Polyimide / laponite composite aerogel fiber and preparation method and application thereof

Abstract

The application discloses a kind of polyimide / Laponite composite aerogel fibers and preparation method and application thereof, and is used in the field of coating.The preparation method disclosed in the application comprises the following steps: S1, dianhydride compound, diamine compound and amino Laponite are reacted in N-methyl pyrrolidone, and PAAS / Laponite powder is obtained by precipitation and drying;S2, the powder obtained in step S1 is dissolved to form PAAS / Laponite spinning solution of water system, spinning is carried out, and PAAS / Laponite hydrogel fiber is obtained by being placed in coagulation bath;S3, the PAAS / Laponite hydrogel fiber obtained in step S2 is dried and heat treated, and the spinning solution obtained in the application has reversible sol-gel behavior, and the prepared aerogel fiber has abundant pore structure and good mechanical property, and has potential application in the field of light thermal insulation materials.

Description

Technical Field

[0001] This invention relates to the field of aerogel fiber technology, and in particular to a polyimide / Laponite composite aerogel fiber, its preparation method, and its application. Background Technology

[0002] Aerogel fibers are one-dimensional two-phase mixtures consisting of a matrix framework and air. They not only retain the superior properties of high-performance materials but also possess characteristics difficult to acquire in dense fibers, such as low thermal conductivity, sound absorption, and infrared stealth, due to the introduction of a porous structure. In recent years, with the increasing demand for lightweight and flexible functional materials in various fields, high-performance porous fibers have received widespread attention due to their composite characteristics. For example, carbon aerogel fibers, aramid aerogel fibers, and polyimide aerogel fibers have been successively developed and applied in flexible electronic devices, thermal shielding, and oil-water separation, respectively. However, traditional aerogel materials, due to the introduction of crosslinking agents, lack sol-gel reversibility, resulting in a narrow processing window.

[0003] Polyimide aerogel fibers, as a novel type of differentiated high-performance fiber material, have great application potential in high-tech fields such as wave transmission, heat insulation, and radioactive element adsorption. However, compared with two- or three-dimensional PI porous materials such as porous membranes, foams, and aerogels, the development of one-dimensional PI aerogel fibers is more challenging. The sol-gel method is an effective approach for preparing high-performance porous materials, characterized by its simplicity, narrow and adjustable pore size distribution. However, this method currently mainly focuses on preparing two-dimensional films or three-dimensional bulk materials. Its reliance on mold forming makes it difficult to use for preparing one-dimensional fiber materials with high aspect ratios. Furthermore, this method generally employs a strategy of constructing irreversible gel networks through chemical cross-linking, which results in the polymer losing its spinnability after cross-linking, hindering spinning processing.

[0004] Therefore, there is an urgent need to develop an aerogel fiber with reversible sol-gel behavior in the spinning solution, while also possessing good mechanical properties. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a polyimide / Laponite composite aerogel fiber with abundant pore structure and good tensile mechanical properties.

[0006] The present invention also provides polyimide / Laponite composite aerogel fibers obtained by the above preparation method.

[0007] The present invention also provides applications of the above-mentioned polyimide / Laponite composite aerogel fibers.

[0008] A first aspect of the present invention provides a method for preparing polyimide / Laponite composite aerogel fibers, the method comprising the following steps:

[0009] S1. The dianhydride compound, the diamine compound, and the amino-modified Laponite were reacted in N-methylpyrrolidone, and the precipitate was dried to obtain PAAS / Laponite powder;

[0010] S2. Dissolve the powder obtained in step S1 to form an aqueous spinning solution of PAAS / Laponite and spin it. Place it in a coagulation bath to obtain PAAS / Laponite hydrogel fiber.

[0011] S3. The PAAS / Laponite hydrogel fiber obtained in step S2 is dried and heat-treated to obtain the polyimide / Laponite composite aerogel fiber.

[0012] According to the first aspect of the present invention, at least the following beneficial effects are achieved:

[0013] (1) The Laponite used in this invention is a synthetic lithium diatomite. The particle size of Laponite is monodisperse, with a sheet diameter of about 25-30 nm and a thickness of about 1 nm. Laponite can form a transparent dispersion in aqueous solution. Due to the electrostatic repulsion between the nanosheets, Laponite will self-assemble in the aqueous medium to form a cross-linked structure of "house of cards", forming a gel state. By heating, the cross-linked structure can collapse, thus undergoing a transformation from "gel" to "sol" state. Conversely, cooling will cause a transformation from "sol" to "gel" state. This transformation has a temperature reversible response.

