Multi-stimulus response color-changing film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of functional devices, and discloses a multi-stimulus response color-changing film as well as a preparation method and application thereof. The multi-stimulus response color-changing film comprises a first film, a second film and a third film which are sequentially stacked; wherein the first thin film comprises a polydimethylsiloxane material layer, a silicon dioxide material layer and a polydimethylsiloxane material layer which are sequentially stacked; the second thin film is a nano material layer with a photo-thermal response near-infrared light adjusting function; the third thin film comprises a polydimethylsiloxane material layer and a humidity response layer which are stacked, the elasticity modulus of the humidity response layer and the polydimethylsiloxane material layer differ by three orders of magnitude, and the recovery speed of the humidity response layer and the polydimethylsiloxane material layer differ by three to four orders of magnitude. The thin film can realize the capability of independently adjusting visible light, near-infrared light and haze through the stimulation of response force, light, heat, humidity and the like, so that multiple modes are realized, and the application in different environments can be met.

Description

Technical Field

[0001] This invention relates to the field of functional device technology, and in particular to a multi-stimulus responsive color-changing thin film, its preparation method, and its application. Background Technology

[0002] Buildings account for nearly 40% of global energy consumption, with windows contributing over 50% of that heat loss. Smart windows, capable of dynamically regulating solar radiation, offer a revolutionary approach to improving building energy efficiency and enhancing living comfort. Building windows need to achieve triple independent control of the solar spectrum: regulating daylighting with visible light (380-780 nm), controlling heat radiation with near-infrared light (780-2500 nm), and regulating fog to ensure privacy. An ideal smart window should be able to independently adjust these parameters to adapt to different environmental and seasonal needs. However, achieving decoupled control of visible light, near-infrared light, and fog remains a significant challenge.

[0003] Current smart window technologies primarily rely on dynamic optical modulation to light, heat, electricity, or mechanical stimuli, but these have inherent limitations. WO3-based electrochromic systems can modulate visible and near-infrared light, but cannot adjust haze and require an external power source (Advanced Optical Materials, 2025, 13, 2402526); VO2 or NIPAM (N-isopropylacrylamide)-based thermochromic systems mainly modulate near-infrared (>780 nm) or visible (<1300 nm) light independently (Light: Science & Applications, 2024, 13, 2255); polymer-dispersed liquid crystals can adjust haze, but their control over near-infrared light is poor (ACS Nano, 2023, 17, 19767). Furthermore, most existing systems respond to only a single stimulus, which greatly limits their adaptability.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a multi-stimulus responsive color-changing film, its preparation method and application, in order to solve the problem that existing smart window systems only respond to a single stimulus.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a multi-stimulus responsive color-changing film, the multi-stimulus responsive color-changing film comprising a first film, a second film and a third film stacked sequentially; The first film comprises a polydimethylsiloxane material layer, a silica material layer and a polydimethylsiloxane material layer stacked sequentially. The second thin film is a nanomaterial layer with the function of regulating near-infrared light through photothermal response; The third thin film includes a polydimethylsiloxane material layer and a humidity response layer arranged in a stacked manner. The polydimethylsiloxane material layer in the third thin film is adhered to the second thin film. The elastic modulus of the humidity response layer material is 1 - 4 GPa, and the elastic modulus of the polydimethylsiloxane is 1 - 2 MPa, with a difference of three orders of magnitude between them. The recovery speed of the humidity response layer material is extremely slow, at the second - hour level, while the recovery speed of the polydimethylsiloxane is extremely fast, at the millisecond level (from millisecond to dozens of milliseconds), with a difference of three to four orders of magnitude between them.

[0007] Preferably, the nanomaterial with the function of regulating near-infrared light through photothermal response is selected from one of tungsten oxide, metal-doped tungsten oxide, vanadium oxide, metal-doped vanadium oxide, GeSbTe alloy, gold nanorods, Cu 2-x S (0 < x < 1), CuSe, CuTe, PbS.

[0008] Preferably, the material of the humidity response layer is selected from one of polyvinyl alcohol, gelatin, chitosan, cellulose and its derivatives, polyurethane, polyacrylamide, poly(N-isopropylacrylamide), and polyacrylic acid.

