Temperature-responsive polymer and smart window comprising the same

Abstract

The application provides a temperature-responsive polymer, which comprises a repeating unit shown in the following formula I; the formula I is a polymerization product of two monomers of 2-(2-methoxyethoxy)methyl acrylate (MEO2MA) and 2-(2-hydroxyethoxy)ethyl methacrylate (HEO2MA); in the formula I, x is 1-100; y is 20-500. The smart window prepared from the temperature-responsive polymer has the characteristics of wide temperature response range, high light transmittance, excellent heat insulation performance and long-term stability, and can be widely applied to light-collecting and temperature-controlling parts in various scenes such as residential buildings, commercial buildings and public facilities, and has significant energy-saving value and market prospect.

Description

Technical Field

[0001] This invention relates to the field of smart materials, and more specifically to a temperature-responsive polymer and a smart window containing the same. Background Technology

[0002] Building energy consumption accounts for approximately 40% of global energy consumption, with about 60% of that originating from energy exchange between the interior and exterior through windows. As a key component for light and heat exchange between buildings and the external environment, windows' shading performance directly impacts indoor comfort and overall building energy consumption. Ideal shading technology should possess dynamic response capabilities: effectively blocking solar radiation in hot environments to reduce cooling load, and allowing natural light to enter in cold or well-lit conditions to reduce artificial lighting energy consumption, thereby achieving a dynamic balance between energy conservation and natural lighting.

[0003] Dynamic shading windows based on smart materials mainly include three categories: electrochromic, photochromic, and thermochromic. Among them, thermochromic materials have unique application advantages in the field of smart windows because they do not require external energy input and can actively respond to changes in ambient temperature.

[0004] Traditional thermochromic materials include liquid crystals, perovskites, ionic liquid gels, and hydrogels. These materials have been attempted for application in the visible and near-infrared (NIR) ranges of solar energy modulation. However, existing technologies still have many shortcomings that limit their industrialization: for example, the poly(N-isopropylacrylamide) hydrogel system, based on which smart windows can only adjust light transmission in a single way, has limited solar energy modulation capabilities, and has a fixed response temperature, making it unsuitable for different climatic regions. Vanadium oxide (VO2) inorganic material system: phase transition temperature is 68℃, which does not match the comfortable indoor temperature range of buildings, and the thin film preparation requires precision equipment such as magnetron sputtering, which is complex and has a light transmittance of less than 80%.

[0005] Therefore, developing a novel temperature-responsive material with adjustable response temperature and a significant difference in light transmittance before and after phase change is of great significance for promoting the industrial application of smart windows and improving building energy efficiency. Summary of the Invention

[0006] In view of this, the present invention provides a temperature-responsive polymer, which is particularly suitable for the preparation of smart glass windows, and can undergo a reversible phase transition within the comfortable temperature range of a building's interior: when the ambient temperature is lower than the polymer's response temperature, the smart window maintains high light transmittance to ensure good lighting; when the ambient temperature is higher than the polymer's response temperature, the smart window quickly transforms into an opaque state to block solar radiation, thereby providing a universal active smart photothermal regulation solution for different climate zones.

[0007] In a first aspect, the present invention provides a temperature-responsive polymer comprising repeating units as shown in Formula I: Formula I; Formula I is a polymerization product of two monomers: 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and 2-(2-hydroxyethoxy)ethyl methacrylate (HEO2MA). In Formula I, x is the average degree of polymerization of 2-(2-hydroxyethoxy)ethyl methacrylate (HEO2MA), and y is the average degree of polymerization of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA). In Equation I, x is 1-100; y is 20-500.

[0008] Preferably, in Formula I, x is 1-100 and y is 20-500; or more preferably, x is 2-30 and y is 30-100; or most preferably, x is 2-20 and y is 50-80.

[0009] In some instances, x can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, or 100; y can be, for example, 20, 30, 40, 50, 55, 60, 65, 70, 75, 80, 90, 100, 120, 150, 180, 200, 250, 300, 350, 400, 450, or 500.

[0010] Preferably, in Formula I, x:y is 1:1 to 1:100, or 1:3 to 1:50, or 1:4 to 1:30, preferably 1:5 to 1:20, and more preferably 1:7 to 1:19. For example, x:y can be 1:3, 1:5, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:25, 1:30, 1:40, or 1:50.

[0011] Preferably, the number-average molecular weight of the temperature-responsive polymer is 3,000-100,000, more preferably 4,000-50,000, or 5,000-20,000, and even more preferably 8,000-15,000. For example, the number-average molecular weight of the temperature-responsive polymer can be 3,000, 5,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 18,000, 20,000, 30,000, 50,000, 80,000, or 100,000. The number-average molecular weight is measured by GPC.

