A polythiophene polymer and its preparation method

Abstract

This invention discloses a polythiophene polymer, wherein the structural formula of the polythiophene polymer is as follows, wherein R is an alkyl or ester group, and n is a positive integer that makes the molecular weight of the polythiophene polymer between 1200 and 8000; the molecular weight distribution of the polythiophene polymer is 1.05-1.28; the polymer prepared by this invention has the characteristics of well-defined end groups, regular structure, controllable molecular weight and narrow molecular weight distribution, which makes the prepared polymer of great significance in exerting its inherent photoelectric properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis, specifically relating to a polythiophene polymer and its preparation method. Background Technology

[0002] Polythiophene is a class of conjugated polymers with unique electronic structures and optical properties. Due to the thiophene ring structure in its molecular chain, polythiophene exhibits excellent properties in conductivity, photoelectric conversion, and photoluminescence. In particular, polythiophene with high stereoregularity, due to its highly ordered arrangement, often possesses superior physical and chemical properties and is considered to have great potential in various applications. However, existing methods for synthesizing polythiophene often suffer from complex synthesis processes, poor structural regularity of the product, and low purity, which limits the performance of polythiophene in practical applications. Therefore, developing a simple and efficient synthetic method for preparing structurally regular polythiophene is of great significance.

[0003] Traditional methods for synthesizing polythiophene typically require multiple reaction steps and complex post-processing, while direct arylation synthesis (DArP) simplifies the process, improves atom economy, and reduces environmental pollution. However, the reaction is usually carried out at high temperatures and has a long polymerization time, which can lead to increased energy consumption and poor reaction control. Finding suitable catalysts and reaction media to allow the arylating agent to polymerize with the thiophene monomer under mild conditions, and synthesizing polythiophenes with regular structures and narrow molecular weight distributions through precise control of reaction conditions and catalyst ratios, has significant application value and represents a technical challenge in this field. Furthermore, the synthesis of polythiophene polymers with well-defined end groups remains a technical challenge in this field, as it allows for the utilization of the excellent photoelectric properties of thiophene polymers for the further synthesis of other block polymers.

[0004] Therefore, those skilled in the art are dedicated to developing a mild DArP condition to prepare polymers with well-defined end groups and high stereoregularity, while achieving controllable molecular weight (Mn) and narrow molecular weight distribution (Mw / Mn), thereby providing a new method for the precise and controllable synthesis of polythiophene. Summary of the Invention

[0005] The present invention provides a polythiophene polymer and a method for preparing the same. This method can efficiently synthesize polythiophene with controllable molecular weight and narrow molecular weight distribution through catalyst transfer polycondensation at a relatively mild temperature and a relatively fast reaction rate.

[0006] To achieve the above-mentioned objectives, the present invention provides a polythiophene polymer with the following structural formula:

[0007]

[0008] Wherein, R is an alkyl or ester group, and n is a positive integer that makes the molecular weight of the polythiophene polymer between 1200 and 8000; the molecular weight distribution of the polythiophene polymer is 1.05-1.28.

[0009] Preferably, in the above structural formula, R is independently selected from -CH2(CH2)4CH3 and -CO2CH2(CH2)4CH3;

[0010] One of -CO2C(CH3)3.

[0011] On the other hand, the present invention provides a method for preparing the above-mentioned polythiophene polymer, comprising the following steps:

[0012] S1. After placing the thiophene monomer, neodecanoic acid, K3PO4 and catalyst into the reactor, the reactor is subjected to several alternating vacuuming and inert gas filling processes to place the reactants in an inert environment.

[0013] S2. Add solvent, heat to 40-60℃, and react for 10-240 hours;

[0014] S3. After the reaction is complete, the mixture generated by the reaction is post-processed to obtain the polythiophene polymer.

[0015] Preferably, the catalyst is a palladium catalyst, and its structure is as follows:

[0016] Preferably, the thiophene monomer is Wherein, R is independently selected from -CH2(CH2)4CH3,

[0017] One of -CO2CH2(CH2)4CH3; -CO2C(CH3)3.

[0018] Preferably, the molar ratio of the palladium catalyst to the thiophene monomer is 1:(5-35).

[0019] Preferably, the solvent is a mixture of N,N-dimethylacetamide, tetrahydrofuran and water, wherein the volume ratio of N,N-dimethylacetamide, tetrahydrofuran and water is 3:(1-2):(0.1-0.4).

[0020] Preferably, the post-processing operation includes adding methanol solution to quench the reaction to precipitate the polythiophene polymer, obtaining a crude polythiophene polymer product after filtration, methanol washing and drying, dissolving the crude polythiophene polymer product in an organic solvent to obtain an organic phase, washing the organic phase with water, collecting the organic phase layer and removing the organic reagents therein to obtain the polythiophene polymer.

