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

Spherical titanium dioxide particles were synthesized via the hydrolys is of tetraethylorthotitanate (TEOT) in ethanol in the presence of hyd roxypropyl cellulose (HPC) which served as an in situ steric stabilize r. This work focused on the effect that water concentration had on the HPC-TiO2 interactions leading to steric stabilization. The water conc entration varied in the range [H2O]/[TEOT]=5.3-60. The amount of adsor bed HPC increased threefold over this water concentration range. This correlates with measurements of the preferential adsorption of water o n TiO2 in ethanol. The particle size decreased fivefold in the presenc e of HPC over the range of water concentrations studied owing to the c ombined effects of increased HPC adsorption and increased nucleation r ates. Mean particle diameters as small as 70 nm were obtained.