Aerogel fibers and methods of making and using the same

Abstract

The application discloses aerogel fibers, a preparation method and application thereof, and belongs to the technical field of fiber preparation. The aerogel fibers with a skin-core structure are prepared by successfully combining high-silica fiber bundles and cross-linked polyimide aerogels through injection and PMMA tube forming. The polyimide is modified, so that the polyimide has good bonding force with the high-silica fiber bundles and good hydrophobicity. The aerogel fibers prepared by the application have superior mechanical properties, heat insulation properties and hydrophobic properties. Fabrics prepared by using the aerogel fibers can achieve excellent heat insulation and waterproof properties in extremely hot and humid environments. The technology has wide application prospects in application fields requiring high durability, excellent heat insulation and waterproof properties.

Description

TECHNICAL FIELD

[0001] The present application relates to an aerogel fiber and a preparation method and application thereof, and belongs to the technical field of fiber preparation. BACKGROUND

[0002] For a long time, people have been using thermal insulation fiber materials to protect the human body from high temperature and cold, and maintain a suitable body temperature. Due to its unique morphology, the fiber material usually exhibits excellent thermal insulation effect and weavability, which can meet the requirements of different use conditions and is widely used in thermal insulation clothing. So far, a series of thermal insulation fiber materials have been developed, including cellulose, protein, synthetic fibers, etc. However, due to the poor heat resistance of these traditional fiber materials, the thermal insulation effect is not ideal, which cannot meet the thermal insulation demand in extreme conditions such as aerospace, fire scene, polar region, etc., and seriously restricts the development of scientific research and living environment. Therefore, in order to achieve thermal insulation of the human body in harsh environments, it is urgent to develop new high-efficiency thermal insulation fibers.

[0003] In recent years, one-dimensional aerogel material aerogel fiber inherits the advantages of high porosity, large specific surface area and low density of aerogel material, and has attracted widespread attention in the fields of thermal insulation, electromagnetic shielding, adsorption, etc. Due to the porous structure of aerogel fiber, air convection, heat radiation and heat conduction are limited, which can effectively limit the thermal conductivity of aerogel fiber. Therefore, aerogel fiber is considered as a promising candidate material for thermal insulation clothing. Based on different raw materials and preparation processes, various aerogel fibers have been developed.

[0004] The high-porosity structure of aerogel fiber also leads to the deterioration of its mechanical properties, which is a great obstacle to the practical application of aerogel fiber. Therefore, researchers all over the world are trying to improve the mechanical properties of aerogel fiber. The mechanical properties of aerogel fiber still have a great gap with the standard of industrial fibers. It is still a great challenge to design aerogel fibers with high strength and thermal insulation.

[0005] It is well known that composite materials have the advantages of strong designability and excellent performance, and have been widely used in industrial applications and scientific research in the past few decades. Based on the composite reinforcement theory, in order to improve the mechanical properties of composite materials, various shapes of fillers have been developed, including particles, sheets, short fibers, long fibers, etc. It is worth noting that due to the fact that long fibers can bear most of the stress, the addition of long fibers can more significantly improve the mechanical properties of composite materials, but the poor adhesion between the reinforcing material and the substrate is also a common problem. At the same time, in the extremely hot and humid environment, when the material absorbs water, the thermal conduction medium becomes liquid, and the thermal conductivity coefficient increases significantly, resulting in a significant decrease in the thermal insulation performance of the material.

[0006] Therefore, how to prepare an aerogel fiber that can be used in humid and hot environments and has good mechanical properties, thermal insulation properties and hydrophobic properties is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] [Technical Issues]

[0008] Aerogel fibers with high porosity have poor mechanical properties;

[0009] Poor bonding between the reinforcing phase and the matrix in composite materials;

[0010] Materials used in hot and humid environments have poor thermal insulation properties.

[0011] [Technical Solution]

[0012] To address the aforementioned problems, this invention uses high-silica fiber bundles as the core layer and cross-linked polyimide as the shell layer. After lamination, these two materials are subjected to supercritical drying to prepare aerogel fibers. The aerogel fibers prepared by this invention simultaneously possess excellent thermal insulation, mechanical properties, and hydrophobicity.