[0012] The temperature-responsive polymer of the present invention can be prepared by any free radical polymerization method in the art, such as free radical polymerization or living free radical polymerization (e.g., ATRP, RAFT, NMP, etc.).

[0013] The temperature-responsive polymer of the present invention can be prepared by any free radical polymerization method in the art. For example, bulk polymerization, solution polymerization, emulsion polymerization, dispersion polymerization, etc.

[0014] The following are typical examples of preparation processes: 1. Free radical polymerization Using 2-(2-hydroxyethoxy)ethyl methacrylate (HEO2MA) and 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) as comonomers, a homogeneous reaction system was prepared by mixing them in a preset molar ratio, adding an initiator and a suitable solvent. After deoxygenation treatment, a free radical copolymerization reaction was initiated by thermal initiation. The reaction kinetic parameters were adjusted to effectively control the polymer composition and molecular weight. After precipitation purification, washing, and vacuum drying, the reaction product was obtained as a target temperature responsive copolymer.

[0015] The initiator is selected from at least one of the following: For oil-phase polymerization, azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), and azobisisoheptanenitrile (ABVN) are preferred; for aqueous-phase polymerization, ammonium persulfate (APS) and potassium persulfate (KPS) are preferred. They can be used alone or in combination with reducing agents to form a redox initiation system. The solvent is selected from at least one of the following: For oil-phase polymerization, anhydrous tetrahydrofuran (THF), toluene, and dioxane are used; for aqueous / semi-aqueous-phase polymerization, deionized water, ethanol, or a mixture of ethanol and water (volume ratio 1:1) are used, with a solvent-to-monomer mass ratio of 3 to 10:1. Polymerization temperature: 60~80℃ for azo initiators, 50~70℃ for peroxide initiators, and 30~50℃ for redox initiation systems. The temperature is controlled within ±2℃. Initiator dosage: 0.1%~1.0% of the total molar amount of HEO2MA and MEO2MA monomers, preferably 0.3%~0.8%; Monomer concentration: The total mass concentration of monomers in the reaction system should be 10%~30% to avoid excessively high concentrations that could lead to excessive viscosity and uneven heat dissipation. Deoxygenation process: The oil phase system is deoxygenated by freezing-vacuuming-thawing 2-3 times; the aqueous phase system is deoxygenated by high-purity nitrogen bubbling for 30-40 minutes, and a nitrogen atmosphere is maintained throughout the process; Reaction time: 8~24 h, preferably 12~18 h, with a monomer conversion rate ≥90% as the reaction endpoint; Stirring rate: 200~400 rpm, to ensure uniform reaction system and smooth heat dissipation.

[0016] 2. Reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) HEO2MA and MEO2MA were used as comonomers. RAFT reagent, initiator and solvent were added. After three cycles of "freezing-vacuuming-dissolving" to remove oxygen, the polymer was polymerized at a constant temperature for a certain time. The product was purified by dialysis or precipitation and freeze-dried to obtain a pink viscous polymer.

[0017] Preferred process parameters: The RAFT reagent is selected from at least one of the following: Dithioesters (most commonly used, suitable for the monomer system of this invention): 4-cyano-4-(thiobenzoyl)valerate (CPADB), isobutyronitrile dithiobenzoate (CDB), 2-cyano-2-propylbenzodisulfide (CPBD), 4-cyano-4-(phenylthiocarbonylthio)valerate (CTA), 2-phenyl-2-propylbenzodisulfide (PPBD), 1-phenylethylbenzodisulfide (PEBD); Trithiocarbonates (suitable for aqueous / semi-aqueous phase polymerization): Diphenyl trithiocarbonate (DTCB), Diethyl trithiocarbonate (DTCE), O-ethyl-S-(1-methyl-2-oxopropyl)trithiocarbonate (EMPTC), 4-((2-carboxyethyl)thiocarbonylthio)-4-cyanopentanoic acid (CECP); Xanthates (applicable to methacrylate monomers): O-ethyl-S-(2-hydroxyethyl) xanthate (EHEX), O-isopropyl-S-(2-hydroxyethyl) xanthate (IHEX), O-butyl-S-(2-hydroxyethyl) xanthate (BHEX); Dithiocarbamates (suitable for copolymerization with a wide range of monomers): benzyl N,N-diethyldithiocarbamate (BDC), isopropyl N,N-dimethyldithiocarbamate (IPDC); preferred are CPADB, CECP, and EMPTC (suitable for HEO2MA / MEO2MA systems, with strong controllability and high product purity).

