A MXene radar-infrared dual-band compatible flexible material and a preparation method thereof

Abstract

This invention belongs to the field of radar-infrared dual-band compatible materials, specifically relating to an MXene radar-infrared dual-band compatible flexible material and its preparation method. This invention uses patterned MXene material to form a periodic array structure. Utilizing its extremely high conductivity, it is equivalent to a metal in the radar band, thus constructing a novel frequency-selective surface to achieve high radar transmittance. Furthermore, MXene's intrinsic infrared high reflectivity, coupled with the array period and gap dimensions being much larger than the infrared wavelength, means that the proportion of the contact area between MXene and the incident infrared wave directly determines the overall average reflectivity. Therefore, by adjusting the specific dimensions of the MXene units in the array period, the performance of infrared-radar dual-band compatibility can be controlled. This invention achieves high transmittance in the microwave band while maintaining its low emission characteristics in the infrared band, thus providing a novel and customizable material solution for the radar-infrared compatible field.

Description

Technical Field

[0001] This invention belongs to the field of radar-infrared dual-band compatible materials, specifically involving an MXene radar-infrared dual-band compatible flexible material and its preparation method. By preparing patterned MXene materials, it is particularly suitable for scenarios in civil communication, intelligent transportation, and thermal management of electronic equipment where there is a need for coordinated control of X-band radar transmission performance and infrared thermal radiation regulation performance. Background Technology

[0002] Infrared-radar dual-band compatible materials are a cutting-edge research hotspot. The core challenge lies in reconciling the inherent contradiction between infrared suppression and microwave absorption in terms of physical mechanisms. The infrared band aims to achieve low emissivity to reduce the thermal radiation of the target in the infrared band; while the radar band pursues strong absorption and wide bandwidth, requiring low reflection loss while having the widest possible effective absorption bandwidth, ultimately achieving both low infrared emissivity and high radar absorption.

[0003] However, applications requiring high radar transmittance while maintaining infrared radiation modulation necessitate entirely different material design and electromagnetic control strategies, an area with limited research. Existing technologies either fail to address the core issue of performance imbalance between radar and infrared dual bands, or suffer from drawbacks such as complex processes, high costs, difficulties in large-scale production, and poor flexibility.

[0004] Therefore, developing a flexible material that is simple to manufacture, low in cost, can be mass-produced, and can effectively achieve synergistic control of performance in the radar and infrared bands has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems and shortcomings, and to resolve issues such as performance imbalance, high manufacturing costs, and difficulty in large-scale flexible production of existing infrared-radar dual-band compatible flexible materials, this invention provides an MXene radar-infrared dual-band compatible flexible material and its preparation method. By patterning MXene material to form a periodic array structure, performance regulation for infrared-radar dual-band compatibility is achieved.

[0006] An MXene radar-infrared dual-band compatible flexible material, comprising a PET flexible substrate and Ti3C2T x MXene periodic array.

[0007] The Ti3C2T xThe MXene periodic array layer is a periodic conductive array in which MXene units are arranged in a matrix at equal intervals to form different duty cycles. The MXene units are squares with a side length a of 500~5000μm, the gap width w between adjacent units is 50~500μm, and the array period P=a+w is 1 / 5~1 / 20 of the wavelength of the X band (8.2~12.4GHz).

[0008] By precisely controlling (e.g., through screen printing) the period P, unit side length a, and gap width w of the MXene periodic array, periodic conductive arrays with different duty cycles can be formed, thereby achieving coordinated and customized control of the electromagnetic performance of X-band radar and infrared band radar.

[0009] Furthermore, the MXene unit spacing width w ≥ 50 μm, side length a = 300 μm, X-band radar average transmittance ≥ 75%, and infrared band average reflectance ≥ 40%. At this point, the sample has high radar transmittance but correspondingly low infrared reflectance, which can be used in scenarios with high radar transmittance requirements.

[0010] Furthermore, the MXene material is Ti3C2T. x Ti2CT x or Nb2CT x system.

