Double role of polyethylene glycol in the microwaves-assisted non-hydrolytic synthesis of nanometric TiO2: Oxygen source and stabilizing agent

The microwaves-assisted reaction between titanium(IV) tetrachloride and polyethylene glycol (PEG) represents a novel non-aqueous sol-gel route for synthesizing surface-stabilized titanium dioxide nanoparticles. X-ray powder diffraction measurements showed the exclusive presence of anatase phase. Transmission electron microscopy investigations revealed that the particles are nearly uniform in shape with sizes ranging from 4 to 8 nm and a low degree of agglomeration. The presence of covalently bonded PEG chains on the particles surface has been shown by Fourier transform infrared (FT-IR) spectroscopy. This surface functionalization greatly enhances the dispersibility of the particles in water, as observed by dynamic light scattering and zeta-potential analyses. Furthermore, the investigation of the reaction by-products by a combination of FT-IR and high-performance liquid chromatography (HPLC-Mass) techniques allowed a deeper insight into the reaction mechanism suggesting a double role of PEG as a stabilizing agent and an oxygen source. Graphical Abstract: [Figure not available: see fulltext.]