Anti-freezing ultra-wide spectrum modulated overturning intelligent window and preparation method thereof

Abstract

The preparation method comprises the following steps: copolymerizing N, N-diethyl-2-acrylamide and methacrylic acid through a reverse atom transfer radical polymerization method to obtain a polymer solution, and injecting the polymer solution into hollow glass for packaging; and attaching a polyvinylidene fluoride (PVDF) film and a polyethylene glycol terephthalate-indium tin oxide (PET-ITO) film to the upper surface and the lower surface of the glass to obtain the glass. The polymer solution has excellent anti-freezing performance, has high sunlight transmittance below the phase-change temperature, and can generate strong light scattering above the phase-change temperature, prevent sunlight from entering and realize effective modulation of sunlight. The PVDF thin film and the PET-ITO thin film realize thermal modulation by regulating and controlling the emissivity of mid-infrared light, and realize ultra-wide spectrum modulation covering a solar spectrum and a thermal spectrum. The material has freezing resistance, ultra-wide spectrum modulation and excellent temperature regulation and control and energy-saving performance, and is of great significance to development and application of building energy-saving materials.

Description

Technical Field

[0001] The invention relates to an anti-freezing ultra-wide spectrum modulated flip smart window and a preparation method thereof, belonging to the field of building energy conservation. Background Art

[0002] Buildings consume 30% to 40% of global energy consumption, with approximately half of this energy going to heating, ventilation, and air-conditioning systems. Windows are the primary source of heat gain in the summer and heat loss through conduction in the winter, causing visual and physical discomfort. They are considered the least energy-efficient component of a building structure. Therefore, it is necessary to design smart windows that can dynamically adjust indoor heat according to ambient temperature changes, thereby improving building energy efficiency and reducing carbon emissions.

[0003] Based on the type of color rendering technology, current smart windows can be categorized as electrochromic, photochromic, mechanochromic, and thermochromic. Thermochromic smart windows offer the advantages of low cost, passive light modulation, and zero energy input. They can dynamically adjust the amount of sunlight entering a room based on changes in ambient temperature, thereby improving building energy efficiency.

[0004] Chinese patent application CN119976956A discloses a nanoparticle thermochromic smart window coating. Tungsten-doped M-phase vanadium dioxide nanoparticles are synthesized using a hydrothermal method and dispersed in polyvinylpyrrolidone to form a dispersion. The upper layer of this dispersion is then applied to a glass substrate to create a smart window. This smart window exhibits a visible transmittance of 49.8% and a near-infrared light modulation efficiency of 9.3%. However, it suffers from weak light management performance and lacks thermal modulation, resulting in a narrow modulation spectrum and limited energy savings. In 2025, Materials Horizons reported on a high-energy-storage thermosensitive hydrogel synthesized by leveraging the high specific heat capacity of water, the phase-change heat absorption of k-carrageenan, and the solar modulation capability of hydroxypropyl cellulose. This hydrogel was used to construct a multi-gradient energy-saving smart window with thermal response and multimodal thermal energy storage. The window exhibits high visible light transmittance, excellent solar modulation efficiency, and exceptional specific heat absorption. However, due to its high water content, the smart window has weak anti-freezing performance and can only modulate sunlight but not heat. This results in limited application environment and energy-saving effect of the smart window (Multi-gradient energy-saving smart windows with thermo-response and multimodal thermal energy storage, 2025, 12, 1664).

[0005] To date, most thermochromic smart windows have suffered from weak anti-freeze performance and a narrow spectral modulation range. Developing smart windows with excellent anti-freeze performance and ultra-wide spectral modulation across both the solar and thermal spectra, allowing for simultaneous modulation of solar transmittance and mid-infrared emissivity, is of great significance. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a flip smart window with anti-freezing ultra-wide spectrum modulation and a preparation method thereof. The smart window not only has excellent anti-freezing performance and can be used in a wide temperature range, but also has ultra-wide spectrum modulation covering the solar spectrum and thermal spectrum, and can simultaneously modulate the solar light transmittance and mid-infrared light emissivity to achieve the purpose of high efficiency and energy saving.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the present invention is, on the one hand, to provide an anti-freezing ultra-wide spectrum modulation flip smart window, which is composed of a polymer solution formed by copolymerization of N,N-diethyl-2-acrylamide NNDEAm monomer and methacrylic acid MAA monomer encapsulated in a laminated glass formed by hollow glass, and a polyethylene terephthalate-indium tin oxide PET-ITO film with low mid-infrared light emissivity and a polyvinylidene fluoride PVDF film with high and medium infrared light emissivity respectively attached to the upper and lower surfaces of the laminated glass.

