Composite aerogel material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of nano composite materials, in particular to a composite aerogel material as well as a preparation method and application thereof. The preparation method comprises the following steps: providing an MXene solution and a polypropylene nanofiber colloidal solution; mixing the MXene solution and the polypropylene nanofiber colloidal solution to obtain a first mixed solution; performing freeze thawing treatment on the first mixed solution for multiple times to obtain composite nanofiber colloid hydrogel; the composite nanofiber colloid hydrogel is subjected to freeze drying, and composite nanofiber colloid aerogel is obtained; and immersing the composite nanofiber colloid aerogel into a solution containing polysiloxane, and then sequentially carrying out curing and ceramic treatment to obtain the composite aerogel material. The prepared composite aerogel material has heat insulation and compressibility, and is expected to be applied to the fields of flexible wearable electronics, energy and environment.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocomposite materials, and in particular to a composite aerogel material and a preparation method and application thereof. Background Art

[0002] MXenes, or two-dimensional transition metal carbides, carbonitrides, or carbonitrides, are a new type of layered two-dimensional crystalline material similar to graphene. Generally, MAX (where M = transition metal, A = aluminum or silicon, X = C, N, or CN) can obtain a single layer or a few layers of MXene after chemical etching of the A phase and subsequent liquid phase exfoliation. Precisely because of the use of etching agents (such as hydrofluoric acid or its fluorine-containing substitutes), the surface of MXene often carries abundant polar functional groups such as -OH, -F, and -O, which gives it good dispersibility in water. Therefore, two-dimensional MXene not only has high conductivity and high hydrophilicity, but can also be used as an assembled functional element, and has broad application prospects in the fields of biomedicine, energy storage, catalysis, and flexible electronics.

[0003] Two-dimensional MXene can be used to obtain three-dimensional MXene aerogel materials through freeze-drying; however, the interaction (hydrogen bond) between MXenes is weak, the stacking of MXene layers is relatively open, and the resulting single-component aerogel material has poor mechanical strength, no elasticity, and poor thermal insulation effect, which limits its application in flexible wearable electronics and other fields.

[0004] Therefore, the existing technology needs to be further improved and enhanced. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a composite aerogel material and its preparation method and application, aiming to prepare a thermally insulating and compressible composite aerogel material, which is expected to be applied to flexible wearable electronic products.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, a method for preparing a composite aerogel material comprises:

[0008] Providing a MXene solution and a polypropylene nanofiber colloidal solution; mixing the MXene solution and the polypropylene nanofiber colloidal solution to obtain a first mixed solution;

[0009] performing freeze-thaw treatment on the first mixed solution multiple times to obtain a composite nanofiber colloidal hydrogel; freeze-drying the composite nanofiber colloidal hydrogel to obtain a composite nanofiber colloidal aerogel;

[0010] The composite nanofiber colloidal aerogel is immersed in a solution containing polysiloxane, and then subjected to curing and ceramic treatments in sequence after the immersion to obtain the composite aerogel material.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0012] As a preferred technical solution, the method for preparing the composite aerogel material, wherein the preparation of the polypropylene nanofiber colloidal solution comprises:

[0013] dissolving polyacrylonitrile in an organic solvent to obtain a polyacrylonitrile solution;

[0014] The polyacrylonitrile solution is subjected to electrospinning technology to obtain polyacrylonitrile nanofiber cloth;

[0015] The polyacrylonitrile nanofiber cloth is crushed, added into a mixed solvent of deionized water and tert-butyl alcohol, and subjected to shearing treatment under rotation conditions to obtain the polypropylene nanofiber colloidal solution.

[0016] As a preferred technical solution, the method for preparing the composite aerogel material, wherein the first mixed solution is subjected to multiple freeze-thaw treatments, comprises the steps of:

[0017] The first mixed solution is placed on a pre-frozen metal plate, then placed in a freezing setting for freezing treatment, and then placed at room temperature for thawing; and this process is repeated multiple times.