[0018] The initiator is selected from at least one of the following: Azo initiators (suitable for both oil and aqueous phases, with mild decomposition): Azobisisobutyronitrile (AIBN), Azobisisoheptanenitrile (ABVN), 4,4'-azobis(4-cyanopentanoic acid) (ACVA, water-soluble), Azobisisobutyramidine hydrochloride (AIBA, water-soluble), Azobisisopropylimidazoline hydrochloride (AIPH). Peroxide initiators (highly active, suitable for medium and low temperature polymerization): benzoyl peroxide (BPO), diethylhexyl peroxide (EHP), tert-butyl peroxypentanoate (TBPP), potassium persulfate (KPS, water soluble), ammonium persulfate (APS, water soluble), tert-butyl peroxybenzoate (TBPB). Redox initiation system (suitable for low-temperature polymerization to avoid monomer side reactions): APS-sodium bisulfite, KPS-sodium bisulfite, BPO-N,N-dimethylaniline (DMA). For oil-phase polymerization, AIBN, BPO, and ABVN are preferred; for aqueous / semi-aqueous-phase polymerization, a compound system of ACVA, AIBA, and APS-KPS is preferred.

[0019] The solvent is selected from at least one of THF, dioxane, toluene, ethanol, methanol, water, DMSO, DMF, etc. The polymerization temperature is 60-80℃; The molar ratio of monomer to RAFT reagent is 20-600:1; The amount of initiator used is 0.1%-0.3% of the total molar number of monomers; The reaction time is 12-24 h.

[0020] 3. Atom Transfer Radical Polymerization (ATRP) Using HEO2MA and MEO2MA as comonomers, initiators, catalysts, and ligands were added. After three deoxygenation processes of "freezing-vacuuming-dissolving" in a solvent, polymerization was carried out at a constant temperature for a certain period of time. The reaction product was passed through a neutral alumina column to remove metal residues, and then precipitated with n-hexane and vacuum dried to obtain a solid copolymer.

[0021] Preferred process parameters: The initiator is selected from at least one of the following; Alkyl halides (most commonly used, preferred for oil-phase polymerization): ethyl 2-bromoisobutyrate (EBiB), ethyl α-bromophenylacetate (EBPA), methyl 2-bromoisobutyrate (MBiB), tert-butyl 2-bromo-2-methylpropionate (tBBr), 1-bromoethylbenzene (PEBr), ethyl 2-chloroisobutyrate (ECiB); Water-soluble initiators (suitable for aqueous / semi-aqueous phase polymerization): Sodium 2-bromoisobutyrate (NaBiB), sodium 2-bromo-2-methylpropionate (NaMBBr), sodium α-bromophenylacetate (NaBPA), sodium 2-bromoethanesulfonate (NaBES); Multifunctional initiators (for the preparation of star / multi-arm copolymers): Pentaerythritol tetra(2-bromoisobutyrate) (PETIB), Trimethylolpropane tri(2-bromoisobutyrate) (TMPTB), Dipentaerythritol hexa(2-bromoisobutyrate) (DiPETHB); Preferred options include EBiB, EBPA (oil-phase polymerization, with strong controllability and high initiation efficiency), and NaBiB (aqueous-phase polymerization, with good solubility and no organic residue).

[0022] The catalyst is selected from at least one of the following; Copper-based catalysts (most commonly used, suitable for methacrylate monomers): cuprous bromide (CuBr), cuprous chloride (CuCl), cuprous iodide (CuI), cuprous cyanide (CuCN), copper bromide (CuBr2), copper chloride (CuCl2) (used for reverse ATRP or initiator regeneration ATRP); Iron-based catalysts (low toxicity and environmentally friendly, compatible with a wide range of monomers): ferrous chloride (FeCl2・4H2O), ferrous bromide (FeBr2・4H2O), ferric acetylacetone (Fe(acac)3), ferric chloride (FeCl3・6H2O); Ruthenium-based catalysts (highly active, suitable for low-temperature polymerization): bis(triphenylphosphine) ruthenium dichloride (RuCl2(PPh3)3), ruthenium(II) dichlorodi ... Nickel-based catalysts (highly stable and suitable for difficult-to-polymerize monomers): nickel dibromide (NiBr2), bis(diphenylphosphine) nickel dichloride (NiCl2(PPh3)2); The ligand is selected from at least one of the following: Aliphatic amines (suitable for copper-based catalysts, preferred for oil phase): N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA), tris(2-dimethylaminoethyl)amine (Me6TREN), N,N,N',N'-tetramethylethylenediamine (TMEDA), 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA); Phosphine ligands (suitable for ruthenium-based / nickel-based catalysts): triphenylphosphine (PPh3), tricyclohexylphosphine (PCy3), diphenylphosphinemethane (dppm); Water-soluble ligands (suitable for aqueous phase polymerization): tris(2-hydroxyethyl)methylammonium chloride (METAC), N,N-dimethylethanolamine (DMEA), 2-(dimethylamino)ethanol (DMAE); PMDETA (high versatility, low cost) and Me6TREN (high catalytic activity, suitable for high conversion rate requirements) are preferred. The solvent is selected from at least one of THF, dioxane, toluene, ethanol, methanol, water, DMSO, and DMF; The polymerization temperature is 80-100℃; The catalyst to ligand molar ratio is 1:2; The molar ratio of monomer to initiator is 20-600:1; The reaction time is 8-16 h.

