High-performance polythiophene nano conductive polymer material and preparation method thereof

Abstract

The invention discloses a high-performance polythiophene nano conductive polymer material and a preparation method thereof, and belongs to the technical field of conductive polymers. The high-performance polythiophene nano conductive polymer material comprises the following raw materials: 20-40 parts of polar ionic liquid, 40-70 parts of non-polar ionic liquid, 1-3 parts of thiophene monomers, 12-20 parts of an oxidizing agent and 0.01-1 part of a doping agent. The preparation method comprises the following steps: firstly, adding thiophene monomers into non-polar ionic liquid, uniformly mixing, then adding a doping agent, and mixing to obtain a solution A; adding an oxidizing agent into the polar ionic liquid, and uniformly mixing to obtain a solution B; dropwise adding the solution B into the solution A, and uniformly mixing to obtain a suspension; and filtering the suspension to obtain solid particles, and washing to obtain the high-performance polythiophene nano conductive polymer material. According to the invention, the polythiophene material with highly ordered nanoparticle morphology is successfully synthesized, the yield of synthesis at room temperature reaches up to 80%, and the highest conductivity reaches 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), as a prominent conductive polymer, has attracted widespread attention due to its excellent chemical stability and remarkable optical properties. The tunability of its conductivity, covering a wide range from insulators to semiconductors and even metals, makes it show great application potential in many fields. When it has metallic-level conductivity, PTh has a wide range of applications in batteries, smart windows, antistatic coatings, and various sensors; when it behaves 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 process of polythiophene faces many challenges, especially due to the high oxidation potential of the inert sulfur element in the thiophene ring, which makes effective polymerization in water very difficult. Although PTh is usually synthesized in organic solvents by electrochemical polymerization or chemical oxidation polymerization, the electrochemical method has low yield and high cost due to its limited electrode area. Therefore, chemical oxidation polymerization has become a more popular method due to its excellent selectivity, high yield, easy synthesis and excellent conductivity. In the chemical oxidation polymerization process, the reaction conditions and the characteristics of the doped anion have a decisive influence on the final properties of the material. Although the post-doping treatment of iodine vapor can significantly improve the conductivity of PTh, this process requires additional operation steps and the toxicity of iodine vapor needs to be carefully handled. In addition, although traditional anhydrous organic solvents such as chloroform and acetonitrile are effective in the chemical oxidation synthesis of PTh, the yield of these solvents is generally low, especially at low ambient temperatures. In view of the potential threat that these volatile organic solvents may pose to the environment, it is urgent to develop an efficient, environmentally friendly and post-treatment-free synthesis method. Summary of the invention

[0004] In view of the shortcomings of the prior art, 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] 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 by weight:

[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 on polymer quality.

[0010] In some embodiments, the polar ionic liquid is selected from at least one of small molecule imidazole, quaternary ammonium salt and pyridine 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 imidazole structure, low volatility and adjustable physical and chemical properties. Both have an imidazole core and have good thermal and chemical stability. By changing the alkyl chain length and anion type, they differ in polarity and solubility: 1-ethyl-3-methylimidazole hydrochloride exhibits high polarity due to short-chain alkyl and polar anions, suitable for polar environments, while 1-octyl-3-methylimidazole exhibits low polarity due to its longer alkyl chain, which is more suitable for applications in non-polar environments.

[0013] Among them, polar ionic liquids also 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 also include 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][NTf2]). These ionic liquids exhibit different properties in polarity, conductivity, and thermal stability by changing the length of the substituents on the imidazole ring and the type of anions, and are suitable for various chemical and industrial applications.

[0014] In some embodiments, the thiophene-based 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: adding thiophene monomers into non-polar ionic liquid and mixing them evenly;

[0020] S2: adding a dopant to the mixed system of S1 and mixing to obtain solution A;

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

[0022] S4: adding solution B dropwise into solution A and mixing 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 the experimental temperature of about 25°C can ensure the stability and repeatability of the reaction, while achieving a moderate reaction rate and balance, and avoiding the adverse effects of side reactions or material decomposition. Too high a temperature may accelerate the reaction but increase the generation of by-products and the instability of the material, while too low a temperature will reduce the reaction rate, affect solubility or cause equilibrium shift, so operating at 20-35°C can achieve a good balance between reaction effect 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. The present invention successfully synthesized a polythiophene material with a highly ordered nanoparticle morphology by adjusting multiple parameters such as the ratio of thiophene monomer to oxidant, reaction temperature, and ionic liquid solvent type. The yield of the synthesis at room temperature was as high as 80%, and the maximum conductivity reached 25S / cm.

[0030] 2. The present invention adopts polar ionic liquids and non-polar ionic liquids. The 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, which is in sharp contrast to traditional volatile organic solvents and greatly reduces the potential impact on the environment.

