A soluble polythiophene derivative electrochromic material and a preparation method thereof

Abstract

The application belongs to the field of electrochromic materials, and particularly relates to a soluble polythiophene derivative electrochromic material and a preparation method thereof. The soluble polythiophene derivative electrochromic material has a structure as shown in formula (I): wherein x+y=1, x is 0.1 or 0.3, R1 is R2 is The soluble polythiophene derivative electrochromic material of the application can adjust the crosslinking density by adjusting the ratio of the polymerization monomers c-EDT and EDT, thereby optimizing the structure of the polythiophene derivative, making it soluble in a solvent, realizing electrochromism of wine red to light blue, and having excellent stability.

Description

Technical Field

[0001] This invention belongs to the field of electrochromic materials, specifically relating to a soluble polythiophene derivative electrochromic material and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Electrochromic materials exhibit different light absorption properties under different redox states, making them widely applicable in fields such as flexible displays, camouflage materials, and smart glass for buildings and automobiles. Recent studies have shown that combining electrochromism with other functionalities can enhance the intelligence level of devices, thus attracting more attention to electrochromic materials. Compared with inorganic materials, conjugated polymers have many unique advantages as electrochromic materials, such as rich color changes, fast response time, light weight, and simple preparation. In recent years, great efforts have been made in the preparation of high-performance conjugated polymers. Through molecular structure modification, a series of conjugated polymers with rare colors have been obtained, such as green-to-transparent and multicolor transitions. In addition, conjugated polymers also possess high optical contrast (~80%), fast response time (<1.0 second), and high coloring efficiency (>1000 cm⁻¹). 2 C -1 It must be pointed out that good stability is an important parameter for corresponding electrochromic products. However, highly stable conjugated polymers are still relatively rare in the field of electrochromism. Therefore, how to prepare highly stable conjugated polymer electrochromic materials is an urgent problem to be solved.

[0004] Current strategies for improving the stability of conjugated polymers include modifying molecular structure and optimizing post-processing. The electrochromic mechanism of conjugated polymers is directly related to redox reactions. During redox processes, dopant ions may enter and exit the conjugated polymer, causing polymer volume shrinkage / expansion. It has been reported that network-based conjugated polymers can provide ion transport channels and further improve ion transport. The network structure can enhance the structural stability of conjugated polymers during redox processes. Molecules based on covalent organic frameworks (COFs) have been reported as electrochromic materials, exhibiting fast reaction times and good stability due to the presence of the network structure. However, these COF materials have poor solubility in organic and inorganic solvents, increasing the difficulty of device fabrication. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a soluble polythiophene derivative electrochromic material and its preparation method.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a soluble polythiophene derivative electrochromic material having a structure as shown in formula (I):

[0008]

[0009] Where x + y = 1, x is 0.1 or 0.3, and R1 is... R2 is

[0010] In a second aspect, the present invention provides a method for preparing a soluble polythiophene derivative electrochromic material as described in the first aspect, comprising the following steps:

[0011] c-EDT, Th-2Br and EDT were dissolved in dimethylacetamide in a molar ratio of 0.1:1:0.9 or 0.3:1:0.7 and degassed. PivOH, K2CO3 and Pd(OAc)2 were added under N2 protection and heated to react. After the reaction was completed, methanol was added to precipitate solid. The precipitated solid was extracted by Soxhlet extraction, dissolved, recrystallized, filtered and dried to obtain a soluble polythiophene derivative electrochromic material.

[0012] The structure of c-EDT is shown in formula (II), the structure of Th-2Br is shown in formula (III), and the structure of EDT is shown in formula (IV).

[0013]

[0014]

[0015] Where R1 is R2 is

[0016] Preferably, the heating reaction temperature is 115-125℃ and the time is 20-28h.

[0017] Preferably, Soxhlet extraction is performed using methanol, acetone, and hexane.

[0018] Preferably, the solution is dissolved in chloroform and then recrystallized in methanol.

[0019] Preferably, the preparation method of c-EDT includes the following steps:

[0020] ETD-c and azobisisobutyronitrile were dissolved in tetrahydrofuran and refluxed under N2 protection. The c-EDT was then purified by silica gel column chromatography.

[0021] The structure of ETD-c is shown in equation (V):

[0022]

[0023] Further preferred, the reflux time is 20-28 hours.

