Preparation method and application of aerogel fibers

Abstract

This application discloses a method and application of aerogel fiber. The method includes mixing a solvent and a polymer material to form a spinning solution, using airflow spinning technology to drive the spinning solution with a high-speed airflow to form a jet, and forming a gel fiber through sol-gel conversion, and then performing solvent replacement on the gel fiber and drying to prepare aerogel fiber. The method of preparing aerogel fiber by airflow spinning provided by this application does not have high requirements for the gelation process of aerogel material, and if a spinning solution that meets the rheological conditions is obtained, aerogel fiber can be prepared by this method, avoiding the impact of insufficient gelation process on fiber performance, and at the same time improving the production efficiency of aerogel fiber and greatly simplifying the process. The prepared aerogel fiber has a unique porous structure, high specific surface area, high porosity, certain spinnability and excellent skeletal structure stability, and can be applied in fields such as spinning.

Description

[Technical field]

[0001] (Related Applications) This application claims priority to a Chinese patent application with application number 202310054875.9, filed on February 3, 2023, and title "Preparation method and use of aerogel fiber."

[0002] (Technical field) The present application relates to an aerogel material, in particular to a preparation method and application of a novel aerogel fiber, which belongs to the technical field of nanoporous materials and functional fibers. [Background technology]

[0003] With the development and progress of human culture and science and technology, textile materials are important materials in human production and life. The emergence of synthetic fibers has changed the way of life of human beings for thousands of years, when only natural textile materials such as cotton, hemp, wool, and silk were used, liberated productivity, greatly improved the quality of human life, and is an important achievement in the development of science and technology of human beings. After about 180 years of vigorous development, synthetic fibers have gone through the initial stage of rapid expansion and have begun to pursue a sophisticated development stage with high quality, high performance, and cost-effectiveness. The focus of synthetic fiber development has also shifted from the exploration of new fiber materials to the exploration of new fiber structures, and representative examples of new structure fibers include profile fibers, ultra-fine fibers, and multi-layered functional fibers.

[0004] Aerogel materials are new porous materials with three-dimensional nano-mesh structures, and have structural features such as high porosity, high specific surface area, and ultra-low density. Due to their unique structure, they have unique properties such as low thermal conductivity, low dielectric constant, low refractive index, and high acoustic impedance. Since the preparation of aerogel in 1931, aerogel materials have shown great application potential in fields such as thermal insulation, aerospace, energy storage and thermal management, adsorption and catalysis, and sound insulation. The introduction of the nano-porous network structure of aerogel materials into fiber materials should greatly improve the thermal insulation performance of fibers, and bring new properties and application directions to fiber materials. However, due to the poor mechanical properties of aerogel materials, there have been few reports of their commercial applications in the form of aerogel powders, blocks, aerogel composites, and small aerogel films, as well as the preparation and application of aerogel fibers. The inventors of the present application invented a technology for preparing polyamide aerogel fibers by wet spinning and obtained approval (Patent Document 1), but found that in practical use, due to the complex mesoporous structure inside the aerogel fibers, the structure and performance are often impaired by the complex processing techniques such as spinning and weaving required to prepare the aerogel fibers as textiles. Therefore, the inventors of the present application sought an aerogel fiber preparation technology that would allow the aerogel fibers to be directly applied as products, bypassing the complex processing, so as to maximize the retention of the structure and properties of the aerogel fibers.

[0005] Blow spinning is a new nonwoven fabric technology. The previously reported blow spinning method specifically refers to a method in which a high-speed airflow acts on the spinning solution to form a polymer jet, simultaneously volatilizing the solvent in the spinning solution, and finally forming a continuous fiber in a collection device. The resulting fiber form is flock or nonwoven fabric, which can be directly applied as a functional material. Usually, the blow spinning device combines a high-pressure gas source for supplying gas and a syringe pump for pumping the polymer solution to form a stable jet injection device. Blow spinning has unique advantages in the preparation of nanofibers, including a simple preparation device, a safe preparation process, and a high preparation speed, which is more than 10 times faster than conventional electrostatic spinning (Non-Patent Document 1), and has good large-scale production potential. The resulting product is in the form of a flock, nonwoven fabric, etc., and can be directly applied as a product without destructive processing, which is exactly what is lacking in existing aerogel fiber preparation technologies. However, existing airflow spinning technology often uses low-boiling point solvents, and the action of the airflow causes a large amount of solvent to evaporate in the spinning solution, causing polymers to precipitate in the spinning solution and form fibers (Non-Patent Documents 2 and 3). The fibers prepared by this method currently reported are dense, non-porous precipitated fibers, and in the aerogel fiber preparation process, it is necessary to avoid the generation of precipitates as much as possible in order to form homogeneous and stable gel fibers, so the airflow spinning technology cannot be directly applied to the preparation of aerogel fibers.

