The Surface Modification And The Mechanism Of Monodisperse Nanoparticles

One of the research focuses in nanoscience field is to develop novel controlled synthesis routes for monodisperse inorganic nanoparticles, subsequent surface modification and tailered treatment to their sizes, morphologies and dispersion behaviours. In this dissertation, systematic explorations were carried out on monodisperse Fe3O4 and Ag nanoparticles. Herein, monodisperse Fe3O4 and Ag nanoparticles were synthesized firstly and then modified with inorganic and organic species respectively. The formation mechanism, sizes, morphologies and dispersion behaviors have been studied in detail.Hexagonal and triangular monodisperse Fe3O4 nanosheets have been synthesized via a two-step microemulsion solvothermal approach. Hydrophobic Fe3O4 nanocrystals could be dispersed into microemulsion and grew into anisotropic Fe3O4 nanocrystals when Fe2+ ions were introduced followed by solvothermal process. Hexagonal and triangular Fe3O4 nanosheets can be obtained through adjusting the experimental parameters. Formation mechanism was discussed detailed and nucleation of nanocrystals and consequent growth features were studied. It has been proven that it is crystal defects that affected the growth habits and determined final morphologies. HRTEM results can be deemed as powerful evidence to explain the shape of hexagonal and triangular nanosheets of face-centered cubic Fe3O4.A simple reaction of carboxyl with rare metals ions without any solvent, surfactant and initiator could generate free radical, which initiated the polymerization of double bond of OA. Based on this, one-pot two-step method was developed to prepared Ag/POA and Ag/poly undecylenic acid nanocomposite. During the process, OA served as reducing agent, surfactant, polymerization monomers. POA chains circumvoluted each other to form microspheres and micro-plates including monodisperse Ag nanoparticles, according to different experimental conditions. Considering the characteristics of the weak interaction of linear polymer, this material could transform into two-dimensional slices of nanocomposite structure. This synthetic method could be extended to fabricate hybrid nanomaterials consists of rare metals salts and unsaturated fatty acids. Through changing the chain length, the type of functional groups of fatty acid, the dispersion properties of inorganic/polymer nanomaterials will be different which may have potential application in the various research fields such as catalysis and optics.