title: Fabrication of tunable Janus microspheres with dual anisotropy of porosity and magnetism.
abstract: This work presents a facile approach to produce a novel type of Janus microspheres with dual anisotropy of porosity and magnetism based on Pickering-type double emulsion templates. A stable aqueous Fe3O4 dispersion-in-oil-in-water (WF/O/W) double Pickering emulsion is first generated by using hydrophobic silica and hydrophilic mesoporous silica particles as stabilizers. Janus microspheres with multihollow structure possessing magnetite nanoparticles concentrated on one side of the microspheres are obtained after polymerization of the middle oil phase of the double emulsion under a magnetic field. The resultant Janus microspheres are characterized by optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX). Moreover, we have systematically investigated the influences of Fe3O4 particle concentration, hydrophobic silica particle content, and volume ratio of the inner water phase to middle oil phase (WF/O) on the double emulsion formation and consequently on the structure of the resulting Janus microspheres. Our results show that the distribution of the multihollow structures within the prepared microspheres can be accurately tailored by adjusting the ratio of WF/O. In addition, the obtained Janus microsphere can be fairly orientated under a magnetic field, making them a potential candidate for synthesizing Janus membrane.
authors.affiliation: Research Institute of Materials Science, South China University of Technology, Guangzhou 510641, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Ning
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Wang
authors.forename: To
authors.initials: T
authors.lastname: Ngai
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tong
mesh_terms: D016880:Anisotropy; D005290:Ferric Compounds / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D060526:Magnetic Fields; D008863:Microspheres; D009821:Oils / Q000737:chemistry; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D009821:Oils; D014867:Water; C000499:ferric oxide; D012822:Silicon Dioxide