An electromagnetic super-surface composite coating and its preparation method and application

Abstract

The present invention discloses an electromagnetic supersurface composite coating and its preparation method and application. MXene powder and graphene oxide are first ultrasonically dispersed in an organic solvent to form a uniform suspension dispersion; terephthaloyl chloride is then added to the suspension dispersion and stirred to prepare a flocculent cross-linked product; the flocculent cross-linked product is collected and dialyzed in water to displace the organic solvent and unreacted terephthaloyl chloride; the treated product is then configured into a homogeneous colloidal aqueous solution; the homogeneous colloidal aqueous solution is printed using microelectronics technology to construct an electromagnetic supersurface pattern with array characteristics on the surface of a substrate; the pattern is then heated and dried, and then encapsulated with epoxy resin to obtain the electromagnetic supersurface composite coating. The composite coating of the present invention has the advantages of flexibility, high strength, high electromagnetic wave absorption performance, convenient preparation, and easy repair.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave absorption and electromagnetic metamaterials, and specifically relates to an electromagnetic metasurface composite coating and a preparation method and application thereof. Background Art

[0002] Electromagnetic metamaterials are a class of materials with revolutionary potential that have attracted widespread interest and research in the absorption and control of electromagnetic waves. These materials are so attractive because they possess many unique properties not possessed by traditional materials, enabling them to manipulate electromagnetic radiation in unprecedented ways.

[0003] The principle behind electromagnetic metamaterials is to manipulate the propagation and interaction of electromagnetic waves through carefully designed microstructures. These structures are typically composed of multiple microscopic units of varying types, and the geometry and arrangement of these units determine the material's electromagnetic properties. Specifically, electromagnetic metamaterials can achieve unconventional phenomena such as negative refractive index, negative diffraction, and negative refractive lenses, which are not commonly found in nature.

[0004] Electromagnetic metamaterials can achieve efficient absorption of electromagnetic waves within a specific frequency range by adjusting their structure and composition. This property has enormous potential applications in military, communications, antenna design, medical imaging, and solar energy absorption. By customizing the metamaterial's structure, researchers can achieve absorption of specific wavelengths and adjust the position and width of the absorption peak to meet specific application requirements.

[0005] The absorption properties of electromagnetic metamaterials are influenced not only by their structural design but also by the properties of the materials used and the frequency of the electromagnetic waves. Metals are commonly used in traditional electromagnetic metamaterials. Due to their electrical conductivity, they achieve high electromagnetic wave absorption performance. In recent years, researchers have improved the absorption performance of metal metamaterials, particularly in the visible and infrared spectral ranges, through methods such as micro-nanostructure design and the combination of multilayer metal films. Graphene and other two-dimensional materials are also being used in the development of electromagnetic metamaterials. These materials have unique electronic and band structures, which can be used to design metamaterials that absorb electromagnetic waves within specific frequency ranges. The ultra-thin nature of two-dimensional materials makes them promising for applications in flexible and wearable devices. Magnetic materials such as ferrites are also widely used in electromagnetic metamaterial absorption applications. These materials can absorb electromagnetic waves in the microwave and radio frequency bands and have important applications in radar stealth technology.

[0006] Overall, electromagnetic metamaterials' wave-absorbing technology represents cutting-edge research in materials science and electromagnetics, with enormous potential applications. The continued development and innovation of these materials will bring new breakthroughs and opportunities in fields such as wireless communications, electromagnetic stealth technology, and medical imaging.

[0007] However, current electromagnetic metamaterials still have problems such as unsatisfactory electromagnetic absorption performance and narrow effective absorption bandwidth. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide an electromagnetic super-surface composite coating and its preparation method and application to improve the electromagnetic absorption performance and broaden the effective absorption bandwidth.

