Surface topological carbon micro-nanomaterial, and preparation method and application thereof

Abstract

The application belongs to the technical field of electromagnetic wave absorbing materials, and discloses a surface topological carbon micro-nano material and a preparation method and application thereof.The preparation method comprises the following steps: mixing acrylonitrile, a first carbon-carbon double bond unsaturated monomer, a first solvent and a first initiator, performing a precipitation polymerization reaction, and obtaining a first powder; mixing the first powder, a second solvent, a second carbon-carbon double bond unsaturated monomer and a second initiator, performing a seed polymerization reaction, and obtaining a carbon microsphere precursor powder; the carbon microsphere precursor powder is pre-oxidized, and then carbonized under a protective atmosphere to obtain the surface topological carbon micro-nano material.The application controls the morphology, particle size and composition by changing the type and amount of monomers, the type and proportion of solvents, and obtains the surface topological carbon micro-nano material with different compositions, morphologies and carbonization degrees after carbonization, the minimum reflection loss of which is-37.5 to-48.7 dB, and the effective absorption bandwidth is 3.8 to 6.1 GHz.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials technology, and in particular to a surface topological carbon micro / nano material, its preparation method, and its application. Background Technology

[0002] The rapid development of wireless communication technology has brought great convenience to people's production and life. However, electromagnetic pollution is becoming increasingly prominent. Electromagnetic waves not only interfere with the normal operation of precision equipment but also harm human health. Electromagnetic wave absorbing materials can reduce electromagnetic pollution to a certain extent. These materials mainly include carbon materials, MOFs, conductive polymers, and ferrites. Among them, carbon materials, as a common electromagnetic wave absorbing material, possess excellent thermal stability, chemical stability, low density, large specific surface area, and high carrier mobility, and are often used in research on absorption performance. However, the biggest problem with carbon materials as absorbers is their narrow absorption bandwidth, which cannot meet the requirements of practical applications. Common improvement schemes involve changing the conductivity, dipoles, interface, and defect degree of carbon materials to adjust conductive loss, dipole polarization, interface polarization, and defect-induced polarization intensity, thereby adjusting the electromagnetic wave absorption performance. Furthermore, research has found that controlling the composition and morphology of materials can also improve the effective absorption bandwidth and reflection loss of carbon materials to a certain extent. Therefore, how to control the material composition and how to design the material morphology have become urgent technical problems to be solved in the field of electromagnetic wave absorbing materials. Summary of the Invention

[0003] Therefore, starting with the design of the material composition, and based on summarizing a large number of experimental results, the inventors finally completed this invention through extensive experimental research and analysis.

[0004] The purpose of this invention is to provide a surface topological carbon micro / nano material, its preparation method, and its application, thereby solving the problem that existing carbon materials have narrow absorption bandwidth and cannot meet the application requirements in electromagnetic wave absorption.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing surface topological carbon micro / nanomaterials, comprising the following steps:

[0007] (1) By mass fraction, 3-15 parts of acrylonitrile, 0.1-2 parts of the first carbon-carbon double bond unsaturated monomer, 30-70 parts of the first solvent and 0.01-0.5 parts of the first initiator are mixed and subjected to precipitation polymerization reaction to obtain the first powder;

[0008] By mass, 2 parts of the first powder, 50-100 parts of the second solvent, 0.5-2.5 parts of the second carbon-carbon double bond unsaturated monomer and 0.1-0.3 parts of the second initiator are mixed and seeded polymerization is carried out to obtain carbon microsphere precursor powder.

[0009] (2) The carbon microsphere precursor powder obtained in step (1) is pre-oxidized and then carbonized under a protective atmosphere to obtain surface topological carbon micro-nano materials.

[0010] In step (1), the first solvent is a mixture of 25 to 45 parts of ester solvent and 5 to 25 parts of other solvents.

[0011] Preferably, in the method for preparing a surface topological carbon micro / nanomaterial, in step (1), the first carbon-carbon double bond unsaturated monomer and the second carbon-carbon double bond unsaturated monomer are independently one or more of the following: acrylonitrile, styrene, α-methylstyrene, divinylbenzene, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, butyl methacrylate, glycidyl methacrylate, dodecyl acrylate, dodecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, acrylamide, N-(hydroxymethyl)acrylamide, allyl methacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, cyclohexyl methacrylate, 4-acryloylmorpholine, isobornyl acrylate, and isobornyl methacrylate.

[0012] Preferably, in the method for preparing a surface topological carbon micro / nano material, the ester solvent includes one or more of ethyl acetate, ethyl formate, butyl acetate, methyl acetate, isoamyl acetate, and diethyl carbonate, and the other solvents include one or more of methanol, ethanol, isopropanol, butanol, acetonitrile, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane; in step (1), the second solvent includes one or more of methanol, ethanol, isopropanol, butanol, acetonitrile, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, butyl acetate, sulfolane, dimethyl sulfoxide, and water.

[0013] Preferably, in the method for preparing a surface topological carbon micro / nano material, in step (1), the first initiator and the second initiator are independently azobisisobutyronitrile, azobisisoheptanenitrile, azobisisobutyramidine hydrochloride, dimethyl azobisisobutyrate, or benzoyl peroxide.

[0014] Preferably, in the method for preparing a surface topological carbon micro / nano material, the temperature of the precipitation polymerization reaction in step (1) is 65-80°C, and the time of the precipitation polymerization reaction in step (1) is 3-6 hours; the temperature of the seed polymerization reaction in step (1) is 70-85°C, and the time of the seed polymerization reaction in step (1) is 3-6 hours.

