Wide-temperature-range wave-absorbing material and preparation method thereof

Abstract

The invention provides a wide-temperature-range wave-absorbing material and a preparation method thereof, and belongs to the technical field of wave-absorbing materials. The preparation process of the wide-temperature-range wave-absorbing material comprises the following steps: (1) dissolving an ionic liquid and a polymer in a solvent to obtain a premixed solution; (2) pouring the premixed solution into a mold, and curing and molding to obtain an ionic liquid composite material; and (3) carrying out irradiation treatment on the obtained ionic liquid composite material by adopting gamma rays to obtain the wide-temperature-range efficient wave-absorbing material. The irradiation technology is adopted, the risk of ionic liquid leakage is effectively reduced, and efficient packaging of the ionic liquid in the polymer is achieved. Through a novel irradiation technology, strong interaction between the ionic liquid and the polymer is promoted, not only is the mechanical property of the material improved, but also a new degree of freedom is provided for optimizing the dielectric loss and the wave-absorbing property of the material, so that the wide-temperature-range wave-absorbing material (298-433K) with high wave-absorbing property and excellent toughness is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave absorbing materials, and particularly relates to a microwave absorbing material with a wide temperature range. Background Art

[0002] With the rapid development of communication technology and intelligent electronic devices, the development of high-performance electromagnetic wave absorbing materials is of great significance for China's national defense construction and people's daily life. Traditional microwave absorbing materials use solid materials such as graphene, carbon nanotubes, magnetic metals, and ferrites as microwave absorbing agents. The fillers have poor dispersion in the matrix, making it difficult to achieve uniform mixing, and the optical transmittance is relatively low. At the same time, magnetic powder fillers such as ferrites have a high density and a large dosage, making it difficult to meet the requirements of light weight and high efficiency.

[0003] Ionic liquids are molten salts composed of cations and anions, and have special electromagnetic response characteristics. That is, under the action of electromagnetic waves, ionic liquids exhibit unique response behaviors such as Maxwell rotation, vibration, and migration, and finally convert electromagnetic energy into heat energy dissipation. The response and loss behaviors of ionic liquids to electromagnetic waves are specifically manifested as the dipole polarization and ionic conduction of ions. The patent with the publication number (CN117186351A) loads imidazole ionic liquid in the chain network formed by polyurethane cross-linking. Although it shows certain microwave absorbing performance, due to the limited encapsulation amount of the ionic liquid by the polymer matrix, the maximum loading amount of the ionic liquid is only 30wt%. As the microwave absorbing functional phase, the content of the ionic liquid determines the microwave loss ability of the composite material. However, in order to balance the mechanical properties of the composite material and the stability of its performance in applications, it is difficult to further increase the effective content of the ionic liquid in the composite material, which in turn limits the improvement of its microwave absorbing performance and its effective application in complex environments such as wide temperature ranges.

[0004] High-performance microwave absorbing materials not only require strong electromagnetic wave loss ability, but also need to meet the impedance matching characteristics. Currently, the common strategy is to regulate the material structure composition, construct a unique microstructure, and regulate the dispersion distribution state of the fillers in the matrix, etc. However, due to the mutual restraint between multiple factors, the impedance matching and loss ability of the material are in a trade-off relationship, making it difficult to achieve efficient regulation of dielectric and microwave absorbing properties. In addition, since the dielectric and conductive properties of the material are both functions of temperature, an absorbing system that satisfies impedance matching at room temperature often causes an increase in conductivity due to temperature rise, resulting in impedance mismatch. This makes it difficult to maintain stable microwave absorbing performance under wide temperature conditions, which poses higher requirements for the screening and performance regulation of the material system. Therefore, it is necessary to use a new regulation strategy to solve the contradictory relationship between impedance matching and loss ability, so as to effectively improve the electromagnetic wave dissipation ability and microwave absorbing performance of the composite material. Summary of the Invention

[0005] Aiming at the key scientific and technological problems of easy leakage of ionic liquids and poor microwave absorption performance in ionic liquid composites, the present invention proposes a wide-temperature-range microwave absorption material and its preparation method. By means of γ-ray irradiation technology, through promoting strong interaction between ionic liquids and polymers, the microwave absorption intensity and absorption bandwidth are effectively improved, and at the same time, the mechanical properties of the material are improved, preparing a microwave absorption material with both high microwave absorption performance and toughness characteristics (298 - 433K).

