A benzofluorenone polymer and its preparation method and application

Abstract

The present invention discloses a benzofluorenone polymer and a preparation method and application thereof, belonging to the technical field of polymer materials. The structural formula of the benzofluorenone polymer provided by the present invention is as shown in any one of formulas (I) to (III): the polymer of the present invention has a D-A-D type structure based on 7H-benzo[c]fluorene-7-one as an acceptor, and since the keto group in the acceptor unit has a strong ability to accept electrons, the polymer has a lower bandwidth and a wider light absorption range, and therefore has a wider range of applications. The benzofluorenone polymer of the present invention has good electrochromic properties, such as fast response time, good optical transmittance and good stability, and is widely used in the preparation of electrochromic devices.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a benzofluorenone polymer and a preparation method and application thereof. Background Art

[0002] Electrochromism refers to the reversible change of the optical properties of a specific material under the action of an external voltage, which is manifested as a reversible change in color and transparency in appearance. Electrochromic materials can be used in lightweight and portable display devices such as monitors, and devices that use light transmittance such as smart windows, rearview mirrors, etc.

[0003] Inorganic electrochromic materials are usually transition metal oxides. These metals are often very expensive to produce due to their scarce resources. Compared with metal oxide materials, conductive polymers have many unique advantages as electrochromic materials: better flexibility; easy to achieve energy band and color transformation by changing the structure; low cost, etc. However, with the continuous deepening of research, conductive polymer electrochromic materials also have their own limitations, such as poor stability of some polymers and easy oxidation, which greatly limits the development of conductive polymer electrochromic materials.

[0004] Constructing a DA structure is an effective technical means to adjust the molecular energy band, which can reduce the oxidation potential of the polymer and have good stability. In recent years, the DAD-type polymers further developed on this basis have become an important class of electrochromic materials due to their special properties such as rich colors and easy bandwidth adjustment.

[0005] Therefore, exploring and developing DAD-type polymers with good electrochromic properties is a problem that needs to be solved today. Summary of the invention

[0006] In order to overcome the problems existing in the above-mentioned prior art, one of the purposes of the present invention is to provide a benzofluorenone polymer, which has the characteristics of low bandwidth, rich colors, fast response time, high coloring efficiency, etc.

[0007] The second object of the present invention is to provide a method for preparing the above-mentioned benzofluorenone polymer.

[0008] The third object of the present invention is to provide an application of the above-mentioned benzofluorenone polymer in the preparation of electrochromic materials. In order to achieve the above-mentioned object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides a benzofluorenone polymer, the structural formula of the polymer is shown in any one of formulas (I) to (III):

[0010]

[0011] In formulas (I) to (III), X1 to X3 are each independently O, S, Se or N-R'; Y1 to Y4 are each independently O or S; R1 to R4 and R' are each independently H or C1 to C 12 Alkyl; n1-n3 are each independently 3-200.

[0012] Preferably, in formulae (I) to (III), X1 to X3 are each independently S.

[0013] Preferably, in formulae (I) to (III), Y1 to Y4 are each independently O.

[0014] Preferably, in formulas (I) to (III), R1 to R4 and R' are each independently H or C1 to C5 alkyl; more preferably, R1 to R4 and R' are each independently H, methyl or ethyl.

[0015] Preferably, the structural formula of the polymer is as shown in any one of formulas (1) to (4):

[0016]

[0017]

[0018] In formulae (1) to (4), n4 to n7 are each independently 3 to 200.

[0019] The second aspect of the present invention provides a method for preparing the benzofluorenone polymer according to the first aspect of the present invention, comprising the following steps: electrochemically polymerizing the active precursors (I') to (III') of the benzofluorenone polymer to obtain the benzofluorenone polymers (I) to (III) respectively; the structural formula of the active precursor is as follows:

[0020]

[0021]

[0022] In formulae (I') to (III'), X1 to X3, Y1 to Y4, R1 to R3 and R' are as defined in the first aspect of the present invention.