[0015] Preferably, in the method for preparing a surface topological carbon micro / nano material, the pre-oxidation temperature in step (2) is 200-300℃, the pre-oxidation time in step (2) is 1-2h, and the heating rate of the pre-oxidation in step (2) is 0.2-5℃ / min.

[0016] Preferably, in the method for preparing a surface topological carbon micro / nano material, the carbonization temperature in step (2) is 700–1100 °C, the carbonization time in step (2) is 1–3 h, and the heating rate in step (2) is 1–5 °C / min.

[0017] Preferably, in the method for preparing a surface topological carbon micro / nanomaterial, the particle size of the carbon microsphere precursor powder in step (1) is 0.3–2.5 μm.

[0018] The present invention also provides a method for preparing the aforementioned surface topological carbon micro / nanomaterials, wherein the particle size of the surface topological carbon micro / nanomaterials is 0.7–1.7 μm.

[0019] The present invention also provides an application of the aforementioned surface topological carbon micro / nanomaterials in the preparation of microwave absorbing materials.

[0020] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) This invention prepares surface topological carbon micro- and nanomaterials. By changing the monomer type, monomer amount, solvent ratio, and solvent type, the morphology, particle size, and composition of polymer microspheres can be controlled to give them different advantages. By controlling different calcination procedures, surface topological carbon micro- and nanomaterials with different compositions, morphologies, and carbonization degrees can be obtained. This invention has the advantages of high yield, simple process flow, and the ability to meet the needs of large-scale production. Currently, the maximum production capacity of the scheme of this invention in a single batch and single reactor can reach 3L.

[0022] (2) The present invention investigated the microwave absorption performance of the prepared surface topological carbon micro-nano materials. Under the condition of matching thickness of 1.5 to 5.5 mm, in the frequency range of 2 to 18 GHz, the minimum reflection loss of the prepared microwave absorbing material is -37.5 to -48.7 dB, and the effective absorption bandwidth is 3.8 to 6.1 GHz. This shows that the surface topological carbon micro-nano materials prepared by the present invention have the advantages of thin thickness and strong loss. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0024] Figure 1 Here is a SEM image of the carbon microsphere precursor powder obtained in step (1) of Example 1;

[0025] Figure 2 SEM image of the surface topological carbon micro / nanomaterials obtained in Example 1;

[0026] Figure 3 The image shows the SEM image of the carbon microsphere precursor powder obtained in step (1) of Example 2.

[0027] Figure 4 SEM image of the surface topological carbon micro / nanomaterials obtained in Example 2;

[0028] Figure 5 Here is a SEM image of the carbon microsphere precursor powder obtained in step (1) of Example 3;

[0029] Figure 6 SEM image of the surface topological carbon micro / nanomaterials obtained in Example 3;

[0030] Figure 7 The image shows the SEM image of the carbon microsphere precursor powder obtained in step (1) of Example 4.

[0031] Figure 8 SEM image of the surface topological carbon micro / nanomaterials obtained in Example 4;

[0032] Figure 9 Here is a SEM image of the carbon microsphere precursor powder obtained in step (1) of Example 5;

[0033] Figure 10 SEM image of the surface topological carbon micro / nanomaterials obtained in Example 5;

[0034] Figure 11 Here is a SEM image of the carbon microsphere precursor powder obtained in step (1) of Example 6;

[0035] Figure 12SEM image of the surface topological carbon micro / nanomaterials obtained in Example 6;

[0036] Figure 13 The reflection loss diagram of the absorbing material obtained in Example 1 is shown.

[0037] Figure 14 The reflection loss diagram of the absorbing material obtained in Example 2 is shown.

[0038] Figure 15 The reflection loss diagram of the absorbing material obtained in Example 3 is shown.

[0039] Figure 16 The reflection loss diagram of the absorbing material obtained in Example 4 is shown.

[0040] Figure 17 The reflection loss diagram of the absorbing material obtained in Example 5 is shown.

[0041] Figure 18 The reflection loss diagram of the absorbing material obtained in Example 6 is shown.

[0042] Figure 19 The image shows the SEM image of the first powder obtained in step (1) of Example 7.

[0043] Figure 20 The image shows the SEM image of the first powder obtained in step (1) of Example 8.

[0044] Figure 21 The image shows the SEM image of the first powder obtained in step (1) of Example 9.

[0045] Figure 22 The image shows the SEM image of the first powder obtained in step (1) of Example 10.

[0046] Figure 23 The image shows the SEM image of the first powder obtained in step (1) of Example 11.

[0047] Figure 24 The image shows the SEM image of the first powder obtained in step (1) of Example 12.

[0048] Figure 25 The image shows the SEM image of the first powder obtained in step (1) of Example 13. Detailed Implementation

[0049] This invention provides a method for preparing surface topological carbon micro / nanomaterials, comprising the following steps:

[0050] (1) By mass fraction, 3-15 parts of acrylonitrile, 0.1-2 parts of the first carbon-carbon double bond unsaturated monomer, 30-70 parts of the first solvent and 0.01-0.5 parts of the first initiator are mixed and subjected to precipitation polymerization reaction to obtain the first powder;

[0051] By mass, 2 parts of the first powder, 50-100 parts of the second solvent, 0.5-2.5 parts of the second carbon-carbon double bond unsaturated monomer and 0.1-0.3 parts of the second initiator are mixed and seeded polymerization is carried out to obtain carbon microsphere precursor powder.

