A multi-walled carbon nanotube-wrapped hybrid skeleton wave-absorbing aerogel and a preparation method thereof
By using a hybrid framework absorbing aerogel encapsulated by multi-walled carbon nanotubes, the problems of poor mechanical properties and low wave absorption performance of aerogels are solved, achieving efficient electromagnetic wave absorption and hydrophobic stability, reducing production costs, and making it suitable for energy-saving applications.
Patent Information
- Application Number
- CN202411601236.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2026-03-03
- Estimated Expiration
- 2044-11-11
AI Technical Summary
Existing aerogels have poor mechanical properties, low wave absorption performance, unstable hydrophobic properties, and high production costs, making it difficult to achieve mass production and limiting their application in the field of energy conservation.
A hybrid framework absorbing aerogel with multi-walled carbon nanotubes was formed by mixing MXene dispersion with aramid nanofiber gel and freeze-drying process to form a titanium carbide/aramid nanofiber hybrid structure with multi-walled carbon nanotubes. The three-dimensional network structure of the aerogel was maintained by freeze-drying technology.
It improves the mechanical properties and electromagnetic wave absorption capacity of aerogels, enhances hydrophobic stability, reduces production costs, adapts to a wider range of temperature and humidity conditions, and achieves efficient electromagnetic wave absorption and attenuation.
Smart Images
Figure CN119350701B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the cross-disciplinary field of porous materials and polymers, specifically to a hybrid framework microwave absorbing aerogel encapsulated by multi-walled carbon nanotubes and its preparation method. Background Technology
[0002] Aerogel is a solid material with a nanoporous network structure filled with a gaseous dispersion medium. Considered the lightest solid in the world, it is sometimes called "condensed smoke." First invented in the 1930s, it has been a hot research topic for nearly ninety years. Due to its extremely light weight, high-efficiency thermal insulation performance, and nanoporous network structure, it exhibits excellent physical properties in acoustics, optics, electricity, and mechanics. Furthermore, its unique thermal insulation principle and diverse material types have led to its widespread application in various fields. With technological advancements and the promotion of dual-carbon policies, energy conservation has become the main theme for the future development of the chemical, energy, and construction industries. As a highly efficient energy-saving thermal insulation material, the industry demand for aerogel is expected to increase rapidly. Aerogel outperforms traditional insulation materials in terms of thermal insulation, service life, waterproofing, and flame retardancy, demonstrating enormous application potential.
[0003] Currently, the mainstream aerogel is silica aerogel, which has good thermal insulation and adsorption properties. Its preparation process combines the sol-gel method with supercritical drying. However, it has problems such as poor mechanical properties, low wave absorption performance, unstable hydrophobic properties, high requirements for production equipment, high cost, and difficulty in mass production, which limit the sustainable development and application of aerogel in the future. Summary of the Invention
[0004] To address the problems in the prior art, this invention provides a hybrid framework microwave absorbing aerogel encapsulated by multi-walled carbon nanotubes and its preparation method.
[0005] This invention is achieved through the following technical solution:
[0006] A hybrid framework microwave-absorbing aerogel encapsulated in multi-walled carbon nanotubes includes the following steps:
[0007] S1, Ti3AlC2, lithium fluoride and hydrochloric acid were stirred and centrifuged in a ratio of (2-3) g: (3-4) g: (50-60) mL to prepare MXene dispersion;
[0008] S2, mix 5-10 mL of MXene dispersion with 50-60 g of aramid nanofiber gel to obtain a mixed gel;
[0009] S3, the mixed gel is molded into a thin layer gel, first frozen, then freeze-dried to obtain an aerogel;
[0010] S4. The aerogel is impregnated in a carbon nanotube dispersion, then frozen a second time, and then freeze-dried a second time to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0011] Preferably, in S1, stirring is carried out in an oil bath at 45~50℃ for 40~48 hours; hydrochloric acid is added 5 hours before the end of the stirring process.
[0012] Preferably, in step S1, after stirring, the mixture is centrifuged multiple times with increasing centrifugal speed to obtain an MXene dispersion.
[0013] Preferably, in S2, the aramid nanofiber gel is prepared by the following method: the ratio of alkaline solution, dimethyl sulfoxide and para-aramid nanofiber is (2-3) mL: (500-600) mL: (1-2) g, and the reaction is carried out at a stirring speed of (400-8000) r / min for 8-10 h.
