Polyelectrolyte membrane having, as base therefor, polymer having high density of acidic functional groups

Abstract

The present invention provides a novel polyelectrolyte membrane and a monomer that has, through a spacer structure, a composite polymer membrane, an ionomer for a solid polymer-type fuel cell, a phosphonate group, and / or a phosphonate ester and exhibits a conductivity of at least 1.0 × 10–3 S / cm. A polyelectrolyte membrane and a monomer that has, through a spacer structure, a composite polymer membrane, an ionomer for a solid polymer-type fuel cell, a phosphonate group, and / or a phosphonate ester and exhibits a conductivity of at least 1.0 × 10–3S / cm.

Description

Polymer electrolyte membranes based on polymers with a high density of acidic functional groups

[0001] The present invention relates to polymer electrolyte membranes based on polymers with a high density of acidic functional groups.

[0002] Fuel cells, which are expected to be a clean power generation system, generate electrical energy by electrochemically reacting hydrogen and oxygen using the reverse reaction of water electrolysis. In particular, solid polymer fuel cells, which use a polymer electrolyte membrane, are used in fuel cell vehicles and other applications.

[0003] A solid polymer fuel cell's basic component is a membrane electrode assembly (MEA), which is made by sandwiching a proton-conducting membrane called a polymer electrolyte membrane between gas diffusion electrodes consisting of a gas diffusion layer and a catalyst layer containing an ionomer. If protons do not move properly in the electrolyte membrane, the fuel cell reaction will not occur, and excellent power generation characteristics (high output) will not be obtained. Therefore, it is important to use a polymer electrolyte membrane that exhibits high proton conductivity (e.g., 0.1 S / cm or higher), and the polymer electrolyte membrane is considered one of the most important components in a fuel cell.

[0004] Currently, the electrolyte membranes used in commercially available fuel cell vehicles and the like are made of perfluorosulfonic acid polymers, such as Nafion® developed by DuPont. When the membrane is moistened at 70 to 90°C, protons move along the water molecules, achieving high proton transport capacity (proton conductivity > 0.1 S / cm).

[0005] Furthermore, by humidifying a chemically crosslinked random copolymer of polystyrene and polystyrene sulfonic acid, which is obtained by sulfonating a chemically crosslinked polystyrene, a proton conductivity of approximately 0.1 S / cm can be achieved if the proportion of polystyrene sulfonic acid is high.

[0006] While the development of polymer electrolyte membranes that exhibit high proton conductivity of 0.1 S / cm or more under such humidified conditions continues, progress is also being made in the development of proton-conducting polymer electrolyte membranes that exhibit high proton conductivity of about 0.1 S / cm even when the membrane is not sufficiently humidified and not wetted sufficiently.

[0007] Patent Literature 1 discloses a proton conducting membrane (electrolyte membrane) that exhibits proton conductivity in an unhumidified state, the proton conducting membrane comprising: a polymer having a glassy or crystalline first site and a second site having a functional group capable of non-covalently bonding to other molecules, the polymer having a glassy or crystalline first site and a glass transition temperature or melting temperature higher than the operating temperature of the proton conducting membrane; and a proton conducting substance that contains a proton releasing / binding site, the proton releasing / binding site having a functional group capable of non-covalently bonding to the second site of the polymer, and a proton coordinating site capable of coordinating to a proton, either in different interacting molecules or in the same molecule. The glass transition temperature of a proton conducting mixed phase containing the proton conducting substance and the second site to which the proton releasing / binding site is bound is lower than the operating temperature of the proton conducting membrane, and the proton releasing / binding site is present in excess of the second site of the polymer. This unhumidified proton conducting membrane exhibits proton conductivity even in an unhumidified state.

[0008] Patent Document 2 discloses a solid polymer electrolyte membrane containing a crosslinked polymer and a plasticizer, at least one of which has a proton-releasing group.

[0009] Patent Literature 3 discloses a proton conducting membrane (electrolyte membrane) comprising a polymer having first and second portions linked by a covalent bond, and a plasticizer, wherein the first portions aggregate to form domains at the operating temperature of the proton conducting membrane, and the second portions bridge the domains, the second portions have proton-accepting groups, and the plasticizer comprises a proton-donating compound having a pKa of 2.5 or less, thereby allowing the plasticizer to penetrate the second portions and lowering the glass transition temperature of the polymer compared to a membrane containing no plasticizer. This proton conducting membrane (electrolyte membrane) can exhibit high proton conductivity even in a low-humidity or non-humidified environment, and is suitable for use as a proton conducting membrane in a fuel cell in a low-humidity or non-humidified environment.

[0010] Non-Patent Document 1 discloses a conventional method for synthesizing a block copolymer containing an acidic functional group that exhibits strong acidity. In this synthesis method, a sulfonation reaction is carried out after polymer synthesis, and due to the harsh reaction conditions, it is difficult to sulfonate only specific sites selectively and with high reaction efficiency. As a result, not only the styrene moiety in the polymer is sulfonated, but also the tert-butylstyrene, and the role of the mechanical strength phase and the conductive phase of the polymer is not fully achieved.

[0011] Non-Patent Document 2 discloses a method for producing a phosphoric acid-doped polybenzimidazole film by a conventional sol-gel process. It is stated that this film functions as an electrolyte membrane for fuel cells at temperatures above 150°C without humidification.

[0012] It is believed that when the electrolyte membranes described in Patent Documents 1 to 3 and Non-Patent Documents 1 and 2 are brought into contact with water generated in a fuel cell reaction, the low molecular weight electrolytes and low molecular weight compounds in the membranes have hydrophilic sites and are therefore eluted into water.

[0013] International Publication WO2017 / 183397A1 JP 2018-190647 A JP 2020-68130 A

[0014] J. Mater. Chem. , 2012, 22, 25262-25271Chem. Mater. , 2005, 17, 5328-5333

[0015] The present invention newly provides a polymer electrolyte membrane.

[0016] The present invention newly provides 1.0×10 －３ The present invention provides a composite polymer membrane exhibiting a conductivity of 100 S / cm or more, an ionomer for a polymer electrolyte fuel cell, and a monomer having a phosphonic acid group and / or a phosphonic acid ester via a spacer structure.

[0017] The present invention that achieves the above object is as follows.

[0018] Item A The present invention provides a polymer having an acidic functional group (including a polymer composed of a monomer unit having a phosphonic acid group via a spacer structure) (items 1 to 12).

[0019] Item B The present invention provides a composite polymer membrane (including a composite polymer membrane composed of a polymer composed of a monomer unit having a phosphonic acid group / a basic polymer via a spacer structure) (items 13 to 23).

[0020] Item C The present invention provides a monomer having a phosphonic acid group and / or a phosphonate ester via a spacer structure (items 24 to 26).

[0021] Item A Polymer Electrolyte Membrane Item 1. A polymer electrolyte membrane comprising a polymer having an acidic functional group, wherein the polymer is: (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, (ii) a chemically crosslinked polymer having an acidic functional group in a side chain, and / or (iii) a polymer composed of monomer units having a phosphonic acid group via a spacer structure, wherein the polymer does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group, wherein the a block of (i) is composed of a hydrophobic polymer or a water-repellent polymer, and the b block of (i) is composed of a polymer having an acidic functional group in a side chain or the polymer of (iii), or the side chain of the b block of (i) is composed of a graft chain (polymer) including a monomer unit having an acidic functional group.

[0022] The "side chain" refers to a functional group branching off from the main chain (corresponding to the central part of the chain, trunk) of a chain compound (generally a polymer), a unit containing a functional group, or a graft chain (branch, branch polymer).

[0023] Item 2. The polymer electrolyte membrane according to Item 1, wherein the acidic functional group is an acidic functional group composed of at least one type selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0024] Item 3. The polymer electrolyte membrane according to Item 1 or 2, further comprising an ionic low-molecular-weight organic salt.

[0025] The "ionic low-molecular-weight organic salt" generally refers to a compound having a molecular weight of 800 or less, such as ethylmethylimidazolium bromide.

[0026] The "ionic low molecular weight organic salt" is a salt obtained by converting a basic compound into an alkyl halide (C ｎ H ２ｎ＋１ It can be synthesized by quaternizing with -X (n: natural number, X=F, Cl, Br, I) etc.

[0027] Item 4. The polymer electrolyte membrane according to any one of Items 1 to 3, wherein in the b block (i), the polymer having an acidic functional group in a side chain, the polymer (iii), or the graft chain containing an acidic functional group constituting a side chain in a monomer unit, the polymer (ii), and the polymer (iii) are hydrocarbon-based vinyl polymers containing 0.70 or more acidic functional groups in a monomer unit.

[0028] In other words, in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or the graft chain containing an acidic functional group constituting a side chain in a monomer unit is a hydrocarbon vinyl polymer and is a polymer containing an average of 0.70 or more acidic functional groups in a monomer unit.

[0029] In other words, the polymer (ii) is a hydrocarbon vinyl polymer containing an average of 0.70 or more acidic functional groups per monomer unit.

[0030] In other words, the polymer (iii) is a hydrocarbon vinyl polymer containing an average of 0.70 or more acidic functional groups per monomer unit.

[0031] Item 5. The polymer electrolyte membrane according to any one of Items 1 to 4, wherein in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or a graft chain containing an acidic functional group constituting a side chain in a monomer unit, the polymer of (ii), and the polymer of (iii) are obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and the polymer is a polymer containing 0.70 or more of the acidic functional groups in the monomer unit.

[0032] In other words, in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or the graft chain containing an acidic functional group constituting a side chain in a monomer unit is a polymer obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and is a polymer containing an average of 0.70 or more acidic functional groups in the monomer unit.

[0033] In other words, the polymer (ii) is a polymer obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and the polymer contains an average of 0.70 or more acidic functional groups per monomer unit.

[0034] In other words, the polymer (iii) is a polymer obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and the polymer contains an average of 0.70 or more acidic functional groups per monomer unit.

[0035] Item 6. The polymer electrolyte membrane according to any one of Items 1 to 5, wherein the hydrophobic polymer or water-repellent polymer constituting the a block (i) is a hydrophobic hydrocarbon-based vinyl polymer, a water-repellent hydrocarbon-based vinyl polymer, or a fluorocarbon-based vinyl polymer, and is a polymer having a glass transition temperature (Tg) of 100° C. or higher.

[0036] Item 7. The polymer electrolyte membrane according to any one of Items 1 to 6, further comprising a hydrophobic polymer or a water-repellent polymer in addition to the polymer (i) containing a block copolymer having a-b type units in which at least the a block and the b block are linked by a covalent bond.

[0037] Item 8. The polymer electrolyte membrane according to any one of items 1 to 7, further comprising a proton donating agent when the polymer electrolyte membrane comprises: (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond; and / or (iii) a polymer composed of monomer units having a phosphonic acid group via a spacer structure, the polymer containing no highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group.

[0038] Item 9. The polymer electrolyte membrane according to Item 8, wherein the proton donating agent is at least one selected from the group consisting of sulfuric acid and phosphoric acid.

[0039] Item 10. A method for producing a polymer electrolyte membrane, comprising: (A) preparing a hydrophobic polymer to produce an a block; (B) polymerizing a monomer having an acidic functional group protected by a protecting group, or a monomer having a phosphonic acid group protected by a protecting group via a spacer structure, with the a block to form a b block, producing a block copolymer having a-b type units in which the a block and the b block formed by polymerization of units of the monomer are linked by a covalent bond; and (C) deprotecting the protecting group in the b block to produce a polymer having 0.70 or more of the acidic functional group or the phosphonic acid group in a side chain, by deprotecting the protecting group in the b block.

[0040] Item 11. The method for producing a polymer electrolyte membrane according to Item 10, further comprising: (D) a step of mixing a hydrophobic polymer or a water-repellent polymer having a molecular weight of 100,000 or more.

[0041] Item 12. The method for producing a polymer electrolyte membrane according to Item 10 or 11, further comprising: (E) a step of mixing a proton donor.

[0042] The present invention newly provides 1.0×10 －３ A composite polymer membrane exhibiting a conductivity of 100 S / cm or more is provided.

[0043] Item B Composite polymer membrane Item 13. Comprising (1) a polymer having an acidic functional group, and (2) a polymer having a basic functional group, wherein the (1) polymer having an acidic functional group is (i) a block copolymer having an a-b type unit in which at least an a block and a b block are connected by a covalent bond, (ii) a chemically crosslinked polymer having an acidic functional group in a side chain, and / or (iii) a polymer consisting of monomer units having a phosphonic acid group via a spacer structure, and which does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group, wherein the (i) a block is composed of a hydrophobic polymer or a water-repellent polymer, and the (i) b block is composed of a polymer having an acidic functional group in a side chain or the (iii) polymer, or the (i) b block side chain is composed of a graft chain containing an acidic functional group in a monomer unit, 1.0 x 10 －３ A composite polymer membrane exhibiting a conductivity of 100 S / cm or more.

[0044] Item 14. The composite polymer membrane according to Item 13, wherein the acidic functional group is an acidic functional group composed of at least one type selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0045] Item 15. The composite polymer membrane according to Item 13 or 14, wherein the (1) polymer having an acidic functional group is a polymer containing a monomer unit having an acidic functional group composed of at least one selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid.

[0046] Item 16. The composite polymer film according to any one of Items 13 to 15, wherein the (2) polymer having a basic functional group is a polymer having five or more basic functional groups composed of at least one selected from the group consisting of amino groups, imino groups, pyridyl groups, imidazolyl groups, pyrazolyl groups, pyrrolyl groups, and triazolyl groups, or a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of a polymer having five or more basic functional groups composed of at least one selected from the group consisting of amino groups, imino groups, pyridyl groups, imidazolyl groups, pyrazolyl groups, pyrrolyl groups, and triazolyl groups.

[0047] Item 17. The composite polymer film according to any one of Items 13 to 16, wherein the (2) polymer having a basic functional group is a polymer containing five or more monomer units having a basic functional group, the monomer units being composed of at least one selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, and vinylpyrrole, or a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of a polymer containing five or more monomer units composed of at least one selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, vinylpyrole, and vinyltriazole.

[0048] Item 18. The composite polymer membrane according to any one of Items 13 to 17, wherein the (2) polymer having a basic functional group is a polymer having a cationic functional group based on the basic functional group, and a part of the basic functional group is quaternized with an organic halogen compound to generate a cation, forming a cationic functional group based on the basic functional group.

[0049] Item 19. The composite polymer membrane according to any one of Items 13 to 18, wherein the proportion of cationic functional groups based on basic functional groups among the basic functional groups is 10 mol % or more.

[0050] Item 20. The composite polymer film according to Item 18 or 19, wherein the organic halogen compound is a compound having an alkyl halide moiety.

[0051] The "compound having an alkyl halide moiety" is a compound having an alkyl halide moiety, ｎ H ２ｎ＋１ -X (n: natural number, X=F, Cl, Br, I), and R-C ｎ H ２ｎ The compound is a compound represented by —X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and is particularly preferably an alkyl halide.

[0052] Item 21. A polymer having an anionic group based on an acidic functional group, which is obtained by combining the polymer having an acidic functional group (1) with the polymer having a cationic functional group based on a basic functional group, so that a proton is ionized from the acidic functional group of the polymer having the acidic functional group (1) to form an anionic functional group, and a low-molecular-weight acid composed of a counter anion of the cationic functional group of the polymer having the cationic functional group based on a basic functional group and a proton escapes from the membrane, and the polymer having a cationic group based on a basic functional group, －３ 21. The composite polymer membrane according to any one of items 18 to 20, which exhibits a conductivity of 100 S / cm or more.

[0053] Item 22. The composite polymer membrane according to any one of Items 13 to 21, wherein the composite polymer membrane is a composite membrane that, even when immersed in water at 60°C for 1 hour, does not show a difference in conductivity of 25% or more compared to a membrane that is not immersed.

