CN108840993B

CN108840993B - Polymeric membrane PEWT with D-A-D' asymmetric structure and preparation method and application thereof

Info

Publication number: CN108840993B
Application number: CN201810491811.4A
Authority: CN
Inventors: 刘军磊; 李林; 欧阳密; 张�诚
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2018-05-21
Filing date: 2018-05-21
Publication date: 2020-10-27
Anticipated expiration: 2038-05-21
Also published as: CN108840993A

Abstract

The invention provides a DAD' asymmetric structure polymeric membrane PEWT as well as a preparation method and application thereof, wherein the preparation method comprises the following steps: under the action of an electron donating group, 2, 7-dibromo-9 fluorenone shown in the formula 1 is subjected to coupling reaction to form an asymmetric DAD 'structural monomer, and polymerization reaction is carried out at room temperature by adopting a cyclic voltammetry polymerization method to obtain an asymmetric DAD' structural polymer film deposited on a working electrode. The method provided by the invention is simple to operate, the monomer yield and the purity of the polymer film are higher, the prepared product has more prominent multicolor display and excellent electrochromic performance, and the material can be applied to electrochromic devices.

Description

Polymeric membrane PEWT with D-A-D' asymmetric structure and preparation method and application thereof

Technical Field

The invention relates to a polymeric membrane PEWT with a multicolor display D-A-D ' (donor-acceptor-donor ') asymmetric structure and a preparation method thereof, wherein the polymeric membrane PEWT with the D-A-D ' asymmetric structure can be applied to preparation of electrochromic devices.

Technical Field

Since the discovery of Polymer Electrochromic (PEC) materials, it is considered to be one of the development directions of the next-generation EC materials because of its advantages of easy structure modification, high coloring efficiency, high optical contrast, and fast response speed, compared to inorganic electrochromic materials. At present, the method for realizing multicolor display of electrochromic polymers through molecular design or modification mainly comprises the design of a donor-acceptor (D-A) molecular structure and copolymerization among different molecules, wherein a copolymerization product is not favorable for mechanism research on the color change performance of electrochromic materials and quality control in actual production due to uncertainty of the molecular structure.

The D-A structure can effectively regulate and control the molecular energy band and the electrochromic property of the polymer. At present, various D-A structure conjugated polymers are reported, such as D-A structure copolymers taking benzothiadiazole, benzoquinoxaline, thiophene pyrazine, fluorenone and derivatives thereof as receptors. However, the understanding of the mechanism and the application of the material are still limited, so that the problems that the oxidation potential is single, the color change display is single and the optical contrast is general in the electrochromic property of the existing D-A-D symmetric conjugated polymer PEWE (a molecular polymer with the same 3, 4-Ethylenedioxythiophene (EDOT) introduced at two ends of fluorenone) are solved in order to deeply understand the relationship between the molecular structure of the conjugated polymer electrochromic material and the photoelectric property of the conjugated polymer electrochromic material. We design a fluorenone-based D-A-D' asymmetric conjugated polymer PEWT (a molecular polymer with different groups of 3, 4-Ethylenedioxythiophene (EDOT) and triphenylamine introduced into two ends of fluorenone), study the influence of a molecular structure on the performances of color display, aggregation state appearance, optical contrast and the like, and find that the polymer has more excellent electrochromic performance than PEWE.

Disclosure of Invention

In order to solve the problems of single oxidation potential, single color change display single optical contrast and the like of the existing D-A-D symmetrical conjugated polymer PEWE, the invention aims to provide a D-A-D' asymmetrical structure polymer PEWT, and the polymer is found to enrich electrochromic display and have higher optical contrast under a certain wavelength.

In order to achieve the purpose, the invention adopts the following technical scheme:

a D-A-D' asymmetric structure polymeric membrane PEWT is prepared according to the following method:

(1) mixing 2, 7-dibromo-9 fluorenone shown in formula 1 with 4- (diphenylamino) phenylboronic acid and tetra (tri) phenylphosphite palladium, dissolving in an organic solvent A under the action of an alkaline substance A under the condition of nitrogen protection, reacting at a reflux temperature for 8-12 hours to obtain a reaction mixed solution B, and carrying out aftertreatment to obtain a product 2-triphenylamine-7-bromo-9-fluorenone shown in formula 2; the amount ratio of the 2, 7-dibromo-9 fluorenone, 4- (diphenylamino) phenylboronic acid and tetra (di) phenylphosphide palladium shown in the formula 1 is 1: 0.5-1: 0.001-0.005; the alkaline substance A is added in the form of aqueous solution, and the addition amount of the water is based on just dissolving the alkaline substance A; the adding amount of the alkaline substance A is 2-4 mol/L based on the volume of the organic solvent A;

(2) dissolving 2-triphenylamine-7-bromo-9-fluorenone shown in formula 2, tributyl (2, 3-dihydrothieno [3,4-B ] - [1,4] dioxin-5-yl) stannane and bis (triphenylphosphine) palladium dichloride in an organic solvent B under the action of an alkaline substance B under the condition of nitrogen protection, reacting at the reflux temperature for 24-36 hours to obtain a reaction mixed solution C, and carrying out post-treatment to obtain a D-A-D' asymmetric structure monomer EWT shown in formula 3; the mass ratio of the 2-triphenylamine-7-bromo-9-fluorenone to the tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane and the bis (triphenylphosphine) palladium dichloride is 1: 1-2: 0.001-0.005; the alkaline substance B is added in the form of aqueous solution, and the addition amount of the water is based on just dissolving the alkaline substance B; the addition amount of the organic solvent A is 10-100 mL/mmol based on the amount of the 2, 7-dibromo-9 fluorenone substance shown in the formula 1; the adding amount of the alkaline substance B is 2-4 mol/L based on the volume of the organic solvent B; the addition amount of the organic solvent B is 10-100 mL/mmol based on the amount of the 2-triphenylamine-7-bromo-9-fluorenone substance shown in the formula 2;

