SILICA NANOPARTICLES PRODUCED IN AEROSOL OT REVERSE MICROEMULSIONS - EFFECT OF BENZYL ALCOHOL ON PARTICLE-SIZE AND POLYDISPERSITY

Silica nanoparticles have been synthesized in AOT/decane/ammonium hydr oxide reverse microemulsions via-base-catalyzed hydrolysis of tetraeth oxysilane (TEOS). The effect of inter-micellar exchange has been inves tigated by conducting the synthesis experiments in the presence of ben zyl alcohol (BA), an additive which is known to act as a cosurfactant at the water/oil interface, increasing the inter-micellar exchange rat es. Larger, more monodisperse particles are formed at higher benzyl al cohol concentrations. Furthermore, the presence of high concentrations of benzyl alcohol (BA/AOT molar ratios larger than 1.5) promotes phas e separation, probably due to the combined effects of the high benzyl alcohol content and the presence of ethanol (a product of the TEOS hyd rolysis reaction). The effects of benzyl alcohol concentration on part icle size and size distribution have been attributed to the inhibition of nucleation by fast rearrangement of hydrolyzed TEOS species.