Ionic Liquid Assisted Synthesis Of Magnetic Nanomaterials

One of the urgent problems in chemistry and chemical industry is looking for environment-friendly and favoring for reaction controlling solvents. Room temperature ionic liquids (RTILs), owing to their negligible vapor pressure, low melting points, wide range of liquidus temperatures (up to 400℃), low toxicity, large electrochemical window, and good solvents for many organic and inorganic materials, are widely applied in fields of organic chemical syntheses, separations, electro-chemistry, and so on. Now, the use of RTILs in nanomaterials synthesis is still in infancy, but their excellences compared to traditional solvents have caught much attention of chemical researchers. This thesis is focused on RTIL assisted synthesis of magnetic nanomaterials. We systemically studied the influence of RTIL on the micro-morphologies of the products and simply explored the synthesis of carbon-based magnetic nanocomposites with the assistance of RTIL and microwave.1. Hierarchical porous nickel nanostructures were prepared in RTIL 1-butyl -3-methylimidazolium bromide using hydrazine as reducing agent without any seed or template. The Ni microwires and hollow microspheres can be synthesized by modifying the reaction conditions. The products were characterized by means of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results indicated that the products are Ni microwires with length up to 35-75μm and average diameter of～600 nm or Ni hollow microspheres with that of～400 nm. The magnetic properties of typical products were measured by a vibrating sample magnetometer (VSM). The influences of reaction time, concentrations of reactants, and the possible formation mechanism were investigated. The RTIL is important for the formation of Ni microwires.2. Monodisperse porous ferrite nanoparticles in size of 40 nm were prepared in ionic liquid 1-butyl-3-methylimidazolium bromide, which were characterized by means of XRD, TEM, and high-resolution transmission electron microscopy (HRTEM). The magnetic properties of as-obtained products were measured by a vibrating sample magnetometer. The influences of reaction medium and reaction time were studied, and indicated that RTIL is important for the formation of porous structures. These will accumulate data for the application of these ferrite nanoparticles in the fields of catalyst carrier and biomedicine.3. NiFe₂O₄/C and CoFe₂O₄/C nanocomposites were synthesized in the mixture of RTIL and ethanol via a microwave-assisted method. RTIL provided a favorable condition for the adsorption of micro-wave, and maybe also acted as carbon source. This route is significant for developing the methods for preparation of functional composite materials and exploiting their application. However, using this route to monodisperse carbon-coated magnetic nanostructures relies on further study.