Aramid-based MXene-coated Co3O4 composite wave-absorbing fiber as well as preparation method and application thereof
By preparing aramid-based MXene@Co3O4 composite microwave absorbing fibers and adopting a core-sheath structure design, the problem of insufficient deformation adaptability and stability of existing microwave absorbing materials in wearable devices is solved, achieving high mechanical strength and multi-spectral microwave absorption function.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG TRUELOVE CARPET IND SCI & TECH
- Filing Date
- 2026-03-12
- Publication Date
- 2026-05-12
AI Technical Summary
Existing microwave absorbing materials are insufficient to meet the needs of wearable devices in terms of deformation adaptability and wearing comfort, and the coating has weak adhesion, insufficient stability, and significantly reduced mechanical properties.
The preparation method of aramid-based MXene@Co3O4 composite microwave absorbing fiber adopts the coaxial wet spinning technology to combine MXene and Co3O4 powder with aramid nanofibers to form a core-sheath structure fiber. MXene provides strong dielectric loss, aramid nanofibers provide mechanical support, and Co3O4 optimizes impedance matching.
It achieves high mechanical strength and multi-spectral wave absorption function, solves the problem of easy shedding of wave absorbing agent, and provides excellent mechanical properties and environmental stability, making it suitable for wearable integrated electromagnetic devices.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electromagnetic wave absorbing materials technology, and particularly relates to an aramid-based MXene@Co3O4 composite wave absorbing fiber, its preparation method and application. Background Technology
[0002] With the rapid development of portable and wearable smart devices, higher demands are being placed on electromagnetic wave absorbing materials, including lightweight flexibility, functional integration, and high stability. Currently, most widely used absorbing materials exist in powder or bulk form, which is insufficient to meet the practical needs of complex devices in terms of deformation adaptability and wearability comfort. One-dimensional functional fibers, with their flexible structural design and tunable electrical properties, have become one of the ideal candidate materials for constructing wearable absorbing devices. However, existing processes rely on modifying flexible fiber substrates with conductive components through surface coating, which generally suffers from weak coating adhesion, insufficient stability, and significant degradation of mechanical properties. The key to achieving high-performance fiber-based absorbing materials lies in the orderly assembly of nanoscale functional units into macroscopic fibers with hierarchical structures. Developing tunable electromagnetic functional fibers that possess both excellent mechanical properties and environmental stability is of great significance for promoting the development of wearable integrated electromagnetic devices. Summary of the Invention
[0003] In view of this, the purpose of the present invention is to provide an aramid-based MXene@Co3O4 composite microwave absorbing fiber, its preparation method and application.
[0004] This invention provides a method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fibers, comprising the following steps:
[0005] Mix MXene / dimethyl sulfoxide dispersion with aramid nanofiber / dimethyl sulfoxide dispersion, disperse evenly, and defoam by ultrasonication to obtain spinning solution A; place Co3O4 powder into aramid nanofiber / dimethyl sulfoxide dispersion and stir, and defoam by ultrasonication to obtain spinning solution B.
[0006] The spinning solution A and spinning solution B are coaxially wet-spun and the fibers are formed and dried to obtain aramid-based MXene@Co3O4 composite microwave absorbing fibers.
[0007] Preferably, the MXene / dimethyl sulfoxide dispersion is prepared according to the following method:
[0008] Lithium fluoride was dissolved in hydrochloric acid, and Ti3AlC2 powder was added. The mixture was stirred at a constant temperature to obtain solution A. Solution A was mixed with water and centrifuged. The centrifugation / washing was repeated, and the precipitate was collected. The precipitate was dispersed in dimethyl sulfoxide for solvent exchange. After shaking and mixing, the mixture was centrifuged to obtain MXene / dimethyl sulfoxide dispersion.
[0009] The aramid nanofiber / dimethyl sulfoxide dispersion was prepared by the following method:
[0010] Aramid fibers, potassium hydroxide, water, and dimethyl sulfoxide were mixed and stirred to obtain an aramid nanofiber / dimethyl sulfoxide dispersion.
[0011] Preferably, the mass ratio of lithium fluoride to hydrochloric acid is 1:12~13;
[0012] The mass ratio of Ti3AlC2 powder to lithium fluoride is 1:1.5~1.7.
[0013] Preferably, the stirring temperature under constant temperature is 30~50℃, and the stirring time is 24~48h;
[0014] The centrifuge speed is 3500~5000 rpm;
[0015] Repeat centrifugation / washing until the pH of the supernatant is 6-7.
[0016] Preferably, the mass ratio of aramid fiber to potassium hydroxide is 1:1.45~1.55;
[0017] The stirring time is 4 to 8 hours.
