A strategy for synthesis of magnetic nanoparticles with "well-defined" polymers via reversible addition fragmentation chain transfer polymerization under ultrasonic irradiation

The controlled graft modification of Fe3O4 magnetic nanoparticles has been achieved by reversible addition fragmentation chain transfer (RAFT) polymerization under ultrasonic irradiation. The nanoparticles of Fe3O4 were first prepared by a chemical co-precipitation method, and reacted with 3-aminopropyltriethoxylsilane (KH550), and subsequently with S-1-dodecyl-S'-(alpha,alpha'-dimethyl-alpha'-acetic acid) trithiocarbonate (DDACT) to serve as RAFT agent. The graft polymerization of methyl acrylate was carried out under ultrasonic irradiation (28 KHz, 60 W). The first-order kinetics and the polymers with narrow molecular weight distributions suggested the polymerization proceeded via RAFT process. The resultant products were characterized by Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), high performance particle sizer (HPPS) and Gouy magnetic balance. The resultant products with good paramagnetism could be well modified with the "well-defined" polymers via RAFT polymerization under ultrasonic irradiation, thereby providing a new method to well modify magnetic nanoparticles.