Composite film material with dynamic infrared stealth, electromagnetic shielding and thermal management functions and preparation method thereof

Abstract

The application discloses a composite film material with dynamic infrared stealth, electromagnetic shielding and heat management functions and a preparation method and application thereof. The composite film material is a three-layer asymmetric structure. A first outer layer is a nanoporous film for reflecting sunlight and transmitting infrared radiation. A middle layer is a uniform and dense MXene layer for absorbing sunlight, reflecting infrared radiation and shielding electromagnetic interference. A second outer layer is a heat-insulating PDMS layer with a patterned array design for high sunlight transmission and high infrared emissivity. The spectrum-selective nanoporous film / MXene / patterned PDMS composite film material with the asymmetric structure can have good infrared stealth, electromagnetic shielding and heat management performances under high, low and humidity conditions, and can be applied to the fields of shielding stealth and heat management under complex dynamic scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stealth and thermal management materials, in particular to a composite film material with dynamic infrared stealth, electromagnetic shielding and thermal management functions and a preparation method and use thereof. BACKGROUND

[0002] The rapid iteration of modern reconnaissance technology poses a great threat to the survival of military targets. Although visual camouflage has made great progress, reconnaissance in the infrared spectrum is more dangerous because objects with a temperature higher than 0K will emit infrared radiation, and the emitted infrared waves can be clearly identified even in adverse weather conditions. Accordingly, infrared stealth materials for anti-infrared detection are of great significance for preserving the combat effectiveness of soldiers and equipment, gaining the initiative and winning the war.

[0003] The core of infrared stealth technology lies in reducing infrared emissivity and adjusting surface temperature. Generally, the heat insulation and heat flux manipulation design of temperature control materials makes the material thickness large and the structure complex, which is difficult to be compatible with portability and large-scale preparation. Surface emissivity engineering is a strategy to avoid infrared detection by reducing surface infrared radiation. For example, metal coatings are usually applied to static infrared stealth of devices and weapons due to their high reflectivity and low emissivity in the infrared range. However, high-precision processing requirements, corrosion resistance and rigid mechanical properties hinder the human-wearable application of such materials. More importantly, low-emissivity stealth materials can only be used for specific scenarios where the target temperature is higher than the background temperature, such as night and jungle, due to their radiation energy attenuation effect. However, for high-temperature scenarios represented by deserts, it is more reasonable and feasible to compensate the low-emissivity surface of a constant-temperature target with additional radiation energy to match the radiation characteristics of the high-temperature background. X MXene has low emissivity, high electrical conductivity and broad-spectrum light absorption comparable to metals, which can not only be used for infrared stealth and thermal energy supplementation, but also has a lighter weight and easy processability than metal coatings. However, the discomfort caused by the excessive temperature generated by the self-luminescent heat conversion of MXene and its easy oxidation are the difficulties faced by wearable stealth applications in complex conditions. However, corresponding solutions, especially those that simultaneously solve the above problems through a single material or simple method, have received little attention.

[0004] It is a method to reduce the overall light-heat conversion efficiency of the material to compound the light-heat MXene with the material reflecting sunlight, but the polymer material reflecting sunlight often has high infrared absorption characteristics, and the infrared stealth material requires low infrared absorption, and the light-heat compensation requires the material to have high sunlight absorption and high infrared absorption, and the multiple mechanisms are contradictory to each other, therefore, it is still a challenge to realize the switchable infrared stealth integrated technology of both the high reflection of the sunlight band and the low absorption of the infrared band, and the flexible conversion of both the high absorption of the sunlight band and the high absorption of the infrared band, while realizing the heat management. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a composite film material with dynamic infrared stealth, electromagnetic shielding and heat management functions and a preparation method and application thereof.

[0006] According to a first aspect of the present application, a composite film material with dynamic infrared stealth, electromagnetic shielding and heat management functions is provided, the composite film material is a three-layer asymmetric structure, a first outer layer is a nanoporous film reflecting sunlight and transmitting infrared radiation, a middle layer is a uniform and dense MXene layer absorbing sunlight, reflecting infrared radiation and shielding electromagnetic interference, and a second outer layer is a patterned array designed heat insulation PDMS layer with high sunlight transmission and high infrared emissivity.

[0007] In some exemplary embodiments, the nanoporous film is a polytetrafluoroethylene film, a polyethylene film or a nylon film.

[0008] In some exemplary embodiments, the thickness of the first outer layer nanoporous film is 20-50 μm, the thickness of the middle layer MXene layer is 2-10 μm, the thickness of the second outer layer patterned PDMS layer is 500-2000 μm, and the overall thickness of the composite film material is 512-2060 μm.

[0009] In some exemplary embodiments, the pattern design of the second outer layer patterned PDMS layer is a plane, or any one of 5x5, 10x10, 20x20 and 40x40 cone arrays, or any one of 5x5, 10x10, 20x20 and 40x40 column arrays.

[0010] According to a second aspect of the present application, a preparation method of a composite film material with dynamic infrared stealth, electromagnetic shielding and heat management functions is provided, which comprises: preparing a MXene slurry; preparing a patterned PDMS layer; hydrophilic modification of a nanoporous film; and sequentially compounding the prepared MXene slurry and patterned PDMS layer on the modified nanoporous film to prepare the composite film material with a three-layer asymmetric structure of a nanoporous film layer, a MXene layer and a patterned PDMS layer.

