Self-repairing wave-absorbing composite material, preparation method and application thereof

Abstract

The present application belongs to the technical field of wave-absorbing materials, and particularly relates to a self-repairing wave-absorbing composite material and a preparation method and application thereof. The present application uses porous biochar as a substrate to replace traditional carbon-based materials. Through the composite design of manganese selenide nanosheets and the porous network of biochar, the problem of insufficient biochar loss mechanism is optimized, a magnetic-dielectric synergistic loss mechanism is realized, and efficient electromagnetic wave absorption performance is achieved through optimization of the filler. By introducing a dynamic chemical bond, disulfide bond, into the polyurethane through a chain extender, the polyurethane matrix is endowed with self-repairing ability, effectively reducing maintenance costs and ensuring the all-round protection of the electromagnetic wave absorption coating on electronic devices. At the same time, the inherent flexibility of polyurethane is also conducive to the adaptation of multiple scenarios, improving the environmental adaptability of the composite material. In addition, the coupling of the filler conductive network and the high strain characteristics of polyurethane enables the composite material to have heat insulation performance and strain sensing capability, which is helpful for the combination of electromagnetic wave absorption materials and new intelligent wearable thermal management devices.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wave-absorbing materials, and particularly relates to a self-repairing wave-absorbing composite material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of 5G communication, new energy vehicles and smart wearable devices, electromagnetic pollution and single function of wave-absorbing materials have become increasingly prominent. Although the research on current electromagnetic wave-absorbing materials has made progress in improving wave-absorbing effect and bandwidth, it still faces multiple contradictions. On the one hand, traditional materials rely on non-renewable resources or high-pollution processes, such as high-temperature smelting of metal-based materials and synthesis of carbon-based materials (such as graphene and carbon nanotubes) involving fossil raw materials and high energy consumption, which seriously deviate from the concept of green manufacturing. On the other hand, existing technologies are mostly limited to single performance optimization, which is difficult to meet the comprehensive needs of electromagnetic absorption, mechanical durability, thermal management and intelligent response ability of materials in complex application scenarios. SUMMARY

[0003] The application aims to provide a self-repairing wave-absorbing composite material and a preparation method and application thereof.

[0004] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0005] The application provides a self-repairing wave-absorbing composite material, which comprises a polyurethane matrix and a filler filled in the polyurethane matrix.

[0006] The filler is porous biochar loaded with manganese selenide.

[0007] The preparation raw materials of the polyurethane matrix include polyhydric alcohol, isocyanate and chain extender.

[0008] The chain extender includes at least one of 2,2'-diamino diphenyl disulfide, 4,4'-dithiodianiline, 4,4'-dihydroxy diphenyl disulfide and 1,2-ethanedithiol.

[0009] Preferably, the ratio of manganese selenide to porous biochar in the filler is 10 mmol: 1-2 g.

[0010] The preparation raw material of the porous biochar is biomass, and the biomass includes at least one of bamboo, fruit shell and straw.

[0011] Preferably, the mass percentage content of the filler in the self-repairing wave-absorbing composite material is 1-10%.

[0012] Preferably, the polyhydric alcohol includes at least one of polytetrahydrofuran ether glycol, propylene oxide polyether glycol, polyhexamethylene glycol and polyethylene glycol.

[0013] The isocyanate includes at least one of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate and toluene diisocyanate.

[0014] Preferably, the preparation method of the porous biochar comprises the following steps:

[0015] After ultrasonic dispersion of the biomass and potassium hydroxide in water, the alkali-treated biomass is obtained by drying;

[0016] The alkali-treated biomass is sintered to obtain the porous biochar;

[0017] The dosage ratio of the biomass and potassium hydroxide is 16g: 20-50mmol;

[0018] The sintering temperature is 600-1200℃, and the time is 1-6h.

[0019] The application also provides a preparation method of the self-repairing wave-absorbing composite material, comprising the following steps:

[0020] The manganese source, selenium source and complexing agent are dispersed in water, and then a reducing agent is added to react to obtain a precursor solution;

[0021] The precursor solution and the porous biochar are mixed to perform a hydrothermal reaction to obtain a filler;

[0022] The polyhydric alcohol and the isocyanate are dissolved in an organic solvent, and then a catalyst and a chain extender are sequentially added to react to obtain a polyurethane prepolymer;

[0023] The filler and the polyurethane prepolymer are mixed to obtain a system, and the system is sequentially subjected to standing and curing to obtain the self-repairing wave-absorbing composite material.

