Polyimides containing dibenzofuran / dibenzothiophene and triphenylamine structures, and methods of making and using the same

Abstract

Polyimide containing dibenzofuran (thiophene) and triphenylamine structure and preparation method and application thereof, and application thereof, the present application relates to polyimide containing dibenzofuran (thiophene) and triphenylamine structure and preparation method and application thereof. In order to solve the problem of low solubility of aromatic polyimide in organic solvent, poor optical contrast, slow response time and poor capacitor performance, 2,8-dibromodibenzofuran (thiophene) is used as raw material, and 4-methoxy-4'-nitrodiphenylamine is reacted to obtain a new precursor containing dibenzofuran (thiophene) and triphenylamine structure. The nitro group is reduced to obtain a diamine monomer, which is polymerized with dianhydride to form a new high-performance polyimide. At the same time, the polymer has excellent electrochromic performance, including excellent cycle stability, fast switching time, high optical contrast and low voltage start. It also has excellent capacitor performance, including excellent specific capacity and cycle stability. The present application is expected to be applied in the field of electrochromic supercapacitor.

Description

Technical Field

[0001] This invention relates to a polyimide containing a dibenzofuran / dibenzothiophene and triphenylamine structure, its preparation method, and its application. Background Technology

[0002] Electrochromic materials are materials whose optical properties, including reflectivity, transmittance, and absorptivity, undergo stable and reversible color changes under the influence of an applied electric field. As a cutting-edge energy-saving smart material, electrochromic materials can be applied in energy storage materials and devices. However, designing and synthesizing electrochromic-supercapacitor materials with high optical contrast, fast response time, and high capacitor performance still faces significant challenges.

[0003] Triphenylamine has a helical structure, which provides stability and electrochemical properties. Introducing the triphenylamine structure into high-performance polyimides allows the helical structure to effectively break the orderly stacking of polyimide molecular chains. Without compromising the thermal stability of the polyimide material, this structure enhances its solubility and film-forming ability, making it easier to process.

[0004] Dibenzofuran / dibenzothiophene is an oxygen-containing (sulfur-containing) heterocyclic aromatic hydrocarbon formed by the fusion of two benzene rings through an oxygen (sulfur) atom. Due to its unique atomic arrangement and electronic structure, its heterocyclic skeleton combines the stability of aromatic rings with the electronic regulation characteristics of heteroatoms. It is easy to form charge transfer with other conjugated units, making it a classic structural unit in the fields of organic optoelectronics, electrochemistry, and polymer synthesis.

[0005] This invention designs and synthesizes a novel polyimide with a dibenzofuran (thiophene) containing an oxygen (sulfur) heterocycle as the central core and triphenylamine as the terminal, in order to obtain electrochromic supercapacitor materials and devices with good film-forming properties, fast response time, and good capacitor performance. Summary of the Invention

[0006] This invention addresses the problems of low solubility, poor optical contrast, slow response time, and poor capacitor performance of aromatic polyimides in electrochromic materials in organic solvents. It proposes a method for preparing polyimides containing dibenzofuran / dibenzothiophene and triphenylamine units and their application in electrochromic supercapacitors. The polyimides obtained by condensing two diamine monomers containing dibenzofuran / dibenzothiophene (DBF-TPA-NH2 or DBT-TPA-NH2) with other commonly available dianhydride monomers (dianhydrides can be 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, pyromellitic tetracarboxylic anhydride, 4,4'-hexafluoroisopropylphthalic anhydride) have the following structural formulas:

[0007] In the formula, n is an integer from 3 to 20.

[0008] 2. The preparation method of the polyimide synthesized by DBF-TPA-NH2 or DBT-TPA-NH2 according to the present invention is carried out according to the following steps: I. Synthesis of two monomers: DBF-TPA-NH2 or DBT-TPA-NH2: ① Under a nitrogen atmosphere, 4-methoxy-4'-nitrodiphenylamine, 2,8-dibromodibenzofuran or 2,8-dibromodibenzothiophene, copper powder, potassium carbonate, 18-crown-6-ether, and o-dichlorobenzene were added to a three-necked round-bottom flask. The reaction system was slowly heated to 165°C with continuous stirring. Thin-plate chromatography was used to determine whether the reaction was complete. After the reaction was complete, the reaction solution was filtered while hot. The filtrate was cooled to room temperature and poured into a large amount of petroleum ether to precipitate. The precipitate was filtered off and washed with a large amount of distilled water. The product was dried under vacuum. The crude product was separated by silica gel column chromatography and dried under vacuum to obtain an orange solid, namely 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzofuran or 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzothiophene, named DBF-TPA-NO2 or DBT-TPA-NO2.