[0018] As a preferred technical solution, in the method for preparing the composite aerogel material, in the solution containing polysiloxane, the ratio of polysilazane to ethanol is 100 mg to 1 g: 50 ml.

[0019] As a preferred technical solution, the method for preparing the composite aerogel material, wherein the composite nanofiber colloidal aerogel is immersed in a solution containing polysiloxane, and after the immersion, the composite aerogel material is obtained by sequentially curing and ceramicizing. The method comprises:

[0020] immersing the composite nanofiber colloidal aerogel in a solution containing polysiloxane under vacuum conditions;

[0021] drying the impregnated composite nanofiber colloidal aerogel at room temperature;

[0022] heating and curing the dried composite nanofiber colloidal aerogel in a vacuum drying device to obtain the cured composite nanofiber colloidal aerogel;

[0023] The solidified composite nanofiber colloidal aerogel is calcined to obtain the composite aerogel material.

[0024] As a preferred technical solution, the method for preparing the composite aerogel material, wherein the concentration of the MXene solution is 4 to 10 mg / mL;

[0025] Preferably, the mass ratio of MXene to polyacrylonitrile nanofibers in the first mixed solution is 100:5-100.

[0026] As a preferred technical solution, in the method for preparing the composite aerogel material, the mass ratio of the organic solvent to polyacrylonitrile is 100:5-15; and the organic solvent is N,N-dimethylformamide.

[0027] As a preferred technical solution, the preparation method of the composite aerogel material, wherein the calcination temperature is 600-1000°C, the time is 60-180 minutes, and the heating rate is 1-5°C / minute;

[0028] Preferably, the temperature of the heat curing treatment is 100 to 400° C., and the time is 60 to 180 minutes.

[0029] In a second aspect, a composite aerogel material is provided, wherein the composite aerogel material is prepared by the preparation method described above.

[0030] In a third aspect, the composite aerogel material described in the second aspect is used to prepare flexible wearable electronic products.

[0031] Beneficial Effects: Compared with existing technologies, the preparation method provided by the present invention comprises mixing a MXene solution and a polypropylene nanofiber colloidal solution, performing multiple freeze-thaw cycles, and then freeze-drying the freeze-thawed product to obtain a composite nanofiber colloidal aerogel. The aerogel is then immersed in a solution containing polysiloxane, and then subjected to sequential curing and ceramicization treatments to obtain the composite aerogel material. The resulting composite aerogel material exhibits thermal insulation and compressibility, and is expected to be applied in flexible wearable electronics, energy, and environmental fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure is a schematic flow chart of the preparation method of the composite aerogel material provided by the present invention.

[0033] Figure 2 It is a schematic diagram of the structure of the composite aerogel material provided by the present invention. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values ​​described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures. The low temperature detection described in the present invention refers to room temperature detection.

[0037] like Figure 1 As shown, the present invention provides a method for preparing a composite aerogel material, comprising the following steps:

[0038] Step S10: providing a MXene solution and a polypropylene nanofiber colloidal solution; mixing the MXene solution and the polypropylene nanofiber colloidal solution to obtain a first mixed solution.

[0039] Specifically, a highly concentrated, stable, and uniform MXene nanosheet solution was prepared by chemical exfoliation. The specific steps are as follows:

[0040] Ti3AlC2 powder is slowly added to a pre-prepared mixed solution of lithium fluoride and concentrated hydrochloric acid, and the reaction is carried out for 16 to 48 hours at a temperature of 25 to 50°C. After the reaction is completed, the mixed solution is centrifuged and washed to obtain a solid precipitate until the centrifuge solution is neutral or nearly neutral.

[0041] The precipitate obtained last time was intercalated with ethanol and then ultrasonically exfoliated in deionized water; then, a MXene colloidal solution with a concentration of 4 to 10 mg / mL was obtained by centrifugation for standby use.

