A thermally crosslinkable high-transparency electrochromic polymer, an electrochromic polymer film and a preparation method thereof

Abstract

The application belongs to the technical field of functional polymer materials, and provides a heat-crosslinkable high-transparency electrochromic polymer, an electrochromic polymer film and a preparation method thereof. The 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole is obtained by mixing dimethoxy-9H-carbazole, m-bromostyrene, a dialkyl biaryl phosphine ligand, a first catalyst, an organic salt and a first organic solvent and then performing a heating reaction, and then the 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole is mixed with glycidyl methacrylate, a second catalyst and a second organic solvent to perform a polymerization reaction, so as to obtain the heat-crosslinkable high-transparency electrochromic polymer. The method is simple and low in cost, the polymer prepared by the method has carbazole derivatives as color-changing units and epoxy groups as heat-crosslinking units, and the polymer can be in-situ heat-crosslinked by blending with a crosslinking agent and heating in one step, so as to form a neutral-state high-transparency three-dimensional network film, and the polymer is particularly suitable for high-end transparent devices.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials technology, and in particular to a thermally crosslinkable high-permeability electrochromic polymer, an electrochromic polymer film, and a method for preparing the same. Background Technology

[0002] Electrochromic materials can undergo reversible color changes under the influence of an applied electric field, and have significant application value in fields such as smart windows, displays, anti-glare mirrors, and adaptive camouflage. Among various electrochromic materials, conductive polymers have become a research hotspot due to their advantages such as tunable color, rapid response, and high optical contrast.

[0003] However, currently common conductive polymer-based electrochromic materials, especially those based on long conjugated backbones such as polyaniline and polythiophene, still have significant drawbacks in practical applications. These materials are typically prepared via aryl coupling polymerization, resulting in rigid conjugated backbones with poor solubility. They often require modification with long alkyl chains, and the polymerization process is complex and the degree of polymerization is difficult to control precisely. Excessive polymerization further weakens solubility and processability, while overly long conjugated structures can cause the material to exhibit a gray state or background absorption in its intrinsic state, making it difficult to achieve complete colorlessness and high transparency, thus limiting their application in high-end transparent devices.

[0004] Therefore, it is of great significance to develop an electrochromic material that is highly transparent in a neutral state, has vivid colors in a colored state, and has excellent overall performance. Summary of the Invention

[0005] In view of this, the present invention provides a thermally crosslinkable high-permeability electrochromic polymer, an electrochromic polymer film, and a method for preparing the same, in order to solve the problems that existing electrochromic materials are difficult to achieve completely colorless and highly transparent, and that the preparation process is complex.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a thermally crosslinkable high-permeability electrochromic polymer, the structural formula of which is shown in Formula I: ; In Equation I, x and y represent the degree of aggregation, and x and y are independent integers from 5 to 15.

[0007] The present invention also provides a method for preparing the above-mentioned thermally crosslinkable high-permeability electrochromic polymer, comprising the following steps: 1) Dimethoxy-9H-carbazole, m-bromostyrene, dialkylbiarylphosphine ligand, first catalyst, organic salt and first organic solvent are mixed and heated to obtain 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole; 2) 3,6-Dimethoxy-9-(3-vinylphenyl)-9H-carbazole, glycidyl methacrylate, a second catalyst, and a second organic solvent are mixed and polymerized to obtain the thermally crosslinkable, highly permeable electrochromic polymer shown in Formula I. The structural formula of the 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole is shown in Formula II: .

[0008] Preferably, the molar ratio of dimethoxy-9H-carbazole, m-bromostyrene, dialkylbiarylphosphine ligand, first catalyst and organic salt in step 1) is 1:1~1.3:0.04~0.048:0.01~0.1:2~10.

[0009] Preferably, the dialkylbiarylphosphine ligand in step 1) comprises one or more of 2-biscyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, and 2-dicyclohexylphosphine-2',6'-diisopropoxybiphenyl; the first catalyst comprises one or more of tris(dibenzylacetone)palladium, tetra(triphenylphosphine)palladium, and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride; the organic salt comprises potassium tert-butoxide and / or sodium tert-butoxide; and the first organic solvent comprises one or more of toluene, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0010] Preferably, the heating reaction in step 1) is carried out at a temperature of 110~120℃ for 12~15 h.

