CN106987019B

CN106987019B - Polyimide aerogel crosslinked by surface functionalized nanoparticles and preparation method thereof

Info

Publication number: CN106987019B
Application number: CN201710245175.2A
Authority: CN
Inventors: 王凯; 张天翼; 李永武
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2017-04-14
Filing date: 2017-04-14
Publication date: 2020-05-08
Anticipated expiration: 2037-04-14
Also published as: CN106987019A

Abstract

The invention relates to a polyimide aerogel and a preparation method thereof, in particular to a polyimide aerogel crosslinked by surface functionalized nanoparticles and a preparation method thereof. The preparation method of the aerogel comprises the following steps: functionalizing the surface of the nanoparticle; synthesizing a polyamic acid precursor; preparing a polyimide wet gel using the functionalized nanoparticles as a cross-linking agent; and (3) carrying out supercritical drying to obtain the cross-linked polyimide aerogel. The polyimide aerogel disclosed by the invention has a stable mesoporous structure with narrow distribution, high specific surface area, good heat resistance and stable physicochemical properties, can endow the aerogel with different performance characteristics according to the types of used nanoparticles, comprises better toughness, rigidity, heat insulation, dielectric property, electric conductivity, electromagnetic shielding property and the like, and can be further used as a polymer electrode material, an adsorption catalysis carrier, a porous heat insulation material, an electromagnetic shielding material and the like.

Description

Polyimide aerogel crosslinked by surface functionalized nanoparticles and preparation method thereof

Technical Field

The invention relates to an aerogel and a preparation method thereof, in particular to a polyimide aerogel crosslinked by surface functionalized nanoparticles and a preparation method thereof.

Background

The aerogel is a light porous solid material, has the advantages of large specific surface area, high porosity and the like, and can be used as a heat-insulating material, a catalyst carrier, a hydrogen storage material, an adsorption material and the like to be applied to the fields of energy, aerospace, environmental protection and the like. Conventional silica aerogels have a large brittleness and thus have a limited field of application. Organic aerogels represented by polyimides are regarded by researchers for their excellent mechanical properties and good processability.

Polyimide is a special engineering plastic with good thermal stability and higher mechanical strength, and the polyimide aerogel prepared by condensation polymerization and imidization can be widely used for heat insulation materials, dielectric materials, catalyst carrier materials and the like. When the polyimide aerogel is carbonized at high temperature, carbon aerogel with high conductivity, large specific surface area and three-dimensional network structure can be formed. The obtained carbon aerogel can be applied to super capacitors and electrode materials.

Various polyimide aerogels and methods for their preparation have been disclosed in the prior art. For example, CN 106519228A discloses a polyimide aerogel, which is prepared by amidating diamine and dianhydride to obtain anhydride group-terminated linear polyamic acid, crosslinking with a crosslinking agent, dehydrating with a dehydrating agent, and extracting to obtain an aerogel; the cross-linking agent is 2,2 ', 7,7 ' -tetraamino-9, 9 ' -spirobifluorene. Furthermore, CN 105968354a discloses a method for adsorbing CO₂The preparation method of the polyimide aerogel comprises the steps of preparing polyamide acid solution by taking aromatic tetracarboxylic dianhydride and aromatic polyfunctional diamine as monomers, adding a specific cross-linking agent to form a cross-linking structure, carrying out imidization by a chemical method to obtain wet gel, and finally carrying out CO (carbon monoxide) imidization₂And (3) performing supercritical technology to obtain the polyimide aerogel.

At present, the polyamic acid precursor of most polyimide aerogels has low strength when serving as a polymer skeleton structure of the aerogel, is easy to shrink greatly in the drying process, and has low porosity, small specific surface area and relatively poor mechanical properties. In addition, most of the polyimide aerogel in the prior art is of a microporous structure.

