Encapsulation of magnetic nanoparticles with polystyrene via emulsifier-free miniemulsion polymerization

Magnetite nanoparticles (Fe3O4), with an average size of about 10 nm, were encapsulated with polystyrene using a new method based on emulsifier-free miniemulsion polymerization in the presence of 2, 2′ azobis (2-amidinopropane) dihydrochloride (V-50) as a cationic ionizable water-soluble initiator and hexadecane as a hydrophobe. Transmission electron microscopy (TEM) proved the presence of magnetite in polymer particles which appeared to be monodisperse in size, approximately 100–300 nm in diameter, through TEM and scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) measurement was used to determine the percentage of magnetite in the products. The results of emulsifier-free miniemulsion polymerization were compared with those of conventional emulsifier-free emulsion polymerization using (V-50) as the initiator in both cases.