NiZn-MOF-loaded aramid fiber / chitosan carbon aerogel as well as preparation method and application thereof

Abstract

The invention discloses NiZn-MOF-loaded aramid fiber / chitosan carbon aerogel as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, inducing NiZn-MOF to grow on aramid fiber in situ; the ZNMA is obtained; s2, dissolving ZNMA and chitosan in deionized water, stirring and mixing, dropwise adding acetic acid at the same time to form an aerogel precursor, and freeze-drying to obtain NiZn-MOF coated aramid fiber / chitosan aerogel; and S3, carrying out heat treatment on the sample in the step S in an inert gas atmosphere to obtain the NiZn-MOF coated aramid fiber / chitosan carbon aerogel, namely ZNCA. The carbonized MOF derivative is uniformly dispersed in the carbon matrix to serve as a multistage polarization center, meanwhile, the aramid fiber is in bridge connection with the chitosan carbon plate, a high polarization active interface is formed, conductivity loss is enhanced, multiple reflection is induced, high wave absorbing performance is achieved, and meanwhile the method can also be applied to the field of infrared stealth.

Description

Technical Field

[0001] The present invention relates to the technical field of stealth materials, and specifically to an aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF, and a preparation method and application thereof. Background Art

[0002] With the wide application of radar and infrared composite detection technologies, stealth materials need to simultaneously meet the requirements of efficient absorption of electromagnetic waves and control of thermal radiation characteristics for radar-infrared compatibility.

[0003] Traditional single stealth materials face significant limitations in performance. For example, although metal-organic frameworks (MOFs) have a high specific surface area and adjustable pore structures, their weak interfacial bonding with the carbon matrix easily leads to particle agglomeration during the mechanical mixing process, forming conductive islands and reducing the electromagnetic loss efficiency. Although chitosan carbon aerogels can construct a three-dimensional porous framework through freeze-drying-carbonization processes, the molecular chain directional contraction during the carbonization process causes lamellar stacking structures, with poor connectivity of the interlayer conductive network and insufficient structural stability, resulting in a narrow electromagnetic wave absorption band and weak reflection loss. Existing MOF / cellulose-based composites mostly rely on an in-situ mixing strategy, but the interfacial compatibility between the functional phase and the matrix is poor, making it difficult to achieve cross-scale synergistic optimization of the heterogeneous interface.

[0004] Therefore, there is an urgent need to develop a new composite material with strong interfacial bonding, heterogeneous interface synergistic effects, good wave absorption performance, and low infrared detectability. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies existing in the prior art, and provide an aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF, and a preparation method and application thereof, which achieve efficient wave absorption and good thermal management performance for radar-infrared compatible stealth. The present invention is specifically realized through the following technical solutions: A preparation method of an aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF, comprising the following steps: S1: Induce the in-situ growth of NiZn-MOF nickel-zinc metal-organic framework on aramid fibers; obtain aramid fibers loaded with NiZn-MOF, NiZn-MOF@aramid fibers, i.e., ZNMA; S2: Dissolve ZNMA and chitosan in deionized water and stir and mix them, and at the same time drop in acetic acid to form an aerogel precursor, and obtain NiZn-MOF@aramid fiber / chitosan aerogel through freeze-drying; S3: Heat-treat the sample in step S2 under an inert gas atmosphere to obtain NiZn-MOF@aramid fiber / chitosan carbon aerogel, i.e., ZNCA.

[0006] Among them, the specific steps for in-situ growth of NiZn-MOF on aramid fibers in S1 are as follows: Dissolve aramid fibers, zinc nitrate hexahydrate, nickel chloride hexahydrate, 2-methylimidazole, and cetyl dimethyl ammonium bromide in deionized water, mix and stir, then carry out hydrothermal reaction, followed by centrifugation, washing, and taking the precipitate for vacuum drying to obtain NiZn-MOF@aramid fibers, namely ZNMA.

[0007] Among them, the mass ratio of aramid fibers, zinc nitrate hexahydrate, nickel chloride hexahydrate, 2-methylimidazole, cetyl dimethyl ammonium bromide, and deionized water is 0.1-0.2: 0.59-0.6: 0.23-0.25: 4.3-4.6: 0.005-0.015: 90-120.

[0008] Among them, the hydrothermal reaction temperature is 130-180 °C, and the reaction time is 5-15 h; the stirring time for dissolving the aramid fibers, zinc nitrate hexahydrate, nickel chloride hexahydrate, 2-methylimidazole, and cetyl dimethyl ammonium bromide in deionized water is 0.5-6 h; the solvent for centrifugation and washing is ethanol; the temperature for vacuum drying is 60 °C; the vacuum drying time is 10-24 h.

