Polyimide aerogel microsphere material and preparation method thereof

Abstract

The invention belongs to the field of aerogel microspheres, and discloses a polyimide aerogel microsphere material and a preparation method thereof.The preparation method comprises the steps that diamine is dissolved in a polar solvent and stirred, and a diamine solution is obtained; adding dianhydride into the diamine solution, and stirring in an ice-water bath to obtain a polyamide acid solution; carrying out solvothermal reaction on the polyamide acid solution to obtain an aerogel microsphere suspension; and drying the aerogel microsphere suspension in a vacuum oven to obtain the polyimide aerogel microspheres. According to the preparation method disclosed by the invention, the polyimide aerogel microspheres are prepared through solvothermal reaction by taking dianhydride and diamine as raw materials and taking N, N-dimethylacetamide, N, N-dimethylformamide or N-methyl pyrrolidone as a solvent, so that the limitation that most of polyimide aerogel prepared by a traditional method is a block material is solved, and the application field of an aerogel material is widened.

Description

Technical Field

[0001] The invention belongs to the field of aerogel microspheres, and in particular relates to a polyimide aerogel microsphere material and a preparation method thereof. Background Art

[0002] Polymer aerogel is a porous material prepared by a specific drying method with a polymer as the matrix. Its liquid component is replaced by gas, thus presenting a light, porous and complex structure. Polymer aerogel is widely used in thermal insulation materials, dielectric materials, catalyst carriers and adsorption materials due to its porous structure and rich properties such as high specific surface area, low density, low thermal conductivity and low dielectric constant. However, ordinary polymer aerogel materials have problems such as poor mechanical properties and heat resistance, which greatly limits the scope of their use.

[0003] Polyimide is one of the organic polymer materials with the best comprehensive performance. It can withstand high temperatures of more than 400°C, has a long-term use temperature range of -200-300°C, has no obvious melting point, has a low dielectric constant, excellent corrosion resistance, mechanical properties and chemical stability. It has been widely used in aviation, aerospace, shipbuilding, environmental protection, microelectronics industry, etc. However, polyimide aerogels prepared by traditional methods are mostly block materials, which to some extent limits their application in special environments.

[0004] Therefore, it is necessary to provide a method for preparing polyimide aerogel materials into microspheres to broaden the application fields of aerogel materials. Summary of the invention

[0005] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to propose a method for preparing polyimide aerogel microspheres using polyamic acid as raw material through a solvent thermal process, so as to solve the problem that most of the current polyimide aerogel materials are block structures and are limited in use in narrow space areas.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a polyimide aerogel microsphere material, characterized by comprising:

[0008] Dissolving a diamine in a polar solvent and stirring to obtain a diamine solution;

[0009] Adding dibasic anhydride to the diamine solution and stirring in an ice water bath to obtain a polyamic acid solution;

[0010] The polyamic acid solution is subjected to a solvothermal reaction to obtain an aerogel microsphere suspension;

[0011] The aerogel microsphere suspension is dried in a vacuum oven to obtain polyimide aerogel microspheres;

[0012] Wherein, the molar ratio of dibasic anhydride to diamine is 1.2-1:1.

[0013] Further, the polyamic acid solution is subjected to a solvothermal reaction, comprising:

[0014] The polyamic acid solution was heated to 150°C and kept at this temperature for 30 minutes, then heated to 200°C and kept at this temperature for 30 minutes, and then heated to 250°C and kept at this temperature for 120 minutes, with a heating rate of 2°C / min.

[0015] After the reaction was completed, the cooling rate was 2°C / min.

[0016] Further, the diamine includes at least one of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane and p-phenylenediamine.

[0017] Further, the polar solvent includes any one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.

[0018] Further, the dibasic anhydride includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2,3,3',4'-biphenyltetracarboxylic dianhydride.

[0019] Further, the diamine is dissolved in a polar solvent and stirred, comprising:

[0020] The stirring time is 1-2h, and the stirring rate is 100-150r / min.

[0021] Further, stirring in an ice water bath comprises:

[0022] The stirring time is 1-6h, and the stirring rate is 100-400r / min.

[0023] Furthermore, the mass concentration of the polyamic acid solution is 5%-15%.

[0024] On the other hand, the present invention discloses a polyimide aerogel microsphere material, which is prepared by the above method.

[0025] Technical effects and advantages of the present invention:

[0026] The invention adopts dibasic anhydride and diamine as raw materials and N,N-dimethylacetamide, N,N-dimethylformamide or N-methylpyrrolidone as solvent to prepare polyimide aerogel microspheres through solvent thermal reaction, which solves the limitation that polyimide aerogels prepared by traditional methods are mostly block materials and broadens the application field of aerogel materials.