[0006] There are no reports on the preparation of aerogel fibers by airflow spinning technology in existing technical reports, and in order to put aerogel fibers into practical use, development is required to solve a series of problems related to their molding, processing, etc., and from this perspective, the present application is filed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] China Patent Application Publication No. 110468461 [Non-patent literature]

[0008] [Non-Patent Document 1] Nano Lett, 2021, 21(12): 5116-5125 [Non-Patent Document 2] Reviews of Modern Physics, 2020, 92(3):035004 [Non-Patent Document 3] ACS Applied Materials & Interfaces, 2016, 8(51): 34951-34963 Summary of the Invention [Problem to be solved by the invention]

[0009] The main objective of the present application is to provide an aerogel fiber and a method for preparing the same to overcome the deficiencies of the prior art.

[0010] Another object of the present application is to provide uses of said aerogel fibers. [Means for solving the problem]

[0011] To achieve the above object of the invention, the technical solutions adopted in this application include:

[0012] An embodiment of the present application provides a method for preparing an aerogel fiber, the method comprising: mixing a solvent and a polymeric material to form a spinning dope; Adopting airflow spinning technology, the spinning solution is driven by high-speed airflow to form a jet, and gel fibers are formed through sol-gel transformation; and performing a solvent substitution on the gel fiber and then drying the same to prepare an aerogel fiber.

[0013] The embodiments of the present application provide aerogel fibers prepared by the above preparation method.

[0014] Furthermore, the aerogel fiber is a porous material, with a porosity of 60% to 99% and a specific surface area of ​​10 to 2000 m 2 / g, the diameter of the aerogel fibers is 100 μm or less, and the aspect ratio of the aerogel fibers is greater than 100.

[0015] The embodiments of the present application provide applications of the aerogel fibers in high-tech industrial fields such as spinning, chemical industry, environment or energy. Effect of the Invention

[0016] Compared with the prior art, the present application has the following advantages:

[0017] 1) Unlike the strict gel control of the conventional methods, the method of preparing aerogel fibers by air spinning provided by the present application does not have high requirements for the gelation process of the aerogel material, and a spinning solution that meets the rheological conditions can be obtained, and aerogel fibers can be prepared by this method, avoiding the impact of insufficient gelation process on fiber performance. The prepared aerogel fibers have a unique three-dimensional porous network structure, extremely low thermal conductivity, high specific surface area, high porosity, certain spinnability and excellent stability of skeletal structure, and can be applied in fields such as spinning.

[0018] 2) The method of preparing aerogel fibers by air spinning provided by the present application overcomes the impact of the existing technology on aerogel fiber performance, which requires destructive post-processing, while improving the production efficiency of aerogel fibers, and generally greatly simplifies the process, which has great potential for industrial application. [Brief description of the drawings]

[0019] In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the following briefly describes the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these accompanying drawings without creative labor.

[0020] [Figure 1] 1 is an optical microscope photograph of the aerogel fiber obtained in Example 1 of the present application. [Diagram 2] FIG. 1 is an actual diagram of the aerogel fiber obtained in Example 1 of the present application. [Diagram 3] FIG. 2 is a nitrogen adsorption / desorption curve diagram of the aerogel fiber obtained in Example 1 of the present application. [Figure 4] 1 is a SEM photograph of the aerogel fiber obtained in Example 2 of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In view of the deficiencies of the prior art, the inventors of the present application, after long-term research and many practices, put forward the technical solution of the present application, mainly providing a method for preparing aerogel fibers by novel airflow spinning.

[0022] The inventors of the present application found that the existing aerogel fiber preparation technology requires post-processing such as spinning and knitting of aerogel fiber filaments, and in view of the complex mesoporous structure inside the aerogel fiber, the textile products prepared by the complex spinning and knitting processing technology for aerogel fiber tend to be damaged in structure and performance. Therefore, the present application improves the airflow spinning technology, and while retaining the technical feature of jet formation by airflow draft, combines the sol-gel conversion process, so that airflow spinning can obtain stable and uniform gel fiber, and further aerogel fiber can be obtained by drying technology. The aerogel products obtained by this technology can be directly applied in the form of nonwoven fabric, flock, etc., without damaging the structure of the aerogel fiber during processing.

