Modified fiber aerogel and preparation method thereof

Abstract

The invention provides a preparation method of modified fiber aerogel, which comprises the following steps: carrying out electrostatic spinning on a spinning solution under the assistance of airflow to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor; taking one or two of triaminopropyl triethyl silane and triaminopropyl methyl diethoxy silane to prepare a liquid silane aqueous solution; and depositing an organosilane polymeric membrane on the SiO2-ZrO2 doped nanofiber aerogel precursor by using a liquid silane aqueous solution through a low-temperature and low-pressure vapor deposition method to obtain the modified fiber aerogel. The high polymer fiber prepared by electrostatic spinning has a large amount of Si-OH, the group is uniformly spread on the surface of the fiber, and meanwhile, the existence of the group provides a reaction site for a subsequent gas phase reaction, so that the preparation of a fiber aerogel coating is realized in a low-pressure and low-temperature environment. The high temperature resistance and the mechanical property of the prepared super-uniform fiber coating are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to a modified fiber aerogel and a preparation method thereof. Background Art

[0002] Aerogel is a material with a three-dimensional network structure. It features high porosity, a large specific surface area, and low thermal conductivity. It is the lowest-density solid material known. Due to its excellent thermal insulation properties, aerogel has been widely used in energy conservation, heat preservation, fire safety, and social life in recent years.

[0003] Nanofiber aerogels are generally prepared by electrospinning. When nanofibers randomly self-assemble and stack to form block-shaped nanofiber aerogels, they will automatically wrap a large amount of air, thereby forming a micron-level pore structure with a porosity greater than 90%. The existence of these pore structures can extremely effectively inhibit the convective heat transfer of high and low temperatures in objects. In addition, nanofiber aerogels have multiple layers of high refractive index interfaces, which can reflect electromagnetic waves multiple times, inhibiting the radiation heat transfer of high-temperature objects to low-temperature objects.

[0004] At the same time, since the stacking direction and path of nanofibers change when they are self-assembled through electrospinning, multiple tortuous paths will be formed between the nanofibers in the nanofiber aerogel material, which can sharply increase the heat conduction and heat transfer path in the solid.

[0005] Aerogels prepared by airflow-assisted electrospinning have the advantages of rapid prototyping and low energy consumption. However, in practical applications, thermal insulation materials often need to have low thermal conductivity while also possessing a certain degree of compressive resistance to bear a certain load. Performance tests of nanofiber aerogels of different densities found that the mechanical properties of nanofiber aerogels are positively correlated with the aerogel density. However, as the aerogel density increases, the thermal conductivity of the aerogel also increases significantly, indicating a contradiction between the mechanical properties and thermal insulation properties of the aerogel.

[0006] Therefore, enhancing the mechanical properties of aerogels without affecting their thermal insulation performance as much as possible is of great significance to broadening the application scenarios of direct spinning nanofiber aerogels. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a modified fiber aerogel. The modified fiber aerogel provided by the present invention has good high temperature resistance and good mechanical properties.

[0008] The present invention provides a method for preparing a modified fiber aerogel, comprising the following steps:

[0009] A) electrospinning the spinning solution with the aid of airflow to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor;

[0010] B) taking one or both of triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane to prepare a liquid silane aqueous solution;

[0011] C) by low temperature and low pressure vapor deposition method, liquid silane aqueous solution is deposited on the doped SiO2-ZrO2 nanofiber aerogel precursor to obtain modified fiber aerogel.

[0012] Preferably, the temperature of the low-temperature and low-pressure vapor deposition method is 85 to 95° C., the pressure is 20,000 Pa to 30,000 Pa, and the deposition time is 4 to 6 hours.

[0013] Preferably, the molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is (0-0.5): (0.5-1).

[0014] Preferably, the volume ratio of the doped SiO2-ZrO2 nanofiber aerogel precursor to the liquid silane aqueous solution is 50-100 cm 3 :3ml;

[0015] The thickness of the organosilane polymer film is less than 5 nm.

