Preparation method of hydrophobic electromagnetic shielding fabric with infrared stealth function

Abstract

The application discloses a preparation method of a hydrophobic electromagnetic shielding fabric with infrared stealth function, and comprises the following steps: S1, ultrasonic immersion of the fabric, washing, soaking with an alkaline solution, washing and drying to obtain a pretreated fabric; S2, reduction of silver nitrate by a reducing agent to obtain an AgNWs aqueous solution; S3, etching of a MAX phase material to obtain a MXene dispersion liquid; S4, mixing of the AgNWs aqueous solution and the MXene dispersion liquid, cutting of the fabric into a disc, placing on a vacuum suction filter bottle, vacuum suction filtration, drying to obtain MXene@AgNW / fabric; and S5, spraying of a hydrophobic material on the surface of the MXene@AgNW / fabric to obtain a hydrophobic MXene@AgNW / cotton fabric. By bridging one-dimensional AgNWs and MXene nanosheets with two-dimensional structural characteristics, the conductivity of the fabric is improved, and the absorption and reflection characteristics of the fabric to infrared radiation are affected, so that the fabric not only remains light, but also has excellent infrared stealth and electromagnetic shielding performance under the synergistic effect of AgNWs and MXene.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared stealth and electromagnetic shielding technology, and particularly relates to a preparation method of a hydrophobic electromagnetic shielding fabric with infrared stealth function. BACKGROUND

[0002] In recent years, with the rapid development of modern science and technology, electromagnetic waves have brought great convenience to human life, but also have harmful electromagnetic interference (EMI). Therefore, the research on electromagnetic shielding materials is very important. With the advent of the era of intelligent sharing and human-computer interaction, wearable electronic devices have gradually entered people's field of vision, and electromagnetic shielding fabric is a new, flexible and lightweight electromagnetic shielding material, which can be applied to wearable, military and other fields. However, in modern warfare, detection technology is developing towards intelligence, and infrared detectors can identify targets (target temperature is different from background temperature), which makes it difficult for electromagnetic shielding fabrics with single performance to meet actual application. The detection range of infrared detector mainly concentrates on 8-14 micrometer band, which highlights and identifies the target by capturing the heat signal emitted by the object in this band. According to the Stefan-Boltzmann law, reducing the emissivity and temperature of the target can achieve infrared stealth. Therefore, it is very important to develop electromagnetic shielding fabric with excellent infrared stealth to meet the requirements of complex actual application.

[0003] Transition metal carbide / nitride (MXene) is an excellent electromagnetic shielding material due to its superior electrical conductivity and rich surface functional groups. In addition, due to the inherent low mid-infrared emissivity of Ti3C2T x -MXene, it becomes a new infrared stealth material. However, Ti3C2T x -MXene is difficult to form a continuous conductive network due to the irregular size after etching, resulting in a decrease in infrared stealth and electrical conductivity. Therefore, it is still an urgent problem to be solved to further improve the electromagnetic shielding efficiency of MXene to meet the actual application.

[0004] A Chinese invention patent with publication number CN115752095A discloses a multi-band radar stealth multifunctional camouflage net and its preparation method. A high-strength flame-retardant polyester is used as a base material, and a visible light-infrared composite stealth coating is coated on the base material by using silk screen printing technology or coating technology to prepare a composite stealth coating fabric with multi-band camouflage stealth function. Another Chinese utility model patent with publication number CN213663747U discloses an anti-electromagnetic radiation clothing facilitating infrared stealth. The top of the fabric layer is tightly attached to infrared stealth fabric, and the bottom of the infrared stealth fabric is tightly attached to anti-electromagnetic radiation fabric, which can reflect and shield electromagnetic radiation. It is worth noting that there are relatively few studies on the use of MXene to prepare infrared stealth and electromagnetic shielding coating fabrics, and most of the fabrics that realize infrared stealth and electromagnetic shielding at present use multi-layer coating or multi-layer fabric stitching, which makes the overall thickness of the fabric larger.