[0023] 4. Emulsion polymerization In an aqueous phase, HEO2MA and MEO2MA are used as comonomers. An emulsifier is added to form stable micelles. After nitrogen gas is introduced to remove oxygen, an initiator is added. The mixture is polymerized at a constant temperature for a certain period of time to directly obtain an aqueous dispersion of copolymer emulsion.

[0024] Preferred process parameters: The emulsifier is selected from at least one of sodium dodecyl sulfate (SDS) and polyoxyethylene octylphenyl ether (OP-10); The initiator is selected from at least one of ammonium persulfate (APS) and potassium persulfate (KPS); The polymerization temperature is 50-70℃; The amount of emulsifier used is 2%-5% of the total mass of monomers; The amount of initiator used is 0.5%-1% of the total molar number of monomers; The stirring speed is 1000-1500 rpm during pre-emulsification and 200-300 rpm during polymerization; The reaction time is 4-8 hours.

[0025] 5. Solution polymerization HEO2MA and MEO2MA were used as comonomers. An initiator and solvent were added, and the mixture was stirred and dissolved. Nitrogen gas was then introduced to remove oxygen, and polymerization was carried out at a constant temperature for a certain period of time. The reaction product was purified by precipitation with diethyl ether and dried under vacuum to obtain a powdered copolymer.

[0026] Preferred process parameters: The initiator is selected from at least one of AIBN and BPO; The solvent is selected from at least one of THF, dioxane, toluene, ethanol, methanol, water, DMSO, and DMF; The polymerization temperature is 60-80℃; The amount of solvent used is 1-2 times the total mass of the monomers; The stirring speed is 200-300 rpm; The reaction time is 12-24 h.

[0027] Preferably, the temperature-responsive polymer of the present invention is prepared by a living radical polymerization method. More preferably, it is obtained by RAFT polymerization.

[0028] Preferably, the LCST of the temperature-responsive polymer in a 1 mg / mL aqueous solution is 20°C-45°C, and more preferably 30°C-43°C.

[0029] In some instances, the LCST of the temperature-responsive polymer in a 1 mg / mL aqueous solution is 20℃-25℃, 25℃-30℃, 20℃-30℃, 25℃-35℃, 30℃-40℃, etc., for example, it can be 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃ or 45℃.

[0030] Secondly, the present invention provides applications of the temperature-responsive polymer, including the preparation of temperature-sensitive materials, smart glass, or windows (especially sunshade windows).

[0031] Thirdly, the present invention provides a temperature-sensitive material comprising the temperature-responsive polymer described in any of the preceding claims.

[0032] Fourthly, the present invention provides a smart glass comprising an aqueous solution of the temperature-responsive polymer described in any of the preceding claims.

[0033] Preferably, the smart glass comprises a sealed transparent container and the temperature-responsive polymer solution encapsulated within the sealed transparent container.

[0034] Preferably, the sealed transparent container is made of organic or inorganic materials.

[0035] The organic material may be, for example, polymethyl methacrylate, polycarbonate, polystyrene, polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate, cyclic olefin copolymer, polyurethane, plexiglass, epoxy resin, or transparent polyamide.

[0036] The inorganic material may be, for example, ordinary soda-lime glass, borosilicate glass, quartz glass, high borosilicate glass, soda-lime silicate glass, sapphire glass, calcium fluoride crystal, barium fluoride crystal, fused silica, or transparent ceramic.

[0037] Preferably, the sealed transparent container is glass, more preferably sodium-calcium silicate glass.

[0038] Preferably, the temperature-responsive polymer solution is an aqueous solution of a temperature-responsive polymer.

[0039] Preferably, the concentration of the aqueous solution is from 0.1 mg / mL to 10 mg / mL.

[0040] More preferably, the concentration of the aqueous solution is from 0.5 mg / mL to 2.5 mg / mL.

[0041] In some instances, the concentration of the aqueous solution may be, for example, 0.1 mg / mL, 0.5 mg / mL, 0.8 mg / mL, 1.0 mg / mL, 1.2 mg / mL, 1.5 mg / mL, 1.8 mg / mL, 2.0 mg / mL, 2.2 mg / mL, 2.5 mg / mL, 5.0 mg / mL, or 10.0 mg / mL.

[0042] Preferably, the LCST of the temperature-responsive polymer solution is 20°C to 45°C, more preferably 30°C to 43°C.

[0043] Preferably, the LCST of the temperature-responsive polymer solution in the smart glass is 20℃-25℃, 25℃-30℃, 20℃-30℃, 25℃-35℃, 30℃-40℃, etc., for example, it can be 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃ or 45℃.

