Synthesis of Mesocellular Silica Foams with Tunable Window and Cell Dimensions

Polystyrene microspheres coated with cationic surfactants are easily prepared by microemulsion polymerization. These microspheres can be used in place of surfactants to synthesize porous silica foams. The nature of the foams depends strongly upon the synthesis conditions. Under basic catalysis, "closed-cell" foams are obtained. Under acidic catalysis, open-cell foams are obtained. The windows that connect the cells of the open-cell foams are believed to arise from direct contact between adjacent spherical templates. These silica foams resemble dense aerogels.