[0042] A uniform polyacrylonitrile nanofiber colloidal solution was prepared by electrospinning and homogenization. The specific steps are as follows:

[0043] Dry polyacrylonitrile under vacuum at 100-110°C for 24-48 hours;

[0044] Dissolve the polyacrylonitrile in N,N-dimethylformamide, wherein the mass ratio of N,N-dimethylformamide to polyacrylonitrile is 100:5-15, and obtain a uniform solution after continuous stirring for use;

[0045] The polyacrylonitrile nanofiber cloth is obtained by high-voltage electrospinning technology, wherein the voltage is 5-10 kV, the spinning distance is 5-10 cm, the receiver is a roller, the speed is 200-1000 rpm, and the spinning time is 20-60 minutes; then, the obtained polypropylene nanofiber cloth is vacuum dried at 100-110°C for 24-48 hours and set aside;

[0046] The polyacrylonitrile nanofiber cloth is cut into pieces and added to a mixed solvent of deionized water / tert-butanol, wherein the mass ratio of water to tert-butanol is 100:20, and high-speed shearing is performed at a speed of 1000-6000 rpm for 5-60 minutes to finally obtain a uniform polyacrylonitrile nanofiber colloidal solution for standby use; the obtained concentration is 2-10 mg / mL.

[0047] In the present invention, polyacrylonitrile (PAN) is a carbonized polymer material that can be carbonized into a highly conductive carbon material at an appropriate temperature and can serve as both a reinforcing agent and a base material for inorganic materials.

[0048] After electrospinning, polyacrylonitrile produces nanofiber cloth formed by the "layer-by-layer self-assembly" of nanofibers; after high-speed shearing, nanofibers are formed after the "dissociation" of the nanofiber cloth, and these nanofibers have good dispersibility in aqueous solution; polyacrylonitrile nanofiber micelles can be highly entangled with MXene, which enhances the interaction between MXenes; polyacrylonitrile nanofibers can be carbonized into carbon fibers at high temperatures, which undoubtedly further enhances the mechanical strength of MXene.

[0049] Polysilazane (PSZ) is a polymer with a Si-N backbone. Due to its unique structure, it is classified as either inorganic or organic. Si-N bonds are more easily converted into other types of bonds than Si-O and Si-Cl bonds because their bond energy is lower, approximately 355 kJ / mol. Polysilazane also contains Si-N, Si-H, and NH bonds, all of which readily react with other substances such as water, alcohols, silanols, phenols, and substances containing certain functional groups. These reactions primarily include hydrolysis / alcoholysis, condensation coupling, and hydrosilylation. Consequently, polysilazane exhibits high chemical reactivity, making it suitable for use as a surface modifier for inorganic nanomaterials. Furthermore, polysilazane forms Si-N-based compounds upon high-temperature ceramicization, which exhibit high insulating properties.

[0050] Polysilazane has strong adhesion and can connect to MXene surface groups through chemical bonds. The flexible silicon-containing segments improve the adhesion between MXene layers and the subsequent mechanical strength. Polysilazane can form Si-N materials at high temperature ceramics, which have high thermal insulation and high hydrophobicity, further improving the overall performance of the composite gel.

[0051] Step S20: performing freeze-thaw treatment on the first mixed solution multiple times to obtain a composite nanofiber colloidal hydrogel; and freeze-drying the composite nanofiber colloidal hydrogel to obtain a composite nanofiber colloidal aerogel.

[0052] Specifically, the MXene solution and the polypropylene nanofiber colloid solution in step S10 are mixed at a speed of 1000 to 6000 rpm for 1 to 5 minutes to obtain a MXene / polyacrylonitrile composite nanofiber colloid mixed solution for standby use;

[0053] The MXene / polyacrylonitrile composite nanofiber colloidal mixed solution is placed on a pre-frozen copper plate for "oriented freezing"; then, it is placed in a freezer for slow "physical crosslinking"; then, it is placed at room temperature for slow thawing; this process is repeated 3 to 10 times to finally obtain a physically crosslinked MXene / polyacrylonitrile composite nanofiber colloidal hydrogel for use; wherein, the freezing and thawing times are 5 to 24 hours, respectively;

[0054] The physically cross-linked MXene / polyacrylonitrile composite nanofiber colloidal hydrogel is freeze-dried at a temperature of -20 to -40°C for 48 to 96 hours to obtain a MXene / polyacrylonitrile composite nanofiber colloidal aerogel.

