JPH072832B2 - Method for electrolytic polymerization of pyrrole - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for obtaining polypyrrole useful as a conductive material in the form of a thin film having good mechanical properties. More specifically, the present invention relates to a method for obtaining a polypyrrole having improved mechanical strength and stability during conduction by using a specific electrolyte when producing polypyrrole from pyrrole by electrolytic polymerization. .

[0002]

2. Description of the Related Art In recent years, various organic conductive polymer compounds have been developed as new conductive materials, and research for practical use in the electronic industry field has been conducted. As such an organic conductive polymer compound, a polyacetylene-based polymer compound, a polyphenylene-based polymer compound,
Polypyrrole polymer compounds, polythiophene polymer compounds, polyselenophene polymer compounds, etc. are known.

These polymer compounds are usually produced by dehalogenative condensation of a halogenated derivative or electrolytic polymerization. In the case of a five-membered ring polymer compound such as polythiophene or polypyrrole, it is film-like and stable. A manufacturing method by electrolytic polymerization is advantageous because it has the advantage of being formed in a shape.

By the way, the electrolytic polymerization of pyrrole has hitherto been carried out by electrolytically oxidizing pyrrole in an appropriate solvent in the presence of an electrolyte such as a quaternary ammonium salt. There was a problem in terms of mechanical strength, and it was unavoidable that its range of use was limited.

[0005]

The object of the present invention is to obtain a polypyrrole thin film having excellent physical properties by selecting a specific compound as an electrolyte to be used during polymerization when producing polypyrrole by electrolytic polymerization. It was made.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted various studies on the electrolytic polymerization of pyrrole, and as a result, by using a specific aromatic compound polymer as an electrolyte to be added to an electrolytic solution, It has been found that a polypyrrole thin film having improved mechanical properties can be obtained, and the present invention has been completed based on this finding.

That is, according to the present invention, when electrolytically polymerizing pyrrole in a medium containing an electrolyte to produce polypyrrole, a salt of an aromatic ring compound polymer having a carboxyl group directly bonded to a ring is used as an electrolyte. The present invention provides a method for electrolytic polymerization of pyrrole, characterized by using.

The electrolysis in the method of the present invention can be carried out in a medium consisting of water or other polar solvent in the presence of a specific electrolyte under the conditions usually used in the electropolymerization of organic conductive polymer compounds. .

As the anode in the method of the present invention, an electrode which does not participate in redox, for example, an electrode formed of a noble metal such as platinum, an electrode formed of a conductive glass such as indium-tin oxide glass, is used. As a cathode,
An electrode made of iron, carbon, aluminum, gold, platinum, conductive glass or the like is used.

In the method of the present invention, the current density is usually 0.1 to 2
It is carried out under the conditions of 0 mA / cm ² and reaction temperature of -10 to 60 ° C, preferably 0 to 40 ° C.

In the method of the present invention, it is necessary to use a salt of a polymer of an aromatic ring compound having a carboxyl group directly bonded to the ring as the electrolyte. Here, the aromatic ring compound is a chemical compound containing a delocalized π-electron having a planar five- or six-membered carbocyclic or heterocyclic ring, such as a benzene ring, a thiophene ring, a furan ring, or a pyridine ring. It has a structure and has a characteristic peculiar to an aromatic compound.

The polymer of the aromatic ring compound used in the method of the present invention has a salt type carboxyl group directly bonded to the ring. Examples of such a compound include poly (thiophene-3-carboxylic acid). Acid), poly (furan-3-carboxylic acid), poly-benzoic acid and other alkali metal salts, ammonium salts and the like.

Such a compound is obtained by, for example, subjecting a carboxylic acid ester having an aromatic ring substituted by two halogen atoms to condensation polymerization using a nickel catalyst, and then hydrolyzing the obtained polymer with an alkali. It can be manufactured by decomposing.

In the method of the present invention, the salt of the polymer of the aromatic ring compound thus obtained is used in an amount of 1 to 80 g /
l, preferably 5 to 50 g / l in the medium and electrolyzed.

In this way, polypyrrole is formed on the surface of the anode plate as a reddish brown film having a film thickness of 5 μm or more.

[0016]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

Reference Example 1 Argon gas was flowed in a 50 ml three-necked flask equipped with a funnel with a side tube, a thermometer, and a stirrer for 1 hour to replace the gas.
NiBr2 (0.1 mol, 0.438 g), triphenylphosphine (0.76 mol, 4.0 g) and zinc (3.1 mol, 40 g) were dissolved in 10 ml of dimethylformamide and heated to 50 ° C and stirred.

