A novel approach to hollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via interfacial polymerization

We report a novel and facile approach to the preparation of hollow superparamagnetic magnetite/ polystyrene nanocomposite microspheres by the interfacial polymerization technique. The polymerization is initiated by the free radicals at the surface of magnetite nanoparticles (MPs) which are located at the oil/water interface at room temperature and under ambient pressure. The final products were thoroughly characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy ( FTIR), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS), which showed the formation of hollow magnetite/ polystyrene nanocomposite microspheres. Magnetic hysteresis loop measurements revealed that both MPs and hollow nanocomposite microspheres displayed superparamagnetism and that the latter still showed strong magnetic induction. The effects of the ultrasonication time, the dose rate, the added amount of MPs and different types of MPs on the structure and shape of the final products were studied. We have also studied the polymerization kinetics and proposed a possible formation mechanism of hollow superparamagnetic nanocomposite microspheres.