[0023] Preferably, in the preparation method of the benzofluorenone polymer, the active precursor is prepared by a method comprising the following steps: cross-coupling the acceptor compound with the donor compound (I") to (III") in a catalyst and a solvent to obtain the active precursors (I') to (III'), respectively;

[0024] The receptor compound is:

[0025] The donor compound is:

[0026] The catalyst includes tetrakistriphenylphosphine palladium (Pd(PPh3)4), bistriphenylphosphine palladium dichloride (Pd(PPh3)2Cl2) or a combination thereof;

[0027] The solvent includes at least one of benzene, toluene or N,N-dimethylformamide (DMF).

[0028] Preferably, in the method for preparing the active precursor, the solvent includes toluene and N,N-dimethylformamide; more preferably, in the method for preparing the active precursor, the volume ratio of toluene and N,N-dimethylformamide in the solvent is (3-5):1.

[0029] Preferably, in the method for preparing the active precursor, the molar ratio of the acceptor compound to the donor compound is 1:(2-3).

[0030] Preferably, in the method for preparing the active precursor, the molar ratio of the acceptor compound to the catalyst is 1:(0.01-0.1); more preferably, it is 1:(0.03-0.05).

[0031] Preferably, in the method for preparing the active precursor, the dosage ratio of the acceptor compound to the solvent is 1 mmol: (50-200) mL.

[0032] Preferably, in the method for preparing the active precursor, the temperature of the cross-coupling reaction is 100 to 140°C; more preferably, 110 to 130°C.

[0033] Preferably, in the method for preparing the active precursor, the cross-coupling reaction time is 24 to 72 hours; more preferably, it is 36 to 60 hours.

[0034] Preferably, in the method for preparing the active precursor, a purification step is further included after the cross-coupling reaction; further preferably, the purification is performed by chromatographic separation and purification.

[0035] Preferably, the chromatographic column used for the chromatographic separation and purification is selected from a silica gel column.

[0036] Preferably, the eluent used for the chromatographic separation and purification comprises dichloromethane (DCM) and petroleum ether (PE); further preferably, the volume ratio of dichloromethane to petroleum ether is 1:(1-3).

[0037] In the preparation method of the active precursor of the present invention, the cross-coupling reaction is a Stille / Suzuki palladium-catalyzed cross-coupling reaction, through which a DAD-type active precursor containing 7H-benzo[c]fluorene-7-one, i.e., an active precursor represented by formula (I') to (III'), can be prepared.

[0038] Preferably, in the method for preparing the active precursor, the cross-coupling reaction is carried out in an inert gas atmosphere. In a specific embodiment of the present invention, the inert gas is selected from nitrogen.

[0039] Preferably, in the preparation method of the benzofluorenone polymer, the electrochemical polymerization reaction is specifically: using a solution containing the active precursor as an electrolyte solution, electrodeposition is performed in a three-electrode system consisting of a reference electrode, a counter electrode and a working electrode to obtain the polymer on the working electrode.

[0040] Preferably, in the electrochemical polymerization reaction, the concentration of the active precursor in the electrolyte solution is 0.001 to 0.01 mmol·L -1 .

[0041] Preferably, in the electrochemical polymerization reaction, the solvent of the electrolyte solution includes at least one of dichloromethane (CH2Cl2), chloroform (CHCl3) or acetonitrile (MeCN).

[0042] Preferably, in the electrochemical polymerization reaction, the electrolyte solution further contains a supporting electrolyte.

[0043] Preferably, in the electrolyte solution, the supporting electrolyte includes at least one of tetrabutylammonium hexafluorophosphate (PF6), tetrabutylammonium tetrafluoroborate (BF4) or lithium perchlorate.

[0044] Preferably, the concentration of the supporting electrolyte in the electrolyte solution is 0.01 to 0.2 mmol·L -1 .

[0045] Preferably, in the electrochemical polymerization reaction, the reference electrode is selected from an Ag / AgCl electrode; the counter electrode is selected from a platinum wire electrode; and the working electrode is selected from a Pt / ITO conductive glass electrode.

[0046] Preferably, in the electrochemical polymerization reaction, the electrodeposition method is a constant potential method; further preferably, the constant potential method is a constant current method or a cyclic voltammetry method.

