A methyl benzoate-alkylthiophene copolymer and its preparation method

Abstract

This invention discloses an ortho-methyl benzoate-alkylthiophene copolymer and its preparation method, belonging to the technical field of thiophene copolymers. The structural formula of the copolymer is shown, wherein R is selected from alkyl groups with 4 to 12 carbon atoms. This ortho-methyl benzoate-alkylthiophene copolymer has an electron donor-electron acceptor (D-A) structure, and methyl benzoate is connected to alkylthiophene through ortho and meta positions. Its steric hindrance, to a certain extent, disrupts the perfect coplanarity of the molecular chain. This moderate disorder helps to alleviate the oxidation and loss of dopants and improve its stability.

Description

Technical Field

[0001] This invention belongs to the field of thiophene copolymer technology, and particularly relates to a methyl orthobenzoate-alkylthiophene copolymer and its preparation method. Background Technology

[0002] Since their discovery, conductive polymers have been widely studied in fields such as organic optoelectronic devices, thermoelectric conversion, electromagnetic shielding, flexible sensors, and antistatic coatings due to their unique electrochemical activity and tunable conductivity. Among them, polythiophene and its derivatives are considered one of the most promising conductive polymer materials due to their excellent film-forming properties, good environmental tolerance, and structural modifiability. Through chemical or electrochemical doping, polythiophene can transform from an insulating state to a highly conductive state, and the polarons or bipolarons formed after doping are the microscopic basis for its conductivity.

[0003] However, doped polythiophene faces the problem of poor air stability in practical applications. In oxygen- and water-containing environments, oxygen and water molecules in the air interact with the doped polymer backbone, triggering a dedoping reaction: oxygen molecules, acting as electron acceptors, neutralize charge carriers on the polymer chain, leading to a significant decrease in conductivity; water molecules, on the other hand, may promote the insertion / extraction of dopants. This instability severely limits the application of doped polythiophene in devices that require long-term exposure to the atmospheric environment.

[0004] Therefore, how to develop a thiophene copolymer to improve its air stability in the doped state is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a methyl benzoate-alkylthiophene copolymer and its preparation method. The methyl benzoate-alkylthiophene copolymer has an electron donor-electron acceptor (DA) structure, and methyl benzoate is connected to alkylthiophene through ortho and meta positions. Its steric hindrance disrupts the perfect coplanarity of the molecular chain to a certain extent. This moderate disorder helps to alleviate the oxidation and loss of dopants and improve its stability.

[0006] The purpose of this invention is to provide a methyl benzoate-alkylthiophene copolymer, the structural formula of which is shown in formula (I):

[0007] Equation (Ⅰ);

[0008] Wherein, R is selected from one of the alkyl groups having 4 to 12 carbon atoms.

[0009] In some embodiments of the present invention, the alkyl group is a straight-chain alkyl group having 6 to 8 carbon atoms, such as n-hexyl or n-octyl.

[0010] In some embodiments of the present invention, the copolymer has a number-average molecular weight of 3-35 kDa and a molecular weight distribution of 1.05-2.5. Preferably, the number-average molecular weight is 3-10 kDa and the molecular weight distribution is 1.05-1.4.

[0011] In some embodiments of the present invention, the raw materials for preparing the copolymer include methyl 2,5-dibromobenzoate and alkyl-substituted thiophene. .

[0012] Another object of the present invention is to provide a method for preparing the above-mentioned methyl orthobenzoate-alkylthiophene copolymer, which includes the following steps:

[0013] In the presence of catalysts and auxiliaries, methyl 2,5-dibromobenzoate and alkyl-substituted thiophene A polymerization reaction occurs to obtain the methyl benzoate-alkyl thiophene copolymer.

[0014] In some embodiments of the present invention, the molar ratio of the methyl 2,5-dibromobenzoate to the alkyl-substituted thiophene is 1:0.9~1.1.

[0015] In some embodiments of the present invention, the catalyst comprises a palladium-based catalyst. Preferably, the palladium-based catalyst has the structural formula shown in formula (II):

[0016] Equation (II); where R 1 R 2 It can be hydrogen, methyl, ethyl, or isopropyl independently, and R 1 R 2 They are not both hydrogen.

[0017] In some embodiments of the present invention, the amount of the catalyst is 0.5 to 4 mol% of the sum of the amounts of the methyl 2,5-dibromobenzoate and the alkyl-substituted thiophene.

[0018] In some embodiments of the present invention, the additives include inorganic bases, organic acids, and solvents.

[0019] In some embodiments of the present invention, the inorganic base is selected from potassium carbonate.

[0020] In some embodiments of the present invention, the amount of the inorganic base is 1.2 to 2 times the sum of the amounts of the methyl 2,5-dibromobenzoate and the alkyl-substituted thiophene.

