Grafting polymers to titania nanoparticles by radical polymerization initiated by diazonium salt

The grafting of biocompatible poly(hydroxyethyl) methacrylate (PHEMA) by a very simple method onto titanium dioxide nanoparticles is reported. The selected grafting process is based on the chemical reduction of diazonium salts by reducing agents in presence of the vinylic monomer. As previously demonstrated on flat surfaces, it leads to strongly grafted and stable polymer films and has many advantages residing in a short one-step reaction occurring at atmospheric pressure, ambient air and room temperature in water. TiO₂ nanoparticles were synthesized by laser pyrolysis, giving nanoparticles with controlled size and composition. The coating, the composition, the chemical structure, and the grafted PHEMA quantities of the resulting products were investigated by Transmission electron microscopy, Infrared-attenuated total reflection, X-ray photoelectron spectroscopy, and Thermogravimetric analysis. It was demonstrated that the PHEMA shell was successfully chemically grafted onto the surface of the TiO₂ core without any significant influence on the morphology of the nanoparticles.