CN110628217B - Nanofiber modified polyimide aerogel material and preparation method thereof - Google Patents

Nanofiber modified polyimide aerogel material and preparation method thereof Download PDF

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CN110628217B
CN110628217B CN201910932333.0A CN201910932333A CN110628217B CN 110628217 B CN110628217 B CN 110628217B CN 201910932333 A CN201910932333 A CN 201910932333A CN 110628217 B CN110628217 B CN 110628217B
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polyamic acid
aerogel material
short fibers
modified polyimide
aerogel
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CN110628217A (en
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刘天西
樊玮
侯豪情
赵兴宇
杨帆
薛甜甜
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Jiangnan University
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    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
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    • C08J9/286—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum the liquid phase being a solvent for the monomers but not for the resulting macromolecular composition, i.e. macroporous or macroreticular polymers
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    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
    • C08J2201/048—Elimination of a frozen liquid phase
    • C08J2201/0484—Elimination of a frozen liquid phase the liquid phase being aqueous
    • C—CHEMISTRY; METALLURGY
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    • C08J2205/00—Foams characterised by their properties
    • C08J2205/02—Foams characterised by their properties the finished foam itself being a gel or a gel being temporarily formed when processing the foamable composition
    • C08J2205/026—Aerogel, i.e. a supercritically dried gel
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    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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    • C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2427/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
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    • C08J2479/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2461/00 - C08J2477/00
    • C08J2479/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
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Abstract

The invention discloses a nanofiber modified polyimide aerogel material and a preparation method thereof, and belongs to the technical field of aerogel materials and preparation thereof. According to the invention, the polyimide nano short fibers and the polyvinylidene fluoride nano short fibers are added into the aerogel, so that on one hand, the mechanical strength of the aerogel can be enhanced by adding the nano fibers, and the hydrophobic property of the aerogel can be improved; on the other hand, the nano-fibers are added to inhibit the shrinkage of the aerogel, so that the modulus of the aerogel is greatly improved under the condition that the density change is small. The polyimide aerogel has excellent comprehensive performance, simple and easy preparation process, environmental protection and widened application range.

Description

Nanofiber modified polyimide aerogel material and preparation method thereof
Technical Field
The invention relates to a nanofiber modified polyimide aerogel material and a preparation method thereof, and belongs to the technical field of aerogel materials and preparation thereof.
Background
Aerogel refers to a gel material consisting of a microporous solid with the dispersed phase being a gas. The aerogel material has the characteristics of low density, high specific surface area and the like, and has wide application prospects in the fields of aerospace, petrochemical industry, automobile industry, building heat preservation and the like.
Due to the low density of the aerogel, the aerogel has high porosity and a hierarchical pore structure, so that the aerogel has an ultralow density. Therefore, the aerogel has good application prospects in many fields such as buildings, automobiles, aerospace, household appliances, petrochemical plants, outdoor sports and the like. However, in the practical application process, in addition to the requirement of low density, the aerogel is also required to have further improved strength, so as to expand the application range. For example, in the field of building heat insulation materials, besides the requirement of light weight and heat insulation, the materials themselves are required to have certain strength, and in the case of damp places, the hydrophobic property of the materials needs to be improved to improve the heat insulation capability.
Polyimide (Polyimide) is a special engineering plastic with the advantages of good molding processability, high mechanical strength, good thermal stability and the like, and is widely applied to various fields of national economy. Polyimide aerogel material is a common aerosol material, can be used as materials with light weight, heat insulation performance, compression elasticity and the like, and is mainly modified from the aspects of heat insulation performance and elasticity at present. However, polyimide aerogels themselves have limited their use to a wider range of applications due to their low strength and poor hydrophobic properties.
Disclosure of Invention
[ problem ] to provide a method for producing a semiconductor device
Polyimide aerogels themselves have limited their use to a wider range of applications due to their low strength and poor hydrophobic properties.
