Hollow microspheres with binary porous membranes from solid-stabilised emulsion templates

We report a simple one pot procedure for the preparation of hollow microspheres with a shell comprised of an inner polymeric porous membrane and an outer layer of colloidal particles. Solid-stabilised emulsions are used as templates for the precipitation of a high molecular weight polymer at the oil-water interface via internal phase separation of a volatile solvent. As the solvent is extracted from the droplets, the polymer forms a porous membrane on their surface and entraps the colloidal monolayer adsorbed at the interface. We demonstrate the versatility of this method by using several types of particle emulsifiers and by preparing hollow microspheres of different size, porosity and surface properties. We also investigate the use of gold nanoparticles in this process and successfully entrap a large number of nanoparticles on the surface of the polymeric membrane by modifying the surface of the nanoparticles in-situ.