[0009] Preferably, the silica material is silica nanospheres, and the particle size of the silica nanospheres is 200 - 1000 nm. For example: the particle size of the silica nanospheres can be 100 - 200 nm, 200 - 300 nm, 300 - 400 nm, 400 - 500 nm, 500 - 600 nm, 600 - 700 nm, 700 - 800 nm, 800 - 900 nm, 900 - 1000 nm.

[0010] In the second aspect of the present invention, a method for preparing the above multi-stimulus responsive color-changing thin film is provided, and the preparation method includes the following steps: Mix polydimethylsiloxane with a curing agent to obtain a polydimethylsiloxane solution, and dissolve the humidity response layer material in a solvent to obtain a humidity response layer solution; Coat the polydimethylsiloxane solution on a substrate, and cure it by heating to obtain a polydimethylsiloxane material layer, and assemble silica on the surface of the polydimethylsiloxane material layer to obtain a silica material layer. Then coat the polydimethylsiloxane solution on the surface of the silica material layer and cure it by heating to obtain a first thin film; Assemble the nanomaterial with the function of regulating near-infrared light through photothermal response on the surface of the first thin film to obtain a second thin film; The polydimethylsiloxane solution is coated onto the surface of the second film and cured by heating to obtain a polydimethylsiloxane material layer. The humidity-responsive layer solution is coated onto the surface of the polydimethylsiloxane material layer and cured by heating to obtain the multi-stimulus responsive color-changing film.

[0011] Preferably, the assembly method is selected from one of spraying, spin coating, scraping, drip coating, lift coating, and Langmuir-Bugit coating.

[0012] Preferably, the silica material is silica nanospheres, and the preparation method of the silica nanospheres includes: Ammonia, ethanol, and water are mixed to obtain a mixture; Tetraethyl orthosilicate and ethanol were mixed and then added to the mixture. The mixture was stirred at 40-80°C for 0.5-48 hours to obtain the silica nanospheres.

[0013] Preferably, the nanomaterial with photothermal response modulation of near-infrared light function is tungsten oxide nanoparticles, and the preparation method of the tungsten oxide nanoparticles includes: Tungsten hexachloride was dispersed in an organic solvent to obtain a tungsten hexachloride solution; The tungsten hexachloride solution was transferred to a reaction vessel and reacted at 140-240°C for 0.5-48 h to obtain the tungsten oxide nanoparticles.

[0014] Preferably, the nanomaterial with photothermal response modulation of near-infrared light function is tungsten-doped vanadium oxide, and the preparation method of the tungsten-doped vanadium oxide includes: Vanadium oxysulfate was dissolved in water, and ammonium metatungstate and hydrazine hydrate were added sequentially to obtain a mixed solution; Adjust the pH of the mixed solution to 6-8; The mixed solution with a pH of 6-8 is transferred to a reaction vessel and reacted at 200-260°C for 24-48 hours to obtain the tungsten-doped vanadium oxide.

[0015] A third aspect of the present invention provides the application of the above-described multi-stimulus responsive color-changing film in the field of smart doors and windows.

[0016] The present invention has the following beneficial effects: This invention proposes a multi-stimulus responsive color-changing film, its preparation method, and its applications. Compared with existing technologies, the multi-stimulus responsive color-changing film provided by this invention exhibits good visible and near-infrared light transmittance and low haze under normal conditions. Under photothermal stimulation, it reduces near-infrared light transmittance; under mechanical stretching stimulation, it reduces visible light transmittance; through a stretching-recovery process, it effectively increases haze; and finally, through a humidification process, the haze returns to its initial state. This film can independently adjust visible light, near-infrared light, and haze by responding to stimuli such as force, light, heat, and humidity, thus achieving multiple modes and meeting the needs of applications in different environments. Attached Figure Description