[0006] In order to achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A preparation method of a wide-temperature-range microwave absorption material, comprising the following steps:

[0008] (1) Dissolve ionic liquids and polymers in a solvent to obtain a premixed solution;

[0009] (2) Pour the premixed solution into a mold, remove the solvent and solidify it to form an ionic liquid composite;

[0010] (3) Simply irradiate the ionic liquid composite with γ-rays to obtain a wide-temperature-range microwave absorption material.

[0011] The ionic liquid is an imidazole-based ionic liquid; the imidazole-based ionic liquid is any one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-methyl-3-octylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium hexafluoroborate.

[0012] The polymer is a low-dielectric polymer; the low-dielectric polymer is any one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyurethane, and polymethyl methacrylate.

[0013] In the step (1), the ionic liquid accounts for 10 - 60 wt.% of the total mass of the ionic liquid and the polymer.

[0014] The solvent is any one or more of N-methylpyrrolidone, N,N-dimethylformamide, and acetone.

[0015] The temperature for solidification and molding is from room temperature to 120°C, and the time is 2 - 8h.

[0016] The γ-rays are 60 Co-γ rays.

[0017] The irradiation dose of the irradiation is 0 - 100 kGy.

[0018] Preferably, the irradiation dose of the irradiation is 40 - 100 kGy.

[0019] A wide-temperature-range microwave absorbing material is used to absorb electromagnetic waves, with an absorption frequency range of 8.2 - 12.4 GHz and an applicable temperature range of 298 - 433 K.

[0020] Preferably, when the temperature is 433 K, it still exhibits excellent microwave absorbing performance, and its minimum reflection loss value can reach -30 dB.

[0021] 60 The Co-γ ray irradiation modification technology is a method that uses ionizing radiation to induce ionization or excitation of molecules or atoms, which quickly transform into free radicals and neutral molecules, causing complex chemical changes and then leading to changes in the molecular structure of the material or the formation of new substances. For polymer / ionic liquid composites, by controlling the irradiation dose of γ rays, it is possible to promote the breaking and formation of chemical bonds in the material, which is beneficial to enhancing the interaction between the ionic liquid and the polymer, improving the dispersion distribution of the ionic liquid within the polymer molecular chain, and effectively avoiding the leakage of the liquid.

[0022] 60 While enhancing the interaction between the ionic liquid and the polymer, Co-γ ray irradiation modification is also beneficial to improving the "polarization lag" effect of the ionic liquid in the microwave field. With the help of the "hindrance" effect from the polymer molecular chain and external resistances such as friction and collision brought about by the system viscosity, the microwave response behavior of the ionic liquid has a certain lag. In order to compensate for this lag behavior, the ionic liquid needs to "actively" absorb and convert electromagnetic wave energy to enhance its response ability. Therefore, by regulating the interaction between the ionic liquid and the polymer, it is possible to effectively design the microwave dielectric loss characteristics and microwave absorbing performance of the ionic liquid composite, and thus provide a new effective strategy for optimizing the dielectric loss and microwave absorbing performance.

[0023] Therefore, with the help of γ-ray irradiation technology, it is expected to enhance the interaction between ions and polymers, and then regulate the microwave response behavior of the ionic liquid, which is not only beneficial to improving the stability and mechanical properties of the ionic liquid composite, but more importantly, also provides a new idea for optimizing the dielectric loss ability and microwave absorbing performance of the composite.

