Conjugated microporous polymer-based composite magnetic wave-absorbing carbon fiber, and preparation method and application thereof

Abstract

The present application relates to a kind of composite magnetic wave-absorbing carbon fibers based on conjugated microporous polymer and its preparation method and application, the method of the present application selects and introduces conjugated microporous polymer, transition metal iron, cobalt element as the component of wave-absorbing fiber, and the microstructure of the nano-fiber constructed can enhance scattering and electromagnetic synergistic effect, simultaneously realizes stronger absorption intensity and wider absorption bandwidth, and develops a kind of wideband, strong absorption performance wave-absorbing carbon fiber.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wave-absorbing materials, and particularly relates to a composite magnetic wave-absorbing carbon fiber based on conjugated microporous polymers and a preparation method and application thereof. BACKGROUND

[0002] With the increasing demand for electromagnetic protection materials, developing and preparing new wave-absorbing fibers meeting the requirements of "strong, wide, light and thin" and excellent stable performance has become a major research focus in the field of wave-absorbing materials. In recent years, carbon fibers have been widely used as wave-absorbing fibers, but carbon fibers have the disadvantages of high electrical conductivity, single loss mechanism and narrow absorption bandwidth. SUMMARY

[0003] The technical problem to be solved by the application is to provide a composite magnetic wave-absorbing carbon fiber based on conjugated microporous polymers and a preparation method and application thereof. The composite magnetic wave-absorbing carbon fiber has electromagnetic dual components, which can effectively improve the impedance matching of the fiber surface; and the nanofiber structure and the defect interface between the electromagnetic components and the carbon matrix can provide a large number of active sites for polarization, thereby enhancing the attenuation loss capacity of electromagnetic waves, so that the wave-absorbing performance with high absorption strength and wide absorption bandwidth is obtained.

[0004] The application provides a composite magnetic wave-absorbing carbon fiber, which is obtained by in-situ growth of conjugated microporous polymers on a nanofiber membrane and then introduction of magnetic nanoparticles through pyrolysis.

[0005] The application provides a preparation method of the composite magnetic wave-absorbing carbon fiber, which comprises the following steps:

[0006] (1) Preparation of precursor nanofiber:

[0007] The monomer, polyacrylonitrile and solvent are mixed to obtain a spinning solution, and the precursor nanofiber membrane is obtained by spinning.

[0008] (2) In-situ growth of conjugated microporous polymers

[0009] The precursor nanofiber membrane and the mixture are subjected to metal coupling reaction to obtain a composite nanofiber membrane; wherein the mixture comprises a mixture of an organic ligand, a catalyst, sodium tert-butoxide and a solvent.

[0010] (3) High-temperature pyrolysis to introduce magnetic nanoparticles

[0011] The composite nanofiber membrane is immersed in a mixed solution containing an iron source and a cobalt source, and is carbonized to obtain the composite magnetic wave-absorbing carbon fiber.

[0012] Preferably, the monomer in step (1) is aromatic monomer; wherein the aromatic monomer comprises tris(4-bromophenyl)amine and p-phenylenediamine; the solvent comprises N-N-dimethylamide; wherein the molar ratio of tris(4-bromophenyl)amine, p-phenylenediamine in the monomer is (0.8-1.2):(1.3-1.8).

[0013] Preferably, the ratio of monomer, polyacrylonitrile in step (1) is (2-3) mmol:(1.5-1.8) g.

[0014] Preferably, the spinning process parameters in step (1) include: positive voltage is 8-12 kV, negative voltage is 4-6 kV, injector needle distance from the receiver is 9-17 cm, extrusion speed is 0.8-1.2 mL / h, receiver rotation speed is 100-300 rpm.

[0015] The metal coupling reaction in step (2) prepares the conjugated microporous polymer PTPA.

[0016] Preferably, the organic ligand in step (2) comprises 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl; the catalyst comprises bis(benzylideneacetone)palladium(0); the solvent comprises toluene.