[0055] Step S30: Immersing the composite nanofiber colloidal aerogel in a solution containing polysiloxane, and then subjecting the solution to curing and ceramic treatments to obtain the composite aerogel material.

[0056] Specifically, a polysilazane / ethanol mixed solution is prepared, wherein the ratio of polysilazane to ethanol is 100 mg to 1 g: 50 ml;

[0057] The MXene / polyacrylonitrile nanofiber aerogel material prepared in step S20 is completely immersed in the polysilazane / ethanol mixed solution, and the coverage of the polysilazane in the aerogel is increased by vacuum impregnation; wherein the impregnation time is 1 to 5 hours;

[0058] The impregnated MXene / polyacrylonitrile nanofiber aerogel material was dried at room temperature for 24 hours before use;

[0059] The impregnated MXene / polyacrylonitrile nanofiber aerogel material is heated and cured in a vacuum drying oven at a temperature of 100 to 400° C. for 60 to 180 minutes to obtain a low-temperature cured MXene / polyacrylonitrile nanofiber aerogel material.

[0060] The low-temperature solidified PMXene / polyacrylonitrile nanofiber aerogel material is placed in a tubular furnace for high-temperature ceramicization; wherein, the atmosphere is an inert gas such as argon and nitrogen, the temperature is: 600-1000°C, the time is 60-180 minutes, and the heating rate is 1-5°C / minute to obtain a ceramicized MXene / polyacrylonitrile nanofiber aerogel material (composite aerogel material).

[0061] In one embodiment of the present invention, when preparing a polyacrylonitrile nanofiber colloidal solution, the mass ratio of N,N-dimethylformamide to polyacrylonitrile can be 100:5-10 or 100:8. When preparing a MXene / polyacrylonitrile composite nanofiber aerogel material, the mass ratio of MXene to polyacrylonitrile nanofibers can be 100:5-100, 100:5-50, or 100:10. Controlling the mass ratio of MXene to polyacrylonitrile nanofibers can optimize the reaction and create an interpenetrating network between the MXene and polyacrylonitrile nanofibers, enhancing the strength of the MXene.

[0062] In one embodiment of the present invention, when preparing a polysilazane / ethanol mixed solution, the ratio of polysilazane to ethanol can be 200 mg to 500 mg:50 ml or 300 mg:50 ml. Controlling the ratio of polysilazane to ethanol within the above range can better dissolve the polysilazane and obtain a more uniform polysilazane solution.

[0063] In one embodiment of the present invention, when preparing ceramicized MXene / polyacrylonitrile nanofiber aerogel, the low temperature curing temperature is 200-300°C and the curing time is 60-

[0064] 120 minutes; preferably, the low temperature curing temperature is: 250 ° C, and the time is 90 minutes.

[0065] When preparing ceramicized MXene / polyacrylonitrile nanofiber aerogel, the high-temperature ceramicization temperature is 700-900° C. and the time is 60-120 minutes; preferably, the high-temperature ceramicization temperature is 750° C. and the time is 90 minutes.

[0066] Based on the same inventive concept, the present invention also provides a composite aerogel material, which is prepared using the above-mentioned preparation method.

[0067] The composite aerogel material prepared by the present invention has the following advantages:

[0068] 1) MXene and carbon fibers form an interpenetrating network; one-dimensional carbon fibers entangle two-dimensional MXene nanosheets, and the two support each other, improving the mechanical strength of the composite aerogel;

[0069] 2) When polysilazane is cured, it can further improve the mechanical strength of the composite aerogel; after high-temperature ceramicization, it can form a Si-N coating layer on the surface of the aerogel, giving the aerogel high thermal insulation and high hydrophobicity;

[0070] 3) It is expected to be used in flexible wearable electronics, energy and environmental fields.

