Nanometer magnetic material and its processing method

Abstract

The application discloses a kind of nano magnetic material and processing method thereof, it relates to nano magnetic material technical field.The application is prepared with iron nitrate nine water, cobalt nitrate six water, porous carbon as raw material to obtain nano particle;The surface of nano particle is obtained by polyamidation to obtain nano magnetic material.Fluorine-containing monomer and 1,3,5-tri (4-ethynylphenyl) benzene are structural unit, and fluorine-containing conjugated microporous polymer is synthesized, and porous carbon is prepared by calcination, and the porous carbon has suitable adjustable mesoporous pore size, huge specific surface area, regular pore structure and excellent physical and chemical stability, and iron-cobalt-oxygen magnet is deposited on the surface of porous carbon to obtain nano particle, and the magnetic nano particle is assembled using porous carbon, which can avoid the agglomeration problem of nano material, ensure the coupling effect between magnetic nano material and mesoporous pore wall, and exhibit excellent wave-absorbing performance.

Description

Technical Field

[0001] This invention relates to the field of nanomagnetic materials technology, specifically to a nanomagnetic material and its processing method. Background Technology

[0002] Magnetic materials have always been an important pillar and foundation of the national economy and defense industry, with a wide range of applications, especially in information storage, processing, and transmission, where they have become an indispensable component. They are widely used in telecommunications, automatic control, communications, and electrical processing. With technological advancements, magnetic materials have entered the nanoscale stage.

[0003] The properties of nanoscale magnetic materials differ from those of conventional magnetic materials because their characteristic physical lengths associated with magnetism are precisely on the nanometer scale. When the size of a magnetic material is comparable to these characteristic physical lengths, it exhibits anomalous magnetic properties, such as the transition from a magnetically ordered state to a magnetically disordered state. The development of nanoscale magnetic materials has led to a qualitative leap in the magnetic properties of materials, significantly improving their magnetic performance. Studies have shown that when the size of materials enters the nanoscale, the specific surface area increases dramatically, the surface energy rises accordingly, and quantum effects emerge, giving magnetic materials some unique physical and chemical properties. For example, nanoscale magnetic single domains exhibit unusual superparamagnetism and high coercivity; light absorption increases significantly, producing a plasmonic frequency shift in the absorption peak; and superconducting normal phase transitions occur. Therefore, nanoscale magnetic materials have become a research hotspot in the fields of information, biology, chemistry, and materials science.

[0004] Due to their ultra-small size, nanomagnetic materials exhibit many properties different from conventional magnetic materials, such as superparamagnetism, high coercivity, small size effect, quantum tunneling effect, and lower Curie temperature. They are increasingly used in fields such as bioseparation, targeted drug delivery, tumor hyperthermia, and microwave absorption materials, and have become a research hotspot in recent years. However, due to their small size, large specific surface area, increased number of surface atoms, and high surface energy, these atomic surfaces are highly active and extremely unstable. Furthermore, the interactions between magnetic nanoparticles, including van der Waals forces, magnetic forces, and double-layer forces, make them prone to adsorption and aggregation when added to the matrix material, making mechanical dispersion difficult and negatively impacting their optical, electrical, and magnetic properties. In addition, unmodified nanomagnetic materials are inherently hydrophilic and oleophobic. When preparing magnetic microspheres or other magnetic materials, the matrix material is often an organic compound or polymer that is difficult for nanomagnetic materials to be compatible with, affecting the usability of the nanomagnetic materials. Summary of the Invention

[0005] The purpose of this invention is to provide a nanomagnetic material and its processing method, thereby solving the following technical problems:

[0006] Existing nanomagnetic materials are hydrophilic and oleophobic, and tend to agglomerate in the matrix material, which affects their application in the fields of optics, electronics, and magnetism.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for processing nanomagnetic materials includes the following steps:

[0009] A1: Weigh out ferric nitrate nonahydrate and cobalt nitrate hexahydrate and add them to the reaction flask. Add deionized water and stir evenly. Add porous carbon and stir mechanically evenly. Heat to 110-120℃ and dry for 6-9 hours. Balance the internal and external pressure and dry at 110-120℃ for 9-12 hours. Release the pressure and let stand at 200℃ for 12 hours. Dry to obtain nanoparticles.

