Surface Polymer Modification And Fuctionalization Of Magnetic Nanoparticles

Fe3O4 magnetic nanoparticles (Fe3O4MNPs) have significant surface effect, small size effect, high saturation magnetization value and superparamagnetism. Co-precipitation technique is a facile, convenient and promising way to synthesize Fe3O4MNPs, but the Fe3O4MNPs synthesized by co-precipitation technique tend to agglomerate easily. It would be of great theoretical and practical values in industrial and biological applications to enhance the dispersion, biocompatibility and absorption capacity of Fe3O4MNPs through the surface modification using by organic polymer. In this dissertation, we described detailedly the synthesis of Fe3O4MNPs, the copolymerization of the acrylamide and acrylic acid, the surface modification of Fe3O4MNPs using by coupling agent and polymer, the assembly of Fe3O4MNPs in the surface of carbon nanotubes and in the polymer chains, and the structure and properties of prepared materials. Here are the achievements:1. The superparamagnetic Fe3O4MNPs with high saturation magnetization value (54.7emu/g) can be synthesized by co-precipitation technique. X-ray diffraction data show that the Fe3O4MNPs have inverse spinel structure and a single Fe3O4MNP size is 17nm by. Fe3O4MNPs were attached with-NH2 groups via covalently grafted with aγ-aminopropyltriethoxysilane. Fe3O4MNPs attached with-NH2 (Fe3O4-NH2) exhibit excellent superparamagnetism, high saturation magnetization value (51.9emu/g) and good dispersion effect in water. When Fe3O4-NH2 was electrostaticlly assembled with carboxylic carbon nanotubes, the superparamagnetic carbon nanotubes (MCNT) with 40emu/g saturation magnetization value were prepared. The adsorption of MCNT on pharmorubicin is up to 520% and the release efficiency is 91% when the pH value is 3.6, which means that MCNT display the characteristics of the targeted drug delivery, controllable adsorption and controllable release on the anticancer drug pharmorubicin.2. The copolymer of the acrylamide and acrylic acid (P(AM-co-AA)) contains abundant-COOH groups and-CONH2 groups, and exhibits good heat resistance, high intrinsic viscosity and excellent water solubility. Fe3O4MNPs could be modified with P(AM-co-AA) chain via covalently grafted with-COOH of P(AM-co-AA) and-OH in Fe3O4MNPs surface. Fe3O4MNPs modified with wt 8% P(AM-co-AA) show good thermal stability, high saturation magnetization value (51.8emu/g), outstanding superparamagnetism and excellent dispersion effect in water and ethanol. The modified Fe3O4MNPs could be separated quickly and efficiently from water and ethanol through the external magnetic field.3. The structure and function groups between synthesized P(AM-co-AA) and natural macromolecule gelatin are similar. The molecular structure of the P(AM-co-AA) are controllable, and the ratio of the amino and the carboxyl in the polymer chain can be adjusted, which enable them adapt the application environment more widely. The Fe3O4MNPs could be induced to assembled with P(AM-co-AA) or gelatin through in situ synthesis and high temperature reaction technique. Transmission electron microscopy images reveal that the assembled Fe3O4MNPs present more regular structure. The assembled Fe3O4MNPs show good thermal stability, high saturation magnetization value, outstanding superparamagnetism, excellent dispersion effect in water and ethanol and quick separation action from water and ethanol through the external magnetic field.