[0018] Preferably, the Co3O4 powder is prepared by the following method:
[0019] Cobalt nitrate hexahydrate was dissolved in methanol to form a homogeneous solution A; 2-methylimidazole was dissolved in methanol to prepare solution B; solution B was poured into solution A and mixed evenly, and a solvothermal reaction was carried out. The precipitate was collected, washed, dried and calcined to obtain Co3O4 powder.
[0020] Preferably, the temperature of the solvothermal reaction is 120~160℃ and the time is 1~3h;
[0021] The calcination temperature is 350~400℃, and the time is 1~3h.
[0022] Preferably, the mass ratio of the MXene / dimethyl sulfoxide dispersion to the aramid nanofiber / dimethyl sulfoxide dispersion is 1:0.5~4;
[0023] The time for uniformly dispersing spinning solution A is 4~12h.
[0024] This invention provides a composite absorbing fiber, which is prepared by the method described in the above technical solution;
[0025] The composite absorbing fiber has a core-sheath structure;
[0026] The core layer is made of MXene and aramid nanofiber composite;
[0027] The sheath was made of a composite of Co3O4 and aramid nanofibers.
[0028] This invention provides an application of the composite absorbing fiber prepared by the preparation method described above in a wearable integrated electromagnetic device.
[0029] This invention provides a method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fibers, comprising the following steps: mixing MXene / dimethyl sulfoxide dispersion with aramid nanofiber / dimethyl sulfoxide dispersion, uniformly dispersing, and ultrasonically defoaming to obtain spinning solution A; placing Co3O4 powder into the aramid nanofiber / dimethyl sulfoxide dispersion and stirring, ultrasonically defoaming to obtain spinning solution B; coaxially wet spinning and fiber forming of spinning solutions A and B, and drying to obtain aramid-based MXene@Co3O4 composite microwave absorbing fibers. The composite microwave absorbing fiber prepared by this method has a core-sheath structure. The core layer is a composite system of MXene and aramid nanofibers, where MXene provides strong dielectric loss, and aramid nanofibers serve as a continuous phase skeleton, providing basic mechanical support to the fiber; the sheath layer is composed of Co3O4 and aramid nanofibers, utilizing the magnetic loss characteristics of Co3O4 to effectively optimize overall impedance matching and broaden the absorption bandwidth; therefore, this composite fiber has excellent mechanical strength and multi-spectral microwave absorption function. Attached Figure Description
[0030] Figure 1 This is a scanning electron microscope image of the aramid-based MXene@Co3O4 composite microwave absorbing fiber prepared in Example 2 of the present invention;
[0031] Figure 2 The stress-strain curves of the aramid-based MXene@Co3O4 composite microwave absorbing fibers prepared in Examples 1-3 of this invention are shown.
[0032] Figure 3 Two-dimensional reflection loss diagrams of the aramid-based MXene@Co3O4 composite microwave absorbing fibers prepared in Examples 1-3 of this invention;
[0033] Figure 4 The stress-strain curves and two-dimensional reflection loss diagrams of the aramid-based MXene / Co3O4 composite microwave absorbing fibers prepared in the comparative example of this invention are shown. Detailed Implementation
[0034] This invention provides a method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fibers, comprising the following steps:
[0035] Mix MXene / dimethyl sulfoxide dispersion with aramid nanofiber / dimethyl sulfoxide dispersion, stir, and defoam by ultrasonication to obtain spinning solution A; place Co3O4 powder into aramid nanofiber / dimethyl sulfoxide dispersion, stir, and defoam by ultrasonication to obtain spinning solution B.
[0036] The spinning solution A and spinning solution B are coaxially wet-spun and the fibers are formed and dried to obtain aramid-based MXene@Co3O4 composite microwave absorbing fibers.
[0037] This invention proposes a dual-space-confined wet spinning strategy to manufacture MXene / ANF@Co3O4 / ANF (MXene@Co3O4) core-sheath structure fibers. The dense and ordered arrangement of MXene nanosheets constructs a continuous conductive network and forms a continuous built-in electric field, which facilitates efficient charge migration and interfacial charge accumulation, thereby improving dielectric loss. Simultaneously, the sheath fibers not only act as a physical barrier to inhibit MXene oxidation but also precisely regulate impedance matching. The resulting MXene@Co3O4 fibers exhibit excellent mechanical strength and reliability under various harsh conditions, solving the problem of easy absorbing agent shedding. More importantly, by utilizing the intrinsic anisotropy of the fiber material and the synergistic electromagnetic properties of MXene@Co3O4, the fabric is endowed with the ability to intelligently switch and regulate its "wave absorption-transmission" performance through simple arrangement and orientation.
[0038] The MXene / dimethyl sulfoxide dispersion described in this invention is prepared by the following method:
[0039] Lithium fluoride was dissolved in hydrochloric acid, and Ti3AlC2 powder was added. The mixture was stirred at a constant temperature to obtain solution A. Solution A was mixed with water and centrifuged. The centrifugation / washing was repeated, and the precipitate was collected. The precipitate was dispersed in dimethyl sulfoxide for solvent exchange. After shaking and mixing, the mixture was centrifuged to obtain MXene / dimethyl sulfoxide dispersion.
