title: A simple approach to the synthesis of hollow microspheres with magnetite/silica hybrid walls.
abstract: In this paper, we report a simple approach for templating synthesis of magnetic hollow composite microspheres with magnetite/silica walls. This approach is based on the co-sedimentation of polymer microspheres and magnetic colloids followed by impregnation with silica oligomer from tetraethyl orthosilicate and the further removal of the polymer microspheres by pyrolysis. The diameter of the hollow microspheres can be adjusted in range of 300 nm-2.0 microm by using polymer microspheres of different sizes and the wall thickness is tunable from 10-50 nm by controlling ratio of magnetite to the polymer microspheres. Magnetic characterizations show that the hollow microspheres have superparamagnetism with magnetization saturation of 10-30 emu/g. HRTEM and N(2) adsorption-desorption isotherms reveal that the hollow microspheres have numerous nanopores in the walls with a broad distribution in the range of 2 to 80 nm, which results in a high BET surface (67.6 m(2)/g) and pores volume (0.14 cm(3)/g).
authors.affiliation: Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Advanced Materials Laboratory, Fudan University, Shanghai 200433, PR China.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Deng
authors.forename: Chong
authors.initials: C
authors.lastname: Liu
authors.forename: Zhenkun
authors.initials: Z
authors.lastname: Sun
authors.forename: Dongyuan
authors.initials: D
authors.lastname: Zhao
mesh_terms: D052203:Ferrosoferric Oxide / Q000737:chemistry*; D008280:Magnetics; D008567:Membranes, Artificial; D008863:Microspheres; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; D012822:Silicon Dioxide; D052203:Ferrosoferric Oxide