[0013] The first objective of this invention is to provide a method for preparing aerogel fibers, comprising the following steps:

[0014] (1) Preparation of modified polyamic acid precursor:

[0015] A solution of diamine-terminated modified polysiloxane (a-PDMS) was added to a diamine solution, followed by the addition of acid anhydride to carry out a condensation reaction, thereby obtaining a modified polyamic acid precursor solution.

[0016] (2) Preparation of mixed precursor solutions:

[0017] A crosslinking agent is added to a modified polyamic acid precursor solution to form a three-dimensional structure. Then, a dehydrating agent and a catalyst are added and mixed evenly to obtain a mixed precursor solution.

[0018] (3) Preparation of aerogel fibers:

[0019] Using a PMMA tube as a container, a high-silica fiber bundle as a core layer, and a mixed precursor solution as a skin layer, an imidization reaction is carried out to gradually convert polyamic acid (PAA) into cross-linked polyimide, gradually forming a gel skeleton. After the reaction is completed, the PMMA tube is dissolved and dried to obtain aerogel fibers with a core-skin structure.

[0020] In one embodiment of the present invention, the diamine solution in step (1) is a diaminodiphenyl ether (ODA) solution, and its solvent is one of N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF), with a concentration of 10-30 mg / mL.

[0021] In one embodiment of the present invention, the solvent of the diamino-terminated modified polysiloxane (a-PDMS) solution in step (1) is one of N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF), with a mass concentration of 5-6%.

[0022] In one embodiment of the present invention, the acid anhydride in step (1) is one of 1,2,4,5-pyromellitic dianhydride (PMDA), 4,4-oxobisphthalic anhydride (ODPA), and 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0023] In one embodiment of the present invention, the molar ratio of diamine, acid anhydride and diamino-terminated modified polysiloxane (a-PDMS) in step (1) is 1:(1-2):(0.001-0.03).

[0024] In one embodiment of the present invention, the condensation reaction in step (1) is carried out at 150-300 rpm and 0-2°C for 10-14 h.

[0025] In one embodiment of the present invention, the acid anhydride is added in 3-6 portions in step (1) and is completed within 30 minutes.

[0026] In one embodiment of the present invention, the crosslinking agent in step (2) is 1,3,5-triaminophenoxybenzene (TAB); the dehydrating agent is acetic anhydride or propionic anhydride; and the catalyst is pyridine or triethylamine.

[0027] In one embodiment of the present invention, the molar ratio of the crosslinking agent, dehydrating agent, catalyst and diamine in step (1) in step (2) is (0.05-0.07):(5-10):(1-3):1.

[0028] In one embodiment of the present invention, the formation of the three-dimensional structure in step (2) is achieved by stirring at 150-300 rpm and 0-2°C for 3-5 min.

[0029] In one embodiment of the present invention, chemical imidization in step (2) is carried out by stirring at 100-300 rpm and 0-2°C for 0-10 min.

[0030] In one embodiment of the present invention, the diameter of the high silica fiber bundle in step (3) is 100-300 μm, and the diameter of the PMMA tube is 500-1000 μm.

[0031] In one embodiment of the present invention, the diameter of a single fiber in the high silica fiber bundle in step (3) is 15-25 μm.

[0032] In one embodiment of the present invention, in step (3), the high-silica fiber is inserted into the center of the PMMA tube, and the mixed precursor solution is injected into the gap between the high-silica fiber bundle and the PMMA tube to fix and carry out the imidization reaction.

[0033] In one embodiment of the present invention, the imidization reaction in step (3) is carried out at room temperature (20-30°C) for 10-15 min.

[0034] In one embodiment of the present invention, the PMMA tube is dissolved in step (3) using an organic solvent, wherein the organic solvent used is acetone.

[0035] In one embodiment of the present invention, the drying in step (3) is carried out by supercritical CO2 drying, specifically at 50°C and 10 MPa.

[0036] The second objective of this invention is to prepare aerogel fibers using the method described herein.

[0037] A third objective of the present invention is to provide a fabric woven from the aerogel fibers described herein.

[0038] In one embodiment of the present invention, the fabric is obtained by knitting or weaving.

[0039] The fourth objective of this invention is the application of the aerogel fibers and fabrics described herein in the preparation of functional materials.

[0040] In one embodiment of the invention, the functional material can be used in extreme hot and humid environments.