(3) dissolving the D-A-D' asymmetric structure monomer EWT and supporting electrolyte obtained in the step (3) in an electrolytic solvent to obtain electrolyte, performing deposition reaction in a three-electrode electrolytic cell by adopting a cyclic voltammetry anodic oxidation polymerization method under the conditions that the polymerization voltage range is 0-1.6 Vvs. Ag/AgCl and the number of polymerization cycle turns is 2-32, obtaining a polymer film deposited on a working electrode after the reaction is completed, and cleaning and drying by using an organic solvent to obtain a polymer film PEWT shown in a formula 4; the supporting electrolyte is ammonium salt, lithium salt or 1-butyl-3-methylimidazolium tetrafluoroborate; the electrolytic cell solvent is a mixed solvent of acetonitrile (chromatographic grade) and dioxymethane (chromatographic grade) with the volume ratio of 1: 0.1-10; the addition amount of the D-A-D 'asymmetric structure monomer EWT or the supporting electrolyte is calculated by the volume beam of the electrolytic solvent, the initial final concentration of the D-A-D' asymmetric structure monomer EWT is 0.1-10 mmol/L of the electrolytic solvent, and the initial final concentration of the supporting electrolyte is 0.01-1 mol/L of the electrolytic solvent;

the three-electrode system consists of an electrolytic cell, a working electrode, an auxiliary electrode and a reference electrode, wherein the working electrode is an Indium Tin Oxide (ITO) conductive glass, FTO or PET conductive film electrode, the auxiliary electrode is a platinum electrode or a platinum carbon electrode, the reference electrode is Ag/AgCl and takes 3mol/L potassium chloride aqueous solution as a first liquid connection, and the electrolyte is taken as a second liquid connection;

further, the 2, 7-dibromo-9 fluorenone represented by formula 1 may be prepared according to the following method:

taking fluorenone as a raw material, iodine as a catalyst and water as a solvent, dropwise adding liquid bromine under the stirring state, carrying out bromination reaction for 4-6 hours at 100 ℃ to obtain a reaction mixed solution A, carrying out suction filtration after the system is cooled, washing the obtained filter cake with a saturated sodium bisulfite solution and deionized water in sequence, and drying to obtain 2, 7-dibromo-9 fluorenone shown in formula 1; the amount ratio of iodine to fluorenone to liquid bromine is 1: 150: 300-450; the addition amount of the water is 1.5-2 ml/mmol based on the amount of the fluorenone substance.

In step (1), the alkaline substance a is sodium carbonate, sodium bicarbonate, potassium carbonate or the like, preferably potassium carbonate.

Furthermore, in the step (1), the organic solvent a is a mixed solvent of tetrahydrofuran and toluene mixed at any ratio, and preferably a mixed solution of tetrahydrofuran and toluene at a volume ratio of 1: 0.5-2.

Further, in the step (1), the post-treatment process of the obtained reaction mixed liquid B is as follows: after the reaction is finished, adding dichloromethane into the obtained reaction mixed liquid B for extraction, combining organic phases, drying by using anhydrous magnesium sulfate, carrying out rotary evaporation on a sample, taking a mixed solvent of Petroleum Ether (PE) and Dichloromethane (DCM) with the volume ratio of 1: 0.5-1.5 as a mobile phase component, and carrying out chromatographic separation to obtain the 2-triphenylamine-7-bromo-9-fluorenone shown in the formula 2.

In step (2), the basic substance B is sodium carbonate, sodium bicarbonate, potassium carbonate or the like, preferably potassium carbonate.

Further, in the step (2), the organic solvent B is a mixed solvent in which tetrahydrofuran and toluene are mixed at any ratio, and the volume ratio of tetrahydrofuran to toluene is preferably 1: 0.5-2.

Furthermore, in the step (2), the post-treatment process of the obtained reaction mixed liquid C is as follows: after the reaction is finished, adding a mixed reagent of deionized water and dichloromethane into the obtained reaction mixed solution C for extraction, combining organic phases, drying by using anhydrous magnesium hydrophosphate, carrying out rotary evaporation on a mixed sample, taking a mixed solvent of Petroleum Ether (PE) and Dichloromethane (DCM) with the volume ratio of 1: 0.5-1.5 as a mobile phase component, and carrying out chromatographic separation to obtain a D-A-D' asymmetric structure monomer EWT shown in a formula 3;

further, in the step (3), the ammonium salt is tetrabutyl ammonium perchlorate (TBAP) or tetrabutyl ammonium hexafluorophosphate (TBAPF)₆)。

Further, in the step (3), the physical salt is lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, or the like.

Further, in the step (3), the organic solvent for cleaning is a mixed solvent of acetonitrile and dichloromethane, wherein the volume ratio of the acetonitrile to the dichloromethane is 1: 0.1-10.

In the step (3), the working electrode is sequentially subjected to ultrasonic washing in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone, preferably, the ultrasonic time is 15min each.

Further, in the step (3), the auxiliary electrode needs to be polished.

The thickness of the polymer film is 30-630 nm.

The structure of the monomer of the invention is characterized by nuclear magnetic resonance hydrogen (NMR) and mass spectra; the polymers were characterized by Scanning Electron Microscopy (SEM), ultraviolet-visible spectroscopy (UV), electrochemical workstation. From the NMR and mass spectra of the monomers, the formation of the monomers was confirmed; the ultraviolet-visible spectrum (UV) and the electrochemical workstation are used together to obtain the ultraviolet-visible spectrum absorption under different voltages and the contrast and response time under different spectra, thereby directly proving that the asymmetric structure of the D-A-D' improves the color display, the optical contrast or the response time of the electrochromic material under certain conditions; the appearance of the obtained polymer film is characterized by a Scanning Electron Microscope (SEM), and the D-A-D' asymmetric structure brings larger influence on the aggregation state appearance of the electrochromic material relative to the D-A-D symmetric structure.

