Highly stable conjugated polymer electrochromic material capable of achieving neutral yellow-transparent state and its preparation and application
By introducing a cyclic ether structure into the benzene ring to modify the dibromobenzene ring monomer and copolymerize it with the thiophene derivative ProDOT monomer, a conjugated polymer electrochromic material with reduced oxidation potential and improved stability was prepared. This solves the problem of poor stability of existing yellow conjugated polymers and achieves fast response and high contrast electrochromic performance, which is suitable for applications such as smart windows and displays.
Patent Information
- Application Number
- CN202410800905.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-20
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2044-06-20
AI Technical Summary
Existing solution-processable yellow conjugated polymers have a high oxidation potential, resulting in poor redox stability, which affects their application in the field of electrochromic displays.
By introducing a cyclic ether structure into the benzene ring to modify the dibromobenzene ring monomer, and copolymerizing it with a thiophene derivative ProDOT monomer, a conjugated polymer electrochromic material is prepared to reduce the oxidation potential and improve the stability.
A stable and reversible transition from neutral yellow to transparent state was achieved. The polymer film exhibited fast response and high contrast under high cycle stability, and is suitable for smart windows, displays and other fields.
Smart Images
Figure CN118812492B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of electrochromic materials, and in particular to a high-stability conjugated polymer electrochromic material capable of achieving neutral yellow-transparent state, and the preparation and application thereof. Background Art
[0002] Electrochromic materials, as a new type of functional material, have gradually attracted widespread attention. In recent years, electrochromic displays, as a typical non-emissive (passive) display technology, have received widespread attention and are expected to become one of the next-generation displays. The key to applying electrochromic technology in the display field lies in full-color display. Compared to synthesizing materials that can switch between all colors, a "shortcut" to color control is to design and synthesize materials with three primary colors and then achieve full-color control through color mixing theory. Because electrochromism is a non-emissive technology, it must be achieved using the subtractive three primary colors (CMY or RGB). Researchers have demonstrated the feasibility of this color control theory by using electrochromic small molecules and device stacking. However, the high color change voltage and slow response time (several seconds to tens of seconds) of organic small molecules make them unsuitable for application in electrochromic displays. Solution-processable conjugated polymers offer advantages such as easy color adjustment, fast response speed, and excellent processing properties, showing promising potential in the field of electrochromic displays. In the past decade, the design and synthesis of solution-processable conjugated polymer materials that can switch from three primary colors to high transmittance has been a research hotspot in this field.
[0003] Based on current research, high-performance solution-processable conjugated polymers that can switch from yellow to high transmittance are extremely rare. Unlike other colors, yellow or orange polymers in their neutral state require a high band gap, with absorption bands located in the 380-550nm range. In their oxidized state, the absorption band must shift across the entire visible region into the near-infrared to achieve high transmittance. Achieving such a wide spectral shift is challenging. Some researchers have conducted pioneering research in this area. In 2011, they designed and synthesized the first solution-processable conjugated polymer capable of switching from yellow to high transmittance by copolymerizing the thiophene derivative ProDOT with a benzene ring, completing the design and synthesis of CMY primary color materials. Unfortunately, this solution-processable yellow conjugated polymer had a relatively high oxidation potential, which hindered its use as a primary color for mixed color tinting. This high oxidation potential could cause overoxidation of the more easily oxidizable polymers in the mixed material, thereby compromising the overall redox stability. Furthermore, they introduced methoxy groups on the benzene ring to effectively reduce the oxidation potential of the polymer, but the polymer exhibited poor cyclic stability. In order to solve the problem of poor stability of this type of yellow-transparent polymer, the present invention improves the structure by modifying the cyclic ether structure on the benzene ring to effectively reduce the oxidation potential of the polymer and significantly improve the stability. Summary of the Invention
[0004] The present invention provides a highly stable conjugated polymer electrochromic material that achieves a neutral yellow-transparent state, as well as its preparation and application. The conjugated polymer electrochromic material is prepared by copolymerizing a cyclic ether-modified p-dibromobenzene ring monomer and a thiophene derivative ProDOT monomer. Electrochromic polymer films fabricated from this conjugated polymer electrochromic material have promising applications in smart windows, displays, electronic paper, and other fields.