[0052] (2) The carbon microsphere precursor powder obtained in step (1) is pre-oxidized and then carbonized under a protective atmosphere to obtain surface topological carbon micro-nano materials.

[0053] In step (1), the first solvent is a mixture of 25 to 45 parts of ester solvent and 5 to 25 parts of other solvents.

[0054] In this invention, the first carbon-carbon double bond unsaturated monomer and the second carbon-carbon double bond unsaturated monomer in step (1) are preferably one or more of acrylonitrile, styrene, α-methylstyrene, divinylbenzene, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, butyl methacrylate, glycidyl methacrylate, dodecyl acrylate, dodecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, acrylamide, N-(hydroxymethyl)acrylamide, allyl methacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, cyclohexyl methacrylate, 4-acryloylmorpholine, isobornyl acrylate, and isobornyl methacrylate. More preferably, they are one or more of styrene, α-methylstyrene, divinylbenzene, methacrylic acid, acrylic acid, acrylamide, N-(hydroxymethyl)acrylamide, 4-acryloylmorpholine, isobornyl acrylate, and isobornyl methacrylate. More preferably, they are one or more of styrene and divinylbenzene.

[0055] In the technical solution of this invention, acrylonitrile, the first carbon-carbon double bond unsaturated monomer, and the second carbon-carbon double bond unsaturated monomer play a role in changing the morphology and composition of the carbon microsphere precursor powder: acrylonitrile provides abundant N heteroatoms when preparing carbon materials, which can improve the structure of carbon materials; the bifunctional monomer can play a cross-linking role and increase the rigidity of the coating layer; and the methacrylic acid monomer can increase the number of oxygen atoms in the product.

[0056] In this invention, the ester solvent preferably includes one or more of ethyl acetate, ethyl formate, butyl acetate, methyl acetate, isoamyl acetate, and diethyl carbonate, more preferably one or more of ethyl acetate, ethyl formate, butyl acetate, and methyl acetate, and more preferably ethyl acetate.

[0057] In this invention, the other solvents preferably include one or more of methanol, ethanol, isopropanol, butanol, acetonitrile, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane, more preferably one or more of methanol, ethanol, butanol, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide, and more preferably N,N-dimethylformamide.

[0058] In the technical solution of the present invention, the first solvent in step (1) can appropriately change the surface morphology and particle size of the product to better achieve monomer dissolution and product separation.

[0059] In this invention, the second solvent in step (1) preferably includes one or more of methanol, ethanol, isopropanol, butanol, acetonitrile, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, butyl acetate, sulfolane, dimethyl sulfoxide, and water, more preferably one or more of methanol, ethanol, butanol, N,N-dimethylformamide, ethyl acetate, dimethyl sulfoxide, and water, and more preferably one or more of ethanol and water.

[0060] In this invention, the first initiator and the second initiator in step (1) are independently preferred to be azobisisobutyronitrile, azobisisoheptanenitrile, azobisisobutyramidine hydrochloride, dimethyl azobisisobutyrate or benzoyl peroxide, more preferably azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate or benzoyl peroxide, and more preferably azobisisobutyronitrile.

[0061] In the technical solution of the present invention, the role of the first initiator and the second initiator in the preparation of carbon microsphere precursor powder is that they decompose and generate free radicals, which initiate monomer polymerization.

[0062] The raw materials used in this invention are all products currently available on the market.

[0063] In this invention, the mass fraction of acrylonitrile in step (1) is preferably 4 to 12 parts, more preferably 6 to 10 parts, and even more preferably 8 parts. If the mass fraction of acrylonitrile is less than 2 parts, the product obtained is not granular; if it is more than 20 parts, the product will splash within a short time, making the reaction unable to proceed normally.

[0064] In this invention, the mass fraction of the first carbon-carbon double bond unsaturated monomer in step (1) is preferably 0.3 to 1.5 parts, more preferably 0.7 to 1 part, and even more preferably 0.8 parts. If the mass fraction of the first carbon-carbon double bond unsaturated monomer is less than 0.01 parts, it will not affect the original morphology of the product; if it is more than 2.5 parts, it will cause the first powder to agglomerate severely.

[0065] In this invention, the mass fraction of the first solvent in step (1) is preferably 35 to 60 parts, more preferably 45 to 55 parts, and even more preferably 50 parts.

[0066] In this invention, the mass fraction of the ester solvent is preferably 30-45 parts, more preferably 37.5-45 parts, and even more preferably 37.5 parts. The mass fraction of the other solvent is preferably 5-20 parts, more preferably 5-12.5 parts, and even more preferably 12.5 parts. Taking the total mass fraction of the first solvent as 100%, if the content of the ester solvent is less than 50%, the first powder cannot be obtained; if it is greater than 90%, the product morphology is relatively fixed, and the adjustable range is small.

[0067] In this invention, the mass fraction of the first initiator in step (1) is preferably 0.04 to 0.3 parts, more preferably 0.08 to 0.15 parts, and even more preferably 0.095 parts. If the mass fraction of the first initiator is less than 0.01 parts, the reaction will not proceed; if it is greater than 1 part, the product will undergo explosive polymerization.

