Preparation and characterization of a novel magnetic composite particles

Firstly, micro-particles Fe 3 O 4 /SiO 2 were prepared by sol-gel method, with nano-Fe 3 O 4 and tetraethoxysilane (TEOS) as original materials. Secondly, γ-aminoproplytriethoxysilane (KH-550) was used as couple agent to deal with the surface of micro-particles Fe 3 O 4 /SiO 2 , therefore amine was introduced to the surface of micro-particles Fe 3 O 4 /SiO 2 /KH-550. Finally, acrylamide (AM) and methyl methacrylic acid (MMA) as the functional comonomers, were grafted on the surface of micro-particles Fe 3 O 4 /SiO 2 /KH-550. The structures and properties of the magnetic particles were characterized by the fourier transform infrared spectroscopy (FTIR), X-ray diffraction analyzer (XRD), laser particle size analyzer, and vibrating sample magnetometer (VSM). The results shows that the characteristic peaks of Si-O-Si, KH-550, and P (AM-MMA) all were displayed in the infrared spectra, respectively. Surface modification of nano-particle Fe 3 O 4 does not affect its crystalline structure, and the grafting copolymers P (AM-MMA) were a crystalline polymer. The median diameter of Fe 3 O 4 /SiO 2 /KH-550/P (AM-MMA) is 72.46 um, whose size is larger than particles Fe 3 O 4 and Fe 3 O 4 /SiO 2 . Fe 3 O 4 and its derivatives remain super-paramagnetism, and the saturation magnetization reduced with the increasing the thickness of the modifying material on the surface of Fe 3 O 4 .