[0023] The following further explains and explains this technical solution, its implementation process and principle, etc.

[0024] One aspect of the present application provides a method for preparing an aerogel fiber, the method comprising: mixing a solvent and a polymeric material to form a spinning dope; Adopting airflow spinning technology, the spinning solution is driven by high-speed airflow to form a jet, and gel fibers are formed through sol-gel transformation; and performing a solvent substitution on the gel fiber and then drying the same to prepare an aerogel fiber.

[0025] In some specific embodiments, the method for preparing aerogel fibers mainly comprises three steps: 1) Air-spinning step: A sol (i.e., spinning solution) with certain rheological properties is prepared, and the spinning solution is driven by a high-velocity air stream to form a stable jet (also called a "sol fiber"). 2) Dynamic sol-gel conversion step: converting the moving sol jet into gel to form gel fibers. 3) Special drying step: Apply special drying technology to the gel fibers after solvent replacement to convert the gel fibers into aerogel fibers with as little or no shrinkage as possible.

[0026] In some embodiments, the spinning solution comprises a sol state, a semi-gel state, or a high viscosity solution.

[0027] Furthermore, the viscosity range of the spinning solution is 80 to 4000 cp, and the concentration is 0.1 to 30 wt %.

[0028] In some embodiments, the main components of the spinning solution include an organic solvent and a polymeric material, where the solvent includes, but is not limited to, any one or more of non-volatile DMF, DMSO, NMP, water, etc., and substances with similar properties. The present application provides that the use of a non-volatile solvent ensures that the resulting fiber is a gel fiber and that the gel fiber does not shrink, as compared to other volatile solvents.

[0029] Furthermore, the polymeric material may be a natural polymer and / or a synthetic polymeric material, preferably, any one or a combination of two or more of polymers such as polyamide (e.g., terephthaloyl-p-phenylenediamine), polyester (e.g., poly(methyl methacrylate), poly(dimethyl terephthalate)), cellulose (e.g., hydroxycellulose), polyolefin polymeric material (e.g., poly(vinyl alcohol)), polysiloxane, etc., may be used, but is not limited to these.

[0030] In some embodiments, the air spinning technique refers to a method in which a high velocity air stream is used to act on the spinning solution to form a polymer jet, which is then either formed into a continuous gel fiber in flight or a continuous semi-gel fiber on a collection device, which is then formed into a gel fiber.

[0031] In some embodiments, the airflow spinning technique in the preparation method specifically adopts a spinneret as a spinning solution outlet, the number of spinning holes of which is 1-500, and the diameter of the spinning holes is 0.07-3 mm. In the airflow spinning technique, an airflow passage is opened around the spinning holes, and the airflow sufficiently drafts the spinning solution (i.e., the spinning sol) to form a jet.

[0032] Here, the airflow is dry air or a mixed airflow of dry air and water vapor (i.e., gel factor), the air pressure is 0.1-5 MPa, the water vapor used includes any one or a combination of two or more of water vapor, alcohol vapor, hydrochloric acid, ammonia gas, acetone vapor, etc., or other organic solvent water vapor, and the volume ratio of water vapor in the mixed airflow is 0-60%.

[0033] In some embodiments, the preparation method specifically includes autonomously converting the jet into a sol-gel during flight, or contacting the spinning solution (i.e., the spinning sol) with water vapor as a gel factor dispersed in the jet flight space to cause a sol-gel conversion, or converting the spinning solution jet into a gel fiber by one of impregnation, irradiation, heating, etc. after the spinning solution jet arrives at a receiving device.

[0034] Moreover, the soaking time is generally 3 hours or less until a complete gel is formed. The irradiation is performed using ultraviolet light, has no power requirement, and the irradiation time is 3 hours or less until a complete gel is formed. The heating temperature is 80° C. or more, and the temperature is maintained for 3 hours or less.

[0035] In some embodiments, the solvent used in the solvent replacement includes any one or a combination of two or more of water, tertiary butanol, ethanol, acetone, hexane, etc., and the number of solvent replacements is 3 to 8 times.

[0036] Specifically, if the subsequent drying process employs vacuum freeze drying, the solvent replacement may be performed using water, tertiary butanol, or a mixture of water and tertiary butanol (e.g., a 25% aqueous solution of tertiary butanol); if the subsequent drying process employs supercritical drying, the solvent replacement may be performed using ethanol, acetone, or a combination of ethanol and acetone; if the subsequent drying process employs atmospheric drying, the solvent replacement may be performed using hexane.

