Electromagnetic shielding material capable of intelligent temperature control and preparation method thereof

Abstract

This invention belongs to the field of multifunctional composite material technology and discloses an electromagnetic shielding material capable of intelligent temperature control and its preparation method. The electromagnetic shielding material includes an Ag / LSW substrate layer, a phase change energy storage material absorbed within the Ag / LSW substrate layer, and VO2 adsorbed on the surface of the Ag / LSW substrate layer. The Ag / LSW substrate layer is obtained by bonding Ag and leather waste with an adhesive. The electromagnetic shielding material provided by this invention, using an Ag / LSW substrate layer as a base and VO2 as a switch, can achieve both excellent electromagnetic shielding performance and an initial temperature warning in electromagnetic wave scenarios. Then, VO2 activates autonomous temperature control, thereby achieving intelligent temperature control.

Description

Technical Field

[0001] This invention belongs to the field of multifunctional composite material technology, and relates to an electromagnetic shielding material that can achieve intelligent temperature control and its preparation method. Background Technology

[0002] With the rapid development of electronics and the Internet of Things, a large number of large electronic devices have been installed in the environment. The electromagnetic waves generated by these devices can easily interfere with and damage the normal operation of other electronic devices. Low-resistance metallic conductors are widely used as electromagnetic shielding materials through reflection and refraction; however, their high density, susceptibility to corrosion, and difficulty in processing limit their development and application in aerospace, military, and medical fields.

[0003] Researchers have been working to develop new, lightweight shielding devices. The heat generated during the absorption or attenuation of electromagnetic waves is difficult to remove, and excessively high operating temperatures can reduce the performance and lifespan of electronic equipment. Therefore, effective heat dissipation is crucial for maintaining daily operation. However, simple thermal management materials are insufficient for effective equipment protection, necessitating an increasingly intelligent electromagnetic shielding material with autonomous temperature regulation.

[0004] Natural leather is a natural material composed of collagen fiber bundles. Due to its wide availability and excellent properties, it has significant economic value. However, the leather manufacturing process generates a large amount of solid waste, and traditional disposal methods such as direct landfill and incineration damage the natural environment. The abundant amino acid residues in leather collagen fibers can act as electric dipoles to generate natural dipole moments. These dipole moments spontaneously align along the direction of the electric field. Due to the resistance of molecular thermal motion, electric dipole relaxation occurs, thereby converting electromagnetic energy into heat energy through an absorption mechanism. However, the shielding performance of pure leather is not significant enough, requiring the construction of a conductive layer on its surface to enhance the shielding effect. For example, Zeng et al. prepared a novel foldable solid leather waste (LSW) / polyvinyl alcohol (PVA) / silver (Ag) paper using a simple electroless plating (ELP) method. This paper exhibits excellent EMI shielding capabilities, successfully constructing Ag onto leather and improving shielding performance (see Zeng, Shulong et al. "From Waste to Wealth: A Lightweight and Flexible LeatherSolid Waste / Polyvinyl Alcohol / Silver Paper for Highly Efficient Electromagnetic Interference Shielding." ACS Applied Materials & Interfaces 12.46 (2020): 52038–52049); however, this material cannot also possess self-intelligent temperature control functionality. Building upon this foundation, Shi et al. developed a multifunctional material of solid waste / polyvinyl alcohol multi-source layered composite material, further demonstrating the potential for microstructure regulation of leather collagen fibers and utilizing the 3D porous structure for crude oil adsorption (see Shi, Hao et al. "Multifunctional Silver Decorated Leather Solid Waste / Poly(Vinyl Alcohol) Nanocomposites for Electromagnetic Interference Shielding, Joule Heating and Crude-Oil Cleaning." ACS Sustainable Chemistry & Engineering 10.39(2022):13165–13175). However, while this material can achieve rapid heating, it is not intelligent enough to achieve effective heat management.

[0005] Phase change materials (PCMs) can store and release energy in the form of latent heat while maintaining a constant temperature, making them considered the best temperature control materials for thermal protection. By selecting PCMs with reasonable phase change temperatures, the operating temperature of electronic devices can be controlled within a reasonable range. Currently reported methods such as microencapsulation and chemical cross-linking to composite PCMs mostly suffer from complex preparation processes and high costs, severely limiting their large-scale industrialization. In contrast, assembling PCMs with porous support materials using adsorption technology is considered a promising method to overcome these challenges and promote the large-scale preparation of high-performance PCMs. While PCMs alone can store heat, this is insufficient for achieving intelligent temperature control of the material itself. Vanadium dioxide (VO2) is an ideal material for intelligent thermal control systems due to its thermochromic properties. VO2 exhibits a semiconductor-to-metal phase transition at a critical temperature of around 68°C, which allows VO2 to transform from transmitted waves to strongly reflected waves in practical applications, thus serving as a "switch" for temperature control. However, processing VO2 is also very difficult; how to achieve temperature control while facilitating VO2 processing remains a technical problem that needs to be solved.

[0006] In conclusion, developing new materials that can effectively shield electromagnetic waves and achieve autonomous temperature control is a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned problems in the existing technology by providing an electromagnetic shielding material that enables intelligent temperature control, which not only effectively shields electromagnetic waves but also possesses excellent autonomous thermal management performance.

[0008] Another objective of this invention is to provide the above-described method for preparing electromagnetic shielding materials that enable intelligent temperature control.

[0009] To achieve the above objectives, the present invention adopts the following technical solutions.

