Conjugated polymer material capable of realizing neutral green / black-transparent electrochromic performance and preparation method and application thereof

Abstract

The invention discloses a conjugated polymer material capable of achieving neutral green / black-transparent electrochromic performance and a preparation method and application thereof. The conjugated polymer material (IV) disclosed by the invention is prepared from a cyclic ether modified p-dibromobenzene ring monomer (I), a thiophene derivative ProDOT monomer (II) and a D-A-D unit ProDOT-BTD-ProDOT coupling monomer (III) through a copolymerization reaction; an electrochromic polymer film processed from the conjugated polymer material has application prospects in the fields of intelligent windows, intelligent glasses, displays, electronic paper and the like; in the material provided by the invention, the cyclic ether modified p-dibromobenzene ring monomer effectively reduces the oxidation potential of the conjugated polymer, improves the electrochromic performance of the black / green-transparent electrochromic film, and can realize stable and reversible transformation; # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of electrochromic materials, and in particular to a conjugated polymer material capable of realizing neutral green / black-transparent electrochromic performance, and a preparation method and application thereof. Background Art

[0002] As a new type of functional material, electrochromic materials have gradually attracted widespread attention. In recent years, electrochromic display, as a typical non-emissive (passive) display technology, has received widespread attention and is expected to become one of the next generation of displays. In the field of electrochromism, materials that can reversibly switch between black and high transmittance states have received extensive attention and research due to their broad application fields (such as electronic paper, smart windows, and electrochromic glasses). As a new generation of electrochromic materials, solution-processed conjugated polymers have the advantages of easy color adjustment, good mechanical flexibility, fast response time, and good processing performance, providing a good platform for the preparation of black to high transmittance switching materials. Compared with conjugated polymer materials that switch from red, green and other colors to high transmittance, the realization of black to high transmittance switching materials is more difficult, because it not only needs to have full absorption in the entire visible light region in the neutral state, but also needs to achieve high transmittance in the same band range when in the oxidized state. So far, the preparation of high-performance black to high transmittance conjugated polymer materials remains a huge challenge.

[0003] After the efforts of a large number of researchers, many strategies have been developed to achieve the preparation of conjugated polymer materials that switch from black to high transmittance, such as donor-acceptor (DA) design theory, side chain suspension, color blending, etc. Among them, DA design theory is the most commonly used approach to design and prepare black to high transmittance materials. Some scholars reported the first soluble black to high transmittance switching conjugated polymer material based on the DA design method by controlling the feed ratio of D unit ProDOT and DAD unit ProDOT-BTD-ProDOT and using ferric chloride random oxidative polymerization. This pioneering work opened the door to the design and preparation of black conjugated polymer materials. Since then, based on different donor or acceptor units and combined with different polymerization methods, researchers have designed and synthesized many conjugated polymers that switch from black to high transmittance.

[0004] By studying and comparing the above results, we found a common feature, that is, all the current conjugated polymers that switch from black to high transmittance are achieved by random copolymerization of multiple units. The present invention adjusts the feed ratio of monomer structures with different absorption fragments in DA and introduces a cyclic ether-modified dibromobenzene ring monomer, which can reduce the oxidation potential of the polymer, to synthesize a highly stable green / black conjugated polymer with an absorption spectrum extending in the entire visible light region (400-780nm). Summary of the invention

[0005] The present invention provides a conjugated polymer material capable of realizing neutral green / black-transparent electrochromic performance, and a preparation method and application thereof. The electrochromic polymer film processed from the conjugated polymer material has application prospects in the fields of smart windows, smart glasses, displays, electronic paper, etc.

[0006] The technical solution of the present invention is as follows:

[0007] A conjugated polymer material capable of achieving neutral green / black-transparent electrochromic properties, as shown in formula (IV):

[0008]

[0009] In formula (IV),

[0010] R1 and R2 are independently one of a C1-C30 alkyl chain or an alkoxy chain;

[0011] R3 and R4 are independently one of a C1-C30 alkyl chain or an alkoxy chain;

[0012] n = 1 to 9;

[0013] a=1~70, b=1~70, c1=1~70, c2=1~70, and: a+b=c1+c2.