[0040] In this invention, the dissolution of lithium fluoride in hydrochloric acid is preferably carried out under magnetic stirring conditions; the magnetic stirring time is 30-60 min, specifically 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min. In this invention, the mass ratio of lithium fluoride to hydrochloric acid is 1:12-13, specifically 1:12.1, 1:12.2, 1:12.3, 1:12.4, 1:12.5, 1:12.6, 1:12.7, 1:12.8, 1:12.9, or 1:13. The mass ratio of Ti3AlC2 powder to lithium fluoride is 1:1.5-1.7.
[0041] When preparing solution A, the stirring temperature under constant temperature is 30~50℃, specifically 30℃, 35℃, 40℃, 45℃ or 50℃; the time is 24~48h, specifically 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h or 48h.
[0042] In this invention, solution A is mixed with water and then centrifuged, preferably with deionized water; the centrifugation speed is 3500~5000 rpm, specifically 3500 rpm, 4000 rpm, 4500 rpm, or 5000 rpm. This invention lowers the pH of the supernatant by repeated centrifugation / washing, preferably by repeating centrifugation / washing until the pH of the supernatant is 6~7. The precipitate is collected, and this invention preferably disperses it in dimethyl sulfoxide for solvent exchange, shakes to mix, and then centrifuges; this solvent exchange centrifugation process is repeated to obtain an MXene / dimethyl sulfoxide dispersion.
[0043] The aramid nanofiber / dimethyl sulfoxide dispersion described in this invention is preferably prepared according to the following method:
[0044] Aramid fibers, potassium hydroxide, water and dimethyl sulfoxide were mixed and stirred to obtain an aramid nanofiber / dimethyl sulfoxide dispersion, denoted as ANF / dimethyl sulfoxide dispersion.
[0045] The present invention preferably involves shredding aramid fibers, washing and drying them, and then adding them to dimethyl sulfoxide along with potassium hydroxide and deionized water. The present invention also preferably involves ultrasonically washing the aramid fibers sequentially with methanol and deionized water for 30-60 minutes, specifically 30, 35, 40, 45, 50, 55, or 60 minutes. The mass ratio of aramid fibers to potassium hydroxide is 1:1.45-1.55, specifically 1:1.45, 1:1.50, or 1:1.55. In a specific embodiment, the amount of aramid fiber used is 2-4 g. The stirring time is 4-8 hours, specifically 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, or 8 hours.
[0046] The Co3O4 powder described in this invention is prepared by the following method:
[0047] Cobalt nitrate hexahydrate was dissolved in methanol to form a homogeneous solution A; 2-methylimidazole was dissolved in methanol to prepare solution B; solution B was poured into solution A and mixed evenly, and a solvothermal reaction was carried out. The precipitate was collected, washed, dried and calcined to obtain Co3O4 powder.
[0048] In this invention, the mass ratio of cobalt nitrate hexahydrate to 2-methylimidazole is 1:1.95~2.05, preferably 1:2. Preferably, solution B is rapidly poured into solution A, mixed thoroughly, and subjected to a solvothermal reaction. The temperature of the solvothermal reaction is 120~160℃, specifically 120℃, 130℃, 140℃, 150℃, or 160℃; the reaction time is 1~3h, specifically 1h, 1.5h, 2.0h, 2.5h, or 3h. After the solvothermal reaction is complete, the precipitate is collected, washed, dried, and calcined to obtain Co3O4 powder. The calcination temperature is 350~400℃, specifically 350℃, 360℃, 370℃, 380℃, 390℃, or 400℃; the calcination time is 1~3h, specifically 1h, 1.5h, 2.0h, 2.5h, or 3h.
[0049] In this invention, the mass ratio of the MXene / dimethyl sulfoxide dispersion to the aramid nanofiber / dimethyl sulfoxide dispersion is 1:(0.5~4), specifically 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, or 1:4.0. After mixing, the mixture is uniformly dispersed by stirring or ultrasonic dispersion; the uniform dispersion time is 4~12 hours, specifically 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.
[0050] In this invention, the molar ratio of the Co3O4 / dimethyl sulfoxide dispersion to the aramid nanofiber / dimethyl sulfoxide dispersion is 1:(1~5), specifically 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5. After mixing, the mixture is uniformly dispersed by stirring or ultrasonic dispersion; the uniform dispersion time is 4~12 hours, specifically 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.
