Fe3O4–SiO2–P4VP pH‐Sensitive Microgel for Immobilization of Nickel Nanoparticles: An Efficient Heterogeneous Catalyst for Nitrile Reduction in Water

Abstract Fe 3 O 4 magnetic nanoparticles (MNPs) were modified with (3‐aminopropyl)triethoxysilane through silanization. An atom transfer radical polymerization‐initiating site immobilized onto amine‐functionalized Fe 3 O 4 MNPs. The surface‐initiated atom transfer radical polymerization of 4‐vinylpyridine was then performed in the presence of Fe 3 O 4 –SiO 2 –Br nanoparticles, which led to the formation of Fe 3 O 4 –SiO 2 –P4VP [P4VP=poly(4‐vinylpyridine)] hybrid microgels cross‐linked with Fe 3 O 4 MNPs. Our approach uses polymer microgels as templates for the synthesis of nickel nanoparticles (NiNPs). The tunable properties of synthesized NiNPs@Fe 3 O 4 –SiO 2 –P4VP pH‐sensitive microgels were used in the catalytic reduction of aliphatic and aromatic nitriles. Moreover, the catalytic activity of metal nanocomposites that can be modulated by the volume transition of microgel structures with changing pH has been evaluated. TEM, X‐ray photoelectron spectroscopy, thermogravimetric analysis, atomic absorption spectroscopy, XRD, UV/Vis spectroscopy, and FTIR spectroscopy were used to characterize the resultant catalyst.