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Pickering Emulsions

As novel emulsifiers, the use of nanostructured particles allows the preparation of solid-stabilized oil/water or water/oil emulsions (“Pickering emulsions”). By the choice of the nanoparticle material and shell, the properties of the emulsion droplets can be adjusted. Thermo- and magnetoresponsive solid-stabilized o/w emulsions are obtained by coating superparamagnetic nanoparticles with polymers with LCST- or UCST behavior in one of the liquid phases  (Figure 1).1

These emulsions allow the remote manipulation of the droplets by temperature - addressing the shell, and/or external magnetic fields - addressing the magnetic core. (Figure 2).

Such systems are of interest for the encapsulation of lipophilic (o/w) or hydrophilic (w/o) substances, their magnetic transport and release upon an external stimulus. So-called Janus particles can be produced with the help of Pickering emulsions.2 These are particles with two or more distinct types of properties, for example a particle with two hemispheres bearing different functional groups (Figure 3). Janus particles are useful as building blocks for supraparticular assemblies, as surfactants or as nanoswimmers in a fuel solution.

1. "Magnetic Capsules and Pickering Emulsions Stabilized by Core-Shell Particles", A. Kaiser, A. M. Schmidt, Langmuir 25(13), 7335 (2009).
2. "Design and synthesis of Janus micro- and nanoparticles", A. Perro, S. Ravaine, E. Bourgeat-lami, E. Duguet, J. Matter. Chem 15, 3745-3760 (2005).