[0017] Preferably, the molar ratio of monomer, organic ligand, catalyst, sodium tert-butoxide in step (2) is (2-3):(0.09-0.12):(0.06-0.08):(3.8-4.2).

[0018] Preferably, the coupling reaction in step (2) is reacted at 100-110℃ for 24-48h in anhydrous and anaerobic environment.

[0019] Further, as the metal coupling reaction: take bis(benzylideneacetone)palladium(0) (0.06-0.08 mmol), 2-dicyclohexylphosphine-2', 4', 6'-triisopropylbiphenyl (0.09-0.12 mmol) and sodium tert-butoxide (3.8-4.2 mmol) in a reaction tube, add anhydrous toluene, then react with the precursor nanofiber at 100-110℃ under nitrogen atmosphere for 24-48h, wash after the reaction is cooled to room temperature, and finally dry to obtain PTPA nanofiber; wherein the washing is to wash the product roughly with methanol, chloroform and deionized water; wherein the ratio of bis(benzylideneacetone)palladium(0), 2-dicyclohexylphosphine-2', 4', 6'-triisopropylbiphenyl and sodium tert-butoxide is (0.06-0.08 mmol):(0.09-0.12 mmol):(3.8-4.2 mmol):70-80 ml.

[0020] Preferably, the iron source in the step (3) comprises an iron salt; the cobalt source comprises a cobalt salt; wherein the iron salt comprises ferric chloride hexahydrate; the cobalt salt comprises cobalt acetylacetonate.

[0021] Preferably, the ratio of the composite nanofiber membrane, the iron source and the cobalt source in the step (3) is (0.1-0.5) g:(0.01-0.5) mol:(0.01-0.5) mol.

[0022] The mixed solution containing the iron source and the cobalt source in the step (3) comprises one or more of methanol and water.

[0023] The immersion time in the step (3) is 6-12 h.

[0024] Preferably, the carbonization in the step (3) is carried out under an inert atmosphere (such as N2, etc.), the carbonization heating rate is 3-10 ℃ / min, the carbonization temperature is 600-900 ℃, and the holding time is 1-3 h.

[0025] The washing and drying are carried out before the carbonization in the step (3), wherein the drying is carried out at 50-65 ℃ for 5-15 h.

[0026] The application provides an application of the composite magnetic wave-absorbing carbon fiber in the electromagnetic protection field.

[0027] In the application, an aromatic monomer and a polyacrylonitrile precursor nanofiber membrane are prepared by electrospinning; a conjugated microporous polymer is grown in situ on the nanofiber membrane; and then Fe and Co nanoparticles are introduced in a pyrolysis process to obtain a composite magnetic wave-absorbing carbon fiber.

[0028] In the method, the conjugated microporous polymer, the transition metal iron and the element cobalt are selected as components of the wave-absorbing fiber, and the microstructure of the constructed nanofiber can enhance scattering and electromagnetic synergistic effect, and meanwhile, a strong absorption intensity and a wide absorption bandwidth are realized, and a wave-absorbing carbon fiber with wide frequency and strong absorption performance is developed.

[0029] The strongest absorption intensity of the composite magnetic wave-absorbing carbon fiber reaches-59.9 dB, and the maximum absorption bandwidth lower than-10 dB is 5.7 GHz.

[0030] Advantageous effects

[0031] (1) The composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer provided by the application takes the conjugated microporous polymer as a precursor, the unique pore structure of which increases multiple scattering of electromagnetic waves in the interior of the conjugated microporous polymer and thus enhances loss; and on this basis, magnetic metal is loaded to introduce a magnetic loss mechanism, and under the electromagnetic coupling synergistic loss mechanism, the composite magnetic wave-absorbing carbon fiber has high strength and wide frequency absorption performance, and provides a new method for assembling a wave-absorbing material with lightness, thinness, wide frequency and strong absorption.