[0011] In some exemplary embodiments, the step of preparing the MXene slurry further comprises: adding 1 part of Ti3AlC2 powder into concentrated HC1 with 1.6 parts of LiF, and preparing a Ti3C2Tx suspension by etching for 36 h at a temperature of 35 °C; after the Ti3C2Tx suspension is filtered and washed with water, centrifuging 5 times at 8000 rpm until the pH value is close to 7; and obtaining a single-layer MXene suspension by ultrasonic treatment for 0.5 h under nitrogen and ice bath conditions, and centrifuging at 3500 rpm for 1 h.

[0012] In some exemplary embodiments, the step of preparing the patterned PDMS layer further comprises: preparing a patterned template by a 3D printing technology, wherein the patterned array in the patterned template is designed as a plane, or any one of 5x5, 10x10, 20x20 and 40x40 cone arrays, or any one of 5x5, 10x10, 20x20 and 40x40 column arrays, and the array height is 500-2000 pm; coating a mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent on the prepared patterned template; and curing the mixture at a uniform temperature of 60-80 °C for 1-4 h to obtain the patterned PDMS film.

[0013] In some exemplary embodiments, the step of preparing the patterned PDMS layer further comprises: preparing a patterned template by a 3D printing technology, wherein the patterned array in the patterned template is designed as a 10x10 cone array, and the array height is 1000 pm; coating a mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent on the prepared patterned template; and curing the mixture at a uniform temperature of 70 °C for 2 h to obtain the patterned PDMS film.

[0014] In some exemplary embodiments, the cone diameter of the obtained patterned PDMS film is 4000 pm, the cone spacing is 1000 pm, and the air layer occupies a volume of 2081 mm 3 The overall thickness of the patterned PDMS film is 1000 pm.

[0015] In some exemplary embodiments, the step of hydrophilic modification of the nanoporous membrane further comprises: dissolving 1-3 parts of dopamine hydrochloride in a Tris buffer with a pH of 7-9 to prepare a dopamine buffer solution; and soaking the nanoporous membrane in the prepared buffer solution for 12-36 hours to obtain a hydrophilic nanoporous membrane.

[0016] In some exemplary embodiments, the preparation of the composite film material further comprises: uniformly doctoring the prepared MXene slurry on the modified nanoporous film using a doctor blade with a thickness of 200-1000 pm; compounding the prepared patterned PDMS film on the surface of the MXene slurry; and drying at room temperature to obtain a nanoporous film / MXene / patterned PDMS composite film material with a three-layer asymmetric structure.

[0017] According to a third aspect of the present application, there is provided a use of a composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions, the composite film material being the composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions described above or prepared by the preparation method of the composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions described above, the composite film material being used for infrared stealth, electromagnetic shielding and / or thermal management.

[0018] According to the present application, by designing a spectrum-selective nanoporous film / MXene / patterned PDMS composite film with an asymmetric structure, good infrared stealth, electromagnetic shielding and thermal management performance can be achieved under high, low temperature and humidity conditions, and the composite film material can be applied to the fields of shielding and stealth and thermal management in complex dynamic scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following is a description of the drawings needed in the description of the embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0020] Figure 1 Flowchart of the preparation method of the composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions of the present application.

[0021] Figure 2 Flowchart of the preparation method of the composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions of the present application.

[0022] Figure 3 Optical picture of the 10x10 conical PDMS film prepared in Example 1 of the present application.

[0023] Figure 4 Graph showing the thermal insulation performance of the PDMS films prepared in Examples 1, 4-5 and Examples 6-8 of the present application.

[0024] Figure 5Figures showing the properties of the composite film material prepared in Example 1 of the present application, a is a temperature-time curve, b and c are infrared images of the composite film material.

[0025] Figure 6 Figures showing the optical properties of the composite film material prepared in Example 3 of the present application at different wavebands.

[0026] Figure 7 Figures showing the properties of the composite film material prepared in Example 3 of the present application, a is an interface temperature curve, and b is a surface radiant temperature curve.

[0027] Figure 8 Optical pictures of the PDMS films prepared in Example 4 and Example 5 of the present application, a is an optical picture of the 10x10 columnar PDMS film of Example 4, and b is an optical picture of the planar PDMS film of Example 5.

[0028] Figure 9 Optical pictures of the PDMS films prepared in Example 6-8 of the present application, a is an optical picture of the 5x5 conical PDMS film of Example 6, b is an optical picture of the 20x20 conical PDMS film of Example 7, and c is an optical picture of the 40x40 conical PDMS film of Example 8. DETAILED DESCRIPTION

[0029] The essence of the technical solution of the present application is described in detail below.

[0030] The present application proposes a multi-layer material composite film and a preparation method thereof, which utilizes the selective optical properties of the solar spectrum and the infrared spectrum to selectively reflect or absorb sunlight and reflect or emit infrared radiation in different application scenarios, while shielding electromagnetic interference and blocking water molecules from contacting MXene, thereby achieving multiple purposes such as infrared stealth, human thermal management, electromagnetic shielding, and oxidation resistance. Specifically, the present application proposes a spectrum-selective nano-porous film / MXene / patterned PDMS composite film material with an asymmetric structure and a preparation method thereof, which achieves excellent infrared stealth in the ambient temperature through the synergistic effect of effective heat transfer inhibition of the patterned PDMS layer and effective infrared reflection of the MXene layer. At the same time, through the high solar reflectance and infrared transmission behavior of the external nano-porous film, the photo-thermal conversion is weakened without hindering the low-emissivity property of the surface, thereby reducing the photo-thermal temperature and achieving thermal management. In addition, after the composite film is simply flipped over, the patterned PDMS layer can effectively transmit sunlight to the MXene layer, and then efficiently radiate the heat energy generated by photo-thermal or electro-thermal conversion to the surface, actively compensating for the radiant energy, thereby achieving thermal camouflage for instant switching in a high-temperature background. In addition, the composite film material of the present application also has electromagnetic interference shielding, oxidation resistance stability, and stretchability, self-cleaning, and other wearable properties.

