Synthesis and characterization of hollow silica microspheres functionalized with magnetic particles using W/O emulsion method

Hollow silica particles functionalized with magnetic particles (HSFMs) were prepared without templates using the W/O emulsion system containing magnetic nanoparticles synthesized by the redox reaction of Fe salts. Since the removal process like etching step is not required, our system is a simple and easy method to obtain the functionalized shell and composite hollow materials. Here, the magnetite nanoparticles not only give the hollow silica particles, the magnetic properties but also influence the formation process of the hollow silica microspheres. It is verified by X-ray diffraction (XRD), energy-dispersive X-ray (EDS), and vibrating sample magnetometer (VSM) measurements that the structure and magnetic property of the magnetic particles were not changed in quality before and after the synthesis of hollow silica particles. From the Brunauer, Emmett, Teller (BET - Nitrogen adsorption–desorption measurements) analysis, hollow silica microspheres functionalized by magnetic nanoparticles (HSFMs) reveal the typical Type I isotherm in the IUPAC classification, which shows a long saturation plateau and involves micropore filling. This method can be extended to the synthesis of hollow silica particles functionalized by other metal oxide materials as well as iron oxide.