[0021] Preferably, the inert gas is selected from one or more of nitrogen, helium, and argon.

[0022] The beneficial technical effects of this invention are reflected in:

[0023] The polythiophene synthesis method described in this invention is simple, requires less stringent experimental conditions, is easy to operate, has high atom utilization, and reduces the generation of hazardous waste. The polythiophene synthesized by this method exhibits well-defined end groups, regular structure, controllable molecular weight, and narrow molecular weight distribution. Furthermore, through in-depth research on polymerization solvents, a highly efficient DMA / THF / H2O reaction solvent system was proposed, which allows for the direct and efficient synthesis of polythiophene polymers with well-defined end groups under mild conditions via arylation, providing an efficient method for the subsequent synthesis of polythiophene compounds. Attached Figure Description

[0024] Figure 1 This is a gel permeation chromatogram of the polymers obtained in Examples 1-3 of the present invention.

[0025] Figure 2 This is the hydrogen spectrum of the polymer obtained in Example 1.

[0026] Figure 3 This is the fluorine spectrum of the polymer obtained in Example 1.

[0027] Figure 4 This is the phosphorus spectrum of the polymer obtained in Example 1.

[0028] Figure 5 This is the MALDI-TOF MS image of the polymer in Example 1.

[0029] Figure 6 This is the hydrogen spectrum of the polymer obtained in Example 4.

[0030] Figure 7 This is the hydrogen spectrum of the polymer obtained in Example 5.

[0031] Figure 8 These are gel permeation chromatograms of polymers obtained under different solvent ratios. Detailed Implementation

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The present invention has many different embodiments and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. The invention will be defined only by the claims.

[0033] Example 1

[0034] 74.2 mg (0.3 mmol) of thiophene monomer 2-bromo-3-hexylthiophene, 0.09 mmol of neodecanoic acid, 0.378 mmol of K3PO4, and palladium catalyst were added to a 10 mL polymerization flask, with a molar ratio of thiophene monomer to palladium catalyst of 5:1. The polymerization flask was evacuated and then purged with nitrogen, repeated three times, each evacuation lasting at least 10 minutes. A degassed mixed solvent containing 3 mL of N,N-diethylacetamide, 1 mL of tetrahydrofuran, and 0.1 mL of deionized water was added under a nitrogen atmosphere. The polymerization flask was then placed at 55 °C and reacted for 15 hours. Methanol was added to precipitate the polymer. The resulting product was washed 4-5 times with methanol, dried, dissolved in dichloromethane, washed with water, concentrated under reduced pressure, and vacuum dried until the mass remained constant, yielding 46.8 mg of polythiophene polymer. In this embodiment, the palladium catalyst has the following structural formula: The structural formula of the obtained polythiophene polymer is as follows:

[0035] See appendix Figure 1 As shown, the number-average molecular weight, as determined by gel permeation chromatography, is 1.17 × 10⁻⁶. 3 The polymer, Da, has a molecular weight distribution of 1.06 and a degree of polymerization of 5. The proton, fluorine, and phosphorus spectra of the obtained polymer are shown in the appendix. Figure 2-4 As can be seen, all hydrogen atoms appear in their corresponding positions, indicating that a polymer with the corresponding structure has been prepared. Furthermore, both the fluorine and phosphorus spectra show the presence of fluorine and phosphorus in the polymer, whereas, according to synthetic theory, they should only appear at opposite ends of the polymer structure.

[0036] Figure 5 The image shows the MALDI-TOF MS plot of the polymer in Example 1. As can be seen from the figure, each peak differs by about 166.38, which is the molecular weight of a structural unit. This also indicates that the polymerization unit proceeded as designed.

[0037] Example 2

[0038] 87 mg (0.3 mmol) of thiophene monomer, 0.09 mmol of neodecanoic acid, 0.378 mmol of K3PO4, and palladium catalyst were added to a 10 mL polymerization flask, with a molar ratio of thiophene monomer to palladium catalyst of 9:1. The polymerization flask was evacuated and then purged with nitrogen, repeated three times, each evacuation lasting at least 10 minutes. A degassed mixed solvent containing 3 mL of N,N-diethylacetamide, 1 mL of tetrahydrofuran, and 0.1 mL of deionized water was added under a nitrogen atmosphere. The polymerization flask was then placed at 55 °C and reacted for 120 hours. Methanol was added to precipitate the polymer. The resulting product was washed 4-5 times with methanol, dried, dissolved in dichloromethane, washed with water, concentrated under reduced pressure, and vacuum dried until the mass remained constant, yielding 56.7 mg of polyalkylthiophene. In this example, the structure of the thiophene monomer is as follows: The structural formula of the palladium catalyst is The structural formula of the obtained polythiophene polymer is as follows:

[0039]

[0040] Gel permeation chromatography analysis revealed that its number-average molecular weight was 2.56 × 10⁻⁶. 3 Da has a molecular weight distribution of 1.22 and a degree of polymerization m of 9.