[0044] Fifthly, the present invention provides a sunshade window comprising the smart glass described in any of the preceding claims.

[0045] Compared with the prior art, the present invention has the following significant advantages: 1. Wide adjustable response temperature range: By adjusting the monomer ratio of HEO2MA and MEO2MA, the polymer LCST can be precisely adjusted within the range of 20℃-45℃, especially 30℃-40℃, to meet the building needs of different climate regions such as tropical and subtropical regions, and solve the defect of fixed response temperature of traditional materials.

[0046] 2. Excellent optical properties: The visible light transmittance of the polymer solution is ≥90% when the temperature is below LCST, ensuring sufficient indoor lighting; when the temperature is above LCST, the transmittance drops to below 5%, blocking more than 95% of solar radiation. It also possesses excellent ultraviolet blocking properties; experimental measurements show that the ultraviolet absorption rate of the temperature-responsive polymer in this embodiment of the invention after phase transition is ≥95%.

[0047] 3. Significant energy-saving effect: Outdoor simulation experiments show that smart windows equipped with this polymer can reduce indoor temperature by 5-25℃, improving energy efficiency by more than 30% compared with traditional glass, and have broad application prospects in saving building cooling energy consumption.

[0048] Therefore, the manufacturing process of the intelligent window made from the polymer of this invention is simple, compatible with existing glass processing technology, and requires no additional equipment. This intelligent window features a wide temperature response range, high light transmittance, excellent thermal insulation performance, and long-term stability. It can be widely used in lighting and temperature control components in various scenarios such as residential buildings, commercial buildings, and public facilities. Furthermore, it can be extended to applications in building energy-saving films, passive temperature control devices, and other fields, demonstrating significant energy-saving value and market potential. Attached Figure Description

[0049] Figure 1 Typical temperature-responsive polymers of the present invention 1 HNMR spectrum.

[0050] Figure 2 The transmittance curve of the temperature-responsive polymer solution of this invention varies with temperature.

[0051] Figure 3 : Flowchart of the preparation process of the smart glass of this invention.

[0052] Figure 4 Photos of the smart glass of this invention before and after phase transition.

[0053] Figure 5 Photographs of the intelligent window cooling experiment of this invention.

[0054] Figure 6 The temperature at the geometric center of the outdoor simulated building model of the smart glass of this invention changes over time.

[0055] Figure 7 The outdoor performance comparison photos and temperature performance test results of smart windows made of different glass materials prepared with the temperature-responsive polymer of the present invention are shown.

[0056] Figure 8 The results of repeatability tests on the light transmittance of the smart glass of this invention before and after phase transition. Detailed Implementation

[0057] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0058] The present invention will be further described in detail below with reference to specific embodiments: Unless otherwise specified, "%" in this invention refers to the mass percentage (wt%).

[0059] Example raw material MEO2MA: ethyl 2-(2-methoxyethoxy)methacrylate, CAS number 45103-58-0.

[0060] HEO2MA: 2-(2-hydroxyethoxy)ethyl methacrylate, CAS number 2351-43-1.

[0061] All raw materials were purchased from Aldrich. THF was purified by distillation before use, while the other reagents were used directly.

[0062] instrument 1 H NMR: Bruker DMX-400 nuclear magnetic resonance spectrometer.

[0063] UV-Vis Spectrophotometer: SPE CO The RD 250 model is equipped with an automatic temperature control accessory.

[0064] GPC: Waters 150C gel permeation chromatograph, mobile phase: THF, flow rate: 1.0 mL / min.

[0065] Example 1: RAFT method for P [(HEO2MA)- co Synthesis of -(MEO2MA)] HEO2MA and MEO2MA were used as comonomers, 4-cyano-4-(thiobenzoylthio)valerate (CPADB) was used as the RAFT reagent, 2,2'-azobisisobutyronitrile (AIBN) was used as the initiator, and anhydrous THF was used as the solvent. The feeding parameters are shown in Table 1.

[0066] Table 1: P [(HEO2MA)- co Feeding and performance data of the (MEO2MA) polymer.

[0067] Typical synthesis steps: According to the proportions in Table 1, HEO2MA, MEO2MA, CPADB, and AIBN were added to a 5 mL Schlenk tube, and anhydrous THF was added. The system was subjected to three cycles of "freezing (-78℃, liquid nitrogen bath) - vacuuming (5 min) - thawing" to completely remove oxygen. The Schlenk tube was placed in a 70℃ constant temperature water bath and sealed for constant temperature polymerization for 24 h. After the reaction was completed, the mixture was cooled to room temperature, diluted with deionized water, and transferred to a dialysis bag with a molecular weight cutoff of 3500 Da. Dialysis was performed in deionized water for 3 days (changing the water every 8 h). After dialysis, the solution was freeze-dried (-50℃, 0.01 MPa) for 24 h to obtain a pink viscous block polymer with a yield of 85%-88%. The product structure was verified by ¹H NMR (…). Figure 1 The molecular weight and distribution of sample 2 were determined by GPC (H1N M NMR spectrum). The structural formula is as follows: .

