Preparation method of MXene-fumed silica-epoxy resin composite electromagnetic wave-absorbing material

Abstract

The invention discloses a preparation method of an MXene-fumed silica-epoxy resin composite electromagnetic wave-absorbing material, and belongs to the field of material science. The method comprises the following steps: uniformly mixing and stirring epoxy resin and a curing agent at room temperature, and then prepolymerizing at 35-45 DEG C for 1-3 hours; adding fumed silica into the MXene concentrated solution, stirring for 30-60 minutes, and standing at 2-10 DEG C for 1-3 hours to obtain MXene-fumed silica slurry; adding the mixture into the mixture, and slowly stirring at 35-45 DEG C for 0.1-0.5 h to form a dispersion system; vacuumizing to remove bubbles in the solution; heating to cure the epoxy resin in the solution; the resin is dried in a blast oven at the same temperature as the curing temperature to eliminate residual stress in the resin. According to the method disclosed by the invention, good dispersion of hydrophilic MXene in a hydrophobic epoxy resin matrix without agglomeration and self-stacking phenomena is realized by a method of directly mixing the MXene aqueous-phase dispersion liquid into the resin matrix. The epoxy resin-based composite material prepared by the invention has higher tensile strength and better mechanical stability.

Description

Technical Field

[0001] The present invention belongs to the field of materials science and relates to a method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material. Background Art

[0002] Resin-based composite materials offer low density, large relative surface area, and customizable physical properties, making them suitable for applications such as separation, filtration, sound absorption, and electromagnetic stealth. Epoxy resin, as a thermosetting resin, is an ideal matrix material for composite materials. However, conventional preparation methods have resulted in low mechanical strength, poor electrical and thermal conductivity, and difficulty in manipulating electromagnetic parameters, significantly limiting their application.

[0003] Epoxy resin, a commonly used composite matrix, exhibits excellent wave transparency and is therefore used as the base for electromagnetic absorbers. Highly conductive and ferromagnetic dopants are introduced to tailor the electromagnetic parameters of epoxy resin-based composites. However, the hydrophobic nature of epoxy resin limits the types of dopants that can be incorporated. Dopants with strong polarity, in particular, tend to aggregate within the resin matrix, significantly reducing the composite's overall electromagnetic impedance matching performance.

[0004] MXene, a two-dimensional material with excellent conductivity, is an excellent candidate for electromagnetic absorbent fillers. However, its excellent hydrophilicity and numerous polar functional groups on its surface make its dispersion in oily epoxy resins challenging. To address this, freeze-drying and surface modification methods have been used. However, these cumbersome steps significantly increase the storage time of the MXene during preparation, leading to oxidation and reduced conductivity, which in turn affects the overall electromagnetic parameters of the composite material.

[0005] Therefore, developing a fast and effective dispersion method is crucial for improving the electromagnetic absorption performance of MXene-epoxy resin composites. This invention addresses the issues of cumbersome existing MXene dispersion processes, which lead to oxidation during MXene processing, and low dispersion efficiency, which results in a high MXene loading requirement. This approach aims to shorten the process flow while further improving the dispersibility of MXene in the resin matrix, thereby reducing the required MXene loading and enabling the lightweight preparation of MXene-based electromagnetic absorbing materials. Summary of the Invention

[0006] The present invention aims to address the poor physical properties (thermal and electrical conductivity), MXene dispersibility, and electromagnetic absorption performance of existing MXene-epoxy resin-based composites. This method provides a method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorber. This method utilizes the shear rheological properties of silica to convert a MXene aqueous dispersion into a MXene slurry, dynamically trapping water molecules between the MXene@SiO2 flakes and preventing the agglomeration and self-stacking of the MXene flakes. Furthermore, a controllable pore-forming agent and physical property modifier for epoxy resin-based materials is prepared using a mixed slurry of MXene and fumed silica. The resulting composite material exhibits customizable mechanical strength, electrical conductivity, and thermal conductivity.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material, the method comprising the following steps:

[0009] Step 1: Mix the epoxy resin matrix and curing agent in a fixed ratio at room temperature, stir evenly, and then prepolymerize at 35-45°C for 1-3 hours;

[0010] Step 2: Add fumed silica to the concentrated MXene solution and stir for 30-60 minutes, then let it stand at 2-10°C for 1-3 hours to obtain a MXene-fumed silica slurry; wherein, silica is adsorbed on the surface of the MXene layer through electrostatic adsorption and intermolecular forces, forming a MXene@SiO2 layer with a multi-level structure.

[0011] Step 3: Add the MXene-fumed silica slurry from step 2 to the mixture from step 1 and stir slowly (<120 rpm) at 35-45°C for 0.1-0.5h to form a uniform dispersion.

