Polymer Janus Particles Containing Block-Copolymer Stabilized Magnetic Nanoparticles (original) (raw)
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Fabrication of Novel Magnetic Janus Microparticles
MRS Proceedings, 2008
ABSTRACTWe have designed a novel technique for fabrication of magnetic Janus microparticles based on “trapping” the alignment of magnetite nanoparticles dispersed within the oil drops of polymerizable oil-in-water emulsion. We polymerized the oil drops after gelling the continuous aqueous phase in the presence of an external magnetic filed. This allowed us to produce magnetic Janus particles with optical and magnetic anisotropy which form unusual zigzag chains and structures when an external magnetic field is applied to a suspension of such particles. These novel microparticles retain high remanence magnetization and coercivity values indicative of ferromagnetic behavior, which indicates that the composite polymeric Janus microparticles posses a net magnetic dipole and behave like micro-magnets due to the “trapped” orientation of the magnetite nanoparticles in their polymeric matrix.
Anisotropic janus magnetic polymeric nanoparticles prepared via miniemulsion polymerization
Journal of Polymer Science Part A: Polymer Chemistry, 2013
Anisotropic Janus magnetic polymeric nanoparticles are prepared via the miniemulsion polymerization of styrene and acrylic acid monomers in the presence of oleic acid-coated magnetic nanoparticles (MNPs). The controllable phase separation between the polymer matrix and the encapsulated MNPs is a key success factor to produce Janus morphology. The effects of MNPs, 2,2 0-azobis(2-isobutyronitrile) and sodium dodecyl sulfate contents, on the morphology, chemical composition and colloidal stability of the prepared Janus hybrid particles are investigated. Besides the determination of polymerization conversion, zeta potential, size analysis , TGA, and TEM are applied for characterization of the anisotropic particles. The results show the stable spherical Janus particles containing MNPs (15 wt % magnetic content) located on one side of each polymer particle. The anisotropic submicron Janus magnetic polymeric particles (250 nm) can be easily separated by an external magnet. V
ACS applied materials & interfaces, 2014
Recently, anisotropic colloidal polymeric materials including Janus microparticles, which have two distinct aspects on their surfaces or interiors, have garnered much interest due to their anisotropic alignment and rotational orientation with respect to external electric or magnetic fields. Janus microparticles are also good candidates for pigments in "twisting ball type" electronic paper, which is considered promising for next-generation flexible display devices. We demonstrate here a universal strategy to encapsulate inorganic nanoparticles and to introduce different such inorganic nanoparticles into distinct polymer phases in Janus microparticles. TiO2 and Fe2O3 nanoparticles were separately encapsulated in two different mussel-inspired amphiphilic copolymers, and then organic-inorganic composite Janus microparticles were prepared by simple evaporation of solvent from the dispersion containing the polymer and nanoparticle. These Janus microparticles were observed to rot...
Key synthesis of magnetic Janus nanoparticles using a modified facile method
Particuology, 2014
Inorganic/organic poly(methylmethacrylate-acrylic acid-divinylbenzene) iron oxide Janus magnetic nanoparticles (P(MMA-AA-DVB)/Fe 3 O 4 ) with strong magnetic domains and unique surface functionalities were prepared using a solvothermal process. The P(MMA-AA-DVB) nanoparticles were prepared via soapfree emulsion polymerization and used as a precursor for preparing Janus nanoparticles. The morphology and magnetic properties of the magnetic Janus nanoparticles formed were characterized using a laser particle size analyzer, transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and thermogravimetric analysis. The synthesized P(MMA-AA-DVB)/Fe 3 O 4 magnetic Janus nanoparticles were characterized by a Janus structure and possessed a stable asymmetric morphology after being dually functionalized. The particle size, magnetic content, and magnetic domain of the P(MMA-AA-DVB)/Fe 3 O 4 magnetic Janus nanoparticles were 200 nm, 40%, and 25 emu/g, respectively. The formation mechanism of the Janus nanoparticles was also investigated, and the results revealed that the reduction of Fe 3+ ions and growth of Fe 3 O 4 took place on the surface of the P(MMA-AA-DVB) polymeric precursor particles. The size of the Janus particles could be controlled by narrowing the size distribution of the P(MMA-AA-DVB) precursor nanoparticles.
