Synthesis of well-defined poly(n-vinylpyrrolidone)/n-TiO2 nanocomposites by xanthate-mediated radical polymerization

Abstract

For the first time formation of well-defined poly n-vinylpyrrolidone/n-TiO2 nanocomposite by xanthate-mediated radical polymerization was accomplished. The synthesis of polymer nanocomposite materials has been intensively studied due to their extraordinary properties and wide-spread potential applications. For this purpose, first 2‐propionic acid-O-ethyl xanthate, as a RAFT agent, was synthesized by the reaction of 2-bromopropionic acid with potassium O-ethyl xanthate with acetone as the solvent. A carboxylic group in the RAFT agent was attached to the n-TiO2 surface by metalation reaction. Then, RAFT polymerization of n-vinylpyrrolidone (NVP) was subsequently conducted to graft poly(n-vinylpyrrolidone) (PNVP) onto the exterior surface of n-TiO2 nanoparticles, forming a novel core–shell nanostructure with a mesoporous core and a polymeric nanoshell. The viscosimetry data and 1H NMR spectra were used to calculate the molecular weight of the polymer. The obtained results showed a good agreement withthe methods used. A significant enhancement in the stability of the composites was obtained as demonstrated by the TGA results. The SEM and TEM results showed that the polymer was formed on the surface of the particles. The XRD pattern of the nanoparticles of n-TiO2 presented the amorphous structure of the crystal morphology of the composites. The FTIR and UV–visible spectroscopy results proved that the PNVP chains were grafted onto the n-TiO2 nanoparticles by surface RAFT polymerization.