[0051] In this invention, aramid nanofibers are used as a key component, continuously distributed in the core and sheath layers. Their abundant polar groups form a robust hydrogen bond network, significantly enhancing interlayer bonding and stress transfer efficiency. This fundamentally solves the problem of performance degradation caused by interfacial peeling in traditional electromagnetic absorbing coatings. Simultaneously, the aramid nanofibers fully inherit the inherent high strength, high modulus, and high-temperature resistance of aramid fibers, enabling the composite fiber to achieve efficient electromagnetic protection while simultaneously possessing excellent mechanical load-bearing capacity, environmental adaptability, and processability, laying a material foundation for its application in flexible protective equipment. During the preparation process, the polar solvent dimethyl sulfoxide (DMSO) plays a crucial role. Through intermolecular forces, it effectively improves the dispersion stability of MXene and aramid nanofibers in the spinning solution, inhibits nanosheet aggregation, thereby enhancing the interfacial bonding strength of the composite system and the final mechanical properties of the fiber, and synergistically optimizing its electromagnetic wave absorption efficiency.
[0052] This invention involves coaxial wet spinning and fiber forming of spinning solution A and spinning solution B, followed by drying to obtain aramid-based MXene@Co3O4 composite microwave absorbing fibers. In this invention, spinning solution A and spinning solution B are injected into a coagulation bath using a coaxial needle; the coagulation bath is a 5wt% ammonium chloride aqueous solution or ethanol; the needle size is 20~23G / 15~17G; the extrusion speed of the spinning solution is 10~30mL / h, specifically 10 mL / h, 15 mL / h, 20 mL / h, 25 mL / h, or 30 mL / h. Preferably, deionized water is used to wash away the solvent on the fiber surface. The fibers are collected using a winding device. Preferably, drying is carried out in an oven; the drying temperature is 40~80℃, specifically 40℃, 50℃, 60℃, 70℃, or 80℃.
[0053] The aramid-based MXene@Co3O4 composite microwave absorbing fiber prepared in this invention is a coaxial composite fiber with MXene as the core functional material and Co3O4 as the sheath functional material. It employs an innovative core-sheath structure design, possessing both excellent mechanical properties and tunable electromagnetic wave absorption capabilities. In this structure, the core layer is a composite system of MXene and aramid nanofibers, where MXene provides strong dielectric loss, and the aramid nanofibers serve as a continuous phase framework, providing basic mechanical support for the fiber. The sheath layer is composed of Co3O4 and aramid nanofibers, utilizing the magnetic loss characteristics of Co3O4 to effectively optimize overall impedance matching, broaden the absorption bandwidth, and achieve a multi-spectral microwave absorbing functional fiber that combines flexibility and environmental stability.
[0054] The preparation method provided by this invention, based on a simple process and universal equipment, offers a feasible technical path for the efficient mass production of this high-performance microwave absorbing fiber, and has broad application prospects. The preparation method described in this invention, based on a simple process and universal equipment, achieves efficient mass production, providing a feasible technical path for the industrial application of microwave absorbing fibers, and has good application prospects.
[0055] The present invention also provides a composite absorbing fiber, which is prepared by the preparation method described in the above technical solution;
[0056] The composite absorbing fiber has a core-sheath structure;
[0057] The core layer is made of MXene and aramid nanofiber composite;
[0058] The sheath was made of a composite of Co3O4 and aramid nanofibers.
[0059] The aramid-based MXene@Co3O4 composite absorbing fiber of this invention employs an innovative core-sheath structure design, combining excellent mechanical properties with tunable electromagnetic wave absorption capabilities. In this structure, the core layer is a composite system of MXene and aramid nanofibers, where MXene provides strong dielectric loss, and aramid nanofibers serve as a continuous phase framework, providing basic mechanical support for the fiber. The sheath layer is composed of Co3O4 and aramid nanofibers, utilizing the magnetic loss characteristics of Co3O4 to effectively optimize overall impedance matching and broaden the absorption bandwidth.
[0060] The present invention also provides an application of the composite absorbing fiber prepared by the preparation method described above in a wearable integrated electromagnetic device.
[0061] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides an aramid-based MXene@Co3O4 composite microwave absorbing fiber, its preparation method, and its applications. However, these descriptions should not be construed as limiting the scope of protection of the present invention.
[0062] Example 1
[0063] A method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fiber includes the following steps:
[0064] (1) Preparation of MXene dispersion
[0065] Add 4g of lithium fluoride to 50mL of 9M hydrochloric acid and stir magnetically for 30min until completely dissolved. Then, slowly add 2.5g of Ti3AlC2 powder to the reaction system, and stir the mixture at a constant temperature of 35℃ for 30h to obtain solution A;
[0066] Add solution A to deionized water and centrifuge. Wash the supernatant at 3500 rpm to lower the pH to 6. Add dimethyl sulfoxide to the precipitate for solvent exchange. Shake for 30 min to assist in mixing. Repeat centrifugation for 10 min to obtain a 40 mg / mL MXene / dimethyl sulfoxide dispersion.