[0010] A2: Disperse nanoparticles and 2-(3,4-dihydroxyphenyl)ethylamine in Tris-HCl buffer solution, stir mechanically for 12-24 h, add polyamide-amine, stir mechanically for 12-24 h, filter, wash with water, and dry to obtain nanomagnetic materials.

[0011] As a further embodiment of the present invention: the mass ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, deionized water, and porous carbon in A1 is 15-25: 5-10: 200-500: 20-30.

[0012] As a further embodiment of the present invention: the addition ratio of nanoparticles in A2 to 2-(3,4-dihydroxyphenyl)ethylamine to Tris-HCl buffer to polyamide-amine is 0.2:0.05-0.15:80-150mL:0.5-1g.

[0013] As a further aspect of the present invention, the pH value of the Tris-HCl buffer is 8.5.

[0014] As a further embodiment of the present invention: 9g of ethylenediamine and 32g of methanol were added to a reaction flask, and 103.2g of methyl acrylate was added dropwise. The reaction was carried out for 24 hours, and the mixture was distilled under reduced pressure to obtain polyamide-amine.

[0015] As a further aspect of the present invention, the method for preparing the porous carbon includes the following steps:

[0016] B1: In an inert gas atmosphere, 1,3,5-tris(4-ethynylphenyl)benzene and 1,3,5-trifluoro-2,4,6-triiodobenzene were added to a reaction vessel and mechanically stirred until homogeneous. A catalyst was added, and the temperature was raised to 75-85℃. The reaction was maintained at this temperature for 30-36 hours. The mixture was then filtered, washed sequentially with water, methanol, chloroform, and acetone. The solid was extracted sequentially with methanol, chloroform, and tetrahydrofuran for 24 hours. After vacuum drying, a porous polymer was obtained.

[0017] B2: The porous polymer and potassium hydroxide are mechanically ground and mixed, placed in a tube furnace, and calcined in an argon atmosphere. After calcination, argon is continuously introduced, the furnace door is opened and the mixture is allowed to cool naturally to room temperature to obtain powder. The powder is washed with hydrochloric acid and ethanol and dried in an oven to obtain porous carbon.

[0018] As a further embodiment of the present invention: the addition amount of 1,3,5-tris(4-ethynylphenyl)benzene: 1,3,5-trifluoro-2,4,6-triiodobenzene: catalyst in B1 is 1g: 1g: 40-50mL.

[0019] As a further embodiment of the present invention: the catalyst in B1 is obtained by mixing tetra(triphenylphosphine)palladium, copper iodide, tetrahydrofuran and triethylamine in an addition amount of 50-65mg: 15-25mg: 20-40mL: 20-40mL.

[0020] As a further aspect of the present invention: the mass ratio of porous polymer to potassium hydroxide in B2 is 100:10-25.

[0021] As a further aspect of the present invention: B2 is carried out in an argon atmosphere, heated to 600-800℃ for 1-2 hours, with a heating rate of 5-10℃ / min, to obtain porous carbon.

[0022] A nanomagnetic material is prepared by any of the above processing methods.

[0023] The beneficial effects of this invention are:

[0024] This invention synthesizes a fluorinated conjugated microporous polymer using fluorinated monomers and 1,3,5-tris(4-ethynylphenyl)benzene as structural units, exhibiting excellent hydrophobic properties. The prepared porous carbon possesses a suitable and tunable mesopore size, a large specific surface area, a regular pore structure, and excellent physicochemical stability. Iron-cobalt-oxygen magnets are deposited on the porous carbon surface to obtain nanoparticles. Assembling magnetic nanoparticles using porous carbon avoids the problem of nanomaterial aggregation, ensuring coupling between magnetic nanoparticles and between magnetic nanoparticles and the mesopore walls, exhibiting novel optical, electrical, and magnetic properties. The microporous structure improves the impedance matching and attenuation matching of the material, extending the propagation path of electromagnetic waves within the absorbing material. Finally, an organic layer is modified on the nanoparticle surface, endowing the nanoparticles with new surface functions, enabling them to be well-compatible and dispersed in the matrix material, and also improving their surface activity, expanding the application range of the magnetic nanoparticles. The formation of an organic film reduces or eliminates the formation of hydroxyl layers on the surface of the magnetic particles, and the shielding effect of the organic layer spatially isolates the hydroxyl layer, thus achieving the dual purpose of hydrophobicity and preventing adsorption and aggregation. After organic molecules are coated on the surface of the nanomagnetic material, the extension of the carbon chains on the surface of the particles in the solvent also prevents the particles from getting close to each other, thus achieving a dispersion effect. The reaction conditions promote the tight bonding of the surface organic layer, while improving the contact angle and wettability between the particles and the dispersion medium, enhancing the oleophilicity, and improving the compatibility and dispersibility of the magnetic nanoparticles in the matrix material. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] The preparation method of polyamide-amine includes the following steps:

[0028] 45g of ethylenediamine and 160g of methanol were added to a reaction flask, and 516g of methyl acrylate was added dropwise. The reaction was carried out for 24 hours, and the mixture was distilled under reduced pressure to obtain polyamide-amine.

[0029] Example 2

[0030] The preparation method of porous carbon includes the following steps:

[0031] B1: A catalyst was obtained by mixing tetra(triphenylphosphine)palladium, copper iodide, tetrahydrofuran, and triethylamine in an addition ratio of 1.3 g: 0.5 g: 800 mL: 800 mL.

[0032] B2: In an inert gas atmosphere, 30g of 1,3,5-tris(4-ethynylphenyl)benzene and 30g of 1,3,5-trifluoro-2,4,6-triiodobenzene were added to a reaction vessel and mechanically stirred until homogeneous. 1200mL of the catalyst prepared in step B1 was added, the temperature was raised to 75℃, and the reaction was maintained at this temperature for 30h. The mixture was then filtered, washed successively with water, methanol, chloroform, and acetone. The solid was extracted successively with methanol, chloroform, and tetrahydrofuran for 24h, and then dried under vacuum to obtain a porous polymer.

[0033] B3: 40g of porous polymer and 4g of potassium hydroxide were mechanically ground and mixed, placed in a tube furnace, and heated to 600℃ for 1h in an argon atmosphere. The heating rate was 5℃ / min. After calcination, argon was continuously introduced, the furnace door was opened and the mixture was allowed to cool naturally to room temperature to obtain powder. The powder was washed with hydrochloric acid and ethanol and dried in an oven to obtain porous carbon.

[0034] Example 3

[0035] The preparation method of porous carbon includes the following steps:

[0036] B1: A catalyst was obtained by mixing tetra(triphenylphosphine)palladium, copper iodide, tetrahydrofuran, and triethylamine in an addition ratio of 1.3 g: 0.5 g: 800 mL: 800 mL.

[0037] B2: In an inert gas atmosphere, 30g of 1,3,5-tris(4-ethynylphenyl)benzene and 30g of 1,3,5-trifluoro-2,4,6-triiodobenzene were added to a reaction vessel and mechanically stirred until homogeneous. 1300mL of the catalyst prepared in step B1 was added, the temperature was raised to 80℃, and the reaction was maintained at this temperature for 33h. The mixture was then filtered, washed successively with water, methanol, chloroform, and acetone. The solid was extracted successively with methanol, chloroform, and tetrahydrofuran for 24h. After vacuum drying, a porous polymer was obtained.

[0038] B3: 40g of porous polymer and 8g of potassium hydroxide were mechanically ground and mixed, placed in a tube furnace, and heated to 700℃ for 1.5h in an argon atmosphere at a heating rate of 5℃ / min. After calcination, argon was continuously introduced, the furnace door was opened and the mixture was allowed to cool naturally to room temperature to obtain powder. The powder was washed with hydrochloric acid and ethanol and dried in an oven to obtain porous carbon.