[0009] The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 2,8-dibromodibenzofuran or 2,8-dibromodibenzothiophene in step 1① is 1.1:1; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of copper powder in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of potassium carbonate in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 18-crown-6-ether in step 1① is 1:0.4; The vacuum drying temperature in step 1① is 45°C, the vacuum drying time is 36 hours, and the vacuum drying pressure is -30~-29KPa; ② Under a nitrogen atmosphere, DBF-TPA-NO2 (or DBT-TPA-NO2), palladium on carbon, and anhydrous ethanol are added to a three-necked round-bottom flask. Hydrazine hydrate is added dropwise to the stirred reaction system at a rate of 1-2 drops per second through a constant-pressure separatory funnel. The temperature is raised to the boiling point of ethanol, and the reaction is maintained at this temperature for 10-14 hours. Thin-plate chromatography is used to determine if the reaction is complete. After the reaction is complete, the mixture is filtered while hot. The resulting filtrate is poured into a large amount of saturated sodium chloride solution and stirred continuously to precipitate a solid. The solid product is collected by filtration and dried under vacuum under a nitrogen atmosphere to obtain a green solid, named DBF-TPA-NH2 or DBT-TPA-NH2. In step 1②, the ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the amount of palladium on carbon is 4:1; The ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the volume of anhydrous ethanol in step 1② is 1 mmol: (100~120) mL. The ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the volume of hydrazine hydrate in step 1② is 1 mmol: 5 mL; The Pd / C mentioned in step 1② is a Pd-doped C composite material, and the mass fraction of Pd in ​​Pd / C is 10%; II. Preparation of polyimides containing DBF-TPA-NH2 or DBT-TPA-NH2: The above-mentioned dianhydride monomer was completely dissolved in anhydrous N,N-dimethylacetamide to prepare an acid anhydride solution. Under a nitrogen atmosphere, the acid anhydride solution was added dropwise at a rate of 1-2 drops per second through a constant-pressure dropping funnel to a stirred three-necked round-bottom flask containing DBF-TPA-NH2 or DBT-TPA-NH2 and anhydrous N,N-dimethylacetamide. The mixture was stirred at room temperature for 10-12 hours. Subsequently, pyridine and acetic anhydride were added dropwise to the stirred reaction system at a rate of 1-2 drops per second using a syringe. The temperature was raised to 120°C and stirred for 7-9 hours. After the reaction was completed, the mixture was cooled to room temperature, and the resulting filtrate was poured into a large amount of methanol. The mixture was stirred continuously, and a solid precipitated. The solid product was collected by filtration, washed with distillation and methanol, and then vacuum dried. The product was then subjected to Soxhlet extraction with methanol and vacuum dried to obtain the final product. In step two, the molar ratio of DBF-TPA-NH2 or DBT-TPA-NH2 to the dianhydride monomer is 1:1. In step two, the ratio of the amount of DBF-TPA-NH2 or DBT-TPA-NH2 to the volume of pyridine is 1 mmol: 4 mL. In step two, the molar ratio of DBF-TPA-NH2 or DBT-TPA-NH2 to the volume of acetic anhydride is 1 mmol: 7 mL. The dianhydride monomers mentioned in step two are 3,3',4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, pyromellitic acid anhydride, 4,4'-hexafluoroisopropylphthalic acid anhydride, and other dianhydride monomers.

[0010] This invention relates to a polyimide containing dibenzofuran (thiophene) and triphenylamine units, which is used as an electrochromic supercapacitor material and applied in the field of electrochromic supercapacitors.

[0011] This invention aims to develop polyimide materials with excellent combined electrochromic and supercapacitor properties, addressing the problems of low solubility, poor optical contrast, slow response time, and poor capacitor performance inherent in polyimides. A novel molecular structure is synthesized by introducing a helical triphenylamine unit and dibenzofuran (thiophene), which possesses photoelectric properties. The large steric hindrance of triphenylamine increases the solubility of polyimide, while the rapid electron transport characteristics of the oxygen (sulfur)-containing heterocycle of dibenzofuran (thiophene) improve the optical contrast, response time, and capacitor performance of polyimide. Combining these advantages, a triphenylamine-based polyimide containing a dibenzofuran (thiophene) structure is prepared, exhibiting good solubility, electrochromic properties, and capacitor performance, demonstrating excellent performance in electrochromic supercapacitor applications.