[0024] Preferably, the manganese source includes at least one of manganese sulfate, manganese nitrate and manganese carbonate; the selenium source includes at least one of elemental selenium, selenium dioxide and sodium selenite; the complexing agent includes at least one of citric acid, oxalic acid and ethylenediaminetetraacetic acid; and the reducing agent includes at least one of hydrazine hydrate and ethylenediamine;

[0025] The molar ratio of the manganese source and the selenium source is 1:1-2;

[0026] The molar ratio of the manganese source and the complexing agent is 1:10-15;

[0027] The reaction is performed under stirring, and the stirring time is 1-3h.

[0028] Preferably, the dosage ratio of the manganese source and the porous biochar is 10mmol: 1-2g;

[0029] The temperature of the hydrothermal reaction is 160-200 DEG C, and the time is 12-24h.

[0030] Preferably, the molar ratio of the polyol, isocyanate and chain extender is 1:1-5:1-10.

[0031] The catalyst comprises dibutyl tin dilaurate; the ratio of the polyol and catalyst is 0.002mol:60-100ul.

[0032] The dissolving in the organic solvent is carried out under stirring, and the stirring time is 1-3h.

[0033] The stirring temperature after adding the catalyst is 60-80 DEG C, and the stirring time is 2-6h.

[0034] The reaction temperature after adding the chain extender is 60-80 DEG C, and the reaction time is 1-3h.

[0035] Preferably, the mass ratio of the filler and polyurethane prepolymer is 1-10:100.

[0036] The mixing of the filler and the polyurethane prepolymer is carried out under stirring, and the stirring temperature is 60-80 DEG C, and the stirring time is 1-3h.

[0037] The standing mode is vacuum standing, and the standing time is 12-48h.

[0038] The curing temperature is 60-80 DEG C, and the curing time is 24-48h.

[0039] The application provides a self-repairing wave-absorbing composite material, which comprises a polyurethane matrix and a filler filled in the polyurethane matrix; the filler is porous biochar loaded with manganese selenide; the preparation raw material of the polyurethane matrix comprises a polyol, an isocyanate and a chain extender; the chain extender comprises at least one of 2,2'-diamino diphenyl disulfide, 4,4'-dithiodianiline, 4,4'-dihydroxy diphenyl disulfide and 1,2-ethanedithiol.

[0040] The present application takes porous biochar as a substrate to replace traditional carbon-based materials to construct a green and environmentally friendly substrate. Meanwhile, through the composite design of manganese selenide and the porous network of biochar, the problem of insufficient biochar loss mechanism is optimized to realize a magnetic-dielectric synergistic loss mechanism, and through the optimization of fillers, high-efficiency electromagnetic wave absorption performance is realized. At the same time, by introducing a dynamic chemical bond, disulfide bond, into the polyurethane through a chain extender, the polyurethane substrate is endowed with self-repairing ability, which enables it to quickly restore mechanical properties under mild heating conditions, solving the problem of easy formation of small aging cracks in electromagnetic wave absorption materials during use, effectively reducing maintenance costs, and ensuring the all-round protection of electromagnetic wave absorption coatings for electronic devices. At the same time, the inherent flexibility of polyurethane is also conducive to the adaptation of multiple scenarios, improving the environmental adaptability of the composite material. In addition, the coupling of the conductive network of fillers and the high strain characteristics of polyurethane enables the composite material to have heat insulation performance and strain sensing capability, which is helpful for the combination of electromagnetic wave absorption materials and new intelligent wearable thermal management devices, helping to expand the application scenarios of wave absorption materials, and providing ideas for the design of new generation electromagnetic protection materials for emerging fields such as new energy vehicles and flexible electronics. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 SEM images of MnSe2 / BC-1 prepared in Example 1 and wave absorption performance, heat insulation performance, self-repairing and strain sensing performance of MnSe2 / BC / PU-1;

[0042] Figure 2 SEM images of MnSe2 / BC-2 prepared in Example 2 and wave absorption performance, heat insulation performance, self-repairing and strain sensing performance of MnSe2 / BC / PU-2;

[0043] Figure 3 SEM images of MnSe2 / BC-3 prepared in Example 3 and wave absorption performance, heat insulation performance, self-repairing and strain sensing performance of MnSe2 / BC / PU-3. DETAILED DESCRIPTION

[0044] The present application provides a self-repairing wave absorption composite material, which comprises a polyurethane substrate and fillers filled in the polyurethane substrate.