[0031] Figure 1 A flow chart of the preparation method of the composite film material with dynamic infrared stealth, electromagnetic shielding and thermal management functions of the present application is shown, Figure 2 The flow chart of the preparation method of the composite film material with dynamic infrared stealth, electromagnetic shielding and thermal management functions of the present application is shown. Figure 1 、 2 The preparation method of the composite film material with dynamic infrared stealth, electromagnetic shielding and thermal management functions of the present application comprises the following steps.

[0032] In step 101, MXene slurry is prepared.

[0033] Specifically, in this step, first, 1-3 parts of Ti3AlC2 powder are added into concentrated HCl with LiF dissolved therein, and etching is carried out at a temperature of 35-40℃ for 36-48h to prepare a Ti3C2Tx suspension; then, after water washing by suction filtration, centrifugation is carried out at 5000-10000 rpm for 2-5 times until the pH value approaches 7; next, ultrasonic treatment is carried out under nitrogen and ice bath conditions for 0.5-1h, and centrifugation is carried out at 2500-4000 rpm for 0.5-1h to obtain a suspension of single-layer MXene.

[0034] In step 102, a patterned PDMS (polydimethylsiloxane) film is prepared.

[0035] Specifically, in this step, a patterned template is prepared by 3D printing technology, and the patterned array in the patterned template can be designed as a plane, or any one of 5×5, 10×10, 20×20 and 40×40 cone arrays and 5×5, 10×10, 20×20 and 40×40 column arrays, and is preferably a 10×10 cone array; the array height is set to 500-2000μm, and is preferably 1000μm. A mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent is scraped on the prepared patterned template, and then curing is carried out at a uniform temperature of 60-80℃ for 1-4h to obtain a patterned PDMS film.

[0036] In the present application, the thickness of the patterned PDMS film is preferably 500-2000μm, and more preferably 1000μm.

[0037] In step 103, the nanoporous film is hydrophilically modified.

[0038] Specifically, in this step, 1-3 parts of dopamine hydrochloride is dissolved in a Tris buffer with a pH of 7-9 to prepare a dopamine buffer solution, and then the prepared buffer solution is used to soak the nanoporous film for 12-36 hours to obtain a hydrophilic nanoporous film.

[0039] In the present application, the nanoporous membrane is preferably a polytetrafluoroethylene membrane, a polyethylene membrane or a nylon membrane, and the thickness is preferably 20-50 μm.

[0040] In step 104, a composite membrane material is prepared.

[0041] Specifically, in this step, the prepared MXene slurry is uniformly scraped onto the dopamine-modified nanoporous membrane using a doctor blade with a thickness of 200-1000 μm. Subsequently, the prepared PDMS membrane is combined on the surface of the MXene slurry, and after drying at room temperature, a nanoporous membrane / MXene / patterned PDMS composite membrane material with a three-layer asymmetric structure is obtained.

[0042] In the present application, the thickness of the nanoporous membrane is preferably 20-50 μm, and the overall thickness of the composite membrane material is 512-2060 μm.

[0043] The structure and performance of the above-prepared composite membrane material of the present application are described as follows:

[0044] After the PDMS is cured at 70°C for 3 h, a PDMS membrane with an array number of 10×10 cones is obtained, the cone diameter in the array is 4000 μm, the cone spacing is 1000 μm, and the total thickness of the 10×10 cone PDMS membrane is 1000 μm.

[0045] Under the environmental conditions of 25°C, the surface temperature of the cone PDMS membrane covering the 36°C target is 33.6°C, with a heat insulation effect of 2.4°C.

[0046] Under the environmental conditions of 25.5°C, the surface radiation temperature of the composite membrane material covering the 36°C simulated skin is 28°C, with a temperature difference of 2.5°C from the environment, and the infrared imaging of the simulated skin and the environment is basically consistent, which is difficult to identify by infrared detection, achieving infrared stealth effect; when 5 layers of composite membrane materials are stacked, the surface radiation temperature has a temperature difference of 0.2°C from the environment, almost achieving complete stealth.

[0047] Under the light power density of 80 mW cm -2 Under simulated sunlight conditions, the interface temperature of the composite membrane material and the 36°C simulated skin is 47°C, close to the military polyester fabric, and the surface radiation temperature is 6°C lower than that of the military polyester fabric, with good synchronous infrared stealth performance of skin interface photothermal management.

[0048] Under the light power density of 40 mW cm -2 Under simulated sunlight conditions, the surface temperature of the composite membrane material is 50°C; 60 mW cm -2 Under simulated sunlight conditions, the surface temperature is 64°C; 80 mW cm -2Under simulated sunlight conditions, the surface temperature is 75 DEG C; 100 mW cm -2 Under simulated sunlight conditions, the surface temperature is 82 DEG C, and the light-heat provided thermal energy compensation performance is good.

