Preparation method of MXene-based aerogel / fabric composite material giving consideration to electromagnetic shielding and flame retardance

Abstract

The invention discloses a preparation method of an MXene-based aerogel / fabric composite material with both electromagnetic shielding and flame retardance, and belongs to the technical field of multifunctional composite materials. According to the preparation method, a flexible polymer is taken as a reinforcing phase, a chemical cross-linking agent is used for assisting cross-linking, based on a'one-egg twin 'strategy, Fe3O4-coated PNT magnetic hybrid particles are generated through synchronous catalysis, the Fe3O4-coated PNT magnetic hybrid particles are taken as conductive'bridges' for connecting two-dimensional MXene sheet layers to prepare hybrid aerogel, and the hybrid aerogel is compounded with P / N / Si modified MXene flame retardant interface modified fabric to successfully construct the composite material with both electromagnetic shielding and flame retardance. The strategy overcomes the defect that the mechanical property of the MXene self-assembled aerogel is obviously insufficient, effectively enhances the electromagnetic shielding property of the composite material, breaks through the development bottleneck of mutual restriction of mechanical enhancement and electromagnetic shielding property, endows the fabric with good fire safety, and synchronously realizes the synergistic improvement of the mechanical property and flame retardant property of the aerogel / fabric composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of multifunctional composite materials, and specifically to a method for preparing a MXene-based aerogel / fabric composite material that combines electromagnetic shielding and flame retardancy. Background Art

[0002] The trend toward higher frequencies and greater integration of electronic devices is not only leading to increasing electromagnetic radiation pollution but also creating fire hazards due to concentrated heat. This creates an urgent need for multifunctional materials that combine electromagnetic shielding and flame retardancy. MXene aerogels, due to their lightweight, porous, highly conductive, and thermally stable properties, have attracted widespread attention in the fields of electromagnetic shielding and flame retardancy. However, the weak interactions between MXene nanosheets result in a loose three-dimensional network structure, limiting their practical engineering applications. Furthermore, in integrated flame retardant and electromagnetic shielding designs, the introduction of flame retardant components often disrupts the continuity of the conductive network structure, resulting in a mutual constraint between the improvement of the material's electromagnetic shielding effectiveness and flame retardancy.

[0003] The hybrid combination of conductive fillers of different sizes facilitates the formation of a hybrid conductive network, with minimal impact on the formability and mechanical properties of the aerogel material. Using one-dimensional conductive nanomaterials as a "bridge" connecting two-dimensional sheet-like conductive materials, and constructing a three-dimensional conductive interpenetrating network structure through a "line-surface" connection, can ensure the continuity and integrity of the conductive pathways and synergistically address the challenge of balancing conductive network construction with overall performance, thereby fully realizing the potential of MXene materials as electromagnetic shielding materials.

[0004] Magnetic components effectively enhance electromagnetic shielding effectiveness through magnetic losses and optimized impedance matching. However, due to their inherent magnetic interactions, magnetic components often aggregate with each other, significantly negatively impacting the structure and performance of the composite. Attaching magnetic particles to the surface of one-dimensional conductive materials through in-situ growth or chemical grafting can effectively improve the uniform distribution of magnetic particles within the composite system, a prerequisite for synergistically leveraging electrical and magnetic loss mechanisms and constructing high-performance composite materials.

[0005] Fabric-based electromagnetic shielding protective materials, due to their inherent flexibility, meet diverse application requirements in complex scenarios. Three-dimensional spacer fabrics, supported by a double-layer woven structure with spacer yarns, provide ideal pore space for aerogel loading. Their mechanical support significantly enhances the cyclic stability of composite materials, making them an excellent composite substrate for electromagnetic shielding aerogels. However, the inherent flammability of traditional spacer fabrics severely restricts their further application, necessitating flame-retardant modification. Combining flame-retardant modified fabrics as a substrate with the developed electromagnetic shielding aerogels creates a perfect match, overcoming the current limitations of flame retardancy while further enhancing the flexibility of the composite material. Summary of the Invention

[0006] In view of this, the present invention designs MXene-based hybrid aerogels with enhanced and efficient electromagnetic shielding functionality based on polymer reinforcement, synthesis of Fe3O4@PNT electric / magnetic integrated micro-nano hybrid particles, and conductive network construction; and with the help of the interface modification effect of the hybrid flame retardant system on the textile material, an integrated MXene-based aerogel / textile composite material with synergistically improved electromagnetic shielding and flame retardant properties is developed to meet the current growing demand for lightweight, high-performance composite materials.

[0007] In a first aspect, the present invention provides a method for preparing an electromagnetic shielding functionalized polymer-reinforced MXene-based hybrid aerogel solution, comprising the following steps:

[0008] 1. The aluminum layer in the MAX phase is selectively etched using an indirect hydrofluoric acid method. After washing and ultrasonication, a dispersion of a single-layer MXene with rich surface groups is obtained.

