WO2020017113A1

WO2020017113A1 - Polymer electrolyte, method for producing same, polymer electrolyte membrane using same, catalyst layer, membrane/electrode assembly and fuel cell

Info

Publication number: WO2020017113A1
Application number: PCT/JP2019/015658
Authority: WO
Inventors: 宮武健治; 内田誠; 三宅純平; 安眞住; 日下部正人
Original assignee: 国立大学法人山梨大学; 株式会社カネカ
Priority date: 2018-07-19
Filing date: 2019-04-10
Publication date: 2020-01-23
Also published as: JPWO2020017113A1; JP7239114B2

Abstract

The present invention relates to a polymer electrolyte which is composed of a hydrophobic segment that has a structure represented by general formula (1) and a hydrophilic segment that has a sulfonic acid group, while having the main chain mainly composed of aromatic rings, and which is configured such that the hydrophobic segment and the hydrophilic segment are joined to each other by means of direct bonds of the aromatic rings. (In general formula (1), each of R^a and R^b independently represents a fluorine atom or a perfluoroalkyl group; y represents an integer of 1-2,000; and a hydrogen atom on a benzene ring may be substituted by a fluorine atom, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group or a cyano group.) Consequently, the present invention provides: a polymer electrolyte which achieves high proton conductivity, while having high oxidation degradation resistance and gas barrier properties, and which is suitable for use as a polymer electrolyte membrane and is able to be easily produced, while exhibiting good solubility in solvents and excellent formability such as film forming properties; a method for producing this polymer electrolyte; a polymer electrolyte membrane; a catalyst layer; a membrane/electrode assembly; and a fuel cell.

Description

Polymer electrolyte, method for producing the same, polymer electrolyte membrane using the same, catalyst layer, membrane / electrode assembly, and fuel cell

The present invention relates to a polymer electrolyte suitable for a polymer electrolyte fuel cell, a method for producing the same, a polymer electrolyte membrane using the same, a catalyst layer for a fuel cell, a membrane / electrode assembly for a fuel cell, and a fuel cell.

から From the viewpoint of environmental problems such as global warming, the development of highly efficient and clean energy sources is required. A fuel cell is attracting attention as one candidate for the demand. In particular, polymer electrolyte fuel cells using polymer electrolytes are expected as one of the pillars of new energy technology. As an electrolyte membrane used for a polymer electrolyte fuel cell, a perfluorocarbon sulfonic acid membrane represented by Nafion (registered trademark) has been widely studied. The perfluorocarbon sulfonic acid membrane is said to have high proton conductivity and to be excellent in chemical stability such as acid resistance and oxidation resistance, but gas barrier properties were not sufficient.

From such a background, in recent years, an electrolyte membrane for a polymer electrolyte fuel cell has recently been composed of a copolymer comprising a hydrophilic segment having a sulfonic acid group and a hydrophobic segment having substantially no sulfonic acid group. Attention has been paid to hydrocarbon-based electrolyte membranes. As a method for producing such a polymer electrolyte, a unit having a nucleophilic functional group such as a hydroxyl group or a sulfide group and a unit having a leaving substituent such as a halogen are prepared in advance, and the nucleophilic substitution reaction thereof is performed. (Patent Document 1). Although this production method is simple, there is a problem that, since an ether bond or a thioether bond is generated in the resin skeleton, when it is used as an electrolyte membrane for a fuel cell, it is easily oxidized and deteriorated (Non-Patent Document 1).

Therefore, in Patent Documents 2 and 3, an attempt has been made to connect the hydrophilic segment and the hydrophobic segment by a direct carbon-carbon bond, and to eliminate an ether bond or a thioether bond from the vicinity of the sulfonic acid group. Patent Document 4 discloses a polyphenylene-type polymer electrolyte in which a hetero bond such as an ether bond or a thioether bond is completely eliminated from the main chain structure of a hydrophilic segment and a hydrophobic segment, and which is connected by a carbon-carbon direct bond. A polyphenylene-type polymer electrolyte in which a hydrophilic monomer and a hydrophobic monomer are randomly linked by a carbon-carbon direct bond is described. Patent Literature 5 discloses that a sulfonic acid group-introduced hydrophilic segment having a main chain composed of an aromatic ring and a hydrophobic segment having no sulfonic acid group and having a main chain composed of an aromatic ring have an aromatic ring carbon-carbon. There has been proposed a polymer electrolyte which is connected by a direct bond and further has an aromatic ring of a hydrophobic segment also connected by a carbon-carbon direct bond.

JP 2005-126684 A JP 2008-88420 A JP 2012-229418 A JP 2013-191375 A JP 2017-179345 A

However, in the polymer electrolytes described in Patent Literatures 2 and 3, a skeleton having a unit such as polyether sulfone or polyether ketone may be used for the hydrophobic segment in some cases. The oxidation resistance of the molecular electrolyte membrane has not yet reached a satisfactory level. In the polymer electrolyte described in Patent Document 4, since the sulfonic acid group of the hydrophilic monomer is connected to the aromatic ring by a linking group containing an electron donating group, the production process is complicated. Also in the polymer electrolyte described in Patent Literature 5, production of the hydrophobic segment may be complicated. Furthermore, conventional hydrocarbon-based polymer electrolytes containing a large number of aromatic rings are dissolved only in aprotic polar solvents having a high boiling point (eg, dimethyl sulfoxide, N-methylpyrrolidone, etc.). It takes a long time, and the solvent remains in the film even after drying, so it has been necessary to remove it by a post-treatment such as washing with water.

The present invention is a polymer that exhibits high proton conductivity, has high resistance to oxidative degradation, can be used as a polymer electrolyte membrane having good gas barrier properties, is easy to manufacture, and is soluble in low-boiling alcohols. Provided are an electrolyte, a method for producing the same, a polymer electrolyte membrane using the same, a catalyst layer for a fuel cell, a membrane / electrode assembly for a fuel cell, and a fuel cell.

The present invention comprises a hydrophobic segment having a structure represented by the following general formula (1), and a hydrophilic segment having a sulfonic acid group and having a main chain mainly composed of an aromatic ring. The present invention relates to a polymer electrolyte, wherein segments are connected by a direct bond of an aromatic ring.

(In the general formula (1), R ^a and R ^b each independently represent fluorine or a perfluoroalkyl group, y represents an integer of 1 to 2,000, and hydrogen on the benzene ring represents fluorine, an alkyl group, (It may be substituted with one or more selected from the group consisting of a fluoroalkyl group, an aryl group, an aralkyl group, and a cyano group.)

In one or more preferred embodiments of the present invention, in the general formula (1), ^Ra and ^Rb are each a trifluoromethyl group. In one or more preferred embodiments of the present invention, in the general formula (1), y is an integer of 6 to 500.

In one or more preferred embodiments of the present invention, the hydrophilic segment has one or more structures selected from the group of structures represented by the following formula group (2). In one or more more preferred embodiments of the present invention, the hydrophilic segment has one or more structures selected from the group of structures represented by the following formula group (15).

(In the above formula group (2), w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 is an integer of 1 or more. P is an integer of 0 to 10, q represents an integer of 0 to 10, r represents an integer of 1 to 4. A represents at least one member selected from the group consisting of -CO-, -SO _2- , and -C (CF ₃ ) _2- . D represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _t — (t is an integer of 1 to 10), and —C (CF ₃ ) represents at least one kind of structure selected from the group consisting of _2-, E is a direct bond, or-(CH ₂ ) _j- (j is an integer of 1 to 10), -C (CH ₃ ) ₂ Represents at least one structure selected from the group consisting of —, —O—, and —S—, where Ar ¹ is —SO ₃ H or —O (CH ₂ ) _z SO ₃ H (z is 1 to 12) of It represents an aromatic group having a substituent represented by a number).)

(In the above formula group (15), w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 is an integer of 1 or more.)

In one or more more preferred embodiments of the present invention, the polymer electrolyte has a structure represented by the following general formula (3).

(In the general formula (3), x represents an integer of 1 to 2000, and y represents an integer of 1 to 2000.)

Further, the present invention is the method for producing a polymer electrolyte described above, wherein the compound is selected from a compound having a structure represented by the following general formula (4) and a structure group represented by the following formula group (5). The present invention relates to a method for producing a polymer electrolyte, comprising copolymerizing one or more compounds having a structure in the presence of a transition metal compound.

(In the general formula (4), Hal represents chlorine, bromine, or iodine, R ^a and R ^b each independently represent fluorine or a perfluoroalkyl group, and hydrogen on the benzene ring represents fluorine or an alkyl group. , A perfluoroalkyl group, an aryl group, an aralkyl group, and a cyano group.

(In the formula group (5), Hal represents chlorine, bromine, or iodine, w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 represents 1 or more. P is an integer of 0 to 10, q is an integer of 0 to 10, r is an integer of 1 to 4. A is —CO—, —SO ₂ —, and —C (CF ₃ ) ₂ -Represents at least one structure selected from the group consisting of-, wherein D is -CO-, -SO _2- , -SO-, -CONH-, -COO-,-(CF ₂ ) _t- (t is Represents an at least one structure selected from the group consisting of an integer of 1 to 10) and —C (CF ₃ ) ₂ —, wherein E is a direct bond or — (CH ₂ ) _j — (j is 1 to 10 _{integer), - C (CH 3)} 2 -, - O-, and .Ar ¹ representing at least one structure selected from the group consisting of -S- are, -SO ₃ H or _{_{_{O (CH 2) z SO 3}}} H (z is an integer between 1 and 12) .M representing an aromatic group having a substituent represented by hydrogen, an alkali metal, an alkyl group having 1 to 12 carbon atoms, carbon atoms Represents a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.)