[0045] The fillers are porous biochar loaded with manganese selenide.

[0046] The raw materials for preparing the polyurethane substrate include polyhydric alcohol, isocyanate and chain extender.

[0047] The chain extender includes at least one of 2,2'-diamino diphenyl disulfide, 4,4'-dithiodianiline, 4,4'-dihydroxy diphenyl disulfide and 1,2-ethanedithiol.

[0048] In the present application, the ratio of manganese selenide and porous biochar in the filler is preferably 10 mmol: 1-2 g; the raw material for preparing the porous biochar is preferably biomass, and the biomass preferably includes at least one of bamboo, fruit shells and straw. In the present application, the mass percentage of the filler in the self-repairing wave-absorbing composite material is preferably 1-10%, and can be specifically 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0049] In the present application, the preparation method of the porous biochar preferably includes the following steps: adding biomass and potassium hydroxide into water for ultrasonic dispersion, and then drying to obtain alkali-treated biomass; and sintering the alkali-treated biomass to obtain the porous biochar. In the present application, the water is preferably deionized water. In the present application, the usage ratio of the biomass and potassium hydroxide is preferably 16 g: 20-50 mmol; and the ultrasonic dispersion time is preferably 1-3 h. In the present application, the drying temperature is preferably 60-80°C, and the time is preferably 12-48 h. In the present application, the sintering temperature is preferably 600-1200°C, and the time is preferably 1-6 h; and the sintering is preferably carried out in an inert atmosphere, which is preferably argon. In the present application, after the sintering, the obtained material is further preferably subjected to washing and drying in sequence, the washing mode is preferably multiple times of centrifugal washing with anhydrous ethanol and deionized water alternately; and the drying temperature is preferably 60-80°C, and the time is preferably 12-8 h.

[0050] In the present application, the raw material for preparing the polyurethane matrix includes polyol, isocyanate and chain extender; the polyol preferably includes at least one of polytetrahydrofuran ether glycol (PTMG), propylene oxide polyether glycol, polyhexamethylene polyol and polyethylene glycol; the relative molecular weight of the polytetrahydrofuran ether glycol is preferably 1000 (i.e. PTMG1000); the isocyanate preferably includes at least one of isophorone diisocyanate (IPDI), 4,4'-diphenyl methane diisocyanate, hexamethylene diisocyanate and toluene diisocyanate; and the chain extender includes at least one of 2,2'-diamino diphenyl disulfide, 4,4'-dithiodianiline, 4,4'-dihydroxy diphenyl disulfide and 1,2-ethanedithiol. In the present application, the molar ratio of the polyol, isocyanate and chain extender is preferably 1: 1-5: 1-10.

[0051] The present application also provides a preparation method of the self-repairing wave-absorbing composite material described in the above technical solution, which includes the following steps:

[0052] dispersing a manganese source, a selenium source and a complexing agent in water, and then adding a reducing agent to react to obtain a precursor solution;

[0053] Mix the precursor solution and the porous biochar, and perform a hydrothermal reaction to obtain a filler;

[0054] Dissolve the polyol and the isocyanate in an organic solvent, then sequentially add a catalyst and a chain extender, and perform a reaction to obtain a polyurethane prepolymer;

[0055] Mix the filler and the polyurethane prepolymer to obtain a system, and sequentially perform standing and curing on the system to obtain the self-repairing wave-absorbing composite material.

[0056] In the present application, the manganese source preferably includes at least one of manganese sulfate, manganese nitrate and manganese carbonate; the selenium source preferably includes at least one of elemental selenium, selenium dioxide and sodium selenite; the complexing agent preferably includes at least one of citric acid, oxalic acid and ethylenediaminetetraacetic acid; the reducing agent preferably includes at least one of hydrazine hydrate and ethylenediamine; and the water is preferably distilled water.

[0057] In the present application, the molar ratio of the manganese source to the selenium source is preferably 1:1-2, and the molar ratio of the manganese source to the complexing agent is preferably 1:10-15.

