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Aqueous Droplets Used as Enzymatic Microreactors and Their Electromagnetic Actuation
Published on: August 28, 2017
Ferromagnetic liquid droplets with adjustable magnetic properties
Xuefei Wu1,2,3, Robert Streubel4,5,6, Xubo Liu1,2,3,7
1Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Abstract:
The assembly and jamming of magnetic nanoparticles (NPs) at liquid-liquid interfaces is a versatile platform to endow structured liquid droplets with a magnetization, i.e., producing ferromagnetic liquid droplets (FMLDs). Here, we use hydrodynamics experiments to probe how the magnetization of FMLDs and their response to external stimuli can be tuned by chemical, structural, and magnetic means. The remanent magnetization stems from magnetic NPs jammed at the liquid-liquid interface and dispersed NPs magneto-statically coupled to the interface. FMLDs form even at low concentrations of magnetic NPs when mixing nonmagnetic and magnetic NPs, since the underlying magnetic dipole-driven clustering of magnetic NP-surfactants at the interface produces local magnetic properties, similar to those found with pure magnetic NP solutions. While the net magnetization is smaller, such a clustering of NPs may enable structured liquids with heterogeneous surfaces.
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