A preparation method of polyaniline directional induced MOF@hollow carbon fiber for microwave absorption

Abstract

A method for preparing polyaniline-directed MOF@hollow carbon fibers for wave absorption belongs to the technical field of preparation of carbon fiber materials and composite materials thereof. Method: preparing cotton fibers loaded with polyaniline; preparing cotton fibers for growing MOF particles; and carbonization treatment. The present invention is based on biomass materials as carbon templates, and adopts polyaniline as a directional directing agent to precisely and controllably grow MOF nanoparticles on their surface. The carbonization process is precisely regulated, and composite components are screened and optimized, and electromagnetic parameters are regulated to achieve optimization of electromagnetic wave absorption characteristics. The present invention aims to promote the multifunctional application of natural fibers while optimizing the physical and chemical properties of carbon-based materials. The material prepared by the present invention has high hollowness, light weight, simple preparation method, and easy-to-control process. The economic value of cotton biomass fibers is enhanced while giving them functional applications. It can show specificity in chemical and physical (thermal, optical, electromagnetic, etc.) properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of carbon fiber materials and composite materials thereof, and particularly relates to a method for preparing polyaniline directional induced MOF@hollow carbon fibers for wave absorption. Background Art

[0002] The development of efficient, high-potential electromagnetic functional materials has become a research priority for promoting electromagnetic energy attenuation management. Among these, the two most common electromagnetic functional materials for eliminating and reducing electromagnetic radiation are absorbing electromagnetic waves with absorbing materials or reflecting them with electromagnetic shielding materials. Advanced carbon materials have been reported as the most attractive electromagnetic attenuation materials due to their rich functional groups, enhanced electrical loss, and considerable dielectric loss. To date, research on the preparation of many carbon materials has flourished. Unfortunately, the synthesized products of these carbon materials are single-form, requiring expensive raw materials and complex processes. Therefore, there is an urgent need to provide sustainable, economical raw materials and simple synthesis techniques for the production of multifunctional carbon materials. Biomass (such as pumpkin seed shells, walnut shells, eggshells, and orange peels) is a renewable resource with a wide range of sources, low cost, and no contribution to atmospheric CO2. Therefore, biomass-derived carbon materials are green and environmentally friendly materials with numerous advantages, including wide availability, environmentally friendly renewability, unique structures, and low cost. They are currently widely used in electrode materials, electrocatalysis, adsorption, and other fields.

[0003] MOF-based electromagnetic functional materials have attracted widespread attention in the electromagnetic field for the following reasons: First, the multifaceted microstructure and components of the MOF structure can be easily adjusted to tune electromagnetic parameters and accelerate energy absorption and dissipation. Second, the self-template transformation method takes into account the atomic-level distribution of magnetic metal sources and organic ligands, providing the possibility of preparing EMW absorbers with dielectric multi-loss capabilities. Third, the hierarchical porous structure of MOF-derived materials provides the absorber with lightweight properties, excellent impedance matching characteristics, and multiple reflection and scattering paths. As a result, innovative work on MOF-based electromagnetic functional materials has been widely developed, and their absorption properties are constantly being updated. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned problems existing in the existing preparation technology of carbon fibers and composite materials for electromagnetic absorption, and to provide a preparation method of polyaniline directional induced MOF@hollow carbon fibers for electromagnetic absorption.

[0005] A preparation method of polyaniline directional induced MOF@hollow carbon fiber for microwave absorption is achieved by the following steps:

[0006] 1. Surface pretreatment of cotton fibers: soaking the cotton fibers in anhydrous ethanol, then adding aniline and stirring, then dropping an aqueous solution of ammonium persulfate and continuing stirring, washing and drying to obtain polyaniline-loaded cotton fibers;

[0007] 2. Growth of MOF particles: The polyaniline-loaded cotton fibers were immersed in a methanol solution of dimethylimidazole and allowed to stand. A methanol solution of cobalt nitrate hexahydrate was then added and allowed to stand for a further period. After washing and drying, the cotton fibers on which MOF particles were grown were obtained.