[0005] Therefore, it is necessary to improve the prior art to solve the above problems. SUMMARY

[0006] The present application overcomes the shortcomings of the prior art and provides a preparation method of a hydrophobic electromagnetic shielding fabric with infrared stealth function. The primary problem to be solved is to use the low emissivity and conductivity characteristics of MXene to give the fabric infrared stealth and electromagnetic shielding performance.

[0007] Secondly, since the size of MXene after etching is irregular and difficult to form a continuous conductive network, the electrical conductivity decreases, so it is still an urgent problem to be solved to further improve the electromagnetic shielding efficiency and infrared stealth performance of MXene to meet the actual application.

[0008] Finally, the effect of the amount of AgNWs on the infrared stealth and electromagnetic shielding performance of MXene@AgNWs fabric is studied, and a series of flexible hydrophobic MXene@AgNWs electromagnetic shielding fabrics with infrared stealth are obtained by spraying PFOTES.

[0009] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a preparation method of a hydrophobic electromagnetic shielding fabric with infrared stealth function, comprising the following steps:

[0010] S1, immerse the fabric in anhydrous ethanol under ultrasonic, wash with water, and immerse in an alkaline solution, wash with water and dry to obtain a pretreated fabric;

[0011] S2, reduce silver nitrate by a reducing agent to obtain an AgNWs aqueous solution;

[0012] S3, etch the MAX phase material to obtain a MXene dispersion;

[0013] S4, mixing the AgNWs aqueous solution in the S2 step and the MXene dispersion liquid in the S3 step in a certain proportion, cutting the fabric pretreated in the S1 step into a disc, placing the disc on a vacuum suction filter bottle, repeating vacuum-assisted suction filtration, drying in a vacuum oven, to obtain a MXene@AgNW / fabric;

[0014] S5, spraying a hydrophobic material on the surface of the MXene@AgNW / fabric in the S4 step, to obtain a hydrophobic MXene@AgNW / cotton fabric.

[0015] In a preferred embodiment of the present application, in the S1 step, the fabric is one of a cotton fabric, a polyester fabric, or an aramid fabric; and the thickness of the fabric is 1-3 mm.

[0016] In a preferred embodiment of the present application, in the S1 step, the power of the ultrasonic is 5-30%, and the time is 5-30 min.

[0017] In a preferred embodiment of the present application, in the S1 step, the alkaline solution is one of sodium hydroxide or potassium hydroxide; the concentration of the alkaline solution is 10-20 g / L; and the soaking time is 4-12 h.

[0018] In a preferred embodiment of the present application, in the S2 step, the reducing agent is one of glycine, polyethyleneimine, or glucose.

[0019] In a preferred embodiment of the present application, in the S3 step, the MXene is etched by one of HF, NH4HF2, or LiF+HCl.

[0020] In a preferred embodiment of the present application, in the S3 step, the MXene is one of Ti3C2T x , Ti2CT x , Ti3CNT x , or V2CT x .

[0021] In a preferred embodiment of the present application, in the S4 step, the mass ratio of the AgNWs aqueous solution to the MXene dispersion liquid is 1-3:1.

[0022] In a preferred embodiment of the present application, in the S4 step, the number of times of vacuum-assisted suction filtration is 8-12; the drying temperature is 60-100℃, and the time is 2-4 h.

[0023] In a preferred embodiment of the present application, in the S5 step, the hydrophobic material is one of polytetrafluoroethylene, polypropylene, or PFOTES.

[0024] The present application solves the defects in the background art, and has the following advantages:

[0025] (1) The present application provides a preparation method of a hydrophobic electromagnetic shielding fabric with infrared stealth function. By bridging one-dimensional AgNWs and MXene nanosheets with two-dimensional structural characteristics, the gaps existing in the MXene nanosheets can be filled, providing a more continuous and effective path for the transmission of electric charges in its interior. The bridging effect can form an efficient conductive network. When electromagnetic waves contact the coating, they will be absorbed, reflected or scattered by the free charges provided by AgNWs and MXene in the fabric, thereby effectively reducing the penetration of electromagnetic waves and improving the electromagnetic shielding performance. At the same time, MXene itself has a low infrared emissivity. The introduction of AgNWs not only improves its electrical conductivity, but also affects the absorption and reflection characteristics of the fabric to infrared radiation, making the fabric better hide its infrared features. Therefore, under the synergistic effect of AgNWs and MXene, the fabric not only remains light, but also has excellent infrared stealth and electromagnetic shielding performance.

