Method for electrochemical synthesis of thin films of thiophene-based conducting polymers in aqueous solution and applications thereof

Abstract

The present application provides a method for electro-synthesis of a thiophene-based conductive polymer film in an aqueous solution and application of the film, which comprises electrochemical synthesis of a conductive polymer film in an aqueous solution and metallization of the film. Traditional preparation methods of a thiophene-based conductive polymer film have poor solubility of polymer monomers, and thus the monomers need to be modified or dissolved in special organic solvents. The use of organic solvents not only pollutes the environment, but also limits the universality of the preparation of the polymer film to some extent and affects its large-scale application. The present application provides a method for electro-synthesis of a thiophene-based conductive polymer film in an aqueous solution, which uses an aqueous electrolyte solution with low price and almost no pollution to the environment, and can quickly prepare a thiophene-based conductive polymer film with high quality and high stability. Further metallization modification of the film can be applied to various electronic product fields, especially flexible and wearable electronic information products.

Description

Technical Field

[0001] This invention belongs to the field of conductive polymer metallization technology, and specifically relates to a method for electrosynthesizing thiophene-based conductive polymer films in an aqueous solution and their metallization applications.

[0002] Specifically, this invention relates to the synthesis of thiophene-based conductive polymer films via electrochemical methods and the metallization of these films using electrochemical techniques. This technology not only provides a method for electrosynthesizing stable and low-cost thiophene-based conductive polymer films in aqueous solutions, but also enables metal deposition of the thiophene-based conductive polymer films, thereby optimizing and improving polymer properties and broadening the application fields of the polymer. It is particularly applicable to flexible, wearable, and portable electronic information products. Technical Background

[0003] With the rapid development of materials science and electronic technology, the method of endowing conductive polymers with excellent conductivity and mechanical stability by depositing a metal layer on the surface of conductive polymers has been widely used in flexible electronic devices, aerospace, and advanced circuits. Thiophene-based conductive polymers possess excellent conductivity, chemical stability, and mechanical flexibility, making them one of the most promising candidates for direct electrodeposition of metals. Traditional methods for preparing thiophene-based conductive polymer thin films typically rely on organic solvents. For example, invention patent CN1962961A discloses a polythiophene thin film prepared from an acetonitrile solution containing monomers and a supporting electrolyte. This not only pollutes the environment but also limits its commercial application in specific situations. Alternatively, by modifying the thiophene monomer through ion doping, the solubility of the monomer in aqueous solution is increased, thereby forming a polymer thin film. For example, invention patent CN113737241A discloses a water-soluble polythiophene thin film prepared by electrosynthesizing a thiophene derivative doped with sodium polystyrene sulfonate (PSS) in an aqueous solution of sodium dodecylbenzene sulfonate (SDBS). The aforementioned methods require the use of organic solutions that are environmentally polluting and harmful to human health, or require modification of the monomers to enhance their solubility, thereby achieving the preparation of polymer films. Furthermore, these methods use expensive raw materials, hindering large-scale industrial production with economic viability. In contrast, the method proposed in this patent is a method for preparing high-quality, highly stable, and low-cost thiophene-based conductive polymer films. Moreover, the resulting polymer, after metallization, can be applied to flexible, wearable, and portable electronic information products, expanding the application fields of polymers. Summary of the Invention

[0004] The purpose of this invention is to provide a method for electrosynthesizing thiophene-based conductive polymer films in an aqueous solution and their metallization applications. Through electrochemical polymerization, highly stable and low-cost thiophene-based conductive polymer films are successfully synthesized in an aqueous solution. These films are then used as the basis for metal electrodeposition, achieving efficient metallization of the polymer surface. This invention overcomes the limitations of traditional metallization methods by optimizing the electrosynthesis conditions, significantly improving the metal deposition rate and adhesion, and providing a new technical approach for the metallization applications of conductive polymers.

[0005] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0006] A method for electrosynthesizing thiophene-based conductive polymer films in an aqueous solution, comprising the following steps:

[0007] (1.1) Prepare an electrolyte by dissolving one or more of thiophene and its derivative monomers in an acidic aqueous solution under magnetic stirring to obtain a homogeneous aqueous electrolyte.