[0008] 3. Carbonization treatment: The tree cotton fiber on which the MOF particles are grown is calcined at a high temperature in an inert gas atmosphere. After cooling in the furnace, the microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber is obtained, thus completing the preparation method.

[0009] Furthermore, the hollowness of the tree cotton fiber in step 1 is 85% to 90%, the fiber length is 31 mm to 35 mm, and the fiber fineness is 16 μm to 28 μm.

[0010] Furthermore, the specific process of the surface pretreatment of the tree cotton fiber in step 1 is as follows: 0.4-0.6 g of tree cotton fiber is soaked in 100-500 ml of anhydrous ethanol, 0.1-1 ml of aniline is added and stirred for 0.5-6 hours, 10-30 ml of ammonium persulfate aqueous solution is added dropwise and stirring is continued for 5-10 hours, and after washing with anhydrous ethanol 2-3 times, vacuum drying is carried out at 60-80° C. for 15-24 hours to obtain tree cotton fiber loaded with polyaniline.

[0011] Furthermore, the concentration of the ammonium persulfate aqueous solution is 0.003-0.3 g / mL.

[0012] Furthermore, the methanol solution of dimethylimidazole in step 2 is prepared by adding 1 to 10 g of dimethylimidazole to 50 to 150 mL of anhydrous methanol and stirring thoroughly to dissolve the mixture, thereby obtaining a methanol solution of dimethylimidazole.

[0013] Furthermore, the standing time in step 2 is 24 hours.

[0014] Furthermore, the methanol solution of cobalt nitrate hexahydrate in step 2 is prepared by adding 1 to 5 g of cobalt nitrate hexahydrate into 50 to 150 mL of anhydrous methanol and stirring thoroughly to dissolve the mixture, thereby obtaining a methanol solution of cobalt nitrate hexahydrate.

[0015] Furthermore, the time for continuing to stand in step 2 is 24 hours.

[0016] Furthermore, the washing and drying in step 2 are as follows: washing with anhydrous methanol and anhydrous ethanol for 1 to 3 times respectively, and then drying at 60°C.

[0017] Furthermore, the growth of the MOF particles in step 2 can also be as follows: immersing the polyaniline-loaded cotton fiber in a deionized water solution of dimethylimidazole and allowing it to stand, then adding it to an aqueous solution of ferric chloride hexahydrate and continuing to stand, washing and drying, to obtain cotton fibers with grown MOF particles; the deionized water solution of dimethylimidazole: adding 1 to 10 g of dimethylimidazole to 100 mL of deionized water and stirring thoroughly to dissolve; the aqueous solution of ferric chloride hexahydrate: adding 1 to 5 g of ferric chloride hexahydrate to 25 mL of deionized water and stirring thoroughly to dissolve.

[0018] Furthermore, the growth of the MOF particles in step 2 can also be as follows: immersing the polyaniline-loaded cotton fiber in a methanol solution of dimethylimidazole and allowing it to stand, then adding a methanol solution of zinc nitrate hexahydrate and continuing to stand, washing and drying to obtain cotton fibers with grown MOF particles; the methanol solution of dimethylimidazole: adding 1 to 10 g of dimethylimidazole to 100 mL of methanol and stirring thoroughly to dissolve; the methanol solution of zinc nitrate hexahydrate: adding 1 to 5 g of zinc nitrate hexahydrate to 100 mL of methanol and stirring thoroughly to dissolve.

[0019] Furthermore, the specific process of the carbonization treatment in step three is as follows: the tree cotton fiber with MOF particles is placed in a tubular furnace, and in an inert gas atmosphere, the temperature is raised to 625°C at a rate of 0.5-1.5°C / min and kept warm for 45-175 minutes; the inert gas is nitrogen or argon.