[0026] (2) In the present application, by accurately controlling the content of AgNWs, the infrared stealth and electromagnetic shielding performance of the fabric composite material can be effectively improved, solving the problem that single MXene cannot form an efficient and continuous conductive network on the surface of the fabric, thereby increasing the infrared emissivity and reducing the electrical conductivity.

[0027] (3) In the present application, by using the spraying method of PFOTES, it has extremely low surface energy, and the contained fluorine atoms can form a strong hydrophobic barrier, which will react with the functional groups on the surface of MXene to form chemical bonds. Not only does it enhance the bonding force between PFOTES and MXene, but also makes the surface of the MXene layer covered with a layer of fluorinated layer with extremely high hydrophobicity. Water molecules are effectively blocked outside the MXene layer, reducing the reaction opportunity of water molecules with MXene. Moreover, the strong electronegativity of fluorine atoms can also attract and fix the surrounding electrons to form an electron cloud barrier, further blocking the entry and reaction of oxygen molecules, so that the hydrophobically modified fabric composite material has higher electromagnetic shielding performance and better infrared stealth effect. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings;

[0029] Figure 1 is MXene5@AgNWs in the embodiment 1 of the present application 1.16 is the real object image and SEM morphology of cotton fabric;

[0030] Figure 2 is cotton fabric and MXene5@AgNWs in the embodiment 1 of the present application 1.16 is the infrared image of cotton fabric with MXene5@AgNWs on the hot stage at 200℃;

[0031] Figure 3 is MXene5@AgNWs in the embodiment 1 of the present application 1.16 is the hydrophobic angle test image of cotton fabric sprayed with PFOTES. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0033] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can be practiced in other manners different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0034] It should be noted that the raw materials, equipment and reagents used in the present application can be purchased from the market or prepared by the existing technology.

[0035] A preparation method of a hydrophobic electromagnetic shielding fabric with infrared stealth function, comprising the following steps:

[0036] S1, the fabric is immersed in anhydrous ethanol under ultrasonic, washed with water, and immersed in an alkaline solution, washed with water and dried to obtain a pretreated fabric;

[0037] S2, silver nitrate is reduced by a reducing agent to obtain an AgNWs aqueous solution;

[0038] S3, MAX phase material is etched to obtain a MXene dispersion;

[0039] S4, the AgNWs aqueous solution in S2 step and the MXene dispersion in S3 step are mixed in a certain proportion, the pretreated fabric in S1 step is cut into a disc, placed on a vacuum suction filter bottle, and repeatedly vacuum assisted suction filtration, dried in a vacuum oven to obtain MXene@AgNW / fabric.

[0040] S5, spraying a hydrophobic material on the MXene@AgNW / fabric surface in the S4 step to obtain a hydrophobic MXene@AgNW / cotton fabric.

[0041] In some specific embodiments, in the step of S1, the fabric is one of a cotton fabric, a polyester fabric or an aramid fabric; the thickness of the fabric is 1-3 mm; the power of the ultrasonic is 5-30%, and the time is 5-30 min; the alkaline solution is one of sodium hydroxide or potassium hydroxide; the concentration of the alkaline solution is 10-20 g / L; and the soaking time is 4-12 h.

[0042] In a preferred scheme, the fabric is a cotton fabric with a thickness of 1.5 mm; the power of the ultrasonic is 10%, and the time is 20 min; the alkaline solution is NaOH with a concentration of 15 g / L; and the soaking time is 8 h.