[0009] 2. Based on the "twins from one egg" strategy, Fe3O4 was in situ grown on the surface of polypyrrole nanotubes (PNTs). Pyrrole monomer (Py) was introduced into a solution containing methyl orange (MO) as a soft template and FeCl3·6H2O as an oxidant. The PNTs were obtained after stirring at 0°C to 40°C for 1 to 24 hours. The pH was then adjusted to 8 to 11, and the FeCl3·6H2O in the solution was used as a raw material. The reaction was continued for 1 to 24 hours to achieve the in situ growth of Fe3O4 on the PNT surface (Fe3O4@PNT). Fe3O4@PNT powder was obtained after washing and drying at 40°C to 80°C for 12 to 48 hours.

[0010] 3. Fe3O4@PNT and MXene are subjected to ultrasonic stirring to obtain a Fe3O4@PNT-MXene solution, and the flexible polymer is evenly dispersed in the solution. A chemical cross-linking agent is then introduced to react for a period of time to obtain an electromagnetic shielding functionalized polymer-reinforced MXene-based hybrid aerogel solution.

[0011] Furthermore, the indirect hydrofluoric acid method in step 1 is one or more of the following: hydrochloric acid and lithium fluoride method (HCl / LiF), ammonium bifluoride and acid (NH4HF2+HCl / H2SO4) combination method, other fluoride salts and acid (NH4F / HBF4+H2SO4 / HNO3) reaction or molten salt (KF / NaF at high temperature) method; the MAX phase material is Ti3C2T x 、Mo2CT x 、Ta4C3T x or V2CT x One or more of the .

[0012] Furthermore, the mass ratio of the pyrrole monomer to methyl orange in step 2 is 1:0.1-10.

[0013] Furthermore, the mass ratio of the pyrrole monomer to FeCl3·6H2O in step 2 is 1:6-12.

[0014] Furthermore, the flexible polymer in step 3 includes one or more of nanocellulose, bacterial cellulose, sodium alginate (SA), chitosan (CS), gelatin, carrageenan, hyaluronic acid, polyvinyl alcohol (PVA), polyethylene glycol (PEG), polylactic acid (PLA), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polydopamine (PDA), polyacrylamide (PAM), and polycaprolactone (PCL); the chemical crosslinking agent is one or more of glutaraldehyde (GA), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), propylene oxide (PO), methyltriethoxysilane (TESPT), carbodiimides, polyacrylamide (PAM), and polyvinyl alcohol (PVA).

[0015] Furthermore, the mass ratio of Fe3O4@PNT to MXene in step 3 is 1:1 to 20.

[0016] Furthermore, the mass ratio of the flexible polymer in step 3 to Fe3O4@PNT-MXene is 1:0.05-20.

[0017] Furthermore, the mass ratio of the flexible polymer to the chemical cross-linking agent in step 3 is 1:0.01-0.2.

[0018] In a second aspect, the present invention provides a method for preparing an aerogel / fabric composite material having both electromagnetic shielding and flame retardant properties, comprising the following steps:

[0019] (1) Preparation of P / N / Si modified MXene flame retardant: A-POSS was synthesized by stirring 3-aminopropyltriethoxysilane with HCl / CH3OH, and MXene activated by polyhydroxy compounds was added to the A-POSS solution. Then, formaldehyde solution was added and a phosphorus-containing organic compound was introduced. After the reaction, the product was purified to obtain P / N / Si modified MXene flame retardant.

[0020] (2) Preparation of flame-retardant fabrics and aerogel / fabric composites: The P / N / Si-modified MXene flame retardant interface-modified fabric prepared above is combined with a MXene-based hybrid aerogel solution, and a freeze-drying process is used to obtain an aerogel / fabric composite material that takes into account both electromagnetic shielding and flame retardancy.

[0021] Furthermore, the polyol in step (1) includes one or more of tannic acid, gallic acid, proanthocyanidin, trehalitol, xylitol, sorbitol, quercetin, rutin, catechin, and baicalin; the phosphorus-containing organic matter includes one or more of phosphorous acid, dimethyl phosphite, and diethyl phosphite; the interfacial modification strategy includes one or more of impregnation, spraying, padding, in-situ growth, in-situ deposition, and layer-by-layer self-assembly; and the fabric includes one or two of woven fabric, knitted fabric, non-woven fabric, spacer fabric, jacquard fabric, pile fabric, and mesh fabric.

[0022] Furthermore, in step (1), the ratio of the polyhydroxy compound to MXene is 20:1 to 1:5.

[0023] Furthermore, the molar ratio of the NH bond, formaldehyde and the phosphorus-containing organic compound in the A-POSS in step (1) is 1:(1-6):(1-2).

[0024] Furthermore, in step (1), the ratio of the hydroxylated MXene to A-POSS is 1:1 to 36.

[0025] Furthermore, the flame retardant modifier concentration of the flame retardant modifier solution in step (1) is 5 to 20 wt%.

[0026] Furthermore, the drying process described in step (2) includes one or more of freeze drying, directional freeze drying, supercritical drying, air drying, vacuum drying, hot press drying, microwave drying, and radiation drying.

