CN107446546B - Novel magnetic sealing material and preparation method thereof - Google Patents

Novel magnetic sealing material and preparation method thereof Download PDF

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Publication number
CN107446546B
CN107446546B CN201710778089.8A CN201710778089A CN107446546B CN 107446546 B CN107446546 B CN 107446546B CN 201710778089 A CN201710778089 A CN 201710778089A CN 107446546 B CN107446546 B CN 107446546B
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magnetic
nanoparticles
ferromagnetic
particles
sealing material
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CN107446546A (en
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邹伟
陈炯
颜杰
李嘉
杨虎
朱胜兰
苏桂萍
何冬梅
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Zhonghao Chenguang Research Institute of Chemical Industry Co Ltd
Sichuan University of Science and Engineering
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Zhonghao Chenguang Research Institute of Chemical Industry Co Ltd
Sichuan University of Science and Engineering
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/44—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids
    • H01F1/445—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids the magnetic component being a compound, e.g. Fe3O4
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K2003/1034—Materials or components characterised by specific properties

Abstract

The invention discloses a novel magnetic sealing material, which is composed of core-shell-grafting group particles; the core is ferromagnetic nano-particles, and the particle size of the ferromagnetic nano-particles is 5-100 nm; the shell is an inert metal oxide layer or a resin layer coated on the surface of the core; and the hydroxyl, carboxyl, amino or sulfhydryl groups on the shell can be chemically grafted with groups; the thickness of the shell is 1-100 nm; the grafting group is a fluorocarbon chain grafted on the inert metal oxide layer or the resin layer, and the coverage of the fluorocarbon chain on the surface of the shell is 5-95%. The invention provides a novel magnetic sealing material as magnetic particles in a magnetic fluid, so that the magnetic particles can be directly, stably and uniformly dispersed in a carrier liquid, the problems of sedimentation and agglomeration of the magnetic particles can be avoided, and the magnetic sealing effect of the magnetic fluid is better.

Description

Novel magnetic sealing material and preparation method thereof
Technical Field
The invention belongs to a magnetic sealing material, and particularly relates to a novel magnetic sealing material and a preparation method thereof.
Background
The magnetic sealing is a novel sealing technology, and the magnetic sealing component prepared by the technology can resist high and low temperature, has no abrasion, has excellent working reliability even in the limit vacuum degree of 10-6The leakage rate under Pa is also extremely low. Because of its excellent performance, it is widely used in chemical, mechanical and energy fields. Magnetic fluid in magnetic seal assembly is shadowAnd the key factor of good and bad sealing effect.
The magnetic fluid consists of magnetic particles, carrier liquid and dispersing agent; since the sealing member is required to meet the actual requirements at high temperature and high pressure, the carrier liquid is required to have low viscosity and low saturated vapor pressure, and to have a high boiling point and chemical, i.e., thermal, stability so that the magnetic particles dispersed in the carrier liquid do not agglomerate or precipitate. The fluoroether oil can suspend the magnetic particles without precipitation due to high chemical and thermal stability, no vaporization, low viscosity and high density, and is an ideal magnetic fluid carrier liquid. However, the fluorocarbon chain in the fluoroether oil has the characteristics of hydrophobicity and oleophobicity, namely 'double-phobicity', so that the traditional surfactant is difficult to disperse the magnetic particles into the fluoroether. Although the fluorocarbon surfactant can help disperse the magnetic particles in the fluoroether oil at present, the magnetic fluid stability becomes very poor under a high-temperature environment due to the interaction between the magnetic material and the fluorocarbon surfactant, and finally the phenomenon of agglomeration and sedimentation of the magnetic particles occurs, so that the magnetic sealing component cannot meet the sealing requirement.
Disclosure of Invention
Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows: the novel magnetic sealing material is provided, and the technical problems that the traditional surfactant in the existing magnetic fluid is difficult to disperse magnetic particles into a carrier liquid, the stability of the magnetic fluid becomes extremely poor after the magnetic particles are dispersed into the carrier liquid through the surfactant, the phenomenon of agglomeration and sedimentation of the magnetic particles is caused are solved.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a novel magnetic sealing material, which is composed of core-shell-grafted group fine particles; the core is ferromagnetic nano-particles, and the particle size of the ferromagnetic nano-particles is 5-100 nm; the shell is an inert metal oxide layer or a resin layer coated on the surface of the core; and the hydroxyl, carboxyl, amino or sulfhydryl groups on the shell can be chemically grafted with groups; the thickness of the shell is 1-100 nm; the grafting group is a fluorocarbon chain grafted on the inert metal oxide layer or the resin layer, and the coverage of the fluorocarbon chain on the surface of the shell is 5-95%.