[0017] Figure 1 These are scanning electron microscope images of the silica microspheres prepared in Examples 1 and 2 of this invention; Figure 2 Transmission electron microscope (TEM) images of vanadium oxide and tungsten-doped vanadium oxide prepared in Example 1 of this invention; Figure 3 These are cross-sectional scanning electron microscope images of the multi-stimulus responsive color-changing films prepared in Examples 1 and 2 of this invention; Figure 4 This is a scanning electron microscope image of the tungsten oxide nanomaterials prepared in Example 2 of the present invention; Figure 5 The changes in transmittance and reflectance of the multi-stimulus responsive color-changing films prepared in Examples 1 and 2 of the present invention under different stretching conditions; Figure 6 The changes in transmittance of the multi-stimulus responsive color-changing films prepared in Examples 1 and 2 of this invention under photothermal stimulation; Figure 7 The images show the haze modulation changes and physical models of the multi-stimulus responsive color-changing films prepared in Examples 1 and 2 of this invention. Figure 8 These are surface morphology images and schematic diagrams of the multi-stimulus responsive color-changing films prepared in Examples 1 and 2 of this invention before and after haze changes. Figure 9 The cycling stability of the multi-stimuli-responsive color-changing films prepared in Examples 1 and 2 of this invention under different stimuli; Figure 10 This is a photograph of the effect achieved by the multi-stimuli-responsive color-changing film prepared in Example 2 of the present invention under different stimuli. Figure 11 The changes in spectral transmittance of the multi-stimuli-responsive color-changing films prepared in Examples 1 and 2 of this invention under different stimuli; In the figure, the multi-stimulus responsive color-changing film prepared in Example 1 is represented by PV-Si-PVA, and the multi-stimulus responsive color-changing film prepared in Example 2 is represented by PW-Si-PVA. Detailed Implementation

[0018] This invention provides a multi-stimulus responsive color-changing film, its preparation method, and its applications. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0020] This invention provides a multi-stimulus responsive color-changing film, which includes a first film, a second film, and a third film stacked sequentially. The first film comprises a polydimethylsiloxane material layer, a silica material layer and a polydimethylsiloxane material layer stacked sequentially. The second thin film is a nanomaterial layer with photothermal response modulation of near-infrared light; The third film comprises a polydimethylsiloxane material layer and a humidity-responsive layer stacked together. The polydimethylsiloxane material layer in the third film is bonded to the second film. The elastic modulus of the humidity-responsive layer material is 1-4 GPa, while the elastic modulus of the polydimethylsiloxane is 1-2 MPa, a difference of three orders of magnitude. The recovery speed of the humidity-responsive layer material is extremely slow, on the order of seconds to hours, while the recovery speed of the polydimethylsiloxane is extremely fast, on the order of milliseconds (milliseconds to tens of milliseconds), a difference of three to four orders of magnitude. That is, the multi-stimulus responsive color-changing film of this embodiment of the invention sequentially comprises a polydimethylsiloxane material layer, a silica material layer, a polydimethylsiloxane material layer, a nanomaterial layer with photothermal response modulation of near-infrared light, a polydimethylsiloxane material layer, and a humidity-responsive layer.

[0021] The multi-stimulus responsive color-changing film provided in this embodiment can independently adjust visible light, near-infrared light, and haze by responding to stimuli such as force, light, heat, and humidity. Specifically, the first film has good transmittance of visible light and can quickly modulate visible light through stretching. The second film can regulate the transmittance of near-infrared light in response to changes in the external environment. The third film can regulate haze. More specifically, the visible light modulation mechanism of the first film is as follows: In the initial state, PDMS-Si exhibits high transmittance due to the matching refractive indices of PDMS and SiO2. When the multi-stimulus responsive color-changing film is stretched, pores are formed inside. The refractive index of air is much lower than that of PDMS and SiO2, resulting in a significant decrease in the visible light transmittance of the multi-stimulus responsive color-changing film. The second thin film's near-infrared modulation mechanism: Nanomaterials with photothermal response modulation of near-infrared light (taking vanadium oxide as an example) exhibit excellent photochromic effects due to their unique electronic structure and tunable band gap, and can effectively modulate spectral transmittance. The lattice structure of vanadium oxide undergoes a reversible phase transition from a semiconductor state (monoclinic system) to a metallic state (rutile system) near the critical temperature (approximately 68°C), leading to a drastic change in its infrared light transmittance and reflection characteristics. The third thin film's haze modulation mechanism: Due to the large difference in elastic modulus and recovery speed between PDMS and the humidity-responsive layer material, they exhibit a high haze state after stretching and recovery, and can quickly return to their initial state after humidification.

