Radially highly elastic aerogel fibers and applications thereof

Abstract

The application discloses radial high-elasticity aerogel fibers and application thereof, and belongs to the field of general process of processing and dosing. In the application, natural high polymer agarose is used as raw material, and after microwave heating and dissolution, the agarose is compounded with reagents such as cellulose nanofiber and polyvinyl alcohol to obtain a pre-foaming solution. Then, high-speed stirring is carried out to foam the pre-foaming solution, and then the pre-foaming solution is coaxially wet spun with a mixed solution of sodium alginate / cellulose nanofiber to obtain a hydrogel fiber. Then, through supercritical drying and chemical vapor deposition modification, the radial high-elasticity aerogel fiber is obtained. Through detection, the aerogel fiber has high radial resilience under the condition of compression of 40%.

Description

Technical Field

[0001] This invention relates to the field of general processing and ingredient preparation; and particularly to a radially highly elastic aerogel fiber and its applications. Background Technology

[0002] Aerogels are solid materials with a nanoporous three-dimensional network, formed by replacing the liquid phase in their gel backbone with a gaseous phase through a special drying method. Aerogel fibers retain the abundant nanopores of aerogels while also possessing the flexibility and spinnability of fibers, making them a potential material for manufacturing smart wearable textiles. Currently, aerogel fibers have attracted widespread attention and can be effectively manufactured using methods such as wet spinning, 3D printing, centrifugal spinning, electrospinning, and cryospinning.

[0003] Aerogel fibers retain the nanoporous structure of aerogels, giving them great potential for applications in catalysis, thermal insulation, sound absorption, and adsorption. The superior performance of aerogel fibers is determined by both their nanoporous structure and chemical composition. However, existing aerogel fibers are prone to internal network collapse under radial compression, making them unable to spring back when the external force is removed. Summary of the Invention

[0004] The purpose of this invention is to provide a radially highly elastic aerogel fiber and its application, solving the problem that the internal network skeleton of existing aerogel fibers easily collapses when subjected to radial compression, thus failing to rebound when the external force is removed.

[0005] The technical solution adopted in this invention is as follows.

[0006] In a first aspect, the present invention provides a radially highly elastic aerogel fiber, which is prepared by the following method.

[0007] Step 1: Preparation of pre-foamed mixed solution: Add cellulose nanofibers, polyvinyl alcohol solution, sodium dodecylbenzenesulfonate, anhydrous calcium chloride, and lauramide propyl hydroxysulfonate to agarose solution in sol state to obtain a pre-foamed mixed solution.

[0008] Step 2: Dissolve sodium alginate and cellulose nanofibers in water to prepare a mixed solution of sodium alginate and cellulose nanofibers.

[0009] Step 3: Stir the prepared pre-foamed mixed solution to make it foam, and use the foamed solution as the inner axis spinning solution; use the mixed solution of sodium alginate and cellulose nanofibers as the outer axis spinning solution; inject the inner axis spinning solution and the outer axis spinning solution into the coaxial needle at the same time for coaxial wet spinning; the spun fibers output from the coaxial needle are directly injected into the calcium chloride solution to gel and prepare hydrogel fibers.

[0010] Step 4: The hydrogel fibers are fully replaced with anhydrous ethanol, and then dried with supercritical carbon dioxide to obtain aerogel fibers.

[0011] Step 5: Silanization modification of aerogel fibers is performed using chemical vapor deposition to obtain radially highly elastic aerogel fibers.

[0012] Furthermore, in step 1, the agarose solution is prepared as follows: 4 g of agarose is dissolved in 96 mL of deionized water and heated until completely dissolved to obtain an agarose solution with a mass fraction of 4%.

[0013] Furthermore, in step 1, the polyvinyl alcohol solution is prepared as follows: 6 g of polyvinyl alcohol is dissolved in 94 mL of deionized water, and heated to ensure complete dissolution, thereby obtaining a polyvinyl alcohol solution with a mass fraction of 6%.

[0014] Further, in step 1, take 20 mL of agarose solution, add 18 mL of cellulose nanofibers, 2 mL of 6% polyvinyl alcohol solution, 0.2 g of sodium dodecylbenzenesulfonate, 0.4 g of anhydrous calcium chloride, and 4 mL of lauramide propyl hydroxysulfonate to obtain a pre-foamed mixed solution.

[0015] Furthermore, in step 2, sodium alginate and cellulose nanofibers are prepared in a mass ratio of 2:3.

[0016] Further, in step 3, two syringes are used to draw up the outer-axis spinning solution and the inner-axis spinning solution respectively, and then connected to the two input ports of the coaxial needle; then, the two syringes are each fixed to an electric injection pump, and the output port of the coaxial needle is inserted into the coagulant; the two injection pumps are started simultaneously, and the outer-axis spinning solution and the inner-axis spinning solution are simultaneously injected into the coaxial needle, and the hydrogel fiber is extruded from the output port of the coaxial needle into the 1~3% calcium chloride coagulation bath to gel and form; the injection rate of the inner-axis spinning solution is set to 190 mL / h; the injection rate of the outer-axis spinning solution is set to 210 mL / h.