[0008] In another aspect, the present invention provides a method for preparing the aforementioned flip smart window. NNDEAm and MAA monomers are copolymerized via reverse atom transfer radical polymerization to obtain a polymer solution, which is then injected into insulating glass to form a laminated glass. PET-ITO and PVDF films are then attached to the upper and lower surfaces of the laminated glass, respectively, to create a flip smart window with anti-freeze and ultra-wide spectrum modulation. The specific steps are as follows:

[0009] (1) Dissolving NNDEAm monomer, MAA monomer, potassium persulfate (KPS, initiator), iron salt, and isopropyl alcohol (IPA) in deionized water and heating to obtain a poly(N,N-diethyl-2-acrylamide-co-methacrylic acid) P(NNDEAm-MAA) solution;

[0010] (2) Injecting the P(NNDEAm-MAA) solution into insulating glass to form laminated glass;

[0011] (3) The PVDF film was first hydrophobically modified (A self-adaptive film for passiveradiative cooling and solar heating regulation, 2022, 10, 11092), and then the modified PVDF film and PET-ITO film were attached to the upper and lower surfaces of the laminated glass, respectively, to obtain an anti-freezing ultra-wide spectrum modulation flip smart window.

[0012] Furthermore, in step (1), the iron salt is ferric chloride (FeCl3), ferric sulfate (Fe2(SO4)3) or ferric citrate (FeCit3), and the molar ratio of NNDEAm monomer and MAA monomer is 10:1-2:1; the total monomer concentration of NNDEAm monomer and MAA monomer in deionized water is 1.9-2.6 mol / L, KPS is 0.1-1.0 mol% of the total content of NNDEAm monomer and MAA monomer, the iron salt concentration is 0.01-0.05 g / 10 mL, and the IPA concentration is 0.01-0.05 mol / 10 mL; the heating temperature is 50-90°C, and the time is 1-6 h.

[0013] Preferably, in step (1), the iron salt is ferric chloride, the molar ratio of NNDEAm monomer to MAA monomer is 5:1; the total monomer concentration of NNDEAm monomer and MAA monomer in deionized water is 2.1 mol / L, KPS is 0.5 mol% of the total content of NNDEAm monomer and MAA monomer, the iron salt concentration is 0.03 g / 10 mL, and the IPA concentration is 0.03 mol / 10 mL; the heating temperature is 70° C. and the time is 3 h.

[0014] Furthermore, the thickness of the single layer of insulating glass is 1.0mm, and the thickness of the interlayer is 0.14-0.70mm.

[0015] Preferably, the interlayer thickness of the insulating glass is 0.28 mm.

[0016] Furthermore, the thickness of the PVDF film is 0.05-1.0 mm, the thickness of the PET in the PET-ITO film is 0.05-1.0 mm, and the thickness of the surface ITO is 0.05-0.2 mm.

[0017] Preferably, the thickness of the PVDF film is 0.5 mm, the thickness of the PET in the PET-ITO film is 0.5 mm, and the thickness of the surface ITO is 0.1 mm.

[0018] PET-ITO is a commercially available product that is obtained by sputtering a transparent indium tin oxide (ITO) conductive film coating on a PET substrate using magnetron sputtering technology and then undergoing high-temperature annealing treatment.

