Silica-g-poly[2-(N,N-dimethyl amino) ethyl methacrylate] hybrid nanospheres with polymer brushes as stabilizer for metallic nanocolloids

The silica-g-poly[2-(N,N-dimethyl amino)ethyl methacrylate] (SiO2-g-PDMAEMA) hybrid microspheres with polymer brushes were synthesized by the surface-grafted atom transfer radical polymerization (ATRP) from the surface alkyl bromide functionalized silica nanospheres. The inorganic nanosphere as surface-initiating polymerization site was prepared by the amide reaction of 2-bromoisobutyryl bromide with the surface amino group of silica via modification with (3-aminopropyl) trimethoxysilane (APS). The grafted PDMEMA brushes stabilized metallic nanocolloids (silver and palladium) were prepared by the in situ reduction of the inorganic salt precursors (AgNO3 and PdCl2) through the coordination effect of the amino groups to the metallic atom (Au, Ag). The catalytic properties of PDMAEMA brush-stabilized silver and palladium metallic nanocolloids were investigated via the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AnP) by sodium borohydride (NaBH4) as a model reaction with a facilely recoverable and stable catalytic property. The resultant hybrid microspheres were characterized by transmission electron microscopy (TEM), thermal gravimetric analyzer (TGA), Fourier infrared (FT-IR) spectra, and inductive coupled plasma emission spectrum (ICP).