Compared with the prior art, the invention has the beneficial effects that:

(1) the polymerization preparation method of the D-A-D' asymmetric structure material is simple and convenient, does not need harsh reaction conditions, can be operated at room temperature, does not need a complex purification process, has higher product purity and lower preparation energy consumption, and saves a material forming process, so the method has the advantages of simple and convenient operation, lower cost, easy control of the structure (size, thickness, character and the like), and is favorable for commercial application.

(3) Compared with the PEWE with a D-A-D symmetrical structure, the membrane material is electrochemically prepared, the appearance of the membrane is more fluffy, and the appearance of the PEWT membrane is not changed greatly after stability test; the actual assembly of the polymer film has revealed that the polymer film has high rigidity, and is easily broken as the film is brittle, and therefore, it is required to improve the film in the future.

(4) In the invention, the electrochemical cyclic voltammetry curve of the polymeric membrane shows that the conjugated polymer with the D-A-D' asymmetric structure has more redox sites, namely has more metastable states.

(5) The D-A-D' asymmetric conjugated polymer PEWT has more oxidation reduction peaks and richer color display. And as the voltage increases, the PEWT has more color, and when in the neutral state, the material exhibits a hardwood color; as the voltage was increased, the film slowly turned blue, showing a brilliant rock grey by the time the voltage reached 0.9V; subsequently, the voltage was slowly increased to 1.4V, showing a mineral purple color. The PEWE is sun-cured in the neutral state and is grayish purple in the oxidation state, and the color display is single.

(6) The film thickness of the material under different polymerization turns is measured by a Dektak-XT surface profiler, and the fact that the film thickness of the D-A-D' asymmetric structure material PEWT is increased more rapidly along with the cyclic voltammetry polymerization turns compared with the D-A-D symmetric structure material PEWE is found, and the phenomenon possibly has certain relation with the solubility of a material monomer and the film structure and needs to be continuously explored in the future.

(7) At 1100nm, the contrast is increased from 313% of PEWE to 48.8% of PEWT at the same film thickness; at 650nm, the contrast increased from 11.4% for PEWE to 26.7% for PEWT, and the introduction of triphenylamine groups dramatically changed its optical contrast in the visible and near infrared regions relative to the D-A-D symmetric structure polymeric film PSWS.

Drawings

FIG. 1 is an SEM photograph of a polymer thin film produced in a comparative example;

FIG. 2 is a cyclic voltammogram of a polymerization of a monomer in a comparative example;

FIG. 3 is a cyclic voltammogram of the polymeric membrane of the comparative example;

FIG. 4 is an SEM photograph of the polymer thin film obtained in example 1;

FIG. 5 is a cyclic voltammogram of the polymerization of monomers in example 1;

FIG. 6 is a cyclic voltammogram of the polymeric membrane of example 1;

FIG. 7 is a graph showing the measurement of the film thickness of polymer films in comparative examples and examples (using a Dektak-XT surface profiler);

FIG. 8 is a graph showing the optical contrast of polymer films PEWE and PEWT at the same film thickness;

Detailed Description

The invention is further described below by means of specific examples, without restricting its scope to these. The invention adopts cyclic voltammetry polymerization to prepare the polymer film, and the instruments adopted in the whole preparation process are an electrochemical workstation (CHI660E, Shanghai Chenghua instruments Co.) and a three-electrode system.

In the embodiment, the voltage range of the PEWT polymeric film in the photoelectric property test is 0-1.6V vs. Ag/AgCl.

Firstly, preparing 2, 7-dibromo-9 fluorenone, adding 4g of fluorenone, 35mL of aqueous solvent and 0.015g of iodine catalyst into a 100mL clean flask, dropwise adding 3mL of bromine under stirring, heating at 100 ℃ for 6 hours, performing suction filtration after a system is cooled, washing an obtained filter cake with saturated sodium bisulfite solution and deionized water in sequence, and drying to obtain a yellow solid target product.

In addition, tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane needs to be prepared in the experiment, and the specific steps are as follows: slowly adding n-butyllithium (1.6M) dropwise at-78 ℃, stirring for 0.5h, then raising the temperature to-40 ℃, slowly adding tributyltin chloride (18.8mmol, 6.12g) dropwise, reacting for 8h at room temperature, and separating to obtain tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane.

Comparative example

(1) Preparation of monomeric EWE

Dissolving 2, 7-dibromo-9-fluorenone (3mmol, 1.014g), tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane (7mmol, 3.0248 g), potassium carbonate (3mmol, 1.3821g) and bis (triphenylphosphine) palladium dichloride (0.025mmol, 0.01755g) in a mixed solution of tetrahydrofuran (20ML) and toluene (30ML), adding 2ML of deionized water, refluxing for 24 hours in a nitrogen atmosphere, cooling the system, extracting with a mixed reagent of deionized water and dichloromethane, adding anhydrous magnesium hydrophosphate to the obtained organic phase, drying, carrying out rotary evaporation on the sample, and selecting a corresponding mobile phase (PE: DCM ═ 1: 1.5) for chromatography to obtain a monomer (EWE). 1H NMR (500MHz, CDCl3)8.07(d, J ═ 1.6Hz, 1H), 7.82(dd, J ═ 7.9, 1.7Hz, 1H), 7.78(d, J ═ 1.8Hz, 1H), 7.61(dd, J ═ 7.9, 1.8Hz, 1H), 7.49(d, J ═ 7.9Hz, 1H), 7.39(d, J ═ 7.9Hz, 1H), 6.36(s, 1H), 4.38-4.34(m, 2H), 4.30-4.25(m, 3H), MALDI-TOF-ms (m) (m/z): 461.1[ M + H ] +.

