Surface-bridged cross-connection network silicon dioxide aerogel and preparation method thereof
By forming a surface-bridging network in silica fiber aerogel, the problems of insufficient mechanical properties and poor thermal insulation performance in extreme thermal insulation environments are solved, and an aerogel material with high strength and excellent thermal insulation performance is realized.
Patent Information
- Application Number
- CN202510959258.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-10-17
AI Technical Summary
Existing silica fiber aerogels have insufficient mechanical properties and poor thermal insulation properties in extreme thermal insulation environments, and their structures are prone to collapse, especially under high temperature and heavy mechanical loads.
By adopting a surface-bridged cross-linking network structure, uniform two-dimensional nanosheets are grown within the nanofiber framework to form stable cross-linking points, enhance fiber connections, eliminate interfacial incompatibility, and form a high-strength thermal insulation material.
It achieves a combination of high mechanical strength and excellent thermal insulation performance in extreme environments, with a compressive strength of 800 kPa, a tensile strength of 120 kPa, a flexural strength of 390.8 kPa, and a thermal conductivity as low as 0.028 W m-1K-1, making it suitable for high and low temperature environments.
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Figure CN120794562A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of thermal insulation materials, in particular to a face-bridging interlinked network silica aerogel and a preparation method thereof. BACKGROUND
[0002] Silica fiber aerogels use flexible nanofibers with high strength and high modulus as the basic unit of three-dimensional aerogels, overcoming the poor mechanical properties of traditional silica aerogels. Compared with conventional silica aerogels, the mechanical properties are improved, which significantly expands the thermal insulation application of silica fiber aerogels. However, in extreme thermal insulation environments, such as high temperature (>1000°C) and large mechanical load in the field of marine and aviation, in order to prevent structural collapse, the connection between the basic nanofiber units of the silica fiber aerogel needs to be further strengthened to ensure reliable structural stability and excellent thermal insulation performance.
[0003] At present, one of the most common methods to enhance the strength of silica fiber aerogels is to limit the slippage of fibers through node crosslinking. However, this point-to-point crosslinking has a small crosslinking contact area, which causes the fibers to easily deform under large strain or compression, resulting in stress concentration at the fibers and their connections, leading to large plastic deformation and eventual structural failure of the aerogel. And the "point crosslinking" silica fiber aerogel made of one-dimensional fibers contains randomly distributed macroscopic pores, which are usually on the scale of tens of microns, which reduces its thermal insulation performance compared with conventional silica nanoparticle aerogels. Therefore, there is an urgent need for a high-strength aerogel that matches the thermal insulation performance of conventional silica nanoparticle aerogels. SUMMARY
[0004] Based on this, the purpose of the present application is to provide a face-bridging interlinked network silica aerogel and a preparation method thereof, which has high mechanical strength and also guarantees excellent thermal insulation performance.
[0005] To achieve the above purpose, the present application adopts the following technical solutions: The present application first provides a preparation method of a face-bridging interlinked network silica aerogel, which comprises the following steps: S1. Mixing a polyvinyl butyral ester solution and a silicon source solution to obtain a spinning precursor solution, spinning the spinning precursor solution, and calcining to obtain a silica nanofiber membrane; S2. Mixing methyltrimethoxysilane, ultrapure water, acetic acid, urea, and cetyltrimethylammonium chloride to obtain a clear and transparent gel solution; S3. The silica nanofiber membrane is stacked and immersed in the gel solution, and is incubated and reacted to obtain a hydrogel; after the reaction is completed, the hydrogel is subjected to solvent replacement, drying, and calcination to obtain a face-bridging interconnected network silica aerogel.
[0006] As a further improvement of the above-mentioned scheme of the present application, in step S1, the silicon source solution is obtained by mixing tetraethyl orthosilicate, ultrapure water, ethanol and anhydrous oxalic acid, and the mass ratio of tetraethyl orthosilicate, ultrapure water, ethanol and anhydrous oxalic acid is 20-21:5-7:3-4:0.1-0.2. Since a stable solution needs to be formed during spinning to ensure the stability of the solution during spinning, the present application hydrolyzes and condenses tetraethyl orthosilicate under acidic conditions to form a stable long-chain structure, ensuring the stability of the solution during spinning; at the same time, the solution after hydrolysis has better fluidity and viscosity, which helps to form uniform fibers.
[0007] As a further improvement of the above-mentioned scheme of the present application, in step S1, the mass ratio of the polyvinyl butyral ester solution to the silicon source solution is 1:1. The present application optimizes the yield and performance of the final silica fiber by adjusting the ratio of the polyvinyl butyral ester solution and the silicon source solution; the polyvinyl butyral ester solution is obtained by dissolving polyvinyl butyral ester in anhydrous ethanol.