[0011] Preferably, the molar ratio of 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole, glycidyl methacrylate, and the second catalyst in step 2) is 1:0.8~1.1:1~1.5.

[0012] Preferably, in step 2), the second catalyst includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide; the second organic solvent includes acetone and / or tetrahydrofuran.

[0013] Preferably, the polymerization reaction in step 2) is carried out at a temperature of 60-80°C for 36-50 h.

[0014] The present invention also provides an electrochromic polymer film, which is prepared from the above-mentioned thermally crosslinkable high-permeability electrochromic polymer.

[0015] Preferably, the method for preparing the electrochromic polymer film includes the following steps: S1: Mix the thermally crosslinkable, highly permeable electrochromic polymer shown in Formula I, an amine crosslinking agent, and a third organic solvent to obtain a mixed solution; S2: The mixed solution is coated onto the surface of the substrate and then thermally cured to obtain an electrochromic polymer film.

[0016] Preferably, in step S1, the mass ratio of the thermally crosslinkable high-permeability electrochromic polymer to the amine crosslinking agent is 10:1~3; and the mass-volume concentration of the mixed solution is 5~20 mg / mL.

[0017] Preferably, the amine crosslinking agent in step S1 includes one or more of 4,4'-diaminodiphenylmethane, tetraethylenepentamine, and polyethyleneimine; the third organic solvent includes one or more of dichloromethane, trichloromethane, and tetrahydrofuran.

[0018] Preferably, the thermosetting atmosphere in step S2 is an inert atmosphere, the temperature is 120~170℃, and the time is 4~5.5h.

[0019] Preferably, the substrate in step S2 includes one of ITO glass, FTO glass, ITO-PET composite film, and FTO-PET composite film.

[0020] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a thermally crosslinkable, highly transparent electrochromic polymer, which uses carbazole derivatives as color-changing units and introduces epoxy groups as thermal crosslinking units. The polymer has a simple and low-cost synthesis process, achieves colorless high transparency in the neutral state, and can switch to a purplish-blue color in the oxidized state. Furthermore, the polymer exhibits good solubility in common solvents such as chloroform, facilitating film formation using solution processing techniques such as spin coating and spraying. The process is simple and suitable for large-scale production.

[0021] 2. The electrochromic polymer film prepared using the thermally crosslinkable high-transparency electrochromic polymer described in this invention has a crosslinked structure, high transparency in the neutral state, color in the oxidized state, and excellent solution processability; the highly crosslinked network structure endows the material with good durability and stability, reduces the preparation threshold and cost, and has broad application prospects in energy-saving displays, static information display and dynamic information encryption, military camouflage and other fields. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 The 1H NMR spectrum of the thermally crosslinkable, highly permeable electrochromic polymer prepared in Example 1; Figure 2 The cyclic voltammetry curve of the electrochromic polymer film prepared in Example 1 is shown below. Figure 3 The following are the UV-Vis absorption spectra of the electrochromic polymer film prepared in Example 1 at different voltages; Figure 4 The graph shows the transmittance of the electrochromic polymer film prepared in Example 1 as a function of time under multiple potential steps from 0 to 1.3 V at a wavelength of 764 nm. Detailed Implementation

[0024] This invention provides a thermally crosslinkable high-permeability electrochromic polymer, the structural formula of which is shown in Formula I: ; In Formula I, x and y are the degree of aggregation, and x and y are independent integers from 5 to 15, preferably one of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15.

[0025] In this invention, the values ​​of x and y are preferably x=y.

