Ketone-containing polycarbazole derivative electrochromic polymer as well as preparation method and application thereof

Abstract

The invention provides a ketone-containing poly-carbazole derivative electrochromic polymer, the structural formula of which is as shown in formula I. In the formula I, R is one of a C6-C40 alkane chain and an alkoxy hydrocarbon chain; m is 0-1, n is the degree of polymerization, and n is 10-200; the number-average molecular weight Mn of the ketone-containing polycarbazole derivative electrochromic polymer is 1000 to 5000 Da, and the polydispersity coefficient D of the ketone-containing polycarbazole derivative electrochromic polymer is 1.0 to 4.0. The ketone-containing poly-carbazole derivative electrochromic polymer film prepared by the invention has the characteristics of high transparency in a neutral state, color in an oxidation state, excellent solution processability and the like, and has wide application prospects in the fields of energy-saving displays, static information display and dynamic information encryption, military camouflage and the like.

Description

Technical Field

[0001] This invention relates to the field of functional polymers and electrochromic materials, and in particular to a ketone-containing polycarbazole derivative electrochromic polymer, its preparation method, and its applications. Background Technology

[0002] Electrochromic materials are smart materials that can undergo reversible and stable color changes under the influence of an applied electric field. They have broad application prospects in fields such as smart windows, anti-glare rearview mirrors, energy-saving displays, and military camouflage. An ideal electrochromic material typically needs to possess high optical contrast, fast response speed, good cycling stability, and excellent synthesis conditions.

[0003] Among the many electrochromic materials, some highly conjugated polymers have good stability, but due to the high conjugation of their main chain and the narrow band gap, most of the materials exhibit color-changing behavior of "colored in the neutral state to colorless in the oxidized state", and the oxidized state is usually grayish-white with poor transparency.

[0004] A Chinese patent document, CN202110685398.7, discloses an "electrochromic polymer with high transmittance from neutral cyan to oxidized state." However, the electrochromic polymer material in this technology still exhibits a transmittance of less than 75% in the oxidized state, severely limiting its application in scenarios requiring a colorless initial state, such as smart windows and displays. Furthermore, its transparency is only achieved in the oxidized state, which is detrimental to energy-saving goals in practical applications. In addition, this type of material relies on synthetic methods such as arylation polycondensation, which involve cumbersome steps and stringent conditions, further restricting the controllable preparation and widespread application of the material.

[0005] Therefore, there is an urgent need in this field to develop an efficient preparation route for electrochromic polymers that is simple to synthesize, highly transparent in the neutral state, and highly colorimetric in the oxidized state. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a ketone-containing polycarbazole derivative electrochromic polymer, its preparation method, and its application, in order to solve the problem that the low transmittance of existing electrochromic polymer materials in the oxidized state severely limits their application in scenarios requiring a colorless initial state, such as smart windows and displays.

[0007] To achieve the above and other related objectives, the present invention provides an electrochromic polymer containing a ketone-type poly-carbazole derivative, the structural formula of which is shown in Formula I: .

[0008] In Formula I, R is one of the alkane chain and alkoxycarbon chain of C6~C40; m is the number of benzene rings, m is 0 or 1; n is the degree of polymerization, n is 10~200.

[0009] The number-average molecular weight M of the ketone-containing polycarbazole derivative electrochromic polymer n The range is 1000~5000 Da, and the polydispersity index D is 1.0~4.0.

[0010] This application contains a ketone-type poly-carbazole derivative electrochromic polymer. The butanedione unit is embedded in the polymer backbone as a "spacer group" to break the continuous conjugation of the polymer backbone, so that it has a wide optical band gap and thus exhibits neutral, colorless and highly transparent properties. This application uses carbazole, whose structure is easy to modify, as the core color-changing unit and achieves precise control of the color-changing properties of the material through rational molecular design.

[0011] This application also provides a method for preparing the above-mentioned electrochromic polymer containing ketone-type polycarbazole derivatives, comprising the following steps:

[0012] (1) Add the carbazolyl compound to a first organic solvent containing an inorganic base, stir to dissolve, and then add an alkane to carry out a nucleophilic substitution reaction to obtain the monomer shown in Formula II; .

[0013] (2) The monomer shown in Formula II is added to the second organic solvent, and then butanedione and Lewis acid catalyst are added to carry out the polymerization reaction to obtain the ketone-containing polycarbazole derivative electrochromic polymer shown in Formula I.

[0014] In Formula II, R is one of the alkane chain and alkoxycarbon chain of C6~C40; m is the number of benzene rings, m is 0 or 1.