[0058] After obtaining the precursor solution, the present application mixes the precursor solution and the porous biochar, and performs a hydrothermal reaction to obtain a filler.

[0059] In the present application, the dosage ratio of the manganese source to the porous biochar is 10 mmol: 1-2 g; the temperature of the hydrothermal reaction is preferably 160-200 DEG C, and can be specifically 160 DEG C, 170 DEG C, 180 DEG C, 190 DEG C or 200 DEG C; the time is preferably 12-24 h, and can be specifically 12 h, 16 h, 20 h or 24 h; and the hydrothermal reaction is preferably performed in a hydrothermal reaction kettle with a polytetrafluoroethylene lining.

[0060] In the present application, the dosage ratio of the manganese source to the porous biochar is 10 mmol: 1-2 g; the temperature of the hydrothermal reaction is preferably 160-200 DEG C, and can be specifically 160 DEG C, 170 DEG C, 180 DEG C, 190 DEG C or 200 DEG C; the time is preferably 12-24 h, and can be specifically 12 h, 16 h, 20 h or 24 h; and the hydrothermal reaction is preferably performed in a hydrothermal reaction kettle with a polytetrafluoroethylene lining.

[0061] In the present application, the organic solvent preferably comprises N,N-dimethylformamide; the ratio of the polyhydric alcohol and the organic solvent preferably is 0.002 mol:20 mL. In the present application, the molar ratio of the polyhydric alcohol, the isocyanate and the chain extender preferably is 1:1-5:1-10. In the present application, the dissolving in the organic solvent preferably is carried out under stirring, and the stirring time preferably is 1-3 h. In the present application, the catalyst preferably comprises dibutyltin dilaurate; the ratio of the polyhydric alcohol and the catalyst preferably is 0.002 mol:60-100 μL. In the present application, the stirring temperature after adding the catalyst preferably is 60-80 ℃, and the stirring time preferably is 2-6 h; the reaction preferably is carried out under stirring, and the reaction temperature after adding the chain extender preferably is 60-80 ℃, and the reaction time preferably is 1-3 h.

[0062] After obtaining the filler and the polyurethane prepolymer, the filler and the polyurethane prepolymer are mixed in the present application, the obtained system is sequentially subjected to standing and curing to obtain the self-repairing wave-absorbing composite material.

[0063] In the present application, the mass ratio of the filler and the polyurethane prepolymer preferably is 1-10:100; the mixing of the filler and the polyurethane prepolymer preferably is carried out under stirring, and the stirring temperature preferably is 60-80 ℃, and the stirring time preferably is 1-3 h; the standing mode preferably is vacuum standing, and the standing time preferably is 12-48 h; the curing temperature preferably is 60-80 ℃, and the curing time preferably is 24-48 h.

[0064] Unless otherwise specified, the materials and devices used in the present application are commercially available in the art.

[0065] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0066] Embodiment 1

[0067] 50 mmol of potassium hydroxide and 16 g of bamboo powder were mixed and added to deionized water, ultrasonic dispersion was carried out at 60 ℃ for 1 h, and drying was carried out at 80 ℃ for 48 h to obtain alkali-treated bamboo;

[0068] The alkali-treated bamboo was placed in a muffle furnace, sintered at 800 ℃ for 3 h in an argon atmosphere, then washed by centrifugation with anhydrous ethanol and deionized water alternately, and dried at 60 ℃ for 48 h to obtain porous biochar;

[0069] A precursor solution was prepared by dispersing 2 mmol of MnSO4, 4 mmol of selenium powder and 25 mmol of citric acid in 44 mL of distilled water, and then adding 16 mL of hydrazine hydrate, and stirring magnetically for 1 h until no obvious granular solid was observed;

[0070] The obtained precursor solution and 0.26 g of the porous biochar were placed in a hydrothermal reactor with a polytetrafluoroethylene lining, and hydrothermal reaction was carried out at 180 °C for 12 h. After natural cooling, the product was filtered, washed with deionized water alternately for five times, and finally vacuum dried at 80 °C for 10 h to obtain a filler, which was recorded as MnSe2 / BC-1;

[0071] 0.002 mmol of PTMEG1000 and 0.004 mmol of IPDI were dissolved in 20 mL of DMF, and stirred for 1 h. Then 80 μL of dibutyltin dilaurate was added, and stirred at 80 °C for 2 h. Then 0.002 mmol of 2,2'-diamino diphenyl disulfide ether was added, and continuously stirred at 80 °C for 2 h to obtain 3.329 g of a polyurethane prepolymer.