[0010] The electromagnetic shielding material provided by the present invention, which enables intelligent temperature control, includes an Ag / LSW substrate layer, a phase change energy storage material absorbed within the Ag / LSW substrate layer, and VO2 adsorbed on the surface of the Ag / LSW substrate layer; the Ag / LSW substrate layer is obtained by bonding Ag and leather waste with an adhesive.

[0011] The aforementioned electromagnetic shielding material has an Ag / LSW substrate layer with a three-dimensional porous structure.

[0012] In the Ag / LSW base layer, the leather waste (LSW) is waste material obtained during the commercial chrome tanning process. The leather waste is polydopamine-modified leather waste powder; the dopamine can be replaced by vitamin C or catechol. The leather waste can be replaced by cellulose, palm leather, Lino leather, etc. The mass ratio of Ag to unmodified leather waste (LSW) is 1.8–2.0:1. The binder used to bond the Ag and leather waste is one of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), etc.

[0013] The phase change energy storage material absorbed into the Ag / LSW substrate accounts for at least 20% of the total mass of the Ag / LSW substrate and the absorbed phase change energy storage material; preferably, the phase change energy storage material absorbed into the Ag / LSW substrate accounts for 20% of the total mass of the Ag / LSW substrate and the absorbed phase change energy storage material until the phase change energy storage material reaches saturation; further, the phase change energy storage material absorbed into the Ag / LSW substrate accounts for 20% to 26% of the total mass of the Ag / LSW substrate and the absorbed phase change energy storage material. The phase change energy storage material is paraffin wax, coconut oil, or dodecanol, etc.

[0014] This invention also provides a method for preparing the above-mentioned electromagnetic shielding material capable of intelligent temperature control, which includes the following steps:

[0015] (1) Preparation of Ag / LSW substrate, including the following steps:

[0016] (11) Prepare leather waste powder and modify it with polydopamine to obtain modified leather waste powder;

[0017] (12) Preparation of solution A: Under stirring conditions, ammonia water is added dropwise to silver nitrate solution until the solution becomes clear, thus obtaining solution A;

[0018] (13) Preparation of solution B: Glucose, tetrahydrate, potassium sodium tartrate, polyethylene glycol and anhydrous ethanol are mixed evenly in water to obtain solution B;

[0019] (14) The modified leather waste powder is mixed with solution A and solution B, stirred and mixed evenly, and then left to stand for 6-8 hours. After washing and drying, Ag / LSW composite material is obtained.

[0020] (15) The Ag / LSW composite material is uniformly dispersed in water, and the resulting dispersion is then vacuum filtered to obtain an Ag / LSW composite membrane; the Ag / LSW composite membrane is fixed with an adhesive to obtain an Ag / LSW substrate layer.

[0021] (2) Preparation of VO2 / PCM composite materials

[0022] VO2 and phase change energy storage material were stirred and mixed uniformly at a temperature higher than the melting point of the phase change energy storage material to obtain VO2 / PCM composite material;

[0023] (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / PCM composite material includes the following steps:

[0024] (31) At an ambient temperature higher than the melting point of the phase change energy storage material, the phase change energy storage material is drawn into the Ag / LSW substrate layer;

[0025] (32) At an ambient temperature higher than the melting point of the phase change energy storage material, the VO2 / PCM composite material obtained in step (2) is composited onto the surface of the Ag / LSW substrate and cooled at room temperature to obtain an electromagnetic shielding material.

[0026] The purpose of step (1) above is to construct an Ag / LSW substrate layer with a three-dimensional porous structure using chemical silver plating. First, modified leather waste powder is prepared, then an Ag-containing solution is prepared, and then silver ions are reduced and deposited on the surface of the modified leather waste powder, forming a dense silver layer. The formation mechanism is the following redox reaction:

[0027] CH2OH(CHOH)4CHO+2Ag(NH3)2OH→CH2OH(CHOH)4COONH4+2Ag+3NH3+H2O

[0028] In step (11) above, firstly, solid-state grinding and shearing technology (S) is used. 3 M) Solid leather waste (LSM) is processed into LSW fibers (LFs) through 15-20 grinding cycles at a speed of 50-80 rpm; then the LSW fibers are sieved to obtain LSW powder; the obtained LSW powder is vacuum dried (drying temperature 90-120℃, drying time 12-18h), and then mixed and stirred with dopamine in an alkaline buffer solution, followed by washing and drying to obtain modified leather waste powder. The mass ratio of unmodified LSW powder to dopamine is 19-21:1. The alkaline buffer solution is one of Tris buffer solution or phosphate buffer solution, etc.; the pH value of the buffer solution is 8-9. The above mixing and stirring reaction time is 8-10h. The above drying conditions are: vacuum drying at 40-80℃ for 12-18h.

[0029] In step (12) above, the concentration of silver nitrate solution is 110–130 g / L. The concentration of ammonia is 25%–28%. When ammonia is added dropwise to the silver nitrate solution, the color of the silver nitrate solution changes from transparent to dark brown; when a black precipitate gradually appears, ammonia is added again to make the solution transparent again.

[0030] In step (13) above, the mass ratio of glucose, tetrahydrate, potassium sodium tartrate, and polyethylene glycol is 10:0.25:0.01; each 100 mL of solution B contains 10–30 mL of anhydrous ethanol. The glucose concentration is 190–210 g / L; the concentration of the tetrahydrate and potassium sodium tartrate is 2.75–5.25 g / L; and the polyethylene glycol concentration is 0.19–0.21 g / L.

