JPH0668002B2 - Method for producing electroactive polymer and method for producing copolymer suitable for the production - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel polymer, and more particularly to a method for producing a novel electroactive polymer and its precursor copolymer.

(Prior Art) As a polymer used to form a conductive polymer,
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. In addition, these conductive polymers have problems such as extremely poor processability 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. Is physically or chemically unstable,
Therefore, it is difficult to expect the stable repeatability of charge and discharge (cyclability), which is the basic performance required for secondary batteries. 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, US Pat. No. 4,452,725 proposes an electroactive polymer obtained by doping a polymer having a 3,6-carbazolediyl structure as a repeating unit with an electron acceptor.

(Problems to be Solved by the Invention) However, the above-mentioned carbazole-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 provide the above carbazole-based polymer with good electrochemical properties as well as mechanical strength and moldability, it is necessary to obtain a polymer having a higher degree of polymerization (high polymer). It is also difficult to obtain a high molecular weight polymer by Grignard coupling, oxidative coupling, Fluder-Crafts reaction and electrolytic oxidative polymerization, which are generally used as a synthetic method for aromatic compounds and polyheteroaromatics. Even if the conditions are made more severe, not only is it impossible to expect high molecular weight by inducing heterogeneous bonding or cross-linking reaction, but it is also one of the advantages of polymer compounds that it loses processability and becomes insoluble and infusible. There is a problem that it becomes an active polymer.

Further, a polymer having a repeating unit of 3,6-methylcarbazolylmethylene structure is soluble in an organic solvent, and by doping this polymer with an electron acceptor, the direct current conductivity was 10 ⁻³ S / cm. It has been reported that it exhibits a certain degree of conductivity (Synthetic Metals, 10, p. 281-282 (1985)).

However, the above-mentioned carbazolylmethylene-based polymer does not have reversible doping, that is, reversible redox properties, because doping causes desorption of methylene hydrogen in the polymer main chain. Has drawbacks,
Improvement was desired.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art.

(Means for Solving the Problems) The first invention of the present invention is a polymer having a 3,6-carbazolemediyl structure represented by the following general formula (II) as a repeating unit, and a general formula (III) Is a method for producing a copolymer having a repeating unit represented by the general formula (I), which is characterized by polycondensing an aldehyde represented by the following formula or a polymer thereof.

A second invention of the present invention is a method for producing an electroactive polymer, which comprises doping the copolymer obtained by the above method with an electron acceptor.

The polymer having the 3,6-carbazolediyl structure represented by the general formula (II) as a repeating unit is synthesized by a known method. For example, Journal of Organic Synthesis, Vol. 23, No. 5,
p. 447 (1965), Synthesis of carbazole dimers using various oxidant / solvent systems, P. Beresford et a.
l., J. Chem. Soc. Perkin. I, p276 (1974), a method for synthesizing a carbazole dimer using a dehydrogenation catalyst,
JP-A-61-141725 or JP-A-56-88
There are methods such as the oxidative coupling method or Grignard coupling method used in No. 422. General formula
In (II), R ¹ represents hydrogen or a hydrocarbon residue having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and examples of the hydrocarbon residue include a methyl group, an ethyl group, an n-propyl group, and an i-propyl group. , N-butyl group, i-butyl group, n-hexyl group or allyl group, and various aryl groups such as phenyl group, tolyl group, ethylphenyl group, aralkyl group and derivatives thereof. n is 2 or more, but usually 2
50, preferably 2 to 30.

Examples of the aldehyde represented by the general formula (III) include R in the formula
² is hydrogen or a hydrocarbon residue having 1 to 20, preferably 1 to 8 carbon atoms, or a compound having a furyl group, a pyridyl group or a 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, n-hexyl group or allyl group, and various aryl groups such as phenyl group, tolyl group and ethylphenyl group , Aralkyl groups and their derivatives can be used. Typical of these aldehydes are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, acrylaldehyde, cinnamaldehyde, anisaldehyde, nicotinaldehyde,
Furfural etc. can be mentioned.

Further, the aldehyde polymer refers to a polymer obtained by self-condensing the aldehyde represented by the general formula (III) in a concentrated solution or condensing in the presence of an acid catalyst, and the polymer is the present invention. It is a compound that easily hydrolyzes to form an aldehyde monomer under the reaction conditions for synthesizing the copolymer. Typical examples include paraformaldehyde, which is a polymer of aldehyde, and paraaldehyde, which is a trimer of acetaldehyde.

The polycondensation of the carbazole polymer and the aldehyde can be carried out in an organic solvent in which they are both soluble at a temperature of 0 ° C. to 200 ° C. using an acid or alkali catalyst which is a general polycondensation 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 preferred 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.