[0008] As a further improvement of the above-mentioned scheme of the present application, in step S1, the spinning is performed on the spinning precursor solution by using electrospinning technology; by using electrospinning technology, the jet overcomes the capillary force and is stretched under the action of a high-voltage electric field, and finally forms continuous nanofibers. Preferably, the voltage used in the electrospinning technology is 15-20 KV; under the action of high voltage, the spinning precursor solution forms a conical "Taylor cone" at the needle tip, and then is sprayed from the spinneret, undergoes straight-line motion and spiral swinging, and is further stretched and refined to form nanofibers.
[0009] As a further improvement of the above-mentioned scheme of the present application, in step S1, the calcination is performed at 800-1000℃ for 1-2 h. The purpose of calcination is to remove organic matter by high-temperature treatment to obtain silica fibers.
[0010] As a further improvement of the above-mentioned scheme of the present application, in step S2, the mass ratio of methyltrimethoxysilane, ultrapure water, acetic acid, urea and cetyltrimethylammonium chloride is 0.5-2.5:10-20:0.001-0.006:2-8:0.5-1.
[0011] As a further improvement of the above-mentioned scheme of the present application, in step S3, the silica nanofiber membrane is stacked and then immersed in the gel solution for 30-60 min; and the heat preservation reaction is carried out in a closed container at 120-180 DEG C for 4-24 h.
[0012] As a further improvement of the above-mentioned scheme of the present application, in step S3, the solvent replacement is to immerse the hydrogel in an ethanol solution. In order to overcome the surface tension to prevent the structure from collapsing, the solvent replacement is carried out to replace the ethanol solution with a smaller surface tension, and the structure is kept stable by drying under normal pressure.
[0013] As a further improvement of the above-mentioned scheme of the present application, in step S3, the drying is carried out at 60-80 DEG C for 6-12 h, and the calcination is carried out at 800-1000 DEG C for 1-2 h.
[0014] The present application also provides a face-bridging interpenetrating network silica aerogel prepared by the above-mentioned preparation method.
[0015] Compared with the prior art, the present application has the following beneficial effects: The present application grows uniform two-dimensional nanosheets in the partial cavities formed by the nanofiber framework through in-situ polycondensation, forms a face-bridging interpenetrating network between the silica fibers, effectively eliminates the interface incompatibility effect, and obtains stable crosslinking sites; due to the formation of the face-bridging structure, the fiber slip is inhibited, and the aerogel exhibits high mechanical strength; the face-bridging interpenetrating network silica aerogel prepared by the present application exhibits a compression strength as high as 800 kPa at 80% deformation, excellent tensile strength of 120 kPa, and excellent bending strength of 390.8 kPa.
[0016] The face-bridging structure of the present application can effectively alleviate the stress concentration under external force, reduce plastic deformation, and exhibit better structural stability; at the same time, the formation of the two-dimensional nanosheets establishes a two-dimensional physical heat conduction barrier as a face-bridging connector, effectively inhibits the heat flow in the fiber network, and exhibits excellent heat insulation performance. The synergistic effect of mechanical and thermal performance makes the face-bridging interpenetrating network silica aerogel of the present application be able to be used as a heat insulation material in an extreme heat insulation environment. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 A preparation principle diagram of the face-bridging interpenetrating network silica aerogel of the present application; Figure 2 A SEM image of the silica nanofiber membrane prepared in step S3 of Example 1; Figure 3 A SEM image of the face-bridging interpenetrating network silica aerogel prepared in Example 1; Figure 4 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1; Figure 5 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1; Figure 6 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1; Figure 7 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1; Figure 8 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1 under 200g weight compression for 24h; Figure 9 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1 under 200g weight compression for 24h; Figure 10 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1 under 200g weight compression for 24h; Figure 11 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1 under 200g weight compression for 24h; Figure 12 Photograph of face-bridged interpenetrating network silica aerogel made for Example 1 under 200g weight compression for 24h; Figure 13 SEM image of silica nanofiber membrane made for Example 2 Step S3; Figure 14 SEM image of face-bridged interpenetrating network silica aerogel made for Example 2; Figure 15 Photograph of face-bridged interpenetrating network silica aerogel made for Example 2; Figure 16 Photograph of face-bridged interpenetrating network silica aerogel made for Example 2; Figure 17 Photograph of face-bridged interpenetrating network silica aerogel made for Example 2; DETAILED DESCRIPTION
[0018] In order to facilitate the understanding of the present application, a more comprehensive description of the present application will be provided below in conjunction with specific examples. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.
