirsemann, U. H. Wagner, C. Rau, H. Graafsma, P. Schall, M. Paul Lettinga and B. Struth, Soft Matter, 2016, 12, 171
    DOI: 10.1039/C5SM01707F

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