The preparation method of the novel magnetic sealing material of any one of claims 1 to 6 comprises the following steps:
1) preparing ferromagnetic nano particles; fe synthesized by coprecipitation method, solvothermal method, emulsion synthesis method and sol-gel method3O4、γ-Fe2O3Magnetic metal oxide nanoparticles; or synthesizing to obtain metal oxide nanoparticles of iron, cobalt and nickel or alloy oxide nanoparticles of cobalt-neodymium, platinum-iron and palladium-iron by a precipitation method, a solvothermal method, an emulsion synthesis method and a sol-gel method, and then performing electrochemical, hydrogen, carbon monoxide or chemical reduction on the obtained metal oxide nanoparticles of iron, cobalt and nickel or alloy oxide nanoparticles of cobalt-neodymium, platinum-iron and palladium-iron to obtain metal nanoparticles of iron, cobalt and nickel or magnetic alloy nanoparticles of cobalt-neodymium, platinum-iron, palladium-iron and the like;
2) modifying and coating ferromagnetic nano particles; chemically modifying the ferromagnetic nanoparticles obtained in the step 1) to enable the ferromagnetic nanoparticles to be dispersed in water or an organic solvent, then adding one of tetraethyl orthosilicate, tetramethyl orthosilicate, tetraisopropyl titanate, tetrabutyl titanate and aluminum isopropoxide into the ferromagnetic nanoparticles dispersed in the water or the organic solvent, and carrying out stirring reaction to coat an inert metal oxide layer on the surface of the ferromagnetic nanoparticles; adding one or more of vinyltrimethoxysilane, aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, aminopropyltriethoxysilane or 3-mercaptopropyltriethoxysilane in the reaction process of coating the inert metal oxide layer on the ferromagnetic nano-particles to graft hydroxyl, amino or mercapto grafting groups on the inert metal oxide layer or the resin layer of the ferromagnetic nano-particles; or adding one of polymerizable resorcinol, bisphenol A and melamine and one of formaldehyde and furfural into the ferromagnetic nano particles dispersed in water or an organic solvent, and polymerizing on the surfaces of the ferromagnetic nano particles under the action of acid or alkali to form a stable resin layer; or adding methyl acrylate, ethyl acrylate and methacrylic acid into the ferromagnetic nano particles dispersed in water or an organic solvent, heating and stirring for reaction, and realizing the formation of a resin layer on the surface of the ferromagnetic nano particles; hydrolyzing the ferromagnetic nano particles coated with the resin layer to enable the surfaces of the ferromagnetic nano particles to have carboxyl; or epoxy resin and curing agent are selected to coat the ferromagnetic nano particles;
3) adding heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, dodecafluoroheptylpropyltrimethoxysilane and dodecafluoroheptylpropyltriethoxysilane into the ferromagnetic nanoparticles coated with the inert metal oxide layer and the resin layer obtained in the step 2), so that the fluorine-containing carbon chain can be directly linked to the surface of the magnetic particles; or selecting fluorocarbon according to the functional groups on the surface of the ferromagnetic nanoparticles to graft fluorocarbon chains on the surface of the ferromagnetic nanoparticles.
Further, in the step 3), when the surface of the ferromagnetic nanoparticle has an amino group and a hydroxyl group, one of perfluorooctanoic acid, perfluorohexanoic acid chloride, perfluorooctylsulfonyl fluoride and perfluorohexylsulfonyl fluoride, or a mixture of perfluorooctanoic acid or perfluorohexanoic acid and any one of phosphorus pentachloride, phosphorus oxychloride and thionyl chloride is added to the ferromagnetic nanoparticle coated with the inert metal oxide layer and the resin layer.
Further, in the step 3), when the surface of the ferromagnetic nanoparticle has a mercapto group, one or more of perfluorohexylethylene, perfluorooctylethylene, and 14 fluorooctene is added to the ferromagnetic nanoparticle coated with the inert metal oxide layer and the resin layer, and simultaneously, the fluorocarbon chain is grafted on the surface of the ferromagnetic nanoparticle under the irradiation of ultraviolet light.