[0019] Beneficial effects of the present invention:

[0020] (1) The anti-freeze ultra-wide spectrum modulation flip smart window of the present invention is prepared by reverse atom transfer radical polymerization of P(NNDEAm-MAA) solution, which is then combined with PVDF film and PET-ITO film to construct an anti-freeze ultra-wide spectrum modulation flip smart window. The P(NNDEAm-MAA) solution gives the flip smart window excellent anti-freeze performance and solar light modulation ability, while the PVDF film with high and medium infrared light emissivity and the PET-ITO film with low mid-infrared light emissivity give the flip smart window excellent thermal modulation ability. The three factors work together to give the flip smart window of the present invention excellent anti-freeze performance and ultra-wide spectrum modulation covering the solar spectrum and thermal spectrum.

[0021] (2) The anti-freeze ultra-wide spectrum modulation flip smart window of the present invention has excellent anti-freeze performance. By introducing isopropyl alcohol into the P(NNDEAm-MAA) solution to form strong hydrogen bonds between water and isopropyl alcohol, the hydrogen bonding between water molecules is weakened, thereby inhibiting water crystallization. This allows the P(NNDEAm-MAA) solution to remain liquid and highly transparent at low temperatures, thus achieving the anti-freeze performance of the flip smart window.

[0022] (3) The anti-freeze ultra-wide spectrum modulation flip smart window of the present invention has ultra-wide spectrum modulation covering the solar spectrum and thermal spectrum. The P(NNDEAm-MAA) solution has high solar transmittance below the phase transition temperature (26.5°C) and can resist the entry of sunlight above the phase transition temperature, achieving effective modulation of sunlight. At the same time, the PVDF film and PET-ITO film can achieve thermal modulation by regulating the mid-infrared emissivity, thereby achieving ultra-wide spectrum modulation.

[0023] (4) The anti-freeze ultra-wide spectrum modulation flip smart window of the present invention has excellent temperature control and energy-saving performance. Compared with ordinary glass windows, the flip smart window of the present invention can significantly reduce the indoor temperature by 24.2°C in hot summer and increase the indoor temperature by 6.4°C in cold winter. Compared with commercially available ordinary glass windows and low-e windows, the flip smart window has the best year-round energy-saving potential in four regions: Anchorage, Beijing, Hong Kong, and Abu Dhabi, UAE, demonstrating its excellent temperature control and energy-saving performance under all climate conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the mechanism and function of the flip smart window.

[0025] Figure 2 1 and 2 are the solar spectrum and thermal spectrum of the flip smart window of Example 1. In the figure, (A) is the cooling mode and (B) is the heating mode.

[0026] Figure 3 The solar spectrum and transmittance of the flip smart windows with different interlayer thicknesses, as well as their transmittance control capabilities, are shown in Figures 1, 4, 5, 6, and 7. In the figure, (A) shows the full-spectrum solar transmittance of the flip smart windows with interlayer thicknesses of 0.14-0.70 mm, and (B) shows the average transmittance in the visible, near-infrared, and solar regions, and the corresponding modulation capabilities, calculated using equations (1) and (2) for the full-spectrum solar transmittance data in Figure (A).

[0027] Figure 4 The anti-freeze performance test of the flip smart window of Example 1 and Comparative Example 1 is shown in Figure 1. (A) shows the freezing point of Example 1 and Comparative Example 1 measured by differential scanning calorimetry, and (B) shows the transmittance of Example 1 and Comparative Example 1 at -14°C.

[0028] Figure 5 This is an indoor simulation test of temperature control using the smart windows of Example 1 and Comparative Example 2. (A) shows the temperature curves inside model houses equipped with insulating glass windows, Example 1, and Comparative Example 2, while (B) shows the temperature difference between the model houses equipped with Example 1 and Comparative Example 2 and the model house equipped with insulating glass.

[0029] Figure 6 This is an outdoor test of temperature control of the smart windows of Example 1 and Comparative Example 2. In the figure, (A) and (B) were conducted in a hot summer environment, and (C) and (D) were conducted in a cold winter environment.

[0030] Figure 7 This is an energy-saving simulation of the smart windows of Example 1 and Comparative Example 2. In the figure, (A), (B), (C), and (D) represent the monthly HVAC energy consumption of Anchorage, USA; Beijing, China; Hong Kong, China; and Abu Dhabi, UAE, respectively.