[0047] Preferably, the electrochemical polymerization reaction is carried out under a protective gas atmosphere. In a specific embodiment of the present invention, the protective gas is selected from argon.

[0048] The third aspect of the present invention provides a use of the benzofluorenone polymer described in the first aspect of the present invention in preparing an electrochromic device.

[0049] Preferably, the electrochromic device includes one or both of a display device and a light-transmitting device; further preferably, the electrochromic device includes at least one of a display, electrochromic glass, a smart window or a rearview mirror.

[0050] The beneficial effects of the present invention are:

[0051] The polymer of the present invention has a DAD-type structure based on 7H-benzo[c]fluorene-7-one as an acceptor. Since the keto group in the acceptor unit has a strong electron-accepting ability, the polymer has a lower bandwidth and a wider light absorption range, and thus has a wider application range. The benzofluorene-one polymer of the present invention has good electrochromic properties, such as fast response time, good optical transmittance and good stability, and has a wide range of applications in the preparation of electrochromic devices.

[0052] Specifically, compared with the prior art, the present invention has the following advantages:

[0053] 1. The polymer of the present invention uses 7H-benzo[c]fluorene-7-one as the electron acceptor (A) unit, and furanyl, thienyl, selenophenyl, pyrrolyl, pyrrolyl derivatives or thienyl derivatives as the terminal donor (D) unit. By changing the structure of the donor unit, the absorption spectrum of the polymer can be adjusted, thereby changing the color of the polymer; and the acceptor unit has a strong electron-withdrawing ability due to the presence of the keto group; at the same time, the addition of the benzene ring makes the fused ring structure rigidly coplanar in the molecule, which is conducive to enhancing the charge mobility, so that this type of polymer has a lower band gap, a wider redox peak, good optical contrast, fast response time, high coloring efficiency, good stability and other characteristics as an electrochromic material.

[0054] 2. Under the action of an applied voltage, the benzofluorenone polymer of the present invention can be observed to have a stable and reversible color change from gray-blue to gray-green or brown-yellow to yellow-green in appearance, and has good electrochromic properties, including fast response time, high coloring efficiency and good optical transmittance. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The NMR of BZFO-EDOT in Example 1 is 1 H NMR spectrum.

[0056] Figure 2 The polymer P (BZFO-EDOT) of Example 1 was dissolved in MeCN-Bu4NPF6 (0.1 mol·L-1 ) system.

[0057] Figure 3 The transmittance-time curves of the polymer P (BZFO-EDOT) of Example 1 at 433 nm and 1100 nm.

[0058] Figure 4 The polymer P(BZFO-Th) of Example 2 was prepared in MeCN-Bu4NPF6 (0.1 mol·L -1 ) system.

[0059] Figure 5 The transmittance-time curves of the polymer P(BZFO-Th) of Example 2 at 417 nm, 750 nm and 1100 nm. DETAILED DESCRIPTION

[0060] The content of the present invention is further described in detail below through specific examples. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0061] It should be noted that, in the embodiments of the present invention, the coloring efficiency refers to the ratio of the change in absorbance of the electrochromic material at a given wavelength to the total electron injection or extraction.

[0062] For an electrochromic material, coloring efficiency is an important parameter for evaluating material performance. Coloring efficiency The study of the coloring efficiency of conductive polymers should be combined with the electrochemical and spectral changes of the electrochromic film, among which Q d It refers to the amount of charge that moves in / out per unit area, and its calculation formula is as follows:

[0063] CE=ΔOD / Q d ;

[0064] The change in optical contrast (ΔOD) is the change in optical contrast at a specific wavelength λ. max Under the condition of electrochemical oxidation and reduction, the corresponding transmittance value of the polymer membrane (the transmittance of the polymer membrane doped state T ox and the transmittance T in the neutral state red The ratio of is calculated by the following formula:

[0065] ΔOD=log(T ox / T red ).