[0043] In some specific embodiments, in the step of S2, the reducing agent is one of glycine, polyethyleneimine or glucose.

[0044] In a preferred scheme, the reducing agent is glucose.

[0045] In some specific embodiments, in the step of S3, the MXene is etched by one of HF, NH4HF2 or LiF+HCl; and the MXene is one of Ti3C2T x , Ti2CT x , Ti3CNT x or V2CT x .

[0046] In a preferred scheme, the MXene is etched by LiF+HCl; and the MXene is Ti3C2T x .

[0047] In the step of S2, the MAX phase is a kind of layered structure material with the composition of Mn+1AXn (M is an early transition metal, A is a group IIIA or IVA element, and X is carbon or nitrogen). The name of MXene is derived from the MAX phase, where "M" represents an early transition metal, "X" represents carbon or nitrogen, and "ene" indicates that it is a two-dimensional material. Since the M-X bond has a strong bond energy, and the A element has a relatively active chemical activity, the A element can be removed from the MAX phase by etching process, thereby obtaining a two-dimensional structure like graphene-MXene.

[0048] In some specific embodiments, in the step of S4, the mass ratio of the AgNWs aqueous solution and the MXene dispersion is 1-3:1; the number of vacuum-assisted suction filtration is 8-12 times; the temperature of drying is 60-100℃, and the time is 2-4h.

[0049] In a preferred scheme, the mass ratio of the AgNWs aqueous solution and the MXene dispersion is 2:1; the number of vacuum-assisted suction filtration is 10 times; the temperature of drying is 80℃, and the time is 3h.

[0050] In some specific embodiments, in the step of S5, the hydrophobic material is one of polytetrafluoroethylene, polypropylene or PFOTES.

[0051] In a preferred scheme, the hydrophobic material is PFOTES.

[0052] Example 1

[0053] A method for preparing a hydrophobic electromagnetic shielding fabric with infrared stealth function, comprising the following steps:

[0054] S1, a cotton fabric with a thickness of 0.15mm is ultrasonically treated in anhydrous ethanol at an ultrasonic power of 10% for 20min, then taken out and washed with water, and then the fabric is immersed in a 15g / L NaOH aqueous solution for 8h, taken out, washed with water and dried to obtain a pretreated cotton fabric;

[0055] S2, 0.226g of AgNO3 is dissolved in 66.6mL of water to obtain solution A, 0.156g of NaCl is dissolved in 13.32mL of water to obtain solution B, solution B is slowly added to solution A, and 400mL of glucose aqueous solution (the concentration of glucose is 1.17mg / mL) is added; the above mixed solution is hydrothermally reacted in a reaction kettle at 160℃ for 24h, centrifuged 6 times, and the AgNWs aqueous solution is collected to obtain an AgNWs aqueous solution with a concentration of 1.16mg / mL;

[0056] S3, 20mL of 9M HCl solution is poured into a polytetrafluoroethylene beaker, 1.6g of LiF is weighed and added into the beaker, stirred for 5min to obtain an etching solution, 1g of Ti3AlC2 powder is slowly added to the above prepared etching solution for multiple times, and the reaction is continuously carried out at a temperature of 38℃ (with magnetic stirring) for 48h, then the obtained multi-layer MXene dispersion after the reaction is washed in water for multiple times until the pH is 7, finally the multi-layer MXene dispersion is ultrasonically treated for 60min and centrifuged for 30min to obtain a few-layer MXene dispersion with a concentration of 5mg / mL;

[0057] S4. Mix 40 mL of MXene dispersion with 20 mL of AgNWs aqueous solution evenly and stir magnetically for 30 min. Cut the pretreated cotton fabric into 5 cm diameter discs and place them on a vacuum filtration flask. Repeat vacuum-assisted filtration of the cotton fabric 10 times. Dry in a vacuum oven at 80 °C for 3 h to obtain MXene5@AgNWs. 1.16 / Cotton fabric;