[0027] In a third aspect, the present invention provides a method for preparing a composite material having both electromagnetic shielding and flame retardant properties, comprising the following steps:

[0028] S1, uniformly dispersing the polyol-modified MXene in an aqueous solution, adding A-POSS, then adding formaldehyde to react for a period of time, and then adding phosphorous acid to react to obtain a flame retardant modifier;

[0029] S2. Immerse the fabric in a flame retardant modifier solution, take it out and dry it to obtain a modified fabric, then immerse the modified fabric in a MXene-based hybrid aerogel solution, and finally freeze-dry it to obtain an aerogel / fabric composite material that takes into account both electromagnetic shielding and flame retardancy.

[0030] Furthermore, the polyol in step S1 includes one or more of tannic acid, gallic acid, proanthocyanidin, trehalitol, xylitol, sorbitol, quercetin, rutin, catechin, and baicalin.

[0031] Preferably, the polyhydroxy compound in step S1 is proanthocyanidin.

[0032] Furthermore, the MXene in step S1 is a single-layer MXene.

[0033] Furthermore, the preparation method of the monolithic MXene is: selectively etching the aluminum layer in the MAX phase by an indirect hydrofluoric acid method, and obtaining a dispersion of the monolithic MXene with rich surface groups through washing and ultrasound.

[0034] Specifically, the preparation method of the monolithic MXene is as follows: LiF powder and Ti3AlC2MAX powder are added to an HCl solution and stirred, then the reactant is centrifuged, the solid is washed, and finally the monolithic MXene is obtained by ultrasonication; wherein the mass ratio of LiF powder to Ti3AlC2MAX powder is 1:0.5-1.5, the concentration of the HCl solution is 8-10M, and the ratio of the mass of LiF powder to the volume of the HCl solution is 3g:50-70mL.

[0035] Furthermore, the preparation process of the P / N / Si hybrid flame retardant in step S1 is:

[0036] 3-aminopropyltriethoxysilane is uniformly dispersed in a methanol solution, and then an HCl solution is added and stirred. The mixture is then allowed to stand and filtered to obtain a precipitate, which is then washed and dried to obtain a P / N / Si hybrid flame retardant. The ratio of the volume of the 3-aminopropyltriethoxysilane to the methanol solution is 1:5-10, the concentration of HCl in the HCl solution is 30-40 wt%, and the ratio of the volume of the 3-aminopropyltriethoxysilane to the HCl solution is 1:1-2.

[0037] Furthermore, in step S1, the preparation of the polyol-modified MXene is performed by mixing the MXene and the polyol in water and then stirring for 1 to 2 hours.

[0038] Furthermore, the mass ratio of MXene to polyol is 1:5 to 20:1.

[0039] Furthermore, in step S1, the mass ratio of MXene to the P / N / Si hybrid flame retardant is 1:50-100.

[0040] Furthermore, the mass ratio of MXene to water in step S1 is 1:100-1000.

[0041] Furthermore, in step S1, the mass ratio of MXene to formaldehyde is 1:100-500.

[0042] Furthermore, the reaction conditions after adding formaldehyde in step S1 are 40-50° C. and 2-5 hours.

[0043] Furthermore, in step S1, the mass ratio of MXene to phosphorous acid is 1:100-500.

[0044] Furthermore, the reaction conditions after adding phosphorous acid in step S1 are 110-130° C. for 2-5 hours.

[0045] Furthermore, the fabric in step S2 includes one or two of woven fabric, knitted fabric, non-woven fabric, spacer fabric, jacquard fabric, pile fabric and mesh fabric.

[0046] Furthermore, the flame retardant modifier concentration of the flame retardant modifier solution in step S2 is 5 to 20 wt%.

[0047] Furthermore, the immersion time in step S2 is 5 to 10 minutes.

[0048] Furthermore, the preparation method of the MXene-based hybrid aerogel solution in step S2 is:

[0049] I. Pyrrole, methyl orange, and FeCl3·6H2O were mixed in water, stirred for 1 to 24 hours, and then the pH was adjusted to 8 to 11. The stirring was continued for 1 to 24 hours, and then Fe3O4@PNT was obtained by washing and drying.

[0050] Ⅱ. Stir Fe3O4@PNT and MXene in water to obtain Fe3O4@PNT-MXene solution, then add flexible polymer and cross-linking agent, and stir to obtain hybrid aerogel solution.

[0051] Furthermore, in step I, the mass ratio of pyrrole to methyl orange is 1:0.1-10.

[0052] Furthermore, in step I, the mass ratio of pyrrole to FeCl3·6H2O is 1:6-12.

[0053] Furthermore, in step I, the mass ratio of pyrrole to water is 1:10-100.

[0054] Furthermore, the stirring temperature in step I is 0°C to 40°C.

[0055] Furthermore, the MXene in step II is a single-layer MXene.

[0056] Furthermore, the mass ratio of Fe3O4@PNT to MXene in step II is 1:8-10.

[0057] Furthermore, the flexible polymer in step II includes one or more of nanocellulose, bacterial cellulose, sodium alginate, chitosan, gelatin, carrageenan, hyaluronic acid, polyvinyl alcohol, polyethylene glycol, polylactic acid, polyvinyl pyrrolidone, polymethyl methacrylate, polydopamine, polyacrylamide, polycaprolactone

[0058] Preferably, the flexible polymer in step II is chitosan.