[ technical solution ] A
In order to solve the problems, the invention provides a nanofiber modified polyimide aerogel material and a preparation method thereof, which overcome the defects of low strength and poor hydrophobic property of the existing polyimide aerogel; on the other hand, the nano-fibers are added to inhibit the shrinkage of the aerogel, so that the modulus of the aerogel is greatly improved under the condition that the density change is small.
Specifically, the invention firstly provides a preparation method of a nanofiber modified polyimide aerogel material, which comprises the following steps: mixing water-soluble polyamic acid, triethylamine and water, obtaining polyamic acid hydrogel by a sol-gel method, adding polyimide nano short fibers and polyvinylidene fluoride nano short fibers into the prepared polyamic acid hydrogel, mixing, freeze-drying, and performing heat treatment in an inert atmosphere to obtain a nanofiber modified polyimide aerogel material; wherein the length of the polyimide nano short fiber is 0.2-0.4 mm; the length of the polyvinylidene fluoride nano short fiber is 0.2-0.4 mm.
In one embodiment of the present invention, the diameter of the polyimide nano short fiber is 300-1000nm, preferably 800 nm; the diameter of the polyvinylidene fluoride nano short fiber is 300-1000nm, and is preferably 800 nm.
In one embodiment of the invention, the sol-gel time is 12 to 24 hours.
In an embodiment of the present invention, the freeze drying is specifically freezing in a low-temperature constant-temperature reaction bath, and then drying in a freeze dryer, specifically: the temperature of the low-temperature constant-temperature reaction bath is-20 to-90 ℃, and the freezing time is 40 to 120 min; the drying temperature of the freeze dryer is-30 to-80 ℃, preferably-50 ℃, the vacuum degree is 10 to 40Pa, preferably 15Pa, and the drying time is 24 to 60 hours.
In one embodiment of the present invention, the heat treatment process is: carrying out heat treatment for 1.5-2.5 h at 220-270 ℃ in an inert atmosphere; the inert atmosphere comprises nitrogen, helium, argon and other inert atmospheres.
In one embodiment of the present invention, the mass ratio of the water-soluble polyamic acid to the triethylamine to the water is 1 to 10:0.5 to 5: 100.
In one embodiment of the present invention, the polyimide nano short fibers and the polyvinylidene fluoride nano short fibers are added in an amount of 0.1% to 0.4% and 0.1% to 0.4% of the mass of the polyamic acid hydrogel, respectively.
In one embodiment of the present invention, the water-soluble polyamic acid is prepared by the following method: firstly, dissolving a diamine monomer in a polar solvent, then adding a dicarboxylic anhydride monomer, carrying out polymerization reaction in an ice-water bath, then adding organic amine, and continuing the reaction to obtain a water-soluble polyamic acid solution; pouring the prepared water-soluble polyamic acid solution into water to precipitate to obtain polyamic acid, and freeze-drying the polyamic acid to obtain the water-soluble polyamic acid.
In one embodiment of the present invention, the molar ratio of the diamine monomer, the polar solvent, the dibasic anhydride monomer and the organic amine is 1:27.5:1: 1.
In one embodiment of the present invention, the diamine monomer is p-phenylenediamine or 4, 4' -diaminodiphenyl ether; the binary anhydride monomer is any one of pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride or diphenyl ether tetracarboxylic dianhydride; the polar solvent is any one of dimethylacetamide, N-methylpyrrolidone or dimethylformamide; the organic amine is any one of triethylamine or dipropylamine.
In one embodiment of the present invention, the polyimide nano short fiber is preferably prepared by the following method: firstly, dissolving a diamine monomer in a polar solvent, then adding a dicarboxylic anhydride monomer, and carrying out polymerization reaction in an ice-water bath to obtain a polyamic acid solution; and (3) performing electrostatic spinning on the prepared polyamic acid solution to prepare a polyamic acid nanofiber membrane, dispersing the polyamic acid nanofiber membrane into short fibers, drying the short fibers, and imidizing the short fibers to obtain the polyimide nano short fibers.
In one embodiment of the present invention, the operating parameters of the electrospinning are: the voltage is 15-20 kV, the spinning distance is 10-25 cm, and the injection speed is 0.08 mm/min.