[0014] Preferably, in S3, the thickness of the thin gel layer is 2~5mm.
[0015] Preferably, in S3, the temperature during the first freezing is -60 to 62°C, and the time is 10 to 12 hours.
[0016] Preferably, in S3, the temperature during the first freeze-drying is -50 to 59 °C and the time is 24 to 48 hours.
[0017] Preferably, in S4, the temperature during the second freezing is -60 to 62°C, and the time is 10 to 12 hours.
[0018] Preferably, in S4, the temperature during the second freeze-drying is -50 to 59 °C and the time is 12 to 24 hours.
[0019] A product obtained from a hybrid framework absorbing aerogel encapsulated by multi-walled carbon nanotubes.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] The hybrid framework absorbing aerogel encapsulated by multi-walled carbon nanotubes of the present invention includes an Mxene dispersion prepared by an etching reaction and the preparation of aramid nanofibers. Compared with the above-mentioned existing preparation techniques, the present application has optimized and limited the relevant properties, making it more conducive to combining the mechanical properties of aramid nanofibers and the conductive properties of MXene, and exhibiting significant characteristics in terms of extreme temperature resistance, conductivity anisotropy, sensing performance and EMI shielding performance.
[0022] In this invention, all aerogels are in the form of thin layers. This is beneficial for solvent diffusion, which allows for gel formation in the shortest possible time. It also helps to reduce freezing stress concentration and deformation, and shortens freezing and drying time, thus facilitating production and manufacturing.
[0023] In this invention, the aerogel, after being impregnated with a carbon nanotube dispersion, is not dried in an oven, but rather freeze-dried using a freeze dryer. This freezing step allows the carbon nanotube dispersion to rapidly solidify within the aerogel's porous structure, thus preserving the three-dimensional network structure of the aerogel during subsequent drying and maintaining its structural integrity. Furthermore, freeze-drying (also known as freeze dehydration) is performed at low temperatures, effectively avoiding aerogel shrinkage and deformation caused by moisture evaporation, allowing the microporous aerogel to better highlight its mesh structure.
[0024] In this invention, MXene is mixed with aramid nanofibers to form a framework structure, which not only protects MXene and prevents its oxidative decomposition from direct contact with air, but also solves the problem that MXene-based aerogels have weak mechanical properties and cannot be directly applied. Simultaneously, extensive hydrogen bonds are formed between MXene and aramid nanofibers, preventing MXene from disrupting the stress transmission integrity of the aramid nanofibers.
[0025] Titanium carbide possesses high hardness, excellent electrical and thermal conductivity, and can be used to manufacture high-strength cutting tools, abrasives, electronic components, and heat sinks. Aramid nanofibers exhibit excellent properties such as high strength, high modulus, high temperature resistance, and corrosion resistance, and are widely used in aerospace, transportation, power, and defense industries. The composite of titanium carbide and aramid nanofibers effectively improves the strength and toughness of aerogels, providing good electrical conductivity and electromagnetic loss capability, resulting in better absorption and attenuation of electromagnetic waves. Simultaneously, it enhances the hydrophobic stability of the aerogel, allowing it to maintain good hydrophobic properties under a wider range of temperature and humidity conditions. In this invention, multi-walled carbon nanotubes are preferred as the wave-absorbing enhancer due to their lightweight and strong electromagnetic wave loss capability. Furthermore, the impregnation process for loading multi-walled carbon nanotubes onto the aerogel avoids further complex procedures and constructs an interface with microstructured "synapses." This facilitates the interface's interaction with air, promoting improved impedance matching of electromagnetic waves. Moreover, this complex microstructure increases the probability of electromagnetic wave reflection, thereby increasing energy dissipation. Attached Figure Description
[0026] Figure 1 This is a flowchart of a method for preparing a hybrid framework microwave absorbing aerogel encapsulated by multi-walled carbon nanotubes according to the present invention;
[0027] Figure 2 Here is a surface SEM image of the aerogel prepared in Example 1;
[0028] Figure 3 This is a magnified SEM image of the surface of the aerogel prepared in Example 1.
[0029] Figure 4 This is a 3D diagram of the reflection loss of the aerogel in Example 1;
[0030] Figure 5 This is a 3D diagram of the reflection loss of the aerogel in Example 5. Detailed Implementation
[0031] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.