[0008] (1.2) Electrochemical synthesis of conductive polymer films: First, the surface of the working electrode is pretreated. Then, in a three-electrode system, using the aqueous electrolyte prepared in (1.1), a thiophene or thiophene-based conductive polymer film is formed on the surface of the working electrode by electrochemical polymerization using cyclic voltammetry.

[0009] As a preferred method, the purity of the thiophene derivative monomer used is greater than 99.5%; the molecular formula of thiophene and its derivative monomers, C4H3S-R, is as follows:

[0010] R is selected from hydrogen, chlorine, bromine, methyl, ethyl, hydroxyl, and thio group, and the concentration of thiophene derivative monomers is 5 to 50 mM.

[0011] As a preferred embodiment, the acidic solution in the aqueous electrolyte component described in step (1.1) is composed of one or more of hydrochloric acid, nitric acid, sulfuric acid, and perchloric acid, as well as one or more water-soluble metal salts corresponding to such acids, wherein the acid concentration is 100 to 500 mM and the monomer concentration of thiophene and its derivatives is 5 to 50 mM.

[0012] As a preferred method, in step (1.2), the three electrodes are a glassy carbon electrode as the working electrode, a platinum sheet as the counter electrode, and a silver / silver chloride electrode as the reference electrode. The pretreatment steps of the glassy carbon electrode are as follows: sanding with fine sandpaper, polishing with chamois cloth, ultrasonic cleaning with ethanol and deionized water, and then immersing the working electrode in nitric acid solution for later use.

[0013] As a preferred method, the electrochemical polymerization method in step (1.2) is cyclic voltammetry, which involves cyclically scanning between 0 and 2.5V for 10 to 40 cycles to achieve the synthesis of the conductive polymer.

[0014] The second objective of this invention is to provide a metallization application of a conductive polymer film: the conductive polymer film prepared by the method is metallized in a metal plating bath using a constant potential method in a three-electrode system, thereby forming a metal layer deposition on the film surface.

[0015] As a preferred embodiment, the metallization application is further described as a constant potential method in a three-electrode system, wherein the three electrodes are a glassy carbon electrode with a thiophene-based conductive polymer film as the working electrode, a platinum sheet as the counter electrode, and a reference electrode selected from either a saturated mercurous sulfate electrode or a silver / silver chloride electrode. The polymerization conditions are as follows: polymerization is carried out in a potential range of 1V to -1V for 3 to 10 minutes, and the formed metal layer includes one or more alloys of copper, silver, nickel, tin, gold, and palladium.

[0016] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0017] (1) Aqueous solution electrosynthesis technology: Compared with the traditional organic solvent electrosynthesis method, the present invention provides an environmentally friendly and low-cost new technology for aqueous solution electrosynthesis of thiophene-based conductive polymer films, which has great environmental and economic benefits.

[0018] (2) Metal electrodeposition without chloride ions: Traditional metal electrodeposition depends on the presence of chloride ions. However, this invention achieves efficient metal electrodeposition on the surface of thiophene-based conductive polymers even in the absence of chloride ions through the interaction between bis-(3-sulfopropyl) disulfide and conductive polymers, greatly expanding the application range of conductive polymer metallization processes. Attached Figure Description

[0019] Figure 1 This is a circuit diagram of the method for electrosynthesizing thiophene-based conductive polymer films in an aqueous solution and metallizing them, according to the present invention.

[0020] Figure 2 Results of the stability test of the thin film prepared in Example 1;

[0021] Figure 3 Time-current curve of copper metallized polythiophene film prepared in Example 3.

[0022] Figure 4 Comparison of copper metallization before and after processing of the polythiophene thin film prepared in Example 3. Detailed Implementation

[0023] The present invention will now be described in detail with reference to specific implementation examples and accompanying drawings. It should be noted that the following implementation examples are only used to further illustrate the present invention and should not 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 content of the present invention are still within the scope of protection of the present invention.

[0024] All raw materials used in the examples are conventional commercially available raw materials and do not require further purification.

[0025] An example provides a method for electrosynthesizing thiophene-based conductive polymer films in an aqueous solution, comprising the following steps:

[0026] (1.1) Prepare an electrolyte by dissolving one or more of thiophene and its derivative monomers in an acidic aqueous solution under magnetic stirring to obtain a homogeneous aqueous electrolyte.