Secondly, the invention provides a nanofiber modified polyimide aerogel material prepared by the method.
The length-diameter ratio of the nanofibers added into the aerogel is large, the surface area of the nanofibers is large, short fibers are wrapped by gel in gel liquid, so that a soaking interface of the nanofibers and sol is formed, the soaking interface has a physical adsorption effect or a chemical adsorption effect, a sol fiber transition layer structure is easily formed under the adsorption effect, compared with pure sol, the material added with the fibers has better bonding strength, relative slippage of the material can be effectively restrained, and the improvement of the macroscopic stability performance is shown. In addition, after a proper amount of fibers are mixed in the sol, the fibers are distributed in the sol randomly and uniformly, and the uniformly distributed fibers show a network structure form in space. When the mixture bears external load, the fiber bears load stress and restrains aggregate sliding, and then the cracking of the matrix is reduced. The incorporation of fibers can take up a portion of the stress, preventing crack propagation at the crack, thereby increasing the strength of the aerogel material. Finally, the invention also provides application of the nanofiber modified polyimide aerogel material.
In one embodiment of the invention, the application comprises an application in the fields of construction, automotive, aerospace, household appliances, chemical engineering or outdoor sports.
The invention has the following beneficial technical effects:
(1) the polyimide aerogel with higher modulus and hydrophobic property is successfully prepared by adopting simple freeze drying and short fiber modification, and can be used for heat preservation and insulation application in a humid environment.
(2) According to the invention, the polyimide nano short fibers and the polyvinylidene fluoride nano short fibers are added into the polyamic acid hydrogel, so that the mechanical property of the prepared nanofiber modified polyimide aerogel material is obviously improved, and the Young modulus is up to 3.4 MPa; in addition, the hydrophobic property of the aerogel is greatly improved, and the maximum contact angle with water can reach 134 degrees;
(3) according to the invention, the nano short fibers are added to inhibit the shrinkage of the aerogel, so that the modulus of the aerogel is greatly improved under the condition of small density change, and after the polyimide nano short fibers and the polyvinylidene fluoride nano short fibers are added, the density of the aerogel is from 65mg/cm3Increased to 68mg/cm3However, the Young modulus is increased from 1.6MPa to 3.3MPa, and the strength is doubled.
Drawings
FIG. 1 is a stress-strain curve of the nanofiber modified polyimide aerogel prepared in examples 1-5.
FIG. 2 is a graph of Young's modulus of nanofiber modified polyimide aerogels prepared in examples 1-5.
Fig. 3 is a digital photograph of a nanofiber modified polyimide aerogel load bearing prepared in example 3.
FIG. 4 shows the contact angle test results of the nanofiber-modified polyimide aerogel prepared in examples 2 to 5.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
The stress-strain curve measuring method comprises the following steps: and placing the prepared sample on a universal testing machine for compression testing to obtain a stress-strain curve.
Young's modulus measurement method: from the slope of the linear region in the stress-strain curve.
Contact angle test method: and (3) adopting a water drop method, namely dropping a drop of water on the surface of the sample, and calculating the contact angle of the sample by digital photographing.
Polyvinylidene fluoride nano short fiber: obtained by conventional electrospinning and dispersion by a disperser.