[0032] (2) The application provides a preparation method of a composite magnetic wave-absorbing carbon fiber based on a conjugated microporous polymer. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 An absorption performance diagram of the composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer provided for the application example 1 is shown in the figure.

[0034] Figure 2 An absorption performance diagram of the composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer provided for the application example 2 is shown in the figure.

[0035] Figure 3 An absorption performance diagram of the composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer provided for the application example 3 is shown in the figure.

[0036] Figure 4 An absorption performance diagram of the carbonized polyacrylonitrile fiber provided for the comparative example 1 of the application is shown in the figure.

[0037] Figure 5 An absorption performance diagram of the composite powder provided for the comparative example 2 of the application is shown in the figure.

[0038] Figure 6 A scanning electron microscope micrograph of the composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer provided for the application example 2 is shown in the figure. DETAILED DESCRIPTION

[0039] The application will be further described below in conjunction with specific examples. It should be understood that the examples are only used to illustrate the application and not used to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content of the application, and these equivalent forms also fall within the scope of the appended claims of the application.

[0040] The coaxial method is adopted in the examples and the comparative examples, and the composite magnetic carbon fiber is mixed with a paraffin base at a mass ratio of 2:8, uniformly pressed into a concentric cylinder with an inner diameter of 3.04 mm and an outer diameter of 7 mm. The reference test standard is SJ 20512-1995 Microwave Large Loss Solid Material Complex Permittivity and Permeability Test Method.

[0041] Example 1

[0042] The composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer is prepared by the following method:

[0043] Take 1.5 g of polyacrylonitrile, 1 mmol of tris(4-bromophenyl)amine, 1.5 mmol of p-phenylenediamine, and 8.5 g of N-N-dimethylacetamide, swell at room temperature for 3 h, and dissolve at 60°C for 4 h to obtain a spinning solution. Take 10 mL of a syringe to extract an appropriate amount of the prepared spinning solution, and then fix the syringe on a micro pump. Set the distance between the syringe and the receiver to 13 cm, the left and right swing distance of the translation motor to 40 mm, the moving speed to 10 mm / min, the positive voltage to 10 kV, the negative voltage to 5 kV, the extrusion speed to 1.0 mL / h, and the rotation speed of the receiver to 100 rpm to obtain the precursor nanofiber membrane.

[0044] The PTPA / PAN fiber was prepared by Buchwald-Hartwig coupling reaction. Specifically, bis(dibenzylideneacetone)palladium(0) (0.07 mmol), 2-dicyclohexylphospho-2', 4', 6'-triisopropylbiphenyl (0.10 mmol), and sodium tert-butoxide (4.0 mmol) were in a Schlenk tube (volume 100 ml). The precursor nanofiber membrane was hung in the Schlenk tube to avoid contacting the magnetic sub at the bottom of the tube, and the mixture was dissolved in 75 mL of anhydrous toluene in an anhydrous and oxygen-free environment, and then reacted at 110°C for 24 h. After the reaction was completed, it was cooled to room temperature, and then washed with methanol and water three times respectively. Finally, the product was placed in a vacuum oven at 40°C for drying for 12 h to obtain the PTPA nanofiber membrane.

[0045] Take 0.01 mol of iron chloride hexahydrate, 0.01 mol of cobalt acetylacetonate, and 100 mL of methanol in a 200 mL beaker, and stir for 0.5 h until a mixed solution of Fe ions and Co ions is obtained. Take 0.2 g of the PTPA nanofiber membrane and place it in the mixed solution, and take it out and wash after 6 h. Then dry the above-mentioned fiber membrane in an oven at 60°C for 12 h, and carbonize under N2 atmosphere. The temperature is 700°C, the heating rate is 5°C / min, and the holding time is 2 h.

[0046] The strongest absorption intensity of the composite magnetic wave-absorbing carbon fiber reaches -46.6 dB when the thickness is 5.0 mm; and the maximum absorption bandwidth below -10 dB is 5.1 GHz when the thickness is 2.5 mm.

