JP2566881B2 - Electroactive polymer - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel conductive polymer.

[0002]

Polymers used to form conductive polymers include polyacetylene, polyparaphenylene,
Polythiophene, polypyrrole and the like are known. These polymers can be used as a conductive polymer by doping a certain compound, but they have the drawback that they are easily denatured in the air and their electrical characteristics change. Also,
These conductive polymers have problems such as poor workability due to poor melting and solubility, which is a major obstacle to practical use. For example, as an application field of conductive polymers, application to secondary battery electrodes utilizing the reversible redox properties of conductive polymers has been proposed. It is physically or chemically unstable, and therefore stable charging / discharging repeatability (cyclability), which is the basic performance required for secondary batteries, cannot be expected. Further, since the polymer skeleton of the conductive polymer is made of a rigid π-electron conjugated system, it is insoluble and infusible, which is a major obstacle to practical use. As a method for solving these problems, in JP-A-61-206170, an electroactive polymer obtained by doping a polymer having a 4,4'-diphenylamine structure as a repeating unit with an electron acceptor or an electron donor is disclosed. It has been proposed to use it as an electrode material for secondary batteries.

[0003]

However, the above-mentioned diphenylamine-based polymer is an oligomer having a low degree of polymerization and does not have the mechanical strength and moldability originally required to be provided as a polymer compound. When it is used as an electrode material of a secondary battery, soluble components are eluted as it is repeatedly charged and discharged, and there is a problem that cyclability cannot be expected. Further, in order to impart good electrochemical properties, mechanical strength and moldability to the above diphenylamine polymer, a polymer having a higher degree of polymerization (high polymer)
It is necessary to obtain a high molecular weight polymer by Grignard coupling, oxidative coupling, Friedel-Crafts reaction and electrolytic oxidative polymerization that are generally used as a synthetic method for polyaromatic compounds and polyheteroaromatics. It is difficult to obtain, and even if the reaction conditions are made more severe, it is not possible to expect a high molecular weight by inducing a heterologous bond or a cross-linking reaction. There is a problem that the polymer becomes infusible and becomes an electrically inactive polymer, and improvement has been desired.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a novel polymer, and more particularly to a conductive polymer which has solved the conventional problems. That is, the invention has the general formula (I)

[0005]

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(Wherein R ¹ represents H or a hydrocarbon residue having 1 to 20 carbon atoms, R ² represents H, a hydrocarbon residue having 1 to 20 carbon atoms, a furyl group, a pyridyl group or a methoxyphenyl group. , N and x represent an integer of 2 or more), which is an electroactive polymer obtained by doping an electron acceptor into a copolymer represented by the formula:

The copolymer represented by the general formula (I) of the present invention comprises a polymer represented by the general formula (II) having a 4,4'-diphenylamine structure as a repeating unit and a copolymer represented by the general formula (III). It can be easily produced by polycondensation with the represented aldehyde or a polymer thereof.

[0008]

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The polymer having the 4,4'-diphenylamine structure represented by the general formula (II) as a repeating unit is, for example, the oxidation used in JP-A-61-206170 or JP-A-61-28524. It can be synthesized by a known method such as a coupling method or a Grignard coupling method. In the general formula (I), R ¹ represents hydrogen or a hydrocarbon residue having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and as the hydrocarbon residue, a methyl group, an ethyl group, an n-propyl group, i- A propyl group, an n-butyl group, an i-butyl group, an n-hexyl group or an allyl group,
Further, various aryl groups such as phenyl group, tolyl group, ethylphenyl group, aralkyl group and derivatives thereof can be exemplified. Further, n is 2 or more, but is usually 2 to 10, preferably 2 to 8.

Further, as the aldehyde represented by the general formula (III), R ² is hydrogen or has 1 to 20 carbon atoms,
Preferably, 1-8 hydrocarbon residue, or a compound of furyl group, pyridyl group, methoxyphenyl group is used, and as the hydrocarbon residue, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group,
An n-hexyl group or an allyl group, various aryl groups such as a phenyl group, a tolyl group, an ethylphenyl group, an aralkyl group and derivatives thereof can be used.
Typical examples of these aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, acrylaldehyde, cinnamaldehyde, anisaldehyde, nicotinaldehyde and furfural.

The aldehyde polymer means a polymer obtained by subjecting the aldehyde represented by the general formula (III) to a concentrated solution for self-condensation or condensation in the presence of an acid catalyst. The term “combined” refers to a compound that is easily hydrolyzed to produce an aldehyde monomer under the reaction conditions for synthesizing the copolymer of the present invention. Typical examples include paraformaldehyde, which is a polymer of aldehyde, and paraaldehyde, which is a trimer of acetaldehyde.

