Intelligent window glass with composite film layer

Abstract

The invention relates to intelligent window glass with a composite film layer, and belongs to the technical field of intelligent window materials. The intelligent window is composed of outer layer glass, middle layer thermochromic hydrogel and inner layer glass, the surface of the outer layer glass is coated with a W gradient doped VOhydrophilic film layer, tetravalent vanadium and hexavalent tungsten are spin-coated with a low / high concentration precursor solution step by step according to the molar ratio of (0.5-1.5%): 1, the W concentration gradient is 2-3 times, and a W element gradient structure with the inner portion being low and the outer portion being high is formed through nitrogen annealing at the temperature of 650 DEG C; the middle layer is filled with poly (N-isopropylacrylamide) hydrogel, and an interpenetrating network structure with LCST of 32-35 DEG C is formed by regulating the mass ratio of N-isopropylacrylamide to acrylamide (30-80): 1, the concentration of 0.5-2 wt% of potassium persulfate initiator and the polymerization temperature of 60-80 DEG C; a VO / SiO composite hydrophobic membrane is prepared on the surface of the inner-layer glass by adopting a sol-gel method, and a compact-porous composite structure with gradient distribution of SiO content is formed through staged coating of a precursor solution containing 1.5-3ml of tetraethoxysilane and gradient heat treatment at 100 DEG C / 150 DEG C / 300 DEG C.

Description

Technical Field

[0001] The invention belongs to the technical field of smart window materials and relates to a composite film layer smart window glass. Background Art

[0002] With the development of building energy conservation and intelligence, smart windows, as a building material that can automatically adjust lighting and thermal insulation performance according to environmental changes, have attracted widespread attention. 2 ) has a unique metal-insulator phase transition property. At a temperature of 64°C, VO 2 It will transform from a low-temperature monoclinic insulator phase to a high-temperature rutile metallic phase. During the phase transition, its optical and electrical properties will change significantly. For example, the infrared light transmittance will drop sharply. It can effectively block infrared rays in solar radiation, thereby lowering indoor temperature and reducing air-conditioning energy consumption. It has great application potential in the field of smart windows.

[0003] Patent application CN105892101A introduces a composite intelligent energy-saving film and its preparation method, combining VO 2 The advantages of thermochromic smart windows and electrochromic smart windows. The film includes a thermochromic layer (VO 2 (M)), conductive layer, electrochromic layer, ion transport layer and ion storage layer, prepared by vacuum tilt deposition technology; the characteristic is that it can adjust visible light and infrared light at the same time, improve the heat insulation effect and maintain indoor illumination. Patent application CN111139432A proposes a vanadium dioxide smart window film with a moth-eye structure. The film consists of a base layer and W-doped VO 2 Layer composition, VO 2 The layer contains conical, cylindrical or truncated cone-shaped micro-nano structural units; it is prepared by high-energy pulsed magnetron sputtering technology and ion beam etching, and W doping reduces VO 2 The phase transition temperature of the film can reach 66.7%~88.7% at low temperature, and the thermal control ability can reach 7.3%~16.8%. Patent application CN109747240A introduces an electrochromic glass and its preparation and control method, which is composed of VO 2 The film is composed of a gel-like solid electrolyte layer and an electrode layer; by applying voltage, the transmittance of the glass in the visible light and infrared light bands is regulated to achieve lighting and temperature control functions; the electrolyte layer is 1~2mm thick and is made of an organic polymer of conductive ions. Patent application CN106698514A discloses a method for preparing a P-phase vanadium dioxide nanopowder, which uses a hydrothermal method to obtain a P-phase vanadium dioxide nanopowder with a particle size of 50~90nm by reacting ammonium metavanadate and sodium docusate in a formic acid solution; it is green and environmentally friendly, does not require nitrogen protection, is suitable for low-temperature annealing treatment, and is easy to achieve VO 2 (P) To VO 2Patent application CN116395977A proposes a method for preparing vanadium oxide thin films for smart windows, in which VO is prepared on a substrate by magnetron sputtering. 2 film, and adopts SF 6 The gas is subjected to reactive ion etching treatment; after dry etching, wet etching treatment is performed to further optimize the film performance; the visible light transmittance and solar light modulation efficiency of the vanadium oxide film prepared by this method in the 380-2500nm band both meet the standards for use of smart windows.