[0024] A further preferred method for preparing ETD-c includes the following steps:

[0025] EDT-Cl, methacrylic acid, K2CO3 and KI were dissolved in dimethyl sulfoxide and reacted under N2 protection by heating. The mixture was then extracted with dichloromethane and purified by silica gel column chromatography to obtain ETD-c.

[0026] The structure of EDT-Cl is shown in formula (VI):

[0027]

[0028] Further preferred, the molar ratio of EDT-Cl to methacrylic acid is 0.4-0.5:1.

[0029] In a further preferred embodiment, the heating reaction temperature is 115-125℃ and the time is 3-5h.

[0030] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0031] The soluble polythiophene derivative electrochromic material of the present invention can optimize the structure of the polythiophene derivative by adjusting the crosslinking density by adjusting the ratio of polymeric monomers c-EDT and EDT, so that it can be dissolved in solvent, achieves wine red to light blue electrochromism and has excellent stability. Attached Figure Description

[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0033] Figure 1 The image shows the 1H NMR spectrum of c-EDT in deuterated chloroform.

[0034] Figure 2 The spectroelectrochemical spectra of (a) PET-(1,9) and (b) PET-(3,7) in acetonitrile / tetrabutylamine phosphorus hexafluoride solution are shown.

[0035] Figure 3 Transmittance-time curves at 550 nm for (a) PET-(1,9) and (b) PET-(3,7);

[0036] Figure 4For (a) PET-(1,9) and (b) PET-(3,7), at a scan rate of 300 mV / s -1 The volt-ampere curve for the next 1000 cycles;

[0037] Figure 5 Transmittance-time curves for (a) PET-(1,9) and (b) PET-(3,7) after 1000 cycles at 550 nm. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0039] Example 1

[0040] (1) EDT-Cl (3.00 g), methacrylic acid (2.84 g), K2CO3 (5.44 g) and KI (0.052 g) were dissolved in dimethyl sulfoxide (10 ml) and reacted at 120 °C for 4 h. Then, the mixture was extracted with dichloromethane and purified by silica gel column chromatography to obtain light yellow crystalline EDT-c with a yield of 67%.

[0041] (2) EDT-c (2.00 g) and azobisisobutyronitrile (1.37 g) were dissolved in 7 ml of tetrahydrofuran and refluxed for 24 h. After cooling to room temperature, excess methanol was added to obtain a white solid c-EDT. The solid was thoroughly washed with methanol and dried under vacuum. Yield: 83%. Figure 1 As shown, the 1H NMR spectrum of c-EDT confirms its successful synthesis.

[0042] (3) Dissolve c-EDT (7.1 mg), Th-2Br (154 mg) and EDT (64.3 mg) in 10 ml of dimethylacetamide, carefully degas, add PivOH (7.7 mg), K2CO3 (86.3 mg) and Pd(OAc)2 (0.7 mg) under N2 protection, react at 120 °C for 24 h, add excess methanol to precipitate a black solid, extract the crude product with methanol, acetone and hexane by Soxhlet extraction, dissolve the polymer in a small amount of CHCl3, recrystallize with methanol, filter, and vacuum dry to obtain a reddish-black solid, denoted as PET-(1,9), yield: 82%.

[0043] Example 2

[0044] The synthesis of ETD-c and c-DET is the same as in Example 1.

[0045] c-EDT (21.4 mg), Th-2Br (154.0 mg), and EDT (50.0 mg) were dissolved in 10 mL of dimethylacetamide. Under N2 protection, PivOH (7.7 mg), K2CO3 (86.3 mg), and Pd(OAc)2 (0.7 mg) were added. The mixture was reacted at 120 °C for 24 h. Excess methanol was added to precipitate a black solid. The crude product was extracted with methanol, acetone, and hexane using a Soxhlet extractor. The polymer was dissolved in a small amount of CHCl3, recrystallized from methanol, filtered, and dried under vacuum to obtain a reddish-black solid, denoted as PET-(3,7), with a yield of 55%.

[0046] The preparation processes for PET-(1,9) and PET-(3,7) are shown below:

[0047]

[0048] Example 3

[0049] The prepared PET-(1,9) and PET-(3,7) were dissolved in CH2Cl2 and then sprayed onto ITO conductive glass to form thin films, which served as working electrodes. A platinum electrode was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. The electrolyte solution was a 0.1 mol / L tetrabutylamine acetonitrile solution of phosphorus hexafluoride.