[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.
[0020] The present application provides a preparation method of face-bridging interpenetrating network silica aerogel, comprising the following steps: S1. mixing a polyvinyl butyral ester solution with a silicon source solution to obtain a spinning precursor solution, spinning the spinning precursor solution, and calcining to obtain a silica nanofiber membrane; S2. mixing methyltrimethoxysilane, ultrapure water, acetic acid, urea, and cetyltrimethylammonium chloride to obtain a clear and transparent gel solution; S3. laminating the silica nanofiber membrane and then immersing it in the gel solution, incubating and reacting to obtain a hydrogel; after the reaction is completed, the hydrogel is subjected to solvent replacement, drying, and calcining to obtain a face-bridging interpenetrating network silica aerogel.
[0021] Figure 1 The preparation principle of the face-bridging interpenetrating network silica aerogel is as follows: uniform two-dimensional nanosheets are grown in the partial cavities formed by the nanofiber framework through in-situ polycondensation, a face-bridging network is formed between the silica fibers, the interface incompatibility effect is effectively eliminated, and stable crosslinking sites are obtained.
[0022] The present application will be further described below in conjunction with specific examples.
[0023] Example 1 The present example provides a face-bridging interpenetrating network silica aerogel, and a preparation method thereof comprises the following steps: S1. preparation of silica sol: mixing tetraethyl orthosilicate, ultrapure water, ethanol, and anhydrous oxalic acid in a mass ratio of 20.833:6.426:3.27:0.144, stirring at room temperature for 8 h to obtain silica sol; S2. preparation of polymer solution: dissolving polyvinyl butyral ester in an ethanol solution, stirring at room temperature for 8 h to obtain a polymer solution (wherein the mass fraction of polyvinyl butyral ester is 15wt%); S3. Preparation of the silica nanofiber membrane: the polymer solution and the silica sol were mixed in a mass ratio of 1:1, and stirred thoroughly for 4 h to obtain a spinning precursor solution; then the spinning precursor solution was spun using the electrospinning technology at 20 KV, with an injection speed of 1 ml / h, a receiving distance of 20 cm, and a receiving speed of 140 r / min, to obtain a silica fiber membrane; finally, the silica fiber membrane was calcined in an air atmosphere: the temperature was raised to 800°C at a rate of 5°C / min and calcined at 800°C for 2 h, to finally obtain a silica nanofiber membrane; S4. Preparation of the face-bridging network: methyltrimethoxysilane, ultrapure water, acetic acid, urea, and cetyltrimethylammonium chloride were mixed in a mass ratio of 1.096:15:0.0045:5:0.8, stirred for 30 min, to obtain a clear and transparent gel solution; the silica fiber membrane was stacked layer by layer and immersed in the gel solution to absorb sufficiently for 30 min, and then placed in a closed container to react at 180°C for 12 h; after the reaction, solvent exchange was performed in an ethanol solution, and finally dried in an oven at 80°C for 12 h, to obtain a face-bridging network aerogel; S5. Preparation of the face-bridging network silica aerogel: the face-bridging network aerogel was calcined at 800°C for 2 h in an air atmosphere, to obtain a face-bridging network silica aerogel.
[0024] Figure 2 The SEM image of the silica nanofiber membrane prepared in step S3 of Example 1 is shown in FIG. 1. Figure 2 As can be seen, the surface of the silica nanofiber membrane is smooth, and has a disordered intercrossing structure, with a fiber diameter of about 900 nm.
[0025] Figure 3 The SEM image of the face-bridging network silica aerogel prepared in Example 1 is shown in FIG. 2. Figure 3 As can be seen, a face-bridging network is generated inside the fiber framework.
[0026] Figure 4 The actual image of the face-bridging network silica aerogel prepared in Example 1 placed on a leaf is shown in FIG. 3. Figure 4 As can be seen, the face-bridging network silica aerogel prepared in Example 1 exhibits the characteristic of light weight.