Highly Porous Magnetic Janus Microparticles with Asymmetric Surface Topology
Monodispersed magnetic Janus particles composed of a porous polystyrene portion and a nonporous poly(vinyl acetate) portion with embedded oleic acid-coated magnetic nanoparticles were generated using microfluidic emulsification followed by two distinct phase separation events triggered by solvent evaporation. The template droplets were composed of 2 wt % polystyrene, 2 wt % poly(vinyl acetate), and 0.5−2 wt % n-heptane-based magnetic fluid dissolved in dichloromethane (DCM). The porosity of polystyrene compartments was the result of phase separation between a nonvolatile nonsolvent (nheptane) and a volatile solvent (DCM) within polystyrene-rich phase. The focused ion beam cross-sectioning and scanning electron microscopy (SEM) imaging revealed high surface porosity of polystyrene compartments with negligible porosity of poly(vinyl acetate) parts, which can be exploited to increase the wettability contrast between the two polymers and enhance bubble generation in bubble-driven micromotors. The porosity of the polystyrene portion was controlled by varying the fraction of n-heptane in the dispersed phase. The particle composition was confirmed by scanning electron microscopy−energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The fabricated particles were successfully magnetized when subjected to an external magnetic field, which led to their aggregation into regular 2D assemblies. The particle clusters composed of two to four individual particles could be rotated with a rotating magnetic field. Microfluidic generation of highly porous Janus particles with compositional, topological, and magnetic asymmetry provides a cost-effective, easy-to-implement yet highly robust and versatile strategy for the manufacturing of multifunctional smart particles.
Magnetically uniform and tunable Janus particles
Magnetic particles serve as an important tool for a variety of biomedical applications but often lack uniformity in their magnetic responsiveness. For quantitative analysis studies, magnetic particles should ideally be monodisperse and possess uniform magnetic properties. Here we fabricate magnetically uniform Janus particles with tunable magnetic properties using a spin-coating and thermal evaporation method. The resulting 2 m ferromagnetic particles exhibited a 4% magnetic response variability, and the 10 m ferromagnetic particles exhibited a 1% size variability and an 8% magnetic response variability. Furthermore, by reducing the film thickness, the particle behavior was tuned from ferromagnetic to superparamagnetic.
Magnetic polymer particles: Synthesis and properties
Russian Journal of General Chemistry, 2007
A possibility of preparation of monodisperse magnetic polymer particles containing carboxylic groups by the methid of emulsion (co)polymerization in the presence of a magnetic liquidis considered. Angulation of the magnetite nanoparticles by polymeric spheres of styrene3acroleine copolymer followed by incapsulation to the polystyrene coat is studied. Monodisperse particles with inclusion of the magnetite nanoparticles 30 nm to 1 mm size containing up to 5.6 mmol g !1 surface carboxylic groups are obtained, their electrosurface and magnetic properties are studied.
Magnetic Janus Particles for Static and Dynamic (Bio)Sensing
Magnetochemistry
Magnetic Janus particles bring together the ability of Janus particles to perform two different functions at the same time in a single particle with magnetic properties enabling their remote manipulation, which allows headed movement and orientation. This article reviews the preparation procedures and applications in the (bio)sensing field of static and self-propelled magnetic Janus particles. The main progress in the fabrication procedures and the applicability of these particles are critically discussed, also giving some clues on challenges to be dealt with and future prospects. The promising characteristics of magnetic Janus particles in the (bio)sensing field, providing increased kinetics and sensitivity and decreased times of analysis derived from the use of external magnetic fields in their manipulation, allows foreseeing their great and exciting potential in the medical and environmental remediation fields.
Interfacial and Demulsification Properties of Janus Type Magnetic Nanoparticles
Water-in-oil emulsions are formed during crude oil production. Some natural surfactants (asphaltenes) aggregates are known to form viscoelastic film preventing coalescence of emulsified water droplets. The present research work investigates the interfacial properties and demulsifying capacity of Janus type magnetic nanoparticles. poly(methylmethacrylate-acrylicaciddivinylbenzene) iron oxide Janus nanoparticles with Interfacially active P(MMA-AA-DVB) block copolymer and iron oxide (magnetic) shows excellent interfacial and magnetic properties. Experiments performed at the oil-water interface indicates that Janus particles adsorb at the oil - water interface and separate the emulsified water from the external magnetic field. The external magnetic play important role demulsification of magnetically tagged emulsified water droplets, producing smaller volumes of sludge and decrease the hydrocarbon loss to waste aqueous phase. The chemical bonding of interfacially active P(MMA-AA-DVB) grafted with magnetic nanoparticles and the magnetic property of P(MMA-AA-DVB)/Fe3O4 allowed the used Janus nanoparticles to be readily recycled by magnetic separation and regenerated by solvent washing.