[0012] The present invention has the following beneficial effects: I. The polyimide of this invention possesses excellent electrochromic properties. The polyimide of this invention exhibits a significant color change, transitioning from colorless in the neutral state to a deep blue in the oxidized state. When the applied voltage varies between 0 and 1.4 V, the coloring time of the polyimide is 1.8–3.4 seconds, and the bleaching time is 0.9–2.4 seconds; it also exhibits high optical contrast, reaching a maximum of 71%. The naphthalene-containing polyimide prepared by this invention demonstrates excellent cycling stability; after 5000 seconds of cycling, the optical contrast decreases by only 16%, exhibiting superior electrochromic stability.

[0013] II. The polyimide of this invention has excellent capacitor properties. Capacitor performance is another important performance indicator for electrochromic supercapacitor materials. The polyimide of this invention exhibits excellent specific capacitance, at 1 A g / L. -1 The specific capacitance at current density is 154.6~212.3 F g. -1 The polyimide prepared by this invention exhibits excellent capacitance retention, maintaining 69-75% capacitance after 3000 charge-discharge cycles, demonstrating superior capacitor performance. Attached Figure Description

[0014] Figure 1 The hydrogen nuclear magnetic resonance spectrum of DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Example 1; Figure 2 The above are the proton NMR spectra of the polyimides synthesized from DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Examples 1 to 4. Figure 3 Thermogravimetric curves of the polyimides synthesized from DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Examples 1 to 4 are shown. Figure 4 Cyclic voltammetry diagrams of polyimides synthesized from DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Examples 1 to 4; Figure 5 Electrochromic images of the polyimides synthesized from DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Examples 1 to 4; Figure 6 Optical contrast images of the polyimides synthesized from DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Examples 1 to 4; Figure 7 The switching time diagrams are for the polyimides synthesized from DBT-TPA-NH2 / DBF-TPA-NH2 prepared in Examples 1 to 4. Figure 8 The polyimides prepared in Examples 1 to 4 using DBT-TPA-NH2 / DBF-TPA-NH2 were synthesized in 1A g. -1 up to 20A g -1 The constant current charge-discharge curve; Figure 9 The polyimides prepared in Examples 1 to 4 using DBT-TPA-NH2 / DBF-TPA-NH2 were synthesized in 10A g. -1 Cyclic stability test results at current density. Detailed Implementation

[0015] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0016] Specific Implementation Method 1: The structural formulas of the polyimide containing dibenzofuran (thiophene) and triphenylamine units in this implementation method are as follows:

[0017] monomer

[0018] polyimide In the formula, n is an integer from 3 to 20; The present invention has the following beneficial effects: I. The polymer of this invention possesses excellent electrochromic properties. The polyimide of this invention exhibits a significant color change, transitioning from colorless in the neutral state to a deep blue in the oxidized state. When the applied voltage varies between 0 and 1.4 V, the coloring time of the polyimide is 1.8–3.4 seconds, and the bleaching time is 0.9–2.4 seconds; it also exhibits high optical contrast, reaching a maximum of 71%. The naphthalene-containing polyimide prepared by this invention demonstrates excellent cycling stability; after 5000 seconds of cycling, the optical contrast decreases by only 16%, exhibiting superior electrochromic stability.

[0019] II. The polymer of this invention exhibits excellent supercapacitor performance. Supercapacitor performance is another important performance indicator for electrochromic supercapacitor materials. The polyimide of this invention exhibits excellent specific capacitance, reaching 1 A g / L. -1 The specific capacitance at current density is 154.6~212.3 F g. -1 The polyimide prepared by this invention exhibits excellent capacitance retention, maintaining 69-75% capacitance after 3000 charge-discharge cycles, demonstrating superior capacitor performance.