[0032] This invention discloses a hybrid framework absorbing aerogel encapsulated by multi-walled carbon nanotubes, with reference to... Figure 1 This includes the following steps:
[0033] S1. Ti3AlC2, lithium fluoride, and hydrochloric acid were mixed and centrifuged at a ratio of (2-3) g: (3-4) g: (50-60) mL to prepare an MXene dispersion. The mixing was carried out in an oil bath at 45-50℃ for 40-48 h, with hydrochloric acid replenished 5 h before the end of the mixing process. After mixing, the MXene dispersion was obtained by centrifugation at progressively increasing speeds. Specifically, the first centrifugation was performed at 3500 r / min for 5 minutes, the second at 4000 r / min for 15 minutes, the supernatant was discarded, and water was added and allowed to stand overnight. The third centrifugation was performed at 5000 r / min for 15 minutes, the fourth at 6000 r / min for 20 minutes, the supernatant was discarded, and water was added and allowed to stand overnight. The fifth centrifugation was performed at 8000 r / min for 20 minutes, 10 ml of water was added, and the mixture was allowed to stand overnight to obtain the MXene dispersion.
[0034] S2, mix 5-10 mL of MXene dispersion with 50-60 g of aramid nanofiber gel to obtain a mixed gel; wherein, the aramid nanofiber gel is prepared by the following method: the ratio of alkali solution, dimethyl sulfoxide and para-aramid nanofiber is (2-3) mL: (500-600) mL: (1-2) g, and react for 8-10 h under the condition of stirring speed of 400-8000 r / min.
[0035] S3. The mixed gel is molded into a thin gel layer with a thickness of 2-5 mm using a mold. It is first frozen in a refrigerator, then freeze-dried for the first time to obtain an aerogel. The first freezing temperature is -60-62℃ for 10-12 hours; the first freeze-drying temperature is -50-59℃ for 24-48 hours. The mold shape is not limited, and the mold, displacement solvent, and displacement method are convenient and feasible. The mold is a common plastic mold, the displacement solvent is deionized water, and the displacement method is static settling, mainly through phase separation and molecular diffusion principles. This lays a good foundation for the industrialization of this invention.
[0036] S4. The aerogel is impregnated in a carbon nanotube dispersion, then frozen a second time, and then freeze-dried a second time to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0037] During the second freezing, the temperature was -60 to 62°C and the time was 10 to 12 hours; during the second freeze-drying, the temperature was -50 to 59°C and the time was 12 to 24 hours.
[0038] Example 1
[0039] Step 1: Ti3AlC2, lithium fluoride, and 0.37 g / mL hydrochloric acid were added sequentially to a reaction vessel in a ratio of 2 g:3 g:50 mL. The mixture was reacted in an oil bath at 45 °C with stirring at 4000 r / min for 48 h, with 10 mL of hydrochloric acid added 5 h before the end of the reaction. After stirring, the mixture was centrifuged 7 times at an increasing speed of 3500–8000 r / min for 20 min each time to prepare an MXene dispersion.
[0040] Step 2: Mix 5 mL of MXene dispersion with 52 g of para-aramid nanofiber gel evenly.
[0041] Step 3: Place the uniformly mixed gel in a square plastic mold, smooth the surface, and spread the thin gel layer after introducing the aramid nanofiber gel mixed with MXene dispersion to a thickness of 3 mm. Freeze in a refrigerator for 12 hours, and then freeze-dry in a freeze dryer at a freeze-drying temperature of -52℃ for 48 hours to obtain aerogel.
[0042] Step 4: Cut the aerogel into small pieces and soak them evenly in 2 mL (with 4 mL of water added) of carbon nanotube dispersion for 5 min. First, freeze them in a refrigerator for 10 h, and then freeze-dry them in a freeze dryer at -52℃ for 12 h to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0043] like Figure 2As shown, the hybrid framework absorbing aerogel structure encapsulated by multi-walled carbon nanotubes, in Figure 3 The image clearly shows the framework structure formed by the rapid solidification of the carbon nanotube dispersion within the pore structure of the aerogel due to freeze-drying. (Refer to...) Figure 4 As can be seen, the titanium carbide / aramid nanofiber hybrid absorbing aerogel wrapped with multi-walled carbon nanotubes in this embodiment has a porosity of 98.32%, a thickness of 4.07 mm, a reflection loss of -36.94 dB, an effective absorption bandwidth of 2.275 GHz, and a uniform periodic structure.
