Preparation Of Core/Shell Structured Magnetic Nanoparticles With Rich Carboxyl Groups Via Molecule Self-Assembly Method

Molecular self-assembly was used to prepare carboxyl groups functionalized Fe3O4 core/shell nanoparticles in this paper. At the same time, various conditions of self-assembly process and polymerization were optimized.First of all, monolayer oleic acid coated Fe3O4 magnetic nanoparticles were obtained by means of improved chemical co-precipitation method. The average particle size of the product was about 10 nm, the oleic acid content of the product was about 9.7% and the saturation magnetization of the product was 59 emu/g.Then, molecular self-assembly and in-situ polymerization were combined to . synthesize carboxyl groups functionalized Fe3O4 core/shell nanoparticles. Considering all the factors which affected the process of self-assembly and polymerization, the optimum experiment conditions were found. The reaction medium was distilled water, the reaction temperature was 80 ℃, the mass ratio of initiator and monomer was 1:5, and the reaction time for self-assembly process and polymerization were 3hr and 2hr, respectively.Finally, the mass ratio of monomer and magnetic nanoparticles during the process of self-assembly was discussed. Results showed that when the mass ratio of monomer and magnetic nanoparticles was 1:4, the carboxyl groups functionalized Fe3O4 core/shell nanoparticles exhibited excellent properties. The polymer content of the product was about 15.3%, the thickness of the polymer shell was about 2.5 nm, the saturation magnetization was 31.8 emu/g and the content of carboxyl groups on the surface of functionalized nanoparticles was 1.071 mmol/g.