[0020] Specific Implementation Method Two: The preparation method of the polyimide synthesized using DBT-TPA-NH2 or DBT-TPA-NH2 in this implementation method is as follows: I. Synthesis of DBF-TPA-NH2 / DBT-TPA-NH2 monomers: ① Under a nitrogen atmosphere, 4-methoxy-4'-nitrodiphenylamine, 2,8-dibromodibenzofuran or 2,8-dibromodibenzothiophene, copper powder, potassium carbonate, 18-crown-6-ether, and o-dichlorobenzene were added to a three-necked round-bottom flask. The reaction system was slowly heated to 165°C with continuous stirring. Thin-plate chromatography was used to determine whether the reaction was complete. After the reaction was complete, the reaction solution was filtered while hot. The filtrate was cooled to room temperature and poured into a large amount of petroleum ether to precipitate. The precipitate was filtered off and washed with a large amount of distilled water. The product was dried under vacuum. The crude product was separated by silica gel column chromatography and dried under vacuum to obtain an orange solid, namely 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzofuran or 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzothiophene, named DBF-TPA-NO2 or DBT-TPA-NO2.

[0021] The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 2,8-dibromodibenzofuran or 2,8-dibromodibenzothiophene in step 1① is 1.1:1; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of copper powder in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of potassium carbonate in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 18-crown-6-ether in step 1① is 1:0.4; The vacuum drying temperature in step 1① is 45°C, the vacuum drying time is 36 hours, and the vacuum drying pressure is -30~-29KPa; ② Under a nitrogen atmosphere, add DBF-TPA-NO2 or DBT-TPA-NO2, palladium on carbon, and anhydrous ethanol to a three-necked round-bottom flask. Add hydrazine hydrate dropwise to the stirred reaction system at a rate of 1-2 drops per second using a constant-pressure separatory funnel. Heat to the boiling point of ethanol and maintain the temperature for 10-14 hours. Use thin-plate chromatography to determine if the reaction is complete. After the reaction is complete, filter while hot. Pour the filtrate into a large amount of saturated sodium chloride solution and stir continuously to precipitate a solid. Collect the solid product by filtration and vacuum dry it under a nitrogen atmosphere to obtain a green solid, named DBF-TPA-NH2 or DBT-TPA-NH2. In step 1②, the ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the amount of palladium on carbon is 4:1; The ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the volume of anhydrous ethanol in step 1② is 1 mmol: (100~120) mL. The ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the volume of hydrazine hydrate in step 1② is 1 mmol: 5 mL; The Pd / C mentioned in step 1② is a Pd-doped C composite material, and the mass fraction of Pd in ​​Pd / C is 10%; II. Preparation of polyimides containing DBF-TPA-NH2 or DBT-TPA-NH2: A dianhydride monomer was completely dissolved in anhydrous N,N-dimethylacetamide to prepare an acid anhydride solution. Under a nitrogen atmosphere, this acid anhydride solution was added dropwise at a rate of 1-2 drops per second through a constant-pressure dropping funnel to a stirred three-necked round-bottom flask containing DBF-TPA-NH2 or DBT-TPA-NH2 and anhydrous N,N-dimethylacetamide. The mixture was stirred at room temperature for 10-12 hours. Subsequently, pyridine and acetic anhydride were added dropwise to the stirred reaction system at a rate of 1-2 drops per second using a syringe. The temperature was raised to 120°C, and the mixture was stirred for 7-9 hours. After the reaction was completed, the mixture was cooled to room temperature, and the resulting filtrate was poured into a large amount of methanol. The mixture was stirred continuously, and a solid precipitated. The solid product was collected by filtration, washed with distillation and methanol, and then vacuum dried. The product was then subjected to Soxhlet extraction with methanol and vacuum dried to obtain the final product. In step two, the molar ratio of DBF-TPA-NH2 or DBT-TPA-NH2 to the diacid monomer is 1:1. In step two, the ratio of the amount of DBF-TPA-NH2 or DBT-TPA-NH2 to the volume of pyridine is 1 mmol: 4 mL. In step two, the ratio of the amount of DBF-TPA-NH2 or DBT-TPA-NH2 to the volume of acetic anhydride is 1 mmol: 7 mL.

[0022] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that: the diacid monomers mentioned in step 2 are 3,3',4,4'-diphenylsulfone tetracarboxylic acid diacid anhydride, 1,4,5,8-naphthalene tetracarboxylic anhydride, and DBF-TPA-NH2 or DBT-TPA-NH2, respectively, to prepare polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA.

[0023] Specific Implementation Method 4: This implementation method describes the application of polyimide containing dibenzofuran (thiophene) and triphenylamine units as an electrochromic layer in an electrochromic supercapacitor.

