A novel method of fabricating core-shell structure, comprising monodisperse polystyrene (PS) spheres as cores and Fe3O4 as shells, is demonstrated. The coating shell of magnetite (Fe3O4) crystallites was formed by controlled hydrolysis of aqueous solutions of iron ion with diethyleneglycol (DEG) either by the facile, electrostatic absorption between the polymer and iron compounds. Thickness of the shell could be easily changed in the range from 20 to 60 nm by using slow-injecting coating process. Structure and composition of iron compounds shell were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetric analysis (TG) and vibrating-sample magnetometer (VSM), indicating there are some differences between the Fe3O4-shell of the magnetic composite spheres and pure Fe3O4 particles, e.g. smaller crystallite size, lower magnetic transition temperature and weaker ferromagnetic character.