[0014] (2) In this invention, Laponite is introduced into polymer molecules through covalent bonds to prepare water-soluble PAAS / Laponite as spinning solution. The thermotropic sol-gel transformation behavior of Laponite nanoparticles in water solvent system is utilized to construct a temperature gradient between the spinning solution and the coagulation bath to obtain hydrogel fibers. Subsequently, composite aerogel fibers are obtained through heat treatment.

[0015] (3) The spinning solution obtained by the preparation method of the present invention has reversible sol-gel behavior, which makes the spinning processing window wide, thus which is beneficial for mass production.

[0016] According to some embodiments of the present invention, in step S1, the dianhydride compound includes at least one of the following compounds:

[0017]

[0018] According to some embodiments of the present invention, in step S1, the diamine compound includes at least one of the following compounds:

[0019]

[0020] According to some embodiments of the present invention, in step S1, the structural formula of the aminated Laponite is as follows:

[0021]

[0022] According to some embodiments of the present invention, in step S1, the amino content in the aminated Laponite is 5-10 mmol / g.

[0023] According to some embodiments of the present invention, in step S1, the molar mass ratio of the amino group of the diamine compound and the amino-modified Laponite to the molar mass ratio of the anhydride in the dianhydride compound is 1:0.99 to 0.99:1.

[0024] According to some embodiments of the present invention, step S1 further includes a step of adding an organic base and stirring the reaction to obtain polyamic acid salt before the precipitation drying treatment.

[0025] According to some embodiments of the present invention, in step S1, the organic base is at least one of triethylamine and triethanolamine.

[0026] According to some embodiments of the present invention, in step S1, the amount of organic base added is 80 to 120% of the molar mass of the anhydride in the dianhydride compound.

[0027] According to some embodiments of the present invention, in step S1, the reaction time is 15 to 20 hours.

[0028] According to some embodiments of the present invention, in step S1, the reaction temperature is 10–20°C. In step S2, the solvent for the PAAS / Laponite powder is water.

[0029] According to some embodiments of the present invention, in step S2, the ratio of the PAAS / Laponite powder to the sum of the mass of the water solvent and PAAS / Laponite is 6 to 10%.

[0030] According to some embodiments of the present invention, in step S2, the coagulation bath is an aqueous solution of zinc acetate.

[0031] According to some embodiments of the present invention, the concentration of the zinc acetate aqueous solution is 1 to 2 g / L.

[0032] According to some embodiments of the present invention, in step S2, the temperature of the coagulation bath is 5 to 10°C.

[0033] According to some embodiments of the present invention, in step S2, the temperature of the PAAS / Laponite spinning solution is 50-60°C.

[0034] According to some embodiments of the present invention, in step S2, the spinning technique is dry-jet wet spinning.

[0035] According to some embodiments of the present invention, in step S2, the specific steps of the spinning process include:

[0036] The PAAS / Laponite spinning solution is sprayed into fiber shape through a nozzle, and the fiber is placed in the coagulation bath during the spraying process.

[0037] According to some embodiments of the present invention, in step S3, the drying temperature is 55-65°C.

[0038] According to some embodiments of the present invention, in step S3, the heat treatment method includes gradient heating treatment.

[0039] According to some embodiments of the present invention, the gradient temperature rise process includes: treatment at 100-120°C for 1-2 hours, treatment at 190-210°C for 1-2 hours, and treatment at 280-295°C for 1-2 hours.

[0040] A second aspect of the present invention provides polyimide / Laponite composite aerogel fibers prepared by the above preparation method, wherein the polyimide / Laponite composite aerogel fibers have a uniform porous structure.

[0041] According to the second aspect of the present invention, at least the following beneficial effects are achieved:

[0042] The polyimide / Laponite composite aerogel fiber described in this invention has a rich pore structure and good mechanical properties, with a porosity of up to 80% and a tensile strength of up to 35 MPa.

