A high-performance polythiophene nanoconductive polymer material and its preparation method

Abstract

The present invention discloses a high-performance polythiophene nano-conductive polymer material and a preparation method thereof, belonging to the field of conductive polymer technology. The high-performance polythiophene nano-conductive polymer material comprises the following raw materials: 20-40 parts of a polar ionic liquid, 40-70 parts of a non-polar ionic liquid, 1-3 parts of a thiophene monomer, 12-20 parts of an oxidant, and 0.01-1 parts of a dopant; first, the thiophene monomer is added to the non-polar ionic liquid and mixed evenly, and then the dopant is added and mixed to obtain a solution A; the oxidant is added to the polar ionic liquid and mixed evenly to obtain a solution B; the solution B is added dropwise to the solution A and mixed evenly to obtain a suspension; the suspension is filtered to obtain solid particles, which are then washed to obtain a high-performance polythiophene nano-conductive polymer material. The present invention successfully synthesizes a polythiophene material with a highly ordered nanoparticle morphology, with a yield of up to 80% at room temperature and a maximum conductivity of 25S / cm.

Description

Technical Field

[0001] The invention belongs to the technical field of conductive polymers, and in particular relates to a high-performance polythiophene nano conductive polymer material and a preparation method thereof. Background Art

[0002] Polythiophene (PTh), a prominent conductive polymer, has attracted widespread attention due to its exceptional chemical stability and remarkable optical properties. Its tunable conductivity, ranging from insulators to semiconductors and even metals, holds enormous potential for application in numerous fields. When exhibiting metallic-level conductivity, PTh has broad applications in batteries, smart windows, antistatic coatings, and various sensors. When acting as a semiconductor, PTh is particularly prominent in high-tech fields such as LEDs, field-effect transistors (FETs), and photovoltaic cells.

[0003] However, the synthesis of polythiophenes faces numerous challenges, particularly due to the high oxidation potential of the inert sulfur element in the thiophene ring, making efficient polymerization in water difficult. Although PTh is typically synthesized in organic solvents using electrochemical polymerization or chemical oxidative polymerization, electrochemical methods are limited to the electrode region, resulting in low yields and high costs. Therefore, chemical oxidative polymerization has become a more popular method due to its excellent selectivity, high yield, ease of synthesis, and superior conductivity. During chemical oxidative polymerization, reaction conditions and the nature of the doped anion have a decisive influence on the final properties of the material. Although post-doping with iodine vapor can significantly improve the conductivity of PTh, this process requires additional steps and careful handling of the toxicity of iodine vapor. Furthermore, while traditional anhydrous organic solvents such as chloroform and acetonitrile are effective in the chemical oxidative synthesis of PTh, these solvents generally offer low yields, especially at low ambient temperatures. Given the potential environmental risks posed by these volatile organic solvents, the development of efficient, environmentally friendly, and post-processing-free synthesis methods is urgently needed. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to propose a high-performance polythiophene nanoconductive polymer material and a preparation method thereof, which is a new synthesis route of PTh based on environmentally friendly ionic liquids, aiming to achieve high conductivity without the need for subsequent doping treatment.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of the present invention is to provide a high-performance polythiophene nano-conductive polymer material, which comprises the following raw materials in parts by mass:

[0007] 20-40 parts of polar ionic liquid, 40-70 parts of non-polar ionic liquid, 1-3 parts of thiophene monomer, 12-20 parts of oxidant, and 0.01-1 part of dopant.

[0008] In some embodiments, the molar ratio of the thiophene monomer to the oxidant is 1:6-10.

[0009] It should be noted that in the synthesis of conductive polythiophene, selecting a molar ratio of thiophene monomer to oxidant of 1:6-10 can balance the reaction rate, degree of polymerization, conductivity and stability, and can produce polymers with good conductivity and uniform structure, which is suitable for applications with high requirements for polymer quality.

[0010] In some embodiments, the polar ionic liquid is selected from at least one of small molecule imidazole, quaternary ammonium salt and pyridinium ionic liquids; the non-polar ionic liquid is selected from at least one of imidazole containing alkyl side chains and quaternary ammonium salt ionic liquids containing large organic cations.