[0058] To verify the successful acquisition of MXene5@AgNWs in Example 1 1.16 / Cotton fabric, Figure 1 Displayed as MXene5@AgNWs in Example 1 1.16 The physical images and SEM images of the cotton fabric confirm that the flexible AgNWs with high aspect ratios act as connectors between adjacent MXene nanosheets, constructing a continuous and efficient three-dimensional interconnected conductive network on the cotton fabric substrate. This is analogous to nutrients being transported from the ground to the trunk through the root system, enhancing the conductivity, electromagnetic shielding, and infrared stealth properties of the composite fabric. A vector network analyzer was used to test the MXene5@AgNWs. 1.16 The electromagnetic shielding performance of cotton fabric was assessed, with a thickness of 1.583 mm and a coating mass of 9.2 mg / cm³. 2 Its electromagnetic shielding effectiveness in the 8.2–12.4 GHz range is 70.6 dB; Fourier transform infrared spectroscopy was used to analyze MXene5@AgNWs. 1.16 The infrared emissivity of the cotton fabric was tested. Table 1 shows the results for MXene5@AgNWs in Example 1. 1.16 / The infrared emissivity of cotton fabrics in the 3-5μm and 8-14μm ranges, respectively, is MXene5@AgNWs 1.16 The average emissivity of cotton fabric at 3–5 μm and 8–14 μm was 0.25 and 0.17, respectively; and MXene5@AgNWs was monitored using an infrared thermal imager. 1.16 Temperature changes of cotton fabric placed on a heated platform Figure 2 The cotton fabric and MXene5@AgNWs shown in Example 1 are illustrated. 1.16 / Infrared image of cotton fabric placed on a 200℃ hot table. The surface temperature of the cotton fabric on the 200℃ hot table is 130℃. MXene5@AgNWs 1.16 The cotton fabric temperature was only 67.8℃, proving that MXene5@AgNWs 1.16 Cotton fabrics can effectively reduce the emission of infrared light, thus possessing infrared stealth capabilities.

[0059] Table 1:

[0060] Sample name 3-5 μm infrared emissivity 8-14 μm infrared emissivity MXene5@AgNWs 1.16 cotton fabric 0.25 0.17

[0061] S5, 70 mL of 1% PFOTES ethanol solution was prepared, and the PFOTES ethanol solution was sprayed on the MXene5@AgNWs obtained in the S4 step 1.16 / cotton fabric surface, and dried to obtain P-MXene5@AgNWs 1.16 / cotton fabric.

[0062] The hydrophobicity of the P-MXene5@AgNWs 1.16 / cotton fabric was tested by a contact angle meter, Figure 3 The hydrophobic angle test diagram of the MXene5@AgNWs 1.16 / cotton fabric sprayed with PFOTES is shown, and the results show that the P-MXene5@AgNWs 1.16 / cotton fabric has a hydrophobic angle of 135.1°, proving that the MXene5@AgNWs 1.16 / cotton fabric has good hydrophobicity.

[0063] Example 2

[0064] This example is basically the same as Example 1, except that in the S2 step, 0.226 g of AgNO3 was dissolved in 66.6 mL of water to obtain solution A, 0.156 g of NaCl was dissolved in 13.32 mL of water to obtain solution B, solution B was slowly added to solution A, and 400 mL of a glucose aqueous solution (the concentration of glucose was 1.17 mg / mL) was added; the above mixed solution was hydrothermally reacted at 160°C for 24 h in a reaction kettle, centrifuged 6 times, and the AgNWs aqueous solution was collected and the concentration of the AgNWs aqueous solution was adjusted to obtain an AgNWs aqueous solution with a concentration of 1.11 mg / mL. P-MXene5@AgNWs was prepared 1.11 / cotton fabric.