[0016] Preferably, the electrospinning parameters in step A) include:

[0017] The spinning temperature is 20-40°C, the spinning humidity is 20%-40%; the spinning receiver is a drum receiver, and the rotation speed of the drum receiver is 100-200 r / min; the spinning air flow speed is 3-8 L / min, the airflow-assisted spinning needle has an inner ring of No. 23 needle and an outer ring diameter of 1.5 mm; the voltage is 15-25 kV for positive pressure and 1-10 kV for negative pressure.

[0018] Preferably, the method for preparing the spinning solution comprises:

[0019] S1) mixing zirconium acetate, ZrOCl2 8H2O and yttrium nitrate hexahydrate to obtain a first solution;

[0020] S2) mixing triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane, and stirring to prepare a liquid silane aqueous solution;

[0021] S3) adding the liquid silane aqueous solution dropwise to the first solution, then adding polyethylene oxide, and then adjusting the pH value to obtain a spinning solution.

[0022] Preferably, the pH value is adjusted to 1-2.

[0023] Preferably, the molar ratio of the zirconium acetate and ZrOCl2 8H2O is 1:1;

[0024] The molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is (0-0.5): (0.5-1).

[0025] Preferably, the dripping speed of S3) is 2 mL / min; the molecular weight of the polyethylene oxide is 300,000.

[0026] The present invention provides a modified fiber aerogel, which is prepared by the preparation method described in any one of the above technical solutions.

[0027] Compared to the prior art, the present invention provides a method for preparing modified fiber aerogels, comprising the following steps: A) electrospinning a spinning solution using airflow assistance to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor; B) preparing a liquid silane aqueous solution using one or both of triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane; and C) depositing an organosilane polymer film on the doped SiO2-ZrO2 nanofiber aerogel precursor using the liquid silane aqueous solution via a low-temperature, low-pressure vapor deposition method to obtain the modified fiber aerogel. The polymer fibers prepared by electrospinning in the present invention possess a large number of Si-OH groups uniformly distributed across the fiber surface. These groups provide reaction sites for subsequent vapor-phase reactions, thereby enabling the preparation of a fiber aerogel coating under low-pressure, low-temperature conditions. The resulting ultra-uniform fiber coating facilitates mass industrial production and significantly improves high-temperature resistance and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 (a) TEM image of the cross-node position of the deposited organosilane polymer film sample; (b) and (c) high-resolution TEM images of the surface of the undeposited sample and the deposited sample; (d) and (e) EDS electron images of the undeposited sample and the deposited sample;

[0029] Figure 2 Thermal conductivity difference plot;

[0030] Figure 3 Energy loss and cyclic performance test of reinforced nanofiber aerogel: (a) Energy loss under different compression strains; (b) 250 compression cycle curves of nanofibers;

[0031] Figure 4 This is the contact angle test diagram of fiber aerogel;

[0032] Figure 5 This is the contact angle test diagram of fiber aerogel;

[0033] Figure 6 Schematic diagram of the synthesis process. DETAILED DESCRIPTION

[0034] The present invention provides a modified fiber aerogel and a method for preparing the same. Those skilled in the art can refer to the contents herein and appropriately modify the process parameters to achieve the desired results. It is particularly important to note that all similar substitutions and modifications will be readily apparent to those skilled in the art and fall within the scope of protection of the present invention. The methods and applications of the present invention have been described through preferred embodiments. It is clear that those skilled in the art can modify or appropriately alter and combine the methods and applications herein to implement and apply the technology of the present invention without departing from the content, spirit, and scope of the present invention.

[0035] In this application, the term "and / or" describes the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0036] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0037] The inventors have found through extensive research that there are two main methods for reinforcing fiber aerogels: (1) Liquid phase method: The aerogel is immersed in a solution and an adhesive substance is grown on the surface of the nanofibers through liquid-solid interface reaction or drying, thereby achieving a reinforcing effect. (2) Gas phase method: A uniform thin film can be deposited on the fiber surface by chemical vapor deposition or evaporation, forming a reinforcing structure. While providing cross nodes for the nanofibers, the surface of the nanofibers can be strengthened to improve the bending resistance of the nanofibers. Large-scale production of lightweight ceramic aerogels with superelasticity and high mechanical strength is a necessary condition for their practical application. The key to improving the strength of ceramic aerogels without reducing superelasticity lies in reasonable material selection and creative structural design, as well as the bonding design between building blocks. The present invention adopts a gas phase method to coat the fiber aerogel material with a coating through a simple technique. The coating can improve the various performances of the original fiber aerogel and expand the application range of the fiber aerogel.