[0015] The ketone-containing poly-carbazole derivative electrochromic polymer of the present invention is prepared and synthesized by nucleophilic substitution reaction and Friedel-Crafts hydroxyalkylation polycondensation reaction.

[0016] Preferably, in step (1), the carbazolyl compound is carbazolyl or 3,6-diphenyl-9H-carbazolyl.

[0017] Preferably, in step (1), the alkane is a 1-bromoalkane or an alkoxyalkane.

[0018] To improve the solubility of ketone-containing poly-carbazole derivative electrochromic polymers, this invention uses a carbazole derivative monomer with an alkane chain or alkoxy hydrocarbon chain introduced onto the carbazole ring. The monomer is then blended with diacetone under Lewis acid catalysis and subjected to Friedel-Crafts hydroxyalkylation polycondensation reaction to prepare the ketone-containing poly-carbazole derivative electrochromic polymer.

[0019] Preferably, in step (1), the inorganic base is potassium hydroxide or sodium hydroxide.

[0020] Preferably, in step (1), the first organic solvent is one or both of dimethyl sulfoxide and tetrahydrofuran.

[0021] Preferably, in step (1), the reaction temperature is 25~45 ℃ and the reaction time is 12~24 h.

[0022] Preferably, step (1) further includes a post-processing step, in which the organic phases are extracted with saturated brine and dichloromethane, combined, dried, and separated by column chromatography to obtain the monomer shown in formula II.

[0023] Preferably, in step (2), the Lewis acid catalyst is one or more of ferric chloride, aluminum chloride, sulfuric acid, p-toluenesulfonic acid and trifluoromethanesulfonic acid.

[0024] Preferably, in step (2), the second organic solvent is one or both of dichloromethane and 1,2-dichloroethane.

[0025] Preferably, in step (2), the molar ratio of the monomer shown in Formula II to dimethyl ethyl ketone is 1:(1~1.5); the molar ratio of the monomer shown in Formula II to Lewis acid catalyst is 1:(5~20).

[0026] Preferably, in step (2), the Lewis acid catalyst is added at -10 to 0 °C; the polymerization temperature is 25 to 45 °C; and the polymerization time is 36 to 72 h.

[0027] Preferably, step (2) further includes a post-processing step: slowly pouring the reaction mixture into methanol, filtering, drying, extracting with methanol, acetone and hexane in sequence, and finally collecting the solid polymer to obtain a light green solid polymer, which is the ketone-containing polycarbazole derivative electrochromic polymer as shown in Formula I.

[0028] This application also provides an application of the above-mentioned ketone-containing poly-carbazole derivative electrochromic polymer in the preparation of electrochromic polymer films.

[0029] Preferably, an electrochromic polymer film is obtained by solution processing of a ketone-type poly-carbazole derivative electrochromic polymer.

[0030] The above-mentioned ketone-containing poly-carbazole derivative electrochromic polymer is dissolved in an organic solvent and then formed into a film by solution processing methods (such as spin coating, drop coating, spray coating, or blade coating). The film exhibits high optical contrast, good cycling stability, and good film-forming properties.

[0031] As a further preferred embodiment, the solution processing for film formation specifically involves: dissolving the aforementioned ketone-containing poly-carbazole derivative electrochromic polymer in a solvent to obtain a solution, then coating the solution onto a conductive substrate and drying it to obtain an electrochromic polymer film. More preferably, the solvent is dichloromethane, trichloromethane, tetrahydrofuran, etc.

[0032] In this invention, the coating method can be spraying, spin coating, screen printing, etc. The conductive substrate can be ITO glass, FTO glass, ITO-PET substrate, FTO-PET substrate, etc.

[0033] The present invention also provides an electrochromic polymer film prepared from the above-mentioned ketone-containing poly-carbazole derivative electrochromic polymer.

[0034] As described above, the ketone-containing polycarbazole derivative electrochromic polymer, its preparation method, and its application of the present invention have the following beneficial effects:

[0035] (1) The electrochromic polymer containing ketone-type poly-carbazole derivatives in this application uses dimethylglyoxal (DME) units as "spacer groups" embedded in the polymer backbone to break the continuous conjugation of the polymer backbone, thereby giving it a wide optical band gap and exhibiting neutral, colorless, and highly transparent properties; the application uses carbazole, whose structure is easy to modify, as the core color-changing unit, and achieves precise control of the color-changing properties of the material through rational molecular design.