[0024] In addition, since the irradiation technology enhances the interaction between the ionic liquid and the polymer inside the gel, on the one hand, it effectively prevents the leakage of the ionic liquid during the temperature and frequency response processes, improving the stability of the material properties, and on the other hand, it improves the mechanical properties of the composite, and is expected to realize the preparation of high-strength and tough gels.

[0025] The beneficial effects of the present invention:

[0026] 1. A preparation method of a tough ionic liquid composite gel in the present invention effectively improves the wave absorption intensity and absorption bandwidth. In addition, the γ-ray irradiation technology enhances the wave absorption performance of the composite material, effectively reducing the risk of ionic liquid leakage from the root.

[0027] 2. In the present invention, the ionic liquid composite material is first solidified and formed, and then the γ-ray irradiation technology is used to enhance the interaction between ions and polymers. Different from the previous method of improving the wave absorption performance by increasing the filling amount, the present invention starts from the perspective of optimizing the response behavior of ionic liquids. With the "obstruction" of this interaction to the ionic response process, the ionic liquid more "actively" absorbs electromagnetic wave energy to enhance its own response behavior, thereby further optimizing and improving the wave absorption performance. Compared with the material without irradiation treatment, the wave absorption performance is improved by 85%.

[0028] 3. The present invention uses a simple γ-ray irradiation treatment, which not only reduces the risk of ionic liquid leakage but also improves the mechanical properties of the material. The irradiation technology enhances the interaction between the ionic liquid and the polymer, improves the compatibility of the two materials, effectively reduces the risk of ionic liquid leakage, and is beneficial to improving the stability of the wave absorption performance of the material. At the same time, with the help of the γ-ray irradiation technology, by promoting a strong interaction between the ionic liquid and the polymer, the mechanical properties of the material are improved, and an ionic gel with both high performance and toughness characteristics is prepared.

[0029] 4. The raw materials of the present invention are easily available and the processing technology is simple, which is convenient for production in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 For the wave absorption performance of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composites with different contents in Examples 1-3.

[0032] Figure 2 For the dielectric constants of 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composites treated with different irradiation doses in Examples 4-5 and Comparative Example 1, (a) change in the real part of the dielectric constant; (b) change in the imaginary part of the dielectric constant.

[0033] Figure 3The microwave absorption properties of the 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite materials treated with different radiation doses in Examples 4-5 and Comparative Example 1.

[0034] Figure 4 The microwave absorption properties of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyurethane composite material at different temperatures in Example 6.

[0035] Figure 5 This is the wave absorbing performance of the 1-ethyl-3-methylimidazolium tetrafluoroborate / 1-ethyl-3-methylimidazolium hexafluorophosphate / polyvinylidene fluoride-hexafluoropropylene composite material in Example 7.

[0036] Figure 6 The mechanical tensile properties of the 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyurethane composite material in Example 8.

[0037] Figure 7 The conductivity of the 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material in Example 9.

[0038] Figure 8 This is an optical photograph of the 1-methyl-3-octylimidazolium tetrafluoroborate ionic liquid / polymethyl methacrylate composite film in Example 10. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] In this embodiment, 1-butyl-3-methylimidazolium tetrafluoroborate and polyvinylidene fluoride are used as materials to prepare an ionic liquid / polyvinylidene fluoride composite material, wherein the mass percentage of 1-butyl-3-methylimidazolium tetrafluoroborate is 40wt%. The specific steps are as follows:

[0042] (1) 25 g of polyvinylidene fluoride powder was placed in 175 mL of acetone and fully dissolved by magnetic stirring. Then, 16.7 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added and mixed uniformly to obtain a premixed solution.

[0043] (2) Pour the premixed solution into a mold and heat it at 80 °C for 12 h until the acetone has completely evaporated to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite film.

[0044] (3) Place the film in an electron irradiation target chamber and irradiate it with 60 Co-γ rays. Set the dose rate to 60.50 Gy / min and control the irradiation time to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite material with an irradiation dose of 100 kGy.