[0065] Example 3

[0066] This example is basically the same as Example 1, except that in the S2 step, 0.226 g of AgNO3 was dissolved in 66.6 mL of water to obtain solution A, 0.156 g of NaCl was dissolved in 13.32 mL of water to obtain solution B, solution B was slowly added to solution A, and 400 mL of a glucose aqueous solution (the concentration of glucose was 1.17 mg / mL) was added; the above mixed solution was hydrothermally reacted at 160°C for 24 h in a reaction kettle, centrifuged 6 times, and the AgNWs aqueous solution was collected and the concentration of the AgNWs aqueous solution was adjusted to obtain an AgNWs aqueous solution with a concentration of 1.11 mg / mL. P-MXene5@AgNWs was prepared 1.24 / cotton fabric.

[0067] Example 4

[0068] The embodiment is basically the same as example 1, the difference is that: S2 step, specifically: 0.226 g AgNO3 is dissolved in 66.6 mL water to obtain A solution, 0.156 g NaCl is dissolved in 13.32 mL water to obtain B solution, B solution is slowly added to A solution, 400 mL glucose aqueous solution (the concentration of glucose is 1.17 mg / mL) is added; the above mixed solution is hydrothermally reacted at 160 °C for 24 h in a reaction kettle, centrifuged 6 times, AgNWs aqueous solution is collected, and the concentration of AgNWs aqueous solution is regulated to obtain AgNWs aqueous solution with a concentration of 0.96 mg / mL. P-MXene5@AgNWs is prepared 0.96 / cotton fabric.

[0069] Example 5

[0070] The embodiment is basically the same as example 1, the difference is that: S2 step, specifically: 0.226 g AgNO3 is dissolved in 66.6 mL water to obtain A solution, 0.156 g NaCl is dissolved in 13.32 mL water to obtain B solution, B solution is slowly added to A solution, 400 mL glucose aqueous solution (the concentration of glucose is 1.17 mg / mL) is added; the above mixed solution is hydrothermally reacted at 160 °C for 24 h in a reaction kettle, centrifuged 6 times, AgNWs aqueous solution is collected, and the concentration of AgNWs aqueous solution is regulated to obtain AgNWs aqueous solution with a concentration of 0.89 mg / mL. P-MXene5@AgNWs is prepared 0.89 / cotton fabric.

[0071] Example 6

[0072] The embodiment is basically the same as example 1, the difference is that: S2 step, specifically: 0.226 g AgNO3 is dissolved in 66.6 mL water to obtain A solution, 0.156 g NaCl is dissolved in 13.32 mL water to obtain B solution, B solution is slowly added to A solution, 400 mL glucose aqueous solution (the concentration of glucose is 1.17 mg / mL) is added; the above mixed solution is hydrothermally reacted at 160 °C for 24 h in a reaction kettle, centrifuged 6 times, AgNWs aqueous solution is collected, and the concentration of AgNWs aqueous solution is regulated to obtain AgNWs aqueous solution with a concentration of 1.28 mg / mL. P-MXene5@AgNWs is prepared 1.28 / cotton fabric.

[0073] Example 7

[0074] The embodiment is basically the same as embodiment 1, the difference is that: S5 step, specifically: 70 mL of 0.7% PFOTES ethanol solution is configured, and the PFOTES ethanol solution is sprayed on the MXene5@AgNWs obtained in S4 step 1.16 / cotton fabric surface, and dried to obtain P-MXene5@AgNWs 1.16 / cotton fabric.

[0075] Example 8

[0076] The embodiment is basically the same as embodiment 1, the difference is that: S5 step, specifically: 70 mL of 0.5% PFOTES ethanol solution is configured, and the PFOTES ethanol solution is sprayed on the MXene5@AgNWs obtained in S4 step 1.16 / cotton fabric surface, and dried to obtain P-MXene5@AgNWs 1.16 / cotton fabric.

[0077] Example 9

[0078] The embodiment is basically the same as embodiment 1, the difference is that: S5 step, specifically: 70 mL of 1.4% PFOTES ethanol solution is configured, and the PFOTES ethanol solution is sprayed on the MXene5@AgNWs obtained in S4 step 1.16 / cotton fabric surface, and dried to obtain P-MXene5@AgNWs 1.16 / cotton fabric.

