Incorporation Of Fe3O4 Nanoparticles Research Articles

Magnetochromatic Polydiacetylene by Incorporation of Fe3O4 Nanoparticles

Magnetochromatic Polydiacetylene by Incorporation of Fe₃O₄ Nanoparticles

Polymide/Fe<SUB>3</SUB>O<SUB>4</SUB>-carbonized Membranes for Gas Separation

Novel functional carbon membranes for gas separation were designed and prepared by incorporating Fe3O4 nanoparticles into carbon membranes precursor polyimide. The as-synthesized membranes were characterized by TEM, XRD and VSM. The effects of Fe3O4 addition and the final pyrolysis temperature on the gas permeability were investigated. The results show that Fe3O4 nanoparticles transformed into other phase morphologies are helpful to form the graphite-like layers during the pyrolysis process, which make the membrane with two types of carbon structure : amorphous carbon and graphite-like layers. All the functional carbon membranes exhibit magnetism. Single gas permeation test results show that the as-synthesized membranes exhibit an outstanding molecular sieving capability together with high gas permeability. The gas permeability of H-2 is 61 times higher than the pure carbon membrane and the H-2/CO2 selectivity is also improved. Fe3O4 addition and the final pyrolysis temperature siginificantly impair the gas permeability. When the Fe3O4 content is 20wt%, the permeabilities of pure gas H-2, CO2, O-2, N-2, CH4 in the functional carbon membrane are 15476, 4385, 1565, 193 and 114 Barrers (1Barrer = 1 x 10(-10) cm(3) (STP) . cm/(cm(2) . s . cmHg)), respecticvely. The final pyrolysis temperature also has a remarkable effect on the gas separation performance.

Preparation of composite particles with magnetic silica core and fluorescent polymer shell

Dual functions of magnetic and fluorescent properties were created in composite particles that incorporated magnetite (Fe3O4) nanoparticles in particle cores of silica and fluorescent pyrene in particle shells of polystyrene. The Fe3O4 nanoparticles were prepared with a conventional homogeneous precipitation method and surface modified with a coupling agent of carboxyethylsilanetriol. The silica particles incorporating Fe3O4 nanoparticles were synthesized with a modified Stober method in which the Fe3O4 nanoparticles were added to a system of tetraethylorthosilicate (TEOS)/ammonia/water/ethanol. Then, the magnetite/silica composite particles were coated with the pyrene/polystyrene shell in a soap-free emulsion polymerization, which was conducted in the presence of pyrene in a mixed solvent of water/ethanol. The composite particles prepared in the mixed solvent had both magnetic and fluorescent properties. The fluorescent spectrum of the particles with Fe3O4 was very similar to that without Fe3O4, indicating that the magnetic component within the core particles scarcely interfered with the fluorescent emission from the polymer shell.

Cation Exchange: A Simple and Versatile Route to Inorganic Colloidal Spheres with the Same Size but Different Compositions and Properties

This paper describes a cation exchange approach to the synthesis of metal chalcogenide core-shell particles with the same size but a number of different compositions. This method begins with the preparation of colloidal spheres of amorphous Se (a-Se), followed by their reaction with Ag atoms to form Se@Ag2Se spheres. These core-shell spheres are then converted into Se@MSe (M = Zn, Cd, and Pb) via cation exchange with Zn2+, Cd2+, and Pb2+. All the colloidal spheres prepared using this method are monodispersed in size and characterized by a spherical shape and a smooth surface. Starting from the same batch of Se@Ag2Se, the resultant Se@MSe samples were essentially the same in size. Furthermore, these core-shell colloidal spheres can be easily made superparamagnetic by incorporating Fe3O4 nanoparticles into the a-Se cores. This synthetic approach provides a simple and versatile route to magnetoactive core-shell spheres with the same size but a range of different compositions. This study also implies that it is feasible to further increase the diversity of cations that can be used in the cation exchange of a colloidal system to produce multifunctional core-shell spheres with a variety of properties.