Example 1
(1) Preparation of Water-soluble Polyamic acid: n, N-dimethylacetamide is used as a solvent, 4' -diaminodiphenyl ether and terephthalic anhydride in equal molar ratio are added to carry out condensation polymerization reaction in an ice water bath to prepare polyamic acid with solid content of 15%. The specific process is as follows: 8.0096g of 4, 4' -diaminodiphenyl ether is dissolved in 95.57g N, N-dimethylacetamide, 8.8556g of pyromellitic dianhydride is added, and the mixture reacts in an ice-water bath for 5 hours. Then, 4.0476g of triethylamine is added into the mixture, and the mixture is reacted for 5 hours to prepare a water-soluble polyamic acid solution with the solid content of 15 percent; precipitating the prepared water-soluble polyamic acid by using deionized water, and then washing and freeze-drying to obtain a water-soluble polyamic acid prepolymer for later use;
(2) preparing polyimide nano short fibers: n, N-dimethylacetamide is used as a solvent, and polyamic acid electrostatic spinning with the solid content of 15% is prepared by condensation polymerization reaction of 4, 4' -diaminodiphenyl ether and terephthalic anhydride in an ice-water bath according to an equal molar ratio to obtain the short fiber. The specific process is as follows: 8.0096g of 4, 4' -diaminodiphenyl ether is dissolved in 95.57g N, N-dimethylacetamide, 8.8556g of pyromellitic dianhydride is added, and the mixture is reacted in an ice-water bath for 5 hours. A polyamic acid solution was prepared. Adding the prepared polyamic acid mixed solution into an injector, performing electrostatic spinning (the voltage is 18kV, the spinning distance is 15cm, and the injection speed is 0.08mm/min) to obtain a polyamic acid nanofiber membrane, dispersing the polyamic acid nanofiber membrane into short fibers by a dispersion machine, and then drying and imidizing the short fibers to obtain polyimide nano short fibers, wherein the length of the polyimide nano short fibers is 0.2-0.3mm, and the diameter of the polyimide nano short fibers is 300-400 nm;
(3) taking 50mL of deionized water, 2.5g of water-soluble polyamic acid and 2.5g of triethylamine, uniformly mixing, and obtaining polyamic acid hydrogel after 24h of sol-gel process; the hydrogel is frozen and dried, and is subjected to heat treatment at 240 ℃ in the air for 1.0h to obtain the polyimide aerogel which is named as PIAs-0.
Example 2
The present embodiment is different from embodiment 1 in that: after the polyamic acid hydrogel obtained in step (3) of example 1 was added with 0.125g of the polyimide nano-short fiber prepared in step (2) of example 1, that is: taking 50mL of deionized water, 2.5g of water-soluble polyamic acid and 2.5g of triethylamine, uniformly mixing, obtaining polyamic acid hydrogel after 24h of sol-gel process, then adding 0.125g of polyimide nano short fiber into the hydrogel, after uniform mixing, freeze-drying a sample, and carrying out heat treatment at 240 ℃ in the air for 1.0h to obtain polyimide nano fiber modified polyimide aerogel, wherein the name of the polyimide nano fiber modified polyimide aerogel is PIAs-1.
Example 3
The present embodiment is different from embodiment 1 in that: after the polyamic acid hydrogel obtained in the step (3) of example 1 was added with 0.125g of the polyimide nano-staple fiber obtained in the step (2) of example 1 and 0.125g of the polyvinylidene fluoride nano-staple fiber (length 0.2-0.3mm, diameter 300-400nm), that is: and (3) taking 50mL of deionized water, 2.5g of water-soluble polyamic acid and 2.5g of triethylamine, uniformly mixing, and obtaining the polyamic acid hydrogel after 24h of sol-gel process. Then 0.125g of polyimide nano short fiber and 0.125g of polyvinylidene fluoride nano short fiber are added into the hydrogel, after the mixture is uniformly mixed, a sample is freeze-dried and then is subjected to heat treatment for 1.0h at 240 ℃ in nitrogen atmosphere, and a nano fiber modified polyimide aerogel material is obtained and named as PIAs-2.
Example 4
The present embodiment is different from embodiment 3 in that: after the polyamic acid hydrogel obtained in the step (3) of example 1 was added with 0.125g of the polyimide nano-staple fiber obtained in the step (2) of example 1 and 0.15g of polyvinylidene fluoride nano-staple fiber (length 0.2-0.3mm, diameter 300-: and (3) taking 50mL of deionized water, 2.5g of water-soluble polyamic acid and 2.5g of triethylamine, uniformly mixing, and obtaining the polyamic acid hydrogel after 24h of sol-gel process. Then 0.125g of polyimide nano short fiber and 0.15g of polyvinylidene fluoride nano short fiber are added into the hydrogel, after uniform mixing, a sample is freeze-dried and then is subjected to heat treatment at 240 ℃ in nitrogen atmosphere for 1.0h to obtain a nano-fiber modified polyimide aerogel material, and the nano-fiber modified polyimide aerogel material is named as PIAs-3.