[0041] The fifth objective of this invention is to provide a method for improving the mechanical, thermal insulation, and hydrophobic properties of aerogel fibers under humid and hot conditions, comprising the following steps:

[0042] (1) Preparation of modified polyamic acid precursor:

[0043] A solution of diamine-terminated modified polysiloxane (a-PDMS) was added to a diamine solution, followed by the addition of acid anhydride to carry out a condensation reaction, thereby obtaining a modified polyamic acid precursor solution.

[0044] (2) Preparation of mixed precursor solutions:

[0045] A crosslinking agent is added to a modified polyamic acid precursor solution to form a three-dimensional structure. Then, a dehydrating agent and a catalyst are added and mixed evenly to obtain a mixed precursor solution.

[0046] (3) Preparation of aerogel fibers:

[0047] Using PMMA tubes as containers, high-silica fiber bundles as skin layers, and mixed precursor solutions as shell layers, an imidization reaction is carried out to gradually convert polyamic acid (PAA) into cross-linked polyimide, gradually forming a gel skeleton. After the reaction is complete, the PMMA tubes are dissolved and dried to obtain aerogel fibers with a core-shell structure.

[0048] [Beneficial Effects]

[0049] (1) In this invention, high silica fiber bundles and cross-linked polyimide aerogels are successfully combined by injection and PMMA tube molding to prepare aerogel fibers with a core-sheath structure. Due to the high strength of the high silica fiber bundles in the core layer, the aerogel fibers with a core-sheath structure have a mechanical strength of over 200 MPa in the temperature range of -100 to 400℃, and the mechanical properties do not decrease significantly.

[0050] (2) The siloxane structure (double-terminated amino-modified polysiloxane (a-PDMS)) introduced on the main chain of polyimide in this invention is similar to silica (high silica fiber), both of which have a large number of silicon-oxygen bonds, resulting in good bonding force, thereby making the prepared core-shell structure aerogel fiber have good mechanical properties.

[0051] (3) The present invention uses a low shrinkage rate and porous polyimide aerogel skin to give aerogel fibers excellent thermal insulation performance; the textiles woven with the aerogel fibers of the present invention have greatly improved thermal insulation performance compared with cotton fabrics in thermal insulation tests under humid and hot environments, and the surface temperature under a 200°C heating table is much lower than that of cotton fabrics (around 190°C). Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the microstructure of the aerogel fiber prepared in Example 1.

[0053] Figure 2 The graph shows the mechanical properties of pure polyimide in Comparative Example 1.

[0054] Figure 3 The diagram shows the mechanical properties of the aerogel fiber in Example 1.

[0055] Figure 4 This is a diagram of the fabric being mounted on the loom.

[0056] Figure 5 The graph shows the test results of the contact angle of the fabrics woven from aerogel fibers in Examples 1 and 2. Detailed Implementation

[0057] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0058] Test method:

[0059] 1. Mechanical property testing:

[0060] The mechanical properties of aerogel fibers were tested using an Instron 5969 electronic universal testing machine from Instron Corporation, USA. Specifically, the fiber testing mode was used, with a 100 N stress sensor, a tensile rate of 5 mm / min, and each sample was tested 5 times and the average value was taken.

[0061] 2. Thermal insulation performance test under humid and hot environment:

[0062] After spraying 10 mL of deionized water onto the surface of a 4×4 cm sample, place it on a 200 ℃ heating stage and record its surface temperature after 60 min. The humidity is 70%.

[0063] 3. Contact angle test:

[0064] The surface wettability of the fabric was tested using an OCA20 contact angle tester (Df. GmbH, Germany); the droplet volume used was 5 μL, and each sample was randomly measured 5 times and the average value was taken.

[0065] Raw materials used in the examples and comparative examples:

[0066] 1,2,4,5-Pyromellitic dianhydride (PMDA, 99%), diaminodiphenyl ether (ODA, 98%), 1,3,5-tris(4-aminophenoxy)benzene (TAB, 98%), N,N-dimethylacetamide (DMAc, 99%), acetic anhydride (99%), and triethylamine (TEA) were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0067] Amino-terminated modified polysiloxane (a-PDMS): relative molecular mass 860 g / mol, purchased from Shin-Etsu (KF-8010);

[0068] The diameter of a single fiber in the high-silica fiber bundle is 20μm, and there are 19 fibers in total;

[0069] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available.