[0044] Example 2
[0045] Step 1: Using an etching method, Ti3AlC2, lithium fluoride, and 0.37 g / mL hydrochloric acid were added sequentially to a reaction vessel in a ratio of 2 g:3 g:50 mL. The reaction was carried out in an oil bath at 45 °C with stirring at 4000 r / min for 48 h, with 10 mL of hydrochloric acid added 5 h before the end of the reaction. After stirring, the mixture was centrifuged 7 times at an increasing speed of 3500–8000 r / min for 20 min each time to prepare an MXene dispersion.
[0046] Step 2: Mix 6 mL of MXene dispersion with 52 g of para-aramid nanofiber gel evenly.
[0047] Step 3: Place the uniformly mixed gel in a square plastic mold, smooth the surface, and spread the aramid nanofiber gel mixed with MXene dispersion to a thickness of 3 mm after spreading. Freeze in a refrigerator for 12 hours, and then freeze-dry in a freeze dryer at a freeze-drying temperature of -52℃ for 48 hours to obtain aerogel.
[0048] Step 4: Cut the aerogel into small pieces and soak them evenly in 2 mL (with 4 mL of water added) of carbon nanotube dispersion for 5 min. First, freeze them in a refrigerator for 10 h, and then freeze-dry them in a freeze dryer at -52℃ for 12 h to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0049] The titanium carbide / aramid nanofiber hybrid absorbing aerogel encapsulated by multi-walled carbon nanotubes in this embodiment has a porosity of 98.61%, a thickness of 3.73 mm, a reflection loss of -30.35 dB, an effective absorption bandwidth of 2.351 GHz, and a uniform periodic structure.
[0050] Example 3
[0051] Step 1: Using an etching method, Ti3AlC2, lithium fluoride, and 0.37 g / mL hydrochloric acid were added sequentially to a reaction vessel in a ratio of 2 g:3 g:50 mL. The reaction was carried out in an oil bath at 45 °C with stirring at 4000 r / min for 48 h, with 10 mL of hydrochloric acid added 5 h before the end of the reaction. After stirring, the mixture was centrifuged 7 times at an increasing speed of 3500–8000 r / min for 20 min each time to prepare an MXene dispersion.
[0052] Step 2: Mix 7 mL of MXene dispersion with 52 g of para-aramid nanofiber gel evenly.
[0053] Step 3: Place the uniformly mixed gel in a square plastic mold, smooth the surface, and spread the thin gel layer after introducing the aramid nanofiber gel mixed with MXene dispersion to a thickness of 3 mm. Freeze in a refrigerator for 12 hours, and then freeze-dry in a freeze dryer at a freeze-drying temperature of -52℃ for 48 hours to obtain aerogel.
[0054] Step 4: Cut the aerogel into small pieces and soak them evenly in 2 mL (with 4 mL of water added) of carbon nanotube dispersion for 5 min. First, freeze them in a refrigerator for 10 h, and then freeze-dry them in a freeze dryer at -52℃ for 12 h to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0055] The titanium carbide / aramid nanofiber hybrid absorbing aerogel encapsulated by multi-walled carbon nanotubes in this embodiment has a porosity of 98.75%, a thickness of 3.88 mm, a reflection loss of -24.66 dB, an effective absorption bandwidth of 2.572 GHz, and a uniform periodic structure.
[0056] Example 4
[0057] Step 1: Using an etching method, Ti3AlC2, lithium fluoride, and 0.37 g / mL hydrochloric acid were added sequentially to a reaction vessel in a ratio of 2 g:3 g:50 mL. The reaction was carried out in an oil bath at 45 °C with stirring at 4000 r / min for 48 h, with 10 mL of hydrochloric acid added 5 h before the end of the reaction. After stirring, the mixture was centrifuged 7 times at an increasing speed of 3500–8000 r / min for 20 min each time to prepare an MXene dispersion.
[0058] Step 2: Mix 8 mL of MXene dispersion with 52 g of para-aramid nanofiber gel.
[0059] Step 3: Place the uniformly mixed gel in a square plastic mold, smooth the surface, and spread the thin gel layer after introducing the aramid nanofiber gel mixed with MXene dispersion to a thickness of 3 mm. Freeze in a refrigerator for 12 hours, and then freeze-dry in a freeze dryer at a freeze-drying temperature of -52℃ for 48 hours to obtain aerogel.