[0043] According to some embodiments of the present invention, the porosity of the polyimide / Laponite composite aerogel fiber is 68% to 80%.

[0044] The third aspect of this invention provides the application of the polyimide / Laponite composite aerogel fiber prepared by the above preparation method in the field of lightweight thermal insulation materials.

[0045] According to some embodiments of the present invention, the lightweight thermal insulation material includes porous fabric and thermal insulation material.

[0046] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0047] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0048] Figure 1 This is a schematic diagram of the morphology of the polyimide / Laponite composite aerogel fiber in Example 1 of the present invention;

[0049] Figure 2 This is a schematic diagram of the reversible sol-gel behavior of the polyamic acid salt spinning solution obtained in Example 1 of the present invention;

[0050] (a) Under room temperature conditions; (b) Under conditions where the temperature is raised to 60°C; (c) Under conditions where the temperature is lowered to room temperature;

[0051] Figure 3 This is a schematic diagram of the morphology of the polyimide fiber obtained by conventional process in Comparative Example 2 of the present invention. Detailed Implementation

[0052] The embodiments of the present invention are described in detail below. Throughout the embodiments, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0053] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0054] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the embodiments, and are only for the purpose of facilitating the description of this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0055] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0056] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0057] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present invention.

[0058] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0059] The reagents and equipment used in the embodiments of this invention include:

[0060] Biphenyltetracarboxylic dianhydride (BPDA, CAS: 2420-87-3);

[0061] Hexafluorodianhydride (6FDA, CAS: 1107-00-2);

[0062] 3,3,4,4-Benzophenone tetracarboxylic dianhydride (BTDA, CAS: 2421-28-5);

[0063] 2-(4-Aminophenyl)-5-aminobenzimidazole (m-BIA, CAS: 7621-86-5);

[0064] 2-(4-Aminophenyl)-5-aminobenzoxazole (BOA, CAS: 130-71-8);

[0065] Triethylamine: 121-44-8;

[0066] Performance testing methods:

[0067] Porosity: Tested by density method according to GB / T 17146;

[0068] Tensile strength: The tensile strength was measured using a fiber strength tester (model XQ-1) at a tensile speed of 10 mm / min.

[0069] Example 1

[0070] This embodiment provides a method for preparing polyimide / Laponite composite aerogel fibers, and the specific preparation steps are as follows:

[0071] (1) Using 200 mL of N-methylpyrrolidone as solvent, 20.48 g (0.0696 mol) of biphenyltetracarboxylic dianhydride (BPDA), 12.49 g (0.0557 mol) of 2-(4-aminophenyl)-5-aminobenzimidazole (m-BIA), and 13.92 g (10 mmol / g) of aminated Laponite were added sequentially. The mixture was reacted at 15 °C for 15 h to obtain a high-viscosity polyamic acid solution. Then, 5.63 g of triethylamine was added to the reaction system, and the mixture was stirred for another 6 h to obtain a polyamic acid salt solution. Finally, the solution was slowly poured into acetone to precipitate the polyamic acid salt, which was then dried to obtain the polyamic acid salt for later use.

[0072] (2) The obtained polyamic acid salt was dissolved in deionized water with a solid content of 8%, and defoamed to obtain a polyamic acid salt spinning solution; the obtained spinning solution exhibited thermotropic sol-gel transition behavior, such as Figure 2 As shown, the spinning solution is in a gel state at room temperature, such as Figure 2 (a) It becomes fluid when heated to 60°C, and is in a sol state, such as Figure 2 (b) After cooling, it returns to a gel state, such as Figure 2 (c) Based on the above physical phase change behavior, a wet spinning technique was adopted, with 2 g / L zinc acetate as the coagulation bath and the obtained polyamate as the spinning slurry. The spinning slurry temperature was 60℃ (sol), the coagulation bath temperature was 10℃, the spinning solution was extruded and gelled in a low-temperature coagulation bath, and then dried at 55℃ to obtain polyamate aerogel fibers; the obtained polyamate was treated at 100℃ for 1 h, 190℃ for 2 h, and 290℃ for 2 h to obtain porous polyimide / Laponite composite aerogel fibers.