[0071] The composite aerogel material and the preparation method thereof provided by the present invention are further explained below through specific preparation examples.

[0072] Example 1

[0073] Step (1). Prepare a high-concentration, stable, and uniform MXene nanosheet solution by chemical exfoliation, the specific steps of which are as follows:

[0074] 1-a): 2g of Ti3AlC2 powder was slowly added to a pre-prepared mixed solution of lithium fluoride (2g) and hydrochloric acid (9mol / L), and the reaction was carried out for 24 hours at a temperature of 40°C; after the reaction, the mixed solution was centrifuged and washed to obtain a solid precipitate until the centrifuge was neutral or nearly neutral;

[0075] 1-b): The precipitate obtained last time was intercalated with ethanol, and then ultrasonically exfoliated in deionized water; then, a MXene colloidal solution was obtained by centrifugation, with a concentration of 10 mg / mL, for standby use;

[0076] Step (2). Prepare a uniform polyacrylonitrile nanofiber colloidal solution by electrospinning and homogenization, the specific steps are as follows:

[0077] 2-a): polyacrylonitrile was vacuum dried at 105° C. for 30 h;

[0078] 2-b): dissolving the polyacrylonitrile in N, N-dimethylformamide, wherein the mass ratio of N, N-dimethylformamide to polyacrylonitrile is 100:8, and obtaining a uniform solution after continuous stirring, and setting aside;

[0079] 2-c): A polyacrylonitrile nanofiber cloth was obtained by high-voltage electrospinning technology, wherein the voltage was 8 kV, the spinning distance was 8 cm, the receiver was a drum, the speed was 600 rpm, and the spinning time was 30 minutes; then, the obtained polypropylene nanofiber cloth was vacuum dried at 105° C. for 30 hours and set aside;

[0080] 2-d): The polyacrylonitrile nanofiber cloth was cut into pieces and added to a mixed solvent of deionized water / tert-butanol, wherein the mass ratio of water to tert-butanol was 100:20, and high-speed shearing was performed at a speed of 5000 rpm for 30 minutes to obtain a uniform polyacrylonitrile nanofiber colloidal solution for standby use; the resulting concentration was 5 mg / mL;

[0081] Step (3). Prepare MXene / polyacrylonitrile nanofiber aerogel material by freeze-thawing method and freeze-drying method, the specific steps are as follows:

[0082] 3-a): The MXene solution in step (1) and the polyacrylonitrile nanofiber colloidal solution in step (2) were mixed at a speed of 5000 rpm for 3 minutes to obtain a MXene / polyacrylonitrile composite nanofiber colloidal mixed solution for standby use, wherein the mass ratio of MXene to polyacrylonitrile nanofiber is 100:10;

[0083] 3-b): The MXene / polyacrylonitrile composite nanofiber colloidal mixed solution is placed on a pre-frozen copper plate for "oriented freezing"; then, it is placed in a freezer for slow "physical crosslinking"; then, it is placed at room temperature for slow thawing; this process is repeated five times to obtain a physically crosslinked MXene / polyacrylonitrile composite nanofiber colloidal hydrogel for standby use; wherein, the freezing and thawing time are each 20 hours;

[0084] 3-c): freeze-drying the physically cross-linked MXene / polyacrylonitrile composite nanofiber colloidal hydrogel at -30°C for 72 hours to obtain a MXene / polyacrylonitrile composite nanofiber colloidal aerogel;

[0085] Step (4). Prepare polysilazane pre-modified MXene / polyacrylonitrile nanofiber aerogel material by impregnation method, the specific steps are as follows:

[0086] 4-a): preparing a polysilazane / ethanol mixed solution, wherein the ratio of polysilazane to ethanol is 300 mg:50 ml;

[0087] 4-b): The MXene / polyacrylonitrile nanofiber aerogel material prepared in (3) is completely immersed in a polysilazane / ethanol mixed solution, and the coverage of the polysilazane in the aerogel is increased by vacuum impregnation; wherein the immersion time is 2 hours;