[0036] (2) In order to improve the solubility of the ketone-containing poly-carbazole derivative electrochromic polymer, the present invention introduces a carbazole derivative with an alkane chain or alkoxy hydrocarbon chain on the carbazole ring as a monomer, and prepares the ketone-containing poly-carbazole derivative electrochromic polymer by blending it with dimethyl butane under Lewis acid catalysis and Friedel-Crafts hydroxyalkylation polycondensation reaction.

[0037] (3) The ketone-containing poly-carbazole derivative electrochromic polymer films prepared by the present invention have the characteristics of high transparency in the neutral state, color in the oxidized state and excellent solution processability, and have broad application prospects in energy-saving displays, static information display and dynamic information encryption, military camouflage and other fields. Attached Figure Description

[0038] Figure 1 The image shows the cyclic voltammetry curves of the thin film prepared using the polymer PC-2 from Example 1.

[0039] Figure 2 The image shows the cyclic voltammetry curves of the thin film prepared using the polymer PLC-2 from Example 2.

[0040] Figure 3 The images show the UV-Vis absorption spectra of the thin film prepared using polymer PC-2 from Example 1 at different voltages.

[0041] Figure 4 The images show the UV-Vis absorption spectra of the thin film prepared using polymer PLC-2 from Example 2 at different voltages.

[0042] Figure 5 The transmittance spectra of the film prepared using polymer PC-2 from Example 1 in the neutral and oxidized states are shown.

[0043] Figure 6 The transmittance spectra of the thin film prepared using polymer PLC-2 from Example 2 are shown in the neutral and oxidized states.

[0044] Figure 7 The graph shows the response time of the transmittance of the thin film prepared using polymer PLC-2 in Example 2 as a function of time under multiple potential steps from 0 to 1.3 V at a wavelength of 643 nm.

[0045] Figure 8 The graph shows the cyclic stability of the thin film prepared using polymer PLC-2 from Example 2, under multiple potential steps from 0 to 1.3 V at a wavelength of 643 nm, as a function of time.

[0046] Figure 9 The graph shows the response time of the transmittance of the thin film prepared using polymer PLC-2 in Example 2 as a function of time under multiple potential steps from 0 to 1.3 V at a wavelength of 926 nm.

[0047] Figure 10 The graph shows the cyclic stability of the thin film prepared using polymer PLC-2 from Example 2, under multiple potential steps from 0 to 1.3 V at a wavelength of 926 nm, as a function of time. Detailed Implementation

[0048] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0050] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0051] Example 1

[0052] This embodiment provides a method for preparing an electrochromic polymer containing a ketone-type poly-carbazole derivative, as described in Route 1, including the following steps: .

[0053] Route 1

[0054] (1) Carbazole (1.00 g, 5.98 mmol) and KOH (0.26 g, 4.78 mmol) were placed in a 50 mL double-necked round-bottom flask, and THF (20 mL) was added. The mixture was stirred to dissolve the mixture. Then, 1-bromooctane (1.38 g, 7.17 mmol) was added to the mixture, and the mixture was stirred at room temperature for 12 h. Subsequently, the reaction mixture was extracted multiple times with saturated brine and dichloromethane. The organic layer was dried with Na2SO4 and concentrated to obtain the crude product. The crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether (volume ratio 1:3) as eluent to obtain a yellow liquid monomer C (1.37 g, 64%).

[0055] The 1H NMR characterization data of monomer C are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.24 (d, J=4.6 Hz, 2H), δ 7.58 (t, J=4.4 Hz, 2H), δ 7.52 (d, J=5.6 Hz, 2H), δ7.36 (t, J=4.8 Hz, 2H), δ 4.37 (t, J=4.6 Hz, 2H), δ 1.96 (m, J=2.8 Hz, 2 H), δ 1.49-1.37 (m, J=5.6 Hz, 10H), δ 1.02 (t, J=8.0 Hz, 3H).

[0056] (2) Monomer C (250 mg, 0.89 mmol) and dimethyl ethyl ketone (0.10 g, 1.20 mmol) were added to a 35 mL reaction tube. The mixture was cooled in an ice bath, followed by the addition of dichloromethane (1 mL) and stirring for 10 minutes. Then, trifluoromethanesulfonic acid (3 mL) was added dropwise, the ice bath was removed, and the reaction mixture was stirred at room temperature for 60 h. After the reaction was completed, the system was poured into 100 mL of methanol to precipitate the solid. The solid was collected by filtration and then dissolved in tetrahydrofuran. The solid was precipitated again in methanol and filtered. Subsequently, the solid product was purified by Soxhlet extraction with methanol to finally obtain a light brown solid polymer PC-2 (364 mg, 87%, degree of polymerization n = 13).