[0070] Unless otherwise specified, the percentages (%) used in the examples and comparative examples refer to mass percentages.

[0071] The solutions used in the examples and comparative examples do not specifically specify that the solvent is water.

[0072] Example 1

[0073] A method for preparing aerogel fibers includes the following steps:

[0074] (1) Preparation of modified polyamic acid precursor:

[0075] Dissolve 0.6 g (3 mmol) of ODA in 25 mL of freshly distilled DMAc to obtain an ODA solution with a concentration of 24 mg / mL;

[0076] 0.042 g (0.049 mmol) of α-PDMS was dissolved in 0.75 g of DMAc to obtain an α-PDMS solution;

[0077] Then, the α-PDMS solution was added to the ODA solution to obtain a mixed solution;

[0078] 0.676 g (3.1 mmol) of PMDA was divided into five equal portions and added to the mixed solution within 30 min. The reaction was carried out in a water bath (0 °C) for 12 h with constant stirring (200 rpm) to obtain a modified polyamic acid precursor solution.

[0079] (2) Preparation of mixed precursor solutions:

[0080] 0.076 g (0.19 mmol) of crosslinking agent TAB was added to the modified polyamic acid precursor solution, and the mixture was stirred at 200 rpm and 0 °C for 3 min to form a three-dimensional structure; then 2.45 g (24 mmol) of dehydrating agent acetic anhydride (Ac2O) and 0.61 g (6 mmol) of catalyst triethylamine (TEA) were added, and the mixture was stirred at 200 rpm and 0 °C for 3 min to obtain a mixed precursor solution;

[0081] (3) Preparation of aerogel fibers:

[0082] A 100 μm diameter high-silica fiber bundle was inserted into a 500 μm inner diameter PMMA tube. Appropriately sized rings were attached to both ends of the tube. The high-silica fiber bundle was then inserted into the rings and tightened, so that the high-silica fiber bundle was located as close to the center of the PMMA tube as possible. The mixed precursor solution obtained in step (2) was then transferred to a syringe within 15 minutes after preparation and injected into the PMMA tube until it was full. An imidization reaction was carried out at room temperature, and polyamic acid (PAA) was gradually converted into cross-linked polyimide, gradually forming a gel skeleton. After standing for 12 hours, the gelation process was completed.

[0083] After the reaction was completed, the fiber was immersed in ethanol to dissolve the residual PMMA tube and was repeatedly washed to remove the residual organic solvent. The fiber was dried using supercritical CO2 drying method. The ethanol in the aerogel fiber was removed at 50°C and a gas pressure of 10 MPa to obtain a core-sheath structure aerogel fiber.

[0084] The microstructure of the prepared aerogel fibers is as followsFigure 1 As shown.

[0085] Comparative Example 1: No high-silica fiber bundles added

[0086] The high-silica fiber bundle in step (3) of Example 1 is omitted, and the a-PDMS in step (1) is also omitted. Everything else is the same as in Example 1 to obtain pure polyimide gel fiber.

[0087] The fibers obtained in Example 1 and Comparative Example 1 were subjected to mechanical property tests, and the test results are as follows: Figure 2 and Figure 3 ;

[0088] from Figure 2 , Figure 3 The comparison shows that the addition of high silica fiber bundles disperses most of the tensile stress, resulting in a significant increase in the tensile stress of the core-sheath structure aerogel fibers.

[0089] Example 2: Changing the amount of modifier

[0090] The amount of a-PDMS added in step (1) was adjusted to 0.014 g (0.016 mmol), 0.028 g (0.032 mmol), 0.056 g (0.065 mmol), and 0.071 g (0.083 mmol), with doping amounts of 1%, 2%, 4%, and 5% (doping amount = mass of a-PDMS / (mass of a-PDMS + mass of ODA + mass of PMDA + mass of TAB)), and other parameters remained the same as in Example 1, to obtain aerogel fibers with a core-sheath structure.

[0091] Comparative Example 2: Different Modifiers

[0092] In step (1), a-PDMS was adjusted to polydimethylsiloxane (viscosity: 0.65cSt (25℃), PubChem number: 24705), while other steps remained the same as in Example 1, to obtain aerogel fibers.