[0017] Furthermore, in step 3, heating wires are wound around the two syringes, and during the wet spinning process, the syringes are heated to 60 degrees Celsius via the heating wires. o C-80 o C.

[0018] Furthermore, in step 4, supercritical carbon dioxide is used for drying for 6-8 hours, and the temperature of the supercritical carbon dioxide fluid is 40°C. o C~60 o C, with a pressure of 10~20 MPa.

[0019] Furthermore, in step 5, the aerogel fibers obtained in step 4 and two small centrifuge tubes are placed in the same desiccator. Each centrifuge tube contains 0.8–1.2 mL of silanization modifier and 0.6–0.9 mL of deionized water, respectively. The desiccator is placed at 70°C. o Modify in a constant temperature oven at C for 6-10 hours; the silanization modifier is methyltrimethoxysilane, methyltrichlorosilane, or trimethylchlorosilane.

[0020] Secondly, the present invention provides an application of the above-mentioned radially elastic aerogel fiber, using the radially elastic aerogel fiber as a clothing fabric.

[0021] The beneficial effects of this invention are as follows: This invention provides a radially highly elastic aerogel fiber and its application. In this invention, natural high-molecular-weight agarose is used as raw material, which is dissolved by microwave heating and then compounded with cellulose nanofibers, polyvinyl alcohol and other reagents to obtain a pre-foamed solution; then it is foamed by high-speed stirring, and then it is coaxially wet-spun with a mixed solution of sodium alginate / cellulose nanofibers to obtain hydrogel fiber; subsequently, it is modified by supercritical drying and chemical vapor deposition to obtain radially highly elastic aerogel fiber; after testing, the aerogel fiber has high radial resilience under 40% compression. Attached Figure Description

[0022] Figure 1 The diagram shown illustrates the foaming process of the pre-foamed mixed solution in Embodiment 1 of the present invention.

[0023] Figure 2 The diagram shows a schematic of the equipment for preparing hydrogel fibers by coaxial wet spinning according to the present invention.

[0024] Figure 3 The diagram shown is a structural diagram of the coaxial needle used in this invention.

[0025] Figure 4 The image shown is a display diagram of the hydrogel fibers prepared according to various embodiments of the present invention.

[0026] Figure 5 The image shown is a schematic diagram of the radially highly elastic aerogel fiber obtained in Example 1 of the present invention.

[0027] Figure 6 The image shown is a microstructure diagram of the radially highly elastic aerogel fiber obtained in Example 1 of the present invention.

[0028] Figure 7 The figure shown is a graph of the radial compression resilience test results of the radially highly elastic aerogel fiber prepared in Example 1 of the present invention.

[0029] Figure 8 The image shown is a display diagram of an aerogel textile woven from the aerogel fibers of the present invention.

[0030] Figure 9 The image shown is a display of the solar reflectance test results of the aerogel textile of the present invention.

[0031] Figure 10 The images shown are the infrared spectra and chemical bond vibration frequency diagrams of the Non-Foam AG, SA empty shell, Foam AG, and Foam AG no CVD of the present invention.

[0032] Figure 11 The figure shown is a graph of the infrared emissivity test results of the aerogel textile of the present invention.

[0033] Figure 12 The diagram shown is a schematic of the radiation cooling performance testing device of the present invention.

[0034] Figure 13 The graph shows the changes in light intensity, humidity, and irradiance over time from 10:00 AM to 3:00 PM on the day of the radiative cooling performance test.

[0035] Figure 14 The figure shown is a graph showing the temperature change over time in the two grooves during the period from 10:00 to 15:00.

[0036] Figure 15 The figure shown is a graph showing the temperature change over time in the two grooves during the period from 17:30 to 18:00 in this invention.

[0037] Figure 16 The figure shown is a graph illustrating the test results of the thermal insulation performance of the material of this invention.

[0038] Figure 17 The diagram shown illustrates the principle of the temperature self-regulating performance of the material of this invention.

[0039] Figure 18 The diagram shows a structural comparison of Non-Foam AG, SA empty shell, and Foam AG.

[0040] Figure 19 The image shows a comparison of the radial compression rebound performance test results of Non-Foam AG, SA empty shell, and Foam AG.

[0041] Figure 20 The image shows a comparison of the solar reflectance test results for Non-Foam AG, SA empty shell, and Foam AG.

[0042] Figure 21The graph shows the temperature changes over time in the four grooves: Non-Foam AG, SA empty shell, Foam AG, and Air.

[0043] Figure 22 The graph shows the thermal conductivity test results for Non-Foam AG, SA empty shell, Foam AG, Cotton, and Wool.

[0044] Figure 23 The images shown are thermal images taken by Non-Foam AG, SA empty shell, and Foam AG constant temperature heating.

[0045] Figure 24 The image shown is a scanning electron microscope image of AG-0-20, AG-2-18, and AG-4-16.

[0046] Figure 25 The image shows the foaming state of the foaming solution under four different mixing ratios: AG-0-0, AG-0-20, AG-2-18, and AG-4-16.

[0047] Figure 26 The figure shows the radial resilience test results of aerogel fibers with three different modification times.

