Abstract: The affinity between magnetic particles (Fe3O4) and monomer or its polymer is a key factor affecting the function of microspheres in the preparation of encapsulated magnetic micro spheres(EMMS).Silane coupling [KH570,CH2C(CH3)C(O)OC3H6Si(OCH3)3] was used for the surface modification of fine magnetic particles with 0.2～0.3 μm in size and tetrahedron in crystal form.Ethanol/water solution was used as modification medium for silane coupling.Fourier transform infrared spectrometer and X-ray photoelectron spectra analysis show that the coupling bonds chemically on the particle surface,leading to the affinity improvement between magnetic particles and monomer or its polymer.The encapsulated magnetic microspheres synthesized by dispersion polymerization of styrene in the presence of modified Fe3O4 particles are significantly improved compared with that when unmodified Fe3O4 particles are used.

Key words: Encapsulated magnetic micro-spheres, Modification, Magnetic particle, 　Fe₃O₄, Coupling agents