Preparation of magnetic composite microsheres by soap-free emulsion polymerization in the presence of 1,1-diphenylethene

The magnetic composite microspheres, which had no surface active agents on the surface and were more suitable for use of biomedicine, were prepared by a simple method - DPE method. In the preparation of 1, 1-diphenylethene (DPE), methyl methacrylate (MMA) and acrylic acid (AA) took place soap-free polymerization, and the living short copolymer chains, which could chelate with Fe₃O₄, were prepared. Then Fe₃O₄ were added, the living short copolymer chains were chelated to the surface of Fe₃O₄. The subsequent polymerization could take place on the surface of the Fe₃O₄, then the magnetic composite microspheres were prepared. The effects of AA , DPE, Fe₃O₄ and initiator were investigated in detail. With the increase of AA, DPE and initiator,the morphology of magnetic composite microspheres improved and then declined. The morphology of magnetic composite microspheres had no big change with addition of Fe₃O₄, but the magnetic content increased obviously. The magnetic composite microspheres,prepared in optimum conditions, were characterized by transmission electronic microscopy (TEM), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The results showed that for these magnetic composite microspheres the magnetic content was about 20%, the specific saturation magnetization was about 32.2 emu/g, the average size was 265 nm and there were no any impurity on their surface.