The polycondensation of the diphenylamine polymer and the aldehyde can be carried out in an organic solvent in which both are soluble at a temperature of 0 ° C. to 200 ° C. using an acid or alkali catalyst. Examples of acid catalysts include inorganic acids such as sulfuric acid, hydrochloric acid and phosphoric acid, and organic acids such as formic acid, acetic acid and propionic acid. Examples of preferable organic solvents include ethers such as ethyl ether, tetrahydrofuran and dioxane, halogenated hydrocarbons such as chloroform, dichloromethane and chlorobenzene, nitro compounds such as nitrobenzene, acetonitrile, propylene carbonate, dimethylformamide and N-methyl. Examples include pyrrolidone. The reaction time can be appropriately selected within the range of 1 minute to 100 hours, preferably 5 minutes to 24 hours.

The thus obtained copolymer represented by the general formula (I) has x of 2 or more, usually 2 to 1000, preferably 5 to 200, and has a substantially linear structure.

This copolymer is soluble in solvents such as N-methylpyrrolidone, nitrobenzene and sulfuric acid, but insoluble in alcohols, hydrocarbons, acetonitrile and propylene carbonate used in organic electrolyte type batteries, and heated. It is a thermoplastic resin that can be melted by means of, is excellent in workability, and can be formed into various shaped articles of any shape.

This copolymer exhibits high electric activity by doping with an electron acceptor as a dopant and can carry out the redox reaction with good repeatability. Therefore, when it is used as an electrode material of a secondary battery, for example. Reversible charge and discharge is possible, and even if the number of charge and discharge repetitions (cycle number) is remarkably increased, the elution phenomenon may occur and the cyclability may deteriorate as seen in the case of diphenylamine polymer. It is possible to obtain extremely stable characteristics.

As the electron accepting dopant, iodine,
Bromine, halogen compounds such as hydrogen iodide, arsenic pentafluoride, phosphorus pentachloride, phosphorus pentafluoride, antimony pentafluoride,
Such as silicon tetrafluoride, aluminum chloride, aluminum bromide, aluminum fluoride, metal halides such as ferric chloride, sulfuric acid, nitric acid, protic acid such as chlorosulfonic acid, sulfur trioxide, difluorosulfonyl peroxide, etc. Examples of suitable oxidizing agents include organic substances such as tetracyanoquinodimethane. Further, as a dopant that can be electrochemically doped, PF ₆ ⁻ , SbF
₆ ^-, AsF ₆ ^- Va metal selected halide anions, such as, BF ₄ ^- IIIa metal selected halide anions, such ^{_{as, I - (I 8 -)}} , Br -, Cl - halogens, such as Examples include anions and anions such as perchlorate anions such as ClO ₄ ⁻ .

Further, since the above-mentioned copolymer has a property that the nitrogen atom in the polymer becomes positively charged and becomes stable when doped with an anion, it is stable against repeated redox and processability. It is used to form various functional electrodes such as batteries by utilizing the property of good performance. That is,
Molding is carried out using a solution of the above copolymer dissolved in a solvent, molding is carried out by heating and melting, or pressure molding is carried out using the copolymer as a main component, and polytetrafluoroethylene is used as a binder. , Polyvinylidene fluoride, polyvinyl chloride,
Examples thereof include polyethylene, but are not necessarily limited thereto.

[0018]

The copolymer, which is the precursor of the electroactive polymer of the present invention, is linear and therefore has excellent workability, and various molded products can be easily produced. And by doping this copolymer with an electron acceptor, it is possible to express high conductivity, and further, the doping is reversible and has extremely high cyclability,
Excellent as a conductive polymer.

[0019]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1 (Synthesis of N-methyldiphenylamine polymer) 300 m
Into a three-necked flask, place 50.0 g of anhydrous FeCl ₃
After adding and dissolving 150 ml of ethanol, 18.
4 g of N-methyldiphenylamine was added and the reaction was carried out at room temperature for 24 hours with stirring in a nitrogen atmosphere. The blue-green precipitate formed after the reaction was filtered, washed with ethanol and ion-exchanged water, washed again with ethanol, and then dried.
2.1 g of a blue solid was obtained.

The obtained solid was further dissolved in 200 ml of dichloromethane and filtered, and the filtrate was recovered to remove dichloromethane and then dried to obtain N-soluble in dichloromethane.
11.6 g of a methyldiphenylamine polymer was obtained.

The obtained N-methyldiphenylamine polymer was an oligomer of N-methyldiphenylamine having a polymerization degree of 2 and 3 with main peaks detected at mass numbers of 364 and 545 from the result of mass spectrometry. In addition, the infrared absorption spectrum was measured to obtain 82 derived from para-substituted benzene.
Since the absorption at 0 cm ⁻¹ was observed, it was found that this polymer had a structure in which it was linked at the para position of the phenyl group of N-methyldiphenylamine.

