title: Multi-functional thermosensitive composite microspheres with high magnetic susceptibility based on magnetite colloidal nanoparticle clusters.
abstract: Monodisperse organic/inorganic composite microspheres with well-defined structure were prepared through the encapsulation of silica coated superparamagnetic magnetite colloidal nanoparticle clusters (CNCs) with cross-linked poly(N-isopropylacrylamide) (PNIPAM) shell. At first, the sub-micrometer-sized CNCs were fabricated by the solvothermal process, and then a silica layer was coated on the surface of CNCs through a sol-gel process, and finally, a thermoresponsive shell of PNIPAM was deposited onto the surface of the core/shell magnetic microspheres by a precipitation polymerization. The experimental results showed that the size of Fe(3)O(4) core, the thickness of SiO(2) shell, as well as volume phase transition temperature (VPTT) of PNIPAM shell could be well controlled, and this structured modulation could satisfy different requirements. The superparamagnetic behavior, high magnetization (the saturation magnetization of Fe(3)O(4)/SiO(2)/PNIPAM microspheres with a 10% cross-linking density is 41.6 emu/g), and good thermosensitivity make these composite microspheres an ideal candidate for various important applications such as in controlled drug delivery, bioseparation, and catalysis.
authors.affiliation: Key Laboratory of Molecular Engineering of Polymers (Minister of Education), Department of Macromolecular Science, Fudan University, Shanghai 200433, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Luo
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Song
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Ao
authors.initials: A
authors.lastname: Xia
authors.forename: Wu-Li
authors.initials: WL
authors.lastname: Yang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Hu
authors.forename: Chang-Chun
authors.initials: CC
authors.lastname: Wang