[0004] However, the above patented products have some shortcomings, such as the relatively high phase change temperature, which is difficult to reach by relying solely on the energy of sunlight; in terms of the adjustment ability in the near-infrared light region, it is often unable to effectively block or transmit near-infrared light, resulting in the difficulty of effectively controlling the indoor temperature, and the weak self-cleaning ability is also a major drawback. Due to the lack of self-cleaning properties caused by the hydrophilicity of the surface material, windows are prone to accumulate dust and dirt, which not only affects the light transmission effect, but also increases the difficulty and cost of cleaning and maintenance. In addition, traditional smart window glass also has certain limitations in terms of adjustment speed, weather resistance, transparency, etc., and it is difficult to meet the urgent needs of modern buildings for high-performance and multi-functional smart window glass. Therefore, the development of new smart window glass with stronger near-infrared light adjustment ability and self-cleaning ability has become an important direction of current research.

[0005] To solve the above problems, this patent achieves self-cleaning through the outer hydrophilic film layer, the hydrogel adjusts the light transmittance in real time at a lower temperature, and the hydrophobic design of the inner layer. This composite film layer shows multiple advantages on smart window glass. First, the hydrophilicity of the outer layer enables the window surface to automatically repel dust and dirt, achieve a self-cleaning effect, and reduce the need for cleaning and maintenance. Secondly, the hydrogel layer can adjust the light transmittance in real time at a lower temperature, and automatically adjust the transparency of the window according to environmental changes, which not only ensures sufficient indoor light, but also effectively insulates and improves energy-saving performance. Finally, the hydrophobic design of the inner layer can inhibit the condensation of water vapor on the glass from warm air, prevent moisture penetration, and extend the service life of the window. Summary of the invention

[0006] The object of the present invention is to provide a composite film layer intelligent window glass, which has the characteristics of self-cleaning and good light transmittance.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A composite film layer smart window glass, the smart window glass comprises an outer layer of glass and an inner layer of glass, the outer layer of glass is coated with a hydrophilic film layer, a thermochromic hydrogel is filled between the outer layer of glass and the inner layer of glass, and the inner layer of glass is coated with a hydrophobic film layer. The hydrophilic film layer coated on the outer glass is mainly composed of VO doped with W element.2 , the W content in the film layer is less inside and more outside; Among them, the thermochromic hydrogel filled between the outer glass and the inner glass has poly N-isopropylacrylamide PNIPAM as its main component; Wherein, the composite film coated on the inner glass is composed of VO 2 With SiO 2 Composite film composition.

[0008] Furthermore, the preparation method of the hydrophilic film layer coated on the outer glass is to mix the tetravalent vanadium in the vanadium source and the hexavalent tungsten in the tungsten source in a molar ratio of (0.5~1.5%):1, stir evenly with an alcohol solvent, and stand for aging to prepare a low-concentration precursor solution 1 and a high-concentration precursor solution 2, respectively, wherein the W element content of the latter is 2~3 times that of the former.

[0009] Furthermore, the hydrophilic film layer coated on the outer glass is coated by spin coating at a speed of 1800~2000r / min. During coating, a low-concentration precursor solution 1 is first applied, and after drying, it is placed in a muffle furnace and annealed at a high temperature of 650°C for 1h under nitrogen protection. Then, a high-concentration precursor solution 2 is applied, and after drying, it is placed in a muffle furnace again and annealed at a high temperature of 650°C for 1h under nitrogen protection to complete the coating of the hydrophilic film layer.

[0010] Furthermore, the preparation method of the thermochromic hydrogel filled between the outer glass and the inner glass is to add N-isopropylacrylamide monomer, N,N'-methylenebisacrylamide and potassium sulfate to deionized water, stir while heating, the stirring rate is 300r / min, the stirring time is 25min, and then acrylamide is added for polymerization reaction to obtain the PNIPAM hydrogel, and stable nitrogen bubbling is maintained throughout the process.

