Emulsion droplets are metastable dispersions composed of two immiscible fluids such as water and oil. The associated surface tension forces them into a spherical shape to minimize the free-energy. To decrease the latter and stabilize the emulsion droplets, a surface-active agent can be added. Pickering emulsions are stabilized by the incorporation of particles. For instance, emulsion droplets can serve as ideal compartments for reactions catalysed by nanoparticles (NPs) attached at the oil-water interfaces, can be used as drug-delivery vehicles, sensors, and templates for the fabrication of advanced functional materials. The characteristics of Pickering emulsions pose a number of intriguing fundamental physical questions including a thorough understanding of the perennial lack of detail about how particles arrange at the liquid/liquid interface. Other not completely answered questions include particle effects on interfacial tension, layering, buckling and droplet bridging. Interestingly, emulsion droplets show some relevant characteristics and qualities of living systems that could make them proxies for artificial life. They provide an experimental framework for synthetic biology that is different from other protocell model systems, such as vesicles offering distinct advantages. For instance, the apparent similarity in surface properties between inorganic NPs and globular proteins, and the fluid dynamical properties of droplets, could be combined with different chemistries to target applications and exploration of biological scenarios not easily achievable with other supramolecular platforms. Qualitative analysis is thus needed to improve the stability of Pickering emulsions and understand the fundamentals and applications of the phenomena that contribute to this stability.
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last update: Jan 2021