[0066] Example 1

[0067] Electrochemical synthesis of polymer P(BZFO-EDOT):

[0068] (1) Synthesis of BZFO-EDOT active precursor:

[0069]

[0070] Under nitrogen atmosphere, 5,9-dibromo-7H-benzo[c]fluoren-7-one (1.288mmol, 0.5g), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (3.22mmol, 1.391g), and catalyst Pd(PPh3)2Cl2 (0.051mmol, 0.036g) were placed in a 250mL single-necked flask, and DMF (20mL) and dry toluene (80mL) were added and stirred evenly, and heated to 120℃ for condensation and reflux reaction for 48 hours. After the system was cooled, the product was poured into saturated brine, extracted with dichloromethane 4 to 5 times, and then a small amount of water was added to wash the organic layer, and then the solvent was removed by reduced pressure distillation and rotary evaporation, and separated by silica gel chromatography column, the eluent was (DCM:PE=1:2), and the light purple powder product was purified with a yield of 79.14%. NMR of the product 1 H NMR spectrum Figure 1 As shown, the specific NMR data are: 1 H NMR (400MHz, CDCl3) δ8.52-8.35(m,1H),8.09(dd,J=16.9,9.0Hz,2H),8.04-7.95(m,1H),7.93-7.84( m,1H),7.84-7.72(m,2H),7.61(dd,J=18.4,7.3Hz,3H),6.51(s,1H),6.35(s,1H),4.41-4.10(m,8H).

[0071] (2) Synthesis of polymer P(BZFO-EDOT):

[0072]

[0073] Under the protection of argon atmosphere, electrochemical polymerization was carried out in a three-electrode system, with a silver / silver chloride electrode as a reference electrode, a platinum wire as a counter electrode, and a glassy carbon as a working electrode; 10 mL of dichloromethane was used as the electrolyte, BZFO-EDOT (0.0051 g, 0.0001 mmol) was used as the polymerization monomer, and 10 mL of a mixed solution of acetonitrile and tetrabutylammonium hexafluorophosphate (0.3874 g, 0.001 mmol) was used as the supporting electrolyte; cyclic voltammetry was used for polymerization, with a polymerization potential of 1.15 V, a scan rate of 100 mV / s, and the number of polymerization cycles set to 10 cycles. The polymer film obtained by electrodeposition was soaked and rinsed with acetonitrile to remove the electrolyte solution and precursor in the polymer to obtain a polymer P (BZFO-EDOT).

[0074] Electrochromic performance research:

[0075] (1) Test polymer P(BZFO-EDOT) in MeCN-Bu4NPF6 (0.1 mol·L -1 ) system, such as Figure 2 As shown in the figure, combined with the color change of the polymer material observed with the naked eye, it can be seen that with the increase of the potential, the color of the polymer material changes from gray-blue to gray-green (gray-blue in the completely dedoped state). This is because the neutral polymer material has an absorption peak in the purple light region and the red light region respectively, and the color of the neutral polymer material appears gray-green; after the polymer material is oxidized, the absorption peak in the purple light region gradually weakens, and the absorption peak in the red light region gradually weakens, and finally disappears completely; therefore, the polymer material appears gray-blue in the completely dedoped state, and the doped polymer material appears gray-green.

[0076] (2) Test the transmittance-time curve of polymer P(BZFO-EDOT) at 433nm and 1100nm. The response time and coloring efficiency calculated from the time-transmittance curve are shown in Table 1, where T red is the transmittance of the polymer film in neutral state, T ox is the transmittance of the polymer film in the doped state, ΔT = T red -T ox As can be seen from Table 1, the polymer P(BZFO-EDOT) has a fast response time and high coloring efficiency.

[0077] Table 1 Electrochromic parameters of P(BZFO-EDOT)

[0078]

[0079]

[0080] The optical transmittance of P(BZFO-EDOT) was studied by timed absorption method at wavelengths of 433nm and 1100nm. During the experiment, the time interval of the potential step change was 5s. Figure 3 As shown. At both wavelengths, the polymer material exhibits a certain optical contrast and good optical stability; in addition, the optical transmittance has a great influence on the color change of the polymer material, and the polymer material can be transformed from gray-blue in a completely dedoped state to gray-green in a doped state.