[0031] In step (14) above, the anions are reduced and deposited on the surface of the modified leather waste powder to form a dense silver layer. The drying conditions are: vacuum drying at 40-60℃ for 5.5-6.5 hours. The mass ratio of the unmodified leather waste powder, silver nitrate, and glucose is 1:2.8-3.2:4.7-5.3.

[0032] In step (15) above, a solution containing binder is coated onto a support plate (e.g., a PTEE plate), and then the prepared Ag / LSW composite film is placed on top of the solution still containing binder and dried to obtain the Ag / LSW substrate layer. The drying conditions are: vacuum drying at 30–50°C for 5.5–6.5 h. The mass concentration of binder in the binder-containing solution is 9–11%. The thickness of the Ag / LSW substrate layer obtained in this step is approximately 1.7–1.9 cm.

[0033] In step (2) above, the mass ratio of VO2 to phase change energy storage material is 1:1 to 9. VO2 and phase change energy storage material are stirred and mixed evenly at 100 to 140°C; in a preferred embodiment, the stirring rate is 250 to 350 rpm, and the stirring time is 1 to 2 hours. The prepared VO2 / PCM composite material fixes VO2 through the phase change energy storage material, solving the problem of VO2's inconvenience in processing. The thickness of the VO2 / PCM composite material obtained in this step is approximately 0.19 to 0.21 cm.

[0034] In step (3) above, the purpose is to composite VO2 onto the substrate. The ambient temperature in steps (31) and (32) is preferably 60 to 140°C, and is maintained at this ambient temperature for about 30 min to 1.5 h. At this temperature, the phase change energy storage material is first absorbed into the Ag / LSW substrate; then, based on this, the VO2 / PCM composite material obtained in step (2) is coated on the surface of the Ag / LSW substrate (the other side of the Ag / LSW substrate without binder). By combining the phase change energy storage material with the phase change energy storage material absorbed into the Ag / LSW substrate, VO2 is fixed on the surface of the Ag / LSW substrate.

[0035] Compared with existing technologies, the electromagnetic shielding material and its preparation method that enable intelligent temperature control provided by this invention have the following beneficial effects:

[0036] 1) The electromagnetic shielding material provided by this invention is composed of an Ag / LSW substrate and a VO2 / PCM layer. The Ag / LSW substrate is used as a substrate and VO2 is used as a switch. The material can achieve the first temperature warning in the electromagnetic wave scene, and then the VO2 can be used to start autonomous temperature control, thereby realizing intelligent temperature control.

[0037] 2) The electromagnetic shielding material provided by this invention has a dense silver layer, which gives it excellent shielding performance against electromagnetic waves.

[0038] 3) The Ag / LSW substrate provided by this invention can also support phase change energy storage materials, which can store and release energy in the form of latent heat, thereby giving the composite material excellent temperature control effect;

[0039] 4) The present invention first combines VO2 with phase change energy storage material, and fixes VO2 through phase change energy storage material, thereby facilitating the processing of VO2. Attached Figure Description

[0040] Figure 1 The XRD patterns of VO2 before and after paraffin doping prepared in Example 3 of this invention are shown.

[0041] Figure 2 The XRD patterns of the Ag / LSW substrate prepared in Example 3 of this invention before and after paraffin doping are shown.

[0042] Figure 3 This is a SEM image of the Ag / LSW substrate prepared in Example 3 of the present invention;

[0043] Figure 4 This is a SEM image of the VO2 / WAX composite material prepared in Example 3 of the present invention;

[0044] Figure 5 Comparison of the electromagnetic shielding performance of BCE aerogels prepared in Examples 1, 2, 3, and 4 of this invention;

[0045] Figure 6 The phase transition enthalpy of the BCE aerogel prepared in Example 3 of this invention;

[0046] Figure 7 Thermographic image of the BCE aerogel prepared in Example 3;

[0047] Figure 8 The images show the DSC spectra of the BCE aerogel prepared in Example 3 of this invention before and after 120 cycles. Detailed Implementation

[0048] The technical solutions of various embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The materials used in the following embodiments are as follows:

[0050] Solid leather waste (LSW) from sheepskin was supplied by Xuzhou Xingning Leather Co., Ltd. (Jiangsu, China) using a commercial chrome tanning process.

[0051] Polyvinyl alcohol (PVA) 1799 (average degree of polymerization: 1799±50) was purchased from Chengdu Kelong Chemical Co., Ltd.

[0052] Silver nitrate, dopamine hydrochloride, Tris buffer, hydrochloric acid, anhydrous ethanol, potassium sodium tartrate tetrahydrate (C4H4O6KNa·4H2O), ammonia (NH3·H2O), and glucose (C6H4O6KNa·4H2O). 12 O6·H2O (98%) was purchased from Chengdu Jinshan Chemical Reagent Co., Ltd. All reagents were used immediately upon receipt without further purification.

[0053] Vanadium(IV) oxide (VO2) was purchased from Wuhan Yaolanqu Pharmaceutical Chemical Co., Ltd.

[0054] High-efficiency sliced ​​paraffin (WAX) was purchased from Shanghai Huayong Paraffin Co., Ltd.

[0055] Unless otherwise specified, the solvent used in the solutions described in the following examples is deionized water.

[0056] Example 1

[0057] The electromagnetic shielding material provided in this embodiment is prepared using the following steps:

[0058] (1) Preparation of Ag / LSW substrate, including the following steps:

[0059] (11) Using a solid-phase mechanochemical reactor, 2g of LSW was broken into LSW fibers at a speed of 50 rpm for 15 grinding cycles; then, LSW powder was obtained by sieving with a sieve (100 mesh); the obtained LSW powder was vacuum dried at 105°C for 12 h.

