Pickering nanoemulsions comprise particle-stabilized droplets of 200-500 nm diameter. In principle, such formulations offer a range of applications in cosmetics, drug delivery, agrochemicals etc. However, in practice they typically suffer from instability via an Ostwald ripening mechanism. Recently, we have used polymerization-induced self-assembly (PISA) to design a wide range of diblock copolymer nano-objects. More specifically, we have used RAFT aqueous emulsion polymerization to prepare sterically-stabilised spherical nanoparticles of 20-25 nm diameter. Such nanoparticles can be used to stabilize conventional oil-in-water Pickering macroemulsions comprising n-dodecane droplets of 50 µm diameter. Such precursor macroemulsions can be converted into nanoemulsions using high-pressure microfluidization using commercially-available equipment (LV1 Microfluidizer, Microfluidics). Optimization of the processing conditions affords access to final droplet diameters as low as 130 nm. Remarkably, such Pickering nanoemulsions do not seem to suffer from Ostwald ripening: DLS studies indicate no change in the mean droplet diameter after three months storage at 20<sup>o</sup>C.

Pickering nanemulsions using bespoke sterically-stabilized diblock copolymer nanoparticles

253rd National Meeting (2017)

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