After the color of the solution changed to reddish brown, another 3
The nickel catalyst was prepared by stirring for 0 minutes. Then, a solution of methyl 2,5-dichlorothiophene-3-carboxylate (1 mol, 4.22 g) dissolved in 10 ml of dimethylformamide placed in a funnel with a side tube was added dropwise at 30 ° C. at 60 ° C.
Reacted for hours. After completion of the reaction, the reaction solution was poured into a solution of methanol: hydrochloric acid = 9: 1 (180 ml: 20 ml) and then filtered. A Soxhlet extractor was used to remove the methanol-soluble matter from the reaction product, and the product was extracted all day and night for purification to obtain 1.56 g (56%) of a brown polymer.

The poly (methyl thiophene-3-carboxylate) thus obtained was soluble in chloroform, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, chlorobenzene and the like. The structure of poly (methyl thiophene-3-carboxylate) was confirmed from the infrared absorption spectrum. The degree of polymerization by GPC (gel permeation chromatography) was 18.

Next, 530 mg of poly (methylthiophene-3-carboxylate) was added to 0.5 N NaOH (NaOH:
0.4 g, 20 ml H2O) was reacted at 60 ° C. for 4 hours to obtain poly (sodium thiophene-3-carboxylate), precipitated with methanol, and purified by filtration.

Reference Example 2 2,5-Dichlorothiophene-3 under the same conditions as in Reference Example 1
-Polymerized with ethyl 2,5-dichlorobenzoate (0.1 mol, 4.38 g) instead of methyl carboxylate gave a gray poly (phenylenecarboxylate)
2.98 g (100%) was obtained.

G of this polymer in tetrahydrofuran
The degree of polymerization measured by PC was 34.

Poly (ethyl paraphenylenecarboxylate)
0.25 g of 1N NaOH (NaOH: 0.8 g, H
2O: 20 ml) was reacted at 60 ° C. for 5 hours to obtain poly (sodium paraphenylenecarboxylate). Methanol was added to precipitate and filter to purify.

Example 1 In a one-chamber structure cell under an argon atmosphere, an indium-tin oxide conductive glass was used as a working electrode, and a platinum plate was used as a counter electrode.
Pyrrole (0.1 mol, 67 mg) and poly (sodium thiophene-3-carboxylate) 27 mg (5 x 10
-4 mol) in 10 ml of distilled water,
The reaction was carried out at a current density of 0.2 mA / cm 2 for 1 hour to obtain a reddish brown film having a film thickness of 9.0 μm on the working electrode. This film was washed with n-hexane and dried, and then the electrical conductivity was measured by the four-terminal method, and it was 0.06 S / cm. PH at this time (by Toyo pH test paper Cresol Red)
Was about 7.4.

Example 2 In the same manner as in Example 1, instead of poly (sodium thiophene-3-carboxylate), 26 mg (5 × 10 −4 mol) of poly (sodium paraphenylenecarboxylate) was added, and
When reacted at a current density of 2 mA / cm2 for 1 hour,
A black film having a film thickness of 7.6 μm was obtained, and the electric conductivity of this film was 0.24 S / cm. P at this time
H was about 8.0.

Comparative Example 1 Under the same conditions as in Example 1, the polymerization was carried out without adding poly (sodium thiophene-3-carboxylate), but no current flowed between the electrodes, and the polymerization could not be carried out.

Comparative Example 2 Under the same conditions as in Example 1, poly (methyl thiophene-3-carboxylate) was replaced by poly (methyl thiophene-3-carboxylate) and polymerized. This was insoluble in water. Therefore, no current flowed between the electrodes and the polymerization was not possible.

Comparative Example 3 Under the same conditions as in Example 1, poly (ethyl paraphenylenecarboxylate) was added instead of poly (sodium paraphenylenecarboxylate) to polymerize, but this was insoluble in water and was between the electrodes. The current did not flow and the polymerization could not be performed.

[0029]

According to the present invention, polypyrrole useful as a conductive material can be produced as a film having good mechanical properties and stability in a conductive state.

Claims (3)

[Claims] 1. In producing polypyrrole by electrolytically polymerizing pyrrole in a medium containing an electrolyte, it is preferable to use a salt of an aromatic ring compound polymer having a carboxyl group directly bonded to a ring as the electrolyte. A method for electrolytically polymerizing pyrrole. 2. The method according to claim 1, wherein the salt of the aromatic ring compound polymer having a carboxyl group directly bonded to the ring is an alkali metal salt of poly (phenylenecarboxylic acid). 3. The method according to claim 1, wherein the salt of the aromatic ring compound polymer having a carboxyl group directly bonded to the ring is an alkali metal salt of poly (thiophenecarboxylic acid).