Multilayer Magnetic Composite Particles with Functional Polymer Brushes as Stabilizers for Gold Nanocolloids and Their Recyclable Catalysis

Abstract

The functional poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) brush was grafted onto the alkyl-bromide-modified magnetite/silica/poly( N, N ′-methylenebisacrylamide- co -2-hydroxyethylmethacrylate) (Fe 3 O 4 @SiO 2 @PHEMA) trilayer microspheres via the surface-induced atom transfer radical polymerization. Fe 3 O 4 @SiO 2 @PHEMA trilayer microspheres with surface alkyl bromide groups were prepared by the combination of sol–gel process for the synthesis of Fe 3 O 4 @SiO 2 core–shell inorganic component and distillation–precipitation polymerization for the formation of PHEMA shell together with the subsequent esterification of the surface hydroxyl group and 2-bromoisobutyryl bromide. Furthermore, the gold nanoparticles were facilely loaded into the functional PDMAEMA brushes through the in situ reduction due to their strong coordinate interaction. These PDMAEMA brush-stabilized gold nanocolloids were used as a catalyst with the reduction of 4-nitophenol to 4-aminophenol as a model reaction, which revealed a highly catalytic efficiency and good reusable property.