[0009] Among them, the mass ratio of ZNMA, chitosan, acetic acid, and deionized water in S2 is 0-0.5: 0.6-0.8: 0.1-0.2: 15-25; the stirring time is 0.5-6 h; the freezing temperature is 0--60 °C; the freeze-drying time is 48-72 h.

[0010] Among them, the inert gas in S3 is N2 or Ar; the heat treatment temperature is 600-900 °C; the heat treatment time is 0.5-4 h.

[0011] An aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF prepared by the above preparation method.

[0012] An application of an aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF, which is used as a microwave absorbing material in the fields of radar, infrared, and radar-infrared compatible stealth technologies.

[0013] Compared with the closest prior art, the present invention has the following beneficial effects: 1. After carbonization of the present invention, the MOF derivatives are uniformly dispersed in the carbon matrix as multi-level polarization centers. At the same time, aramid fibers bridge chitosan carbon sheets to form a highly polarized active interface, enhancing the conductance loss and inducing multiple reflections. While achieving high microwave absorbing performance, it can also be applied to the field of infrared stealth. 2. The aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF prepared by the present invention has excellent electromagnetic wave absorption performance. At 2.7 mm, the best reflection loss can reach -65.69 dB@9.92 GHz. When the matching thickness is 2.1 mm, the maximum bandwidth is 6.32 GHz. At the same time, the present invention has good thermal management performance. After the sample with a thickness of 2 cm is heated at 135 °C for 60 minutes, its surface temperature is still as low as 41.3 °C. Description of the Drawings

[0014] Figure 1 It is the surface and cross-section SEM images of the aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF in Example 3; Figure 2 It is the electromagnetic parameter diagram of the aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF in Example 3; Figure 3 It is the 3D reflection loss diagram of the aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF in Examples 1, 2, 3, and 4; Figure 4 It is the reflection loss diagram of the aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF in Example 3 at different thicknesses; Figure 5 It is the infrared thermal imaging diagram of the aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF in Example 3 taken at different times on a heating table at 135 °C. Detailed Embodiments

[0015] The technical solutions of the present invention will be further described in detail below with specific embodiments. The following embodiments are only for illustrative explanation of the present invention and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention. Please refer to Figures 1-5 : Example 1 A preparation method of an aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF includes the following steps: S1: Dissolve 0.15 g of aramid fiber, 0.59 g of zinc nitrate hexahydrate, 0.24 g of nickel chloride hexahydrate, 4.45 g of dimethylimidazole, and 0.01 g of cetyltrimethylammonium bromide in 100 ml of deionized water, mix and stir for 1 h, then carry out hydrothermal reaction at 150 °C for 10 h. After centrifugation and ethanol washing, take the precipitate and vacuum dry it at 60 °C for 12 h to obtain NiZn-MOF@aramid fiber, i.e., ZNMA; S2: Dissolve 0 g of NiZn-MOF@aramid fiber and 0.675 g of chitosan in 20 ml of deionized water, stir and mix for 1 h, while dropping acetic acid to form an aerogel precursor, then freeze at -60 °C, and then freeze-dry for 48 h to obtain NiZn-MOF@aramid fiber / chitosan aerogel; S3: Heat-treat the sample in step S2 under a N2 atmosphere at 700 °C for 2 h to obtain NiZn-MOF@aramid fiber / chitosan carbon aerogel, namely ZNCA.

[0016] Example 2 A preparation method of aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF, comprising the following steps: S1: Dissolve 0.15 g of aramid fiber, 0.60 g of zinc nitrate hexahydrate, 0.24 g of nickel chloride hexahydrate, 4.45 g of dimethylimidazole, and 0.01 g of cetyltrimethylammonium bromide in 100 ml of deionized water, mix and stir for 1 h, then carry out hydrothermal reaction at 150 °C for 10 h, after centrifugation and ethanol washing, take the precipitate and vacuum dry at 60 °C for 12 h to obtain NiZn-MOF@aramid fiber, namely ZNMA; S2: Dissolve 0.112 g of NiZn-MOF@aramid fiber and 0.675 g of chitosan in 20 ml of deionized water, stir and mix for 1 h, while dropping acetic acid to form an aerogel precursor, then freeze at -60 °C, and then freeze-dry for 48 h to obtain NiZn-MOF@aramid fiber / chitosan aerogel; S3: Heat-treat the sample in step S2 under a N2 atmosphere at 700 °C for 2 h to obtain NiZn-MOF@aramid fiber / chitosan carbon aerogel, namely ZNCA.