[0024] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Two in that the application of polyimide containing dibenzofuran (thiophene) and triphenylamine units as an electrochromic layer in an electrochromic supercapacitor is carried out according to the following steps: A polyimide containing dibenzofuran (thiophene) and triphenylamine structures is used as the electrochromic layer in an electrochromic supercapacitor. The electrochromic layer is coated on a conductive substrate to prepare the electrochromic supercapacitor. The electrochromic layer produces electrochromic changes under the action of an external electric field. Other steps and parameters are the same as in specific implementation scheme two.

[0025] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the conductive substrate is conductive glass, ITO conductive resin film, transparent silver nanowires, or transparent carbon nanotube electrodes. Other steps and parameters are the same as in Specific Implementation Method Two or Three.

[0026] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Five in that the voltage of the external electric field is 0~3V.

[0027] The beneficial effects of the present invention are verified using the following embodiments: Example 1: The structural formula of the polyimide DBT-TPA-NTCDA synthesized from DBT-TPA-NH2 / DBT-TPA-NH2 is as follows:

[0028] In the formula, n is an integer from 3 to 20; The preparation method of polyimide DBT-TPA-NTCDA synthesized using DBT-TPA-NH2 in this embodiment is as follows: I. Synthesis of DBF-TPA-NH2 / DBT-TPA-NH2 monomers: ① Under a nitrogen atmosphere, 4-methoxy-4'-nitrodiphenylamine, 2,8-dibromodibenzothiophene, copper powder, potassium carbonate, 18-crown-6-ether, and o-dichlorobenzene were added to a three-necked round-bottom flask. The reaction system was slowly heated to 165°C with continuous stirring. Thin-plate chromatography was used to determine whether the reaction was complete. After the reaction was complete, the reaction solution was filtered while hot. The filtrate was cooled to room temperature and poured into a large amount of petroleum ether to precipitate. The precipitate was filtered off and washed with a large amount of distilled water. The product was dried under vacuum. The crude product was separated by silica gel column chromatography and dried under vacuum to obtain an orange solid, namely 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzothiophene, named DBT-TPA-NO2.

[0029] The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 2,8-dibromodibenzothiophene in step 1① is 1.1:1; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of copper powder in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of potassium carbonate in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 18-crown-6-ether in step 1① is 1:0.4; The vacuum drying temperature in step 1① is 45°C, the vacuum drying time is 36 hours, and the vacuum drying pressure is -30~-29KPa; ② Under a nitrogen atmosphere, DBT-TPA-NO2, palladium on carbon, and anhydrous ethanol were added to a three-necked round-bottom flask. Hydrazine hydrate was added dropwise to the stirred reaction system at a rate of 1-2 drops per second through a constant-pressure separatory funnel. The temperature was raised to the boiling point of ethanol, and the reaction was maintained at this temperature for 10-14 hours. Thin-plate chromatography was used to determine whether the reaction was complete. After the reaction was complete, the mixture was filtered while hot, and the filtrate was poured into a large amount of saturated sodium chloride solution. Stirring was continued, and a solid precipitated. The solid product was collected by filtration and dried under vacuum under a nitrogen atmosphere to obtain a green solid, named DBT-TPA-NH2. In step 1②, the ratio of the amount of DBT-TPA-NO2 to the amount of palladium on carbon is 4:1; The ratio of the amount of DBT-TPA-NO2 to the volume of anhydrous ethanol in step 1② is 1 mmol: (100~120) mL; The ratio of the amount of DBT-TPA-NO2 to the volume of hydrazine hydrate in step 1② is 1 mmol: 5 mL; The Pd / C mentioned in step 1② is a Pd-doped C composite material, and the mass fraction of Pd in ​​Pd / C is 10%; II. Preparation of polyimides containing DBT-TPA-NH2: A dianhydride monomer was completely dissolved in anhydrous N,N-dimethylacetamide to prepare an acid anhydride solution. Under a nitrogen atmosphere, this acid anhydride solution was added dropwise at a rate of 1-2 drops per second through a constant-pressure dropping funnel to a stirred three-necked round-bottom flask containing DBT-TPA-NH2 and anhydrous N,N-dimethylacetamide. The mixture was stirred at room temperature for 10-12 hours. Subsequently, pyridine and acetic anhydride were added dropwise to the stirred reaction system at a rate of 1-2 drops per second using a syringe. The temperature was raised to 120°C, and the mixture was stirred for 7-9 hours. After the reaction was completed, the mixture was cooled to room temperature, and the resulting filtrate was poured into a large amount of methanol. The mixture was stirred continuously, and a solid precipitated. The solid product was collected by filtration, washed with distillation and methanol, and then vacuum dried. The product was then subjected to Soxhlet extraction with methanol and vacuum dried to obtain the final product. The molar ratio of DBT-TPA-NH2 to the diacid monomer in step two is 1:1; In step two, the molar ratio of DBT-TPA-NH2 to the volume of pyridine is 1 mmol: 4 mL. In step two, the molar ratio of DBT-TPA-NH2 to the volume of acetic anhydride is 1 mmol: 7 mL. The dianhydride monomer mentioned in step two is 1,4,5,8-naphthalenetetracarboxylic anhydride.