Further, in the step 3), when the surface of the ferromagnetic nanoparticle has carboxyl, one or more of perfluorooctylamine, perfluorohexylamine, perfluorooctanol and perfluorohexanol is/are added to the ferromagnetic nanoparticle coated with the inert metal oxide layer and the resin layer to react with the carboxyl, so as to graft fluorocarbon chains on the surface of the ferromagnetic nanoparticle.
Compared with the prior art, the invention has the following advantages:
(1) the invention provides a novel magnetic sealing material which is used as magnetic particles in a magnetic fluid, aiming at the defects of the traditional magnetic fluid, so that the magnetic particles can be directly, uniformly and stably dispersed in a carrier liquid to form a stable magnetic fluid, and the problem that the existing magnetic particles cannot be dispersed in the carrier liquid by the existing surfactant is solved.
(2) In the invention, the fluorocarbon chains are grafted after the magnetic nano particles are coated, so that the magnetic nano particles are directly, stably and uniformly dispersed in the carrier liquid; on one hand, the use of fluorocarbon surfactant in the magnetic fluid is avoided, and on the other hand, the problems that the stability of the magnetic fluid becomes extremely poor and the phenomenon of agglomeration and sedimentation of the magnetic particles still occurs after the magnetic nanoparticles are dispersed in the carrier liquid by using the fluorocarbon surfactant are solved, so that the stability of the magnetic fluid is good, the magnetic sealing effect of the magnetic fluid is better, and the use requirements under severe conditions of high temperature, high pressure and the like are met.
Drawings
FIG. 1 is a TEM image of a modified magnetic microparticle;
FIG. 2 is an SEM image of a modified magnetic particle;
FIG. 3 is a hysteresis loop of the magnetic material;
figure 4 XRD pattern of example 4 particles;
FIG. 5 photograph of microparticles in example 3 after centrifugation at 3000 rpm;
FIG. 6 photograph of microparticles in example 5 after centrifugation at 3000 rpm.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
The silicon dioxide coats the ferroferric oxide magnetic nano particles grafted by the perfluorooctanoic acid. 27.8g of ferrous sulfate heptahydrate and 3.99g of ferric chloride were prepared into a 50mL solution, and 200mL of aqueous ammonia solution (100mL of concentrated ammonia and 100mL of deionized water) was added and mechanically stirred at 300rpm for 2 h. Then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the ferroferric oxide magnetic nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain high-purity ferroferric oxide magnetic nanoparticles; dispersing the ferroferric oxide magnetic nanoparticles into a mixed solution formed by 100mL of ethanol and 200mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 30mL of concentrated ammonia water at 50 ℃, adding 20g of tetraethyl orthosilicate after 20min, reacting for 1h, adding 0.5g of aminopropyl trimethoxysilane into the system, keeping the stirring speed and the reaction temperature for 90min, removing and washing the magnetic nanoparticles coated with silicon dioxide by using a magnet, and drying at 110 ℃ for 8 h; and then dispersing the prepared magnetic nanoparticles in 200mL of dichloromethane, adding 1.5g of perfluorooctanoic acid at 40 ℃, stirring at 400rpm for 15min, adding 5mL of thionyl chloride, adding 2.5m of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the prepared magnetic nanoparticles from the system by using a magnet, washing, and drying at 100 ℃ for 8h to obtain the magnetic nanoparticles with the ferroferric oxide particles as cores and capable of being dispersed in fluoroether oil, wherein a transmission electron microscope photo is shown in figure 1, the cores are magnetic particles, the outer layers are inert coating layers, and carbon-fluorine chains soluble in perfluoropolyether are grafted on the surfaces.