The functional nano particles are substances with nano-scale sizes, have many excellent characteristics due to the chemical composition and structural characteristics, and can be used as a filler to be mixed with a polymer so as to enable the polymer to have specific functionality. In general, nanoparticles have poor dispersibility in polymers and are relatively prone to agglomeration. The prior art discloses methods for preparing aerogels using nanoparticles. In particular, the university of composite denier discloses a series of nanoparticle cross-linked polyimide-based carbon aerogels and methods for their preparation, such as:

CN 104355302a discloses graphene oxide crosslinked polyimide-based carbon aerogel and a preparation method thereof, wherein the carbon aerogel is prepared by using graphene oxide crosslinked polyamic acid aerogel, and comprises the following components: graphene oxide, one or more water-soluble polyimide precursors, polyamic acid; the preparation method comprises the following steps: mixing the graphene oxide aqueous solution with polyamide acid which is a water-soluble precursor of polyimide, and preparing graphene oxide/polyamide acid aerogel by a sol-gel process and freeze drying; preparing the graphene/polyimide-based carbon aerogel through thermal imidization and high-temperature carbonization treatment.

CN 105197909a discloses a graphene nanoribbon/carbon nanotube crosslinked polyimide-based composite carbon aerogel and a preparation method thereof, the method comprising: the preparation method comprises the steps of preparation of a graphene oxide nanoribbon/carbon nanotube hybrid material, synthesis of water-soluble polyamic acid, preparation of a graphene oxide nanoribbon/carbon nanotube/polyamic acid aerogel by a sol-gel method, preparation of a graphene nanoribbon/carbon nanotube/polyimide composite aerogel, activation treatment, high-temperature carbonization and the like. The method of this document utilizes reactive functional groups present on graphene oxide itself to crosslink the polyimide.

CN 105110313A discloses polyimide-based composite carbon aerogel and a preparation method thereof. The polyimide-based composite carbon aerogel comprises the following components: the water-soluble polyimide precursor is polyamic acid, graphene oxide, single-walled or multi-walled carbon nanotube. CN 105110313a uses oxygen-containing groups on graphene oxide or carbon nanotubes or their hybrids, uses graphene oxide or carbon nanotubes or their hybrids as a cross-linking agent of polyamic acid, uses potassium hydroxide as an activator, and under the action of heat, makes the polyamic acid cross-linked and imidized, and then performs high-temperature carbonization and activation to prepare polyimide-based composite carbon aerogel with high specific surface area.

These documents disclose the preparation of carbon aerogels by subjecting polyimide aerogels to high temperature carbonization, and there is no mention of polyimide aerogels and their preparation at all. In terms of the production process, these documents use water-soluble polyamic acid. It is well known in the art that water-soluble polyamic acids are essentially polyamic acids in the form of organic salts, for the purpose of preparing aerogels by means of freeze-drying. The prepared polyimide aerogel has a pore structure which does not belong to a mesoporous level basically, most of the prepared polyimide aerogel is a micron-level macropore, the adsorption capacity is relatively poor, a small amount of mesopores contained in the polyimide aerogel are introduced by graphene, and the polyimide aerogel prepared in the invention has a mesoporous structure with narrow distribution, better adsorption and a uniform microstructure. In addition, these documents mention crosslinking polyamides by using oxygen-containing functional groups such as carboxyl, carbonyl, epoxy, hydroxyl groups, etc. existing on the nanoparticles themselves, but do not effectively modify the surface of the nanoparticles, in terms of the means of using the nanoparticles.

Disclosure of Invention

The present invention has been made to overcome the above-mentioned disadvantages of the prior art and to provide a surface-functionalized nanoparticle crosslinked polyimide aerogel in which the surface-functionalized nanoparticles are used as a crosslinking agent.

Thus, in one aspect of the invention, the invention relates to a surface functionalized nanoparticle crosslinked polyimide aerogel wherein the surface functionalized nanoparticles are used as the crosslinking agent.

The nano particles used include but are not limited to silver nanowires, ZnO whiskers, carbon nanotubes, graphene oxide, nano TiO₂Nano MoS₂Mesoporous SiO₂Nano Fe₃O₄Nano Al₂O₃And nano silver particlesSeed, and the like, and mixtures thereof.

In the context of the present invention, surface-functionalized nanoparticles refer to nanoparticles that have been surface-treated with a surface-functionalizing agent having functional groups that can crosslink a polyimide precursor. The functional group is a functional group that can react with a polyamic acid, which is a precursor of a polyimide, and is selected from, for example, an amino group, a carboxyl group, an ester group, an acid chloride group, an isocyanate group, an epoxy group, an acid anhydride, and a combination thereof.