[0027] (1.2) Electrochemical synthesis of conductive polymer films: In a three-electrode system, using the aqueous electrolyte prepared in (1.1), a thiophene or thiophene-based conductive polymer film is formed on the surface of the working electrode by electrochemical polymerization using cyclic voltammetry.

[0028] Preferably, the purity of the thiophene derivative monomer used is greater than 99.5%; the molecular formula of thiophene and its derivative monomers, C4H3S-R, is as follows:

[0029] R is selected from hydrogen, chlorine, bromine, methyl, ethyl, hydroxyl, and thio group, and the concentration of thiophene derivative monomers is 5 to 50 mM.

[0030] In the preferred step (1.1), the acidic solution in the aqueous electrolyte is composed of one or more of hydrochloric acid, nitric acid, sulfuric acid, and perchloric acid, as well as one or more water-soluble metal salts corresponding to these acids, wherein the acid concentration is 100 to 500 mM and the concentration of thiophene and its derivative monomers is 5 to 50 mM.

[0031] Preferably, in step (1.2), the three electrodes are a glassy carbon electrode as the working electrode, a platinum sheet as the counter electrode, and a silver / silver chloride electrode as the reference electrode. The pretreatment steps of the glassy carbon electrode are as follows: sanding with fine sandpaper, polishing with chamois cloth, ultrasonic cleaning with ethanol and deionized water, and then immersing the working electrode in nitric acid solution for later use.

[0032] Preferably, the electrochemical polymerization method in step (1.2) is cyclic voltammetry, which involves cyclically scanning between 0 and 2.5V for 10 to 40 cycles to achieve the synthesis of the conductive polymer.

[0033] The embodiment also provides a metallization application of a conductive polymer film, wherein the conductive polymer film is metallized in a metal plating bath using a constant potential method in a three-electrode system, thereby forming a metal layer deposition on the film surface.

[0034] Furthermore, in the metallization application of the conductive polymer film, a constant potential method under a three-electrode system is used, wherein the three electrodes are a glassy carbon electrode with a thiophene-based conductive polymer film as the working electrode, a platinum sheet as the counter electrode, and a reference electrode selected from either a saturated mercurous sulfate electrode or a silver / silver chloride electrode. The polymerization conditions are as follows: polymerization is carried out in a potential range of 1V to -1V for 3 to 10 minutes, and the formed metal layer includes one or more alloys of copper, silver, nickel, tin, gold, and palladium.

[0035] Example 1

[0036] Example 1 provides a method for electrosynthesizing polythiophene films in an aqueous solution, comprising the following steps:

[0037] (1.1) Prepare an electrolyte by dissolving thiophene monomer in an aqueous solution containing perchloric acid under magnetic stirring to obtain an aqueous electrolyte;

[0038] The purity of the thiophene monomer used is greater than 99.5%; the molecular formula of the thiophene monomer is as follows:

[0039]

[0040] Preferably, the aqueous electrolyte in step (1.1) contains 5 to 50 mM thiophene monomer and 100 to 500 mM perchloric acid per 100 ml of aqueous solution.

[0041] (1.2) Pre-treat the surface of the working electrode by grinding the electrode surface and removing grease and fingerprint contaminants by ultrasonic and acid pickling.

[0042] Preferably, the working electrode in step (1.2) is a glassy carbon electrode, and its pretreatment steps are as follows: first, polish it with 7000-mesh fine sandpaper for 5 minutes, then polish it on a chamois polishing cloth with 0.05μm alumina polishing powder for 5 minutes, and then sonicate it in ethanol and deionized water for 1 minute in sequence. After that, immerse the working electrode in 3M nitric acid solution for later use.

[0043] (1.3) In a three-electrode system, an aqueous electrolyte prepared in (1.1) is used to electrochemically polymerize the working electrode surface pretreated in (1.2) to form a conductive polythiophene film.

[0044] Preferably, the three electrodes in step (1.3) are a glassy carbon electrode as the working electrode, a platinum sheet as the counter electrode, and a silver / silver chloride electrode as the reference electrode. All electrodes are soaked in 3 mol / L nitric acid before use.

[0045] Preferably, the electrochemical polymerization method in step (1.3) is cyclic voltammetry, which involves 20 cycles of scanning between 0 and 2.5V at a scanning speed of 100mV / s.

