Preparation of Solvent-dispersible Nano-silica Powder by Sol-gel Method

ABSTRACT Solvent dispersible nano-silica powder was prepared by a dual-step sol-gel process: first, SiO2 nanoparticles were synthesized through acid-catalyzed hydrolysis and condensation of tetraethyl orthosilicate in 2-propanol aqueous solution. Then, the particles were surface-modified by means of the capping agent trimethylethoxysilane (TMES). The formed product, termed TSiO2 nanopowder, was dispersible in many organic solvents, and the dispersibility was found to depend on the amounts of TMES bounded to the SiO2 nanoparticles. FTIR spectra of TSiO2 samples confirm SiOSi linkage being formed between TMES and SiO2 through the capping reaction. The sizes of TSiO2 dispersed in various solvents, as determined by dynamic light scattering (DLS), fell largely over the range 220 nm for solvents with solubility parameters of 1629.6 MPa1/2. TEM imaging of the nanoparticles indicated that they were well separated with the largest identifiable size of ~10 nm, agreeing with the results obtained from DLS.