[0037] In some embodiments, the drying process may employ any one or a combination of two or more of supercritical drying techniques, vacuum freeze drying techniques, atmospheric drying techniques, and the like.

[0038] Furthermore, the supercritical drying includes replacing the organic solvent inside the gel fiber with a supercritical fluid under supercritical conditions to obtain the aerogel fiber, where the supercritical fluid includes, but is not limited to, any one or a combination of two or more of supercritical CO2, supercritical methanol, and supercritical ethanol.

[0039] Furthermore, the vacuum freeze drying involves subjecting the gel fibers to a freeze crystallization treatment at a low temperature (-10°C to -20°C) for 8 to 24 hours, followed by a sublimation treatment under conditions of a cold trap temperature of -80 to -45°C and a vacuum degree of less than 0.1 kPa to obtain aerogel fibers.

[0040] Furthermore, the atmospheric drying includes directly removing the organic solvent in the gel fibers under an atmospheric pressure environment to obtain aerogel fibers.

[0041] In summary, the method of preparing aerogel fibers by air spinning provided by this application is a universal method, which is different from the strict gel control of the conventional methods, does not have high requirements for the gelation process of the aerogel material, and can obtain a spinning solution that meets the rheological conditions, and can prepare aerogel fibers by this method, avoiding the impact on fiber performance caused by insufficient gelation process. At the same time, this method solves the impact on aerogel fiber performance of the prior art that requires destructive post-processing, improves the production efficiency of aerogel fibers, and generally simplifies the process greatly, and has great industrial applicability.

[0042] Another aspect of the present application further provides an aerogel fiber prepared by the above preparation method.

[0043] In some embodiments, the aerogel fibers are primarily made of natural or synthetic polymeric materials, preferably including, but not limited to, any one or a combination of two or more of polyamide, cellulose, polyether, polyolefin polymeric materials, graphene, carbon nanotubes, silicon dioxide, and the like.

[0044] Furthermore, the aerogel fibers are distributed macroscopically in the form of a network or aggregates, and the aerogel fibers are porous materials, and the network is composed of microporous pores with a pore size of 2 nm or less, mesoporous pores with a pore size of 2 to 50 nm, and macroporous pores with a pore size of 50 nm or more.

[0045] Furthermore, the aerogel fiber has a porosity of 60% to 99% and a specific surface area of ​​10 to 2000 m 2 / g, the diameter of the aerogel fibers is 100 μm or less, and the aspect ratio of the aerogel fibers is greater than 100.

[0046] Compared with the wet spinning preparation, the aerogel fiber obtained in this application has the advantages of improved preparation efficiency, obvious reduction in fiber diameter, and the fiber is softer, the hand feeling is optimized, and it can be better applied in the spinning field.

[0047] As described above, the aerogel fiber is a porous fiber and has characteristics such as a high specific surface area, high porosity, extremely low thermal conductivity, certain spinnability, and excellent skeletal structure stability, and can be used in fields such as spinning.

[0048] Another aspect of the embodiment of the present application further provides applications of the aerogel fibers, which can be applied in high-tech industrial fields such as textiles, chemical industry, environment or energy.

[0049] The technical solution of the present application will be described in more detail below through some embodiments in conjunction with the accompanying drawings. However, the selected embodiments are only used for the purpose of interpreting the technical solution of the present application, and do not limit the scope of the present application. Therefore, the details of the specific functions disclosed in this specification should not be interpreted as limiting, but only as a basis for the claims and as a representative basis for teaching those skilled in the art to actually adopt the present invention in any appropriately detailed embodiment.

[0050] [Example 1] (1) Terephthaloyl-p-phenylenediamine was dissolved in DMSO, and the concentration was adjusted to have a viscosity of 1000 cp to prepare a spinning solution. The concentration of the spinning solution was 3.8 wt%. (2) The spinning solution is pumped into the spinning nozzle by a pumping pump, the number of the spinning holes is 10, and the diameter of the spinning holes is 0.3 mm. A mixed vapor of dry air and ethanol vapor is used as the gas source, and the air flow valve is opened to form a high-pressure air flow. The volume ratio of dry air to ethanol vapor is adjusted to 4:1 and the total pressure is adjusted to 1.3 MPa until a stable jet is formed. The jet undergoes autonomous sol-gel conversion during flight to form a gel fiber; (3) The gel fiber is subjected to solvent replacement, the replacement solvent being water, and the number of replacements is six; (4) The above hydrogel fiber is frozen at -12℃ for 8 hours, then placed in a vacuum freeze dryer and sublimated under conditions of a cold trap temperature of -80℃ and a vacuum degree of less than 0.1kPa until the fiber is free of solvent components. Please refer to Figure 1 for an optical microscope photograph of the obtained aerogel fiber, Figure 2 for a real image, Figure 3 for a BET test diagram of the obtained aerogel fiber, and Table 1 for other parameters.