[0038] The present invention proposes a method based on the Si-OH characteristic group existing in the aerogel precursor after electrospinning, and solves the key problems of high temperature and coating driving force of aerogel coating prepared by conventional vapor phase method through low-pressure and low-temperature vapor deposition. The prepared ultra-uniform fiber coating is conducive to mass industrial production and greatly improves the mechanical properties.

[0039] The present invention provides a method for preparing a modified fiber aerogel, comprising the following steps:

[0040] A) electrospinning the spinning solution with the aid of airflow to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor;

[0041] B) taking one or both of triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane to prepare a liquid silane aqueous solution;

[0042] C) by low temperature and low pressure vapor deposition method, liquid silane aqueous solution is deposited on the doped SiO2-ZrO2 nanofiber aerogel precursor to obtain modified fiber aerogel.

[0043] The preparation method of the modified fiber aerogel provided by the present invention firstly performs electrostatic spinning on a spinning solution with the assistance of airflow to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor.

[0044] The present invention utilizes a spinning precursor prepared from inexpensive silane, organic zirconic acid, and zirconium halide. Currently, tetraethyl orthosilicate (TES) is commonly used in aqueous solution at a certain ratio to prepare a silicon-containing spinning solution. However, if the ratio of TES to water changes, the TES can easily hydrolyze, causing the spinning solution to gel. Furthermore, the high price of TES increases the production cost of aerogel materials. Therefore, selecting an inexpensive organosilane with low hydrolysis capacity can effectively ensure the spinnability of the spinning solution and reduce aerogel production costs. The use of organic zirconium acid and zirconium halide is intended to improve the high-temperature resistance of the prepared fiber aerogel. Conventional nanofiber silica aerogel materials suffer from brittle fiber fracture due to the inability of silica grains to withstand excessively high temperatures. The introduction of zirconium dioxide can address this problem. By preparing a good spinning solution and using it through pneumatic electrostatic spinning, fluffy aerogel blocks can be produced.

[0045] The present invention first prepares a spinning solution.

[0046] According to the present invention, the method for preparing the spinning solution comprises:

[0047] S1) mixing zirconium acetate and ZrOCl2 8H2O to obtain a first solution;

[0048] S2) mixing triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane, and stirring to prepare a liquid silane aqueous solution;

[0049] S3) adding the liquid silane aqueous solution dropwise to the first solution, then adding polyethylene oxide, and then adjusting the pH value to obtain a spinning solution.

[0050] The spinning solution of the present invention is prepared by first mixing zirconium acetate and ZrOCl2 8H2O to obtain a first solution.

[0051] According to the present invention, the molar ratio of the zirconium acetate and ZrOCl2 8H2O is 1:1;

[0052] In the above-mentioned first solution, the Zr content is preferably 10-20wt%, specifically 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%.

[0053] The polymer fiber prepared by electrospinning the above mixture has a large amount of Si-OH groups, which are evenly distributed on the surface of the fiber. At the same time, the presence of the groups provides reaction sites for subsequent gas-phase reactions.

[0054] Triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane are mixed and stirred to prepare a liquid silane aqueous solution. The mixing of the present invention is magnetic stirring mixing, and the mixing time is preferably 3 to 7 minutes, more preferably 5 minutes.

[0055] According to the present invention, the molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is (0-0.5): (0.5-1);

[0056] Specifically, the molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is 0.5:0.5 or 0:1.

[0057] The liquid silane aqueous solution is added dropwise to the first solution at a rate of 2 mL / min. Preferably, the liquid silane aqueous solution is gradually added dropwise to the first solution in the three-necked flask at a rate of 2 ml / min using a dropping funnel at room temperature, and magnetically stirred for 1 hour.

[0058] Then, polyethylene oxide (PEO) having a molecular weight of 300,000 is added and stirred at room temperature for 4 to 6 hours, preferably 5 hours.

[0059] The mass ratio of the liquid silane aqueous solution to the polyethylene oxide is 100:0.5.

[0060] Then the pH value is adjusted to obtain a spinning solution. The pH value adjustment of the present invention is to adjust the pH value to 1-2.