[0067] (2) Preparation of aramid nanofiber dispersion
[0068] Aramid fibers were cut into small pieces and ultrasonically cleaned successively with methanol and deionized water for 30 min each. After cleaning, they were dried in an oven at 60℃ for 12 h. 2.4 g of the dried aramid fibers, 3.6 g of potassium hydroxide, and 4 mL of deionized water were added to 100 mL of dimethyl sulfoxide and stirred for 4 h to obtain a 20 mg / mL aramid nanofiber / dimethyl sulfoxide dispersion.
[0069] (3) Preparation of Co3O4 powder
[0070] 3.32 g of cobalt nitrate hexahydrate was dissolved in 100 mL of methanol to form a homogeneous solution A; separately, 1.56 g of 2-methylimidazole was dissolved in 100 mL of methanol to prepare solution B; solution B was quickly poured into solution A and mixed thoroughly, and then subjected to a solvothermal reaction at 120 °C for 2 h. After the reaction was complete, the precipitate was collected, washed, dried, and then calcined in a muffle furnace at 350 °C for 2 h to obtain Co3O4 powder;
[0071] (4) Preparation of aramid-based MXene@Co3O4 composite microwave absorbing fiber
[0072] Mix 1.75 mL of MXene / dimethyl sulfoxide dispersion with 14 g of aramid nanofiber / dimethyl sulfoxide dispersion, stir for 8 h, and ultrasonically defoam for 30 min to obtain spinning solution A with a mass ratio of 1:4 (i.e., the relative content of MXene is 20%).
[0073] Dissolve 0.2g of Co3O4 powder in 8.9mL of dimethyl sulfoxide, place it in 9.8g of aramid nanofiber / dimethyl sulfoxide dispersion, stir for 8h, and ultrasonically defoam for 30min to obtain spinning solution B;
[0074] Spinning solution A and spinning solution B were injected into a 5wt% ammonium chloride coagulation bath using a coaxial needle 21G / 15G. The solvent on the fiber surface was removed by washing with deionized water. The fiber was collected by a winding device and dried in a 60℃ oven for 12 hours to obtain aramid-based MXene@Co3O4 composite microwave absorbing fiber (M2@C).
[0075] Example 2
[0076] A method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fiber includes the following steps:
[0077] (1) Preparation of MXene dispersion
[0078] 4g of lithium fluoride was added to 50mL of 9mol / L hydrochloric acid and magnetically stirred for 30min until completely dissolved. Then, 2.5g of Ti3AlC2 powder was slowly added to the reaction system, and the mixture was stirred at a constant temperature of 35℃ for 30h to obtain solution A.
[0079] Add solution A to deionized water and centrifuge. Wash the supernatant at 3500 rpm to lower the pH to 6. Add dimethyl sulfoxide to the precipitate for solvent exchange. Shake for 30 min to assist in mixing. Repeat centrifugation for 10 min to obtain a 40 mg / mL MXene / dimethyl sulfoxide dispersion.
[0080] (2) Preparation of aramid nanofiber dispersion
[0081] Aramid fibers were cut into small pieces and ultrasonically cleaned successively with methanol and deionized water for 30 min each. After cleaning, they were dried in an oven at 60℃ for 12 h. 2.4 g of dried aramid fibers, 3.6 g of potassium hydroxide, and 4 mL of deionized water were added to 100 mL of dimethyl sulfoxide and stirred for 4 h to obtain a 20 mg / mL aramid nanofiber / dimethyl sulfoxide dispersion.
[0082] (3) Preparation of Co3O4 powder
[0083] 3.32 g of cobalt nitrate hexahydrate was dissolved in 100 mL of methanol to form a homogeneous solution A; separately, 1.56 g of 2-methylimidazole was dissolved in 100 mL of methanol to prepare solution B; solution B was quickly poured into solution A and mixed thoroughly, and then subjected to a solvothermal reaction at 120 °C for 2 h. After the reaction was complete, the precipitate was collected, washed, dried, and then calcined in a muffle furnace at 350 °C for 2 h to obtain Co3O4 powder;
[0084] (4) Preparation of aramid-based MXene@Co3O4 composite microwave absorbing fiber
[0085] Mix 2.80 mL of MXene / dimethyl sulfoxide dispersion with 14 g of aramid nanofiber / dimethyl sulfoxide dispersion, stir for 8 h, and ultrasonically defoam for 30 min to obtain spinning solution A with a mass ratio of 1:2.5 (i.e., the relative content of MXene is 28.6%).
[0086] Dissolve 0.2g of Co3O4 powder in 8.9mL of dimethyl sulfoxide, place it in 9.8g of aramid nanofiber / dimethyl sulfoxide dispersion, stir for 8h, and ultrasonically defoam for 30min to obtain spinning solution B;
[0087] Spinning solution A and spinning solution B were injected into a 5wt% ammonium chloride coagulation bath using a coaxial needle 21G / 15G. The solvent on the fiber surface was removed by washing with deionized water. The fiber was collected by a winding device and dried in a 60℃ oven for 12 hours to obtain aramid-based MXene@Co3O4 composite microwave absorbing fiber (M3@C1).