[0031] Figure 8 It is the annual energy-saving effect of the smart windows of Example 1 and Comparative Example 2.

[0032] Figure 9 These are the phase transition temperature test results of the smart windows of Example 1 and Comparative Example 3.

[0033] Figure 10 The P(NNDEAm-co-MAA) solutions prepared in Example 1, Comparative Example 4 and Comparative Example 5 are shown.

[0034] Figure 11 The solar spectrum and solar transmittance and corresponding modulation capabilities of Example 1, Comparative Example 6 and Comparative Example 7 are shown. In the figure, (A) is the full spectrum transmittance of sunlight, and (B) is the average transmittance of the sunlight region and the corresponding modulation capability. DETAILED DESCRIPTION

[0035] The following examples further illustrate the specific embodiments of the present invention. Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0036] The performance test method of the flip smart window is as follows:

[0037] (1) Antifreeze performance test: 15 μL of P(NNDEAm-MAA) solution was placed in an aluminum crucible of a differential scanning calorimeter (TAQ2000) and sealed. The cooling rate was set to 2°C / min and the temperature range was -50-10°C. The thermal effect of the P(NNDEAm-MAA) solution during heating and cooling was measured to determine its freezing point. 3.5 mL of P(NNDEAm-MAA) solution was added to a quartz cuvette, which was placed between the light source and the receiver of a transmittance meter (LH-221). The device was placed in a room temperature environment (25°C) and a freezer (-14°C) for 3 h to measure the change in visible light transmittance of the P(NNDEAm-MAA) solution.

[0038] (2) UV-visible-near-infrared transmittance spectrum test: The flip smart window is placed on a UV-visible-near-infrared spectrophotometer (TP-760) equipped with a hot and cold stage to test its transmittance of the full spectrum of sunlight from 280 to 2500 nm at 25°C and 40°C. Equations (1) and (2) are used to calculate the visible light transmittance T lum (380-780nm), near-infrared light transmittance T NIR (780-2500nm), solar transmittance T sol (280-2500nm) and the corresponding transmittance modulation capability (efficiency) ΔT lum / NIR / sol :

[0039]

[0040] ΔT lum / NIR / sol =T lum / NIR / sol (25℃)-T lum / NIR / sol (40℃) (2)

[0041] In equation (1), T(λ) is the light transmittance at wavelength λ, is the standard efficiency function, is the solar radiation spectrum function under the atmospheric mass AM1.5 condition.

[0042] (3) Thermal emission spectrum test: The flip smart window was placed on a Fourier transform infrared spectrometer (Spotlight 220i) equipped with a hot and cold stage to test its mid-infrared light reflectivity (ρ) and transmittance (τ) of the 2.5-16 μm thermal spectrum at 25°C and 40°C, and the mid-infrared light emissivity (ε) was calculated using equation (3):

[0043] ε=1-ρ-τ (3)

[0044] (4) Temperature control experiment: 5 blocks with a volume of 70×70×1mm were used. 3 A glass box with an empty top was prepared from a quartz glass sheet as a model house. The sides and bottom were wrapped with 10mm thick polystyrene foam. A K-type thermocouple was placed at the bottom of the model house to record the time-temperature curve inside the house. Insulating glass windows, temperature-sensitive gel smart windows, and flip smart windows were installed on the top of the model house in sequence. A light intensity of 1 sun (1000w / m 2 A xenon lamp (Newport 94023A) with an AM1.5 atmospheric mass was used as a sunlight irradiation source to illuminate the model room for 30 minutes to conduct indoor temperature control simulation experiments. Three sets of model rooms were placed outdoors for 6 hours, illuminated by sunlight as the light source. An optical power meter and anemometer were used to record the ambient solar irradiance, wind speed, and relative humidity for the outdoor temperature control experiments.