[0060] Step 4: Cut the aerogel into small pieces and soak them evenly in 2 mL (with 4 mL of water added) of carbon nanotube dispersion for 5 min. First, freeze them in a refrigerator for 10 h, and then freeze-dry them in a freeze dryer at -52℃ for 12 h to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0061] The titanium carbide / aramid nanofiber hybrid absorbing aerogel encapsulated by multi-walled carbon nanotubes in this embodiment has a porosity of 98.34%, a thickness of 4.12 mm, a reflection loss of -16.19 dB, an effective absorption bandwidth of 2.734 GHz, and a uniform periodic structure.
[0062] Example 5
[0063] Step 1: Using an etching method, Ti3AlC2, lithium fluoride, and 0.37 g / mL hydrochloric acid were added sequentially to a reaction vessel in a ratio of 2 g:3 g:50 mL. The reaction was carried out in an oil bath at 45 °C with stirring at 4000 r / min for 48 h, with 10 mL of hydrochloric acid added 5 h before the end of the reaction. After stirring, the mixture was centrifuged 7 times at an increasing speed of 3500–8000 r / min for 20 min each time to prepare an MXene dispersion.
[0064] Step 2: Mix 10 mL of MXene dispersion with 52 g of para-aramid nanofiber gel evenly.
[0065] Step 3: Place the uniformly mixed gel in a square plastic mold, smooth the surface, and spread the aramid nanofiber gel mixed with MXene dispersion to a thickness of 3 mm. Freeze in a refrigerator for 12 hours, and then freeze-dry in a freeze dryer at a freeze-drying temperature of -52℃ for 48 hours to obtain aerogel.
[0066] Step 4: Cut the aerogel into small pieces and soak them evenly in 2 mL (with 4 mL of water added) of carbon nanotube dispersion for 5 min. First, freeze them in a refrigerator for 10 h, and then freeze-dry them in a freeze dryer at -52℃ for 12 h to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel.
[0067] Reference Figure 5The titanium carbide / aramid nanofiber hybrid absorbing aerogel wrapped with multi-walled carbon nanotubes in this embodiment has a porosity of 99.06%, a thickness of 3.57 mm, a reflection loss of -13.23 dB, an effective absorption bandwidth of 2.975 GHz, and a uniform periodic structure. In addition, the process is stable, highly operable, and has controllable overall cost, thus having good social value.
[0068] The present invention also discloses a product obtained from a hybrid framework absorbing aerogel encapsulated by multi-walled carbon nanotubes.
[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.
Claims
1. A method for preparing a hybrid framework microwave-absorbing aerogel encapsulated by multi-walled carbon nanotubes, characterized in that, Includes the following steps: S1, Ti3AlC2, lithium fluoride and hydrochloric acid were stirred and centrifuged in a ratio of (2-3) g: (3-4) g: (50-60) mL to prepare MXene dispersion; stirring was carried out in an oil bath at 45-50℃ for 40-48 h; hydrochloric acid was added 5 h before the end of stirring; after stirring, the mixture was centrifuged multiple times with increasing centrifugation speed to obtain MXene dispersion; S2, mix 5-10 mL of MXene dispersion with 50-60 g of aramid nanofiber gel to obtain a mixed gel; wherein, the aramid nanofiber gel is prepared by the following method: the ratio of alkali solution, dimethyl sulfoxide and para-aramid nanofiber is (2-3) mL: (500-600) mL: (1-2) g, and react for 8-10 h under the condition of stirring speed of 400-8000 r / min; S3, the mixed gel is molded into a thin layer gel, first frozen, then freeze-dried to obtain an aerogel; wherein, the temperature of the first freezing is -(60~62)℃ and the time is 10~12h; the temperature of the first freeze-drying is -(50~59)℃ and the time is 24~48h. S4. The aerogel is impregnated in a carbon nanotube dispersion, then frozen a second time, and then freeze-dried a second time to obtain a multi-walled carbon nanotube-encapsulated titanium carbide / aramid nanofiber hybrid microwave absorbing aerogel. During the second freezing, the temperature was -60 to 62°C and the time was 10 to 12 hours; during the second freeze-drying, the temperature was -50 to 59°C and the time was 12 to 24 hours.
2. The method for preparing a hybrid framework microwave absorbing aerogel encapsulated by multi-walled carbon nanotubes according to claim 1, characterized in that, S3, the thickness of the thin gel layer is 2~5mm.
3. A product obtained by the method for preparing a hybrid framework microwave absorbing aerogel encapsulated by multi-walled carbon nanotubes according to any one of claims 1 to 2.