[0026] The present invention also provides a method for preparing the above-mentioned thermally crosslinkable high-permeability electrochromic polymer, comprising the following steps: 1) Dimethoxy-9H-carbazole, m-bromostyrene, dialkylbiarylphosphine ligand, first catalyst, organic salt and first organic solvent are mixed and heated to obtain 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole (yellow solid). 2) 3,6-Dimethoxy-9-(3-vinylphenyl)-9H-carbazole, glycidyl methacrylate, a second catalyst, and a second organic solvent were mixed and subjected to a polymerization reaction to obtain a thermally crosslinkable, highly permeable electrochromic polymer (pale yellow solid) as shown in Formula I. The structural formula of the 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole is shown in Formula II: .

[0027] In this invention, the molar ratio of dimethoxy-9H-carbazole, m-bromostyrene, dialkylbiarylphosphine ligand, first catalyst and organic salt in step 1) is 1:1~1.3:0.04~0.048:0.01~0.1:2~10, preferably 1:1.05~1.2:0.042~0.047:0.015~0.05:3~8, more preferably 1:1.1~1.15:0.043~0.045:0.019~0.03:4~5.

[0028] In this invention, the dialkylbiarylphosphine ligand in step 1) preferably includes one or more of 2-biscyclohexylphosphine-2',4',6'-triisopropylbiphenyl (X-Phos), 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, and 2-dicyclohexylphosphine-2',6'-diisopropoxybiphenyl; the first catalyst preferably includes one or more of tris(dibenzylideneacetone)palladium (Pd2(dba)3 catalyst), tetra(triphenylphosphine)palladium, and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride; the organic salt preferably includes potassium tert-butoxide and / or sodium tert-butoxide (t-BuONa); the first organic solvent preferably includes one or more of anhydrous toluene, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0029] In this invention, the temperature of the heating reaction in step 1) is 110~120℃, preferably 112~118℃, more preferably 115℃; the heating reaction time is 12~15 h, preferably 12.5~14.5 h, more preferably 13~14 h, more preferably 13.5 h.

[0030] In this invention, the chemical reaction equation for the heating reaction in step 1) is as follows: .

[0031] In this invention, the molar ratio of 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole, glycidyl methacrylate, and the second catalyst in step 2) is 1:0.8~1.1:1~1.5, preferably 1:0.9~1.05:1.1~1.3, and more preferably 1:1:1.2.

[0032] In this invention, the second catalyst in step 2) preferably includes one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile, and benzoyl peroxide; the second organic solvent preferably includes acetone and / or tetrahydrofuran.

[0033] In this invention, the temperature of the polymerization reaction in step 2) is 60~80℃, preferably 62~78℃, more preferably 65~75℃, and even more preferably 70℃; the time of the polymerization reaction is 36~50 h, preferably 38~48 h, more preferably 40~46 h, and even more preferably 45 h.

[0034] In this invention, the chemical reaction equation for the polymerization reaction in step 2) is as follows: .

[0035] In this invention, the polymerization reaction described in step 2) preferably includes a post-processing operation; the post-processing preferably involves immersing the product of the polymerization reaction in a methanol solution for precipitation, filtration, and finally Soxhlet extraction and purification with methanol.

[0036] In this invention, the thermally crosslinkable high-permeability electrochromic polymer combines electrochromic activity and epoxy reactivity. By blending with a multifunctional amine crosslinking agent and heating, it can induce in-situ thermal crosslinking in one step to form a neutral, colorless, highly transparent, and stable three-dimensional network film. This polymer provides a high-performance and easily processed material solution for the fabrication of flexible electrochromic devices (such as smart windows, displays, and camouflage systems).

[0037] The present invention also provides an electrochromic polymer film, which is prepared from the above-mentioned thermally crosslinkable high-permeability electrochromic polymer and has a crosslinked structure.

[0038] In this invention, the method for preparing the electrochromic polymer film includes the following steps: S1: Mix the thermally crosslinkable, highly permeable electrochromic polymer shown in Formula I, an amine crosslinking agent, and a third organic solvent to obtain a mixed solution; S2: The mixed solution is coated onto the surface of the substrate and then thermally cured to obtain an electrochromic polymer film.

