JPS6162521A - Production of electrically conductive polymer - Google Patents

Abstract

PURPOSE:To produce an electrically conductive polymer composed of regularly bonded monomers and having excellent electrical conductivity, in high current efficiency, by chemically doping an acceptor dopant, etc. to a polymer prepared by the electrolytic polymerization of a thiophene oligomer. CONSTITUTION:The objective polymer can be prepared by (1) dissolving or dispersing a thiophene oligomer (e.g. alpha-terthienyl) in a solvent (e.g. ethanol) in the presence of a supporting electrolyte (a salt of formula A<+>B<->, etc., and B<-> is ClO4<->, etc.), and carrying out the electrolytic polymerization of the oligo mer under a definite potential (preferably 0.1-25V) or a definite current density (preferably 0.05-50mA/cm<2>), usually in an inert atmosphere (e.g. nitrogen), and chemically doping an acceptor dopant (e.g. H2SO4) or a donor dopant (e.g. lithium naphthalene) to the polymer. USE:Material for electrode, cell, display element, and various sensor, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for producing electrical conductors made from polymers. Especially the electrode, 1! This invention relates to a method for producing a chemically stable polymer with excellent conductivity that is used as a display element and various sensor materials.

BACKGROUND OF THE INVENTION Organic polymer compounds are generally insulators, but it has recently become known that they can be made into semiconductors or conductors by adding certain impurities (hereinafter referred to as dopants).

Depending on the selection of dopants, these polymers can be used as P-type or N-type semiconductors in combination with various semiconductors to produce electronic materials,
The possibility of application to batteries, etc. is being considered.

Polyacetylene is the most actively studied representative of these polymers. However, polyacetylene lacks stability in air, making it difficult to put it into practical use.

However, polymers having five-membered heterocycles as repeating units, such as polythiophene and polypillow kfxE, have attracted attention because of their high electrical conductivity and good stability in air.

Conventionally, polythiophenes are prepared in the presence of a nickel catalyst by 2.
It was synthesized by the Grignard method using 5-dibromothiophene as a raw material (J, POlym.

Sci, Polym, Lett, Ed.
Vol. 18, p. 9 (198033゜) However, the obtained polymer was powdery and had the disadvantage of lacking processability. However, when pyrrole was electrolyzed in the presence of a supporting electrolyte such as tetraethylammonium tetrafluoroborate, A method for producing a film of polypyrrole that has high conductivity and is stable in the air by polymerization was proposed (J, Chem, Soc, Chem, Comm).
um, 1979, p. 854].

Similarly, it was developed to polymerize thiophene by electrolytic polymerization to produce electrically conductive polythiophene that is stable in air (J, ElectroanalCham).
, Vol. 135, p. 173 (1982)).

These electrolytic polymerization methods are superior to chemical polymerization methods such as the Grignard method in that they can easily produce polymer films that are advantageous in terms of application.

However, the current efficiency of producing polythiophene and polypyrrole by electrolytic polymerization is as low as about 40%, and the polymerization positions are not limited to the 2nd and 5th positions.
There are problems in that the 3rd or 4th position also participates in polymerization, resulting in structural disorder and low crystallinity.

Purpose of the Invention The present invention was made in order to solve the problems in the conventional manufacturing method of conductive polymers. An object of the present invention is to provide a method for producing an excellent conductive polymer.

Structure of the Invention The present inventor has achieved the above object.As a result of research, using thiophene oligomer as a starting material and polymerizing by electrolytic polymerization method, the current efficiency is high, and the obtained polymer is It was discovered that highly crystalline polymers with regular bonding only in positions can be easily obtained, and that highly conductive polymers can be produced by chemically doping this polymer with acceptor or donor dopants. did.

The present invention was completed based on this knowledge.

The gist of the present invention resides in a method for producing a conductive polymer, which comprises chemically doping an acceptor or donor dopant into a polymer obtained by polymerizing a thiophene oligomer by electrolytic polymerization.

To explain this basic manufacturing method in detail, thiophene oligomer is dissolved or dispersed in a solvent together with a supporting electrolyte,
Polymerization is carried out electrochemically using constant voltage or constant current.

Examples of thiophene oligomers include α-terchenyl, α-quarterthienyl, α-quincuccinyl, α-sexichenyl, 2,2'-dichenyl-diacetylene, and 2,2'-dichenyl-N-R-virol (R is represents hydrogen, an aliphatic group, an alicyclic group, or an aromatic group).