[0046] (1.4) Copper deposition was performed on the polythiophene film prepared by (1.3) using a three-electrode system via a constant potential method.

[0047] Preferably, the copper plating solution in step (1.4) consists of a solution of 100 to 200 g / L copper sulfate pentahydrate, 50 to 100 g / L sulfuric acid and 10 to 200 ppm bis-(3-sulfopropyl) disulfide.

[0048] Preferably, the constant potential method in the three-electrode system of step (1.4) uses a glassy carbon electrode with a polythiophene film as the working electrode, a platinum sheet as the counter electrode, and a saturated mercurous sulfate electrode as the reference electrode. The polymerization conditions are: polymerization at a potential of -0.3V to -0.9V for 3 to 10 minutes.

[0049] Example 2

[0050] This embodiment provides a method for electrosynthesizing polythiophene films in an aqueous solution, comprising the following steps:

[0051] Step 1: Preparation of aqueous electrolyte

[0052] Under magnetic stirring, 10 to 100 mM thiophene monomer (purity greater than 99.5%, unpurified, sourced from McLean Company) was dissolved in 100 mL of aqueous solution containing 100 mM perchloric acid to obtain an aqueous electrolyte.

[0053] Step 2: Electrode Pretreatment

[0054] The electrode surface was sanded with 7000-grit sandpaper for 5 minutes, then polished with 0.05μm alumina polishing powder on a chamois polishing cloth for 5 minutes to ensure a smooth and clean surface. After treatment, the electrode was rinsed with deionized water, and then ultrasonically cleaned in ethanol and deionized water for 1 minute each. Finally, the electrode was immersed in 3M nitric acid solution.

[0055] Step 3: Electrochemical Synthesis

[0056] In a three-electrode system (glassy carbon electrode as the working electrode, platinum sheet as the counter electrode, Ag / Ag...), + The electrode is used as a reference electrode. Electrochemical polymerization is performed on the pretreated working electrode surface using the above-mentioned aqueous electrolyte to form a conductive polythiophene film. The electrochemical polymerization is performed using cyclic voltammetry (CV), with 10 to 40 cycles in the potential range of 0 to 2.5 V at a scan rate of 100 mV / s.

[0057] The stability test of the thin film prepared in this embodiment is as follows: Figure 2 As shown, the anodic oxidation curves obtained after one and 100 cyclic voltammetric scans of the polythiophene interface are basically the same, which proves that the prepared polythiophene film has good electrochemical stability.

[0058] Example 3

[0059] This embodiment provides a metallization application of electrosynthesized polythiophene thin films in an aqueous solution, including the following steps:

[0060] Step 1: Electrolyte preparation

[0061] Weigh 100 to 200 g / L of copper sulfate pentahydrate (CuSO4·5H2O) and dissolve it in an appropriate amount of deionized water, stirring thoroughly until completely dissolved. Next, add 50 to 100 g / L of sulfuric acid (H2SO4) to adjust the acidity of the electrolyte and continue stirring until homogeneous. Finally, add 10 to 200 ppm of bis-(3-sulfopropyl)disulfide as an additive for the electroplating process, ensuring complete dissolution. The entire preparation process should be carried out at room temperature to ensure the homogeneity and stability of the electrolyte, ultimately yielding a solution suitable for copper electroplating.

[0062] Step 2: Potentially constant copper deposition

[0063] A polythiophene film was prepared on a glassy carbon electrode using the method described in Example 1. The glassy carbon electrode with the pre-prepared polythiophene (PTh) film was selected as the working electrode. The electrode surface was cleaned to ensure it was free of oil and contaminants. A platinum sheet was used as the counter electrode, and a saturated mercurous sulfate electrode (Hg / Hg2SO4) was used as the reference electrode.

[0064] Connect the three-electrode system to the electrochemical workstation. Add electrolyte to the electroplating tank, ensuring it covers all electrodes. Electrodeposit copper at a constant potential of -0.7V. Maintain this potential and perform the electroplating process for 3 to 10 minutes. After electroplating, remove the working electrodes, rinse with deionized water, and allow them to air dry. At this point, a copper metal layer has been uniformly deposited on the PTh film surface, ready for further characterization and application.