[0022] Furthermore, the first, second, and third films are ultimately combined into a single film due to the action of PDMS. Visible, near-infrared, and haze modulation can be achieved independently by applying individual stimuli, and there are also synergistic effects. For example, applying stretching and light / heat simultaneously can achieve a low visible light and near-infrared transmission mode; or stretching can restore the high haze state, responding to light or heat to modulate near-infrared light.

[0023] This invention provides a method for preparing the above-mentioned multi-stimulus responsive color-changing film, the method comprising the following steps: Polydimethylsiloxane is mixed with a curing agent to obtain a polydimethylsiloxane solution, and the humidity-responsive layer material is dissolved in the solvent to obtain a humidity-responsive layer solution. The polydimethylsiloxane solution is coated onto a substrate and cured by heating to obtain a polydimethylsiloxane material layer. Silica is then assembled onto the surface of the polydimethylsiloxane material layer to obtain a silica material layer. The polydimethylsiloxane solution is then coated onto the surface of the silica material layer and cured by heating to obtain a first film. A second film is obtained by assembling nanomaterials with photothermal response modulation of near-infrared light onto the surface of the first film. The polydimethylsiloxane solution is coated onto the surface of the second film and cured by heating to obtain a polydimethylsiloxane material layer. The humidity-responsive layer solution is coated onto the surface of the polydimethylsiloxane material layer and cured by heating to obtain the multi-stimulus responsive color-changing film.

[0024] In some embodiments, the nanomaterial with photothermal response modulation of near-infrared light function is tungsten oxide nanoparticles, and the preparation method of the tungsten oxide nanoparticles includes: Tungsten hexachloride was dispersed in an organic solvent to obtain a tungsten hexachloride solution; The tungsten hexachloride solution was transferred to a reaction vessel and reacted at 140-240°C for 0.5-48 hours to obtain the tungsten oxide nanoparticles.

[0025] In some specific embodiments, the method for preparing the tungsten oxide nanoparticles includes: Tungsten hexachloride was completely dissolved in an alcohol system to obtain a tungsten hexachloride solution with a concentration of 0.1-6.0 mg / mL. The obtained tungsten hexachloride solution was transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 140-240℃ for 0.5-48 h.

[0026] After the reaction was completed, the product was collected by high-speed centrifugation, ethanol was added to redisperse and centrifuged again to purify the product, and finally the supernatant was removed to disperse the nanoparticles in the solvent.

[0027] The solvent is selected from at least one of dimethyl sulfoxide, water, ethanol, isopropanol, n-hexane, and toluene.

[0028] Preferably, the concentration of tungsten hexachloride is 3.75 mg / mL, the hydrothermal reaction temperature is 180℃, the reaction time is 1-24 h, and after the reaction is completed, the mixture is washed multiple times by centrifugation with ethanol and finally dispersed in anhydrous ethanol.

[0029] In some embodiments, the nanomaterial with photothermal response modulation of near-infrared light function is tungsten-doped vanadium oxide, and the preparation method of the tungsten-doped vanadium oxide includes: Vanadium oxysulfate was dissolved in water, and ammonium metatungstate and hydrazine hydrate were added sequentially to obtain a mixed solution; Adjust the pH of the mixed solution to 6-8; The mixed solution with a pH of 6-8 is transferred to a reaction vessel and reacted at 200-260°C for 24-48 hours to obtain the tungsten-doped vanadium oxide.

[0030] In some specific embodiments, the method for preparing the tungsten-doped vanadium oxide includes: Vanadium oxysulfate was dissolved in deionized water, and a certain amount of ammonium metatungstate was added. The mixture was stirred until completely dissolved, and then hydrazine hydrate was added until the solution turned gray. The mixture was stirred for 5-15 minutes. Then, sodium hydroxide solution was added dropwise to adjust the pH value to about 7. The precipitate was filtered, centrifuged and washed, and then dispersed in deionized water. The precipitate was transferred to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 200-260℃ for 24-48 hours. After the reaction was completed, the precipitate was repeatedly centrifuged and washed, and then dispersed in ethanol for later use.

[0031] Preferably, the amount of ammonium metatungstate added relative to vanadium oxysulfate is 2-3 mol%, the amount of hydrazine hydrate added is 0.28-0.32 mL, the reaction temperature is 240℃, and the reaction time is 32-40 h.

