37 results about "Ferromagnetic nanoparticles" patented technology

A magnetic nanoparticle (22), a magnetic nanomaterial (30), assembly (30), and a method for synthsising a magnetic nanoparticle, relating to thermodynamically stable and air stable ferromagnetic nanoparticles of adjustable aspect ratio made upon decomposition of organometallic precursors in solution in the presence of a reaction gas and a mixture of organic ligands. The magnetic nanomaterial comprises magnetic nanoparticles of homogeneous size, shape, and magnetic orientation that comprises a magnetic core (24, 34) ferromagnetic at room temerature and/or operating temperatures, and a non-magnetic matrix (26, 36) encapsulating the magnetic core. This magenetic nanomaterial could be used in high frequency integrated circuit applications, such as used in wireless portable electronic devices, to enchance magnetic field confienment and improve passive component performance at MHz and GHz frequency in a variety of passive and active devices, such as transformers, on-chip signal isolation, inductors, and the like.

Provided is a method of inhibiting magnetically induced aggregation of ferrimagnetic and/or ferromagnetic nanoparticles by encapsulating the nanoparticles in a silica shell. The method entails coating magnetic nanoparticle surfaces with a polyacid polymer to form polymer-coated magnetic nanoparticles and treating the polymer-coated magnetic nanoparticles with a silica precursor to form uniform silica-coated magnetic nanoparticles. By controlling the thickness of the silica encapsulating the nanoparticles, the inherent magnetically induced aggregation of the nanoparticles can be completely inhibited.

A magnetic recording medium for high-density recording, having a doped interlayer to preserve the uniformity and ordering of the magnetic nanoparticles in its recording layer. The interlayer is doped with a high electronegativity material. The dopant atoms in the interlayer interact with the ferromagnetic nanoparticles to promote the formation of a homogeneous, ordered monolayer of nanoparticles in the recording layer. In addition, the high electronegative property of the dopant atoms holds the nanoparticles in place during the subsequent annealing process to prevent sintering and disordering damage. In one embodiment, the dopant is a halogen or non-halogen material having a high electronegativity, which is not polymerized to the matrix material in the interlayer. The matrix material may be polymerized. An example of a doped interlayer is a fluorinated carbon film.

The present invention relates to a water-soluble polymer complex that includes a water-soluble block copolymer and a magnetic nanoparticle, wherein the water-soluble polymer complex has a nonzero net magnetic moment in the absence of an applied magnetic field at ambient temperatures. The water-soluble block copolymer is preferably a diblock or triblock copolymer and the magnetic nanoparticle is preferably a ferrimagnetic or ferromagnetic nanoparticle. The water-soluble complexes may be derivatized with reactive groups and conjugated to biomolecules. Exemplary water-soluble polymer complexes covered under the scope of the invention include PEG₁₁₂-b-PAA₄₀ modified CoFe₂O₄; NH₂-PEG₁₁₂-b-PAA₄₀ modified CoFe₂O₄; PNIPAM₆₈-b-PAA₂₈ modified CoFe₂O₄; and mPEG-b-PCL-b-PAA modified CoFe₂O₄.

Ferromagnetic nanoparticles which are produced by reducing, in the presence of a polymer, two or more metals having different reduction potentials twice or more, using two or more reducing agents having different reduction potentials, a material coated with a dispersion of ferromagnetic nanoparticles in which the ferromagnetic nanoparticles are dispersed, and a magnetic recording medium which has a magnetic layer consisting of the material. The ferromagnetic nanoparticles having a holding power Hc of 95.5 kA/m or more, the material coated with the dispersion of ferromagnetic nanoparticles having excellent industrial coatability, and the magnetic recording medium using the dispersion are provided.

The invention belongs to the technical field of environmental pollution research and environmental protection technology, and in particular relates to a ferromagnetic nanoparticle and preparation thereof and an application in removal of micro-plastics in the environment based on the nanoparticle. The surface of an iron nanoparticle is modified with methoxysilane to form siloxane bonds (-Si-O-Si-), and alkyl chains face outward to form a hydrophobic iron nanoparticle. The ferromagnetic nanomaterial is applied to extract and remove micro-plastics in an environmental sample. The method has wide adaptability, reliable method, simple operation and relatively low cost, can be used for extracting and identifying micro-plastics in environmental pollution (water, soil, sediment) researches, can be used for removing micro-plastics in environmental water body, sewage, and drinking water, provides a new solution for the micro-plastic environmental pollution field research and the environmental management, and is suitable for further development and application.

The invention discloses a novel magnetic sealing material, which is formed by nucleus-shell-grafting group particles. The nucleus is ferromagnetic nanoparticles with the particle size being 5 to 100nm; the shell is an inert metal oxide layer or a resin layer covering the surface of the nucleus; hydroxide radical, carboxyl, amidogen or hydrosulphonyl on the shell can be chemically grafted with groups; the thickness of the shell is 1 to 100nm; the grafting group is a fluorocarbon chain grafted on the inert metal oxide layer or the resin layer; the cover degree of the fluorocarbon chain on the shell surface is 5 to 95 percent. The invention provides the novel magnetic sealing material used as magnetic particles in magnetic fluid, so that the magnetic particles can be directly, stably and uniformly dispersed into carrier liquid, and cannot be settled or agglomerated, and the magnetic sealing effect of the magnetic fluid is better.

