Synthesis of silica aerogels:: Influence of the supercritical CO2 on the sol-gel process

The synthesis of silica aerogels was modified by addition of supercritical CO2 during the sol-gel process. It was shown, that CO2 acts as a catalyst and accelerates the gelation significantly. This effect was studied under a multitude of experimental conditions. The influence of the precursor concentration, temperature and the nature of the catalysts and solvent on the gel formation in presence of CO2 was studied. Several gels obtained by this method were dried and transparent silica aerogels were produced.