[0012] Step 4: Vacuum the solution to a degree of 0.01-0.05 MPa for 0.1-1 h at a temperature of 20-35°C to remove air bubbles from the solution in step 3;

[0013] Step 5: heating the solution in step 4 to cure the epoxy resin in the solution at a temperature of 40-80°C for 24-48 hours;

[0014] Step 6: Dry the resin obtained in step 5 in a forced air oven at the same temperature as the curing temperature for 5 to 10 hours to eliminate residual stress in the resin, thereby obtaining a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material with finely controlled physical properties.

[0015] Furthermore, in step 2, the average particle size of the fumed silica is 100-500 nm.

[0016] Furthermore, in step 2, the MXene concentrated solution is prepared by etching the MAX phase Ti3AlC2 through a clay method.

[0017] Furthermore, in step 2, the concentration range of the MXene concentrated solution is 0.01~35 mg / ml.

[0018] Furthermore, in step 2, the mass ratio of the fumed silica to the MXene concentrated solution is 0.2-0.4:1. The resulting MXene-fumed silica slurry is slurry-like and exhibits good shear-thinning properties: it has no fluidity when left standing, but exhibits some fluidity when stirred.

[0019] Furthermore, in step three, the mass ratio of the MXene-fumed silica slurry to the mixture is 0.01-40:100.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention achieves good dispersion of hydrophilic MXene in a hydrophobic epoxy resin matrix without agglomeration and self-stacking by directly mixing the MXene aqueous dispersion into the resin matrix.

[0022] 2. The MXene-epoxy resin-based composite material prepared by the present invention has higher tensile strength and better mechanical stability.

[0023] 3. The electromagnetic properties of the epoxy resin-based composite material prepared by the present invention can be finely controlled by regulating the content of doped MXene, and the obtained composite material exhibits excellent electromagnetic absorption properties.

[0024] 4. The present invention introduces water into the composite material, thereby achieving uniform dispersion and stable storage of water, and utilizing the polarity of water to further enhance the dielectric loss performance of the composite material.

[0025] 5. The present invention achieves the grafting of SiO2 onto MXene sheets through electrostatic adsorption and intermolecular forces, and at the same time utilizes the shear rheological properties of silica to dynamically lock water between the MXene@SiO2 sheets, thereby achieving uniform and stable dispersion of MXene and water in the epoxy resin matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a macroscopic photo of a resin-based composite material plate;

[0027] Figure 2 is the mechanical tensile stress-strain curve of the resin-based composite material;

[0028] Figure 3 is the electromagnetic parameter diagram of the resin-based composite material corresponding to Example 1;

[0029] Figure 4 This is a graph showing the electromagnetic absorption performance of the resin-based composite material corresponding to Example 3;

[0030] Figure 5 It is the small-angle diffraction pattern of the resin-based composite material;

[0031] Figure 6 is the electromagnetic parameter diagram of the resin-based composite material corresponding to Example 2;

[0032] Figure 7 This is the electromagnetic parameter diagram of the resin-based composite material corresponding to Example 3. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0034] Example 1:

[0035] Step 1: Mix 35g of epoxy resin matrix and 10.5g of curing agent at a mass ratio of 10:3 at room temperature, stir well, and prepolymerize at 35°C for 1h;

[0036] Step 2: Add 3 g of fumed silica to 15 g of a 20 mg / g MXene concentrated solution, stir evenly, and let stand at 4 °C for 3 h to obtain a MXene-fumed silica slurry;

[0037] Step 3: Add the MXene-fumed silica slurry described in step 2 to the emulsion described in step 1 and slowly stir at 35°C for 0.2h to form a homogeneous solution;

[0038] Step 4: Vacuum the solution to 0.05 MPa for 0.1 h at 30°C to remove air bubbles from the solution in step 3.

[0039] Step 5: heating the solution in step 4 to cure the epoxy resin in the solution at 40° C. for 24 hours;

[0040] Step 6: Dry the resin described in step 5 in a forced air oven at the same temperature as the curing temperature to remove moisture in the resin pores and eliminate residual stress in the resin for 5 hours. This will produce a MXene-fumed silica-epoxy resin composite material with finely regulated physical properties. The obtained resin-based composite material exhibits good dispersion and no agglomeration occurs ( Figure 5 ).