[0048] Figure 27 The figure shown is a comparison of the hydrophobicity of aerogel fibers before and after silanization modification in Example 1 of the present invention.

[0049] In the figure, there are: first injection pump 101, second injection pump 102, first syringe 201, second syringe 202; coaxial needle 3, first inlet 301, second inlet 302, coaxial output tube 303, inner tube 304, outer tube 305; coagulation bath material box 4; EPS foam plastic 5, groove 501, aluminum foil 6, aerogel textile 7, plastic wrap 8, thermocouple 9. Detailed Implementation

[0050] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Unless otherwise specified, the methods described in the embodiments of this invention are all conventional experimental methods. All reagents and materials used are commercially available. Table 1 below summarizes the sources of some materials and related parameters of this invention.

[0052] Table 1. Summary of some material sources and related parameters of this invention.

[0053] Reagent Name source Relevant parameters Agarose Beijing Huamaike Biotechnology Co., Ltd. CAS: 9012-36-6 Brand: Spain Grade: Premium (GR) Cellulose nanofibers Huzhou Shansi New Material Technology Co., Ltd. A product with a solid content of approximately 1.2% was prepared by TEMPO oxidation. Sodium alginate Shanghai McLean Biochemical Technology Co., Ltd. CAS: 9005-38-3 Grade: Reagent Grade (90%) Polyvinyl alcohol 1750±50 Sinopharm Chemical Reagent Co., Ltd. Content ≥99%, Sodium hydroxide ≤0.2%, Volatile matter ≤9%

[0054] Example 1: A radially highly elastic aerogel fiber, which is prepared by the following method.

[0055] Step 1: Add cellulose nanofibers, polyvinyl alcohol solution, sodium dodecylbenzenesulfonate, anhydrous calcium chloride, and lauramide propyl hydroxysulfonate to the agarose solution in sol state to obtain a pre-foamed mixed solution for later use.

[0056] Furthermore, in this embodiment, the agarose solution is prepared as follows: Weigh 4 g of agarose and place it in a beaker, add 96 mL of deionized water, and then heat it in a microwave oven until completely dissolved to obtain a 4% (w / w) agarose solution. Place the prepared agarose solution in an 80°C microwave oven. o Store in a constant temperature oven (C) for later use.

[0057] In this specific operation, the beaker is placed in a microwave oven and heated to boiling until the agarose is completely dissolved. The beaker can be removed several times to observe the dissolution process. The agarose solution is heated to 40°C. o C-60 o At temperature C, it has a jelly-like consistency; below 40... o At temperature C, agarose will form a hard gel, making subsequent reactions impossible; therefore, the agarose solution needs to be at a temperature above 60°C before use. o Store at a temperature of C; in this embodiment, the preferred storage temperature is 80°C. o C.

[0058] In this embodiment, the polyvinyl alcohol solution is prepared as follows: Weigh 6 g of polyvinyl alcohol into a beaker, then add 94 mL of deionized water; place the beaker in an oil bath and heat to 100°C. o C is used to fully dissolve the polyvinyl alcohol to obtain a 6% (w / w) polyvinyl alcohol solution for later use.

[0059] In this embodiment, the reagent mixing method is as follows: Place a beaker on a constant temperature heating platform, add 20 mL of the prepared agarose solution, and set the heating platform temperature to 80°C. o C, to keep the agarose solution in a sol state. Then, add 18 mL of cellulose nanofibers, 2 mL of 6% polyvinyl alcohol solution, 0.2 g of sodium dodecylbenzenesulfonate, 0.4 g of anhydrous calcium chloride, and 4 mL of lauramide propyl hydroxysulfonate to a beaker to obtain a pre-foamed mixed solution for later use.

[0060] Step 2: Dissolve sodium alginate and cellulose nanofibers in water to prepare a mixed solution of sodium alginate and cellulose nanofibers.

[0061] In this embodiment, sodium alginate and cellulose nanofibers are prepared at a mass ratio of 2:3. In specific operation, first, 95 mL of deionized water is placed in a beaker, the beaker is placed on a stirring table, and stirring is turned on. Then, 2 g of sodium alginate is weighed and added to the beaker. Subsequently, 3 g of cellulose nanofiber dispersion is added to the beaker using a syringe and stirred until completely dissolved to obtain a mixed solution of sodium alginate and cellulose nanofibers.

[0062] It should be noted that the order of steps 1 and 2 above is not important.

[0063] Step 3: Stir the pre-foamed mixed solution prepared in Step 1 to make it foam, and use the foamed solution as the inner axis spinning solution; use the mixed solution of sodium alginate and cellulose nanofibers as the outer axis spinning solution; inject the inner axis spinning solution and the outer axis spinning solution into the coaxial needle at the same time for coaxial wet spinning; the spun fibers output from the coaxial needle are directly gelled in the calcium chloride solution to prepare hydrogel fibers.

[0064] In this embodiment, a mechanical stirrer is used to stir the pre-foamed mixture at high speed until its volume remains constant, obtaining a stable foamed solution for later use. In this embodiment, the stirring speed is 2000 r / min.

