Multifunctional aerogel and preparation method and application thereof

Abstract

This invention provides a multifunctional aerogel, its preparation method, and its applications. The multifunctional aerogel of this invention comprises reduced graphene oxide (rGO) and nanoparticles supported on the rGO, wherein the nanoparticles are a Fe3O4 / Fe / C heterocomposite material. It allows incident electromagnetic waves to undergo multiple scattering within the aerogel, thus dissipating electromagnetic wave energy. By selecting reduced graphene oxide (rGO) as the host material, its low density achieves lightweight properties. Furthermore, the numerous defects in rGO can act as dipole polarization centers, generating strong dipole polarization to attenuate electromagnetic waves. This invention also provides a method for preparing the multifunctional aerogel and its applications.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a multifunctional aerogel, its preparation method, and its applications. Background Technology

[0002] With the rapid development of communication technology, electronic equipment, and aerospace, the demand for novel materials with multifunctional properties is increasing. Aerogel materials have attracted much attention in recent years due to their unique porous structure and high specific surface area, making them promising for applications in lightweighting, heat insulation, and microwave absorption. For example, in the 5G and future 6G era, aerogel materials can be used as microwave absorbers or electromagnetic shielding films in wearable electronic devices and the construction industry to eliminate electromagnetic interference and protect human health. Simultaneously, aerogel materials with hydrophobic and thermal insulation properties can also serve as an outer protective layer covering building surfaces, achieving multiple functions such as self-cleaning, heat insulation, and elimination of electromagnetic pollution. Not only are they environmentally friendly, but they also have broader prospects in both civilian and military applications compared to single-function microwave absorbing materials.

[0003] In the area of ​​low-frequency microwave absorption, due to the relatively long wavelength of low-frequency electromagnetic waves, relatively large absorbing materials are required for effective absorption. Current material properties are not ideal. To cope with increasingly complex electromagnetic environments and engineering requirements, it is necessary to develop a new material that can combine excellent low-frequency microwave absorption, electromagnetic interference shielding, hydrophobicity, and thermal insulation properties. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a multifunctional aerogel that combines excellent low-frequency microwave absorption, electromagnetic interference shielding, hydrophobicity, and thermal insulation properties.

[0005] The present invention also provides a method for preparing a multifunctional aerogel.

[0006] This invention also provides applications of multifunctional aerogels.

[0007] A first aspect of the present invention provides a multifunctional aerogel comprising reduced graphene oxide and nanoparticles supported on the reduced graphene oxide, wherein the nanoparticles are a Fe3O4 / Fe / C heterocomposite material.

[0008] One technical solution of the present invention relating to multifunctional aerogels has at least the following beneficial effects:

[0009] The multifunctional aerogel of this invention can optimize low-frequency microwave absorption performance by adjusting the pore structure and material composition of the aerogel material, thus meeting the increasingly complex electromagnetic environment and engineering requirements. Specifically:

[0010] The porous structure of multifunctional aerogels can significantly reduce the impedance difference between the material and air, effectively optimizing impedance matching. This allows incident electromagnetic waves to undergo multiple scattering within the aerogel, thus dissipating electromagnetic wave energy. Reduced graphene oxide (rGO) is chosen as the main material, utilizing its low density to achieve lightweight properties. Furthermore, the numerous defects in rGO can act as dipole polarization centers, generating strong dipole polarization to attenuate electromagnetic waves.

[0011] The multifunctional aerogel of this invention is prepared by selecting MIL-88B as a precursor and obtaining Fe3O4 / Fe / C heterocomposite material through high-temperature calcination. This not only brings magnetic loss, but also generates strong interfacial polarization in the Fe3O4 / Fe / C heterocomposite material and between the Fe3O4 / Fe / C heterocomposite material and rGO, thus achieving good low-frequency absorption.

[0012] Fe3O4 / Fe / C heterogeneous composite materials, where "heterogeneous" refers to composite materials containing different components.

[0013] The multifunctional aerogel of this invention has good impedance matching and attenuation performance, and can effectively attenuate electromagnetic waves.

[0014] The multifunctional aerogel of this invention has excellent electromagnetic interference shielding performance.

[0015] The multifunctional aerogel of this invention also has good hydrophobic and thermal insulation properties, and has even better application prospects.

[0016] According to some embodiments of the present invention, the specific surface area of ​​the multifunctional aerogel is 50 m². 2 / g~200m 2 / g.