[0041] Example 2:

[0042] Step 1: 54g of epoxy resin matrix and 16.2g of curing agent were mixed at a mass ratio of 10:3 at room temperature, stirred evenly, and prepolymerized at 35°C for 1h;

[0043] Step 2: Add 1.2 g of fumed silica to 6 g of a 25 mg / g MXene concentrated solution, stir evenly, and let stand at 2°C for 3 h to obtain a MXene-fumed silica slurry;

[0044] Step 3: Add the MXene-fumed silica slurry described in step 2 to the emulsion described in step 1, and slowly stir at 35°C for 0.1h to form a homogeneous solution;

[0045] Step 4: Vacuum the solution to 0.02 MPa for 0.1 h at 30°C to remove air bubbles from the solution in step 3.

[0046] Step 5: heating the solution in step 4 to cure the epoxy resin in the solution at 40° C. for 24 hours;

[0047] Step 6: Dry the resin described in step 5 in a forced air oven at the same temperature as the curing temperature for 6 hours to remove moisture from the resin pores and eliminate residual stress in the resin. This will produce a MXene-fumed silica-epoxy resin composite material with finely controlled physical properties. The tensile strength is greater than 40 MPa, which is 30% higher than the tensile strength of the resin obtained by direct mixing with the MXene solution ( Figure 2 ).

[0048] Example 3:

[0049] Step 1: 40g of epoxy resin matrix and 12g of curing agent were mixed at a mass ratio of 10:3 at room temperature, stirred evenly, and prepolymerized at 35°C for 1h;

[0050] Step 2: Add 2 g of fumed silica to 10 g of a 10 mg / g MXene concentrated solution, stir evenly, and let stand at 2°C for 3 h to obtain a MXene-fumed silica slurry;

[0051] Step 3: Add the MXene-fumed silica slurry described in step 2 to the emulsion described in step 1, and slowly stir at 35°C for 0.1h to form a homogeneous solution;

[0052] Step 4: Vacuum the solution to 0.02 MPa for 0.1 h at 30°C to remove air bubbles from the solution in step 3.

[0053] Step 5: heating the solution in step 4 to cure the epoxy resin in the solution at 40° C. for 24 hours;

[0054] Step 6: Dry the resin described in step 5 in a forced air oven at the same temperature as the curing temperature to remove moisture in the resin pores and eliminate residual stress in the resin for 6 hours. This will produce a MXene-fumed silica-epoxy resin composite material with finely regulated physical properties. The obtained resin-based composite material exhibits an optimal absorption peak greater than 60dB and a broadband effective absorption greater than 6GHz, showing excellent high-frequency electromagnetic stealth performance ( Figure 4 ).

[0055] like Figure 3 、 Figure 6 and Figure 7 As shown, by adjusting the MXene slurry content, the electromagnetic parameters of resin-based composites can be finely controlled. Because the MXene slurry is evenly dispersed in the resin matrix (a difficult problem in the industry), it can solve the performance control problem of stealth materials at low filler content, providing a low-cost and fast mixing method.

Claims

1. A method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material, characterized by: The method comprises the following steps: Step 1: Mix the epoxy resin matrix and curing agent in a fixed ratio at room temperature, stir evenly, and then prepolymerize at 35-45°C for 1-3 hours; Step 2: Add fumed silica to the MXene concentrated solution and stir for 30-60 minutes, then let it stand at 2-10°C for 1-3 hours to obtain a MXene-fumed silica slurry; Step 3: Add the MXene-fumed silica slurry from step 2 to the mixture from step 1 and stir slowly (<120 rpm) at 35-45°C for 0.1-0.5h to form a uniform dispersion. Step 4: Vacuum the solution to a degree of 0.01-0.05 MPa for 0.1-1 h at a temperature of 20-35°C to remove air bubbles from the solution in step 3; Step 5: heating the solution in step 4 to cure the epoxy resin in the solution at a temperature of 40-80°C for 24-48 hours; Step 6: Dry the resin obtained in step 5 in a forced air oven at the same temperature as the curing temperature for 5 to 10 hours to obtain a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material.

2. The method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material according to claim 1, characterized in that: In step 2, the average particle size of the fumed silica is 100-500 nm.

3. The method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material according to claim 1, characterized in that: In step 2, the MXene concentrated solution is prepared by etching the MAX phase Ti3AlC2 through the clay method.

4. The method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material according to claim 1, characterized in that: In step 2, the concentration of the MXene concentrated solution ranges from 0.01 to 35 mg / ml.

5. The method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material according to claim 1, characterized in that: In step 2, the mass ratio of the fumed silica to the MXene concentrated solution is 0.2-0.4:

1.

6. The method for preparing a MXene-fumed silica-epoxy resin composite electromagnetic absorbing material according to claim 1, characterized in that: In step 3, the mass ratio of the MXene-fumed silica slurry to the mixture is 0.01-40:100.

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