Example 5
The present embodiment is different from embodiment 3 in that: after the polyamic acid hydrogel obtained in the step (3) of example 1 was added with 0.125g of the polyimide nano-staple fiber obtained in the step (2) of example 1 and 0.20g of polyvinylidene fluoride nano-staple fiber (length 0.2-0.3mm, diameter 300-400nm), that is: and (3) taking 50mL of deionized water, 2.5g of water-soluble polyamic acid and 2.5g of triethylamine, uniformly mixing, and obtaining the polyamic acid hydrogel after 24h of sol-gel process. Then adding 0.125g of polyimide nano short fiber and 0.20g of polyvinylidene fluoride nano short fiber into the hydrogel, uniformly mixing, freeze-drying the sample, and carrying out heat treatment at 240 ℃ in nitrogen atmosphere for 1.0h to obtain a nano-fiber modified polyimide aerogel material, wherein the name of the nano-fiber modified polyimide aerogel material is PIAs-4
The aerogel materials prepared in examples 1 to 5 were subjected to performance tests such as stress strain, young's modulus, contact angle, and the like, and the results are shown in fig. 1 to 4.
FIG. 1 is a stress-strain curve of the nanofiber modified polyimide aerogel prepared in examples 1-5, and it can be seen that the stress of PIAs-2 is the greatest, reaching 428KPa, when 60% strain occurs.
FIG. 2 is a graph showing the Young's moduli of PIAs-0, PIAs-1 and PIAs-2, and it can be seen that the Young's moduli of PIAs-0, PIAs-1, PIAs-2, PIAs-3 and PIAs-4 are 1.6MPa, 3.1MPa, 3.3MPa, 3.4M Pa and 3.2MPa, respectively.
The aerogel prepared in example 1 had a density of 65mg/cm3The aerogel prepared in example 3 had a density of 68mg/cm3However, the young's modulus of the aerogel prepared in example 3 is 2 times that of the aerogel prepared in example 1, and it can be found that the invention can greatly improve the modulus of the aerogel under the condition of small density change.
FIG. 3 is a digital photograph of a load-bearing PIAs-2, wherein the mass of the PIAs-2 is 180mg and the loaded mass is 350g, and it can be seen that the aerogel material prepared by the method can bear 1900 times of the mass of the aerogel material without obvious deformation.
FIG. 4 is a schematic diagram showing the results of water contact angle tests of PIAs-1, PIAs-2, PIAs-3 and PIAs-4, and it can be seen that the contact angle of PIAs-1 is 97 degrees, while the contact angles of PIAs-2, PIAs-3 and PIAs-4 are 121 degrees, 134 degrees and 122 degrees, respectively, and it can be seen that after polyvinylidene fluoride nano short fibers are added, the hydrophobic property of the aerogel material is greatly improved.
Comparative example 1
When the heat treatment is carried out in the air, the rest steps and the operation parameters are consistent with those of the example 3, the polyimide aerogel material is prepared, and the performance of the polyimide aerogel material is tested, and the performance of the polyimide aerogel material is found to have no obvious change in the Young modulus and other properties of the aerogel material prepared by the heat treatment in the air, but the hydrophobic property is poor, and the water contact angle is only 103 degrees and is obviously lower than the 121 degrees of the example 3.
Comparative example 2
When the dispersion machine in the step (2) in the embodiment 1 disperses the long fibers (the length of the polyimide nanofibers is 1-2 mm), the long fibers are used for replacing the polyimide nanofibers in the embodiment 3 to prepare the polyimide aerogel material, and the performance test of the polyimide aerogel material shows that the Young modulus of the prepared aerogel material is obviously reduced to 2.2 MPa.