[0049] When the voltage is 1V, the surface temperature of the composite film material is 32 DEG C; when the voltage is 2V, the surface temperature of the composite film material is 46 DEG C; when the voltage is 3V, the surface temperature of the composite film material is 74 DEG C; when the voltage is 4V, the surface temperature of the composite film material is 100 DEG C, and the electric-heat provided thermal energy compensation performance is good.

[0050] The EMI SE of the double sides of the composite film material in the X wave band is greater than 40 dB, and the electromagnetic shielding performance is good.

[0051] The contact angle of the nano-porous film side of the composite film material is 139 DEG, and the contact angle of the PDMS film side is 120 DEG, and the water-repellent oxidation-resistant and self-cleaning performance is good.

[0052] It can be seen that the spectrum-selective nano-porous film / MXene / patterned PDMS composite film material with an asymmetric structure has good infrared stealth, electromagnetic shielding and thermal management performance under high, low temperature and humidity conditions, and can be applied to the shielding, stealth and thermal management field under complex dynamic scenes, and the composite film material further has the functions of active heating assisted camouflage switching and wide-band electromagnetic shielding.

[0053] The application applies the following four basic principles:

[0054] (1) Infrared stealth principle: the infrared detector identifies the target by the difference of the infrared radiation energy of the target and the background. The infrared radiation energy of the target surface is proportional to the fourth power of the surface emissivity and temperature. The effect of the material on the radiation includes reflection, absorption and transmission. For the gray body material, the absorption rate is equal to the emission rate. The infrared stealth requires that the material has low infrared absorption rate, that is, low infrared emission rate. The emission rate of the material on the radiation is inversely proportional to the intrinsic conductivity of the material, and the material with high carrier concentration and migration rate has low infrared emission rate, so when the temperature of the constant temperature object is higher than the background temperature, the low emission rate of the object reduces the efficiency of the outward emission of the infrared radiation energy, so that the infrared detector can only capture the surface radiation energy of the object close to the low temperature background, that is, the infrared stealth of the target object is realized.

[0055] (2) Solar light reflection principle: the pore size of the nano-porous film matches the visible light wavelength, so that strong Mie scattering can be caused, thereby reflecting the sunlight.

[0056] (3) Infrared radiation transmission principle: the absorption of materials in the infrared band mainly depends on molecular vibration absorption, and the nano-porous film only has simple chemical groups in the atmospheric window, and the vibration absorption in the 8-14 μm band is weak, so it has high infrared transmittance.

[0057] (4) Patterned thermal insulation principle: the heat transfer behavior of the material includes convection, conduction and radiation. The patterned array structure design reduces the contact heat conduction, reflects the heat radiation, and the array gap seals the air layer with low thermal conductivity to form a heat shielding barrier, so it has good thermal insulation performance.

[0058] According to the present application, by compounding materials with different optical properties, the composite film has different optical behaviors in different wave bands and selects different optical properties in different modes, and by patterning the PDMS, the composite film is further endowed with thermal insulation performance, and the infrared stealth performance of the opposite mode is realized. The patterned PDMS layer first contacts the heat source, which reduces the contact heat conduction and seals the low-conductivity air for thermal insulation, the middle layer MXene reflects the infrared radiation and shields the electromagnetic interference, and the nano-porous film reflects the sunlight and transmits the infrared radiation, realizing the shielding infrared stealth with compatible heat management; after simple turning over, the patterned PDMS layer transmits the sunlight, the MXene absorbs the sunlight and provides heat by using the photothermal / electrothermal effect, which is emitted to the surface through the PDMS layer, realizing the compensatory thermal camouflage. Based on the hydrophobicity of the PDMS layer and the nano-porous film on both sides, the composite film also has the performance of oxidation resistance and self-cleaning.

[0059] The technical solutions of the application will be described below in conjunction with specific examples, but the conditions and results described in the implementation do not constitute a limitation on the protection scope of the application. In addition, the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described in the examples can be obtained commercially unless otherwise specified.

[0060] Example 1.

[0061] First, the MXene slurry was prepared. Specifically, first, 1 part of Ti3AlC2 powder was added in concentrated HCl with LiF dissolved therein, and etched at a temperature of 35℃ for 36h to prepare a Ti3C2Tx suspension; then, after water washing by suction filtration, centrifuged at 8000 rpm for 5 times until the pH value was close to 7; then, under the conditions of nitrogen and ice bath, ultrasonic treatment was carried out for 1h, and centrifugation was carried out at 3500 rpm for 0.5h to obtain a suspension of single-layer MXene.

[0062] Next, a patterned PDMS film was prepared. Specifically, a patterned template was prepared using 3D printing technology. The patterned array in the template was designed as a 10×10 cone array with an array height of 1000 μm. A mixture of 10 parts Sylgard 184 silicone elastomer matrix and 1 part crosslinking agent was coated onto the prepared patterned template, and then cured at a uniform temperature of 70°C for 2 hours to obtain the patterned PDMS film.

[0063] Furthermore, the nanoporous polytetrafluoroethylene membrane was hydrophilically modified. Specifically, a dopamine buffer solution was prepared by dissolving two parts of dopamine hydrochloride in a Tris buffer solution at pH 8.5. Then, a 20 μm thick nanoporous polytetrafluoroethylene membrane was soaked in the prepared buffer solution for 24 h to obtain a hydrophilic polytetrafluoroethylene / polydopamine membrane.

