JPH029620B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a conductor made of a polymer. In particular, the present invention relates to a method for producing polymers with high chemical stability and excellent conductivity, which are used as electrodes, batteries, display elements, and various sensor materials. Prior Art Organic polymer compounds are generally insulators, but recently it has been known that they can be made into semiconductors or conductors by adding certain impurities (hereinafter referred to as dopants). The possibility of applying these polymers to electronic materials, batteries, etc. by combining them with various semiconductors as P-type or N-type semiconductors is being studied depending on the selection of dopants. Polyacetylene is the most actively studied representative of these polymers. However, since polyacetylene lacks stability even in air, it is difficult to apply it practically. However, polymers having five-membered heterocycles as repeating units, such as polythiophene and polypyrrole, have attracted attention because of their high electrical conductivity and good stability in air. Conventionally, polythiophene was synthesized by the Grignard method using 2,5-dibromothiophene as a raw material in the presence of a nickel catalyst (J. Polym.
Sci., Polym. Lett. Ed., vol. 18, p. 9 (1980)).
However, the resulting polymer was powdery and had the disadvantage of poor processability. However, a method has been developed to produce a polypyrrole film that has high electrical conductivity and is stable in air by polymerizing pyrrole using an electrolytic polymerization method in the presence of a supporting electrolyte such as tetraethylammonium tetrafluoroborate (J .Chem.SOC.Chem.Commum.1979, p. 854). Similarly, it was developed to polymerize thiophene using an electrolytic polymerization method to produce electrically conductive polythiophene that is stable in air (J.Electroanal
Chem. vol. 135, p. 173 (1982)). These electrolytic polymerization methods are more efficient than chemical polymerization methods such as the Grignard method.
This method is excellent in that a polymer film that is advantageous in applications can be easily obtained. However, the current efficiency of producing polythiophene and polypyrrole by electrolytic polymerization is as low as about 40%, and the polymerization positions of these are at the 2nd and 5th positions.
There were problems in that not only the position but also the 3rd or 4th position were involved in polymerization, resulting in structural disorder and low crystallinity. Purpose of the Invention The present invention was made to solve the problems in conventional methods for producing conductive polymers.The purpose of the present invention is to produce conductive polymers that have high current efficiency and have regularly bonded monomers by electrolytic polymerization. An object of the present invention is to provide an excellent method for producing a polymerizable polymer. Structure of the Invention As a result of research to achieve the above object, the present inventor has
When a thiophene oligomer is used as a starting material and polymerized by electrolytic polymerization, the current efficiency is high and the resulting polymer is easily formed into a highly crystalline polymer with regular bonds only at the 2- and 5-positions. I was able to find out what I could get. The present invention was completed based on this knowledge. The gist of the present invention is a method for producing a conductive polymer, which is characterized by polymerizing a thiophene oligomer by an electrolytic polymerization method. This basic manufacturing method will be described in detail. A thiophene oligomer is dissolved or dispersed in a solvent together with a supporting electrolyte, and the polymer is electrochemically polymerized at a constant voltage or current. Examples of thiophene oligomers include α-terthienyl, α-quarterthienyl, α-quinquinthienyl, α-sexithienyl, 2,2′-
Examples thereof include dithienyl-diacetylene and 2,2'-dithienyl-NR-pyrrole (R represents hydrogen, an aliphatic group, an alicyclic group or an aromatic group). As the supporting electrolyte, a salt represented by the general formula A ⁺ B ^- is used. In the formula, A ⁺ is H ⁺ , alkali metal ion, alkaline earth metal ion, R ₄ N ⁺ ,
Represents cations such as R ₄ P ⁺ , NO ⁺ , NO ₂ ⁺ . In addition, R in the above formula represents a hydrogen atom aliphatic, alicyclic or aromatic group. ) B ^- is ClO ^- ₄ , BF ^- ₄ , PF ^- ₆ , SbF ^- ₆ , SpCl ^- ₆ ,
AsF ^- ₆ , SO ^2- ₄ , HSO ^- ₄ , CF ₃ SO ^- ₃ , CH ₃ COO ^- ,
Represents anions such as C ₆ H ₅ SO ^- ₃ and tosylate. The supporting electrolyte is used at a concentration of 0.01 to 10 molar per solvent, and the thiophene oligomer is used at a concentration of 0.01 to 10 molar per solvent.
Use at 0.001-10 molar concentrations. The solvent is preferably one that can dissolve or disperse the thiophene oligomer and the supporting electrolyte. For example, ethanol, methanol, tetrahydrofuran, 1,4-dioxane, acetone, acetonitrile, propionitrile, benzonitrile, pyridine, formamide, dimethylformamide, dimethylacetamide, hexanephosphorotriamide, N-methyl-2-pyrrolidone, dimethylsulfoxide. , sulfolane, 1,2-dichloroethane, propylene carbonate, or a mixture thereof. The electrolytic polymerization reaction is generally preferably carried out under an inert atmosphere such as nitrogen or argon. The reaction temperature may be any temperature as long as it is not lower than the solidification temperature of the electrolytic solution or lower than its boiling point temperature. Generally it is -10 to 50°C. Reaction time is 1 minute to 20 hours, preferably 10 minutes to 60 hours.