[0030] The structure of the polyimide DBT-TPA-DSDA synthesized in Example 2 using DBT-TPA-NH2 is similar to that of DBT-TPA-NTCDA in Example 1.

[0031] The specific preparation method of DBT-TPA-DSDA is the same as that of DBT-TPA-NTCDA in Example 1. The difference is that in Example 2, 3,3',4,4'-diphenylsulfone tetracarboxylic anhydride is used instead of 1,4,5,8-naphthalenetetracarboxylic anhydride.

[0032] The structure of the polyimide DBF-TPA-NTCDA synthesized in Example 3 using DBF-TPA-NH2 is similar to that of DBT-TPA-NTCDA in Example 1.

[0033] The specific preparation method of DBF-TPA-NTCDA is the same as that of DBT-TPA-NTCDA in Example 1, except that DBF is used instead of DBT as a three-purpose raw material.

[0034] The structure of the polyimide DBF-TPA-DSDA synthesized in Example 4 using DBF-TPA-NH2 is similar to that of DBT-TPA-NTCDA in Example 1.

[0035] The specific preparation method of DBF-TPA-DSDA is the same as that of DBT-TPA-NTCDA in Example 1. The difference is that in Example 4, DBF is used instead of DBT and DSDA is used instead of NTCDA.

[0036] Figure 1 The proton NMR spectra of the monomers DBT-TPA-NO2, DBF-TPA-NO2, DBT-TPA-NH2, and DBF-TPA-NH2 prepared in Example 1 demonstrate the successful synthesis of the monomers. Figure 2 The hydrogen nuclear magnetic resonance spectra of the four polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA prepared by DBT-TPA-NH2 in Examples 1 to 4 are shown. Figure 2 The values ​​of 9.37-10.39 ppm represent the characteristic chemical shift of the -NHCO amide bond, 7.1-9.0 ppm represent the characteristic peak of the aromatic ring, 3.8-4.0 ppm represent the characteristic peak of the methoxy group, and 1.0-3.1 ppm represent the aliphatic region of the side chain. This indicates that the polyimide synthesized by DBT-TPA-NH2 in Examples 1 to 4 was successfully synthesized.

[0037] Figure 3The thermogravimetric curves of polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized from DBT-TPA-NH2 in Examples 1 to 4 are shown. Figure 3 It can be seen that the polyimides synthesized with DBT-TPA-NH2 exhibit thermal decomposition temperatures between 128 and 228°C under a nitrogen atmosphere with a 5% weight loss, indicating that these polyimides possess good thermodynamic stability. When the polyimides are heated to 800°C, the char residue ranges from 33 to 58°C, demonstrating the good thermal stability of the polyimides.

[0038] Figure 4 Cyclic voltammograms of polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized from DBT-TPA-NH2 in Examples 1 to 4 are shown. Figure 4 It can be seen that DBT-TPA-NTCDA showed an oxidation peak at 0.97V and a reduction peak at 0.32V; DBT-TPA-DSDA showed an oxidation peak at 1.12V and a reduction peak at 0.15V; DBF-TPA-NTCDA showed an oxidation peak at 0.42V and a reduction peak at -0.25V; DBF-TPA-DSDA showed an oxidation peak at 0.99V and a reduction peak at 0.35V; indicating that the polyimides prepared in Examples 1 to 4 underwent redox reactions under applied voltage.

[0039] Figure 5 Electrochromic images of the polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized from DBT-TPA-NH2 in Examples 1 to 4; from Figure 5 It can be seen that, between 0 and 1.4V, the absorption peak at 356nm gradually decreases while the absorption peaks at 648nm and 809nm gradually increase with the increase of voltage; when applied to 1.1V, the color of the film turns dark blue.