[0027] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a method for preparing a polyimide aerogel microsphere material of the present invention;

[0029] Figure 2 This is a low-magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in Example 1;

[0030] Figure 3 This is a high-magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in Example 1;

[0031] Figure 4 This is a low-magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in Example 2;

[0032] Figure 5 This is a high-magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in Example 2;

[0033] Figure 6 This is a low-magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in Example 3;

[0034] Figure 7 This is a high-magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in Example 3. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, the present invention provides a method for preparing a polyimide aerogel microsphere material, comprising:

[0037] Dissolving a diamine in a polar solvent and stirring to obtain a diamine solution;

[0038] Adding dibasic anhydride to the diamine solution and stirring in an ice water bath to obtain a polyamic acid solution;

[0039] The polyamic acid solution is subjected to a solvothermal reaction to obtain an aerogel microsphere suspension;

[0040] The aerogel microsphere suspension is dried in a vacuum oven to obtain polyimide aerogel microspheres.

[0041] In some embodiments of the present invention, the polyamic acid solution is subjected to a solvothermal reaction, comprising:

[0042] The polyamic acid solution was heated to 150°C and kept warm for 30 minutes, then heated to 200°C and kept warm for 30 minutes, and then heated to 250°C and kept warm for 120 minutes, with a heating rate of 2°C / min; after the reaction was completed, the cooling rate was 2°C / min.

[0043] For example, pour the polyamic acid solution into a glass bottle, place the glass bottle in the polytetrafluoroethylene inner sleeve of the reactor, pour acetone solvent into the gap between the polytetrafluoroethylene inner sleeve and the glass bottle, seal the reactor, place the reactor in an oven for heating, heat the oven to 150°C and keep it warm for 30 minutes, then heat it to 200°C and keep it warm for 30 minutes, then heat it to 250°C and keep it warm for 120 minutes, the heating rate is 2°C / min, and a solvent thermal reaction is carried out. After the reaction is completed, the cooling rate is 2°C / min and the reactor is cooled to room temperature.

[0044] In some embodiments of the present invention, the diamine includes at least one of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane and p-phenylenediamine.

[0045] In some embodiments of the present invention, the polar solvent includes any one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.

[0046] In some embodiments of the present invention, the dibasic anhydride includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2,3,3',4'-biphenyltetracarboxylic dianhydride.

[0047] In some embodiments of the present invention, dissolving a diamine in a polar solvent and stirring the mixture comprises:

[0048] The stirring time is 1-2h, and the stirring rate is 100-150r / min.

[0049] In some embodiments of the present invention, stirring in an ice water bath comprises:

[0050] The stirring time is 1-6h, and the stirring rate is 100-400r / min.

[0051] In some embodiments of the present invention, the mass concentration of the polyamic acid solution is 5%-15%.

[0052] On the other hand, the present invention discloses a polyimide aerogel microsphere material, which is prepared by the above method. 。

[0053] In order to better illustrate the present solution, the following embodiments are also provided.

[0054] Example 1

[0055] The precursor polyamic acid solution of polyimide was prepared by using 4,4'-diaminodiphenyl ether and pyromellitic anhydride as monomers and N-methylpyrrolidone as solvent in an ice water bath for polymerization reaction.

[0056] S1: First, weigh 2.40 g (0.012 mol) of 4,4'-diaminodiphenyl ether and fully dissolve it in 20 g of N-methylpyrrolidone. The mechanical stirring rate is 100-150 r / min for 1-2 h until the particles are completely dissolved in the solvent to obtain a diamine solution.

[0057] S2: Then slowly add 2.616g (0.012mol) of pyromellitic dianhydride to the diamine solution, and then add 25.144g of N-methylpyrrolidone, and mechanically stir in an ice-water bath for 1-6h at a stirring rate of 100-400r / min until the light yellow polyamic acid solution becomes spherical and has an obvious pole climbing phenomenon, that is, the polyamic acid solution is successfully synthesized.

[0058] S3: Pour 20ml of polyamic acid solution into a 30ml glass bottle and place it in the polytetrafluoroethylene inner sleeve of the reactor. Pour an appropriate amount of acetone solvent into the gap between the inner sleeve and the glass bottle. The liquid level of the acetone solvent should be slightly lower than the bottle mouth of the glass bottle. The reactor is sealed. The reactor is placed in an oven for heating to perform a solvent thermal reaction. The three heating temperatures and insulation times are: 150°C for 30min, 200°C for 30min, and 250°C for 120min. The heating rate is 2°C / min. After the solvent thermal reaction is completed, it is cooled to room temperature at a cooling rate of 2°C / min to obtain a suspension of polyimide aerogel microspheres.

[0059] S4: placing the suspension of aerogel microspheres in an oven for vacuum drying at a drying temperature of 25° C. for a drying time of 1-48 h, removing excess solvent, and obtaining polyimide aerogel microspheres.

[0060] The low magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in this embodiment is as follows: Figure 2 As shown in the high magnification scanning electron microscope image Figure 3 as shown.