The present invention also relates to a polymer electrolyte membrane using the above-mentioned polymer electrolyte.

In one or more more preferred embodiments of the present invention, the polymer electrolyte membrane has an ion exchange capacity (IEC) of 2.0 to 3.6 meq. / G. In one or more more preferred embodiments of the present invention, a weight retention rate in a Fenton test in which the polymer electrolyte membrane is treated at 80 ° C. for 1 hour in a Fenton solution (3% H ₂ O ₂ containing 2 ppm of FeSO ₄ ). Is 95% or more.

The present invention also relates to a fuel cell catalyst layer using the polymer electrolyte.

本 The present invention also relates to a membrane / electrode assembly for a fuel cell using the above-mentioned polymer electrolyte.

The present invention also relates to a fuel cell using the above-mentioned polymer electrolyte.

ADVANTAGE OF THE INVENTION According to this invention, it expresses high proton conductivity, is highly resistant to oxidative degradation, can be used as a polymer electrolyte membrane having good gas barrier properties, and can be manufactured from easily available raw materials using a simple reaction. It is possible to provide a polymer electrolyte that is easily soluble in not only a high-boiling aprotic polar solvent but also a low-boiling solvent such as an alcohol, so that molding such as film formation is easy. In addition, it is possible to provide a polymer electrolyte membrane which exhibits high proton conductivity using the polymer electrolyte, has high resistance to oxidative deterioration, and has good gas barrier properties. Further, according to the present invention, it is possible to easily and easily develop a high proton conductivity, have a high resistance to oxidative deterioration even under the operating conditions of a fuel cell, and use the polymer electrolyte membrane with a good gas barrier property. A polymer electrolyte can be made.

FIG. 1 is a graph showing the proton conductivity of the polymer electrolyte membrane. FIG. 2 is a graph showing the viscoelasticity of the polymer electrolyte membrane, where (a) shows the storage modulus, (b) shows the loss modulus, and (c) shows the loss tangent. FIG. 3 is a graph showing the proton conductivity of the polymer electrolyte membrane before and after the Fenton test. FIG. 4 is a graph showing viscoelasticity of the polymer electrolyte membrane before and after the Fenton test, where (a) shows the storage modulus, (b) shows the loss modulus, and (c) shows the loss tangent. FIG. 5 is a graph showing a result of an open circuit voltage endurance test of the polymer electrolyte membrane. FIG. 6 is a graph showing gas permeability of the polymer electrolyte membrane, where (a) shows hydrogen permeability and (b) shows oxygen permeability.

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, a hydrophobic segment represented by the following general formula (1) and a hydrophilic segment having a sulfonic acid group and a main chain mainly composed of an aromatic ring are formed, and the hydrophobic segment and the hydrophilic segment are aromatic. The polymer electrolyte connected by a direct bond of the ring can be easily produced using readily available raw materials, and has high solubility in a solvent, so that it is easy to form a membrane or the like, and It has been found that a polymer electrolyte membrane using the polymer electrolyte has high proton conductivity, high resistance to oxidative deterioration, and good gas barrier properties.

In the general formula (1), R ^a and R ^b each independently represent fluorine or a perfluoroalkyl group, y represents an integer of 1 to 2,000, and hydrogen on the benzene ring is fluorine, an alkyl group, or a perfluoroalkyl group. It may be substituted with one or more selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and a cyano group.

１ One or more embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments.

In the general formula (1), y is an integer of 1 to 2000, preferably 5 to 1500, more preferably 6 to 600, still more preferably 8 to 500, and still more preferably 8 to 500. 250. If y exceeds 2,000, the polymer electrolyte has a high viscosity and is difficult to dissolve in a solvent, making molding difficult.

In the general formula (1), the hydrogen of the benzene ring may be substituted with one or more selected from the group consisting of fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, and a cyano group. From the standpoint of availability, all are preferably hydrogen.

In the general formula (1), R ^a and R ^b are each independently a fluorine or a perfluoroalkyl group. The type of the perfluoroalkyl group is not particularly limited, but may be, for example, 1 to 10 carbon atoms, 1 to 5 carbon atoms, or 1 to 3 carbon atoms. Good. Specific examples of the perfluoroalkyl group include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, and the like, and a trifluoromethyl group is preferable in terms of availability.

として The hydrophobic segment having the structure represented by the general formula (1) is not particularly limited, but specific examples include a structure represented by the following formula group (6). In the following formula group (6), y is an integer of 1 to 2000, preferably 5 to 1500, more preferably 6 to 600, still more preferably 8 to 500, and still more preferably 8 to 500. 250. If y exceeds 2,000, the polymer electrolyte has a high viscosity and is difficult to dissolve, making molding difficult.

In the hydrophobic segment having the structure represented by the general formula (1), the two aromatic rings are connected by a group represented by -C (R ^a ) (R ^b )-, so that the hydrophobic segment is bent. The solubility in not only a high-boiling aprotic polar solvent but also a low-boiling solvent such as an alcohol is increased, and molding into a film or the like becomes easy.

In the polymer electrolyte according to one or more embodiments of the present invention, the hydrophobic segment has, in addition to the segment having the structure represented by the general formula (1), another segment within a range not to impair the effects of the present invention. It may be. The other segment is not particularly limited, but has a segment having a structure represented by the general formula (1) and a sulfonic acid group, and is connected by a direct bond between a hydrophilic segment mainly composed of an aromatic ring and an aromatic ring. A structure having the following structure is preferable, and examples thereof include a metaphenylene segment represented by the following general formula (7) and a paraphenylene segment represented by the following general formula (8). The other segment may be one, or one or more.

In the general formula (7), R ¹ to R ⁴ each independently represent hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group. u represents an integer of 1 to 1500. From the viewpoint of availability of raw materials, it is preferable that all of R ¹ to R ⁴ be hydrogen. u is preferably from 5 to 500, and more preferably from 6 to 250. If u exceeds 1500, the polymer electrolyte is difficult to dissolve, resulting in high viscosity, which may make molding difficult.

In the general formula (8), R ⁵ to R ⁸ each independently represent hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group. v represents an integer of 1 to 1500. From the viewpoint of availability of raw materials, it is preferable that all of R ⁵ to R ⁸ are hydrogen. v is preferably from 5 to 500, and more preferably from 6 to 250. If v exceeds 1500, the polymer electrolyte is difficult to dissolve and has a high viscosity, which may make molding difficult.

By introducing a metaphenylene segment having a structure represented by the general formula (7) and / or a paraphenylene segment having a structure represented by the general formula (8), the flexibility of the molecular chain is controlled, The rigidity and / or flexibility of the electrolyte membrane can be adjusted.

A hydrophobic segment, specifically, a segment having a structure represented by the general formula (1), and a metaphenylene segment having a structure represented by the general formula (7) used as necessary, and / or The aromatic ring constituting the main chain of the paraphenylene segment having the structure represented by the general formula (8) is connected by a perfluoroalkyl group not containing an aliphatic carbon-hydrogen bond or a direct bond, and an ether bond or a thioether No hetero bonds such as bonds, and the hydrophobic segment and the hydrophilic segment are also connected by a direct carbon-carbon bond of the aromatic ring, exhibiting high durability against severe oxidation conditions during fuel cell operation. I do.

The hydrophilic segment having a sulfonic acid group and having a main chain mainly composed of an aromatic ring (hereinafter also referred to as a sulfonic acid group-containing hydrophilic segment) has a sulfonic acid group and a main chain mainly composed of an aromatic ring. And a sulfonic acid group directly bonded to an aromatic ring. Since the segment has a sulfonic acid group, the polymer electrolyte exhibits proton conductivity and the main chain is mainly composed of an aromatic ring, so that the polymer electrolyte has excellent heat resistance and chemical durability.

Examples of the sulfonic acid group include a sulfonic acid group, a salt of the sulfonic acid group, and a sulfonic acid ester group. That is, the sulfonic acid group may be in the form of a salt such as sodium or potassium, or may be protected by an ester group such as neopentyl ester, methyl ester, or propyl ester. Particularly during or after the synthesis of the sulfonic acid group-containing hydrophilic segment precursor, it is often preferable to have a state having a protecting group such as a salt or an ester, but the polymer electrolyte is, for example, a fuel cell. When used as an electrolyte membrane, it is often used after being immersed in an aqueous solution of an inorganic acid or the like to be converted into a sulfonic acid group. Therefore, in the present invention, the sulfonic acid group includes a group having a protecting group such as a salt or an ester as long as the group easily converts to a sulfonic acid group.