[0017] Example 3 A preparation method of aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF, comprising the following steps: S1: Dissolve 0.15 g of aramid fiber, 0.592 g of zinc nitrate hexahydrate, 0.24 g of nickel chloride hexahydrate, 4.45 g of dimethylimidazole, and 0.01 g of cetyltrimethylammonium bromide in 100 ml of deionized water, mix and stir for 1 h, then carry out hydrothermal reaction at 150 °C for 10 h, after centrifugation and ethanol washing, take the precipitate and vacuum dry at 60 °C for 12 h to obtain NiZn-MOF@aramid fiber, namely ZNMA; S2: Dissolve 0.199 g of NiZn-MOF@aramid fiber and 0.675 g of chitosan in 20 ml of deionized water, stir and mix for 1 h, while dropping acetic acid to form an aerogel precursor, then freeze at -60 °C, and then freeze-dry for 48 h to obtain NiZn-MOF@aramid fiber / chitosan aerogel; S3 subjects the sample in step S2 to heat treatment at 700 °C for 2 h under a N2 atmosphere to obtain NiZn-MOF@aramid fiber / chitosan carbon aerogel, namely ZNCA.

[0018] Example 4 A preparation method of aramid fiber / chitosan carbon aerogel loaded with NiZn-MOF includes the following steps: S1: Dissolve 0.15 g of aramid fiber, 0.595 g of zinc nitrate hexahydrate, 0.24 g of nickel chloride hexahydrate, 4.45 g of dimethylimidazole, and 0.01 g of cetyl dimethyl ammonium bromide in 100 ml of deionized water, mix and stir for 1 h, then carry out hydrothermal reaction at 150 °C for 10 h, centrifuge, wash with ethanol, and take the precipitate to be vacuum dried at 60 °C for 12 h to obtain NiZn-MOF@aramid fiber, namely ZNMA; S2: Mix 0.383 g of NiZn-MOF@aramid fiber with 0.675 g of chitosan in 20 ml of deionized water, stir and mix for 1 h, and simultaneously drop in acetic acid to form an aerogel precursor, then freeze at -60 °C and then freeze-dry for 48 h to obtain NiZn-MOF@aramid fiber / chitosan aerogel; S3: Subject the sample in step S to heat treatment at 700 °C for 2 h under a N2 atmosphere to obtain NiZn-MOF@aramid fiber / chitosan carbon aerogel, namely ZNCA.

[0019] Microscopic morphology and performance of the carbon aerogels prepared in Examples 1-4 were characterized. Figure 1 a is the surface SEM image of the original NiZn-MOF@aramid fiber / chitosan carbon aerogel, Figure 1 b is the cross-sectional SEM image of the original NiZn-MOF@aramid fiber / chitosan carbon aerogel. It can be observed that nano-Ni3ZnC0.7 particles with a diameter of about 200 nm are uniformly loaded on the surface of the aramid fiber after carbonization, effectively enhancing the conductive anisotropy caused by the stacking of pure chitosan carbon sheets, and the interface between the MOF-derived porous carbon and the fiber is tightly combined without obvious cracks or voids, confirming the enhancement effect of the interface bridging and in-situ growth strategies on the interface stability.

[0020] Figure 2are the electromagnetic parameters of NiZn-MOF@aramid fiber / chitosan carbon aerogel. With the increase in the number of ZNMA alloy capsules, there is a significant increase in ε' and ε". The average value of ε' increases from 5.8 to 7.8 to 8.4 to 9.1 in the range of 2 - 18 GHz, and the average value of ε" increases from 2.0 to 3.0 to 3.83 to 7.4 in the range of 2 - 18 GHz. The increased value of ε' is due to the abundant heterogeneous interfaces between ZNMF-derived carbides and chitosan carbon layers. Since the main components after carbonization are Ni3ZnC0.7 alloy phase and graphite carbon, although Ni3ZnC0.7 contains Ni, the magnetic moment arrangement of Ni in its alloy structure is restricted, resulting in relatively weak overall magnetism. And since the μ of graphite carbon itself is approximately 1, which dominates the magnetic response of the composite material, the real part of the magnetic permeability of the samples in Examples 1, 2, 3, and 4 is basically 1, and the imaginary part is basically 0, as Figure 2 shown in

[0021] Figure 3 a - d are the 3D reflection loss diagrams of NiZn-MOF@aramid fiber / chitosan carbon aerogel in Examples 1, 2, 3, and 4. The electromagnetic wave absorption ability of each sample can be evaluated more intuitively. It can be observed that the 3D absorption valley of pure chitosan-derived carbon is relatively shallow, while the absorption valleys of the three ZNCAs are deeper, indicating that ZNCA has better electromagnetic wave absorption ability than pure carbon.