[0068] In this invention, the mass fraction of the second solvent in step (1) is preferably 75 to 100 parts, more preferably 85 to 100 parts, and even more preferably 100 parts. If the mass fraction of the second solvent is less than 30 parts, the product will agglomerate; if it is more than 150 parts, the monomers are difficult to polymerize, making the reaction unable to proceed normally.

[0069] In this invention, the mass fraction of the second carbon-carbon double-bonded unsaturated monomer in step (1) is preferably 0.8 to 2 parts, more preferably 1 to 2 parts, and even more preferably 2 parts. If the mass fraction of the second carbon-carbon double-bonded unsaturated monomer is less than 0.3 parts, polymerization will not occur due to the low monomer concentration; if it is greater than 2.5 parts, the carbon microsphere precursor powder will undergo severe agglomeration.

[0070] In this invention, the mass fraction of the second initiator in step (1) is preferably 0.12 to 0.25 parts, more preferably 0.125 to 0.2 parts, and even more preferably 0.2 parts. If the mass fraction of the second initiator is less than 0.1 parts, the reaction will not proceed; if it is greater than 1 part, the product will undergo explosive polymerization.

[0071] In this invention, the temperature of the precipitation polymerization reaction in step (1) is preferably 65-80°C, more preferably 70-75°C, and even more preferably 75°C; the time of the precipitation polymerization reaction in step (1) is preferably 3-6 hours, more preferably 3-4.5 hours, and even more preferably 3 hours. If the temperature of the precipitation polymerization reaction is below 65°C, the reaction will not proceed; if it is above 85°C, explosive polymerization will occur.

[0072] In this invention, the precipitation polymerization reaction in step (1) preferably further includes vacuum filtration. This invention does not limit the method of vacuum filtration; any method well-known to those skilled in the art can be used.

[0073] In this invention, the temperature of the seed polymerization reaction in step (1) is preferably 70-85°C, more preferably 70-75°C, and even more preferably 75°C; the time of the seed polymerization reaction in step (1) is preferably 3-6 hours, more preferably 3-4.5 hours, and even more preferably 3 hours. If the temperature of the seed polymerization reaction is below 65°C, the reaction will not proceed; if it is above 90°C, explosive polymerization will occur.

[0074] In this invention, the seed polymerization reaction in step (1) preferably further includes filtration and washing. This invention does not limit the method of filtration and washing; any method well known to those skilled in the art can be used.

[0075] In this invention, the particle size of the carbon microsphere precursor powder in step (1) is preferably 0.3–2.5 μm. The surface of the carbon microsphere precursor powder exhibits particle accumulation or a thin layer.

[0076] In this invention, the pre-oxidation and carbonization in step (2) are preferably carried out in a tubular furnace.

[0077] In this invention, the pre-oxidation temperature in step (2) is preferably 200–300°C, more preferably 250–300°C, and even more preferably 300°C; the pre-oxidation time in step (2) is preferably 1–2 h, more preferably 1.5–2 h, and even more preferably 2 h; the heating rate in step (2) is preferably 0.2–5°C / min, more preferably 0.5–2°C / min, and even more preferably 1°C / min. The purpose of pre-oxidation in this invention is to enable polyacrylonitrile to crosslink into rings, thereby improving the stability of carbon micro / nanomaterials.

[0078] In this invention, the protective atmosphere in step (2) is preferably nitrogen or argon, and more preferably argon.

[0079] In this invention, the carbonization temperature in step (2) is preferably 700–1100°C, more preferably 900–1100°C, and even more preferably 900°C; the carbonization time in step (2) is preferably 1–3 h, more preferably 1.5–2.5 h, and even more preferably 2 h; the heating rate in step (2) is preferably 1–5°C / min, more preferably 1–3°C / min, and even more preferably 1°C / min. If the carbonization temperature is below 600°C, the carbon material obtained will have a low degree of carbonization, affecting the material's conductivity loss and reducing its electromagnetic wave absorption performance; if the carbonization temperature is above 1100°C, the graphitization degree of the carbon material will be too high, resulting in impedance mismatch and hindering electromagnetic wave absorption.

[0080] The present invention also provides a method for preparing the aforementioned surface topological carbon micro / nanomaterials.

[0081] In this invention, the particle size of the surface topological carbon micro / nanomaterial is preferably 0.7–1.7 μm.

[0082] This invention also provides an application of the aforementioned surface topological carbon micro / nanomaterials in the preparation of microwave absorbing materials. This invention does not limit the preparation method of the microwave absorbing material; any method well-known to those skilled in the art can be used.

[0083] Specifically, in the embodiments of the present invention, the method for preparing the microwave absorbing material includes the following steps:

[0084] Topological carbon micro / nanomaterials on the surface of the microwave absorbing agent are mixed with molten paraffin at a mass ratio of 1:5 to 8 and pressed into coaxial rings to obtain the microwave absorbing material.

[0085] The present invention does not limit the outer diameter and inner diameter of the coaxial ring; any solution well known to those skilled in the art can be used. Specifically, in the embodiments of the present invention, the outer diameter of the coaxial ring is 7.00 mm and the inner diameter is 3.04 mm.

[0086] In this invention, within a matching thickness of 1.5 to 5.5 mm and a frequency range of 2 to 18 GHz, the minimum reflection loss of the absorbing material is -37.5 to -48.7 dB, and the effective absorption bandwidth of the absorbing material is 3.8 to 6.1 GHz.

[0087] 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.

[0088] Example 1

[0089] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0090] (1) By mass, 128 parts acrylonitrile, 6.4 parts divinylbenzene, 600 parts ethyl acetate, 200 parts N,N-dimethylformamide and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder.