[0061] The pH value adjustment of the present invention is to use nitric acid / hydrochloric acid / sulfuric acid to change the pH value of the spinning solution to 1-2, and finally prepare a colorless, clear, transparent and stable spinning solution (the spinning solution is left to stand for 12 hours).

[0062] The inventors have found that in order to better provide reaction sites with high reactivity, the pH value of the spinning solution is very important. The addition of acid enables Si-OH to better react with the gas to generate relevant coatings, thereby realizing the preparation of fiber aerogel coatings under low pressure and low temperature environment.

[0063] Si-Zr spinning solution was prepared using zirconium acetate and zirconium oxychloride as zirconium sources, and finally a nanofiber spinning solution was obtained which was water-based, had a simple preparation process, excellent stability and spinnability, and could arbitrarily control the Zr-Si molar ratio.

[0064] In the spinning solution provided by the present invention, the silicon-zirconium molar ratio of the spinning solution is preferably (0.1-1):1, specifically 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1 or 1:1.

[0065] After the spinning solution is prepared, the spinning solution is electrospun with the assistance of air flow to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor.

[0066] In the nanofiber aerogel and preparation method thereof provided by the present invention, the electrospinning is preferably carried out in an airflow-assisted electrospinning device; the receiver of the electrospinning device is preferably a drum receiver, and the rotation speed of the drum receiver is preferably 100-200 r / min, specifically 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min, 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min or 200 r / min; the airflow speed of the electrospinning is preferably 3-8 L / min, specifically 3 L / min, 3.5 L / min, 4 L / min, 4 .5L / min, 5L / min, 5.5L / min, 6L / min, 6.5L / min, 7L / min, 7.5L / min or 8L / min; the spinning needle used for the electrospinning is preferably a 23-gauge needle with an outer diameter of 1.5mm; the positive pressure of the electrospinning is preferably set to 15-25kV, specifically 15kV, 16kV, 17kV, 18kV, 19kV, 20kV, 21kV, 22kV, 23kV, 24kV or 25kV; the negative pressure of the electrospinning is preferably set to 1-10kV, specifically 1kV, 2kV, 3kV, 4kV, 5kV, 6kV, 7kV, 8kV, 9kV or 10kV.

[0067] In the nanofiber aerogel and preparation method thereof provided by the present invention, the temperature of the electrospinning is preferably 20-40°C, specifically 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C; the humidity of the electrospinning is preferably 20-40%, specifically 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.

[0068] Particularly preferably, the electrospinning parameters include:

[0069] The spinning temperature is 28-32°C, and the spinning humidity is 20%-40%; the spinning receiver is a drum receiver, and the rotation speed of the drum receiver is 140r / min; the spinning air flow speed is 5L / min, and the airflow-assisted spinning needle has an inner ring of No. 23 needle and an outer ring diameter of 1.5mm; the voltage is 20kV for positive pressure and 5kV for negative pressure.

[0070] The prepared fiber aerogel material is collected and placed in a spinning environment for storage and use.

[0071] Taking one or both of triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane to prepare a liquid silane aqueous solution;

[0072] According to the present invention, the molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is (0-0.5): (0.5-1);

[0073] Specifically, the molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is 0.5:0.5 or 0:1.

[0074] Particularly preferably, one or two of the triaminopropylmethyldiethoxysilanes are used to prepare a liquid silane aqueous solution.

[0075] Liquid silane is a commonly used surface modifier that can be evenly applied to the surface of the block. Most silanes have a low boiling point and a small saturated vapor pressure. Leveraging this characteristic, liquid silane is used as a gas source to deposit a layer of organosilane polymer film on the precursor nanofibers, achieving reinforcement of the inorganic nanofiber cross-nodes.

[0076] The prepared fiber aerogel material is appropriately sized and placed in a low-pressure oven.

[0077] In one embodiment of the present invention, the specifications of the fiber aerogel material are 80*40*20 mm.

[0078] The modified fiber aerogel is obtained by depositing an organic silane polymer film on a doped SiO2-ZrO2 nanofiber aerogel precursor using a low-temperature and low-pressure vapor deposition method.

