Thermally induced phase change heat insulation intelligent material and preparation method and application thereof

Abstract

The invention discloses a thermally induced phase change heat insulation intelligent material and a preparation method and application thereof, and belongs to the technical field of building energy-saving intelligent windows. The preparation method comprises the following steps: doping NaYF4: Yb < 3 + > / Er < 3 + > or NaYF4: Yb < 3 + > / Tm < 3 + > into an N-isopropylacrylamide precursor containing a photoinitiator I2959, and finally constructing a reversible thermochromic interlayer between quartz glass substrates by using the precursor by adopting a polymerization process, thereby preparing the intelligent glass with photo-thermal synergistic response. The intelligent glass shows high visible light transmittance under the condition of room temperature, and meanwhile, shows quick reversible response to temperature change within 28-35 DEG C. Through the synergistic effect of the introduced photoinitiator I2959 and NaYF4: Yb < 3 + > / Er < 3 + > or NaYF4: Yb < 3 + > / Tm < 3 + >, high absorption is achieved in the ultraviolet band of 200-400 nm, a characteristic absorption peak is formed in the near-infrared band, the photothermal conversion efficiency is improved to 68%, and the multi-band photothermal barrier is effectively constructed. According to the intelligent glass, precise regulation and control of a response temperature threshold at 28-32 DEG C are achieved by regulating and controlling the proportion of the nanocrystalline, high light transmittance is maintained in a comfortable temperature range of a human body, and response characteristics can be flexibly adjusted according to personalized temperature control requirements.

Description

Technical Field

[0001] The present invention relates to a thermally induced phase change heat-insulating intelligent material and a preparation method and application thereof, belonging to the technical field of building energy-saving intelligent windows. Background Art

[0002] Driven by global population growth and economic development, buildings account for 40% of global energy consumption. Building windows, the weakest link in thermal performance within the building envelope, contribute approximately 30% of building energy losses. Thermochromic smart window technology achieves passive energy conservation by dynamically controlling the solar spectrum through temperature-driven modulation. Its significant advantages, including compact structure, low manufacturing cost, and passive actuation, have made it a research hotspot in the field of building energy conservation. Conventional inorganic thermochromic materials based on vanadium dioxide (VO2) can achieve significant changes in infrared transmittance (ΔTIR ≈ 45%) near a phase transition point of 68°C. However, this phase transition temperature is significantly higher than the ambient temperature range of human habitation (18-28°C), significantly limiting their practical engineering applications. In contrast, thermosensitive hydrogel materials, with their full-spectrum control capabilities, high transparency, and low cost, have become a research focus. N-isopropylacrylamide (NIPAM)-based hydrogels have attracted considerable attention due to their critical solution temperature (LCST ≈ 32°C) near room temperature and rapid phase transition rate. It is worth noting that the material's light absorption efficiency in the 200-400nm ultraviolet band and the 1500-2500nm near-infrared band still has room for improvement (the current ultraviolet absorption rate is approximately 80% and the near-infrared absorption rate is approximately 2%), which limits its effectiveness in regulating indoor thermal comfort under continuous high-temperature radiation. In addition, the phase transition temperature threshold of 32°C is still slightly higher than the human thermal comfort range (summer comfort temperature is 19-24°C), requiring material modification to achieve precise control of the response temperature (continuously adjustable from 28-32°C) to meet the application needs of different climate zones. Summary of the Invention

[0003] In order to overcome the problems in the background technology, the purpose of the present invention is to provide a smart material with thermo-induced phase change insulation and its preparation method and application.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for preparing a thermo-induced phase change heat-insulating smart material comprises the following steps:

[0006] (1) adding upconversion nanoparticles to a hydrochloric acid solution, washing with water, and then dispersing in water to form a nanoparticle dispersion; the upconversion nanoparticles are NaYF4:Yb 3 + / Er 3+ or NaYF4:Yb 3 + / Tm 3+ ;

[0007] (2) adding N-isopropylacrylamide monomer and photoinitiator I2959 to the nanoparticle dispersion prepared in step (1) and ultrasonically dispersing the mixture to form a precursor solution;

[0008] (3) The precursor solution is irradiated under ultraviolet light for the first time, then transferred to a cold storage environment for standing, and then irradiated under ultraviolet light for the second time, and finally refrigerated to form a thermoinduced phase change insulation smart material.

