SYNTHESIS OF POROUS SIO2 SPHERICAL-PARTICLES BY SOL-GEL METHODS IN W/O EMULSION

Dispersed porous spherical silica particles were prepared by a sol-gel process from solutions of tetramethoxysilane (TMOS), polyethyleneglycol (PEG), H2O and organic solvent in W/O (water in oil phase) emulsions. The interconnected pores can be made by eliminating PEG from gel bodies. Such PEG originates by phase separation between the PEG and the polymerizing silica in common solvents. Microstructures of the particles are affected by the compositions of the starting solutions. The pore diameter increases with an increase in molecular weight of PEG when the molar ratio of PEG as monomer unit to TMOS is fixed to 0.3. The pore diameter decreases and specific surface area increases with an increase in the content of PEG having molecular weight of 50000 when the [PEG]/[TMOS] molar ratio is greater than 0.3. The pore diameter decreases by use of basic solvents such as N,N-dimethylformamide (DMF) and formamide (FA) instead of methanol.