[0093] Comparative Example 3: Different Modifiers

[0094] In step (1), a-PDMS was adjusted to be a dual-hydroxyl-terminated polysiloxane (CAS No.: 156327-07-0, PubChem No.: 22558249, hydroxyl-terminated dual-end polydimethylsiloxane), while the rest remained the same as in Example 1, to obtain aerogel fibers.

[0095] Comparative Example 4: Different Fiber Lengths

[0096] In step (3), the high-silica fiber bundles are replaced with aramid fiber bundles, while the rest remains the same as in Example 1, to obtain aerogel fibers.

[0097] Comparative Example 5 (Unmodified)

[0098] Omit a-PDMS in step (1) of Example 1, and keep everything else the same as in Example 1 to obtain aerogel fibers.

[0099] Comparative Example 6: Pure cross-linked polyimide aerogel fibers

[0100] (1) Preparation of modified polyamic acid precursor:

[0101] Dissolve 0.6 g (3 mmol) of ODA in 25 mL of freshly distilled DMAc to obtain an ODA solution with a concentration of 24 mg / mL;

[0102] 0.042 g (0.049 mmol) of α-PDMS was dissolved in 0.75 g of DMAc to obtain the α-PDMS solution;

[0103] Then, the α-PDMS solution was added to the ODA solution to obtain a mixed solution;

[0104] 0.676 g (3.1 mmol) of PMDA was divided into five equal portions and added to the mixed solution within 30 min. The reaction was carried out in a water bath (0 °C) for 12 h with constant stirring (200 rpm) to obtain a modified polyamic acid precursor solution.

[0105] (2) Preparation of mixed precursor solutions:

[0106] 0.076 g (0.19 mmol) of crosslinking agent TAB was added to the modified polyamic acid precursor solution, and the mixture was stirred at 200 rpm and 0 °C for 3 min to form a three-dimensional structure; then 2.45 g (24 mmol) of dehydrating agent acetic anhydride (Ac2O) and 0.61 g (6 mmol) of catalyst triethylamine (TEA) were added, and the mixture was stirred at 200 rpm and 0 °C for 3 min to obtain a mixed precursor solution;

[0107] (3) Polyimide aerogel fiber:

[0108] The mixed precursor solution prepared above was injected into a PMMA tube with an inner diameter of 500 μm within 15 min, and an imidization reaction was carried out at room temperature. The polyamic acid (PAA) was gradually converted into cross-linked polyimide and gradually formed a gel skeleton. After standing for 12 h, the gelation process was completed.

[0109] After the reaction was completed, the fiber was immersed in ethanol to dissolve the residual PMMA tube and was repeatedly washed to remove the residual organic solvent. The fiber was dried using supercritical CO2 drying method. The ethanol in the aerogel fiber was removed at 50°C and a gas pressure of 10 MPa to obtain pure polyimide aerogel fiber.

[0110] The aerogel fibers obtained in Examples 1 and 2 and Comparative Examples 1-6 were subjected to performance tests, and the test results are shown in Table 1 below:

[0111] As can be seen from Table 1:

[0112] The aerogel fibers with core-sheath structure prepared in Examples 1 and 2 have a tensile strength of over 214 MPa;

[0113] Comparative Example 1: The tensile strength of conventional polyimide aerogel fibers is only 25 MPa.

[0114] Comparative Examples 2 and 3, where the modifier was changed, also showed a decrease in their mechanical properties;

[0115] Comparative Example 4 shows that replacing the core material reduced the bonding strength between the core and the skin, resulting in a decrease in mechanical properties.

[0116] Comparative Example 5 was not modified, and its mechanical properties decreased slightly.

[0117] Comparative Example 6 is a pure cross-linked aerogel fiber prepared after modification, with a mechanical property of only 17 MPa.

[0118] Table 1 Mechanical Properties

[0119]

[0120] As shown in Table 1, pure polyimide aerogel fibers without long fibers have extremely low tensile strength and poor mechanical properties.

[0121] Example 3

[0122] Aerogel fibers are made into 4×4cm fabrics, as shown in the machine drawing. Figure 4 As shown, the warp and weft density of the fabric is 3.5 threads / cm; at the same time, a cotton fabric with the same structure and size was selected as a control.