[0009] Preferably, the NaYF4:Yb 3 + / Er 3+ The molar ratio of Y, Yb, and Er in the upconversion nanoparticles is Y:Yb:Er=60:38:2; the NaYF4:Yb 3 + / Tm 3+ The molar ratio of Y, Yb and Tm in the upconversion nanoparticles is Y:Yb:Tm=60:39:1.

[0010] Preferably, the total weight percentage of the upconversion nanoparticles in the precursor solution is 0.3-1.0 wt %.

[0011] If the upconversion nanoparticle content is less than 0.3wt%, the thermal insulation effect of the thermochromic smart glass will not be very effective. If the upconversion nanoparticle content exceeds 1.5wt%, the hydrogel structure will be destroyed, and the resulting sample will no longer have the viscous texture expected of a hydrogel, resulting in poor light transmittance and thermal insulation.

[0012] Preferably, the mass ratio of the N-isopropylacrylamide monomer to the photoinitiator I2959 is 5:0.25.

[0013] Preferably, the mass ratio of the N-isopropylacrylamide monomer, the photoinitiator I2959, and the upconversion nanoparticles is 5:0.25:0.308-0.931.

[0014] Preferably, the ultraviolet light has a wavelength of 365 nm and an intensity of 50-80 mW / cm 2 ; The first irradiation time is 1-2 minutes; the second irradiation time is 10-15 minutes.

[0015] The present invention adopts two ultraviolet irradiation and cold storage static process, which can ensure that a stable cross-linked structure is formed inside the material, ensuring heat insulation effect and high light transmittance at room temperature.

[0016] Preferably, the temperature of the refrigerated environment is 4-5°C and the time is 30 minutes.

[0017] The present invention also claims protection for the thermally induced phase change thermal insulation smart material prepared by the preparation method of the thermally induced phase change thermal insulation smart material, wherein the moisture content of the thermally induced phase change thermal insulation smart material is 91%.

[0018] The present invention also claims the use of the thermochromic smart glass in a smart glass structure. The smart glass is formed by vacuum-injecting the material between quartz glass substrates to form a sandwich structure. The edges are sealed with epoxy resin glue, and precise pressure control ensures uniform distribution. The thickness of the smart material in the glass is 1-3 mm.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention is doped with NaYF4:Yb 3 + / Er 3+ or NaYF4:Yb 3 + / Tm 3+ The thermo-induced phase change insulation smart glass constructed by dual-mode rare earth and in-situ photopolymerization process achieves 80.4% visible light transmittance at room temperature and exhibits rapid reversible response to temperature changes within the range of 25-35°C. 3 + / Er 3+ or NaYF4:Yb 3 + / Tm 3+ The synergistic effect of the dual-mode rare earth doping system constructs an intelligent optical system with photothermal synergistic response characteristics while maintaining high transmittance.

[0021] (2) Compared with traditional VO2-based inorganic thermochromic materials (phase transition temperature 68°C), this invention successfully adjusts the critical solution temperature (LCST) of NIP AM hydrogel from 32°C to the range of 28-32°C by regulating the nanocrystal doping ratio and process control, and maintains high light transmittance within the human body comfortable temperature range of 25-30°C. Through the dual light and heat response mechanism, this smart glass system achieves dynamic adjustment of solar radiation reflectivity from 30-75%, meeting the personalized temperature control needs of different climate zones.

[0022] (3) The smart glass of the present invention achieves an absorption efficiency of 98.7% in the 200-400nm ultraviolet band and forms a characteristic absorption peak in the 1500-2000nm near-infrared band, increasing the light-to-heat conversion efficiency to 68%. By constructing a multi-band light-to-heat barrier, the smart glass can maintain a stable indoor temperature under continuous high-temperature radiation, reducing the air conditioning load in summer by 37%, significantly improving the building's energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is the preparation flow chart of thermochromic smart glass.

[0024] Figure 2 NaYF4:Yb prepared in Example 1-2 3 + / Er 3+ Nanoparticles, NaYF4:Yb 3 + / Tm 3+ XRD patterns of nanoparticles and standard cards.

[0025] Figure 3 NaYF4:Yb prepared in Example 1-2 3 + / Er 3+ Nanoparticles, NaYF4:Yb 3 + / Tm 3+ TEM images of nanoparticles, the left image is NaYF4:Yb 3 + / Er 3+ TEM images of nanoparticles, the right image is NaYF4:Yb 3 + / Tm 3+ TEM image of nanoparticles.

[0026] Figure 4 The optical images of the thermochromic smart glass prepared in Comparative Example 1 at different temperatures show that the color change temperature is around 31°C.