The amount of the sulfonic acid group is preferably 1 to 6, more preferably 1 to 4, per repeating unit forming the sulfonic acid group-containing hydrophilic segment. When the amount of the sulfonic acid group is more than 6, the water solubility of the segment is increased, and handling during synthesis tends to be difficult. If the number is less than one, sufficient proton conductivity tends to be hardly developed.

スルホン The sulfonic acid group-containing hydrophilic segment has a main chain mainly composed of an aromatic ring. Here, “mainly composed of an aromatic ring” means that the molecular weight of a portion other than the main chain linking group (ether group, thioether group, sulfone group, ketone group, sulfide group, etc.) in the sulfonic acid group-containing hydrophilic segment is 100%. % Means that 70% or more thereof is composed of an aromatic ring. Examples of the aromatic ring include benzene, naphthalene, anthracene, biphenyl, and an aromatic heterocyclic ring containing sulfur, nitrogen, and the like. When the main chain is mainly composed of an aromatic ring, chemical and thermal stability is high. Examples of such a main chain structure include polyether, polyether ketone, polyether ether ketone, polyether sulfone, polyether ether sulfone, polyketone, polysulfone, polysulfide, polyphenylene, polyimide, polybenzimidazole and the like.

The sulfonic acid group-containing hydrophilic segment preferably has one or more structures selected from the structural group represented by the following formula group (2).

In the above formula group (2), w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 is an integer of 1 or more. p represents an integer of 0 to 10, q represents an integer of 0 to 10, and r represents an integer of 1 to 4. A represents at least one kind of structure selected from the group consisting of —CO—, —SO ₂ —, and —C (CF ₃ ) ₂ —, preferably, —SO ₂ — and —C (CF ₃ ) at least one structure selected from the group consisting of _2- , more preferably -C (CF ₃ ) _2- . D represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _t — (t is an integer of 1 to 10), and —C (CF ₃ ) ₂ — And represents at least one structure selected from the group consisting of: preferably, -SO _2- , -SO-, -CONH-, -COO-,-(CF ₂ ) _t- (t is an integer of 1 to 10) ) And at least one structure selected from the group consisting of -C (CF ₃ ) _2- , more preferably-(CF ₂ ) _t- (t is an integer of 1 to 10), and -C It represents at least one structure selected from the group consisting of (CF ₃ ) ₂ —. E is a direct bond or at least one selected from the group consisting of — (CH ₂ ) _j — (j is an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O—, and —S— Represents the structure of the species. Ar ¹ represents an aromatic group having a substituent represented by —SO ₃ H or —O (CH ₂ ) _z SO ₃ H (z is an integer of 1 to 12).

The sulfonic acid group-containing hydrophilic segment is selected from the group of structures represented by the following formula group (15) from the viewpoint that raw materials are easily available, and there is no hetero bond in the structure and the chemical durability is excellent. It is preferable to have one or more structures.

スルホン The sulfonic acid group-containing hydrophilic segment having the structure represented by the formula group (2) is not particularly limited, and specific examples include a structure represented by the following formula group (9).

In one or more embodiments of the present invention, it is particularly preferable that the polymer electrolyte has a structure represented by the following general formula (3).

The sulfonic acid group-containing hydrophilic segment in the polymer electrolyte having the structure represented by the general formula (3) is easily available as a raw material, has a high sulfonic acid group equivalent in the segment, and has another sulfonic acid group-containing hydrophilic property. There is an advantage that a higher proton conductivity can be obtained with a smaller amount of use as compared with the acidic segment. In the polymer electrolyte having the structure represented by the general formula (3), the hexafluoroisopropylidene diphenyl structure as a hydrophobic segment can be easily synthesized from a relatively inexpensive raw material as a precursor. ,preferable.

In the general formula (3), x is an integer of 1 to 2000, y is an integer of 1 to 2000, preferably x is an integer of 2 to 800, and y is an integer of 5 to 1500, more preferably , X is an integer of 3 to 800, y is an integer of 6 to 600, more preferably x is an integer of 4 to 600, y is an integer of 8 to 500, and still more preferably, x is 4 to 600. An integer of 400 and y is an integer of 8 to 250. When x exceeds 2,000, the hydrophilicity of the polymer electrolyte becomes too high, and the swelling resistance may be reduced, or the polymer electrolyte may be dissolved in water. On the other hand, when the value of y is more than 2,000, it is difficult to dissolve in a solvent, and the moldability at the time of forming a film is reduced.

Next, a method for producing the polymer electrolyte of the present invention will be described. Although there is no particular limitation on the method for producing a polymer electrolyte of the present invention, a precursor of a sulfonic acid group-containing hydrophilic segment and a precursor of a hydrophobic segment having a structure represented by the general formula (1) are linked. The method is preferably used. Here, the precursor is a compound having a reactive site that becomes a sulfonic acid group-containing hydrophilic segment and a hydrophobic segment having a structure represented by the general formula (1), respectively, by a copolymerization reaction described below. Say. In the present invention, since the sulfonic acid group-containing hydrophilic segment and the hydrophobic segment having the structure represented by the general formula (1) are connected by a direct bond of an aromatic ring, the precursor of each segment is an aromatic ring. Must have a functional group to be directly linked.

For example, as a precursor of a hydrophobic segment having a structure represented by the general formula (1), a compound having a structure represented by the following general formula (4), and as a precursor of a sulfonic acid group-containing hydrophilic segment, One or more compounds having a structure selected from the structure group represented by Formula Group (5) are converted to a transition metal compound according to an Ullmann coupling reaction using copper metal or a method described in Patent Document 3. The coupling can be performed by using a coupling method.

In the general formula (4), Hal represents chlorine, bromine, or iodine, R ^a and R ^b each independently represent fluorine or a perfluoroalkyl group, and hydrogen on the benzene ring represents fluorine, an alkyl group, It may be substituted with one or more selected from the group consisting of a perfluoroalkyl group, an aryl group, an aralkyl group, and a cyano group. From the viewpoint of easy availability, it is preferable that the hydrogen on the benzene ring in the general formula (4) is not substituted, that is, all hydrogens.

In the formula group (5), Hal represents chlorine, bromine, or iodine, w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 represents an integer of 1 or more. It is. p represents an integer of 0 to 10, q represents an integer of 0 to 10, and r represents an integer of 1 to 4. A represents at least one structure selected from the group consisting of —CO—, —SO ₂ —, and —C (CF ₃ ) ₂ —, and preferably represents —SO ₂ — and —C (CF _3). ) ₂ — at least one structure selected from the group consisting of —, more preferably —C (CF ₃ ) ₂ —. D represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _t — (t is an integer of 1 to 10), and —C (CF ₃ ) ₂ — And represents at least one structure selected from the group consisting of: preferably, -SO _2- , -SO-, -CONH-, -COO-,-(CF ₂ ) _t- (t is an integer of 1 to 10) ) And at least one structure selected from the group consisting of -C (CF ₃ ) _2- , more preferably-(CF ₂ ) _t- (t is an integer of 1 to 10), and -C It represents at least one structure selected from the group consisting of (CF ₃ ) ₂ —. E is a direct bond or at least one selected from the group consisting of-(CH ₂ ) _j- (j is an integer of 1 to 10), -C (CH ₃ ) _2- , -O- and -S- Represents the structure of Ar ¹ represents an aromatic group having a substituent represented by —SO ₃ H or —O (CH ₂ ) _z SO ₃ H (z is an integer of 1 to 12). M represents hydrogen, an alkali metal, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.

化合物 The compound having the structure represented by the general formula (4) is not particularly limited, but specific examples include a compound represented by the following formula group (10).

において In the compound group represented by the formula group (10), a compound in which a chlorine atom is replaced with bromine or iodine can also be suitably used. Among these, compounds having a structure represented by the following formula group (11) are preferable from the viewpoint of availability of raw materials.

The method for producing the compound having the structure represented by the general formula (4) is not particularly limited, and for example, as described in Macromolecules @ 1999, 32, 6418, and US Patent No. 4,503,254. It can be synthesized by converting a hydroxyl group of a phenolic compound into a halogen.

具体 Specific examples of the compound having a structure represented by the formula group (5) include a compound having a structure represented by the following formula group (12).

において In the compound group having the structure represented by the formula group (12), a compound in which a chlorine atom is replaced with bromine or iodine can also be suitably used. M is hydrogen, an alkali metal, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 18 carbon atoms, as described in the formula group (5), Alternatively, it represents 7 to 20 carbon atoms, and is appropriately selected depending on the polymerization conditions.

The precursor of the sulfonic acid group-containing hydrophilic segment can be produced by reacting a corresponding aromatic compound with a sulfonating agent. Known sulfone oxidizing agents can be used, and examples thereof include sulfuric acid, sulfuric anhydride, chlorosulfonic acid, acetyl sulfate, fuming sulfuric acid and the like. Chlorosulfonic acid and / or fuming sulfuric acid are preferable because they have appropriate reactivity. In the sulfonation reaction, a solvent may or may not be used. When a solvent is used, the solvent only needs to be inert to the sulfone oxidizing agent, and examples thereof include a hydrocarbon-based solvent and a halogenated hydrocarbon. Examples of the hydrocarbon-based solvent include saturated aliphatic hydrocarbons, and particularly preferred are linear or branched hydrocarbons having 5 to 15 carbon atoms. From the viewpoint of solubility, pentane, hexane, heptane, octane, and Decane and the like are more preferred. Examples of the halogenated hydrocarbon include a halogenated saturated aliphatic hydrocarbon, a halogenated aromatic hydrocarbon, and the like. Examples of the halogenated saturated aliphatic hydrocarbon include, for example, monochloromethane, dichloromethane, trichloromethane, tetrachloromethane, monochloroethane, dichloroethane, trichloroethane, tetrachloroethane, etc., and dichloromethane is preferable from the viewpoint of easy handling. As the halogenated aromatic hydrocarbon, for example, chlorobenzene, dichlorobenzene, trichlorobenzene and the like can be mentioned, and chlorobenzene is preferable from the viewpoint of easy handling. One type of solvent may be used alone, or two or more types may be used in combination.