[0065] The explanation is as follows: In the pre-foamed mixed solution of this invention, sodium dodecylbenzenesulfonate and polyvinyl alcohol work together to stabilize the bubbles; lauramide propyl hydroxysulfonate betaine acts as a foaming aid to cause the solution to foam. Figure 1 The diagram illustrates the foaming process of the pre-foamed mixed solution in Embodiment 1 of the present invention. In the diagram, the left side shows the pre-foamed mixed solution (mixed solution before foaming), the middle side shows the solution after foaming, and the right side shows the foamed solution after 10 minutes. Actual observation shows that the foaming solution of the present invention can maintain stability for a long time after foaming.

[0066] The specific method for preparing hydrogel fibers by coaxial wet spinning is as follows: Figure 2 The diagram shows a schematic of the equipment for preparing hydrogel fibers using coaxial wet spinning according to the present invention. The equipment mainly includes two 10 mL syringes, two electric injection pumps, a coaxial needle, and a coagulation bath material box 4. The coagulation bath material box contains a coagulant; in this embodiment, the coagulant is specifically a 2% (by mass) calcium chloride solution.

[0067] Two syringes are used to inject the outer-axis spinning solution and the inner-axis spinning solution, respectively. After drawing up the injection solution, the two syringes are connected to the two inlets of a coaxial needle. Then, each syringe is fixed to an electric injection pump, and the output port of the coaxial needle extends into the coagulant. When both injection pumps are started simultaneously, the outer-axis spinning solution and the inner-axis spinning solution are simultaneously fed into the coaxial needle. The output port of the coaxial needle extrudes hydrogel fibers into the coagulant to gel and form a solidified gel.

[0068] In addition, to ensure that the foaming solution inside the syringe remains in a sol state, a temperature-controlled heating wire is wound around the syringe that draws the foaming solution. The temperature of the heating wire is set to 60°C. o C-80 o C, preferably 70 o C. The purpose of this design is to prevent the foaming solution from gelling inside the syringe and coaxial needle, causing blockage and preventing spinning.

[0069] Furthermore, if the temperature of the outer-axis spinning solution is lower than that of the foaming solution, and the temperature difference is significant, the foaming solution entering the coaxial needle will exchange heat with the outer-axis spinning solution, causing the temperature to drop. The foaming solution will also gel within the coaxial needle, clogging it and preventing spinning. Therefore, in a preferred embodiment, a temperature-controlled heating wire is also wound around the syringe that draws the outer-axis spinning solution, with the heating wire temperature set to 60°C. o C-80 o C, preferably 70 o C.

[0070] In this embodiment, the coaxial needle 3 is model number 20-13G. For example... Figure 3 The diagram shows the structure of the coaxial needle used in this invention. The total length of the coaxial needle is 50.6 mm, the diameter of the first input port 301 is 5.4 mm, the diameter of the second input port 302 is 5.4 mm, the length of the coaxial output tube 303 is 30 mm, and the coaxial output tube is composed of inner and outer tubes. The inner tube 304 has a diameter of 0.6 mm and a wall thickness of 0.3 mm; the outer tube 305 has a diameter of 1.9 mm and a wall thickness of 0.5 mm.

[0071] In one specific embodiment, the devices can be assembled in the following manner. For example... Figure 2As shown, one syringe pump is placed horizontally; for ease of description, this syringe pump is designated as the first syringe pump 101. The other syringe pump is vertically mounted via a support; for ease of description, this syringe pump is designated as the second syringe pump 102. A syringe is used to draw a mixed solution of sodium alginate and cellulose nanofibers as the outer-axis spinning solution; for ease of description, this syringe is designated as the first syringe 201. The first syringe 201 is connected to the second input port 302 of the coaxial needle 3. Another syringe is used to draw a stable foaming solution as the inner-axis spinning solution; for ease of description, this syringe is designated as the second syringe 202. The second syringe 202 is connected to the first input port 301 of the coaxial needle 3.

[0072] Then, the first syringe 201 is installed on the first injection pump 101, and the second syringe 202 is installed on the second injection pump 102. The injection rate of the inner-axis spinning solution is set to 190 mL / h; the injection rate of the outer-axis spinning solution is set to 210 mL / h. After setting the relevant parameters, the injection pumps are started for coaxial wet spinning. The two spinning solutions are extruded through the coaxial needle 3 and then enter a 2% (w / w) calcium chloride coagulation bath. A stable gel shell forms the instant sodium alginate comes into contact with calcium chloride, providing sufficient time for the agarose solution after inner-axis foaming to cool and gel; without the outer spinning solution, stable hydrogel fibers cannot be formed. Figure 4 The image shown is a display diagram of the hydrogel fibers prepared according to various embodiments of the present invention.

[0073] Step 4: The hydrogel fibers are fully replaced with anhydrous ethanol, and then dried with supercritical carbon dioxide to obtain aerogel fibers.

[0074] In this embodiment, the hydrogel fibers obtained in step 3 were completely replaced with anhydrous ethanol three times, with a replacement cycle of 12 hours, to completely convert the internal aqueous phase into the ethanol phase. Subsequently, they were dried using supercritical carbon dioxide for 8 hours to obtain aerogel fibers. In this embodiment, the temperature of the supercritical carbon dioxide fluid was 50°C. o C, pressure is 18 MPa.