[0039] Example 4

[0040] The preparation method of porous carbon includes the following steps:

[0041] B1: A catalyst was obtained by mixing tetra(triphenylphosphine)palladium, copper iodide, tetrahydrofuran, and triethylamine in an addition ratio of 1.3 g: 0.5 g: 800 mL: 800 mL.

[0042] B2: In an inert gas atmosphere, 30g of 1,3,5-tris(4-ethynylphenyl)benzene and 30g of 1,3,5-trifluoro-2,4,6-triiodobenzene were added to a reaction vessel and mechanically stirred until homogeneous. 1500mL of the catalyst prepared in step B1 was added, the temperature was raised to 85℃, and the reaction was maintained at this temperature for 36h. The mixture was then filtered, washed successively with water, methanol, chloroform, and acetone. The solid was extracted successively with methanol, chloroform, and tetrahydrofuran for 24h. After vacuum drying, a porous polymer was obtained.

[0043] B3: 40g of porous polymer and 10g of potassium hydroxide were mechanically ground and mixed, placed in a tube furnace, and heated to 800℃ for 2h in an argon atmosphere at a heating rate of 5℃ / min. After calcination, argon was continuously introduced, the furnace door was opened and the mixture was allowed to cool naturally to room temperature to obtain powder. The powder was washed with hydrochloric acid and ethanol and dried in an oven to obtain porous carbon.

[0044] Example 5

[0045] A method for processing nanomagnetic materials includes the following steps:

[0046] A1: Weigh 15g of ferric nitrate nonahydrate and 5g of cobalt nitrate hexahydrate and add them to the reaction flask. Add 200mL of deionized water and stir evenly. Add 20g of porous carbon from Example 2 and stir evenly mechanically. Heat to 110℃ and dry for 6h. Balance the internal and external pressures and dry at 110℃ for 9h. Release the pressure and let stand at 200℃ for 12h. Dry to obtain nanoparticles.

[0047] A2: 0.2 g of nanoparticles and 0.05 g of 2-(3,4-dihydroxyphenyl)ethylamine were dispersed in 80 mL of Tris-HCl buffer solution with a pH of 8.5 and mechanically stirred for 12 h. Then, 0.5 g of polyamide-amine prepared in Example 1 was added and mechanically stirred for 12 h. The mixture was filtered, washed with water, and dried to obtain the nanomagnetic material.

[0048] Example 6

[0049] A method for processing nanomagnetic materials includes the following steps:

[0050] A1: Weigh 20g of ferric nitrate nonahydrate and 7g of cobalt nitrate hexahydrate and add them to the reaction flask. Add 400mL of deionized water and stir evenly. Add 25g of porous carbon from Example 3 and stir evenly mechanically. Heat to 115℃ and dry for 8h. Balance the internal and external pressure, dry at 115℃ for 10h, release the pressure, stand at 200℃ for 12h, and dry to obtain nanoparticles.

[0051] A2: 0.2 g of nanoparticles and 0.1 g of 2-(3,4-dihydroxyphenyl)ethylamine were dispersed in 120 mL of Tris-HCl buffer solution with a pH of 8.5 and mechanically stirred for 18 h. Then, 0.7 g of polyamide-amine prepared in Example 1 was added and mechanically stirred for 21 h. The mixture was filtered, washed with water, and dried to obtain the nanomagnetic material.

[0052] Example 7

[0053] A method for processing nanomagnetic materials includes the following steps:

[0054] A1: Weigh 25g of ferric nitrate nonahydrate and 10g of cobalt nitrate hexahydrate and add them to the reaction flask. Add 500mL of deionized water and stir evenly. Add 30g of porous carbon from Example 4 and stir evenly. Heat to 120℃ and dry for 9h. Balance the internal and external pressures and dry at 120℃ for 12h. Release the pressure and let stand at 200℃ for 12h. Dry to obtain nanoparticles.

[0055] A2: 0.2g of nanoparticles and 0.15g of 2-(3,4-dihydroxyphenyl)ethylamine were dispersed in 150mL of Tris-HCl buffer solution with a pH of 8.5 and mechanically stirred for 24h. Then, 1g of polyamide-amine prepared in Example 1 was added and mechanically stirred for 12-24h. The mixture was filtered, washed with water, and dried to obtain the nanomagnetic material.

