Pickering emulsions stabilized with differently charged particles.

For addressing health issues and ecological concerns, the cosmetic and pharmaceutical industries are facing the challenge of designing emulsions without the use of surfactants. Emulsions stabilized by colloidal particles, known as Pickering emulsions, are promising in this matter. In this article, three different types of particles (neutral, anionic and cationic) are used alone or in binary mixtures as stabilizers of Pickering emulsions. The influence of the particles' charge on the emulsions' properties and the synergies between the different types of particles are studied. It is demonstrated that the kinetics of adsorption of the particles at the water/oil interface control the coverage and their organization at the droplet surface, rather than their interactions after adsorption. Binary mixtures of differently charged particles are a powerful way to control the droplet coverage and the particle loading in the emulsions. In particular, the combination of anionic and cationic particles led to smaller droplets and higher particle coverage of emulsion droplets.