[0091] By mass, 2 parts of the first powder were dispersed in a mixed solvent of 95 parts ethanol and 5 parts deionized water. Then, 1 part divinylbenzene and 0.2 parts azobisisobutyronitrile were added, and the mixture was reacted at 75°C for 3 hours. After filtration and washing, carbon microsphere precursor powder was obtained, as shown below. Figure 1 As shown, its particle size is 1.1–1.5 μm;

[0092] (2) The carbon microsphere precursor powder obtained in step (1) was pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours under argon protection at a heating rate of 1℃ / min to 900℃, thereby obtaining surface topological carbon micro / nanomaterials, such as... Figure 2 As shown, the product morphology is well maintained, with a network morphology (the surface is covered with grooves), and the particle size is reduced to 0.7-0.9 μm.

[0093] Example 2

[0094] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0095] (1) By mass, 128 parts acrylonitrile, 6.4 parts divinylbenzene, 600 parts ethyl acetate, 200 parts N,N-dimethylformamide and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder.

[0096] By mass, 2 parts of the first powder were dispersed in a mixed solvent of 90 parts ethanol and 10 parts deionized water. Then, 1 part divinylbenzene and 0.2 parts azobisisobutyronitrile were added, and the mixture was reacted at 75°C for 3 hours. After filtration and washing, carbon microsphere precursor powder was obtained, as shown below. Figure 3 As shown, its particle size is 1.1–1.5 μm;

[0097] (2) The carbon microsphere precursor powder obtained in step (1) was pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours under argon protection at a heating rate of 1℃ / min to 900℃, thereby obtaining surface topological carbon micro / nanomaterials, such as... Figure 4As shown, the product maintains a good morphology, with grooves on the surface and a small amount of polyvinylbenzene microspheres attached, with the particle size reduced to 0.7-0.9 μm.

[0098] Example 3

[0099] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0100] (1) By mass, 128 parts acrylonitrile, 6.4 parts divinylbenzene, 600 parts ethyl acetate, 200 parts N,N-dimethylformamide and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder.

[0101] By mass, 2 parts of the first powder were dispersed in 100 parts of ethanol, followed by the addition of 1.7 parts of divinylbenzene and 0.2 parts of azobisisobutyronitrile. The mixture was reacted at 75°C for 3 hours, filtered, and washed to obtain the carbon microsphere precursor powder. Figure 5 As shown, the particle size is 1.1–1.5 μm, and the product is almost spherical;

[0102] (2) The carbon microsphere precursor powder obtained in step (1) was pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours under argon protection at a heating rate of 1℃ / min to 900℃, thereby obtaining surface topological carbon micro / nanomaterials, such as... Figure 6 As shown, the product morphology is well maintained, with a small number of grooves on the surface, slight adhesion of the product, and the particle size is reduced to 0.7-0.9 μm.

[0103] Example 4

[0104] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0105] (1) By mass, 128 parts acrylonitrile, 4 parts divinylbenzene, 11.2 parts styrene, 720 parts ethyl acetate, 80 parts N,N-dimethylformamide and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder.

[0106] By mass, 8 parts of the first powder were dispersed in 300 parts of ethanol, followed by the addition of 8 parts of divinylbenzene and 0.5 parts of azobisisobutyronitrile. The mixture was reacted at 75°C for 3 hours, filtered, and washed to obtain the carbon microsphere precursor powder. Figure 7 As shown, the particle size is 2.2–2.5 μm, the product is slightly rounded, and there is slight adhesion;

[0107] (2) The carbon microsphere precursor powder obtained in step (1) was pre-oxidized in a tube furnace at a heating rate of 1℃ / min to 300℃ for 2 hours, and then carbonized at a heating rate of 1℃ / min to 1000℃ for 2 hours under argon protection to obtain surface topological carbon micro / nanomaterials, such as... Figure 8 As shown, the product morphology is well maintained, the product surface is raised, slightly adhered, and the particle size is reduced to 1.5-1.7 μm.

[0108] Example 5

[0109] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0110] (1) By mass, 128 parts acrylonitrile, 4 parts divinylbenzene, 11.2 parts styrene, 720 parts ethyl acetate, 80 parts N,N-dimethylformamide and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder.

[0111] By mass, 8 parts of the first powder were dispersed in 300 parts of ethanol, followed by the addition of 5 parts of divinylbenzene and 0.5 parts of azobisisobutyronitrile. The mixture was reacted at 75°C for 3 hours, filtered, and washed to obtain the carbon microsphere precursor powder. Figure 9 As shown, the particle size is 2.2–2.5 μm, and the product is somewhat rounded;

[0112] (2) The carbon microsphere precursor powder obtained in step (1) was pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours under argon protection at a heating rate of 1℃ / min to 1100℃, resulting in surface topological carbon micro / nanomaterials, such as... Figure 10 As shown, the product morphology is well maintained, with surface wrinkles, slight adhesion, and particle size reduced to 1.5–1.7 μm.

[0113] Example 6

[0114] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0115] (1) By mass, 128 parts acrylonitrile, 4 parts divinylbenzene, 11.2 parts styrene, 720 parts ethyl acetate, 80 parts N,N-dimethylformamide and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder.