[0057] The 1H NMR characterization data of polymer PC-2 are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.33-8.11(m, 2H), δ 7.11 (m, J=4.4 Hz, 4H), δ 4.23 (t, J=2.1 Hz, 2H), δ 2.30-2.09 (m,3H), δ 1.97 (m, J=2.1 Hz, 2H), δ 1.50-1.39 (m, 2H), δ 1.22 (s, J=9.4 Hz, 10H), δ 0.84 (t, J=3.5 Hz, 3H).

[0058] Example 2

[0059] This embodiment provides a method for preparing an electrochromic polymer containing a ketone-type poly-carbazole derivative, as described in Route 2, including the following steps: .

[0060] Route 2

[0061] (1) 3,6-Diphenyl-9H-carbazole (1.00 g, 3.13 mmol) and KOH (0.14 g, 2.50 mmol) were placed in a 50 mL double-necked round-bottom flask; DMSO (15 mL) was added and stirred to dissolve the mixture. Then 1-bromooctane (0.72 g, 3.75 mmol) was added, and the mixture was stirred at room temperature for 12 h. The reaction mixture was extracted multiple times with saturated brine and dichloromethane; the organic layer was dried with Na2SO4 and concentrated to obtain the crude product. The crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether (v / v 1:1) as eluents, and the purified and separated monomer LC (1.18 g, 74%) was obtained.

[0062] The 1H NMR characterization data of the monomer LC are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.39 (s, J=1.7 Hz, 2H), δ 7.76 (d, J=3.2Hz, 6H), δ 7.51 (m, J=2.6 Hz, 6H), δ 7.37 (t, J=1.2 Hz, 2H), δ 4.37 (t, J=1.0Hz, 2H), δ 1.96 (m, J=0.6 Hz, 2H), δ 1.45-1.28 (m, J=1.6 Hz, 10H), δ 0.9 (t,J=1.8 Hz, 3H).

[0063] Monomer LC (500 mg, 1.15 mmol) and dimethyl ethyl ketone (0.12 g, 1.38 mmol) were added to a 35 mL reaction tube. The mixture was cooled in an ice bath, followed by the addition of dichloromethane (1 mL) and stirring for 10 min; then trifluoromethanesulfonic acid (3 mL) was added dropwise; the ice bath was removed, and the reaction mixture was stirred at room temperature for 72 h; subsequently, it was precipitated in methanol (100 mL), and the solid product was collected by filtration. The solid product was dissolved in tetrahydrofuran, precipitated again in methanol, and filtered. Finally, the solid product was purified by Soxhlet extraction with methanol to obtain a pale green solid polymer PLC-2 (520 mg, 88%, degree of polymerization n = 21). (M) n =2.55 kDa, PDI = 1.20).

[0064] The 1H NMR characterization data of polymer PLC-2 are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.39 (s, J=2.6 Hz, 2H) δ 7.76 (d, J=5.4 Hz, 6H), δ 7.50 (m, J=4.4 Hz, 6H), δ 7.37 (t, J=2.1 Hz, 2H), δ 4.37 (t, J=1.8 Hz,2H), δ 2.27-2.03 (m, 3H), δ 1.95 (m, J=1.4 Hz, 2H), δ 1.49-1.45 (m, 2H), δ1.28 (s, J=9.0 Hz, 10H), δ 0.89 (t, J=4.8 Hz, 3H).

[0065] The two polymers PC-2 and PLC-2 obtained in Examples 1 and 2 were dissolved in chloroform and sprayed onto an ITO substrate to form films, with a solution concentration of 10 mg / mL.

[0066] Electrochromic performance testing of polymer films: Using an electrochemical workstation coupled with a UV-Vis spectrophotometer, cyclic voltammetry curves and UV-Vis absorption at different voltages, transmittance spectra at specific wavelengths, and response time and stability tests of the films under step voltage were measured in 0.1 M lithium perchlorate / acetonitrile solution for the two prepared films. The data processing results are shown below. Figure 1-10 As shown.

[0067] from Figure 1-2 It can be seen that the oxidation voltage of the two polymer films PC-F is 0.9 V, while that of PLC-2 is 1.3 V, indicating that PLC-2 exhibits better electrochemical behavior.

[0068] from Figure 3-6 It can be seen that both polymer films are colorless and transparent in the neutral state. The PC-F polymer film turns yellowish-green after oxidation at an oxidation voltage of 0.9 V. The PLC-2 polymer film turns green after oxidation at an oxidation voltage of 1.3 V.