[0017] According to some embodiments of the present invention, the water contact angle of the multifunctional aerogel is 120° to 150°.

[0018] A second aspect of the present invention provides a method for preparing multifunctional aerogels, comprising the following steps:

[0019] S1: After dispersing MIL-88B in a solvent, a surfactant is added, and after washing, it is mixed with a graphene oxide solution to carry out an electrostatic self-assembly reaction to obtain a MIL-88B / graphene oxide composite material. After freeze-drying, a MIL-88B / graphene oxide aerogel is obtained.

[0020] S2: The MIL-88B / graphene oxide is calcined under a protective atmosphere to obtain the multifunctional aerogel.

[0021] One technical solution of the present invention relating to the preparation method of multifunctional aerogels has at least the following beneficial effects:

[0022] The preparation method of the present invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0023] According to some embodiments of the present invention, in step S1, the MIL-88B has a rod-like shape.

[0024] MIL-88B consists of MIL-88B nanorods. The morphology of the nanorods helps to increase the specific surface area and porosity of the material, thereby enhancing the electromagnetic attenuation effect to a certain extent.

[0025] According to some embodiments of the present invention, in step S1, the method for preparing MIL-88B includes the following steps:

[0026] Iron salts and terephthalic acid were dispersed in an organic solvent, and then NaOH solution was added. After stirring, the reaction was carried out, and the products were separated, purified and dried to obtain MIL-88B nanorods.

[0027] The reaction temperature is 70℃~120℃.

[0028] The reaction time is 6 to 18 hours.

[0029] According to some embodiments of the present invention, the iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric sulfate.

[0030] According to some embodiments of the present invention, the organic solvent is selected from at least one of dimethylformamide, ethanol, and methanol.

[0031] According to some embodiments of the present invention, in step S1, after dispersing MIL-88B in a solvent, a surfactant is added, and after washing, it is mixed with a graphene oxide solution. Specifically, MIL-88B can be first dispersed in water, then the surfactant is added, and after thorough mixing, the product is separated, purified, and redispersed in water to mix with the graphene oxide (GO) solution. This treatment method effectively removes excess surfactant after introducing a positive charge onto the surface of MIL-88B.

[0032] According to some embodiments of the present invention, in step S1, MIL-88B is dispersed in a solvent, the solvent including water.

[0033] According to some embodiments of the present invention, in step S1, the surfactant includes at least one of hexadecyltrimethylammonium bromide, polyvinyl alcohol, and polyvinylpyrrolidone.

[0034] According to some embodiments of the present invention, in step S1, the mass ratio of MIL-88B to graphene oxide is 1 to 15:1.

[0035] According to some embodiments of the present invention, in step S1, the temperature of the electrostatic self-assembly reaction is 10°C to 100°C.

[0036] According to some embodiments of the present invention, in step S1, the electrostatic self-assembly reaction takes 1 h to 12 h.

[0037] According to some embodiments of the present invention, in step S1, the freeze-drying temperature is -40°C to -60°C.

[0038] According to some embodiments of the present invention, in step S1, the freeze-drying time is 12h to 48h.

[0039] According to some embodiments of the present invention, in step S2, the calcination step includes: heating to 600°C to 900°C at a rate of 2°C / min to 5°C / min, and holding at that temperature for 1h to 5h.

[0040] According to some embodiments of the present invention, in step S2, the protective atmosphere includes nitrogen.

[0041] A third aspect of the present invention provides the application of multifunctional aerogels in low-frequency microwave absorption and electromagnetic interference shielding.

[0042] The present invention relates to a technical solution for the application of multifunctional aerogels in low-frequency microwave absorption and electromagnetic interference shielding, which has at least the following beneficial effects:

[0043] The multifunctional aerogel of this invention can optimize low-frequency microwave absorption performance by adjusting the pore structure and material composition of the aerogel material, thus meeting the increasingly complex electromagnetic environment and engineering requirements. Specifically:

[0044] The multifunctional aerogel of this invention, due to its porous structure, can significantly reduce the impedance difference between the material and air, effectively optimizing impedance matching. This allows incident electromagnetic waves to undergo multiple scattering within the aerogel, thus dissipating electromagnetic wave energy. Reduced graphene oxide (rGO) is chosen as the main component, utilizing its low density to achieve lightweight properties. Simultaneously, the numerous defects in rGO can act as dipole polarization centers, generating strong dipole polarization to attenuate electromagnetic waves. During preparation, MIL-88B is selected as the precursor, and a Fe3O4 / Fe / C heterocomposite material is obtained through high-temperature calcination. This not only introduces magnetic loss, but the numerous heterojunctions within the Fe3O4 / Fe / C heterocomposite material and between the Fe3O4 / Fe / C heterocomposite material and rGO also generate strong interfacial polarization, achieving excellent low-frequency absorption. When used for low-frequency microwave absorption and electromagnetic interference shielding, it exhibits good impedance matching and attenuation performance, effectively attenuating electromagnetic waves and demonstrating excellent electromagnetic interference shielding effectiveness. It also possesses good hydrophobic and thermal insulation properties, indicating promising application prospects.

[0045] According to some embodiments of the present invention, when the amount of the multifunctional aerogel added to the matrix material is 1% to 50%, the microwave absorption performance is -20dB to -70dB.

[0046] According to some embodiments of the present invention, when the amount of the multifunctional aerogel added to the matrix material is 1% to 50%, the electromagnetic interference shielding performance is 20dB to 90dB.

[0047] According to some embodiments of the present invention, the matrix material includes paraffin wax and epoxy resin. Attached Figure Description

[0048] Figure 1 A picture of a multifunctional aerogel.

[0049] Figure 2 This is a scanning electron microscope image of the multifunctional aerogel from Example 1.

[0050] Figure 3 The graph shows the reflection loss of the microwave absorbing material made from the multifunctional aerogel of Example 1.

[0051] Figure 4 The electromagnetic interference shielding effectiveness diagram of the multifunctional aerogel absorbing material of Example 1 is shown.

[0052] Figure 5 This is a contact angle test diagram of the multifunctional aerogel in Example 1.

[0053] Figure 6 This is a diagram illustrating the heat insulation effect of the multifunctional aerogel in Example 1. Detailed Implementation

[0054] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0055] In some embodiments of the present invention, a multifunctional aerogel is provided, comprising reduced graphene oxide and nanoparticles supported on the reduced graphene oxide, wherein the nanoparticles are Fe3O4 / Fe / C heterocomposite materials.

[0056] It is understood that the multifunctional aerogel of this invention can optimize low-frequency microwave absorption performance by adjusting the pore structure and material composition of the aerogel material, thus meeting the increasingly complex electromagnetic environment and engineering requirements. Specifically:

[0057] It can also be understood that the unique porous structure of multifunctional aerogels allows incident electromagnetic waves to undergo multiple scatterings within the aerogel, thus dissipating electromagnetic wave energy. By choosing reduced graphene oxide (rGO) as the main material, its low density achieves lightweight properties. Furthermore, the numerous defects in rGO can act as dipole polarization centers, generating strong dipole polarization to attenuate electromagnetic waves.

[0058] Specifically, in the preparation of the multifunctional aerogel of the present invention, MIL-88B is selected as the precursor, and Fe3O4 / Fe / C heterocomposite material is obtained by high-temperature calcination. This not only brings magnetic loss, but also generates strong interfacial polarization in the Fe3O4 / Fe / C heterocomposite material and the numerous hetero interfaces between the Fe3O4 / Fe / C heterocomposite material and rGO, thus achieving good low-frequency absorption.

[0059] It should be noted that in Fe3O4 / Fe / C heterogeneous composite materials, "heterogeneous" means that the composite material contains different components.

[0060] The multifunctional aerogel of this invention has good impedance matching and attenuation performance, and can effectively attenuate electromagnetic waves.

[0061] The multifunctional aerogel of this invention has excellent electromagnetic interference shielding performance.

[0062] The multifunctional aerogel of this invention also has good hydrophobic and thermal insulation properties, and has even better application prospects.

[0063] In some embodiments of the present invention, the specific surface area of ​​the multifunctional aerogel is 50 m². 2 / g~200m 2 / g.

[0064] In some embodiments of the present invention, the water contact angle of the multifunctional aerogel is 120° to 150°.

[0065] In other embodiments of the present invention, a method for preparing multifunctional aerogels is provided, comprising the following steps:

[0066] S1: After dispersing MIL-88B in a solvent, a surfactant is added, and after washing, it is mixed with a graphene oxide solution to carry out an electrostatic self-assembly reaction to obtain a MIL-88B / graphene oxide composite material. After freeze-drying, a MIL-88B / graphene oxide aerogel is obtained.

