Investigation on Formation Mechanism of Magnetic Nanoparticles-coated on Polystyrene Microspheres in Aqueous Solution of Anhydrous Ethylenediamine and Hexamethylene Tetramine

The monodispersed polystyrene (PS) microspheres were modified by concentrated sulfuric acid to obtain PS microspheres with negative charges, and then polystyrene/magnetic composite microspheres were fabricated by a simple and novel method in aqueous solution of anhydrous Ethylene diamine (EDA) and Hexamethylenetetramine (HMTA). Through serials of contrast experiments (based on different precursor ratios) and characteristic investigations of target samples, we have discovered the functions of EDA and HMTA, respectively. EDA not only acted as a weak base providing OH- ions, but also acted as a chelating combining with Fe2 ions, which could control the concentration of Fe2 ions, and resulted in the pure Fe3O4 nanoparticle coated on the surface of PS microspheres. Otherwise, the typical XRD peaks of FeOOH and Fe3O4 appeared, simultaneously, if HMTA played an action in the formation magnetic nanoparticles-coated PS microspheres. It indicated that HMTA could provide OH- ions and make Fe2 to become FeOOH and Fe3O4, simultaneously, which could be confirmed the reaction mechanism suggested by us. Finally, the corresponding possible reaction mechanisms of EDA and HMTA for fabricating magnetic composite microspheres have been suggested in detail by combining SEM, XRD, FTIR analysis together.