[0011] The above-mentioned method for preparing the MXene radar-infrared dual-band compatible flexible material includes the following steps:

[0012] Step 1: Preparation of MXene precursor;

[0013] MXene dispersions were prepared using a LiF-HCl selective etching method: A Ti3AlC2 MAX phase was used as a precursor and etched with a LiF-HCl mixture at 35–45 °C for 20–28 h to remove the Al atomic layer. The mixture was repeatedly washed with deionized water and centrifuged until the pH of the supernatant reached 5–7. After further treatment with ice-bath sonication and centrifugation, a monolayer Ti3C2 MAX dispersion with a concentration of 5–10 mg / mL was obtained. x MXene dispersion.

[0014] Step 2: Preparation of high-solids-content MXene printing paste;

[0015] Centrifuge the MXene dispersion obtained in step 1 at 8000-12000 rpm for 1-2 hours, discard the supernatant and collect the lower precipitate to obtain a solid content of 120-180 mg / mL. -1 The MXene paste, after being stirred evenly, is allowed to stand to degas, making it suitable for screen printing processes.

[0016] Step 3: Array patterning printing;

[0017] Using a 200-400 mesh screen template with pre-designed array parameters, the MXene paste obtained in step 2 is uniformly coated onto the screen template of the plasma-pretreated PET substrate through a screen printing process, forming a pre-defined Ti3C2T pattern on the substrate surface. x MXene periodic array.

[0018] Step 4: Post-drying and curing treatment;

[0019] The array sample printed in step 3 is first dried at room temperature for 12-24 hours, and then vacuum dried at 30-40°C for 2-4 hours to remove residual solvent, so that the MXene array is tightly bonded to the substrate, and the MXene radar-infrared dual-band compatible flexible material is obtained.

[0020] Furthermore, the screen printing speed is 5~15 mm / s. -1 .

[0021] Radar-infrared dual-band performance regulation mechanism

[0022] X-band radar: The primary principle is the resonant modulation of an equivalent LC circuit using a frequency selective surface (FSS). MXene, a material with extremely high conductivity, can be considered metallic in the radar band. Therefore, patterning MXene into a square periodic array structure effectively influences the incident electromagnetic waves, much like a metallic pattern affects the signal. This periodic MXene pattern achieves high radar transmittance. In the array structure, each MXene conductive unit is equivalent to a lumped inductor, and the gap between adjacent units is equivalent to a lumped capacitance, forming an LC resonant circuit. Increasing the gap width w reduces the equivalent capacitance, thereby improving radar wave transmittance and reducing reflectivity, achieving quantitative control of radar transmittance performance.

[0023] Infrared band: The dominant principle is the area-weighted average reflectance law. The infrared performance in this structure stems from the intrinsic high infrared reflectance (low emissivity) of MXene. Since the array period and gap size are much larger than the infrared wavelength, the proportion of the contact area between MXene and the incident infrared wave directly determines the overall average reflectance. In other words, the infrared reflectance is linearly determined by the area proportion of the MXene conductive region. Reducing the gap width w increases the proportion of the MXene conductive region, thereby improving the infrared reflectance. According to Kirchhoff's thermal radiation law (ε=1-R), precise control of the infrared emissivity can be achieved.

[0024] Cross-band collaborative mechanism: Based on the three-order-of-magnitude wavelength difference between X-band radar waves and infrared waves, partial decoupling of the dual-band electromagnetic response is achieved. Through gradient control of a single array parameter, the radar transmission and infrared thermal radiation control performance are simultaneously optimized, thus resolving the inherent contradiction in dual-band performance.

