Issue 28, 2021

Interfacially-adsorbed particles enhance the self-propulsion of oil droplets in aqueous surfactant

Abstract

Understanding the chemo-mechanical mechanisms that direct the motion of self-propulsive colloids is important for the development of active materials and exploration of dynamic, collective phenomena. Here, we demonstrate that the adsorption of solid particles on the surface of solubilizing oil droplets can significantly enhance the droplets’ self-propulsion speeds. We investigate the relationship between the self-propulsion of bromodecane oil droplets containing silica particles of varying concentration in Triton X-100 surfactant, noting up to order of magnitude increases in propulsion speeds. Using fluorescently labeled silica, we observe packing of the particles at the oil–water interfaces of the rear pole of the moving droplets. For bromodecane oil droplets in Triton X-100, the highest droplet speeds were achieved at approximately 40% particle surface coverage of the droplet interface. We find particle-assisted propulsion enhancement in ionic surfactants and different oil droplet compositions as well, demonstrating the breadth of this effect. While a precise mechanism for the propulsion enhancement remains unclear, the simple addition of silica particles to droplet oil–water interfaces provides a straightforward route to tune active droplet dynamics.

Graphical abstract: Interfacially-adsorbed particles enhance the self-propulsion of oil droplets in aqueous surfactant

Supplementary files

Article information

Article type
Paper
Submitted
19 Dec 2020
Accepted
25 Jun 2021
First published
28 Jun 2021

Soft Matter, 2021,17, 6742-6750

Interfacially-adsorbed particles enhance the self-propulsion of oil droplets in aqueous surfactant

S. I. Cheon, L. B. C. Silva, A. S. Khair and L. D. Zarzar, Soft Matter, 2021, 17, 6742 DOI: 10.1039/D0SM02234A

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