[0067] S2: MIL-88B / graphene oxide was calcined under a protective atmosphere to obtain a multifunctional aerogel.

[0068] It is understood that the preparation method of the present invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0069] In some embodiments of the present invention, in step S1, the MIL-88B has a rod-like morphology.

[0070] MIL-88B consists of MIL-88B nanorods. The morphology of the nanorods helps to increase the specific surface area and porosity of the material, thereby enhancing the electromagnetic attenuation effect to a certain extent.

[0071] In some embodiments of the present invention, step S1, the method for preparing MIL-88B includes the following steps:

[0072] Iron salts and terephthalic acid were dispersed in an organic solvent, and then NaOH solution was added. After stirring, the reaction was carried out, and the products were separated, purified and dried to obtain MIL-88B nanorods.

[0073] The reaction temperature is 70℃~120℃.

[0074] The reaction time is 6 to 18 hours.

[0075] In some embodiments of the present invention, the iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric sulfate.

[0076] In some embodiments of the present invention, the organic solvent is selected from at least one of dimethylformamide, ethanol, and methanol.

[0077] In some embodiments of the present invention, in step S1, after dispersing MIL-88B in a solvent, a surfactant is added, and after washing, it is mixed with a graphene oxide solution. Specifically, MIL-88B can be first dispersed in water, then the surfactant is added, and after thorough mixing, the product is separated, purified, and redispersed in water to mix with the graphene oxide (GO) solution. The above treatment method is beneficial for effectively removing excess surfactant after introducing a positive charge onto the surface of MIL-88B.

[0078] In some embodiments of the present invention, in step S1, MIL-88B is dispersed in a solvent, including water.

[0079] In some embodiments of the present invention, in step S1, the surfactant includes at least one of hexadecyltrimethylammonium bromide, polyvinyl alcohol, and polyvinylpyrrolidone.

[0080] In some embodiments of the present invention, in step S1, the mass ratio of MIL-88B to graphene oxide is 1 to 15:1.

[0081] In some embodiments of the present invention, in step S1, the temperature of the electrostatic self-assembly reaction is 10°C to 100°C.

[0082] In some embodiments of the present invention, in step S1, the electrostatic self-assembly reaction takes 1 h to 12 h.

[0083] In some embodiments of the present invention, in step S1, the freeze-drying temperature is -40°C to -60°C.

[0084] In some embodiments of the present invention, in step S1, the freeze-drying time is 12h to 48h.

[0085] In some embodiments of the present invention, step S2, the calcination step includes: heating to 600°C to 900°C at a rate of 2°C / min to 5°C / min, and holding at that temperature for 1h to 5h.

[0086] In some embodiments of the present invention, in step S2, the protective atmosphere includes nitrogen.

[0087] In other embodiments of the present invention, the application of multifunctional aerogels in low-frequency microwave absorption and electromagnetic interference shielding is provided.

[0088] It is understood that the multifunctional aerogel of this invention can optimize low-frequency microwave absorption performance by adjusting the pore structure and material composition of the aerogel material, thus meeting the increasingly complex electromagnetic environment and engineering requirements. Specifically:

[0089] It can also be understood that the multifunctional aerogel of this invention, due to its porous structure, can significantly reduce the impedance difference between the material and air, effectively optimizing impedance matching. This allows incident electromagnetic waves to undergo multiple scattering within the aerogel, thus dissipating electromagnetic wave energy. Reduced graphene oxide (rGO) is chosen as the main component, utilizing its low density to achieve lightweight properties. Simultaneously, the numerous defects in rGO can act as dipole polarization centers, generating strong dipole polarization to attenuate electromagnetic waves. During preparation, MIL-88B was selected as the precursor, and a Fe3O4 / Fe / C heterocomposite material was obtained through high-temperature calcination. This not only introduces magnetic loss, but the numerous heterojunctions within the Fe3O4 / Fe / C heterocomposite material and between the Fe3O4 / Fe / C heterocomposite material and rGO also generate strong interfacial polarization, achieving excellent low-frequency absorption. When used for low-frequency microwave absorption and electromagnetic interference shielding, it exhibits good impedance matching and attenuation performance, effectively attenuating electromagnetic waves and demonstrating excellent electromagnetic interference shielding effectiveness. It also possesses good hydrophobic and thermal insulation properties, indicating promising application prospects.