[0123] The thermal insulation performance of the fabric was tested under a humid and hot environment. The test results are as follows:

[0124] The performance of the aerogel fibers prepared in Examples 1 and 2 and Comparative Examples 2-5 was tested, and the test results are as follows:

[0125] Table 2 Test Results of Thermal Insulation Performance

[0126]

[0127] Table 3. Test results of thermal insulation performance in Example 2

[0128]

[0129] As can be seen from Tables 2 and 3, the aerogel fibers prepared in Examples 1 and 2 have better thermal insulation performance in humid and hot environments.

[0130] Table 4 Hydrophobicity test results

[0131]

[0132] As can be seen from Table 4, the fabric prepared from the aerogel fiber in Example 1 has good hydrophobicity.

[0133] Figure 5 The contact angle test results of the fabric woven from the composite aerogel fibers prepared in Example 2 are as follows: Figure 5 It can be seen that as the amount of modifier increases, the contact angle increases and the hydrophobicity is enhanced. When the doping amount reaches 3% (0.042 g, 0.049 mmol), the contact angle reaches 121°. Further increasing the amount of modifier does not significantly change the hydrophobicity.

[0134] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method of making an aerogel fiber, characterized by, The method comprises the following steps: (1) Preparation of modified polyamic acid precursor: A diamine solution is added with a double-end amino-modified polysiloxane solution, and then an acid anhydride is added to perform a condensation reaction to obtain a modified polyamic acid precursor solution; (2) Preparation of mixed precursor solution: A crosslinking agent is added to the modified polyamic acid precursor solution to form a three-dimensional structure, and then a dehydrating agent and a catalyst are added and uniformly mixed to obtain a mixed precursor solution; (3) Preparation of aerogel fiber: A PMMA tube is used as a container, a high-silica fiber bundle is inserted into the PMMA tube, the mixed precursor solution obtained in step (2) is transferred into the PMMA tube until it is filled, the high-silica fiber bundle serves as a core layer, and the mixed precursor solution serves as a skin layer, an imidization reaction is performed, the polyamic acid is gradually converted into crosslinked polyimide, and a gel skeleton is gradually formed; after the reaction is completed, the PMMA tube is dissolved and dried to obtain an aerogel fiber with a skin-core structure.

2. The method of claim 1, wherein, In step (1), the diamine solution is a diaminodiphenyl ether solution, the solvent is one of N,N-dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylformamide, and the concentration is 10-30 mg / mL.

3. The method of claim 1, wherein, In step (1), the solvent of the double-end amino-modified polysiloxane solution is one of N,N-dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylformamide, and the mass concentration is 5-6%.

4. The method of claim 1, wherein, In step (1), the molar ratio of the diamine, the acid anhydride, and the double-end amino-modified polysiloxane is 1:(1-2):(0.001-0.03).

5. The method of claim 1, wherein, In step (2), the molar ratio of the crosslinking agent, the dehydrating agent, the catalyst, and the diamine in step (1) is (0.05-0.07):(5-10):(1-3):

1.

6. The method of claim 1, wherein, The diameter of the high-silica fiber bundle is 100-300 μm.

7. The method of claim 1, wherein, In step (1), the acid anhydride is one of 1,2,4,5-benzene tetracarboxylic dianhydride, 4,4-oxybisphthalic anhydride, and 3,3',4,4'-diphenyl tetracarboxylic dianhydride.

8. The method of claim 1, wherein, In step (1), the condensation reaction is performed at 150-300 rpm and 0-2°C for 10-14 h.

9. The method of claim 1, wherein, In step (2), the crosslinking agent is 1,3,5-triaminophenoxybenzene, the dehydrating agent is acetic anhydride or propionic anhydride, and the catalyst is pyridine or triethylamine.

10. The method of claim 1, wherein, In step (3), the diameter of a single fiber in the high-silica fiber bundle is 15-25 μm.

11. The method of claim 1, wherein, In step (3), the PMMA tube is dissolved by using an organic solvent, and the organic solvent used is acetone.

12. The aerogel fiber prepared by the method of any one of claims 1-11.

13. A fabric, characterized by The fabric is woven by using the aerogel fiber of claim 12.

14. The aerogel fiber of claim 12 or the fabric of claim 13 for use in preparing a functional material.

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