Synthesis of recoverable thermosensitive Fe3O4 hybrid microgels with controllable catalytic activities

High efficiency recoverable catalytic magnetite microgel particles comprising of a magnetic Fe3O4 nanoparticles (NPs) core with a thermo-sensitive poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) polymer shell were synthesized through a four-step procedure. The preparation route contained: (1) preparation of Fe3O4 NPs through the hydrothermal method; (2) attachment of double bond functionalization to the surface of the NPs; (3) self-initiated photo-grafting and photopolymerization (SIPGP) of monomer of 2-(dimethylamino) ethyl methacrylate (DMAEMA); (4) anchoring Au onto Fe3O4@PDMAEMA magnetic microgel particles. Perfect surface functionalization was characterized by dynamic light scattering (DLS), fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM) analysis. The Fe3O4@PDMAEMA-Au microgel particles exhibited excellent thermally adjustable catalytic activities for the typical reduction of 4-nitrophenol (4-NP). In addition, the Fe3O4@PDMAEMA-Au catalyst was responsive to the external magnetic field, performing the microgel particles easy to separate and recover from the water after catalytic reactions. This type of novel smart microgel nanocatalysts has the potential to be applied as high performance more sustainable catalytical systems in chemical synthesis, micromotors, and bio-molecule immobilization fields.