[0088] Example 3
[0089] A method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fiber includes the following steps:
[0090] (1) Preparation of MXene dispersion
[0091] Add 4g of lithium fluoride to 50mL of 9M hydrochloric acid and stir magnetically for 30min until completely dissolved. Then, slowly add 2.5g of Ti3AlC2 powder to the reaction system, and stir the mixture at a constant temperature of 35℃ for 30h to obtain solution A;
[0092] Add solution A to deionized water and centrifuge. Wash the supernatant at 3500 rpm to lower the pH to 6. Add dimethyl sulfoxide to the precipitate for solvent exchange. Shake for 30 min to assist in mixing. Repeat centrifugation for 10 min to obtain a 40 mg / mL MXene / dimethyl sulfoxide dispersion.
[0093] (2) Preparation of aramid nanofiber dispersion
[0094] Aramid fibers were cut into small pieces and ultrasonically cleaned successively with methanol and deionized water for 30 min each. After cleaning, they were dried in an oven at 60℃ for 12 h. 2.4 g of the dried aramid fibers, 3.6 g of potassium hydroxide, and 4 mL of deionized water were added to 100 mL of dimethyl sulfoxide and stirred for 4 h to obtain a 20 mg / mL aramid nanofiber / dimethyl sulfoxide dispersion.
[0095] (3) Preparation of Co3O4 powder
[0096] 3.32 g of cobalt nitrate hexahydrate was dissolved in 100 mL of methanol to form a homogeneous solution A; separately, 1.56 g of 2-methylimidazole was dissolved in 100 mL of methanol to prepare solution B; solution B was quickly poured into solution A and mixed thoroughly, and then subjected to a solvothermal reaction at 120 °C for 2 h. After the reaction was complete, the precipitate was collected, washed, dried, and then calcined in a muffle furnace at 350 °C for 2 h to obtain Co3O4 powder;
[0097] (4) Preparation of aramid-based MXene@Co3O4 composite microwave absorbing fiber
[0098] 4.67 mL of MXene / dimethyl sulfoxide dispersion was mixed with 14 g of aramid nanofiber / dimethyl sulfoxide dispersion, stirred for 8 h, and ultrasonically defoamed for 30 min to obtain spinning solution A with a mass ratio of 1:1.5 (i.e., a relative MXene content of 40%).
[0099] Dissolve 0.2g of Co3O4 powder in 8.9mL of dimethyl sulfoxide, place it in 9.8g of aramid nanofiber / dimethyl sulfoxide dispersion, stir for 8h, and ultrasonically defoam for 30min to obtain spinning solution B;
[0100] Spinning solution A and spinning solution B were injected into a 5wt% ammonium chloride coagulation bath using a coaxial needle 21G / 15G. The solvent on the fiber surface was removed by washing with deionized water. The fiber was collected by a winding device and dried in a 60℃ oven for 12 hours to obtain aramid-based MXene@Co3O4 composite microwave absorbing fiber (M4@C1).
[0101] Comparative Example
[0102] A method for preparing an aramid-based MXene / Co3O4 composite microwave absorbing fiber includes the following steps:
[0103] (1) Preparation of MXene dispersion
[0104] Add 4g of lithium fluoride to 50mL of 9M hydrochloric acid and stir magnetically for 30min until completely dissolved. Then, slowly add 2.5g of Ti3AlC2 powder to the reaction system, and stir the mixture at a constant temperature of 35℃ for 30h to obtain solution A;
[0105] Add solution A to deionized water and centrifuge. Wash the supernatant at 3500 rpm to lower the pH to 6. Add dimethyl sulfoxide to the precipitate for solvent exchange. Shake for 30 min to assist in mixing. Repeat centrifugation for 10 min to obtain a 40 mg / mL MXene / dimethyl sulfoxide dispersion.
[0106] (2) Preparation of aramid nanofiber dispersion
[0107] Aramid fibers were cut into small pieces and ultrasonically cleaned successively with methanol and deionized water for 30 min each. After cleaning, they were dried in an oven at 60℃ for 12 h. 2.4 g of the dried aramid fibers, 3.6 g of potassium hydroxide, and 4 mL of deionized water were added to 100 mL of dimethyl sulfoxide and stirred for 4 h to obtain a 20 mg / mL aramid nanofiber / dimethyl sulfoxide dispersion.