Example 2
The silicon dioxide coats the ferroferric oxide magnetic nano particles grafted by the perfluorohexanoic acid. 27.8g of ferrous sulfate heptahydrate and 3.99g of ferric chloride were prepared into a 50mL solution, and 200mL of aqueous ammonia solution (100mL of concentrated ammonia and 100mL of deionized water) was added and mechanically stirred at 300rpm for 2 h. And then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the magnetic ferroferric oxide to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity ferroferric oxide nanoparticles. Dispersing the ferroferric oxide magnetic nanoparticles into a mixed solution formed by 100mL of ethanol and 200mL of deionized water, stirring at the speed of 300rpm for 15min, adding 30mL of strong ammonia water, stirring for 20min, adding 20g of tetraethyl orthosilicate, reacting for 1h, adding 0.5g of aminopropyl trimethoxysilane into the system, keeping the stirring speed and the reaction temperature for 90min, removing and washing the magnetic nanoparticles coated with silicon dioxide by using a magnet, drying at 110 ℃ for 8h, dispersing 200mL of the prepared magnetic nanoparticles into dichloromethane, adding 1.2g of perfluorohexanoic acid at 40 ℃, stirring at the speed of 400rpm for 15min, adding 5mL of thionyl chloride, adding 2.5m of pyridine as an acid binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the magnetic nanoparticles from the system by using the magnet, washing, drying at 100 ℃ for 8h, and (3) obtaining magnetic nanoparticles which take ferroferric oxide particles as cores and can be dispersed in fluoroether oil, wherein a scanning electron microscope of the particles is shown in figure 2, and the magnetic particles in figure 2 are spherical and have the particle size of 5-10 nm.
Example 3
Silicon dioxide coated fluoroether acid grafted ferroferric oxide magnetic nanoparticles. 27.8g of ferrous sulfate heptahydrate and 3.99g of ferric chloride were prepared into a 50mL solution, and 200mL of aqueous ammonia solution (100mL of concentrated ammonia and 100mL of deionized water) was added and mechanically stirred at 300rpm for 2 h. And then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the magnetic ferroferric oxide to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity ferroferric oxide magnetic nanoparticles. Dispersing the ferroferric oxide magnetic nanoparticles into a mixed solution formed by 100mL of ethanol and 200mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 30mL of concentrated ammonia water, adding 20g of tetraethyl orthosilicate after 20min, reacting for 1h, adding 0.5g of aminopropyl trimethoxysilane into the system, keeping the stirring speed and the reaction temperature for 90min, removing and washing the magnetic particles coated with silicon dioxide by using a magnet, drying at the temperature of 110 ℃ for 8h, dispersing the prepared magnetic nanoparticles into 200mL of dichloromethane, adding 2.5g of fluoroether acid at the temperature of 40 ℃, stirring at the speed of 400rpm for 15min, adding 5mL of thionyl chloride, adding 2.5m of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stable and stirring, and separating the magnetic nanoparticles from the system by using the magnet, and (3) drying for 8 hours at 100 ℃ after washing to obtain the magnetic nanoparticles which take the ferroferric oxide particles as cores and can be dispersed in the fluoroether oil, wherein the magnetic curve of the material is shown in figure 3, and the magnetic nanoparticles have a superparamagnetic characteristic, which is typical superparamagnetic characteristic.
Example 4
The silicon dioxide coats the ferroferric oxide magnetic nanoparticles grafted by the perfluorooctane sulfonic acid. 27.8g of ferrous sulfate heptahydrate and 3.99g of ferric chloride were prepared into a 50mL solution, and 200mL of aqueous ammonia solution (100mL of concentrated ammonia and 100mL of deionized water) was added and mechanically stirred at 300rpm for 2 h. And then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the magnetic ferroferric oxide to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity ferroferric oxide magnetic nanoparticles. Dispersing the ferroferric oxide magnetic nanoparticles into a mixed solution formed by 100mL of ethanol and 200mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 30mL of concentrated ammonia water, adding 20g of tetraethyl orthosilicate after 20min, reacting for 1h, adding 0.5g of aminopropyl trimethoxysilane into the system, keeping the stirring speed and the reaction temperature for 90min, removing and washing the magnetic particles coated with silicon dioxide by using a magnet, and drying at the temperature of 110 ℃ for 8 h; and then dispersing the prepared magnetic nanoparticles in 200mL of dichloromethane, adding 1.5g of perfluorooctanoyl fluoride at 40 ℃, stirring at 400rpm for 15min, adding 5mL of thionyl chloride, adding 2.5g of triethanolamine as a catalyst, reacting for 2h under the condition of keeping stability and stirring, separating the magnetic nanoparticles from the system by using a magnet, washing, and drying at 100 ℃ for 8h to obtain the magnetic nanoparticles which take ferroferric oxide particles as cores and can be dispersed in fluoroether oil, wherein the X-ray diffraction pattern of the particles is shown in FIG. 4, and the comparison of FIG. 4 with a standard chart library is carried out to confirm that the phase of the particles is ferroferric oxide.
