title: Toward designer magnetite/polystyrene colloidal composite microspheres with controllable nanostructures and desirable surface functionalities.
abstract: An effective method was developed for synthesizing magnetite/polymer colloidal composite microspheres with controllable variations in size and shape of the nanostructures and desirable interfacial chemical functionalities, using surfactant-free seeded emulsion polymerization with magnetite (Fe(3)O(4)) colloidal nanocrystal clusters (CNCs) as the seed, styrene (St) as the monomer, and potassium persulfate (KPS) as the initiator. The sub-micrometer-sized citrate-acid-stabilized Fe(3)O(4) CNCs were first obtained via ethylene glycol (EG)-mediated solvothermal synthesis, followed by 3-(trimethoxysilyl)propyl methacrylate (MPS) modification to immobilize the active vinyl groups onto the surfaces, and then the hydrophobic St monomers were polymerized at the interfaces to form the polymer shells by seeded emulsion radical polymerization. The morphology of the composite microspheres could be controlled from raspberry- and flower-like shapes, to eccentric structures by simply adjusting the feeding weight ratio of the seed to the monomer (Fe(3)O(4)/St) and varying the amount of cross-linker divinyl benzene (DVB). The morphological transition was rationalized by considering the viscosity of monomer-swollen polymer matrix and interfacial tension between the seeds and polymer matrix. Functional groups, such as carboxyl, hydroxyl, and epoxy, can be facilely introduced onto the composite microspheres through copolymerization of St with other functional monomers. The resultant microspheres displayed a high saturation magnetization (46 emu/g), well-defined core-shell nanostructures, and surface chemical functionalities, as well as a sustained colloidal stability, promising for further biomedical applications.
authors.affiliation: State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, People's Republic of China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Xu
authors.forename: Wan-Fu
authors.initials: WF
authors.lastname: Ma
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: You
authors.forename: Ju-Mei
authors.initials: JM
authors.lastname: Li
authors.forename: Jia
authors.initials: J
authors.lastname: Guo
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Hu
authors.forename: Chang-Chun
authors.initials: CC
authors.lastname: Wang
mesh_terms: D003102:Colloids / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D008863:Microspheres; D049329:Nanostructures / Q000737:chemistry; D017646:Organosilicon Compounds / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry*; D013499:Surface Properties; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D003102:Colloids; D008689:Methacrylates; D017646:Organosilicon Compounds; D011137:Polystyrenes; D014753:Vinyl Compounds; C004985:divinyl benzene; C505504:3-(trimethoxysilyl)propyl methacrylate; D052203:Ferrosoferric Oxide