[0032] In some implementations, the modulation effect of visible and near-infrared light is affected by adjusting the size or content of silica and the content of nanomaterials with photothermal response modulation of near-infrared light, so as to meet the application needs of different regions and climates, showing broad application prospects in the field of new intelligent energy-saving windows.

[0033] The following detailed description uses specific examples.

[0034] Example 1 The preparation of a multi-stimulus responsive color-changing film includes the following steps: (1) Mix 30 mL of ethanol, 24 mL of deionized water, and 10 mL of ammonia water evenly and preheat to 65°C. Stir continuously at 500 rpm. Then, mix 24 mL of tetraethyl orthosilicate and 40 mL of ethanol evenly and add it to the mixture. Continue stirring at 65°C for 1 h. After the reaction is complete, centrifuge the dispersion at 6000 rpm for 5 min, remove the supernatant, and centrifuge and wash repeatedly to remove unreacted impurities. Disperse the dispersion in 80 mL of anhydrous ethanol for later use to prepare silica microspheres, such as... Figure 1 As shown.

[0035] (2) Dissolve 1 g of vanadium oxysulfate in 40 mL of deionized water, and add 0 g or 0.3 g of ammonium metatungstate. Stir until completely dissolved, then add about 0.3 mL of hydrazine hydrate to the mixture until the solution turns gray. Continue stirring for 10 min, then add 0.5 mol / L sodium hydroxide solution dropwise to the mixture to adjust the pH to 7. After filtration, centrifugation and washing, the resulting precipitate is dispersed in 40 mL of deionized water and transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene. React at 240℃ for 36 h. After the reaction, repeatedly centrifuge and wash with ethanol, then disperse in 40 mL of ethanol for later use. The prepared vanadium oxide (with 0 g of ammonium metatungstate) or tungsten-doped vanadium oxide (with 0.3 g of ammonium metatungstate) is as follows: Figure 2 As shown.

[0036] (3) Mix polydimethylsiloxane and curing agent at a mass ratio of 10:1 to obtain polydimethylsiloxane solution, and remove bubbles by vacuum treatment.

[0037] (4) Drop the polydimethylsiloxane solution onto a 4*4 cm plate. 2 On a polycarbonate substrate, spin coating was performed at 500 rpm and cured at 80°C for 1 h. Subsequently, 3 mL of silica dispersion was sprayed onto the polydimethylsiloxane material layer. During the spraying process, the air compressor pressure was increased to 30 kPa, the spraying distance was 8 cm, and the spray gun movement speed was 5 cm / s. Then, polydimethylsiloxane solution was added dropwise to the silica material layer, and spin coating was performed at 500 rpm, cured at 80°C for 1 h, to obtain the first film.

[0038] (5) Spray 1.5 mL of vanadium oxide dispersion onto the surface of the first film. During the spraying process, the air compressor pressure is increased to 30 kPa. The spraying distance is 8 cm and the spray gun moving speed is 5 cm / s to obtain the second film.

[0039] (6) A polydimethylsiloxane solution was dropped onto the surface of the second film, and spin-coated at 500 rpm. The film was cured at 80°C for 1 h, and then subjected to oxygen plasma treatment for 5 min. 0.2 mL of polyvinyl alcohol solution (mass fraction of 3%) was dropped onto the surface, and finally the film was slowly dried on a heating table at 40°C to obtain the third film. The final product is a multi-stimulus responsive color-changing film, the cross-section of which is shown in Figure 1. Figure 3 As shown.

[0040] Example 2 The preparation of a multi-stimulus responsive color-changing film includes the following steps: (1) Mix 30 mL of ethanol, 24 mL of deionized water, and 10 mL of ammonia water evenly and preheat to 65°C. Stir continuously at 500 rpm. Then, mix 24 mL of tetraethyl orthosilicate and 40 mL of ethanol evenly and add it to the mixture. Continue stirring at 65°C for 1 h. After the reaction is complete, centrifuge the dispersion at 6000 rpm for 5 min, remove the supernatant, and centrifuge and wash repeatedly to remove unreacted impurities. Disperse the dispersion in 80 mL of anhydrous ethanol for later use to prepare silica microspheres, such as... Figure 1 As shown.