[0040] Figure 6 Optical contrast images of the polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized with DBT-TPA-NH2 in Examples 1 to 4 are shown. Figure 6It can be seen that the optical contrast of DBT-TPA-NTCDA is 71%, and it still remains at 56% after 5000 seconds of cycling, indicating that the polyimide synthesized with DBT-TPA-NH2 has high optical contrast and excellent cycling stability.

[0041] Figure 7 The following are on / off time diagrams of the polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized from DBT-TPA-NH2 in Examples 1 to 4; from Figure 7 It can be seen that the coloring time of DBT-TPA-NTCDA is 3.3 seconds and the bleaching time is 0.9 seconds, indicating that the polyimide synthesized with DBT-TPA-NH2 has a fast switching response.

[0042] Figure 8 The polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized with DBT-TPA-NH2 as described in Examples 1 to 4 were prepared in 1A g. -1 up to 20A g -1 Constant current charge-discharge curve; from Figure 8 It can be seen that the specific capacitance of DBT-TPA-NTCDA is within 1A g -1 2A g -1 5A g -1 10A g -1 and 20A g -1 The values ​​at current densities are 212.3 F g. -1 201.1F g -1 193.9F g -1 180.1F g -1 174.1F g -1 The capacitance retention rate was 82%, indicating that the polyimide synthesized with DBT-TPA-NH2 has high specific capacitance and excellent capacitance retention rate.

[0043] Figure 9 The polyimides DBT-TPA-NTCDA, DBT-TPA-DSDA, DBF-TPA-NTCDA, and DBF-TPA-DSDA synthesized with DBT-TPA-NH2 as described in Examples 1 to 4 were prepared at 10A g. -1 Cyclic stability test results at current density. From Figure 9 It can be seen that DBT-TPA-NTCDA retains 75% of its capacitance after 3000 charge-discharge cycles. This indicates that the polyimide synthesized from DBT-TPA-NH2 has excellent capacitance cycling stability.

Claims

1. The diamine monomers are 2,8-bis[4-nitrophenyl(4-methoxyphenyl)amino]dibenzofuran and 2,8-bis[4-nitrophenyl(4-methoxyphenyl)amino]dibenzothiophene (abbreviated as DBF-TPA-NH2 / DBT-TPA-NH2). The monomer is characterized by containing dibenzofuran / dibenzothiophene and triphenylamine, as shown in the figure:

2. A polyimide synthesized using DBF-TPA-NH2 / DBT-TPA-NH2, characterized in that... Polyimide obtained by polymerizing DBF-TPA-NH2 or DBT-TPA-NH2 with dianhydride monomers; the dianhydride monomers include, but are not limited to, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, pyromellitic anhydride, 4,4'-hexafluoroisopropylphthalic anhydride, etc. The structural formula of the prepared polyimide is as follows: In the formula, n is an integer from 3 to 20.