[0025] In summary, this invention innovatively uses MXene material, commonly used for broadband absorption or uniform shielding, to create a periodic array structure through patterning. Leveraging its extremely high conductivity, which makes it equivalent to metal in the radar band, this periodic MXene pattern is used to construct a novel frequency-selective surface, achieving high radar transmittance. MXene's intrinsic infrared high reflectivity (low emissivity), coupled with the array period and gap dimensions being much larger than the infrared wavelength, means that the proportion of the contact area between MXene and the incident infrared wave directly determines the overall average reflectivity. Therefore, by adjusting the specific dimensions of the MXene units in the array period, infrared-radar dual-band compatible performance can be achieved. This invention achieves high transmittance in the microwave band while maintaining its low emissivity in the infrared band, thus providing a novel and customizable material solution for radar-infrared performance compatibility. Attached Figure Description

[0026] Figure 1 shows optical microscope images of MXene arrays with different gap widths;

[0027] Figure 2 shows the X-band radar transmittance comparison curves of the MXene array and the continuous MXene film;

[0028] Figure 3 shows the infrared reflectance spectra of the MXene array and the continuous MXene film. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0030] Implementation: Fabrication of MXene patterned flexible array materials

[0031] Step 1: Preparation of MXene precursor

[0032] Mix 1.6g LiF with 20mL 9M HCl solution and stir magnetically for 5min until completely dissolved. Slowly add 1g of 400-mesh Ti3AlC2MAX phase powder and etch in a 40℃ water bath with continuous stirring for 24h. After etching, wash the reaction product repeatedly with deionized water and centrifuge at 4000rpm until the pH of the supernatant is 6. Then sonicate in an ice bath at 200W for 15min, followed by centrifugation at 3500rpm for 15min. Collect the supernatant to obtain a monolayer Ti3C2T with a concentration of 8mg / mL. x The MXene dispersion exhibited a significant Tyndall effect after dilution, confirming that the nanosheets were uniformly dispersed.

[0033] Step 2: Preparation of MXene Printing Paste

[0034] The above MXene dispersion was centrifuged at 10,000 rpm for 1 hour. After discarding the supernatant, the lower precipitate was collected, yielding a solid content of 150 mg / mL. -1 The MXene paste was obtained to be suitable for screen printing processes.

[0035] Step 3: Array patterning printing

[0036] A 300-mesh screen template was selected, with a checkerboard-like periodic array pattern. The unit side length a = 300 μm, and the gap width between adjacent units w = 50 μm. A 100 μm thick PET substrate was used, treated with plasma for 3 minutes, and then fixed on the printing table. The printing parameters were set as follows: squeegee pressure 0.2 MPa, printing speed 10 mm / s. -1 The MXene paste is evenly coated onto the screen template using a screen printing machine to form a pre-set checkerboard array pattern on the surface of the PET substrate, and then dried at room temperature (25°C) for 20 hours.

[0037] Step 4: Post-drying and curing treatment

[0038] The printed sample was placed in a room temperature environment and dried for another 3 hours to allow the MXene array to fully bond with the PET substrate, thus obtaining the MXene patterned flexible array material.

[0039] Performance Tests and Results

[0040] Structural morphology: such as Figure 1 As shown, a stable array gap cannot be formed when the gap is 30μm. Only when the gap is greater than 50μm can a relatively clear array gap be obtained. Therefore, when designing MXene screen printing patterns, the array gap must be greater than 50μm.

[0041] Radar performance: As shown in Figure 2, the average radar transmittance of the sample is greater than 75% in the GHz X band, as tested by a vector network analyzer (VNA). Compared with continuous MXene films (transmittance of continuous films in the same band is <0.01%), the radar transmittance of this sample is improved by more than 4 orders of magnitude, and the reflectivity is significantly reduced, achieving excellent radar transmission performance.

[0042] Infrared performance: As shown in Figure 3, the average infrared reflectance of the MXene sample is greater than 40%, maintaining the excellent low infrared emissivity and infrared thermal radiation modulation characteristics of MXene material.

