Polymer, electrolyte material, electrolyte membrane, electrolyte membrane equipped with catalyst layer, membrane electrode assembly, solid polymer fuel cell, and solid polymer electrolysis device

Abstract

Provided is a polymer comprising a structural unit A represented by formula (a1) and a structural unit B represented by formula (a2). [In formula (a1), IExG represents an ion exchange group, L1 represents a single bond or the like, x represents an integer of 1-10, and * represents a bond.] [In formula (a2), Ar1 represents an arylene group that does not have an ion exchange group, L2 represents a single bond or the like, y represents an integer of 3-20, and * represents a bond. The number of L2, which are single bonds, is an integer that is not less than 0.5y but is less than 1.0y.]

Description

Polymers, electrolyte materials, electrolyte membranes, electrolyte membranes with catalyst layers, membrane electrode assemblies, polymer electrolyte fuel cells, and polymer electrolyte water electrolyzers.

[0001] This disclosure relates to polymers, electrolyte materials, electrolyte membranes, electrolyte membranes with catalyst layers, membrane electrode assemblies, polymer electrolyte fuel cells, and polymer electrolyte water electrolyzers.

[0002] In recent years, fuel cells have been attracting attention as a highly energy-efficient new energy technology, driven by environmental concerns. Among them, polymer electrolyte fuel cells, which use polymer materials as electrolytes, are particularly noteworthy because they have a high maximum current density and operate at low temperatures, making them suitable as power sources for mobile devices such as automobiles and small-capacity power sources for portable electronic devices.

[0003] Fluorine-based polymers are known as electrolyte polymers used in polymer electrolyte fuel cells and water electrolysis (see, for example, Patent Document 1). Although fluorine-based polymers are widely used in electrolyte applications due to their high proton conductivity and excellent swelling resistance, they have the problems of being expensive and having a large environmental impact.

[0004] For these reasons, the development of electrolyte polymers that do not use fluorine is also progressing. For example, Patent Document 2 discloses an invention relating to a polymer electrolyte membrane made of a block copolymer containing one or more segments (A1) containing ionic groups and one or more segments (A2) that do not contain ionic groups.

[0005] Japanese Patent Publication No. 11-204119, International Publication No. 2013-031675

[0006] However, non-fluorinated polymers obtained by block copolymerization, such as those disclosed in Patent Document 2, do not necessarily possess sufficient proton conductivity. Increasing the proportion of ion exchange groups (ionic groups) can be considered to increase proton conductivity, but since increasing the number of ion exchange groups reduces the swelling resistance of the electrolyte membrane, it is not easy to achieve both proton conductivity and swelling resistance.

[0007] One aspect of the present disclosure aims to provide a polymer that has excellent proton conductivity as an electrolyte and excellent swelling resistance.

[0008] The present invention is as described in the claims, and the present disclosure provides the following [1] to

[15] in some aspects.

[0009] [1] A polymer comprising a structural unit A represented by the following formula (a1) and a structural unit B represented by the following formula (a2). [In formula (a1), IExG represents an ion-exchange group, L ２ ,

[0012] , , １ , ２ ,

[0010] , ２ , ,

[0011] , represents a single bond, -O-, -S- or -SO ２ -, x represents an integer from 1 to 10, and * represents a bond. A plurality of IExG may be the same or different from each other, and a plurality of L １ may be the same or different from each other. ] [In formula (a2), Ar １ represents an arylene group having no ion-exchange group, L ２ represents a single bond, -O-, -S- or -SO ２ -, y represents an integer from 3 to 20, and * represents a bond. A plurality of Ar １ may be the same or different from each other, and a plurality of L ２ may be the same or different from each other. However, the number of L ２ that is a single bond is an integer of 0.5y or more and less than 1.0y. ]

[0010] [2] The polymer according to [1], wherein the structural unit A contains at least one group selected from the group consisting of a sulfonic acid group, an alkylsulfonic acid group, a sulfonimide group, and salts thereof as the ion-exchange group.

[0011] [3] The polymer according to [1] or [2], wherein the structural unit B contains at least one group selected from the group consisting of a phenylene group, a naphthylene group, and a fluorene group, which may have a substituent, as the arylene group.

[0012] [4] The polymer according to any one of [1] to [3], wherein the constituent unit B has a structure in which at least three consecutive arylene groups are bonded together by single bonds.

[0013] [5] The polymer according to any one of [1] to [4], wherein the content of the constituent unit B is 25 to 75 mol% of the total amount of all constituent units that make up the polymer.

[0014] [6] A polymer according to any one of [1] to [5], comprising a plurality of polymer units including the constituent unit A and the constituent unit B, and having a crosslinking group that bonds with three or more of the polymer units.

[0015] [7] The polymer according to any one of [1] to [6], wherein the weight-average molecular weight is 40,000 to 500,000.

[0016] [8] Tetramethylsilane is used as the internal standard. １ A polymer according to any one of [1] to [7], having a peak in the range of 6.70 to 6.95 ppm in the 1H-NMR spectrum.

[0017] [9] The polymer according to any one of [1] to [8], wherein the ion exchange capacity is 1.0 to 3.5 mmol / g.

[0018]

[10] An electrolyte material containing the polymer described in any of [1] to [9].

[0019]

[11] An electrolyte membrane containing the polymer described in any of [1] to [9].

[0020]

[12] An electrolyte membrane with a catalyst layer, comprising the electrolyte membrane described in

[11] and a catalyst layer disposed on one or both sides of the electrolyte membrane.

[0021]

[13] A membrane electrode assembly comprising an electrolyte membrane as described in

[11] and an electrode layer disposed on one or both sides of the electrolyte membrane.

[0022]

[14] A polymer electrolyte fuel cell comprising the membrane electrode assembly described in

[13] .

[0023]

[15] A solid polymer water electrolysis apparatus comprising the membrane electrode assembly described in

[13] .

[0024] According to one aspect of this disclosure, it is possible to provide a polymer that has excellent proton conductivity as an electrolyte and excellent swelling resistance.

[0025] The following describes exemplary embodiments of this disclosure. However, this disclosure is not limited to the embodiments described below. In this specification, numerical ranges indicated using "~" indicate a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. Also, unless otherwise explicitly stated, the units of the numerical values ​​before and after "~" are the same. Furthermore, each configuration and parameter disclosed in this specification can be combined in any way, and the upper and lower limits described individually can be combined in any way.

[0026] <Polymer> The polymer of one embodiment (hereinafter also referred to as "polymer (P)") is a polymer comprising a constituent unit A represented by the following formula (a1) and a constituent unit B represented by the following formula (a2).

[0027]

[0028] In formula (a1), IExG indicates an ion exchange group, and L １ These are single bonds, -O-, -S-, or -SO ２ - indicates a hyphen, x represents an integer from 1 to 10, and * represents a combination. Multiple IExGs may be the same or different from each other, and multiple L １ They may be the same or different from one another.

[0029]

[0030] In formula (a2), Ar １ This indicates an arylene group that does not have an ion exchange group, L ２ These are single bonds, -O-, -S-, or -SO ２ - indicates a combination, y represents an integer from 3 to 20, and * indicates a combination. Multiple Ar １ These may be the same or different from each other, and there may be multiple L ２ These may be identical or different from each other. However, L is a single bond. ２The number is an integer between 0.5y and 1.0y, inclusive. For example, if y is 10, then L is a simple combination. ２ The number is an integer between 5 and 10 (inclusive).

[0031] Polymer (P) is a so-called electrolyte polymer and possesses excellent proton conductivity. Therefore, membranes formed by polymer (P) (polymer electrolyte membranes) exhibit excellent proton conductivity, and tend to exhibit even better proton conductivity in high-humidity environments (for example, under humidity levels of 80% RH or higher). The reason why polymer (P) possesses excellent proton conductivity is not clear, but it is presumed that polymer (P) contains a hydrophilic part composed of constituent unit A and a hydrophobic part composed of constituent unit B, and that the hydrophilic part, where ion exchange groups are densely concentrated, and the hydrophobic part, which has high water repellency, self-assemble in a higher-order structure, inducing a microphase separation structure, thereby forming good proton conduction paths within polymer (P). Furthermore, because polymer (P) contains a highly water-repellent constituent unit (constituent unit B) in its main chain, where single bonds account for a large proportion of the bonds between arylene groups containing benzene rings, the diffusion coefficient of water increases, and this is also presumed to contribute to the improvement of proton conductivity.

[0032] Polymer (P) also possesses excellent swelling resistance. Therefore, films formed from polymer (P) tend to have superior swelling resistance. The reason for this is not entirely clear, but as mentioned above, it is thought that because polymer (P) contains highly water-repellent structural units (structural units B) in its main chain, the penetration of water into the polymer is suppressed, resulting in superior swelling resistance when formed into a film.

[0033] Polymer (P) tends to exhibit excellent gas barrier properties when formed into a film. The reason for this is presumed to be as follows: Because the main chain of polymer (P) is composed of arylene groups containing benzene rings, the solubility of hydrogen and oxygen is low, and segmental motion is restricted, suppressing gas diffusion within the film. Therefore, it is thought to exhibit excellent gas barrier properties when formed into a film.

[0034] (Constituent Unit A) Constituent unit A contains an aromatic ring having an ion exchange group (IExG), and a linking group (L) at one end that bonds to other constituent units. １) has. Constituent unit A has an aromatic ring having an ion exchange group (IExG) as a linking group (L １ ) may have a continuous structure via a linkage. The linking group located at the end of constituent unit A is, for example, bonded to the aromatic ring of another constituent unit.

[0035] An ion-exchange group is a group that has the property of being able to exchange ions (e.g., cations) with other ions, and is also called an ionic group. Examples of ion-exchange groups include sulfonic acid groups, alkyl sulfonic acid groups, perfluoroalkyl sulfonic acid groups, sulfonimide groups, phosphonic acid groups, phosphate groups, and carboxyl groups, as well as their salts. As mentioned above, ion-exchange groups also include those that form salts with metal ions, etc.

[0036] Sulfonic acid groups and their salts include, for example, -SO ３ M １／ｑ (M represents H or a metal (for example, at least one selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, Al, Fe, Pt, Rh, Ru, Ir, and Pd), and q represents the valence of M (for example, an integer from 1 to 4).) The metal represented by M exists as an ion (cation), -SO ３ － It forms salt.

[0037] Alkyl sulfonic acid groups and their salts are, for example, -R １ SO ３ M １／ｑ It is represented by R １ R is an alkanediyl group, and from the viewpoint of obtaining better proton conductivity, its carbon number is preferably 1 to 12 (an integer). １ Specific examples include, for instance, a methylene group, a butane-1,4-diyl group, and a hexane-1,6-diyl group. M and q are as defined above.

[0038] Sulfonimide groups and their salts include, for example, -SO ２ NM １／ｑ SO ２ R ２ It is represented by R ２R is an alkyl group, and from the viewpoint of obtaining better proton conductivity, its number of carbon atoms is preferably 1 to 6 (an integer). ２ Specific examples include methyl, ethyl, and propyl groups. M and q are the same as above.

[0039] From the viewpoint of obtaining better proton conductivity, constituent unit A preferably contains at least one group selected from the group consisting of sulfonic acid groups, alkyl sulfonic acid groups, and sulfonimide groups, and their salts, as an ion exchange group, and more preferably contains at least one group selected from the group consisting of sulfonic acid groups and their salts. From a similar viewpoint, it is even more preferable that the majority of the multiple ion exchange groups present in constituent unit A are of the above-described preferred form, and it is particularly preferable that all of the multiple ion exchange groups present in constituent unit A are of the above-described preferred form.