[0020] This invention uses biomass as a carbon template and employs polyaniline as a directional directing agent to precisely and controllably grow MOF nanoparticles on its surface. By precisely controlling the carbonization process and optimizing the composite components, electromagnetic parameters are manipulated to optimize electromagnetic wave absorption properties. This invention aims to promote the multifunctional application of natural fibers while optimizing the physical and chemical properties of carbon-based materials. This invention has broad application prospects.

[0021] The reaction principle of the present invention is: tree cotton is a natural biomass fiber with an ultra-high aspect ratio and a unique hollow microscopic morphology. Biomass is the most abundant carbon source material other than petrochemical-based materials. In the context of the "dual carbon" goals, in addition to reasonably reducing the use of carbon-containing fossil fuels, thinking about how to fix the carbon dioxide gas absorbed by plants from the atmosphere through photosynthesis in a more stable form for a long time and make high-value use of it has become an important topic worthy of in-depth research. With the increasing complexity of scenarios such as commercial, radar monitoring and military applications, scientific researchers have gradually deepened their exploration of electromagnetic absorption materials. After carbonization, tree cotton fibers become carbon fibers with a unique hollow structure, which is conducive to electromagnetic absorption. First, hollow carbon within the structure can extend the propagation path of electromagnetic waves, providing more opportunities for multiple reflections and scattering, thereby increasing energy attenuation and leading to electromagnetic wave dissipation. Second, the pores and voids between hollow carbon fibers introduce air, reducing the effective dielectric constant and thus optimizing impedance matching. Third, the porosity of the hollow carbon fibers can act as point defects, leading to the emergence of dipole moments. This dipole moment enhances dielectric relaxation by improving the material's dielectric dipole polarization, thus facilitating electromagnetic wave absorption. Fourth, the hollow, porous structure can induce multipolarization relaxation, improving electromagnetic absorption performance. Therefore, tree cotton-derived carbon fibers hold great promise for application in electromagnetic functional materials. However, because biomass-derived carbon materials are typically nonmagnetic, the unique electromagnetic wave attenuation mechanism and the mismatch in electromagnetic wave input impedance severely hinder their electromagnetic wave absorption performance. Therefore, tree cotton fibers are selected as biomass templates for subsequent carbonization to obtain hollow carbon tube fibers. Polyaniline (PANI), with its advantages of light weight, corrosion resistance, ease of preparation, and excellent dielectric properties, is a reasonable choice for improving EM absorption performance. During the doping process, polyaniline H + and counter anions (such as Cl -, sulfate, phosphate) will not change. These polarities and dipoles are delocalized from the P bonds of the entire molecular chain, so polyaniline has higher conductivity. It is considered to be one of the most promising candidate materials because of its excellent properties (including light weight, corrosion resistance, ease of synthesis and dielectric loss capacity). At the same time, the amino groups on polyaniline can bond with the hydroxyl groups on the tree cotton fiber, thereby attracting the attachment of polyaniline. Therefore, binary composites with polyaniline with higher conductivity on the surface of hollow carbon fibers can adjust the electromagnetic parameters and enhance electromagnetic absorption. Adding MOF particles on this basis can further enhance the electromagnetic absorption capacity of the material, because MOF particles, as a new type of porous material, have unique structural characteristics that make them have great application potential in the field of electromagnetic wave absorption. Its large pore size and high specific surface area provide ample space for the absorption of electromagnetic waves, and its adjustable structural components make it possible to achieve customized design for specific functions. At the same time, the metal ions in the MOF particles can bond with the amino groups of polyaniline to produce metal chelation, thereby achieving directional induction of polyaniline, promoting the growth of MOF particles on the surface of tree cotton-derived hollow carbon fibers, achieving ternary composite, regulating electromagnetic parameters, and accelerating energy absorption and dissipation.

