Synthesis and properties of magnetite nanoparticles coated with poly(ethylene glycol) and poly(ethylene imine).

Water-soluble magnetite nanoparticles were synthesized by thermal decomposition of iron(III) acetylacetonate in poly(ethylene glycol) in the presence of poly(ethylene imine). The amount of poly(ethylene imine), the reaction temperature and time are found to have significant effects on the shape evolution and size distribution of the magnetite nanoparticles. The prepared magnetite nanoparticles show superparamagnetic behavior at 300 K. Coated with poly(ethylene glycol) and poly(ethylene imine) the magnetite nanoparticles are positively charged and highly soluble in deionized water with small hydrodynamic size, and show longer time dispersion in water except the magnetite nanoparticles prepared with insufficient amount of poly(ethylene imine).