In situ production of spherical silica particles containing self-organized mesopores

A spray drying method was used to produce a silica powder that contained ordered mesopores. A colloidal mixture of silica nanoparticles and polystyrene latex nanoparticles was mixed and sprayed as droplets into a vertical reactor that contained two temperature zones. The solvent in the droplets was evaporated at the front part of the reactor to produce a powder composite consisting of silica and PS nanoparticles. The PS nanoparticles in the powder were evaporated in the back portion of the reactor to produce a silica powder consisting of mesopores. The mesopores was observed to be arranged into a hexagonal packing, indicating the self-organization process occurred spontaneously during the solvent evaporation. The entire process was completed in only several seconds, which is contrary to currently available methods that require several hours or up to several days to complete this self-organization process.