[0047] Example 2

[0048] The composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer is prepared by the following method:

[0049] Take 1.5 g of polyacrylonitrile, 1 mmol of tris(4-bromophenyl)amine, 1.5 mmol of p-phenylenediamine, and 8.5 g of N-N-dimethylacetamide, swell at room temperature for 3 h, and dissolve at 60°C for 4 h to obtain a spinning solution. Take 10 mL of a syringe to extract an appropriate amount of the prepared spinning solution, and then fix the syringe on a micro pump. Set the distance between the syringe and the receiver to 13 cm, the left and right swing distance of the translation motor to 40 mm, the moving speed to 10 mm / min, the positive voltage to 10 kV, the negative voltage to 5 kV, the extrusion speed to 1.0 mL / h, and the rotation speed of the receiver to 100 rpm to obtain the precursor nanofiber membrane.

[0050] The PTPA / PAN fiber is prepared by Buchwald-Hartwig coupling reaction. Specifically, bis(dibenzylideneacetone)palladium(0) (0.07 mmol), 2-dicyclohexylphospho-2', 4', 6'-triisopropylbiphenyl (0, 10 mmol), and sodium tert-butoxide (4 mmol) are in a Schlenk tube (volume 100 ml). The precursor nanofiber membrane is hung in the Schlenk tube to avoid contacting the magnetic sub at the bottom of the tube, and the mixture is dissolved in 75 mL of anhydrous toluene in an anhydrous and oxygen-free environment, and then reacted at 110°C for 24 h. After the reaction is completed, it is cooled to room temperature, and then washed with methanol and water three times respectively. Finally, the product is placed in a vacuum oven at 40°C for drying for 12 h to obtain the PTPA nanofiber membrane.

[0051] Take 0.05 mol of iron chloride hexahydrate, 0.05 mol of cobalt acetylacetonate, and 100 mL of methanol in a 200 mL beaker, and stir for 0.5 h until a mixed solution of Fe ions and Co ions is obtained. Take 0.2 g of the PTPA nanofiber membrane and place it in the mixed solution, and take it out and wash after 6 h. Then dry the above-mentioned fiber membrane in an oven at 60°C for 12 h, and carbonize under N2 atmosphere. The temperature is 700°C, the heating rate is 5°C / min, and the holding time is 2 h.

[0052] When the matching thickness is 5.0 mm, the strongest absorption intensity of the composite magnetic wave-absorbing carbon fiber reaches -41.4 dB; when the thickness is 2.5 mm, the maximum absorption bandwidth below -10 dB is 5.7 GHz.

[0053] Example 3

[0054] The composite magnetic wave-absorbing carbon fiber based on the conjugated microporous polymer is prepared by the following method:

[0055] 1.5 g of polyacrylonitrile, 1 mmol of tris(4-bromophenyl)amine, and 1.5 mmol of p-phenylenediamine were weighed into 8.5 g of N-N-dimethylacetamide, swelled at room temperature for 3 h, and dissolved at 60°C for 4 h to obtain a spinning solution. An appropriate amount of the prepared spinning solution was taken into a 10 mL syringe, and then the syringe was fixed on a micro pump. The distance between the syringe and the receiver was set to 13 cm, the left-right swing distance of the translation motor was set to 40 mm, the moving speed was set to 10 mm / min, the positive voltage was set to 10 kV, the negative voltage was set to 5 kV, the extrusion speed was set to 1.0 mL / h, and the rotation speed of the receiver was set to 100 rpm to obtain a precursor nanofiber membrane.

[0056] The PTPA / PAN fiber was prepared by Buchwald-Hartwig coupling reaction. Specifically, bis(dibenzylideneacetone)palladium(0) (0.07 mmol), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (0.10 mmol), and sodium tert-butoxide (4 mmol) were in a Schlenk tube (volume 100 ml). The precursor nanofiber membrane was hung in the Schlenk tube to avoid contacting the magnetic sub at the bottom of the tube, and the mixture was dissolved in 75 mL of anhydrous toluene in an anhydrous and oxygen-free environment, and then reacted at 110°C for 24 h. After the reaction was completed, it was cooled to room temperature, and then washed with methanol and water three times respectively. Finally, the product was placed in a vacuum oven at 40°C for drying for 12 h to obtain a PTPA nanofiber membrane.