[0060] 0.1212 g Tris was dissolved in deionized water at room temperature, and the pH was adjusted to approximately 8.5. Then, 0.1 g dopamine hydrochloride and 2 g LSW powder were added to the solution. The solution was then diluted to volume with a 100 mL volumetric flask and stirred magnetically for 8 hours to form a polydopamine (PDA) layer on the surface of the LSW powder. The solution was then washed with deionized water and vacuum dried at 40 °C for 12 hours to obtain PDA-modified LSW powder.

[0061] (12) Add ammonia water (concentration of 25-28%) dropwise into silver nitrate solution (containing 6g of silver nitrate) until the solution becomes clear (observe by placing white paper under the container), and then continue to add deionized water to make up to 50mL of solution A, with a silver nitrate concentration of 120g / L.

[0062] (13) Add deionized water to a container containing 10g glucose, 0.25g tetrahydrate and sodium potassium tartrate (C4H4O6KNa·4H2O), 0.01g polyethylene glycol 1000 and 10mL anhydrous ethanol to make up to 50mL. Mix well to obtain 50mL solution B; the concentration of glucose is 200g / L, the concentration of tetrahydrate and sodium potassium tartrate is 5g / L, and the concentration of polyethylene glycol 1000 is 0.2g / L.

[0063] (14) The modified LSW powder obtained in step (11) is mixed with 50 mL of solution A and 50 mL of solution B, magnetically stirred for 0.5 h, then soaked and allowed to stand for 6 h, then washed with deionized water, and vacuum dried at 40 °C for 6 h to obtain Ag / LSW composite material.

[0064] (15) The Ag / LSW composite material obtained in step (14) is uniformly dispersed in 100 mL of deionized water. The resulting dispersion is vacuum filtered to obtain an Ag / LSW composite membrane. About 4 mL of PVA solution (PVA concentration of 10 wt%) is coated on a PTFE plate. The prepared Ag / LSW composite membrane is then placed on top of the PVA solution and vacuum dried at 40 °C for 6 h to obtain an Ag / LSW substrate layer with a thickness of 1.8 cm.

[0065] (2) In an oven at 80°C, place paraffin wax on top of the Ag / LSW substrate and heat for about 1 hour until the paraffin wax is absorbed into the Ag / LSW substrate. The paraffin wax accounts for 26% of the total mass of the Ag / LSW substrate and the paraffin wax. Since it does not contain VO2, it is designated as BCJ fabric-0.

[0066] Example 2

[0067] The electromagnetic shielding material provided in this embodiment is prepared using the following steps:

[0068] (1) Preparation of Ag / LSW substrate, including the following steps:

[0069] (11) Using a solid-phase mechanochemical reactor, 2g of LSW was broken into LSW fibers at a speed of 50 rpm for 15 grinding cycles; then, LSW powder was obtained by sieving with a sieve (100 mesh); the obtained LSW powder was vacuum dried at 105°C for 12 h.

[0070] 0.1212 g Tris was dissolved in deionized water at room temperature, and the pH was adjusted to approximately 8.5. Then, 0.1 g dopamine hydrochloride and 2 g LSW powder were added to the solution. The solution was then diluted to volume with a 100 mL volumetric flask and stirred magnetically for 8 hours to form a polydopamine (PDA) layer on the surface of the LSW powder. The solution was then washed with deionized water and vacuum dried at 40 °C for 12 hours to obtain PDA-modified LSW powder.

[0071] (12) Add ammonia water (concentration of 25-28%) dropwise into silver nitrate solution (containing 6g of silver nitrate) until the solution becomes clear (observe by placing white paper under the container), and then continue to add deionized water to make up to 50mL of solution A, with a silver nitrate concentration of 120g / L.

[0072] (13) Add deionized water to a container containing 10g glucose, 0.25g tetrahydrate and sodium potassium tartrate (C4H4O6KNa·4H2O), 0.01g polyethylene glycol 1000 and 10mL anhydrous ethanol to make up to 50mL. Mix well to obtain 50mL solution B; the concentration of glucose is 200g / L, the concentration of tetrahydrate and sodium potassium tartrate is 5g / L, and the concentration of polyethylene glycol 1000 is 0.2g / L.

[0073] (14) The modified LSW powder obtained in step (11) is mixed with 50 mL of solution A and 50 mL of solution B, magnetically stirred for 1 h, then soaked and allowed to stand for 8 h, then washed with deionized water, and vacuum dried at 40 °C for 6 h to obtain Ag / LSW composite material.

[0074] (15) The Ag / LSW composite material obtained in step (14) is uniformly dispersed in 100 mL of deionized water. The resulting dispersion is vacuum filtered to obtain an Ag / LSW composite membrane. About 4 mL of PVA solution (PVA concentration of 10 wt%) is coated on a PTFE plate. The prepared Ag / LSW composite membrane is then placed on top of the PVA solution and vacuum dried at 40 °C for 6 h to obtain an Ag / LSW substrate layer with a thickness of 1.8 cm.

[0075] (2) Preparation of VO2 / WAX composite materials

[0076] VO2 and paraffin were placed in a beaker at a mass ratio of 1:9, and the VO2 / WAX composite material was obtained by mechanical stirring at 250 rpm for 1 h in an oil bath at 120 °C.

[0077] (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / WAX composite material includes the following steps:

[0078] (31) In an oven at 80°C, paraffin wax is placed on top of the Ag / LSW substrate and heated for about 1 hour until the paraffin wax is absorbed into the Ag / LSW substrate. The paraffin wax accounts for 26% of the total mass of the Ag / LSW substrate and the paraffin wax.