[0040] From the viewpoint of obtaining better proton conductivity, the constituent unit A has a linking group (L １ ) as -SO ２ - is preferable. From a similar viewpoint, multiple linking groups (L) present in constituent unit A are preferable. １ It is even more preferable that the majority of these are of the above-described preferred embodiment.

[0041] Linking group (L) in constituent unit A １ ) is a linking group (L) that provides excellent flexibility. １ It is preferable that it contains -O- as a component.

[0042] Linking group (L) in constituent unit A １ ) are single bonds, -O- or -SO-, from the viewpoint of improving proton conductivity and flexibility. ２ - is preferable.

[0043] Linking group (L １ The bonding position of the ion exchange group is not particularly limited, but from the viewpoint of obtaining better proton conductivity and chemical durability, it is preferable that it be located in the ortho or meta position relative to the ion exchange group. That is, it is preferable that the constituent unit A contains a 1,4-phenylene group having an ion exchange group.

[0044] The number of repeating structures (x) in the brackets [ ] in formula (a1) of constituent unit A is preferably 2 to 8, and more preferably 3 to 5, from the viewpoint of obtaining better proton conductivity and excellent resistance to hot water. The reason why proton conductivity improves when x is within the above range is not clear, but it is presumed to be due to the effect of the densely packed presence of multiple ion exchange groups.

[0045] From the viewpoint of obtaining better proton conductivity, it is preferable that the constituent unit A includes at least one structure selected from the group consisting of the structure represented by the following formula (a1-1) (hereinafter referred to as "structure (a1-1)"), the structure represented by the following formula (a1-2) (hereinafter referred to as "structure (a1-2)"), and the structure represented by the following formula (a1-3) (hereinafter referred to as "structure (a1-3)").

[0046]

[0047]

[0048]

[0049] In formulas (a1-1), (a1-2), and (a1-3), IExG, L １ And * are equivalent to those stated above. L in equation (a1-3) １１ x represents -O- or -S-. Multiple IExGs may be the same or different from each other. １ x represents an integer between 2 and 9, and x in equation (a1-2) ２ x represents an integer from 1 to 5, and x in equation (a1-3) ３ x represents an integer between 1 and 2. However, if the constituent unit A includes two or more structures selected from the group consisting of structures (a1-1), structures (a1-2), and structures (a1-3), x １ , 2x ２ (2 and x) ２ (product of) and 4x ３ (4 and x) ３ The sum of the products of x is between 4 and 9. １ From the viewpoint of obtaining better proton conductivity and excellent resistance to hot water, the ratio is preferably 2 to 5, and more preferably 2 to 3. ２From the viewpoint of obtaining better proton conductivity and excellent resistance to hot water, it is preferably 2 to 3, and more preferably 2. ３ From the viewpoint of obtaining better proton conductivity and excellent resistance to hot water, L is preferably 1. In formulas (a1-1), (a1-2), and (a1-3), １ From the viewpoint of improving proton conductivity and flexibility, it is preferable that it be -O-.

[0050] Constituent unit A may consist only of structure (a1-1), or it may include structure (a1-1) and structures other than structure (a1-1). Similarly, constituent unit A may consist only of structure (a1-2), or it may include structure (a1-2) and structures other than structure (a1-2). Similarly, constituent unit A may consist only of structure (a1-3), or it may include structure (a1-3) and structures other than structure (a1-3).

[0051] Constituent unit A may be a constituent unit represented by any of the following formulas (A1-1) to (A1-4).

[0052]

[0053] In formulas (A1-1) to (A1-4), IExG, * and L １ This is equivalent to the above, and L in formula (A1-2) １２ These are single bonds, -O-, -S-, or -SO ２ This indicates -. Multiple IExG may be the same or different from each other. Multiple L １ They may be the same or different from one another.

[0054] In polymer (P), the constituent unit A is preferably one of the constituent units represented by formulas (A1-1) to (A1-4), and more preferably the constituent unit represented by formula (A1-2), from the viewpoint of obtaining better proton conductivity and excellent chemical durability. １２ From the viewpoint of improving proton conductivity and chemical durability, it is preferable that it be a single bond. In this case, L in formula (A1-2) １From the viewpoint of improving proton conductivity and flexibility, it is preferable that it be -O-.

[0055] The multiple constituent units A in the polymer (P) may be identical or different from each other. From the viewpoint of obtaining better proton conductivity, it is preferable that the difference of x in formula (a1) among the multiple constituent units A is within 3, and it is more preferable that the multiple constituent units A are identical from each other.

[0056] From the viewpoint of obtaining better proton conductivity, the content of constituent unit A may be 20 mol% or more, 25 mol% or more, and may be 80 mol% or less, 75 mol% or less, or 50 mol% or less, relative to the total amount of all constituent units constituting the polymer (P). From a similar viewpoint, the content of constituent unit A may be 20 to 80 mol%, 25 to 75 mol%, or 25 to 50 mol%, relative to the total amount of all constituent units constituting the polymer (P).

[0057] (Constituent unit B) Constituent unit B is an arylene group (Ar) that does not have an ion exchange group. １ ) is a linking group (L ２ It has a continuous structure via ) and has a linking group (L) at one end that bonds to other constituent units. ２ ) has a connecting group (L) located at the end of constituent unit B. ２ ) is, for example, bonded to the aromatic ring of another constituent unit.

[0058] The arylene group is a divalent aromatic hydrocarbon group and has a structure obtained by removing two hydrogen atoms from a monocyclic or condensed polycyclic aromatic hydrocarbon. The number of aromatic rings in the arylene group is preferably 1 to 4 from the viewpoint of solubility in solvents, film-forming ability, and further improvement of swelling resistance. The arylene group may have substituents other than ion exchange groups. The substituent may be at least one group selected from the group consisting of aryl groups such as phenyl groups and cyano groups. When the arylene group has an aryl group as a substituent, the number of aromatic rings in the arylene group shall include the number of aromatic rings in the substituent.

[0059] The unsubstituted arylene group may be at least one group selected from the group consisting of phenylene, naphthylene, fluorene, anthracylene, phenanthrylene, triphenylene, pyrenylene, and tetracenylene groups. The substituted arylene group may be at least one group selected from the group consisting of diphenylfluorene, methylphenylene, ethylphenylene, cyanophenylene, dimethylfluorene, diethylfluorene, dipropylfluorene, diisopropylfluorene, dibutylfluorene, dipentylfluorene, dihexylfluorene, diheptylfluorene, dioctylfluorene, dinonylfluorene, didecylfluorene, diundecylfluorene, and didodecylfluorene groups. Note that the fluorene group as an arylene group refers to a divalent fluorene group (for example, a fluorene-2,7-diyl group).

[0060] From the viewpoint of solubility in the solvent, film-forming properties, and swelling resistance, it is preferable that the arylene group in the constituent unit B contains at least one group selected from the group consisting of phenylene, naphthylene, and fluorene groups, which may have substituents, and more preferably contains at least one group selected from the group consisting of phenylene, naphthylene, and fluorene groups, which may have an aryl group as a substituent. From the viewpoint of further improving solubility in the solvent and film-forming properties, it is more preferable that the constituent unit B contains a phenylene group, and even more preferable that it contains a 1,4-phenylene group. From the viewpoint of further improving swelling resistance, it is even more preferable that the constituent unit B contains a diphenylfluorene group. From a similar viewpoint, it is particularly preferable that the majority of the multiple arylene groups present in the constituent unit B are of the above-preferred embodiments, and it is extremely preferable that all of the multiple arylene groups present in the constituent unit B are of the above-preferred embodiments (for example, phenylene, naphthylene, or fluorene groups, which may have substituents).

[0061] Linking group (L) in constituent unit B ２From the viewpoint of obtaining superior swelling resistance and flexibility, as well as excellent solubility in solvents and film-forming properties, and excellent mechanical strength of the electrolyte membrane, the following are used: single bond, -O-, or -SO ２ - is preferable. However, the constituent unit B is a linking group (L ２ ) includes at least two single bonds. L is a single bond in constituent unit B. ２ The number is an integer between 0.5y and less than 1.0y, and may be an integer between 0.6y and 0.7y or more from the viewpoint of obtaining better swelling resistance, and may be an integer between 0.95y or less or 0.90y or less from the viewpoint of obtaining better flexibility. From these viewpoints, the single bond L in the constituent unit B ２ The number may be an integer between 0.6y and 0.95y or between 0.7y and 0.90y.

[0062] In the constituent unit B, the number of repeating structures (y) in the brackets [ ] in formula (a2) is an integer from 3 to 20, and is preferably 4 to 12, more preferably 5 to 10, from the viewpoint of obtaining better proton conductivity, better swelling resistance, and excellent heat and water resistance.

[0063] In the constituent unit B, the number of repeating structures (y) in the brackets [ ] in formula (a2) is preferably 2 to 7 more than the number of repeating structures (x) in formula (a1) (x + (2 to 7)), from the viewpoint of achieving both superior proton conductivity and resistance to hot water, and obtaining superior swelling resistance.

[0064] From the viewpoint of obtaining better proton conductivity, the number of aromatic rings in the main chain of constituent unit B is preferably 3 to 20, more preferably 4 to 12, and even more preferably 5 to 10.

[0065] From the viewpoint of obtaining better swelling resistance, it is preferable that constituent unit B includes a structure in which at least three consecutive arylene groups are linked by single bonds. From the viewpoint of obtaining even better swelling resistance, the number of consecutive arylene groups via single bonds may be four or more or five or more. From the viewpoint of obtaining better flexibility, the number of consecutive arylene groups via single bonds may be 10 or less, 8 or less, or 6 or less. From these viewpoints, the number of consecutive arylene groups via single bonds may be 3 to 10, 3 to 8, 3 to 6, 4 to 8, or 5 to 6.

[0066] Constituent unit B may be a constituent unit represented by any of the following formulas (A2-1) to (A2-6).

[0067]

[0068] * and L in equations (A2-1) to (A2-6) ２ This is equivalent to the above. R in equations (A2-3) and (A2-5) ３ R represents an alkyl group, and from the viewpoint of obtaining better proton conductivity, its carbon number is preferably 1 to 12 (an integer). ３ Specific examples include methyl, ethyl, propyl, hexyl, and dodecyl groups. In formulas (A2-3) and (A2-5), multiple R ３ They may be the same or different from one another.

[0069] From the viewpoint of obtaining better swelling resistance, the constituent unit B in polymer (P) is preferably one of the constituent units represented by formulas (A2-1) to (A2-6), and more preferably the constituent unit represented by formula (A2-4).

[0070] The multiple constituent units B in the polymer (P) may be identical or different from one another. From the viewpoint of obtaining better proton conductivity, it is preferable that the difference of y in formula (a2) among the multiple constituent units B be within 5, and it is more preferable that the multiple constituent units B are identical from one another.

[0071] From the viewpoint of obtaining better swelling resistance, the content of constituent unit B may be 25 mol% or more, 40 mol% or more, and 75 mol% or less, or 60 mol or less, based on the total amount of all constituent units that make up the polymer (P). From a similar viewpoint, the content of constituent unit B is preferably 25 to 75 mol%, and more preferably 40 to 60 mol%, based on the total amount of all constituent units that make up the polymer (P).

[0072] The polymer (P) may consist only of constituent units A and B, or it may contain constituent units other than constituent units A and B. An example of a constituent unit other than constituent units A and B is constituent unit C, which is represented by the following formula (a3).