[0108] (3) Preparation of Co3O4 powder
[0109] 3.32 g of cobalt nitrate hexahydrate was dissolved in 100 mL of methanol to form a homogeneous solution A; separately, 1.56 g of 2-methylimidazole was dissolved in 100 mL of methanol to prepare solution B; solution B was quickly poured into solution A and mixed thoroughly, and then subjected to a solvothermal reaction at 120 °C for 2 h. After the reaction was complete, the precipitate was collected, washed, dried, and then calcined in a muffle furnace at 350 °C for 2 h to obtain Co3O4 powder;
[0110] (4) Preparation of aramid-based MXene / Co3O4 composite microwave absorbing fiber
[0111] 4.67 mL of MXene / dimethyl sulfoxide dispersion was mixed with 14 g of aramid nanofiber / dimethyl sulfoxide dispersion, stirred for 8 h, and ultrasonically defoamed for 30 min to obtain spinning solution A with a mass ratio of 1:1.5 (i.e., the relative content of MXene is 40%).
[0112] Dissolve 0.2g of Co3O4 powder in 8.9mL of dimethyl sulfoxide, place it in 9.8g of aramid nanofiber / dimethyl sulfoxide dispersion, stir for 8h, and ultrasonically defoam for 30min to obtain spinning solution B;
[0113] Spinning solution A and spinning solution B were magnetically stirred for 4 hours to ensure uniform mixing. The mixed spinning solution was then injected into a 5wt% ammonium chloride coagulation bath through a 15G single-axis needle. The fiber surface solvent was removed by washing with deionized water. The fibers were collected by a winding device and dried in a 60℃ oven for 12 hours to obtain aramid-based MXene / Co3O4 composite microwave absorbing fiber.
[0114] Figure 1 The image shows a scanning electron microscope (SEM) image of the aramid-based MXene@Co3O4 composite microwave absorbing fiber prepared in Example 2 of this invention. The core-sheath fiber surfaces are relatively smooth with slight roughness, indicating good fiber formability and uniform Co3O4 distribution on the fiber surface. The fiber cross-section shows a clear layered stacking morphology of MXene, exhibiting a uniform elemental distribution, confirming the structural integrity and uniformity of the sheath-core structure. This spatially ordered arrangement and the double crosslinking network (MXene / ANF-NH4) further demonstrate its effectiveness. + This significantly enhances interface integrity and achieves structural densification. This is crucial for achieving superior mechanical properties (strength and toughness).
[0115] Figure 2 The stress-strain curves of the aramid-based MXene@Co3O4 composite microwave absorbing fibers prepared in Examples 1-3 of this invention show that as the relative content of MXene in the core and sheath fibers increases, the breaking strength and breaking elongation of the fibers both show a continuous decreasing trend. The breaking strength of the composite fiber prepared in Example 2 is 173.59 MPa.
[0116] Figure 3 The image shows the two-dimensional reflection loss diagrams of the aramid-based MXene@Co3O4 composite absorbing fibers prepared in Examples 1-3. In Example 2, the MXene / aramid nanofibers in the core-sheath fiber constitute a conductive path. Therefore, the composite fiber prepared in Example 2 has good absorption performance, with an effective absorption bandwidth of 6.07 GHz and a minimum reflection loss of -55.32 dB.
[0117] Figure 4 The stress-strain curves and two-dimensional reflection loss diagrams of the aramid-based MXene / Co3O4 composite microwave absorbing fiber prepared in the comparative example of this invention are shown. The comparison reveals that the aramid-based MXene / Co3O4 composite fiber has a tensile strength of 127.06 MPa and exhibits no microwave absorption bandwidth at any simulated thickness. Figure 2 , Figure 3 It can be seen that the core-sheath structure composite microwave absorbing fiber prepared by the present invention exhibits superior fracture strength and microwave absorption performance.
[0118] As can be seen from the above embodiments, the present invention provides a method for preparing aramid-based MXene@Co3O4 composite microwave absorbing fibers, comprising the following steps: mixing MXene / dimethyl sulfoxide dispersion with aramid nanofiber / dimethyl sulfoxide dispersion, uniformly dispersing, and ultrasonically defoaming to obtain spinning solution A; placing Co3O4 powder into aramid nanofiber / dimethyl sulfoxide dispersion and stirring, ultrasonically defoaming to obtain spinning solution B; coaxially wet spinning and fiber forming of spinning solution A and spinning solution B, drying to obtain aramid-based MXene@Co3O4 composite microwave absorbing fibers. The composite microwave absorbing fiber prepared by this method has a core-sheath structure. The core layer is a composite system of MXene and aramid nanofibers, wherein MXene provides strong dielectric loss, and aramid nanofibers serve as a continuous phase skeleton, providing basic mechanical support to the fiber; the sheath layer is composed of Co3O4 and aramid nanofibers, utilizing the magnetic loss characteristics of Co3O4 to effectively optimize overall impedance matching and broaden the absorption bandwidth; therefore, the composite fiber has excellent mechanical strength and multi-spectral microwave absorption function.
