Surface chemical modification of nanosized oxide particles with a titanate coupling reagent in isopropanol

The function of the hydroxyl on particle surface in chemical modification in isopropanol with titanate coupling reagent CA7 was investigated. Four kinds of nanosized oxide particles: anatase TiO2, rutile TiO2, gamma-Al2O3, and monoclinic Zt-O-2, were used in experiments. The effects of different crystal structures of polymorph TiO2 on the chemical modification, i.e., anatase and rutile TiO2, were studied. Fourier tranform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric (TG) analyses showed that the surfaces of anatase TiO2, gamma-Al2O3, and monoclinic ZrO2 were chemically modified, and the quantities of CA7 reacted on particle surfaces were 1.66, 1.79, and 4.29 molecule nm(-2), respectively. It was difficult to chemically modify rutile TiO2. The hydroxyl groups on anatase TiO2 have IR adsorption bands at 3714 and 3672 cm(-1). The 3714 cm(-1) hydroxyl reacted with CAT The hydroxyl on rutile TiO2 particle has a frequency of 3739 cm(-1), but this did not react with CAT XPS analysis showed that the binding energies of the oxygen and metal atoms on the modified oxide surfaces were increased. It was inferred that the hydroxyl group has its proton displaced to form a Me-O: species that, together with existing Me-O: on the particle surface, reacted with CA7 to form a Me-O-Ti bond.