Generally, nanoparticles have various reactive functional groups on their surface, such as hydroxyl, carboxyl, amino, etc., or the nanoparticles themselves are reactive, such as silver nanoparticles that can react with thiol groups. Thus, to enable the surface functionalizing agent to bind to the nanoparticles, the surface functionalizing agent also has functional groups, such as mercapto groups, alkoxysilyl groups, isocyanate groups, amino groups, and the like, that are capable of reacting with the functional groups on the surface of the nanoparticles or with the nanoparticles themselves.

The inventors have surprisingly found that by surface-functionalization modification of the nanoparticles, the reactivity of the functional groups on the nanoparticles is greatly increased, and the nanoparticles can firmly chemically interact with the polyamic acid molecules, thereby resulting in a smaller shrinkage and higher mechanical properties of the aerogel produced. In addition, the addition of different kinds of nanoparticles can also provide different functionalities to the aerogel, such as electromagnetic shielding property, dielectric property, sound absorption property, and thermal insulation property, depending on the functionality of the added nanoparticles themselves.

In one embodiment of the present invention, surface functionalizing agents used to treat the nanoparticles include, but are not limited to, mercaptoaniline, aminopropyltriethoxysilane, diphenylmethane diisocyanate, 4-diaminodiphenyl ether, aminopropyltrimethylsiloxane, thionyl chloride, p-phenylenediamine, and the like, and mixtures thereof.

Functionalization of the nanoparticles may be achieved by reacting the nanoparticles with a surface functionalizing agent. Specifically, the nanoparticles may be dispersed in a solvent in which the surface-functionalizing agent is dissolved or dispersed, and allowed to react. Such solvents include, but are not limited to, anhydrous ethanol, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, tetrahydrofuran, pyridine, triethylamine, acetone, ethyl acetate, and the like. The reaction temperature is 0-180 ℃, and the preferable temperature is room temperature to 120 ℃; the reaction time is 12-24h, preferably 12-16h, more preferably 16 h. The reaction is carried out under an atmosphere of air or nitrogen. After the reaction, excess surface functionalizing agent is removed by centrifugation, filtration, sonication or dialysis and the like, and the solvent is dried in a vacuum oven to remove the solvent, thereby obtaining a functionalized nanoparticle product.

In one embodiment of the present invention, the polyimide aerogel of the present invention comprises a polyimide matrix crosslinked by surface functionalized nanoparticles and voids. In the aerogels of the present invention, the surface-functionalized nanoparticles comprise from 0.01 to 2% by volume, preferably from 0.01 to 1.5% by volume, more preferably from 0.01 to 1.0% by volume; the polyimide matrix is present in an amount of 5 to 20% by volume, preferably 5 to 10% by volume, more preferably 5 to 8% by volume; the voids constitute from 78 to 95% by volume, preferably from 85 to 95% by volume, more preferably from 90 to 95% by volume; in each case relative to the total volume of the aerogel.

The average pore size of the polyimide aerogel of the present invention is 5 to 40nm, preferably 10 to 30nm, and more preferably 15 to 20 nm.

In another aspect of the present invention, the present invention relates to a method for preparing a surface-functionalized nanoparticle crosslinked polyimide aerogel, which comprises adding surface-functionalized nanoparticles to a polyamic acid precursor and allowing a crosslinking reaction to occur.

The surface-functionalized nanoparticles are as defined above.

In one embodiment of the present invention, the surface-functionalized nanoparticles are dispersed in a solvent and then mixed with the prepared polyamic acid precursor and subjected to a crosslinking reaction. The solvent may be a variety of possible solvents including, but not limited to, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, tetrahydrofuran, pyridine, triethylamine, acetone, ethyl acetate. Preferably, the solvent is the same as the solvent used to prepare the polyamic acid precursor. The mass ratio of the surface-functionalized nanoparticles to the polyamic acid is 0.1:100 to 30:100, preferably 0.5:100 to 25:100, more preferably 1:100 to 20: 100. The reaction is carried out at a temperature of 0-200 ℃, preferably at room temperature; the reaction time is 20-200min, preferably 20-100min, more preferably 20-60 min. The crosslinking reaction is preferably carried out under mechanical stirring.