[0011] Furthermore, when the PNIPAM hydrogel is prepared, the heating temperature is 60-80° C., the concentration range of the potassium persulfate solution is 1.5 wt %, and the mass ratio of N-isopropylacrylamide to potassium persulfate is (30-80):1.

[0012] Furthermore, the preparation method of the composite film coated on the inner glass is: S6.1: 100 ml of N,N-dimethylacetamide DMAC was used as solvent, 4 g of PMDA and 4,4'-diaminodiphenyl ether ODA were added in a 1:1 molar ratio, and the mixture was stirred at 35°C and 500 r / min for 2.5 h to synthesize polyamic acid sol by a sol-gel method; S6.2: Preparation of precursor solution 1: Mix 20 ml of isopropanol, 1.5-2 ml of ethyl orthosilicate and 0.5 mmol of vanadium acetylacetonate and stir for 24 h to obtain a solution containing SiO 2 and VO 2 The precursor solution 1; S6.3: Preparation of precursor solution 2: Under the same conditions, adjust the amount of ethyl orthosilicate to 2-3 ml, and keep the other components and amounts the same as those of precursor solution 1 to obtain a solution containing SiO 2 and VO 2 Precursor solution 2; S6.4: Preparation of low SiO 2 Content VO 2 Film layer: 20 ml of polyamic acid sol was mixed with 1.5 ml of precursor solution 1, stirred for 6 h, and then spin-coated on the substrate surface. After heat treatment at 100 °C, 150 °C, and 300 °C for 1 h each, a low SiO 2 Content VO 2 Membrane layer; S6.5: Preparation of high SiO 2 Content VO 2 Film layer: Mix polyamic acid sol and precursor solution 2 in the same volume ratio of S6.4, repeat spin coating and staged heat treatment, and 2 High SiO content film 2 Content VO 2 Composite film layer.

[0013] The composite film layer smart window glass provided by the present invention realizes the comprehensive optimization of light and heat regulation, self-cleaning and long-term stability through the innovative gradient doping structure design, dynamic thermal response mechanism and synergistic effect of multifunctional film layer, and has significant technical breakthroughs in energy saving efficiency, environmental adaptability and intelligent level. Its creativity and beneficial effects are specifically manifested as follows: In terms of material system and functional coordination, the outer glass uses gradient W-doped VO 2 The hydrophilic film layer is formed by mixing tetravalent vanadium and hexavalent tungsten in a molar ratio of (0~15%):1, and then spin-coating a low-concentration precursor solution 1 (W / V=0~5%) and a high-concentration precursor solution 2 (W / V=7.5~15%) step by step to form a gradient distribution structure of W elements with low inside and high outside. 2The phase change temperature is optimized from 68°C to 25~40°C, which is close to the actual ambient temperature requirements. The outer layer with high W concentration (W content is 1.5~3 times that of the inner layer) reduces the phase change threshold through lattice distortion, and the inner layer with low concentration maintains high infrared reflectivity (RIR≥80% after phase change). The overall solar modulation efficiency ΔTsol reaches 35%, and the visible light transmittance Tvis≥60%. The water contact angle on the hydrophilic film surface is ≤15°, and the self-cleaning function is realized by combining photocatalytic activity. The pollutant degradation rate is ≥90% / 24h, which overcomes the limitation of traditional electrochromic glass relying on external power control.

[0014] The middle layer of thermochromic PNIPAM hydrogel adopts a dual monomer system (NIPAM and acrylamide mass ratio of 30~80:1), and forms an interpenetrating network structure at a polymerization temperature of 60~80℃. Its lower critical solution temperature can be adjusted to 32~35℃, the phase change response time is ≤3 minutes, and the swelling ratio change rate is ≥80%. When the temperature is higher than LCST, the haze of this layer quickly increases from the initial ≤5% to ≥85%, dynamically adjusting the lighting and heat insulation performance. Under summer conditions, the overall solar energy transmittance g value is ≤0.25, which is 50% lower than that of conventional insulating glass (g value ≈ 0.5), and the air conditioning energy consumption is reduced by 30~45%. After polymerization under nitrogen protection, the three-dimensional network structure has a tensile strength of ≥1.5MPa, a pore size of 50~200nm, and a mechanical property of 87.5% higher than that of traditional hydrogels, and a service life of more than 2 times.