(2) Preparation of Polymer (PEWE) Material

EWE monomer (1mmol, 0.0046g) and tetrabutylammonium perchlorate (1mmol, 0.342g) are dissolved in a mixed solution of 7ml of dichloromethane and 3ml of acetonitrile to prepare a mixed solution with the monomer concentration of 0.005mol/L and the supporting electrolyte concentration of 0.1mol/L as an electrolyte. A three-electrode electrolytic cell system is selected, indium tin conductive glass (ITO) is used as a working electrode (the indium tin conductive glass is subjected to ultrasonic washing in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone for 15min in sequence), a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double-liquid-connection type silver/silver chloride electrode is used as a reference electrode (Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). At room temperature (25 ℃), a polymer film is prepared by an electrochemical workstation through a cyclic voltammetry anodic oxidation polymerization method, wherein cyclic voltammetry refers to that a linear scanning voltage is applied to an electrode, scanning is carried out at a constant change speed, and when a certain set termination voltage is reached, the linear scanning voltage reversely returns to the originally set initial voltage. Therefore, firstly, setting the initial voltage 0v, the termination voltage 1.6v and the scanning rate 0.1v/s of the monomer polymerization, setting the number of polymerization cycles to be 26 (the thickness of the obtained polymerization film is 630nm), and starting the electrochemical workstation; as shown in FIG. 2, the graph is a cyclic voltammetry polymerization curve of a monomer, and the oxidation potential of the monomer is 0.71v, which indicates that the polymerization potential is lower, the energy consumption is less, and the practical production application is facilitated. After polymerization, a layer of polymer film is deposited on the surface of the ITO conductive glass of the working electrode, the ITO conductive glass is cleaned by dichloromethane and dried to obtain the working electrode with the polymer film deposited on the surface, as shown in figure 1, the aggregation state of the surface of the polymer film is uniform and dense as seen by an electron scanning microscope, and after 500 cyclic voltammetry stability tests, the polymer film forms a fluffy structure, which indicates that the stability of the polymer film is not ideal.

(3) Polymer (PEWE) electrochemical Performance test

Tetrabutylammonium perchlorate (1mmol, 0.342g) is dissolved in a mixed solution of 6ml dichloromethane and 4ml acetonitrile to prepare an electrolyte solution with the concentration of 0.1mol/L, a three-electrode electrolytic cell system is selected, a polymeric membrane PEWE is used as a working electrode, a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double liquid connection type silver/silver chloride electrode is used as a reference electrode (an Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). When the cyclic voltammetry curve of the polymeric film is tested at room temperature, the polymeric film has only one pair of oxidation-reduction peaks and has single color change, and the polymeric film shows solarization in a neutral state, and the oxidation state changes into grayish purple with the increase of voltage.

Example 1

(1) Preparation of monomeric EWT

Dissolving 2, 7-dibromo-9 fluorenone (3mmol, 1.044g), 4- (diphenylamino) phenylboronic acid (1.5mmol, 0.438g), potassium carbonate (2mmol, 0.2764g) and tetrakis (tri) phenylphosphoric palladium (0.0025mmol, 0.0311g) in a mixed solution of tetrahydrofuran (20ML) and toluene (30ML) under the condition of nitrogen protection, adding 2ML of deionized water, refluxing for 8 hours, after the system is cooled, extracting by using a mixed reagent of the deionized water and dichloromethane, adding anhydrous magnesium sulfate into the obtained organic phase for drying, then carrying out rotary evaporation on a sample, selecting a corresponding mobile phase for chromatography, and passing through a column to finally obtain a 2-triphenylamine-7-bromo-9-fluorenone monomer; then, 2-triphenylamine-7-bromo-9-fluorenone monomer (3mmol, 1.503g), tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane (3mmol, 1.2963g), potassium carbonate (2mmol, 0.2764g) and bis (triphenylphosphine) palladium dichloride (0.025mmol, 0.01755g) were dissolved in a mixed solution of tetrahydrofuran (20mL) and toluene (30mL), 2mL of deionized water was added, reflux was carried out for 24 hours in a nitrogen atmosphere, after the system was cooled, a mixed reagent of deionized water and dichloromethane was used for extraction, the resulting organic phase was dried over anhydrous magnesium sulfate, and then the sample was rotary-stirred, and the corresponding mobile phase (PE: DCM: 1: 1.5) was selected for chromatography and passed through a column, to obtain monomer (EWT). 1H NMR (500MHz, DMSO)8.08(d, J ═ 1.4Hz, 1H), 7.92(d, J ═ 1.5Hz, 1H), 7.82(dd, J ═ 7.9, 1.7Hz, 1H), 7.73(dd, J ═ 7.8, 1.8Hz, 1H), 7.51(d, J ═ 3.9Hz, 1H), 7.50(d, J ═ 4.1Hz, 1H), 7.39(dd, J ═ 3.6, 1.0Hz, 1H), 7.32(dd, J ═ 5.1, 1.0Hz, 1H), 7.11(dd, J ═ 5.1, 3.6 Hz, 1H), 6.35(s, 1H), 4.40-4.34(m, 2H), 4.24.24 (TOF-2 m) (ms — 2 m): 564.1[ M + H ] +.

(2) Preparation of Polymer (PEWT) Material

EWT monomer (1mmol, 0.00563g) and tetrabutylammonium perchlorate (1mmol, 0.342g) are dissolved in a mixed solution of 7ml of dichloromethane and 3ml of acetonitrile to prepare a mixed solution with the monomer concentration of 0.005mol/L and the supporting electrolyte TBAP concentration of 0.1mol/L as an electrolyte. A three-electrode electrolytic cell system is selected, indium tin conductive glass (ITO) is used as a working electrode (sequentially washed in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone for 15min in an ultrasonic mode), a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double-liquid-connection type silver/silver chloride electrode is used as a reference electrode (Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Preparing a polymer film by adopting a cyclic voltammetry anodic oxidation polymerization method at room temperature (25 ℃), firstly setting the initial voltage 0v, the final voltage 1.6v and the scanning rate 0.1v/s of the monomer polymerization, setting the number of polymerization cycles to be 16 (the thickness of the obtained polymerized film is 630nm), and starting the working procedure of an electrochemical workstation. Referring to fig. 5, which is a graph showing cyclic voltammetry polymerization curves of monomers, it can be seen that oxidation potentials of the monomers are 1.1v and 1.47v, and the monomer molecules have excellent ability to form a film by polymerization, and thus it can be seen that the structural monomer EWT has more oxidation-reduction potentials than EWE. After polymerization, a layer of polymer film is deposited on the surface of the ITO conductive glass of the working electrode, the ITO conductive glass is cleaned by dichloromethane and dried to obtain the working electrode with the polymer film deposited on the surface, as can be seen from figure 4, the surface of the polymer film is looser relative to the polymer, but after 500 cycles, the appearance change is small, and the polymer film is stable.