[0068] Example 2: Preparation of P[(HEO2MA)- by ATRP method co -(MEO2MA)] Feeding: In a 50 mL Schlenk tube, add HEO2MA (0.96 mmol, 167.04 mg), MEO2MA (8.88 mmol, 1669.44 mg), ethyl 2-bromoisobutyrate (EBiB, 0.1 mmol, 18.9 mg), CuBr (0.1 mmol, 14.4 mg), PMDETA (0.2 mmol, 35.6 mg), and anhydrous THF (20 mL), and stir until homogeneous; Deoxygenation: Repeat the "freeze-vacuum-thaw" cycle three times to remove oxygen from the system; Polymerization: Place the Schlenk tube in a 90℃ oil bath and polymerize at a constant temperature for 12 h; Purification: Filter the reaction solution through a neutral alumina column to remove Cu salt, and precipitate the filtrate by adding it dropwise to 100 mL of n-hexane; Drying: Collect the solid by filtration and dry it under vacuum at 40℃ for 12 h. h, a white powdery polymer was obtained with a yield of 78%-83%, and the structural formula was the same as in Example 1, wherein X was 9, Y was 71, Mn was 13200, and PDI was 1.16.

[0069] Example 3 Preparation of P[(HEO2MA)- by ring-opening polymerization (ROP) co -(MEO2MA)] Preparation: PEG (molecular weight 4000 Da, 1 mmol, 4 g) was dried in a vacuum drying oven (80℃, 0.01 MPa) for 4 h; toluene was dried with sodium wire and then collected by distillation; Feeding: In a 50 mL Schlenk tube, the dried PEG, HEO2MA (0.5 mmol, 87 mg), MEO2MA (5 mmol, 930 mg), stannous octoate (0.05 mmol, 23.8 mg), and anhydrous toluene (10 mL) were added and stirred until homogeneous; Deoxygenation: The oxygen was removed by two cycles of "freezing-vacuuming-thawing"; Polymerization: The Schlenk tube was placed in an oil bath at 110℃ and polymerized at a constant temperature for 12 h; Purification: The reaction solution was added dropwise to 100 mL of n-hexane to precipitate, the solid was collected by filtration and dried under vacuum at 60℃ for 12 h. h, a waxy polymer was obtained with a yield of 80%-85%, and the structural formula was the same as in Example 1, wherein X is 7, Y is 73, Mn is 17800, and PDI is 1.25.

[0070] Example 4 Preparation of P[(HEO2MA)- by emulsion polymerization co -(MEO2MA)] Pre-emulsification: In a 250 mL three-necked flask, add 100 mL of deionized water, 0.5 g of SDS, and 0.5 g of OP-10. After stirring to dissolve, add HEO2MA (0.96 mmol, 167.04 mg) and MEO2MA (8.88 mmol, 1669.44 mg). Stir at high speed (1000 rpm) for 30 min to form a stable pre-emulsion. Deoxygenation: Purge the pre-emulsion with nitrogen for 30 min to remove oxygen. Polymerization: Place the flask in a 60°C water bath, add APS (0.1 mmol, 28.8 mg), adjust the stirring speed to 300 rpm, and polymerize at a constant temperature for 4 h. Product: After the reaction is complete, cool to room temperature to obtain a blue, semi-transparent copolymer emulsion with a solid content of approximately 10%. If a solid product is required, the emulsion can be centrifuged (8000 rpm, 15 min). (min), collect the precipitate and freeze-dry it, with a yield of 95%. The structural formula is the same as in Example 1, where X is 8, Y is 70, Mn is 14800, and PDI is 1.42.

[0071] Example 5 Preparation of P[(HEO2MA)- by solution polymerization co -(MEO2MA)] Feeding: In a 100 mL three-necked flask, add HEO2MA (0.96 mmol, 167.04 mg), MEO2MA (8.88 mmol, 1669.44 mg), AIBN (0.1 mmol, 16.4 mg), and an ethanol / water mixture (volume ratio 1:1, 30 mL), and stir until completely dissolved; Deoxygenation: Purge with nitrogen for 30 min to remove oxygen from the system; Polymerization: Place the flask in a 70 °C water bath and polymerize at a constant temperature for 16 h; Purification: Add the reaction solution dropwise into 200 mL of diethyl ether to precipitate, and filter to collect the solid; Drying: Dry under vacuum at 50 °C for 12 h to obtain a white powdered polymer with a yield of 75%-80%, the structural formula of which is the same as in Example 1, wherein X is 7, Y is 71, Mn is 12900, and PDI is 1.5.