[0056] Comparative Example 1

[0057] 30g of glucose monohydrate and 450g of sodium chloride were dissolved sequentially in 1500ml of deionized water. The solution was then continuously magnetically stirred in a 90℃ water bath until thickened, and then transferred to an 80℃ oven for drying. The dried mixture was then placed in a graphite boat, transferred to a tube furnace, and calcined at 800℃ for 2 hours under an argon atmosphere. Both the heating and cooling rates were set to 5℃ / min. Finally, the carbonized powder sample was washed multiple times with deionized water and vacuum filtered to remove the NaCl template, and then dried in a 60℃ oven to obtain porous carbon.

[0058] Comparative Example 2

[0059] A method for processing nanomagnetic materials includes the following steps:

[0060] A1: Weigh 25g of ferric nitrate nonahydrate and 10g of cobalt nitrate hexahydrate and add them to the reaction flask. Add 500mL of deionized water and stir evenly. Add 30g of porous carbon prepared in Comparative Example 1 and stir evenly. Heat to 120℃ and dry for 9h. Balance the internal and external pressure, dry at 120℃ for 12h, release the pressure, stand at 200℃ for 12h, and dry to obtain nanoparticles.

[0061] A2: 0.2g of nanoparticles and 0.15g of 2-(3,4-dihydroxyphenyl)ethylamine were dispersed in 150mL of Tris-HCl buffer solution with a pH of 8.5 and mechanically stirred for 24h. Then, 1g of polyamide-amine prepared in Example 1 was added and mechanically stirred for 12-24h. The mixture was filtered, washed with water, and dried to obtain the nanomagnetic material.

[0062] Comparative Example 3

[0063] A method for processing nanomagnetic materials includes the following steps:

[0064] Weigh 25g of ferric nitrate nonahydrate and 10g of cobalt nitrate hexahydrate and add them to a reaction flask. Add 500mL of deionized water and stir until homogeneous. Add 30g of porous carbon from Example 4 and stir mechanically until homogeneous. Heat to 120℃ and dry for 9 hours. Balance the internal and external pressures and dry at 120℃ for 12 hours. Release the pressure and let stand at 200℃ for 12 hours. Dry to obtain nano-magnetic materials.

[0065] Comparative Example 4

[0066] A method for processing nanomagnetic materials includes the following steps:

[0067] Weigh 25g of ferric nitrate nonahydrate and 10g of cobalt nitrate hexahydrate and add them to a reaction flask. Add 500mL of deionized water and stir until homogeneous. Add 30g of porous carbon prepared in Comparative Example 1 and stir mechanically until homogeneous. Heat to 120℃ and dry for 9h. Balance the internal and external pressures and dry at 120℃ for 12h. Release the pressure and let stand at 200℃ for 12h. Dry to obtain nano-magnetic materials.

[0068] Performance testing

[0069] (1) IR was measured using an RXS100 Fourier transform infrared spectrometer from Pepperl (USA) (KBr pellet). Magnetic properties were characterized using a 7407 vibrating sample magnetometer from Lakeshore (USA) at room temperature. The results are shown in Table 1.

[0070] (2) The nanomagnetic materials prepared in Examples 5-7 and Comparative Examples 2-4 were uniformly mixed with sliced ​​paraffin at a mass fraction of 40 wt%. The paraffin was dissolved in cyclohexane and stirred continuously in a mortar. During the stirring process, the cyclohexane continuously evaporated, and the sample and paraffin were thoroughly mixed. The mixture was then pressed into coaxial rings with an inner diameter of 3.00 mm, an outer diameter of 7.00 mm, and a thickness of 2.50 mm using a mold for testing. The electromagnetic parameters of these rings were tested in the 12-18 GHz frequency range using an Agilent 8720ET vector network analyzer via the Nicolson method. The test results are shown in Table 1, where the effective absorption band is the absorption band with an absorption intensity exceeding -10 dB (absorption rate of 90%).