[0116] By mass, 8 parts of the first powder were dispersed in 300 parts of ethanol, followed by the addition of 8 parts of divinylbenzene and 0.5 parts of azobisisobutyronitrile. The mixture was reacted at 75°C for 3 hours, filtered, and washed to obtain the carbon microsphere precursor powder. Figure 11As shown, the particle size is 2.2–2.5 μm, the product is slightly rounded, and there is slight adhesion;

[0117] (2) The carbon microsphere precursor powder obtained in step (1) was pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours under argon protection at a heating rate of 1℃ / min to 900℃, thereby obtaining surface topological carbon micro / nanomaterials, such as... Figure 12 As shown, the product morphology is well maintained, with slight surface wrinkles and a particle size reduced to 1.5–1.7 μm.

[0118] Application Example 1

[0119] This application example provides a method for preparing a microwave absorbing material, including the following steps:

[0120] The surface topological carbon micro / nano material prepared in Example 1 was mixed with paraffin at a mass ratio of 1:5 in a centrifuge tube. The centrifuge tube was heated to 80°C using a German Elma Select ultrasonic cleaner. After the paraffin was completely melted, the mixture was poured into a mold. The mold was then removed and cooled to room temperature to obtain the microwave absorbing material.

[0121] The absorbing material was pressed into a coaxial ring with an outer diameter of 7.0 mm and an inner diameter of 3.04 mm. The electromagnetic parameters of the absorbing material were tested under normal temperature conditions using an Agilent PNA Network Analyzer N5224A vector network analyzer. The reflection loss diagram of the absorbing material was calculated according to formulas 1 and 2.

[0122]

[0123]

[0124] In formulas 1 and 2, Z in Z represents input impedance, Z0 represents free space impedance, d represents sample thickness, f represents frequency, c represents the speed of light in vacuum, and ε represents the input impedance. r μ represents the complex permittivity. r Represents complex permeability.

[0125] The reflection loss diagram of the absorbing material obtained from Example 1 is shown below. Figure 13 As shown. By Figure 13 It can be seen that the best wave absorption performance of the surface topological carbon micro / nano material obtained in Example 1 is that under the conditions of matching thickness of 2.5 mm and frequency of 12.24 GHz, the minimum reflection loss is -44.7 dB and the effective absorption bandwidth is 6.1 GHz.

[0126] Application Example 2

[0127] This application example provides a method for preparing a microwave absorbing material, including the following steps:

[0128] The surface topological carbon micro / nano material prepared in Example 2 was mixed with paraffin at a mass ratio of 1:5 in a centrifuge tube. The centrifuge tube was heated to 80°C using a German Elma Select ultrasonic cleaner. After the paraffin was completely melted, the mixture was poured into a mold. The mold was then removed and cooled to room temperature to obtain the microwave absorbing material.

[0129] The electromagnetic parameters of the absorbing material in Application Example 2 were tested using the method described in Application Example 1, and the reflection loss diagram was calculated. The results are as follows: Figure 14 As shown. By Figure 14 It can be seen that the best wave absorption performance of the surface topological carbon micro / nano material obtained in Example 2 is that, under the conditions of a matching thickness of 2.5 mm and a frequency of 13.84 GHz, the minimum reflection loss is -48.7 dB and the effective absorption bandwidth is 5 GHz.

[0130] Application Example 3

[0131] This application example provides a method for preparing a microwave absorbing material, including the following steps:

[0132] The surface topological carbon micro / nano material prepared in Example 3 was mixed with paraffin at a mass ratio of 1:5 in a centrifuge tube. The centrifuge tube was heated to 80°C using a German Elma Select ultrasonic cleaner. After the paraffin was completely melted, the mixture was poured into a mold. The mold was then removed and cooled to room temperature to obtain the microwave absorbing material.

[0133] The electromagnetic parameters of the absorbing material in Application Example 3 were tested using the method described in Application Example 1, and the reflection loss diagram was calculated. The results are as follows: Figure 15 As shown. By Figure 15 It can be seen that the best wave absorption performance of the surface topological carbon micro / nanomaterial obtained in Example 3 is that, under the conditions of a matching thickness of 2 mm and a frequency of 14.48 GHz, the minimum reflection loss is -43.4 dB and the effective absorption bandwidth is 4.29 GHz.

[0134] Application Example 4

[0135] This application example provides a method for preparing a microwave absorbing material, including the following steps:

[0136] The surface topological carbon micro / nano material prepared in Example 4 was mixed with paraffin at a mass ratio of 1:8 in a centrifuge tube. The centrifuge tube was heated to 80°C using a German Elma Select ultrasonic cleaner. After the paraffin was completely melted, the mixture was poured into a mold. The mold was then removed and cooled to room temperature to obtain the microwave absorbing material.

[0137] The electromagnetic parameters of the absorbing material in Application Example 4 were tested using the method described in Application Example 1, and the reflection loss diagram was calculated. The results are as follows: Figure 16 As shown. By Figure 16 It can be seen that the best wave absorption performance of the surface topological carbon micro / nanomaterial obtained in Example 4 is that, under the conditions of a matching thickness of 2 mm and a frequency of 13.52 GHz, the minimum reflection loss is -41 dB and the effective absorption bandwidth is 3.8 GHz.

[0138] Application Example 5

[0139] This application example provides a method for preparing a microwave absorbing material, including the following steps:

[0140] The surface topological carbon micro / nano material prepared in Example 5 was mixed with paraffin at a mass ratio of 1:8 in a centrifuge tube. The centrifuge tube was heated to 80°C using a German Elma Select ultrasonic cleaner. After the paraffin was completely melted, the mixture was poured into a mold. The mold was then removed and cooled to room temperature to obtain the microwave absorbing material.