[0081] Example 2

[0082] Electrochemical synthesis of polymer P(BZFO-Th):

[0083] (1) Synthesis of BZFO-Th active precursor:

[0084]

[0085] Under nitrogen atmosphere, 5,9-dibromo-7H-benzo[c]fluorene-7-one (1.288mmol, 0.5g), 2-tinbutylthiophene (3.22mmol, 1.201g), and catalyst Pd(PPh3)2Cl2 (0.051mmol, 0.036g) were placed in a 250mL single-necked flask, and DMF (20mL) and dry toluene (80mL) were added and stirred evenly, and heated to 120°C for condensation and reflux reaction for 48 hours. After the system was cooled, the product was poured into saturated brine, extracted with dichloromethane 4 to 5 times, and then a small amount of water was added to wash the organic layer, and then the solvent was removed by reduced pressure distillation and rotary evaporation, and separated by silica gel chromatography column, the eluent was (DCM: PE = 1: 2), and the orange-red solid was purified with a yield of 58.70%.

[0086] (2) Synthesis of polymer P(BZFO-Th):

[0087]

[0088] Under argon atmosphere, electrochemical polymerization was carried out in a three-electrode system, with a silver / silver chloride electrode as a reference electrode, a platinum wire as a counter electrode, and a glassy carbon as a working electrode; 10 mL of dichloromethane was used as an electrolyte, BZFO-Th (0.0039 g, 0.0001 mmol) was used as a polymerization monomer, and 10 mL of a mixed solution of acetonitrile and tetrabutylammonium hexafluorophosphate (0.3874 g, 0.001 mmol) was used as a supporting electrolyte; the polymerization was carried out by a constant potential method, the polymerization potential was 1.35 V, the scanning rate was 100 mV / s, the number of polymerization cycles was set to 10 cycles, and the polymer film obtained by electrodeposition was soaked and rinsed with acetonitrile to remove the electrolyte solution and precursor in the polymer to obtain a polymer P (BZFO-Th).

[0089] Electrochromic performance research:

[0090] (1) Test polymer P(BZFO-Th) in MeCN-Bu4NPF6 (0.1 mol·L -1 ) system, such as Figure 4 As shown in the figure, combined with the color change of the polymer material observed with the naked eye, it can be seen that with the increase of the potential, the color of the polymer material changes from brown-yellow to yellow-green (brown-yellow in the completely dedoped state). This is because the neutral polymer material has an absorption peak in the purple light region and the red light region respectively, and the color of the neutral polymer material appears yellow-green; after the polymer material is oxidized, the absorption peak in the purple light region gradually weakens, and the absorption peak in the red light region gradually weakens, and finally disappears completely; therefore, the polymer material in the completely dedoped state appears brown-yellow, and the doped polymer material appears yellow-green.

[0091] (2) The transmittance-time curves of polymer P(BZFO-Th) at 417nm, 750nm and 1100nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 2. As can be seen from Table 2, polymer P(BZFO-Th) has a fast response time and high coloring efficiency.

[0092] Table 2 Electrochromic parameters of polymer P(BZFO-Th)

[0093]

[0094] The optical transmittance of P(BZFO-Th) was studied by timed absorption method at wavelengths of 417nm, 750nm and 1100nm. During the experiment, the time interval of the potential step change was 5s. Figure 5 As shown. At three wavelengths, the polymer material exhibits a certain optical contrast and good optical stability; in addition, the optical transmittance has a great influence on the color change of the polymer material, and the polymer material can be transformed from brown-yellow in a completely dedoped state to yellow-green in a doped state.