[0015] Inner VO 2 / SiO 2 Composite membranes constructed by sol-gel method SiO 2 Gradient distribution (volume ratio of ethyl orthosilicate in precursor solution 1 and 2 is 1.5:2), and a dense-porous composite structure is formed by staged heat treatment (desolventization at 100℃, imidization at 150℃, and crystallization at 300℃). 2 Content ≥ 60at.%, water contact angle ≥ 120°, dust adhesion is reduced by more than 70%, and the maintenance cycle is extended to 3~5 years. The film has a visible light transmittance Tvis ≥ 70%, infrared reflectivity RIR ≥ 85%, UV blocking rate ≥ 99%, hardness of 6H, scratch resistance ≥ 5000 times, which is better than conventional VO 2 / SiO 2 The mechanical properties of the membrane are improved by 50%.

[0016] In terms of manufacturing process innovation, the outer layer W-VO 2The gradient membrane adopts a dual precursor spin coating and segmented annealing process, with a spin coating speed of 1800~2000r / min to ensure the uniformity of the membrane layer. Two 650℃ nitrogen annealings make the membrane-base bonding strength ≥15MPa, and the cycle stability reaches 5000 phase changes after ΔTsol decay ≤5%. The intermediate hydrogel achieves the optimization of pore size distribution and mechanical properties through the precise control of potassium persulfate concentration (0.5~2wt.%) and monomer / initiator mass ratio (30~80:1), combined with a stirring rate of 300r / min and a reaction time of 25min. The inner composite membrane uses a volume ratio of polyamic acid sol to precursor solution of 1:0.075~0.1 (20ml sol with 1.5~2ml precursor), and after three spin coatings and gradient heat treatments, the membrane thickness is precisely controlled to 500±50nm, and the membrane density is increased by 30%.

[0017] In terms of comprehensive performance, the smart window has an outer layer of W-VO 2 The film starts infrared reflection (RIR ≥ 80%), the haze of the middle hydrogel is increased to ≥ 85%, and the overall g value is ≤ 0.25; under winter conditions (5°C), the outer layer maintains a high transparency (Tsol ≥ 70%), the hydrogel is transparent (Tvis ≥ 80%), and the indoor heat gain coefficient is increased by more than 40%. Its comprehensive energy-saving efficiency is more than 40%, and it does not require external power drive, reducing operating costs by 70%. The surface self-cleaning function reduces maintenance costs by 80% compared to ordinary curtain wall glass, and it still maintains excellent light transmittance in hot and humid, dusty environments.

[0018] The present invention solves the pain points of the existing smart window technology, such as the single photothermal regulation mode, high energy consumption, and frequent maintenance, through the triple innovative design of gradient doping to optimize phase change response, dynamic hydrogel to regulate photothermal transmission, and hydrophobic / hydrophilic film layer collaborative self-cleaning. It achieves the unity of high efficiency energy saving and long-term stability, and provides a breakthrough solution for the fields of green buildings and smart homes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0020] Figure 1 A schematic diagram of the structure of the smart window of the present invention; Description of reference numerals: Figure 1 Middle: 10, VO with high W content 2 Film layer; 11. VO with less W content 2 Membrane layer; 12, outer glass; 13, thermochromic hydrogel; 20, SiO 2 VO 2 Film layer, 21, SiO 2 Low content of VO 2Film layer, 22, inner glass. DETAILED DESCRIPTION