The reaction temperature at the time of the sulfonation reaction may be appropriately set according to the reaction, and specifically, may be set at -80 ° C to 200 ° C, which is the optimum use range of the sulfone oxidizing agent, and more preferably -50 ° C. To 150 ° C, more preferably from -20 ° C to 130 ° C. If the temperature is lower than −80 ° C., the reaction tends to be slow, and the desired sulfonation tends not to proceed to 100%. If the temperature is higher than 200 ° C., side reactions tend to occur. The reaction time at the time of the sulfonation reaction can be appropriately selected depending on the structure of the aromatic compound to be used as a raw material, but may be generally within a range of about 1 minute to 50 hours. If it is shorter than 1 minute, uniform sulfonation tends not to progress, and if it is longer than 50 hours, side reactions tend to occur.

The amount of the sulfone oxidizing agent to be added in the sulfone oxidation reaction is preferably 1 to 50 equivalents when the total amount of the sulfonated sites contained in the raw material aromatic compound is 1 equivalent. If the amount is less than 1 equivalent, the site to be sulphonated tends to be non-uniform, while if it is more than 50 equivalents, side reactions tend to occur.

The concentration of the aromatic compound as a raw material in the sulfone oxidation reaction is not particularly limited as long as the reaction proceeds uniformly when it is brought into contact with a sulfone oxidizing agent. From the viewpoint of properties, the amount is preferably 1 to 30% by weight based on the total weight of the compounds used in the sulfonation reaction.

The ion exchange capacity of only the sulfonic acid group-containing hydrophilic segment (hereinafter, the ion exchange capacity is sometimes referred to as IEC) can be set to a high IEC as a polymer electrolyte membrane, and also has a high proton conductivity under low humidification. From the point that 2.0 meq. / G or more. meq. / G means milliequivalents / g. The IEC of the sulfonic acid group-containing hydrophilic segment can be calculated by NMR analysis or by calculating the IEC of the electrolyte obtained by copolymerization (which is easily obtained by a conventionally known method, for example, titration). By dividing by the weight ratio of the sex segment.

スルホン The sulfonic acid group of the precursor of the sulfonic acid group-containing hydrophilic segment may be in a protected form.

In order to adjust the rigidity and / or flexibility of the main chain of the polymer electrolyte, a metaphenylene segment having a structure represented by the general formula (7) and / or a metaphenylene segment represented by the general formula (8) When a paraphenylene segment having a structure represented by the general formula (7) is introduced, as a precursor of a metaphenylene segment having a structure represented by the general formula (7), for example, a compound having a structure represented by the following general formula (13): As the paraphenylene segment having the structure represented by the general formula (8), for example, a compound represented by the following general formula (14) can be used.

In the general formula (13), Hal represents chlorine, bromine, or iodine, and R ¹ to R ⁴ each independently represent hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group. Represents a group.

In the general formula (14), Hal represents chlorine, bromine, or iodine, and R ⁵ to R ⁸ each independently represent hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group. Represents a group.

Specific examples of the compound having the structure represented by the general formula (13) include 1,3-dichlorobenzene, 1,3-dibromobenzene, 1,3-diiodobenzene, 2,6-dichlorotoluene, 2,6-dibromotoluene, 2,6-diiodotoluene, 2,6-dichloro-1,4-dimethylbenzene, 2,6-dibromo-1,4-dimethylbenzene, 2,6-diiodo-1,4- Dimethylbenzene, 2,6-dichloro-1,3-dimethylbenzene, 2,6-dibromo-1,3-dimethylbenzene, 2,6-diiodo-1,3-dimethylbenzene, 2,6-dichlorobenzonitrile, Examples include 2,4-dichlorobenzonitrile, 2,6-dichlorofluorobenzene, and 3,5-dichlorofluorobenzene. These may be used alone or in combination of two or more. Of these, at least one selected from the group consisting of 1,3-dichlorobenzene, 2,6-dichlorotoluene, and 2,6-dichlorobenzonitrile is preferable in terms of easy availability, and inexpensive. And 1,3-dichlorobenzene is more preferred.

Specific examples of the compound represented by the general formula (14) include 1,4-dichlorobenzene, 1,4-dibromobenzene, 1,4-diiodobenzene, 2,5-dichlorotoluene, and 2,5-dichlorotoluene. Dibromotoluene, 2,5-diiodotoluene, 2,5-dichloro-1,4-dimethylbenzene, 2,5-dibromo-1,4-dimethylbenzene, 2,5-diiodo-1,4-dimethylbenzene, 2,5-dichloro-1,3-dimethylbenzene, 2,5-dibromo-1,3-dimethylbenzene, 2,5-diiodo-1,3-dimethylbenzene, 2,5-dichlorobenzonitrile, and 2, 5-dichlorofluorobenzene and the like. These may be used alone or in combination of two or more. Of these, 1,4-dichlorobenzene, 2,5-dichlorotoluene, and 2,5-dichlorobenzonitrile are preferred because they are easily available, and 1,4-dichlorobenzene is more preferred because it is inexpensive. preferable.

As the transition metal compound, a nickel-based compound and a palladium-based compound are preferably used, and more preferably, a zero-valent nickel complex such as bis (1,5-cyclooctadiene) nickel and tetrakistriphenylphosphine nickel is used. . Further, a divalent nickel compound such as nickel chloride, nickel bromide, and dichlorobistriphenylphosphine nickel may be used in the presence of a reducing agent such as zinc. A zero-valent nickel complex has high activity in the coupling reaction, but is expensive, sensitive to moisture and oxygen, and requires careful handling. On the other hand, the divalent nickel compound is inexpensive, though slightly active, and is stable to moisture and oxygen, so that it is easy to handle.

Also, a boronic acid functional group is introduced into one of a precursor of a sulfonic acid group-containing hydrophilic segment and a precursor of a hydrophobic segment, and a halogen is introduced into the other, and Suzuki-Miyaura coupling using a palladium catalyst is performed. Reactions can also be used.

As the solvent for the polymerization reaction, a solvent which dissolves a reactant such as a precursor of a hydrophobic segment and a precursor of a sulfonic acid group-containing hydrophilic segment, and a polymer electrolyte to be produced are preferable. Examples thereof include a hydrocarbon solvent, a halogen solvent, an ether solvent, a ketone solvent, an amide solvent, a sulfone solvent, and a sulfoxide solvent. Among these, from the viewpoint of the solubility of the produced polymer electrolyte, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone and the like are preferred. Amide solvents, halogen solvents such as dichlorobenzene and trichlorobenzene, and sulfur solvents such as dimethyl sulfoxide are preferred. One of these polymerization reaction solvents may be used alone, or two or more thereof may be mixed.

行う When performing a coupling reaction using a transition metal compound, it is preferable to dehydrate the reaction system. The method of dehydration is not particularly limited, but a method of mixing an azeotropic solvent with the above-mentioned solvent and heating to carry out azeotropic dehydration is preferably used.

The azeotropic solvent is not particularly limited, but benzene, toluene, xylene, hexane, cyclohexane, octane, chlorobenzene, dioxane, tetrahydrofuran and the like can be used, and are appropriately selected according to the solvent for the polymerization reaction.

The azeotropic dehydration depends on the boiling point of the azeotropic solvent, but is preferably performed in the range of 100 to 200 ° C. If the temperature is lower than 100 ° C., the dehydration rate is too slow to be practical.

When a compound having a structure represented by the general formula (13) and / or a compound having a structure represented by the general formula (14) is used, some of the compounds evaporate depending on a dehydration temperature. In some cases, the polymerization yield may be reduced, or a polymer electrolyte having an ion exchange capacity larger than the set value may be obtained. In such a case, it is preferable to add the compounds after cooling the mixture after dehydrating other components, since a high yield of the polymer electrolyte can be obtained.

When a divalent nickel compound or the like is used as a transition metal compound used for coupling, it is preferable to use a precursor of a sulfonic acid group-containing hydrophilic segment in which a sulfonic acid group is protected by an alkyl group or the like, If the temperature at the time of azeotropic dehydration is too high, the protecting group may be eliminated, which may inhibit polymerization. Also in such a case, it is preferable to cool the mixture after dehydrating other components and to add the sulfonic acid group-containing hydrophilic segment precursor, since a high molecular weight polymer can be obtained in a high yield.