Example 5
The silicon dioxide coats the ferroferric oxide magnetic nano particles grafted by perfluorooctanesulfonyl. Preparing 50mL of solution by 27.8g of ferrous sulfate heptahydrate and 3.99g of ferric chloride, adding 200mL of ammonia water solution (100mL of concentrated ammonia water and 100mL of deionized water), and mechanically stirring at the speed of 300rpm for 2 hours; then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the magnetic ferroferric oxide to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain high-purity ferroferric oxide magnetic nanoparticles; dispersing the ferroferric oxide magnetic nanoparticles into a mixed solution formed by 100mL of ethanol and 200mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 30mL of concentrated ammonia water, adding 20g of tetraethyl orthosilicate after 20min, reacting for 1h, adding 0.5g of aminopropyl trimethoxysilane into the system, keeping the stirring speed and the reaction temperature for 90min, removing and washing the magnetic nanoparticles coated with silicon dioxide by using a magnet, and drying at the temperature of 110 ℃ for 8 h; and then dispersing the prepared magnetic nanoparticles in 200mL of dichloromethane, adding 1.5g of perfluorooctanesulfonyl fluoride at 40 ℃, stirring at the speed of 400rpm for 15min, adding 5mL of thionyl chloride, adding 2.5g of triethanolamine as a catalyst, reacting for 2h under the condition of keeping stability and stirring, separating the magnetic nanoparticles from the system by using a magnet, washing, and drying at 100 ℃ for 8h to obtain the magnetic nanoparticles which take ferroferric oxide particles as cores and can be dispersed in fluoroether oil.
Example 6
And coating the cobalt magnetic nanoparticles grafted by the perfluorooctanoic acid with silicon dioxide. Dissolving 23.79g of cobalt chloride hexahydrate in 100mL of deionized water, then adding 3g of ethanolamine, then mechanically stirring at the speed of 300rpm for 30min, adding 50mL of sodium borohydride aqueous solution of sodium hydroxide (the concentration of sodium borohydride is 1mol/L), and then stirring at 50 ℃ for 2 h; and then transferring the mixture into a beaker, placing the beaker above a magnet, quickly precipitating the cobalt nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity cobalt magnetic nanoparticles. Dispersing the cobalt magnetic nanoparticles into a mixed solution formed by 50mL of ethanol and 100mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 15mL of concentrated ammonia water, adding 10g of tetraethyl orthosilicate after 20min, reacting for 1h, adding 0.25g of aminopropyl trimethoxysilane into the system, keeping the stirring speed and the reaction temperature for 90min, removing and washing the cobalt magnetic nanoparticles coated with silicon dioxide by using a magnet, and drying at the temperature of 110 ℃ for 8 h; and then dispersing the prepared cobalt magnetic nanoparticles into 200mL of dichloromethane, adding 0.75g of perfluorooctanoic acid at 40 ℃, stirring at 400rpm for 15min, adding 2.5mL of thionyl chloride, adding 2.5mL of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the cobalt magnetic nanoparticles from the system by using a magnet, washing, and drying at 100 ℃ for 8h to obtain the magnetic nanoparticles taking the cobalt nanoparticles as cores and capable of being dispersed in fluoroether oil.
Example 7
The cobalt magnetic nanoparticles grafted by perfluorooctanoic acid are coated by phenolic resin. 23.79g of cobalt chloride hexahydrate is dissolved in 100mL of deionized water, then 3g of ethanolamine is added, and after mechanical stirring is carried out at the speed of 300rpm for 30min, 50mL of sodium borohydride aqueous solution of sodium hydroxide (the concentration of sodium borohydride is 1mol/L) is added, and then stirring is carried out at the temperature of 50 ℃ for 2 h. And then transferring the mixture into a beaker, placing the beaker above a magnet, quickly precipitating the magnetic cobalt magnetic nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity cobalt magnetic nanoparticles. Dispersing the cobalt magnetic nanoparticles into a mixed solution formed by 100mL of ethanol and 50mL of deionized water, stirring at the speed of 300rpm at the temperature of 50 ℃ for 15min, adding 15mL of strong ammonia water, adding 6g of resorcinol and 10g (37%) of formaldehyde solution after 20min, keeping the stirring speed and the reaction temperature for 90min, removing and washing the cobalt magnetic nanoparticles coated with the phenolic resin by using a magnet, drying at 110 ℃ for 8h, then dispersing the prepared cobalt magnetic nanoparticles in 200mL dichloromethane, 0.75g of perfluoroiodooctane is added at 40 ℃, 1.2mL of pyridine is added as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the cobalt magnetic nanoparticles from the system by using a magnet, washing, and drying at 100 ℃ for 8h to obtain the magnetic nanoparticles which take the cobalt nanoparticles as cores and can be dispersed in the fluoroether oil.