[0051] [Example 2] (1) Poly(methyl methacrylate) and hydroxycellulose were dissolved in DMF, and the concentration was adjusted to a viscosity of 1000 cp to prepare a spinning solution. The concentration of the solution was 5.1 wt%. (2) The spinning solution is pumped into the spinning nozzle by a pump, the number of the spinning hole is 1, and the diameter of the spinning hole is 0.07 mm. Dry air is used as a high-pressure gas source. The air flow valve is opened to form a high-pressure air flow. The dry air pressure is adjusted to 0.1 MPa until a stable jet is formed. After the jet reaches the surface of the receiving device, it is converted into a sol-gel by impregnation (for 3 hours or less) to form a gel fiber; (3) The gel fiber is subjected to solvent replacement, the replacement solvent being water, and the number of replacements is 5; (4) The above hydrogel fiber is frozen at -12℃ for 8 hours, then placed in a vacuum freeze dryer and sublimated under conditions of a cold trap temperature of -45℃ and a vacuum degree of less than 0.1kPa until the fiber is free of solvent components. See Figure 4 for SEM micrographs of the obtained aerogel fiber, and Table 1 for other parameters.

[0052] [Example 3] (1) Poly(methyl methacrylate) was dissolved in NMP and the concentration was adjusted so that the viscosity was 1000 cp to prepare a spinning solution. The concentration of the solution was 4 wt%. (2) The spinning solution is pumped into the spinning nozzle by a pump, the number of the spinning holes is 100, the diameter of the spinning holes is 0.5 mm, dry air and hydrochloric acid vapor are used as the high-pressure gas source, the volume ratio of the dry air to the hydrochloric acid vapor is 2:1, the air flow valve is opened to form a high-pressure air flow, and the total pressure is adjusted to 1.9 MPa until a stable jet is formed. After the jet arrives on the surface of the receiving device, it is irradiated with ultraviolet light (for 3 hours or less) to convert it into a sol-gel to form a gel fiber; (3) The gel fiber is subjected to solvent replacement, the replacement solvent is ethanol, and the number of replacements is 8 times; (4) Place the gel fiber in a supercritical CO2 dryer and dry until the fiber is free of solvent components. See Table 1 for the parameters of the resulting aerogel fiber.

[0053] [Example 4] (1) Poly(vinyl alcohol) is dispersed in water and the concentration is adjusted to form a pourable gel state, and used as a spinning solution, the concentration of which is 0.1 wt% and the viscosity is 80 cp; (2) The spinning solution is pumped into a spinning nozzle by a pumping pump, the number of the spinning holes is 500, and the diameter of the spinning holes is 0.7 mm. A mixed vapor of dry air and acetone vapor is used as a gas source, and a high-pressure air flow is formed by opening an air flow valve. Until a stable jet is formed, the volume ratio of dry air to acetone vapor is adjusted to 4:1, and the total pressure is adjusted to 1.3 MPa. After the spinning solution comes into contact with the acetone vapor as a gel factor dispersed in the jet flight space, it is converted into a sol-gel to form a gel fiber; (3) The gel fiber is subjected to solvent replacement, the replacement solvent is tertiary butanol, and the replacement number is three times; (4) The gel fiber is frozen at -20°C for 10 hours, then placed in a vacuum freeze dryer and sublimated under conditions of a cold trap temperature of -60°C and a vacuum degree of less than 0.1 kPa until the fiber is free of solvent components. See Table 1 for the parameters of the obtained aerogel fiber.

[0054] [Example 5] (1) Poly(vinyl alcohol) and poly(dimethyl terephthalate) are dispersed in DMSO, and the concentration is adjusted to form an injectable gel, to prepare a spinning solution, the concentration of which is 15 wt% and the viscosity of which is 4000 cp. (2) The spinning solution is pumped into the spinning nozzle by a pump, the number of the spinning holes is 10, and the diameter of the spinning holes is 3 mm. A mixed vapor of dry air and acetone vapor is used as the gas source. The air flow valve is opened to form a high-pressure air flow. The volume ratio of dry air and acetone vapor is adjusted until the proportion of acetone gas reaches 60%, the total pressure reaches 5 MPa, and a stable jet is formed. After the jet reaches the surface of the receiving device, it is heated to 80°C (the temperature is maintained for 3 hours or less) to undergo sol-gel conversion and form gel fibers; (3) The gel fiber is subjected to solvent replacement, the replacement solvent is cyclohexane, and the number of replacements is six; (4) The gel fiber is dried at normal pressure at 80° C. until no solvent components are present. See Table 1 for the parameters of the obtained aerogel fiber.