[0022] The beneficial effect of the present invention is that it can combine the advantages of excellent magnetic loss electromagnetic wave absorption capacity of MOF-derived magnetic metal / C nanoparticles. Magnetic metal / carbon nanocomposites with various nanostructures are prepared by directly pyrolyzing MOF particles containing Fe / Co / Zn, such as zeolite imidazolate framework (ZIF-67) particles and compounding with biomass-derived carbon materials. These magnetic nanocomposites have the advantages of porous structure, high specific surface area and ferromagnetism. At the same time, the synergistic electromagnetic dissipation effect between the carbon base and the magnetic metal nanoparticles makes it a lightweight broadband electromagnetic wave absorption material. The carbon-based material prepared by the present invention has high hollowness, light weight, simple preparation method and easy process control. It enhances the economic value of tree cotton biomass fiber and gives it functional applications. The polyaniline directional induced MOF-derived metal particle @ hollow carbon composite fiber prepared by the present invention. It can show specificity in chemical and physical (thermal, optical, electromagnetic, etc.) properties.

[0023] The present invention is suitable for the preparation of polyaniline directional induction MOF@hollow carbon fiber for wave absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a SEM image of the polyaniline oriented MOF@hollow carbon fiber for microwave absorption prepared in Example 1;

[0025] Figure 2 This is a 3D loss diagram of the electromagnetic absorption performance of the polyaniline directional induced MOF@hollow carbon fiber prepared in Example 1;

[0026] Figure 3 This is a SEM image of the polyaniline oriented MOF@hollow carbon fiber for microwave absorption prepared in Example 2;

[0027] Figure 4 This is a 3D loss diagram of the electromagnetic absorption performance of the polyaniline directional induced MOF@hollow carbon fiber prepared in Example 2;

[0028] Figure 5 This is a 3D loss diagram of the electromagnetic absorption performance of the polyaniline-loaded hollow carbon fiber prepared in Example 3. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0030] Specific embodiment 1: This embodiment provides a method for preparing polyaniline directional induced MOF@hollow carbon fiber for wave absorption, which is achieved by the following steps:

[0031] 1. Surface pretreatment of cotton fibers: soaking the cotton fibers in anhydrous ethanol, then adding aniline and stirring, then dropping an aqueous solution of ammonium persulfate and continuing stirring, washing and drying to obtain polyaniline-loaded cotton fibers;

[0032] 2. Growth of MOF particles: The polyaniline-loaded cotton fibers were immersed in a methanol solution of dimethylimidazole and allowed to stand. A methanol solution of cobalt nitrate hexahydrate was then added and allowed to stand for a further period. After washing and drying, the cotton fibers on which MOF particles were grown were obtained.

[0033] 3. Carbonization treatment: The tree cotton fiber on which the MOF particles are grown is calcined at a high temperature in an inert gas atmosphere. After cooling in the furnace, the microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber is obtained, thus completing the preparation method.

[0034] In the polyaniline-loaded tree cotton fiber described in step 1 of this embodiment, the loaded polyaniline is used as the rivet site of the MOF particle to achieve its directional and controllable growth.

[0035] The polyaniline directional induced MOF@hollow carbon fiber for wave absorption prepared in step 3 of this embodiment is used for electromagnetic wave absorption function applications.

[0036] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the hollowness of the tree cotton fiber in step 1 is 85% to 90%, the fiber length is 31mm to 35mm, and the fiber fineness is 16μm to 28μm. Other steps and parameters are the same as specific embodiment 1.

[0037] Specific embodiment three: This embodiment differs from specific embodiment two in that the specific process of the tree cotton fiber surface pretreatment in step one is as follows: 0.4-0.6g of tree cotton fiber is soaked in 100-500ml of anhydrous ethanol, 0.1-1ml of aniline is added, and the mixture is stirred for 0.5-6h. 10-30ml of an aqueous ammonium persulfate solution is then added dropwise and stirred for 5-10h. After washing with anhydrous ethanol 2-3 times, the mixture is vacuum-dried at 60-80°C for 15-24h to obtain the polyaniline-loaded tree cotton fiber. The other steps and parameters are the same as those in specific embodiment two.