[0009] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0010] A method for preparing an electromagnetic supersurface composite coating comprises the following steps:

[0011] S1. Ultrasonic dispersion of MXene powder and graphene oxide in an organic solvent to form a uniform suspension dispersion;

[0012] S2. The terephthaloyl chloride was added to the suspension dispersion obtained in S1 and stirred to prepare a flocculent cross-linked product;

[0013] S3 collected S2 obtained flocculent cross-linked product, dialyzed in water, displaced the organic solvent and unreacted terephthaloyl chloride, and then the treated product is configured into a homogeneous colloidal aqueous solution;

[0014] S4. The homogeneous colloidal aqueous solution obtained in S3 is used through microelectronic printing technology to construct an electromagnetic metasurface pattern with array characteristics on the surface of the substrate. After heating and drying, it is encapsulated with epoxy resin to obtain the electromagnetic metasurface composite coating.

[0015] As a further improvement, the organic solvent in S1 is dimethyl sulfoxide.

[0016] As a further improvement, the mass ratio of MXene to graphene oxide described in S1 is 10:(0.1-1.5).

[0017] As a further improvement, the mass ratio of MXene to graphene oxide described in S1 is 10:(0.8-1.2).

[0018] As a further improvement, in S2, a flocculent cross-linked product is prepared by stirring at 45 to 55 degrees Celsius.

[0019] As a further improvement, the mass ratio of phthaloyl chloride to MXene in S2 is (0.01-0.1):10.

[0020] As a further improvement, the electromagnetic metasurface pattern described in S4 is composed of 6 rows and 6 columns of structural units arranged at equal intervals to form a square pattern, and each structural unit is composed of 4 squares that are reduced in size at equal gradients and nested in sequence.

[0021] As a further improvement, the mass ratio of the total amount of MXene and graphene oxide added to the epoxy resin is (3-6):(4-7).

[0022] The present invention provides an electromagnetic super-surface composite coating, which is prepared by adopting the method described.

[0023] The present invention also provides an application of the electromagnetic super-surface composite coating in the preparation of electromagnetic absorbing materials.

[0024] The present invention overcomes the problems of low absorption performance and narrow effective absorption bandwidth caused by the large amount of MXene conductive coating material used and the impedance mismatch caused by excessively high conductivity.

[0025] In the present invention, MXene and graphene oxide are cross-linked into a colloid with graphene oxide, configured into a conductive ink, and an electromagnetic supersurface pattern with array characteristics is prepared using microelectronic printing technology. After heating and drying, it is encapsulated with epoxy resin to obtain an electromagnetic supersurface composite coating.

[0026] Graphene oxide stabilizes the MXene suspension. Further cross-linking with terephthaloyl chloride creates a stable, inkjet-printable colloidal conductive ink, facilitating subsequent fabrication. Furthermore, graphene oxide can moderately reduce the MXene's conductivity, enabling the composite coating to meet impedance matching requirements, further improving electromagnetic absorption performance and increasing the effective absorption bandwidth.

[0027] The conductive MXene forms an electromagnetic planar array structure under the action of a two-dimensional inkjet printer. The geometric characteristics of the electromagnetic resonance array pattern can cause the incident electromagnetic waves to produce destructive interference through the coupling of electric and magnetic fields, converting the electromagnetic waves into heat energy and absorbing them, giving the composite coating electromagnetic absorption properties.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) Through the cross-linking effect between terephthaloyl chloride and the hydroxyl groups on the surface of MXene and graphene oxide, the two are cross-linked to form a homogeneous conductive ink. For the first time, a conductive structure with electromagnetic resonance array pattern characteristics is prepared using two-dimensional inkjet technology;

[0030] 2) The composite coating, which is composed of an electromagnetic resonant array of MXene and graphene oxide encapsulated in an insulating epoxy resin, has excellent electromagnetic absorption properties under the mechanism of electromagnetic coupling.