[0045] (4) Place the irradiated composite material in a mold and hot press it at 180 °C for 30 min to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite material.

[0046] Example 2

[0047] In this example, 1-butyl-3-methylimidazolium tetrafluoroborate and polyvinylidene fluoride were used as materials to prepare an ionic liquid / polyvinylidene fluoride composite material, in which the mass percentage content of 1-butyl-3-methylimidazolium tetrafluoroborate was 50 wt%. The specific steps are as follows:

[0048] (1) Take 25 g of polyvinylidene fluoride powder and place it in 175 mL of acetone. Stir it magnetically to dissolve it completely, and then add 25 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. After mixing evenly, a premixed solution is obtained.

[0049] (2) Pour the premixed solution into a mold and heat it at 80 °C for 12 h until the acetone has completely evaporated to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite film.

[0050] (3) Place the film in an electron irradiation target chamber and irradiate it with 60 Co-γ rays. Set the dose rate to 60.50 Gy / min and control the irradiation time to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite material with an irradiation dose of 100 kGy.

[0051] (4) Place the irradiated composite material in a mold and hot press it at 180 °C for 30 min to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite material.

[0052] Example 3

[0053] In this embodiment, 1-butyl-3-methylimidazolium tetrafluoroborate and polyvinylidene fluoride were used as materials to prepare an ionic liquid / polyvinylidene fluoride composite material, where the mass percentage content of 1-butyl-3-methylimidazolium tetrafluoroborate was 60 wt%. The specific steps are as follows:

[0054] (1) Take 25 g of polyvinylidene fluoride powder and place it in 175 mL of acetone. Stir it magnetically to dissolve it fully, and then add 37.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. After mixing evenly, a premixed solution is obtained.

[0055] (2) Pour the premixed solution into a mold and heat it at 80 °C for 12 h. Wait for the acetone to evaporate completely to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite film.

[0056] (3) Place the film in an electron irradiation target chamber and use 60 Co-γ rays for irradiation treatment. Set the dose rate to 60.50 Gy / min and control the irradiation time to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite material with an irradiation dose of 100 kGy.

[0057] (4) Place the irradiated composite material in a mold and hot press it at 180 °C for 30 min to obtain a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride composite material.

[0058] The electromagnetic parameters of the samples in the above Examples 1-3 were tested, and the comparison results of their microwave absorption properties are as Figure 1 shown. The microwave absorption performance of the material reached -25.2 dB when the ionic liquid content was 60 wt%.

[0059] Example 4

[0060] In this embodiment, 1-ethyl-3-methylimidazolium hexafluorophosphate and polyvinylidene fluoride-hexafluoropropylene were used as materials to prepare an ionic liquid composite material, where the mass percentage content of 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid was 50 wt%. The specific implementation steps are as follows:

[0061] (1) Take 20 g of polyvinylidene fluoride-hexafluoropropylene powder and place it in 150 mL of NMP. Stir it magnetically to dissolve it fully, and then add 20 g of 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid. After mixing evenly, a premixed solution is obtained.

[0062] (2) Pour the premixed solution into a mold and heat it at 120 °C for 12 h. Wait for the NMP to evaporate completely to obtain a 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite film.

[0063] (3) Place the film in an electron irradiation target chamber and irradiate it with 60 Co-γ rays, set the dose rate to 60.50 Gy / min, control the irradiation time, and obtain an ionic liquid composite film with an irradiation dose of 100 kGy.

[0064] (4) Place the irradiated film in a mold and hot press it at 180 °C for 30 min to obtain a 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material.

[0065] Example 5

[0066] In this example, 1-ethyl-3-methylimidazolium hexafluorophosphate and polyvinylidene fluoride-hexafluoropropylene are used as materials to prepare an ionic liquid composite material, where the mass percentage content of 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid is 50 wt%. The specific implementation steps are as follows:

[0067] (1) Take 20 g of polyvinylidene fluoride-hexafluoropropylene powder and place it in 150 mL of NMP. Stir it magnetically to dissolve it fully, and then add 20 g of 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid. After mixing evenly, a premixed solution is obtained.