[0027] I. Mechanical performance test of the face-bridging network silica aerogel prepared in Example 1: (1) Compression strength test of the face-bridging network silica aerogel prepared in Example 1: a universal testing machine was used to test the compression of the aerogel at 20%, 40%, 60%, and 80% strain, with a compression rate of 5 mm min-1 ; the compressive strength curve as shown in Figure 5 , from which it can be seen that the face-bridged network silica aerogel prepared in Example 1 exhibits a compressive strength of up to 800 kPa at 80% deformation. Figure 5
[0028] (2) The face-bridged network silica aerogel prepared in Example 1 was subjected to tensile test: the tensile properties of the aerogel were tested using a universal testing machine, and the tensile rate was 5 mm min -1 ; the tensile strength curve as shown in Figure 6 , from which it can be seen that the face-bridged network silica aerogel prepared in Example 1 has excellent tensile strength of 120 kPa. Figure 6
[0029] (3) The face-bridged network silica aerogel prepared in Example 1 was subjected to bending strength test: the bending properties of the aerogel were tested using a universal testing machine, and the bending rate was 5 mm min -1 , and the bending test interval was 3 cm; the bending strength curve as shown in Figure 7 , from which it can be seen that the face-bridged network silica aerogel prepared in Example 1 has excellent bending strength of 390.8 kPa. Figure 7
[0030] (4) The face-bridged network silica aerogel prepared in Example 1 was subjected to compressive strength test: the aerogel with a height of 1 cm was compressed under a 200 g weight, and the weight was removed after 24 h of compression to test the change in the height of the aerogel; the result shows that the face-bridged network silica aerogel prepared in Example 1 can support a weight of more than 10,000 times its own weight. Figure 8
[0031] (5) The face-bridged network silica aerogel prepared in Example 1 was subjected to tensile test as shown in Figure 9 : 0.1 g of the aerogel was stretched by a 200 g weight, and the tensile condition was determined according to the breaking condition of the aerogel; the result shows that the face-bridged network silica aerogel prepared in Example 1 can be stretched by a weight of more than 2,000 times its own weight without breaking.
[0032] The above test results show that the face-bridged network silica aerogel prepared in Example 1 has excellent mechanical strength.
[0033] II. The face-bridged network silica aerogel prepared in Example 1 was subjected to thermal insulation performance test: the thermal conductivity of the aerogel was tested by Hot-disk method, and the corresponding thermal conductivity was tested at different temperature points during the temperature rising process.
[0034] The results show that the face-bridged interpenetrating network silica aerogel prepared in Example 1 exhibits extremely low thermal conductivity of 0.028 W m -1 K -1 at room temperature, and the thermal conductivity increases with the increase of temperature, and the thermal conductivity at 1000℃ is 0.156 W m -1 K -1 Figure 10 ); at the same time, it can be observed that the face-bridged interpenetrating network silica aerogel prepared in this example can restore its original shape after being compressed several times under the butane torch (~1300℃), and the structure is not broken, which exhibits excellent high-temperature stability ( Figure 11 ). In addition, the face-bridged interpenetrating network silica aerogel prepared in Example 1 can restore its original shape after being compressed several times in liquid nitrogen, and the structure is not broken, which has excellent low-temperature structural stability ( Figure 12 ).
[0035] Example 2 This embodiment proposes a face-bridged interpenetrating network silica aerogel, and the preparation method thereof comprises the following steps: S1. Preparation of silica sol: mixing tetraethyl orthosilicate, ultrapure water, ethanol and anhydrous oxalic acid according to the mass ratio of 20.833:6.426:3.27:0.144, stirring at room temperature for 8 h to obtain silica sol; S2. Preparation of polymer solution: dissolving polyvinyl butyral ester in ethanol solution, stirring at room temperature for 8 h to obtain a polymer solution (wherein the mass fraction of polyvinyl butyral ester is 15wt%); S3. Preparation of silica nanofiber membrane: mixing the polymer solution and the silica sol according to the mass ratio of 1:1, fully stirring for 4 h to obtain a spinning precursor solution; then using the electrospinning technology to spin the spinning precursor solution at 20 KV, the injection speed is 1 ml / h, the receiving distance is 20 cm, and the receiver rotating speed is 140 r / min, to obtain a silica fiber membrane; finally, the silica fiber membrane is calcined in air atmosphere: heating at a rate of 5℃ / min to 800℃ and calcining at 800℃ for 2 h, to finally obtain a silica nanofiber membrane; S4. Preparation of face-bridged junction network: methyltrimethoxysilane, ultrapure water, acetic acid, urea and cetyltrimethylammonium chloride were mixed according to the mass ratio of 0.533:15:0.0045:5:0.8, stirred for 30 min to obtain a clear and transparent gel solution; the silica nanofiber membrane was stacked layer by layer and immersed in the gel solution for sufficient absorption for 30 min, and then placed in a closed container for reaction at 180°C for 12h, after reaction, solvent exchange was carried out in an ethanol solution, and finally dried in an oven at 80°C for 12h to obtain a face-bridged junction network aerogel; S5. Preparation of face-bridged junction network silica aerogel: the face-bridged junction network aerogel was calcined at 800°C for 2h under air atmosphere to obtain a face-bridged junction network silica aerogel.