[0064] Next, the composite membrane material was prepared. Specifically, the prepared MXene slurry was uniformly coated onto a polydopamine-modified nanoporous polytetrafluoroethylene membrane using a 1000 μm thick doctor blade. Subsequently, the prepared PDMS membrane was laminated onto the surface of the MXene slurry, and after drying at room temperature, a three-layer asymmetric nanoporous polytetrafluoroethylene / MXene / conical PDMS composite membrane material was obtained.

[0065] Figure 3 An optical image of the 10×10 cone-shaped PDMS film prepared in Example 1 of the present invention. Figure 3 As shown, the 10×10 cone-shaped PDMS film array prepared by Example 1 is uniformly distributed, with a complete cone structure, a cone diameter of 4000 μm, a cone spacing of 1000 μm, and an air layer volume of 2081 mm². 3 The overall thickness of the PDMS film is 1000 μm. In addition, the thickness of the MXene layer is 5 μm.

[0066] Figure 4 Figure a is a graph showing the thermal insulation performance of the PDMS films prepared in Examples 1 and 4-5. (Refer to...) Figure 4 According to the figure, under environmental conditions of 25℃, the surface temperature of the 10×10 conical PDMS film covering a target of 36℃ is 33.6℃, ​​providing a heat insulation effect of 2.4℃. When 5 layers of this PDMS film are stacked, the surface temperature is 31℃, providing a heat insulation effect of 5℃.

[0067] Figure 5 To illustrate the characteristics of the composite membrane material prepared in Example 1 of the present invention, graph a is a temperature-time curve, and graphs b and c are infrared images of the composite membrane material. (Refer to...) Figure 5The surface radiation temperature of the composite film material covering the 36 °C simulated skin is 28 °C under the environmental condition of 25.5 °C, and the temperature difference with the environment is 2.5 °C, the infrared imaging of the simulated skin and the environment is basically the same, and the infrared detection is difficult to identify, achieving the effect of infrared invisibility; when the 5-layer composite film is superimposed, the surface radiation temperature and the environment temperature difference is 0.2 °C, and almost complete invisibility is achieved.

[0068] Example 2.

[0069] The MXene slurry was prepared, as in Example 1.

[0070] The patterned PDMS film was prepared, as in Example 1.

[0071] Further, the nanoporous polytetrafluoroethylene film was hydrophilically modified. Specifically, 2 parts of dopamine hydrochloride was dissolved in a Tris buffer with a pH of 8.5 to prepare a dopamine buffer solution. Further, the nanoporous polytetrafluoroethylene film with a thickness of 50 μm was soaked in the prepared buffer solution for 36 h to obtain a hydrophilic polytetrafluoroethylene / polydopamine film.

[0072] Then, the composite film material was prepared. Specifically, the prepared MXene slurry was uniformly scraped onto the polydopamine-modified nanoporous polytetrafluoroethylene film using a 1000 μm thick doctor blade. Subsequently, the prepared PDMS film was combined on the surface of the MXene slurry, and after drying at room temperature, a nanoporous polytetrafluoroethylene / MXene / pyramid PDMS composite film material with a three-layer asymmetric structure was obtained.

[0073] The nanoporous polytetrafluoroethylene / MXene / pyramid PDMS composite film material prepared by this example has a reflectivity of 70% in the solar wave band and an emissivity of 40% in the infrared wave band.

[0074] Example 3.

[0075] The MXene slurry was prepared, as in Example 1.

[0076] The patterned PDMS film was prepared, as in Example 1.

[0077] The nanoporous polytetrafluoroethylene film was hydrophilically modified, as in Example 1.

[0078] Then, the composite film material was prepared. Specifically, the prepared MXene slurry was uniformly scraped onto the polydopamine-modified nanoporous polytetrafluoroethylene film using a 500 μm thick doctor blade. Subsequently, the prepared PDMS film was combined on the surface of the MXene slurry, and after drying at room temperature, a nanoporous polytetrafluoroethylene / MXene / pyramid PDMS composite film material with a three-layer asymmetric structure was obtained.

[0079] The thickness of the MXene layer in the nanoporous polytetrafluoroethylene / MXene / cone PDMS composite film material prepared through this embodiment is 2 pm.

[0080] Figure 6 The graph shows the optical properties of the composite film material prepared in Embodiment 3 of the present application in different wave bands. As shown in graph a, the solar reflectivity of the nanoporous polytetrafluoroethylene side of the composite film material is higher than 60%, and the infrared emissivity is as low as 28%; as shown in graph b, the solar absorption of the PDMS side is higher than 50%, and the infrared emissivity is higher than 90%. Figure 6

[0081] Figure 7 The graph shows the properties of the composite film material prepared in Embodiment 3 of the present application, a is the interface temperature graph, and b is the surface radiation temperature graph. As shown in Figure 7 -2 Under simulated sunlight conditions, the interface temperature of the composite film material with a simulated skin of 36°C is 47°C, close to that of military polyester fabric, and the surface radiation temperature is 6°C lower than that of military polyester fabric, having good interface light-heat management and synchronous infrared stealth.

[0082] In addition, the EMI SE of the composite film material is greater than 40 dB.

[0083] Embodiment 4.

[0084] MXene slurry was prepared, as in Embodiment 1.