[0041] Example 3

[0042] 78.4 mg (0.3 mmol) of thiophene monomer, 0.09 mmol of neodecanoic acid, 0.378 mmol of K3PO4, and palladium catalyst were added to a 10 mL polymerization flask, with a molar ratio of thiophene monomer to palladium catalyst of 16:1. The polymerization flask was evacuated and then purged with nitrogen, repeated three times, each evacuation lasting at least 10 minutes. A degassed mixed solvent containing 3 mL of N,N-diethylacetamide, 1.1 mL of tetrahydrofuran, and 0.1 mL of deionized water was added under a nitrogen atmosphere. The polymerization flask was then placed at 55 °C and reacted for 240 hours. Methanol was added to precipitate the polymer. The resulting product was washed 4-5 times with methanol, dried, dissolved in dichloromethane, washed with water, concentrated under reduced pressure, and vacuum dried until the mass remained constant, yielding 43.68 mg of polyalkylthiophene. In this example, the structure of the thiophene monomer is as follows: The structural formula of the palladium catalyst is The structural formula of the obtained polythiophene polymer is as follows:

[0043]

[0044] Gel permeation chromatography analysis revealed that its number-average molecular weight was 4.23 × 10⁻⁶. 3 Da has a molecular weight distribution of 1.14 and a degree of polymerization of 21.

[0045] Example 4

[0046] 74.7 mg (0.3 mmol) of thiophene monomer 2-bromo-3-hexylthiophene, 0.09 mmol of neodecanoic acid, 0.378 mmol of K3PO4, and palladium catalyst were added to a 10 mL polymerization flask, with a molar ratio of thiophene monomer to palladium catalyst of 23:1. The polymerization flask was evacuated and then purged with nitrogen, repeated three times, each evacuation lasting at least 10 minutes. A degassed mixed solvent containing 3 mL of N,N-diethylacetamide, 1 mL of tetrahydrofuran, and 0.1 mL of deionized water was added under a nitrogen atmosphere. The polymerization flask was then placed at 55 °C and reacted for 15 hours. Methanol was added to precipitate the polymer. The resulting product was washed 4-5 times with methanol, dried, dissolved in dichloromethane, washed with water, concentrated under reduced pressure, and vacuum dried until the mass remained constant, yielding 47.5 mg of polyalkylthiophene. In the examples, the palladium catalyst has the following structural formula: The structural formula of the obtained polythiophene polymer is as follows:

[0047] See appendix Figure 1 As shown, the number-average molecular weight, as determined by gel permeation chromatography, is 5.57 × 10⁻⁶. 3 Da has a molecular weight distribution of 1.28 and a degree of polymerization of 23.

[0048] Example 5

[0049] 74.7 mg (0.3 mmol) of thiophene monomer 2-bromo-3-hexylthiophene, 0.09 mmol of neodecanoic acid, 0.378 mmol of K3PO4, and palladium catalyst were added to a 10 mL polymerization flask. The molar ratio of thiophene monomer to palladium catalyst was 32:1. The polymerization flask was evacuated and then purged with nitrogen, repeated three times, with each evacuation lasting at least 10 minutes. A degassed mixed solvent containing 1.5 mL of N,N-diethylacetamide, 0.5 mL of tetrahydrofuran, and 0.1 mL of deionized water was added under a nitrogen atmosphere. The polymerization flask was placed at 55 °C and reacted for 15 hours. Methanol was added to precipitate the polymer. The resulting product was washed 4-5 times with methanol, dried, dissolved in dichloromethane, washed with water, concentrated under reduced pressure, and dried under vacuum until the mass remained constant, yielding 46.56 mg of polyalkylthiophene. In this embodiment, the structure of the palladium catalyst is described. The structural formula of the obtained polythiophene polymer is as follows:

[0050] See appendix Figure 1 As shown, the number-average molecular weight, as determined by gel permeation chromatography, is 8.07 × 10⁻⁶. 3 Da has a molecular weight distribution of 1.26 and a degree of polymerization n of 32.