The polymerization degree of the polyamic acid is 50 or more, preferably 50 to 100. The inventor surprisingly found that by selecting the polyamic acid with higher polymerization degree, the obtained polyimide aerogel has smaller shrinkage, higher strength and toughness, higher specific surface area, uniform pore size distribution and mesopores.

In the present invention, the polyamic acid precursor can be prepared as follows: the monomeric diamine is reacted with a monomeric dicarboxylic anhydride to obtain a polyamic acid. The used diamine is preferably one or more selected from p-phenylenediamine, m-phenylenediamine, 3, 4-diaminodiphenyl ether, 4' -diaminodiphenyl ether, 1, 4-bis [2- (4-aminophenyl) ethyl ] benzene, 2-bis [4- (4-aminophenoxy) phenyl ] propane and dimethyl benzimidazole; the dibasic anhydride is preferably selected from one or more of pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, diphenylether tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, bisphenol a diether dianhydride, bis (trifluoromethyl) methylenediphenyltetracarboxylic dianhydride. The polymerized monomers of the polyamic acid of the present invention may also include other monomers, if possible, such as p-phenylene diisocyanate, 4-amino-3 ', 4' -dicarboxydiphenyl ether, tert-butyl 2, 5-diiodo-terephthalate, and the like.

The reaction for preparing the polyamic acid precursor may be performed in a solvent including, for example, one or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, tetrahydrofuran, pyridine, triethylamine, acetone, and ethyl acetate. Depending on the reactive functional group on the surface functionalizing agent, the resulting polyamic acid precursor can be anhydride terminated or amine terminated such that the reactive functional group on the surface functionalizing agent can react with the polyamic acid precursor, thereby crosslinking it. For example, anhydride-terminated polyamic acid precursors can be used when the reactive functional groups on the surface-functionalized nanoparticles are alkylamino, phenylamino, isocyanate, and the like; when the reactive functional group on the surface functionalized nanoparticles is a carboxyl group, an acid chloride group, an isocyanate group, an anhydride, or the like, an amine-terminated polyamic acid precursor can be used. In the case of anhydride-terminated polyamic acid precursors, the molar ratio of diamine to diacid anhydride is 1 (1-1.02), more preferably 1 (1.001-1.02), and most preferably 1 (1.01-1.02). In the case of amine-terminated polyamic acid precursors, the molar ratio of the diacid anhydride to diamine is 1 (1-1.02), more preferably 1 (1.001-1.02), and most preferably 1 (1.01-1.02). The reaction for preparing the polyamic acid precursor is carried out at a temperature of 0 to 100 deg.C, preferably at a temperature of 0 to 50 deg.C, more preferably at room temperature.

Different from the water-soluble polyamic acid precursor used in the prior art, the polyamic acid precursor used in the invention is in a nonaqueous polar solvent system, is simpler and more convenient to synthesize than the former, and does not need a salt forming step; and the water-soluble polyamic acid precursor can only be used for preparing aerogel by a freeze-drying method, and the aerogel with a mesoporous structure cannot be obtained. In the present invention, after the wet gel is formed, the aerogel is obtained by supercritical drying instead of freeze drying. The aerogel obtained by drying the wet gel has a nano-scale mesoporous structure, while the wet gel in the prior art can only obtain a micro-scale macroporous structure, and the aerogel has a larger specific surface area and a finer porous structure.

The method further includes chemically imidizing the polyamic acid precursor after the crosslinking reaction. Chemical imidization can be carried out by conventional methods known to those skilled in the art, for example by adding triethylamine and acetic anhydride. The chemical imidization is carried out at a temperature of 0-200 ℃, preferably at room temperature; the reaction time is 1-200min, preferably 2-100min, more preferably 5-30 min. The imidization reaction is preferably carried out under mechanical stirring.

After imidization, a crosslinked polyimide wet gel was obtained. And performing supercritical drying on the obtained crosslinked polyimide wet gel to obtain the polyimide aerogel. In a preferred embodiment, the crosslinked polyimide wet gel is solvent-replaced with ethanol prior to supercritical drying, in order to replace the solvent in the wet gel with ethanol that is more easily replaced during supercritical drying, does not corrode supercritical equipment, and is relatively less toxic to humans. And after solvent replacement, placing the gel in a drying kettle, performing supercritical drying under 8-12MPa, and drying for several hours to obtain the polyimide aerogel.