[0031] 3) The MXene / epoxy resin composite coating can effectively shield and absorb electromagnetic waves, and has the characteristics of high electromagnetic absorption and wide effective absorption bandwidth. When the coating is 300μm, its maximum absorption efficiency is -26.1dB in the range of 1-18GHz, and the effective absorption bandwidth (greater than -10dB) is about 8.1;

[0032] 4) The product of the present invention has the characteristics of flexibility and high strength, and its bonding strength is greater than or equal to 25MPa (according to GB / T18240 standard);

[0033] 5) The composite coating has a simple preparation process, low cost, high performance, easy repair, and easy industrial production and commercial application. It is an excellent composite coating that can be widely used in electromagnetic wave absorption and shielding applications for wireless communications, electromagnetic stealth, and medical imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 is the electromagnetic metasurface pattern image in the sample of Example 1;

[0036] Figure 2 is a schematic diagram of the size structure of the sample of Example 1, wherein the black line width feature size is 500 microns;

[0037] Figure 3 is a SEM image of the microstructure of the portion of the sample containing MXene / graphene oxide components in Example 1;

[0038] Figure 4 is the electromagnetic absorption performance of the example sample at 1-18 GHz;

[0039] Figure 5 is the effective absorption bandwidth of the example sample (greater than -10dB). DETAILED DESCRIPTION

[0040] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0042] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0043] The present invention uses microelectronic composite printing technology to construct an electromagnetic metasurface pattern with array characteristics on the surface of a substrate by cross-linking a conductive coating formed by MXene, graphene oxide and terephthaloyl chloride. After heating and drying, it is encapsulated with epoxy resin to obtain a composite coating.

[0044] In some specific embodiments, the method for preparing the electromagnetic supersurface composite coating of the present invention comprises the following steps:

[0045] S1. Ultrasonic treatment of MXene powder in an organic solvent, followed by addition of graphene oxide, and further ultrasonic dispersion to form a uniform suspension dispersion.

[0046] The chemical formula of MXene is Ti3C2. In some embodiments, MXene is a lamellar particle with a diameter of about 40-50 microns.

[0047] The organic solvent is, for example, dimethyl sulfoxide (DMSO).

[0048] In some embodiments, the mass ratio of MXene to graphene oxide is 10:(0.1-1.5), preferably 10:(0.5-1.2), more preferably 10:(0.8-1.2), and most preferably 10:1.

[0049] To prevent rapid sedimentation of MXene powder in DMSO, graphene oxide was added as a stabilizer. In the following examples, graphene oxide was prepared by mixing 40-50 micron few-layer graphite flakes with potassium permanganate, potassium nitrate, and sulfuric acid in a mass ratio of 1:1:2:10 at 5°C for 30 minutes, then diluting the mixture in 10 volumes of water, heating and stirring at 90°C for 3 hours, and then acid-washing and water-washing.

[0050] S2. Add terephthaloyl chloride to the obtained suspension dispersion and stir at 45 to 55 degrees Celsius to obtain a flocculent cross-linked product.

[0051] The addition of terephthaloyl chloride facilitates the production of a conductive, homogeneous, colloidal aqueous solution that is easily printed on microelectronics. In some embodiments, the terephthaloyl chloride is a white, crystalline powder with a purity of 99.9%. In some embodiments, the mass ratio of terephthaloyl chloride to MXene is (0.01-0.1):10, preferably (0.03-0.08):10.

[0052] In some embodiments, the stirring time is 1 to 1.5 hours.

[0053] S3. Collect the flocculent cross-linked product and dialyze it in water to displace the organic solvent (eg, DMSO) and unreacted terephthaloyl chloride. The treated product is prepared into a homogeneous colloidal aqueous solution.

[0054] In some embodiments, the treated product is prepared into a homogeneous colloidal aqueous solution at a concentration of 12-20 mg / ml by evaporation or dropwise addition.

[0055] S4. The obtained homogeneous colloidal aqueous solution is used through microelectronic printing technology to construct an electromagnetic metasurface pattern with array characteristics on the surface of the substrate. After heating and drying, it is encapsulated with epoxy resin to obtain the electromagnetic metasurface composite coating.

[0056] In some embodiments, the microelectronic printing technology is specifically to use a two-dimensional inkjet printer to draw the configured conductive ink on the substrate into a computer-digital designed pattern.