(Polycondensation of N-methyldiphenylamine polymer and propionaldehyde) 2.0 g of the above N-methyldiphenylamine polymer was placed in a 300 ml three-necked flask and dissolved in 40 ml of 1,4-dioxane. After 0.38 g of propionaldehyde dissolved in 0.5 ml of concentrated sulfuric acid and 20 ml of 1,4-dioxane was added dropwise thereto, the mixture was heated and stirred at 85 ° C. for 3 hours to be reacted. After the reaction,
The reaction solution was poured into 200 ml of ethanol, the precipitate was filtered, washed with acetonitrile and then dried to obtain 0.73 g of a blue polymer. The obtained polymer was soluble in N-methylpyrrolidone and nitrobenzene, but insoluble in acetonitrile, propylene carbonate, dichloromethane and hydrocarbons.

The result of measuring the infrared absorption spectrum is shown in FIG.
Shown in The absorption derived from the para-substituted benzene at 820 cm ⁻¹ strongly appeared, and at the same time, 700 cm was observed in the infrared absorption spectrum of the N-methyldiphenylamine polymer.
It was found that the absorption derived from the mono-substituted benzenes at ⁻¹ and 750 cm ⁻¹ was significantly reduced and polycondensation with the aldehyde occurred at the para position of the terminal phenyl group of the N-methyldiphenylamine polymer.

This polymer was pressure-bonded onto a platinum mesh to prepare a measuring electrode. As an electrolytic solution, 0.07 mol / l (n
-C ₄ H _{9) 4} acetonitrile NClO _4, platinum plate as a counter electrode, a reference electrode with a Ag / AgNO ₃ electrode in a dry nitrogen atmosphere was measured cyclic voltammetry of the above electrodes. Sweep speed is 50 mV / sec
Was used. The obtained results are shown in FIG. It showed reversible and extremely stable redox behavior with no change even after several tens of redox cycles. The redox potential is 0.40 VVS.
It was Ag / AgNO ₃ .

Example 2 A reaction was carried out in the same manner as in Example 1 except that N-ethyldiphenylamine was used in place of N-methyldiphenylamine and a 37% formaldehyde aqueous solution was used in place of propionaldehyde. Using 20.0 g of N-ethyldiphenylamine, 12.6 g of N
-Ethyldiphenylamine polymer was obtained. Further, 2.0 g of this polymer and 0.85 g of 37% aqueous formaldehyde solution were subjected to polycondensation reaction at room temperature for 4 hours to obtain 16.3 g of N 2.
A polycondensation reaction product of an ethyldiphenylamine polymer and formaldehyde was obtained. x is about 70.

Cyclic voltammetry measurement as in Example 1 except that the above polymer was used instead of the polycondensation reaction product of the N-methyldiphenylamine polymer and propionaldehyde in Example 1. I went. FIG. 3 shows the obtained results. It showed reversible and extremely stable redox behavior. Redox potential is 0.41VV
S. It was Ag / AgNO ₃ .

Example 3 The reaction was performed in the same manner as in Example 1 except that 0.66 g of benzaldehyde was used instead of propionaldehyde. After purification, 0.41 g of polycondensation reaction product was obtained.

Cyclic voltammetry measurement as in Example 1, except that the above polymer was used instead of the polycondensation reaction product of the N-methyldiphenylamine polymer and propionaldehyde in Example 1. I went. The obtained results are shown in FIG. It showed reversible and extremely stable redox behavior. Redox potential is 0.40VV
S. It was Ag / AgNO ₃ .

Example 4 A reaction was carried out in the same manner as in Example 1 except that 0.41 g of paraaldehyde was used instead of propionaldehyde. After purification, 0.87 g of polycondensation reaction product was obtained. A polymer doped with this polymer by a conventional method showed high electroactivity.

Example 5 A reaction was carried out in the same manner as in Example 1 except that 0.30 g of acetaldehyde was used instead of propionaldehyde in Example 1. After purification, 0.81 g of polycondensation reaction product was obtained. A polymer doped with this polymer by a conventional method showed high electroactivity.

[Brief description of drawings]

1 is an infrared absorption spectrum chart of the copolymer obtained in Example 1. FIG.

FIG. 2 shows measurement results of cyclic voltammetry of electrodes in Example 1.

FIG. 3 shows measurement results of cyclic voltammetry of electrodes in Example 2.

FIG. 4 shows measurement results of cyclic voltammetry of electrodes in Example 3.

Claims (1)

(57) [Claims] 1. A compound of the general formula (In the formula, R ¹ represents H or a hydrocarbon residue having 1 to 20 carbon atoms, R ² represents H, a hydrocarbon residue having 1 to 20 carbon atoms, a furyl group, a pyridyl group or a methoxyphenyl group, and n and x represents an integer of 2 or more), which is an electroactive polymer obtained by doping a copolymer represented by the formula (1) with an electron acceptor.