[0045] (5) Energy-saving simulation: Energy-Plus software was used to simulate the energy-saving performance of thermosensitive gel smart windows and flip smart windows in different regions, with ordinary glass windows and low-emissivity windows as the control group. Weather data from Anchorage, USA (high latitude), Beijing, China (mid-latitude), Hong Kong, China (subtropical), and Abu Dhabi, UAE (hot desert) were used as external boundary conditions. The internal boundary conditions for indoor heating and cooling were set to 18°C ​​(heating) and 26°C (cooling). The building model volume was 8×8×3m. 3 The installation area in the center of the four outer sides is 3×2m 2 of different windows.

[0046] Example 1

[0047] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0048] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0049] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0050] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0051] The mechanism and function of the anti-freezing ultra-wide spectrum modulation flip smart window obtained in Example 1 are shown as follows: Figure 1 As shown, the flip smart window is composed of a P(NNDEAm-MAA) solution with a thermochromic effect, a PVDF film with high and medium infrared emissivity, and a PET-ITO film with low mid-infrared emissivity. The P(NNDEAm-MAA) solution has a high solar transmittance below the phase transition temperature, and can produce strong light scattering above the phase transition temperature to resist the entry of sunlight and achieve effective modulation of sunlight. At the same time, the PVDF film and the PET-ITO film can achieve thermal modulation by regulating the mid-infrared emissivity, achieving ultra-wide spectrum modulation covering the solar spectrum and thermal spectrum. In the hot summer, the PVDF film faces the outdoors, and the flip smart window has a low solar transmittance (5.7%) and high and medium infrared emissivity (0.96). It can reduce indoor heat by blocking the entry of sunlight and promoting internal heat dissipation to achieve energy saving ( Figure 2 A). In the cold winter, the PET-ITO film faces the outside. The flip smart window has high sunlight transmittance (79.6%) and low mid-infrared light reflectance (0.43). Its excellent anti-freezing performance allows sunlight to enter the room through the flip smart window. At the same time, the outer PET-ITO film can block internal heat, achieving daily lighting and raising the indoor temperature ( Figure 2 B) The smart window can be switched between cooling and heating modes with a simple flip, achieving efficient energy saving throughout the year.

[0052] Example 2

[0053] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0054] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.011 g KPS, 0.02 g Fe2(SO4)3, and 1.46 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 90°C water bath for 1 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0055] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0056] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0057] Example 3

[0058] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0059] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.11 g KPS, 0.1 g FeCit3, and 7.3 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The reaction flask was then placed in a 50°C water bath for 6 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0060] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0061] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0062] Example 4

[0063] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0064] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0065] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.14 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0066] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0067] Example 5

[0068] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0069] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0070] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.42 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0071] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0072] Example 6

[0073] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0074] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0075] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.56 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0076] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0077] Example 7

[0078] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0079] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0080] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.70 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0081] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0082] Figure 3The solar spectrum, transmittance, and transmittance control capability of the flip smart windows of Examples 1, 4, 5, 6, and 7 with different interlayer thicknesses are shown. The results show that as the interlayer thickness increases, the visible light transmittance of the flip smart windows of Examples 1, 4, 5, 6, and 7 gradually decreases, and the corresponding near-infrared light modulation efficiencies are 59.6%, 43.4%, 59.1%, 59.0%, and 58.7%, respectively. The corresponding solar light modulation efficiencies reach 73.9%, 62.2%, 72.5%, 72.2%, and 72.0%, respectively. Overall, Example 1 with an interlayer thickness of 0.28 mm exhibits the best light management capability, with an excellent solar light modulation efficiency of 73.9%.

[0083] Example 8

[0084] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0085] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0086] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0087] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.05 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0088] Example 9

[0089] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0090] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0091] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0092] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.1 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0093] Example 10

[0094] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0095] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0096] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0097] (3) The hydrophobically modified PVDF film (PVDF film thickness is 1.0 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0098] The solar light modulation efficiencies of the flip smart windows obtained in Examples 1, 8, 9, and 10, with PVDF film thicknesses of 0.05-1.0 mm, were 73.9%, 78.1%, 75.4%, and 69.4%, respectively. The thermal modulation efficiencies (the difference in mid-infrared light emissivity between the upper and lower surfaces of the flip smart window) were 0.53, 0.20, 0.24, and 0.54, respectively. As the PVDF film thickness increased, the solar light modulation efficiency gradually decreased, while the thermal modulation efficiency gradually increased. Overall, Example 1, with a PVDF film thickness of 0.5 mm, exhibited the best combined solar light modulation efficiency (73.9%) and thermal modulation efficiency (0.53).

