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 Fe3O4were 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.