[0011] Preferably, the polar ionic liquid is 1-ethyl-3-methylimidazole hydrochloride, and the non-polar ionic liquid is 1-octyl-3-methylimidazole.

[0012] It should be noted that 1-ethyl-3-methylimidazole hydrochloride and 1-octyl-3-methylimidazole were selected as ionic liquids based on their imidazolyl structure, low volatility, and tunable physicochemical properties. Both have an imidazolyl core and exhibit good thermal and chemical stability. By varying the alkyl chain length and anion type, their polarity and solubility properties differ: 1-ethyl-3-methylimidazole hydrochloride exhibits high polarity due to its short alkyl chain and polar anion, making it suitable for polar environments, while 1-octyl-3-methylimidazole exhibits low polarity due to its longer alkyl chain, making it more suitable for applications in non-polar environments.

[0013] Polar ionic liquids include 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), and 1-methyl-3-propylimidazolium trifluoromethanesulfonate ([MPIM][TfO]). Non-polar ionic liquids include 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][NTf2]). These ionic liquids exhibit varying properties in polarity, conductivity, and thermal stability by varying the length of the substituents on the imidazole ring and the type of anion, making them suitable for a variety of chemical and industrial applications.

[0014] In some embodiments, the thiophene monomer is selected from at least one of thiophene and its derivatives.

[0015] In some other embodiments, the thiophene monomer is selected from at least one of 2,2'-bithiophene, 3,4-ethylenedioxythiophene, thiophene and bithiophene.

[0016] In some embodiments, the oxidant is selected from at least one of ferric chloride, potassium persulfate, ammonium persulfate, and potassium permanganate.

[0017] In some embodiments, the dopant is selected from at least one of sulfuric acid, phosphoric acid, and benzoic acid.

[0018] The second aspect of the present invention is to provide a method for preparing a high-performance polythiophene nano-conductive polymer material, comprising the following steps:

[0019] S1: Add thiophene monomers to non-polar ionic liquid and mix well;

[0020] S2: Add dopant to the mixed system of S1 and mix to obtain solution A;

[0021] S3: adding an oxidant to the polar ionic liquid and mixing them uniformly to obtain solution B;

[0022] S4: Add solution B dropwise to solution A and mix well to obtain a suspension;

[0023] S5: filtering the suspension to obtain solid particles, and washing to obtain high-performance polythiophene nano-conductive polymer materials.

[0024] In some embodiments, the mixing temperature in S1-S4 is 20-35°C.

[0025] It should be noted that an experimental temperature of around 25°C ensures reaction stability and reproducibility, while achieving a moderate reaction rate and equilibrium, avoiding the adverse effects of side reactions or material decomposition. Excessively high temperatures may accelerate the reaction but increase the formation of byproducts and material instability, while excessively low temperatures can reduce reaction rates, affect solubility, or cause equilibrium shifts. Therefore, operating at 20-35°C achieves a good balance between reaction performance and experimental conditions.

[0026] In some embodiments, the mixing time in S2 is 40-80 min, the mixing time in S3 is 5-20 min, and the mixing time in S4 is 20-30 h.

[0027] In some embodiments, the washing step in S5 is washing with isopropyl alcohol, deionized water and acetone in sequence.

[0028] The present invention has the following beneficial effects:

[0029] 1. By adjusting multiple parameters such as the ratio of thiophene monomer to oxidant, reaction temperature, and ionic liquid solvent type, the present invention successfully synthesized polythiophene materials with highly ordered nanoparticle morphology. The yield of the synthesis at room temperature is as high as 80%, and the maximum conductivity reaches 25S / cm.

[0030] 2. The present invention uses polar ionic liquids and non-polar ionic liquids. Ionic liquids, with their low viscosity, low vapor pressure, and non-volatility at room temperature, create a stable environment for the effective polymerization of thiophene, in sharp contrast to traditional volatile organic solvents, greatly reducing the potential impact on the environment.

[0031] 3. The preparation method provided by the present invention reduces the dependence on and emission of harmful chemicals, can achieve green and sustainable development, and reduce the impact of the chemical industry on the environment BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an SEM image of the high-performance polythiophene nanoconductive polymer material of Example 2 of the present application;

[0033] Figure 2 This is the X-ray diffraction pattern of the high-performance polythiophene nanoconductive polymer material of Example 2 of the present application. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be understood as limiting the present invention.