Example 8
The perfluorooctane grafted iron-platinum alloy magnetic nanoparticles are coated by phenolic resin. 1.62g of ferric chloride and 0.41g of chloroplatinic acid are taken in 20mL of deionized water, then 0.1g of tartaric acid is added, then mechanical stirring is carried out at the speed of 300rpm for 30min, and then 2mL of sodium borohydride aqueous solution of sodium hydroxide (the concentration of sodium borohydride is 1mol/L) is added, and then stirring is carried out at the temperature of 50 ℃ for 2 h. And then transferring the mixture into a beaker, placing the beaker above a magnet, quickly precipitating the magnetic Pt-Fe alloy nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity Pt-Fe alloy magnetic nanoparticles. Dispersing the platinum-iron alloy magnetic nanoparticles into a mixed solution formed by 10mL of ethanol and 5mL of deionized water, stirring at the temperature of 50 ℃ at the speed of 300rpm for 15min, adding 1.5mL of concentrated ammonia water, adding 0.6g of resorcinol and 1g (37%) of formaldehyde solution after 20min, keeping the stirring speed and the reaction temperature for 90min, removing and washing the platinum-iron alloy magnetic nanoparticles coated with the phenolic resin by using a magnet, and drying at the temperature of 110 ℃ for 8 h; and then dispersing the prepared platinum-iron alloy magnetic nanoparticles into 200mL of dichloromethane, adding 0.1g of perfluoroiodooctane at 40 ℃, adding 0.1mL of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the platinum-iron alloy magnetic nanoparticles from the system by using a magnet, washing, and drying for 8h at 100 ℃ to obtain the magnetic nanoparticles which take the platinum-iron alloy particles as cores and can be dispersed in fluoroether oil.
Example 9
The melamine resin coats the perfluorooctyl grafted iron-platinum alloy magnetic nanoparticles. 1.62g of ferric chloride and 0.41g of chloroplatinic acid are taken to be put into 20mL of deionized water, then 0.1g of tartaric acid is added, then the mechanical stirring is carried out at the speed of 300rpm for 30min, 2mL of sodium borohydride aqueous solution of sodium hydroxide is added (the concentration of sodium borohydride is 1mol/L), and then the stirring is carried out for 2h at the temperature of 50 ℃; and then transferring the mixture into a beaker, placing the beaker above a magnet, quickly precipitating the platinum-iron alloy magnetic nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain the high-purity platinum-iron alloy magnetic nanoparticles. Dispersing the platinum-iron alloy magnetic nanoparticles into a mixed solution formed by 10mL of ethanol and 5mL of deionized water, stirring at 50 ℃ at a speed of 300rpm for 15min, adjusting the pH of the solution to 3.5 by using hydrochloric acid, adding 0.6g of melamine and 1g (37%) of formaldehyde solution after 20min, keeping the stirring speed and the reaction temperature for 90min, removing and washing the platinum-iron alloy magnetic nanoparticles coated with melamine resin by using a magnet, and drying at 110 ℃ for 8 h; and then dispersing the prepared platinum-iron alloy magnetic nanoparticles in 200mL of dichloromethane, adding 0.1g of perfluoroiodooctane at 40 ℃, adding 0.1mL of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the material from the system by using a magnet, washing, and drying for 8h at 100 ℃ to obtain the magnetic nanoparticles which take platinum-iron alloy as a core and can be dispersed in fluoroether oil.