[0061] Example 2

[0062] The precursor polyamic acid solution of polyimide was prepared by using 4,4'-diaminodiphenyl ether and pyromellitic anhydride as monomers and N,N-dimethylacetamide as solvent in an ice-water bath for polymerization reaction.

[0063] S1: First, weigh 2.40 g (0.012 mol) of 4,4'-diaminodiphenyl ether and fully dissolve it in 20 g of N,N-dimethylacetamide. The mechanical stirring rate is 100-150 r / min for 1-2 h until the particles are completely dissolved in the solvent to obtain a diamine solution.

[0064] S2: Then slowly add 2.616g (0.012mol) of pyromellitic dianhydride to the diamine solution, and then add 25.144g of N,N-dimethylacetamide, and mechanically stir in an ice water bath for 1-6h at a stirring rate of 100-400r / min to obtain a polyamic acid solution with N,N-dimethylacetamide as solvent.

[0065] The remaining steps are the same as those in Example 1 to prepare polyimide aerogel microspheres.

[0066] The low magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in this embodiment is as follows: Figure 4 As shown in the high magnification scanning electron microscope image Figure 5 shown.

[0067] Example 3

[0068] The precursor polyamic acid solution of polyimide was prepared by using 4,4'-diaminodiphenyl ether and pyromellitic anhydride as monomers and N,N-dimethylformamide as solvent in an ice water bath for polymerization reaction.

[0069] S1: First, weigh 2.40 g (0.012 mol) of 4,4'-diaminodiphenyl ether and fully dissolve it in 20 g of N,N-dimethylformamide. The mechanical stirring rate is 100-150 r / min for 1-2 h until the particles are completely dissolved in the solvent to obtain a diamine solution.

[0070] S2: Then slowly add 2.616g (0.012mol) of pyromellitic dianhydride to the diamine solution, and then add 25.144g of N,N-dimethylacetamide, and mechanically stir in an ice water bath for 1-6h at a stirring rate of 100-400r / min to obtain a polyamic acid solution with N,N-dimethylformamide as solvent.

[0071] The remaining steps are the same as those in Example 1 to prepare polyimide aerogel microspheres.

[0072] The low magnification scanning electron microscope image of the polyimide aerogel microspheres prepared in this embodiment is as follows: Figure 6As shown in the high magnification scanning electron microscope image Figure 7 shown.

[0073] In summary, the present invention uses dibasic anhydride and diamine as raw materials and N,N-dimethylacetamide, N,N-dimethylformamide or N-methylpyrrolidone as solvent to prepare polyimide aerogel microspheres by solvent thermal reaction, which solves the limitation that the polyimide aerogels prepared by traditional methods are mostly bulk materials and broadens the application field of aerogel materials.

[0074] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a polyimide aerogel microsphere material, characterized in that: include: Dissolving a diamine in a polar solvent and stirring to obtain a diamine solution; Adding dibasic anhydride to the diamine solution and stirring in an ice-water bath to obtain a polyamic acid solution; performing a solvothermal reaction on the polyamic acid solution to obtain an aerogel microsphere suspension; Drying the aerogel microsphere suspension in a vacuum oven to obtain polyimide aerogel microspheres; Wherein, the molar ratio of the dibasic anhydride to the diamine is 1.2-1:

1.

2. The method for preparing a polyimide aerogel microsphere material according to claim 1, characterized in that: The step of subjecting the polyamic acid solution to a solvothermal reaction comprises: The polyamic acid solution was heated to 150°C and kept at this temperature for 30 minutes, then heated to 200°C and kept at this temperature for 30 minutes, and then heated to 250°C and kept at this temperature for 120 minutes, with a heating rate of 2°C / min; After the reaction was completed, the cooling rate was 2°C / min.

3. The method for preparing a polyimide aerogel microsphere material according to claim 1, characterized in that: The diamine includes at least one of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane and p-phenylenediamine.

4. The method for preparing a polyimide aerogel microsphere material according to claim 1, characterized in that: The polar solvent includes any one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.

5. The method for preparing a polyimide aerogel microsphere material according to claim 1, characterized in that: The dibasic anhydride includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2,3,3',4'-biphenyltetracarboxylic dianhydride.

6. The method for preparing a polyimide aerogel microsphere material according to claim 1, characterized in that: The step of dissolving the diamine in a polar solvent and stirring the mixture comprises: The stirring time is 1-2h, and the stirring rate is 100-150r / min.

7. The method for preparing a polyimide aerogel microsphere material according to claim 1, characterized in that: The stirring in an ice water bath comprises: The stirring time is 1-6h, and the stirring rate is 100-400r / min.

8. A method for preparing a polyimide aerogel microsphere material according to any one of claims 1 to 7, characterized in that: The mass concentration of the polyamic acid solution is 5%-15%.

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

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