[0085] Secondly, a patterned PDMS film was prepared. Specifically, a patterned template was prepared by 3D printing technology, and the patterned array in the patterned template was designed as a 10x10 column array with an array height of 1000 pm. A mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent was scraped on the prepared patterned template, and then cured at a uniform temperature of 70°C for 2.5 h to obtain a patterned PDMS film.

[0086] Furthermore, the nanoporous polytetrafluoroethylene film was hydrophilically modified. Specifically, 2 parts of dopamine hydrochloride were dissolved in a Tris buffer with a pH of 8.5 to prepare a dopamine buffer solution. Then, the nanoporous polytetrafluoroethylene film with a thickness of 20 pm was soaked in the prepared buffer solution for 24 h to obtain a hydrophilic polytetrafluoroethylene / polydopamine film.

[0087] ​​Next, the composite membrane material was prepared. Specifically, the prepared MXene slurry was uniformly coated onto a polydopamine-modified nanoporous polytetrafluoroethylene membrane using a 1000 μm thick doctor blade. Subsequently, the prepared PDMS membrane was laminated onto the surface of the MXene slurry, and after drying at room temperature, a three-layer asymmetric nanoporous polytetrafluoroethylene / MXene / pillar PDMS composite membrane material was obtained.

[0088] Figure 8 Image a is an optical image of the PDMS film prepared in Example 4 of this invention. Figure 8 As shown in Figure a, the 10×10 columnar PDMS film array prepared by this embodiment is uniformly distributed, with complete column structure, column diameter of 4000 μm, column spacing of 1000 μm, and air layer volume of 1244 mm². 3 The overall thickness of the columnar PDMS film is 1000 μm.

[0089] Figure 4 Figure a is a graph showing the thermal insulation performance of the PDMS films prepared in Examples 1 and 4-5 of the present invention. (Refer to...) Figure 4 In an environment of 25°C, the surface temperature of the 10×10 cylindrical PDMS film covering a target at 36°C is 34.4°C, providing a heat insulation effect of 1.6°C. When five layers of this PDMS film are stacked, the surface temperature is 32.5°C, providing a heat insulation effect of 3.5°C.

[0090] Example 5.

[0091] Prepare MXene slurry as in Example 1.

[0092] Next, a patterned PDMS film was prepared. A patterned template was prepared using 3D printing technology, and the patterned array in the template was designed as a plane. A mixture of 10 parts Sylgard 184 silicone elastomer matrix and 1 part crosslinking agent was coated onto the prepared patterned template, and then cured at a uniform temperature of 60°C for 2 hours to obtain the patterned PDMS film.

[0093] The hydrophilic modification of the nanoporous polytetrafluoroethylene membrane is the same as in Example 1.

[0094] Next, the composite membrane material was prepared. Specifically, the prepared MXene slurry was uniformly coated onto a polydopamine-modified nanoporous polytetrafluoroethylene membrane using a 1000 μm thick doctor blade. Subsequently, the prepared PDMS membrane was laminated onto the surface of the MXene slurry, and after drying at room temperature, a three-layer asymmetric nanoporous polytetrafluoroethylene / MXene / planar PDMS composite membrane material was obtained.

[0095] Figure 8b is an optical picture of the PDMS film prepared in Example 5 of the present application. As shown in Figure 8 The surface of the planar PDMS film prepared by this example is smooth and uniform, and the air layer occupies a volume of 0 mm 3 The overall thickness of the planar PDMS film is 1000 pm.

[0096] Figure 4 a is a chart showing the heat insulation performance of the PDMS film prepared in Examples 1, 4-5 of the present application. Referring to Figure 4 The surface temperature of the planar PDMS film covering the 36°C target is 35.6°C under the environmental conditions of 25°C, having a heat insulation effect of 0.4°C. When the 5-layer PDMS film is used in a stacked manner, the surface temperature is 35°C, having a heat insulation effect of 1°C.

[0097] Example 6.

[0098] The MXene slurry was prepared, as in Example 1.

[0099] Secondly, the patterned PDMS film was prepared. Specifically, a patterned template was prepared by 3D printing technology, and the patterned array in the patterned template was designed as a 5x5 cone array with an array height of 1000 pm. A mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent was scraped on the prepared patterned template, and then cured at a uniform temperature of 70°C for 2h to obtain the patterned PDMS film.

[0100] The hydrophilic modification of the nanoporous polytetrafluoroethylene film was as in Example 1.

[0101] Then, the composite film material was prepared. Specifically, the prepared MXene slurry was uniformly scraped onto the polydopamine-modified nanoporous polytetrafluoroethylene film using a 1000 pm thick scraper. Subsequently, the prepared PDMS film was combined on the surface of the MXene slurry, and after drying at room temperature, a nanoporous polytetrafluoroethylene / MXene / cone PDMS composite film material with a three-layer asymmetric structure was obtained.

[0102] Figure 9 a is an optical picture of the PDMS film prepared in Example 6 of the present application. As shown in Figure 9 As shown in a of the present application, the 5x5 cone PDMS film array prepared by this example is uniformly distributed, the cone structure is complete, the cone diameter is 8000 pm, and the air layer occupies a volume of 2081 mm 3 The overall thickness of the cone PDMS film is 1000 pm.