[0027] Figure 5 The FTIR images of the thermochromic smart glass prepared in Comparative Example 1 before (26°C) and after (35°C) the phase transition show that at 26°C, hydrogen bonds are less obvious and are formed between N-isopropylacrylamide monomers and water molecules. After the phase transition, the link between N and H becomes stronger, and the N-isopropylacrylamide monomer curls up, isolating it from external water molecules and achieving an opaque state.

[0028] Figure 6 The figures are actual pictures of the smart glass prepared in Examples 1 and 2 and their color changes at a temperature of 28°C-33°C. (a) is a actual picture of the smart glass prepared in Example 1, (b) is the color changes of the smart glass prepared in Example 1 at different temperatures, (c) is a actual picture of the smart glass prepared in Example 2, and (d) is the color changes of the smart glass prepared in Example 2 at different temperatures.

[0029] Figure 7 Graph showing the transmittance of the thermochromic smart glasses prepared in Examples 1 and 2 and the glass prepared in Comparative Example 1 (without the addition of thermochromic phase-change insulation smart materials) in the range of 200 nm to 2000 nm.

[0030] Figure 8The transmittance of the thermochromic smart glass prepared in Example 1 at different temperatures.

[0031] Figure 9 This is a comparison chart of the internal temperature changes over ten minutes under xenon lamp illumination for tin foil boxes equipped with air-sandwich windows, ordinary thermochromic glass, and the thermochromic smart glass prepared in Example 1 of the present invention. The left figure is a diagram of the test system, and the right figure is a comparison chart of the internal temperature changes over ten minutes for tin foil boxes equipped with air-sandwich windows, ordinary thermochromic glass, and the thermochromic smart glass prepared in Example 1.

[0032] Figure 10 This is the reversible response diagram of the thermochromic smart glass prepared in Example 1 within the temperature range of 25-35°C. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0034] Example 1

[0035] A method for preparing a thermally induced phase change heat-insulating smart material comprises the following steps:

[0036] (1) Synthesis of NaYF4:Yb by chemical precipitation method 3 + / Er 3+ In the specific experimental steps for upconversion nanoparticles, a total of 1 mmol of YbCl₃ and ErCl₃ was added to a mixture of oleic acid (7 mL) and octadecene (12 mL) (molar ratio: YbCl₃:ErCl₃ = 38:2) in a 50 mL flask at room temperature. The mixture was reacted at 150°C for 45 minutes to form a rare earth-oleate precursor. The resulting solution was cooled to 50°C and then mixed with a methanol solution (8.6 mL) containing ammonium fluoride (1.6 mmol) and sodium hydroxide (1 mmol). The reaction solution was stirred at 55°C for 60 minutes. The temperature was then raised to 100°C to remove the methanol. The resulting solution was then heated to 305°C and reacted for 1 hour. The product was precipitated with ethanol, collected by centrifugation at 8000 rpm for 5 minutes, washed with ethanol, and finally dispersed in 10 mL of cyclohexane to produce nanoparticles. The nanoparticles were surface-modified using a 0.1 M hydrochloric acid solution, washed repeatedly with deionized water, and then dispersed in ultrapure water to form a stable dispersion with a concentration of 10 mg / mL, which was colorless and transparent.

[0037] (2) N-isopropylacrylamide monomer, photoinitiator I2959 and NaYF4:Yb 3 + / Er 3+Weigh according to the mass ratio of 5:0.25:0.931, add it to the nanoparticle dispersion prepared in step (1), and ultrasonically disperse it in a water bath at 20°C for 30 minutes to form a uniform and stable precursor solution. The precursor solution contains NaYF4:Yb 3 + / Er 3+ The concentration is 1.0wt%.

[0038] (3) Place the precursor solution in a culture dish and expose it to 365 nm ultraviolet light (intensity 50 mW / cm 2 ) irradiated for 1 minute to initiate free radical polymerization reaction, transferred to a 4°C refrigerated environment and allowed to stand for 30 minutes, then UV irradiated again for 10 minutes, and then transferred to a 4°C refrigerated environment and allowed to stand for 30 minutes, finally forming a smart material with thermoinduced phase change insulation.

[0039] according to Figure 1 It can be seen that a thermochromic smart glass includes the following steps: a thermochromic phase-change insulating smart material is used as an intelligent control layer, vacuum-injected between quartz glass substrates, sealed at the edges with epoxy resin glue, and encapsulated between quartz glass substrates with a side length of 100mm×100mm and a thickness of 1mm to form an intelligent sandwich structure with a thickness of 2mm. Precise pressure control is used to ensure uniform distribution to form a complete thermochromic smart glass.

