The Effect of Particle Shape and Size on the Stability of Pickering Emulsions

Abstract

Emulsions are used in a wide variety of applications in the oil, food and cosmetic industry. They consist of two immiscible liquids where one liquid is dispersed in the other liquid. Pickering emulsions are emulsions where particles are adsorbed at the oil-water interface with a high stabilization energy and are believed to form a continuous layer around the dispersed drops impeding coalescence and hence stabilizing the emulsion. Extensive research has been performed in varying the composition, shape and size of the colloidal particles. In this research, we focus on cubic shaped particles to stabilize oil-in-water emulsions. Using optical and laser scanning confocal microscopy the adsorption and orientation of the cubic particles at the oil-water interface was studied. Whereas the hematite cubes with side lengths of around one micrometer stabilize emulsions with oil droplets of several millimeters, in this study oil droplets of micrometer sizes were observe when using copper oxide cubes of around 60 nm. Both types of cubes can serve as a template for the synthesis as hollow silica cubes, which were used to study the effect of particle size on the stability of oil-in-water emulsions.