[0036] Figure 13 SEM image of the silica nanofiber membrane prepared in step S3 of Example 2, from Figure 1 It can be seen that the surface of the silica nanofiber membrane is smooth and has a disordered intercrossing structure, and the fiber diameter is about 900 nm.
[0037] Figure 14 SEM image of the face-bridged junction network silica aerogel prepared in Example 2, from Figure 2 It can be seen that a small amount of face-bridged network is generated inside the fiber framework.
[0038] I. Mechanical property test of the face-bridged junction network silica aerogel prepared in Example 2: (1) Compression strength test of the face-bridged junction network silica aerogel prepared in Example 2: the compression of the aerogel at 20%, 40%, 60% and 80% strain was tested using a universal testing machine, and the compression rate was 5 mm min -1 ; the compression strength curve is shown in Figure 15 , from Figure 15 it can be seen that the face-bridged junction network silica aerogel prepared in Example 2 has a compression strength of up to 250 kPa at 80% deformation.
[0039] (2) Tensile test of the face-bridged junction network silica aerogel prepared in Example 2: the tensile properties of the aerogel were tested using a universal testing machine, and the tensile rate was 5 mm min -1 ; the tensile strength curve is shown in Figure 16 , from Figure 16 it can be seen that the face-bridged junction network silica aerogel prepared in Example 2 has excellent tensile strength of 120 kPa.
[0040] The above test results show that the face-bridged interlocking network silica aerogel prepared in Example 2 has excellent mechanical strength.
[0041] II. The face-bridged interlocking network silica aerogel prepared in Example 2 was subjected to thermal insulation performance test: the thermal conductivity of the aerogel was tested by using Hot-disk method, and the corresponding thermal conductivity was tested at different temperature points in the process of temperature rise, and the results are shown in Figure 17
[0042] Figure 17 The results show that the face-bridged interlocking network silica aerogel prepared in Example 2 exhibits extremely low thermal conductivity of 0.029 W m -1 K -1 at room temperature.
[0043] The technical features of the above-described embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the description.
[0044] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.
Claims
1. A method for preparing a surface-bridged interlocking network silica aerogel, characterized in that: It includes the following steps: S1. The polyvinyl butyral ester solution is mixed with a silicon source solution to obtain a spinning precursor solution, the spinning precursor solution is spun, and calcined to obtain a silica nanofiber membrane; S2. Methyltrimethoxysilane, ultrapure water, acetic acid, urea, and hexadecyltrimethylammonium chloride were mixed to obtain a gel solution; S3. The silica nanofiber membranes are stacked and immersed in the gel solution, and the mixture is kept warm for reaction to obtain a hydrogel; after the reaction is completed, the hydrogel is subjected to solvent replacement, drying, and calcination to obtain a surface-bridged cross-linked network silica aerogel.
2. The method for preparing the surface-bridged cross-linked network silica aerogel according to claim 1, characterized in that: In step S1, the silicon source solution is obtained by mixing tetraethyl orthosilicate, ultrapure water, ethanol and anhydrous oxalic acid, and the mass ratio of tetraethyl orthosilicate, ultrapure water, ethanol and anhydrous oxalic acid is 20-21:5-7:3-4:0.1-0.
2.
3. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S1, the mass ratio of the polyvinyl butyral solution to the silicon source solution is 1:
1.
4. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S1, the spinning is performed on the spinning precursor solution using an electrospinning technique, and the voltage used in the electrospinning technique is 15-20 KV.
5. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S1, the calcination is carried out at 800-1000° C. for 1-2 hours.
6. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S2, the mass ratio of methyltrimethoxysilane, ultrapure water, acetic acid, urea, and hexadecyltrimethylammonium chloride is 0.5-2.5:10-20:0.001-0.006:2-8:0.5-1.
7. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S3, after the silica nanofiber membranes are stacked, they are immersed in the gel solution for 30-60 minutes; the heat preservation reaction is carried out in a sealed container at 120-180° C. for 4-24 hours.
8. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S3, the solvent exchange is to soak the hydrogel in an ethanol solution.
9. The method for preparing the surface-bridged interlocking network silica aerogel according to claim 1, characterized in that: In step S3, the drying is carried out at 60-80°C for 6-12 hours, and the calcination is carried out at 800-1000°C for 1-2 hours.
10. A surface-bridged interlocking network silica aerogel, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.