[0069] Figure 7-10 The figures show the transmittance of the PLC-2 polymer film as a function of time under multiple potential steps from 0 to 1.3 V at 643 nm and 926 nm, respectively. Figure 7 and Figure 8 It can be seen that the optical contrast ratios of the thin film at 643 nm and 926 nm are 27.6% and 45.6%, respectively. From Figure 9 and Figure 10 It can be seen that the film retains 77.9% and 91.6% contrast after 100 cycles in the stability test at 643 nm and 926 nm (12 s step time).

[0070] Performance test results show that, compared with PC-2 film, the electrochemical behavior and electrochromic properties (optical contrast ΔT%, cycle stability) of the PLC-F film prepared in this invention are significantly improved. This result strongly demonstrates that structural modification of the carbazole unit can not only induce Friedel-Crafts hydroxyalkylation polycondensation but also construct electrochromic polymers with optimized performance, thus comprehensively improving their electrochromic properties.

[0071] In summary, the successful preparation of colorless-colored electrochromic polymers and their films based on the polycondensation reaction of carbazole derivatives and dimethylglyoxal (DMCO) demonstrates that Friedel-Crafts hydroxyalkylation reaction holds promise as a novel method for constructing neutral, colorless, highly transparent, non-conjugated electrochromic polymer materials. The ketone-containing poly-carbazole derivative electrochromic polymer films prepared by this invention possess characteristics such as high transparency in the neutral state, color in the oxidized state, and excellent solution processability, showing broad application prospects in fields such as energy-saving displays, static information display and dynamic information encryption, and military camouflage. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A ketone-type poly-carbazole derivative electrochromic polymer, characterized in that, Its structural formula is shown in Formula I: ， In Formula I, R is one of the alkane chain and alkoxycarbon chain of C6~C40; m is the number of benzene rings, m is 0 or 1; n is the degree of polymerization, n is 10~200; The number-average molecular weight M of the ketone-containing polycarbazole derivative electrochromic polymer n The range is 1000~5000 Da, and the polydispersity index D is 1.0~4.

0.

2. A method for preparing the ketone-containing polycarbazole derivative electrochromic polymer as described in claim 1, characterized in that: Includes the following steps: (1) Add the carbazolyl compound to a first organic solvent containing an inorganic base, stir to dissolve, and then add an alkane to carry out a nucleophilic substitution reaction to obtain the monomer shown in Formula II; ； (2) The monomer shown in Formula II is added to the second organic solvent, and then butanedione and Lewis acid catalyst are added to carry out the polymerization reaction to obtain the ketone-containing polycarbazole derivative electrochromic polymer shown in Formula I. In Formula II, R is one of the alkane chain and alkoxycarbon chain of C6~C40; m is the number of benzene rings, m is 0 or 1.

3. The preparation method according to claim 2, characterized in that: In step (1), the carbazolyl compound is carbazole or 3,6-diphenyl-9H-carbazole, the alkane is 1-bromoalkane or alkoxyalkane, the inorganic base is potassium hydroxide or sodium hydroxide, and the first organic solvent is one or both of dimethyl sulfoxide and tetrahydrofuran.

4. The preparation method according to claim 2, characterized in that: In step (1), the reaction temperature is 25~45 ℃ and the reaction time is 12~24 h.

5. The preparation method according to claim 2, characterized in that: In step (2), the Lewis acid catalyst is one or more of ferric chloride, aluminum chloride, sulfuric acid, p-toluenesulfonic acid and trifluoromethanesulfonic acid; the second organic solvent is one or two of dichloromethane and 1,2-dichloroethane.

6. The preparation method according to claim 1, characterized in that: In step (2), the molar ratio of the monomer shown in Formula II to dimethyl ethyl ketone is 1:(1~1.5); the molar ratio of the monomer shown in Formula II to Lewis acid catalyst is 1:(5~20).

7. The preparation method according to claim 1, characterized in that: The Lewis acid catalyst was added at -10 to 0 °C; the polymerization temperature was 25 to 45 °C; and the polymerization time was 36 to 72 h.

8. The application of the ketone-containing poly-carbazole derivative electrochromic polymer as described in claim 1 in the preparation of electrochromic polymer films.

9. The application according to claim 8, characterized in that: Electrochromic polymer films were obtained by solution processing of ketone-type poly-carbazole derivative electrochromic polymers.

10. An electrochromic polymer film, characterized in that: It is prepared from the ketone-containing poly-carbazole derivative electrochromic polymer as described in claim 1.

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