[0073]

[0074] In formula (a3), Ar ２ L indicates an allerene group. ３ These are single bonds, -O-, -S-, or -SO ２ - indicates a combination, z represents an integer from 1 to 20, and * indicates a combination. Multiple Ar ２ These may be the same or different from each other, and there may be multiple L ３ They may be the same or different from one another.

[0075] The constituent unit C is an arylene group (Ar ２ ) includes a linking group (L) that is bonded to another constituent unit at one end. ３ ) has a constituent unit C is an arylene group (Ar ２ ) is a linking group (L ３ ) may have a continuous structure via a connecting group (L) located at the end of the constituent unit C. ３ ) is, for example, bonded to the aromatic ring of another constituent unit.

[0076] The arylene group may or may not have an ion-exchange group. Specific examples of the arylene group having an ion-exchange group are phenylene groups having one ion-exchange group. Specific examples of the ion-exchange group are the same as the specific examples of the ion-exchange group in the constitutional unit A described above. Specific examples of the arylene group having no ion-exchange group are the same as the specific examples of the arylene group in the constitutional unit B described above.

[0077] The constitutional unit C may be a constitutional unit in which all of the arylene groups (Ar ２ ) in the formula (a3) are arylene groups having no ion-exchange group. In this case, the number of linking groups (L ３ ) that are single bonds in the constitutional unit C is an integer less than 0.5z or equal to 1.0z.

[0078] The content of the constitutional unit C may be, for example, 1 to 40 mol%, 3 to 30 mol%, or 5 to 20 mol% with respect to the total of all constitutional units constituting the polymer (P).

[0079] The arrangement of each constitutional unit in the polymer (P) is not particularly limited. Each constitution may be arranged regularly or irregularly. For example, the polymer (P) may be a so-called precision arrangement polymer in which the constitutional unit A and the constitutional unit B, or the constitutional unit A, the constitutional unit B, and the constitutional unit C are alternately arranged, or a random polymer in which the constitutional unit A and the constitutional unit B, or the constitutional unit A, the constitutional unit B, and the constitutional unit C are irregularly arranged. From the viewpoint of facilitating the coexistence of more excellent proton conductivity and more excellent swelling resistance, the polymer (P) is preferably a random polymer. From the same viewpoint, it is preferable that each constitutional unit in the polymer (P) is arranged so that the same constitutional unit does not continue.

[0080] The polymer (P) may have, for example, a structure represented by the following formulas (1) to (6).

[0081]

[0082] In equations (1) to (6), * has the same meaning as described above. In equations (1) to (6), A and B represent constituent unit A represented by equation (a1) and constituent unit B represented by equation (a2), respectively, and n represents an integer from 10 to 100. In equations (2) to (6), X represents constituent unit X selected from constituent unit A represented by equation (a1), constituent unit B represented by equation (a2), and constituent unit C represented by equation (a3). In equations (4) to (6), l and m each independently represent a number from 0 to 1. Multiple A's may be the same or different from each other, multiple B's may be the same or different from each other, and multiple X's may be the same or different from each other. Furthermore, equation (4) means that blocks consisting of constituent units A and B (first block) and blocks consisting of constituent units X and B (second block) exist in a ratio of l:m, and that polymer (P) is composed of l × n first blocks and m × n second blocks. In equation (4), for convenience, (A - B) ｌ and (X-B) ｍ Although this is stated, it does not mean that the first block consists of l consecutive elements and the second block consists of m consecutive elements; the arrangement of the first and second blocks may be regular or irregular. The same applies to equations (5) and (6).

[0083] From the viewpoint of obtaining better proton conductivity and better swelling resistance, the polymer (P) preferably has a structure represented by any of formulas (1) to (6), and more preferably has a structure represented by formula (4) or (5).

[0084] The polymer (P) may consist of a polymer structure containing constituent units A and B, and terminal structures bonded to the structure. Examples of terminal structures include hydroxyl groups, thiol groups, halogen atoms, boronic acid groups, alkylborane groups, and boronic acid ester groups. Examples of halogen atoms include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). Examples of alkylborane groups include diethylborane, diciamilborane, dicyclohexylborane, and 9-borabicyclo[3.3.1]nonane. Examples of boronic acid ester groups include pinacol boronic acid ester, 1,3-propanediol boronic acid ester, biscyclohexyldiol boronic acid ester, neopentyl glycol boronic acid ester, and catechol boronic acid ester.

[0085] The polymer (P) may include a three-dimensional crosslinked structure formed by crosslinking a plurality of polymer units, including constituent unit A and constituent unit B, via a crosslinking group. The crosslinking group may be a group derived from a known crosslinkable compound (e.g., decafluorobiphenyl). If the crosslinking group has an aromatic ring, the polymer units may be directly crosslinked to the aromatic ring of the crosslinking group, or to -O-, -S-, or -SO ２ They may be bonded via a cross-linking group. The number of cross-linking groups may be one or more. The multiple cross-linking groups may be the same or different from each other.

[0086] The polymer (P) may contain fluorine atoms, but the fluorine content in the polymer (P) is preferably 5% by mass or less, and it is preferable that the polymer (P) does not contain fluorine atoms (the fluorine content is below the detection limit).

[0087] The number-average molecular weight of the polymer (P) may be 20,000 or more, 25,000 or more, or 30,000 or more from the viewpoint of superior proton conductivity and superior mechanical strength of the electrolyte membrane, and may be 300,000 or less, 200,000 or less, or 150,000 or less from the viewpoint of superior solubility in the solvent and film formation. From these viewpoints, the number-average molecular weight of the polymer (P) may be 20,000 to 300,000, 20,000 to 150,000, 25,000 to 200,000, or 30,000 to 150,000.

[0088] The weight-average molecular weight of polymer (P) may be 40,000 or more, 50,000 or more, 60,000 or more, or 100,000 or more from the viewpoint of superior proton conductivity and superior mechanical strength of the electrolyte membrane, and may be 500,000 or less, 300,000 or less, 200,000 or less, 150,000 or less, 100,000 or less, or 70,000 or less from the viewpoint of superior solubility in solvents and film formation. From these viewpoints, the weight-average molecular weight of polymer (P) may be 40,000 to 500,000, 50,000 to 300,000, 60,000 to 200,000, 60,000 to 100,000, 100,000 to 150,000, 100,000 to 500,000, or 40,000 to 70,000.

[0089] The ratio of the weight-average molecular weight to the number-average molecular weight of the polymer (P) (polydispersity) may be 1.5 or higher, and may be 2.0 or higher, 2.5 or higher, 2.8 or higher, or 3.0 or higher. When the polydispersity of the polymer (P) is 1.5 or higher, there is a tendency to obtain better swelling resistance, and when the polydispersity of the polymer (P) is 2.5 or higher, there is a tendency to obtain even better swelling resistance. From the viewpoint of solubility in the solvent, the polydispersity of the polymer (P) may be 20.0 or lower, and may be 15.0 or lower, 10.0 or lower, 7.0 or lower, 5.0 or lower, or 3.0 or lower. From these perspectives, the polydispersity of the polymer (P) may be 1.5–20.0, 1.5–10.0, 1.5–7.0, 1.5–5.0, 1.5–3.0, 2.0–20.0, 2.5–20.0, 2.5–15.0, 2.8–10.0, 3.0–10.0, 3.0–7.0, or 3.0–5.0.

[0090] The number-average molecular weight and weight-average molecular weight of the polymer (P) are measured by gel permeation chromatography (GPC) and are expressed as standard polyethylene glycol / oxide (PEG / PEO) equivalent values.

[0091] Polymer (P) uses tetramethylsilane as an internal standard. １ In the 1H-NMR spectrum, a peak may be present in the range of 6.70 to 6.95 ppm. If the peak is split into a doublet or other multiplet, the median value of the peak is taken as the chemical shift value of that peak. Polymers (P) that have such a peak tend to have excellent chemical durability. The above peak may originate from the ortho hydrogen atom of the hydroxyl group in the aromatic ring at the end of polymer (P). １ The 1H-NMR spectrum can be measured by the method described in the examples below.

[0092] The ion exchange capacity (IEC) of the polymer (P) may be 1.0 mmol / g or more, 1.5 mmol / g or more, 1.8 mmol / g or more, 2.0 mmol / g or more, or 2.2 mmol / g or more from the viewpoint of superior proton conductivity, and may be 3.5 mmol / g or less, 3.0 mmol / g or less, 2.8 mmol / g or less, 2.5 mmol / g or less, or 2.3 mmol / g or less from the viewpoint of superior swelling resistance. From these viewpoints, the ion exchange capacity of the polymer (P) may be 1.0 to 3.5 mmol / g, 1.5 to 3.0 mmol / g, 1.8 to 2.8 mmol / g, 1.5 to 2.5 mmol / g, 1.5 to 2.3 mmol / g, 2.0 to 2.3 mmol / g, or 2.2 to 3.0 mmol / g.

[0093] The ion exchange capacity of the polymer (P) is the value measured by the following procedures (1) to (7). (1) Dissolve the polymer (P) in dimethyl sulfoxide (DMSO) to obtain a solution containing 15% by mass of the polymer (P). (2) Cast and apply the obtained solution onto a glass substrate and dry it at 60 ° C for 12 hours to produce a film. (3) After immersing the obtained film in 1 M hydrochloric acid for 24 hours, immerse it in pure water for washing. (4) Dry the washed electrolyte membrane to obtain the dry mass. Drying is carried out until the mass reduction amount when the electrolyte membrane is heated at 80 ° C becomes 1% by mass / hour or less. For example, after drying under reduced pressure, heat at 80 ° C for 12 hours or more. (5) Immerse the dried film in a 20% by mass aqueous sodium chloride solution and stir for 24 hours for ion exchange. (6) Using a 0.01 M aqueous sodium hydroxide solution, titrate the hydrochloric acid generated by the above ion exchange with the end point being the point where the pH reaches 7. (7) Calculate the ion exchange capacity (IEC) of the polymer (P) by the following formula. IEC (unit: mmol / g) = {concentration of aqueous sodium hydroxide solution (unit: mol / L) × dropping amount (unit: mL)} / dry mass of electrolyte membrane (unit: g)

[0094] The polymer (P) can be obtained, for example, by reacting (polymerizing) monomers including a compound represented by the following formula (b1) (hereinafter also referred to as "compound (b1)") and a compound represented by the following formula (b2) (hereinafter also referred to as "compound (b2)"). That is, the polymer (P) can be a polymer of monomers including the compound (b1) and the compound (b2).

[0095]

[0096] In formula (b1), IExG, L １ and x have the same meanings as described above, and X １ｂ and X ２ｂ each independently represents a halogen atom. Examples of the halogen atom are the same as the examples of the halogen atom exemplified as the terminal structure of the polymer (P) described above.

[0097]

[0098] In formula (b2), Ar １ , L ２And y are the same as above. Z １ｂ and Z ２ｂ Each of these independently represents a hydroxyl group, a thiol group, a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group. Examples of halogen atoms, alkylborane groups, and boronic acid ester groups are the same as the examples of halogen atoms, alkylborane groups, and boronic acid ester groups exemplified above as terminal structures of polymer (P). However, Z ２ｂ When L is a hydroxyl group or a thiol group, it is a single bond. ２ The number is an integer between 0.5y and (1.0y-1), and Z ２ｂ When is a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group, L is a single bond. ２ The number is an integer between (0.5y-1) and (1.0y-1) inclusive.