[0141] The electromagnetic parameters of the absorbing material in Application Example 5 were tested using the method described in Application Example 1, and the reflection loss diagram was calculated. The results are as follows: Figure 17 As shown. By Figure 17 It can be seen that the best wave absorption performance of the surface topological carbon micro / nano material obtained in Example 5 is that, under the conditions of a matching thickness of 2 mm and a frequency of 13.84 GHz, the minimum reflection loss is -37.5 dB and the effective absorption bandwidth is 4.4 GHz.

[0142] Application Example 6

[0143] This application example provides a method for preparing a microwave absorbing material, including the following steps:

[0144] The surface topological carbon micro / nano material prepared in Example 6 was mixed with paraffin at a mass ratio of 1:8 in a centrifuge tube. The centrifuge tube was heated to 80°C using a German Elma Select ultrasonic cleaner. After the paraffin was completely melted, the mixture was poured into a mold. The mold was then removed and cooled to room temperature to obtain the microwave absorbing material.

[0145] The electromagnetic parameters of the absorbing material in Application Example 6 were tested using the method described in Application Example 1, and the reflection loss diagram was calculated. The results are as follows: Figure 18 As shown. By Figure 18 It can be seen that the best wave absorption performance of the surface topological carbon micro / nanomaterial obtained in Example 6 is that, under the conditions of a matching thickness of 2.5 mm and a frequency of 12.56 GHz, the minimum reflection loss is -44.4 dB and the effective absorption bandwidth is 4.1 GHz.

[0146] Example 7

[0147] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0148] (1) By mass, 4 parts acrylonitrile, 45 parts ethyl acetate, 5 parts N,N-dimethylformamide, and 0.2 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. After filtration, the first powder was obtained, as shown in the figure. Figure 19 As shown, the product has a uniform morphology, is a geometric shape composed of inserts, and has a particle size of about 0.6 μm.

[0149] By mass, 2 parts of the first powder were dispersed in 100 parts of ethyl acetate, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0150] (2) The carbon microsphere precursor powder obtained in step (1) is heated to 300℃ in a tube furnace at a heating rate of 1℃ / min for 2h for pre-oxidation, and then heated to 1100℃ at a heating rate of 1℃ / min for 2h for carbonization under the protection of argon to obtain surface topological carbon micro-nano materials.

[0151] Example 8

[0152] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0153] (1) By mass, 4 parts acrylonitrile, 45 parts ethyl acetate, 5 parts ethanol, and 0.2 parts azobisisobutyronitrile were reacted in a three-necked flask at 75°C for 3 hours. After filtration, the first powder was obtained, as shown in the figure. Figure 20 As shown, the product has a uniform morphology, a particle size of 0.6 μm, and an angular surface.

[0154] By mass, 2 parts of the first powder were dispersed in 100 parts of ethanol, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0155] (2) The carbon microsphere precursor powder obtained in step (1) is pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours in the protection of argon at a heating rate of 1℃ / min to 900℃, so as to obtain surface topological carbon micro-nano materials.

[0156] Example 9

[0157] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0158] (1) By mass, 128 parts acrylonitrile, 4 parts divinylbenzene, 11.2 parts styrene, 720 parts ethyl acetate, 80 parts N,N-dimethylformamide, and 1.5 parts azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. After filtration, the first powder was obtained, as shown in the figure. Figure 21 As shown, the product has a uniform morphology, a particle size of 1.9–2.1 μm, and an uneven surface;

[0159] By mass, 2 parts of the first powder were dispersed in 100 parts of ethyl acetate, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0160] (2) The carbon microsphere precursor powder obtained in step (1) is heated to 300℃ in a tube furnace at a heating rate of 1℃ / min for 2h for pre-oxidation, and then heated to 1000℃ at a heating rate of 1℃ / min for 2h under the protection of argon to obtain surface topological carbon micro-nano materials.

[0161] Example 10

[0162] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0163] (1) By mass, 80 parts acrylonitrile, 300 parts ethyl acetate and 1 part azobisisobutyronitrile were mixed and reacted in a three-necked flask at 75°C for 3 hours. After filtration, the first powder was obtained, as shown in the figure. Figure 22 As shown, the product has a uniform morphology, sharp edges, and a particle size of 0.8 μm.

[0164] By mass, 2 parts of the first powder were dispersed in 100 parts of ethyl acetate, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0165] (2) The carbon microsphere precursor powder obtained in step (1) is heated to 300℃ in a tube furnace at a heating rate of 1℃ / min for 2h for pre-oxidation, and then heated to 1100℃ at a heating rate of 1℃ / min for 2h for carbonization under the protection of argon to obtain surface topological carbon micro-nano materials.

[0166] Example 11

[0167] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0168] (1) By mass, 4 parts acrylonitrile, 1 part divinylbenzene, 50 parts ethyl acetate, and 0.2 parts azobisisobutyronitrile were reacted in a three-necked flask at 75°C for 3 hours. After filtration, the first powder was obtained, as shown in the figure. Figure 23 As shown, the product has a uniform morphology, a particle size of 0.8 μm, and slight adhesion.