[0079] (32) The hot VO2 / WAX composite material mixed in step (2) is directly coated on the upper surface of the Ag / LSW substrate (thickness is 0.2cm), and then placed in an oven at 80℃ for about 1 hour. After that, it is cooled at room temperature to obtain the electromagnetic shielding material, which is denoted as BCJ fabric-10.

[0080] Example 3

[0081] The electromagnetic shielding material provided in this embodiment is prepared using the following steps:

[0082] (1) Preparation of Ag / LSW substrate, including the following steps:

[0083] (11) Using a solid-phase mechanical chemical reactor, 2g of LSW was unbundled into LSW fibers at a speed of 50rpm after 15 grinding cycles; then, LSW powder was obtained by sieving with a sieve (100 mesh); the obtained LSW powder was vacuum dried at 105℃ for 12h.

[0084] 0.1212 g Tris was dissolved in deionized water at room temperature, and the pH was adjusted to approximately 8.5. Then, 0.1 g dopamine hydrochloride and 2 g LSW powder were added to the solution. The solution was then diluted to volume with a 100 mL volumetric flask and stirred magnetically for 8 hours to form a polydopamine (PDA) layer on the surface of the LSW powder. The solution was then washed with deionized water and vacuum dried at 40 °C for 12 hours to obtain PDA-modified LSW powder.

[0085] (12) Add ammonia water (concentration of 25-28%) dropwise into 150mL of silver nitrate solution (containing 6g of silver nitrate) until the solution becomes clear (observe by placing white paper under the container), and then continue to add deionized water to make up to 50mL of solution A, with a silver nitrate concentration of 120g / L.

[0086] (13) Add deionized water to a container containing 10g glucose, 0.25g tetrahydrate and sodium potassium tartrate (C4H4O6KNa·4H2O), 0.01g polyethylene glycol 1000 and 10mL anhydrous ethanol to make up to 50mL. Mix well to obtain 50mL solution B; the concentration of glucose is 200g / L, the concentration of tetrahydrate and sodium potassium tartrate is 5g / L, and the concentration of polyethylene glycol 1000 is 0.2g / L.

[0087] (14) The modified LSW powder obtained in step (11) is mixed with 50 mL of solution A and 50 mL of solution B, magnetically stirred for 0.5 h, then soaked and allowed to stand for 6 h, then washed with deionized water, and vacuum dried at 40 °C for 6 h to obtain Ag / LSW composite material.

[0088] (15) The Ag / LSW composite material obtained in step (14) is uniformly dispersed in 100 mL of deionized water. The resulting dispersion is vacuum filtered to obtain an Ag / LSW composite membrane. Approximately 4 mL of PVA solution (PVA concentration of 10 wt%) is applied to the PVA solution on a PTFE plate. The prepared Ag / LSW composite membrane is then placed on top of the PVA solution and vacuum dried at 40 °C for 6 h to obtain an Ag / LSW substrate layer with a thickness of 1.8 cm.

[0089] (2) Preparation of VO2 / WAX composite materials

[0090] VO2 and paraffin were placed in a beaker at a mass ratio of 1:3, and the VO2 / WAX composite material was obtained by mechanical stirring at 350 rpm for 2 hours in an oil bath at 120°C.

[0091] (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / WAX composite material includes the following steps:

[0092] (31) In an oven at 80°C, paraffin wax is placed on top of the Ag / LSW substrate and heated for about 1 hour until the paraffin wax is absorbed into the Ag / LSW substrate. The paraffin wax accounts for 26% of the total mass of the Ag / LSW substrate and the paraffin wax.

[0093] (32) The hot VO2 / WAX composite material mixed in step (2) is directly coated on the upper surface of the Ag / LSW substrate (thickness is 0.2cm), and then placed in an oven at 80℃ for about 1 hour. After that, it is cooled at room temperature to obtain the electromagnetic shielding material, which is denoted as BCJ fabric-25.

[0094] Example 4

[0095] The electromagnetic shielding material provided in this embodiment is prepared using the following steps:

[0096] (1) Preparation of Ag / LSW substrate, including the following steps:

[0097] (11) Using a solid-phase mechanical chemical reactor, 2g of LSW was unbundled into LSW fibers at a speed of 50rpm after 15 grinding cycles; then, LSW powder was obtained by sieving with a sieve (100 mesh); the obtained LSW powder was vacuum dried at 105℃ for 12h.

[0098] 0.1212 g Tris was dissolved in deionized water at room temperature, and the pH was adjusted to approximately 8.5. Then, 0.1 g dopamine hydrochloride and 2 g LSW powder were added to the solution. The solution was then diluted to volume with a 100 mL volumetric flask and stirred magnetically for 8 hours to form a polydopamine (PDA) layer on the surface of the LSW powder. The solution was then washed with deionized water and vacuum dried at 40 °C for 12 hours to obtain PDA-modified LSW powder.

[0099] (12) Add ammonia water (concentration of 25-28%) dropwise into silver nitrate solution (containing 6g of silver nitrate) until the solution becomes clear (observe by placing white paper under the container), and then continue to add deionized water to make up to 50mL of solution A, with a silver nitrate concentration of 120g / L.