[0005] The technical solutions of the present invention are as follows:
[0006] A cyclic ether-modified p-dibromobenzene ring monomer, the structural formula of which is shown in formula (I):
[0007]
[0008] In formula (I), n=1 to 9.
[0009] The preparation method of the cyclic ether-modified p-dibromobenzene ring monomer (I) of the present invention is as follows:
[0010] (1) Catechol (Ia), dibromo-substituted alkane (Ib), an inorganic base, a phase transfer catalyst, and an organic solvent are mixed and reacted at 60-160°C (preferably 70-90°C) for 6-48 hours (preferably 8-16 hours), and the reaction solution is post-treated to obtain compound (Ic);
[0011] The molar ratio of catechol (Ia), dibromo-substituted alkane (Ib), inorganic base, and phase transfer catalyst is 1:1:0.5-5:0.03-0.1, preferably 1:1:2.5:0.05;
[0012] The inorganic base is selected from one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate;
[0013] The phase transfer catalyst is selected from one or more of 18-crown-6, tetrabutylammonium bromide, and tetrabutylammonium iodide, preferably 18-crown-6;
[0014] The organic solvent is selected from one or more of ethanol, acetone, dimethylformamide, and acetonitrile, preferably ethanol;
[0015] The post-treatment method is as follows: after the reaction is completed, the reaction solution is poured into water, extracted with dichloromethane, separated, the organic phase is spin-dried and then separated and purified using a silica gel column chromatography, using dichloromethane: petroleum ether = 2-5:1 (volume ratio, preferably 3:1) as the eluent, collecting the eluate containing the target compound, evaporating the solvent and drying to obtain compound (Ic);
[0016] (2) dissolving compound (Ic) in an anhydrous organic solvent, adding tetraethylethylenediamine and n-butyllithium to carry out a hydrogen extraction reaction, and then adding liquid bromine to react. After the reaction is completed, post-treatment is performed to obtain the product cyclic ether-modified p-dibromobenzene ring monomer (I);
[0017] The molar ratio of compound (Ic), tetraethylethylenediamine, n-butyllithium, and liquid bromine is 1:2-8:2-8:2-6, preferably 1:6:6:3;
[0018] The anhydrous organic solvent is anhydrous ether or anhydrous tetrahydrofuran (THF);
[0019] Tetraethylethylenediamine and n-butyllithium are added at a low temperature of -100 to -60°C (preferably -80 to -20°C), and the reaction is maintained at low temperature for 2 to 4 hours, and then transferred to room temperature and continued to react for 24 to 72 hours (preferably 48 hours);
[0020] Liquid bromine is added at a low temperature of -100 to -60°C (preferably -80 to -20°C), and the reaction is maintained at the low temperature for 0.5 to 2 hours, and then transferred to room temperature and continued to react for 12 to 36 hours (preferably 24 hours);
[0021] The post-treatment method is as follows: after the reaction is completed, the reaction solution is poured into water, extracted with dichloromethane, separated, the organic phase is dried by rotation, and then separated and purified by silica gel chromatography, using dichloromethane: petroleum ether = 2 to 5:1 (volume ratio, preferably 3:1) as eluent, collecting the eluate containing the target compound, evaporating the solvent and drying to obtain product (I);
[0022]
[0023] In formula (Ib) or (Ic): n=1-9.
[0024] The present invention also relates to a conjugated polymer electrochromic material, the structural formula of which is shown in formula (III), which is prepared by copolymerization of a cyclic ether-modified p-dibromobenzene ring monomer (I) and a thiophene derivative ProDOT-type monomer (II);
[0025]
[0026] In formula (III), n=1-9, m=20-50.