[0079] Example 10

[0080] The embodiment is basically the same as embodiment 1, the difference is that: S5 step, specifically: 70 mL of 1.9% PFOTES ethanol solution is configured, and the PFOTES ethanol solution is sprayed on the MXene5@AgNWs obtained in S4 step 1.16 / cotton fabric surface, and dried to obtain P-MXene5@AgNWs 1.16 / cotton fabric.

[0081] Comparative Example 1

[0082] The comparative example is basically the same as embodiment 1, the difference is that: no S2 step, S4 step, specifically: the pretreated cotton fabric is cut into a disc with a diameter of 5 cm, placed on a vacuum suction filter bottle, and the cotton fabric is repeatedly vacuum assisted suction filtered 40 mL of MXene dispersion solution 10 times, dried in a vacuum oven at 80°C for 3 h, to obtain P-MXene5 / cotton fabric.

[0083] Comparative Example 2

[0084] The comparative example is basically the same as example 1, the difference is that there is no S5 step, MXene5@AgNWs is obtained 1.16 / cotton fabric.

[0085] Performance test: the fabrics obtained in examples 2-10 and comparative examples 1-2 are first detected for surface temperature by an infrared thermal imager on a hot stage at 200℃; then the electromagnetic shielding performance of the fabrics is tested by a vector network analyzer at 8.2-12.4GHz; and the antioxidant capacity (DPPH free radical clearance rate as an index) is tested; finally, the electromagnetic shielding performance of the fabrics after oxidation is tested by a vector network analyzer at 8.2-12.4GHz, and compared with example 1, the results are shown in table 2.

[0086] The specific steps of the antioxidant capacity test are as follows: 80mL of 50% volume percentage ethanol solution and 20mL of DPPH· ethanol solution (0.1mmol / L) are mixed to obtain a DPPH test solution. The fabrics obtained in examples 1-10 and comparative examples 1-2 are respectively placed in the DPPH test solution, and the absorbance A0 at this time is detected, and the absorbance A1 after 0.5h of shaking water bath heating at 37℃ in a dark environment is detected; the DPPH test solution is heated in a shaking water bath at 37℃ in a dark environment for 0.5h, and the absorbance A2 at this time is detected. The DPPH free radical clearance rate of the fabric is obtained by the formula,

[0087] Table 2:

[0088]

[0089] As shown in table 2, by comparing example 1 with comparative example 1, it can be known that by bridging one-dimensional AgNWs with MXene nanosheets having two-dimensional structural characteristics, the gaps existing in the MXene nanosheets can be filled, and a more continuous and effective path is provided for the transmission of charges in its interior, the bridging effect can form a high-efficiency conductive network, when electromagnetic waves contact the coating, they will be absorbed, reflected or scattered by the free charges provided by AgNWs and MXene in the fabric, thereby effectively reducing the penetration of electromagnetic waves and improving the electromagnetic shielding performance, at the same time, MXene itself has a low infrared emissivity, the introduction of AgNWs not only improves the conductivity of the fabric, but also affects the absorption and reflection characteristics of the fabric to infrared radiation, so that the fabric can better hide its infrared characteristics, and under the synergistic effect of AgNWs and MXene, the fabric not only remains light, but also has excellent infrared stealth and electromagnetic shielding performance.

[0090] ​It can be seen from the comparison of Example 1 and Examples 2-6 that accurate control of the content of AgNWs can effectively improve the infrared stealth and electromagnetic shielding performance of the fabric composite material, solve the problem that a single MXene cannot form a high-efficiency continuous conductive network on the surface of the fabric, thereby increasing the infrared emissivity and reducing the electrical conductivity. When the content is too low, the conductive network in the fabric composite material is not perfect enough, which hinders the transmission path of electromagnetic waves, and an effective electromagnetic shielding layer cannot be formed, so that electromagnetic waves can more easily penetrate the material. When the content is too high, the electrical conductivity is too high, which will increase the reflection loss due to the impedance mismatch between air and the interface of the shielding material, thereby reducing the shielding performance and indirectly affecting the infrared stealth effect.