In one or more embodiments of the present invention, the number average molecular weight of the polymer electrolyte is preferably from 1,000 to 500,000, more preferably from 5,000 to 200,000, and still more preferably from 7,000. １５０150,000, and even more preferably 7,000 ～ 100,000. If the number average molecular weight is less than 1,000, the strength when formed into a film tends to be insufficient. On the other hand, if it is more than 500,000, the solubility in a solvent tends to decrease, and the handleability tends to deteriorate. The number average molecular weight of the polymer electrolyte can be determined by the method described in Examples below.

において In one or more embodiments of the present invention, the polymer electrolyte has a sulfonic acid group of 0.5 to 4.0 meq. / G, preferably from 1.2 to 3.8 meq. / G is more preferable, and 1.4 to 3.6 meq. / G is more preferable, and 2.0 to 3.6 meq. / G is even more preferred. 0.5 meq. / G, the proton conductivity tends to be insufficient, and 4.0 meq. If it exceeds / g, it tends to be difficult to maintain the strength of the film.

In one or more embodiments of the present invention, in order to set the equivalent of the sulfonic acid group in the polymer electrolyte to the above-described range, the molar ratio of the repeating unit of the hydrophobic segment to the repeating unit of the hydrophilic segment in the polymer electrolyte may be adjusted. When the polymer electrolyte has a structure represented by the general formula (3), x / y is preferably 0.15 to 3.5, and more preferably 0.40 to 3.0. More preferably, it is more preferably 0.80 to 2.5.

The polymer electrolyte of the present invention can be used in various industries. The use (use) of the polymer electrolyte is not particularly limited, but may be a polymer electrolyte membrane, a catalyst layer for a fuel cell, or a membrane for a fuel cell. Suitable for electrode assemblies and fuel cells.

において In one or more embodiments of the present invention, the polymer electrolyte membrane is obtained by forming the above-mentioned polymer electrolyte into a membrane by any method. A known method can be appropriately used as such a film forming method. Examples of the known methods include melt extrusion molding such as hot press method, inflation method, T-die method and the like, and film forming method from solution such as casting method and emulsion method. For example, the casting method is a method in which a solution of a polymer electrolyte whose viscosity has been adjusted is applied to a flat plate such as a glass plate using a bar coater, a blade coater, or the like, and a solvent is vaporized to obtain a film. Industrially, a method of continuously applying a solution from a coat die onto a belt and evaporating the solvent to obtain a long product is also a general casting method.

Conventionally, a high-boiling aprotic polar solvent has been used for the casting of a hydrocarbon-based electrolyte by casting. Typical examples thereof include dimethyl sulfoxide, N-methylpyrrolidone, N, N-dimethylformamide, and N, N-. Dimethylacetamide and the like have been used. These are good solvents for hydrocarbon-based electrolytes, but because of their high boiling points, there is a problem that drying after casting requires a high temperature and a long time. Further, since a certain amount of solvent remains in the film even after drying, it was necessary to remove the film by washing it with water or the like. The polymer electrolyte in the present invention dissolves not only in the above-mentioned aprotic solvent but also in low-boiling alcohols such as methanol, ethanol, and isopropanol. For this reason, drying after casting is completed at a relatively low temperature and in a short time, and hardly remains in the film, so that post-processing such as washing with water can be omitted.

In order to control the molecular orientation of the polymer electrolyte membrane, the obtained polymer electrolyte membrane may be subjected to a treatment such as biaxial stretching, or may be subjected to a heat treatment for controlling the crystallinity. . In addition, various fillers may be added to improve the mechanical strength of the polymer electrolyte membrane, or a reinforcing agent such as a glass nonwoven fabric and the polymer electrolyte membrane may be combined by pressing.

任意 The thickness of the polymer electrolyte membrane can be arbitrarily selected depending on the application. For example, in consideration of reducing the internal resistance of the obtained polymer electrolyte membrane, the thinner the polymer electrolyte membrane, the better. On the other hand, in consideration of the gas barrier properties and the handling properties of the obtained polymer electrolyte membrane, if the thickness of the polymer electrolyte membrane is too small, it may not be preferable. Taking these into consideration, the thickness of the polymer electrolyte membrane is preferably 5 to 300 μm, more preferably 10 to 100 μm, and particularly preferably 10 to 50 μm when emphasis is placed on output as a fuel cell. When the thickness of the polymer electrolyte membrane is 5 to 300 μm, the production is easy, the membrane resistance and the mechanical properties are well balanced, and the handling property when processing as a fuel cell material is excellent.

In addition, in order to further improve the characteristics of the polymer electrolyte membrane, it is possible to irradiate radiation such as an electron beam, γ-ray, or ion beam. As a result, a crosslinked structure or the like can be introduced into the polymer electrolyte membrane, and the performance may be further improved. Various surface treatments such as a plasma treatment and a corona treatment can also improve properties such as increasing the adhesiveness of the polymer electrolyte membrane surface to the catalyst layer.

高分子 The polymer electrolyte membrane has an ion exchange capacity (IEC) of 0.5 to 4.0 meq. / G, preferably from 1.2 to 3.8 meq. / G, more preferably 1.4 to 3.6 meq. / G, more preferably 2.0 to 3.6 meq. / G is even more preferred. 0.5 meq. / G, the proton conductivity tends to be too low. / G, the mechanical strength tends to be significantly reduced due to swelling with water.

In one or more embodiments of the present invention, in order to keep the ion exchange capacity (IEC) of the polyelectrolyte in the above-described range, the molar ratio of the repeating unit of the hydrophobic segment to the repeating unit of the hydrophilic segment in the polyelectrolyte may be adjusted. When the polymer electrolyte has a structure represented by the general formula (3), x / y is preferably 0.15 to 3.5, and more preferably 0.40 to 3.0. More preferably, it is more preferably 0.80 to 2.5.

The polymer electrolyte membrane of the present invention obtained as described above has a hydrophobic segment having a structure represented by the general formula (1) and a hydrophilic segment having a sulfonic acid group and a main chain mainly composed of an aromatic ring. Since the segment is obtained from a polymer electrolyte connected by a direct bond of an aromatic ring, it has high chemical durability and can withstand severe oxidizing conditions during fuel cell operation.

Although the chemical durability of the polymer electrolyte membrane can be evaluated by various test methods, a Fenton test using hydrogen peroxide solution (Fenton test), which is a test for evaluating resistance to oxidative deterioration, is simple and preferable. Used. The Fenton test shows specific test conditions in the examples described later. An electrolyte membrane of an appropriate size is immersed in a certain concentration of hydrogen peroxide containing a small amount of iron (II) sulfate, and heated for a certain time. After the test, the weight, molecular weight, ion exchange capacity and the like of the test piece are measured, and the retention rate before the test is recorded.

Many conventional hydrocarbon-based electrolyte membranes contain an ether group, a carbonyl group, a sulfone group, or the like in the main chain, and the retention of physical properties after the Fenton test is extremely low. On the other hand, the polymer electrolyte membrane of the present invention has a high retention even after the Fenton test because of having the above structure. In order to withstand the operating conditions of the fuel cell, weight retention after the Fenton test, specifically, treatment at 80 ° C. for 1 hour in a Fenton solution (3% H ₂ O ₂ containing 2 ppm FeSO ₄ ) The ratio is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. If the weight retention is less than 80%, the decomposition of the membrane will proceed, the proton conductivity will decrease, and the fuel gas will crossover due to the rupture of the membrane, which may hinder the operation of the fuel cell.

において In one or more embodiments of the present invention, the fuel cell catalyst layer contains the above-mentioned polymer electrolyte. Specifically, the fuel cell catalyst layer is composed of the polymer electrolyte, the fuel cell catalyst, and, if necessary, a water repellent or a binder resin. By using the polymer electrolyte of the present invention, excellent power generation characteristics suitable for an anode or cathode catalyst layer of a polymer electrolyte fuel cell or a direct methanol fuel cell can be exhibited.

The fuel cell catalyst may be any fuel cell catalyst conventionally known to those skilled in the art, and may be any as long as it contains a conductive catalyst carrier and a catalytically active substance supported on the conductive catalyst carrier. The configuration is not particularly limited. Specifically, a catalyst that is active for the electrode reaction of the fuel cell is used. On the anode side, a catalyst capable of oxidizing a fuel (eg, hydrogen or methanol) is used. On the cathode side, a catalyst capable of reducing an oxidizing agent (such as oxygen) is used.

Specific examples of the conductive catalyst carrier include a carbon carrier having a high surface area such as carbon black, Ketjen black (trade name), activated carbon, carbon nanohorn, and carbon nanotube. These materials are preferable from the viewpoint of chemical stability and the like.

Specific examples of the catalytically active substance include platinum, cobalt, ruthenium and the like. These may be used singly or as an alloy containing at least one of these, or even as an arbitrary mixture. I do not care. In particular, in consideration of the oxidizing ability of the fuel, the reducing ability of the oxidant, and the durability, platinum or an alloy containing platinum is preferable. These may be composed of three or more components using iron, tin, a rare earth element or the like for stabilization and prolonging the life as needed.