[0068] (2) Pour the premixed solution onto a mold and heat it at 120 °C for 12 h until the NMP is completely evaporated to obtain a 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite film.

[0069] (3) Place the film in an electron irradiation target chamber and irradiate it with 60 Co-γ rays, set the dose rate to 60.50 Gy / min, control the irradiation time, and obtain an ionic liquid composite film with an irradiation dose of 40 kGy.

[0070] (4) Place the irradiated film in a mold and hot press it at 180 °C for 30 min to obtain a 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material.

[0071] Comparative Example 1

[0072] In this comparative example, 1-ethyl-3-methylimidazolium hexafluorophosphate and polyvinylidene fluoride-hexafluoropropylene are used as materials to prepare an ionic liquid composite material, where the mass percentage content of 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid is 50 wt%. The specific implementation steps are as follows:

[0073] (1) Take 20 g of polyvinylidene fluoride - hexafluoropropylene powder and place it in 150 mL of NMP. Stir it magnetically to dissolve it completely. Then add 20 g of 1 - ethyl - 3 - methylimidazolium hexafluorophosphate ionic liquid. After uniform mixing, a premixed solution is obtained.

[0074] (2) Pour the premixed solution into a mold and heat it at 120 °C for 12 h. Wait for the NMP to evaporate completely to obtain a 1 - ethyl - 3 - methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride - hexafluoropropylene composite film.

[0075] (3) Place the film in a mold and hot - press it at 180 °C for 30 min to obtain a 1 - ethyl - 3 - methylimidazolium hexafluorophosphate ionic liquid / polyvinylidene fluoride - hexafluoropropylene composite material.

[0076] Examples 4 - 5 and Comparative Example 1 explored the influence of the irradiation dose on the microwave absorption performance of the ionic liquid composite materials during the irradiation process. The dielectric properties of the samples prepared in Examples 4 - 5 and Comparative Example 1 were tested using a vector network analyzer. The results are as Figure 2 shown. It can be clearly observed that for the ionic liquid composite materials treated by γ - ray irradiation, both the real part and the imaginary part of the dielectric constant have been significantly improved.

[0077] The microwave absorption performance of the test samples was measured. The results are as Figure 3 shown. After γ - ray irradiation treatment, the microwave absorption performance of the 1 - ethyl - 3 - methylimidazolium hexafluorophosphate ionic liquid composite material has been significantly improved. The minimum reflection loss value can reach - 24 dB. Compared with the non - irradiated material, its microwave absorption performance has increased by 85%, and the effective absorption frequency range is 8.2 GHz - 12.4 GHz.

[0078] Example 6

[0079] In this example, 1 - butyl - 3 - methylimidazolium hexafluorophosphate and thermoplastic polyurethane were used as materials to prepare an ionic liquid composite material, in which the mass percentage content of the 1 - butyl - 3 - methylimidazolium hexafluorophosphate ionic liquid was set to 40 wt%. The specific implementation steps are as follows:

[0080] (1) Take 30 g of polyurethane and place it in 300 mL of DMF. Stir it magnetically to dissolve it completely. Then add the 1 - butyl - 3 - methylimidazolium hexafluorophosphate ionic liquid according to the proportion. After uniform mixing, a premixed solution is obtained.

[0081] (2) Pour the premixed solution into a mold and heat it at 120 °C for 12 h. Wait for the DMF to evaporate completely to obtain a 1 - butyl - 3 - methylimidazolium hexafluorophosphate ionic liquid / polyurethane composite film.

[0082] (3) Place the film in an electron irradiation target chamber and use 60Irradiate with Co-γ rays, set the irradiation dose rate to 60.50 Gy / min, control the irradiation time, and obtain a 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyurethane composite material with enhanced γ-ray irradiation.