[0072] 0.14 g of MnSe2 / BC-1 was added to the polyurethane prepolymer, and heated and stirred at 80 °C for 2 h. The mixed system was placed in vacuum for 24 h, and finally cured at 80 °C for 48 h to obtain a self-repairing wave-absorbing composite material, which was recorded as MnSe2 / BC / PU-1.

[0073] Example 2

[0074] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, and added to deionized water. Ultrasonic dispersion was carried out at 60 °C for 1 h, and then dried at 80 °C for 48 h to obtain alkali-treated bamboo.

[0075] The alkali-treated bamboo was placed in a muffle furnace, and sintered at 800 °C for 3 h in an argon atmosphere. Then the product was washed by centrifugation with anhydrous ethanol and deionized water alternately, and dried at 60 °C for 48 h to obtain porous biochar.

[0076] A precursor solution was prepared by dispersing 2 mmol of MnSO4, 4 mmol of selenium powder and 25 mmol of citric acid in 44 mL of distilled water, and then adding 16 mL of hydrazine hydrate, and stirring magnetically for 1 h until no obvious granular solid was observed;

[0077] The obtained precursor solution and 0.39 g of the porous biochar were placed in a hydrothermal reactor with a polytetrafluoroethylene lining, and hydrothermal reaction was carried out at 180 °C for 12 h. After natural cooling, the product was filtered, washed with deionized water alternately for five times, and finally vacuum dried at 80 °C for 10 h to obtain a filler, which was recorded as MnSe2 / BC-2;

[0078] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL of dibutyltin dilaurate was added, stirred at 80 °C for 2 h; 0.002 mmol of 2,2'-diamino diphenyl disulfide ether was added, and stirring was continued at 80 °C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0079] 0.14 g of MnSe2 / BC-2 was added to the polyurethane prepolymer, heated and stirred at 80 °C for 2 h, uniformly mixed, and the mixed system was placed in vacuum for 24 h, and finally cured at 80 °C for 48 h to obtain a self-repairing wave-absorbing composite material, denoted as MnSe2 / BC / PU-2.

[0080] Example 3

[0081] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60 °C for 1 h, and dried at 80 °C for 48 h to obtain alkali-treated bamboo;

[0082] The alkali-treated bamboo was placed in a muffle furnace, sintered at 800 °C for 3 h in an argon atmosphere, and then washed by centrifugation with anhydrous ethanol and deionized water alternately, and dried at 60 °C for 48 h to obtain porous biochar;

[0083] 2 mmol of MnSO4, 4 mmol of selenium powder and 25 mmol of citric acid were dispersed in 44 mL of distilled water, and then 16 mL of hydrazine hydrate was added, and magnetically stirred for 1 h until no obvious granular solid was observed to obtain a precursor solution;

[0084] The obtained precursor solution and 0.26 g of porous biochar were placed in a hydrothermal reactor with a polytetrafluoroethylene liner, and hydrothermal reaction was carried out at 180 °C for 12 h, and after natural cooling, the product was washed with deionized water alternately for five times, and finally dried at 80 °C under vacuum for 10 h to obtain a filler, denoted as MnSe2 / BC-3;

[0085] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL of dibutyltin dilaurate was added, stirred at 80 °C for 2 h; 0.002 mmol of 2,2'-diamino diphenyl disulfide ether was added, and stirring was continued at 80 °C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0086] 0.29 g of MnSe2 / BC-3 was added to the polyurethane prepolymer, heated and stirred at 80 °C for 2 h, uniformly mixed, and the mixed system was placed in vacuum for 24 h, and finally cured at 80 °C for 48 h to obtain a self-repairing wave-absorbing composite material, denoted as MnSe2 / BC / PU-3.