[0040] Example 2

[0041] A method for preparing a thermally induced phase change heat-insulating smart material comprises the following steps:

[0042] (1) Synthesis of NaYF4:Yb by chemical precipitation method 3 + / Tm 3+ In the experimental procedure for upconversion nanoparticles, a total of 1 mmol of YbCl₃ and TmCl₃ was added to a mixture of oleic acid (7 mL) and octadecene (12 mL) (molar ratio: YbCl₃:TmCl₃ = 39:1) in a 50 mL flask at room temperature. The mixture was reacted at 150°C for 45 minutes to form a rare earth-oleate precursor. The resulting solution was cooled to 50°C and then mixed with a methanol solution (8.6 mL) containing ammonium fluoride (1.6 mmol) and sodium hydroxide (1 mmol). The reaction solution was stirred at 55°C for 60 minutes. The temperature was then raised to 100°C to remove the methanol. The resulting solution was then heated to 305°C and reacted for 1 hour. The product was precipitated with ethanol, collected by centrifugation at 8000 rpm for 5 minutes, washed with ethanol, and finally dispersed in 10 mL of cyclohexane. The nanoparticles were surface-modified using a 0.1 M hydrochloric acid solution, washed repeatedly with deionized water, and then dispersed in ultrapure water to form a stable dispersion with a concentration of 10 mg / mL, which was colorless and transparent.

[0043] (2) N-isopropylacrylamide monomer, photoinitiator I2959NaYF4:Yb 3 + / Tm 3+ Weigh according to the mass ratio of 5:0.25:0.308, add it to the nanoparticle dispersion prepared in step (1), and ultrasonically disperse it in a water bath at 20°C for 30 minutes to form a uniform and stable precursor solution. 3 + / Tm 3+ The concentration of nanocrystals was 0.3 wt%.

[0044] (3) Place the precursor solution in a culture dish and expose it to 365nm ultraviolet light (intensity 80mW / cm 2 ) irradiation initiated a free radical polymerization reaction. When the system showed obvious photochromic changes, it was transferred to a 4°C refrigerated environment and allowed to stand for 20 minutes. Then, it was irradiated with UV light for 15 minutes and then transferred to a 4°C refrigerated environment and allowed to stand for 30 minutes. Finally, a smart material with thermoinduced phase change insulation was formed.

[0045] A thermochromic smart glass comprises the following steps: vacuum-injecting a thermochromic phase-change insulating smart material as an intelligent control layer between quartz glass substrates, sealing the edges with epoxy resin glue, and encapsulating the material between quartz glass substrates with a side length of 100 mm × 100 mm and a thickness of 1 mm to form an intelligent sandwich structure with a thickness of 2 mm. Precise pressure control is used to ensure uniform distribution of the material to form a complete thermochromic smart glass.

[0046] Comparative Example 1

[0047] A method for preparing a thermally induced phase change heat-insulating smart material comprises the following steps:

[0048] (1) N-isopropylacrylamide monomer and photoinitiator I2959 were weighed in a mass ratio of 5:0.25 and ultrasonically dispersed in a water bath at 20°C for 30 minutes to form a uniform and stable precursor solution.

[0049] (2) Place the precursor solution in a culture dish and expose it to 365 nm ultraviolet light (intensity 50 mW / cm 2 ) irradiation initiated a free radical polymerization reaction. When the system showed obvious photochromic changes, it was transferred to a 4°C refrigerated environment and allowed to stand for 30 minutes. Then, it was irradiated with UV light for another 20 minutes, ultimately forming a smart material with thermoinduced phase change insulation.

[0050] A thermochromic smart glass comprises the following steps: vacuum-injecting a thermochromic phase-change insulating smart material as an intelligent control layer between quartz glass substrates, sealing the edges with epoxy resin glue, and encapsulating the material between quartz glass substrates with a side length of 100 mm × 100 mm and a thickness of 1 mm to form a 2 mm thick intelligent sandwich structure. Precise pressure control is used to ensure uniform distribution of the material, thereby forming a complete thermochromic smart glass.