[0099] Example 11

[0100] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0101] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0102] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0103] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.05 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0104] Example 12

[0105] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0106] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0107] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0108] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.2 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0109] The solar modulation efficiencies of the flip smart windows obtained in Examples 1, 11, and 12, with magnetron sputtered ITO thicknesses of 0.05-0.2 mm, were 73.9%, 74.8%, and 68.2%, respectively, and the thermal modulation efficiencies were 0.53%, 0.38%, and 0.55, respectively. As the ITO thickness increased, the solar modulation efficiency gradually decreased, while the thermal modulation efficiency gradually increased. Overall, Example 1, with a magnetron sputtered ITO thickness of 0.1 mm, exhibited the best combined solar modulation efficiency (73.9%) and thermal modulation efficiency (0.53).

[0110] Comparative Example 1

[0111] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0112] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, and 0.06 g FeCl3 were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0113] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0114] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0115] The antifreeze performance test of the flip smart window (P(NNDEAm-MAA) solution) obtained in Example 1 and Comparative Example 1 is as follows: Figure 4 As shown, compared with the comparative example 1 without adding isopropyl alcohol, the freezing point of the embodiment 1 with adding isopropyl alcohol is reduced from -3.2°C to -20.6°C ( Figure 4 A). After being placed at -14°C for 3 hours, Example 1 with isopropyl alcohol added was able to maintain a high visible light transmittance (94.4%), while Comparative Example 1 without isopropyl alcohol was frozen, and its visible light transmittance dropped sharply to 0.4% ( Figure 4 B) It is confirmed that Example 1 with the addition of isopropyl alcohol has excellent anti-freezing performance and can be used in cold environments.

[0116] Comparative Example 2

[0117] A temperature-sensitive gel smart window, the preparation method of which comprises the following steps:

[0118] (1) 4.8 mL NNDEAm, 0.6 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0119] (2) The P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (the thickness of the single-layer glass was 1.0 mm) to obtain a temperature-sensitive gel smart window.

[0120] The anti-freezing ultra-wide spectrum modulation flip smart window obtained in Example 1 and the temperature-sensitive gel smart window obtained in Comparative Example 2 can reduce the indoor temperature by 24.8 and 21.0°C respectively in indoor simulation experiments. Figure 5 A, B); in outdoor experiments, the indoor temperature can be reduced by 24.2 and 22.3℃ respectively in hot summer ( Figure 6 A, B), and rise by 6.4 and 2.6℃ in cold winter ( Figure 6 C, D). Compared with the thermosensitive gel smart window, the flip smart window can further reduce the indoor temperature by 1.9°C in hot summer and increase the indoor temperature by 3.8°C in cold winter. This is attributed to the excellent thermal modulation efficiency (0.53) given to the flip smart window by the PVDF film with high and medium infrared light emissivity and the PET-ITO film with low mid-infrared light emissivity. Compared with commercially available ordinary glass windows and low-emissivity windows, energy-saving simulations were performed to calculate the HVAC energy consumption in Anchorage, USA, Beijing, China, Hong Kong, China, and Abu Dhabi, UAE. The results showed that the flip smart window has the best year-round energy-saving potential in all four regions ( Figure 7 By deducting the energy consumption of ordinary glass windows, the energy saving effect of the flip smart window in Anchorage, USA, Beijing, China and Hong Kong, China exceeds 60MJ / m 2 , the energy saving effect in Abu Dhabi, UAE reached 130MJ / m 2 , compared with the thermosensitive gel smart window, it is improved by 30-220%, showing its excellent energy-saving performance under all climate conditions ( Figure 8 ).