In a preferred embodiment of the present invention, the aerogel preparation method of the present invention comprises: functionalizing the surface of the nanoparticle; synthesizing a polyamic acid precursor; preparing a polyimide wet gel using the functionalized nanoparticles as a cross-linking agent; and (3) carrying out supercritical drying to obtain the cross-linked polyimide aerogel.

Specifically, the method of the present invention comprises the steps of:

(1) reacting the nanoparticles with a surface functionalizing agent to produce surface functionalized nanoparticles;

(2) adding the surface functionalized nano-particles into the polyamic acid precursor and carrying out a crosslinking reaction on the polyamic acid precursor;

(3) chemically imidizing a polyamic acid precursor to obtain a crosslinked polyimide wet gel;

(4) and (3) performing supercritical drying on the crosslinked polyimide wet gel to obtain the polyimide aerogel.

The polyimide aerogel disclosed by the invention has a stable mesoporous structure with narrow distribution, high specific surface area, good heat resistance and stable physicochemical properties, and different performance advantages including better toughness, rigidity, heat insulation, dielectric property, electric conductivity, electromagnetic shielding property and the like can be generated according to different types of used functional nanoparticles. Therefore, the polyimide aerogel of the invention is particularly suitable for polymer electrode materials, adsorption catalysis carriers, porous heat insulation materials and electromagnetic shielding materials.

In the context of the present invention, "mesoporous" refers to a pore structure with a pore diameter between 2 and 50nm according to the definition of the International Union of Pure and Applied Chemistry (IUPAC).

In another aspect of the present invention, the present invention relates to the use of the polyimide aerogel of the present invention in a polymer electrode material, an adsorption catalyst support, a porous heat insulating material, an electromagnetic shielding material.

Drawings

FIG. 1 is a photograph of a sample of aerogel of example 1;

FIG. 2 is a SEM photograph of a sample of example 1.

Examples

The invention is illustrated in more detail below by way of examples and figures, wherein the starting materials are commercially available and, unless otherwise specified, are of chemically pure or analytically pure grade.

Example 1

Preparing the polyimide aerogel crosslinked by the aminated silver nanowires: dispersing silver nanowires in an absolute ethyl alcohol solvent, adding p-mercaptoaniline with the molar ratio of 4:1 to silver in the silver nanowires, performing amination modification in the absolute ethyl alcohol solvent for 6 hours, centrifuging, washing with absolute ethyl alcohol for 5 times, and drying for later use; dissolving 15mmol of diamine monomer 4, 4-diaminodiphenyl ether in solvent N, N-dimethylacetamide, slowly adding 15.3mmol of

dianhydride monomer

3,3 ', 4, 4' -biphenyl tetracarboxylic dianhydride, reacting at room temperature for 4h after full dissolution to obtain anhydride terminated polyamic acid with polymerization degree of about 50, and adjusting solid content to 12% by changing the mass of the solvent. Adding a certain amount of modified silver nanowires into the polyamic acid solution. Crosslinking was carried out at room temperature for 40min under mechanical stirring. And triethylamine and acetic anhydride are added in a molar ratio of 1:1, and the molar weight of the triethylamine and the acetic anhydride is twice that of the polyamic acid. And carrying out chemical imidization at room temperature, mechanically stirring for 5min, quickly pouring into a mold, and standing at room temperature for 24h to prepare the polyimide wet gel with certain strength. And then carrying out solvent exchange in ethanol for 3 days, completely replacing the solvent in the wet gel with ethanol, maintaining the pressure in a carbon dioxide drying kettle at 10MPa for 4h, and then carrying out supercritical drying at 14MPa and 25 ℃ for 8h to obtain the polyimide aerogel. A photograph of the aerogel sample prepared is shown in fig. 1.