The invention discloses a method for preparing magnetic nanoparticles with improved quality. The method comprises the following steps: weighing a soluble trivalent iron salt and sodium acetate to be dissolved in ethylene glycol so as to obtain yellow transparent liquid; adding trisodium citrate, a polyvinylpyrrolidone dispersing agent and an alkaline additive, and mechanically stirring at a room temperature; and adding the obtained mixed liquid into a reactor to be reacted, naturally cooling the product, washing with ethanol and water, and performing vacuum drying, thereby obtaining the magnetic nanoparticles. According to the method for preparing magnetic nanoparticles disclosed by the invention, ferroferric oxide magnetic nanoparticles are synthesized by a solvothermal method, synthesisis completed at a time under high temperature and high pressure, later crystallization treatment is not needed, the obtained powder is narrow in particle size distribution and pure in components, andanhydrous sodium acetate with excellent electrostatic stability is selected as the alkaline additive, so that agglomeration of the magnetic nanoparticles is effectively avoided. Therefore, the prepared ferroferric oxide magnetic nanoparticles are excellent in stability and have excellent monodispersity, superparamagnetism and particle size uniformity in water.

The invention relates to a ferromagnetic resonance temperature measurement method based on a field sweeping method. The method comprises the following steps: applying a static magnetic field to a measured object containing ferromagnetic nanoparticles to saturate and magnetize the ferromagnetic nanoparticles; applying an alternating pulse excitation magnetic field along the vertical direction of the static magnetic field; determining the magnetic field intensity of the static magnetic field through a field sweeping method when the ferromagnetic nanoparticles generate ferromagnetic resonance; and calculating the temperature of the measured object according to the determined magnetic field intensity of the static magnetic field. According to the method provided by the invention, temperature measurement is carried out through the established relation model of the magnetic field intensity of the external static magnetic field and the temperature, the model is simple in form, the measurement method is simple and convenient, the internal temperature of the measured object can be rapidly and simply measured, and the measurement accuracy is very high.

The invention discloses a magnetic photonic crystal microsphere for enriching and separating aflatoxin B1 as well as a preparation method and application of the magnetic photonic crystal microsphere. The microsphere is a core-shell type surface molecular imprinting magnetic inverse opal photonic crystal microsphere, wherein the core is a photonic crystal microsphere which is of a magnetic inverse opal structure and is formed by silicon dioxide nanoparticles, polystyrene nanoparticles and ferroferric oxide magnetic nanoparticles through self-assembly and high-temperature firing, and the shell is a molecular imprinting layer which is modified through a molecular imprinting technology and can specifically recognize aflatoxin B1. The prepared core-shell type surface molecular imprinting magnetic inverse opal photonic crystal microsphere can selectively extract aflatoxin B1 in a sample, and compared with a biological antibody modified material, the stability of the material can be greatly improved, and the preparation cost of the material is reduced.

The invention discloses a polylactic acid shell of an electric energy metering box and a preparation method of the polylactic acid shell. The preparation method comprises the following steps: mixing the phase change material, the high-molecular surfactant and an alcohol-water mixed solution in a reaction container; starting a temperature control system to heat the reaction system to 30-100 DEG C under the condition of inert gas protective atmosphere; after the temperature of the reaction system is stable, adding a styrene monomer and an initiator, mixing and stirring at the stirring speed of 200-400r/min; when the reaction is carried out for 11-13 hours, ferromagnetic nanoparticles modified by a high-molecular surfactant are added, and the reaction is continued for 2-4 hours to obtain a phase change microcapsule; the preparation method comprises the following steps: putting polylactic acid into a dryer, and carrying out drying treatment at 55-65 DEG C for 22-26 hours to remove moisture; premixing polylactic acid and the phase change microcapsules, and performing melt extrusion and granulation through a double-screw extruder; and carrying out injection molding on the blended particles through an injection molding machine. Development of electrical branches can be effectively inhibited, the electrical aging process of the material is delayed, the service life of the material is prolonged, and the use safety is improved.

The invention provides a magnetofluid enhanced electromagnetic heating device and method for preventing and treating secondary hydrate around a well. At present, in the process of exploiting natural gas hydrates through a depressurization method, secondary hydrates or ice can be formed due to the fact that the temperature around a well is too low, a gas migration channel in sediment is blocked, and the gas production rate is affected. According to the device or method, a coil is arranged outside a shaft sleeve, and the coil generates a specific-frequency electromagnetic field radiated to stratum sediments. Under the action of the electromagnetic field, magnetite nano-particles naturally contained in the stratum sediment generate oscillating motion, and the aim of heating the stratum around the well is achieved due to heat generated by friction. In addition, in the hydraulic fracturing or slotting stage of the reservoir, the magnetofluid containing the ferromagnetic nanoparticles can be injected along with fracturing fluid, so that the magnetothermal effect of sediments is increased, and the heating effect is further enhanced. In this way, secondary hydrate or ice can be prevented from being formed around the well, pore channels in the sediment are kept unblocked, and therefore the exploitation efficiency of the natural gas hydrate is improved.