[0071] Table 1: Material property test data of Examples 5-7 and Comparative Examples 2-4

[0072]

[0073] As shown in Table 1, the porous carbon prepared by this invention not only reduces the density of the material but also increases the multiple reflections of electromagnetic waves within the material, taking into account both magnetic loss and nodal loss mechanisms. This increases the dissipation capacity of electromagnetic waves within the material and improves its wave absorption performance. This invention involves organic modification of the nanoparticle surface, endowing it with new functions, reducing or eliminating the formation of hydroxyl layers on the surface of magnetic particles, and utilizing the shielding effect of the organic layer to spatially isolate the hydroxyl layer. This achieves the dual purpose of hydrophobicity and prevention of adsorption and aggregation, further improving the wave absorption performance of the nanomagnetic material. The nanomagnetic particles prepared in this application exhibit excellent wave absorption performance.

[0074] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for processing nanomagnetic materials, characterized in that, Includes the following steps: A1: Weigh out ferric nitrate nonahydrate and cobalt nitrate hexahydrate and add them to the reaction flask. Add deionized water and stir evenly. Add porous carbon and stir mechanically evenly. Heat to 110-120℃ and dry for 6-9 hours. Balance the internal and external pressure and dry at 110-120℃ for 9-12 hours. Release the pressure and let stand at 200℃ for 12 hours. Dry to obtain nanoparticles. A2: Disperse nanoparticles and 2-(3,4-dihydroxyphenyl)ethylamine in Tris-HCl buffer solution, stir mechanically for 12-24 h, add polyamide-amine, stir mechanically for 12-24 h, filter, wash with water, and dry to obtain nanomagnetic materials; The method for preparing the porous carbon includes the following steps: B1: In an inert gas atmosphere, 1,3,5-tris(4-ethynylphenyl)benzene and 1,3,5-trifluoro-2,4,6-triiodobenzene were added to a reaction vessel and mechanically stirred until homogeneous. A catalyst was added, and the temperature was raised to 75-85℃. The reaction was maintained at this temperature for 30-36 hours. The mixture was then filtered, washed sequentially with water, methanol, chloroform, and acetone. The solid was extracted sequentially with methanol, chloroform, and tetrahydrofuran for 24 hours. After vacuum drying, a porous polymer was obtained. B2: The porous polymer and potassium hydroxide are mechanically ground and mixed, placed in a tube furnace, and calcined in an argon atmosphere. After calcination, argon is continuously introduced, the furnace door is opened and the mixture is allowed to cool naturally to room temperature to obtain powder. The powder is washed with hydrochloric acid and ethanol and dried in an oven to obtain porous carbon.

2. The processing method of a nanomagnetic material according to claim 1, characterized in that, The mass ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, deionized water, and porous carbon in A1 is 15-25: 5-10: 200-500: 20-30.

3. The processing method of a nanomagnetic material according to claim 1, characterized in that, The addition ratio of nanoparticles in A2 to 2-(3,4-dihydroxyphenyl)ethylamine, Tris-HCl buffer, and polyamide-amine is 0.2g:0.05-0.15g:80-150mL:0.5-1g.

4. The processing method of a nanomagnetic material according to claim 1, characterized in that, In B1, the addition amount of 1,3,5-tris(4-ethynylphenyl)benzene: 1,3,5-trifluoro-2,4,6-triiodobenzene: catalyst is 1g: 1g: 40-50mL.

5. A method for processing nanomagnetic materials according to claim 1, characterized in that, The catalyst in B1 is a mixture of tetra(triphenylphosphine)palladium, copper iodide, tetrahydrofuran, and triethylamine in an addition ratio of 50-65 mg: 15-25 mg: 20-40 mL: 20-40 mL.

6. The processing method of a nanomagnetic material according to claim 1, characterized in that, In B2, the mass ratio of porous polymer to potassium hydroxide is 100:10-25.

7. A method for processing nanomagnetic materials according to claim 1, characterized in that, In B2, carbonization is carried out in an argon atmosphere, heated to 600-800℃ for 1-2 hours, with a heating rate of 5-10℃ / min, to obtain porous carbon.

8. A nanomagnetic material, characterized in that, It is prepared by the processing method of a nanomagnetic material according to any one of claims 1-7.

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