[0027] The preparation method of the conjugated polymer electrochromic material (III) of the present invention is as follows:
[0028] The cyclic ether-modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), an inorganic base, trimethylacetic acid, Pd(OAc)2 and an anhydrous organic solvent are mixed, and a polymerization reaction is carried out at 100-160°C (preferably 120-140°C) under nitrogen protection for 24-100 hours (48-72 hours), followed by post-treatment to obtain a conjugated polymer electrochromic material (III);
[0029] The molar ratio of the cyclic ether-modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), the inorganic base, trimethylacetic acid, and Pd(OAc)2 is 1:1:0.5-5:0.1-1:0.01-0.1, preferably 1:1:2.5:0.3:0.03;
[0030] The inorganic base is selected from one or more of potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate, preferably potassium carbonate;
[0031] The preferred anhydrous organic solvent is anhydrous N,N-dimethylacetamide (DMAc);
[0032] The post-treatment method is as follows: after the reaction is completed, the reaction mixture is poured into methanol and filtered, and the obtained precipitate is purified by Soxhlet extraction, and then extracted with methanol, acetone, petroleum ether, and dichloromethane in sequence, and the petroleum ether extract and the dichloromethane extract are collected, and the solvent is evaporated to obtain a conjugated polymer electrochromic material (III).
[0033] The conjugated polymer electrochromic material (III) of the present invention can be further processed by spin coating or spray coating to prepare an electrochromic polymer film. The film has neutral yellow-transparent electrochromic properties and has application prospects in the fields of smart windows, displays, electronic paper, etc.
[0034] Specifically, the preparation method of the electrochromic polymer film is as follows:
[0035] The conjugated polymer electrochromic material (III) is dissolved in a solvent, and is spin-coated on a conductive substrate by a spin coater, and then dried to obtain an electrochromic polymer film;
[0036] The solvent is selected from dichloromethane, chloroform, tetrahydrofuran, methanol or water, preferably dichloromethane;
[0037] The concentration of the conjugated polymer electrochromic material (III) in the solvent is 1 to 30 mmol / L, preferably 15 mmol / L;
[0038] The conductive substrate can be ITO glass, FTO glass, ITO-PET substrate or FTO-PET substrate, etc.
[0039] The working speed of the glue spreader is 500-2000r / min, the acceleration is 0-1000r / min, and the working time is 0.5-2min; preferably, the working speed is 1000r / min, the acceleration is 500r / min, and the working time is 1min.
[0040] The beneficial effects of the present invention are:
[0041] The cyclic ether-modified p-dibromobenzene ring monomer of this invention effectively reduces the oxidation potential of the conjugated polymer, improving the electrochromic properties of the yellow-transparent electrochromic film, achieving a stable and reversible transition from neutral yellow to transparent. Specifically, the polymer film exhibits a coloring time of 0.9 seconds and a fading time of 1.9 seconds at 446 nm. The contrast ratio reaches 45.7%, and it maintains a contrast ratio of 65% after 500 cycles. This new functional material has great potential for applications in displays, smart windows, mobile phone cases, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Figure 1 : Optical absorption of the polymer film prepared in Example 3 under different voltages.
[0043] Figure 2 : Curve of the transmittance of the polymer film prepared in Example 3 changing with time under multiple potential steps from 0 to 1.1 V at a specific wavelength.
[0044] Figure 3 : Cyclic voltammetry curve of the polymer film prepared in Example 3.
[0045] Figure 4 : Response time of the polymer film prepared in Example 3.
[0046] Figure 5 : Relationship between L* value of the polymer film prepared in Example 3 and applied voltage.
[0047] Figure 6 : a*b* values of the polymer film prepared in Example 3.
[0048] Figure 7 : The nuclear magnetic resonance spectrum of embodiment 1 cyclic ether modified p-dibromobenzene ring monomer. DETAILED DESCRIPTION
[0049] The present invention is further described below by means of specific examples, but the protection scope of the present invention is not limited thereto.
[0050] Example 1
[0051] Synthesis of cyclic ether modified p-dibromobenzene ring monomer, the monomer molecular structure is shown below:
[0052]
[0053] 1,2-Dihydroxybenzene (0.11 g, 1 mmol) was mixed with 1,3-dibromopropane (0.20 g, 1 mmol) and 50 mg of 18-crown ether-6 in 30 mL of 1 mol / L NaOH ethanol solution and the reaction temperature was raised to 80°C for 8 h. After the reaction, the mixture in the reaction flask was poured into deionized water and thoroughly extracted with dichloromethane. The organic phase was dried and then purified by silica gel chromatography using a dichloromethane:petroleum ether ratio of 3:1 as the eluent. 0.12 g of the product was obtained with a yield of 82%. 1 NMR δ = 6.8 (s, 4H), δ = 4.3 (m, 4H), δ = 2.34 (m, 2H).