[0038] Specific embodiment 4: This embodiment differs from specific embodiment 3 in that the concentration of the aqueous ammonium persulfate solution is 0.003-0.3 g / mL. Other steps and parameters are the same as those of specific embodiment 3.

[0039] Specific embodiment 5: This embodiment differs from specific embodiment 1 in that, in step 2, the methanol solution of dimethylimidazole is prepared by adding 1-10 g of dimethylimidazole to 50-150 mL of anhydrous methanol and stirring thoroughly to dissolve the resulting solution. The other steps and parameters are the same as those in specific embodiment 1.

[0040] Specific embodiment 6: This embodiment differs from specific embodiment 1 in that the resting time in step 2 is 24 hours. The other steps and parameters are the same as those in specific embodiment 1.

[0041] Specific Embodiment 7: This embodiment differs from Specific Embodiment 1 in that, in step 2, the methanol solution of cobalt nitrate hexahydrate is prepared by adding 1-5 g of cobalt nitrate hexahydrate to 50-150 mL of anhydrous methanol and stirring thoroughly to dissolve the cobalt nitrate hexahydrate in methanol. Other steps and parameters are the same as those in Specific Embodiment 1.

[0042] Specific embodiment 8: This embodiment differs from specific embodiment 1 in that the time for continuing to stand in step 2 is 24 hours. Other steps and parameters are the same as those in specific embodiment 1.

[0043] Specific embodiment 9: This embodiment differs from specific embodiment 1 in that the washing and drying in step 2 are performed using anhydrous methanol and anhydrous ethanol for 1 to 3 times each, and then dried at 60° C. The other steps and parameters are the same as those in specific embodiment 1.

[0044] Specific embodiment ten: This embodiment differs from specific embodiment one in that the growth of the MOF particles in step two can also be: immersing the polyaniline-loaded cotton fiber in a deionized aqueous solution of dimethylimidazole and allowing it to stand, then adding it to an aqueous solution of ferric chloride hexahydrate and continuing to stand, and then washing and drying to obtain the cotton fiber with the MOF particles grown thereon;

[0045] The deionized water solution of dimethylimidazole: add 1-10g of dimethylimidazole to 100mL of deionized water and stir thoroughly to dissolve;

[0046] The aqueous solution of ferric chloride hexahydrate: add 1-5 g of ferric chloride hexahydrate into 25 mL of deionized water and stir thoroughly to dissolve.

[0047] Other steps and parameters are the same as those in the first embodiment.

[0048] Specific embodiment 11: This embodiment differs from specific embodiment 1 in that the growth of the MOF particles in step 2 can also be performed by immersing the polyaniline-loaded cotton fiber in a methanol solution of dimethylimidazole and allowing it to stand, then adding a methanol solution of zinc nitrate hexahydrate and continuing to stand, washing and drying to obtain the cotton fiber on which the MOF particles are grown;

[0049] The methanol solution of dimethylimidazole: add 1-10 g of dimethylimidazole to 100 mL of methanol and stir thoroughly to dissolve;

[0050] The methanol solution of zinc nitrate hexahydrate: add 1-5 g of zinc nitrate hexahydrate into 100 mL of methanol and stir thoroughly to dissolve.

[0051] Other steps and parameters are the same as those in the first embodiment.

[0052] Specific Embodiment 12: This embodiment differs from Specific Embodiment 1 in that the carbonization process described in step 3 is as follows: the cotton fibers on which the MOF particles are grown are placed in a tubular furnace and heated at a rate of 0.5-1.5°C / min to 625°C under an inert gas atmosphere of nitrogen or argon for 45-175 minutes. Other steps and parameters are the same as those in Specific Embodiment 1.