[0043] This invention achieves precise customization of the radar-infrared dual-band performance of MXene flexible array material by adjusting the array parameter w of the screen template. Examples verify the applicability of this method in scenarios involving dual-band performance balance, high infrared thermal radiation control, and high radar transmittance. Test results show that:

[0044] The array gap width is linearly positively correlated with the X-band radar transmittance of MXene material and linearly negatively correlated with the infrared reflectance, providing a clear basis for process parameters for dual-band performance control;

[0045] The array geometry parameters, through frequency-selective surface equivalent LC circuit resonance effect and area-weighted average reflection law, respectively regulate the X-band radar response and infrared band emission characteristics, with a clear structure-effect relationship, enabling synergistic optimization of dual-band performance;

[0046] The fabrication process does not require precision photolithography equipment and complex driving systems. It is simple, low-cost, and highly repeatable, and can be scaled up on large-size flexible substrates. The resulting materials have excellent performance, strong flexibility and stability, and have potential for engineering applications.

[0047] As can be seen from the above embodiments, this invention solves the technical bottlenecks of existing radar-infrared dual-band materials, such as performance imbalance, high preparation cost, and difficulty in large-scale flexible production, by establishing a precise control path of "array geometry → dual-band electromagnetic performance". It provides new functional materials and industrial preparation technology support for fields such as civil communication, intelligent transportation, industrial electronics, and building energy conservation, and has important practical application value.

Claims

1. An MXene radar-infrared dual-band compatible flexible material, characterized in that: A PET flexible substrate and Ti3C2T x MXene periodic array layer The Ti3C2T x The MXene periodic array layer is a matrix arrangement of MXene units at equal intervals, forming a periodic conductive array with different duty cycles. The MXene unit is a square with a side length a of 500~5000μm, the spacing w between adjacent MXene units is 50~500μm, and the array period P=a+w is 1 / 5~1 / 20 of the X-band wavelength; By adjusting P, a, and w, periodic array layers with different duty cycles can be formed, enabling coordinated and customized control of the electromagnetic performance of X-band radar and infrared band radar.

2. The MXene radar-infrared dual-band compatible flexible material as described in claim 1, characterized in that: With w≥50μm and a=300μm, the average transmittance of the X-band radar is ≥75%, and the average reflectance of the infrared band is ≥40%, making it suitable for scenarios with high radar transmittance requirements.

3. The MXene radar-infrared dual-band compatible flexible material as described in claim 1, characterized in that: The MXene material employs Ti3C2T x , Ti2CT x or Nb2CT x systems.

4. The method for preparing the MXene radar-infrared dual-band compatible flexible material as described in any one of claims 1, characterized in that, Includes the following steps: The surface is screen-printed Step 1: Preparation of MXene precursor; MXene dispersions were prepared using a LiF-HCl selective etching method: A Ti3AlC2 MAX phase was used as a precursor and etched with a LiF-HCl mixture at 35–45 °C for 20–28 h to remove the Al atomic layer. The mixture was repeatedly washed with deionized water and centrifuged until the pH of the supernatant reached 5–7. After further treatment with ice-bath sonication and centrifugation, a monolayer Ti3C2 MAX dispersion with a concentration of 5–10 mg / mL was obtained. x MXene dispersion; Step 2: Preparation of high-solids-content MXene printing paste; Centrifuge the MXene dispersion obtained in step 1 at 8000-12000 rpm for 1-2 hours, discard the supernatant and collect the lower precipitate to obtain a solid content of 120-180 mg / mL. -1 The MXene slurry was stirred evenly and then allowed to stand to degas. Step 3: Array patterning printing; Using a 200-400 mesh screen template with pre-designed array parameters, the MXene paste obtained in step 2 is uniformly coated onto the screen template of the plasma-pretreated PET substrate through a screen printing process, forming a pre-defined Ti3C2T pattern on the substrate surface. x MXene periodic array; Step 4: Post-drying and curing treatment; The array sample printed in step 3 is first dried at room temperature for 12-24 hours, and then vacuum dried at 30-40°C for 2-4 hours to remove residual solvent, so that the MXene array is tightly bonded to the substrate, and the MXene radar-infrared dual-band compatible flexible material is obtained.

5. The method for preparing the MXene radar-infrared dual-band compatible flexible material as described in claim 4, characterized in that: The screen printing speed is 5~15mm / s. -1 .

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