Example 10
The perfluorooctyl grafted iron-platinum alloy magnetic nanoparticles are coated by the aluminum trioxide. 1.62g of ferric chloride and 0.41g of chloroplatinic acid are taken in 20mL of deionized water, then 0.1g of tartaric acid is added, then mechanical stirring is carried out at the speed of 300rpm for 30min, and then 2mL of sodium borohydride aqueous solution of sodium hydroxide (the concentration of sodium borohydride is 1mol/L) is added, and then stirring is carried out at the temperature of 50 ℃ for 2 h. Then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the platinum-iron alloy magnetic nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain high-purity platinum-iron alloy magnetic nanoparticles; dispersing the platinum-iron alloy magnetic nanoparticles into a mixed solution formed by 10mL of ethanol and 20mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 2g of aluminum isopropoxide, keeping the stirring speed and the reaction temperature for 30min, adding 02g of aminopropyltrimethoxysilane, reacting with 1.5g of ammonia water for 2h, removing and washing the platinum-iron alloy magnetic nanoparticles coated with aluminum trioxide resin by using a magnet, and drying at 110 ℃ for 8 h; then dispersing 200mL of the prepared material in dichloromethane, adding 0.1g of perfluoroiodooctane at 40 ℃, adding 0.1mL of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the material from the system by using a magnet, washing, and drying for 8h at 100 ℃; the magnetic nanometer particles which take the platinum-iron alloy as the core and can be dispersed in the fluoroether oil are obtained.
Example 11
The titanium dioxide coats the perfluorooctyl grafted iron-platinum alloy magnetic nanoparticles. 1.62g of ferric chloride and 0.41g of chloroplatinic acid are taken in 20mL of deionized water, then 0.1g of tartaric acid is added, then mechanical stirring is carried out at the speed of 300rpm for 30min, and then 2mL of sodium borohydride aqueous solution of sodium hydroxide (the concentration of sodium borohydride is 1mol/L) is added, and then stirring is carried out at the temperature of 50 ℃ for 2 h. Then transferring the mixture into a beaker, placing the beaker above a magnet, rapidly precipitating the platinum-iron alloy magnetic nanoparticles to the bottom of the beaker, pouring off water and impurities on the upper part, and washing for 2-3 times by using deionized water to obtain high-purity platinum-iron alloy magnetic nanoparticles; dispersing the platinum-iron alloy magnetic nanoparticles into a mixed solution formed by 10mL of ethanol and 20mL of deionized water, stirring at the speed of 300rpm at 50 ℃ for 15min, adding 2g of tetraisopropyl titanate, keeping the stirring speed and the reaction temperature for 30min, adding 02g of aminopropyltrimethoxysilane, reacting with 1.5g of ammonia water for 2h, removing and washing the platinum-iron alloy magnetic nanoparticles coated with aluminum trioxide resin by using a magnet, and drying at 110 ℃ for 8 h; then dispersing 200mL of the prepared material in dichloromethane, adding 0.1g of perfluoroiodooctane at 40 ℃, adding 0.1mL of pyridine as an acid-binding agent, reacting for 2h under the condition of keeping stability and stirring, separating the material from the system by using a magnet, washing, and drying for 8h at 100 ℃; the magnetic nanometer particles which take the platinum-iron alloy as the core and can be dispersed in the fluoroether oil are obtained.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims (8)

1. A preparation method of a novel magnetic sealing material is characterized in that the magnetic sealing material is composed of core-shell particles and grafting groups; the core is a superparamagnetic nanoparticle, and the particle size of the magnetic nanoparticle is 5-100 nm; the shell is an inert oxide layer or a resin layer coated on the surface of the core; and the hydroxyl, carboxyl, amino or sulfhydryl groups on the shell can be chemically grafted with groups; the thickness of the shell is 1-100 nm; the grafting group is a fluorocarbon chain grafted on the inert metal oxide layer or the resin layer, the coverage of the fluorocarbon chain on the surface of the shell is 5-95%, and the chain length is 4-15 carbon atoms;
the preparation method comprises the following steps:
1) preparing ferromagnetic nano particles: synthesized by coprecipitation method, solvothermal method, emulsion synthesis method and sol-gel method
Figure 836758DEST_PATH_IMAGE001
Magnetic metal oxide nanoparticles; or synthesizing to obtain metal oxide nanoparticles of iron, cobalt and nickel or alloy oxide nanoparticles of cobalt-neodymium, platinum-iron and palladium-iron by a precipitation method, a solvothermal method, an emulsion synthesis method and a sol-gel method, and then reducing the obtained metal oxide nanoparticles of iron, cobalt and nickel or alloy oxide nanoparticles of cobalt-neodymium, platinum-iron and palladium-iron into metal nanoparticles of iron, cobalt and nickel or cobalt-neodymium, platinum-iron and palladium-ferromagnetic alloy nanoparticles;
