JPH0681778B2 - New copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel polymer, and more particularly to a precursor suitable for conversion into a novel conductive polymer.

(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, JP-A-61-206170 discloses 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. It has been proposed to use it as an electrode material for secondary batteries.

(Problems to be Solved by the Invention) 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 give the above diphenylamine-based polymer good mechanical properties and moldability at the same time as good electrochemical properties, it is necessary to obtain a polymer having a higher degree of polymerization (high polymer). It is difficult to obtain a high molecular weight polymer by Grignard coupling, oxidative coupling, Friedel-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, and improvement has been desired.

(Means for Solving Problems) The present invention relates to a novel polymer, and more particularly to a copolymer suitable for conversion into a conductive polymer that solves the conventional problems. That is, the present invention relates to the copolymer represented by the general formula (I).

In the formula, R ¹ is H or a hydrocarbon residue having 1 to 20 carbon atoms, R ² is H, a hydrocarbon residue having 1 to 20 carbon atoms, a furyl group, a pyridyl group or a methoxyphenyl group, and n is 2 Is an integer of 10 and x is an integer of 2 to 1000.

Further, in the present invention, when the copolymer represented by the general formula (I) is doped with an electron acceptor, an excellent electroactive polymer can be obtained as described below.

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

The polymer having the 4,4'-diphenylamine structure represented by the general formula (II) as a repeating unit is, for example, the oxidative coupling method used in JP-A-61-206170 or JP-A-61-28524. It can be synthesized by a known method such as the 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- Examples thereof include 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 to 10, preferably 2
~ 8.

Further, as the aldehyde represented by the general formula (III), in the formula, R ² is hydrogen or a carbon number of 1 to 20, preferably 1 to
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, n-hexyl group or allyl group, various aryl groups such as phenyl group, tolyl group, ethylphenyl group, aralkyl group and derivatives thereof can be used. Typical of these aldehydes are formaldehyde,
Examples thereof include acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, acrylaldehyde, cinnamaldehyde, anisaldehyde, nicotinaldehyde, furfural and the like.

In addition, the aldehyde polymer is a self-condensation of the aldehyde represented by the general formula (III) in a concentrated solution,
Represents a polymer obtained by condensation in the presence of an acid catalyst,
The polymer represents a polymer which is easily hydrolyzed to form 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 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 24 hours without 5 minutes.

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

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 thermoplastic resin that can be melted by means of, is excellent in workability, and can be formed 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 are possible, 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 deteriorate, as seen in the case of diphenylamine polymers. It is possible to obtain extremely stable characteristics.

As the electron accepting dopant, iodine, halogen compounds such as bromine hydrogen iodide, arsenic pentafluoride, phosphorus pentachloride, phosphorus pentafluoride, antimony pentafluoride, silicon tetrafluoride, aluminum chloride, aluminum bromide, Aluminum fluoride, metal halides such as ferric chloride, sulfuric acid, nitric acid, protic acids such as chlorosulfonic acid, sulfur trioxide, oxidizing agents such as difluorosulfonyl peroxide, such as tetracyanoquinodimethane Examples thereof include organic substances. The electrochemical doping can _{^{dopant, PF 6 -, SbF 6 -}} , AsF 6 - Va metal selected halide anions, such as, BF ₄ ^- IIIa metal selected halide anions, such as, _{^{I - (I 6 -),}} Br -, Cl - halogen anion such as, ClO 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.

(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-methyldiphenylamine polymer) 50.0 g of anhydrous FeCl ₃ was placed in a 300 ml three-necked flask, 150 ml of ethanol was added and dissolved, and then 18.4 g of N-methyldiphenylamine was added, and at room temperature, The reaction was carried out for 24 hours while stirring in a nitrogen atmosphere. The blue-green precipitate produced after the reaction was filtered, washed with ethanol and ion-exchanged water, washed with ethanol again and dried to obtain 12.1 g of a blue solid.

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 11.6 g of a dichloromethane-soluble N-methyldiphenylamine polymer.

The obtained N-methyldiphenylamine polymer was an oligomer of N-methyldiphenylamine having major peaks at mass numbers 364 and 545, and polymerization degrees of 2 and 3, from the results of mass spectrometry. In addition, infrared absorption spectrum measurement was carried out, and an absorption at 820 cm ⁻¹ derived from para-substituted benzene was observed. Therefore, this polymer has a structure linked at the para position of the phenyl group of N-methyldiphenylamine. I understood it.

(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. 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, and the mixture was heated and stirred at 85 ° C. for 3 hours for reaction. 200m after reaction
The precipitate was filtered into 1 l of ethanol, washed with acetonitrile, and dried to obtain 0.73 g of a blue polymer.
The obtained polymer was soluble in N-methylpyrrolidone and nitrobenzene, and insoluble in acetonitrile, propylene carbonate, dichloromethane and hydrocarbons.

The result of measuring the infrared absorption spectrum is shown in FIG. 82
Absorption derived from para-substituted benzene of 0 cm ^-1 appeared strong, at the same time N- methyldiphenylamine polymer infrared absorption derived from mono-substituted benzene absorption 700 cm ^-1 and 750 cm ^-1 which is observed in the spectrum is significantly reduced It was found that polycondensation with an aldehyde occurred at the para position of the terminal phenyl group of the N-methyldiphenylamine polymer.

Reference Example 1. The polymer obtained in Example 1 was pressure-bonded onto a platinum mesh to prepare a measurement electrode. 0.07 mol / l (nC ₄ H ₉ ) ₄ NClO as electrolyte
Cyclic voltammetry of the above electrodes was measured in a dry nitrogen atmosphere using the acetonitrile solution of _4, 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 0.40
It was V VS. 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. Furthermore, with this polymer 2.0g
Polycondensation reaction was performed with 0.85 g of 37% aqueous formaldehyde solution at room temperature for 4 hours to obtain 16.3 g of a polycondensation reaction product of the N-ethyldiphenylamine polymer and formaldehyde. x is about 70.

Reference Example 2 Reference Example 1 except that the polymer obtained in Example 2 was used in place of the polycondensation reaction product of the N-methyldiphenylamine polymer and propionaldehyde in Reference Example 1.
The cyclic voltammetry measurement was performed in the same manner as in.
The obtained results are shown in FIG. It showed reversible and extremely stable redox behavior. Redox potential is 0.41V VS. Ag / AgN
It was O ₃ .

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

Reference Example 3. Reference Example 1 except that the polymer obtained in Example 3 was used in place of the polycondensation reaction product of the N-methyldiphenylamine polymer and propionaldehyde in Reference Example 1.
The cyclic voltammetry measurement was performed in the same manner as in.
The obtained results are shown in FIG. It showed reversible and extremely stable redox behavior. Redox potential is 0.40 V VS. Ag / AgN
It was O ₃ .

Example 4 A reaction was performed 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.

Example 5 Example 1 except that 0.30 g of acetaldehyde was used instead of propionaldehyde in Example 1.
The reaction was performed in the same manner as in. After purification, 0.81 g of polycondensation reaction product was obtained.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum diagram of the copolymer obtained in Example 1, and FIGS. 2 to 4 show cyclic voltammetry measurements of the electrodes in Reference Examples 1 to 3, respectively.

Claims (1)

[Claims] 1. A general formula (In the formula, R ¹ is H or a hydrocarbon residue having 1 to 20 carbon atoms, R ²
Is H, a hydrocarbon residue having 1 to 20 carbon atoms, a furyl group, a pyridyl group or a methoxyphenyl group, n is an integer of 2 to 10, and x is an integer of 2 to 1000) Coalescing.