As the supporting electrolyte, a salt represented by the general formula AB is used. In the formula, A+ is H+, an alkali metal ion, an alkaline earth metal ion, R2H'', R4F''.

Represents cations such as NO+ and NO+2. In addition, R in the above formula represents a hydrogen atom aliphatic, alicyclic or aromatic group. ) B is cto″″, BF; , PF; , SbF″
: , sbc! ;, AsF; +8o4. H8O
; , ay, so; I CH,Coo'''', C6
1(5So″S.

Represents an anion such as tosylate.

The supporting electrolyte is used at a concentration of 0.01 to 10 molar per 11 solvent, and the thio7ene oligomer is used at a concentration of 50.00 molar per 11 solvent.
It is used at a concentration of 1 to 10 molar.

The solvent is preferably one that can dissolve or disperse the thiophene oligomer and the supporting electrolyte.

Examples Eva, ethanol, methanol, tetrahydrofuran, 1,4-dioxane, acetone, acetonitrile, fropionitrile, benzonitrile.

Pyridine, formamide, dimethylformamide.

Dimethylacetamide, hexamethylphosphortriamide, N-methyl-2-viclidone, dimethylsulfoxide, sulfolane, 1,2-dipaa ethane, and propylene carbonate may be used alone or as a mixed solvent 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 one ten
~50°C.

The reaction time is 1 minute to 20 hours, preferably 10 minutes to 60 minutes. Voltage is 0.1-25v, preferably 1-15v
The current density is 0.05 to 50 mVCWI2, and the electrode is a plate or mesh electrode made of platinum, gold, chromium, copper, nickel, etc., or a glass electrode coated with a thin film of tin or indium oxide (ITO). ) etc. can be used. When a thin film of polymer is deposited on it, it is preferable that the surface is smooth.0 The polymer can be used in the form of a film, powder, or gel depending on the type of supporting electrolyte and solvent used. There are things you can get.

Therefore, by changing the conditions, the physical properties or morphology of the polymer can be controlled as desired.

For example, + N-methyl-2-pyrrolidone, nitrope/
When a solvent such as zene or benzonitrile is used, a film-like polymer is obtained. Further, when solvent 1 of acetonitrile, nitrometh/tetrahydrofuran is used, a powdery polymer is obtained.

When H or So4 is used as the supporting electrolyte, a gel-like polymer is obtained regardless of the solvent used.

The polymer production efficiency is 70% or more, 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. In contrast, the polymer obtained by the method of the present invention can be easily chemically doped with a dopant.

The polymer obtained by the method of the present invention is already partially doped during electrolytic polymerization and is electrically conductive, but by further chemically doping with an acceptor or donor dopant, the electrical conductivity can be significantly improved. It has excellent effects.

As the acceptor dopant, for example, H30,
So, I, HF, YeCl + 01, Br2+C12+ HNO3+ HCt,
SbF5+ No BF4 is mentioned.

Examples of donor dopants include Li,
It is selected from Na, K, Rb and Os, and is a mixture of these alkali metals or an alloy thereof, or lithium naphthalene, sodium naphthalene/
, potassium naphthalene, lithium biphenyl, sodium biphenyl, potassium biphenyl, lithium anthracene, sodium anthracene, and potassium anthracene.

When the dopant is a gas, the doping method is carried out by exposing the polymer to the vapor of the dopant under reduced pressure. When the dopant is a solid, the dopant is dissolved in a solvent that can dissolve the dopant, and the polymer is immersed in this solution.Also, when the dopant is a liquid, the polymer is immersed in the dopant. I can do it.

Examples Example 1 In a glass container purged with an inert gas, 0.10 f (0.01 molar concentration) of α-terchenyl and 1.1 mol of tetrabutylammonium perchlorate were placed. (0.1 molar concentration) and 30 d of N-methyl-2-pyrrolidone were added and dissolved with stirring. Argon gas was blown into this for 15 minutes to remove dissolved oxygen.

Using platinum electrode as cathode and ITO electrode as anode, 1mAZ-
2. Electrolysis was carried out for 30 minutes using a constant current. A film-like polymer having a thickness of about 10 μm and having a metallic luster was formed on the anode. The resulting film was peeled off from the electrode.Pin, N-methyl-
After thorough washing with 2-pyrrolidone, further washing with metal and vacuum drying at 30°C for 24 hours. Current efficiency is 7
0%, and the crystallinity was 10%. In the IR spectrum of the polymer, absorptions peculiar to the 2,5-disubstituted thiophene ring were observed at 690 and 790 Cm-', confirming that the polymer was bonded regularly at the 2 and 5 positions.

