Oil-coated bubbles in particle suspensions,capillary foams,and related opportunities in colloidal multiphase systems

The interaction of solid particles with fluid interfaces in colloidal multiphase systems can lead to a wide range of fascinating and sometimes useful phenomena. Most of the research in this area has focused on ternary systems with two immiscible fluids and one particle species. After a brief review of some common characteristics, this article discusses recent insights and future opportunities regarding systems that confront particles with multiple types of fluid interfaces, focusing in particular on the interaction of particles with oil-coated bubbles in aqueous media. Relevant examples include the particle-assisted reconfiguration of bubble–droplet morphologies, the separation of hydrophilic particles from aqueous slurries by oily bubble flotation, and the formation of capillary foams, a promising new class of foam materials.