[0072] Example 6 Thermosensitivity Test Take samples 1-3 from Example 2 and prepare aqueous solutions of 1 mg / mL each using deionized water as the solvent. Pour the solutions into 1 cm thick quartz cuvettes and place them in a UV-Vis spectrophotometer. Turn on the automatic temperature control accessory, set the test temperature range to 20℃-45℃ with a temperature interval of 1℃, and test the transmittance at a wavelength of 560 nm.

[0073] The test results (see Figure 2) show that: 1: Temperature responsiveness and phase transition synchronicity The low critical solution temperature (LCST) of sample 1 (x / y=4 / 76, Mn=12364, PDI=1.13) is 31.4℃. When the temperature rises to 31.4℃, the polymer molecular chains rapidly change from a hydrophilic extended state to a hydrophobic coiled state, resulting in phase separation. The LCST of sample 2 (x / y=8 / 72, Mn=11391, PDI=1.12) was 34.2℃. Due to the increased HEO2MA content, the hydrophilicity was enhanced, and the phase transition temperature shifted to the high-temperature region. The LCST of sample 3 (x / y=10 / 70, Mn=12950, ​​PDI=1.12) was 33.3℃, ​​and the phase transition temperature was between that of sample 1 and sample 2, which verified that the LCST can be precisely controlled in the range of 30℃-40℃ by adjusting the monomer molar ratio.

[0074] In addition, the transmittance of all three samples underwent rapid abrupt changes within the LCST±1℃ range, with a transmittance decrease slope >40% / ℃, demonstrating excellent phase transition synchronicity, which is closely related to the narrow molecular weight distribution of the polymer (PDI≤1.13).

[0075] 2: Visible light transmittance When the temperature is below LCST, the polymer solution is uniform and transparent. Sample 1 has a transmittance of 92% at 560 nm at 20℃, Sample 2 has a transmittance of 93%, and Sample 3 has a transmittance of 92.5%, all of which are significantly higher than those of traditional PNIPAM hydrogel (transmittance before phase change is about 85%) and VO2 film (transmittance is about 80%), which can fully meet the needs of natural lighting in building interiors. When the temperature is higher than LCST, the polymer molecular chains aggregate to form microspheres and scatter light. The transmittance of sample 1 drops to 4.5% at 35℃, sample 2 drops to 4.2% at 36℃, and sample 3 drops to 4.3% at 40℃. The transmittance drops by more than 87% in all samples, which can block more than 95% of solar radiation and effectively reduce indoor temperature.

[0076] In summary, all three polymers exhibit core properties such as adjustable response temperature, high light transmittance, and reversible and stable phase transition. Their response temperature ranges from 30℃ to 40℃, making them fully suitable for the energy-saving needs of buildings in tropical, subtropical, and other high-temperature climate regions.

[0077] Example 7: Preparation of Smart Glass Window according to Figure 3 The smart glass of this invention is prepared using the following process.

[0078] 1. Glass pretreatment: Select double-layer insulated tempered glass (size 25 cm × 25 cm, insulated layer thickness 1 cm, material is sodium calcium silicate), wipe the inner surface of the glass with anhydrous ethanol, and let it air dry naturally; 2. Preparation of filling solution: Take the polymer of sample 2 in Example 1, and use deionized water as solvent to prepare aqueous solutions of 0.5 mg / mL, 1 mg / mL and 2 mg / mL, and stir for 30 min until completely dissolved; 3. Filling and sealing: Through the pre-drilled injection hole in the glass, slowly inject 250 mL of filling liquid into the insulating glass interlayer using a syringe. During the filling process, gently tap the glass to expel air bubbles. 4. Curing: Seal the injection holes with silicone sealant and cure at room temperature for 24 hours to obtain 3 sets of finished smart glass windows. Simultaneously, ordinary double-glazed windows of the same specifications were prepared as a blank control group.

[0079] Among them, the photos of the smart glass (1 mg / mL) of sample 2 before phase transition (32℃) and after phase transition (35℃) are as follows: Figure 4 As shown, the smart glass of this invention becomes opaque after the phase transition.

[0080] Example 8: Outdoor Energy-Saving Performance Test of Smart Windows 1. Simulated building model construction A simulated building model (45 cm long × 39 cm wide × 37 cm high, with an inner wall thickness of 4.2 cm) was fabricated using foam material. Three sets of smart glass windows prepared in Example 7 were installed on one side of the model, and the gaps were sealed with sealant. A PT100 thermocouple was fixed at the geometric center of the model for monitoring the indoor temperature.

