IN-SITU STERIC STABILIZATION OF TITANIUM-DIOXIDE PARTICLES SYNTHESIZED BY A SOL-GEL PROCESS

Spherical titanium dioxide particles were synthesized via the hydrolysis of tetraethylorthotitanate (TEOT) in ethanol in the presence of hydroxypropyl cellulose (HPC) which served as an in situ steric stabilizer. This work focused on the effect that water concentration had on the HPC-TiO2 interactions leading to steric stabilization. The water concentration varied in the range [H2O]/[TEOT]=5.3-60. The amount of adsorbed HPC increased threefold over this water concentration range. This correlates with measurements of the preferential adsorption of water on TiO2 in ethanol. The particle size decreased fivefold in the presence of HPC over the range of water concentrations studied owing to the combined effects of increased HPC adsorption and increased nucleation rates. Mean particle diameters as small as 70 nm were obtained.