Monolithic organosilica aerogel consisting of hollow microspheres by a simple ambient pressure drying process

Abstract Methyltrimethoxysilane (MTMS) was used as the precursor and the organosilica aerogel was prepared by an acid-base catalyzed two stage process. To the aqueous system of acid-catalyzed hydrolyzate of MTMS, a kind of hydrophobic organic solvent, cyclohexane, which is insoluble in the aqueous phase was added and dispersed into small droplets with the aid of a high speed homogenizer. Then the reaction mixture was transformed into a gel through base catalyzed condensation. The hydrophobic solvent was pre-embedded in the gel in the form of microcapsules with the condensed MTMS hydrolyzate forming the shell. The pre-embedded hydrophobic solvent reduced the interface tension between the pore liquid and the skeleton solid. Ambient pressure drying of the wet gels produced low shrinkage and gave low density monolithic aerogels consisting of hollow microspheres.