[0055] [Example 6] (1) Poly(vinyl alcohol) and tetraethyl orthosilicate were dissolved in DMSO, and the concentration was adjusted to have a viscosity of 2000 cp to prepare a spinning solution. The concentration of the solution was 30 wt%. (2) The spinning solution is pumped into the spinning nozzle by a pump, the number of the spinning holes is 100, and the diameter of the spinning holes is 0.07 mm. A mixed vapor of dry air and ammonia gas is used as the gas source. The air flow valve is opened to form a high-pressure air flow. The volume ratio of dry air to ammonia gas is adjusted to 1:1 and the total pressure is adjusted to 1.3 MPa until a stable jet is formed. The jet is autonomously converted into a sol-gel during flight to form a gel fiber; (3) The gel fiber is subjected to solvent replacement, the replacement solvent is cyclohexane, and the replacement number is 5 times; (4) The gel fiber is dried at normal pressure at 80° C. until no solvent components are present. See Table 1 for the parameters of the obtained aerogel fiber.

[0056] [Example 7] (1) Terephthaloyl-p-phenylenediamine was dissolved in DMSO, and the concentration was adjusted to have a viscosity of 1000 cp to prepare a spinning solution. The concentration of the spinning solution was 3.8 wt%. (2) The spinning solution is pumped into the spinning nozzle by a pump, the number of the spinning holes is 10, and the diameter of the spinning holes is 0.3 mm. A mixed vapor of dry air and water vapor is used as a gas source, and a high-pressure air flow is formed by opening an air flow valve. The volume ratio of dry air to water vapor is adjusted so that the proportion of water vapor is 15% and the total pressure is 1.3 MPa until a stable jet is formed, and the jet is autonomously subjected to sol-gel conversion during flight to form a gel fiber; (3) The gel fiber is subjected to solvent replacement, the replacement solvent being water, and the number of replacements is four; (4) The above hydrogel fiber is frozen at -10°C for 24 hours, then placed in a vacuum freeze dryer and sublimated under conditions of a cold trap temperature of -50°C and a vacuum degree of less than 0.1 kPa until the fiber is free of solvent components. Please refer to Table 1 for the parameters of the obtained aerogel fiber.

[0057] [Comparative Example 1: Low boiling point volatile solvent used in spinning solution] (1) Poly(vinyl alcohol) and tetraethyl orthosilicate are dissolved in ethanol, and the concentration is adjusted to a viscosity of 1500 cp to prepare a spinning solution. (2) The spinning solution is pumped into the spinning nozzle by a pressure pump, and a mixed vapor of dry air and ammonia gas is used as the gas source. The air flow valve is opened to form a high-pressure air flow. The ratio of air to ammonia gas is adjusted to 1:1 and the total pressure is adjusted to 1.3 MPa until a stable jet is formed. (3) subjecting the gel fiber to solvent replacement, the replacement solvent being cyclohexane; (4) The fibers are dried at normal pressure at 80°C until no solvent content is present. The fibers show significant shrinkage and are tested for non-porous structure, see Table 1 for other parameters.

[0058] [Control Example 2: No sol-gel process] (1) Poly(methyl methacrylate) and hydroxycellulose were dissolved in DMSO, and the concentration was adjusted to a viscosity of 1000 cp to prepare a spinning solution. (2) The spinning solution is pumped into the spinning nozzle by a pump, and dry air is used as a high-pressure gas source. The air flow valve is opened to form a high-pressure air flow, and the air pressure is adjusted to 0.8 MPa until a stable jet is formed, forming a liquid stream on the receiving device surface; (3) subjecting the fibers to solvent exchange, the solvent being water; (4) The hydrogel fiber is frozen at -12°C for 8 hours, then placed in a vacuum freeze dryer and dried until the fiber is free of solvent components. This fiber does not form an aerogel pore structure and has a very low specific surface area; see Table 1 for other parameters.

[0059] [Table 1]

[0060] As can be seen from Examples 1-7, the aerogel fibers obtained by the above technical solutions of the present application have porous structure, high porosity and good skeletal structure stability, and are suitable for large-scale production due to their simple preparation process, mild reaction conditions and low energy consumption.

