INFLUENCE OF SOLVENTS ON THE STRUCTURE OF SIO2 GEL FROM HYDROLYSIS OF TETRAMETHYLORTHOSILICATE

The effects of solvents on bulk density, specific surface area and pore size distribution of alkoxy-derived silica dry gel were investigated. Bulk densities of dry gel prepared using solvents of high dipole moment such as N,N-dimethylformamide (DMF), ethylene glycol (EG), formamide (FA) and ethyleneglycolmonomethylether (EGM) decreased with increasing amount of solvent. The specific surface area of the gels using EGM and EG increased monotonically with an increase of their content, whereas it decreased drastically by small addition and then increased when DMF or FA were used. These results were rationalized in terms of competition between the promotion of polymerization and the inhibition of coalescence among primary particles in the presence of organic solvent.