[0057] 0.1 mol of iron chloride hexahydrate and 0.1 mol of cobalt acetylacetonate were weighed into 100 mL of methanol in a 200 mL beaker, stirred for 0.5 h until fully dispersed to obtain a mixed solution of Fe ions and Co ions. 0.2 g of the PTPA nanofiber membrane was placed in the mixed solution and taken out and washed after 6 h. Then the above-mentioned fiber membrane was dried in an oven at 60°C for 12 h and carbonized under N2 atmosphere. The temperature was 700°C, the heating rate was 5°C / min, and the holding time was 2 h.

[0058] When the matching thickness was 5.0 mm, the strongest absorption intensity of the composite magnetic wave-absorbing carbon fiber reached -59.9 dB; when the thickness was 2.5 mm, the maximum absorption bandwidth below -10 dB was 5.1 GHz.

[0059] Comparative Example 1

[0060] The carbonized polyacrylonitrile fiber was prepared by the following method:

[0061] Take 1.5 g of polyacrylonitrile and place it in 8.5 g of N-N-dimethylamide, swell at room temperature for 3 h, and dissolve at 60°C for 4 h to obtain a spinning solution. Take 10 mL of a syringe to extract an appropriate amount of the above prepared spinning solution, then fix the syringe on a micro pump. Set the distance between the syringe and the receiver to 13 cm, the left and right swing distance of the translation motor to 40 mm, the moving speed to 10 mm / min, the positive voltage to 10 kV, the negative voltage to 5 kV, the extrusion speed to 1.0 mL / h, and the rotation speed of the receiver to 100 rpm to obtain polyacrylonitrile nanofibers.

[0062] Carbonize the above polyacrylonitrile nanofibers under N2 atmosphere, the temperature is 700°C, the heating rate is 5°C / min, and the holding time is 2 h.

[0063] When the matching thickness is 5.0 mm, the strongest absorption intensity of the carbonized polyacrylonitrile fiber reaches -20.0 dB, and when the thickness is 2.5 mm, the maximum absorption bandwidth below -10 dB is 5.23 GHz.

[0064] Comparative Example 2

[0065] The composite magnetic wave-absorbing carbon material based on the conjugated microporous polymer is prepared by the following method:

[0066] The composite magnetic wave-absorbing carbon material is prepared by Buchwald-Hartwig coupling reaction. Specifically, take 1 mmol of tris(4-bromophenyl)amine, 1.5 mmol of p-phenylenediamine bis(dibenzalacetone) palladium(0) (0.07 mmol), 2-dicyclohexylphosphine-2',4',6'-triisopropyl biphenyl (0.10 mmol), and sodium tert-butoxide (4.0 mmol) in a Schlenk tube. Dissolve the mixture in 75 mL of anhydrous toluene in an anhydrous and oxygen-free environment, then react at 110°C for 24 h. After the reaction is completed, cool to room temperature, then rinse with methanol and water three times respectively. Finally, place the product in a 40°C vacuum oven for drying for 12 h to obtain a composite powder.

[0067] Take 0.05 mol of iron chloride hexahydrate, 0.05 mol of cobalt acetylacetonate, and 100 mL of methanol in a 200 mL beaker, stir for 0.5 h until fully dispersed to obtain a mixed solution of Fe ions and Co ions. Take 0.2 g of the composite powder and place it in the mixed solution, and take it out and rinse after 6 h. Then dry the product in a 60°C oven for 12 h, and carbonize under N2 atmosphere. The temperature is 700°C, the heating rate is 5°C / min, and the holding time is 2 h.