[0054] The present invention provides a novel ionomer for use in polymer electrolyte fuel cells.

[0055] Item 23. An ionomer for a polymer electrolyte fuel cell, comprising the polymer according to any one of Items 1 to 9, or the composite polymer constituting the composite polymer membrane according to any one of Items 13 to 22.

[0056] The present invention newly provides a monomer having a phosphonic acid group and / or a phosphonate ester via a spacer structure.

[0057] Item C Monomer Item 24. A monomer having a phosphonic acid group and / or a phosphonic acid ester via a spacer structure, and not containing a highly hydrolyzable functional group between the part that becomes the main chain skeleton of the polymer after polymerization and the phosphonic acid group and / or phosphonic acid ester that is part of the side chain of the polymer after polymerization.

[0058] The "portion that will become the main chain skeleton of the polymer after polymerization" refers to the portion that will become the main chain (corresponding to the center of the chain, trunk) of a chain compound (generally a polymer). In the case of a vinyl monomer, it is generally a vinyl group CH ２ =CH-. A functional group branching off from the main chain skeleton, a unit containing a functional group, or a graft chain (branch, branch polymer) is referred to as a "side chain."

[0059] Item 25. The monomer according to Item 24, wherein the spacer structure is an alkyl spacer.

[0060] Item 26. The monomer according to Item 24 or 25, wherein the spacer structure is an alkyl spacer having 2 to 12 repeating methylene groups.

[0061] The present invention can provide a new polymer electrolyte membrane.

[0062] The polymer electrolyte membrane of the present invention can be suitably used particularly as a proton conducting membrane in a fuel cell.

[0063] The present invention newly provides 1.0×10 －３ It is possible to provide a composite polymer membrane that exhibits a conductivity of 100 S / cm or more.

[0064] The present invention can provide a new ionomer for use in polymer electrolyte fuel cells.

[0065] The present invention can newly provide a monomer having a phosphonic acid group and / or a phosphonate ester via a spacer structure.

[0066] The phosphonic acid polymer-based composite polymer membrane of the present invention can be suitably used under both non-humidified and humidified conditions.

[0067] The composite polymer membrane (electrolyte membrane) of the present invention includes a polymer-based composite polymer membrane (electrolyte membrane) composed of monomer units having phosphonic acid and / or phosphonate ester via a spacer structure, and since the membrane basically does not contain a low molecular weight electrolyte, elution of the low molecular weight electrolyte into liquid water does not occur, and in addition, elution of the polymer electrolyte from the membrane into liquid water is also suppressed, and －３ It exhibits good conductivity of 5 S / cm or more.

[0068] The composite polymer membrane (electrolyte membrane) of the present invention has a surface area of ​​1.0×10 －３ The resulting membrane exhibits a good conductivity of 100 S / cm or more, and is particularly suitable for use as a proton conducting membrane in a fuel cell.

[0069] The GPC chromatogram of Example 1 is shown. Dashed line: B-1 obtained in step 1-1. Solid line: B-nBsS-1 obtained in step 1-2. １ H-NMR spectrum is shown. Dotted line: B-nBsS-1 obtained in step 1-2. Solid line: B-sSA-1 obtained in step 2. Measurement results of proton conductivity at 80°C are shown. ●: Proton conductivity of Example 1. ×: Proton conductivity of Comparative Example 1. ▲: Proton conductivity of Example 2. ■: Proton conductivity of Example 3. Measurement results of proton conductivity at 95°C are shown. ●: Proton conductivity of Example 1. ×: Proton conductivity of Comparative Example 1. ▲: Proton conductivity of Example 2. ■: Proton conductivity of Example 3. １H-NMR spectrum is shown. Dotted line: B-nBsS-2. Solid line: B-sSA-2. GPC chromatogram of Example 2 is shown. Solid line: B-nBsS-2. Dashed line: precursor poly(4-tert-butylstyrene) (B-2). Results of tensile test of the proton-conductive electrolyte membrane (solid line) of Example 4 are shown. GPC chromatogram of Example 8 is shown. Solid line: B-EsP. Dashed line: precursor poly(4-tert-butylstyrene) (B-4). Results of tensile test of the proton-conductive electrolyte membrane of Example 8 are shown. １ H-NMR spectra are shown. Dotted line: B-4. Dashed line: B-EsP. Solid line: B-sPA. Thermograms (Tg) are shown. Dashed line: (Example 1) B-sSA-1. Solid line: (Example 8) B-sPA. １ The H-NMR spectra are shown. Upper: B-5, middle: B-(nBsS-co-EsP)-1, lower: B-(sSA-co-sPA)-1. １ The H-NMR spectrum is shown. Upper: CL-nBsS, lower: CL-sSA. １ The H-NMR spectrum is shown. Upper: CL-EsP, lower: CL-sPA. １ H-NMR spectra are shown. a: BrS, b: BrS-B, c: (BrS-g-EvP)-B, d: (BrS-g-vPA)-B. GPC chromatograms are shown for Example 14. Dotted line: BrS, dashed line: BrS-B, solid line: (BrS-g-EvP)-B. １ The H-NMR spectrum is shown. Upper row: 4-bromostyrene, middle row: 1-(4-bromobutyl)-4-vinylbenzene, lower row: 4-(4-vinylphenyl)butylphosphonic acid diethyl monomer. １３ The C-NMR spectrum is shown. Upper row: 4-bromostyrene, middle row: 1-(4-bromobutyl)-4-vinylbenzene, lower row: 4-(4-vinylphenyl)diethyl butylphosphonate monomer. ３１ The P-NMR spectrum of Example 28 is shown below. １1H-NMR spectrum is shown. Upper: poly(4-(4-vinylphenyl)butylphosphonic acid diethyl), lower: poly(4-(4-vinylphenyl)butylphosphonic acid). GPC chromatogram of poly(4-(4-vinylphenyl)butylphosphonic acid diethyl) of Example 28 is shown. Proton conductivity of Example 28 (●) and Comparative Example 6 (×) is shown. GPC chromatogram of B and B-EsbP of Example 32 is shown. １ The H-NMR spectra are shown: top: B, middle: B-EsbP, bottom: B-sbPA.

[0070] The present invention will be described in detail below.

[0071] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0072] In this specification, when a numerical range is expressed as "X to Y", it means X or more and Y or less.

[0073] As used herein, the prefix "poly" refers to a polymer containing two or more monomers.

[0074] Item A Polymer Electrolyte Membrane Conventionally, for example, the non-humidified proton conductive membrane disclosed in Patent Document 1 or the proton conductive membrane having a crosslinked structure disclosed in Patent Document 3 does not have an acidic group on the block polymer side, and even if a membrane made of only this block polymer is humidified, it does not exhibit conductivity. Furthermore, when a membrane containing a proton donor is humidified, an acidic liquid may leach from the membrane into the liquid water generated by humidification, and therefore, it is not suitable as a membrane for humidification.

[0075] Conventionally, for example, the solid polymer electrolyte membrane disclosed in Patent Document 2 does not have a high concentration of free protons in the membrane, and the proton conductivity exhibited in an unhumidified state is low, which is not as high as the conductivity of a membrane used in a humidified state.

[0076] The polymer electrolyte membrane of the present invention is a polymer electrolyte membrane based on a polymer having a high density of acidic functional groups.

[0077] The polymer electrolyte membrane of the present invention comprises a polymer having an acidic functional group, wherein the polymer is (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, the polymer is (ii) a chemically crosslinked polymer having an acidic functional group in a side chain, and / or the polymer is (iii) a polymer composed of monomer units having a phosphonic acid group via a spacer structure, and does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group, the a block of (i) being composed of a hydrophobic polymer or a water-repellent polymer, the b block of (i) being composed of a polymer having an acidic functional group in a side chain or the polymer of (iii), or the side chain of the b block of (i) being composed of a graft chain containing an acidic functional group in a monomer unit.

[0078] The "side chain" refers to a functional group branching off from the main chain (corresponding to the central part of the chain, trunk) of a chain compound (generally a polymer), a unit containing a functional group, or a graft chain (branch, branch polymer).

[0079] In the polymer electrolyte membrane of the present invention, the acidic functional group is preferably an acidic functional group composed of at least one type selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0080] The polymer electrolyte membrane of the present invention contains a polymer having an acidic functional group, and the polymer is (i) a block copolymer having at least an a-b type unit in which an a block and a b block are linked by a covalent bond.

[0081] In the polymer electrolyte membrane of the present invention, the polymer having an acidic functional group in a side chain that constitutes the b block is preferably a hydrocarbon-based vinyl polymer, and is a polymer that contains, on average, 0.70 or more, preferably 0.80 or more, more preferably 0.90 or more, preferably 0.95 or more, more preferably 0.98 or more acidic functional groups per monomer unit.

[0082] In the polymer electrolyte membrane of the present invention, the polymer having an acidic functional group in a side chain that constitutes the b block is preferably obtained by polymerizing a monomer having a protecting group on the acidic functional group, and then deprotecting the protecting group, and is a polymer containing, on average, 0.70 or more, 0.90 or more, preferably 0.95 or more, and more preferably 0.98 or more acidic functional groups per monomer unit.

[0083] In the polymer electrolyte membrane of the present invention, the a block (i) is composed of a hydrophobic polymer or a water-repellent polymer.

[0084] In the polymer electrolyte membrane of the present invention, the hydrophobic polymer or water-repellent polymer constituting the a block (i) is preferably a hydrophobic hydrocarbon-based vinyl polymer, a water-repellent hydrocarbon-based vinyl polymer, or a fluorocarbon-based vinyl polymer, and is a polymer having a glass transition temperature (Tg, measured by DSC) of 100°C or higher.

[0085] The hydrophobic polymer is a hydrophobic hydrocarbon vinyl polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher.

[0086] The water-repellent polymer is a water-repellent hydrocarbon vinyl polymer or a fluorocarbon vinyl polymer, and is a polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher.

[0087] The polymer electrolyte membrane of the present invention preferably contains a hydrophobic polymer or a water-repellent polymer having a molecular weight of 100,000 or more, in addition to the polymer (i) having a block copolymer having at least a-b type units in which the a block and the b block are linked by a covalent bond.

[0088] Polymer I Having Acidic Functional Groups The polymer electrolyte membrane of the present invention contains a polymer having acidic functional groups, and the polymer is (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, and the b block of (i) is composed of a polymer having an acidic functional group in its side chain.

[0089] The polymer having an acidic functional group in the side chain is a polymer containing a monomer unit having an acidic functional group composed of at least one selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid.

[0090] Polymer II Having Acidic Functional Groups The polymer electrolyte membrane of the present invention contains a polymer having acidic functional groups, and the polymer is (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, and the b block of (i) is composed of the polymer of (iii).

[0091] Polymer III Having an Acidic Functional Group The polymer electrolyte membrane of the present invention comprises a polymer having an acidic functional group, and the polymer is (i) a block copolymer having a-b type units in which at least an a block and a b block are connected by a covalent bond, and the side chain of the b block in (i) is composed of a graft chain containing an acidic functional group in the monomer unit.

[0092] The graft chain (polymer) containing a monomer unit having an acidic functional group is a graft chain containing a monomer unit having an acidic functional group that is composed of at least one acid selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid.

[0093] The "side chain" refers to a functional group branching off from the main chain (corresponding to the central part of the chain, trunk) of a chain compound (generally a polymer), a unit containing a functional group, or a graft chain (branch, branch polymer).

[0094] Polymer IV Having Acidic Functional Groups The polymer electrolyte membrane of the present invention contains a polymer having acidic functional groups, and the polymer is (ii) a chemically crosslinkable polymer having acidic functional groups in its side chains.

[0095] The chemically crosslinkable polymer having an acidic functional group in the side chain is a polymer in which a polymer consisting of a monomer unit having an acidic functional group in the side chain, such as poly(4-styrenesulfonic acid) or poly(4-styrenephosphonic acid), is chemically crosslinked with divinylbenzene or the like.

[0096] Polymer V Having Acidic Functional Group The polymer electrolyte membrane of the present invention contains a polymer having an acidic functional group, and the polymer is (iii) a polymer composed of monomer units having a phosphonic acid group via a spacer structure, and the polymer does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group.

[0097] The polymer having an acidic functional group is composed of a monomer unit, i.e., a polymer having an acidic functional group is a polymer composed of a monomer unit having an acidic functional group, a phosphonic acid and / or a phosphonate ester, in a side chain via a spacer structure.

[0098] The phosphonic acid and / or phosphonic acid ester present via a spacer structure (preferably an alkyl spacer) may exist, for example, one, two, or four per monomer unit, as shown in the following chemical structural formula.

[0099]

[0100] In the chemical structural formula of the polymer having an acidic functional group, Spacer represents a spacer structure, and is preferably an alkyl spacer.

[0101] In the polymer having an acidic functional group, R １ represents the main chain skeleton of the monomer unit (for example, -CH in the case of a polystyrene-based polymer). ２ -CH(C ６ H Ｘ )-. X represents 0 to 4. The number of phosphonic acids and / or phosphonate esters with a spacer structure is 1 or more, and may be 2, 3, 4, 5, 6, 8, 10 or more, and is not particularly limited.

[0102] In the polymer having an acidic functional group, R ２ represents a protecting group (particularly an alkyl protecting group) or a hydrogen atom (H).

[0103] The polymer having the acidic functional group has a phosphonic acid group and a spacer structure, which makes it easier for the phosphonic acid groups to be aligned closely together and makes it easier to form a continuous ion conduction channel (ion conduction path) compared to when the polymer does not have a spacer structure, thereby exhibiting good conductivity.

[0104] The polymer having an acidic functional group is preferably a hydrocarbon-based or hydrogen fluoride-based polymer, more preferably a vinyl polymer, and even more preferably a polystyrene-based polymer.

[0105] The polystyrene-based polymer preferably includes polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, polytrimethylstyrene, and the like.

[0106] The polymer having a phosphonic acid group in the side chain is preferably obtained by polymerizing a monomer having a phosphonic acid group protected with a protecting group via a spacer structure, and then deprotecting the protecting group.

[0107] The polymer having a phosphonic acid group in the side chain preferably does not contain a highly hydrolyzable functional group between the main chain skeleton of the polymer and the phosphonic acid group.

[0108] Highly hydrolyzable functional groups include, for example, amide bonds, imide bonds, urethane bonds, ester bonds, ether bonds, etc. Ionic functional groups such as ammonium, imidazolium, and pyridinium can also be considered as highly hydrolyzable functional groups.

[0109] The polymer having a phosphonic acid group in the side chain may further contain the following monomer unit.

[0110] For example, styrene, acetylstyrene, anisoylstyrene, benzoylstyrene, biphenylstyrene, bromoethoxystyrene, bromomethoxystyrene, bromostyrene, butoxymethylstyrene, tert-butylstyrene, butyrylstyrene, chlorofluorostyrene, chloromethylstyrene, chlorostyrene, cyanostyrene, dichlorostyrene, difluorostyrene, dimethylstyrene, ethoxymethylstyrene, ethoxystyrene, fluoromethylstyrene, fluorostyrene, iodostyrene, methoxycarbonylstyrene, methoxymethylstyrene, methylstyrene, methoxystyrene, perfluorostyrene, phenoxystyrene, phenylacetylstyrene, phenylstyrene, prostyrene, conjugated diene monomers such as 1,3-butadiene and isoprene (2-methyl-1,3-butadiene); α,β-unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acid anhydride monomers such as maleic anhydride, butenyl succinic anhydride, tetrahydrophthalic anhydride and citraconic anhydride; unsaturated carboxylic acid ester monomers such as methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate and 2-ethylhexyl methacrylate; and non-conjugated diene monomers preferably having 5 to 12 carbon atoms such as 1,4-pentadiene and 1,4-hexadiene.