[0059] Furthermore, the chemical crosslinking agent in step II is one or more of glutaraldehyde, toluene diisocyanate, hexamethylene diisocyanate, propylene oxide, methyltriethoxysilane, carbodiimides, polyacrylamide, and polyvinyl alcohol.

[0060] Preferably, the cross-linking agent in step II is glutaraldehyde.

[0061] Furthermore, in step II, the mass ratio of the flexible polymer to Fe3O4@PNT-MXene is 1:0.05~20.

[0062] Furthermore, in step II, the mass ratio of the flexible polymer to the chemical cross-linking agent is 1:0.01-0.2.

[0063] Furthermore, in step II, the mass ratio of Fe3O4@PNT to water is 1:10-200.

[0064] Beneficial effects

[0065] (1) Using flexible polymer as the reinforcing phase, chemical crosslinking agent to assist crosslinking, and one-dimensional polypyrrole nanotubes (PNTs) as the conductive "bridge" connecting two-dimensional MXene sheets, a hybrid aerogel composite material with a stable three-dimensional interpenetrating conductive network structure was successfully constructed. This effectively overcomes the obvious shortcomings of the MXene self-assembled aerogel in mechanical properties, effectively enhances the electromagnetic shielding performance of the composite material, and breaks through the development bottleneck of the mutual constraints between mechanical reinforcement and electromagnetic shielding performance.

[0066] (2) Based on the soft template and co-precipitation method, an innovative "one egg twin" strategy was adopted. While FeCl3·6H2O catalyzes the construction of one-dimensional polypyrrole nanotubes, it also provides an iron source for the formation of ferroferric oxide, successfully synthesizing Fe3O4@PNT micro-nano hybrid particles with electrical / magnetic integration in one step. The magnetic material uses the dielectric material to reduce the agglomeration phenomenon caused by magnetic effects, giving full play to its impedance matching optimization ability to address the shortcomings of the single shielding mechanism of MXene materials, reduce secondary pollution caused by electromagnetic wave reflection, and enhance the synergistic loss of electromagnetic waves.

[0067] (3) The P / N / Si modified MXene flame retardant interface modified fabric composite MXene-based hybrid aerogel composite material solves the disadvantage of easy generation of molten droplets during the combustion process of fabric, gives the fabric good fire safety, and simultaneously achieves the synergistic improvement of the mechanical properties and flame retardant properties of aerogel / fabric composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1FE-SEM and transmission electron microscopy images of polypyrrole nanotubes (PNTs) prepared using a soft template, and FE-SEM images of electromagnetically integrated micro-nanoparticles (Fe3O4@PNTs) prepared using the "twins from one egg" strategy;

[0069] Figure 2 FE-SEM images of the polymer-reinforced MXene-based hybrid aerogels of Comparative Examples 1 to 3 at different magnifications;

[0070] Figure 3 FE-SEM images of polymer-reinforced MXene-based hybrid aerogels with three-dimensional interpenetrating conductive network structures constructed with different ratios of one-dimensional PNT / two-dimensional MXene in Examples 2 to 4 at different magnifications;

[0071] Figure 4 These are real-time snapshots of vertical combustion and thermal infrared temperature recording images of Example 1. DETAILED DESCRIPTION

[0072] Source of raw materials

[0073] Ti3AlC2 MAX powder was purchased from Jilin Yiyi Technology Co., Ltd., 400 mesh; spacer fabric was purchased from Changshu Meishunqi Textile Technology Co., Ltd., consisting of polyester woven surface tissue and polypropylene spacer yarn.

[0074] Example 1

[0075] A method for preparing a polymer-reinforced MXene-based hybrid aerogel with a three-dimensional interpenetrating conductive network structure constructed based on electric / magnetic integrated micro-nano hybrid particles Fe3O4@PNT / MXene, comprising the following steps:

[0076] 1. Disperse 3g of LiF powder in 60mL of 9M HCl solution to form a homogeneous mixture, which is then stirred continuously at 45°C for approximately 30min. Then, weigh 3g of Ti3AlC2MAX powder and slowly add it to the mixture, stirring continuously for 48h to selectively etch away the Al layer of the MAX phase. The resulting product is mixed with deionized water and washed by repeated centrifugation (3500rpm, 10min) until the supernatant pH is close to neutral. Finally, a monolayer MXene solution is obtained after ultrasonication in an ice bath for 60min.

[0077] 2. Under ice-bath conditions and constant stirring (300 rpm), 0.05 g of MO powder was weighed and dissolved in 60 mL of deionized water. 0.243 g of FeCl₃·6H₂O was then added. Once fully dispersed, 0.105 mL of Py was added and stirred continuously until the oil droplets disappeared. The resulting reaction mixture was black and highly viscous. After stirring in the dark and ice-bath for 5 hours, ammonia was added to adjust the pH to 10. The reaction was stirred for another 3.5 hours. PNTs with in situ Fe₃O₄ growth on their surfaces were obtained by vacuum filtration, designated Fe₃O₄@PNT. Finally, the mixture was rinsed with ethanol and water until all unreacted solvent was removed and dried in a dryer for 10 hours to obtain Fe₃O₄@PNT powder.