By the above reaction, the copolymer of the present invention which is substantially linear and has a high degree of polymerization is obtained. The copolymer of the present invention is soluble in solvents such as N-methylpyrrolidone, nitrobenzene, and sulfuric acid, but insoluble in alcohol, hydrocarbons, acetonitrile, propylene carbonate, and the like used in organic electrolyte type batteries, and heated. It is a thermoreversible resin that can be melted by means of excellent processability and can be made into various shaped articles of any shape.

The copolymer of the present invention shows high electric activity by doping with an electron acceptor as a dopant, and can carry out a redox reaction with good repeatability. Therefore, when used as an electrode material of a secondary battery, for example, it is reversible. Charge and discharge can be performed, and even if the number of charge and discharge repetitions (cycle number) is remarkably increased, the elution phenomenon does not occur and the cyclability does not decrease, as seen in the case of a carbazole-based polymer. It is possible to obtain extremely stable characteristics.

Electron-accepting dopants include halogen compounds such as iodine, bromine, hydrogen iodide, arsenic pentafluoride, phosphorus pentachloride, phosphorus pentafluoride, antimony pentafluoride, silicon tetrafluoride, aluminum chloride, aluminum bromide. , Aluminum fluoride, metal halides like ferric chloride, sulfuric acid, nitric acid, protic acids like chlorosulfonic acid, sulfur trioxide, oxidizers like difluorosulfonyl peroxide, like tetracyanoquinodimethane. There can be mentioned various organic substances. Further, as a dopant that can be electrochemically doped, V such as PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ is used.
halide anions of a metal selected, BF ₄ ^-, such as III
halide anions of a metal ^{_{selected, I - (I 8 -)}} , Br -, CI
^- halogen anion such as, C1O ₄ ^- include anions such as perchlorate anion such as.

Further, the copolymer of the present invention has a property that the nitrogen atom in the polymer is positively charged and is in a stable state when doped with an anion, so that the copolymer is stable against repeated redox and has a processability. It is used to form various functional electrodes such as batteries by utilizing the characteristic of goodness. That is, the copolymer of the present invention is molded by using the one dissolved in a solvent, heat-melted and molded, or pressure-molded with the copolymer as a main component, or by using a binder. An electrode can be formed in any shape. Examples of the binder include, but are not limited to, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, and polyethylene.

Further, the copolymer of the present invention can be used as a photoconductive material because it has a carbazole unit which is promising as a photoconductive material.

(Effects of the Invention) Since the copolymer of the present invention is linear, it has excellent processability, and various molded products can be easily manufactured. Also,
By doping the copolymer of the present invention with an electron acceptor, high conductivity can be exhibited, and the doping is reversible and has extremely high cyclability. As excellent.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Example 1 (Synthesis of N-ethylcarbazole dimer) N-ethylcarbazole 8.0 in a 200 m three-necked flask.
After adding 30 g of 70% perchloric acid aqueous solution and 30 m of glacial acetic acid into a homogeneous solution, 200 g of glacial acetic acid was added under stirring at room temperature
9.0 g of 2,3-dichloro-5,6-dicyano-p-benzoquinone dissolved in was added dropwise over 1 hour. After stirring at room temperature for 30 minutes, the reaction precipitate was filtered and washed with diethyl ether. The obtained black powder was dissolved in 600 m of acetone, saturated aqueous sodium hydrogen sulfide solution was added dropwise under stirring to reduce the precipitate, and the precipitate was filtered and dried to give yellow crude N-ethylcarbazole dimer 7.3 g. Got This was further dissolved in chloroform and passed through an alumina column to obtain 6.8 g of a pale yellowish white purified N-ethylcarbazole dimer.

As a result of infrared absorption spectrum analysis and ¹ H-NMR analysis, the obtained N-ethylcarbazole dimer was 9,9′-diethyl-3,3 ′ having a structure linked at the 3-position of N-ethylcarbazole. Found to be bicarbazolyl.

(Polycondensation of N-ethylcarbazole dimer and formaldehyde) 0.39 g of the above N-ethylcarbazole dimer was placed in a 50 m three-necked flask and dissolved in 1,4-dioxane 15 m. After adding a few drops of concentrated sulfuric acid and 82 mg of a 37% aqueous formaldehyde solution, the mixture was heated and stirred at 85 ° C. for 3 hours for reaction. After the reaction, the reaction precipitate was filtered, washed with methanol and dried to obtain 0.36 g of a blue-green polymer. The obtained polymer was soluble in N-methylpyrrolidone and nitrobenzene and insoluble in acetonitrile, propylene carbonate and hydrocarbons.

The result of measuring the infrared absorption spectrum is shown in FIG. 7
90cm ^-1 and an absorption derived from 1,2,4-trisubstituted benzenes 870 cm ^-1 appears strongly, of 750 cm ^-1 was observed in the infrared absorption spectrum of the simultaneously N- ethylcarbazole monomers and dimers It was found that the absorption derived from the 1,2-disubstituted benzene was relatively reduced and the polycondensation with the aldehyde occurred at the 6,6'-position of the N-ethylcarbazole dimer.