It's a minute. Voltage is 0.1-25V, preferably 1-15V
The additive density is 0.05 to 50 mA/cm ² , preferably 0.1
~20mA/ ^cm2 . As the electrode, a plate or mesh electrode made of platinum, gold, chromium, copper, or nickel, or an air electrode (ITO) coated with a thin film of tin or indium oxide can be used. When depositing a thin film of polymer thereon, these preferably have smooth surfaces. Depending on the type of supporting electrolyte and solvent used, the polymer may be obtained in the form of a film, powder, or gel. Therefore, by changing the conditions, the physical properties or morphology of the polymer can be controlled as desired. For example, when a solvent such as N-methyl-2-pyrrolidone, nitrobenzene, or benzonitrile is used, a film-like polymer is obtained. Furthermore, when acetonitrile, nitromethane, or tetrahydrofuran is used as a solvent, a powdery polymer can be obtained. When H ₂ SO ₄ is used as the supporting electrolyte, a gel-like polymer is obtained regardless of the solvent used. The polymer production efficiency is over 70%, which is significantly higher than about 40% in conventional methods. It is difficult to chemically dope polypyrrole and polythiophene obtained by conventional electrolytic polymerization methods with dopants. On the other hand, the polymer obtained by the method of the present invention can be easily chemically doped with various dopants. Examples Example 1 Into a glass container purged with inert gas, 0.10 g of α-terthienyl (0.01 molar concentration), 1.1 g of tetrabutylammonium perchlorate (0.1 molar concentration), and 30 ml of N-methyl-2-pyrrolidone were placed. ,
Stir and dissolve. Argon gas was blown into this for 15 minutes to remove dissolved oxygen. Using a platinum electrode as the cathode and an ITO electrode as the anode,
Electrolysis was carried out for 30 minutes at a constant current of 1 mA/cm ² . A film-like polymer with a thickness of approximately 10 μm and a metallic luster was formed on the anode. The obtained film was peeled off from the electrode, thoroughly washed with N-methyl-2-pyrrolidone, further washed with methanol, and kept at 30°C for 24 hours.
It was vacuum dried. Current efficiency is 70% and crystallinity is 10
It was %. The IR spectrum of a polymer contains 2,
Absorption specific to 5-disubstituted thiophene ring is 690, 790
cm ^-1 and was confirmed to be a polymer with regular bonds at the 2 and 5 positions. On the other hand, in both polythiophenes polymerized by the conventional Grignard method and the electrochemical method, absorption based on bonds not only at the 2 and 5 positions but also at the 3 and 4 positions was observed. A four-terminal electrode was applied to the film-like polymer using silver paste, and the conductivity was measured using a constant current power source and a digital voltmeter. The results are shown in Table 1. Table 1 Film 1.0×10 ^-8 Scm ^-1 Powder 1.2×10 ^-2 Gel 2.0×10 ^-2 The powder and gel were made by changing the electrolytic polymerization conditions. Even when the obtained polymer film was left in the air for 6 months, its electrical and chemical properties did not change at all. Example 2 Using a reaction vessel in the same manner as in Example 1, 0.10 g of α-terthienyl (0.01 molar concentration) and 1.1 g of tetrabutylammonium perchlorate (0.1 molar concentration) were added.
was dissolved in 30 ml of acetonitrile. A polymer was produced in the same manner as in Example 1. The obtained polymer was a powdery polymer with a black border. The conductor was 1.2×10 ^-2 Scm ^-1 , current efficiency was 80%, and crystallinity was 40%. The IR spectrum confirmed that the polymer was correctly bonded at the 2 and 5 positions. Example 3 α-terthienyl 0.10g (0.01 molar concentration),
0.34 g (0.1 molar concentration) of H ₂ SO ₄ in acetonitrile
Dissolved in 30ml. Using this, a polymer was produced in the same manner as in Example 1. The obtained polymer was a dark green gel-like polymer. Current efficiency is 85%, conductivity is 5.4×10 ^-4 Scm
^-1 , and the crystallinity was 27%. It was confirmed from the IR spectrum that it was bonded at the 2nd and 5th positions. Example 4 In Example 3, gel polymers were produced by varying the concentration of the supporting electrolyte H ₂ SO ₄ . The electrical conductivity, production efficiency, and crystallinity of the obtained polymer were as shown in Table 2 below.

[Table] Examples 5 to 9 In the same manner as in Example 3, α-quarterthienyl, α-quinquinthienyl, α-sexithienyl, 2,2′-dithienyldiacetylene, 2,2′ were used as raw material oligomers. - A polymer was made using dithienylpyrrole. Its production efficiency and crystallinity were as shown in Table 3.

[Table] Effects of the Invention According to the method of the present invention, the drawbacks of conventional polymer conductor production methods are improved, and in particular, compared to conventional electrolytic polymerization methods, current efficiency is high and monomers are bonded in an orderly manner. However, a polymer with high crystallinity and stability in air can be obtained. Moreover, by controlling the polymerization conditions,
It has an excellent effect of providing film-like, powder-like, and gel-like forms.

Claims (1)

[Claims] 1 α-terthienyl, α-quarterthienyl, α-quaintienyl, α-sexithienyl, 2,2′-dithienyl-diacetylene, and 2,
2'-dithienyl-N-R-pyrrole (R is hydrogen,
Represents an aliphatic group, an alicyclic group, or an aromatic group. )
A method for producing a conductive polymer, comprising polymerizing a thiophene oligomer selected from the following by an electrolytic polymerization method.