Chemical reactions have been shown to be effective at transporting and organizing colloidal particles. In the first part of the talk, we discuss the propulsion of active colloids with surface chemical reactions due to diffusiophoresis. We develop a theoretical framework to demonstrate that a pair of interacting active colloids can show a range of dynamical behaviors including attraction, repulsion and chasing. We apply this framework to many-particle systems and find complex collective behavior on the system scale, consistent with recent experiments. In the second part of the talk, we discuss the transport driven by buoyancy gradients due to density differences between reactants and products of a chemical reaction. We show that the resulting fluid flow can be quantified by a Darcy-type model in a wide range of confined systems. Finally, we identify combinations of physical parameters for which both buoyancy-driven and diffusiophoretic transport may compete or cooperate to drive colloidal motion.

Propulsion of colloids in chemically active systems

2019 Spring National Meeting

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