[0061] Furthermore, the inventors of the present application have also experimented with other raw materials and conditions described in this specification, with reference to the embodiments of Examples 1 to 7, and have been able to produce aerogel fibers having similarly unique porous structures and excellent skeletal structure stability.

[0062] It should be noted that the above are merely some embodiments of the present application, and any other modifications or improvements made by those skilled in the art without departing from the creative ideas of the present application are all intended to be included in the scope of protection of the present application.

[0063] (Additional Note) (Appendix 1) mixing a solvent and a polymeric material to form a spinning dope; Adopting airflow spinning technology, the spinning solution is driven by high-speed airflow to form a jet, and gel fibers are formed through sol-gel transformation; and performing a solvent replacement on the gel fiber and then drying the gel fiber to prepare an aerogel fiber.

[0064] (Appendix 2) The method for preparing the spinning solution according to claim 1, characterized in that the spinning solution contains a sol state, a semi-gel state, or a high-viscosity solution, and / or the viscosity of the spinning solution is 80 to 4000 cp and the concentration is 0.1 to 30 wt %.

[0065] (Appendix 3) The method according to claim 1, wherein the solvent is any one or a combination of two or more of DMF, DMSO, NMP, and water.

[0066] (Appendix 4) The preparation method described in Appendix 1, characterized in that the polymer material is made of a natural polymer and / or a synthetic polymer material, preferably made of any one or a combination of two or more of polyamide, polyester, cellulose, polyolefin polymer material, and polysiloxane.

[0067] (Appendix 5) The preparation method according to claim 1, characterized in that a spinneret is used as a spinning solution discharge port, the number of spinning holes is 1 to 500, the diameter of the spinning holes is 0.07 to 3 mm, an airflow passage is opened around the spinning holes, the airflow drafts the spinning solution to form a jet, the airflow is dry air or a mixed airflow of dry air and water vapor, the air pressure is 0.1 to 5 MPa, and the water vapor is any one or a combination of two or more of water vapor, alcohol vapor, hydrochloric acid, ammonia gas, and acetone vapor.

[0068] (Appendix 6) The preparation method according to claim 5, wherein the volume ratio of water vapor in the mixed gas stream is 0 to 60%.

[0069] (Appendix 7) The preparation method according to claim 1, characterized in that it includes: autonomously converting the jet into a sol-gel state during flight; or converting the spinning solution into a sol-gel state by contacting the spinning solution with water vapor as a gelling factor dispersed in the flight space of the jet; or converting the spinning solution into a sol-gel state by one of impregnation, irradiation and heating after the spinning solution jet arrives at a receiving device to form a gel fiber.

[0070] (Appendix 8) The method of claim 7, wherein the impregnation time is not longer than 3 h, the irradiation is performed using ultraviolet light, the irradiation time is not longer than 3 h, the heating temperature is not shorter than 80° C., and the temperature is maintained not longer than 3 h.

[0071] (Appendix 9) The preparation method according to claim 1, characterized in that the solvent used in the solvent substitution is any one or a combination of two or more of water, tert-butanol, ethanol, acetone, and hexane, and the solvent substitution is performed 3 to 8 times.

[0072] (Appendix 10) The preparation method described in Appendix 1, characterized in that the drying treatment is any one or a combination of two or more of supercritical drying, vacuum freeze drying, and atmospheric drying.

[0073] (Appendix 11) The method of claim 10, wherein the supercritical drying comprises replacing the organic solvent inside the gel fiber with a supercritical fluid under a supercritical state to obtain an aerogel fiber, and preferably, the supercritical fluid is any one or a combination of two or more of supercritical CO2, supercritical methanol, and supercritical ethanol.

[0074] (Appendix 12) The vacuum freeze-drying includes subjecting the gel fiber to a freeze-crystallization treatment at -10°C to -20°C for 8 to 24 hours, and then subjecting the gel fiber to a sublimation treatment under conditions of a cold trap temperature of -80 to -45°C and a vacuum degree of less than 0.1 kPa to obtain an aerogel fiber.

[0075] (Appendix 13) The method of claim 10, wherein the atmospheric drying includes directly removing the organic solvent in the gel fiber under an atmospheric pressure environment to obtain an aerogel fiber.