2) modifying and coating superparamagnetic nanoparticles: dispersing the ferromagnetic nanoparticles obtained in the step 1) in water or an organic solvent, then adding one of tetraethyl orthosilicate, tetramethyl orthosilicate, tetraisopropyl titanate, tetrabutyl titanate or aluminum isopropoxide into the superparamagnetic nanoparticles dispersed in the water or the organic solvent, and stirring to coat an inert oxide layer on the surfaces of the magnetic nanoparticles; adding one or more of vinyltrimethoxysilane, aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, aminopropyltriethoxysilane or 3-mercaptopropyltriethoxysilane in the process of coating the inert oxide layer on the ferromagnetic nanoparticles to graft hydroxyl, amino or mercapto grafting groups on the inert metal oxide layer of the superparamagnetic nanoparticles; or adding one of polymerizable resorcinol, bisphenol A and melamine and one of formaldehyde and furfural into ferromagnetic nanoparticles dispersed in water or an organic solvent, and polymerizing on the surface of the magnetic nanoparticles under the action of acid or alkali to form a stable resin layer; or adding methyl acrylate, ethyl acrylate and methacrylic acid into the magnetic nanoparticles dispersed in water or an organic solvent, heating and stirring for reaction, and realizing the formation of a resin layer on the surface of the ferromagnetic nanoparticles; hydrolyzing the magnetic nano particles coated with the resin layer to enable the surfaces of the magnetic nano particles to have carboxyl; or epoxy resin and a curing agent are selected to coat the ferromagnetic nano particles, so that the surfaces of the magnetic particles contain residual amino groups of the curing agent;
3) adding heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, dodecafluoroheptylpropyltrimethoxysilane and dodecafluoroheptylpropyltriethoxysilane into the ferromagnetic nanoparticles coated with the inert metal oxide layer or the resin layer obtained in the step 2), so that the fluorine-containing carbon chain can be directly linked to the surface of the magnetic particles; or selecting fluorocarbon according to the functional group on the surface of the magnetic nano-particles to graft fluorocarbon chains on the surface of the magnetic nano-particles.
2. The method for preparing the novel magnetic sealing material according to claim 1, wherein the microscopic morphology of the superparamagnetic nanoparticles is a spherical, rod-like, cubic, rectangular, hexagonal or nanoflower structure.
3. The method for preparing the novel magnetic sealing material according to claim 1, wherein the inert oxide layer is formed by coating one of silicon dioxide and titanium dioxide on the surface of the ferromagnetic nanoparticles.
4. The method for preparing a novel magnetic sealing material according to claim 1, wherein the resin layer is formed by coating one of phenolic resin, melamine resin, polyacrylic resin and epoxy resin on the surface of the superparamagnetic nanoparticle.
5. The method for preparing a novel magnetic sealing material according to claim 1, wherein the fluorocarbon chain is one or two of perfluorooctanoyl, perfluorohexanoyl, fluoroether acid, perfluorooctanol, perfluorooctanoamine, perfluorooctanoyl, and perfluorohexanoyl fluorocarbon chains.
6. The method for preparing a novel magnetic sealing material according to claim 1, wherein in the step 3), when the surface of the superparamagnetic nanoparticle has amino groups and hydroxyl groups, one of perfluorooctanoic acid, perfluorohexanoic acid chloride, perfluorooctylsulfonyl fluoride and perfluorohexylsulfonyl fluoride, or a mixture of perfluorooctanoic acid or perfluorohexanoic acid and any one of phosphorus pentachloride, phosphorus oxychloride and thionyl chloride is added to the superparamagnetic nanoparticle coated with the inert oxide layer or the resin layer.
7. The method for preparing the novel magnetic sealing material according to claim 1, wherein in the step 3), when the surface of the ferromagnetic nanoparticle has a mercapto group, one or more of perfluorohexylethylene, perfluorooctylethylene or 14 fluorooctene is/are added to the ferromagnetic nanoparticle coated with the inert metal oxide layer or the resin layer, and the fluorocarbon chain is grafted on the surface of the ferromagnetic nanoparticle under the irradiation of ultraviolet light.
8. The method for preparing the novel magnetic sealing material according to claim 1, wherein in the step 3), when the surface of the superparamagnetic nanoparticle has carboxyl groups, one or more of perfluorooctylamine, perfluorohexylamine, perfluorooctanol and perfluorohexanol are added to the magnetic nanoparticle coated with the inert metal oxide layer or the resin layer to react with the carboxyl groups, so as to graft fluorocarbon chains on the surface of the ferromagnetic nanoparticle.
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