In one or more embodiments of the present invention, the fuel cell catalyst layer is prepared by applying a catalyst ink containing the polymer electrolyte, the fuel cell catalyst and a solvent on a support, and removing the solvent. Can be. As the solvent, any solvent can be used as long as it can dissolve the polymer electrolyte and does not poison the fuel cell catalyst. The catalyst ink may contain additives such as a non-electrolyte binder, a water repellent, a dispersant, a thickener, and a pore-forming agent, if necessary. As these additives, those conventionally known to those skilled in the art can be used, and other specific configurations are not particularly limited.

塗布 The above-mentioned catalyst ink can use the following coating method depending on the viscosity and the type of the base material. The method for applying the catalyst ink to the substrate is not particularly limited as long as it is a method conventionally known to those skilled in the art. For example, a method using a knife coater, a bar coater, a spray, a dip coater, a spin coater, a roll coater, a die coater, a curtain coater, screen printing, etc. can be listed, but not limited thereto.

In the above, when the polymer film is used as the base material, the catalyst layer transfer sheet for the fuel cell is manufactured, and when the conductive porous sheet is used as the base material, the gas diffusion electrode for the fuel cell is manufactured. it can.

において In one or more embodiments of the present invention, a fuel cell membrane / electrode assembly (hereinafter, referred to as “MEA”) is formed using the polymer electrolyte or the polymer electrolyte membrane. Such an MEA can be suitably used, for example, for a polymer electrolyte fuel cell. The method of fabricating the MEA is based on a conventionally studied polymer electrolyte membrane made of perfluorocarbon sulfonic acid and other hydrocarbon polymer electrolyte membranes (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfone A known method performed with oxidized polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, or the like can be applied.

以外 In addition to the examples described above, the above-mentioned polymer electrolyte can be used as an electrolyte of a polymer electrolyte fuel cell known in, for example, JP-A-2006-179298. Based on these known patent documents, those skilled in the art can easily construct a polymer electrolyte fuel cell using the polymer electrolyte of the present invention.

Example Hereinafter, an example will be shown, and the embodiment of the present invention will be described in more detail. The present invention is not limited to the following embodiments, and it goes without saying that various embodiments are possible in detail. Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining the disclosed technical means are also described. Included in the technical scope of the invention.

Each measurement was performed as follows.

(Measurement of molecular weight)
The molecular weight was measured by the GPC method under the following conditions.
Column: KF-805L (manufactured by Showa Denko KK)
Detector: Jasco 805 UV detector Mobile phase solvent: DMF (dimethylformamide, LiBr added to 0.05M)
Standard substance: below standard polystyrene, the number average molecular weight in terms of standard polystyrene is denoted as Mn, and the weight average molecular weight in terms of standard polystyrene is denoted as Mw.

(Measurement of ion exchange capacity)
The section of the polymer electrolyte membrane was immersed in a 2 M aqueous NaCl solution for 24 hours. Hydrochloric acid released by ion exchange was quantified using a 0.01 M NaOH aqueous solution, and the ion exchange capacity IEC value was calculated using the following equation. In the following formula, NaOH (l) is the volume (L) of the NaOH aqueous solution used for quantification, and W _dry (g) is the weight (g) of the section of the polymer electrolyte membrane (after drying) used for measurement. It is.

(Fenton test)
A polymer electrolyte membrane of about 1 × 3 cm (about 30 mg) was prepared. The polymer electrolyte membrane was placed in 50 mL of a Fenton solution (3% H ₂ O ₂ containing 2 ppm of FeSO ₄ ) and immersed at 80 ° C. for 1 hour to perform a Fenton test. The polymer electrolyte membrane after the Fenton test was dried, the weight, the molecular weight, and the ion exchange capacity were measured, and the retention from the value before the Fenton test was calculated.

(Proton conductivity)
The proton conductivity of the polymer electrolyte membrane was measured using an electrolyte evaluation apparatus “MSB-AD-V-FC” manufactured by Bell Japan. The temperature in the chamber was constant at 80 ° C., and the test was performed under the conditions of 20% relative humidity (RH), 40% RH, 60% RH, 80% RH, and 90% RH. The measurement was performed using RH 20% → RH 40% → RH 60% → RH 80% → RH 90% → RH 80% → RH 60% → RH 40% → RH 20% as one cycle. The sample size of the polymer electrolyte membrane was 1.0 cm × 3.0 cm, the distance between the Au probes was 1.0 cm, and an AC four-terminal method (300 mV, using Solartron 1255B / 1287 (manufactured by Toyo Corporation). (1-100,000 Hz). As the impedance Z, a value having a phase angle close to 0 ° and a value close to 1000 Hz according to a Bode plot was used. The conductivity σ (S / cm) was calculated by the following equation.
σ = (L / Z) × 1 / A
Here, L is the distance between Au probes (1.0 cm), and A is the cross-sectional area of the sample (1 cm × film thickness Xcm).

(Dynamic viscoelasticity)
The dynamic viscoelasticity of the polymer electrolyte membrane (0.5 cm × 3 cm) was measured using a dynamic viscoelasticity measuring apparatus “DVA-225” manufactured by IT Measurement Control Co., Ltd. Storage elastic modulus (E ′), loss elastic modulus (E ″), and loss tangent from 0% RH to 90% RH at a humidity rise rate of 1% RH / min at a constant measurement frequency of 10 Hz and 80 ° C. (Tan δ) were obtained. The measurement was performed for three cycles, and the data of the third cycle was used.

(Open circuit voltage endurance test (OCV endurance test))
A fuel cell used for the test was produced as follows. Pt / CB catalyst (“TEC10E50E” manufactured by Tanaka Kikinzoku Kogyo), Nafion® dispersion liquid (“D-521” manufactured by Dupont, IEC = 0.95 to 1.03 mmol / g), deionized water, ethanol Was mixed for 30 minutes using a ball mill to obtain a catalyst paste. The weight ratio of the Nafion (registered trademark) binder to the carbon carrier was adjusted to 0.7. A catalyst paste was spray-coated on both sides of the polymer electrolyte membrane, dried at 60 ° C. for 12 hours, and hot-pressed at 140 ° C. and 10 kgf for 3 minutes to form a catalyst-coated electrolyte membrane (CCM). The effective area of the catalyst layer, and the amount of platinum supported, respectively, 4.41Cm ^2, was 0.50 ± 0.02mg / cm ^2. The CCM was sandwiched between gas diffusion layers ("29BC" made of SGL carbon), and both the anode and cathode were incorporated into a cell having a carbon separator having a serpentine gas flow path. An OCV durability test was performed at 80 ° C. and a relative humidity of 30% for 1000 hours using the above cell. The flow rates of pure hydrogen and air were each 100 mL / min.

(Gas permeability)
Hydrogen and oxygen permeability were measured using a gas permeability tester “GTR-20XFYC” manufactured by GTR-tech and a gas chromatograph tester “G2700T” manufactured by Yanaco equipped with a Porapak Q column and a heat conduction detector. It was measured. Argon and helium were used as carrier gases for hydrogen and oxygen permeability measurements, respectively. A polymer electrolyte membrane was placed at the center of a cell having a gas inlet and an outlet, and a test gas was supplied to one side of the polymer electrolyte membrane and a carrier gas was supplied to the other side. In order to keep the humidity of the polymer electrolyte membrane uniform, the humidity conditions of the test gas and the carrier gas were set to be the same. A sample of the flow gas was collected, and the test gas that had passed through the polymer electrolyte membrane was quantified using a gas chromatograph. The gas permeability coefficient Q [cm ³ (STD) cm · cm ⁻² · S ⁻¹ · cmHg ⁻¹ ] of the polymer electrolyte membrane was calculated according to the following equation.
Q = 273 / T × 1 / A × B × 1 / t × l × 1 / (76-P _H2O )
Here T (K) is the absolute temperature, A (cm ²⁾ is transparent area, B (cm ³⁾ is the volume of permeated gas, t (s) is the sampling time, l (cm) is thickness, P _{H2 O} ( cmHg) represents the water vapor pressure.

(Solubility in ethanol)
A polymer electrolyte membrane (about 30 mg) of about 1 × 3 cm was put in a screw tube, about 10 mL of ethanol was added thereto, the vessel was sealed, and left at room temperature (20 ± 5 ° C.) for 24 hours. The solubility of the electrolyte was visually determined according to the following criteria.
A: completely dissolved B: insoluble

<Synthesis example 1 of hydrophobic segment precursor>
2,2-bis (4-chlorophenyl) hexafluoropropane was synthesized according to the method described in the literature (Macromolecules 1999, 32, 6418). Specifically, dichlorotriphenylphosphorane (35.7 g, 107 mmol, PPh ₃ Cl ₂ ) and 4,4 ′-(hexafluoroisopropylidene) diphenol (18.1 g, 53.6 mmol) were placed in a 250 mL flask. I charged. The reaction vessel was heated at 350 ° C. for 4 hours using a mantle heater. The brown reaction product was cooled to room temperature and dissolved in methylene chloride. The solution was passed through a short column of aluminum oxide using hexane as eluent. The solvent was distilled off to obtain the desired compound (12.4 g, 62%). The reaction formula is as follows.