[0075] Step 5: Silanization modification of aerogel fibers is performed using chemical vapor deposition to obtain radially highly elastic aerogel fibers.

[0076] The specific operation method in this embodiment is as follows: The aerogel fiber obtained in step 4 and two small centrifuge tubes are placed in the same desiccator. The two centrifuge tubes contain 1 mL of methyltrimethoxysilane and 0.8 mL of deionized water, respectively. The desiccator is placed at 70°C. o The aerogel fibers were modified in a constant temperature oven at C for 8 h. A rigid hydrophobic layer was uniformly coated on the surface of the prepared aerogel fibers through a chemical reaction, resulting in radially highly elastic aerogel fibers, denoted as Foam AG.

[0077] like Figure 5 The image shown is a schematic diagram of the radially highly elastic aerogel fibers obtained in Example 1 of the present invention. Figure 6 The image shown is a microstructure diagram of the radially highly elastic aerogel fibers obtained in Example 1 of this invention. From... Figure 6 As can be seen, the radially highly elastic aerogel fiber prepared by this invention has a large number of dome-shaped pore structures inside, and the size of these dome structures is measured to be 0.8~50 µm.

[0078] Furthermore, to verify the radial resilience of the aerogel fibers, this invention employs a universal testing machine to test their radial compression resilience performance. For example... Figure 7 The figure shown is a test result of the radial compression resilience of the radially highly elastic aerogel fiber prepared in Example 1 of the present invention. The test results showed that the aerogel fiber could rebound almost 100% under 40% compression, which proves that it has high radial resilience.

[0079] Furthermore, this invention investigates other performance benefits of the dome structure.

[0080] The aerogel fibers of this invention contain numerous dome structures, and the walls of these dome structures act like concave mirrors, reflecting sunlight. To verify their sunlight reflection capability, the prepared aerogel fibers were woven into aerogel textiles. Figure 8 The image shown is an illustration of an aerogel textile woven from the aerogel fibers of this invention. The aerogel textile is made by interlacing several aerogel fibers.

[0081] This invention uses an ultraviolet-visible-near-infrared spectrometer for testing. For example... Figure 9 The image shown illustrates the solar reflectance test results of the aerogel textile of this invention. The test results indicate that the material of this invention has a high solar reflectance.

[0082] Subsequently, the present invention used an infrared spectrometer to test the vibrational frequencies of its internal chemical bonds. For example... Figure 10 The figures show the infrared spectra and chemical bond vibration frequency diagrams of the Non-Foam AG, SA empty shell, Foam AG, and Foam AG no CVD aerogels of this invention. Foam AG represents the radially highly elastic aerogel fiber prepared in this embodiment, Foam AG no CVD represents the aerogel in this embodiment without modification in step 5, and Non-Foam AG and SA empty shell are materials obtained in subsequent experiments of this invention. The study found that the vibrational frequencies of CH, Si-O-Si, and COC within the aerogel fibers of this invention fall precisely within the atmospheric transparency window of 8-12 µm, which is the basis for their high infrared emissivity.

[0083] The emissivity of this invention was further tested using a Fourier transform infrared spectrometer. Figure 11 The image shown is a graph illustrating the infrared emissivity test results of the aerogel textile of this invention. The test results indicate that the aerogel fiber of this invention possesses a high infrared emissivity of 95%.

[0084] High solar reflectivity and high infrared emissivity are the foundation for the high radiative cooling performance of the aerogel fibers of this invention. To intuitively understand its radiative cooling performance, this invention employed a radiative cooling performance testing device for field testing.

[0085] like Figure 12 The diagram shows a schematic of the radiative cooling performance testing device of the present invention. The device includes a 30cm x 30cm cube-shaped EPS foam 5. To prevent external factors from affecting the test results, aluminum foil 6 is used to cover the outer surface of the EPS foam. Then, two square grooves 501, each 1cm deep, are cut into one side of the foam. The two grooves are of the same size, and the aerogel textile 7 of the present invention is fixed at the opening of one of the grooves. Plastic wrap 8 is then used to cover the grooves to eliminate the influence of convective heat transfer. A thermocouple 9 is placed in each of the two grooves to detect the temperature within each groove. The outputs of the two thermocouples are connected to a temperature controller (Agilent 34972A, USA). The temperature within the two grooves is recorded every 3 seconds and the data is transmitted to a computer. The radiative cooling performance of the material of the present invention is measured by the temperature difference between the two grooves.

[0086] The radiative cooling performance test method is as follows: The test will be conducted on September 18, 2025, outdoors in Baotou City. The grooved side of the EPS foam plastic will face the sun. The temperature changes in the two grooves will be recorded between 10:00 AM and 3:00 PM on that day.

[0087] like Figure 13 The graph shown depicts the changes in light intensity, humidity, and irradiance over time from 10:00 AM to 3:00 PM on the day of the radiative cooling performance test. Figure 14 The figure shows the temperature changes over time in the two grooves during the period from 10:00 AM to 3:00 PM. The test results show that from 10:00 AM to 3:00 PM on the test day, the temperature in the groove where the aerogel textile of this invention was placed was consistently lower than the temperature in the other empty groove; this indicates that the material of this invention has radiative cooling properties, and that the material of this invention has a peak temperature of 8... o The radiative cooling effect of C.