[0054] The above product (0.15g, 1mmol) was dissolved in 50mL of anhydrous THF, and tetraethylethylenediamine (0.70g, 6mmol) was added dropwise at -78°C. After thorough stirring, n-butyllithium solution (containing 0.38g, 6mmol) was slowly added. The reaction was maintained at -78°C for 3h, then transferred to room temperature and the reaction was continued for 3 days. The reaction apparatus was transferred to -78°C, and liquid bromine (0.48g, 3mmol) was added dropwise, and stirred at -78°C for 1h. The reaction apparatus was then transferred to room temperature and the reaction was continued for 1 day. After the reaction was completed, the reaction solution was poured into water and extracted with dichloromethane. The liquid was separated, and the organic phase was dried and separated and purified by silica gel chromatography. The eluent was dichloromethane: petroleum ether = 3:1 to obtain 0.04g of an oily liquid product with a yield of 13%. 1 NMR δ=7.08(s,2H)、δ=4.3(m,4H)、δ=2.34(m,2H). Its nuclear magnetic resonance spectrum is shown in the attached Figure 7 shown.
[0055] Example 2
[0056] Synthesis of conjugated polymer electrochromic materials. The polymer molecular structure is shown below:
[0057]
[0058] Under nitrogen protection, the cyclic ether-modified dibromobenzene ring monomer (0.31 g, 1 mmol) prepared in Example 1, a thiophene derivative ProDOT monomer (shown in Formula II, 0.44 g, 1 mmol), K2CO3 (0.346 g, 2.5 mmol), pivalic acid (30 mg, 0.3 mmol), catalyst palladium acetate (6.7 mg, 0.03 mmol) and 8 mL DMAc were added to the reaction flask, the temperature was raised to 120-130 ° C, and the reaction was stirred for 72 h. After the reaction, the cooled mixture was poured into methanol for thorough washing and purified using a Soxhlet extractor. The crude product was wrapped with filter paper and loaded into a Soxhlet extraction apparatus. Pure methanol, acetone, petroleum ether, and dichloromethane were used for extraction to obtain an extract. The products in petroleum ether and dichloromethane were retained, with a yield of 70% in petroleum ether and 10% in dichloromethane. The solvent was evaporated to finally obtain 0.49 g of a conjugated polymer electrochromic material with a molecular weight distribution of 7 to 25 kDa.
[0059] Example 3
[0060] Preparation of electrochromic polymer film: 15 mg of the conjugated polymer electrochromic material obtained in Example 2 was dissolved in 1 mL of dichloromethane. The resulting solution was prepared as a thin film on an ITO conductive substrate using a spin coater at a speed of 1000 r / min, an acceleration of 500 r / min, and a working time of 1 min. After drying, an electrochromic polymer film with a thickness of 150 nm was obtained.
[0061] Compared to existing electrochromic films that shift from yellow to transparent, the polymer film prepared in this invention exhibits a significant decrease in absorption near 450nm with increasing voltage under operating voltage conditions of 0-1.1V, and its appearance changes from yellow to transparent. This film expands upon existing yellow polymer systems and establishes a precedent for the preparation of yellow electrochromic polymer materials using a phenyl ether structure.
[0062] Furthermore, this polymer material achieves high stability. Current experimental results show that it can achieve over 1,000 stable cycles at an applied voltage of 0-1.1V, whereas yellow polymers prepared from existing materials typically experience significant optical contrast degradation after 250 cycles. This significant difference is attributed to the introduction of a phenyl ether structure, which increases the material's spatial distortion and further improves its withstand voltage, providing insights for the future preparation of highly stable electrochromic polymer materials that transition from yellow to transparent.