[0050] like Figure 2 As shown, PET-(1,9) and PET-(3,7) have an absorption peak at around 550 nm in the neutral state, and the neutral state polymer is wine red in color. After the polymer is oxidized, the optical absorption at around 550 nm weakens, the absorption in the near-infrared region is enhanced, and the oxidized state polymer is light blue in color.

[0051] The kinetic properties of PET-(1,9) and PET-(3,7) were characterized by time-transmittance curves. The transmittance of the polymer films under different states was measured using a spectrophotometer, and the optical contrast, response time, and coloring efficiency of the polymers were calculated.

[0052] The time-transmittance curves of PET-(1,9) and PET-(3,7) are as follows: Figure 3 As shown in Table 1, the optical contrast ratio, response time, and coloring efficiency were calculated using time-transmittance curves. As shown in Table 1, PET-(1,9) and PET-(3,7) exhibit high optical contrast ratios, low response times, and high coloring efficiencies, indicating their excellent photochromic properties.

[0053] Table 1 Optical contrast, response time, and coloring efficiency of PET-(1,9) and PET-(3,7)

[0054]

[0055] Redox stability was determined by cyclic voltammetry at 300 mV s. -1 Characterization at scan rate shows that the cyclic stability of the polymer can be measured by the cyclic area of ​​the CVs. For example... Figure 4 As shown, the fact that the CV area did not decrease after 1000 cycles indicates that PET-(1,9) and PET-(3,7) have good stability.

[0056] The optical stability of PET-(1,9) and PET-(3,7) was measured using time-transmittance curves with a conversion time of 2 s. For example... Figure 5 As shown, after 1000 cycles, the optical contrast of PET-(1,9) and PET-(3,7) did not decrease, indicating that PET-(1,9) and PET-(3,7) have high optical stability.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A soluble polythiophene derivative electrochromic material, characterized in that, It has a structure as shown in equation (I): Equation (I); Where x + y = 1, x is 0.1 or 0.3, and R1 is... R2 is .

2. A method for preparing the soluble polythiophene derivative electrochromic material as described in claim 1, characterized in that, Includes the following steps: c-EDT, Th-2Br and EDT were dissolved in dimethylacetamide in a molar ratio of 0.1:1:0.9 or 0.3:1:0.7 and degassed. PivOH, K2CO3 and Pd(OAc)2 were added under N2 protection and heated to react. After the reaction was completed, methanol was added to precipitate solid. The precipitated solid was extracted by Soxhlet extraction, dissolved, recrystallized, filtered and dried to obtain a soluble polythiophene derivative electrochromic material. The structure of c-EDT is shown in formula (II), the structure of Th-2Br is shown in formula (III), and the structure of EDT is shown in formula (IV). Equation (II); Equation (III); Formula (IV); Where R1 is R2 is .

3. The preparation method according to claim 2, characterized in that, The heating reaction was carried out at a temperature of 115-125 °C for 20-28 h.

4. The preparation method according to claim 2, characterized in that, Soxhlet extraction was performed using methanol, acetone, and hexane.

5. The preparation method according to claim 2, characterized in that, Dissolved in chloroform and then recrystallized in methanol.

6. The preparation method according to claim 2, characterized in that, The preparation method of c-EDT includes the following steps: ETD-c and azobisisobutyronitrile were dissolved in tetrahydrofuran and refluxed under N2 protection. The c-EDT was then purified by silica gel column chromatography. The structure of ETD-c is shown in equation (V): Equation (V).

7. The preparation method according to claim 6, characterized in that, The reflux time is 20-28 hours.

8. The preparation method according to claim 6, characterized in that, The preparation method of ETD-c includes the following steps: ETD-C was obtained by dissolving EDT-Cl, methacrylic acid, K2CO3 and KI in dimethyl sulfoxide and heating under N2 protection, followed by extraction with dichloromethane and purification by silica gel column chromatography. The structure of EDT-Cl is shown in formula (VI): Formula (VI).

9. The preparation method according to claim 8, characterized in that, The molar ratio of EDT-Cl to methacrylic acid is 0.4-0.5:

1.

10. The preparation method according to claim 8, characterized in that, The heating reaction is carried out at a temperature of 115-125 ℃ for 3-5 h.

Images