The resulting aerogels were tested for properties, wherein density was determined according to ASTM D792-2007; the shrinkage is obtained by measuring the dimensions of the sample before and after drying; the specific surface area is determined by combining a BET multipoint method according to a nitrogen adsorption and desorption test result; the average pore size is obtained by combining the BJH equation determination according to the nitrogen adsorption and desorption test result; 10% compressive strength and compressive modulus were determined according to ASTM D1621-2004a, and tensile elongation at break was determined according to ASTM D6382003; thermal conductivity was measured according to ASTM C518.

The results are summarized in table 1.

Table 1 properties of aerogels of different silver nanocontent in example 1

Wherein the mass fraction of silver nanowires is relative to the polyamic acid precursor.

As can be seen from table 1 above, the 10% compressive strength and compressive modulus are greatly improved with the addition of the silver wire, and the thermal conductivity is also kept below 0.050m · K.

Example 2

Preparation of functionalized mesoporous silica crosslinked polyimide aerogel: mesoporous silica microspheres are prepared by a template method, under the condition of rapid magnetic stirring, 2.31ml of dodecylamine and 0.1822g of hexadecyl trimethyl ammonium bromide are added into a mixed solution of ethanol, isopropanol, deionized water and a small amount of ammonia water (ethanol: 131.01ml, ammonia water: 0.11ml, isopropanol 47.74ml and deionized water 67.5ml), and then tetraethoxysilane is rapidly added, and the stirring is kept slowly. And after the addition is finished for 10 hours, centrifuging and ultrasonically dispersing the reaction liquid, washing with deionized water, repeating for 5 times to obtain silicon dioxide microsphere wet powder, and freeze-drying the powder for 3 hours. And finally, roasting the dried powder in a high-temperature furnace at 700K for 10 hours to obtain the mesoporous silica microspheres. Then refluxing the microspheres and aminopropyltriethoxysilane in a toluene solvent environment at 110 ℃ for 5h to perform amination grafting modification. And centrifuging the obtained product, and washing the product for 3 times by using absolute ethyl alcohol to obtain the amino functionalized mesoporous silicon dioxide. 10mmol of diamine monomer 4, 4-diamino-diDissolving phenylate in N, N-dimethylacetamide, slowly adding 10.1

mmol dianhydride monomer

3,3 ', 4, 4' -biphenyl tetracarboxyl dianhydride, reacting at room temperature for 4h after fully dissolving to obtain anhydride terminated polyamic acid with polymerization degree of about 100, and adjusting solid content to 8% by changing the mass of the solvent. The amino-functionalized mesoporous silica was added to the polyamic acid solution in a mass fraction of 10% based on the polyamic acid precursor, and the crosslinking reaction, the gelling reaction, and the chemical imidization reaction were performed according to the procedure of example 1, and finally, the polyimide aerogel was obtained by supercritical drying. The specific surface area of the obtained product aerogel reaches 300m²The pore diameter is about 10 nm. The compression modulus is improved by 20 percent compared with the sample without the mesoporous silica, and the thermal conductivity is reduced by 10 percent.

Example 3

Preparation of isocyanate group modified graphene oxide crosslinked polyimide aerogel: ultrasonically dispersing graphene oxide in N-methyl pyrrolidone, and adding diphenylmethane diisocyanate according to the mass ratio of the graphene oxide to the graphene oxide of 6: 1. And (3) reacting for 24 hours at 40 ℃ in a nitrogen atmosphere, replacing hydroxyl and carboxyl on the graphene oxide with isocyanate groups, and purifying by centrifuging, washing and dialyzing to obtain the isocyanate group modified graphene oxide. The isocyanate group-modified graphene oxide was added to the same polyamic acid solution as in example 1 in a mass fraction of 5% based on the polyamic acid precursor according to the same procedure as in example 1, and subjected to a crosslinking reaction, a gelling reaction, and a chemical imidization reaction according to the procedure in example 1, and finally, a polyimide aerogel was obtained by supercritical drying. The compression modulus of the obtained product aerogel is improved by 40% compared with that of a sample without the graphene oxide, and the thermal conductivity is reduced by 25%.

