Preparation of quarternary chitosan/Fe₃O₄ composite magnetic nanoparticles by reversed microemulsion method

Quarternary chitosan, N-2-hydroxylpropyl trimethyl ammonium chloride chitosan was synthesized using 2, 3-epoxypropyl trimethyl ammonium chloride as reagent for quaterization. The degree of quaterization was measured by silver nitrate potential titration method. Water-based Fe₃O₄ magnetic nanoparticles were prepared using sodium citrate as modifier by one-step method. QC/Fe₃O₄ composite magnetic nanoparticles were prepared through reversed microemulsion and static self-assembly method. The structure and performance of the composite magnetic nanoparticles were characterized through a series of measures. QC is mainly covered on the surface of Fe₃O₄ magnetic nanoparticles according to the results of Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG) and X-ray photoelectron spectroscopy (XPS). The results of transmission electron microscopy (TEM) and X-ray diffraction (XRD) show that the composite magnetic nanoparticles have magnetic core with crystal structure of Fe₃O₄, and the average particle size is about 50 nm~60 nm. The prepared composite nanoparticles are still superparamagnetic with a specific saturation magnetization of 19.4 emu/g by the results of vibrating sample magnetometer (VSM).