[0099] In the above method, Z ２ｂ If it is a hydroxyl group, the terminal linking group (L ２ A constituent unit B is formed in which ) is -O-, Z ２ｂ If it is a thiol group, the terminal linking group (L ２ A constituent unit B is formed in which ) is -S-, Z ２ｂ When is a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group, the terminal linking group (L ２ A constituent unit B is formed, which is a single bond.

[0100] As for compound (b1), X １ｂ and / or X ２ｂ Multiple types of compounds with different properties can be used. Similarly, as compound (b2), Z １ｂ and / or Z ２ｂ Multiple types of compounds with different properties can be used.

[0101] Monomers containing compound (b1) and compound (b2) can be reacted (polymerized), for example, by an aromatic nucleophilic substitution reaction in a solvent in the presence of a base.

[0102] The solvent used in the reaction is preferably one that is a good solvent for compound (b1), compound (b2), and polymer (P), and that allows for the high molecular weight of polymer (P) during polymerization. For example, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, 1,3-dimethyl-2-imidazolidinone, and tetramethylurea are preferably used. These solvents may be used individually or as a mixture of two or more.

[0103] A base is used to enhance the nucleophilicity of the monomer. The base is not particularly limited as long as it can deprotonate compound (b2). For example, alkali metal hydroxides and carbonates, alkaline earth metal hydroxides and carbonates, and organic bases such as amines can be used. The alkali metal may be lithium, sodium, potassium, rubidium, or cesium. The alkaline earth metal may be magnesium, calcium, strontium, or barium.

[0104] The reaction temperature in aromatic nucleophilic substitution reactions may be in the range of 25 to 350°C. From the viewpoint of excellent reaction rate, the reaction temperature is preferably 60°C or higher, and more preferably 100°C or higher. From the viewpoint of suppressing polymer decomposition, the reaction temperature is preferably 300°C or lower, and more preferably 250°C or lower. From these viewpoints, the reaction temperature is preferably 60 to 300°C, and more preferably 100 to 250°C.

[0105] Monomers containing compound (b1) and compound (b2) can also be subjected to cross-coupling reactions (polymerization), for example, in a solvent in the presence of a catalyst. Examples of solvents that can be used in the reaction are the same as examples of solvents that can be used in the aromatic nucleophilic substitution reaction described above.

[0106] There are no particular restrictions on the catalyst as long as it can carry out the cross-coupling reaction, and conventionally known catalysts can be used. For coupling reactions between halogens, for example, copper catalysts, nickel catalysts, or palladium catalysts can be used. For coupling reactions between halogens and boronic acid groups, alkylborane groups, or boronic acid ester groups, for example, conventionally known catalysts used in the Suzuki-Miyaura coupling reaction (palladium catalysts, nickel catalysts, etc.) can be used.

[0107] The copper catalyst may be, for example, copper(I) 2-thiophenecarboxylate or tetrakis(acetonitrile)copper(I)hexafluorophosphate.

[0108] The nickel catalyst may be, for example, bis(1,5-cyclooctadiene)nickel(0), dibromobis(triphenylphosphine)nickel(II), or [1,1'-bis(diphenylphosphino)ferrocene]dichloronickel(II).

[0109] The palladium catalyst may be, for example, tetrakis(triphenylphosphine)palladium(0), palladium(II) acetate, bis(triphenylphosphine)palladium(II) dichloride, or [1,1'-bis(diphenylphosphine)ferrocene]dichloropalladium(II).

[0110] The reaction temperature in the cross-coupling reaction may be in the range of 0 to 350°C. From the viewpoint of improving the reaction rate, the reaction temperature is preferably 30°C or higher, and more preferably 60°C or higher. From the viewpoint of suppressing polymer decomposition, the reaction temperature is preferably 300°C or lower, and more preferably 250°C or lower. From these viewpoints, the reaction temperature is preferably 30 to 300°C, and more preferably 60 to 250°C.

[0111] In the aromatic nucleophilic substitution and cross-coupling reactions described above, it is preferable to remove water from the reaction system in order to increase the molecular weight of the polymer (P). The method of dehydration is not particularly limited, but examples include azeotropic dehydration by coexisting an azeotropic solvent in the reaction system, continuous removal from the reaction system by heating above the boiling point of water, and coexisting a water-absorbing agent such as a molecular sieve. The azeotropic solvent is not particularly limited as long as it can remove water, and for example, at least one selected from the group consisting of benzene, toluene, cyclohexane, and xylene may be used.

[0112] The above aromatic nucleophilic substitution and cross-coupling reactions are preferably carried out under an inert atmosphere (for example, under a nitrogen or argon atmosphere). After the polymerization reaction is complete, the polymer can be recovered from the reaction solution and purified to obtain the desired polymer. Methods for recovering the polymer from the reaction solution include, for example, adding the reaction solution to a solvent in which the polymer has low solubility, allowing the polymer to precipitate and be recovered as a solid, and removing the solvent from the reaction solution by evaporation and recovering the polymer as a solid. Methods for purifying the polymer include, for example, washing in a solvent in which the polymer has low solubility and the by-product inorganic salts and residual monomer-derived compounds have high solubility, and washing using a Soxhlet extractor. The methods for recovering and purifying the polymer are not limited to these methods.

[0113] Polymer (P) can also be obtained by reacting (polymerizing) monomers containing compound (b1), compound (b2), and a compound represented by the following formula (b3) (hereinafter also referred to as "compound (b3)"). In other words, polymer (P) can also be a polymer of monomers containing compound (b1), compound (b2), and compound (b3).

[0114]

[0115] In formula (b3), Ar ２ Z １ｂ Z ２ｂ , L ３ And z are equivalent to those stated above.

[0116] As for compound (b3), Z １ｂ and / or Z ２ｂ Multiple types of compounds with different properties can be used. Reactions of monomers containing compound (b1), compound (b2), and compound (b3) can be carried out in the same manner as reactions of monomers containing compound (b1) and compound (b2).

[0117] While some aspects of the polymer (P) and its manufacturing method in this disclosure have been described above, the polymer (P) and its manufacturing method in this disclosure are not limited to those described above.

[0118] For example, polymer (P) can be replaced with X in formula (b1) １ｂ and X ２ｂ However, compounds that are independently a hydroxyl group, a thiol group, a boronic acid group, an alkylborane group, or a boronic acid ester group may be used. In this case, as compound (b2) and / or compound (b3), both ends (Z in formula (b2)) may be used. １ｂ and Z ２ｂ , and also Z in equation (b3) １ｂ and Z ２ｂ Either use a compound in which the (b) atom is a halogen atom, or use compounds in which one end is a halogen atom as compound (b2) and compound (b3).

[0119] Furthermore, polymer (P) can also be obtained by oxidizing a polymer (for example, a monomer polymer containing compound (b1) and compound (b2)) that includes constituent unit A represented by formula (a1) and constituent unit B represented by formula (a2). More specifically, polymer (P) is obtained by L １ or L ２ It can be an oxide of a polymer containing a -S- (sulfide group) (hereinafter referred to as "sulfide-containing polymer").

[0120] Furthermore, polymer (P) can also be obtained, for example, by reacting (polymerizing) a polymer of the monomer or its oxide with a known crosslinkable compound (e.g., decafluorobiphenyl) having three or more groups that react with the polymer or its oxide to form a crosslink. In other words, polymer (P) can be a reaction product of the polymer of the monomer or its oxide and a crosslinkable compound. This method makes it possible to obtain polymer (P) having the polymer or its oxide as a polymer unit.

[0121] The polymer (P) may be obtained by a method that includes a step of protonating the ion exchange groups that form salts with metal ions. This step may involve immersing the polymer obtained by the method described above (for example, a polymer of compound (b1) and compound (b2) or an oxide thereof, or a reaction product of the polymer or oxide and a crosslinkable compound (d)) in an acid (for example, hydrochloric acid) to protonate the ion exchange groups (for example, a salt of a sulfonic acid group). By washing and drying the compound (for example, a powder) after immersion, the metal ions of the polymer before immersion are replaced with protons, and a polymer (P) in which the ion exchange groups are protonated is obtained.

[0122] <Electrolyte Material and Electrolyte Membrane> The electrolyte material of one embodiment is a material containing an electrolyte, and contains the above polymer (P) as the electrolyte. The electrolyte membrane of one embodiment is a membrane containing an electrolyte, and contains the above polymer (P) as the electrolyte. The electrolyte material is used to form the electrolyte membrane. That is, the electrolyte membrane may be made of the electrolyte material.

[0123] The electrolyte material and electrolyte membrane have excellent proton conductivity because they contain polymer (P). The proton conductivity of the electrolyte membrane is, for example, 130 mS / cm or higher, and may be 150 mS / cm or higher or 180 mS / cm or higher, in an environment of 80°C and 100% relative humidity.

[0124] The electrolyte material and electrolyte membrane, containing polymer (P), exhibit excellent swelling resistance. The swelling resistance of the electrolyte membrane can be confirmed, for example, by the volume swelling rate measured by the method described in the examples below. The volume swelling rate of the electrolyte membrane measured by the method of the examples may be 60% or less, 50% or less, or 40% or less.

[0125] Electrolyte materials and electrolyte membranes also tend to exhibit excellent gas barrier properties. The gas barrier properties of an electrolyte membrane can be confirmed by the hydrogen gas permeability measured by a hydrogen gas permeability test. For example, the hydrogen gas permeability of an electrolyte membrane is 1.00 × 10⁻¹⁶ under conditions of 80°C and 60% relative humidity. －７ cm ３ mm / (cm) ２ It is less than or equal to s kPa, and 0.50 × 10 －７ cm ３ mm / (cm) ２ (s・kPa) or less or 0.30 × 10 －７ cm ３ mm / (cm) ２ It may be less than or equal to s kPa.

[0126] The electrolyte material and electrolyte membrane may consist solely of polymer (P), or they may contain components other than polymer (P). That is, the electrolyte material may be a composition. Components other than polymer (P) may be additives such as water-retaining inorganic substances or radical scavengers. Specific examples of additives include water, silica, cerium oxide, and manganese oxide. These components may be used individually or in combination.

[0127] The polymer (P) content in the electrolyte material and electrolyte membrane may be 80 to 100% by mass, 90 to 100% by mass, or 95 to 100% by mass, from the viewpoint of superior proton conductivity and swelling resistance. The above content is based on the total amount of solids in the electrolyte material or electrolyte membrane.

[0128] The thickness of the electrolyte membrane is not particularly limited and can be changed according to the size of the fuel cell, etc. From the viewpoint of increasing the mechanical strength of the membrane while reducing membrane resistance, the thickness of the electrolyte membrane may be, for example, 1 to 200 μm, or it may be 1 to 100 μm or 1 to 50 μm.

[0129] There are no particular limitations on the method for manufacturing the electrolyte membrane, and it can be manufactured by known methods for forming an electrolyte polymer film. Examples of methods for manufacturing the electrolyte membrane include the solution casting method, the dispersion casting method, the melt pressing method, and the melt extrusion method.

[0130] In the solution casting method, for example, an electrolyte film can be obtained by using a solution containing a polymer (P) as the electrolyte material, casting the solution onto a substrate, removing the solvent, and then peeling the film off the substrate.

[0131] The solvent used in the solution casting method is not particularly limited as long as it is capable of dissolving the polymer (P). For example, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, 1,3-dimethyl-2-imidazolidinone, and tetramethylurea can be used. These may be used individually or in combination.

[0132] In the dispersion casting method, for example, an electrolyte film can be obtained by using a dispersion containing a polymer (P) as the electrolyte material, casting the dispersion onto a substrate, removing the dispersion medium, and then peeling the film off the substrate.