Reference Example 1 The copolymer obtained in Example 1 was pressure-bonded onto a platinum mesh to prepare a measuring electrode. 0.07mol / 1 nC ₄ H ₉ NCIO ₄ as electrolyte
The above-mentioned electrode cyclic voltammetry was measured in a dry nitrogen atmosphere using the above acetonitrile solution, a platinum plate as a counter electrode, and an Ag / AgNO ₃ electrode as a reference electrode. The sweep speed was 50 mV / sec. 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. Redox potential is
It was 0.74V VS. Ag / AgNO ₃ .

Example 2 (Synthesis of N-ethylcarbazole polymer) N-ethylcarbazole 19.5 was added to a 1000 m three-necked flask.
After adding g, 450 m of glacial acetic acid and 20 m of concentrated sulfuric acid to form a uniform solution, 35.4 g of sodium dichromate dissolved in 30 m of ion-exchanged water was added dropwise at 30C under stirring over 30 minutes. After stirring at 15 ° C. for 20 minutes, 750 m of a saturated sodium hydrogen sulfite aqueous solution was added, and the mixture was stirred at 65 ° C. for 1 hour to stop the reaction. After the reaction was stopped, the reaction solution was filtered, the obtained solid was dried, further dissolved in chloroform and passed through a silica column to obtain 6.3 g of a yellow-green N-ethylcarbazole polymer.

The obtained N-ethylcarbazole polymer was subjected to mass spectrometry to find that it was a mixture of dimers and trimers of N-ethylcarbazole, and infrared absorption spectrum analysis and ¹ H
As a result of -NMR analysis, it was found to be a dimer and trimer of N-ethylcarbazole having a structure in which N-ethylcarbazole was linked at the 3-position.

(Polycondensation of N-ethylcarbazole polymer and formaldehyde) A reaction was conducted in the same manner as in Example 1 except that 0.30 g of the N-ethylcarbazole polymer was used instead of the N-ethylcarbazole dimer in Example 1. went. After purification, 0.29 g of polycondensation reaction product was obtained.

Example 2 In the same manner as in Reference Example 1, except that the copolymer obtained in Example 2 was used in place of the polycondensation reaction product of N-ethylcarbazole dimer and formaldehyde in Reference Example 1. Click voltammetry measurements were performed. The obtained results are shown in FIG. It showed reversible and extremely stable redox behavior. The redox potential was 0.70 V VS Ag / AgNO ₃ .

Comparative Example In the polycondensation of the N-ethylcarbazole dimer and formaldehyde of Example 1, N-ethylcarbazole 0.35 g, 37% was used instead of the N-ethylcarbazole dimer.
The reaction was carried out as in Example 1 except that 160 mg of formaldehyde aqueous solution was used. After purification, 0.32 g of polycondensation reaction product was obtained. When the polycondensation reaction product was extracted with chloroform, 0.19 g (60%) was soluble in chloroform and 0.13 g (40%) was insoluble.

Same as Reference Example 1 except that the above-mentioned two types of polycondensation products soluble in chloroform and insoluble in chloroform were used in place of the polycondensation reaction product of N-ethylcarbazole dimer and formaldehyde in Reference Example 1. Then, cyclic voltammetry measurement was performed. The obtained results are shown in FIG. 4 (chloroform-soluble portion) and FIG. 5 (chloroform-insoluble portion). Neither showed reversible redox behavior.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum of the copolymer obtained in Example 1, and FIGS. 2 to 5 show the results of cyclic voltammetry of the electrodes in Reference Examples 1 and 2 and Comparative Example, respectively. Show.

Claims (2)

[Claims] 1. General formula (II) (In the formula, R ¹ is H or a hydrocarbon residue having 1 to 20 carbon atoms, n is 2 to 50) and a polymer having a 3,6-carbazolediyl structure represented by the general formula (III ) R ² CHO (III) (R ² is H or a hydrocarbon residue having 1 to 20 carbon atoms or an aldehyde represented by a furyl group, a pyridyl group, a methoxyphenyl group) or a polymer thereof is polycondensed. Characteristic general formula (I) A method for producing a copolymer having a repeating unit represented by the formula (wherein R ¹ , R ² and n are as described above). 2. General formula (II) (In the formula, R ¹ is H or a hydrocarbon residue having 1 to 20 carbon atoms, n is 2 to 50) and a polymer having a 3,6-carbazolediyl structure represented by the general formula (III ) R ² CHO (III) (R ² is H or a hydrocarbon residue having 1 to 20 carbon atoms or an aldehyde represented by a furyl group, a pyridyl group, a methoxyphenyl group) or a polymer thereof is polycondensed to obtain a general compound. formula
(I) An electroactive material comprising producing a copolymer having a repeating unit represented by the formula (wherein R ¹ , R ² and n are as described above), and then doping the copolymer with an electron acceptor. Polymer manufacturing method.