[0088] 4-c): Dry the impregnated MXene / polyacrylonitrile nanofiber aerogel material at room temperature for 24 hours before use;

[0089] Step (5). Prepare ceramic MXene / polyacrylonitrile nanofiber aerogel by high temperature calcination method, the specific steps are as follows:

[0090] 5-a): The impregnated MXene / polyacrylonitrile nanofiber aerogel material is heated and cured in a vacuum drying oven at 200° C. for 90 minutes to obtain a low-temperature cured MXene / polyacrylonitrile nanofiber aerogel material;

[0091] 5-b): The low-temperature cured PMXene / polyacrylonitrile nanofiber aerogel material is placed in a tubular furnace for high-temperature ceramicization; wherein the atmosphere is an inert gas such as argon and nitrogen, the temperature is: 700°C, the time is: 90 minutes, and the heating rate is 2°C / minute to obtain a ceramic MXene / polyacrylonitrile nanofiber aerogel material;

[0092] Example 2: The preparation method is the same as that of Example 1, except that in step 2-b), the mass ratio of N,N-dimethylformamide to polyacrylonitrile is 100:10;

[0093] Example 3: The preparation method is the same as that of Example 1, except that in step 2-b), the mass ratio of N,N-dimethylformamide to polyacrylonitrile is 100:15;

[0094] Example 4: The preparation method is the same as that of Example 1, except that in step 3-a), the mass ratio of MXene to polyacrylonitrile nanofibers is 100:6;

[0095] Example 5: The preparation method is the same as that of Example 1, except that in step 3-a), the mass ratio of MXene to polyacrylonitrile nanofibers is 100:20;

[0096] Example 6: The preparation method is the same as that of Example 1, except that in step 3-a), the mass ratio of MXene to polyacrylonitrile nanofibers is 100:60;

[0097] Example 7: The preparation method is the same as that of Example 1, except that in step 4-a), the ratio of polysilazane to ethanol is 100 mg:50 ml;

[0098] Example 8: The preparation method is the same as that of Example 1, except that in step 4-a), the ratio of polysilazane to ethanol is 500 mg:50 ml;

[0099] Example 9: The preparation method is the same as that of Example 1, except that in step 4-a), the ratio of polysilazane to ethanol is 700 mg:50 ml;

[0100] Comparative Example 1: The preparation method is the same as that of Example 1, except that no polyacrylonitrile nanofibers and polysilazane are added during the implementation process, i.e., pure MXene aerogel;

[0101] Comparative Example 2: The preparation method is the same as that of Example 1, except that only polyacrylonitrile nanofibers, i.e., MXene / carbon fiber aerogel, are added during the implementation process;

[0102] Comparative Example 3: The preparation method is the same as that of Comparative Example 2, except that in step 3-a), the mass ratio of MXene to polyacrylonitrile nanofibers is 100:6;

[0103] Comparative Example 4: The preparation method is the same as that of Comparative Example 2, except that in step 3-a), the mass ratio of MXene to polyacrylonitrile nanofibers is 100:20;

[0104] Comparative Example 5: The preparation method is the same as that of Comparative Example 2, except that in step 3-a), the mass ratio of MXene to polyacrylonitrile nanofibers is 100:60;

[0105] The evaluation of the flexibility, thermal stability and maximum insulation temperature of each embodiment and comparative example is shown in the following table:

[0106]

[0107]

[0108] As can be seen from the above table, the mechanical properties of pure MXene aerogel (Comparative Example 1) are poor and compression recovery cannot be achieved, which indicates that the interactions such as hydrogen bonds between MXene sheets are weak, which is caused by the loss of polar groups on the MXene surface due to high temperature. In contrast, one-dimensional carbon fibers (due to carbonization of polyacrylonitrile) can form an interpenetrating network with two-dimensional MXene sheets, increasing the contact points between MXene sheets, thereby giving MXene aerogel compressibility (such as Comparative Examples 3 and 4); however, excessive carbon fibers lead to a decrease in the mechanical strength of the matrix, thereby losing compressibility (such as Comparative Example 5). In contrast, the thermal stability and high-temperature critical insulation temperature of MXene / carbon fiber aerogels increase significantly after high-temperature ceramicization of polysilazane. For example, in Example 1, the composite aerogel not only has compressibility, but its maximum insulation temperature far exceeds that of pure MXene aerogel (Comparative Example 1). Studies have further shown that further increasing the polysilazane content can continue to increase the maximum insulation temperature (such as Example 8), but loses compression recovery (such as Example 9).

