Synthesis and Properties of MPEG‐Coated Superparamagnetic Magnetite Nanoparticles

Abstract

The magnetite nanoparticles were synthesized by the thermal decomposition of iron(III) acetylacetonate in methoxy polyethylene glycol, which was used as solvent, reducing agent, and modifying agent in the reaction. The morphologies and phase compositions of the nanoparticles were determined by transmission electron microscopy and X‐ray diffraction, respectively. The surface coating of the nanoparticles was recognized using Fourier transform infrared spectroscopy. Magnetic properties were measured using superconducting quantum interference device. The zeta potential and hydrodynamic size of the nanoparticles was determined using nanoparticle and zeta potential analyzer. The magnetite nanoparticles show superparamagnetic behavior in 300 K. The negatively charged methoxy polyethylene glycol‐coated magnetite nanoparticles in water exhibited longer‐time dispersion with small hydrodynamic size than the magnetite nanoparticles synthesized by the thermal decomposition of iron(III) acetylacetonate in polyethylene glycol. The less conjunction between methoxy polyethylene glycol‐coated magnetite nanoparticles due to the inert –CH 3 terminal group may cause their higher stability in water dispersion.