[0078] 3. Fe3O4@PNT powder was added to the monolithic MXene solution, maintaining a mass ratio of Fe3O4@PNT to MXene of 1:9. The mixture was ultrasonically and stirred for 15 minutes to obtain Fe3O4@PNT-MXene. Then, under continuous stirring and ice-bath ultrasonication, 5.44 g of a 30 mg / mL CS solution was dropwise added to 26.44 g of a 20 mg / mL Fe3O4@PNT-MXene dispersion to form a uniform and stable solution. After this, 0.13 g of a 250 mg / mL GA aqueous solution was introduced, followed by a chemical cross-linking reaction for 5 minutes. The CS-PF@MX hybrid aerogel was then freeze-dried.

[0079] Example 2

[0080] A method for preparing a polymer-reinforced MXene-based hybrid aerogel with a three-dimensional interpenetrating conductive network structure constructed based on one-dimensional PNT / two-dimensional MXene, comprising the following steps:

[0081] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0082] 2. In an ice bath and continuous stirring (300 rpm), 0.05 g of MO powder was weighed and dissolved in 60 mL of deionized water. 0.243 g of FeCl3·6H2O was then added. After complete dispersion, 0.105 mL of Py was introduced and stirred until the oil droplets disappeared. The resulting reaction mixture was black and highly viscous. After stirring in the dark and in an ice bath for 5 h, the mixture was rinsed with ethanol and water until the unreacted solvent was completely removed. The mixture was then dried in a drying oven for 10 h to obtain PNT powder.

[0083] 3. PNT powder was added to the monolithic MXene solution, maintaining a PNT / MXene mass ratio of 1:18. Ultrasonication and stirring were continued for 15 minutes to obtain PNT@MXene. Under conditions of continuous mechanical stirring and ice-bath ultrasonication, 5.44 g of a 30 mg / mL CS solution was dropwise added to 26.44 g of a 20 mg / mL PNT@MXene dispersion. Once a uniform and stable solution was formed, 0.13 g of a 250 mg / mL GA aqueous solution was introduced. The chemical cross-linking reaction was carried out for 5 minutes, and the CS-PF@MX-1 hybrid aerogel was obtained after freeze-drying.

[0084] Example 3

[0085] A method for preparing a polymer-reinforced MXene-based hybrid aerogel with a three-dimensional interpenetrating conductive network structure constructed based on one-dimensional PNT / two-dimensional MXene, comprising the following steps:

[0086] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0087] 2. The PNT preparation method was carried out with reference to step 2 of Comparative Example 4, and finally PNT powder was obtained.

[0088] 3. PNT powder was added to the monolithic MXene solution, maintaining a PNT / MXene mass ratio of 1:9. The mixture was ultrasonically and stirred for 15 minutes to obtain PNT@MXene. Under conditions of continuous mechanical stirring and ice-bath ultrasonication, 5.44 g of a 30 mg / mL CS solution was dropwise added to 26.44 g of a 20 mg / mL PNT@MXene dispersion. Once a uniform and stable solution was formed, 0.13 g of a 250 mg / mL GA aqueous solution was introduced. The reaction was chemically cross-linked for 5 minutes, and the CS-PF@MX-2 hybrid aerogel was obtained after freeze-drying.

[0089] Example 4

[0090] A method for preparing a polymer-reinforced MXene-based hybrid aerogel with a three-dimensional interpenetrating conductive network structure constructed based on one-dimensional PNT / two-dimensional MXene, comprising the following steps:

[0091] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0092] 2. The PNT preparation method was carried out with reference to step 2 of Comparative Example 4, and finally PNT powder was obtained.

[0093] 3. PNT powder was added to the monolithic MXene solution, maintaining a PNT / MXene mass ratio of 1:3. The mixture was ultrasonically and stirred for 15 minutes to obtain PNT@MXene. Under conditions of continuous mechanical stirring and ice-bath ultrasonication, 5.44 g of a 30 mg / mL CS solution was dropwise added to 26.44 g of a 20 mg / mL PNT@MXene dispersion. Once a uniform and stable solution was formed, 0.13 g of a 250 mg / mL GA aqueous solution was introduced. The reaction was chemically cross-linked for 5 minutes, and the CS-PF@MX-3 hybrid aerogel was obtained after freeze-drying.

[0094] Comparative Example 1

[0095] A method for preparing SA-enhanced MXene-based hybrid aerogel comprises the following steps:

[0096] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0097] 2. Under the conditions of continuous mechanical stirring and ice bath ultrasound, 5.44 g of 30 mg / mL SA solution was added dropwise to 26.44 g of 20 mg / mL monolayer MXene solution. After a uniform and stable solution system was formed, 0.13 g of 250 mg / mL GA aqueous solution was introduced. The chemical cross-linking reaction was carried out for 5 minutes, and the SMA hybrid aerogel was obtained by freeze-drying.

[0098] Comparative Example 2

[0099] A method for preparing CS-enhanced MXene-based hybrid aerogel comprises the following steps:

[0100] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0101] 2. Under the conditions of continuous mechanical stirring and ice bath ultrasound, 5.44 g of 30 mg / mL CS solution was added dropwise to 26.44 g of 20 mg / mL monolayer MXene solution. After a uniform and stable solution system was formed, 0.13 g of 250 mg / mL GA aqueous solution was introduced. The chemical cross-linking reaction was carried out for 5 minutes, and the CMA hybrid aerogel was obtained after freeze-drying.