[0076] (Appendix 14) The aerogel fiber is a porous material with a porosity of 60% to 99% and a specific surface area of ​​10 to 2000 m 2 / g, the diameter of the aerogel fiber is 100 μm or less, the aspect ratio of the aerogel fiber is more than 100, and the internal pore structure of the aerogel fiber is composed of microporous pores with a pore size of 2 nm or less, mesoporous pores with a pore size of 2 to 50 nm, and macroporous pores with a pore size of 50 nm or more.

[0077] (Appendix 15) Use of the aerogel fiber prepared by the preparation method according to any one of appendixes 1 to 14 in the fields of spinning, chemical industry, environment or energy.

Claims

1. mixing a solvent and a polymeric material to form a spinning dope; Adopting airflow spinning technology, the spinning solution is driven by high-speed airflow to form a jet, and gel fibers are formed through sol-gel transformation; and performing a solvent replacement on the gel fiber and then drying the gel fiber to prepare an aerogel fiber.

2. 2. The method according to claim 1, wherein the spinning solution comprises a sol state, a semi-gel state or a high viscosity solution, and / or the viscosity of the spinning solution is 80-4000 cp and the concentration is 0.1-30 wt %.

3. 2. The method according to claim 1, wherein the solvent is any one or a combination of two or more of DMF, DMSO, NMP, and water.

4. The preparation method according to claim 1, characterized in that the polymeric material is made of a natural polymer and / or a synthetic polymeric material, preferably made of any one or a combination of two or more of polyamide, polyester, cellulose, polyolefin polymeric material, and polysiloxane.

5. The method according to claim 1, characterized in that: a spinneret is used as a spinning solution outlet, the number of spinning holes is 1-500, the diameter of the spinning holes is 0.07-3 mm, an airflow passage is opened around the spinning holes, the airflow drafts the spinning solution to form a jet, the airflow is dry air or a mixed airflow of dry air and water vapor, the air pressure is 0.1-5 MPa, and the water vapor is any one or a combination of two or more of water vapor, alcohol vapor, hydrochloric acid, ammonia gas, and acetone vapor.

6. The method according to claim 5, characterized in that the volume ratio of water vapor in the mixed gas stream is 0 to 60%.

7. The preparation method according to claim 1, comprising: autonomously converting the sol-gel during flight of the jet; converting the spinning solution into a sol-gel by contacting the spinning solution with water vapor as a gelling factor dispersed in the flight space of the jet; or converting the spinning solution into a sol-gel by any one of impregnation, irradiation, and heating after the spinning solution jet arrives at a receiving device to form a gel fiber.

8. 8. The method according to claim 7, characterized in that the impregnation time is not more than 3h, the irradiation is carried out using ultraviolet light, the irradiation time is not more than 3h, the heating temperature is not less than 80°C, and the temperature is maintained not more than 3h.

9. The preparation method according to claim 1, characterized in that the solvent used in the solvent replacement is any one or a combination of two or more of water, tert-butanol, ethanol, acetone, and hexane, and the number of solvent replacements is 3 to 8 times.

10. 2. The method according to claim 1, wherein the drying process is any one or a combination of two or more of supercritical drying, vacuum freeze drying, and atmospheric drying.

11. The supercritical drying includes replacing the organic solvent inside the gel fiber with a supercritical fluid under a supercritical state to obtain an aerogel fiber, and preferably, the supercritical fluid is supercritical CO ２ 11. The method according to claim 10, characterized in that the method comprises any one or a combination of two or more of supercritical methanol and supercritical ethanol.

12. The method according to claim 10, characterized in that the vacuum freeze-drying comprises subjecting the gel fiber to a freeze-crystallization treatment at -10°C to -20°C for 8 to 24 hours, and then subjecting the gel fiber to a sublimation treatment under conditions of a cold trap temperature of -80 to -45°C and a vacuum degree of less than 0.1 kPa to obtain the aerogel fiber.

13. 11. The method of claim 10, wherein the atmospheric drying comprises directly removing the organic solvent in the gel fiber under atmospheric environment to obtain the aerogel fiber.

14. The aerogel fiber is a porous material with a porosity of 60% to 99% and a specific surface area of ​​10 to 2000 m ２ / g, the diameter of the aerogel fiber is 100 μm or less, the aspect ratio of the aerogel fiber is more than 100, and the internal pore structure of the aerogel fiber is composed of microporous pores with a pore size of 2 nm or less, mesoporous pores with a pore size of 2 to 50 nm, and macroporous pores with a pore size of 50 nm or more.

15. 15. Use of the aerogel fibers prepared by the method according to any one of claims 1 to 14 in the fields of spinning, chemical industry, environment or energy.

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