[0133] The dispersion medium used in the dispersion casting method is not particularly limited as long as it is a dispersion medium capable of dispersing the polymer (P). For example, water, ethers, alcohols, ketones, esters, carboxylic acids, amines, acetonitrile, nitromethane, toluene, xylene, chlorobenzene, and chloroform can be used. Examples of ethers include tetrahydrofuran and diethyl ether. Examples of alcohols include methanol, ethanol, 1-propanol, isopropyl alcohol, and 1-butanol. Examples of ketones include acetone and cyclohexanone. Examples of esters include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, methyl lactate, and ethyl lactate. Examples of carboxylic acids include formic acid, acetic acid, and propionic acid. Examples of amines include dimethylamine, diethylamine, triethylamine, pyridine, triethanolamine, and piperazine. These may be used individually or in combination.

[0134] A method for manufacturing an electrolyte membrane according to one embodiment may further include a step of washing the obtained membrane (hereinafter referred to as the "washing step"). In the washing step, the membrane may be washed using a washing solution. In this case, the electrolyte membrane is obtained by drying the membrane after the washing step by a method such as vacuum drying. As the washing solution, a known washing solution according to the purpose of washing may be used. Specific examples of washing solutions include hydrogen peroxide, sulfuric acid, hydrochloric acid, nitric acid, and pure water. These may be used individually or in combination of two or more.

[0135] The electrolyte material and electrolyte membrane are suitably used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers. The electrolyte material and electrolyte membrane can also be used in redox flow batteries, electrochemical hydrogen pumps, chlor-alkali electrolyzers, solid acid catalysts, membrane-type humidity control devices, gas separation membranes, and the like.

[0136] The electrolyte membrane can also be used in combination with a microporous membrane, nonwoven fabric, mesh, etc. That is, another embodiment of the present disclosure is a laminate comprising an electrolyte membrane and another membrane (microporous membrane, nonwoven fabric, mesh, etc.).

[0137] <Electrolyte membrane with catalyst layer> An electrolyte membrane with a catalyst layer according to one embodiment comprises the electrolyte membrane of the above embodiment and a catalyst layer disposed on one or both sides of the electrolyte membrane.

[0138] The catalyst layer is, for example, a layer composed of an anode catalyst or a cathode catalyst, such as in a polymer electrolyte fuel cell or polymer electrolyte water electrolysis device. Hereinafter, a layer composed of an anode catalyst will be referred to as the anode catalyst layer, and a layer composed of a cathode catalyst will be referred to as the cathode catalyst layer.

[0139] The composition of the catalyst layer is not particularly limited and can be a conventionally known configuration for catalyst layers (anode catalyst layer, cathode catalyst layer) in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers. The catalyst layer may be formed of a conductive composition containing, for example, an anode catalyst or cathode catalyst and a conductive material. The catalyst layer may also contain an ionomer.

[0140] As an anode catalyst in a polymer electrolyte fuel cell, a metal catalyst capable of promoting the oxidation reaction of fuels such as hydrogen can be used. As an anode catalyst in a polymer electrolyte water electrolysis device, a metal catalyst capable of promoting the oxygen evolution reaction can be used. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, and vanadium, as well as alloys of two or more of these, can be used. These may be used individually or in mixtures of two or more.

[0141] As a cathode catalyst in a polymer electrolyte fuel cell, a metal catalyst capable of promoting the reduction reaction of oxygen can be used, and as a cathode catalyst in a polymer electrolyte water electrolysis device, a metal catalyst capable of promoting the hydrogen evolution reaction can be used. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, and vanadium, as well as alloys of two or more of these, can be used. These may be used individually or in mixtures of two or more.

[0142] Examples of conductive materials that can be used include carbon blacks such as furnace black, Ketjen black, channel black, and acetylene black, activated carbon, and graphite. These may be used individually or in combination of two or more.

[0143] Conventional known materials can be used as the ionomer; for example, an ionomer containing a perfluoro electrolyte can be used. Alternatively, the above-mentioned polymer (P) can be used as the ionomer. It is preferable to use a material with high oxygen permeability as the ionomer. There are no particular restrictions on the amount of ionomer added to the catalyst layer, but it is preferable to adjust the amount added within a range where oxygen diffusion is not easily inhibited.

[0144] The catalyst layer may further contain additives such as water repellents like fluorinated carbon, binders like fluororesins and hydrocarbon resins having sulfonic acid groups.

[0145] A laminate comprising an electrolyte membrane with an anode catalyst layer and a cathode catalyst layer on both sides (for example, a laminate with a layer configuration of "anode catalyst layer / electrolyte membrane / cathode catalyst layer") is also called a CCM (Catalist Coated Membrane) and is suitably used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers.

[0146] In the above embodiment, instead of the electrolyte membrane, a laminate comprising an electrolyte membrane and the other membranes mentioned above (microporous membrane, nonwoven fabric, mesh, etc.) can also be used.

[0147] <Membrane electrode assembly> A membrane electrode assembly according to one embodiment comprises the electrolyte membrane of the above embodiment and an electrode layer disposed on one or both sides of the electrolyte membrane.

[0148] The electrode layer comprises, for example, the catalyst layer (anode catalyst layer or cathode catalyst layer) in the electrolyte membrane with catalyst layer of the above embodiment. Hereinafter, an electrode layer comprising an anode catalyst layer will be referred to as the anode layer, and an electrode layer comprising a cathode catalyst layer will be referred to as the cathode layer.

[0149] The configuration of the electrode layer is not particularly limited and may be a configuration conventionally known as the electrode layer (anode layer, cathode layer) of a polymer electrolyte fuel cell or polymer electrolyte water electrolysis device. The electrode layer may consist, for example, of the catalyst layer (anode catalyst layer or cathode catalyst layer) and a gas diffusion substrate. If the catalyst layer itself has gas diffusivity, the electrode layer may consist only of the catalyst layer. As the gas diffusion substrate, for example, a porous membrane can be used. As the gas diffusion substrate, in addition to gas diffusivity, materials that have water repellency and conductivity can also be used (for example, carbon fiber substrates such as carbon nonwoven fabric or carbon paper, or titanium fiber sintered bodies).

[0150] A laminate comprising an electrolyte membrane with an anode layer and a cathode layer as electrode layers on both sides (for example, a laminate with a layer configuration of "gas diffusion substrate / anode catalyst layer / electrolyte membrane / cathode catalyst layer / gas diffusion substrate") is also called a MEA (Membrane Electrode Assembly) and is suitably used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers.

[0151] In the above embodiment, instead of the electrolyte membrane, a laminate comprising an electrolyte membrane and the other membranes mentioned above (microporous membrane, nonwoven fabric, mesh, etc.) can also be used.

[0152] <Solid Polymer Fuel Cell> A solid polymer fuel cell according to one embodiment comprises the membrane electrode assembly of the above embodiment.

[0153] The configuration of a polymer electrolyte fuel cell is not particularly limited and may be a conventionally known configuration, except that the membrane electrode assembly of the above embodiment is used. A polymer electrolyte fuel cell may, for example, comprise two or more membrane electrode assemblies. The two or more membrane electrode assemblies may be stacked (laminated) with a separator in between. A separator conventionally known for polymer electrolyte fuel cells can be used as the separator.

[0154] <Solid Polymer Water Electrolyzer> A solid polymer water electrolyzer according to one embodiment includes the membrane electrode assembly according to the above embodiment.

[0155] The configuration of the polymer electrolyte water electrolysis apparatus is not particularly limited, and can be a conventionally known configuration except for the use of the membrane electrode assembly of the above embodiment. The polymer electrolyte water electrolysis apparatus may, for example, further include a power supply element outside the membrane electrode assembly. It may also include two or more membrane electrode assemblies.

[0156] The contents of this disclosure will be described in more detail below using examples and comparative examples, but this disclosure is not limited to the following examples.

[0157] <Synthesis Example 1> (Synthesis of hydrophilic monomer (M1)) A 10 L flask equipped with a dropping funnel, reflux condenser, and mechanical stirrer was purged with nitrogen, and 101 g of 4,4'-bis[(4-chlorophenyl)sulfonyl]-1,1'-biphenyl and 4 L of anhydrous tetrahydrofuran were charged in, and stirring was started. The mixture was cooled to -70°C in a methanol-dry ice bath, and 320 mL of 2.6 mol / L n-butyllithium-hexane solution was added dropwise. The mixture was stirred for 1 hour while remaining cooled in the bath. 40 mL of sulfur dioxide gas was introduced into the flask with nitrogen gas. The mixture was stirred for 30 minutes while remaining cooled in the bath. After that, the bath was removed and the temperature was raised to 0°C. The precipitated solid was filtered off by suction filtration and washed with 200 mL of tetrahydrofuran. The recovered solid was dissolved in 2 L of pure water, 260 mL of 35% hydrogen peroxide solution was added, and the mixture was stirred for 18 hours. The solid was removed by suction filtration, and 600 g of sodium chloride was added to the recovered filtrate. The precipitated white solid was recovered by suction filtration and purified by recrystallization from water / isopropyl alcohol. The obtained solid was dried under reduced pressure to obtain a hydrophilic monomer (M1) represented by the following formula (M1). The yield was 65%.

[0158]

[0159] <Synthesis Example 2> (Synthesis of hydrophobic monomer (M2)) A 500 mL flask equipped with a stirring bar and condenser was purged with nitrogen. To this flask, 9.5 g of 2,7-dibromo-9,9-diphenylfluorene, 12.1 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)biphenyl-4-ol, 19 g of potassium carbonate, 2.0 g of tetrakis(triphenylphosphine)palladium(0), and 250 mL of tetrahydrofuran were added. The reaction mixture was heated to 90°C and stirred for 3 hours. After the reaction mixture was allowed to cool to room temperature (approximately 25°C), 200 mL of water and 500 mL of ethyl acetate were added and the mixture was separated, and the organic layer was recovered. The solvent was removed by evaporation using an evaporator, and the resulting crude product was purified by silica column chromatography using an ethyl acetate / hexane = 1 / 1 (volume ratio) mixed solvent as the developing solvent. The fraction containing the target substance was recovered, and the solvent was removed using an evaporator. The resulting solid was dried under reduced pressure to obtain a hydrophobic monomer (M2) represented by the following formula (M2). The yield was 53%.

[0160]

[0161] <Synthesis Example 3> (Synthesis of hydrophobic monomer (M3)) A 200 mL flask equipped with a stirring bar and condenser was purged with nitrogen. 4.0 g of 2,7-dibromonaphthalene, 4.65 g of 4-hydroxyphenylboronic acid, 9.73 g of potassium carbonate, 0.32 g of tetrakis(triphenylphosphine)palladium(0), and 90 mL of N,N-dimethylformamide were added to the flask. The reaction mixture was heated to 80°C and stirred for 19 hours. After the reaction mixture cooled to room temperature, 150 mL of water and 300 mL of ethyl acetate were added and the mixture was separated, and the organic layer was recovered. The solvent was removed using an evaporator, and the resulting crude material was dissolved in 15 mL of ethanol. 30 mL of chloroform was added, and the precipitated solid was recovered. The obtained solid was dried under reduced pressure to obtain the hydrophobic monomer (M3) represented by the following formula (M3). The yield was 78%.