[0090] In some embodiments of the present invention, when the amount of multifunctional aerogel added to the matrix material is 1% to 50%, the microwave absorption performance is -20dB to -70dB.

[0091] In some embodiments of the present invention, when the amount of multifunctional aerogel added to the matrix material is 1% to 50%, the electromagnetic interference shielding performance is 20dB to 90dB.

[0092] The technical solution of the present invention will be better understood below with reference to specific embodiments.

[0093] It should be noted that all reagents used in the examples were obtained from commercially available sources.

[0094] Example 1

[0095] A multifunctional aerogel was prepared, comprising the following steps:

[0096] 1) Add 1.35 g of FeCl3·6H2O and 0.58 g of terephthalic acid to 25 mL of dimethylformamide solvent, add 2 mL of NaOH (2M) solution, stir magnetically at 25 °C for 30 min, seal and heat at 100 °C for 12 h, filter, wash the obtained solid with ethanol and water until neutral, and then dry at 60 °C for 12 h to obtain MIL-88B nanorods;

[0097] 2) Disperse 150 mg of MIL-88B nanorods in 250 mL of ultrapure water, add 25 mg of cetyltrimethylammonium bromide, mix thoroughly, wash three times with ultrapure water, redisperse, and then mix with 3 mL of pre-prepared 5 mg / mL graphene oxide solution. Electrostatic self-assembly at 50 °C for 6 h, and then freeze-dry for 24 h to obtain MIL-88B / GO aerogel.

[0098] 3) The MIL-88B / GO aerogel was placed in a nitrogen environment and heated to 800℃ at a heating rate of 2℃ / min. It was then calcined, kept at that temperature for 2 hours, and then naturally cooled to obtain a multifunctional aerogel with excellent low-frequency microwave absorption, electromagnetic interference shielding, hydrophobicity, and thermal insulation properties.

[0099] refer to Figure 1 As shown, when the aerogel was placed on the flower's stamen, the stamen did not collapse, demonstrating the excellent lightweight properties of the multifunctional aerogel. Tests revealed that the aerogel's density is only 0.029 g / cm³. 3 .

[0100] The scanning electron microscope image of the multifunctional aerogel prepared in this embodiment is shown below. Figure 2 As shown.

[0101] from Figure 2 It can be seen that the reduced graphene oxide is randomly loaded with nanoparticles derived from MIL-88B nanorods and has a large number of pores, indicating that the aerogel was successfully prepared.

[0102] The multifunctional aerogel of this embodiment is used to make a microwave absorbing material. Specifically:

[0103] First, a mixture consisting of 5 wt% multifunctional aerogel and 95 wt% paraffin wax was thoroughly mixed to form a homogeneous composite material. Then, the mixture was pressed into a ring shape with an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 1-5 mm. Electromagnetic parameters were measured using a vector network analyzer in the 2-18 GHz range, and the resulting reflection loss curve is shown below. Figure 3 As shown.

[0104] Depend on Figure 3 It can be seen that the obtained multifunctional aerogel-based microwave absorbing material has excellent microwave absorption performance. With a thickness of 4.83 mm, the reflection loss reaches -65.17 dB at a low frequency of 5.84 GHz, and the effective absorption bandwidth is as high as 5.76 GHz with a thickness of 2.23 mm.

[0105] Furthermore, the mixture consisting of 40 wt% multifunctional aerogel and 60 wt% paraffin was thoroughly mixed to form a homogeneous composite material. S-parameter measurements were performed using a vector network analyzer in the 2-18 GHz range, and the resulting electromagnetic interference shielding effectiveness curves are shown below. Figure 4 As shown.

[0106] Depend on Figure 4 It can be seen that the obtained multifunctional aerogel-based microwave absorbing material has excellent electromagnetic interference shielding performance, reaching 81.83dB at 18GHz.

[0107] Furthermore, the hydrophobic and thermal insulation properties of the aerogel were evaluated, as follows: Figure 5 and Figure 6 As shown.

[0108] Depend on Figure 5 It can be seen that the contact angle of the multifunctional aerogel is 136°, which indicates that it has good hydrophobic properties.

[0109] Depend on Figure 6 It can be seen that multifunctional aerogels have good thermal insulation properties.