[0103] Figure 4 b is a chart showing the heat insulation performance of the PDMS film prepared in Examples 6-8 of the present application. Referring toFigure 4 b) Under 25°C conditions, the surface temperature of the 5×5 cone-shaped PDMS membrane covering a 36°C target is 33.3°C, providing a heat insulation effect of 2.7°C.

[0104] Example 7.

[0105] Prepare MXene slurry as in Example 1.

[0106] Next, a patterned PDMS film was prepared. Specifically, a patterned template was prepared using 3D printing technology. The patterned array in the template was designed as a 20×20 cone array with an array height of 1000 μm. A mixture of 10 parts Sylgard 184 silicone elastomer matrix and 1 part crosslinking agent was coated onto the prepared patterned template, and then cured at a uniform temperature of 80°C for 2 hours to obtain the patterned PDMS film.

[0107] The hydrophilic modification of the nanoporous polytetrafluoroethylene membrane is the same as in Example 1.

[0108] Next, the composite membrane material was prepared. Specifically, the prepared MXene slurry was uniformly coated onto a polydopamine-modified nanoporous polytetrafluoroethylene membrane using a 1000 μm thick doctor blade. Subsequently, the prepared PDMS membrane was laminated onto the surface of the MXene slurry, and after drying at room temperature, a three-layer asymmetric nanoporous polytetrafluoroethylene / MXene / conical PDMS composite membrane material was obtained.

[0109] Figure 9 Image b is an optical image of the PDMS film prepared in Example 7 of the present invention. Figure 9 As shown in b, the 20×20 cone-shaped PDMS film array prepared by this embodiment is uniformly distributed, but the cone structure is obviously broken. The cone diameter is 2000 μm, and the air layer occupies a volume of 2081 mm². 3 The overall thickness of the cone-shaped PDMS film is 1000 μm.

[0110] Figure 4 Figure b is a graph illustrating the thermal insulation performance of the PDMS films prepared in Examples 6-8 of the present invention. (Refer to...) Figure 4 b) Under 25°C conditions, the surface temperature of the 20×20 cone-shaped PDMS membrane covering a target at 36°C is 34.2°C, providing a heat insulation effect of 1.8°C.

[0111] Example 8.

[0112] Prepare MXene slurry as in Example 1.

[0113] Secondly, the patterned PDMS film was prepared. Specifically, a patterned template was prepared by 3D printing technology, and the patterned array in the patterned template was designed as a 40x40 cone array with an array height of 1000 pm. A mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent was scraped on the prepared patterned template, and then cured at a uniform temperature of 80°C for 2.5 h to obtain the patterned PDMS film.

[0114] The hydrophilic modification of the nanoporous polytetrafluoroethylene film was the same as in Example 1.

[0115] Then, the composite film material was prepared. Specifically, the prepared MXene slurry was uniformly scraped onto the polydopamine-modified nanoporous polytetrafluoroethylene film using a 1000 pm thick scraper. Subsequently, the prepared PDMS film was combined on the surface of the MXene slurry, and after drying at room temperature, a nanoporous polytetrafluoroethylene / MXene / cone PDMS composite film material with a three-layer asymmetric structure was obtained.

[0116] Figure 9 Fig. c is an optical picture of the PDMS film prepared in Example 8 of the present application. As shown in Fig. c, the 40x40 cone PDMS film array prepared by this example is uniformly distributed, but the cone structure is severely damaged, and part of the cone is not formed. The diameter of the formed cone is 1000 pm. Figure 9 As shown in Fig. c, the 40x40 cone PDMS film array prepared by this example is uniformly distributed, but the cone structure is severely damaged, and part of the cone is not formed. The diameter of the formed cone is 1000 pm.

[0117] Figure 4 Fig. b is a chart showing the thermal insulation performance of the PDMS films prepared in Examples 6-8 of the present application. Referring to Fig. b, the surface temperature of the 40x40 cone PDMS film covering the 36°C target was 34.4°C under the environmental conditions of 25°C, with a thermal insulation effect of 1.6°C. Figure 4 As shown in Fig. b, the surface temperature of the 40x40 cone PDMS film covering the 36°C target was 34.4°C under the environmental conditions of 25°C, with a thermal insulation effect of 1.6°C.

[0118] Example 9.

[0119] The MXene slurry was prepared, and the same as in Example 1.

[0120] The patterned PDMS film was prepared, and the same as in Example 1.

[0121] Furthermore, the nanoporous polyethylene film was hydrophilically modified. Specifically, 2 parts of dopamine hydrochloride were dissolved in a Tris buffer with a pH of 8.5 to prepare a dopamine buffer solution. Furthermore, the prepared buffer solution was used to soak a nanoporous polyethylene film with a thickness of 20 pm for 24 h to obtain a hydrophilic polyethylene / polydopamine film.

[0122] Then, the composite film material was prepared. Specifically, the prepared MXene slurry was uniformly coated on the polyethylene film using a 1000 pm thick doctor blade. Subsequently, the prepared PDMS film was combined on the surface of the MXene slurry, and after drying at room temperature, a three-layer asymmetric structure of the nanoporous polyethylene / MXene / pyramid PDMS composite film material was obtained.

[0123] The solar reflectance of the polyethylene side of the composite film material of the present embodiment was higher than 70%, the infrared emissivity was as low as 22%, the solar absorption rate of the PDMS side was higher than 50%, and the infrared emissivity was higher than 90%.

[0124] Example 10.

[0125] The MXene slurry was prepared, as in Example 1.