[0088] The invention also recorded the temperature changes within the two grooves between 5:30 PM and 6:00 PM that day. For example... Figure 15The graph shows the temperature changes over time in the two grooves during the period from 17:30 to 18:00. As can be seen from the graph, before 17:45, the temperature in the groove containing the aerogel textile of this invention was consistently lower than the temperature in the other empty groove; after 17:45, the temperature in the groove containing the aerogel textile of this invention was slightly higher than the temperature in the other empty groove.

[0089] Subsequently, to verify the thermal insulation performance of the material of the present invention, the thermal conductivity of the aerogel textile was tested using a thermal conductivity meter. The test results showed that the thermal conductivity of the aerogel textile of the present invention was 0.034 W·m. -1 ·K -1 Its extremely low thermal conductivity indicates that it has excellent thermal insulation properties.

[0090] To visually observe the thermal insulation performance of the aerogel fiber of this invention, the thermal insulation performance of the aerogel textile was further tested. The specific operation is as follows: the aerogel textile was placed on the hot plate of the heating stage, the temperature of the heating stage was controlled to rise, and two thermocouples were used to detect the temperature of the hot plate and the temperature of the upper surface of the aerogel textile, respectively.

[0091] like Figure 16 The figure shows the test results of the thermal insulation performance of the material of this invention. In the figure, the horizontal axis represents the temperature of the hot plate, and the vertical axis represents the absolute value of the difference between the temperature of the hot plate and the surface temperature of the aerogel textile. The test found that when the temperature of the hot plate reaches 90°C... o At temperature C, the surface temperature of the aerogel textile is lower than that of the hot plate, and the difference is 32°C. o C, which directly proves that the aerogel fiber prepared by the present invention has good thermal insulation properties.

[0092] The excellent radiative cooling and thermal insulation properties give the material of this invention temperature self-regulating properties, enabling it to be used in the preparation of thermal insulation fabrics. For example... Figure 17 The diagram illustrates the principle of the temperature self-regulating performance of the material of this invention. At the beginning of the day, as the sun rises and solar radiation intensifies, the ambient temperature gradually increases. The radiative cooling capacity of the material of this invention plays a dominant role, consistently maintaining the temperature inside the material below the ambient temperature, thus keeping the human body cool and comfortable in hot environments. As the sun sets and the ambient temperature gradually decreases, the material's heat insulation performance begins to play a dominant role, keeping the human body warm in cold environments.

[0093] Furthermore, the present invention conducts the following experiments to study the influence of important factors in the process of the present invention.

[0094] Experiment 1: In this experiment, two materials were prepared: a non-foamed aerogel material (denoted as Non-Foam AG). A mixed solution of sodium alginate and cellulose nanofibers was used as the outer axial spinning solution, and a 2% (w / w) calcium chloride solution was used as the inner axial spinning solution; a hollow shell (denoted as SA empty shell) was prepared. The aerogel prepared in Example 1 is denoted as Foam AG. Non-Foam AG and Foam AG were used to compare the effects of foaming and non-foaming on the prepared materials. The SA empty shell was used to compare the effect of the shell formed by the outer axial spinning solution on the material.

[0095] The preparation method of Non-Foam AG is as follows: Various reagents are prepared using the method in Example 1, except that the inner shaft spinning solution is not stirred and foamed, and the rest of the operation is the same as in Example 1.

[0096] The preparation method of the SA empty shell is as follows: A mixed solution of sodium alginate and cellulose nanofibers was prepared using step 2 of Example 1. A 2% (w / w) calcium chloride solution was used as the inner axial spinning solution; the mixed solution of sodium alginate and cellulose nanofibers was used as the outer axial spinning solution; the inner and outer axial spinning solutions were simultaneously injected into a coaxial needle for coaxial wet spinning. During the coaxial wet spinning process, the injection rate of the inner axial spinning solution was set to 30 mL / h; the injection rate of the outer axial spinning solution was set to 45 mL / h. Subsequent steps were the same as in Example 1.

[0097] like Figure 18 The image shows a structural comparison of Non-Foam AG, SA empty shell, and Foam AG. As can be seen from the image, Foam AG contains a large number of micron and submicron-sized dome pores; Non-Foam AG and SA empty shell have large, discontinuous nano-network structures inside.

[0098] Next, the present invention conducted the following series of tests on Non-Foam AG, SA empty shell, and Foam AG.

[0099] First, this invention tested the radial resilience of Non-Foam AG, SA empty shell, and Foam AG, such as... Figure 19The image shows a comparison of the radial compression resilience test results for Non-Foam AG, SA empty shell, and Foam AG. The tests show that, under 40% compression, the foamed aerogel fiber of this invention can almost completely rebound; the rebound rate of non-foam AG is 61%; and the rebound rate of SA empty shell is 90%. This demonstrates that introducing the dome structure into the aerogel fiber in this invention can improve the radial resilience of the material.

