The first successful method for the preparation of
monodisperse, spherical silica nanoparticles was reported by Stöber et al. in 1968,based on the hydrolysis of tetraethyl orthosilicate (TEOS) in alcohol media under catalysis by ammonia. With their procedure,
it is possible to obtain different-sized silica spheres in
the whole colloidal size range, simply by changing the
initial concentrations of the reagents.