[0035] Example 1

[0036] A high-performance polythiophene nanoconductive polymer material comprises the following raw materials, calculated by weight: 33 parts of 1-ethyl-3-methylimidazole hydrochloride, 66 parts of 1-octyl-3-methylimidazole, 2 parts of thiophene monomer, 0.1 parts of sulfuric acid, and 12 parts of anhydrous ferric chloride; wherein the molar ratio of the thiophene monomer to the oxidant is 1:6.

[0037] The above-mentioned high-performance polythiophene nano-conductive polymer material is obtained by the following preparation steps:

[0038] S1: dissolving thiophene monomer in 1-octyl-3-methylimidazole, maintaining the reaction temperature at 25°C, to prepare a homogeneous and transparent mixed solution;

[0039] S2: Add sulfuric acid to the mixture obtained in S1 and continue stirring at 25°C for 60 minutes to form a uniform solution A;

[0040] S3: Dissolve anhydrous ferric chloride in 1-ethyl-3-methylimidazole hydrochloride, control the reaction temperature at 25°C, and stir for 10 minutes to form a uniform reddish-brown solution B;

[0041] S4: Solution B was added dropwise to solution A for polymerization reaction. The reaction temperature was controlled at 25°C and stirring was continued for 24 hours to obtain a deep red suspension.

[0042] S5: The suspension after the reaction is filtered to separate solid particles, and then the solid particles are washed with isopropyl alcohol, deionized water and acetone in sequence to remove impurities to obtain a high-performance polythiophene nanoconductive polymer material.

[0043] Example 2

[0044] The same as Example 1, except that the amount of ferric chloride is 16 parts, and the molar ratio of thiophene monomer to oxidant is 1:8.

[0045] Example 3

[0046] The same as Example 1, except that the ferric chloride is 20 parts, and the molar ratio of the thiophene monomer to the oxidant is 1:10.

[0047] Comparative Example 1

[0048] A traditional polythiophene comprises the following raw materials, calculated by weight: 33 parts of acetonitrile, 66 parts of dichloromethane, 2 parts of thiophene monomer, 0.1 parts of sulfuric acid, and 16 parts of anhydrous ferric chloride.

[0049] The above polythiophene is obtained by the following preparation steps:

[0050] S1: Dissolve thiophene monomer in dichloromethane, maintain the reaction temperature at 25°C, and prepare a uniform and transparent mixed solution.

[0051] S2: Add sulfuric acid to the mixed solution obtained in S1 and continue stirring at 25°C for 60 minutes to form a uniform A solution.

[0052] S3: Dissolve anhydrous ferric chloride in 33 parts of acetonitrile, control the reaction temperature at 25°C, and stir for 10 minutes to form a uniform reddish-brown solution B.

[0053] S4: Solution B was added dropwise to solution A for polymerization reaction. The reaction temperature was maintained at 25°C and stirring was continued for 24 hours to obtain a deep red suspension.

[0054] S5: The suspension after the reaction is filtered to separate solid particles, and then the solid particles are washed with isopropyl alcohol, deionized water and acetone in sequence to remove impurities to obtain a high-performance polythiophene nanoconductive polymer material.

[0055] Comparative Example 2

[0056] The same as Example 1, except that the ferric chloride is 4 parts, and the molar ratio of the thiophene monomer to the oxidant is 1:2.

[0057] Comparative Example 3

[0058] The same as Example 1, except that the amount of ferric chloride is 8 parts, and the molar ratio of thiophene monomer to oxidant is 1:4.

[0059] Comparative Example 4

[0060] The same as Example 3, the only difference is that the amount of 1-octyl-3-methylimidazole is 33 parts.

[0061] Performance Testing

[0062] The high-performance polythiophene nano-conductive polymer materials and polythiophene powders prepared in Examples 1-3 and Comparative Examples 1-4 were tested for micromorphology and conductivity. The micromorphology of the samples was examined using a scanning electron microscope (SEM), and the conductivity was tested using a four-probe method. The results are as follows: Figure 1-2 The performance test results are shown in Table 1.