[0014] The preparation method of the conjugated polymer material (IV) of the present invention is as follows:

[0015] The cyclic ether modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), the DAD unit ProDOT-BTD-ProDOT coupling monomer (III), Pd(OAc)2, an inorganic base, pivalic acid and an organic solvent are mixed, and a polymerization reaction is carried out at 110 to 160° C. (preferably 120 to 140° C.) for 20 to 100 hours (preferably 40 to 72 hours) under nitrogen protection, and a conjugated polymer material (IV) is obtained after post-treatment;

[0016] in,

[0017] The molar ratio of the cyclic ether-modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), the DAD unit ProDOT-BTD-ProDOT coupling monomer (III), Pd(OAc)2, the inorganic base, and the pivalic acid is x:1:1-x:0.01-0.1:0.5-5:0.1-1, x=0.2-0.8; preferably x:1:1-x:0.05:2.5:0.4, x=0.3-0.5;

[0018] The inorganic base is selected from one or more of potassium carbonate, cesium carbonate, potassium bicarbonate, sodium bicarbonate, and sodium carbonate, preferably potassium carbonate;

[0019] The preferred organic solvent is anhydrous N,N-dimethylacetamide (DMAc);

[0020] The specific post-treatment method is as follows: after the reaction is completed, the reaction mixture is cooled to room temperature, then poured into methanol for washing, filtered, the precipitate is collected and purified by Soxhlet extraction, and methanol, acetone, petroleum ether, and dichloromethane are used for Soxhlet extraction in turn, the petroleum ether extract and the dichloromethane extract are collected, the solvent is evaporated, and the conjugated polymer material (IV) is obtained.

[0021]

[0022] In formula (I) to formula (III),

[0023] R1, R2, R3, R4 and n are defined the same as in formula (IV).

[0024] The conjugated polymer material (IV) of the present invention can be prepared into an electrochromic polymer film by spin coating or spray coating, and the obtained film has neutral green / black-transparent electrochromic properties. Specifically, the preparation method of the electrochromic polymer film is as follows:

[0025] The conjugated polymer material (IV) is dissolved in a solvent, sprayed on a conductive substrate by a spray gun, and an electrochromic polymer film is obtained after drying;

[0026] The solvent is selected from dichloromethane, chloroform, tetrahydrofuran, methanol or water, preferably dichloromethane;

[0027] The concentration of the conjugated polymer material (IV) in the solvent is 1 to 30 mmol / L, preferably 5 mmol / L;

[0028] The conductive substrate may be ITO glass, ITO-PET substrate, FTO glass or FTO-PET substrate, etc.;

[0029] The film spraying thickness is 50 to 200 nm.

[0030] The beneficial effects of the present invention are:

[0031] In the material provided by the present invention, the cyclic ether-modified dibromobenzene ring monomer effectively reduces the oxidation potential of the conjugated polymer, improves the electrochromic performance of the black / green-transparent electrochromic film, and can achieve a stable and reversible transition from neutral green / black to transparent. Specifically, the coloring time of the polymer film at 650nm is 2.1s, and the fading time is 2.2s; the contrast can reach 39.35%, and it can still maintain a contrast of 91% after 1626 cycles. This material is a new functional material with great potential, and has potential application value in the fields of smart windows, smart glasses, displays, electronic paper, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : NMR of the polymer prepared in Example 1.

[0033] Figure 2 : Optical absorption of the polymer film prepared in Example 2 under different voltages.

[0034] Figure 3 : Curve of the transmittance variation with time of the polymer film prepared in Example 2 under multiple potential steps from 0 to 0.9 V at 300 to 1100 nm.

[0035] Figure 4 : Cyclic voltammetry curve of the polymer film prepared in Example 2.

[0036] Figure 5 : Response time of the polymer film prepared in Example 2.

[0037] Figure 6 : Relationship between L* value of the polymer film prepared in Example 2 and applied voltage.

