Interfacial structure of solid-stabilised emulsions studied by scanning electron microscopy

Low temperature field emission scanning electron microscopy has been used to visualise the interfacial structure of emulsions stabilised solely by solid particles. Examples are given which include both oil-in-water and water-in-oil emulsions stabilised by either sub-micron silica or polystyrene latex particles, and either cyclohexane, toluene or a medium chain length triglyceride as oil. Evidence is shown of either a close-packed arrangement of particles adsorbed at the curved oil/water interface or of the formation of flocs of particles separated by particle-free regions on the surface. In emulsions stabilised by silica, the stabilising layer appears to be aggregates composed of partially fused primary particles. For emulsions containing latex, individual particles are seen to form a close-packed monolayer at the surface of drops. The findings are discussed in relation to the structure of particle monolayers at planar oil/water interfaces studied previously.