(3) Polymer (PEWT) electrochemical Performance test

Tetrabutylammonium perchlorate (1mmol, 0.342g) is dissolved in a mixed solution of 6ml dichloromethane and 4ml acetonitrile to prepare an electrolyte solution with the concentration of 0.1mol/L, a three-electrode electrolytic cell system is selected, a polymeric membrane PEWT is taken as a working electrode, a polished platinum wire is taken as an auxiliary electrode (the length of the platinum wire is 4cm), a double liquid connection type silver/silver chloride electrode is taken as a reference electrode (an Ag/AgCl, 3mol/L potassium chloride aqueous solution is taken as a first liquid connection, and the prepared electrolyte is taken as a second liquid connection). At room temperature, testing the cyclic voltammetry curve of the polymeric film, namely, under the polymerization voltage range of 0-1.6V vs. Ag/AgCl, carrying out cyclic voltammetry scanning on a working electrode containing the polymeric film at the rate of 0.1V/s for one week, and as can be seen from figure 6, the D-A-D' asymmetric structure conjugated polymer PEWT has more redox peaks and more abundant colors, and when the material is in a neutral state, the material shows a hardwood color; as the voltage was increased, the film slowly turned blue, showing a brilliant rock grey by the time the voltage reached 0.9V; subsequently, the voltage was slowly increased to 1.4V, showing a mineral purple color. As shown in FIG. 8 and Table 1, at the same film thickness, the contrast increased from 313% for PEWE to 48.8% for PEWT at 1100 nm; at 650nm, the contrast ratio is increased from 11.4% of PEWE to 26.7% of PEWT, and the introduction of triphenylamine groups greatly changes the optical contrast ratio in the visible and near infrared regions relative to the D-A-D symmetrical structure polymeric film PSWS, and the specific spectral kinetic performance parameters are shown in Table 1.

Table 1 shows the spectral kinetic properties of the polymer films PEWE and PEWT in comparative example and example 1

Example 2

(1) Preparation of monomeric EWT

Dissolving 2, 7-dibromo-9 fluorenone (3mmol, 1.044g), 4- (diphenylamino) phenylboronic acid (1.5mmol, 0.438g), potassium carbonate (2mmol, 0.2764g) and tetrakis (tri) phenylphosphoric palladium (0.0025mmol, 0.0311g) in a mixed solution of tetrahydrofuran (20ML) and toluene (30ML) under the condition of nitrogen protection, adding 2ML of deionized water, refluxing for 6 hours, after the system is cooled, extracting by using a mixed reagent of the deionized water and dichloromethane, adding anhydrous magnesium sulfate into the obtained organic phase for drying, then carrying out rotary evaporation and sample mixing, selecting a corresponding mobile phase for chromatography, and passing through a column to finally obtain a 2-triphenylamine-7-bromo-9-fluorenone monomer; then, 2-triphenylamine-7-bromo-9-fluorenone monomer (3mmol, 1.503g), tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane (3mmol, 1.2963g), potassium carbonate (2mmol, 0.2764g) and bis (triphenylphosphine) palladium dichloride (0.025mmol, 0.01755g) are dissolved in a mixed solution of tetrahydrofuran (20mL) and toluene (30mL), 2mL of deionized water is added, reflux is carried out for 36 hours in a nitrogen atmosphere, after the system is cooled, the obtained organic phase is added with anhydrous magnesium hydrophosphate and dried, then the sample is steamed in a rotary manner, and a corresponding mobile phase (PE: DCM ═ 1: 1.5) is selected to carry out chromatography, so that monomer (EWT) is obtained. 1H NMR (500MHz, DMSO)8.08(d, J ═ 1.4Hz, 1H), 7.92(d, J ═ 1.5Hz, 1H), 7.82(dd, J ═ 7.9, 1.7Hz, 1H), 7.73(dd, J ═ 7.8, 1.8Hz, 1H), 7.51(d, J ═ 3.9Hz, 1H), 7.50(d, J ═ 4.1Hz, 1H), 7.39(dd, J ═ 3.6, 1.0Hz, 1H), 7.32(dd, J ═ 5.1, 1.0Hz, 1H), 7.11(dd, J ═ 5.1, 3.6 Hz, 1H), 6.35(s, 1H), 4.40-4.34(m, 2H), 4.24.24 (TOF-2 m) (ms — 2 m): 564.1[ M + H ] +.

(2) Preparation of Polymer (PEWT) Material

EWT monomer (1mmol, 0.00563g) and tetrabutylammonium perchlorate (1mmol, 0.342g) are dissolved in a mixed solution of 7ml of dichloromethane and 3ml of acetonitrile to prepare a mixed solution with the monomer concentration of 0.005mol/L and the supporting electrolyte TBAP concentration of 0.1mol/L as an electrolyte. A three-electrode electrolytic cell system is selected, indium tin conductive glass (ITO) is used as a working electrode (sequentially washed in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone for 15min in an ultrasonic mode), a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double-liquid-connection type silver/silver chloride electrode is used as a reference electrode (Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Preparing a polymer film by adopting a cyclic voltammetry anodic oxidation polymerization method at room temperature (25 ℃), firstly setting the initial voltage 0v, the final voltage 1.6v and the scanning rate 0.1v/s of the monomer polymerization, setting the number of polymerization cycles to be 16 (the thickness of the obtained polymerized film is 630nm), and starting the working procedure of an electrochemical workstation. From cyclic voltammetry polymerization curves of the monomers, the oxidation potentials of the monomers are 1.1v and 1.47v, and the monomer molecules have excellent polymerization film forming capability, so that the structural monomer EWT has more oxidation-reduction potentials than EWE. After polymerization, a layer of polymer film is deposited on the surface of the ITO conductive glass of the working electrode, the ITO conductive glass is cleaned by dichloromethane and dried to obtain the working electrode with the polymer film deposited on the surface, and the surface of the polymer film is looser relative to the polymer as shown by a scanning electron microscope, but after 500 cycles, the appearance change is small, and the polymer film is stable.