[0065] The time-current curve of metallization of the polythiophene film prepared in this embodiment is as follows: Figure 3 As shown, the comparison before and after metallization is as follows: Figure 4 As shown.

[0066] Example 4

[0067] The difference between this embodiment and embodiment 2 is that the thiophene monomer in embodiment 1 is replaced with 3,4-ethylenedioxythiophene monomer, that is, a poly(3,4-ethylenedioxythiophene) film is formed, and the poly(3,4-ethylenedioxythiophene) is copper-metallized by the same copper plating process as in embodiment 2.

[0068] Example 5

[0069] The difference between this embodiment and embodiment 3 is that the electroplating solution in embodiment 2 is prepared by replacing copper sulfate pentahydrate and sulfuric acid with silver nitrate (AgNO3) and sodium thiosulfate (Na2S2O3), while metallizing the polythiophene film under the same conditions.

[0070] Example 6

[0071] The difference between this embodiment and embodiment 3 is that the electroplating solution in embodiment 2 is prepared by replacing copper sulfate pentahydrate and sulfuric acid with nickel sulfate (NiSO4·6H2O) and nickel chloride (NiCl2·6H2O), while metallizing the polythiophene film under the same conditions.

Claims

1. A metallization application of a conductive polymer thin film, characterized in that: Thiophene-based conductive polymer films synthesized in aqueous solution are metallized in copper plating bath using a potentiostatic method in a three-electrode system, forming a metal layer deposition on the film surface. The thiophene derivative monomers used in the electrolyte for the electrosynthesis of thiophene-based conductive polymer films in aqueous solution have a purity greater than 99.5%; the molecular formula of thiophene and its derivative monomers, C4H3S−R, is as follows: R is selected from hydrogen, chlorine, bromine, methyl, ethyl, hydroxyl, and thiol groups, and the concentration of thiophene derivative monomers is 5 to 50 mM. The copper plating solution consists of a solution of 100 to 200 g / L copper sulfate pentahydrate, 50 to 100 g / L sulfuric acid, and 10 to 200 ppm bis-(3-sulfopropyl) disulfide.

2. The metallization application according to claim 1, characterized in that: The potentiostatic method under a three-electrode system, wherein the three electrodes are a glassy carbon electrode with a thiophene-based conductive polymer film as the working electrode, a platinum sheet as the counter electrode, and a reference electrode selected from either a saturated mercurous sulfate electrode or a silver / silver chloride electrode. The polymerization conditions are to polymerize for 3 to 10 minutes in the potential range of 1 V to -1 V.

3. The metallization application according to claim 1, characterized in that... The method for preparing thiophene-based conductive polymer films by electrosynthesis in aqueous solution includes the following steps: (1.1) Prepare an electrolyte by dissolving one or more of thiophene and its derivative monomers in an acidic aqueous solution under magnetic stirring to obtain a homogeneous aqueous electrolyte; (1.2) Electrochemical synthesis of conductive polymer films: In a three-electrode system, using the aqueous electrolyte prepared in (1.1), thiophene or thiophene-based conductive polymer films are electrochemically polymerized on the surface of the working electrode by cyclic voltammetry.

4. The metallization application according to claim 3, characterized in that, The acidic solution in the aqueous electrolyte component described in step (1.1) is composed of one or more of hydrochloric acid, nitric acid, sulfuric acid, and perchloric acid, as well as one or more water-soluble metal salts corresponding to such acids, wherein the acid concentration is 100 to 500 mM and the concentration of thiophene and its derivative monomers is 5 to 50 mM.

5. The metallization application according to claim 3, characterized in that, In step (1.2), the three electrodes are a glassy carbon electrode as the working electrode, a platinum sheet as the counter electrode, and a silver / silver chloride electrode as the reference electrode. The pretreatment steps for the glassy carbon electrode are as follows: sanding with fine sandpaper, polishing with chamois cloth, ultrasonic cleaning with ethanol and deionized water, and then immersing the working electrode in nitric acid solution for later use.

6. The metallization application according to claim 3, characterized in that, The electrochemical polymerization method in step (1.2) is cyclic voltammetry, which involves cyclically scanning between 0 and 2.5 V for 10 to 40 cycles to achieve the synthesis of conductive polymers.

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