[0100] (13) Add deionized water to a container containing 10g glucose, 0.25g tetrahydrate and sodium potassium tartrate (C4H4O6KNa·4H2O), 0.01g polyethylene glycol 1000 and 10mL anhydrous ethanol to make up to 50mL. Mix well to obtain 50mL solution B; the concentration of glucose is 200g / L, the concentration of tetrahydrate and sodium potassium tartrate is 5g / L, and the concentration of polyethylene glycol 1000 is 0.2g / L.

[0101] (14) The modified LSW powder obtained in step (11) is mixed with 50 mL of solution A and 50 mL of solution B, magnetically stirred for 0.5 h, then soaked and allowed to stand for 6 h, then washed with deionized water, and vacuum dried at 40 °C for 6 h to obtain Ag / LSW composite material.

[0102] (15) The Ag / LSW composite material obtained in step (14) is uniformly dispersed in 100 mL of deionized water. The resulting dispersion is vacuum filtered to obtain an Ag / LSW composite membrane. Approximately 4 mL of PVA solution (PVA concentration of 10 wt%) is applied to the PVA solution on a PTFE plate. The prepared Ag / LSW composite membrane is then placed on top of the PVA solution and vacuum dried at 40 °C for 6 h to obtain an Ag / LSW substrate layer with a thickness of 1.8 cm.

[0103] (2) Preparation of VO2 / WAX composite materials

[0104] VO2 and paraffin were placed in a beaker at a mass ratio of 1:1, and the VO2 / WAX composite material was obtained by mechanical stirring at 300 rpm for 1 h in an oil bath at 120 °C.

[0105] (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / WAX composite material includes the following steps:

[0106] (31) In an oven at 80°C, paraffin wax is placed on top of the Ag / LSW substrate and heated for about 1 hour until the paraffin wax is absorbed into the Ag / LSW substrate. The paraffin wax accounts for 26% of the total mass of the Ag / LSW substrate and the paraffin wax.

[0107] (32) The hot VO2 / WAX composite material mixed in step (2) is directly coated on the upper surface of the Ag / LSW substrate (thickness is 0.2cm), and then placed in an oven at 80°C for about 1 hour. After that, it is cooled at room temperature to obtain the electromagnetic shielding material, which is denoted as BCJ fabric-50.

[0108] Example 5

[0109] The electromagnetic shielding material provided in this embodiment is prepared using the following steps:

[0110] (1) Preparation of Ag / LSW substrate, including the following steps:

[0111] (11) Using a solid-phase mechanical chemical reactor, 2g of LSW was unbundled into LSW fibers at a speed of 50rpm after 15 grinding cycles; then, LSW powder was obtained by sieving with a sieve (100 mesh); the obtained LSW powder was vacuum dried at 105℃ for 12h.

[0112] 0.1212 g Tris was dissolved in deionized water at room temperature, and the pH was adjusted to approximately 8.5. Then, 0.1 g dopamine hydrochloride and 2 g LSW powder were added, and the solution was brought to a final volume in a 100 mL volumetric flask. The solution was then magnetically stirred for 8 h to form a polydopamine (PDA) layer on the surface of the LSW powder. The solution was then washed with deionized water and vacuum dried at 80 °C for 12 h to obtain PDA-modified LSW powder.

[0113] (12) Add ammonia water (concentration of 25-28%) dropwise into silver nitrate solution (containing 5.6g silver nitrate) until the solution becomes clear (observe by placing white paper under the container), and then continue to add deionized water to make up to 50mL of solution A, with a silver nitrate concentration of 112g / L.

[0114] (13) Add deionized water to a container containing 10g glucose, 0.25g tetrahydrate and sodium potassium tartrate (C4H4O6KNa·4H2O), 0.01g polyethylene glycol 1000 and 5mL anhydrous ethanol to make up to 50mL. Mix well to obtain 50mL solution B; the concentration of glucose is 200g / L, the concentration of tetrahydrate and sodium potassium tartrate is 5g / L, and the concentration of polyethylene glycol 1000 is 0.2g / L.

[0115] (14) The modified LSW powder obtained in step (11) is mixed with 50 mL of solution A and 50 mL of solution B, magnetically stirred for 0.5 h, then soaked and allowed to stand for 8 h, then washed with deionized water, and vacuum dried at 60 °C for 5.5 h to obtain Ag / LSW composite material.

[0116] (15) The Ag / LSW composite material obtained in step (14) is uniformly dispersed in 100 mL of deionized water. The resulting dispersion is vacuum filtered to obtain an Ag / LSW composite membrane. Approximately 4 mL of PVP solution (PVP concentration of 10 wt%) is applied to a PTFE plate. The prepared Ag / LSW composite membrane is then placed on top of the PVP solution and vacuum dried at 50 °C for 6 h to obtain an Ag / LSW substrate layer with a thickness of 1.8 cm.

[0117] (2) Preparation of VO2 / WAX composite materials

[0118] VO2 and paraffin were placed in a beaker at a mass ratio of 1:9, and the VO2 / WAX composite material was obtained by mechanical stirring at 300 rpm for 2 hours in an oil bath at 100°C.

[0119] (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / WAX composite material includes the following steps:

[0120] (31) In an oven at 60°C, place paraffin wax on top of the Ag / LSW substrate and heat for about 1.5 hours until the paraffin wax is absorbed into the Ag / LSW substrate. The paraffin wax accounts for 20% of the total mass of the Ag / LSW substrate and the paraffin wax.

[0121] (32) The hot VO2 / WAX composite material mixed in step (2) is directly coated on the upper surface of the Ag / LSW substrate (thickness is 0.2cm), and then placed in an oven at 60°C for about 1.5h. After that, it is cooled at room temperature to obtain the electromagnetic shielding material.