[0111] In the case of a polymer having a phosphonic acid group in a side chain, the phosphonate ester can be deprotected to give the phosphonic acid group. For example, when synthesizing a polymer, the polymer is formed with a protecting group, and then deprotected to form a polymer having a phosphonic acid group.

[0112] A polymer containing a phosphonate ester group, which is an acidic functional group, in a monomer unit is obtained by polymerizing a monomer having a phosphonate ester via a spacer structure and then deprotecting the polymer. The deprotection rate in the polymer is preferably 70% or more, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 100%.

[0113] Polymer II Having Acidic Functional Groups The polymer electrolyte membrane of the present invention contains a polymer having acidic functional groups, and the polymer is (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, and the b block of (i) is composed of the polymer of (iii).

[0114] The block copolymer of the present invention is a block copolymer having at least ab type units in which the a block and the b block are linked by a covalent bond.

[0115] In the block copolymer, the a block is composed of a hydrophobic or water-repellent polymer.

[0116] In the block copolymer, the b block is composed of a polymer having a phosphonic acid group in the side chain (polymer V having an acidic functional group).

[0117] The hydrophobic polymer is preferably a hydrophobic hydrocarbon-based vinyl polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher.

[0118] The block copolymer is a block copolymer having an a-b type unit in which at least an a block and a b block are linked by a covalent bond, and may further include a c block as a third portion, a d block as a fourth portion, etc.

[0119] Block copolymers also include so-called graft copolymers having a branched structure, and star copolymers.

[0120] In a membrane made of a block copolymer, the hydrophobic or water-repellent phase of polymer A maintains mechanical strength, while microscopic phase separation can occur between the phase of polymer B, which has ion channels derived from the polymer having phosphonic acid groups, which are acidic functional groups. By adding appropriate humidity to the block polymer membrane, good proton conductivity can be achieved by protons hopping between anions formed by ionization of protons from the phosphonic acid groups and water molecules in the ion-conducting channels made of multiple phosphonic acids.

[0121] a Block The a block is composed of a hydrophobic polymer or a water-repellent polymer.

[0122] The a-block exhibits mechanical strength at high temperatures (100° C. or higher) when formed into a composite membrane.

[0123] The polymer constituting the a block is preferably a polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher. The glass transition temperature (Tg, measured by DSC) of the polymer constituting the a block is more preferably 120° C. or higher, and even more preferably 140° C. or higher.

[0124] In this specification, unless otherwise specified, the glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0125] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0126] The polymer constituting the a block is preferably a hydrophobic polymer, and is preferably a hydrophobic hydrocarbon-based vinyl polymer having excellent chemical stability, more preferably an aromatic vinyl polymer, and even more preferably a polystyrene-based polymer.

[0127] The polystyrene-based polymer preferably includes polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, polytrimethylstyrene, and the like.

[0128] The polymer constituting the a-block may be a water-repellent polymer, which is a polymer that has the property of repelling water droplets when the water droplets are dropped onto its surface (water repellency), and has a contact angle of preferably 90° or more, more preferably 100° or more.

[0129] The water-repellent polymer preferably includes a silicone compound and a fluorinated polymer.

[0130] The silicone compound is a compound having a siloxane bond (Si—O—Si), and is preferably a polyorganosiloxane. Examples of the polyorganosiloxane include polydimethylsiloxane and polymethylphenylsiloxane. The polyorganosiloxane may have an unsaturated bond or a functional group such as an amino group.

[0131] The fluorinated polymer is preferably a copolymer of a fluorinated (meth)acrylic compound. The fluorinated (meth)acrylic compound refers to a compound in which at least a portion of the hydrogen atoms of the (meth)acrylic compound are replaced with fluorine atoms, such as a fluoroalkyl (meth)acrylate such as perfluoroalkyl (meth)acrylate, or an N-alkylperfluoroalkylsulfonamidoalkyl (meth)acrylate such as N-methylperfluorooctylsulfonamidoethyl (meth)acrylate.

[0132] b Block The b block is composed of a polymer having a phosphonic acid group in a side chain (polymer V having an acidic functional group). In other words, the polymer having a phosphonic acid group in a side chain is a polymer composed of monomer units having an acidic functional group, phosphonic acid and / or phosphonate ester, in the side chain via a spacer structure.

[0133] The b block has a phosphonic acid group and can exhibit good conductivity.

[0134] The polymer constituting the b block is preferably a hydrocarbon-based vinyl polymer, as explained in the polymer having a phosphonic acid group in the side chain (polymer V having an acidic functional group), and more preferably a polystyrene-based polymer.

[0135] The polymer having a phosphonic acid group in the side chain constituting the b block can be obtained by polymerizing a monomer having a phosphonate ester in the side chain via a spacer structure in a state in which the monomer has a protecting group, forming a block polymer, and then deprotecting the protecting group (ester moiety), thereby obtaining a polymer containing a phosphonic acid group in the monomer unit.

[0136] One embodiment of the arrangement of the block copolymer The block copolymer is a diblock copolymer having at least an ab type unit in which the a block and the b block are linked by a covalent bond.

[0137] One embodiment of the ab type diblock copolymer has the following chemical formula:

[0138]

[0139] The average degree of polymerization (e.g., n in the chemical formula) of the a block (e.g., the poly(4-tert-butylstyrene) portion in the chemical formula) is preferably an integer of 2 or greater, for example, 2 or greater, 10 or greater, 30 or greater, 50 or greater, 100 or greater, 200 or greater, 500 or greater, 800 or greater, 1,000 or greater, 1,500 or greater, or 2,000 or greater. The average degree of polymerization of the a block is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000.

[0140] The average degree of polymerization of the b block (e.g., m in the chemical formula) (e.g., a polymer portion composed of monomer units having the phosphonic acid in the chemical formula via a spacer structure) is preferably an integer of 2 or greater, for example, 2 or greater, 10 or greater, 30 or greater, 50 or greater, 100 or greater, 200 or greater, 500 or greater, 800 or greater, 1,000 or greater, 1,500 or greater, or 2,000 or greater. The average degree of polymerization of the b block is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000.

[0141] The average degree of polymerization is determined by gel permeation chromatography (GPC) using standard polystyrene and by comparing the proton intensity of initiator residues with the proton intensity of the repeating unit of the polymer. １ Determined by H-NMR.

[0142] The b block is composed of the polymer having a phosphonic acid group in the side chain (polymer V having an acidic functional group), and the polymer preferably does not contain a highly hydrolyzable functional group, such as an amide bond, an imide bond, a urethane bond, an ester bond, or an ether bond, between the main chain skeleton of the polymer and the phosphonic acid group. The spacer structure is preferably an alkyl spacer, and l in the chemical formula may be 2 to 12.

[0143] In the polymer electrolyte membrane of the present invention, preferably, in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or the graft chain containing an acidic functional group constituting a side chain in a monomer unit, the polymer of (ii), and the polymer of (iii) are hydrocarbon-based vinyl polymers and are polymers containing 0.70 or more acidic functional groups in a monomer unit.

[0144] In other words, in the polymer electrolyte membrane of the present invention, preferably, in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or the graft chain containing an acidic functional group constituting a side chain in a monomer unit is a hydrocarbon-based vinyl polymer and is a polymer containing 0.70 or more acidic functional groups in a monomer unit.

[0145] In other words, in the polymer electrolyte membrane of the present invention, the polymer (ii) is preferably a hydrocarbon vinyl polymer containing an average of 0.70 or more acidic functional groups per monomer unit.

[0146] In other words, in the polymer electrolyte membrane of the present invention, the polymer (iii) is preferably a hydrocarbon vinyl polymer containing an average of 0.70 or more acidic functional groups per monomer unit.

[0147] In the polymer electrolyte membrane of the present invention, preferably, in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or a graft chain containing an acidic functional group constituting a side chain in a monomer unit, the polymer of (ii), and the polymer of (iii) are polymers obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group and then deprotecting the protecting group, and containing 0.70 or more of the acidic functional groups in the monomer unit.

[0148] In other words, in the polymer electrolyte membrane of the present invention, preferably, in the b block of (i), the polymer having an acidic functional group in a side chain, the polymer of (iii), or the graft chain containing an acidic functional group constituting a side chain in a monomer unit is a polymer obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and is a polymer containing 0.70 or more of the acidic functional groups in the monomer unit.

[0149] In other words, in the polymer electrolyte membrane of the present invention, the polymer (ii) is preferably a polymer obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and the polymer contains 0.70 or more of the acidic functional groups in the monomer unit.

[0150] In other words, in the polymer electrolyte membrane of the present invention, the polymer (iii) is preferably a polymer obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and the polymer contains 0.70 or more of the acidic functional groups in the monomer unit.

[0151] The polymer electrolyte membrane of the present invention preferably further contains an ionic low-molecular-weight organic salt.

[0152] The "ionic low-molecular-weight organic salt" generally refers to a compound having a molecular weight of 800 or less, such as ethylmethylimidazolium bromide.

[0153] The "ionic low molecular weight organic salt" is a salt obtained by converting a basic compound into an alkyl halide (C ｎ H ２ｎ＋１ It can be synthesized by quaternizing with -X (n: natural number, X=F, Cl, Br, I) etc.

[0154] The ionic low-molecular-weight organic salt is preferably at least one selected from the group consisting of imidazolium salts, pyridinium salts, and ammonium salts, including 1-ethyl-3-methylimidazolium bromide (EMImBr), 1-ethylpyridinium bromide (EPyBr), and tetrabutylammonium bromide (TBAmBr).

[0155] The polymer electrolyte membrane of the present invention, when it comprises: (i) a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond; and / or (iii) a polymer composed of monomer units having a phosphonic acid group via a spacer structure, wherein the polymer electrolyte membrane does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group, may preferably further comprise a proton donor.

[0156] In the polymer electrolyte membrane of the present invention, the proton donating agent is at least one selected from the group consisting of sulfuric acid and phosphoric acid.

[0157] The polymer electrolyte membrane of the present invention is a polymer electrolyte membrane based on a block polymer having a high density of acidic functional groups, and containing the hydrophobic polymer a and a polymer b having an acidic functional group (preferably an acidic functional group such as a sulfonic acid group or a phosphonic acid group) on its side chain (polymer I having an acidic functional group, polymer II having an acidic functional group, and / or polymer III having an acidic functional group).

[0158] In the polymer electrolyte membrane of the present invention, polymer b is preferably a hydrocarbon-based vinyl polymer containing, on average, 0.70 or more, preferably 0.80 or more, more preferably 0.90 or more, preferably 0.95 or more, and more preferably 0.98 or more acidic functional groups per monomer unit. In a preferred embodiment, polymer b does not contain a highly hydrolyzable functional group such as an ester bond or an amide bond between the polymer main chain and the acidic functional group in the side chain. The polymer electrolyte membrane of the present invention has a high ion cluster forming ability because the equivalent mass EW (100 to 200) of polymer b roughly corresponds to the monomer molecular weight.

[0159] In conventional methods in which sulfonation is carried out after polymer synthesis, it is difficult to sulfonate only specific sites selectively and with high reaction efficiency due to the harsh reaction conditions. To avoid side reactions such as molecular chain scission, the sulfonation rate must be limited to 70-80 mol% at most.

[0160] In the polymer electrolyte membrane of the present invention, polymer b is a polymer containing, on average, 0.70 or more, preferably 0.80 or more, more preferably 0.90 or more, preferably 0.95 or more, more preferably 0.98 or more acidic functional groups per monomer unit, not by sulfonation after polymer synthesis, but by polymerizing a monomer having a protecting group on the acidic group and then deprotecting the polymer. For example, when synthesizing a block polymer containing polymer b, a block polymer is formed with a protecting group, and then deprotected to form the block polymer.

[0161] In the polymer electrolyte membrane of the present invention, polymer a is a hydrophobic hydrocarbon-based vinyl polymer.

[0162] In the polymer electrolyte membrane of the present invention, polymer a is a water-repellent hydrocarbon-based vinyl polymer or a fluorocarbon-based vinyl polymer.

[0163] The polymer a is preferably an aromatic vinyl polymer having excellent chemical stability, and more preferably has a glass transition temperature (Tg, measured by DSC) of 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and particularly preferably 140°C or higher.

[0164] In the polymer electrolyte membrane of the present invention, the block polymer is composed of a polymer obtained by linking at least polymer a and polymer b via one or more covalent bonds, and can be produced, for example, by solvent casting, press molding, or the like.

[0165] In the polymer electrolyte membrane of the present invention, microscopic phase separation occurs within the block polymer membrane between a phase that generates ion channels derived from the acidic functional groups of polymer b and a hydrophobic phase that maintains mechanical strength of polymer a. For this reason, the polymer electrolyte membrane of the present invention exhibits high proton conductivity (e.g., a conductivity of 0.01 S / cm at 80°C and 60% RH, and a conductivity of 0.05 S / cm at 80°C and 80% RH) by applying appropriate humidification to the block polymer membrane, as protons hop between anions formed by proton ionization from the acidic functional groups within the ion channels and water molecules.

[0166] The polymer electrolyte membrane of the present invention exhibits conductivity even at temperatures above 100° C. and low humidity, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0167] The polymer electrolyte membrane of the present invention, obtained by mixing a block polymer with a hydrophobic polymer a (homopolymer) having a molecular weight of 100,000 or more, has improved mechanical strength under humidified conditions, is excellent in dimensional stability when in contact with liquid water and water vapor, and exhibits high proton conductivity (e.g., a conductivity of 0.19 S / cm under conditions of 80°C and 80% RH), compared to a block polymer membrane not containing the hydrophobic polymer a (homopolymer).

[0168] The polymer electrolyte membrane of the present invention exhibits high proton conductivity (e.g., a conductivity of 0.1 S / cm at 125°C) under conditions of, for example, 100°C or higher and no humidity, by impregnating a non-volatile acid, which is a proton donor, into a block polymer membrane, or by impregnating a membrane obtained by mixing a block polymer and a hydrophobic polymer a (homopolymer) with a non-volatile acid.

[0169] The polymer electrolyte membrane of the present invention is useful as an anhydrous electrolyte membrane.

[0170] The proton conductive membrane of the present invention can be used at temperatures of 100° C. or higher and is suitable for use in fuel cells.

[0171] Temperature and Humidity in Use of Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention can be used in a medium temperature range of 100°C or higher and 150°C or lower.

[0172] The use temperature of the polymer electrolyte membrane of the present invention is the temperature at which the proton conductive membrane is used, and is preferably room temperature or higher, more preferably 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, or 90° C. or higher, and in some cases 100° C. or higher. The use temperature of the polymer electrolyte membrane of the present invention is 200° C. or lower, 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, or 110° C. or lower, in some cases.

[0173] The polymer electrolyte membrane of the present invention exhibits high proton conductivity even at temperatures of 100° C. or higher, in the absence of humidity (e.g., 125° C.). The polymer electrolyte membrane of the present invention can be used in a medium temperature range of 100° C. or higher and 150° C. or lower, in the absence of humidity, and can be used in fuel cells in the absence of humidity.

[0174] The polymer electrolyte membrane of the present invention can be used, for example, under conditions of 80°C and 60% RH, or 80°C and 80% RH, etc. The polymer electrolyte membrane of the present invention exhibits conductivity even at low humidity of 100°C or higher, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0175] The polymer electrolyte membrane of the present invention exhibits high proton conductivity by applying appropriate humidity to a block polymer membrane that does not contain a non-volatile acid as a proton donor, and by allowing protons to hop between anions formed by proton ionization from acidic functional groups and water molecules in the ion channels.

[0176] Block Copolymer The block copolymer is a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond (polymer I having an acidic functional group). The block copolymer may also contain a c block (third portion), a d block (fourth portion), etc.

[0177] a Block The a block is composed of a hydrophobic polymer or a water-repellent polymer.