[0087] Comparative Example 1

[0088] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 h, dried at 80°C for 48 h, to obtain alkali-treated bamboo;

[0089] The alkali-treated bamboo was placed in a muffle furnace, sintered at 800°C for 3 h in an argon atmosphere, then washed by centrifugation with anhydrous ethanol and deionized water alternately, and dried at 60°C for 48 h, to obtain a porous biochar;

[0090] 2 mmol of MnSO4, 4 mmol of selenium powder and 25 mmol of citric acid were dispersed in 44 mL of distilled water, then 16 mL of hydrazine hydrate was added, and magnetic stirring was performed for 1 h until no obvious granular solid was present, to obtain a precursor solution;

[0091] The obtained precursor solution and 0.26 g of porous biochar were placed in a hydrothermal reactor with a polytetrafluoroethylene liner, and hydrothermal reaction was performed at 180°C for 12 h, and after natural cooling, the product was filtered and washed with deionized water alternately for five times, and finally vacuum dried at 80°C for 10 h, to obtain a wave-absorbing material;

[0092] Testing showed that the minimum reflection loss of the wave-absorbing material was -15.72 dB at 3.12 mm and 12.063 GHz, and the effective absorption bandwidth was 0.494 GHz.

[0093] Comparative Example 2

[0094] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 h, dried at 80°C for 48 h, to obtain alkali-treated bamboo;

[0095] The alkali-treated bamboo was placed in a muffle furnace, sintered at 800°C for 3 h in an argon atmosphere, then washed by centrifugation with anhydrous ethanol and deionized water alternately, and dried at 60°C for 48 h, to obtain a porous biochar;

[0096] 2 mmol of MnSO4, 4 mmol of selenium powder and 25 mmol of citric acid were dispersed in 44 mL of distilled water, then 16 mL of hydrazine hydrate was added, and magnetic stirring was performed for 1 h until no obvious granular solid was present, to obtain a precursor solution;

[0097] The obtained precursor solution and 0.52 g of porous biochar were placed in a hydrothermal reactor with a polytetrafluoroethylene liner, and hydrothermal reaction was performed at 180°C for 12 h, and after natural cooling, the product was filtered and washed with deionized water alternately for five times, and finally vacuum dried at 80°C for 10 h, to obtain a filler, denoted as MnSe2 / BC-4;

[0098] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL of dibutyltin dilaurate was added, stirred at 80 °C for 2 h; 0.002 mmol of 2,2'-diamino diphenyl disulfide ether was continuously added, and stirred at 80 °C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0099] 0.14 g of MnSe2 / BC-4 was added to the polyurethane prepolymer, heated and stirred at 80 °C for 2 h, uniformly mixed, and the mixed system was placed in vacuum for 24 h, and finally cured at 80 °C for 48 h to obtain a self-repairing wave-absorbing composite material, denoted as MnSe2 / BC / PU.

[0100] Test results show that the minimum reflection loss of the MnSe2 / BC / PU-4 wave-absorbing material at 10.12 GHz at 2.98 mm is -12.31 dB, and the effective absorption bandwidth is 0.508 GHz.

[0101] Comparative Example 3

[0102] The filler and the polyurethane prepolymer were prepared in the manner of Example 1;

[0103] 0.59 g of the filler was added to 3.329 g of the polyurethane prepolymer, heated and stirred at 80 °C for 2 h, uniformly mixed, and the mixed system was placed in vacuum for 24 h, and finally cured at 80 °C for 48 h to obtain a composite wave-absorbing material.

[0104] Test results show that the minimum reflection loss of the composite material at 12.01 GHz at 2.66 mm is -24.75 dB, the effective absorption bandwidth is 0.83 GHz, the self-repairing effect is 92.2%, the heat insulation effect is 33.2%, and the strain sensing sensitivity GF is 0.519.

[0105] Performance test

[0106] Test Example 1

[0107] Figure 1 SEM image of MnSe2 / BC-1 prepared in Example 1 and wave-absorbing performance, heat insulation performance, self-repairing and strain sensing performance of MnSe2 / BC / PU-1;

[0108] Figure 1 (a) of FIG. 1 is an SEM image of MnSe2 / BC-1, and it can be seen that the active porous biochar has a pore structure, and MnSe2 is attached to the surface of the porous biochar in a cubic shape;

[0109] Figure 1(b) is the three-dimensional reflectance loss diagram of MnSe2 / BC / PU-1, the minimum reflectance loss is -13.98 dB at 2.95 mm and 12.022 GHz, and the effective absorption bandwidth is 0.168 GHz;