[0126] The patterned PDMS film was prepared, as in Example 1.

[0127] Then, the composite film material was prepared. Specifically, the prepared MXene slurry was uniformly coated on the polyethylene film using a 1000 pm thick doctor blade. Subsequently, the prepared PDMS film was combined on the surface of the MXene slurry, and after drying at room temperature, a three-layer asymmetric structure of the nanoporous polyethylene / MXene / pyramid PDMS composite film material was obtained.

[0128] The solar reflectance of the polyethylene side of the composite film material of the present embodiment was higher than 70%, the infrared emissivity was as low as 22%, the solar absorption rate of the PDMS side was higher than 50%, and the infrared emissivity was higher than 90%.

[0129] The contact angle of the nylon side of the composite film material of the present embodiment was 0°, and it did not have a hydrophobic protection function.

[0130] It should be understood that the "one embodiment" or "an embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that the size of the serial number of each process in various embodiments of the present application does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The serial number of the above-mentioned embodiments of the present application is only for description, not representing the advantages and disadvantages of the embodiments.

[0131] It should be noted that, as used in this document, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a", "comprising", or "comprises" does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0132] The above description is only the preferred embodiment of the application, but the protection scope of the application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A composite film material with dynamic infrared stealth, electromagnetic shielding and thermal management functions, characterized in that, the composite film material is a three-layer asymmetric structure, the first outer layer is a nanoporous film that reflects sunlight and transmits infrared radiation, the middle layer is a uniform and dense MXene layer that absorbs sunlight, reflects infrared radiation and resists electromagnetic interference shielding, and the second outer layer is a patterned array designed high-transmission sunlight and high-emissivity infrared thermal insulation PDMS layer, the pattern design of the second outer layer patterned PDMS layer is a plane, or any one of 5x5, 10x10, 20x20 and 40x40 cone arrays, or any one of 5x5, 10x10, 20x20 and 40x40 column arrays.

2. The composite film material according to claim 1, characterized in that, the thickness of the first outer layer nanoporous film is 20-50 μm, the thickness of the middle layer MXene layer is 2-10 μm, and the thickness of the second outer layer patterned PDMS layer is 500-2000 μm.

3. A method for preparing a composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions, characterized in that, including: preparing a MXene slurry; preparing a patterned PDMS layer; hydrophilic modification of a nanoporous film; and sequentially compounding the prepared MXene slurry and patterned PDMS layer on the modified nanoporous film to prepare the composite film material with a three-layer asymmetric structure of a nanoporous film layer, a MXene layer and a patterned PDMS layer, the step of preparing a patterned PDMS layer further comprises: preparing a patterned template by 3D printing technology, the patterned array design in the patterned template is a plane, or any one of 5x5, 10x10, 20x20 and 40x40 cone arrays, or any one of 5x5, 10x10, 20x20 and 40x40 column arrays, and the array height is 500-2000 μm; spreading a mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent on the prepared patterned template; and curing the mixture at a uniform temperature of 60-80°C for 1-4 h to obtain the patterned PDMS film.

4. The production method according to claim 3, characterized by, the step of preparing a MXene slurry further comprises: adding 1 part of Ti3AlC2 powder to concentrated HCl with 1.6 parts of LiF, and etching at a temperature of 35°C for 3 h to prepare a Ti3C2Tx suspension; after the Ti3C2Tx suspension is filtered and washed with water, centrifuging 5 times at 8000 rpm until the pH value approaches 7; and ultrasonic treatment under nitrogen and ice bath conditions for 0.5 h, and centrifugation at 3500 rpm for 1 h to obtain a single-layer MXene suspension.

5. The preparation method according to claim 3, characterized in that, the step of preparing a patterned PDMS layer further comprises: preparing a patterned template by 3D printing technology, the patterned array design in the patterned template is a 10x10 cone array, and the array height is 1000 μm; spreading a mixture of 10 parts of Sylgard 184 silicone elastomer base and 1 part of crosslinking agent on the prepared patterned template; and The mixture is cured at a uniform temperature of 70℃ for 2h to obtain the patterned PDMS film.

6. The preparation method according to claim 3, characterized in that, The step of hydrophilic modification of the nanoporous membrane further comprises: dissolving 1-3 parts of dopamine hydrochloride in a Tris buffer solution with a pH of 7-9 to prepare a dopamine buffer solution; and immersing the nanoporous membrane in the prepared buffer solution for 12-36 hours to obtain a hydrophilic nanoporous membrane.

7. The preparation method according to claim 3, characterized in that, The further comprising of the preparation of the composite membrane material comprises: uniformly doctoring the prepared MXene slurry onto the modified nanoporous membrane using a doctor blade with a thickness of 200-1000μm; compositing the prepared patterned PDMS film on the surface of the MXene slurry; and drying at room temperature to obtain a three-layer asymmetric structure of nanoporous membrane / MXene / patterned PDMS composite membrane material.

8. Use of a composite film material having dynamic infrared stealth, electromagnetic shielding and thermal management functions, characterized in that, The composite membrane material is the composite membrane material with dynamic infrared stealth, electromagnetic shielding and thermal management functions of any one of claims 1-2 or prepared by the preparation method of the composite membrane material with dynamic infrared stealth, electromagnetic shielding and thermal management functions of any one of claims 3-7, and is used for infrared stealth, electromagnetic shielding and / or thermal management.

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