[0041] (2) 0.3 g of tungsten hexachloride was completely dissolved in a mixed solution of 20 mL ethanol and 60 mL isopropanol. After complete dissolution, a uniform yellow solution was obtained. The solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene and reacted at 180 °C for 1 h. After the reaction, the product was collected by high-speed centrifugation at 8000 rpm for 5 min. Ethanol was added for redispersible centrifugation to purify the product. Finally, the supernatant was removed, and the tungsten oxide nanoparticles were dispersed in 40 mL of anhydrous ethanol for later use. The prepared tungsten oxide nanoparticles are shown below. Figure 4 As shown.

[0042] (3) Mix polydimethylsiloxane and curing agent at a mass ratio of 10:1 to obtain polydimethylsiloxane solution, and remove bubbles by vacuum treatment.

[0043] (4) Drop the polydimethylsiloxane solution onto a 4*4 cm plate. 2 On a polycarbonate substrate, spin coating was performed at 500 rpm and cured at 80°C for 1 h. Subsequently, 3 mL of silica dispersion was sprayed onto the polydimethylsiloxane material layer. During the spraying process, the air compressor pressure was increased to 30 kPa, the spraying distance was 8 cm, and the spray gun movement speed was 5 cm / s. Then, polydimethylsiloxane solution was added dropwise to the silica material layer, and spin coating was performed at 500 rpm, cured at 80°C for 1 h, to obtain the first film.

[0044] (4) Spray 4 mL of tungsten oxide dispersion onto the surface of the first film. During the spraying process, the air compressor pressure is increased to 30 kPa. The spraying distance is 8 cm and the spray gun moving speed is 5 cm / s to obtain the second film.

[0045] (5) A polydimethylsiloxane solution was dropped onto the surface of the second film, and spin-coated at 500 rpm. The film was cured at 80°C for 1 h, and then subjected to oxygen plasma treatment for 5 min. 0.2 mL of polyvinyl alcohol solution (mass fraction of 3%) was dropped onto the surface, and finally the film was slowly dried on a heating table at 40°C to obtain the third film. The final product is a multi-stimulus responsive color-changing film, the cross-section of which is shown in Figure 1. Figure 3 As shown.

[0046] The multi-stimulus responsive color-changing films prepared in Examples 1 and 2 were tested respectively. Both films achieved visible light modulation by being stretched to different ratios. Figure 5 As shown, a 50% strain on the film prepared in Example 1 resulted in a 50.7% decrease in visible light transmittance (from 62.8% to 12.1%, λ=550 nm) and an increase in reflectance of 36.7% (from 7.4% to 44.1%). Under the same strain conditions, a 50% strain on the film prepared in Example 2 resulted in a 54.8% decrease in visible light transmittance (from 87.0% to 32.2%) and an increase in reflectance of 36.9% (from 8.8% to 45.7%). Figure 6 As shown, the two films modulated near-infrared light in response to ambient temperature or light intensity. In Example 1, as the temperature increased from 20°C to 50°C, the near-infrared light transmittance (λ=1500nm) decreased from 80.9% to 45.1%, a modulation of 35.8%. Simultaneously, the visible light transmittance (λ=550nm) remained at 63.1%. In Example 2, the near-infrared transmittance decreased from 92.4% to 11.8% after ultraviolet light irradiation, a modulation of 80.6% (λ = 1500 nm), while maintaining a relatively small impact on visible light (<32% at λ=550 nm). Figure 7 As shown, the multi-stimulus responsive color-changing film achieves a high haze state through stretching-recovery. The haze of the film prepared in Example 1 increased from 17.6% to 85.7% and the film prepared in Example 2 increased from 16.3% to 83.1%, respectively. It can quickly recover to a low haze state by humidification. The corresponding structural diagrams are shown below. Figure 8 As shown. The other two types of multi-stimulus responsive color-changing films exhibit excellent cycling stability for regulation of visible light, near-infrared light, and haze, such as... Figure 9 As shown. Finally, by applying different active stimuli, the state changes of the multi-stimulus responsive color-changing film were achieved, such as... Figure 10 As shown. Spectra under different stimuli are as follows. Figure 11 As shown, the films prepared in Example 1 and Example 2 can both achieve multiple modes in response to different stimuli.