[0178] The hydrophobic polymer constituting the a block is preferably a hydrophobic hydrocarbon-based vinyl polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher. The hydrophobic polymer constituting the a block more preferably has a glass transition temperature (Tg, measured by DSC) of 110° C. or higher, even more preferably 120° C. or higher, and particularly preferably 140° C. or higher.

[0179] In this specification, unless otherwise specified, the glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0180] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0181] The polymer constituting the a block is preferably a hydrophobic hydrocarbon-based vinyl polymer, more preferably a polystyrene-based polymer.

[0182] The polystyrene polymer is preferably a polymer having 50 mol % or more of a styrene moiety as a repeating unit.

[0183] The polystyrene-based polymer preferably includes polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, polytrimethylstyrene, and the like.

[0184] The polymer constituting the a block is preferably a water-repellent hydrocarbon vinyl polymer, more preferably polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, or the like.

[0185] The polymer constituting the a block is preferably a fluorocarbon vinyl polymer, more preferably polyperfluorostyrene, polyperfluoromethylstyrene, polypentafluorostyrene, or the like.

[0186] The b block is composed of a polymer having an acidic functional group in a side chain. The acidic functional group is preferably at least one selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0187] The polymer having an acidic functional group in a side chain that constitutes the b block is preferably a hydrocarbon-based vinyl polymer, and is a polymer that contains, on average, 0.70 or more, preferably 0.80 or more, more preferably 0.90 or more, preferably 0.95 or more, and more preferably 0.98 or more acidic functional groups per monomer unit.

[0188] The monomer unit forming the polymer having an acidic functional group is preferably a monomer unit having an acidic functional group composed of at least one selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid.

[0189] The polymer having an acidic functional group in the side chain that constitutes the b block is more preferably a polymer containing approximately 100 mol % of the acidic functional group in the monomer unit.

[0190] The polymer constituting the b block is preferably a hydrocarbon-based vinyl polymer.

[0191] The hydrocarbon vinyl polymer may contain 50 mol% or less of polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, polytrimethylstyrene, or the like.

[0192] The acidic functional group present in the side chain of the polymer constituting the b block is preferably an acidic functional group composed of at least one type selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0193] The polymer having an acidic functional group in a side chain constituting the b block is preferably obtained by polymerizing a monomer having a protecting group on the acidic functional group and then deprotecting the protecting group, and is a polymer containing approximately one acidic functional group per monomer unit.

[0194] In the polymer electrolyte membrane of the present invention, microscopic phase separation occurs within the block polymer membrane between a hydrophobic phase composed of polymer a that maintains mechanical strength and a phase composed of polymer b that generates ion channels derived from the acidic functional groups. By applying appropriate humidification to the block polymer membrane, the polymer electrolyte membrane of the present invention exhibits high proton conductivity due to proton hopping between anions formed by proton ionization from the acidic functional groups and water molecules within the ion channels.

[0195] Arrangement of Block Copolymer The block copolymer is a diblock copolymer (polymer I having an acidic functional group, polymer II having an acidic functional group, or / and polymer III having an acidic functional group) having a-b type units in which at least an a block and a b block are connected by a covalent bond.

[0196] An example of the ab type diblock copolymer is represented by the following chemical formula (a sulfonic acid group-containing block polymer and a phosphonic acid group-containing block polymer).

[0197]

[0198]

[0199] The average degree of polymerization (e.g., n in the chemical formula) of the a blocks (e.g., the poly(4-tert-butylstyrene) portion in the chemical formula) constituting the diblock copolymer having a-b type units is preferably an integer of 2 or greater, for example, 2 or greater, 10 or greater, 30 or greater, 50 or greater, 100 or greater, 200 or greater, 500 or greater, 800 or greater, 1,000 or greater, 1,500 or greater, or 2,000 or greater. The average degree of polymerization of the a blocks constituting the diblock copolymer having a-b type units is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000.

[0200] The average degree of polymerization (e.g., m in the chemical formula) of the b blocks constituting the diblock copolymer having a-b type units (e.g., the poly(4-styrenesulfonic acid) portion and the poly(4-styrenephosphonic acid) portion in the chemical formula) is preferably an integer of 2 or greater, for example, 2 or greater, 10 or greater, 30 or greater, 50 or greater, 100 or greater, 200 or greater, 500 or greater, 800 or greater, 1,000 or greater, 1,500 or greater, or 2,000 or greater. The average degree of polymerization of the b blocks constituting the diblock copolymer having a-b type units is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000.

[0201] The average degree of polymerization can be determined by 1H-NMR.

[0202] Hydrophobic polymer or water-repellent polymer having a molecular weight of 100,000 or more The polymer electrolyte membrane of the present invention contains a polymer, and the polymer has a block copolymer having at least a-b type units in which an a block and a b block are linked by a covalent bond, and may additionally contain a hydrophobic polymer or water-repellent polymer having a molecular weight of 100,000 or more.

[0203] The hydrophobic polymer or water-repellent polymer is preferably a homopolymer made of the monomers that constitute the a-block.

[0204] The molecular weight of the hydrophobic polymer or water-repellent polymer is preferably 200,000 or more, 400,000 or more, 600,000 or more, or 800,000 or more. The molecular weight of the hydrophobic polymer is determined by determining the molecular weight distribution (Mw / Mn) by gel permeation chromatography (GPC) using standard polystyrene for molecular weight calibration.

[0205] The polymer electrolyte membrane of the present invention, obtained by mixing a block copolymer (block polymer) with a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer), has improved mechanical strength under humidified conditions, is excellent in dimensional stability when in contact with liquid water and water vapor, and exhibits high proton conductivity, compared to a membrane made of a block copolymer (block polymer) that does not contain a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer).

[0206] Proton-Donating Agent (Non-Volatile Acid) The polymer electrolyte membrane of the present invention may preferably further contain a proton-donating agent (plasticizer).

[0207] The proton donor (plasticizer) contained in the polymer electrolyte membrane of the present invention is preferably a proton donor composed of at least one selected from the group consisting of sulfuric acid and phosphoric acid.

[0208] The polymer electrolyte membrane of the present invention exhibits high proton conductivity under non-humidified conditions by impregnating a block copolymer (block polymer) membrane with a proton donating agent (non-volatile acid) or by impregnating a membrane obtained by mixing a block copolymer (block polymer) with a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer) with a proton donating agent (non-volatile acid).

[0209] Method for Producing Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention is produced by a method comprising: (A) a step of preparing a hydrophobic polymer and producing an a block; (B) a step of polymerizing a monomer having an acidic functional group protected by a protecting group, or a monomer having a phosphonic acid group protected by a protecting group via a spacer structure, to the a block to form a b block, thereby producing a block copolymer having a-b type units in which the a block and the b block formed by polymerization of units of the monomer are covalently linked together; and (C) a step of deprotecting the protecting group in the b block to produce a polymer having 0.70 or more of the acidic functional group or the phosphonic acid group in a side chain, by deprotecting the protecting group in the b block.

[0210] The polymer electrolyte membrane of the present invention preferably further comprises the step of (D) mixing a hydrophobic polymer (hydrophobic polymer a (homopolymer)) having a molecular weight of 100,000 or more, or a water-repellent polymer (water-repellent polymer a (homopolymer)).

[0211] The polymer electrolyte membrane of the present invention preferably further comprises the step of: (E) mixing a proton-donating agent.

[0212] In conventional methods in which sulfonation is carried out after polymer synthesis, it is difficult to sulfonate only specific sites selectively and with high reaction efficiency due to the harsh reaction conditions. To avoid side reactions such as molecular chain scission, the sulfonation rate must be limited to 70-80 mol% at most.

[0213] In the polymer electrolyte membrane of the present invention, polymer b is preferably a polymer containing an average of 0.70 or more, preferably 0.80 or more, more preferably 0.90 or more acidic functional groups per monomer unit, not by sulfonation after polymer synthesis, but by polymerizing a monomer having a protecting group on the acidic group and then deprotecting the polymer. For example, when synthesizing a block polymer containing polymer b, a block polymer is formed with the protecting group attached, and then deprotected to form a block polymer (polymer I having an acidic functional group, polymer II having an acidic functional group, and / or polymer III having an acidic functional group).

[0214] Polymer b (a polymer having an acidic functional group in a side chain constituting the b block) is a polymer containing, on average, 0.70 or more, preferably 0.80 or more, more preferably 0.95 or more, and particularly preferably 0.98 or more acidic functional groups per monomer unit.

[0215] The polymer electrolyte membrane of the present invention, obtained by mixing a block copolymer (block polymer) with a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer), has improved mechanical strength under humidified conditions, is excellent in dimensional stability when in contact with liquid water and water vapor, and exhibits high proton conductivity, compared to a membrane made of a block copolymer (block polymer) that does not contain a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer).

[0216] The polymer electrolyte membrane of the present invention exhibits high proton conductivity under non-humidified conditions by impregnating a block copolymer (block polymer) membrane with a proton donating agent (non-volatile acid) or by impregnating a membrane obtained by mixing a block copolymer (block polymer) with a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer) with a proton donating agent (non-volatile acid).

[0217] Synthesis of Block Copolymer (Polymer I Having Acidic Functional Group, Polymer II Having Acidic Functional Group, and / or Polymer III Having Acidic Functional Group) The method for synthesizing the block copolymer having an a block and a b block is not particularly limited as long as it is addition polymerization such as anionic polymerization, cationic polymerization, or radical polymerization.

[0218] The block copolymer having the a block and the b block can be synthesized by the following method.

[0219] (A) Step of preparing a hydrophobic polymer and producing an a-block A monomer constituting the a-block (e.g., 4-tert-butylstyrene monomer), a RAFT agent (reversible addition-fragmentation chain transfer agent), and a polymerization initiator are mixed and polymerized, and then the polymer is isolated and purified to synthesize a macro RAFT agent containing an a-block.

[0220] The solvent used for synthesis and isolation is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and ether solvents such as dimethyl ether, diethyl ether and tetrahydrofuran. The solvent is not limited to these.

[0221] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0222] (B) A step of polymerizing the a block with a monomer having an acidic functional group protected by a protecting group, or a monomer having a phosphonic acid group protected by a protecting group via a spacer structure, to form a b block, and producing a block copolymer having a-b type units in which the a block and the b block formed by polymerization of units of the monomers are linked by a covalent bond (polymer I having an acidic functional group, polymer II having an acidic functional group, and / or polymer III having an acidic functional group). Next, in the presence of a polymerization initiator, a macro RAFT agent including the a block and a monomer having a protecting group (e.g., n-butyl group) on the acidic functional group (e.g., sulfonic acid group or phosphonic acid group) that forms the b block (e.g., n-butyl 4-styrenesulfonate monomer and diethyl 4-styrenephosphonate monomer) are polymerized to produce a block copolymer having a-b type units in which the a block and the b block are linked by a covalent bond.

[0223] The solvent used in the synthesis and isolation is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and ether solvents such as dimethyl ether, diethyl ether and tetrahydrofuran. The solvent is not limited to these.

[0224] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0225] (C) a step of deprotecting the protecting group in the b block to produce a graft chain having the acidic functional group or the phosphonic acid group in a side chain of a monomer unit constituting the b block, wherein the monomer unit contains 0.70 or more of the acidic functional group or the phosphonic acid group. By deprotecting the protecting group in the b block with a basic solution (e.g., aqueous sodium hydroxide solution), a polymer is produced which contains, on average, 0.95 or more of the acidic functional groups in the monomer unit constituting the b block and has the acidic functional group in a side chain.

[0226] The polymer having an acidic functional group in the side chain that constitutes the b block is more preferably a polymer containing approximately 100 mol % of the acidic functional group in the monomer unit.

[0227] (D) Step of Mixing a Hydrophobic Polymer or Water-Repellent Polymer Having a Molecular Weight of 100,000 or More In the polymer electrolyte membrane of the present invention, a hydrophobic polymer or a water-repellent polymer is preferably mixed in addition to the polymer having a block copolymer having a-b type units in which at least the a block and the b block are linked by a covalent bond.

[0228] The hydrophobic polymer or water-repellent polymer is preferably a homopolymer made of the monomers that constitute the a-block.

[0229] The polymer electrolyte membrane of the present invention, obtained by mixing a block copolymer (block polymer) with a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer), has improved mechanical strength under humidified conditions, is excellent in dimensional stability when in contact with liquid water and water vapor, and exhibits high proton conductivity, compared to a membrane made of a block copolymer (block polymer) that does not contain a hydrophobic polymer a (homopolymer) or a water-repellent polymer a (homopolymer).

[0230] Ratio of Use of Polymer Having a Block Copolymer Having a-b Type Units (Polymer I Having an Acidic Functional Group, Polymer II Having an Acidic Functional Group, and / or Polymer III Having an Acidic Functional Group) to Hydrophobic Polymer or Water-Repellent Polymer From the viewpoints of improving mechanical strength under humidified conditions, excellent dimensional stability when in contact with liquid water and water vapor, and exhibiting high proton conductivity, the ratio of use of the block copolymer having a-b type units to the hydrophobic polymer or water-repellent polymer is preferably 6-9:4-1, and more preferably 7-8:3-2, by weight.

[0231] (E) Step of Mixing Proton-Donating Agent In the polymer electrolyte membrane of the present invention, a proton-donating agent (in a volatile solvent (methanol)) is preferably further mixed.

[0232] The proton donor (which can act as a plasticizer) contained in the polymer electrolyte membrane of the present invention is preferably at least one selected from the group consisting of sulfuric acid and phosphoric acid.

[0233] The proton donating agent (a non-volatile acid such as sulfuric acid or phosphoric acid) preferably contains a proton donating compound involved in proton transport, and dissolves well in and penetrates sufficiently into the b block made of a polymer having an acidic functional group (such as a sulfonic acid group or a phosphonic acid group) in its side chain.

[0234] The polymer electrolyte membrane of the present invention exhibits high proton conductivity under non-humidified conditions by impregnating a block copolymer (block polymer) membrane with a proton donor (non-volatile acid) or by impregnating a membrane obtained by mixing a block copolymer (block polymer) and a hydrophobic polymer a (homopolymer) with a proton donor (non-volatile acid).

[0235] Usage Ratio of Block Copolymer Having a-b Type Units (Polymer I Having an Acidic Functional Group, Polymer II Having an Acidic Functional Group, and / or Polymer III Having an Acidic Functional Group) and Proton Donor: From the viewpoint of exhibiting high proton conductivity under non-humidified conditions, the usage ratio of the block copolymer having a-b type units and the proton donor is preferably (block copolymer having a-b type units):(proton donor) by weight ratio of 3 to 7:7 to 3, more preferably 5 to 7:5 to 3.

[0236] The ratio of the block copolymer having a-b type units to the proton donating agent used, in terms of the molar ratio (number of moles of sulfonic groups in the block copolymer having a-b type units):(total number of moles of protons available for donating by the proton donating agent), is preferably 1-4:9-6, more preferably 2-3:8-7, from the viewpoint of exhibiting high proton conductivity under non-humidified conditions.

[0237] Proportion of the Block Copolymer Having a-b Type Units (Polymer I Having an Acidic Functional Group, Polymer II Having an Acidic Functional Group, and / or Polymer III Having an Acidic Functional Group), Hydrophobic Polymer or Water-Repellent Polymer, and Proton-Donating Agent The proportion of the block copolymer having a-b type units, hydrophobic polymer or water-repellent polymer, and proton-donating agent used is preferably 20-50:5-20:40-70 by weight, in terms of improving mechanical strength under humidified conditions, providing excellent dimensional stability when in contact with liquid water and water vapor, and exhibiting high proton conductivity, as well as exhibiting high proton conductivity under unhumidified conditions.

[0238] RAFT Agents (Reversible Addition-Fragmentation Chain Transfer Agents) RAFT agents are preferably thiocarbonylthio compounds such as dithioesters, dithiocarbamates, trithiocarbonates, and xanthates.