[0021] In some embodiments of the present invention, the organic acid is selected from pivalic acid.

[0022] In some embodiments of the present invention, the amount of organic acid used is 10 to 50 mol% of the sum of the amounts of the methyl 2,5-dibromobenzoate and the alkyl-substituted thiophene.

[0023] In some embodiments of the present invention, the solvent is selected from at least one of toluene and N,N-dimethylacetamide.

[0024] In some embodiments of the present invention, the polymerization reaction is carried out at a temperature of 80~120°C.

[0025] In some embodiments of the present invention, the polymerization reaction takes 18 to 30 hours.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The ortho-methyl benzoate-alkylthiophene copolymer of the present invention has an electron donor-electron acceptor (DA) structure, and methyl benzoate is connected to alkylthiophene through ortho and meta positions. Its steric hindrance disrupts the perfect coplanarity of the molecular chain to a certain extent. This moderate disorder helps to alleviate the oxidation and loss of dopants, thereby enabling the doped state of the copolymer to achieve good air stability. After being treated with hot air for 7 days, it can maintain a conductivity of more than 75% or even more than 85%. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate the present application and form part of the specification. Together with the embodiments of the present application, they serve to explain the present application but do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 The methyl benzoate-alkylthiophene copolymer obtained in Example 2 of this invention 1 H NMR spectrum. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0031] All raw materials used in this invention, unless otherwise specified, are obtained commercially.

[0032] The structure of the palladium catalyst C1 of the present invention is shown below: ;

[0033] The structure of the palladium catalyst C2 of the present invention is shown below: ;

[0034] The structure of the palladium catalyst C3 of the present invention is shown below: .

[0035] Example 1

[0036] This embodiment provides a methyl orthobenzoate-alkylthiophene copolymer, the preparation method of which includes the following steps:

[0037] Weigh 0.25 mmol of 3-n-butylthiophene, 0.25 mmol of methyl 2,5-dibromobenzoate, 0.15 mmol of tervastatinic acid, 0.75 mmol of anhydrous potassium carbonate, and 0.01 mmol of palladium catalyst C1, and transfer them sequentially to a reactor. Then add 4 mL of N,N-dimethylacetamide. The reaction system is purged multiple times with N2 to remove air. The reaction system is heated to 100 °C and reacted at this temperature for 24 h. After the reaction is complete, the reaction solution is poured into a large amount of methanol to settle, filtered, and the filter cake is dissolved in N,N-dimethylacetamide and then precipitated again with a large amount of methanol. This process is repeated twice. The filter cake is crushed, added to a beaker containing water, stirred for 30 min, filtered, and the filter cake is washed with methanol and dried to obtain a yellow solid powder, which is the methyl benzoate-alkylthiophene copolymer (yield 43%), and its structure is shown below:

[0038] .

[0039] Example 2

[0040] This embodiment provides a methyl orthobenzoate-alkylthiophene copolymer, the preparation method of which includes the following steps:

[0041] Weigh 0.25 mmol of 3-n-hexylthiophene, 0.25 mmol of methyl 2,5-dibromobenzoate, 0.15 mmol of tervastatinic acid, 0.75 mmol of anhydrous potassium carbonate, and 0.01 mmol of palladium catalyst C3, and transfer them sequentially to a reactor. Then add 4 mL of N,N-dimethylacetamide. The reaction system is purged multiple times with N2 to remove air. The reaction system is heated to 100 °C and reacted at this temperature for 24 h. After the reaction is complete, the reaction solution is poured into a large amount of methanol to settle, filtered, and the filter cake is dissolved in N,N-dimethylacetamide and then precipitated again with a large amount of methanol. This process is repeated twice. The filter cake is crushed, added to a beaker containing water, stirred for 30 min, filtered, and the filter cake is washed with methanol and dried to obtain a yellow solid powder, which is the methyl benzoate-alkylthiophene copolymer (yield 41%), and its structure is shown below:

[0042] .

[0043] In addition, the ortho-methyl benzoate-alkylthiophene copolymer 1 The H NMR analysis results are as follows: Figure 1 As shown, by Figure 1 It can be seen that the integral area of ​​the benzene ring H at a chemical shift of 7.94~8.20 ppm, the integral area of ​​the thiophene H at a chemical shift of 7.30 ppm, the integral area of ​​the methyl H at a chemical shift of 3.89~3.92 ppm, and the integral area of ​​the methylene H connected to the thiophene are approximately 3:1:3:2. This indicates that methyl benzoate and alkyl-substituted thiophene have been successfully copolymerized. That is, Example 2 of the present invention successfully prepared an ortho-methyl benzoate-alkyl thiophene copolymer.