[0047] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A multi-stimuli responsive color-changing film, characterized in that, The multi-stimulus responsive color-changing film comprises a first film, a second film and a third film which are sequentially stacked; The first film comprises a dimethyl polysiloxane material layer, a silica material layer and a dimethyl polysiloxane material layer which are sequentially stacked; The second film is a nano material layer with a function of adjusting near-infrared light by photothermal response; The third film comprises a dimethyl polysiloxane material layer and a humidity responsive layer which are stacked, the dimethyl polysiloxane material layer in the third film is attached to the second film, the elastic modulus of the humidity responsive layer is different from that of the dimethyl polysiloxane material layer by three orders of magnitude, and the recovery speed of the humidity responsive layer is different from that of the dimethyl polysiloxane material layer by three to four orders of magnitude.

2. The multi-stimuli responsive chromic film according to claim 1, wherein The nano-material with photo-thermal response adjusting near-infrared light function is selected from one of tungsten oxide, metal-doped tungsten oxide, vanadium oxide, metal-doped vanadium oxide, GeSbTe alloy, gold nanorod, Cu 2-x S, CuSe, CuTe, PbS, wherein 0 < x < 1.

3. The multi-stimuli responsive chromic film of claim 1, wherein, The material of the humidity responsive layer is selected from one of polyvinyl alcohol, gelatin, chitosan, cellulose and its derivatives, polyurethane, polyacrylamide, poly N-isopropyl acrylamide and polyacrylic acid.

4. The multi-stimuli responsive chromic film of claim 1, wherein, The silica material is silica nanospheres, and the particle size of the silica nanospheres is 200-1000 nm.

5. A method of preparing a multi-stimuli responsive color-changing film, characterized by, The preparation method comprises the following steps: Mixing dimethyl polysiloxane and a curing agent to obtain a dimethyl polysiloxane solution, dissolving the material of the humidity responsive layer in a solvent to obtain a humidity responsive layer solution; Coating the dimethyl polysiloxane solution on a substrate, curing by heating to obtain a dimethyl polysiloxane material layer, assembling silica on the surface of the dimethyl polysiloxane material layer to obtain a silica material layer, and coating the dimethyl polysiloxane solution on the surface of the silica material layer, curing by heating to obtain the first film; Assembling nano materials with a function of adjusting near-infrared light by photothermal response on the surface of the first film to obtain the second film; Coating the dimethyl polysiloxane solution on the surface of the second film, curing by heating to obtain a dimethyl polysiloxane material layer, coating the humidity responsive layer solution on the surface of the dimethyl polysiloxane material layer, and curing by heating to obtain the multi-stimulus responsive color-changing film.

6. The method of claim 5, wherein the multistimuli responsive film is prepared by the steps of: The assembling method is selected from one of spraying, spin coating, blade coating, drop coating, pulling, Langmuir-Blodgett.

7. The method of claim 5, wherein the multistimuli responsive film is prepared by the steps of: The silica material is silica nanospheres, and the preparation method of the silica nanospheres comprises: Mixing ammonia, ethanol and water to obtain a mixed solution; Mixing tetraethyl orthosilicate and ethanol, and then adding the mixed solution into the mixed solution, stirring at 40-80℃ for 0.5-24h, and reacting to obtain the silica nanospheres.

8. The method of claim 5, wherein the multistimuli responsive film is prepared by the steps of: The nano material with a function of adjusting near-infrared light by photothermal response is tungsten oxide nanoparticles, and the preparation method of the tungsten oxide nanoparticles comprises: Dispersing tungsten hexachloride into an organic solvent to obtain a tungsten hexachloride solution; Transferring the tungsten hexachloride solution into a reaction container, reacting at 140-240℃ for 0.5-48h to obtain the tungsten oxide nanoparticles.

9. The method of claim 5, wherein the multistimuli responsive film is prepared by the steps of: The nano material with a function of adjusting near-infrared light by photothermal response is tungsten-doped vanadium oxide, and the preparation method of the tungsten-doped vanadium oxide comprises: Dissolving vanadyl sulfate in water, sequentially adding ammonium metatungstate and hydrazine hydrate to obtain a mixed solution; adjusting the pH value of the mixed solution to 6-8; transferring the mixed solution with pH value of 6-8 into a reaction container, and reacting at 200-260 ℃ for 24-48 h to obtain the tungsten-doped vanadium oxide.

10. The application of the multi-stimulus responsive color-changing film of claim 1 in the field of intelligent doors and windows.

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