[0079] The volume ratio of the doped SiO2-ZrO2 nanofiber aerogel precursor to the liquid silane aqueous solution is 50-100 cm 3 :3ml;

[0080] The temperature of the low-temperature, low-pressure vapor deposition method of the present invention is: 85-95°C, specifically 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C or 95°C;

[0081] The pressure of the low-pressure vapor deposition method of the present invention is 20,000 Pa to 30,000 Pa, specifically 20,000 Pa, 21,000 Pa, 22,000 Pa, 23,000 Pa, 24,000 Pa, 25,000 Pa, 26,000 Pa, 27,000 Pa, 28,000 Pa, 29,000 Pa, and 30,000 Pa;

[0082] The deposition time is 2 to 6 hours.

[0083] The thickness of the organosilane polymer film of the present invention is less than 5 nm, and in specific embodiments, it can be 2 nm, 3 nm, 4 nm or 5 nm.

[0084] The present invention provides a modified fiber aerogel, which is prepared by the preparation method described in any one of the above technical solutions. The present invention has already clearly described the above specific preparation method, which will not be repeated here.

[0085] This invention successfully deposits an organosilane polymer film on fiber aerogel using a low-cost, easy-to-use, and highly reproducible process. This technology improves the performance of existing fiber aerogels. Furthermore, the low-cost raw material used, silane, offers excellent economic applicability, broadening the application range of existing aerogel materials and enhancing their quality and efficiency.

[0086] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0087] The numerical ranges and parameters used in this disclosure are presented as precisely as possible to represent the relevant numerical values ​​of the specific embodiments. However, any numerical value inherently and inevitably contains standard deviations resulting from individual testing methods. Therefore, unless otherwise expressly stated, it should be understood that all numerical ranges or specific data used in this disclosure are subject to reasonable deviation within a certain range, for example, within 1% or 0.5%.

[0088] Some cases are described in the embodiments and comparative examples of the present invention, wherein the embodiments illustrate certain implementations of the present invention. However, this does not mean that the effects of the present invention can only be achieved in these cases.

[0089] In order to further illustrate the present invention, a modified fiber aerogel and a preparation method thereof provided by the present invention are described in detail below with reference to examples.

[0090] Example 1

[0091] (1) Preparation of nanofiber spinning solution:

[0092] (1) Solution A: Place 100 g of zirconium acetate (Zr(CH3COO)4, Zr, 15-16 wt%) in a three-necked flask, mix zirconium acetate and zirconium oxychloride (zirconium oxychloride, octahydrate (ZrOCl2 8H2O, AR, 99%)) in a molar ratio of 1:1, and allow the solution to settle.

[0093] (2) Solution B: Place APTES and APMDES (3-aminopropyltriethoxysilane) in a molar ratio of 1:1 in a beaker and stir magnetically for 5 minutes;

[0094] (3) Using a dropping funnel, gradually add solution B into solution A in the three-necked flask at room temperature at a rate of 2 ml / min and stir magnetically for 1 h.

[0095] (4) After the addition of liquid B is completed, 0.5 g of PEO (300,000 molecular weight) is added, and stirring is continued at room temperature for 5 h. 4 mL of concentrated hydrochloric acid is added to finally prepare a colorless, clear, transparent, and stable spinning solution (the spinning solution is allowed to stand for 12 h).

[0096] (2) The prepared spinning solution is spun using an airflow-assisted electrospinning device to obtain a doped SiO2-ZrO2 nanofiber precursor, and the parameters are set as follows:

[0097] (1) Process control parameters

[0098] Receiver: drum receiver, speed 140r / min;

[0099] Air flow rate: 5L / min

[0100] Airflow-assisted spinning needle: inner ring 23-gauge needle, outer ring diameter 1.5mm;

[0101] Voltage: positive voltage 20kV, negative voltage: 5kV;

[0102] (2) Environmental parameters

[0103] Temperature control: The temperature is set to 30±2℃ through the temperature control system of the electrospinning machine. Humidity control: The humidity parameters in the electrospinning machine are regulated by the humidification and dehumidification system: 20%, 30%, 35%, 40%.

[0104] The prepared fiber aerogel material is collected and placed in a spinning environment for storage and use.