[0021] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0022] Example 1

[0023] 1. Change of W element content VO 2 Preparation of membrane layer: According to the molar ratio of hexavalent tungsten to tetravalent vanadium of 0.5%:1, 1g of acetylacetonatovanadium, 40ml of methanol, and 0.0075g of tungsten hexachloride were mixed together, stirred for 24h, and then aged for 48h to obtain precursor solution 1; according to the molar ratio of hexavalent tungsten to tetravalent vanadium of 1%:1, 60ml of methanol and 0.015g of tungsten hexachloride were mixed together, and the other parameters were the same as those of precursor solution 1 to obtain precursor solution 2; precursor solution 1 was dripped onto a spin coater, and spin coated at a speed of 1800r / min. After drying, it was placed in a muffle furnace and annealed at 650℃ for 1h under nitrogen protection to prepare VO with less W content. 2 Precursor solution 2 was added dropwise to the spin coater, and the other parameters were the same to prepare VO with a high W content on the outer glass. 2 Membrane layer; 2. Preparation of PNIPAM hydrogel: 2.5 g of N-isopropyl acrylamide monomer, 2.5 mg of N,N'-methylenebisacrylamide and 100 mL of deionized water were stirred for 25 min under nitrogen bubbling conditions to form a mixed solution of monomer and crosslinker; 20 mL of the solution was taken out and added to 40 mL of deionized water, and after nitrogen bubbling for 10 min, it was heated to 70°C and 5 mL of 1.5 wt% potassium persulfate solution was added; The remaining monomer and cross-linking agent mixed solution was added, nitrogen bubbling and stirring speed of 300 rpm were maintained for 90 minutes, and then cooled to prepare a polyisopropylacrylamide microgel dispersion; Take out 2 mL of the dispersion, add 0.4 g of acrylamide, 0.2 mg of N,N'-methylenebisacrylamide, 2 mg of potassium persulfate, and 8.5 L of tetramethylethylenediamine, use ultrasonic waves to dissolve the acrylamide monomer, and transfer the solution to a mold composed of an outer glass layer and an inner glass layer; 3.SiO 2 Content change VO 2 Preparation of membrane layer: Using 100 ml of N,N-dimethylacetamide DMAC as solvent, adding 4 g of dried pyromellitic acid PMDA and 4.4'-diaminodiphenyl ether ODA, wherein the molar ratio of PMDA to ODA is 1:1, the temperature is controlled at 35°C, the rotation speed is 500 r / min, and the time is 2.5 h, the polyamic acid sol is synthesized by the sol-gel method; Take 20 ml of isopropanol, 1.5 ml of ethyl orthosilicate, and 0.5 mmol of vanadium acetylacetonate, and stir for 24 hours to obtain a solution containing SiO 2 , VO 2 Precursor solution 1; add 2 ml of ethyl orthosilicate and 0.5 mmol of vanadium acetylacetonate, and the rest is the same as that of precursor solution 1 to obtain a SiO 2 , VO 2 Precursor solution 2; Mix 20 ml of polyamic acid sol with 1.5 ml of SiO 2 , VO 2 Precursor solution 1 was stirred for 6 hours; a prefabricated film layer was prepared on the inner glass layer by spin coating, and the first heat treatment was carried out in a muffle furnace at 100°C, 150°C, and 300°C for 1 hour each to prepare SiO 2 Low VO 2 Film layer; mixed polyamide acid sol and SiO 2 , VO 2 Precursor solution 2, other parameters such as containing SiO 2 , VO 2 Precursor solution 1, through the second heat treatment, in the low SiO 2 Content VO 2 High SiO 2 VO content 2 Membrane layer.

[0024] In this embodiment, the water droplets and the W element content change VO 2 The contact angle of the film layer is less than 15°. The transmittance is tested using a spectrophotometer and an infrared spectrometer. Before testing, ensure that the sample is stable at the set temperature for 10 minutes. The transmittance of visible light (550nm) and near-infrared light (1650nm) at different temperatures is evaluated. The transmittances of visible light and near-infrared light are 9% and 55% at 5°C, and 95% and 52% at 25°C.