[0044] Example 3

[0045] This embodiment provides a methyl orthobenzoate-alkylthiophene copolymer, the preparation method of which includes the following steps:

[0046] Weigh 0.25 mmol of 3-n-octylthiophene, 0.25 mmol of methyl 2,5-dibromobenzoate, 0.15 mmol of tervastatinic acid, 0.75 mmol of anhydrous potassium carbonate, and 0.01 mmol of palladium catalyst C2, and transfer them sequentially to a reactor. Then add 2 mL of N,N-dimethylacetamide and 2 mL of toluene. The reaction system is purged multiple times with N2 to remove air. The reaction system is heated to 100 °C and reacted at this temperature for 24 h. After the reaction is complete, the reaction solution is poured into a large amount of methanol to settle, filtered, and the filter cake is dissolved in N,N-dimethylacetamide and then precipitated again with a large amount of methanol. This process is repeated twice. The filter cake is crushed, added to a beaker containing water, stirred for 30 min, filtered, and the filter cake is washed with methanol and dried to obtain a yellow solid powder, which is the methyl benzoate-alkylthiophene copolymer (yield 42%), and its structure is shown below:

[0047] .

[0048] Example 4

[0049] This embodiment provides a methyl orthobenzoate-alkylthiophene copolymer, the preparation method of which includes the following steps:

[0050] Weigh 0.25 mmol of 3-dodecylthiophene, 0.25 mmol of methyl 2,5-dibromobenzoate, 0.15 mmol of tervastatinic acid, 0.75 mmol of anhydrous potassium carbonate, and 0.01 mmol of palladium catalyst C2, and transfer them sequentially to a reactor. Then add 4 mL of N,N-dimethylacetamide. The reaction system is purged multiple times with N2 to remove air. The reaction system is heated to 100 °C and reacted at this temperature for 24 h. After the reaction is complete, the reaction solution is poured into a large amount of methanol to settle, filtered, and the filter cake is dissolved in N,N-dimethylacetamide and then precipitated again with a large amount of methanol. This process is repeated twice. The filter cake is crushed, added to a beaker containing water, stirred for 30 min, filtered, and the filter cake is washed with methanol and dried to obtain a yellow solid powder, which is the methyl benzoate-alkylthiophene copolymer (yield 35%), and its structure is shown below:

[0051] .

[0052] Example 5

[0053] This embodiment provides a methyl orthobenzoate-alkylthiophene copolymer, the preparation method of which includes the following steps:

[0054] Weigh 0.25 mmol of 3-(2-ethylhexyl)thiophene, 0.25 mmol of methyl 2,5-dibromobenzoate, 0.15 mmol of tervastatinic acid, 0.75 mmol of anhydrous potassium carbonate, and 0.01 mmol of palladium catalyst C2, and transfer them sequentially to a reactor. Then add 4 mL of N,N-dimethylacetamide. The reaction system is purged multiple times with N2 to remove air. The reaction system is heated to 100 °C and reacted at this temperature for 24 h. After the reaction is complete, the reaction solution is poured into a large amount of methanol to settle, filtered, and the filter cake is dissolved in N,N-dimethylacetamide and then precipitated again with a large amount of methanol. This process is repeated twice. The filter cake is crushed, added to a beaker containing water, stirred for 30 min, filtered, and the filter cake is washed with methanol and dried to obtain a yellow solid powder, which is the methyl benzoate-alkylthiophene copolymer (yield 51%), and its structure is shown below:

[0055] .

[0056] Example 6

[0057] This embodiment provides a methyl orthobenzoate-alkylthiophene copolymer, the preparation method of which includes the following steps:

[0058] Weigh 0.25 mmol of 3-n-hexylthiophene, 0.25 mmol of methyl 2,5-dibromobenzoate, 0.15 mmol of tertivalic acid, 0.75 mmol of anhydrous potassium carbonate, and 0.01 mmol of palladium catalyst C2, and transfer them sequentially to a reactor. Then add 4 mL of N,N-dimethylacetamide. The reaction system is purged multiple times with N2 to remove air. The reaction system is heated to 100°C and reacted at this temperature for 24 h. Then, the reaction system is heated to 110°C and reacted at this temperature for 12 h. After the reaction is completed, the reaction solution is poured into a large amount of methanol to settle, filtered, and the filter cake is dissolved in N,N-dimethylacetamide and then precipitated again with a large amount of methanol. This process is repeated twice. The filter cake is crushed, added to a beaker containing water, stirred for 30 min, filtered, and the filter cake is washed with methanol and dried to obtain a yellow solid powder, which is the methyl benzoate-alkylthiophene copolymer (yield 43%), and its structure is as in Example 2.

