Chemical synthesis of magnetic nanoparticles
The comparison between the PXRD patterns of talc and the prepared Fe3O4/talc nanocomposites under the chemical reduction route fell in the small-angle range of 2θ (9.35–9.50), which indicated the immobilized formation of Fe3O4 nanoparticles on the external surface of the talc layers. The TEM images and size distribution of talc/Fe3O4 nanocomposites showed that the mean diameter of the nanoparticles ranged from about 1.2–3.2 nm. Additionally, the SEM images indicated that there were no structural changes between the initial talc and talc/Fe3O4 nanocomposites. Furthermore, FT-IR spectra showed that there was no chemical interaction between the silicate layers and Fe3O4 nanoparticles in talc/Fe3O4 nanocomposites. The synthesized talc suspensions containing Fe3O4 nanoparticles were found to be unstable over a long period of time, displaying signs of precipitation.
Chemical Synthesis of Monodisperse Magnetic ..
Another avenue for magnetic nanoparticles is the development of magnetically recoverable catalysts. In this case, magnetic nanoparticles can be synthesized in the presence of functional capping molecules such as polyphenylenepyridyl dendrons or thermally stable polymers (collaboration with Dr. Zinaida Shifrina's group from A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, Moscow, Russia) bearing functional groups. Such dendrons/polymer shells can stabilize catalytic species on top of magnetic nanoparticles, and allow for easy magnetic separation. The graphic below shows the STEM EDS map and a schematic representation of Zn-containing magnetic oxide nanoparticle stabilized by polyphenylquinoxaline. The catalytic testing in syngas conversion to methanol demonstrated outstanding catalytic properties of Zn-containing magnetic oxides, whose activities are dependent on the Zn loading. Repeat experiments carried out with the best catalyst after magnetic separation showed remarkable catalyst stability even after five consecutive catalytic runs.
We synthesize monodisperse magnetic nanoparticles of different shapes, sizes and composition via organometallic routes. The proper functionalization can make these particles hydrophobic or hydrophilic and can determine the interaction forces between the particles. As major means of functionalization we use hydrophobic interactions of the nanoparticle protective layer with functionalized lipids or amphiphilic copolymers, covalent interaction of the particle surface with functional silanes, or ligand exchange. The negatively charged water soluble nanoparticles (left, below) can be additionally coated with virus protein forming virus-like nanoparticles (VNPs, right, below).