On the other hand, polythiophenes polymerized by the conventional Grignard method and the electrochemical method have not only the 2nd and 5th positions but also the 3rd positions.
, Absorption based on the bond at the 4-position was also 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.

After measuring the conductivity, it was set in a doping reaction vessel under reduced pressure, H2SO4 vapor was introduced into the reaction vessel, and changes in conductivity were measured. The conductivity increased with the introduction of H2SO4 vapor and became approximately constant after about 24 hours. The results are shown in Table 1.

Table 1 [Conductivity (Scm) During electropolymerization Film after doping 1. Ox 10-88.5 x 10-2
Powder 1.2 x 10-27.0 Gel 2. OX 10-211 Powder and gel polymers were prepared and chemically P-pinged with H2SO4.

Further, even when this polymer film was left in the air for 6 months, its electrical and chemical properties did not change at all.

Example 2 In the same manner as in Example 1, film-like, powder-like, and gel-like polymers were produced using α-terchenyl as a raw material. The polymer was doped with copper and its conductivity was measured. The conductivity reached a constant value about 2 hours after the start of doping. The results are shown in Table 2.

Table 2 Conductivity after doping (Sew) Film 3. OX 10-2 powder? , 9 X 10-2 Gel 0.45 Example 3 In the same manner as in Example 1, film-like, powder-like and gel-like polymers were produced using α-terchenyl as a raw material. This polymer was immersed in a solution of sodium naphthalene in tetrahydrofuran for 24 hours in a glass doping reaction vessel. The obtained product was washed with tetrahydrofuran, dried in vacuum, and the conductivity was measured. The results are shown in Table 3.

Table 3 Conductivity after doping (SCrn) Film 8.5 X 10-2 powder
9.2 x 10-2 gel
0.60 Example 4. ~8° In the same manner as in Example 1, α-quarterthienyl, α-
Quincuchenyl, α-sexichenyl, 2.2'-
A polymer was produced using dichenyl diacetylene and 2,2'-dichenylupyrrole as raw materials.

This polymer was treated with H2SO4 in the same manner as in Examples 1 and 3.
and sodium naphthalene doping.

Table 4 shows the results of measuring the electrical conductivity of the obtained polymer.

4th 9th Conductivity (Scm) α-Quarterthienyl 3.7 0.1
8α-Kleincchenyl 2.5 8.
4X10-2α-sexichenyl 1.0
9.3X10-22.2'-dithenyl diacetylene
0.13 6.8 X 10-22.2'-dichenylpyrrole 9.8 9. OX 10-
2 Effects of the Invention According to the method of the present invention, the drawbacks of conventional polymer conductor manufacturing methods are improved, and in particular, compared to conventional electrolytic polymerization methods, current efficiency is high, monomers are bonded regularly, Highly crystalline products can be easily produced.

By controlling the electrolytic polymerization conditions, the resulting polymer can be formed into any film-like, powder-like, or gel-like form, and the resulting polymer is stable even in the air and has excellent electrical conductivity. It has excellent effects such as:

Claims (1)

[Scope of Claims] 1) A method for producing a conductive polymer, which comprises chemically doping an acceptor or donor dopant into a polymer obtained by polymerizing a thiophene oligomer by electrolytic polymerization. 2) The thiophene oligomer is α-terthienyl, α-quarterthienyl, α-quainthienyl, 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. ) The method for producing a conductive polymer according to claim 1, wherein the conductive polymer is selected from the following. 3) The acceptor dopant is H_2SO_4,
SO_3, I_2, HF, FeCl_3, ICl, Br
_2, Cl_2, HNO_3, HCl, SbF_5, and NO^+BF^-_4. The method for producing a conductive polymer according to claim 1. 4) The donor dopant is selected from Li, Na, K, Rb and Cs, and these alkali metals are directly or alloyed, or lithium naphthalene, sodium naphthalene, potassium naphthalene, lithium biphenyl, The method for producing a conductive polymer according to claim 1, wherein the conductive polymer is prepared as an organic compound salt such as sodium biphenyl, potassium biphenyl, lithium anthracene, sodium anthracene, and potassium anthracene.