[0105] Liquid silane is a commonly used surface modifier that can be evenly applied to the surface of the block. Most silanes have a low boiling point and a small saturated vapor pressure. Leveraging this characteristic, liquid silane is used as a gas source to deposit a layer of organosilane polymer film on the precursor nanofibers, achieving reinforcement of the inorganic nanofiber cross-nodes.

[0106] (3) Deposition of organosilane polymer film

[0107] ① Take the prepared fiber aerogel material of 80*40*20mm and place it in a low-pressure high-temperature oven;

[0108] ② Place a mixture of triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane in a molar ratio of 0.5:0.5 in a small beaker;

[0109] ③Then place the beaker containing liquid silane into a high-temperature oven containing nanofiber aerogel at 90°C and an absolute pressure of 0.02 MPa.

[0110] ④ Place it in an oven and set the oven temperature to high. Process for 6 hours.

[0111] ⑤ Place the deposited fiber aerogel in a muffle furnace, heat it to 1000℃ at 10℃ / min, and keep it warm for 1h.

[0112] Example 2

[0113] Referring to the spinning solution and nanofiber aerogel preparation process in Example 1, the high temperature treatment time in step ④ in (III) was changed to 2 h, and the other steps remained consistent with Example 1.

[0114] Comparative Example 1

[0115] Referring to the spinning solution and nanofiber aerogel preparation process in Example 1, the fiber aerogel precursor obtained by spinning was placed in a muffle furnace, heated to 1000° C. at a rate of 10° C. / min, and kept warm for 1 hour to obtain an undeposited fiber aerogel sample.

[0116] The undeposited sample (Comparative Example 1) and the deposited silane polymer film sample (Example 1) were observed and analyzed using a transmission electron microscope. The fiber aerogel material was compared before and after deposition. Figure 1 As shown in a, the cross-node positions of the nanofibers in the deposited organosilane polymer film sample were obviously cross-linked. This indicates that during the deposition process, APMDES successfully adsorbed on the surface of the fiber precursor and reacted with the precursor surface. High-resolution transmission electron microscopy revealed that ( Figure 1 b, c) An amorphous coating approximately 4 nm thick forms on the surface of the nanofibers of the deposited organosilane polymer film sample. Comparison reveals that the APMDES deposition thickness at the nanofiber intersections is significantly higher than at non-intersections. This is because, theoretically, fiber intersections are point contacts, resulting in a concave surface with a curvature approaching infinity. Non-intersections, on the other hand, are convex, and the nanofiber radius is small, resulting in a large curvature. Therefore, the adsorption rate of APMDES at intersections is higher than at non-intersections.

[0117] Figure 1 (a) TEM image of the cross-node position of the deposited organic silane polymer film sample; (b), (c) high-resolution TEM images of the surface of the undeposited sample and the deposited sample; (d), (e) EDS electron images of the undeposited sample and the deposited sample. Figure 1 d, e) show that the distribution of Si and Zr elements on the surface is still uniform before and after modification.

[0118] Figure 2 This is a thermal conductivity test diagram, gray corresponds to comparative example 1, and red corresponds to example 1. The thermal conductivity was measured using a hot-disk, and the results showed that the thermal conductivity of the sample not coated with a film (comparative example 1) was higher than that of the sample coated with a film (experimental example 1).

[0119] Figure 3 Energy loss and cyclic performance test of reinforced nanofiber aerogel (Experimental Example 1): (a) energy loss under different compression strains; (b) 250 compression cycle curves of nanofibers.

[0120] By integrating the area of ​​the compression-rebound curve, the total energy consumption per unit volume of nanofiber aerogel under the compression-rebound condition can be obtained in kJ / m 3, which is the energy loss of the material, also known as the unit damping energy of the material. After the aerogel is subjected to 5 compression-rebound cycles, the energy loss of the aerogel corresponding to the cycle is obtained by integrating the different strain cycle curves. The energy loss corresponding to the compression strain of 50%, 60%, 70%, and 80% is 0.46kJ / m 3 , 0.82kJ / m 3 , 1.58kJ / m 3 and 3.16 kJ / m 3 ,observe Figure 3 As shown in the thumbnail in a, the energy loss of the reinforced nanofiber aerogel increases exponentially with the maximum compressive strain within the strain range of 50% to 80%. The reinforced nanofiber aerogel was then subjected to a 250-cycle compression performance test at a strain of 60%. Figure 3 b) The compression-rebound curves show a high degree of overlap, with the maximum compressive stress after the test decreasing by only 1 kPa relative to the maximum compressive stress before the test. This suggests that the aerogel is suitable for use in environments with frequent vibrations.