Example 4

Preparing the surface functionalized nano zinc oxide whisker cross-linked polyimide aerogel: adding a silane coupling agent gamma-aminopropyltriethoxysilane into a water-ethanol solution with the pH of 3 and the volume ratio of 1:1, carrying out hydrolysis reaction for 30min, then adding nano zinc oxide whiskers with the mass ratio of 20:1 to the coupling agent, carrying out mechanical stirring reaction for 60min at a constant temperature under the condition of a water bath at 60 ℃, then carrying out reduced pressure filtration and deionized water washing for 5 times until the supernatant liquid after centrifugation is free of chloride ions, drying in an oven at 80 ℃, turning over for 4h, and finally activating for 5h at 150 ℃ to obtain functionalized zinc oxide whiskers. According to the same procedure as example 1, silane coupling agent modified nano zinc oxide whiskers were added to the same polyamic acid solution as example 2 at a mass fraction of 20% based on the polyamic acid precursor, and the crosslinking reaction, gelation, and chemical imidization were performed according to the procedure of example 1, and finally, a polyimide aerogel was obtained by supercritical drying. Compared with a sample without the nano zinc oxide whiskers, the compression strength of the obtained aerogel is improved by 45%, the volume resistivity of the obtained aerogel is reduced from 1052 ohm cm to 207 ohm cm of the base material, and the obtained aerogel can be used as an antistatic material.

Claims

1. A surface functionalized nanoparticle crosslinked polyimide aerogel, wherein the surface functionalized nanoparticles are used as a crosslinking agent, wherein the polymerization degree of a polyamic acid precursor used for preparing polyimide is 50-100, and wherein the functional group used in the functionalization is a functional group capable of crosslinking the polyamic acid precursor.

2. The aerogel of claim 1, wherein the surface-functionalized nanoparticles are obtained by surface-treating nanoparticles with a surface-functionalizing agent having functional groups capable of crosslinking a polyamic acid precursor.

3. The aerogel of claim 2, wherein the functional groups are selected from the group consisting of amino groups, carboxyl groups, isocyanate groups, acid chloride groups, epoxy groups, ester groups, anhydrides, and combinations thereof.

4. The aerogel of claim 1, wherein the nanoparticles are selected from the group consisting of silver nanowires, ZnO whiskers, carbon nanotubes, graphene oxide, nano-TiO₂Nano MoS₂Mesoporous SiO₂Nano Fe₃O₄Nano Al₂O₃And nano silver particlesAnd mixtures thereof.

5. The aerogel of claim 2, wherein the nanoparticles are selected from the group consisting of silver nanowires, ZnO whiskers, carbon nanotubes, graphene oxide, nano-TiO₂Nano MoS₂Mesoporous SiO₂Nano Fe₃O₄Nano Al₂O₃And nano silver particles, and mixtures thereof.

6. The aerogel of claim 3, wherein the nanoparticles are selected from the group consisting of silver nanowires, ZnO whiskers, carbon nanotubes, graphene oxide, nano TiO₂Nano MoS₂Mesoporous SiO₂Nano Fe₃O₄Nano Al₂O₃And nano silver particles, and mixtures thereof.

7. A method of making an aerogel according to any of claims 1-6, comprising the step of adding surface-functionalized nanoparticles to a polyamic acid precursor and allowing a crosslinking reaction to occur.

8. The method of claim 7, wherein the surface-functionalized nanoparticles are dispersed in a solvent and subsequently mixed with the prepared polyamic acid precursor and subjected to a crosslinking reaction.

9. The method of claim 7, wherein the mass ratio of the surface functionalized nanoparticles to the polyamic acid precursor is from 0.1:100 to 30: 100.

10. The method of claim 9, wherein the mass ratio of the surface functionalized nanoparticles to the polyamic acid precursor is from 0.5:100 to 25: 100.

11. The method of claim 9, wherein the mass ratio of the surface functionalized nanoparticles to the polyamic acid precursor is from 1:100 to 20: 100.

12. The method of any one of claims 7 to 11, wherein the polymerization degree of the polyamic acid precursor is 50 to 100.

13. The method of any one of claims 7-11, wherein the method further comprises, after the crosslinking reaction, chemically imidizing the polyamic acid precursor to yield a crosslinked polyimide wet gel; and performing supercritical drying on the obtained crosslinked polyimide wet gel to obtain the polyimide aerogel.

14. Use of the aerogel of any of claims 1-6 in a polymeric electrode material, an adsorptive catalytic support, a porous thermal insulation material, or an electromagnetic shielding material.