[0162]

[0163] <Synthesis Example 4> (Synthesis of hydrophobic monomer (M4)) A 300 mL flask equipped with a stirring bar and condenser was purged with nitrogen. To this flask, 6.0 g of 4,4'-dichlorodiphenylsulfone, 13.0 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)biphenyl-4-ol, 13.3 g of potassium carbonate, 0.24 g of tetrakis(triphenylphosphine)palladium(0), and 180 mL of N,N-dimethylformamide were added. The reaction mixture was heated to 80°C and stirred for 48 hours. After the reaction mixture was allowed to cool to room temperature, 200 mL of water and 300 mL of ethyl acetate were added and the mixture was separated, and the organic layer was recovered. The solvent was removed using an evaporator, and the resulting crude material was washed in the following order: 100 mL of ethanol, 250 mL of 1 M hydrochloric acid, and 200 mL of pure water. The obtained solid was dried under reduced pressure to obtain a hydrophobic monomer (M4) represented by the following formula (M4). The yield was 80%.

[0164]

[0165] <Synthesis Example 5> (Synthesis of hydrophobic monomer (M5)) A 200 mL flask equipped with a stirring bar and condenser was purged with nitrogen. 2.5 g of 3,3'-dibromoviphenyl, 5.93 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)biphenyl-4-ol, 5.54 g of potassium carbonate, 0.18 g of tetrakis(triphenylphosphine)palladium(0), and 80 mL of N,N-dimethylformamide were added to the flask. The reaction mixture was heated to 85°C and stirred for 22 hours. After the reaction mixture cooled to room temperature, 100 mL of 1 M hydrochloric acid was added to stop the reaction, and the precipitated solid was collected. The obtained crude was washed with 50 mL of ethanol to obtain the hydrophobic monomer (M5) represented by the following formula (M5). The yield was 92%.

[0166]

[0167] <Synthesis Example 6> (Synthesis of hydrophobic monomer (M6)) A 200 mL flask equipped with a stirring bar and condenser was purged with nitrogen. To this flask, 2.24 g of 2,6-dichlorobenzonitrile, 8.10 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)biphenyl-4-ol, 9.00 g of potassium carbonate, 0.29 g of tetrakis(triphenylphosphine)palladium(0), and 60 mL of N,N-dimethylformamide were added. The reaction mixture was heated to 80°C and stirred for 22 hours. After the reaction mixture was allowed to cool to room temperature, 100 mL of 1 M hydrochloric acid was added to stop the reaction, and the precipitated solid was collected. The obtained crude was dissolved in 108 mL of dimethyl sulfoxide, and then 400 mL of ethanol was added, and the precipitated solid was collected to obtain the hydrophobic monomer (M6) represented by the following formula (M6). The yield was 34%.

[0168]

[0169] <Structures of Polymers (P1) to (P15)> Tables 1 and 2 show the structures of polymers (P1) to (P15) in Comparative Examples 2 to 4 and Examples 1 to 12 described below, represented by formulas (P1), (P4), (P7), (P10) to (P15), respectively. In formulas (P1), (P4), (P7), and (P10) to (P15) below, M represents Na, K, or H, and x, y, and n represent positive numbers. The synthesis methods for polymers (P1) to (P15) are as described in Comparative Examples 2 to 4 and Examples 1 to 12 described below.

[0170]

[0171]

[0172] <Comparative Example 1> In Comparative Example 1, a commercially available Nafion was used as the evaluation sample. ＴＭ Using NR211 (film thickness 25 μm), various measurements and evaluations (ion exchange capacity measurement, proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test) were performed using the following methods.

[0173] (Ion exchange capacity measurement) Electrolyte membrane of Comparative Example 1 (Nafion ＴＭNR211) was dried at 80°C for 12 hours or more, and its dry mass was determined. The dried electrolyte membrane was immersed in a 20% sodium chloride aqueous solution and stirred for 24 hours to perform ion exchange. The resulting hydrochloric acid was titrated using a 0.01 M sodium hydroxide aqueous solution. An automatic titrator COM-A19 manufactured by HIRANUMA Corporation was used for the titration, and the endpoint was set at a pH of 7. The ion exchange capacity (IEC) was calculated using the following formula. The IEC of this comparative example was 1.0 mmol / g. IEC (unit: mmol / g) = {Concentration of sodium hydroxide aqueous solution (unit: mol / L) × Dropping volume (unit: mL)} / Dry mass of electrolyte membrane (unit: g)

[0174] (Evaluation) [Proton Conductivity Evaluation] The proton conductivity of the electrolyte membrane of Comparative Example 1 was measured by the following method. A Teflon® measurement cell (Scribner, BT-115) was used, and the electrolyte membrane was placed in the cell in contact with four platinum wires. After being held at 80°C and 20% relative humidity for 2 hours, the relative humidity was increased by 10% and held for 30 minutes. This operation was continued until the relative humidity reached 100%, and then DC resistance measurement was performed using the four-terminal method at 100% relative humidity. The proton conductivity in the planar direction of the electrolyte membrane was calculated from the obtained resistance value, the thickness of the electrolyte membrane, and the distance between terminals. The proton conductivity of the electrolyte membrane of this comparative example under conditions of 80°C and 100% relative humidity was 129 mS / cm. Note that in the following examples, the above Nafion ＴＭ Using the proton conductivity of NR211 as a reference, an electrolyte membrane was evaluated as having excellent proton conductivity if its measured proton conductivity under conditions of 80°C and 100% relative humidity was 129 mS / cm or higher.

[0175] [Measurement of Volume Swelling Rate] A 3 cm square membrane was punched out from the electrolyte membrane, and the punched-out membrane was immersed in 50 mL of pure water at 80°C for 1 hour. The volume of the membrane was calculated by measuring the dimensions before and after immersion in pure water. The volume swelling rate was calculated by dividing the change in the volume of the membrane before and after immersion in pure water ([Volume after pure water immersion] - [Volume before pure water immersion]) by the volume of the membrane before immersion in pure water. The volume swelling rate was 61%. In the following examples, the above Nafion ＴＭBased on the volume swelling rate of NR211, an electrolyte membrane was evaluated as having excellent swelling resistance if its volume swelling rate was 61% or less.

[0176] [Hydrogen Gas Permeability Test] The hydrogen gas permeability of the electrolyte membrane was evaluated according to the gas permeability test method using the isobaric method (JIS K 7126-2). Specifically, first, the electrolyte membrane was installed in a sealed state between the two chambers of the permeation cell. Next, hydrogen gas, the gas to be measured, was supplied to one side of the electrolyte membrane, and Ar gas, the carrier gas, was supplied to the other side. The relative humidity was adjusted by the humidifier temperature of each supplied gas and the cell temperature. The gas that permeated through the electrolyte membrane was supplied to a gas chromatograph along with the carrier gas, and the hydrogen gas permeability was measured from the detection data and flow rate. From the obtained hydrogen gas permeability and the thickness of the electrolyte membrane, the hydrogen gas permeability (unit: cm) was calculated. ３ mm / (cm) ２ The pressure (s・kPa) was calculated. The hydrogen gas permeability of the electrolyte membrane in Comparative Example 1 was 1.03 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The value was s・kPa). The hydrogen gas transmission rates in the following examples and comparative examples are measured under conditions of 80°C and 60% relative humidity.

[0177] <Comparative Example 2> (Synthesis of Polymer (P1)) 2.1754 g of 4,4'-dihydroxybiphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.5891 g of 4,4'-dichlorodiphenylsulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.3245 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.0151 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130°C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130°C for 150 hours. After the reaction solution was allowed to cool to room temperature, it was reprecipitated and purified from 1000 mL of isopropyl alcohol (IPA), and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P1) having the structure represented by the above formula (P1). The yield was 97%. In polymer (P1), x in formula (P1) was approximately 0.22 (0.18 to 0.26), y was approximately 0.78 (0.74 to 0.82), and n was approximately 47. Note that n in formula (P1) was calculated from the number-average molecular weight described later. The same applies to n in formulas (P4), (P7), and (P10) to (P15) described later.

[0178] (Molecular Weight Measurement) The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polymer (P1) were measured under the following conditions, and the polydispersity (Mw / Mn) was determined. Mn was 30,000, Mw was 71,000, and Mw / Mn was 2.4.

[0179] [Measurement Conditions] Polymer (P1) was dissolved at a concentration of 1 mg / mL in an eluent (N,N-dimethylformamide solvent containing 10 mmol / L of lithium bromide) to prepare the sample solution. A Tosoh HLC-8320GPC was used as the apparatus. Two Tosoh TSKgel SuperAWM-H columns (6.0 mm inner diameter, 15 cm length) were used. A differential refractometer was used as the detector. The flow rate was 0.6 mL / min and the temperature was 40°C. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) were determined by converting to standard polyethylene glycol / oxide (PEG / PEO). Furthermore, the polydispersity (Mw / Mn) was determined by dividing the weight-average molecular weight (Mw) by the number-average molecular weight (Mn).

[0180] ( １ (H-NMR measurement) Under the following conditions, the polymer (P1) １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.83–6.85 ppm.

[0181] [Measurement Conditions] For 1H-NMR measurements, an AVANCE III HD 400 (400MHz, manufactured by Bruker) was used as the apparatus. １ ¹H-NMR was performed using heavy DMSO as the measurement solvent and tetramethylsilane (TMS) as the internal standard. Commercially available reagents were used.

[0182] (Preparation of electrolyte membrane) The obtained polymer (P1) was dissolved in DMSO to obtain a solution containing 15% by mass of polymer (P1). The obtained solution was cast onto a glass substrate and dried at 60°C for 12 hours to obtain a film (film thickness 39 μm). The obtained film was immersed in 1 M hydrochloric acid for 24 hours to remove metal ions (Na ＋ or K ＋ ) to proton (H ＋After substitution with ), the electrolyte membrane of Comparative Example 2 (an electrolyte membrane made of a proton-substituted polymer (P1), with a film thickness of 39 μm) was obtained by immersion in pure water for thorough washing and then dried under reduced pressure. When the ion exchange capacity was measured using the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Comparative Example 2 was 1.51 mmol / g. The "film thickness" in this comparative example was measured using PG-02 manufactured by TECLOK CORPORATION. The same applies to the "film thickness" in the following comparative examples and examples.

[0183] (Evaluation) The electrolyte membrane of Comparative Example 2 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 90 mS / cm. The volume swelling rate was 49%. The hydrogen gas permeability was 0.14 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa. The polymer electrolyte membrane of Comparative Example 2 had excellent swelling resistance, but its proton conductivity was low, and it was not possible to achieve both high proton conductivity and swelling resistance.

[0184] <Comparative Example 3> (Synthesis of Polymer (P2)) Polymer (P2) was obtained by the same method as in Comparative Example 2, except that the amounts of each compound added were 2.0620 g of 4,4'-dihydroxybiphenyl, 2.2868 g of 4,4'-dichlorodiphenylsulfone, 2.7347 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.0674 g of potassium carbonate. Polymer (P2) is a polymer having the structure represented by the above formula (P1), where x in the above formula (P1) is approximately 0.27 (0.23 to 0.31), y is approximately 0.73 (0.69 to 0.77), and n is approximately 39. The yield of polymer (P2) was 80%. The Mn of polymer (P2), measured in the same manner as in Comparative Example 2, was 27000, Mw was 57000, and Mw / Mn was 2.1. In the same manner as in Comparative Example 2, the polymer (P2) １ When the 1H-NMR spectrum was measured, a peak was observed at 6.84 ppm.

[0185] (Preparation of Electrolyte Membrane) The electrolyte membrane of Comparative Example 3 (electrolyte membrane made of proton-substituted polymer (P2), thickness 56 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P2) was used instead of polymer (P1) and the thickness of the membrane made of polymer (P2) was adjusted to 56 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Comparative Example 3 was 1.88 mmol / g.