[0121] Comparative Example 3

[0122] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0123] (1) 4.8 mL NNDEAm, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0124] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0125] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0126] The phase change temperature tests of Comparative Example 3 and Example 1 correspond to Figure 9 (A) PNNDEAm, (B) P(NNDEAm-MAA). Compared to the PNNDEAm system obtained by NNDEAm self-polymerization (phase transition temperature: 38.2°C), the P(NNDEAm-MAA) solution prepared by copolymerization of NNDEAm and MAA exhibits a more suitable transition temperature (26.5°C), closer to the human body's indoor comfort temperature in summer, which is conducive to the practical application of flip smart windows in the field of building energy conservation.

[0127] Comparative Example 4

[0128] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0129] (1) 4.8 mL NNDEAm, 0.3 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The reaction flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0130] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0131] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0132] Comparative Example 5

[0133] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0134] (1) 4.8 mL NNDEAm, 1.5 mL MAA, 0.057 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added sequentially to a 40 mL reaction flask containing 20 mL deionized water and stirred thoroughly. The reaction flask was then placed in a 70°C water bath for 3 h. After the reaction was complete, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-MAA) solution.

[0135] (2) P(NNDEAm-MAA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0136] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the laminated glass to obtain a flip smart window.

[0137] Comparative Example 4, Example 1 and Comparative Example 5 correspond to Figure 10 The molar ratio of NNDEAm to MAA is 10:1 (A), 5:1 (B), and 2:1 (C). Figure 10 As can be seen from the figure, only the P(NNDEAm-MAA) solution with a 5:1 molar ratio of NNDEAm to MAA meets the requirements for use. The sample with a 10:1 molar ratio of NNDEAm to MAA has a dense structure due to low electrostatic repulsion between internal chains, thus affecting light transmission. The sample with a 2:1 molar ratio of NNDEAm to MAA has an excessively high MAA content, which leads to a sharp drop in pH in the solution, accompanied by a significant strengthening of molecular hydrogen bonds within the polymer, ultimately resulting in a transition temperature below room temperature.

[0138] Comparative Example 6

[0139] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0140] (1) 4.8 mL NNDEAm, 1.5 mL 3-butenoic acid (3-BA) (the molar ratio of NNDEAm to 3-BA is 2:1; when the molar ratio is 5:1, it will gel and will not have phase change ability), 0.07 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added to a 40 mL reaction bottle containing 20 mL deionized water and stirred thoroughly. The reaction bottle was then placed in a 70°C water bath and reacted for 3 h. After the reaction was completed, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-BA) solution.

[0141] (2) P(NNDEAm-BA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0142] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the glass to obtain a flip smart window.

[0143] Comparative Example 7

[0144] A freeze-resistant ultra-wide spectrum modulated flip smart window, the preparation method of which comprises the following steps:

[0145] (1) 4.8 mL NNDEAm, 1.8 mL 4-pentenoic acid (4-PA) (the molar ratio of NNDEAm to 4-PA is 2:1; when the molar ratio is 5:1, it will gel and will not have phase change ability), 0.07 g KPS, 0.06 g FeCl3, and 4.4 mL IPA were added to a 40 mL reaction bottle containing 20 mL deionized water and stirred thoroughly. The reaction bottle was then placed in a 70°C water bath and reacted for 3 h. After the reaction was completed, the solution was cooled to room temperature, and the supernatant was the prepared P(NNDEAm-PA) solution.

[0146] (2) P(NNDEAm-PA) solution was injected into insulating glass with an interlayer thickness of 0.28 mm (single-layer glass thickness of 1.0 mm) to form laminated glass;

[0147] (3) The hydrophobically modified PVDF film (PVDF film thickness is 0.5 mm) and PET-ITO film (PET thickness is 0.5 mm, ITO thickness is 0.1 mm) are attached to the upper and lower surfaces of the glass to obtain a flip smart window.

