Superparamagnetic Fe3O4 nanoparticles were synthesized by chemical coprecipitation method with FeCl36H2O and FeCl24H2O as raw materials

followed by the modification of their surfaces with oleic acid and sodium undecylenate

and a stable water-based magnetic fluid with solid content of 4% was obtained.The seed microspheres were prepared through soap-free emulsion polymerization with the existence of magnetic fluid

using styrene (St) and glycidyl methacrylate (GMA) as the monomers.Then core-shell magnetic fluorescent microspheres were prepared through soap-free seeded emulsion polymerization in the presence of seeded microspheres

using styrene (St)

sodium 4-vinyl benzenesulfonate (NaSS) and rare earth complexes Eu(AA)3Phen as functional monomer

the microspheres exhibit excellent magnetic properties as well as fluorescent properties.The structure

morphology

magnetic and fluorescent properties of the microspheres were characterized by X-ray diffraction (XRD)

transmission electron microscopy (TEM)

photon correlation spectroscopy (PCS)

Fourier transform infrared spectroscopy (FTIR)

vibrating sample magnetometer (VSM) and fluorescence spectroscopy.It was indicated that seed microspheres and magnetic fluorescent microspheres showed good monodispersity

with the average particle diameter of 147 nm and 228 nm respectively

TGA analysis showed that the Fe3O4 content of magnetic fluorescent microspheres was 4.7%

corresponding to a saturation magnetization of 0.396 emu/g

and characteristic emission spectra of rare earth Eu3 + were observed at 595 nm and 619 nm.