[0169] By mass, 2 parts of the first powder were dispersed in 100 parts of ethyl acetate, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0170] (2) The carbon microsphere precursor powder obtained in step (1) is heated to 300℃ in a tube furnace at a heating rate of 1℃ / min for 2h for pre-oxidation, and then heated to 1000℃ at a heating rate of 1℃ / min for 2h under the protection of argon to obtain surface topological carbon micro-nano materials.

[0171] Example 12

[0172] This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0173] (1) By mass, 4 parts acrylonitrile, 1 part acrylic acid, 50 parts ethyl acetate and 0.2 parts azobisisobutyronitrile were reacted in a three-necked flask at 75°C for 3 hours, and filtered to obtain the first powder, as shown in the figure. Figure 24 As shown, the product has a uniform morphology, a particle size of 0.3 μm, and slight adhesion.

[0174] By mass, 2 parts of the first powder were dispersed in 100 parts of ethyl acetate, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0175] (2) The carbon microsphere precursor powder obtained in step (1) is heated to 300℃ in a tube furnace at a heating rate of 1℃ / min for 2h for pre-oxidation, and then heated to 1000℃ at a heating rate of 1℃ / min for 2h under the protection of argon to obtain surface topological carbon micro-nano materials.

[0176] Example 13

[0177] (1) This embodiment provides a method for preparing surface topological carbon micro / nanomaterials, including the following steps:

[0178] By mass, 4 parts acrylonitrile, 0.3 parts styrene, 50 parts ethyl acetate, and 0.2 parts azobisisobutyronitrile were reacted in a three-necked flask at 75°C for 3 hours. The mixture was then filtered to obtain the first powder, as shown below. Figure 25 As shown, the product has a uniform morphology and a particle size of 1.2 μm;

[0179] By mass, 2 parts of the first powder were dispersed in 100 parts of ethyl acetate, and 1 part of divinylbenzene and 0.2 parts of azobisisobutyronitrile were added. The mixture was reacted at 75°C for 3 hours, filtered and washed to obtain carbon microsphere precursor powder.

[0180] (2) The carbon microsphere precursor powder obtained in step (1) is pre-oxidized for 2 hours in a tube furnace at a heating rate of 1℃ / min to 300℃, and then carbonized for 2 hours in the protection of argon at a heating rate of 1℃ / min to 900℃, so as to obtain surface topological carbon micro-nano materials.

[0181] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a surface topological carbon micro / nanomaterial in the preparation of microwave absorbing materials, characterized in that, The preparation method of the surface topological carbon micro / nanomaterial includes the following steps: (1) By mass fraction, 3-15 parts of acrylonitrile, 0.1-2 parts of the first carbon-carbon double bond unsaturated monomer, 30-70 parts of the first solvent and 0.01-0.5 parts of the first initiator are mixed and subjected to precipitation polymerization reaction to obtain the first powder; By mass, 2 parts of the first powder, 50-100 parts of the second solvent, 0.5-2.5 parts of the second carbon-carbon double bond unsaturated monomer and 0.1-0.3 parts of the second initiator are mixed and seeded polymerization reaction is carried out to obtain carbon microsphere precursor powder. (2) The carbon microsphere precursor powder obtained in step (1) is pre-oxidized and then carbonized under a protective atmosphere to obtain surface topological carbon micro-nano materials. Wherein, in step (1), the first carbon-carbon double bond unsaturated monomer and the second carbon-carbon double bond unsaturated monomer are independently selected from one or more of the following: acrylonitrile, styrene, α-methylstyrene, divinylbenzene, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, butyl methacrylate, glycidyl methacrylate, dodecyl acrylate, dodecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, acrylamide, N-(hydroxymethyl)acrylamide, allyl methacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, cyclohexyl methacrylate, 4-acryloylmorpholine, isobornyl acrylate, and isobornyl methacrylate. Step (1) The first solvent is a mixture of 25-45 parts of ester solvent and 5-25 parts of other solvent; The ester solvents include one or more of ethyl acetate, ethyl formate, butyl acetate, methyl acetate, isoamyl acetate, and diethyl carbonate; the other solvents include one or more of methanol, ethanol, isopropanol, butanol, acetonitrile, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane. Step (1) The second solvent includes one or more of methanol, ethanol, isopropanol, butanol, acetonitrile, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, butyl acetate, sulfolane, dimethyl sulfoxide, and water; The pre-oxidation temperature in step (2) is 200~300℃, the pre-oxidation time in step (2) is 1~2h, and the heating rate in step (2) is 0.2~5℃ / min.

2. The application as described in claim 1, characterized in that, Step (1) The first initiator and the second initiator are independent of each other, namely azobisisobutyronitrile, azobisisoheptanenitrile, azobisisobutyramidine hydrochloride, dimethyl azobisisobutyrate or benzoyl peroxide.

3. The application as described in claim 2, characterized in that, The temperature of the precipitation polymerization reaction in step (1) is 65~80℃, and the time of the precipitation polymerization reaction in step (1) is 3~6h; the temperature of the seed polymerization reaction in step (1) is 70~85℃, and the time of the seed polymerization reaction in step (1) is 3~6h.

4. The application as described in claim 1, characterized in that, The carbonization temperature in step (2) is 700~1100℃, the carbonization time in step (2) is 1~3h, and the heating rate in step (2) is 1~5℃ / min.

5. The application as described in claim 3, characterized in that, The particle size of the carbon microsphere precursor powder in step (1) is 0.3~2.5μm.

6. The application as described in any one of claims 1 to 5, characterized in that, The particle size of the surface topological carbon micro / nanomaterial is 0.7~1.7μm.

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