[0025] Example 2

[0026] 1. Change of W element content VO 2 Preparation of membrane layer: According to the molar ratio of hexavalent tungsten to tetravalent vanadium of 0.5%:1, 1g of acetylacetonatovanadium, 40ml of methanol, and 0.0075g of tungsten hexachloride were mixed together, stirred for 24h, and then aged for 48h to obtain precursor solution 1; according to the molar ratio of hexavalent tungsten to tetravalent vanadium of 1.5%:1, 60ml of methanol and 0.015g of tungsten hexachloride were mixed together, and the other parameters were the same as those of precursor solution 1 to obtain precursor solution 2; precursor solution 1 was dripped onto a spin coater, and spin coated at a speed of 2000r / min. After drying, it was placed in a muffle furnace and annealed at 650℃ for 1h under nitrogen protection to prepare VO with less W content. 2 Precursor solution 2 was added dropwise to the spin coater, and the other parameters were the same to prepare VO with a high W content on the outer glass. 2 Membrane layer; 2. Preparation of PNIPAM hydrogel: 2.5 g of N-isopropyl acrylamide monomer, 2.5 mg of N,N'-methylenebisacrylamide and 100 mL of deionized water were stirred for 25 min under nitrogen bubbling conditions to form a mixed solution of monomer and crosslinker; 20 mL of the solution was taken out and added to 40 mL of deionized water, and after nitrogen bubbling for 10 min, it was heated to 70°C and 5 mL of 1.5 wt% potassium persulfate solution was added; The remaining monomer and cross-linking agent mixed solution was added, nitrogen bubbling and stirring speed of 300 rpm were maintained for 90 minutes, and then cooled to prepare a polyisopropylacrylamide microgel dispersion; Take out 2 mL of the dispersion, add 0.4 g of acrylamide, 0.2 mg of N,N'-methylenebisacrylamide, 2 mg of potassium persulfate, and 8.5 L of tetramethylethylenediamine, use ultrasonic waves to dissolve the acrylamide monomer, and transfer the solution to a mold composed of an outer glass layer and an inner glass layer; 3.SiO 2 Content change VO 2 Preparation of membrane layer: Using 100 ml of N,N-dimethylacetamide DMAC as solvent, adding 4 g of dried pyromellitic acid PMDA and 4.4'-diaminodiphenyl ether ODA, wherein the molar ratio of PMDA to ODA is 1:1, the temperature is controlled at 35°C, the rotation speed is 500 r / min, and the time is 2.5 h, the polyamic acid sol is synthesized by the sol-gel method; Take 20ml isopropanol, 2ml ethyl orthosilicate, 0.5mmol vanadium acetylacetonate, stir for 24h, and obtain a solution containing SiO 2 , VO 2 Precursor solution 1; add 3 ml of ethyl orthosilicate and 0.5 mmol of vanadium acetylacetonate, and the rest is the same as that of precursor solution 1 to obtain a SiO 2 , VO2 Precursor solution 2; Mix 20 ml of polyamic acid sol with 1.5 ml of SiO 2 , VO 2 Precursor solution 1 was stirred for 6 hours; a prefabricated film layer was prepared on the inner glass layer by spin coating, and the first heat treatment was carried out in a muffle furnace at 100°C, 150°C, and 300°C for 1 hour each to prepare SiO 2 Low VO 2 Film layer; mixed polyamide acid sol and SiO 2 , VO 2 Precursor solution 2, other parameters such as containing SiO 2 , VO 2 Precursor solution 1, through the second heat treatment, in the low SiO 2 Content VO 2 High SiO 2 VO content 2 Membrane layer.

[0027] In this embodiment, the water droplets and the W element content change VO 2 The contact angle of the film layer is less than 16.5°. The transmittance is tested using a spectrophotometer and an infrared spectrometer. Before testing, ensure that the sample is stable at the set temperature for 10 minutes. The transmittance of visible light (550nm) and near-infrared light (1650nm) at different temperatures is evaluated. The transmittances of visible light and near-infrared light are 10.5% and 56% at 5°C, and 92% and 50% at 25°C.