[0059] Comparative Example 1

[0060] The copolymer in this comparative example is the ester-based thiophene-hexylthiophene copolymer obtained in Example 5 of CN119019651A, and its structure is shown below:

[0061] Among them, x=16mmol%, y=84mmol%, number-average molecular weight Mn is 7.4kDa, and PDI is 2.0.

[0062] The performance tests are as follows, and the results are shown in Table 1:

[0063] 1. GPC analysis was performed on the methyl orthobenzoate-alkylthiophene copolymers obtained in Examples 1-6 above to determine their molecular weight and molecular weight distribution;

[0064] 2. The methyl benzoate-alkylthiophene copolymers obtained in Examples 1-6 and the ester-thiophene-hexylthiophene copolymer of Comparative Example 1 were respectively prepared into 0.2 mg / mL solutions with chlorobenzene and coated onto a 20 mm × 20 mm glass substrate by spin coating. After the solvent evaporated naturally, the copolymer films were annealed to form the corresponding copolymer films. The copolymer films were immersed in a 100 mM FeCl3 CH3CN solution for 2 min, removed and immersed in pure CH3CN for 20 s. After drying the surface, they were dried in an oven at 60 °C for 5 min. The initial conductivity was measured using the four-probe method. Then, the films were exposed to hot air (oven) at 50 °C for 7 days, and their conductivity was tested again and the retention rate relative to the initial conductivity was calculated.

[0065] Table 1: Properties of different alkylthiophene copolymers

[0066]

[0067] As shown in Table 1, the doped state of the methyl benzoate-alkyl thiophene copolymers obtained in Examples 1-6 of the present invention has good air stability and can maintain a conductivity of more than 75% or even more than 85% after being treated with hot air for 7 days.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A methyl benzoate-alkylthiophene copolymer, characterized in that, Its structural formula is shown in equation (Ⅰ): Equation (Ⅰ); Wherein, R is selected from one of the alkyl groups having 4 to 12 carbon atoms.

2. The methyl benzoate-alkylthiophene copolymer according to claim 1, characterized in that, The alkyl group is a straight-chain alkyl group having 6 to 8 carbon atoms.

3. The methyl benzoate-alkylthiophene copolymer according to claim 1, characterized in that, The copolymer has a weight-average molecular weight of 3-35 kDa and a molecular weight distribution of 1.05-2.

5.

4. The methyl benzoate-alkylthiophene copolymer according to claim 1, characterized in that, The copolymer has a weight-average molecular weight of 3-10 kDa and a molecular weight distribution of 1.05-1.

4.

5. The methyl benzoate-alkylthiophene copolymer according to claim 1, characterized in that, The copolymer is prepared from methyl 2,5-dibromobenzoate and alkyl-substituted thiophene. .

6. The method for preparing the methyl orthobenzoate-alkylthiophene copolymer according to any one of claims 1 to 5, characterized in that, Includes the following steps: In the presence of catalysts and auxiliaries, methyl 2,5-dibromobenzoate and alkyl-substituted thiophene A polymerization reaction occurs to obtain the methyl benzoate-alkyl thiophene copolymer.

7. The method for preparing the ortho-methyl benzoate-alkylthiophene copolymer according to claim 6, characterized in that, The molar ratio of the methyl 2,5-dibromobenzoate to the alkyl-substituted thiophene is 1:0.9~1.

1.

8. The method for preparing the ortho-methyl benzoate-alkylthiophene copolymer according to claim 6, characterized in that, The catalyst includes palladium-based catalysts; And / or, the amount of the catalyst used is 0.5 to 4 mol% of the sum of the molar amounts of the methyl 2,5-dibromobenzoate and the alkyl-substituted thiophene; And / or, the additives include inorganic bases, organic acids, and solvents.

9. The method for preparing the methyl ortho-benzoate-alkylthiophene copolymer according to claim 8, characterized in that, The inorganic base is selected from potassium carbonate; And / or, the amount of the inorganic base is 1.2 to 2 times the sum of the amounts of the methyl 2,5-dibromobenzoate and the alkyl-substituted thiophene; And / or, the organic acid is selected from pivalic acid; And / or, the amount of the organic acid used is 10-50 mol% of the sum of the amounts of the methyl 2,5-dibromobenzoate and the alkyl-substituted thiophene; And / or, the solvent is selected from at least one of toluene and N,N-dimethylacetamide.

10. The method for preparing the ortho-methyl benzoate-alkylthiophene copolymer according to claim 6, characterized in that, The polymerization reaction is carried out at a temperature of 80-120°C; and / or the polymerization reaction is carried out for a duration of 18-30 hours.

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