[0051] Examples 1, 4, and 5 demonstrate that the molecular weight of the resulting polythiophene polymer, i.e., its degree of polymerization, can be precisely controlled by simply varying the ratio of thiophene monomer to palladium catalyst. Furthermore, the molecular weight distribution can be controlled within a narrow range of 1.06-1.26.

[0052] Comparative Example 1

[0053] For specific experimental procedures, please refer to the steps in Example 4. The difference is that the mixed solvent contains 1.5 mL of N,N-diethylacetamide and 1.5 mL of tetrahydrofuran.

[0054] After the reaction was complete, 46 mg of polythiophene polymer was obtained. Gel permeation chromatography showed that its number-average molecular weight was 1.22 × 10⁻⁶. 4 Da has a molecular weight distribution of 2.25.

[0055] Comparative Example 2

[0056] For specific experimental procedures, please refer to the steps in Example 4. The difference is that the mixed solvent contains 3 mL of N,N-diethylacetamide and 1 mL of tetrahydrofuran, and the reaction time is 46 h.

[0057] After the reaction was complete, 46.3 mg of polythiophene polymer was obtained. Gel permeation chromatography showed that its number-average molecular weight was 5.64 × 10⁻⁶. 3 Da has a molecular weight distribution of 1.26.

[0058] See appendix Figure 8 The results from Comparative Examples 1 and 2 show that the addition of THF can controllably increase the molecular weight of the polymer within a certain range. When THF is in excess, the molecular weight of the polymer increases, but the molecular weight distribution becomes too wide, reaching 2.25. Therefore, the amount of THF added should be controlled within a suitable range. Further experiments revealed that when the molar ratio of DMA to THF is controlled at 3:(1-2), the molecular weight distribution of the synthesized polymer can be well controlled.

[0059] Referring to Examples 4 and 2, the addition of water can shorten the reaction time. Without water, the polymerization reaction began to show orange fluorescence after approximately 10 hours; with the addition of a certain amount of water, the polymerization reaction began to show orange fluorescence after 5 hours. This indicates that adding a certain amount of water can promote the reaction rate. Specifically, compared to Example 4, the reaction time in Comparative Example 2 needed to be increased by three times to obtain a polymer with an approximate yield. Further experiments showed that controlling the ratio of DMA, THF, and water at 3:(1-2):(0.1-0.4) consistently yielded polymers with controllable molecular weight and a narrow molecular weight distribution. However, excessive water reduced polymer solubility during polymerization, leading to a significant decrease in reaction yield.

[0060] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polythiophene polymer, characterized in that, The structural formula of the polythiophene polymer is shown below: ， Wherein, R is an alkyl or ester group, and n is a positive integer that makes the molecular weight of the polythiophene polymer between 1200 and 8000; the molecular weight distribution of the polythiophene polymer is 1.05-1.

28.

2. The polythiophene polymer as described in claim 1, characterized in that, R is independently selected from one of -CH2(CH2)4CH3, -CO2CH2(CH2)4CH3, or -CO2C(CH3)3.

3. A method for preparing the polythiophene polymer as described in claim 1 or 2, characterized in that, Includes the following steps: S1. After placing the thiophene monomer, neodecanoic acid, K3PO4 and catalyst into the reactor, the reactor is subjected to several alternating vacuuming and inert gas filling processes to place the reactants in an inert environment. S2. Add solvent, heat to 40-60℃, and react for 10-240 hours; S3. After the reaction is complete, the mixture generated by the reaction is post-processed to obtain the polythiophene polymer; The catalyst is a palladium catalyst, and its structure is as follows: ; The solvent is a mixture of N,N-dimethylacetamide, tetrahydrofuran, and water; wherein the volume ratio of N,N-dimethylacetamide, tetrahydrofuran, and water is 3:(1-2):(0.1-0.4). The inert gas is selected from one or more of nitrogen, helium, and argon.

4. The method for preparing polythiophene polymer according to claim 3, characterized in that, The thiophene monomer is R is independently selected from one of -CH2(CH2)4CH3, -CO2CH2(CH2)4CH3, and -CO2C(CH3)3.

5. The method for preparing polythiophene polymer according to claim 3, characterized in that, The molar ratio of the palladium catalyst to the thiophene monomer is 1:(5-35).

6. The method for preparing polythiophene polymer according to claim 3, characterized in that, The post-processing operation includes adding methanol solution to quench the reaction and precipitate the polythiophene polymer. After filtration, washing with methanol and drying, a crude polythiophene polymer product is obtained. The crude polythiophene polymer product is dissolved in an organic solvent to obtain an organic phase. The organic phase is then washed with water, and the organic phase layer is collected and the organic reagents are removed to obtain the polythiophene polymer.

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