[0239] The RAFT agent is preferably 4-[(2-carboxyethylsulfanylthiocarbonyl)sulfanyl]-4-cyanopentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methyl ... Methyl 2-(dodecylthiocarbonothioylthio)propionic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid pentafluorophenyl ester, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid 3-azido-1-propanol ester, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, methyl 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoate, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoate N-Hydroxysuccinimidyl ethylpropionate, 3-[[(benzylthio)carbonothioyl]thio]propionic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, cyanomethyl[3-(trimethoxysilyl)propyl]trithiocarbonate, 3-butenyl-2-(dodecylthiocarbonothioylthio)-2-methylpropane, phthalimidomethylbutyltrithiocarbonate, 2-(2-carboxyethylsulfanylthiocarbonylsulfanyl) ) propionic acid, 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanol, and RAFT agents such as cyanomethyl dodecyl trithiocarbonate 1,4-phenylenebis(methylene)didodecylbis(carbonotrithioate), 1,4-phenylenebis(methylene)dibutylbis(carbonotrithioate), and 1,4-phenylenebis(methylene)dioctadecylbis(carbonotrithioate).

[0240] By appropriately selecting the RAFT agent, it is possible to synthesize the desired block copolymer sequence.

[0241] Polymerization Initiator The polymerization initiator is preferably an azo-based radical polymerization initiator, a peroxide-based radical polymerization initiator, or the like.

[0242] The polymerization initiator is preferably an azo-based radical polymerization initiator such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or dimethyl 2,2'-azobisisobutyrate.

[0243] The polymerization initiator is preferably a peroxide radical polymerization initiator such as benzoyl peroxide, t-butyl hydroperoxide, or cumene hydroperoxide.

[0244] Formation of Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention is preferably formed into a membrane by a casting method, a pressing method, etc., before removing the solvent, or preferably by a hot melt method, etc.

[0245] Thickness of Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention has excellent processability and can be formed by a hot melt method, a solvent casting method, or the like, and therefore can be made thinner than conventional proton conductive membranes.

[0246] The membrane thickness of the polymer electrolyte membrane of the present invention is preferably 1.00 mm or less, 0.90 mm or less, 0.80 mm or less, 0.75 mm or less, 0.73 mm or less, 0.72 mm or less, 0.71 mm or less, 0.70 mm or less, 0.68 mm or less, 0.65 mm or less, 0.60 mm or less, 0.55 mm or less, 0.50 mm or less, 0.45 mm or less, 0.40 mm or less, 0.35 mm or less, 0.30 mm or less, 0.28 mm or less, 0.25 mm or less, 0.23 mm or less, or 0.20 mm or less.

[0247] Proton Conductivity of Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention exhibits high proton conductivity in a non-humidified environment, a low-humidity environment, or a humidified environment.

[0248] The proton conductivity of the polymer electrolyte membrane of the present invention is preferably 0.003 S / cm or more, 0.0032 S / cm or more, 0.005 S / cm or more, 0.010 S / cm or more, 0.014 S / cm or more, 0.015 S / cm or more, 0.030 S / cm or more, 0.040 S / cm or more, 0.050 S / cm or more, 0.075 S / cm or more, 0.080 S / cm or more, 0.090 S / cm or more, or 0.095 S / cm or more under a low-humidity environment or a humidified environment (for example, a temperature condition of about 80°C to 95°C and a humidity condition of about 20% RH to 80% RH).

[0249] The proton conductivity of the polymer electrolyte membrane of the present invention, in a non-humid environment (for example, a temperature condition of about 125°C), is preferably 0.010 S / cm or more, 0.020 S / cm or more, 0.030 S / cm or more, 0.050 S / cm or more, 0.075 S / cm or more, 0.100 S / cm or more, 0.125 S / cm or more, 0.150 S / cm or more, 0.175 S / cm or more, or 0.200 S / cm or more.

[0250] Fuel Cell The fuel cell of the present invention has the polymer electrolyte membrane of the present invention.

[0251] The fuel cell of the present invention preferably comprises a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side catalyst layer, the proton conductive membrane of the present invention, an air electrode-side catalyst layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0252] The fuel cell of the present invention preferably has a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side gas diffusion layer, a fuel electrode-side catalyst layer, the proton conductive membrane of the present invention, an air electrode-side catalyst layer, an air electrode-side gas diffusion layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0253] Section C Monomer The monomer of the present invention has a phosphonic acid group and / or a phosphonate ester via a spacer structure.

[0254] The monomer of the present invention is a monomer that does not contain a highly hydrolyzable functional group between the part that will become the main chain skeleton of the polymer after polymerization and the phosphonic acid group and / or phosphonic acid ester that will be part of the side chain of the polymer after polymerization.

[0255] The "portion that will become the main chain skeleton of the polymer after polymerization" refers to the portion that will become the main chain (corresponding to the center of the chain, trunk) of a chain compound (generally a polymer). In the case of a vinyl monomer, it is generally a vinyl group CH ２ =CH-. A functional group branching off from the main chain skeleton, a unit containing a functional group, or a graft chain (branch, branch polymer) is referred to as a "side chain."

[0256] In this specification, the term "phosphonate ester" refers to a phosphonate diester or phosphonate monoester in which a protecting group is attached to a phosphonic acid, and particularly refers to a phosphonate diester.

[0257] The spacer structure is preferably an alkyl spacer.

[0258] The spacer structure is preferably an alkyl spacer having 2 to 12 repeating methylene groups.

[0259] The monomer has an acidic functional group, phosphonic acid and / or phosphonate ester, on the side chain via a spacer structure.

[0260] Phosphonic acids can be easily prepared by deprotecting phosphonate esters.

[0261] The monomer of the present invention has a phosphonic acid group and / or a phosphonate ester via a spacer structure.

[0262] The monomer of the present invention is a monomer that does not contain a highly hydrolyzable functional group between the part that will become the main chain skeleton of the polymer after polymerization and the phosphonic acid group and / or phosphonic acid ester that will be part of the side chain of the polymer after polymerization.

[0263] The spacer structure is preferably an alkyl spacer.

[0264] The spacer structure is preferably a linear, branched, or cyclic alkyl spacer. Examples of the alkyl spacer include linear or branched alkyl spacers having 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1-ethylpropyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 5-propylnonyl, n-tridecyl, n-tetradecyl, n-pentadecyl, hexadecyl, heptadecyl, and octadecyl; and cyclic alkyl spacers having 3 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0265] The spacer structure is preferably methylene (methylene: —CH ２ The number of repeating groups is 2 to 12 (-(CH ２ ) n -units, n=2-12).

[0266] The spacer structure is more preferably an alkyl spacer such as ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1-ethylpropyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, or 5-propylnonyl.

[0267] The spacer structure is preferably bonded to the styrene-based monomer constituting the monomer at any of the O-, m- and p-positions, for example, with a bonding number of 1 to 5.

[0268] For example, the following chemical structural formula is a case where the number of bonds is 2, and the styrene-based monomer constituting the monomer has two phosphonate esters via a spacer structure.

[0269]

[0270] In addition, first, carbon tetrabromide (CBr) may be optionally added to the styrene-based monomer constituting the monomer at the O-, m-, or p-position. ４ ), bromoform (CHBr ３ ) or the like to synthesize, for example, 3,5-bis(tribromomethyl)styrene, 3,5-bis(dibromomethyl)styrene, etc., and then introduce an alkyl spacer into the tribromomethyl group or dibromomethyl group. Furthermore, by introducing phosphonic acid, it is possible to synthesize a monomer in which multiple phosphonic acid groups with alkyl spacers are introduced into a styrene-based monomer. The number of phosphonic acid groups with alkyl spacers introduced is one or more, and may be two, three, four, five, six, eight, ten or more.

[0271] For example, the chemical structural formulas below are those in which the number of alkyl spacer-attached phosphonic acid groups is 2, 3, or 4, and the styrene-based monomer constituting the monomer has multiple phosphonic acid esters via spacer structures.

[0272]

[0273] Item B Composite polymer membrane The composite polymer membrane of the present invention comprises: (1) a polymer having an acidic functional group; and (2) a polymer having a basic functional group, wherein the (1) polymer having an acidic functional group is: (i) a block copolymer having an a-b type unit in which at least an a block and a b block are connected by a covalent bond; (ii) a chemically crosslinked polymer having an acidic functional group in a side chain; and / or (iii) a polymer consisting of monomer units having a phosphonic acid group via a spacer structure, wherein the polymer does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group; wherein the (i) a block is composed of a hydrophobic polymer or a water-repellent polymer; and the (i) b block is composed of a polymer having an acidic functional group in a side chain or the (iii) polymer; or the (i) b block side chain is composed of a graft chain containing an acidic functional group in a monomer unit. －３ It exhibits a conductivity of 100 S / cm or more.

[0274] The polymer electrolyte membrane of the present invention contains a polymer having an acidic functional group, and the polymer is (i) a block copolymer having at least an a-b type unit in which an a block and a b block are linked by a covalent bond (Polymers I to III Having an Acidic Functional Group).

[0275] The polymer electrolyte membrane of the present invention contains a polymer having an acidic functional group, and the polymer is (ii) a chemically crosslinkable polymer having an acidic functional group on the side chain (polymer IV having an acidic functional group).

[0276] The polymer electrolyte membrane of the present invention includes a polymer having an acidic functional group, and the polymer is (iii) a polymer composed of monomer units having a phosphonic acid group via a spacer structure, and is a polymer (polymer V having an acidic functional group) that does not contain a highly hydrolyzable functional group between its main chain skeleton and the phosphonic acid group.

[0277] In the polymer electrolyte membrane of the present invention, the a block (i) is composed of a hydrophobic polymer or a water-repellent polymer.

[0278] In the polymer electrolyte membrane of the present invention, the b block of (i) is composed of a polymer having an acidic functional group in a side chain (polymer I having an acidic functional group) or the polymer of (iii) (polymer II having an acidic functional group).

[0279] In the polymer electrolyte membrane of the present invention, the side chains of the b block of (i) are composed of graft chains having acidic functional groups (polymer III having acidic functional groups).

[0280] The composite polymer membrane of the present invention has a viscosity of 1.0×10 －３ It exhibits a conductivity of 100 S / cm or more.

[0281] The mixture of (1) a polymer with acidic functional groups and (2) a polymer with basic functional groups that forms a composite polymer membrane is called a composite polymer.

[0282] Polymer with Basic Functional Groups The composite polymer membrane comprises a polymer with basic functional groups in addition to a polymer with acidic functional groups.

[0283] The composite polymer membrane contains a polymer having a basic functional group in addition to a polymer having an acidic functional group, thereby forming multiple acid-base complexes between the phosphonic acid group and the basic functional group. Since the membrane basically does not contain low molecular weight electrolytes, the elution of the polymer electrolyte (polymer having an acidic functional group), the polymer having a basic functional group, and the low molecular weight electrolyte from the membrane into water is suppressed, and proton ionization from the acidic functional group is also promoted. －３ It exhibits good conductivity of 100 S / cm or more.

[0284] The polymer having a basic functional group has a glass transition temperature of preferably 300°C or lower, 200°C or lower, or 100°C or lower, more preferably 80°C or lower, even more preferably 60°C or lower, and particularly preferably 50°C or lower.

[0285] In this specification, unless otherwise specified, the glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0286] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0287] The polymer having a basic functional group is preferably a polymer having a basic functional group composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0288] The polymer having a basic functional group is preferably a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, the c block being composed of a hydrophobic polymer or a water-repellent polymer, and the d block being composed of a polymer having at least one basic functional group selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0289] The polymer having a basic functional group is preferably a polymer having 5 or more basic functional groups, more preferably 10 or more, and even more preferably 15 or more.

[0290] The polymer having a basic functional group is more preferably a polymer having a glass transition temperature of 100°C or lower and having five or more basic functional groups composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0291] The polymer having a basic functional group is more preferably a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of a polymer having five or more basic functional groups each composed of at least one type selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0292] The polymer having a basic functional group is more preferably a polymer having a glass transition temperature of 100°C or lower and containing five or more monomer units having a basic functional group, the monomer units being composed of at least one selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, and vinylpyrrole.

[0293] More preferably, the polymer having a basic functional group is a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of a polymer containing five or more monomer units composed of at least one type selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, vinylpyrrole, and vinyltriazole.

[0294] More preferably, the polymer having a basic functional group is a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of at least one polymer selected from the group consisting of polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, poly(2-vinylpyridine), polyvinylimidazole, polyvinylpyrazole, polyvinylpyrrole, and polyvinyltriazole.

[0295] More preferred examples of the polymer having a basic functional group include polyethyleneimine (EI), polyallylamine (aAm, Tg (DSC): for example, about 30°C), polyvinylamine, polyvinylpyridine (VP), poly(2-vinylpyridine) (2VP, Tg (DSC): for example, about 100°C), polybenzimidazole, polybenzoxazole, polybenzthioazole, polyindole, polyquinoline, polyvinylimidazole, dialkylamine-ammonia-epichlorohydrin polycondensates such as dimethylamine-ammonia-epichlorohydrin polycondensates, and dialkylamine-epichlorohydrin polycondensates such as dimethylamine-epichlorohydrin polycondensates.

[0296] The polymer constituting the c block is preferably a hydrophobic polymer or a water-repellent polymer, and the hydrophobic polymer or water-repellent polymer constituting the a block described in the above [3] Block copolymer can be used.

[0297] The molecular weight of the polymer having a basic functional group is preferably 200 or more, 500 or more, or 1,000 or more, and more preferably 2,000 or more, 5,000 or more, 10,000 or more, 20,000 or more, 40,000 or more, or 80,000 or more.

[0298] The molecular weight of a polymer having basic functional groups can be determined by gel permeation chromatography (GPC) to determine the number average molecular weight (Mn) using standard polystyrene for molecular weight calibration.

[0299] In the composite polymer membrane of the present invention, (2) the polymer having a basic functional group may be a polymer having a cationic functional group based on the basic functional group, and a part of the basic functional group is quaternized with an organic halogen compound to generate a cation, thereby forming a cationic functional group based on the basic functional group.

[0300] In the composite polymer membrane of the present invention, the proportion of cationic functional groups based on basic functional groups among the basic functional groups may be 10 mol % or more.

[0301] In the composite polymer membrane of the present invention, the organic halogen compound is a compound having an alkyl halide moiety.

[0302] The "compound having an alkyl halide moiety" is a compound having an alkyl halide moiety, ｎ H ２ｎ＋１ -X (n: natural number, X=F, Cl, Br, I), and R-C ｎ H ２ｎ The compound is a compound represented by —X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and is particularly preferably an alkyl halide.

[0303] The composite polymer membrane of the present invention comprises: a polymer having an anionic group based on an acidic functional group, which is obtained by combining the polymer having the (1) acidic functional group with a polymer having a cationic functional group based on the basic functional group, so that a proton is ionized from the acidic functional group of the polymer having the (1) acidic functional group to form an anionic functional group, and a low-molecular-weight acid consisting of a counter anion of the cationic functional group of the polymer having the cationic functional group originating from the basic functional group and a proton escapes from the membrane; and a polymer having a cationic group based on the basic functional group, －３ It exhibits a conductivity of 100 S / cm or more.

[0304] One embodiment of the composite polymer membrane The composite polymer membrane includes (1) a polymer having acidic functional groups and (2) a polymer having basic functional groups.

[0305] One embodiment of the composite polymer membrane has the following chemical formula:

[0306]

[0307] When the composite polymer film contains a block copolymer, the equivalent mass EW (100 to 400) of the polymer constituting the b block roughly corresponds to the molecular weight of the monomer, and therefore the composite polymer film has a high ability to form ion clusters.