[0186] (Evaluation) The electrolyte membrane of Comparative Example 3 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 132 mS / cm. The volume swelling rate was 78%. The hydrogen gas permeability was 0.14 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa. The polymer electrolyte membrane of Comparative Example 3 had excellent proton conductivity, but it had a high volume swelling rate, making it impossible to achieve both proton conductivity and swelling resistance.

[0187] <Comparative Example 4> (Synthesis of Polymer (P3)) Polymer (P3) was obtained by the same method as in Comparative Example 2, except that the amounts of each compound added were 1.9486 g of 4,4'-dihydroxybiphenyl, 1.9845 g of 4,4'-dichlorodiphenylsulfone, 3.1449 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.1197 g of potassium carbonate. Polymer (P3) is a polymer having the structure represented by the above formula (P1), where in polymer (P3), x in the above formula (P1) was approximately 0.33 (0.29 to 0.37), y was approximately 0.67 (0.63 to 0.71), and n was approximately 37. The yield of polymer (P3) was 80%. The Mn of polymer (P3), measured in the same manner as in Comparative Example 2, was 28000, Mw was 62000, and Mw / Mn was 2.2. In the same manner as in Comparative Example 2, the polymer (P3) １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.83–6.85 ppm.

[0188] (Preparation of Electrolyte Membrane) The electrolyte membrane of Comparative Example 4 (electrolyte membrane made of proton-substituted polymer (P3), thickness 62 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P3) was used instead of polymer (P1) and the thickness of the film made of polymer (P3) was adjusted to 62 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Comparative Example 4 was 2.12 mmol / g.

[0189] (Evaluation) The electrolyte membrane of Comparative Example 4 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 171 mS / cm. The volume swelling rate was 113%. The hydrogen gas permeability was 0.17 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa. The polymer electrolyte membrane of Comparative Example 4 had excellent proton conductivity, but it had a high volume swelling rate, making it impossible to achieve both proton conductivity and swelling resistance.

[0190] <Example 1> (Synthesis of polymer (P4)) 1.1027 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.196 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.9116 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 0.662 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 10 mL of DMSO and 10 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 150 hours. After allowing the reaction mixture to cool to room temperature, reprecipitation purification was performed from 300 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P4) having the structure represented by the above formula (P4). The yield was 92%.

[0191] In polymer (P4), x in the above formula (P4) was approximately 0.59 (0.55 to 0.63), y was approximately 0.41 (0.37 to 0.45), and n was approximately 20. Furthermore, the content of constituent units derived from hydrophobic monomer (M2) was 50 mol% of the total amount of all constituent units constituting polymer (P4). The Mn of polymer (P4), measured in the same manner as in Comparative Example 2, was 31,000, Mw was 63,000, and Mw / Mn was 2.0. １ When the 1H-NMR spectrum was measured, a peak was observed at 6.85 ppm.

[0192] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 1 (electrolyte membrane made of proton-substituted polymer (P4), thickness 78 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P4) was used instead of polymer (P1) and the thickness of the membrane made of polymer (P4) was adjusted to 78 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 1 was 1.84 mmol / g.

[0193] (Evaluation) The electrolyte membrane of Example 1 was evaluated in the same manner as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 135 mS / cm, confirming that the electrolyte membrane of Example 1 has excellent proton conductivity. The volume swelling rate was 28%, confirming that the electrolyte membrane of Example 1 has excellent swelling resistance. The hydrogen gas permeability was 0.19 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, confirming that the electrolyte membrane of Example 1 has excellent gas barrier properties.

[0194] <Example 2> (Synthesis of Polymer (P5)) Polymer (P5) was obtained by the same method as in Example 1, except that the amounts of each compound added were 1.0421 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.127 g of 4,4'-dichlorodiphenyl sulfone, 1.0483 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 0.699 g of potassium carbonate. Polymer (P5) is a polymer having the structure represented by the above formula (P4), where x in the above formula (P4) is approximately 0.72 (0.68 to 0.76), y is approximately 0.28 (0.24 to 0.32), and n is approximately 13. In addition, the content of constituent units derived from the hydrophobic monomer (M2) was 50 mol% of the total amount of all constituent units that make up polymer (P5). The yield of polymer (P5) was 78%. The polymer (P5), measured in the same manner as in Comparative Example 2, had a Mn of 21,000, a Mw of 52,000, and a Mw / Mn ratio of 2.5. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.85–6.87 ppm.

[0195] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 2 (electrolyte membrane made of proton-substituted polymer (P5), thickness 83 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P5) was used instead of polymer (P1) and the thickness of the film made of polymer (P5) was adjusted to 83 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 2 was 2.30 mmol / g.

[0196] (Evaluation) The electrolyte membrane of Example 2 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 178 mS / cm, confirming that the electrolyte membrane of Example 2 has excellent proton conductivity. The volume swelling rate was 36%, confirming that the electrolyte membrane of Example 2 has excellent swelling resistance. The hydrogen gas permeability was 0.19 × 10⁻⁶. －７ cm ３ mm / (cm) ２The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 2 has excellent gas barrier properties.

[0197] <Example 3> (Synthesis of Polymer (P6)) Polymer (P6) was obtained by the same method as in Example 1, except that the amounts of each compound added were 1.1850 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.057 g of 4,4'-dichlorodiphenyl sulfone, 0.981 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 0.720 g of potassium carbonate. Polymer (P6) is a polymer having the structure represented by the above formula (P4), where x in the above formula (P4) is approximately 0.87 (0.83 to 0.91), y is approximately 0.13 (0.09 to 0.17), and n is approximately 20. In addition, the content of constituent units derived from the hydrophobic monomer (M2) was 50 mol% of the total amount of all constituent units that make up polymer (P6). The yield of polymer (P6) was 80%. The polymer (P6), measured in the same manner as in Comparative Example 2, had a Mn of 35,000, a Mw of 68,000, and a Mw / Mn ratio of 1.9. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.85–6.87 ppm.

[0198] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 3 (electrolyte membrane made of proton-substituted polymer (P6), thickness 64 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P6) was used instead of polymer (P1) and the thickness of the film made of polymer (P6) was adjusted to 64 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 3 was 2.49 mmol / g.

[0199] (Evaluation) The electrolyte membrane of Example 3 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 205 mS / cm, confirming that the electrolyte membrane of Example 3 has excellent proton conductivity. The volume swelling rate was 50%, confirming that the electrolyte membrane of Example 3 has excellent swelling resistance. The hydrogen gas permeability was 0.20 × 10⁻⁶. －７cm ３ mm / (cm) ２ The pressure was s·kPa, confirming that the electrolyte membrane of Example 3 has excellent gas barrier properties.

[0200] <Example 4> (Synthesis of polymer (P7)) 3.1050 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.8212 g of disodium diphenylsulfone-4,4'-dichloro-3,3'-disulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.9959 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 2.5862 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130°C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130°C for 150 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 900 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P7) having the structure represented by the above formula (P7). The yield was 81%.

[0201] In polymer (P7), x in the above formula (P7) was approximately 0.66 (0.62 to 0.70), y was approximately 0.34 (0.30 to 0.38), and n was approximately 17. Furthermore, the content of constituent units derived from the hydrophobic monomer (M2) was 50 mol% of the total amount of all constituent units constituting polymer (P7). The Mn of polymer (P7), measured in the same manner as in Comparative Example 2, was 22,000, Mw was 68,000, and Mw / Mn was 3.1. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.85–6.87 ppm.

[0202] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 4 (electrolyte membrane made of proton-substituted polymer (P7), thickness 64 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P7) was used instead of polymer (P1) and the thickness of the film made of polymer (P7) was adjusted to 64 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 4 was 2.42 mmol / g.

[0203] (Evaluation) The electrolyte membrane of Example 4 was evaluated in the same manner as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 174 mS / cm, confirming that the electrolyte membrane of Example 4 has excellent proton conductivity. The volume swelling rate was 46%, confirming that the electrolyte membrane of Example 4 has excellent swelling resistance. The hydrogen gas permeability was 0.23 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 4 has excellent gas barrier properties.

[0204] <Example 5> (Synthesis of polymer (P8)) In a 200 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, 7.36 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.43 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 8.88 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 11.2 g of potassium carbonate were added, and the mixture was purged with nitrogen. Then, 50 mL of DMSO and 50 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 90 hours. Then, 0.40 g of decafluorobiphenyl was added, and the reaction was continued for another 3 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 1200 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain a polymer (P8) containing multiple polymer units having the structure represented by the above formula (P4), and having a decafluorobiphenyl-derived crosslinking group that bonds to three or more of the polymer units. The yield was 96%. The Mn of polymer (P8), measured in the same manner as in Comparative Example 2, was 22,000, Mw was 91,000, and Mw / Mn was 4.1. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.85–6.87 ppm.

[0205] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 5 (electrolyte membrane made of proton-substituted polymer (P8), thickness 67 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P8) was used instead of polymer (P1) and the thickness of the film made of polymer (P8) was adjusted to 67 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 5 was 2.27 mmol / g.

[0206] (Evaluation) The electrolyte membrane of Example 5 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 168 mS / cm, confirming that the electrolyte membrane of Example 5 has excellent proton conductivity. The volume swelling rate was 42%, confirming that the electrolyte membrane of Example 5 has excellent swelling resistance. The hydrogen gas permeability was 0.20 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, confirming that the electrolyte membrane of Example 5 has excellent gas barrier properties.

[0207] <Example 6> (Synthesis of polymer (P9)) 7.47 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.43 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 9.40 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 11.2 g of potassium carbonate were added to a 200 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and the mixture was purged with nitrogen. Then, 50 mL of DMSO and 50 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 90 hours. Then, 0.047 g of decafluorobiphenyl was added, and the reaction was continued for another 3 hours. After the reaction solution was allowed to cool to room temperature, it was reprecipitated and purified from 1200 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain a polymer (P9) containing multiple polymer units with the structure represented by the above formula (P4), and having decafluorobiphenyl-derived crosslinking groups that bond to three or more of the polymer units. The yield was 91%. The Mn of polymer (P9), measured in the same manner as in Comparative Example 2, was 57,000, Mw was 360,000, and Mw / Mn was 6.3. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.78–6.82 ppm.

[0208] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 6 (electrolyte membrane made of proton-substituted polymer (P9), thickness 28 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P9) was used instead of polymer (P1) and the thickness of the film made of polymer (P9) was adjusted to 28 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 6 was 2.28 mmol / g.

[0209] (Evaluation) The electrolyte membrane of Example 6 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 156 mS / cm, confirming that the electrolyte membrane of Example 6 has excellent proton conductivity. The volume swelling rate was 57%, confirming that the electrolyte membrane of Example 6 has excellent swelling resistance. The hydrogen gas permeability was 0.19 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 6 has excellent gas barrier properties.

[0210] <Example 7> (Synthesis of polymer (P10)) 1.30 g of the hydrophobic monomer (M3) obtained in Synthesis Example 3, 0.77 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.37 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.39 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 120 hours. After allowing the reaction mixture to cool to room temperature, reprecipitation purification was performed from 300 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P10) having the structure represented by the above formula (P10). The yield was 84%.

[0211] In polymer (P10), x in the above formula (P10) was approximately 0.36 (0.32 to 0.40), y was approximately 0.64 (0.60 to 0.68), and n was approximately 40. Furthermore, the content of constituent units derived from hydrophobic monomer (M3) was 50 mol% of the total amount of all constituent units constituting polymer (P10). The Mn of polymer (P10), measured in the same manner as in Comparative Example 2, was 30,000, Mw was 130,000, and Mw / Mn was 4.3. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.89–6.91 ppm.