Comparative example 3
When polyvinylidene fluoride nanofiber's length was 1 ~ 2mm, with this polyvinylidene fluoride nanometer short fiber among the longer fibre replacement embodiment 3, polyimide aerogel material was obtained in the preparation, tests its performance, and the discovery, the contact angle of the aerogel material that the preparation obtained drops to some extent, reduces to 114.
Comparative example 4
When the addition amount of the polyimide nano short fibers is 1g, the other steps are consistent with those in example 3, the polyimide aerogel material is prepared, and the performance of the polyimide aerogel material is tested, so that the Young modulus of the prepared aerogel material is obviously reduced to 1.9 MPa.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (9)

1. A preparation method of a nanofiber modified polyimide aerogel material is characterized by comprising the following steps: mixing water-soluble polyamic acid, triethylamine and water, obtaining polyamic acid hydrogel by a sol-gel method, adding polyimide nano short fibers and polyvinylidene fluoride nano short fibers into the prepared polyamic acid hydrogel, mixing, freeze-drying, and performing heat treatment in an inert atmosphere to obtain a nanofiber modified polyimide aerogel material; wherein the length of the polyimide nano short fiber is 0.2-0.4 mm; the length of the polyvinylidene fluoride nano short fibers is 0.2-0.4 mm; the addition amount of the polyimide nano short fibers and the polyvinylidene fluoride nano short fibers is 0.1-0.4% and 0.1-0.4% of the mass of the polyamic acid hydrogel respectively.
2. The method for preparing the nanofiber modified polyimide aerogel material as claimed in claim 1, wherein the heat treatment process comprises: carrying out heat treatment for 1.5-2.5 h at 220-270 ℃ in an inert atmosphere; the inert atmosphere comprises nitrogen, helium and argon.
3. The preparation method of the nanofiber modified polyimide aerogel material as claimed in claim 1 or 2, wherein the mass ratio of the water-soluble polyamic acid to the triethylamine to the water is 1-10: 0.5-5: 100.
4. The method for preparing nanofiber modified polyimide aerogel material according to claim 1, wherein the water-soluble polyamic acid is prepared by the following steps: firstly, dissolving a diamine monomer in a polar solvent, then adding a dicarboxylic anhydride monomer, carrying out polymerization reaction in an ice-water bath, then adding organic amine, and continuing the reaction to obtain a water-soluble polyamic acid solution; precipitating, and freeze-drying to obtain water-soluble polyamic acid.
5. The preparation method of the nanofiber modified polyimide aerogel material as claimed in claim 4, wherein the molar ratio of the diamine monomer, the polar solvent, the dibasic anhydride monomer and the organic amine is 1:27.5:1: 1.
6. The method for preparing the nanofiber modified polyimide aerogel material as claimed in claim 5, wherein the diamine monomer is p-phenylenediamine or 4, 4' -diaminodiphenyl ether; the binary anhydride monomer is any one of pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride or diphenyl ether tetracarboxylic dianhydride; the polar solvent is any one of dimethylacetamide, N-methylpyrrolidone or dimethylformamide; the organic amine is any one of triethylamine or dipropylamine.
7. The method for preparing a nanofiber modified polyimide aerogel material according to claim 1, wherein the polyimide nano short fibers are prepared by the following method: firstly, dissolving a diamine monomer in a polar solvent, then adding a dicarboxylic anhydride monomer, and carrying out polymerization reaction in an ice-water bath to obtain a polyamic acid solution; and (3) performing electrostatic spinning on the prepared polyamic acid solution to prepare a polyamic acid nanofiber membrane, dispersing the polyamic acid nanofiber membrane into short fibers, drying the short fibers, and imidizing the short fibers to obtain the polyimide nano short fibers.
8. The nanofiber modified polyimide aerogel material prepared by the preparation method of the nanofiber modified polyimide aerogel material as claimed in any one of claims 1 to 7.
9. Use of the nanofiber modified polyimide aerogel material of claim 8 in the field of construction, automotive, aerospace, household appliances, chemical, or outdoor sports.
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