Synthesis of polystyrene-grafted nanosilica via nitroxide radical coupling reaction and its application in UV-curable acrylate-based coating systems

The fabrication of polystyrene-grafted nanosilica (SiO2-g-PS) via nitroxide radical coupling (NRC) reaction was presented in this study. First, nanosilica anchored with 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO)-based nitroxide radicals was synthesized by hydrolysis-condensation reaction between TEMPO-based nitroxide radical functional triethoxysilyl coupling agents and nanosilica. Then, the pre-synthesized, well-defined PS with bromide end group which was obtained by atom-transfer radical polymerization (ATRP) was grafted onto the functionalized nanosilica in the presence of CuBr/PMDETA. The structure, surface morphologies and particle size of the obtained hybrid nanoparticles were investigated by characterization methods The grafting yield by this method achieved up to 37.5% in the given conditions, which is approximated to the ones obtained by `grafting to' route. A comprehensive study of UV-curable formula based on acrylates/polymer-grafted nanosilica were also discussed to find a possible correlation among the viscosity, curing kinetics, mechanical and thermal properties of the final hybrid organic-inorganic coatings.