Large-scale preparation of macro-porous silica microspheres via sol–gel composite particles and a spray drying process

Abstract

One novel method of preparing macro-porous silica microspheres on a large scale is presented here, which utilized spray drying silica/polymer composite particles and calcination. Silica/polymer composite particles were prepared via sol–gel reaction of siloxane on polymer latex particles, which were obtained via cationic emulsion polymerization. Afterwards the latex of composite particles was spray dried to produce hollow microspheres, and the microspheres were calcinated to remove the polymer particle templates so that a porous structure could be generated. With these common industrial procedures, macro-porous silica microspheres could be prepared on a large scale. Parameters like polymer particle glass transition temperature and cationic monomer amount in emulsion polymerization were explored. It was found that, with a glass transition temperature of 10 °C and a cationic monomer amount of 5.0 wt%, composite particles could well coalesce during spray drying and generate uniform macro-porous structure.