[0091] It can be seen from the comparison of Example 1 and Comparative Example 2 that by using the spraying method of PFOTES, the surface energy is extremely low, and the contained fluorine atoms can form a strong hydrophobic barrier and react with the functional groups on the surface of MXene to form chemical bonds. This not only enhances the bonding force between PFOTES and MXene, but also covers the surface of the MXene layer with a fluorinated layer with extremely high hydrophobicity, effectively blocking water molecules outside the MXene layer, reducing the reaction opportunity of water molecules with MXene, and the strong electronegativity of fluorine atoms can also attract and fix the surrounding electrons to form an electron cloud barrier, further blocking the entry and reaction of oxygen molecules, thereby making the hydrophobically modified fabric composite material have higher electromagnetic shielding performance and better infrared stealth effect.

[0092] It can be seen from the comparison of Example 1 and Examples 7-10 that a suitable content of PFOTES can reduce the oxidation of the MXene layer and increase the hydrophobicity of the fabric. When the content is too low, the hydrophobic layer formed on the surface of the MXene layer is not dense or uniform enough, which makes the MXene layer more susceptible to oxidative damage, thereby affecting its electrical conductivity and structural integrity. When the content is too high, it is easy to cause the MXene layer to form agglomeration or defects on the surface, and the interfacial bonding force between the MXene layer and AgNWs or the fabric is weakened, becoming a channel for water molecules and oxygen molecules to penetrate, thereby weakening the electromagnetic shielding performance.

[0093] The above is based on the ideal embodiment of the present application, through the above description, for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0094] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for preparing a hydrophobic electromagnetic shielding fabric with infrared stealth function, characterized in that, The method comprises the following steps: S1, ultrasonic immersion of cotton fabric in anhydrous ethanol, washing with water, and soaking with an alkaline solution, washing with water and drying to obtain pretreated fabric; S2, reduction of silver nitrate by a reducing agent to obtain an AgNWs aqueous solution; S3, etching of a MAX phase material to obtain a MXene dispersion; S4, mixing the AgNWs aqueous solution in S2 and the MXene dispersion in S3 according to a volume ratio of 1:2, cutting the pretreated fabric in S1 into a disc, placing it on a vacuum suction filter bottle, repeating vacuum-assisted suction filtration 8-12 times, and drying in a vacuum oven to obtain MXene@AgNW / fabric; wherein the concentration of the MXene dispersion is 5 mg / mL, and the concentration of the AgNWs aqueous solution is one of 0.89 mg / mL, 0.96 mg / mL, 1.11 mg / mL, 1.16 mg / mL, 1.24 mg / mL or 1.28 mg / mL; S5, spraying PFOTES on the surface of the MXene@AgNW / fabric in S4 to obtain a hydrophobic MXene@AgNW / cotton fabric; In the step S3, the MXene is etched by one of HF, NH4HF2 or LiF+HCl; and the MXene is Ti3AlC2.

2. The method for preparing a hydrophobic electromagnetic shielding fabric with infrared stealth function according to claim 1, characterized in that: In the step S1, the thickness of the cotton fabric is 1-3 mm.

3. The method for preparing a hydrophobic electromagnetic shielding fabric with infrared stealth function according to claim 1, characterized in that: In the step S1, the power of the ultrasonic is 5-30%, and the time is 5-30 min.

4. The method for preparing a hydrophobic electromagnetic shielding fabric with infrared stealth function according to claim 1, characterized in that: In the step S1, the alkaline solution is one of sodium hydroxide or potassium hydroxide; the concentration of the alkaline solution is 10-20 g / L; and the soaking time is 4-12 h.

5. The method for preparing a hydrophobic electromagnetic shielding fabric with infrared stealth function according to claim 1, characterized in that: In the step S2, the reducing agent is one of glycine, polyethyleneimine or glucose.

6. The method for preparing a hydrophobic electromagnetic shielding fabric with infrared invisibility function according to claim 1, characterized in that: In the step S4, the drying temperature is 60-100℃, and the time is 2-4 h.

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