[0038] Figure 7 : a*b* values ​​of the polymer film prepared in Example 2. DETAILED DESCRIPTION

[0039] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0040] In the following embodiments,

[0041] The structural formula of the raw material cyclic ether modified p-dibromobenzene ring monomer is as follows:

[0042]

[0043] The preparation method is:

[0044] 1,2-dihydroxybenzene (0.11 g, 1 mmol) was mixed with 1,3-dibromopropane (0.20 g, 1 mmol) and 50 mg 18-crown ether-6 in 30 mL 1 mol / L NaOH ethanol solution, and the temperature was raised to 80 °C for 8 h. After the reaction, the mixture in the reaction bottle was poured into deionized water, and fully extracted with dichloromethane. The organic phase was spin-dried and separated and purified by silica gel chromatography. The eluent was dichloromethane: petroleum ether = 3:1. 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).

[0045] The above product (0.15g, 1mmol) was dissolved in 50mL of anhydrous THF, and tetraethylethylenediamine (0.70g, 6mmol) was added dropwise at a low temperature of -78°C. After sufficient stirring, n-butyl lithium solution (containing 0.38g, 6mmol) was slowly added, and the reaction was maintained at a low temperature of -78°C for 3h, and then transferred to room temperature and continued to react for 3 days. The reaction device was transferred to a low temperature of -78°C, and liquid bromine (0.48g, 3mmol) was added dropwise, and stirred at a low temperature of -78°C for 1h, and then the reaction device was transferred to room temperature and continued to react for 1 day. After the reaction was completed, the reaction solution was poured into water, extracted with dichloromethane, separated, and the organic phase was spin-dried and separated and purified using a silica gel column, and the eluent was dichloromethane: petroleum ether = 3:1, and 0.04g of oily liquid product was obtained, with a yield of 13%, H 1 NMR δ = 7.08 (s, 2H), δ = 4.3 (m, 4H), δ = 2.34 (m, 2H).

[0046] The structural formula of the raw material thiophene derivative ProDOT monomer is as follows:

[0047]

[0048] Purchased from Aode Technology (10g)

[0049] The structural formula of the raw material DAD unit ProDOT-BTD-ProDOT coupling monomer is as follows:

[0050]

[0051] Purchased from Bid Pharmaceuticals (10g)

[0052] Example 1 Synthesis of conjugated polymer materials:

[0053]

[0054] Under nitrogen protection, add cyclic ether modified p-dibromobenzene ring monomer (0.23g, 0.71mmol), thiophene derivative ProDOT monomer (0.43g, 1mmol), DAD unit ProDOT-BTD-ProDOT coupling monomer (0.21g, 0.29mmol), catalyst palladium acetate (11mg, 0.05mmol), K2CO3 (0.35g, 2.5mmol), pivalic acid (40mg, 0.4mmol) and 9mL DMAc to the reaction bottle, heat to 130-140℃, stir and react for 48h. After the reaction, pour the cooled mixture into methanol for thorough washing, and purify it with a Soxhlet extractor. After the crude product is packed with filter paper, it is loaded into a Soxhlet extraction device, and 500mL of pure methanol, 500mL of acetone, 500mL of petroleum ether, and 500mL of dichloromethane are used for extraction to obtain an extract. The products in petroleum ether and dichloromethane were retained, with a yield of 35% in petroleum ether and 45% in dichloromethane. The solvent was evaporated to finally obtain 0.533 g of a conjugated polymer material with a molecular weight distribution of 2.9 to 102 kDa.

[0055] Example 2 Preparation of electrochromic polymer film:

[0056] 5 mg of the conjugated polymer material obtained in Example 1 was dissolved in 1 mL of dichloromethane. The obtained solution was sprayed on an ITO conductive substrate to prepare a thin film. After drying, an electrochromic polymer thin film with a thickness of 150 nm was obtained.

[0057] Compared with the current black to transparent electrochromic film, the polymer film prepared by the present invention has a significantly decreased absorption near 650nm and 430nm as the voltage increases under the working voltage of 0-0.9V, and the appearance shows a color change from black / green to transparent. The prepared film expands the existing black / green polymer system and creates a precedent for the preparation of black / green electrochromic polymer materials with phenyl cyclic ether structure.