[0053] The beneficial effects of the present invention are verified by the following examples:

[0054] Example 1:

[0055] A preparation method of polyaniline directional induced MOF@hollow carbon fiber for microwave absorption is achieved by the following steps:

[0056] 1. Surface pretreatment of cotton fibers: soaking the cotton fibers in anhydrous ethanol, then adding aniline and stirring, then dropping an aqueous solution of ammonium persulfate and continuing stirring, washing and drying to obtain polyaniline-loaded cotton fibers;

[0057] 2. Growth of MOF particles: The polyaniline-loaded cotton fibers were immersed in a methanol solution of dimethylimidazole and allowed to stand. A methanol solution of cobalt nitrate hexahydrate was then added and allowed to stand for a further period. After washing and drying, the cotton fibers on which MOF particles were grown were obtained.

[0058] 3. Carbonization treatment: The tree cotton fiber on which the MOF particles are grown is calcined at a high temperature in an inert gas atmosphere. After cooling in the furnace, the microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber is obtained, thus completing the preparation method.

[0059] The hollowness of the tree cotton fiber in step 1 of this embodiment is 85% to 90%, the fiber length is 31 mm to 35 mm, and the fiber fineness is 16 μm to 28 μm;

[0060] The specific process of the surface pretreatment of the tree cotton fiber in step 1 is as follows: 0.5 g of tree cotton fiber is soaked in 200 ml of anhydrous ethanol, 0.4 ml of aniline is added and stirred for 2 hours, 20 ml of ammonium persulfate aqueous solution is added dropwise and stirring is continued for 5 to 10 hours, and after washing with anhydrous ethanol 2 to 3 times, vacuum drying is carried out at 60 to 80 ° C for 15 to 24 hours to obtain tree cotton fiber loaded with polyaniline;

[0061] The concentration of the ammonium persulfate aqueous solution is 0.0125 g / mL;

[0062] The methanol solution of dimethylimidazole in step 2: add 4 g of dimethylimidazole to 120 mL of anhydrous methanol and stir thoroughly to dissolve to obtain a methanol solution of dimethylimidazole;

[0063] The standing time in step 2 is 24 hours;

[0064] The methanol solution of cobalt nitrate hexahydrate described in step 2: add 3.87 g of cobalt nitrate hexahydrate to 120 mL of anhydrous methanol and stir thoroughly to dissolve to obtain a methanol solution of cobalt nitrate hexahydrate;

[0065] The time for continuing to stand still in step 2 is 24 hours;

[0066] Washing and drying in step 2: washing with anhydrous methanol and anhydrous ethanol twice each, and then drying at 60°C;

[0067] The specific process of the carbonization treatment in step 3 is as follows: the tree cotton fiber with MOF particles is placed in a tubular furnace, and the temperature is raised to 625° C. at a rate of 1° C. / min under an inert gas atmosphere and kept at this temperature for 120 min; the inert gas is argon.

[0068] Example 2:

[0069] The differences between this embodiment and embodiment 1 are as follows: 0.1 ml of aniline is added in step 1; the concentration of the ammonium persulfate aqueous solution is 0.0031 g / mL; and the rest are the same as embodiment 1.

[0070] Example 3:

[0071] The polyaniline-loaded cotton fiber prepared in step 1 of Example 2 was placed in a tubular furnace, and heated to 625° C. at a rate of 1° C. / min under an inert gas atmosphere and kept at this temperature for 120 min; the inert gas was argon.

[0072] In this embodiment, polyaniline-loaded hollow carbon fibers were prepared.

[0073] result:

[0074] from Figure 1 The SEM image of the polyaniline-oriented MOF@hollow carbon fibers prepared in Example 1 shows that the carbonized carbon fibers replicate the hollow morphology of cottonwood. The fiber diameter is approximately 15 μm, and the carbon wall thickness is approximately 600 nm. The method used in this example successfully grew MOF particles within the hollow carbon tubes, along with cobalt metal oxide particles derived from the MOF particles on the surface and within the hollow carbon tubes.

[0075] from Figure 2 The 3D loss diagram of the electromagnetic absorption performance of the polyaniline directional induced MOF@hollow carbon fiber prepared in Example 1 shows that the composite carbon fiber prepared by the method of this example has a reflection loss value of -56dB, and is an excellent electromagnetic absorption material.