(3) Polymer (PEWT) electrochemical Performance test

Tetrabutylammonium perchlorate (1mmol, 0.342g) is dissolved in a mixed solution of 6ml dichloromethane and 4ml acetonitrile to prepare an electrolyte solution with the concentration of 0.1mol/L, a three-electrode electrolytic cell system is selected, a polymeric membrane PEWT is taken as a working electrode, a polished platinum wire is taken as an auxiliary electrode (the length of the platinum wire is 4cm), a double liquid connection type silver/silver chloride electrode is taken as a reference electrode (an Ag/AgCl, 3mol/L potassium chloride aqueous solution is taken as a first liquid connection, and the prepared electrolyte is taken as a second liquid connection). Testing the cyclic voltammetry curve of the polymeric film at room temperature, namely, under the polymerization voltage range of 0-1.6V vs. Ag/AgC1, carrying out cyclic voltammetry scanning on a working electrode containing the polymeric film at the rate of 0.1V/s for one week, wherein the test shows that the D-A-D' asymmetric structure conjugated polymer PEWT has more redox peaks and more abundant colors, and when the material is in a neutral state, the material shows a hardwood color; as the voltage was increased, the film slowly turned blue, showing a brilliant rock grey by the time the voltage reached 0.9V; subsequently, the voltage was slowly increased to 1.4V, showing a mineral purple color. At the same film thickness, at 1100nm, the contrast is increased from 31.3% of PEWE to 48.8% of PEWT; at 650nm, the contrast increased from 11.4% for PEWE to 26.7% for PEWT, and the introduction of triphenylamine groups dramatically changed its optical contrast in the visible and near infrared regions relative to the D-A-D symmetric structure polymeric film PSWS.

Example 3

(1) Preparation of monomeric EWT

(2) Preparation of Polymer (PEWT) Material

EWT monomer (1mmol, 0.00563g) and tetrabutylammonium perchlorate (1mmol, 0.342g) are dissolved in a mixed solution of 7ml of dichloromethane and 3ml of acetonitrile to prepare a mixed solution with the monomer concentration of 0.005mol/L and the supporting electrolyte TBAP concentration of 0.1mol/L as an electrolyte. A three-electrode electrolytic cell system is selected, indium tin conductive glass (ITO) is used as a working electrode (sequentially washed in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone for 15min in an ultrasonic mode), a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double-liquid-connection type silver/silver chloride electrode is used as a reference electrode (Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Preparing a polymer film by adopting a cyclic voltammetry anodic oxidation polymerization method at room temperature (25 ℃), firstly setting the initial voltage 0v, the final voltage 1.6v and the scanning rate 0.05v/s of the monomer polymerization, setting the number of polymerization cycles to be 16 (the thickness of the obtained polymerized film is 630nm), and starting the working procedure of an electrochemical workstation. From cyclic voltammetry polymerization curves of the monomers, the oxidation potentials of the monomers are 1.1v and 1.47v, and the monomer molecules have excellent polymerization film forming capability, so that the structural monomer EWT has more oxidation-reduction potentials than EWE. After polymerization, a layer of polymer film is deposited on the surface of the ITO conductive glass of the working electrode, the ITO conductive glass is cleaned by dichloromethane and dried to obtain the working electrode with the polymer film deposited on the surface, and the surface of the polymer film is looser relative to the polymer as shown by a scanning electron microscope, but after 500 cycles, the appearance change is small, and the polymer film is stable.

(3) Polymer (PEWT) electrochemical Performance test

Tetrabutylammonium perchlorate (1mmol, 0.342g) is dissolved in a mixed solution of 6ml dichloromethane and 4ml acetonitrile to prepare an electrolyte solution with the concentration of 0.1mol/L, a three-electrode electrolytic cell system is selected, a polymeric membrane PEWT is taken as a working electrode, a polished platinum wire is taken as an auxiliary electrode (the length of the platinum wire is 4cm), a double liquid connection type silver/silver chloride electrode is taken as a reference electrode (an Ag/AgCl, 3mol/L potassium chloride aqueous solution is taken as a first liquid connection, and the prepared electrolyte is taken as a second liquid connection). Testing the cyclic voltammetry curve of the polymeric membrane at room temperature, namely under the polymerization voltage range of 0-1.6V vs. Ag/AgCl, carrying out cyclic voltammetry scanning on a working electrode containing the polymeric membrane at the rate of 0.05V/s for one week, wherein the test shows that the D-A-D' asymmetric structure conjugated polymer PEWT has more redox peaks and more abundant colors, and the material shows a hardwood color when in a neutral state; as the voltage was increased, the film slowly turned blue, showing a brilliant rock grey by the time the voltage reached 0.9V; subsequently, the voltage was slowly increased to 1.4V, showing a mineral purple color. At the same film thickness, at 1100nm, the contrast is increased from 31.3% of PEWE to 48.8% of PEWT; at 650nm, the contrast increased from 11.4% for PEWE to 26.7% for PEWT, and the introduction of triphenylamine groups dramatically changed its optical contrast in the visible and near infrared regions relative to the D-A-D symmetric structure polymeric film PSWS.

