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Advective-diffusive spreading of diffusiophoretic colloids under transient solute gradients

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Abstract

We analytically calculate the one-dimensional advective-diffusive spreading of a point source of diffusiophoretic (DP) colloids, driven by the simultaneous diffusion of a Gaussian solute patch. The spreading of the DP colloids depends critically on the ratio of the DP mobility, M (which can be positive or negative), to the solute diffusivity, Ds. For instance, we demonstrate, for the first time, that solute-repelling colloids (M < 0) undergo long-time super-diffusive transport for M/Ds < −1. In contrast, the spreading of strongly solute-attracting colloids (M/Ds ≫ 1) can be spatially arrested over long periods on the solute diffusion timescale, due to a balance between colloid diffusion and DP under the evolving solute gradient. Further, a patch of the translating solute acts as a “shuttle” that rapidly transports the colloids relative to their diffusive timescale. Finally, we use numerical computations to show that the above behaviors persist for three-dimensional, radially symmetric DP spreading. The results presented here could guide the use of DP colloids for microscale particle sorting, deposition, and delivery.

Graphical abstract: Advective-diffusive spreading of diffusiophoretic colloids under transient solute gradients

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Publication details

The article was received on 26 Sep 2019, accepted on 11 Nov 2019 and first published on 12 Nov 2019


Article type: Paper
DOI: 10.1039/C9SM01938C
Soft Matter, 2019, Advance Article

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    Advective-diffusive spreading of diffusiophoretic colloids under transient solute gradients

    H. C. W. Chu, S. Garoff, R. D. Tilton and A. S. Khair, Soft Matter, 2019, Advance Article , DOI: 10.1039/C9SM01938C

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