[0073] In this embodiment, the polyimide / Laponite composite aerogel fiber prepared has a uniform porous structure, such as... Figure 1 As shown, the porosity is 68% and the tensile strength is 30MPa, making it valuable for applications in porous fabrics and other fields.

[0074] Example 2

[0075] This embodiment provides a method for preparing polyimide / Laponite composite aerogel fibers, and the specific preparation steps are as follows:

[0076] (1) Using 180 mL of N-methylpyrrolidone as solvent, 18.22 g (0.041 mol) of hexafluorodianhydride (6FDA), 5.52 g (0.0246 mol) of 2-(4-aminophenyl)-5-aminobenzimidazole (m-BIA), and 20.51 g (8 mmol / g) of aminated Laponite were added sequentially. The mixture was reacted at 20 °C for 20 h to obtain a high-viscosity polyamic acid solution. Then, 7.34 g of triethylamine was added to the reaction system, and the mixture was stirred for another 8 h to obtain a polyamic acid salt solution. Finally, the solution was slowly poured into anhydrous ethanol to precipitate the polyamic acid salt, which was then dried to obtain the polyamic acid salt for later use.

[0077] (2) The obtained polyamate was dissolved in deionized water with a solid content of 6%, and degassed to obtain polyamate spinning solution; wet spinning technology was adopted, with 1.5 g / L zinc acetate as coagulation bath, and the obtained polyamate as spinning slurry. The spinning slurry temperature was 55℃, the coagulation bath temperature was 5℃, the spinning solution was extruded and gelled in a low-temperature coagulation bath, and then dried at 60℃ to obtain polyamate aerogel fiber; the obtained polyamate was treated at 100℃ for 2 h, 190℃ for 1 h, and 285℃ for 1 h to obtain porous polyimide / Laponite composite aerogel fiber.

[0078] The polyimide / Laponite composite aerogel fiber prepared in this embodiment has a uniform porous structure with a porosity of 80% and a tensile strength of 25 MPa, and has application value in fields such as thermal insulation and protection.

[0079] Example 3

[0080] This embodiment provides a method for preparing polyimide / Laponite composite aerogel fibers, and the specific preparation steps are as follows:

[0081] (1) Using 250 mL of N-methylpyrrolidone as solvent, 22.44 g (0.0697 mol) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 10.98 g (0.0448 mol) of 2-(4-aminophenyl)-5-aminobenzoxazole (BOA), and 29.85 g (7 mmol / g) of aminated Laponite were added sequentially. The mixture was reacted at 15 °C for 20 h to obtain a high-viscosity polyamic acid solution. Then, 8.5 g of triethylamine was added to the reaction system, and the mixture was stirred for another 8 h to obtain a polyamic acid salt solution. Finally, the solution was slowly poured into anhydrous ethanol to precipitate the polyamic acid salt, which was then dried to obtain the polyamic acid salt for later use.

[0082] (2) The obtained polyamate was dissolved in deionized water with a solid content of 8%, and degassed to obtain polyamate spinning solution; wet spinning technology was used, with 2 g / L zinc acetate as coagulation bath and the obtained polyamate as spinning slurry. The spinning slurry temperature was 60℃ and the coagulation bath temperature was 10℃. The spinning solution was extruded and gelled in a low-temperature coagulation bath, and then dried at 65℃ to obtain polyamate aerogel fiber; the obtained polyamate was treated at 100℃ for 2 h, 190℃ for 1 h, and 285℃ for 1 h to obtain porous polyimide / Laponite composite aerogel fiber.

[0083] The polyimide / Laponite composite aerogel fiber prepared in this embodiment has a uniform porous structure with a porosity of 75% and a tensile strength of 35 MPa, making it valuable for applications in fields such as thermal insulation and protection.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing polyimide aerogel fibers, which differs from Example 1 in that it does not introduce aminated Laponite.

[0086] In this comparative example, the polymer obtained during the preparation process does not exhibit sol-gel transition behavior. After undergoing the same spinning process, the resulting fibers have a pointer-shaped macroporous and microporous mixed structure, exhibiting the typical morphological characteristics of fibers obtained by traditional wet spinning.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing polyimide aerogel fibers, which differs from Example 1 in that it uses a conventional spinning process.

[0089] The resulting polyimide aerogel fibers have a needle-like porous structure, such as... Figure 3 As shown.

