Robust preparation of core-shell type silica/polymer nanocomposites by using surface-initiated ARGET ATRP

A facile route for covalent functionalization of silica (SiO₂) nanoparticles with poly(methyl methacrylate) (PMMA) has been investigated. The surfaces of the SiO₂ nanoparticles were treated with 2-bromo-2-methyl-N-[3-(trimethoxysilyl)propyl] propanamide to introduce the initiator moieties on the surface. Subsequently, activators regenerated by using electron transfer atom transfer radical polymerization (ARGET ATRP) of methyl methacrylate were employed for the preparation of SiO₂/PMMA nanocomposites with a CuBr₂/ N,N,N′, N″,N″-pentamethyldiethylenetriamine catalyst system and a tin(II) 2-ethylhexanoate reducing agent. The modification of SiO₂ was confirmed by surface analyses including Fourier transfer infrared spectroscopy and X-ray photoelectron spectroscopy. The morphology of the nanocomposites was investigated by using field-emission scanning electron microscopy and transmission electron microscopy. A thermogravimetric analysis was used to evaluate the thermal properties and the grafting density. The colloidal stability of silica nanoparticles in a common organic solvent was explicitly shown to have been remarkably improved by the grafting process.