[0039] In this invention, the mass ratio of the thermally crosslinkable high-permeability electrochromic polymer to the amine crosslinking agent in step S1 is 10:1 to 3, preferably one of 10:1, 10:2, and 10:3, and more preferably 10:1; the mass-volume concentration of the mixed solution is 5 to 20 mg / mL, preferably 8 to 18 mg / mL, and more preferably 10 to 15 mg / mL.

[0040] In this invention, the amine crosslinking agent in step S1 preferably includes one or more of 4,4'-diaminodiphenylmethane, tetraethylenepentamine, and polyethyleneimine (PEI), more preferably polyethyleneimine; the third organic solvent preferably includes one or more of dichloromethane, trichloromethane, and tetrahydrofuran.

[0041] In this invention, the atmosphere for heat curing in step S2 is an inert atmosphere; the gas in the inert atmosphere is preferably nitrogen and / or argon; the temperature for heat curing is 120~170℃, preferably 130~160℃, more preferably 145~155℃, and even more preferably 150℃; the time for heat curing is 4~5.5 h, preferably 4.5~5.4 h, more preferably 4.8~5.2 h, and even more preferably 5 h.

[0042] In this invention, the thermosetting process in step S2 causes the epoxy groups to undergo a ring-opening crosslinking reaction, forming a dense crosslinked network, and finally obtaining an electrochromic polymer film.

[0043] In this invention, the chemical reaction mechanism of thermosetting in step S2 is as follows: .

[0044] In this invention, during the thermosetting process described in step S2, the crosslinking efficiency between the thermocrosslinkable high-permeability electrochromic polymer and the amine crosslinking agent is closely related to the number of reactive NH groups on the amine crosslinking agent molecule.

[0045] In this invention, the only byproduct of efficient cross-linking during the thermosetting process in step S2 is water, which is environmentally friendly. In addition, the electrochromic polymer film after thermo-cross-linking forms a stable three-dimensional network structure, which gives it excellent solvent resistance (insoluble in dichloromethane), while exhibiting high contrast, good mechanical strength and outstanding electrochemical cycling stability, making it suitable for high-performance electrochromic devices.

[0046] In this invention, the molar ratio of epoxy groups on the thermally crosslinkable high-permeability electrochromic polymer to reactive active NH groups on the amine crosslinking agent molecule in the mixed solution in step S2 is preferably 1:1.

[0047] In this invention, the substrate mentioned in step S2 preferably includes one of ITO glass, FTO glass, ITO-PET composite film and FTO-PET composite film.

[0048] In this invention, the coating method described in step S2 preferably includes one or more of spraying, spin coating and screen printing.

[0049] In this invention, starting from the design of the material system, a strategy is proposed to combine electrochromic functional units with epoxy thermal crosslinking structures. By constructing a non-conjugated main chain and introducing color-changing units (carbazole derivatives) and thermal crosslinking units (epoxy groups) into the side chains, the solubility and film-forming processability of the polymer are improved first, and then a stable three-dimensional crosslinking network is formed through thermal curing. This simultaneously improves the mechanical strength, adhesion and electrochemical stability of the electrochromic polymer film, and finally obtains an electrochromic polymer film with high transparency in the neutral state, bright color in the colored state and excellent comprehensive performance.

[0050] In this invention, the side chains of the thermally crosslinkable, highly transparent electrochromic polymer contain carbazole color-changing units and epoxy groups. The amine compounds used as crosslinking agents are safe, inexpensive, and diverse. Through a simple solution processing and thermosetting process, a crosslinked network film, i.e., an electrochromic polymer film, can be formed on a conductive substrate. This method has a simple synthesis route and mild processing conditions. By thermally crosslinking a mixed solution, an electrochromic polymer film with a crosslinked network structure, excellent performance, and suitable for large-scale production is prepared, which can achieve reversible conversion between a highly transparent state and a dark (purple-blue) state. The electrochromic polymer film exhibits high transparency and colorlessness in the neutral state and can reversibly turn into a purple-blue state after applying voltage.