[0063] Table 1 Characterization results of Examples 1-3 and Comparative Examples 1-4

[0064]

[0065] The results in Table 1 show that the polythiophene materials of Examples 1 to 3 show a significant improvement in electrical conductivity compared to Comparative Example 1. This result indicates that at similar doping levels, polythiophene using ionic liquids as reaction media has superior electrical conductivity. The stability and non-volatile nature of ionic liquids create a stable environment for the effective polymerization of thiophene, thereby promoting the improvement of the crystallinity and yield of polythiophene. Figure 2 It can be seen that the polythiophene material is in a highly crystalline state, which significantly enhances the conductivity of polythiophene, reaching 16 times the conductivity of traditional organic solvent polymerized polythiophene. Figure 1 It can be seen that the spontaneous polymerization of thiophene in ionic liquids can form regular nanoparticles, which enhances its processing ability and makes its application prospects in the fields of coatings and smart sensors broader.

[0066] Compared with Comparative Examples 2 and 3, the polythiophene materials of Examples 1-3 exhibit superior conductivity and significantly improved yield, demonstrating that an appropriate molar ratio of thiophene monomer to oxidant can balance reaction rate, degree of polymerization, conductivity, and stability, resulting in highly conductive polymers. Compared with Comparative Example 4, insufficient nonpolar ionic liquid can lead to irregular aggregation, resulting in an amorphous state and reduced conductivity.

[0067] Figure 1The high-performance polythiophene nano-conductive polymer material obtained in Example 2 is a nanoparticle structure of 200-250 nm, indicating that the present invention can produce a polythiophene material with a highly ordered nanoparticle morphology; Figure 2 The X-ray diffraction pattern shows the crystalline state of the polythiophene in Example 2. The polythiophene in Example 2 exhibits significant crystallinity on the (100) and (020) planes, with the (020) plane exhibiting a particularly high and sharp diffraction peak, indicating a high degree of crystalline order. This ordered structure enhances the material's electrical conductivity, mechanical strength, and thermal stability, resulting in excellent performance in electronic and optoelectronic applications, demonstrating its superior performance as a conductive polymer material.

[0068] Another significant advantage of this invention is the environmentally friendly nature of ionic liquids as polymerization media. Compared to traditional organic solvents, ionic liquids have low volatility and high chemical stability, effectively reducing the emission of harmful substances and the risk of environmental pollution. This green and sustainable synthesis method not only improves the performance of polythiophene but also conforms to current industrial development and environmental trends.

[0069] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance polythiophene nano-conductive polymer material, characterized in that: The following steps are involved: S1: Add thiophene monomers to non-polar ionic liquid and mix well; S2: Add dopant to the mixed system of S1, stir and mix to obtain solution A; S3: adding an oxidant to the polar ionic liquid and stirring to mix uniformly to obtain solution B; S4: Add solution B dropwise to solution A, and stir to mix evenly to obtain a suspension; S5: filtering the suspension to obtain solid particles, and washing to obtain high-performance polythiophene nano-conductive polymer materials; Wherein, by mass, the polar ionic liquid is 20-40 parts, the non-polar ionic liquid is 40-70 parts, the thiophene monomer is 1-3 parts, the oxidant is 12-20 parts, and the dopant is 0.01-1 part; the molar ratio of the thiophene monomer to the oxidant is 1:6-10; The polar ionic liquid is 1-ethyl-3-methylimidazole hydrochloride, and the non-polar ionic liquid is 1-octyl-3-methylimidazole.

2. The method for preparing a high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: The thiophene monomer is selected from at least one of thiophene and its derivatives.

3. The method for preparing a high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: The oxidant is selected from at least one of ferric chloride, potassium persulfate, ammonium persulfate, and potassium permanganate.

4. The method for preparing a high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: The dopant is selected from at least one of sulfuric acid, phosphoric acid and benzoic acid.

5. The method for preparing high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: The mixing temperature in S1-S4 is 20-35°C.

6. The method for preparing high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: The mixing time in S2 is 40-80 min, the mixing time in S3 is 5-20 min, and the mixing time in S4 is 20-30 h.

7. The method for preparing high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: In the step S5, the washing step is to use isopropyl alcohol, deionized water and acetone to wash in sequence.

8. A high-performance polythiophene nano-conductive polymer material prepared by the method for preparing a high-performance polythiophene nano-conductive polymer material according to any one of claims 1 to 7.

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