[0122] Example 6

[0123] The electromagnetic shielding material provided in this embodiment is prepared using the following steps:

[0124] (1) Preparation of Ag / LSW substrate, including the following steps:

[0125] (11) Using a solid-phase mechanical chemical reactor, 2g of LSW was unbundled into LSW fibers at a speed of 50rpm after 15 grinding cycles; then, LSW powder was obtained by sieving with a sieve (100 mesh); the obtained LSW powder was vacuum dried at 105℃ for 12h.

[0126] 0.1212 g Tris was dissolved in deionized water at room temperature, and the pH was adjusted to approximately 8.5. Then, 0.1 g dopamine hydrochloride and 2 g LSW powder were added, and the solution was brought to a final volume in a 100 mL volumetric flask. The solution was then magnetically stirred for 8 h to form a polydopamine (PDA) layer on the surface of the LSW powder. The solution was then washed with deionized water and vacuum dried at 60 °C for 18 h to obtain PDA-modified LSW powder.

[0127] (12) Add ammonia water (concentration of 25-28%) dropwise into silver nitrate solution (containing 6.4g silver nitrate) until the solution becomes clear (observe by placing white paper under the container), and then continue to add deionized water to make up to 50mL of solution A, with a silver nitrate concentration of 128g / L.

[0128] (13) Add deionized water to a container containing 10g glucose, 0.25g tetrahydrate and sodium potassium tartrate (C4H4O6KNa·4H2O), 0.01g polyethylene glycol 1000 and 15mL anhydrous ethanol to make up to 50mL. Mix well to obtain 50mL solution B; the concentration of glucose is 200g / L, the concentration of tetrahydrate and sodium potassium tartrate is 5g / L, and the concentration of polyethylene glycol 1000 is 0.2g / L.

[0129] (14) The modified LSW powder obtained in step (11) is mixed with 50 mL of solution A and 50 mL of solution B, magnetically stirred for 0.5 h, then soaked and allowed to stand for 8 h, then washed with deionized water, and vacuum dried at 40 °C for 6.5 h to obtain Ag / LSW composite material.

[0130] (15) The Ag / LSW composite material obtained in step (14) is uniformly dispersed in 100 mL of deionized water. The resulting dispersion is vacuum filtered to obtain an Ag / LSW composite membrane. Approximately 4 mL of PAA solution (PAA concentration of 10 wt%) is applied to the PAA plate. The prepared Ag / LSW composite membrane is then placed on top of the PAA solution and vacuum dried at 50 °C for 6 h to obtain an Ag / LSW substrate layer with a thickness of 1.8 cm.

[0131] (2) Preparation of VO2 / WAX composite materials

[0132] VO2 and paraffin were placed in a beaker at a mass ratio of 1:1 and mechanically stirred at 300 rpm for 1 h in an oil bath at 140 °C to obtain a VO2 / WAX composite material.

[0133] (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / WAX composite material includes the following steps:

[0134] (31) In an oven at 140°C, place paraffin wax on top of the Ag / LSW substrate and heat for about 30 minutes until the paraffin wax is absorbed into the Ag / LSW substrate. The paraffin wax accounts for 23% of the total mass of the Ag / LSW substrate and the paraffin wax.

[0135] (32) The hot VO2 / WAX composite material mixed in step (2) is directly coated on the surface of the Ag / LSW substrate (thickness is 0.2cm), and then placed in an oven at 140℃ for about 30 minutes. After that, it is cooled at room temperature to obtain the electromagnetic shielding material.

[0136] The structure and properties of the electromagnetic shielding materials prepared in the above embodiments were characterized.

[0137] (I) Structural Characterization

[0138] XRD tests were performed on VO2 and the VO2 / WAX composite material prepared in Example 3. The test results are as follows: Figure 1 As shown. From Figure 1 As can be seen, the target product, the VO2 / WAX composite material, was successfully prepared. SEM testing was performed on the VO2 / WAX composite material prepared in Example 3, and the results are as follows: Figure 4 As shown, from Figure 4 It can be seen that VO2 and paraffin (WAX) are well combined and easy to process.

[0139] XRD tests were performed on the Ag / LSW substrate prepared in Example 3 before and after paraffin inhalation. The test results are as follows: Figure 2 As shown. From Figure 2 As can be seen, paraffin wax was successfully loaded into the Ag / LSW substrate, which can provide phase change energy storage and realize intelligent temperature control.

[0140] The Ag / LSW substrate prepared in Example 3 was subjected to SEM testing, and the results are as follows: Figure 3 As shown, from Figure 3 As can be seen, there is a dense silver layer wrapped around the surface of the LSW fiber in the Ag / LSW substrate. Since silver can provide electromagnetic shielding performance, the substrate has good electromagnetic shielding properties.

[0141] (II) Electromagnetic shielding performance

[0142] The electromagnetic shielding performance of the electromagnetic shielding materials prepared in Examples 1, 2, 3, and 4 was characterized and compared. The results are as follows: Figure 5 As shown.

[0143] As can be seen from the figure, the electromagnetic shielding effect is generally poor when no VO2 / WAX layer is set; however, the electromagnetic shielding performance is significantly improved when a VO2 / WAX layer is set.

[0144] (III) Thermal properties

[0145] The electromagnetic shielding material BCJ fabric-25 prepared in Example 3 was subjected to phase transition enthalpy, thermal imaging, and DSC cycle tests. The results are as follows: Figure 6 , Figure 7 , Figure 8 As shown.