[0095] Example 3

[0096] Electrochemical synthesis of polymer P(BZFO-MeTh):

[0097] (1) Synthesis of BZFO-MeTh active precursor:

[0098]

[0099] Under nitrogen atmosphere, 5,9-dibromo-7H-benzo[c]fluorene-7-one (1.288mmol, 0.50g), 2-tinbutyl-3-methylthiophene (3.22mmol, 1.249g), and catalyst Pd(PPh3)2Cl2 (0.051mmol, 0.036g) were placed in a 250mL single-necked flask, and DMF (20mL) and dry toluene (80mL) were added and stirred evenly, and heated to 120°C for condensation and reflux reaction for 48 hours. After the system was cooled, the product was poured into saturated brine, extracted with dichloromethane 4 to 5 times, and then a small amount of water was added to wash the organic layer, and then the solvent was removed by reduced pressure distillation and rotary evaporation, and separated by silica gel chromatography column, the eluent was (DCM: PE = 1: 1), and purified to obtain a yellow solid with a yield of 48.70%.

[0100] (2) Synthesis of polymer P(BZFO-MeTh):

[0101]

[0102] Under argon atmosphere, electrochemical polymerization was carried out in a three-electrode system, with a silver / silver chloride electrode as a reference electrode, a platinum wire as a counter electrode, and a glassy carbon as a working electrode; 10 mL of dichloromethane was used as an electrolyte, BZFO-MeTh (0.0042 g, 0.0001 mmol) was used as a polymerization monomer, and 10 mL of a mixed solution of acetonitrile and tetrabutylammonium hexafluorophosphate (0.3874 g, 0.001 mmol) was used as a supporting electrolyte; the polymerization was carried out by a constant potential method, the polymerization potential was 1.2 V, the scanning rate was 100 mV / s, the number of polymerization cycles was set to 10 cycles, and the polymer film obtained by electrodeposition was soaked and rinsed with acetonitrile to remove the electrolyte solution and precursor in the polymer to obtain a polymer P (BZFO-MeTh).

[0103] Example 4

[0104] Electrochemical synthesis of polymer P(BZFO-ProEDOT):

[0105] (1) Synthesis of BZFO-ProEDOT active precursor:

[0106]

[0107] Under nitrogen atmosphere, 5,9-dibromo-7H-benzo[c]fluorene-7-one (1.288mmol, 0.50g), 2-tinbutyl-3,3-diethyl-3,4-propylenedioxythiophene 2-tinbutyl-3-methylthiophene (3.22mmol, 1.630g), and catalyst Pd(PPh3)2Cl2 (0.051mmol, 0.036g) were placed in a 250mL single-necked flask, DMF (20mL) and dry toluene (80mL) were added and stirred evenly, and heated to 120℃ for condensation and reflux reaction for 48 hours. After the system was cooled, the product was poured into saturated brine, extracted with dichloromethane 4 to 5 times, and then a small amount of water was added to wash the organic layer, and then the solvent was removed by reduced pressure distillation and rotary evaporation, and separated by silica gel chromatography column, the eluent was (DCM: PE = 1: 2), and the red solid was purified with a yield of 45.0%.

[0108] (2) Synthesis of polymer P(BZFO-ProEDOT):

[0109]

[0110] Under argon atmosphere, electrochemical polymerization was carried out in a three-electrode system, with a silver / silver chloride electrode as a reference electrode, a platinum wire as a counter electrode, and a glassy carbon as a working electrode; 10 mL of dichloromethane was used as the electrolyte, BZFO-ProEDOT (0.0065 g, 0.0001 mmol) was used as the polymerization monomer, and 10 mL of a mixed solution of acetonitrile and tetrabutylammonium hexafluorophosphate (0.3874 g, 0.001 mmol) was used as the supporting electrolyte; the polymerization was carried out by a constant potential method, the polymerization potential was 1.05 V, the scanning rate was 100 mV / s, the number of polymerization cycles was set to 10 cycles, and the polymer film obtained by electrodeposition was soaked and rinsed with acetonitrile to remove the electrolyte solution and precursor in the polymer to obtain a polymer P (BZFO-ProEDOT).