[0100] like Figure 20 The image shows a comparison of the solar reflectance test results for Non-Foam AG, SA empty shell, and Foam AG. As can be seen from the image, Foam AG has a higher solar reflectance than both Non-Foam AG and SA empty shell. This test demonstrates that introducing aerogel fibers into the dome structure can significantly improve the material's solar reflectance. Since its internal chemical composition remains unchanged, the difference in infrared emissivity is not significant.

[0101] Subsequently, the present invention weaves Non-Foam AG, SA empty shell, and Foam AG fibers into textiles and conducts field tests on their radiation cooling performance using the apparatus described in Example 1.

[0102] In practice, four 1cm deep square grooves are carved into one side of a 30cm x 30cm cube of EPS foam. The four grooves are identical in size. Non-Foam AG, SAempty shell, and Foam AG fibers woven into textiles are fixed to the openings of three of the grooves, respectively. The grooves are then covered with plastic wrap to eliminate the influence of convective heat transfer. A thermocouple is placed in each of the four grooves to monitor the temperature. The temperature of each groove is recorded every 3 seconds and the data is transmitted to a computer.

[0103] like Figure 21 The graph shows the temperature changes over time in four grooves: Non-Foam AG, SA empty shell, Foam AG, and Air. Air represents an empty groove. The graph shows that the temperature in the Foam AG groove is the lowest of the four. Specifically, the temperature of the aerogel fiber with the dome structure is 3-5 degrees Celsius lower than the other two. o C. This phenomenon proves that the dome structure introduced in this invention can improve its radiative cooling performance.

[0104] To visually observe the thermal insulation performance of the three materials, this invention conducted thermal conductivity tests on textiles made from these three materials. The results were then compared with those of thermal conductivity tests on cotton and wool. Figure 22 The graph shows the thermal conductivity test results for Non-Foam AG, SA empty shell, Foam AG, Cotton, and Wool. The test results indicate that the thermal conductivity of the foamed aerogel fiber is significantly lower than that of other textiles.

[0105] Subsequently, this invention places three textiles—Non-Foam AG, SA empty shell, and Foam AG—at 90°C. o Thermal images of C are taken using an infrared thermal imaging camera on a constant-temperature heat source. For example... Figure 23 The images shown are thermal images taken during constant-temperature heating of Non-Foam AG, SA empty shell, and Foam AG. It can be clearly observed from the images that the surface temperature of the textile made from foamed aerogel fibers is significantly lower than the other two types. This directly demonstrates that introducing a dome structure into the aerogel fibers in this invention can improve the thermal insulation performance of the aerogel fibers.

[0106] Experiment 2: This experiment aims to verify the effect of different polyvinyl alcohol to cellulose nanofiber ratios on aerogel fibers.

[0107] This experiment uses the preparation method of Example 1, except that while keeping the total amount of polyvinyl alcohol and cellulose nanofibers in the pre-foamed solution constant at 20 mL, the polyvinyl alcohol content is varied to 0 mL, 2 mL, and 4 mL.

[0108] The aerogel fibers prepared under the three formulations were named according to the following rules: AG-xy (naming rule: x represents the amount of polyvinyl alcohol added, and y represents the amount of cellulose nanofibers added). Therefore, the aerogel fiber prepared with 0 g of polyvinyl alcohol content was designated as AG-0-20; the aerogel fiber prepared with 2 g of polyvinyl alcohol content was designated as AG-2-18 (the formulation used in Example 1); and the aerogel fiber prepared with 4 g of polyvinyl alcohol content was designated as AG-4-16.

[0109] After obtaining the aerogel fibers, the present invention used scanning electron microscopy to observe the microstructure of the three materials. For example... Figure 24The images show scanning electron microscope (SEM) images of AG-0-20, AG-2-18, and AG-4-16. As can be seen from the images, AG-2-18 has the most complete gradient dome structure, while AG-0-20, although possessing a complete three-dimensional network structure, does not exhibit a clear gradient dome structure. In AG-4-16, it is evident that the number of fracture points within the aerogel fibers increases significantly with increasing polyvinyl alcohol content.

[0110] like Figure 25 The diagram shows the foaming state of the foaming solution under four different formulations: AG-0-0 (0% polyvinyl alcohol and 0% cellulose nanofiber), AG-0-20 (0% polyvinyl alcohol and 20% cellulose nanofiber), AG-2-18 (2% polyvinyl alcohol and 18% cellulose nanofiber), and AG-4-16 (4% polyvinyl alcohol and 16% cellulose nanofiber). As can be seen from the diagram, when the polyvinyl alcohol content is too high, it occupies a large portion of the liquid film, resulting in a decrease in both the foaming capacity and the stability of the bubbles, thus failing to meet the requirements for subsequent use.

[0111] Experiment 3: This experiment was conducted to investigate the effect of different silanization modification times on aerogel fibers.