[0308] The composite polymer membrane does not show a significant change in conductivity before and after immersion in water. The composite polymer membrane is a composite membrane that does not show a decrease in conductivity of 25% or more before and after immersion in water. The composite polymer membrane is a composite membrane that does not show a difference in conductivity of 25% or more compared to a membrane that is not immersed in water, even when immersed in water at 20°C to 70°C, for example, 60°C, for 1 hour. The degree of change in conductivity before and after immersion in water, including error, is preferably 25% or less, more preferably 15% or less, and even more preferably 5% or less.

[0309] The composite polymer membrane exhibits no elution of polymer or low molecular weight electrolyte after immersion in water (for example, at 20°C and 70°C), and exhibits a solubility of 1.0 x 10 under appropriate conditions of 60°C to 150°C and 0% RH to 100% RH. －３ Achieve a conductivity of 0.5 S / cm or higher.

[0310] The composite polymer membrane generates substantially no eluate from the membrane after immersion for 1 hour in water at 20° C. to 70° C., for example, water at 60° C. The amount of eluate eluted from the membrane into water is preferably 25% by mass or less, more preferably 15% by mass or less, and even more preferably 5% by mass or less.

[0311] In composite polymer membranes, block copolymers (block polymers) are composed of polymers obtained by linking at least polymer a and polymer b by one or more covalent bonds, and can be produced, for example, by solvent casting or press molding.

[0312] In the composite polymer membrane, microscopic phase separation occurs within the block polymer membrane between a phase of polymer b that generates ion channels derived from the phosphonic acid groups and a hydrophobic phase of polymer a that maintains mechanical strength. For this reason, the composite polymer membrane exhibits good proton conductivity by adding appropriate humidity to the block polymer membrane, as protons hop over anions and water molecules formed by proton ionization from the phosphonic acid groups in the ion conduction channels. For example, under appropriate conditions of 60°C to 150°C and 0% RH to 100% RH, the composite polymer membrane exhibits good proton conductivity of 1.0 x 10 －３ It exhibits a conductivity of 100 S / cm or more.

[0313] The composite polymer membrane exhibits conductivity even under humidified conditions of 100° C. or higher or under low humidified conditions, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0314] In the composite polymer membrane, a non-volatile acid (e.g., phosphoric acid), which is a proton donor for the low molecular weight electrolyte, may be impregnated into a membrane of a block polymer or a membrane obtained by mixing a block polymer with a hydrophobic polymer a (homopolymer). By doing so, good proton conductivity (e.g., 1.0 × 10) can be obtained, for example, under conditions of 100°C or higher and no humidity. －３ The conductivity is 1000 S / cm or more.

[0315] The proton conductivity is 1.0×10 －３ S / cm or more, 2.0×10 －３ S / cm or more, 3.0×10 －３ S / cm or more, 5.0×10 －３ S / cm or more, 7.0×10 －３ S / cm or more, 1.0×10 －２ S / cm or more, 2.0×10 －２ S / cm or more, 3.0×10 －２ S / cm or more, 5.0×10 －２ S / cm or more, 7.0×10 －２ S / cm or more, 1.0×10 －１ It may be S / cm or more.

[0316] Composite polymer membranes are useful as electrolyte membranes.

[0317] The composite polymer membrane can be used at temperatures above 100° C. and is suitable for use in fuel cells.

[0318] Temperature and Humidity for Use of Composite Polymer Membrane The composite polymer membrane of the present invention can be used in a medium temperature range of 100°C or higher and 200°C or lower.

[0319] The use temperature of the composite polymer membrane is the temperature at which the proton conductive membrane is used, and is preferably room temperature or higher, more preferably 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, or 90° C. or higher, and in some cases 100° C. or higher. The use temperature of the composite polymer membrane is 200° C. or lower, 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, or 110° C. or lower, in some cases.

[0320] The composite polymer membrane exhibits high proton conductivity even at temperatures above 100° C. and under non-humidified conditions (e.g., 125° C.). The composite polymer membrane can be used in a medium temperature range, particularly at temperatures above 100° C. and below 150° C., and in a non-humidified environment, and can be used in fuel cells under non-humidified conditions.

[0321] The composite polymer membrane can be used, for example, under conditions of 80°C and 60% RH, or 80°C and 80% RH. The composite polymer membrane exhibits conductivity even under humidified conditions at 100°C or higher, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0322] By adding appropriate humidity to a block polymer membrane that does not contain non-volatile acids, which are proton donors, the composite polymer membrane exhibits good proton conductivity by allowing protons to hop between anions or water molecules formed by proton ionization from phosphonic acid groups within the ion channel.

[0323] The polymer having an acidic functional group is a vinyl monomer (CH ２ The polymer may or may not be a vinyl polymer based on =CH-R (where R is a substituent).

[0324] The polymers having acidic functional groups that make up the composite polymer membrane may be homopolymers or random copolymers having acidic functional groups. Their generalized chemical structural formulas (chemical structural formulas containing A-H (Acid)) are shown below.

[0325] (A-H: acidic functional group, n≧1, 0<x≦1)

[0326] The polymers having acidic functional groups that make up the composite polymer membrane may be block copolymers (block polymers) having acidic functional groups. Their generalized chemical structural formulas (chemical structural formulas containing A-H (Acid)) are shown below.

[0327] (A-H: acidic functional group, l≧1, n≧1, 0<x≦1)

[0328] In the generalized chemical structure of the homopolymers, lathand copolymers, and block polymers having acidic functional groups, AH (Acid) represents the acidic functional group, for example, sulfonic acid or phosphonic acid.

[0329] In the generalized chemical structure of the acidic functional group-containing homopolymers, lathand copolymers, and block polymers, n represents the overall degree of polymerization of the acidic functional group-containing polymer.

[0330] In the generalized chemical structure of homopolymers, lathand copolymers, and block polymers having acidic functional groups, x represents the percentage of monomer units having acidic functional groups.

[0331] In the generalized chemical structural formulas of homopolymers, lathand copolymers, and block polymers having acidic functional groups, (1-x) represents the proportion (percentage) of monomer units that do not have acidic functional groups.

[0332] In the generalized chemical structure of the homopolymer, latham copolymer, and block polymer having an acidic functional group, preferably R ２ The smaller the ratio (1-x) (percentage) of R １ The ratio x (percentage) of R should be 100%. ２ When the ratio (1-x) (percentage) is 0%, R１ It becomes a homopolymer of

[0333] In the generalized chemical structure of homopolymers, latham copolymers, and block polymers having acidic functional groups, R １ represents the main skeleton of a monomer unit having an acidic functional group. １ When (A-H(Acid))- represents a vinylphosphonic acid unit, R １ Ha-CH ２ -CH-. １ When (A-H(Acid))- represents a styrenephosphonic acid unit, R １ Ha-CH ２ -CH(C ６ H ４ )-.

[0334] In the generalized chemical structure of homopolymers, latham copolymers, and block polymers having acidic functional groups, R ２ represents a monomer unit that does not have an acidic functional group. ２ a monomer unit that does not have an acidic functional group (e.g., styrene-CH ２ -CH(C ６ H ５ )-, acrylate-CH ２ -CH(COOR)-) may contain one type alone or two or more types in combination.

[0335] In the generalized chemical structure of the acidic functional group-containing homopolymers, lathand copolymers, and block polymers, the acidic functional group-containing monomer units may have one or more acidic functional groups.

[0336] In the generalized chemical structure of homopolymers, latham copolymers, and block polymers having acidic functional groups, R ０ represents a monomer unit of a hydrophobic polymer or a water-repellent polymer, and may contain two or more types of monomer units.

[0337] In the generalized chemical structure of the homopolymer, latham copolymer, and block polymer having an acidic functional group, l represents the degree of polymerization of the monomer unit of the hydrophobic or water-repellent polymer.

[0338] In the generalized chemical structural formulas of homopolymers, random copolymers, and block polymers having acidic functional groups, when a slash ( / ) is written above a hyphen (-), it means that the monomer units on either side of the slash ( / ) are linked randomly, and when only a hyphen (-) is written, it means that the polymers on either side of the hyphen (-) are linked in a block manner.

[0339] The polymers having basic functional groups that make up the composite polymer membrane may be homopolymers or random copolymers having basic functional groups. Their generalized chemical structural formulas (chemical structural formulas containing Z (Base)) are shown below.

[0340] (Z: basic functional group, m≧1, 0<y≦1)

[0341] The polymers containing basic functional groups that make up the composite polymer membrane may be homopolymers or ladandum copolymers containing both basic and cationic functional groups. Their generalized chemical structural formulas (including Z (Base)) are shown below.

[0342] (Z: basic functional group, m≧1, 0<y≦1, (+)Z-R: cationic functional group in which an organic group is bonded to a basic functional group, R: organic group (alkyl group, benzyl group, etc.), X(-): counter anion of the cationic functional group)

[0343] The polymer having a basic functional group that constitutes the composite polymer membrane may be a block polymer having a basic functional group. Their generalized chemical structural formula (chemical structural formula including Z (Base)) is shown below.

[0344] (Z: basic functional group, l′≧1, m≧1, 0<y≦1)

[0345] The polymer having a basic functional group that constitutes the composite polymer membrane may be a block polymer having a basic functional group and a cationic functional group. The generalized chemical structural formula (chemical structural formula including Z (Base)) of such a block polymer is shown below.

[0346] (Z: basic functional group, l'≧1, m≧1, 0<y≦1, (+)Z-R: cationic functional group in which an organic group is bonded to a basic functional group, R: organic group (alkyl group, benzyl group, etc.), X(-): counter anion of the cationic functional group)

[0347] In the generalized chemical structural formulas of homopolymers, lathand copolymers, and block polymers having basic functional groups, Z (Base) represents a basic functional group, such as amine, imine, pyridine, imidazole, pyrazole, pyrrole, or triazole.

[0348] In the generalized chemical structural formulas of homopolymers, lathand copolymers, and block polymers having basic functional groups, m represents the overall degree of polymerization of the polymer having basic functional groups.

[0349] In the generalized chemical structural formulas of homopolymers, lathand copolymers, and block polymers having basic functional groups, y represents the proportion (percentage) of monomer units having basic functional groups.

[0350] In the generalized chemical structural formulas of homopolymers, lathand copolymers, and block polymers having basic functional groups, (1-y) represents the proportion (percentage) of monomer units not having basic functional groups.

[0351] In the generalized chemical structure of a homopolymer, a ladandum copolymer, and a block polymer having a basic functional group, R ３ represents the main skeleton of the monomer unit having a basic functional group.

[0352] In the generalized chemical structure of a homopolymer, a ladandum copolymer, and a block polymer having a basic functional group, R ４ represents a monomer unit that does not have a basic functional group.

[0353] In the generalized chemical structure of the homopolymer, latham copolymer, and block polymer having a basic functional group, the monomer unit having a basic functional group may have one or more basic functional groups.

[0354] In the generalized chemical structure of a homopolymer, a ladandum copolymer, and a block polymer having a basic functional group, R ０ ' represents a monomer unit of a hydrophobic polymer or a water-repellent polymer, and may contain two or more types of monomer units.

[0355] In the generalized chemical structural formulas of homopolymers, lathand copolymers, and block polymers having basic functional groups, l' represents the degree of polymerization of the monomer units of the hydrophobic polymer or water-repellent polymer.

[0356] In the generalized chemical structural formulas of homopolymers, random copolymers, and block polymers having basic functional groups, when a slash ( / ) is written above a hyphen (-), it means that the monomer units on either side of the hyphen are linked randomly, and when only a hyphen (-) is written, it means that the polymers on either side of the hyphen are linked in a block fashion.

[0357] The composite polymer membrane has multiple acid-base complexes per molecule of polymers having acidic functional groups (homopolymers, ladandam copolymers, and block polymers) and per molecule of polymers having basic functional groups (homopolymers, ladandam copolymers, and block polymers), and therefore can achieve high conductivity (e.g., under low humidity conditions) while suppressing the elution of polymers and the like from the composite polymer membrane.

[0358] The mixture of (1) a polymer with acidic functional groups and (2) a polymer with basic functional groups that forms a composite polymer membrane is called a composite polymer.

[0359] Specific embodiments and chemical structural formulas of the composite polymer membrane of the present invention are shown below.

[0360] The composite polymer membrane of the present invention includes a combination of a polymer (random polymer or homopolymer) having acidic functional groups and a polymer (random polymer or homopolymer) having basic groups.

[0361] Composite polymer film consisting of a homopolymer or a ladandum copolymer having an acidic functional group and a homopolymer or a ladandum copolymer having a basic functional group

[0362] (A-H: acidic functional group, n≧1, 0<x≦1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, 0<w≦1, A(-): anionic functional group in which a proton (H(+)) is ionized from an acidic functional group, (+)Z-H: cationic functional group in which a proton is bonded to a basic functional group, A(-)(+)Z-H: acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves))

[0363] A composite polymer membrane consisting of a homopolymer or random copolymer having an acidic functional group and a homopolymer or random copolymer having a basic functional group and a cationic functional group (volatile acid HX is removed from the system by contact with liquid water or humidification).

[0364] (A-H: acidic functional group, n≧1, 0<x≦1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, 0<w≦1, 0<t≦1, 0<u≦1, 0<v≦1, v+w=1, A(-): an anionic functional group formed by ionization of a proton (H(+)) from an acidic functional group, (+)Z-H: a cationic functional group formed by a proton bonding to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves), A(-)(+)Z-R: an ion pair consisting of an anionic functional group and a cationic functional group)

[0365] The composite polymer membrane of the present invention includes a combination of a block copolymer (graft copolymers including star copolymers) containing a polymer (random polymer or homopolymer) having acidic functional groups and a polymer (random polymer or homopolymer) having basic groups.

[0366] Composite polymer membranes consisting of block polymers with acidic functional groups and homopolymers or random copolymers with basic functional groups

[0367] (A-H: acidic functional group, n≧1, 0<x≦1, l≧1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, 0<w≦1, A(-): an anionic functional group in which a proton (H(+)) has been ionized from an acidic functional group, (+)Z-H: a cationic functional group in which a proton has been bonded to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves))

[0368] A composite polymer membrane consisting of a block polymer with acidic functional groups and a homopolymer or random copolymer with basic and cationic functional groups (volatile acid HX is removed from the system by contact with liquid water or humidification).

[0369] (A-H: acidic functional group, n≧1, 0<x≦1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, 0<w≦1, 0<t≦1, 0<u≦1, 0<v≦1, v+w=1, A(-): an anionic functional group formed by ionization of a proton (H(+)) from an acidic functional group, (+)Z-H: a cationic functional group formed by a proton bonding to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves), A(-)(+)Z-R: an ion pair consisting of an anionic functional group and a cationic functional group)

[0370] The composite polymer membrane of the present invention includes a combination of a polymer (random polymer or homopolymer) having acidic functional groups and a block copolymer (graft copolymers also include star copolymers) containing a polymer (random polymer or homopolymer) having basic groups.

[0371] Composite polymer membranes consisting of homopolymers or random copolymers with acidic functional groups and block polymers with basic functional groups

[0372] (A-H: acidic functional group, n≧1, 0<x≦1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, l'≧1, 0<w≦1, A(-): an anionic functional group in which a proton (H(+)) has been ionized from an acidic functional group, (+)Z-H: a cationic functional group in which a proton has been bonded to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves))

[0373] A composite polymer membrane consisting of a homopolymer or random copolymer having an acidic functional group and a block polymer having a basic functional group and a cationic functional group (volatile acid HX is removed from the system by contact with liquid water or humidification).