[0051] Comparative Example 2

[0052] A method for preparing a thermally induced phase change heat-insulating smart material comprises the following steps:

[0053] (1) Synthesis of NaYF4:Yb by chemical precipitation method 3 + / Er 3+ In the specific experimental steps for upconversion nanoparticles, a total of 1 mmol of YbCl₃ and ErCl₃ was added to a mixture of oleic acid (7 mL) and octadecene (12 mL) (molar ratio: YbCl₃:ErCl₃ = 38:2) in a 50 mL flask at room temperature. The mixture was reacted at 150°C for 45 minutes to form a rare earth-oleate precursor. The resulting solution was cooled to 50°C and then mixed with a methanol solution (8.6 mL) containing ammonium fluoride (1.6 mmol) and sodium hydroxide (1 mmol). The reaction solution was stirred at 55°C for 60 minutes. The temperature was then raised to 100°C to remove the methanol. The resulting solution was then heated to 305°C and reacted for 1 hour. The product was precipitated with ethanol, collected by centrifugation at 8000 rpm for 5 minutes, washed with ethanol, and finally dispersed in 10 mL of cyclohexane to obtain a nanoparticle dispersion.

[0054] (2) N-isopropylacrylamide monomer, photoinitiator I2959 and NaYF4:Yb 3 + / Er 3+ Weigh according to the mass ratio of 5:0.25:0.931, add it to the nanoparticle dispersion prepared in step (1), and ultrasonically disperse it in a water bath for 30 minutes to form a uniform and stable precursor solution. 3 + / Er 3+ The concentration of nanocrystals was 1.0 wt%.

[0055] (3) Place the precursor solution in a culture dish and expose it to 365 nm ultraviolet light (intensity 50 mW / cm 2 ) irradiation initiated a free radical polymerization reaction. When the system showed obvious photochromic changes, it was transferred to a 4°C refrigerated environment and allowed to stand for 30 minutes. Then, it was irradiated with UV light for another 20 minutes, ultimately forming a smart material with thermoinduced phase change insulation.

[0056] In this comparative example, after the upconversion nanoparticles that have not been treated with hydrochloric acid are added to the precursor solution, the solution as a whole appears as a white turbid liquid. After irradiation with ultraviolet light, white lumps appear, but the overall appearance is still white without any discoloration. In addition, the solution is not viscous and does not have the characteristics of a hydrogel material.

[0057] Effect Example 1

[0058] according to Figure 2 It can be seen that since the diffraction peaks of the samples prepared in Example 1-2 match the standard PDF card 16-0334, it is shown that the synthesized nanoparticles are pure phase. Therefore, the NaYF4:Yb prepared in Example 1-2 and Comparative Example 1-2 are 3 + / Er 3+ Nanoparticles and NaYF4:Yb 3 + / Tm 3+ Nanoparticles were successfully prepared.

[0059] according to Figure 3 It can be seen that NaYF4:Yb 3 + / Er 3+ The particle diameter of the material is about 70nm. 3 + / Tm 3+ The diameter of the material particles is about 50nm, and Figure 3 It can be seen that NaYF4:Yb 3 + / Er 3+ with NaYF4:Yb 3 + / Tm 3+ The nanoparticles have uniform particle size distribution, good crystallinity, and good dispersibility.

[0060] Effect Example 2

[0061] The glasses prepared in Example 1-2 and Comparative Example 1-2 were subjected to optical image analysis at different temperatures to obtain phase transition temperatures, as shown in Table 1.

[0062] Table 1

[0063] Phase transition temperature / ℃ Example 1 29 Example 2 29 Comparative Example 1 30 Comparative Example 2 No phase change

[0064] Figure 4 The optical images of the smart glass prepared in Comparative Example 1 at different temperatures (35°C, 34°C, 33°C, 32°C, 31°C, 30°C, 29°C, and 20°C) show that the phase transition temperature is 31°C, and the transmittance of visible light is low at high temperatures after the phase transition. As the temperature decreases, the glass gradually becomes transparent, and the image behind it can be clearly seen.

[0065] Figure 5The FTIR images of the thermo-induced phase change insulation smart material prepared in Example 1 before and after the phase change show that after the temperature rises, characteristic absorption peaks of CH appear at 1273nm and 1284nm, and the characteristic peak of OH at 3400nm shifts to the left, proving that high temperature causes the thermo-induced phase change insulation smart material to undergo a phase change, resulting in curling of the amide group and becoming opaque.

[0066] Figure 6 The actual pictures of the smart glass prepared in Examples 1 and 2 at different temperatures, as well as its color change at different temperatures, show that at room temperature, the glass is transparent and has a good transmittance, but after the phase change, it becomes white and completely blocks visible light. Figure 8 Under different temperature conditions, the transmittance of the thermochromic smart glass of Example 1 shows a downward trend as the temperature increases, proving that it can effectively block visible light after the phase change and maintain good absorption of ultraviolet light and near-infrared light.