[0076] from Figure 3 The SEM image of the polyaniline-oriented MOF@hollow carbon fibers prepared in Example 2 shows that the carbonized carbon fibers replicate the hollow morphology of cottonwood. The fiber diameter is ~15 μm, and the carbon wall thickness is approximately ~600 nm. The method of this example successfully grew MOF particles within the hollow carbon tubes, with cobalt metal oxide particles derived from the MOF particles growing on the surface and within them.

[0077] from Figure 4 From the 3D loss diagram of the electromagnetic absorption performance of the polyaniline directional induced MOF@hollow carbon fiber prepared in Example 2, it can be seen that the composite carbon fiber prepared by the method of this embodiment has a reflection loss value of -59dB, and is an excellent electromagnetic absorption material.

[0078] Figure 5 3D loss diagram of the electromagnetic absorption performance of the polyaniline-loaded hollow carbon fiber prepared in Example 3; compared with the polyaniline-oriented induced MOF@hollow carbon fiber prepared in Example 1, it increased by two times.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing polyaniline directional induced MOF@ hollow carbon fiber for microwave absorption, characterized in that It proceeds as follows:

1. Surface pretreatment of cotton fibers: soaking the cotton fibers in anhydrous ethanol, then adding aniline and stirring, then dropping an aqueous solution of ammonium persulfate and continuing stirring, washing and drying to obtain polyaniline-loaded cotton fibers; 2. Growth of MOF particles: The polyaniline-loaded cotton fibers were immersed in a methanol solution of dimethylimidazole and allowed to stand. A methanol solution of cobalt nitrate hexahydrate was then added and allowed to stand for a further period. After washing and drying, the cotton fibers on which MOF particles were grown were obtained.

3. Carbonization treatment: The tree cotton fiber on which the MOF particles are grown is calcined at a high temperature in an inert gas atmosphere. After cooling in the furnace, the microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber is obtained, thus completing the preparation method.

2. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The hollowness of the tree cotton fiber in step 1 is 85% to 90%, the fiber length is 31mm to 35mm, and the fiber fineness is 16μm to 28μm.

3. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The specific process of the surface pretreatment of the tree cotton fiber in step 1 is as follows: 0.4-0.6 g of tree cotton fiber is soaked in 100-500 ml of anhydrous ethanol, 0.1-1 ml of aniline is added and stirred for 0.5-6 hours, 10-30 ml of ammonium persulfate aqueous solution is then added dropwise and stirring is continued for 5-10 hours. After washing with anhydrous ethanol 2-3 times, vacuum drying is carried out at 60-80° C. for 15-24 hours to obtain tree cotton fiber loaded with polyaniline.

4. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 3, characterized in that The concentration of the ammonium persulfate aqueous solution is 0.003-0.3 g / mL.

5. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The methanol solution of dimethylimidazole in step 2: add 1-10 g of dimethylimidazole to 50-150 mL of anhydrous methanol and stir thoroughly to dissolve, to obtain a methanol solution of dimethylimidazole.

6. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The standing time in step 2 is 24 hours.

7. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The methanol solution of cobalt nitrate hexahydrate in step 2: add 1-5 g of cobalt nitrate hexahydrate to 50-150 mL of anhydrous methanol and stir thoroughly to dissolve, thereby obtaining a methanol solution of cobalt nitrate hexahydrate.

8. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The time for continuing to stand still in step 2 is 24 hours.

9. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that Washing and drying in step 2: washing with anhydrous methanol and anhydrous ethanol 1 to 3 times each, and then drying at 60°C.

10. The method for preparing a microwave-absorbing polyaniline-oriented MOF@hollow carbon fiber according to claim 1, characterized in that The specific process of the carbonization treatment described in step 3 is as follows: the tree cotton fiber with MOF particles is placed in a tubular furnace, and the temperature is raised to 625°C at a rate of 0.5-1.5°C / min under an inert gas atmosphere and kept warm for 45-175 minutes; the inert gas is nitrogen or argon.

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