Preparation and characterization of TiO2 nanoparticles surface-modified by octadecyltrimethoxysilane

Titanium dioxide (TiO2) nanoparticles surface-modified by octadecyltrimethoxysilane (commercial name WD-11) are prepared via in situ surface-modification in dehydrated ethanol at room temperature. As-obtained TiO2 nanoparticles are characterized by means of Fourier transform infrared spectrometry, thermogravimetric, X-ray diffraction and transmission electron microscope. The tribological properties of TiO2 nanoparticles surface-capped by WD-11 as an additive in liquid paraffin are evaluated with a four-ball friction and wear tester. It is found that WD-11 is chemically bonded to the surface of TiO2 nanoparticles during the surface modification process, resulting in increased dispersibility of TiO2 nanoparticles in various organic solvents. UV-vis transmittance spectra show that the light transmittance of modified TiO2 nanoparticles in liquid paraffin (1%, w/v) is over 99%, which indicates that highly dispersed TiO2 nanoparticles can be obtained. Besides, surface-capped TiO2 nanoparticles are able to significantly improve the antiwear ability of liquid paraffin, showing promising application as a multifunctional lubricating oil additive of steel-steel frictional pair.