[0067] Figure 7 The transmittance values for the thermochromic smart glasses prepared in Examples 1-2 and the control group within the 200nm-2000nm range are shown. Compared to the control group, the thermochromic smart glasses prepared in Examples 1-2 exhibit superior absorption of ultraviolet and near-infrared light, maintaining a high transmittance within the visible light range (380-780nm). Furthermore, compared to the thermochromic smart glass in Comparative Example 1, the thermochromic phase-change insulation smart materials prepared in Examples 1 and 2 of the present invention significantly improve the transmittance of the glass within this visible light range.

[0068] Effect Example 3

[0069] Under the irradiation of xenon lamp, the temperature changes of the tin foil boxes with air sandwich windows, ordinary thermochromic glass, and thermochromic smart glass prepared by the present invention after ten minutes are shown in Table 2 and Figure 9 .

[0070] Table 2

[0071] Temperature inside the tin foil box after 10 minutes / ℃ Example 1 25.4 Example 2 25.2 Comparative Example 1 27 Comparative Example 2 27.4 Air clip window 31.7

[0072] according to Figure 9 It can be seen that although the single thermochromic glass (Comparative Example 1) has a certain heat insulation ability compared to the air sandwich window (Air), its heat insulation and temperature insulation effect is not as good as the thermochromic smart glass prepared in Examples 1 and 2 of the present invention.

[0073] Figure 10The prepared smart glass exhibits a rapid and reversible response to temperature changes within the 25-35°C range. Although the smart glass's response from high to low temperatures during cooling is less pronounced than from low to high, resulting in variations in the phase transition temperature during heating and cooling, further heating restores the phase transition temperature to 29°C, demonstrating the excellent stability of the smart glass.

[0074] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a thermo-induced phase change insulation smart material, characterized by: The steps include: (1) adding upconversion nanoparticles to a hydrochloric acid solution, washing with water, and then dispersing in water to form a nanoparticle dispersion; the upconversion nanoparticles are NaYF4:Yb 3 + / Er 3 + or NaYF4:Yb 3 + / Tm 3 +; (2) adding N-isopropylacrylamide monomer and photoinitiator I2959 to the nanoparticle dispersion prepared in step (1) and ultrasonically dispersing the mixture to form a precursor solution; (3) The precursor solution is irradiated under ultraviolet light for the first time, then transferred to a cold storage environment for standing, and then irradiated under ultraviolet light for the second time, and finally refrigerated to form a thermoinduced phase change insulation smart material.

2. The method for preparing the thermo-induced phase change insulation smart material according to claim 1, characterized in that: The NaYF4:Yb 3 + / Er 3 + The molar ratio of Y, Yb, and Er in the upconversion nanoparticles is Y:Yb:Er=60:38:2; the NaYF4:Yb 3 + / Tm 3 +The molar ratio of Y, Yb and Tm in the upconversion nanoparticles is Y:Yb:Tm=60:39:

1.

3. The method for preparing the thermo-induced phase change insulation smart material according to claim 1, characterized in that: The weight percentage of the upconversion nanoparticles in the precursor solution is 0.3-1.0 wt %.

4. The method for preparing the thermo-induced phase change insulation smart material according to claim 1, characterized in that: The mass ratio of the N-isopropylacrylamide monomer to the photoinitiator I2959 is 5:0.

25.

5. The method for preparing the thermo-induced phase change insulation smart material according to claim 1, characterized in that: The ultraviolet light has a wavelength of 365 nm and an intensity of 50-80 mW / cm 2 ; The first irradiation time is 1-2 minutes; the second irradiation time is 10-15 minutes.

6. The method for preparing the thermo-induced phase change insulation smart material according to claim 1, characterized in that: The temperature of the refrigerated environment is 4-6°C and the time is 20-30 minutes.

7. Thermotropic phase-change thermal insulation smart material prepared according to the method for preparing the thermotropic phase-change thermal insulation smart material according to any one of claims 1 to 6.

8. Use of the thermochromic phase-change heat-insulating smart material according to claim 7 in thermochromic smart glass.

9. The application according to claim 8, characterized in that: Thermochromic smart glass is formed by vacuum-injecting thermochromic phase-change insulation smart materials between quartz glass substrates to form a sandwich structure, and then the edges of the quartz glass substrates are sealed with epoxy resin glue.

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