[0148] The UV-visible-near infrared transmission spectra of the flip smart window prepared by copolymerization of NNDEAm and MAA, 3-BA, and 4-PA obtained in Example 1, Comparative Example 6, and Comparative Example 7 are as follows: Figure 11 As shown in the figure, the solar transmittances of Example 1, Comparative Example 6, and Comparative Example 7 before the phase change were 79.6%, 63.8%, and 52.5%, respectively. After the phase change, the solar transmittances were 5.7%, 7.0%, and 8.2%, respectively. The solar modulation efficiencies were 73.9%, 56.8%, and 44.3%, respectively. Example 1 is the flip smart window with the best light management capability.

Claims

1. A flip smart window with anti-freezing ultra-wide spectrum modulation, characterized in that: The flip smart window consists of a laminated glass formed by encapsulating a polymer solution formed by copolymerization of N,N-diethyl-2-acrylamide (NNDEAm) monomer and methacrylic acid (MAA) monomer in insulating glass, as well as a polyethylene terephthalate (PET)-indium tin oxide (Indium Tin Oxide) (PET-ITO) film and a polyvinylidene fluoride (PVDF) film attached to the upper and lower surfaces of the laminated glass, respectively.

2. A method for preparing the flip smart window according to claim 1, characterized in that: The polymer solution obtained by copolymerizing NNDEAm monomer and MAA monomer through reverse atom transfer radical polymerization is injected into the insulating glass for encapsulation to form laminated glass. PET-ITO film and PVDF film are then attached to the upper and lower surfaces of the laminated glass respectively to construct an anti-freeze and ultra-wide spectrum modulated flip smart window.

3. The preparation method according to claim 2, characterized in that The specific steps are as follows: (1) dissolving NNDEAm monomer, MAA monomer, potassium persulfate (KPS), iron salt, and isopropyl alcohol (IPA) in deionized water and heating to obtain a poly(N,N-diethyl-2-acrylamide-co-methacrylic acid) (P(NNDEAm-MAA)) solution; (2) Injecting the P(NNDEAm-MAA) solution into insulating glass to form laminated glass; (3) The PVDF film is first hydrophobically modified, and then the modified PVDF film and PET-ITO film are attached to the upper and lower surfaces of the laminated glass respectively to obtain an anti-freezing ultra-wide spectrum modulation flip smart window.

4. The preparation method according to claim 3, characterized in that In step (1), the iron salt is ferric chloride, ferric sulfate or ferric citrate, the molar ratio of NNDEAm monomer to MAA monomer is 10:1-2:1; the total monomer concentration of NNDEAm monomer and MAA monomer in deionized water is 1.9-2.6 mol / L, KPS is 0.1-1.0 mol% of the total content of NNDEAm monomer and MAA monomer, the iron salt concentration is 0.01-0.05 g / 10 mL, and the IPA concentration is 0.01-0.05 mol / 10 mL; the heating temperature is 50-90° C., and the heating time is 1-6 h.

5. The preparation method according to claim 4, characterized in that In step (1), the iron salt is ferric chloride, the molar ratio of NNDEAm monomer and MAA monomer is 5:1; the total monomer concentration of NNDEAm monomer and MAA monomer in deionized water is 2.1 mol / L, KPS is 0.5 mol% of the total content of NNDEAm monomer and MAA monomer, the iron salt concentration is 0.03 g / 10 mL, and the IPA concentration is 0.03 mol / 10 mL; the heating temperature is 70° C. and the time is 3 h.

6. The preparation method according to claim 1, characterized in that The thickness of single-layer glass of insulating glass is 1.0mm, and the thickness of interlayer is 0.14-0.70mm.

7. The preparation method according to claim 6, characterized in that The interlayer thickness of insulating glass is 0.28mm.

8. The preparation method according to claim 1, characterized in that The thickness of the PVDF film is 0.05-1.0 mm, the thickness of the PET in the PET-ITO film is 0.05-1.0 mm, and the thickness of the surface ITO is 0.05-0.2 mm.

9. The preparation method according to claim 8, characterized in that The thickness of the PVDF film is 0.5 mm, the thickness of the PET in the PET-ITO film is 0.5 mm, and the thickness of the surface ITO is 0.1 mm.

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