[0374] (A-H: acidic functional group, n≧1, 0<x≦1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, 0<w≦1, 0<t≦1, 0<u≦1, 0<v≦1, v+w=1, A(-): an anionic functional group formed by ionization of a proton (H(+)) from an acidic functional group, (+)Z-H: a cationic functional group formed by a proton bonding to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves), A(-)(+)Z-R: an ion pair consisting of an anionic functional group and a cationic functional group)

[0375] The composite polymer membrane of the present invention includes a combination of a block copolymer (graft copolymers including star copolymers) containing a polymer (random polymer or homopolymer) having acidic functional groups and a block copolymer (graft copolymers including star copolymers) containing a polymer (random polymer or homopolymer) having basic groups.

[0376] Composite polymer membranes consisting of block polymers with acidic and basic functional groups

[0377] (A-H: acidic functional group, n≧1, 0<x≦1, l≧1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, l'≧1, 0<w≦1, A(-): an anionic functional group in which a proton (H(+)) has been ionized from an acidic functional group, (+)Z-H: a cationic functional group in which a proton has been bonded to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves))

[0378] A composite polymer membrane consisting of a block polymer having an acidic functional group and a block polymer having a basic functional group and a cationic functional group (volatile acid HX is removed from the system by contact with liquid water or by humidification).

[0379] (A-H: acidic functional group, n≧1, 0<x≦1, 0<z≦1, Z: basic functional group, m≧1, 0<y≦1, 0<w≦1, 0<t≦1, 0<u≦1, 0<v≦1, v+w=1, A(-): an anionic functional group formed by ionization of a proton (H(+)) from an acidic functional group, (+)Z-H: a cationic functional group formed by a proton bonding to a basic functional group, A(-)(+)Z-H: an acid-base complex consisting of an acidic functional group and a basic functional group (an ion pair consisting of the acid and base themselves), A(-)(+)Z-R: an ion pair consisting of an anionic functional group and a cationic functional group)

[0380] In the generalized chemical structural formula of the composite polymer, AH (Acid) and Z (Base) are as explained in the generalized chemical structural formula of the polymer having an acidic functional group and the generalized chemical structural formula of the polymer having a basic functional group.

[0381] In the generalized chemical structural formula of a composite polymer, A-H (Acid) and Z (Base) are paired, A-H (Acid) (-) (+) Z (Base), which represents an acid-base complex. A-H (Acid) that is not paired with Z (Base) is a free acidic functional group that can ionize protons that contribute to proton conductivity. Z (Base) that is not paired with A-H (Acid) is a free basic functional group.

[0382] In the generalized chemical structure of the composite polymer, n, l, x, (1-x), R１ , R ２ , R ０ is as explained in the generalized chemical structure of a polymer having an acidic functional group.

[0383] In the generalized chemical structure of the composite polymer, m, l', y, (1-y), R ３ , R ４ , R ０ ' is as explained in the generalized chemical structural formula of a polymer having a basic functional group.

[0384] In the generalized chemical structural formula of the composite polymer, z represents the proportion (percentage) of the acidic functional group of the monomer unit having the acidic functional group that forms an acid-base complex with the basic functional group.

[0385] In the generalized chemical structural formula of the composite polymer, (1-z) represents the proportion (percentage) of the acidic functional groups of the monomer units having the acidic functional groups that do not form an acid-base complex with the basic functional groups and are free acidic functional groups.

[0386] In the generalized chemical structural formula of the composite polymer, w represents the proportion (percentage) of the basic functional group of the monomer unit having the basic functional group that forms an acid-base complex with the acidic functional group.

[0387] In the generalized chemical structural formula of the composite polymer, (1-w) represents the proportion (percentage) of the basic functional groups of the monomer units having a basic functional group that do not form an acid-base complex with the acidic functional group and are free basic functional groups.

[0388] The polymer having an acidic functional group in the composite polymer membrane (II)(2) is a polymer other than the polymer consisting of a monomer unit having a phosphonic acid functional group in a side chain via a spacer structure, as described in the polymer [2] above.

[0389] Polymer Having Acidic Functional Group The polymer having an acidic functional group is preferably a hydrocarbon-based vinyl polymer, and is a polymer containing 0.70 or more, 0.80 or more, 0.90 or more, preferably 0.95 or more, and more preferably 0.98 or more acidic functional groups per monomer unit.

[0390] The polymer having an acidic functional group is more preferably a polymer containing approximately 100 mol % of the acidic functional group in the monomer unit.

[0391] The polymer having an acidic functional group is preferably a hydrocarbon-based vinyl polymer, and may contain 50 mol% or less of polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, polytrimethylstyrene, or the like.

[0392] The acidic functional group present in the side chain of the polymer having the acidic functional group is preferably an acidic functional group composed of at least one type selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0393] The polymer having an acidic functional group may be prepared without deprotection or may be prepared after deprotection. The polymer having an acidic functional group is obtained, for example, by polymerizing a monomer having a protecting group on the acidic functional group and then deprotecting the protecting group, and is a polymer containing approximately one acidic functional group per monomer unit. The polymer having an acidic functional group is, for example, a polymer in which a phosphonate ester is deprotected to form a phosphonic acid group, or a polymer in which a sulfonic acid ester is deprotected to form a sulfonic acid group.

[0394] The polymer having an acidic functional group is preferably a polymer containing a monomer unit having an acidic functional group, which is composed of at least one selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid units.

[0395] The content of the monomer units having an acidic functional group in the polymer having an acidic functional group is preferably 50 mol % or more, more preferably 70 mol % or more, and even more preferably 90 mol % or more. The polymer having an acidic functional group may be, for example, a random copolymer containing about 90 mol % of styrene phosphonic acid and about 90 mol % of another monomer.

[0396] The polymer having an acidic functional group is preferably a polymer having an acidic functional group composed of at least one selected from the group consisting of poly(4-styrenesulfonic acid), polyvinylsulfonic acid, poly(4-styrenephosphonic acid), and polyvinylphosphonic acid.

[0397]

[0398] Block Copolymer (Example of Polymer Having Acidic Functional Group) The polymer having an acidic functional group may be a block copolymer having an a-b type unit in which at least an a block and a b block are linked by a covalent bond.

[0399] In the block copolymer, the a block is composed of a hydrophobic polymer or a water-repellent polymer. The hydrophobic polymer is preferably a hydrophobic hydrocarbon-based vinyl polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher.

[0400] In the block copolymer, the b block is a polymer having an acidic functional group, which is composed of a polymer having an acidic functional group in a side chain, and the acidic functional group is preferably at least one selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0401] The block copolymer is a block copolymer having a-b type units in which at least an a block and a b block are linked by a covalent bond, and may further include a c block as a third portion, a d block as a fourth portion, etc.

[0402] Block copolymers also include so-called graft copolymers having a branched structure, and star copolymers.

[0403] In a membrane made of a block copolymer, the hydrophobic or water-repellent phase of polymer A maintains mechanical strength, while microscopic phase separation can occur between the phase of polymer B, which has ion channels derived from the polymer having sulfonic acid or phosphonic acid groups, which are acidic functional groups. By adding appropriate humidification, the composite polymer membrane can exhibit good proton conductivity by protons hopping between anions formed by proton ionization from sulfonic acid or phosphonic acid groups and water molecules in the ion-conducting channels made of multiple sulfonic or phosphonic acid groups.

[0404] a Block The a block is composed of a hydrophobic polymer or a water-repellent polymer.

[0405] When the a-block is formed into a composite membrane, it exhibits mechanical strength even at high temperatures (100° C. or higher).

[0406] The polymer constituting the a block is preferably a polymer having a glass transition temperature (Tg, measured by DSC) of 100° C. or higher. The glass transition temperature (Tg, measured by DSC) of the polymer constituting the a block is more preferably 120° C. or higher, and even more preferably 140° C. or higher.

[0407] In this specification, unless otherwise specified, the glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0408] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0409] The polymer constituting the a block is preferably a hydrophobic polymer, and is preferably a hydrophobic hydrocarbon-based vinyl polymer having excellent chemical stability, more preferably an aromatic vinyl polymer, and even more preferably a polystyrene-based polymer.

[0410] The polystyrene-based polymer preferably includes polystyrene, polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, polytrimethylstyrene, and the like.

[0411] The polymer constituting the a-block may be a water-repellent polymer, which is a polymer that has the property of repelling water droplets when the water droplets are dropped onto its surface (water repellency), and has a contact angle of preferably 90° or more, more preferably 100° or more.

[0412] The water-repellent polymer preferably includes a silicone compound and a fluorinated polymer.

[0413] The silicone compound is a compound having a siloxane bond (Si—O—Si), and is preferably a polyorganosiloxane. Examples of the polyorganosiloxane include polydimethylsiloxane and polymethylphenylsiloxane. The polyorganosiloxane may have an unsaturated bond or a functional group such as an amino group.

[0414] The fluorinated polymer is preferably a copolymer of a fluorinated (meth)acrylic compound. The fluorinated (meth)acrylic compound refers to a compound in which at least a portion of the hydrogen atoms of the (meth)acrylic compound are replaced with fluorine atoms, such as a fluoroalkyl (meth)acrylate such as perfluoroalkyl (meth)acrylate, or an N-alkylperfluoroalkylsulfonamidoalkyl (meth)acrylate such as N-methylperfluorooctylsulfonamidoethyl (meth)acrylate.

[0415] b Block The b block is a polymer made up of monomer units having an acidic functional group in the side chain.

[0416] The acidic functional group is preferably an acidic functional group composed of at least one selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0417] The polymer constituting the b block is preferably a polymer containing a monomer unit having an acidic functional group composed of at least one selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid.

[0418] One embodiment of the arrangement of the block copolymer The block copolymer is a diblock copolymer having at least ab type units in which the a block and the b block are linked by a covalent bond.

[0419] One embodiment of the ab type diblock copolymer has the following chemical formula:

[0420]

[0421] The average degree of polymerization (e.g., n in the chemical formula) of the a block (e.g., the poly(4-tert-butylstyrene) portion in the chemical formula) is preferably an integer of 2 or greater, for example, 2 or greater, 10 or greater, 30 or greater, 50 or greater, 100 or greater, 200 or greater, 500 or greater, 800 or greater, 1,000 or greater, 1,500 or greater, or 2,000 or greater. The average degree of polymerization of the a block is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000.

[0422] The average degree of polymerization of the b block (e.g., the polymer portion composed of monomer units having a sulfonic acid group or a phosphonic acid group in the chemical formula) (e.g., m in the chemical formula) is preferably an integer of 2 or greater, for example, 2 or greater, 10 or greater, 30 or greater, 50 or greater, 100 or greater, 200 or greater, 500 or greater, 800 or greater, 1,000 or greater, 1,500 or greater, or 2,000 or greater. The average degree of polymerization of the b block is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000.

[0423] The average degree of polymerization is determined by gel permeation chromatography (GPC) using standard polystyrene and by comparing the proton intensity of initiator residues with the proton intensity of the repeating unit of the polymer. １ Determined by H-NMR.

[0424] Polymer with Basic Functional Groups The composite polymer membrane comprises a polymer with basic functional groups in addition to a polymer with acidic functional groups.

[0425] The composite polymer membrane contains a polymer having a basic functional group in addition to a polymer having an acidic functional group, thereby forming a plurality of acid-base complexes between the phosphonic acid group or sulfonic acid group and the basic functional group. Since the membrane basically does not contain a low molecular weight electrolyte, the elution of the polymer electrolyte (polymer having a phosphonic acid group or polymer having a sulfonic acid group), the polymer having a basic functional group, and the low molecular weight electrolyte from the membrane into water is suppressed, and proton ionization from the phosphonic acid group or sulfonic acid group is also promoted. －３ It exhibits good conductivity of 100 S / cm or more.

[0426] The polymer having a basic functional group preferably has a glass transition temperature of 300°C or lower, 250°C or lower, 200°C or lower, 150°C or lower, and 100°C or lower, more preferably 80°C or lower, even more preferably 60°C or lower, and particularly preferably 50°C or lower, in that order.

[0427] In this specification, unless otherwise specified, the glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0428] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0429] The polymer having a basic functional group is preferably a polymer having a basic functional group composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0430] The polymer having a basic functional group is preferably a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, the c block being composed of a hydrophobic polymer or a water-repellent polymer, and the d block being a polymer having a basic functional group composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0431] The polymer having a basic functional group is preferably a polymer having 5 or more basic functional groups, more preferably 10 or more, and even more preferably 15 or more.

[0432] The polymer having a basic functional group is more preferably a polymer having a glass transition temperature of 100°C or lower and having five or more basic functional groups composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0433] The polymer having a basic functional group is more preferably a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of a polymer having five or more basic functional groups each composed of at least one type selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group.

[0434] The polymer having a basic functional group is more preferably a polymer having a glass transition temperature of 100°C or lower and containing five or more monomer units having a basic functional group, the monomer units being composed of at least one selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, and vinylpyrrole.

[0435] More preferably, the polymer having a basic functional group is a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of a polymer containing five or more monomer units composed of at least one type selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, vinylpyrrole, and vinyltriazole.

[0436] More preferably, the polymer having a basic functional group is a block copolymer having c-d type units in which at least a c block and a d block are linked by a covalent bond, wherein the c block is composed of a hydrophobic polymer or a water-repellent polymer, and the d block is composed of at least one polymer selected from the group consisting of polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, poly(2-vinylpyridine), polyvinylimidazole, polyvinylpyrazole, polyvinylpyrrole, and polyvinyltriazole.

[0437] The polymer having a basic functional group is preferably polyethyleneimine (EI), polyallylamine (aAm, Tg (DSC): for example, about 30°C), polyvinylamine, polyvinylpyridine (VP), poly(2-vinylpyridine) (2VP, Tg (DSC): for example, about 100°C), polyvinylimidazole, polyvinylpyrazole, polyvinylpyrrole, or the like.

[0438] The polymer constituting the c block is preferably a hydrophobic polymer or a water-repellent polymer, and the hydrophobic polymer or water-repellent polymer constituting the a block described in the above [3] Block copolymer can be used.

[0439] The molecular weight of the polymer having a basic functional group is preferably 200 or more, 500 or more, preferably 1,000 or more, more preferably 2,000 or more, 5,000 or more, 10,000 or more, 20,000 or more, 40,000 or more, or 80,000 or more.

[0440] The molecular weight of a polymer having basic functional groups can be determined by gel permeation chromatography (GPC) to determine the number average molecular weight (Mn) using standard polystyrene for molecular weight calibration.

[0441] In the composite polymer membrane of the present invention, (2) the polymer having a basic functional group may be a polymer having a cationic functional group based on the basic functional group, and a part of the basic functional group is quaternized with an organic halogen compound to generate a cation, thereby forming a cationic functional group based on the basic functional group.

[0442] In the composite polymer membrane of the present invention, the proportion of cationic functional groups based on basic functional groups among the basic functional groups may be 10 mol % or more.

[0443] In the composite polymer membrane of the present invention, the organic halogen compound is a compound having an alkyl halide moiety.

[0444] The "compound having an alkyl halide moiety" is a compound having an alkyl halide moiety, ｎ H ２ｎ＋１ -X (n: natural number, X=F, Cl, Br, I), and R-C ｎ H ２ｎ The compound is a compound represented by —X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and is particularly preferably an alkyl halide.

[0445] The composite polymer membrane of the present invention comprises: a polymer having an anionic group based on an acidic functional group, which is obtained by combining the polymer having the (1) acidic functional group with a polymer having a cationic functional group based on the basic functional group, so that a proton is ionized from the acidic functional group of the polymer having the (1) acidic functional group to form an anionic functional group, and a low-molecular-weight acid consisting of a counter anion of the cationic functional group of the polymer having the cationic functional group originating from the basic functional group and a proton escapes from the membrane; and a polymer having a cationic group based on the basic functional group, －３ It exhibits a conductivity of 100 S / cm or more.

[0446] One embodiment of the composite polymer membrane The composite polymer membrane includes (1) a polymer having acidic functional groups and (2) a polymer having basic functional groups.