[0102] Comparative Example 3

[0103] A method for preparing a PVA-reinforced MXene-based hybrid aerogel comprises the following steps:

[0104] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0105] 2. Under the conditions of continuous mechanical stirring and ice bath ultrasound, 5.44 g of 30 mg / mL PVA solution was added dropwise to 26.44 g of 20 mg / mL monolayer MXene solution. After a uniform and stable solution system was formed, 0.13 g of 250 mg / mL GA aqueous solution was introduced. The chemical cross-linking reaction was carried out for 5 minutes, and the PMA hybrid aerogel was obtained by freeze-drying.

[0106] In order to facilitate the comparison of MXene-based hybrid aerogels reinforced with different polymers, MXene-based hybrid aerogels SMA (Comparative Example 1), CMA (Comparative Example 2) and PMA (Comparative Example 3) reinforced with polymers SA, CS and PVA, respectively, and MXene-based hybrid aerogels CS-PF@MX-1 (Comparative Example 4), CS-PF@MX-2 (Comparative Example 5) and CS-PF@MX-3 (Comparative Example 6) reinforced with one-dimensional PNT / two-dimensional MXene ratios of 1:18, 1:9 and 1:3, respectively, were selected for comparison:

[0107] Table 1 Formula table of Examples 1 to 4 and Comparative Examples 1 to 3

[0108]

[0109] Electromagnetic shielding performance testing: The electromagnetic properties of the samples were measured using an Agilent Technologies E5071C vector network analyzer. The S-parameters of the CS-PNT@MX series aerogels were obtained using the waveguide method, and the electromagnetic shielding effectiveness (EMI SE) and ART coefficient were calculated using transmission line theory. Samples were larger than 35 mm x 35 mm in size, and the test frequency range was 8 to 18 GHz.

[0110] Compression testing: The compression properties of SMA, CMA, and PMA samples were tested using a 5000N YF-900 dual-column digital tensile testing machine from Yangzhou Yuanfeng Testing Equipment Co., Ltd. The aerogel samples were tested for resilience at room temperature at a compression speed of 20.0 mm / min. Stress-strain curves were recorded to obtain the maximum stress value. Sample dimensions were 10 mm × 10 mm × 30 mm.

[0111] Limiting oxygen index (LOI) test process: The limiting oxygen index of SMA, CMA and PMA samples with a size of 10 mm × 10 mm × 100 mm was tested using an oxygen index meter model HC-2 from Nanjing Jiangning Analytical Instrument Co., Ltd., China.

[0112] Thermogravimetric (TGA) data analysis: A TA Instruments Q500 thermogravimetric analyzer was used to test the thermal properties of SMA, CMA, and PMA samples in air and nitrogen atmospheres. The test temperature range was from room temperature to 800°C, with a constant heating rate of 20°C / min.

[0113] Table 2 shows the electromagnetic shielding performance, maximum stress value, thermal performance and flame retardant performance of Examples 1 to 4 and Comparative Examples 1 to 3

[0114]

[0115] The results show that: Comparative Examples 1 and 3 show weak mechanical properties and electromagnetic shielding properties, respectively, while Comparative Example 2 is preferred due to its balanced electromagnetic shielding performance, mechanical properties and flame retardant properties, indicating that CS can exert better performance in the selection of polymers. In the mass ratio of one-dimensional PNT material and two-dimensional MXene material, the ratio of 1:9 (Example 3) can make the three-dimensional interpenetrating conductive network structure in the hybrid aerogel sample more complete, with an electromagnetic shielding performance of up to 57dB, and excellent mechanical properties and flame retardant properties due to structural optimization. In addition, compared with the A coefficient of 0.55 in the comparative example, the A coefficient of Example 1 is as high as 0.71, which is due to the absorption and shielding mechanism of the Fe3O4@PNT electric / magnetic integrated micro-nano hybrid particles, which enhances the absorption loss of the composite material, thereby reducing the pollution caused by the secondary reflection of electromagnetic waves.

[0116] Furthermore, on the basis of Example 1 with the best electromagnetic shielding parameter effect, a P / N / Si hybrid flame retardant system interface modified flame retardant coating fabric was compounded to prepare a MXene-based aerogel / fabric composite material with both electromagnetic shielding and flame retardancy.

[0117] Example 5

[0118] An aerogel / fabric composite material that combines electromagnetic shielding and flame retardancy, based on a flame retardant coating fabric of a P / N / Si modified MXene flame retardant and a MXene-based hybrid aerogel, comprises the following steps:

[0119] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0120] 2. First, 90 mL of 3-aminopropyltriethoxysilane was evenly dispersed in 720 mL of CH3OH solution; and under continuous magnetic stirring (1100 rpm), 123 mL of HCl aqueous solution (37 wt%) was added to the above mixture and stirred for 72 h. During this reaction process, a white precipitate gradually formed. The mixture was allowed to stand for about 10 days until the white precipitate was completely deposited. The precipitate was filtered and washed with CH3OH twice or more, and then dried to obtain A-POSS as a white powder.

