Formation of inorganic/organic nanocomposites by nitroxide-mediated polymerization in bulk using a bimolecular system
Résumé
A series of organic-inorganic nanoparticles were synthesized by nitroxide-mediated polymerization (NMP) of butyl acrylate initiated by a self-assembled monolayer of an azo initiator. The azo initiator was immobilized on silica particles in the presence of a stable nitroxide radical, SG1 (an acyclic β-phosphonylated nitroxide, N-tert-butyl-N-(1-diethylphosphono-2,2- dimethyl)propyl nitroxide). After preliminary qualitative characterization by X-ray spectroscopy (XPS) and Fourier-transform infrared (FTIR) measurements, the nanoparticles were studied by thermogravimetric analysis (TGA) to determine the polymer grafting density and to permit a comparison with corresponding values of the initiator monolayer. It was demonstrated that the grafting from polymerization exhibits a controlled character with a low polydispersity (M̄w/M̄n < 1.2) in a large range of molecular weights of the grafted chains (from 4000 up to 145000 g · mol -1) under the conditions when the stable radical SG1, acting as chain growth moderator tethered to the inorganic core, was used.