[0110] Example 2

[0111] A multifunctional aerogel was prepared, comprising the following steps:

[0112] 1) Add 3g of FeCl3·6H2O and 0.8g of terephthalic acid to 50mL of dimethylformamide solvent, add 4mL of NaOH (2M) solution, stir magnetically at 25℃ for 30min, seal and heat at 100℃ for 12h, filter, wash the obtained solid with ethanol and water until neutral, and then dry at 60℃ for 12h to obtain MIL-88B nanorods;

[0113] 2) Disperse 200 mg of MIL-88B nanorods in 300 mL of ultrapure water, add 30 mg of cetyltrimethylammonium bromide, mix thoroughly, wash three times with ultrapure water, redisperse, and then mix with 5 mL of pre-prepared 5 mg / mL graphene oxide solution. Electrostatic self-assembly at 50 °C for 10 h, and then freeze-dry for 48 h to obtain MIL-88B / GO aerogel.

[0114] 3) The MIL-88B / GO aerogel was placed in a nitrogen environment and heated to 600℃ at a heating rate of 2℃ / min. It was then calcined, kept at that temperature for 2 hours, and then cooled naturally to obtain a multifunctional aerogel with excellent low-frequency microwave absorption, electromagnetic interference shielding, hydrophobic and thermal insulation properties.

[0115] A mixture consisting of 10 wt% multifunctional aerogel and 90 wt% paraffin wax was thoroughly mixed to form a uniform composite material. The mixture was then pressed into a ring shape with an outer diameter of 7 mm and an inner diameter of 3 mm, with a thickness of 1-5 mm. At a thickness of 2.4 mm, a reflection loss of -24 dB was obtained.

[0116] Furthermore, the mixture consisting of 20 wt% multifunctional aerogel and 80 wt% paraffin was thoroughly mixed to form a homogeneous composite material. S-parameter measurements were performed using a vector network analyzer in the 2-18 GHz range, and the electromagnetic interference shielding effectiveness was found to be 15.04 dB.

[0117] Example 3

[0118] A multifunctional aerogel was prepared, comprising the following steps:

[0119] 1) Add 2.7g of FeCl3·6H2O and 1.16g of terephthalic acid to 50mL of dimethylformamide solvent, add 4mL of NaOH (2M) solution, stir magnetically at 25℃ for 30min, seal and heat at 100℃ for 12h, filter, wash the filtered solid with ethanol and water until neutral, and then dry at 60℃ for 12h to obtain MIL-88B nanorods;

[0120] 2) Disperse 300 mg of MIL-88B nanorods in 500 mL of ultrapure water, add 50 mg of cetyltrimethylammonium bromide, mix thoroughly, wash three times with ultrapure water, redisperse, and then mix with 6 mL of pre-prepared 5 mg / mL graphene oxide solution. Electrostatic self-assembly at 50 °C for 10 h, and then freeze-dry for 24 h to obtain MIL-88B / GO aerogel.

[0121] 3) The MIL-88B / GO aerogel was placed in a nitrogen environment and heated to 700℃ at a heating rate of 2℃ / min. It was then calcined, kept at that temperature for 2 hours, and then cooled naturally to obtain a multifunctional aerogel with excellent low-frequency microwave absorption, electromagnetic interference shielding, hydrophobic and thermal insulation properties.

[0122] A mixture consisting of 5 wt% multifunctional aerogel and 95 wt% paraffin wax was thoroughly mixed to form a uniform composite material. The mixture was then pressed into an annular shape with an outer diameter of 7 mm and an inner diameter of 3 mm, with a thickness of 1-5 mm. At a thickness of 2.23 mm, a reflection loss of -51.99 dB was obtained.

[0123] Furthermore, the mixture consisting of 40 wt% multifunctional aerogel and 60 wt% paraffin was thoroughly mixed to form a homogeneous composite material. S-parameter measurements were performed using a vector network analyzer in the 2-18 GHz range, and the electromagnetic interference shielding effectiveness was found to be 30.57 dB.

[0124] The reason why the multifunctional aerogel of the present invention can achieve low-frequency microwave absorption is that the porous structure can not only cause multiple scattering of incident electromagnetic waves inside the aerogel, thus consuming electromagnetic wave energy, but also promote conduction loss.