[0110] Figure 1 (c) is the temperature change curve of MnSe2 / BC / PU-1 placed on a 100℃ hot stage, the top heat insulation equilibrium temperature is only 82.3℃, and the heat insulation effect reaches 17.7% (the percentage of the reduced temperature to the hot stage temperature);

[0111] Figure 1 (d) is the stress-strain diagram of MnSe2 / BC / PU-1 after the cut part is contacted after cutting with a small knife and repaired for 3h at 80℃, wherein the strain repair effect (the ratio of the elongation at break before and after repair) is 93.8%;

[0112] Figure 1 (e) is the resistance change rate of MnSe2 / BC / PU-1 under 100% strain, and the sensitivity reaches 0.427;

[0113] Figure 1 (f) is the resistance induction signal of MnSe2 / BC / PU-1 generated by bending the finger 90°, it can be seen that the relative resistivity change is high, the highest reaches 4.7, and similar electrical signals are generated by three times of bending, and the signal transmission is stable.

[0114] Test Example 2

[0115] Figure 2 are the SEM diagram of MnSe2 / BC-2 prepared in Example 2 and the wave absorption performance, heat insulation performance, self-repair and strain sensing performance diagram of MnSe2 / BC / PU-2;

[0116] Figure 2 (a) is the SEM diagram of MnSe2 / BC-2, it can be seen that the content of active porous biochar is increased, and MnSe2 is attached to the surface of the porous biochar;

[0117] Figure 2 (b) is the three-dimensional reflectance loss diagram of MnSe2 / BC / PU-2, the minimum reflectance loss is -25.76 dB at 2.45 mm and 12.106 GHz, and the effective absorption bandwidth is 1.241 GHz;

[0118] Figure 2 (c) is the temperature change curve of MnSe2 / BC / PU-2 placed on a 100℃ hot stage, the top heat insulation equilibrium temperature is only 74.3℃, and the heat insulation effect reaches 25.7%;

[0119] Figure 2(d) is the stress-strain diagram of MnSe2 / BC / PU-2 after the cut is contacted and repaired at 80℃ for 3h after cutting with a knife, wherein the strain repair effect is 93.4%;

[0120] Figure 2 (e) is the resistance change rate of MnSe2 / BC / PU-2 under 100% strain, and the sensitivity reaches 0.412;

[0121] Figure 2 (f) is the resistance response signal of MnSe2 / BC / PU-2 generated by bending the finger by 90°, and it can be seen that the relative resistivity change is high, and the highest reaches 4.1. Three bends all produce similar electrical signals, and the signal transmission is stable.

[0122] Test Example 3

[0123] Figure 3 (a) is the SEM image of MnSe2 / BC-3 and the wave absorption performance, heat insulation performance, self-repairing and strain sensing performance diagram of MnSe2 / BC / PU-3 prepared in Example 3;

[0124] Figure 3 (a) is the SEM image of MnSe2 / BC-3, and it can be seen that the porosity of the active porous biochar continues to increase, and MnSe2 is attached to the surface of the porous biochar and the number increases;

[0125] Figure 3 (b) is the three-dimensional reflection loss diagram of MnSe2 / BC / PU-3, and the minimum reflection loss is-41.53dB at 3.95mm and 8.221GHz, and the effective absorption bandwidth is 1.271GHz;

[0126] Figure 3 (c) is the temperature change curve of MnSe2 / BC / PU-3 placed on a 100℃ hot stage, and the top heat insulation equilibrium temperature is only 69.9℃, and the heat insulation effect reaches 31.1%;

[0127] Figure 3 (d) is the stress-strain diagram of MnSe2 / BC / PU-3 after the cut is contacted and repaired at 80℃ for 3h after cutting with a knife, wherein the strain repair effect is 90.7%;

[0128] Figure 3 (e) is the resistance change rate of MnSe2 / BC / PU-3 under 100% strain, and the sensitivity reaches 0.522;

[0129] Figure 3(f) is the resistance signal of MnSe2 / BC / PU-3 when the finger is bent 90°, and it can be seen that the relative resistivity change is high, up to 5.6, and similar peaks of the electrical signal are generated after three times of bending, and the signal transmission is stable.

[0130] Although the above embodiments have been described in detail, they are only some embodiments of the present application, not all embodiments, and other embodiments can be obtained according to the above embodiments without creativity, and these embodiments all belong to the protection scope of the present application.