Claims
1. A cyclic ether-modified p-dibromobenzene ring monomer, the structural formula of which is shown in formula (I): In formula (I), n=2-9.
2. A method for preparing the cyclic ether-modified p-dibromobenzene ring monomer (I) as claimed in claim 1, characterized in that: The method is as follows: (1) Catechol (Ia), dibromo-substituted alkane (Ib), an inorganic base, a phase transfer catalyst, and an organic solvent are mixed and reacted at 60-160°C for 6-48 hours. The reaction solution is then post-treated to obtain compound (Ic); The inorganic base is selected from one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate; The phase transfer catalyst is selected from one or more of 18-crown ether-6, tetrabutylammonium bromide, and tetrabutylammonium iodide; The organic solvent is selected from one or more of ethanol, acetone, dimethylformamide, and acetonitrile; (2) dissolving compound (Ic) in an anhydrous organic solvent, adding tetraethylethylenediamine and n-butyllithium to carry out a hydrogen extraction reaction, and then adding liquid bromine to react. After the reaction is completed, post-treatment is performed to obtain the product cyclic ether-modified p-dibromobenzene ring monomer (I); The anhydrous organic solvent is anhydrous ether or anhydrous tetrahydrofuran; Tetraethylethylenediamine and n-butyllithium are added at a low temperature of -100 to -60°C, and the reaction is maintained at low temperature for 2 to 4 hours, and then transferred to room temperature and continued to react for 24 to 72 hours; Liquid bromine is added at a low temperature of -100 to -60°C, and the reaction is maintained at low temperature for 0.5 to 2 hours, and then transferred to room temperature and continued to react for 12 to 36 hours; In formula (Ib) or (Ic): n=2-9.
3. The method for preparing the cyclic ether-modified p-dibromobenzene ring monomer (I) as claimed in claim 2, wherein: In step (1), the molar ratio of catechol (Ia), dibromo-substituted alkane (Ib), inorganic base, and phase transfer catalyst is 1:1:0.5-5:0.03-0.
1.
4. The method for preparing the cyclic ether-modified p-dibromobenzene ring monomer (I) as claimed in claim 2, wherein: In step (2), the molar ratio of compound (Ic), tetraethylethylenediamine, n-butyllithium and liquid bromine is 1:2-8:2-8:2-6.
5. A conjugated polymer electrochromic material, having the structural formula shown in formula (III): In formula (III), n=1-9, m=20-50.
6. A method for preparing the conjugated polymer electrochromic material (III) as claimed in claim 5, characterized in that: The method is as follows: The cyclic ether-modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), an inorganic base, trimethylacetic acid, Pd(OAc)2 and an anhydrous organic solvent are mixed, and a polymerization reaction is carried out at 100-160°C under nitrogen protection for 24-100 hours, followed by post-treatment to obtain a conjugated polymer electrochromic material (III); The inorganic base is selected from one or more of potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate; The anhydrous organic solvent is anhydrous N,N-dimethylacetamide; In formula (I), n=1 to 9.
7. The method for preparing the conjugated polymer electrochromic material (III) according to claim 6, characterized in that: The molar ratio of the cyclic ether modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), the inorganic base, trimethylacetic acid, and Pd(OAc)2 is 1:1:0.5~5:0.1~1:0.01~0.
1.
8. The method for preparing the conjugated polymer electrochromic material (III) according to claim 6, characterized in that: The post-treatment method is as follows: after the reaction is completed, the reaction mixture is poured into methanol and filtered, and the obtained precipitate is purified by Soxhlet extraction, and then extracted with methanol, acetone, petroleum ether, and dichloromethane in sequence, and the petroleum ether extract and the dichloromethane extract are collected, and the solvent is evaporated to obtain a conjugated polymer electrochromic material (III).
9. An electrochromic polymer film having neutral yellow-transparent electrochromic properties, characterized in that: The electrochromic polymer film is prepared by spin coating or spray coating the conjugated polymer electrochromic material (III) according to claim 5.
10. Application of the electrochromic polymer film according to claim 9 in the fields of smart windows, displays, and electronic paper.