[0057] In some embodiments, the electromagnetic metasurface pattern is a two-dimensional electromagnetic planar array structure composed of micron structural units (with a line width feature size of 500 microns), such as Figure 2 As shown, it consists of six rows and six columns of equally spaced structural units arranged in a square pattern. Each structural unit consists of four squares, each decreasing in size at an equal gradient, nested within each other to form a "U"-shaped pattern. The geometric characteristics of this electromagnetic resonance array pattern cause incident electromagnetic waves to destructively interfere through the coupling of electric and magnetic fields, dissipating the incident electromagnetic waves and achieving electromagnetic absorption performance.

[0058] The epoxy resin is completely coated on the electromagnetic metasurface pattern containing MXene and graphene oxide to form an encapsulation layer. In some embodiments, the epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.

[0059] In some embodiments, the mass ratio of the total amount of MXene and graphene oxide added (solid content of the colloidal aqueous solution) to the epoxy resin is (3-6):(4-7), preferably (4-6):(4-6), and most preferably 1:1.

[0060] During the preparation process of the present invention, other processing aids known in the prior art, such as degassing agents, curing accelerators, and reactive diluents, may also be added.

[0061] Example 1

[0062] The method for preparing the electromagnetic supersurface composite coating of this embodiment comprises the following steps:

[0063] (1) 10 g of MXene powder was ultrasonically treated in 50 ml of dimethyl sulfoxide (DMSO) solution, and then 1 g of graphene oxide was added as a stabilizer for further ultrasonic dispersion to prepare a uniform suspension dispersion;

[0064] (2) adding 0.05 g of terephthaloyl chloride to the suspension dispersion obtained in step (1), stirring at a constant speed for 1 hour at 50 degrees Celsius to obtain a flocculent cross-linked product;

[0065] (3) Collect the flocculent cross-linked product obtained in step (2), place it in a 1000 ml dialysis bag, and dialyze it in water to displace DMSO and unreacted terephthaloyl chloride. The treated product is prepared into a 20 mg / ml homogeneous colloidal aqueous solution by evaporation or dropwise addition for later use;

[0066] (4) 25 ml of the homogeneous colloidal aqueous solution obtained in step (3) was subjected to microelectronic printing technology (solid content of 0.5 g) and Figure 2 The size of the electromagnetic metasurface is constructed on the substrate surface with array characteristics, and the results are as follows Figure 1 After heating and drying, 0.5 g of epoxy resin was used for packaging to obtain the electromagnetic super surface composite coating with a coating thickness of 300 μm. The microstructure SEM image of the composite coating containing MXene / graphene oxide components is shown in FIG. Figure 3 According to GB / T 18240, the bonding strength is 25MPa 3 .

[0067] Example 2

[0068] The implementation method is the same as that of Example 1, except that the concentration of the homogeneous colloidal aqueous solution in step (3) is configured to 16 mg / ml, the epoxy resin in step (4) is changed to 0.6 g, the solid content of MXene and graphene oxide is 0.4 g, and the other components and masses remain unchanged.

[0069] Example 3

[0070] The implementation method is the same as that of Example 1, except that the concentration of the homogeneous colloidal aqueous solution in step (3) is configured to be 12 mg / ml, the epoxy resin in step (4) is changed to 0.7 g, the solid content of MXene and graphene oxide is 0.3 g, and the other components and masses remain unchanged.

[0071] Example 4

[0072] Compared with Example 1, the difference is that the graphene oxide in step (1) is changed to 0.5 g, and the other components and masses remain unchanged.

[0073] Example 5

[0074] Compared with Example 1, the difference is that: graphene oxide is not added in step (1), and other components and masses remain unchanged.

[0075] Example 6

[0076] Compared with Example 1, the difference is that this example is a pure epoxy resin coating.

[0077] The electromagnetic absorption performance test results of the composite material obtained above are shown in Figure 4 , effective absorption bandwidth see Figure 5 The electromagnetic parameter measurement method using a waveguide device in the microwave frequency band of solid materials in GB / T35679-2017 was used for testing. Based on the obtained electromagnetic parameters, the electromagnetic absorption performance and effective absorption bandwidth were calculated.