[0119] This core-sheath structure, through multi-scale interface design, enables aramid nanofibers to be uniformly distributed and continuously formed in both the core and sheath layers. At the mechanical level, the aramid nanofibers serve as the fiber-forming substrate, with their molecular chains bonded by hydrogen and ionic bonds, providing core skeletal support for the fibers. In the core layer, their effective bonding and filling of axially aligned large-diameter MXene particles, while in the sheath layer, they act as a carrier to immobilize Co3O4 nanoflower particles. This interpenetrating network, with aramid nanofibers as bridges, achieves uniform stress transfer between the core and sheath, avoiding localized stress concentration, thus synergistically endowing the composite fiber with high tensile strength and toughness.
[0120] At the electromagnetic functional level, this structure achieves a highly efficient "wave absorption-loss" mechanism. The sheath layer, by introducing a Co3O4 magnetic component, optimizes the matching of dielectric constant and permeability, reducing the initial reflection of electromagnetic waves on the fiber surface. The core layer utilizes MXene to construct a continuous conductive network, forming a gradient loss structure together with the sheath layer. Electromagnetic waves can penetrate deeper into the fiber interior and are efficiently dissipated through the synergistic effect of the macroscopic interface between the core and sheath and the nanoscopic interface of the components: the macroscopic interface induces multiple reflections, while the nanoscopic interface excites strong interfacial polarization, dipole polarization, and magnetic loss. This multi-mechanism synergy ultimately converts electromagnetic wave energy into heat energy, significantly improving the overall wave absorption performance.
[0121] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing an aramid-based MXene@Co3O4 composite microwave absorbing fiber, comprising the following steps: Mix MXene / dimethyl sulfoxide dispersion with aramid nanofiber / dimethyl sulfoxide dispersion, disperse evenly, and defoam by ultrasonication to obtain spinning solution A; place Co3O4 powder into aramid nanofiber / dimethyl sulfoxide dispersion and stir, and defoam by ultrasonication to obtain spinning solution B. The spinning solution A and spinning solution B are coaxially wet-spun and the fibers are formed and dried to obtain aramid-based MXene@Co3O4 composite microwave absorbing fibers.
2. The preparation method according to claim 1, characterized in that, The MXene / dimethyl sulfoxide dispersion was prepared by the following method: Lithium fluoride was dissolved in hydrochloric acid, and Ti3AlC2 powder was added. The mixture was stirred at a constant temperature to obtain solution A. Solution A was mixed with water and centrifuged. The centrifugation / washing was repeated, and the precipitate was collected. The precipitate was dispersed in dimethyl sulfoxide for solvent exchange. After shaking and mixing, the mixture was centrifuged to obtain MXene / dimethyl sulfoxide dispersion. The aramid nanofiber / dimethyl sulfoxide dispersion was prepared by the following method: Aramid fibers, potassium hydroxide, water, and dimethyl sulfoxide were mixed and stirred to obtain an aramid nanofiber / dimethyl sulfoxide dispersion.
3. The preparation method according to claim 2, characterized in that, The mass ratio of lithium fluoride to hydrochloric acid is 1:12~13; The mass ratio of Ti3AlC2 powder to lithium fluoride is 1:1.5~1.
7.
4. The preparation method according to claim 2, characterized in that, The stirring temperature is 30~50℃ and the stirring time is 24~48h under constant temperature. The centrifuge speed is 3500~5000 rpm; Repeat centrifugation / washing until the pH of the supernatant is 6-7.
5. The preparation method according to claim 2, characterized in that, The mass ratio of aramid fiber to potassium hydroxide is 1:1.45~1.55; The stirring time is 4 to 8 hours.
6. The preparation method according to claim 1, characterized in that, The Co3O4 powder was prepared by the following method: Cobalt nitrate hexahydrate was dissolved in methanol to form a homogeneous solution A; 2-methylimidazole was dissolved in methanol to prepare solution B; solution B was poured into solution A and mixed evenly, and a solvothermal reaction was carried out. The precipitate was collected, washed, dried and calcined to obtain Co3O4 powder.
7. The preparation method according to claim 6, characterized in that, The solvothermal reaction is carried out at a temperature of 120~160℃ for a time of 1~3h. The calcination temperature is 350~400℃, and the time is 1~3h.
8. The preparation method according to claim 1, characterized in that, The mass ratio of the MXene / dimethyl sulfoxide dispersion to the aramid nanofiber / dimethyl sulfoxide dispersion is 1:0.5~4; The time for uniformly dispersing spinning solution A is 4~12h.
9. A composite microwave absorbing fiber, prepared by any one of the preparation methods of claims 1 to 8; The composite absorbing fiber has a core-sheath structure; The core layer is made of MXene and aramid nanofiber composite; The sheath was made of a composite of Co3O4 and aramid nanofibers.
10. The application of a composite absorbing fiber prepared by the preparation method according to any one of claims 1 to 8 in a wearable integrated electromagnetic device.