Claims

1. A self-healing metamaterial, characterized in that, The polyurethane matrix and the filler filled in the polyurethane matrix; The filler is porous biochar loaded manganese selenide; The raw materials for preparing the polyurethane matrix are polyhydric alcohol, isocyanate, chain extender and catalyst; The chain extender is at least one of 2,2'-diamino diphenyl disulfide, 4,4'-dithiodianiline, 4,4'-dihydroxy diphenyl disulfide and 1,2-ethanedithiol; The molar ratio of the polyhydric alcohol, isocyanate and chain extender is 1:1-5:1-10.

2. The self-healing metamaterial according to claim 1, wherein, The ratio of manganese selenide and porous biochar in the filler is 10 mmol:1-2 g; The raw material for preparing the porous biochar is biomass, and the biomass includes at least one of bamboo, fruit shell and straw.

3. The self-healing metamaterial of claim 1 or 2, wherein, The mass percentage of the filler in the self-repairing wave-absorbing composite material is 1-10%.

4. The self-healing metamaterial of claim 1, wherein, The polyhydric alcohol includes at least one of polytetrahydrofuran ether glycol, propylene oxide polyether glycol, polyhexamethylene polyol and polyethylene glycol; The isocyanate includes at least one of isophorone diisocyanate, 4,4'-diphenyl methane diisocyanate, hexamethylene diisocyanate and toluene diisocyanate.

5. The self-healing metamaterial of claim 1, wherein, The preparation method of the porous biochar includes the following steps: After the biomass and potassium hydroxide are added into water for ultrasonic dispersion, the alkali-treated biomass is obtained by drying; The alkali-treated biomass is sintered to obtain the porous biochar; The dosage ratio of the biomass and potassium hydroxide is 16 g:20-50 mmol; The sintering temperature is 600-1200 DEG C, and the time is 1-6 h.

6. The method for preparing the self-repairing wave-absorbing composite material according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: The manganese source, selenium source and complexing agent are dispersed in water, and then a reducing agent is added for reaction to obtain a precursor solution; The precursor solution and porous biochar are mixed for hydrothermal reaction to obtain a filler; The polyhydric alcohol and isocyanate are dissolved in an organic solvent, and then a catalyst and a chain extender are sequentially added for reaction to obtain a polyurethane prepolymer; The filler and the polyurethane prepolymer are mixed, and the obtained system is sequentially subjected to standing and curing to obtain the self-repairing wave-absorbing composite material.

7. The production method according to claim 6, characterized by, The manganese source includes at least one of manganese sulfate, manganese nitrate and manganese carbonate; the selenium source includes at least one of elemental selenium, selenium dioxide and sodium selenite; the complexing agent includes at least one of citric acid, oxalic acid and ethylenediaminetetraacetic acid; and the reducing agent includes at least one of hydrazine hydrate and ethylenediamine; The molar ratio of the manganese source and selenium source is 1:1-2; The molar ratio of the manganese source and complexing agent is 1:10-15; The reaction is carried out under stirring, and the stirring time is 1-3 h.

8. The preparation method according to claim 6, characterized in that, The dosage ratio of the manganese source and porous biochar is 10 mmol:1-2 g; The hydrothermal reaction temperature is 160-200 DEG C, and the time is 12-24 h.

9. The preparation method according to claim 6, characterized in that, The molar ratio of the polyhydric alcohol, isocyanate and chain extender is 1:1-5:1-10; The catalyst includes dibutyltin dilaurate; and the dosage ratio of the polyhydric alcohol and catalyst is 0.002 mol:60-100 μL; The dissolution in the organic solvent is carried out under stirring, and the stirring time is 1-3 h; The temperature of the stirring after adding the catalyst is 60-80℃, and the time is 2-6h; The temperature of the reaction after adding the chain extender is 60-80℃, and the time is 1-3h.

10. The method of claim 6, wherein, The mass ratio of the filler and the polyurethane prepolymer is 1-10:100; The mixing of the filler and the polyurethane prepolymer is carried out under stirring, the temperature of the stirring is 60-80℃, and the time is 1-3h; The mode of the standing is vacuum standing, and the time of the standing is 12-48h; The temperature of the curing is 60-80℃, and the time is 24-48h.

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