GROWTH-MECHANISM OF LARGE MONODISPERSED SILICA PARTICLES PREPARED FROM TETRAETHOXYSILANE IN THE PRESENCE OF SODIUM DODECYL-SULFATE

Monodispersed silica particles up to ca. 1.2 mu m in diameter were pre pared by hydrolysis of tetraethoxysilane in the presence of sodium dod ecyl sulfate (SDS). The particle size was increased with an increase o f SDS added. The geometrical standard deviation of the particles was d ecreased with an increase of SDS. In the earlier reaction stage, doubl e spherical particles by the coalescence of the particles were frequen tly observed when large amounts of SDS were added. Particle size was g radually increased after the coalescence occurred and spherical partic les were finally obtained. The results of Nielsen's chronomal analysis suggest that the polynuclear layer growth took place after the coales cence of the particles in the presence of larger amount of SDS.