[0212] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 7 (electrolyte membrane made of proton-substituted polymer (P10), thickness 28 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P10) was used instead of polymer (P1), and the thickness of the film made of polymer (P10) was adjusted to 28 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 7 was 1.54 mmol / g.

[0213] (Evaluation) The electrolyte membrane of Example 7 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 135 mS / cm, confirming that the electrolyte membrane of Example 7 has excellent proton conductivity. The volume swelling rate was 46%, confirming that the electrolyte membrane of Example 7 has excellent swelling resistance. The hydrogen gas permeability was 0.11 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 7 has excellent gas barrier properties.

[0214] <Example 8> (Synthesis of polymer (P11)) 2.11 g of the hydrophobic monomer (M4) obtained in Synthesis Example 4, 0.52 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.82 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.82 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 110 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 400 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P11) having the structure represented by the above formula (P11). The yield was 84%.

[0215] In polymer (P11), x in the above formula (P11) was approximately 0.53 (0.49 to 0.57), y was approximately 0.47 (0.43 to 0.51), and n was approximately 19. Furthermore, the content of constituent units derived from the hydrophobic monomer (M4) was 50 mol% of the total amount of all constituent units constituting polymer (P11). The Mn of polymer (P11), measured in the same manner as in Comparative Example 2, was 20,000, Mw was 77,000, and Mw / Mn was 3.9. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.85–6.87 ppm.

[0216] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 8 (electrolyte membrane made of proton-substituted polymer (P11), thickness 32 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P11) was used instead of polymer (P1), and the thickness of the membrane made of polymer (P11) was adjusted to 32 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 8 was 1.69 mmol / g.

[0217] (Evaluation) The electrolyte membrane of Example 8 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 134 mS / cm, confirming that the electrolyte membrane of Example 8 has excellent proton conductivity. The volume swelling rate was 46%, confirming that the electrolyte membrane of Example 8 has excellent swelling resistance. The hydrogen gas permeability was 0.16 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 8 has excellent gas barrier properties.

[0218] <Example 9> (Synthesis of polymer (P12)) 2.98 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 0.44 g of 4,4'-dihydroxybiphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.), 3.39 g of diphenylsulfone-4,4'-dichloro-3,3'-disulfonic acid disodium (manufactured by Tokyo Chemical Industry Co., Ltd.), and 6.74 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 135 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 600 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P12) having the structure represented by the above formula (P12). The yield was 91%.

[0219] In polymer (P12), x in the above formula (P12) was approximately 0.34 (0.30 to 0.38), y was approximately 0.66 (0.62 to 0.70), and n was approximately 40. Furthermore, the content of constituent units derived from hydrophobic monomer (M2) was 33 mol% of the total amount of all constituent units constituting polymer (P12). The Mn of polymer (P12), measured in the same manner as in Comparative Example 2, was 35,000, Mw was 130,000, and Mw / Mn was 3.7. １When the 1H-NMR spectrum was measured, a peak was observed at 6.85.

[0220] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 9 (electrolyte membrane made of proton-substituted polymer (P12), thickness 73 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P12) was used instead of polymer (P1), and the thickness of the film made of polymer (P12) was adjusted to 73 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 9 was 2.13 mmol / g.

[0221] (Evaluation) The electrolyte membrane of Example 9 was evaluated using the same method as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 167 mS / cm, confirming that the electrolyte membrane of Example 9 has excellent proton conductivity. The volume swelling rate was 54%, confirming that the electrolyte membrane of Example 9 has excellent swelling resistance. The hydrogen gas permeability was 0.18 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 9 has excellent gas barrier properties.

[0222] <Example 10> (Synthesis of polymer (P13)) 1.81 g of the hydrophobic monomer (M5) obtained in Synthesis Example 5, 0.31 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.37 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 4.34 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 115 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 300 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P13) having the structure represented by the above formula (P13). The yield was 75%.

[0223] In polymer (P13), x in the above formula (P13) was approximately 0.70 (0.66 to 0.74), y was approximately 0.30 (0.26 to 0.34), and n was approximately 20. Furthermore, the content of constituent units derived from hydrophobic monomer (M5) was 50 mol% of the total amount of all constituent units constituting polymer (P13). The Mn of polymer (P13), measured in the same manner as in Comparative Example 2, was 21,000, Mw was 98,000, and Mw / Mn was 4.7. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.87–6.89 ppm.

[0224] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 10 (electrolyte membrane made of proton-substituted polymer (P13), thickness 29 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P13) was used instead of polymer (P1), and the thickness of the membrane made of polymer (P13) was adjusted to 29 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 10 was 2.29 mmol / g.

[0225] (Evaluation) The electrolyte membrane of Example 10 was evaluated in the same manner as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 191 mS / cm, confirming that the electrolyte membrane of Example 10 has excellent proton conductivity. The volume swelling rate was 60%, confirming that the electrolyte membrane of Example 10 has excellent swelling resistance. The hydrogen gas permeability was 0.14 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 10 has excellent gas barrier properties.

[0226] <Example 11> (Synthesis of polymer (P14)) 1.67 g of 4,4'-bis(4-hydroxyphenyl)diphenylsulfone (BLDpharm), 0.70 g of 4,4'-dichlorodiphenylsulfone (Tokyo Chemical Industries, Ltd.), 1.59 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.78 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 108 hours. After allowing the reaction mixture to cool to room temperature, reprecipitation purification was performed from 300 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P14) having the structure represented by the above formula (P14). The yield was 93%.

[0227] In polymer (P14), x in the above formula (P14) was approximately 0.42 (0.38 to 0.46), y was approximately 0.58 (0.54 to 0.62), and n was approximately 26. Furthermore, the content of constituent units derived from the hydrophobic monomer 4,4'-bis(4-hydroxyphenyl)diphenylsulfone was 50 mol% of the total amount of all constituent units constituting polymer (P14). The Mn of polymer (P14), measured in the same manner as in Comparative Example 2, was 22,000, Mw was 46,000, and Mw / Mn was 2.1. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.77–6.93 ppm.

[0228] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 11 (electrolyte membrane made of proton-substituted polymer (P14), thickness 26 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P14) was used instead of polymer (P1), and the thickness of the membrane made of polymer (P14) was adjusted to 26 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 11 was 1.67 mmol / g.

[0229] (Evaluation) The electrolyte membrane of Example 11 was evaluated in the same manner as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 137 mS / cm, confirming that the electrolyte membrane of Example 11 has excellent proton conductivity. The volume swelling rate was 58%, confirming that the electrolyte membrane of Example 11 has excellent swelling resistance. The hydrogen gas permeability was 0.14 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 11 has excellent gas barrier properties.

[0230] <Example 12> (Synthesis of polymer (P15)) 1.53 g of the hydrophobic monomer (M6) obtained in Synthesis Example 6, 0.35 g of 4,4'-dichlorodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.08 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 3.98 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 20 mL of DMSO and 20 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 120 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 300 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P15) having the structure represented by the above formula (P15). The yield was 84%.

[0231] In polymer (P15), x in the above formula (P15) was approximately 0.65 (0.61 to 0.69), y was approximately 0.35 (0.31 to 0.39), and n was approximately 28. Furthermore, the content of constituent units derived from hydrophobic monomer (M6) was 50 mol% of the total amount of all constituent units constituting polymer (P15). The Mn of polymer (P15), measured in the same manner as in Comparative Example 2, was 28,000, Mw was 110,000, and Mw / Mn was 3.9. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.81–6.94 ppm.

[0232] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 12 (electrolyte membrane made of proton-substituted polymer (P15), thickness 26 μm) was obtained by the same method as in Comparative Example 2, except that polymer (P15) was used instead of polymer (P1), and the thickness of the film made of polymer (P15) was adjusted to 26 μm. When the ion exchange capacity was measured by the same method as in Comparative Example 1, the IEC of the electrolyte membrane of Example 12 was 2.08 mmol / g.

[0233] (Evaluation) The electrolyte membrane of Example 12 was evaluated in the same manner as in Comparative Example 1 (proton conductivity evaluation, volume swelling rate measurement, and hydrogen gas permeability test). The proton conductivity was 132 mS / cm, confirming that the electrolyte membrane of Example 12 has excellent proton conductivity. The volume swelling rate was 58%, confirming that the electrolyte membrane of Example 12 has excellent swelling resistance. The hydrogen gas permeability was 0.16 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, and it was confirmed that the electrolyte membrane of Example 12 has excellent gas barrier properties.

[0234]

[0235] This application is based on Japanese patent applications filed on 27 September 2024 (JP 2024-169431) and on 24 January 2025 (JP 2025-010414), which are incorporated by reference in their entirety. All references cited herein are incorporated as a whole.

Claims

1. A polymer comprising a structural unit A represented by the following formula (a1) and a structural unit B represented by the following formula (a2). [In formula (a1), IExG represents an ion exchange group, and L １ represents a single bond, -O-, -S- or -SO ２ -, x represents an integer of 1 to 10, and * represents a bond. A plurality of IExG may be the same as or different from each other, and a plurality of L １ may be the same as or different from each other. ] [In formula (a2), Ar １ represents an arylene group having no ion exchange group, and L ２ represents a single bond, -O-, -S- or -SO ２ -, y represents an integer of 3 to 20, and * represents a bond. A plurality of Ar １ may be the same as or different from each other, and a plurality of L ２ may be the same as or different from each other. However, the number of L ２ that is a single bond is an integer of 0.5y or more and less than 1.0y. ] 2. The polymer according to claim 1, wherein the constituent unit A comprises at least one group selected from the group consisting of a sulfonic acid group, an alkyl sulfonic acid group, a sulfonimide group, and salts thereof, as the ion exchange group.

3. The polymer according to claim 1 or 2, wherein the constituent unit B comprises at least one group selected from the group consisting of a phenylene group, a naphthylene group, and a fluorene group, which may have substituents, as the arylene group.

4. The polymer according to any one of claims 1 to 3, wherein the constituent unit B includes a structure in which at least three consecutive arylene groups are bonded together by single bonds.

5. The polymer according to any one of claims 1 to 4, wherein the content of the constituent unit B is 25 to 75 mol% of the total amount of all constituent units that make up the polymer.

6. The polymer according to any one of claims 1 to 5, comprising a plurality of polymer units including the constituent unit A and the constituent unit B, and having a crosslinking group that bonds with three or more of the polymer units.

7. The polymer according to any one of claims 1 to 6, wherein the weight-average molecular weight is 40,000 to 500,000.

8. Use tetramethylsilane as the internal standard. １ The polymer according to any one of claims 1 to 7, having a peak in the range of 6.70 to 6.95 ppm in the 1H-NMR spectrum.

9. The polymer according to any one of claims 1 to 8, wherein the ion exchange capacity is 1.0 to 3.5 mmol / g.

10. An electrolyte material containing the polymer described in any one of claims 1 to 9.

11. An electrolyte membrane containing the polymer described in any one of claims 1 to 9.

12. An electrolyte membrane with a catalyst layer, comprising the electrolyte membrane according to claim 11, and a catalyst layer disposed on one or both sides of the electrolyte membrane.

13. A membrane electrode assembly comprising an electrolyte membrane according to claim 11, and an electrode layer disposed on one or both sides of the electrolyte membrane.

14. A polymer electrolyte fuel cell comprising the membrane electrode assembly described in claim 13.

15. A solid polymer water electrolysis apparatus comprising the membrane electrode assembly described in claim 13.

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