Synthesis of highly concentrated TiO2 nanocolloids and coating on boron nitride powders

Highly concentrated TiO2 nanocolloids were synthesized by hydrolysis method of TiCl4. Reactions were performed in a TiCl4/HCl/H2O aqueous solution and particle characteristics such as shape, size and aggregation were controlled by polymerization and adsorption of acrylamide on the surface of TiO2 nanoparticles. Moreover, aminopropyltriethoxysilane was added instead of acrylamide, and their effects were compared with each other. The prepared colloids dispersed well and showed strong absorption peaks at 350–370 nm, which blue-shifted to 20–30 nm, as compared with macroparticles. The obtained techniques from TiO2 nanocolloids synthesis were utilized in coating boron nitride powders, which are nonpolar and isoelectronic materials of carbon. Their surface morphology, structure, thermal stability and ultraviolet (UV) absorption characteristics were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG/DTA), ultraviolet–vis spectroscopy (UV–vis).