Dynamics of Fractal Cluster Gels with Embedded Active Colloids
| Autor: | Michael J. Solomon, Wenxuan Zhang, Megan Szakasits |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
digestive oral and skin physiology General Physics and Astronomy Janus particles 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Suspension (chemistry) Mean squared displacement Colloid Fractal Chemical physics 0103 physical sciences Cluster (physics) Particle Janus 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review Letters. 119 |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/physrevlett.119.058001 |
| Popis: | We find that embedded active colloids increase the ensemble-averaged mean squared displacement of particles in otherwise passively fluctuating fractal cluster gels. The enhancement in dynamics occurs by a mechanism in which the active colloids contribute to the average dynamics both directly through their own active motion and indirectly through their excitation of neighboring passive colloids in the fractal network. Fractal cluster gels are synthesized by addition of magnesium chloride to an initially stable suspension of $1.0\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ polystyrene colloids in which a dilute concentration of platinum coated Janus colloids has been dispersed. The Janus colloids are thereby incorporated into the fractal network. We measure the ensemble-averaged mean squared displacement of all colloids in the gel before and after the addition of hydrogen peroxide, a fuel that drives diffusiophoretic motion of the Janus particles. The gel mean squared displacement increases by up to a factor of 3 for an active to passive particle ratio of $1\ensuremath{\mathbin:}20$ and inputted active energy---defined based on the hydrogen peroxide's effect on colloid swim speed and run length---that is up to 9.5 times thermal energy, on a per particle basis. We model the enhancement in gel particle dynamics as the sum of a direct contribution from the displacement of the Janus particles themselves and an indirect contribution from the strain field that the active colloids induce in the surrounding passive particles. |
| Databáze: | OpenAIRE |
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