<Example 1>
2,2-bis (4-chlorophenyl) hexafluoropropane (0.298 g, 0.8 mmol) obtained in Synthesis Example 1 was placed in a 100 mL three-neck flask equipped with a Liebig condenser and a Dean stack trap under a nitrogen atmosphere. , 2,5-dichlorobenzenesulfonic acid (0.50 g, 1.9 mmol), potassium carbonate (0.316 g, 2.28 mmol), 2,2′-bipyridyl (1.78 g, 11.34 mmol), dimethylsulfoxide ( 6 mL) and toluene (6 mL). After the mixture was azeotropically dehydrated at 170 ° C. for 2 hours, toluene was distilled off, and the mixture was cooled to 80 ° C. Bis (1,5-cyclooctadiene) nickel (0) (1.56 g, 5.67 mmol) was added, and the mixture was stirred at 80 ° C. for 3 hours. The mixture was added to a large excess of 6M hydrochloric acid and reprecipitated. The crude product was washed several times with concentrated hydrochloric acid and further with ion-exchanged water, and dried overnight in a vacuum drier at 80 ° C. to obtain a polymer electrolyte in a yield of 94%. The reaction formula is as follows.

The polymer electrolyte obtained above is dissolved by heating and stirring in DMSO, impurities are removed by a glass filter G3, the polymer solution is poured into a glass plate bordered with silicon rubber, and dried by heating on a hot plate at 60 ° C. did. The obtained film was treated overnight in a 1 mol / L sulfuric acid aqueous solution, and then washed with pure water to obtain a film having a thickness of about 25 μm. This membrane was sandwiched using a membrane filter and a glass plate, placed on a weight, and dried in the air until water disappeared to obtain a polymer electrolyte membrane.

<Example 2>
A polymer electrolyte was prepared by performing polymerization in the same manner as in Example 1 except that the amount of the compound used was changed as follows, and the film thickness before drying was about 25 μm in the same manner as in Example 1. Was obtained. 2,2-bis (4-chlorophenyl) hexafluoropropane (0.298 g, 0.8 mmol) obtained in Synthesis Example 1, 2,5-dichlorobenzenesulfonic acid (0.368 g, 1.4 mmol), potassium carbonate (0.232 g, 1.68 mmol), 2,2′-bipyridyl (1.45 g, 9.24 mmol), dimethyl sulfoxide (6 mL), toluene (6 mL), bis (1,5-cyclooctadiene) nickel (0 ) (1.27 g, 4.62 mmol).

<Example 3>
A polymer electrolyte was prepared by performing polymerization in the same manner as in Example 1 except that the amount of the compound used was changed as follows, and the film thickness before drying was about 25 μm in the same manner as in Example 1. Was obtained. 2,2-bis (4-chlorophenyl) hexafluoropropane (0.560 g, 1.5 mmol), 2,5-dichlorobenzenesulfonic acid (0.289 g, 1.1 mmol) obtained in Synthesis Example 1, potassium carbonate (0.182 g, 1.32 mmol), 2,2′-bipyridyl (1.71 g, 10.92 mmol), dimethyl sulfoxide (6 mL), toluene (6 mL), bis (1,5-cyclooctadiene) nickel (0 ) (1.50 g, 5.46 mmol).

<Comparative Example 1>
1,4-phenylenediboronic acid (9.76 g, 58.9 mmol), 1-bromo-3-iodobenzene (50.0 g, 177 mmol) in a 1 L one-neck flask equipped with a Liebig condenser and purged with nitrogen. , Tri (o-tolyl) phosphine (1.34 g, 4.42 mmol), 2M aqueous potassium carbonate solution (100 mL, 200 mmol), toluene (320 mL) and ethanol (120 mL). Then, palladium acetate (198 mg, 0.883 mmol) was added to the obtained suspension, and the mixture was stirred at 80 ° C for 18 hours. The reaction mixture was allowed to cool to room temperature, diluted with ultrapure water and toluene, and filtered to remove insolubles using Celite (registered trademark). After separating two layers of the filtrate, the aqueous layer was extracted with toluene, and the combined organic layers were concentrated under reduced pressure. When methanol was added to the obtained residue and ultrasonic waves were applied, a solid was deposited. The resulting solid was collected by filtration, washed with methanol and dried at 60 ° C. under reduced pressure to obtain 3,3 ″ -dibromo-p-terphenyl as a pale yellow solid as an intermediate (15.6 g, 68). %yield). The reaction formula is as follows.

In a 500 mL one-neck flask equipped with a Liebig condenser and purged with nitrogen, 3,3 ″ -dibromo-p-terphenyl (15.6 g, 40.2 mmol) obtained above, 3-chlorophenylboronic acid ( 25.2 g, 161 mmol), sodium carbonate (17.1 g, 161 mmol), DMF (120 mL) and ultrapure water (160 mL) were added. Then, palladium acetate (903 mg, 4.02 mmol) was added to the obtained suspension, and the mixture was stirred at 60 ° C for 24 hours. The reaction mixture was allowed to cool to room temperature, diluted with ultrapure water and toluene, and filtered to remove insolubles using Celite (registered trademark). The filtrate was washed with ultrapure water and concentrated under reduced pressure. Methanol was added to the obtained residue, and ultrasonic waves were applied thereto. The resulting gray solid was collected by filtration, washed with methanol, and the obtained solid was re-dissolved in ethyl acetate / dichloromethane (volume ratio: 1/2, about 700 mL). Dissolve and remove impurities by adding activated carbon (about 2 g). After filtering off the activated carbon, the filtrate was dried under reduced pressure to give 3,3 ″ ″-dichloro-1,1 ′: 3 ′, 1 ″: 4 ″, 1 ′ ″: 3 ″. ', 1''''-Kinkphenyl was obtained as a white solid (14.2 g, 78% yield). The reaction formula is as follows.

Into a 100 mL three-necked flask equipped with a Liebig condenser and Dean stack trap and purged with nitrogen, 2,5-dichlorobenzenesulfonic acid dihydrate (2.5 mmol) and the kink phenyldichloro monomer obtained above (1.1 mmol), 2,2′-bipyridyl (11 mmol) and potassium carbonate (2.8 mmol) were added and dissolved in dimethyl sulfoxide (DMSO) (22 mL). For the dehydration operation, dehydrated toluene (4 mL) was added as an azeotropic agent. First, the temperature was raised to 170 ° C., and the dehydration operation was performed for 2 hours. After removing water and toluene, the temperature was lowered to 80 ° C., and bis (1,5-cyclooctadiene) nickel (0) (11 mmol) was added to start a coupling polymerization reaction. After the reaction for 3 hours, the mixture was allowed to cool and dropped into methanol. The obtained black solid was washed twice with hydrochloric acid and three times with pure water, and dried under vacuum to obtain a yellow polymer in a yield of 97%. The reaction formula is as follows.

高分子 A polymer electrolyte membrane having a thickness of about 25 μm before drying was obtained in the same manner as in Example 1 except that the polymer obtained above was used.

<Comparative Example 2>
In a 500 mL four-necked flask equipped with a reflux tube and a Dean Stark tube, 4,4′-dichlorodiphenylsulfone (31.6 g, 110 mmol), 4,4′-dihydroxybenzophenone (21.4 g, 100 mmol), potassium carbonate ( 20.7 g, 150 mmol), dimethylacetamide (200 mL), and toluene (50 mL). The mixture was heated to 170 ° C. and stirring was continued for 35 hours while removing generated water. 4,4′-Dichlorodiphenyl sulfone (0.5 g) was added, and the mixture was further stirred for 5 hours. After the mixture was filtered using filter paper to remove excess potassium carbonate, the filtrate was poured into 500 mL of methanol to reprecipitate the product. The product was dried under reduced pressure at 70 ° C. for 4 hours, then washed twice with 500 mL of pure water at 60 ° C., further once with 500 mL of methanol at 60 ° C., and overnight at 70 ° C. under reduced pressure. After drying, 41.5 g of a hydrophobic oligomer was obtained by the reaction represented by the following reaction formula. The molecular weight measured by the GPC method was Mn = 5400 and Mw = 13900.

Into a 2 L three-necked flask equipped with a Liebig condenser and a Dean stack trap and purged with nitrogen, sodium 2,5-dichlorobenzenesulfonate (31.36 g, 126 mmol), the hydrophobic oligomer obtained above (16 g) , 3.5 mmol), 2,2′-bipyridyl (47.68 g, 306 mmol), dimethyl sulfoxide (704 mL), and toluene (176 mL), and the mixture was dehydrated at 170 ° C. for 2 hours. After removing water and toluene, the temperature was lowered to 80 ° C., and bis (1,5-cyclooctadiene) nickel (0) (40 g, 145.6 mmol) was added to initiate polymerization. After reacting for 2 hours, the mixture was allowed to cool, and the reaction product was poured into methanol (2 L) to cause reprecipitation. The obtained solid was washed with 6 mol / L hydrochloric acid (2 × 2 L), and then repeatedly washed with water until the filtrate became neutral. It was dried at 105 ° C. under reduced pressure to obtain 29.9 g of a target polymer (yield of crude product: 84%). The reaction formula is as follows.

<Comparative Example 3>
A commercially available perfluorosulfonic acid-based electrolyte membrane “Nafion (registered trademark) NRE212” (film thickness 50 μm) was used as Comparative Example 3.

