Nanoparticle-Stabilized Double Emulsions and Compressed Droplets

Stable double emulsions, both oil-in-water-in-oil and water-in-oil-in-water, stabilized by two types of nanoparticles residing at the o/w interfaces (see picture; red: CdSe quantum dots) were prepared in a simple fashion by shaking, and with narrow size distributions by microcapillary flow focusing. These double-emulsion droplets proved stable against coalescence throughout solvent evaporation, allowing for formation of nanoparticle foams and hexagonally arrayed structures.