[0112] This experiment involved silanization modification of the aerogel fibers prepared in Example 1 at different times. First, the aerogel fibers prepared in step 4 of Example 1 were uniformly divided into three equal portions. Then, each portion, along with two small centrifuge tubes, was placed in a desiccator. Each centrifuge tube contained 1 mL of methyltrimethoxysilane and 0.8 mL of deionized water, respectively. The desiccator was placed at 70°C. o The aerogel fibers were modified in a constant temperature oven at temperature C for 6 h, 8 h, and 10 h, respectively. The remaining operations were the same as in Example 1. A rigid hydrophobic layer was uniformly coated onto the prepared aerogel fibers through a chemical reaction to obtain radially highly elastic aerogel fibers.

[0113] Subsequently, this invention used a universal testing machine to test the radial resilience of aerogel fibers with different modification times. For example... Figure 26 The figure shows the radial resilience test results of aerogel fibers with three different modification times. The test results show that the radial elasticity of aerogel fibers is significantly enhanced with the extension of modification time. However, when the modification time reaches 10 h, the brittleness of the internal skeleton of the aerogel fibers also increases due to the excessively long reaction time, resulting in poor radial resilience.

[0114] like Figure 27The image shows a comparison of the hydrophobicity of aerogel fibers before and after silanization modification in Example 1 of this invention. The hydrophobicity of the aerogel fibers modified by chemical vapor deposition is significantly improved, which provides a foundation for their application in the field of smart clothing fabrics.

[0115] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A radially highly elastic aerogel fiber, characterized in that, The aerogel fiber was prepared by the following method: Step 1: Preparation of pre-foamed mixed solution: Cellulose nanofibers, polyvinyl alcohol solution, sodium dodecylbenzenesulfonate, anhydrous calcium chloride, and lauramide propyl hydroxysulfonate betaine are added to agarose solution in sol state to obtain a pre-foamed mixed solution; Step 2: Dissolve sodium alginate and cellulose nanofibers in water to prepare a mixed solution of sodium alginate and cellulose nanofibers; Step 3: Stir the prepared pre-foamed mixed solution to make it foam, and use the foamed solution as the inner axis spinning solution; use the mixed solution of sodium alginate and cellulose nanofibers as the outer axis spinning solution; inject the inner axis spinning solution and the outer axis spinning solution into the coaxial needle at the same time for coaxial wet spinning; the spun fibers output from the coaxial needle are directly injected into the calcium chloride solution to gel and prepare hydrogel fibers. Step 4: The hydrogel fibers are fully replaced with anhydrous ethanol, and then dried with supercritical carbon dioxide to obtain aerogel fibers. Step 5: Silanization modification of aerogel fibers using chemical vapor deposition to obtain radially highly elastic aerogel fibers. Specifically, the aerogel fibers obtained in Step 4 and two small centrifuge tubes are placed in the same desiccator. The two centrifuge tubes contain a silanization modifier and deionized water, respectively. The desiccator is placed at 70°C. o Modify in a constant temperature oven at C for 6-10 hours; the silanization modifier is methyltrimethoxysilane, methyltrichlorosilane, or trimethylchlorosilane.

2. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 1, the agarose solution is prepared as follows: Dissolve 4 g of agarose in 96 mL of deionized water and heat until completely dissolved to obtain an agarose solution with a mass fraction of 4%.

3. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 1, the polyvinyl alcohol solution is prepared as follows: 6 g of polyvinyl alcohol is dissolved in 94 mL of deionized water and heated to fully dissolve it, resulting in a polyvinyl alcohol solution with a mass fraction of 6%.

4. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 1, take 20 mL of agarose solution, add 18 mL of cellulose nanofibers, 2 mL of 6% polyvinyl alcohol solution, 0.2 g of sodium dodecylbenzenesulfonate, 0.4 g of anhydrous calcium chloride, and 4 mL of lauramide propyl hydroxysulfonate to obtain a pre-foamed mixed solution.

5. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 2, sodium alginate and cellulose nanofibers are prepared at a mass ratio of 2:

3.

6. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 3, two syringes are used to draw up the outer-axis spinning solution and the inner-axis spinning solution respectively, and then connected to the two input ports of the coaxial needle. Next, each of the two syringes is fixed to an electric injection pump, and the output port of the coaxial needle is inserted into the coagulant. The two injection pumps are started simultaneously, and the outer-axis spinning solution and the inner-axis spinning solution are simultaneously injected into the coaxial needle. The hydrogel fibers are extruded from the output port of the coaxial needle and enter the 1-3% calcium chloride coagulation bath to gel and form. The injection rate of the inner-axis spinning solution is set to 190 mL / h, and the injection rate of the outer-axis spinning solution is set to 210 mL / h.

7. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 3, heating wires are wound around the two syringes, and the syringes are heated to 60°C through the heating wires during the wet spinning process. o C-80 o C.

8. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 4, supercritical carbon dioxide is used for drying for 6-8 hours, and the temperature of the supercritical carbon dioxide fluid is 40°C. o C~60 o C, with a pressure of 10~20 MPa.

9. The radially highly elastic aerogel fiber according to claim 1, characterized in that, In step 5, two centrifuge tubes are filled with 0.8-1.2 mL of silanization modifier and 0.6-0.9 mL of deionized water, respectively.

10. An application of the radially highly elastic aerogel fiber according to claim 1, characterized in that, Radial high elasticity aerogel fibers are used as clothing fabrics.

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