[0028] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A composite film layer smart window glass, the smart window glass comprising an outer layer of glass and an inner layer of glass, characterized in that: The outer glass is coated with a hydrophilic film layer, the space between the outer glass and the inner glass is filled with a thermochromic hydrogel, and the inner glass is coated with a hydrophobic film layer. The main component of the hydrophilic film layer coated on the outer glass is VO2 doped with W element, and the content of W element in the film layer is less inside and more outside; Among them, the thermochromic hydrogel filled between the outer glass and the inner glass has poly N-isopropylacrylamide PNIPAM as its main component; Wherein, the composite film coated on the inner layer of glass is a composite film composed of VO2 and SiO2.

2. The composite film layer smart window glass according to claim 1, characterized in that: The preparation method of the hydrophilic film layer coated on the outer glass is as follows: tetravalent vanadium in the vanadium source and hexavalent tungsten in the tungsten source are mixed in a molar ratio of (0.5-1.5%):1, stirred evenly with an alcohol solvent, and allowed to stand for aging to prepare a low-concentration precursor solution 1 and a high-concentration precursor solution 2, respectively, wherein the W element content of the latter is 2-3 times that of the former.

3. The composite film layer smart window glass according to claim 1, characterized in that: The hydrophilic film layer coated on the outer glass is coated by spin coating at a rotation speed of 1800~2000r / min. During coating, a low-concentration precursor solution 1 is first applied, and after drying, it is placed in a muffle furnace and annealed at a high temperature of 650°C for 1h under nitrogen protection. Then a high-concentration precursor solution 2 is applied, and after drying, it is placed in a muffle furnace again and annealed at a high temperature of 650°C for 1h under nitrogen protection to complete the coating of the hydrophilic film layer.

4. The composite film layer smart window glass according to claim 1, characterized in that: The preparation method of the thermochromic hydrogel filled between the outer glass and the inner glass is as follows: N-isopropyl acrylamide monomer, N,N'-methylenebisacrylamide and potassium sulfate are added to deionized water, and stirred while heating at a stirring rate of 300 r / min for 25 min, and then acrylamide is added for polymerization reaction to obtain the PNIPAM hydrogel, and nitrogen is maintained to stably bubble throughout the process.

5. The composite film layer smart window glass according to claim 4, characterized in that: When the PNIPAM hydrogel is prepared, the heating temperature is 60-80° C., the concentration range of the potassium persulfate solution is 1.5 wt %, and the mass ratio of N-isopropylacrylamide to potassium persulfate is (30-80):

1.

6. The composite film layer smart window glass according to claim 1, characterized in that: The method for preparing the composite film coated on the inner glass is as follows: S6.1: 100 ml of N,N-dimethylacetamide DMAC was used as solvent, 4 g of PMDA and 4,4'-diaminodiphenyl ether ODA were added in a 1:1 molar ratio, and the mixture was stirred at 35°C and 500 r / min for 2.5 h to synthesize polyamic acid sol by a sol-gel method; S6.2: Prepare precursor solution 1: Mix 20 ml of isopropanol, 1.5-2 ml of ethyl orthosilicate and 0.5 mmol of vanadium acetylacetonate, and stir for 24 h to obtain precursor solution 1 containing SiO2 and VO2; S6.3: Prepare precursor solution 2: Under the same conditions, adjust the amount of ethyl orthosilicate added to 2-3 ml, and keep the other components and amounts the same as those of precursor solution 1, to obtain precursor solution 2 containing SiO2 and VO2; S6.4: Preparation of a VO2 film layer with low SiO2 content: 20 ml of polyamic acid sol was mixed with 1.5 ml of precursor solution 1, and the mixture was spin-coated on the substrate surface after stirring for 6 h, and then heat-treated at 100°C, 150°C, and 300°C for 1 h each in stages to form a VO2 film layer with low SiO2 content; S6.5: Preparation of VO2 film layer with high SiO2 content: Mix the polyamic acid sol and precursor solution 2 in the same volume ratio as S6.4, repeat spin coating and staged heat treatment to form a VO2 composite film layer with high SiO2 content on the film layer with low SiO2 content.

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