Colloidosomes formation by controlling the solvent extraction from particle-stabilized emulsions

Colloidosomes with porous shells have attracted attention in recent years because of the great potential as vehicles for controlled delivery of active ingredients. We present herein a simple and flexible method to prepare colloidosomes by a combination of particle-stabilized emulsion and solvent extraction method. We first generate an oil-in-water (o/w) emulsion where the dispersed phase is slightly soluble in the continuous phase and contains a water-insoluble polymer. Polystyrene particles, suspended in the dispersed phase, absorb onto the surface of oil droplet to stabilize the emulsions. The particles at the interface eventually become the shell of colloidosome microcapsules upon the removal of the oil by solvent-mediated diffusion. In addition, during the oil removal, the dissolved water-insoluble polymer likely deposits at the interface and binds the assembled polystyrene particles together, in turn leading to mechanical stable colloidosomes. We demonstrate that the size and morphology of the resultant colloidosome microcapsules depend on the type of the solvent and the oil extraction rate.