[0109] Therefore, the ceramic MXene / carbon fiber composite aerogel material of the present invention has high thermal insulation and compressibility, and is expected to be used in flexible wearable electronics, energy and environmental fields.

[0110] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a composite aerogel material, characterized in that: include: Providing a MXene solution and a polypropylene nanofiber colloidal solution; mixing the MXene solution and the polypropylene nanofiber colloidal solution to obtain a first mixed solution; performing freeze-thaw treatment on the first mixed solution multiple times to obtain a composite nanofiber colloidal hydrogel; freeze-drying the composite nanofiber colloidal hydrogel to obtain a composite nanofiber colloidal aerogel; The composite nanofiber colloidal aerogel is immersed in a solution containing polysiloxane, and then subjected to curing and ceramic treatments in sequence after the immersion to obtain the composite aerogel material.

2. The method for preparing a composite aerogel material according to claim 1, wherein: The preparation of the polypropylene nanofiber colloidal solution comprises: dissolving polyacrylonitrile in an organic solvent to obtain a polyacrylonitrile solution; The polyacrylonitrile solution is subjected to electrospinning technology to obtain polyacrylonitrile nanofiber cloth; The polyacrylonitrile nanofiber cloth is crushed, added into a mixed solvent of deionized water and tert-butyl alcohol, and subjected to shearing treatment under rotation conditions to obtain the polypropylene nanofiber colloidal solution.

3. The method for preparing a composite aerogel material according to claim 1, wherein: The first mixed solution is subjected to multiple freeze-thaw treatments, comprising the steps of: The first mixed solution is placed on a pre-frozen metal plate, then placed in a freezing setting for freezing treatment, and then placed at room temperature for thawing; and this process is repeated multiple times.

4. The method for preparing a composite aerogel material according to claim 1, wherein: In the solution containing polysiloxane, the ratio of polysilazane to ethanol is 100 mg to 1 g: 50 ml.

5. The method for preparing a composite aerogel material according to claim 1, wherein: The composite nanofiber colloidal aerogel is immersed in a solution containing polysiloxane, and then subjected to curing and ceramic treatments in sequence to obtain the composite aerogel material, comprising: immersing the composite nanofiber colloidal aerogel in a solution containing polysiloxane under vacuum conditions; drying the impregnated composite nanofiber colloidal aerogel at room temperature; heating and curing the dried composite nanofiber colloidal aerogel in a vacuum drying device to obtain the cured composite nanofiber colloidal aerogel; The solidified composite nanofiber colloidal aerogel is calcined to obtain the composite aerogel material.

6. The method for preparing a composite aerogel material according to claim 1, characterized in that: The concentration of the MXene solution is 4 to 10 mg / mL; Preferably, the mass ratio of MXene to polyacrylonitrile nanofibers in the first mixed solution is 100:5-100.

7. The method for preparing a composite aerogel material according to claim 2, characterized in that: The mass ratio of the organic solvent to polyacrylonitrile is 100:5-15; the organic solvent is N,N-dimethylformamide.

8. The method for preparing a composite aerogel material according to claim 5, characterized in that: The calcination temperature is 600-1000°C, the time is 60-180 minutes, and the heating rate is 1-5°C / minute; Preferably, the temperature of the heat curing treatment is 100 to 400° C., and the time is 60 to 180 minutes.

9. A composite aerogel material, characterized in that: The composite aerogel material is prepared by adopting the preparation method according to any one of claims 1 to 8.

10. Use of the composite aerogel material according to claim 9 in preparing flexible wearable electronic products.

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