[0058] In addition, the polymer material can achieve high stability. The current experimental results show that it can achieve more than 1,600 stable cycles under an applied voltage of 0-0.9V, while most black polymers prepared from existing materials have a large optical contrast attenuation after 500 cycles. This huge difference is due to the introduction of the benzene cyclic ether structure, which improves the spatial distortion of the material and further improves the withstand voltage, providing ideas for the future preparation of highly stable black to transparent electrochromic polymer materials.

Claims

1. A conjugated polymer material capable of achieving neutral green / black-transparent electrochromic properties, as shown in formula (IV): In formula (IV), R1 and R2 are independently one of a C1-C30 alkyl chain or an alkoxy chain; R3 and R4 are independently one of a C1-C30 alkyl chain or an alkoxy chain; n＝1～9； a=1~70, b=1~70, c1=1~70, c2=1~70, and: a+b=c1+c2.

2. The method for preparing the conjugated polymer material (IV) according to claim 1, characterized in that: The preparation method is as follows: The cyclic ether modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), the DAD unit ProDOT-BTD-ProDOT coupling monomer (III), Pd(OAc)2, an inorganic base, pivalic acid and an organic solvent are mixed, and a polymerization reaction is carried out at 110-160°C for 20-100 hours under nitrogen protection, and a conjugated polymer material (IV) is obtained after post-treatment; in, The molar ratio of the cyclic ether-modified p-dibromobenzene ring monomer (I), the thiophene derivative ProDOT monomer (II), the DAD unit ProDOT-BTD-ProDOT coupling monomer (III), Pd(OAc)2, the inorganic base, and the pivalic acid is x:1:1-x:0.01~0.1:0.5~5:0.1~1, x=0.2~0.8; In formula (I) to formula (III), R1, R2, R3, R4 and n are defined the same as in formula (IV).

3. The method for preparing the conjugated polymer material (IV) as claimed in claim 2, characterized in that: The molar ratios of cyclic ether modified dibromobenzene ring monomer (I), thiophene derivative ProDOT monomer (II), DAD unit ProDOT-BTD-ProDOT coupling monomer (III), Pd(OAc)2, inorganic base and pivalic acid are x:1:1-x:0.05:2.5:0.4, x=0.3~0.

5.

4. The method for preparing the conjugated polymer material (IV) according to claim 2, characterized in that: The inorganic base is selected from one or more of potassium carbonate, cesium carbonate, potassium bicarbonate, sodium bicarbonate and sodium carbonate.

5. The method for preparing the conjugated polymer material (IV) according to claim 2, characterized in that: The organic solvent was anhydrous N,N-dimethylacetamide.

6. The method for preparing the conjugated polymer material (IV) according to claim 2, characterized in that: The polymerization reaction temperature is 120-140°C and the reaction time is 40-72 hours.

7. The method for preparing the conjugated polymer material (IV) according to claim 2, characterized in that: The post-treatment method is as follows: after the reaction is completed, the reaction mixture is cooled to room temperature, then poured into methanol for washing, filtered, the precipitate is collected and purified by Soxhlet extraction, and methanol, acetone, petroleum ether, and dichloromethane are used for Soxhlet extraction in turn, the petroleum ether extract and the dichloromethane extract are collected, the solvent is evaporated, and a conjugated polymer material (IV) is obtained.

8. An electrochromic polymer film, characterized in that: The conjugated polymer material (IV) according to claim 1 is prepared by spin coating or spray coating.

9. The method for preparing an electrochromic polymer film according to claim 8, characterized in that: The preparation method is: The conjugated polymer material (IV) is dissolved in a solvent, sprayed on a conductive substrate by a spray gun, and an electrochromic polymer film is obtained after drying; The solvent is selected from dichloromethane, chloroform, tetrahydrofuran, methanol or water; The concentration of the conjugated polymer material (IV) in the solvent is 1 to 30 mmol / L; The conductive substrate is selected from ITO glass, ITO-PET substrate, FTO glass or FTO-PET substrate; The film spraying thickness is 50 to 200 nm.

10. Application of the electrochromic polymer film according to claim 8 in the fields of smart windows, smart glasses, displays and electronic papers.

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