[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] Preparation of thermally crosslinkable, highly permeable electrochromic polymers: 1) 13.2 mmol / L dimethoxy-9H-carbazole, 14.5 mmol / L m-bromostyrene, 0.53 mmol / L 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (X-Phos), 0.26 mmol / L Pd2(dba)3 catalyst, 26.4 mmol / L sodium tert-butoxide (t-BuONa), and 16 mL anhydrous toluene were mixed and heated at 110 °C for 14 h. The reaction product was then cooled to room temperature and extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and finally purified by column chromatography using dichloromethane and n-hexane in a 1:5 volume ratio. The purified product was crystallized from the eluent to give 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole (yellow solid). The yield was 41%. 2) Mix 2.10 mmol of 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole obtained in step 1) with glycidyl methacrylate. 2.10 mmol was added to a 35 mL reaction tube, followed by 2.52 mmol of azobisisobutyronitrile (AIBN), and finally 10 mL of tetrahydrofuran (THF). The mixture was stirred until dissolved. The polymerization reaction was then carried out under nitrogen atmosphere and at 75 °C for 48 h with stirring. Subsequently, the reaction product was precipitated in methanol (200 mL), and the solid product was collected by filtration. Finally, the solid product was purified by Soxhlet extraction with methanol to obtain a thermally crosslinkable, highly permeable electrochromic polymer (pale yellow solid). .

[0054] Preparation of electrochromic polymer films: S1: Dissolve the thermally crosslinkable high-permeability electrochromic polymer and polyethyleneimine (PEI) prepared above in chloroform at a mass ratio of 10:1 to obtain a mixed solution with a mass-volume concentration of 10 mg / mL. S2: The mixed solution obtained in S1 is sprayed onto the surface of the ITO substrate and then thermally cured in an argon atmosphere and a tube furnace at 150°C for 5 h to form a dense cross-linked network. Finally, the uncross-linked part is washed away with dichloromethane to obtain an electrochromic polymer film (denoted as Cz+GMA-0.1PEI).

[0055] The 1H NMR characterization data of the thermally crosslinkable, highly permeable electrochromic polymer in Example 1 are as follows: Figure 1 As shown, from Figure 1 This demonstrates the successful synthesis of copolymers of epoxy crosslinking units and color-changing units.

[0056] The electrochromic performance of the electrochromic polymer film prepared in Example 1 was tested: using an electrochemical workstation coupled with a UV-Vis spectrophotometer, the cyclic voltammetry curves, UV-Vis absorption and chromaticity diagrams at different voltages, transmittance spectra at a specific wavelength (764 nm), response time, and stability of the film under a step voltage were measured in a 0.1 mol / L mixed solution of tetrabutylammonium hexafluorophosphate and acetonitrile. The data processing results are as follows: Figures 2-4 As shown.

[0057] Figure 2 This is a cyclic voltammogram of the electrochromic polymer film prepared in this embodiment; from Figure 2 As can be seen, the oxidation voltage of the electrochromic polymer film Cz+GMA-0.1PEI is 1.0 V, which indicates good electrochemical behavior.

[0058] Figure 3 The images show the UV-Vis absorption spectra of the electrochromic polymer film prepared in this embodiment under different voltages; from Figure 3It can be seen that the electrochromic polymer film is colorless and highly transparent in the neutral state, and turns purple-blue under oxidation voltage, exhibiting electrochromic properties with high optical contrast from colorless to colored.

[0059] Figure 4 The graph shows the transmittance of the electrochromic polymer film Cz+GMA-0.1PEI prepared in this embodiment as a function of time under multiple potential steps from 0 to 1.3 V at a wavelength of 764 nm; Figure 4 As can be seen, the electrochromic polymer film retains 50.1% of its contrast after 100 cycles in the stability test at this wavelength.

[0060] In summary, the electrochromic polymer film Cz+GMA-0.1PEI prepared in this invention exhibits excellent electrochemical behavior and electrochromic properties. This result strongly demonstrates that by copolymerizing epoxy functional units with chromogenic groups and preparing polymers with non-conjugated backbones, not only can neutral, colorless, and highly transparent electrochromic polymer films be prepared, but also polymer materials with excellent electrochromic properties can be obtained by constructing cross-linked networks.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A thermally crosslinkable, highly permeable electrochromic polymer, characterized in that, The structural formula of the thermally crosslinkable, highly permeable electrochromic polymer is shown in Formula I: ； In Equation I, x and y represent the degree of aggregation, and x and y are independent integers from 5 to 15.