[0081] 2. Intelligent cooling performance test The three sets of simulated building models obtained in step 1 were placed in an outdoor natural environment. The test period was from 6:00 to 24:00. The core temperature of the model and the ambient temperature were recorded every 50 minutes (photos of the experimental time points are shown in the figure). Figure 5 (As shown).

[0082] Tests such as Figure 6 As shown, where Figure 6 The left image shows the test results on a cloudy day. Figure 6 The right figure shows the test results on a sunny day. The results indicate that when the ambient temperature reaches a maximum of 38℃, the center temperature of the blank control group model is 66℃; the center temperatures of the models corresponding to 0.5 mg / mL, 1 mg / mL, and 2 mg / mL polymer solutions are 60℃, 56℃, and 55℃, respectively, which are 6℃, 10℃, and 11℃ lower than the control group. The higher the polymer solution concentration, the more significant the heat insulation effect, achieving a temperature adjustment range of up to 11℃.

[0083] 3. Performance Comparison Tests of Different Types of Glass Five different types of glass were selected for outdoor performance comparison: A (ordinary single-pane glass), B (ordinary double-pane insulated glass), C (double-pane water-filled glass), D (heat-insulating film glass), and E (sample 2 of the smart window of this invention, filled with a 1 mg / mL polymer solution). The five types of glass were installed on identical simulated building models, and the temperature change at the model's center was tested under the same outdoor environment from 6:00 to 24:00 (see...). Figure 7 ). Figure 7 The left image is a photograph of the experiment, and the right image is the result of the temperature performance test.

[0084] Test results show that the intelligent window (E) of this invention has the best temperature regulation effect. The highest temperature at the center of the model is 54℃, which is 10℃ lower than ordinary single-pane glass (A, 64℃), 9℃ lower than ordinary double-glazed glass (B, 63℃), 7℃ lower than water-filled glass (C, 61℃), and 6℃ lower than heat-insulating film glass (D, 60℃). This intelligent window maintains high light transmittance when the temperature is below LCST and quickly switches to a light-blocking and heat-insulating state when the temperature is above LCST, thus achieving active energy-saving regulation.

[0085] 4. Repeatability test of light transmittance of smart glass before and after phase transition The smart window of this invention (sample 2, filled with a 1 mg / mL polymer solution) was selected. The performance changes of the smart window's light transmittance after multiple cycles were simulated under normal temperature (25°C) and extreme high temperature (45°C). The test conditions were as follows: the smart window was placed in an environment at 25°C, and the light transmittance at 560 nm was measured after 2 minutes; then the window was quickly placed in an environment at 45°C, and the light transmittance at 560 nm was measured after 2 minutes. This process was repeated 50 times.

[0086] Test results show that the smart window of this invention can still maintain good light-blocking performance after 50 cycles, achieving good light transmission performance at low temperatures and blocking sunlight at high temperatures.

[0087] All technical solutions described above that fall within the scope of this invention's conceptual framework are protected by this invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of this invention should also be considered within the scope of protection of this invention.

Claims

1. A temperature-responsive polymer comprising repeating units as shown in Formula I: Equation I; Formula I is a polymerization product of two monomers: 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and 2-(2-hydroxyethoxy)ethyl methacrylate (HEO2MA). In Equation I, x is 1-100; y is 20-500.

2. The temperature-responsive polymer according to claim 1, wherein the number-average molecular weight of the temperature-responsive polymer is 3,000-100,000, preferably 5,000 to 15,000.

3. The temperature-responsive polymer according to claim 1, wherein in formula I, x:y is 1:3 to 1:100, preferably 1:5 to 1:20; Preferably, in Formula I, x is 2-20; y is 50-80.

4. The temperature-responsive polymer according to claim 1, wherein the temperature-responsive polymer is prepared by a free radical polymerization method.

5. The temperature-responsive polymer according to claim 1, wherein the LCST of the temperature-responsive polymer in a 1 mg / mL aqueous solution is 20°C-45°C, preferably 30°C-43°C.

6. A temperature-sensitive material comprising the temperature-responsive polymer according to any one of claims 1-5.

7. A smart glass comprising an aqueous solution of the temperature-responsive polymer according to any one of claims 1-5.

8. The smart glass according to claim 7, wherein the smart glass comprises a sealed transparent container and the temperature-responsive polymer solution encapsulated in the sealed transparent container; Preferably, the sealed transparent container is made of organic or inorganic materials, and more preferably glass.

9. The smart glass according to claim 7, wherein the temperature-responsive polymer solution is an aqueous solution of a temperature-responsive polymer; preferably, the concentration of the aqueous solution is from 0.1 mg / mL to 10 mg / mL; preferably, the LCST of the temperature-responsive polymer solution is from 20°C to 45°C, more preferably from 30°C to 43°C.

10. A sunshade window comprising the smart glass according to any one of claims 7-9.

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