[0121] Figure 4 Figures 1 and 2 show contact angle measurements of fiber aerogels, (a) Comparative Example 1; (b) Example 1. Contact angle measurements revealed that the untreated fiber aerogel, as shown in Figure (a), exhibited minimal hydrophobicity. As shown in Figure (b), the vapor-deposited reinforced fiber aerogel exhibited excellent hydrophobicity (up to 136°), demonstrating that the presence of the ultrathin layer imparts hydrophobic properties to the fiber aerogel.

[0122] Figure 5 The thermal expansion coefficient test diagram of the fiber aerogel is shown in Figure 1, with the black line corresponding to Example 1 and the red line corresponding to Example 1. The thermal expansion coefficient test shows that when the temperature rises from 25°C to 400°C, the untreated fiber aerogel exhibits a thermal expansion of up to 50 μm, while the vapor-deposited reinforced fiber aerogel expands only less than 7 μm, proving that the presence of the ultra-thin layer reduces the thermal expansion of the fiber aerogel.

[0123] Figure 6 is a schematic diagram of the synthesis process, Figure 6 It can be seen that the silane solution forms organic gas by evaporation and reacts with the hydroxyl groups on the fiber surface under low pressure to generate a chain structure and form an amorphous layer of SiO2 and ZrO2 at a certain temperature.

[0124] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing modified fiber aerogel, characterized in that: The steps include: A) electrospinning the spinning solution with the aid of airflow to obtain a doped SiO2-ZrO2 nanofiber aerogel precursor; B) taking one or both of triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane to prepare a liquid silane aqueous solution; C) by low temperature and low pressure vapor deposition method, liquid silane aqueous solution is deposited on the doped SiO2-ZrO2 nanofiber aerogel precursor to obtain modified fiber aerogel.

2. The preparation method according to claim 1, characterized in that The temperature of the low-temperature and low-pressure vapor deposition method is 85 to 95° C., the pressure is 20,000 Pa to 30,000 Pa, and the deposition time is 4 to 6 hours.

3. The preparation method according to claim 1, characterized in that The molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is (0-0.5): (0.5-1).

4. The preparation method according to claim 3, characterized in that The volume ratio of the doped SiO2-ZrO2 nanofiber aerogel precursor to the liquid silane aqueous solution is 50-100 cm 3 :3ml; The thickness of the organosilane polymer film is less than 5 nm.

5. The preparation method according to claim 1, characterized in that The electrospinning parameters of step A) include: The spinning temperature is 20-40°C, the spinning humidity is 20%-40%; the spinning receiver is a drum receiver, and the rotation speed of the drum receiver is 100-200 r / min; the spinning air flow speed is 3-8 L / min, the airflow-assisted spinning needle has an inner ring of No. 23 needle and an outer ring diameter of 1.5 mm; the voltage is 15-25 kV for positive pressure and 1-10 kV for negative pressure.

6. The preparation method according to claim 1, characterized in that The preparation method of the spinning solution comprises: S1) mixing zirconium acetate and ZrOCl2 8H2O to obtain a first solution; S2) mixing triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane, and stirring to prepare a liquid silane aqueous solution; S3) adding the liquid silane aqueous solution dropwise to the first solution, then adding polyethylene oxide, and then adjusting the pH value to obtain a spinning solution.

7. The preparation method according to claim 6, characterized in that The pH value is adjusted to 1-2.

8. The preparation method according to claim 1, characterized in that The molar ratio of zirconium acetate and ZrOCl28H2O is 1:1; The molar ratio of the triaminopropyltriethylsilane and triaminopropylmethyldiethoxysilane is (0-0.5): (0.5-1).

9. The preparation method according to claim 1, characterized in that The speed of adding the S3) dropwise is 2 mL / min; the molecular weight of the polyethylene oxide is 300,000.

10. A modified fiber aerogel, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 9.

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