[0078] Figure 4 The test results show that the electromagnetic supersurface composite coating prepared by the present invention has the characteristics of high electromagnetic wave absorption performance. By comparing Examples 1-3 and Example 6 (pure epoxy resin coating), it can be explained that MXene and graphene oxide constitute an electromagnetic resonant planar array structure, which can effectively couple the incident electromagnetic waves, so that the composite coating produces electromagnetic wave absorption performance in the range of 1-18GHz. By comparing Example 1, Example 4 and Example 5, it can be explained that the effect of graphene oxide on the absorption performance at different addition amounts can be explained. Graphene oxide with weaker conductivity can effectively improve the electromagnetic parameters of MXene conductive ink, and the electromagnetic compatibility transition region formed between the highly conductive MXene and the insulating epoxy resin can achieve impedance matching of the composite coating, and more significantly improve the electromagnetic wave absorption characteristics.

[0079] Figure 5 The test results show that the electromagnetic supersurface composite coating prepared by the present invention has the characteristics of wide absorption bandwidth. By comparing Examples 1-2 and Example 6 (pure epoxy resin coating), it can be shown that the electromagnetic resonant planar array structure composed of MXene and graphene oxide can significantly improve the effective absorption bandwidth of the material, and as the content of MXene and graphene oxide decreases, the effective absorption bandwidth also decreases to 0. Figure 4 The effective absorption bandwidth of the composite coating is positively correlated with its electromagnetic absorption performance. A comparison of Examples 1, 4, and 5 shows that the presence of graphene oxide, thanks to the impedance matching effect, expands the material's absorption bandwidth and gives the composite coating better electromagnetic interface compatibility.

[0080] Among them, Example 1 is the best example, with the largest mixed addition amount of MXene and graphene oxide, the best electromagnetic absorption performance, and the largest effective absorption bandwidth. In Examples 2 and 3, the performance decreased when the mixed addition amount of MXene and graphene oxide was reduced.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form. Therefore, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical solution of the present invention and are based on the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing an electromagnetic super-surface composite coating, characterized in that: The following steps are included: S1. Ultrasonic dispersion of MXene powder and graphene oxide in an organic solvent to form a uniform suspension; wherein the mass ratio of MXene to graphene oxide is 10:(0.8-1.2); S2. The terephthaloyl chloride was added to the suspension dispersion obtained in S1 and stirred to prepare a flocculent cross-linked product; The mass ratio of terephthaloyl chloride to MXene is (0.01-0.1):10; S3 collected S2 obtained flocculent cross-linked product, dialyzed in water, displaced the organic solvent and unreacted terephthaloyl chloride, and then the treated product is configured into a homogeneous colloidal aqueous solution; S4. The homogeneous colloidal aqueous solution obtained in S3 is subjected to microelectronic printing technology to construct an electromagnetic metasurface pattern having array characteristics on the surface of the substrate, which is then heated and dried, and then encapsulated with epoxy resin to obtain the electromagnetic metasurface composite coating; The mass ratio of the total amount of MXene and graphene oxide added to the epoxy resin is (4-6):(4-6); The electromagnetic metasurface pattern is composed of 6 rows and 6 columns of structural units arranged in a square pattern at equal intervals, and each structural unit is composed of 4 squares that are reduced in size at equal gradients and nested in sequence. The electromagnetic super-surface composite coating is used for electromagnetic wave absorption.

2. The method for preparing the electromagnetic super surface composite coating according to claim 1, wherein: The organic solvent in S1 is dimethyl sulfoxide.

3. The method for preparing the electromagnetic super surface composite coating according to claim 1, wherein: In S2, a flocculent cross-linked product is prepared by stirring at 45 to 55 degrees Celsius.

4. An electromagnetic super surface composite coating, characterized in that: The invention is prepared by the method according to any one of claims 1 to 3.

5. Use of the electromagnetic supersurface composite coating according to claim 4 in the preparation of electromagnetic absorbing materials.

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