2. A method for preparing a thermally crosslinkable, highly permeable electrochromic polymer as described in claim 1, characterized in that, Includes the following steps: 1) Dimethoxy-9H-carbazole, m-bromostyrene, dialkylbiarylphosphine ligand, first catalyst, organic salt and first organic solvent are mixed and heated to obtain 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole; 2) 3,6-Dimethoxy-9-(3-vinylphenyl)-9H-carbazole, glycidyl methacrylate, a second catalyst, and a second organic solvent are mixed and polymerized to obtain the thermally crosslinkable, highly permeable electrochromic polymer shown in Formula I. The structural formula of the 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole is shown in Formula II: 。 3. The method for preparing a thermally crosslinkable, highly permeable electrochromic polymer according to claim 2, characterized in that, In step 1), the molar ratio of dimethoxy-9H-carbazole, m-bromostyrene, dialkylbiarylphosphine ligand, first catalyst, and organic salt is 1:1~1.3:0.04~0.048:0.01~0.1:2~10. The dialkyl arylphosphine ligands mentioned in step 1) include one or more of 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, and 2-dicyclohexylphosphine-2',6'-diisopropoxybiphenyl. The first catalyst comprises one or more of tris(dibenzylacetone)palladium, tetra(triphenylphosphine)palladium, and [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) dichloride; The organic salt includes potassium tert-butoxide and / or sodium tert-butoxide; The first organic solvent includes one or more of toluene, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

4. The method for preparing a thermally crosslinkable, highly permeable electrochromic polymer according to claim 3, characterized in that, The heating reaction in step 1) is carried out at a temperature of 110~120℃ for 12~15 h.

5. A method for preparing a thermally crosslinkable, highly permeable electrochromic polymer according to any one of claims 2 to 4, characterized in that, In step 2), the molar ratio of 3,6-dimethoxy-9-(3-vinylphenyl)-9H-carbazole, glycidyl methacrylate, and the second catalyst is 1:0.8~1.1:1~1.

5. In step 2), the second catalyst includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide; The second organic solvent includes acetone and / or tetrahydrofuran.

6. The method for preparing a thermally crosslinkable, highly permeable electrochromic polymer according to claim 5, characterized in that, The polymerization reaction in step 2) is carried out at a temperature of 60-80°C for 36-50 h.

7. An electrochromic polymer film, characterized in that, It is prepared from the thermally crosslinkable, highly permeable electrochromic polymer described in claim 1; The method for preparing the electrochromic polymer film includes the following steps: S1: Mix the thermally crosslinkable, highly permeable electrochromic polymer shown in Formula I, an amine crosslinking agent, and a third organic solvent to obtain a mixed solution; S2: The mixed solution is coated onto the surface of the substrate and then thermally cured to obtain an electrochromic polymer film.

8. The electrochromic polymer film according to claim 7, characterized in that, The mass ratio of the thermally crosslinkable, highly permeable electrochromic polymer to the amine crosslinking agent in step S1 is 10:1~3; The mass-volume concentration of the mixed solution is 5~20 mg / mL; The amine crosslinking agent includes one or more of 4,4'-diaminodiphenylmethane, tetraethylenepentamine, and polyethyleneimine; The third organic solvent includes one or more of dichloromethane, trichloromethane, and tetrahydrofuran.

9. The electrochromic polymer film according to claim 8, characterized in that, The thermosetting atmosphere in step S2 is an inert atmosphere, the temperature is 120~170℃, and the time is 4~5.5 h.

10. The electrochromic polymer film according to claim 9, characterized in that, The substrate mentioned in step S2 includes one of ITO glass, FTO glass, ITO-PET composite film, and FTO-PET composite film.

Images