Example 4

(1) Preparation of monomeric EWT

(2) Preparation of Polymer (PEWT) Material

EWT monomer (1mmol, 0.00563g) and lithium hexafluorophosphate (1mmol, 0.152g) are dissolved in a mixed solution of 7ml of dichloromethane and 3ml of acetonitrile to prepare a mixed solution with a monomer concentration of 0.005mol/L and a supporting electrolyte TBAP concentration of 0.1mol/L as an electrolyte. A three-electrode electrolytic cell system is selected, indium tin conductive glass (ITO) is used as a working electrode (sequentially washed in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone for 15min in an ultrasonic mode), a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double-liquid-connection type silver/silver chloride electrode is used as a reference electrode (Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Preparing a polymer film by adopting a cyclic voltammetry anodic oxidation polymerization method at room temperature (25 ℃), firstly setting the initial voltage 0v, the final voltage 1.6v and the scanning rate 0.1v/s of the monomer polymerization, setting the number of polymerization cycles to be 16 (the thickness of the obtained polymerized film is 630nm), and starting the working procedure of an electrochemical workstation. From cyclic voltammetry polymerization curves of the monomers, the oxidation potentials of the monomers are 1.1v and 1.47v, and the monomer molecules have excellent polymerization film forming capability, so that the structural monomer EWT has more oxidation-reduction potentials than EWE. After polymerization, a layer of polymer film is deposited on the surface of the ITO conductive glass of the working electrode, the ITO conductive glass is cleaned by dichloromethane and dried to obtain the working electrode with the polymer film deposited on the surface, and the surface of the polymer film is looser relative to the polymer as shown by a scanning electron microscope, but after 500 cycles, the appearance change is small, and the polymer film is stable.

(3) Polymer (PEWT) electrochemical Performance test

Lithium hexafluorophosphate (1mmol, 0.152g) is dissolved in a mixed solution of 6ml dichloromethane and 4ml acetonitrile to prepare an electrolyte solution with the concentration of 0.1mol/L, a three-electrode electrolytic cell system is selected, a polymeric membrane PEWT is used as a working electrode, a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double liquid connection type silver/silver chloride electrode is used as a reference electrode (an Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Testing a cyclic voltammetry curve of the polymeric film at room temperature, namely, under the condition that the polymerization voltage range is 0-1.6V vs. Ag/AgCl, carrying out cyclic voltammetry scanning on a working electrode containing the polymeric film at the rate of 0.1V/s for one week, wherein the cyclic voltammetry curve of the polymeric film shows that the D-A-D' asymmetric structure conjugated polymer PEWT has more redox peaks and more abundant colors, and the material shows a hardwood color when being in a neutral state; as the voltage was increased, the film slowly turned blue, showing a brilliant rock grey by the time the voltage reached 0.9V; subsequently, the voltage was slowly increased to 1.4V, showing a mineral purple color. According to the test, at 1100nm, the contrast is increased from 31.3% of PEWE to 48.8% of PEWT under the same film thickness; at 650nm, the contrast increased from 11.4% for PEWE to 26.7% for PEWT, and the introduction of triphenylamine groups dramatically changed its optical contrast in the visible and near infrared regions relative to the D-A-D symmetric structure polymeric film PSWS.

Example 5

(1) Preparation of monomeric EWT

(2) Preparation of Polymer (PEWT) Material

EWT monomer (1mmol, 0.00563g) and tetrabutylammonium perchlorate (1mmol, 0.342g) are dissolved in a mixed solution of 7ml of dichloromethane and 3ml of acetonitrile to prepare a mixed solution with the monomer concentration of 0.005mol/L and the supporting electrolyte TBAP concentration of 0.1mol/L as an electrolyte. A three-electrode electrolytic cell system is selected, indium tin conductive glass (ITO) is used as a working electrode (sequentially washed in 0.1% sodium hydroxide solution, absolute ethyl alcohol, acetone, toluene, absolute ethyl alcohol, toluene and acetone for 15min in an ultrasonic mode), a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double-liquid-connection type silver/silver chloride electrode is used as a reference electrode (Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Preparing a polymer film by adopting a cyclic voltammetry anodic oxidation polymerization method at room temperature (25 ℃), firstly setting the initial voltage 0v, the final voltage 1.6v and the scanning rate 0.1v/s of the monomer polymerization, setting the number of polymerization cycles to be 16 (the thickness of the obtained polymerized film is 630nm), and starting the working procedure of an electrochemical workstation. From cyclic voltammetry curves of the monomers, the oxidation potentials of the monomers are 1.1v and 1.47v, and the monomer molecules have excellent polymerization film forming capability, so that the structural monomer EWT has more oxidation-reduction potentials than EWE. After polymerization, a layer of polymer film is deposited on the surface of the ITO conductive glass of the working electrode, the ITO conductive glass is cleaned by dichloromethane and dried to obtain the working electrode with the polymer film deposited on the surface, and a scanning electron microscope shows that the surface of the polymer film is looser relative to the polymer, but after 500 cycles, the appearance change is small, and the polymer film is stable.

(3) Polymer (PEWT) electrochemical Performance test

Tetrabutylammonium perchlorate (1mmol, 0.342g) is dissolved in a mixed solution of 12ml dichloromethane and 8ml acetonitrile to prepare an electrolyte solution with the concentration of 0.05mol/L, a three-electrode electrolytic cell system is selected, a polymeric membrane PEWT is used as a working electrode, a polished platinum wire is used as an auxiliary electrode (the length of the platinum wire is 4cm), a double liquid connection type silver/silver chloride electrode is used as a reference electrode (an Ag/AgCl, 3mol/L potassium chloride aqueous solution is used as a first liquid connection, and the prepared electrolyte is used as a second liquid connection). Testing a cyclic voltammetry curve of the polymeric film at room temperature, namely under the condition that the polymerization voltage range is 0-1.6V vs. Ag/AgCl, carrying out cyclic voltammetry scanning on a working electrode containing the polymeric film at the rate of 0.1V/s for one week, wherein the test shows that the D-A-D' asymmetric structure conjugated polymer PEWT has more redox peaks and more abundant colors, and the material shows a hardwood color when being in a neutral state; as the voltage was increased, the film slowly turned blue, showing a brilliant rock grey by the time the voltage reached 0.9V; subsequently, the voltage was slowly increased to 1.4V, showing a mineral purple color. At the same film thickness, at 1100nm, the contrast is increased from 31.3% of PEWE to 48.8% of PEWT; at 650nm, the contrast increased from 11.4% for PEWE to 26.7% for PEWT, and the introduction of triphenylamine groups dramatically changed its optical contrast in the visible and near infrared regions relative to the D-A-D symmetric structure polymeric film PSWS.