[0146] Phase transition enthalpy testing shows that BCJ aerogel has high melting enthalpy and high crystallization enthalpy, giving it excellent thermal management capabilities.

[0147] In the thermal imaging experiment, BCJ aerogel was irradiated with an infrared lamp to simulate a real-world application scenario. By comparing high-power and low-power irradiation, BCJ aerogel exhibited different response rates, with rapid heating observed under high-power irradiation. Furthermore, the phase transition plateau observed during the heating and cooling processes of BCJ aerogel was consistent with the results of differential scanning calorimetry (DSC) measurements.

[0148] Excellent durability is essential to ensure a long service life for BCJ aerogels, and service life is also crucial for evaluating the suitability of materials. Cyclic DSC experiments were used to evaluate the durability of BCJ aerogels. Figure 8 The DSC curve after 120 cycles almost overlapped with the original curve, indicating that BCE aerogel has excellent thermal reliability.

[0149] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for preparing an electromagnetic shielding material capable of intelligent temperature control, characterized in that, Includes the following steps: (1) Preparation of Ag / LSW substrate, including the following steps: (11) Prepare leather waste powder and modify it with polydopamine to obtain modified leather waste powder; (12) Preparation of solution A: Under stirring conditions, ammonia water is added dropwise to silver nitrate solution until the solution becomes clear, thus obtaining solution A; (13) Preparation of solution B: Glucose, tetrahydrate and potassium sodium tartrate, polyethylene glycol and anhydrous ethanol are mixed evenly in water to obtain solution B; (14) The modified leather waste powder is mixed with solution A and solution B, stirred and mixed evenly, and then left to stand for 6-8 hours. After washing and drying, Ag / LSW composite material is obtained. (15) The Ag / LSW composite material is uniformly dispersed in water, and the resulting dispersion is then vacuum filtered to obtain an Ag / LSW composite membrane; the Ag / LSW composite membrane is fixed with an adhesive to obtain an Ag / LSW substrate layer; (2) Preparation of VO2 / PCM composite materials VO2 and phase change energy storage material were stirred and mixed uniformly at a temperature higher than the melting point of the phase change energy storage material to obtain VO2 / PCM composite material; (3) The preparation of electromagnetic shielding materials by combining Ag / LSW substrate with VO2 / PCM composite material includes the following steps: (31) At an ambient temperature higher than the melting point of the phase change energy storage material, the phase change energy storage material is drawn into the Ag / LSW substrate layer; (32) At an ambient temperature higher than the melting point of the phase change energy storage material, the VO2 / PCM composite material obtained in step (2) is composited onto the surface of the Ag / LSW substrate and cooled at room temperature to obtain an electromagnetic shielding material.

2. The method for preparing an electromagnetic shielding material capable of intelligent temperature control according to claim 1, characterized in that, In step (11), solid leather waste is first prepared into LSW fibers through solid-phase grinding and shearing technology for 15-20 grinding cycles at a speed of 50-80 rpm; then the LSW fibers are sieved to obtain LSW powder; the obtained LSW powder is vacuum dried and then mixed and stirred with dopamine in an alkaline buffer solution, and then washed and dried to obtain modified leather waste powder; the mass ratio of LSW powder to dopamine is 19-21:

1.

3. The method for preparing an electromagnetic shielding material capable of intelligent temperature control according to claim 1, characterized in that, In step (13), the mass ratio of glucose, tetrahydrate, potassium sodium tartrate, and polyethylene glycol is 10:0.25:0.

01.

4. The method for preparing the electromagnetic shielding material capable of intelligent temperature control according to claim 1, characterized in that, In step (2), the mass ratio of VO2 to phase change energy storage material is 1:1~9.

5. The method for preparing an electromagnetic shielding material capable of intelligent temperature control according to claim 1, characterized in that, Step (2) involves stirring and mixing VO2 and phase change energy storage material at 100~140℃ until homogeneous; the ambient temperature in steps (31) and (32) is 60~140℃.

6. An electromagnetic shielding material capable of intelligent temperature control, characterized in that, The electromagnetic shielding material is obtained by the preparation method according to any one of claims 1 to 5; the electromagnetic shielding material includes an Ag / LSW substrate layer, a phase change energy storage material absorbed into the Ag / LSW substrate layer, and VO2 adsorbed on the surface of the Ag / LSW substrate layer; the Ag / LSW substrate layer is obtained by bonding Ag and leather waste with an adhesive.

7. The electromagnetic shielding material capable of intelligent temperature control according to claim 6, characterized in that, The Ag / LSW substrate has a three-dimensional porous structure.

8. The electromagnetic shielding material capable of intelligent temperature control according to claim 6, characterized in that, In the Ag / LSW base layer, the mass ratio of Ag to unmodified leather waste LSW is 1.8~2.0:

1.

9. The electromagnetic shielding material capable of intelligent temperature control according to any one of claims 6 to 8, characterized in that, The leather waste is polydopamine-modified leather waste powder.

10. The electromagnetic shielding material capable of intelligent temperature control according to claim 9, characterized in that, The dopamine can be replaced by vitamin C or catechol; the leather waste can be replaced by cellulose, palm leather, or Lino leather; the binder used to bond the Ag and leather waste is one of polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, or polyacrylic acid; the phase change energy storage material is paraffin wax, coconut oil, or dodecanol.

11. The electromagnetic shielding material capable of intelligent temperature control according to claim 9, characterized in that, The phase change energy storage material absorbed into the Ag / LSW substrate accounts for at least 20% of the total mass of the Ag / LSW substrate and the absorbed phase change energy storage material.

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