3. The method for preparing polyimide synthesized from DBF-TPA-NH2 or DBT-TPA-NH2 as described in claim 2, characterized in that... The preparation method is as follows: I. Synthesis of DBF-TPA-NH2 or DBT-TPA-NH2 monomers: ① Under a nitrogen atmosphere, 4-methoxy-4'-nitrodiphenylamine, 2,8-dibromodibenzofuran or 2,8-dibromodibenzothiophene, copper powder, potassium carbonate, 18-crown-6-ether, and o-dichlorobenzene were added to a three-necked round-bottom flask. The reaction system was slowly heated to 165°C with continuous stirring. Thin-plate chromatography was used to determine whether the reaction was complete. After the reaction was complete, the reaction solution was filtered while hot. The filtrate was cooled to room temperature and poured into a large amount of petroleum ether to precipitate. The precipitate was filtered off and washed with a large amount of distilled water. The product was dried under vacuum. The crude product was separated by silica gel column chromatography and dried under vacuum to obtain an orange solid, namely 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzofuran or 2,8-bis[4-nitrophenyl(4-methoxyphenyl)nitro]dibenzothiophene, named DBF-TPA-NO2 or DBT-TPA-NO2. The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 2,8-dibromodibenzofuran or 2,8-dibromodibenzothiophene in step 1① is 1.1:1; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of copper powder in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of potassium carbonate in step 1① is 1:4; The ratio of the amount of 4-methoxy-4'-nitrodiphenylamine to the amount of 18-crown-6-ether in step 1① is 1:0.4; The vacuum drying temperature in step 1① is 45°C, the vacuum drying time is 36 hours, and the vacuum drying pressure is -30~-29KPa; ② Under a nitrogen atmosphere, add DBF-TPA-NO2 or DBT-TPA-NO2, palladium on carbon, and anhydrous ethanol to a three-necked round-bottom flask. Add hydrazine hydrate dropwise to the stirred reaction system at a rate of 1-2 drops per second using a constant-pressure separatory funnel. Heat to the boiling point of ethanol and maintain the temperature for 10-14 hours. Use thin-plate chromatography to determine if the reaction is complete. After the reaction is complete, filter while hot. Pour the filtrate into a large amount of saturated sodium chloride solution and stir continuously to precipitate a solid. Collect the solid product by filtration and vacuum dry it under a nitrogen atmosphere to obtain a green solid, named DBF-TPA-NH2 or DBT-TPA-NH2. In step 1②, the ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the amount of palladium on carbon is 4:1; The ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the volume of anhydrous ethanol in step 1② is 1 mmol: (100~120) mL. The ratio of the amount of DBF-TPA-NO2 or DBT-TPA-NO2 to the volume of hydrazine hydrate in step 1② is 1 mmol: 5 mL; The Pd / C mentioned in step 1② is a Pd-doped C composite material, and the mass fraction of Pd in ​​Pd / C is 10%; II. Preparation of polyimides containing DBF-TPA-NH2 or DBT-TPA-NH2: A dianhydride monomer was completely dissolved in anhydrous N,N-dimethylacetamide to prepare an acid anhydride solution. Under a nitrogen atmosphere, this acid anhydride solution was added dropwise at a rate of 1-2 drops per second through a constant-pressure dropping funnel to a stirred three-necked round-bottom flask containing DBF-TPA-NH2 or DBT-TPA-NH2 and anhydrous N,N-dimethylacetamide. The mixture was stirred at room temperature for 10-12 hours. Subsequently, pyridine and acetic anhydride were added dropwise to the stirred reaction system at a rate of 1-2 drops per second using a syringe. The temperature was raised to 120°C, and the mixture was stirred for 7-9 hours. After the reaction was completed, the mixture was cooled to room temperature, and the resulting filtrate was poured into a large amount of methanol. The mixture was stirred continuously, and a solid precipitated. The solid product was collected by filtration, washed with distillation and methanol, and then vacuum dried. The product was then subjected to Soxhlet extraction with methanol and vacuum dried to obtain the final product. In step two, the molar ratio of DBF-TPA-NH2 or DBT-TPA-NH2 to the diacid monomer is 1:

1. In step two, the ratio of the amount of DBF-TPA-NH2 or DBT-TPA-NH2 to the volume of pyridine is 1 mmol: 4 mL. In step two, the molar ratio of DBF-TPA-NH2 or DBT-TPA-NH2 to the volume of acetic anhydride is 1 mmol: 7 mL. The dianhydride monomers mentioned in step two are 3,3',4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, pyromellitic acid anhydride, 4,4'-hexafluoroisopropylphthalic acid anhydride, and other dianhydride monomers.

4. The method for preparing polyimide synthesized from DBF-TPA-NH2 or DBT-TPA-NH2 according to claim 3, characterized in that... The dianhydride monomers mentioned in step two are 3,3',4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, pyromellitic acid anhydride, 4,4'-hexafluoroisopropylphthalic acid anhydride and other dianhydride monomers, which are used to prepare polyimides.

5. The application of the polyimide containing dibenzofuran (thiophene) and triphenylamine units as described in claim 3 as an electrochromic layer in an electrochromic supercapacitor.

6. The application of the polyimide containing dibenzofuran (thiophene) and triphenylamine units according to claim 5, characterized in that: Polyimide containing dibenzofuran (thiophene) and triphenylamine units is used as the electrochromic layer in an electrochromic supercapacitor. The electrochromic layer is coated on a conductive transparent electrode to prepare an active electrode, which exhibits electrochromic phenomenon under the action of an external electric field.

7. The application of the polyimide containing dibenzofuran (thiophene) and triphenylamine units according to claim 5, characterized in that... The voltage of the applied electric field is 0~3V.

8. The application of the polyimide containing dibenzofuran (thiophene) and triphenylamine units according to claim 5, characterized in that... The transparent electrode is an ITO (indium tin oxide), transparent silver nanowire, or transparent carbon nanotube electrode.

Images