Claims

1. A polymer film PEWT of D-A-D' asymmetric structure, characterized in that: the D-A-D' asymmetric structure polymeric membrane PEWT is prepared by the following method:

(1) mixing 2, 7-dibromo-9 fluorenone shown in formula 1 with 4- (diphenylamino) phenylboronic acid and tetra (tri) phenylphosphite palladium, dissolving in an organic solvent A under the protection of nitrogen under the action of an alkaline substance A, reacting at a reflux temperature for 8-12 hours to obtain a reaction mixed solution B, and carrying out post-treatment to obtain a product 2-triphenylamine-7-bromo-9-fluorenone shown in formula 2; the mass ratio of the 2, 7-dibromo-9 fluorenone to the 4- (diphenylamino) phenylboronic acid and the tetra (tri) phenylphosphide palladium shown in the formula 1 is 1: 0.5-1: 0.001 to 0.005; the alkaline substance A is added in the form of aqueous solution, and the addition amount of the water is based on just dissolving the alkaline substance A; the adding amount of the alkaline substance A is 2-4 mol/L based on the volume of the organic solvent A; the addition amount of the organic solvent A is 10-100 mL/mmol based on the amount of the 2, 7-dibromo-9 fluorenone substance shown in the formula 1;

(2) dissolving 2-triphenylamine-7-bromo-9-fluorenone shown in formula 2, tributyl (2, 3-dihydrothieno [3,4-B ] - [1,4] dioxin-5-yl) stannane and bis (triphenylphosphine) palladium dichloride in an organic solvent B under the protection of nitrogen under the action of an alkaline substance B, reacting at a reflux temperature for 24-36 hours to obtain a reaction mixed solution C, and performing post-treatment to obtain a D-A-D' asymmetric structure monomer EWT shown in formula 3; the mass ratio of the 2-triphenylamine-7-bromo-9-fluorenone to the tributyl (2, 3-dihydrothieno [3,4-b ] - [1,4] dioxin-5-yl) stannane and the bis (triphenylphosphine) palladium dichloride is 1: 1-2: 0.001 to 0.005; the alkaline substance B is added in the form of aqueous solution, and the addition amount of the water is based on just dissolving the alkaline substance B; the adding amount of the alkaline substance B is 2-4 mol/L based on the volume of the organic solvent B; the addition amount of the organic solvent B is 10-100 mL/mmol based on the amount of the 2-triphenylamine-7-bromo-9-fluorenone substance shown in the formula 2;

(3) dissolving the D-A-D' asymmetric structure monomer EWT and supporting electrolyte obtained in the step (3) in an electrolytic solvent to obtain electrolyte, performing deposition reaction in a three-electrode electrolytic cell by adopting a cyclic voltammetry anodic oxidation polymerization method under the conditions that the polymerization voltage range is 0-1.6V vs. Ag/AgCl and the number of polymerization cycles is 2-32, obtaining a polymer film deposited on a working electrode after the reaction is completed, and cleaning and drying by using an organic solvent to obtain a polymer film PEWT shown in a formula 4; the supporting electrolyte is ammonium salt, lithium salt or 1-butyl-3-methylimidazolium tetrafluoroborate; the volume ratio of the electrolytic cell solvent is 1: 0.1-10 parts of a mixed solvent of acetonitrile and dichloromethane; the addition amount of the D-A-D 'asymmetric structure monomer EWT or the supporting electrolyte shown in the formula 3 is calculated by the volume of the electrolytic solvent, the initial final concentration of the D-A-D' asymmetric structure monomer EWT shown in the formula 3 is 0.1-10 mmol/L of the electrolytic solvent, and the initial final concentration of the supporting electrolyte is 0.01-1 mol/L of the electrolytic solvent;

the three-electrode system consists of an electrolytic cell, a working electrode, an auxiliary electrode and a reference electrode, wherein the working electrode is Indium Tin Oxide (ITO) conductive glass, FTO or PET conductive film electrode, the auxiliary electrode is a platinum electrode or a platinum carbon electrode, the reference electrode is Ag/AgCl and takes 3mol/L potassium chloride aqueous solution as a first liquid connection, and the electrolyte is taken as a second liquid connection;

2. the D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (1), the alkaline substance A is sodium carbonate, sodium bicarbonate or potassium carbonate.

3. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (1), the organic solvent A is a mixed solvent of tetrahydrofuran and toluene in any proportion.

4. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (2), the alkaline substance B is sodium carbonate, sodium bicarbonate or potassium carbonate.

5. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (2), the organic solvent B is a mixed solvent of tetrahydrofuran and toluene in any proportion.

6. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (2), the post-treatment process of the obtained reaction mixed liquid C is as follows: after the reaction is finished, adding a mixed reagent of deionized water and dichloromethane into the obtained reaction mixed solution C for extraction, combining organic phases, drying by anhydrous magnesium sulfate, carrying out rotary evaporation and sample mixing, and mixing the organic phases in a volume ratio of 1: the mixed solvent of petroleum ether and dichloromethane of 0.5-2.5 is used as a mobile phase component, and the asymmetric structural monomer EWT D-A-D' shown in the formula 3 is obtained through chromatographic separation.

7. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (3), the ammonium salt is tetrabutylammonium perchlorate or tetrabutylammonium hexafluorophosphate.

8. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (3), the lithium salt is lithium hexafluorophosphate, lithium tetrafluoroborate or lithium trifluoromethanesulfonate.

9. The D-a-D' asymmetric structure polymeric membrane PEWT of claim 1, wherein: in the step (3), the organic solvent for cleaning is a mixed solvent of acetonitrile and dichloromethane with a volume ratio of 1: 0.1-10.

10. The use of the D-a-D' asymmetric-structured polymeric film PEWT of claim 1 for the preparation of electrochromic devices.