[0125] The multifunctional aerogel of this invention utilizes numerous defects within the material to generate strong dipole polarization, thereby attenuating electromagnetic waves. The Fe3O4 / Fe / C heterocomposite material obtained through high-temperature calcination not only introduces magnetic loss but also generates strong interfacial polarization through numerous heterogeneous interfaces within Fe3O4 / Fe / C and between Fe3O4 / Fe / C and rGO.

[0126] The multifunctional aerogel of this invention exhibits a strong synergistic effect of dielectric loss, magnetic loss, and conduction loss in the low-frequency band due to various factors.

[0127] The reason for electromagnetic interference shielding is to increase the sample filling amount in the pressed test ring, which increases the conductivity of the material, leading to impedance mismatch, which causes a large number of electromagnetic waves to be reflected back, thus achieving the shielding effect.

[0128] The multifunctional aerogel of this invention possesses excellent hydrophobic properties. Firstly, the aerogel's microstructure consists of a highly nano-sized three-dimensional network containing numerous microscale pores. This unique structure endows the aerogel with an extremely high specific surface area and porous nature, thereby increasing its hydrophobicity. Secondly, the reduced graphene oxide (rGO) undergoes a high-temperature reduction process to remove oxygen functional groups from graphene oxide (GO), reducing or eliminating its hydrophilic properties.

[0129] Aerogels possess excellent thermal insulation properties primarily because they consist of a highly nano-sized porous structure containing numerous micro-scale pores. These micro-pores restrict heat transfer, making it difficult for heat to be rapidly transferred through the aerogel material, thus achieving a thermal insulation effect.

[0130] The multifunctional aerogel of this invention exhibits excellent low-frequency microwave absorption performance (-20dB to -70dB), effectively absorbing low-frequency microwaves and converting electromagnetic waves into heat or other forms of energy, thereby reducing or blocking the propagation of electromagnetic waves. This is crucial for the control and management of electromagnetic waves, especially in reducing radio wave interference or isolating electromagnetic radiation.

[0131] The multifunctional aerogel of this invention possesses electromagnetic interference shielding performance (20dB to 90dB), effectively shielding against electromagnetic interference, i.e., preventing electromagnetic waves from passing through or interfering with the transmission and function of equipment or systems. It plays a crucial role in the protection of electronic devices, communication systems, and sensitive equipment, improving their performance and stability.

[0132] In summary, the addition of this multifunctional aerogel enables the matrix material to possess excellent electromagnetic wave control characteristics, making it applicable to various fields requiring low-frequency microwave absorption and electromagnetic interference shielding, including electronics, communications, military, and sensitive equipment. This improves the performance and reliability of the equipment and reduces the impact of electromagnetic interference on the surrounding environment or other equipment.

[0133] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A multifunctional aerogel, characterized by, It includes reduced graphene oxide and nanoparticles supported on the reduced graphene oxide, wherein the nanoparticles are Fe3O4 / Fe / C heterocomposite materials; The multifunctional aerogel is prepared by a method comprising the following steps: S1: After dispersing MIL-88B in a solvent, a surfactant is added, and after washing, it is mixed with a graphene oxide solution to carry out an electrostatic self-assembly reaction to obtain a MIL-88B / graphene oxide composite material. After freeze-drying, a MIL-88B / graphene oxide aerogel is obtained. S2: The MIL-88B / graphene oxide is calcined under a protective atmosphere to obtain the multifunctional aerogel.

2. The multifunctional aerogel according to claim 1, wherein, The specific surface area of ​​the multifunctional aerogel is 50 m². 2 / g~200m 2 / g.

3. The multifunctional aerogel of claim 1, wherein, The water contact angle of the multifunctional aerogel is 120°~150°.

4. The multifunctional aerogel of claim 1, wherein, In step S1, the mass ratio of MIL-88B to graphene oxide is 1~15:

1.

5. The multifunctional aerogel of claim 1, wherein, In step S1, the freeze-drying temperature is -40℃ to -60℃; and / or, the freeze-drying time is 12h to 48h.

6. The multifunctional aerogel of claim 1, wherein, In step S2, the calcination step includes: heating to 600℃ to 900℃ at a rate of 2℃ / min to 5℃ / min, and holding at that temperature for 1h to 5h.

7. The application of the multifunctional aerogel as described in any one of claims 1 to 6 in low-frequency microwave absorption and electromagnetic interference shielding.

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