[0022] Figure 4 are the reflection losses of NiZn-MOF@aramid fiber / chitosan carbon aerogel with different thicknesses in Example 3. As Figure 4 shown, the best reflection loss of -65.69 dB@9.92 GHz can be obtained at 2.7 mm; the maximum bandwidth of 6.32 GHz is at 2.1 mm.

[0023] Figure 5 are the infrared thermal imaging diagrams of NiZn-MOF@aramid fiber / chitosan carbon aerogel in Example 3 taken at different times on a heating table at 135 °C. It can be observed that after heating for 5 minutes, the surface temperature of ZNCA reaches 37.37 °C. After continuing to heat for some time, the surface temperature of ZNCA reaches 38.5 °C, 39.2 °C, 40.8 °C, 41.1 °C in turn. Finally, when the heating time reaches 60 minutes, the surface temperature of ZNCA is still as low as 41.3 °C. It can be seen that with the increase in heating time, the heating rate of the sample surface temperature decreases, indicating that ZNCA has excellent thermal insulation performance.

[0024] Table 1 Performance comparison table of ZNCA prepared in Examples 1 - 4 It can be seen from the table that Example 3 has the optimal performance. At 2.7 mm, Example 3 can obtain the best reflection loss of -65.69 dB @ 9.92 GHz; at 2.1 mm, the maximum bandwidth is 6.32 GHz.

[0025] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing NiZn-MOF-loaded aramid fiber / chitosan carbon aerogel, characterized in that: The following steps are included: S1: Induce NiZn-MOF nickel-zinc metal organic framework to grow in situ on aramid fiber; obtain NiZn-MOF loaded aramid fiber, NiZn-MOF@aramid fiber, namely ZNMA; S2: ZNMA and chitosan were dissolved in deionized water and stirred and mixed, and acetic acid was added dropwise to form an aerogel precursor, and then freeze-dried to obtain NiZn-MOF@aramid fiber / chitosan aerogel; S3: The sample in S2 is heat treated under an inert gas atmosphere to obtain NiZn-MOF@aramid fiber / chitosan carbon aerogel, namely ZNCA.

2. The method for preparing a carbon aerogel in which NiZn-MOF is loaded on aramid fiber and chitosan according to claim 1, characterized in that: The specific steps of inducing the in-situ growth of NiZn-MOF on aramid fiber in S1 are: dissolving aramid fiber, zinc nitrate hexahydrate, nickel chloride hexahydrate, dimethylimidazole and hexadecyldimethylammonium bromide in deionized water, mixing and stirring, and then performing a hydrothermal reaction, centrifuging, washing, and vacuum drying the precipitate to obtain NiZn-MOF@aramid fiber, namely ZNMA.

3. The method for preparing NiZn-MOF loaded aramid fiber / chitosan carbon aerogel according to claim 2, characterized in that: The mass ratio of the aramid fiber, zinc nitrate hexahydrate, nickel chloride hexahydrate, dimethyl imidazole, hexadecyl dimethyl ammonium bromide and deionized water is 0.1-0.2: 0.59-0.6: 0.23-0.25: 4.3-4.6: 0.005-0.015: 90-120.

4. The method for preparing NiZn-MOF loaded aramid fiber / chitosan carbon aerogel according to claim 2, characterized in that: The hydrothermal reaction temperature is 130-180° C., and the reaction time is 5-15 hours. The aramid fiber, zinc nitrate hexahydrate, nickel chloride hexahydrate, dimethylimidazole and hexadecyldimethylammonium bromide are dissolved in deionized water and stirred for 0.5-6 hours. The solvent for centrifugal washing is ethanol. The vacuum drying temperature is 60° C. and the vacuum drying time is 10-24 hours.

5. The method for preparing NiZn-MOF loaded aramid fiber / chitosan carbon aerogel according to claim 1, characterized in that: The mass ratio of ZNMA, chitosan, acetic acid and deionized water in S2 is 0-0.5: 0.6-0.8: 0.1-0.2: 15-25; the stirring time is 0.5-6 h; the freezing temperature is 0--60°C; and the freeze-drying time is 48-72 h.

6. The method for preparing NiZn-MOF loaded aramid fiber / chitosan carbon aerogel according to claim 1, characterized in that: The inert gas in S3 is N2 or Ar; the heat treatment temperature is 600-900°C; and the heat treatment time is 0.5-4h.

7. A NiZn-MOF loaded aramid fiber / chitosan carbon aerogel prepared according to any one of claims 1 to 6.

8. An application of the NiZn-MOF loaded aramid fiber / chitosan carbon aerogel as claimed in claim 7, characterized in that: It is used as an absorbing material in the fields of radar, infrared, and radar-infrared compatible stealth technology.

Images