[0031] 3. The preparation method provided by the present invention reduces the dependence on and discharge 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 a SEM image of the high-performance polythiophene nano-conductive 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 in conjunction with 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 construed as limiting the present invention.

[0035] Example 1

[0036] A high-performance polythiophene nano conductive polymer material comprises the following raw materials, measured 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, and preparing a uniform and transparent mixed solution;

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

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

[0041] S4: Dropping solution B into solution A for polymerization reaction, the reaction temperature is controlled at 25°C, and stirring is continued for 24 hours to obtain a deep red suspension;

[0042] S5: filtering the suspension after the reaction to separate the solid particles, and then washing the solid particles with isopropanol, deionized water and acetone in sequence to remove impurities to obtain a high-performance polythiophene nano-conductive polymer material.

[0043] Example 2

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

[0045] Example 3

[0046] The same as Example 1, the only difference is 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 conventional 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, stir for 10 minutes, and form a uniform reddish brown B solution.

[0053] S4: Solution B was dropped into 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: Filter the suspension after the reaction to separate the solid particles, and then use isopropanol, deionized water and acetone to wash the solid particles in sequence to remove impurities to obtain a high-performance polythiophene nano conductive polymer material.

[0055] Comparative Example 2

[0056] The same as Example 1, the only difference is 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, the only difference is that the ferric chloride is 8 parts, and the molar ratio of the thiophene monomer to the oxidant is 1:4.

[0059] Comparative Example 4

[0060] The same as Example 3, the only difference is that: 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 microscopic morphology and conductivity. The microscopic morphology of the samples was detected 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] According to the results in Table 1, compared with Comparative Example 1, the polythiophene materials of Examples 1 to 3 show a significant improvement in electrical conductivity. This result shows that at similar doping levels, polythiophene using ionic liquid as a reaction medium 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 have excellent electrical conductivity and significantly improved yields, indicating that the appropriate molar ratio of thiophene monomer and oxidant can balance the reaction rate, degree of polymerization, electrical conductivity and stability, and can produce polymers with good electrical conductivity. Compared with Comparative Example 4, it can be seen that insufficient non-polar ionic liquid will lead to irregular aggregation, resulting in an amorphous state, which reduces the electrical conductivity.

[0067] Figure 1The high-performance polythiophene nano-conductive polymer material prepared in Example 2 is a nanoparticle structure of 200-250 nm, indicating that the present invention can prepare a polythiophene material with a highly ordered nanoparticle morphology; Figure 2 The crystal state of polythiophene in Example 2 is shown. From the X-ray diffraction pattern, it can be seen that the polythiophene in Example 2 exhibits significant crystallinity on the (100) and (020) crystal planes, especially the diffraction peak intensity on the (020) crystal plane is high and sharp, indicating that the polythiophene has a high degree of crystal order. This ordered structure enhances the electrical conductivity, mechanical strength and thermal stability of the material, making it exhibit excellent performance in electronic and optoelectronic applications, reflecting its high-quality choice as a conductive polymer material.

[0068] The environmentally friendly nature of ionic liquids as polymerization media is another significant advantage of the present invention. Compared with 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 the current trend of industrial development and environmental protection.

[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 creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A high-performance polythiophene nano-conductive polymer material, characterized in that: The following raw materials are included by weight: 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.

2. The high-performance polythiophene nano-conductive polymer material according to claim 1, characterized in that: The molar ratio of the thiophene monomer to the oxidant is 1:6-10.

3. The high performance polythiophene nano conductive polymer material according to claim 1, characterized in that: The polar ionic liquid is selected from at least one of small molecule imidazole, quaternary ammonium salt and pyridine ionic liquids; the non-polar ionic liquid is selected from at least one of imidazole containing alkyl side chains and quaternary ammonium salt containing large organic cations.

4. The 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.

5. The 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.

6. The 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.

7. The method for preparing the high-performance polythiophene nano-conductive polymer material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: adding thiophene monomers into non-polar ionic liquid and mixing them evenly; S2: adding a dopant to the mixed system of S1 and mixing to obtain solution A; S3: adding an oxidant to the polar ionic liquid and mixing them evenly to obtain a B solution; S4: adding solution B dropwise into solution A and mixing well to obtain a suspension; S5: filtering the suspension to obtain solid particles, and washing to obtain high-performance polythiophene nano-conductive polymer materials.

8. The method for preparing high-performance polythiophene nano-conductive polymer material according to claim 7, characterized in that: The mixing temperature in S1-S4 is 20-35°C.

9. The method for preparing high-performance polythiophene nano-conductive polymer material according to claim 7, 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.

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

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