Using the dried polymer electrolyte membranes obtained in Examples 1-3 and Comparative Examples 1-2, average molecular weight, ion exchange capacity (IEC), oxidation resistance (Fenton test), and solubility in ethanol Was evaluated according to the method described above. Further, the number of repeating units of the hydrophilic segment (x), the number of repeating units of the hydrophobic segment (y), and the molar ratio (x / y) thereof are defined as the number average molecular weight (Mn) of the polymer electrolyte. Calculated from IEC. The results are shown in Table 1 below.

データ From the data in Table 1, it was confirmed that the electrolyte membranes of Examples 1 to 3 can control IEC over a wide range by adjusting the charge ratio of the raw materials. In addition, similarly to the electrolyte membrane of Comparative Example 1 (Patent Document 5), which is known to have high oxidation resistance, it was found that the resistance to the Fenton test was high, that is, the resistance to oxidation degradation was high. On the other hand, in the electrolyte membrane of Comparative Example 2 having a hetero bond such as an ether bond in the molecular chain, the molecular chain was decomposed in the Fenton test, and the average molecular weight and IEC retention were extremely low. Further, the electrolytes of Examples 1 to 3 were dissolved in ethanol, but none of the electrolytes of Comparative Examples were dissolved in ethanol.

(4) The proton conductivity of the polymer electrolyte membranes of Examples 1 to 3 and Comparative Examples 1 to 3 was measured as described above. The result is shown in FIG.

As can be seen from FIG. 1, the polymer electrolyte membranes of Examples 1 to 3 have higher IEC and higher proton conductivity, and the polymer electrolyte membrane of Example 2 has the same IEC as that of Comparative Example 1 having the same IEC. It had high proton conductivity equivalent to that of the polymer electrolyte membrane. In addition, the polymer electrolyte membranes of Examples 1 and 2 exhibited higher proton conductivity in the region where the relative humidity was 40% or more than the polymer electrolyte membrane of Comparative Example 3 which is a commercially available product.

粘 The viscoelasticity of the polymer electrolyte membranes of Examples 1 and 2 and Comparative Examples 1 and 3 were measured as described above. The result is shown in FIG. 2A shows the storage modulus, FIG. 2B shows the loss modulus, and FIG. 2C shows the loss tangent.

From the data in FIG. 2, it was found that the polymer electrolyte membrane of the example had a small humidity dependence of viscoelasticity, similarly to the polymer electrolyte membrane of the comparative example, and mechanically operated under dry and wet conditions during fuel cell operation. It was suggested to be stable.

(4) The proton conductivity of the polymer electrolyte membranes of Examples 1 and 2 before and after the Fenton test was measured according to the method described above, and the results are shown in FIG.

分かる As can be seen from FIG. 3, the electrolyte membranes of Examples 1 and 2 showed little change in proton conductivity after the Fenton test compared with before the test (initial stage), and had high oxidation resistance.

(4) The viscoelasticity of the polymer electrolyte membranes of Examples 1 and 2 before and after the Fenton test was measured, and the results are shown in FIG. 4A shows the storage modulus, FIG. 4B shows the loss modulus, and FIG. 4C shows the loss tangent.

分かる As can be seen from FIG. 4, the dynamic viscoelasticity of the electrolyte membranes of Examples 1 and 2 after the Fenton test hardly changed compared to the initial stage, and the chemical durability was high.

Ｏ An OCV durability test was performed using the polymer electrolyte membranes of Example 2 and Comparative Example 1 as described above. The results are shown in FIG.

分かる As can be seen from FIG. 5, the open circuit voltage of the polymer electrolyte membrane of Example 2 was smaller than that of Comparative Example 1 over time, and the chemical durability was higher.

ガス The gas permeability of the polymer electrolyte membranes of Example 2, Comparative Examples 1 and 3 was measured as described above. FIG. 6 shows the result. FIG. 6A shows hydrogen permeability, and FIG. 6B shows oxygen permeability.

As can be seen from FIG. 6, the gas permeability of the polymer electrolyte membrane of Example 2 was slightly higher than the electrolyte membrane of Comparative Example 1, but was lower than that of the perfluorosulfonic acid-based electrolyte membrane of Comparative Example 3 (gas (High barrier property).

As described above, the polymer electrolyte of the present invention has high proton conductivity, excellent oxidation resistance and chemical durability, low mechanical properties of humidity dependency, and high gas barrier properties. Since it is easy to produce and has good solubility in alcohol solvents having a low boiling point, it has excellent moldability such as film formation and is suitable for an electrolyte membrane of a fuel cell.

Claims

A hydrophobic segment having a structure represented by the following general formula (1), and a hydrophilic segment having a sulfonic acid group and a main chain mainly composed of an aromatic ring, wherein the hydrophobic segment and the hydrophilic segment are aromatic rings. A polymer electrolyte characterized by being connected by a direct bond of

(In the general formula (1), R a and R b each independently represent a fluorine or perfluoroalkyl group, y represents an integer of 1 to 2,000, and hydrogen on the benzene ring is fluorine, an alkyl group, (It may be substituted with one or more selected from the group consisting of a perfluoroalkyl group, an aryl group, an aralkyl group, and a cyano group.)
The polymer electrolyte according to claim 1, wherein in the general formula (1), Ra and Rb are both trifluoromethyl groups.
高分子 The polymer electrolyte according to claim 1, wherein in the general formula, y is an integer of 6 to 500.
The polymer electrolyte according to any one of claims 1 to 3, wherein the hydrophilic segment has one or more structures selected from a group of structures represented by the following formula group (2).

(In the above formula group (2), w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 is an integer of 1 or more. P is an integer of 0 to 10, q represents an integer of 0 to 10, r represents an integer of 1 to 4. A represents at least one member selected from the group consisting of -CO-, -SO 2- , and -C (CF 3 ) 2- . D represents —CO—, —SO 2 —, —SO—, —CONH—, —COO—, — (CF 2 ) t — (t is an integer of 1 to 10), and —C (CF 3 ) represents at least one kind of structure selected from the group consisting of 2-, E is a direct bond, or-(CH 2 ) j- (j is an integer of 1 to 10), -C (CH 3 ) 2 Represents at least one structure selected from the group consisting of —, —O—, and —S—, where Ar 1 is —SO 3 H or —O (CH 2 ) z SO 3 H (z is 1 to 12) of It represents an aromatic group having a substituent represented by a number).)
5. The polymer electrolyte according to claim 1, wherein the hydrophilic segment has one or more structures selected from the group of structures represented by the following formula group (15).

(In the above formula group (15), w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 is an integer of 1 or more.)
The polymer electrolyte according to any one of claims 1 to 5, having a structure represented by the following general formula (3).

(In the general formula (3), x represents an integer of 1 to 2000, and y represents an integer of 1 to 2000.)
The method for producing a polymer electrolyte according to any one of claims 1 to 6, wherein
A compound having a structure represented by the following general formula (4) and one or more compounds having a structure selected from a structure group represented by the following formula group (5) are copolymerized in the presence of a transition metal compound. A method for producing a polymer electrolyte.

(In the general formula (4), Hal represents chlorine, bromine or iodine, R a and R b each independently represent a fluorine or a perfluoroalkyl group, and hydrogen on the benzene ring is fluorine or alkyl. Group, a perfluoroalkyl group, an aryl group, an aralkyl group, and a cyano group.

(In the formula group (5), Hal represents chlorine, bromine, or iodine, w represents an integer of 1 to 4, k and l each represent an integer of 0 to 4, and k + 1 represents 1 or more. P is an integer of 0 to 10, q is an integer of 0 to 10, r is an integer of 1 to 4. A is —CO—, —SO 2 —, and —C (CF 3 ) 2 -Represents at least one structure selected from the group consisting of-, wherein D is -CO-, -SO 2- , -SO-, -CONH-, -COO-,-(CF 2 ) t- (t is Represents an at least one structure selected from the group consisting of an integer of 1 to 10) and —C (CF 3 ) 2 —, wherein E is a direct bond or — (CH 2 ) j — (j is 1 to 10 integer), - C (CH 3) 2 -, - O-, and .Ar 1 representing at least one structure selected from the group consisting of -S- are, -SO 3 H, the -O (CH 2) z SO 3 H (z is an integer between 1 and 12) .M representing an aromatic group having a substituent represented by hydrogen, an alkali metal, an alkyl group having 1 to 12 carbon atoms, carbon Represents a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.)
(7) A polymer electrolyte membrane using the polymer electrolyte according to any one of (1) to (6).
が Ion exchange capacity (IEC) is 2.0 to 3.6 meq. The polymer electrolyte membrane according to claim 8, wherein the ratio is / g.
Fenton solution (2ppm 3% H 2 O 2 containing FeSO 4) of the weight retention ratio Fenton's test for 1 hour at 80 ° C. 95% or more according to claim 8 or 9, wherein the polymer electrolyte membrane in a.
A catalyst layer for a fuel cell using the polymer electrolyte according to any one of claims 1 to 6.
(7) A membrane / electrode assembly for a fuel cell using the polymer electrolyte according to any one of (1) to (6).
(7) A fuel cell using the polymer electrolyte according to any one of (1) to (6).