[0083] (4) Place the irradiated film in a mold and hot press it at 180 °C for 30 min to obtain a 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid / polyurethane composite material.

[0084] Use a vector network analyzer to test the microwave absorption performance of the sample prepared in Example 6 at different temperatures, as Figure 4 shown. When the ambient temperature is 393 K, the minimum reflection loss is -22 dB; when the ambient temperature rises to 433 K, the minimum reflection loss can reach -30 dB, and the effective absorption range covers the X band (8.2 - 12.5 GHz).

[0085] Example 7

[0086] In this example, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and polyvinylidene fluoride-hexafluoropropylene are used as materials to prepare an ionic liquid composite material. Among them, the mass fraction of the ionic liquid content is set to 50 wt%, and the mass ratio of the two ionic liquids is 1:1. The specific implementation steps are as follows:

[0087] (1) Take 25 g of polyvinylidene fluoride-hexafluoropropylene and place it in 200 mL of DMF. Stir it magnetically to dissolve it fully, and then add two ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium hexafluorophosphate, with a ratio of 1:1 between them and a total mass of 25 g for the ionic liquids. After uniform mixing, a premixed solution is obtained.

[0088] (2) Pour the premixed solution into a mold and heat it at 120 °C for 12 h until the DMF completely evaporates to obtain an ionic liquid / polyurethane composite film.

[0089] (3) Place the film in an electron irradiation target chamber and use 60 Co-γ rays for irradiation treatment. Set the irradiation dose rate to 60.50 Gy / min, control the irradiation time, and obtain an ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material with enhanced γ-ray irradiation.

[0090] (4) Place the irradiated film in a mold and hot press it at 180 °C for 30 min to obtain an ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material

[0091] Use a vector network analyzer to test the microwave absorption performance of the sample prepared in Example 7. The results are as Figure 5As shown, due to the synergistic effect of different ions, the compounded ionic liquid composite material exhibits excellent wave absorption performance, with a minimum reflection loss value of -28 dB and an effective absorption frequency range of 8.2 - 12.4 GHz.

[0092] Example 8

[0093] In this example, 1-ethyl-3-methylimidazolium tetrafluoroborate and thermoplastic polyurethane are used as materials to prepare an ionic liquid composite material, in which the mass percentage content of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid is set to 60 wt%. The specific implementation steps are as follows:

[0094] (1) Take 20 g of polyurethane and place it in 250 mL of DMF, and dissolve it thoroughly by magnetic stirring. Then add 30 g of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid according to the proportion, and after uniform mixing, a premixed solution is obtained.

[0095] (2) Pour the premixed solution into a mold and heat it at 120 °C for 12 h. Wait until the DMF completely evaporates to obtain a 1-ethyl-3-butylimidazolium tetrafluoroborate ionic liquid / polyurethane composite film.

[0096] (3) Place the film in an electron irradiation target chamber and use 60 Co-γ rays for irradiation treatment. Set the irradiation dose rate to 60.50 Gy / min and control the irradiation time to obtain a γ-ray irradiated enhanced 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyurethane composite material.

[0097] Use the sample prepared in Example 8 to study the enhancement effect of γ-ray irradiation on the mechanical properties of the ionic liquid composite material. As Figure 6 shown, when the film is stretched to a certain length, it can still return to its original state, indicating that the prepared 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyurethane composite material has good stretchability.

[0098] Example 9

[0099] In this example, 1-hexyl-3-methylimidazolium tetrafluoroborate and polyvinylidene fluoride-hexafluoropropylene are used as materials to prepare an ionic liquid composite material, in which the mass percentage content of 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid is 20 wt%.

[0100] (1) Take 30 g of polyvinylidene fluoride-hexafluoropropylene powder and place it in 275 mL of DMF, and dissolve it thoroughly by magnetic stirring. Then add 7.5 g of 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid, and after uniform mixing, a premixed solution is obtained.