[0121] 3. Under ultrasonic conditions, a 4 mg / mL aqueous solution of proanthocyanidins (PCs) was added to a 20 mg / mL monolayer MXene solution, the mass ratio of PCs to MXene was controlled to be 1:5, and mechanical stirring was continued for more than 1 hour to obtain a PC-MXene dispersion. Then, in a three-necked flask equipped with a reflux condenser, 3.52 g of A-POSS was completely dissolved in 20 mL of water, and 4 mL of PC-MXene solution (16 wt%) was added. Ultrasonic stirring was performed for 20 minutes, and then 26 g of formaldehyde aqueous solution was added to the above reaction system. The temperature was raised to 45 ° C and stirred for about 40 minutes. Then, the temperature was raised to 55 ° C, 17.6 g of phosphorous acid was added, and the mixture was reacted at 120 ° C for 3.5 hours. Finally, a rotary evaporator was used to remove excess solvent and unreacted formaldehyde in the material under vacuum to obtain a black viscous substance P / N / Si modified MXene flame retardant, named PAP@P-MXene.

[0122] 4. Weigh a certain mass of PAP@P-MXene hybrid flame retardant and dissolve it in deionized water to obtain a mixed solution with a concentration of 15 wt%. Then, immerse the spacer fabric in the above-prepared solution for 5 to 10 minutes and evaporate the solvent in a drying oven at 60°C for 1 to 3 hours to obtain a flame-retardant spacer fabric named PAP@P-MX-T.

[0123] 5. The CS-PF@MX hybrid aerogel solution was prepared according to Example 1.

[0124] 6. PAP@P-MX-T of appropriate size was immersed in the CS-PF@MX hybrid aerogel solution obtained in step 5 and transferred to a plastic mold of specific size and frozen for more than 24 hours. It was then reacted in a freeze dryer until the solvent was completely evaporated. After demolding, CS-FP@MX / PAP@P-MX-T was obtained.

[0125] Comparative Example 4

[0126] A flame-retardant coated fabric based on the interface modification of a P / N / Si modified MXene flame retardant comprises the following steps:

[0127] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0128] 2. A-POSS preparation method was carried out according to step 2 of Example 2 to obtain A-POSS in white powder form.

[0129] 3. The preparation method of PAP@P-MXene is carried out according to step 3 of Example 2 to obtain PAP@P-MXene.

[0130] 4. The preparation method of the flame-retardant spacer fabric named PAP@P-MX-T refers to step 4 of Example 2.

[0131] Comparative Example 5

[0132] A MXene-based hybrid aerogel / fabric composite material comprising the following steps:

[0133] 1. The MXene preparation method was carried out according to step 1 of Example 1, and finally a single-layer MXene solution was obtained.

[0134] 2. The CS-PF@MX hybrid aerogel solution was prepared according to Example 1.

[0135] 3. Immerse the spacer fabric PT of appropriate size in the CS-PF@MX hybrid aerogel solution obtained in step 2 and transfer it to a plastic mold of specific size and freeze it for more than 24 hours. Then react it in a freeze dryer until the solvent is completely evaporated. After demolding, CS-FP@MX-T is obtained.

[0136] Comparative Example 6

[0137] A spacer fabric PT without any treatment.

[0138] In order to compare the flame retardant properties of P / N / Si modified MXene flame retardants and the comprehensive electromagnetic shielding and flame retardant properties of MXene-based hybrid aerogel / textile composites, PAP@P-MX-T (Comparative Example 4) and PT (Comparative Example 5) before and after interface modification of the P / N / Si hybrid flame retardant system were selected, and CS-FP@MX-T treated only with CS-PF@MX hybrid aerogel solution was compared:

[0139] Table 3 Formulations of Example 5 and Comparative Examples 4 to 6

[0140]

[0141] Cone calorimeter (CONE) testing process: using the iCone of the British FTT company 2+The combustion performance of PT, CS-FP@MX-T, and CS-FP@MX / PAP@P-MX-T samples was tested using a cone calorimeter under a 35 kW horizontal heat flux. Before testing, the test samples, measuring 100 mm × 100 mm × 2 mm, were wrapped in aluminum foil and exposed to a heat source at a distance of 25 mm. Materials were then analyzed for heat release rate (pHRR), combustion efficiency (CO₂ / CO), and carbon residue.

[0142] Table 4 shows the electromagnetic shielding performance, maximum stress value and flame retardant performance of Example 5 and Comparative Examples 4 to 6

[0143]

[0144] The results show that the flame retardancy of Comparative Example 4 (PAP@P-MX-T) was significantly improved. Example 5, through the combined action of the flame-retardant and electromagnetic shielding phases, exhibited excellent electromagnetic shielding, mechanical, and flame retardancy. Its EMI SE reached 51 dB (an increase of 1175% compared to PT), maximum stress reached 384 kPa (an increase of 1224.14% compared to PT), LOI was 26.5% (an increase of 39.47% compared to PT), pHRR was 268.77 (a decrease of 11.85% compared to PT), and the residual carbon rate was 24.09 (an increase of 49.35% compared to PT). The CO2 / CO ratio also shows that Example 5 is effective in suppressing the release of toxic gases.