[0068] When the matching thickness is 5.0 mm, the strongest absorption intensity of the composite magnetic wave-absorbing carbon fiber reaches-16.4 dB, and when the thickness is 2.5 mm, the maximum absorption bandwidth below-10 dB is 2.94 GHz.

Claims

1. A composite magnetic wave-absorbing carbon fiber, characterized by, The composite magnetic wave-absorbing carbon fiber is obtained by in-situ growth of conjugated microporous polymers on the nanofiber membrane, and then introducing magnetic nanoparticles by pyrolysis; The preparation method of the composite magnetic wave-absorbing carbon fiber comprises the following steps: (1) mixing monomers, polyacrylonitrile and a solvent to obtain a spinning solution, and spinning to obtain a precursor nanofiber membrane; wherein the monomers are aromatic monomers; the aromatic monomers are tri(4-bromophenyl)amine and p-phenylenediamine; (2) coupling the precursor nanofiber membrane and a mixture to obtain a composite nanofiber membrane; wherein the mixture comprises a mixture of an organic ligand, a catalyst, sodium tert-butoxide and a solvent; (3) immersing the composite nanofiber membrane in a mixed solution containing an iron source and a cobalt source, and carbonizing to obtain the composite magnetic wave-absorbing carbon fiber.

2. A preparation method of a composite magnetic wave-absorbing carbon fiber, comprising: (1) mixing monomers, polyacrylonitrile and a solvent to obtain a spinning solution, and spinning to obtain a precursor nanofiber membrane; wherein the monomers are aromatic monomers; wherein the aromatic monomers are tri(4-bromophenyl)amine and p-phenylenediamine; (2) coupling the precursor nanofiber membrane and a mixture to obtain a composite nanofiber membrane; wherein the mixture comprises a mixture of an organic ligand, a catalyst, sodium tert-butoxide and a solvent; (3) immersing the composite nanofiber membrane in a mixed solution containing an iron source and a cobalt source, and carbonizing to obtain the composite magnetic wave-absorbing carbon fiber.

3. The preparation method according to claim 2, characterized in that, The solvent in step (1) comprises N-N-dimethylformamide; The ratio of the monomers to polyacrylonitrile in step (1) is (2-3) mmol:(1.5-1.8) g.

4. The preparation method according to claim 2, characterized in that, The spinning process parameters in step (1) comprise: a positive voltage of 8-12 kV, a negative voltage of 4-6 kV, a distance between the injector needle and the receiver of 9-17 cm, an extrusion speed of 0.8-1.2 mL / h, and a receiver rotation speed of 100-300 rpm.

5. The preparation method according to claim 2, characterized in that, The organic ligand in step (2) comprises 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl; the catalyst comprises bis(bibenzylideneacetone)palladium; and the solvent comprises toluene.

6. The preparation method according to claim 2, characterized in that, The molar ratio of the monomers, the organic ligand, the catalyst and sodium tert-butoxide in step (2) is (2-3):(0.09-0.12):(0.06-0.08):(3.8-4.2).

7. The preparation method according to claim 2, characterized in that, The coupling reaction in step (2) is carried out under anhydrous and anaerobic conditions at 100-110°C for 24-48 h.

8. The preparation method according to claim 2, characterized in that, The iron source in step (3) comprises an iron salt; the cobalt source comprises a cobalt salt; the iron salt comprises ferric chloride hexahydrate; and the cobalt salt comprises cobalt acetylacetonate; The ratio of the composite nanofiber membrane, the iron source and the cobalt source in step (3) is (0.1-0.5) g:(0.01-0.5) mol:(0.01-0.5) mol.

9. The preparation method according to claim 2, characterized in that, The carbonization in step (3) is carried out under an inert atmosphere, the carbonization temperature rising rate is 3-10°C / min, the carbonization temperature is 600-900°C, and the holding time is 1-3 h; The immersion time in step (3) is 6-12 h.

10. Application of the composite magnetic wave-absorbing carbon fiber in the electromagnetic protection field.

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