[0101] (2) The premixed solution was poured into a mold and heated at 120° C. for 12 h to completely evaporate the DMF to obtain a 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite film.

[0102] (3) Place the film in an electron irradiation target chamber and use 60 The irradiation treatment was performed by Co-γ ray, the dose rate was set to 60.50 Gy / min, and the irradiation time was controlled to obtain an ionic liquid composite film with an irradiation dose of 100 kGy.

[0103] (4) placing the irradiated film in a mold and hot pressing it at 180° C. for 30 min to obtain a 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material.

[0104] The 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material prepared in Example 9 was connected to an LED lamp and the voltage was adjusted. It can be observed that the prepared composite material has a certain conductive property, such as Figure 7 shown.

[0105] Example 10

[0106] In this embodiment, 1-methyl-3-octylimidazolium tetrafluoroborate and polymethyl methacrylate are used as materials to prepare an ionic liquid composite material, wherein the mass percentage of 1-methyl-3-octylimidazolium tetrafluoroborate ionic liquid is 10wt%. The specific implementation steps are as follows:

[0107] (1) 25 g of polymethyl methacrylate was placed in 200 mL of DMF and fully dissolved by magnetic stirring. Then, 2.8 g of 1-methyl-3-octylimidazolium tetrafluoroborate ionic liquid was added and mixed uniformly to obtain a premixed solution.

[0108] (2) Pour the premixed solution into a mold and heat it at 120° C. for 12 h until DMF is completely evaporated to obtain a 1-methyl-3-octylimidazolium tetrafluoroborate ionic liquid / polyvinylidene fluoride-hexafluoropropylene composite material.

[0109] (3) Place the film in an electron irradiation target chamber and use 60 The ion liquid composite film was irradiated with Co-γ rays at a dose rate of 60.50 Gy / min and the irradiation time was controlled to obtain an ion liquid composite film with an irradiation dose of 100 kGy. The optical photograph is shown in FIG. Figure 8 shown.

[0110] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a wide temperature range absorbing material, characterized in that: The following steps are involved: (1) dissolving the ionic liquid and the polymer in a solvent to obtain a premixed solution; (2) pouring the premixed solution into a mold and curing it to obtain an ionic liquid composite material; (3) The ionic liquid composite material is irradiated with gamma rays to obtain a wide temperature range absorbing material.

2. The method for preparing a wide temperature range absorbing material according to claim 1, characterized in that: The ionic liquid is an imidazolium ionic liquid; the imidazolium ionic liquid is any one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-methyl-3-octylimidazole tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium hexafluoroborate.

3. The method for preparing a wide temperature range absorbing material according to claim 2, characterized in that: The polymer is a low dielectric polymer; the low dielectric polymer is any one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyurethane and polymethyl methacrylate.

4. The method for preparing a wide temperature range absorbing material according to claim 3, characterized in that: In the step (1), the ionic liquid accounts for 10-60 wt% of the total mass of the ionic liquid and the polymer.

5. The method for preparing a wide temperature range absorbing material according to any one of claims 1 to 4, characterized in that: The solvent is any one or more of N-methylpyrrolidone, N,N-dimethylformamide and acetone.

6. The method for preparing a wide temperature range absorbing material according to claim 5, characterized in that: The curing temperature is from room temperature to 120° C. and the curing time is 2-8 hours.

7. The method for preparing a wide temperature range absorbing material according to claim 6, characterized in that: The gamma ray is 60 Co-gamma rays.

8. The method for preparing a wide temperature range absorbing material according to claim 7, characterized in that: The irradiation dose is 40-100 kGy.

9. A wide temperature range absorbing material prepared by the method according to any one of claims 1 to 8.

10. The wide temperature range absorbing material according to claim 9, characterized in that: The wide temperature range absorbing material is used for absorbing electromagnetic waves, the absorption frequency range is 8.2-12.4 GHz, and the applicable temperature range is 298-433K.

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