[0145] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing an electromagnetic shielding functionalized polymer-reinforced MXene-based hybrid aerogel solution, characterized in that: The following steps are involved: (1) The aluminum layer in the MAX phase is selectively etched by an indirect hydrofluoric acid method, and a dispersion of a monolayer MXene with rich surface groups is obtained after washing and ultrasonication; (2) Based on the "twins from one egg" strategy, Fe3O4 was in situ grown on the surface of polypyrrole nanotubes. Pyrrole monomers were introduced into a solution containing methyl orange as a soft template and FeCl3·6H2O as an oxidant. After stirring at 0℃~40℃ for 1~24h, PNTs were obtained. The pH was then adjusted to 8~11. With the help of FeCl3·6H2O in the solution as a raw material, the reaction was continued for 1~24h to achieve the in situ growth of Fe3O4 on the surface of PNTs. After washing and drying at 40℃~80℃ for 12h~48h, Fe3O4@PNT powder was obtained. (3) Fe3O4@PNT and MXene were subjected to ultrasonic stirring to obtain Fe3O4@PNT-MXene solution, and the flexible polymer was evenly dispersed in the solution. A chemical cross-linking agent was then introduced to react for a period of time to obtain a polymer-reinforced MXene-based hybrid aerogel solution based on electromagnetic shielding functionality.

2. The preparation method according to claim 1, characterized in that The indirect hydrofluoric acid method in step 1 is one or more of the following: hydrochloric acid and lithium fluoride method, ammonium bifluoride and acid combination method, reaction of other fluoride salts with acid, or molten salt method; the MAX phase material is Ti3C2T x 、Mo2CT x 、Ta4C3T x or V2CT x One or more of the .

3. The preparation method according to claim 1, characterized in that In step 2, the mass ratio of the pyrrole monomer to methyl orange is 1:0.1-10; the mass ratio of the pyrrole monomer to FeCl3·6H2O is 1:6-12.

4. The preparation method according to claim 1, wherein The flexible polymer in step 3 includes one or more of nanocellulose, bacterial cellulose, sodium alginate, chitosan, gelatin, carrageenan, hyaluronic acid, polyvinyl alcohol, polyethylene glycol, polylactic acid, polyvinyl pyrrolidone, polymethyl methacrylate, polydopamine, polyacrylamide, and polycaprolactone; the chemical crosslinking agent is one or more of glutaraldehyde, toluene diisocyanate, hexamethylene diisocyanate, propylene oxide, methyltriethoxysilane, carbodiimides, polyacrylamide, and polyvinyl alcohol.

5. The preparation method according to claim 1, wherein In step 3, the mass ratio of Fe3O4@PNT to MXene is 1:1~20; the mass ratio of the flexible polymer to Fe3O4@PNT-MXene is 1:0.05~20; and the mass ratio of the flexible polymer to the chemical cross-linking agent is 1:0.01~0.

2.

6. A method for preparing an aerogel / fabric composite material with both electromagnetic shielding and flame retardant properties, characterized in that: The following steps are involved: (1) Preparation of P / N / Si modified MXene flame retardant: A-POSS was synthesized by stirring 3-aminopropyltriethoxysilane with HCl / CH3OH, and MXene activated by polyhydroxy compounds was added to the A-POSS solution. Then, formaldehyde solution was added and a phosphorus-containing organic compound was introduced. After the reaction, the product was purified to obtain P / N / Si modified MXene flame retardant. (2) Preparation of flame-retardant fabrics and aerogel / fabric composite materials: The P / N / Si modified MXene flame retardant interface-modified fabric prepared above is combined with a MXene-based hybrid aerogel solution prepared by the preparation method according to any one of claims 1 to 5, and an aerogel / fabric composite material that takes into account both electromagnetic shielding and flame retardancy is obtained through a drying process.

7. The preparation method according to claim 6, characterized in that The polyhydroxy compound in step (1) includes one or more of tannic acid, gallic acid, proanthocyanidin, trehalitol, xylitol, sorbitol, quercetin, rutin, catechin, and baicalin; the phosphorus-containing organic matter includes one or more of phosphorous acid, dimethyl phosphite, and diethyl phosphite; the ratio of the polyhydroxy compound to MXene is 20:1 to 1:5; the molar ratio of the NH bond, formaldehyde, and the phosphorus-containing organic compound in the A-POSS is 1:(1-6):(1-2); the ratio of the hydroxylated MXene to A-POSS is 1:1 to 36.

8. The preparation method according to claim 6, characterized in that The interface modification strategy in step (1) includes one or more of impregnation, spraying, padding, in-situ growth, in-situ deposition, and layer-by-layer self-assembly; the fabric includes one or two of woven fabric, knitted fabric, non-woven fabric, spacer fabric, jacquard fabric, pile fabric, and mesh fabric.

9. The preparation method according to claim 6, characterized in that The flame retardant modifier concentration of the flame retardant modifier solution in step (1) is 5 to 20 wt%.

10. The preparation method according to claim 6, characterized in that: The drying process described in step (2) includes one or more of freeze drying, directional freeze drying, supercritical drying, air drying, vacuum drying, hot press drying, microwave drying, and radiation drying.

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