[0111] From the above examples, it can be seen that the polymer of the present invention uses 7H-benzo[c]fluorene-7-one as the electron acceptor (A) unit, and furanyl, thienyl, selenophenyl, pyrrolyl, pyrrolyl derivatives or thienyl derivatives as the terminal donor (D) unit. By changing the structure of the donor unit, the absorption spectrum of the polymer can be adjusted, thereby changing the color of the polymer; and the acceptor unit has a strong electron-withdrawing ability due to the presence of the keto group; at the same time, the addition of the benzene ring makes the fused ring structure rigidly coplanar in the molecule, which is conducive to enhancing the charge mobility, so that this type of polymer has a lower band gap, a wider redox peak, good optical contrast, fast response time, high coloring efficiency, good stability and other characteristics as an electrochromic material.

[0112] The benzofluorenone polymer of the present invention can be observed to have a stable and reversible color change from gray-blue to gray-green or brown-yellow to yellow-green under the action of an applied voltage, and has good electrochromic properties, including fast response time, high coloring efficiency and good optical transmittance.

[0113] In summary, the polymer of the present invention has a DAD-type structure based on 7H-benzo[c]fluorene-7-one as an acceptor. Since the keto group in the acceptor unit has a strong ability to accept electrons, the polymer has a lower bandwidth and a wider light absorption range, and thus has a wider range of applications. The benzofluorene-one polymer of the present invention has good electrochromic properties, such as fast response time, good optical transmittance and good stability, and has a wide range of applications in the preparation of electrochromic devices.

Claims

1. A benzofluorenone polymer, characterized in that: The structural formula of the polymer is shown in any one of formulas (I) to (III): In formulas (I) to (III), X1 to X3 are each independently O, S, Se or N-R'; Y1 to Y4 are each independently O or S; R1 to R4 and R' are each independently H or C1 to C 12 Alkyl; n1-n3 are each independently 3-200.

2. The benzofluorenone polymer according to claim 1, characterized in that: In formulas (I) to (III), X1 to X3 are each independently S; and / or, Y1 to Y4 are each independently O; And / or, R1-R4 and R' are each independently H or C1-C5 alkyl.

3. The benzofluorenone polymer according to claim 1, characterized in that: The structural formula of the polymer is shown in any one of formulas (1) to (4): In formulae (1) to (4), n4 to n7 are each independently 3 to 200.

4. The method for preparing a benzofluorenone polymer according to any one of claims 1 to 3, characterized in that: The following steps are involved: The active precursors (I') to (III') of the benzofluorenone polymers are subjected to electrochemical polymerization reaction to obtain the benzofluorenone polymers (I) to (III) respectively; the structural formula of the active precursors is as follows: In formulae (I') to (III'), X1 to X3, Y1 to Y4, R1 to R3 and R' are as defined in any one of claims 1 to 3.

5. The preparation method according to claim 4, characterized in that: The active precursor is prepared by a method comprising the following steps: cross-coupling reaction of an acceptor compound with a donor compound (I") to (III") in a catalyst and a solvent to obtain the active precursors (I') to (III') respectively; The receptor compound is: The donor compound is: (III”); The catalyst includes tetrakistriphenylphosphine palladium, bistriphenylphosphine palladium dichloride or a combination thereof; The solvent includes at least one of benzene, toluene or N,N-dimethylformamide.

6. The preparation method according to claim 4, characterized in that: The electrochemical polymerization reaction is specifically as follows: using a solution containing the active precursor as an electrolyte solution, performing electrodeposition in a three-electrode system consisting of a reference electrode, a counter electrode and a working electrode, and obtaining the polymer on the working electrode.

7. The preparation method according to claim 6, characterized in that: The concentration of the active precursor in the electrolyte solution is 0.001 to 0.01 mmol·L -1 .

8. The preparation method according to claim 6, characterized in that: The solvent of the electrolyte solution includes at least one of dichloromethane, chloroform or acetonitrile; And / or, the electrolyte solution further contains a supporting electrolyte; preferably, the supporting electrolyte includes at least one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate or lithium perchlorate.

9. The preparation method according to claim 6, characterized in that: The reference electrode is selected from Ag / AgCl electrode; the counter electrode is selected from platinum wire electrode; and the working electrode is selected from Pt / ITO conductive glass electrode.

10. Use of the benzofluorenone polymer according to any one of claims 1 to 3 in preparing an electrochromic device.

Images