[0090] In summary, the polyamic acid salt spinning solution in the preparation process of the present invention exhibits thermotropic sol-gel transition behavior, and the aerogel fibers prepared by the present invention have abundant pore structure and good mechanical properties, and have the potential for application in the field of lightweight thermal insulation materials.

[0091] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing polyimide / Laponite composite aerogel fibers, characterized in that, The preparation method includes the following steps: S1. A dianhydride compound, a diamine compound, and amino-modified Laponite are reacted in N-methylpyrrolidone, and the precipitate is dried to obtain PAAS / Laponite powder; the structural formula of the amino-modified Laponite is shown below: ； S2. Dissolve the powder obtained in step S1 to form an aqueous spinning solution of PAAS / Laponite and spin it. Place it in a coagulation bath to obtain PAAS / Laponite hydrogel fiber. S3. The PAAS / Laponite hydrogel fiber obtained in step S2 is dried and heat-treated to obtain the polyimide / Laponite composite aerogel fiber.

2. The preparation method according to claim 1, characterized in that, In step S1, the dianhydride compound includes at least one of the following compounds: 、 、 、 、 。 3. The preparation method according to claim 2, characterized in that, In step S1, the diamine compound includes at least one of the following compounds: 、 、 、 。 4. The preparation method according to claim 2, characterized in that, In step S1, the amino content in the amination of Laponite is 5~10 mmol / g.

5. The preparation method according to claim 1, characterized in that, In step S1, the molar mass ratio of the amino group of the diamine compound and the amino-modified Laponite to the molar mass ratio of the anhydride in the dianhydride compound is 1:0.99~0.99:

1.

6. The preparation method according to claim 5, characterized in that, In step S1, before the precipitation drying process, an organic base is added and stirred to react to obtain polyamic acid salt.

7. The preparation method according to claim 6, characterized in that, In step S1, the organic base is at least one of triethylamine and triethanolamine.

8. The preparation method according to claim 6, characterized in that, In step S1, the amount of organic base added is 80-120% of the molar mass of the anhydride in the dianhydride compound.

9. The preparation method according to claim 1, characterized in that, In step S1, the reaction time is 15-20 hours.

10. The preparation method according to claim 9, characterized in that, In step S1, the reaction temperature is 10~20℃.

11. The preparation method according to claim 1, characterized in that, In step S2, the solvent for the PAAS / Laponite powder is water.

12. The preparation method according to claim 11, characterized in that, In step S2, the ratio of the PAAS / Laponite powder to the sum of the mass of the water solvent and PAAS / Laponite is 6 to 10%.

13. The preparation method according to claim 1, characterized in that, In step S2, the coagulation bath is an aqueous solution of zinc acetate.

14. The preparation method according to claim 13, characterized in that, The concentration of the zinc acetate aqueous solution is 1~2 g / L.

15. The preparation method according to claim 13, characterized in that, In step S2, the temperature of the coagulation bath is 5~10℃.

16. The preparation method according to claim 13, characterized in that, In step S2, the temperature of the PAAS / Laponite spinning solution is 50~60℃.

17. The preparation method according to claim 1, characterized in that, In step S2, the spinning technique is dry-jet wet spinning.

18. The preparation method according to claim 17, characterized in that, In step S2, the specific steps of the spinning process include: spraying the PAAS / Laponite spinning solution into fiber shape through a nozzle, and placing the fiber in the coagulation bath during the spraying process.

19. The preparation method according to claim 1, characterized in that, In step S3, the drying temperature is 55~65℃.

20. The preparation method according to claim 19, characterized in that, In step S3, the heat treatment method includes gradient heating.

21. The preparation method according to claim 20, characterized in that, The gradient temperature treatment process includes: treatment at 100~120℃ for 1~2 hours, treatment at 190~210℃ for 1~2 hours, and treatment at 280~295℃ for 1~2 hours.

22. A polyimide / Laponite composite aerogel fiber prepared by the preparation method according to any one of claims 1 to 21, characterized in that, The polyimide / Laponite composite aerogel fiber has a uniform porous structure.

23. The application of polyimide / Laponite composite aerogel fiber prepared by the preparation method according to any one of claims 1 to 21 in the field of lightweight thermal insulation materials.

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