Abstract:Magnetic nano zinc ferrite fliuds were synthesized using an improved liquid phase chemical method, which would be used to replace tradditional iron oxides magnetic material. A novel copolymer (PLAA) with D, L-lactide (D, L-LA) and alanine was synthesized using stannous octoate as initiator. Magnetic polymer microspheres were fabricated with nano zinc ferrite fluid coated with alanine modified poly lactide. These as-prepared zinc ferrite fluids, modified poly lactide and magnetic composites, were characterized with X-ray diffraction diffractometer, FT-IR spectrometer, nuclear magnetic resonance spectrometer, scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, and thermogravimetric analyzer. The results demonstrate that the as-prepared zinc ferrite is spinel type of ZnFe₂O₄ nano crystals with particle size of 20−45 nm and magnetization of 32×10^{−3 A}·m². Alanine is copolymerized with lactide, and the prepared composite magnetic microsphere is coated with the modified polylactide, with mass fraction of 45.5% of PLA, particle size ranging from 80−300 nm, and magnetization of 10.6×10^{−3 A}·m², which suggests ZnFe₂O₄ enjoys a stable magnetization after being coated by polymer.

Key words: zinc ferrite; alanine; polylactide; magnetic composite microsphere