[0447] One embodiment of the composite polymer membrane is a combination of (1) a polymer having an acidic functional group and (2) a polymer having a basic functional group.

[0448] (1) Polymers having acidic functional groups

[0449]

[0450] (2) Polymers having basic functional groups

[0451]

[0452] A preferred embodiment of the composite polymer membrane is a composite polymer membrane (electrolyte membrane) that combines a polymer having an acidic functional group (a polymer having a phosphonic acid group) such as poly(4-styrenephosphonic acid) (sPA) with a polymer having a basic functional group such as polyethyleneimine (EI).

[0453]

[0454] The composite polymer membrane has a high ion cluster forming ability because the equivalent mass EW (100 to 400) of the polymer having an acidic functional group roughly corresponds to the molecular weight of the monomer.

[0455] The composite polymer membrane does not show a significant change in conductivity before and after immersion in water. The composite polymer membrane is a composite membrane that does not show a decrease in conductivity of 25% or more before and after immersion in water. The composite polymer membrane is a composite membrane that does not show a difference in conductivity of 25% or more compared to a membrane that has not been immersed in water, even when immersed in water at 20°C to 70°C, for example, 60°C, for 1 hour. The degree of change in conductivity before and after immersion in water, including error, is preferably 25% or less, more preferably 15% or less, and even more preferably 5% or less.

[0456] The composite polymer membrane exhibits no elution of the polymer or low molecular weight electrolyte after immersion in water (for example, at 20°C and 70°C), and exhibits a solubility of 1.0 x 10 under appropriate conditions of 60°C to 150°C and 0% RH to 100% RH. －３ Achieve a conductivity of 0.5 S / cm or higher.

[0457] The composite polymer membrane generates substantially no eluate from the membrane after immersion for 1 hour in water at 20° C. to 70° C., for example, water at 60° C. The amount of eluate eluted from the membrane into water is preferably 25% by mass or less, more preferably 15% by mass or less, and even more preferably 5% by mass or less.

[0458] Composite polymer membranes can be manufactured, for example, by solvent casting, press molding, and the like.

[0459] In the composite polymer membrane, there is a phase in which ion channels originating from the phosphonic acid groups or sulfonic acid groups of the polymer having acidic functional groups are generated. When the composite polymer membrane is moderately humidified, protons hop over the anions formed by the ionization of protons from the phosphonic acid groups or sulfonic acid groups and over water molecules in the ion conduction channels, resulting in good proton conductivity. For example, under appropriate conditions of 60°C to 150°C and 0% RH to 100% RH, the composite polymer membrane exhibits a high proton conductivity of 1.0 × 10 －３ It exhibits a conductivity of 100 S / cm or more.

[0460] The composite polymer membrane exhibits conductivity even under humidified conditions of 100° C. or higher or under low humidified conditions, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0461] The composite polymer membrane may be impregnated with a non-volatile acid (e.g., phosphoric acid) that is a proton donor for the low molecular weight electrolyte. By doing so, for example, at 100°C or higher and under non-humidified conditions, good proton conductivity (e.g., 1.0 × 10 －３ The conductivity is 1000 S / cm or more.

[0462] The proton conductivity is 1.0×10 －３ S / cm or more, 2.0×10 －３ S / cm or more, 3.0×10 －３ S / cm or more, 5.0×10 －３ S / cm or more, 7.0×10 －３ S / cm or more, 1.0×10 －２ S / cm or more, 2.0×10 －２ S / cm or more, 3.0×10 －２ S / cm or more, 5.0×10 －２ S / cm or more, 7.0×10 －２ S / cm or more, 1.0×10 －１ It may be S / cm or more.

[0463] Composite polymer membranes are useful as electrolyte membranes.

[0464] The composite polymer membrane can be used at temperatures above 100° C. and is suitable for use in fuel cells.

[0465] Temperature and Humidity for Use of Composite Polymer Membrane The composite polymer membrane can be used in the medium temperature range of 100°C or higher and 200°C or lower.

[0466] The use temperature of the composite polymer membrane is the temperature at which the proton conductive membrane is used, and is preferably room temperature or higher, more preferably 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, or 90° C. or higher, and in some cases 100° C. or higher. The use temperature of the composite polymer membrane is 200° C. or lower, 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, or 110° C. or lower, in some cases.

[0467] The composite polymer membrane can be used, for example, under conditions of 80°C and 60% RH, or 80°C and 80% RH. The composite polymer membrane exhibits conductivity even under humidified conditions at 100°C or higher, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0468] By adding appropriate humidity to the composite polymer membrane, protons ionized from the acidic functional groups in the ion channel hop on anions or water molecules, resulting in a 1.0 × 10 －３ The resulting polymer exhibits excellent proton conductivity of 100 S / cm or more.

[0469] The polymer having an acidic functional group is a vinyl monomer (CH ２ The polymer may or may not be a vinyl polymer based on =CH-R (where R is a substituent).

[0470] Ionomer The ionomer of the present invention contains the composite polymer that constitutes the composite polymer membrane, and can be used to form a catalyst layer of a polymer electrolyte fuel cell.

[0471] The mixture of (1) a polymer with acidic functional groups and (2) a polymer with basic functional groups that forms a composite polymer membrane is called a composite polymer.

[0472] The polymer and composite polymer of the present invention can be used as an electrolyte membrane, and also as a proton-conducting polymer, so-called ionomer, to be used in a catalyst layer.

[0473] First Step of Manufacturing Method of Composite Polymer For example, as a phosphonate ester monomer having a spacer structure (preferably an alkyl spacer), a monomer having a protecting group (e.g., an ethyl group, an n-butyl group) on the phosphonic acid group (e.g., diethyl 4-(4-vinylphenyl)butylphosphonate) is synthesized.

[0474] Alternatively, a monomer having a protecting group (eg, ethyl group) on the phosphonic acid group (eg, 4-styrenephosphonic acid diethyl) is synthesized as a phosphonate ester monomer.

[0475] Alternatively, a monomer having a protecting group (for example, n-butyl group) on the sulfonic acid group (for example, n-butyl 4-styrenesulfonate) is synthesized as a sulfonate ester monomer.

[0476] Second Step Subsequently, the monomer is polymerized.

[0477] Third Step: Subsequently, the alkyl protecting groups of the obtained polymer (for example, poly(4-(4-vinylphenyl)butylphosphonic acid diethyl) are deprotected to synthesize poly(4-(4-vinylphenyl)butylphosphonic acid) (also known as poly(4-(4-phosphonobutyl)styrene)), which is a phosphonic acid polymer having an alkyl spacer.

[0478] Fourth Step Subsequently, the resulting polymer (for example, poly(4-(4-vinylphenyl)butylphosphonic acid)) is formed into a membrane to produce a proton-conductive electrolyte membrane.

[0479] Method for Producing Block Copolymers Block copolymers having a block and a block are preferably synthesized by addition polymerization such as anionic polymerization, cationic polymerization, or radical polymerization.

[0480] (1) A step of preparing a hydrophobic polymer or a water-repellent polymer and producing an a-block; mixing a monomer constituting the a-block (for example, 4-tert-butylstyrene monomer as a hydrophobic polymer), a RAFT agent (reversible addition-fragmentation chain transfer agent), and a polymerization initiator, polymerizing the resulting mixture, and then isolating and purifying the resulting mixture to synthesize a macro RAFT agent containing the a-block.

[0481] RAFT agents (reversible addition-fragmentation chain transfer agents) are preferably thiocarbonylthio compounds such as dithioesters, dithiocarbamates, trithiocarbonates, and xanthates.

[0482] The RAFT agent is preferably 4-[(2-carboxyethylsulfanylthiocarbonyl)sulfanyl]-4-cyanopentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methyl ... Methyl 2-(dodecylthiocarbonothioylthio)propionic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid pentafluorophenyl ester, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid 3-azido-1-propanol ester, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, methyl 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoate, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoate N-Hydroxysuccinimidyl ethylpropionate, 3-[[(benzylthio)carbonothioyl]thio]propionic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, cyanomethyl[3-(trimethoxysilyl)propyl]trithiocarbonate, 3-butenyl-2-(dodecylthiocarbonothioylthio)-2-methylpropane, phthalimidomethylbutyltrithiocarbonate, 2-(2-carboxyethylsulfanylthiocarbonylsulfanyl) ) propionic acid, 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanol, and RAFT agents such as cyanomethyl dodecyl trithiocarbonate 1,4-phenylenebis(methylene)didodecylbis(carbonotrithioate), 1,4-phenylenebis(methylene)dibutylbis(carbonotrithioate), and 1,4-phenylenebis(methylene)dioctadecylbis(carbonotrithioate).

[0483] By appropriately selecting the RAFT agent, it is possible to synthesize the desired block copolymer sequence.

[0484] The polymerization initiator is preferably an azo-based radical polymerization initiator, a peroxide-based radical polymerization initiator, or the like.

[0485] The polymerization initiator is preferably an azo-based radical polymerization initiator such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or dimethyl 2,2'-azobisisobutyrate.

[0486] The polymerization initiator is preferably a peroxide radical polymerization initiator such as benzoyl peroxide, t-butyl hydroperoxide, or cumene hydroperoxide.

[0487] The solvent used in the synthesis and isolation is not particularly limited. The solvent is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and ethereal solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran.

[0488] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0489] (2) A step of polymerizing the a block and a monomer that constitutes the b block and has a phosphonic acid group with a protecting group on the side chain via a spacer structure to produce a block copolymer having a-b type units in which the a block and the b block are linked by a covalent bond. In the presence of a polymerization initiator, a macro RAFT agent containing the a block and a monomer (e.g., diethyl 4-(4-vinylphenyl)butylphosphonate) in which the phosphonic acid group that constitutes the b block has a protecting group (e.g., n-butyl group) are polymerized to produce a block copolymer having a-b type units in which the a block and the b block are linked by a covalent bond.

[0490] The solvent used in the synthesis and isolation is not particularly limited. The solvent is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and ethereal solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran.

[0491] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0492] (3) A step of deprotecting the protecting group of the b block to produce a polymer having a phosphonic acid group in the monomer unit constituting the b block. The protecting group of the b block is deprotected using a basic solution (e.g., aqueous sodium hydroxide solution) or bromotrimethylsilane (see Tetrahedron Letters 1977, 18, 155-158.), to produce a polymer having a phosphonic acid group in the side chain of the monomer unit constituting the b block.

[0493] Method for Producing Composite Polymer Membrane Step of Mixing Polymer Having Basic Functional Group in Composite Polymer Membrane The composite polymer membrane of the present invention contains (1) a polymer having an acidic functional group and (2) a polymer having a basic functional group.

[0494] The composite polymer membrane of the present invention is prepared by mixing (1) a polymer having acidic functional groups with (2) a polymer having basic functional groups.

[0495] The composite polymer membrane of the present invention, obtained by mixing a block copolymer (block polymer) and a polymer having a basic functional group, forms a plurality of acid-base complexes between the phosphonic acid groups and the basic functional groups and basically does not contain small molecular weight electrolytes. Therefore, elution of small molecular weight electrolytes from the membrane into liquid water does not occur. In addition, elution of polymer electrolytes (polymers having phosphonic acid groups) and polymers having basic functional groups from the membrane into liquid water is also suppressed, and proton ionization from the phosphonic acid groups is also promoted, resulting in a 1.0 × 10 －３ It exhibits good conductivity of 100 S / cm or more.

[0496] The ratio of the polymer having an acidic functional group to the polymer having a basic functional group is 1.0 × 10, which suppresses the elution of the polymer electrolyte (polymer having an acidic functional group) and the polymer having a basic functional group from the membrane into the liquid water and also promotes proton ionization from the phosphonic acid group. －３ From the viewpoint of exhibiting good conductivity of 100 S / cm or more, with regard to the molar ratio of acidic functional groups to basic functional groups, it is preferable that the proportion of acidic functional groups used in the polymer having acidic functional groups is larger than the proportion of basic functional groups used in the polymer having basic functional groups.

[0497] The proportion of the polymer having an acidic functional group and the polymer having a basic functional group, in terms of the molar ratio of the acidic functional group to the basic functional group, (acidic functional groups of the polymer having an acidic functional group):(basic functional groups of the polymer having a basic functional group) is preferably 50 to 99:50 to 1, more preferably 65 to 99:35 to 1, and even more preferably 80 to 99:20 to 1.

[0498] Formation of Composite Polymer Membrane The composite polymer membrane of the present invention is preferably formed into a membrane by a method such as casting or pressing before removing the solvent.

[0499] The composite polymer film of the present invention is preferably formed into a film by a method such as a hot melt method.

[0500] Thickness of Composite Polymer Membrane The composite polymer membrane of the present invention has excellent processability and can be formed by a hot melt method, a solvent casting method, or the like, and therefore can be made thinner than conventional proton conductive membranes.

[0501] The composite polymer membrane preferably has a membrane thickness of 1.00 mm or less, 0.90 mm or less, 0.80 mm or less, 0.75 mm or less, 0.73 mm or less, 0.72 mm or less, 0.71 mm or less, 0.70 mm or less, 0.68 mm or less, 0.65 mm or less, 0.60 mm or less, 0.55 mm or less, 0.50 mm or less, 0.45 mm or less, 0.40 mm or less, 0.35 mm or less, 0.30 mm or less, 0.28 mm or less, 0.25 mm or less, 0.23 mm or less, or 0.20 mm or less.

[0502] Proton Conductivity of Composite Polymer Membrane The composite polymer membrane of the present invention exhibits good proton conductivity in a non-humidified environment, a low-humidity environment, or a humidified environment.

[0503] The proton conductivity of the composite polymer membrane is preferably 0.0003 S / cm or more, 0.0005 S / cm or more, or 0.001 S / cm or more in a low-humidity environment or a humidified environment (for example, at a temperature of about 80°C to 150°C and a humidity of about 0% RH to 100% RH).

[0504] The resulting conductivity is 2.0 x 10 －３ S / cm or more, 3.0×10 －３ S / cm or more, 5.0×10 －３ S / cm or more, 7.0×10 －３ S / cm or more, 1.0×10 －２ S / cm or more, 2.0×10 －２ S / cm or more, 3.0×10 －２ S / cm or more, 5.0×10 －２ S / cm or more, 7.0×10 －２ S / cm or more, 1.0×10 －１ The conductivity may be determined by an AC impedance method.

[0505] Fuel Cells The polymer having an acidic functional group of the present invention and the composite polymer forming the composite polymer membrane can be used as an electrolyte membrane, and can also be used as a proton-conductive polymer, so-called ionomer, used in a catalyst layer.

[0506] The fuel cell of the present invention comprises a composite polymer membrane of the present invention.

[0507] The fuel cell of the present invention preferably comprises a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side catalyst layer, the proton conductive membrane of the present invention, an air electrode-side catalyst layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0508] The fuel cell of the present invention preferably has a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side gas diffusion layer, a fuel electrode-side catalyst layer, the proton conductive membrane of the present invention, an air electrode-side catalyst layer, an air electrode-side gas diffusion layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0509] The present disclosure will be described in more detail below with reference to examples.

[0510] The present disclosure is not limited thereto.

[0511] [1] Example 1 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 1 In Example 1, poly(4-tert-butylstyrene)-b-poly(n-butyl 4-styrenesulfonate) (hereinafter also referred to as "B-nBsS diblock copolymer") was synthesized as a block copolymer according to the following Scheme 1 (first step).

[0512] Next, the ester protecting groups of the poly(n-butylstyrenesulfonate) block were deprotected by hydrolysis to synthesize poly(4-tert-butylstyrene)-b-poly(4-styrenesulfonic acid) (hereinafter also referred to as "B-sSA diblock copolymer") having a proton-donating group (second step).

[0513] This B-sSA diblock copolymer was formed into a membrane to produce the proton conductive membrane of Example 1 (hereinafter also referred to as "B-sSA membrane") (third step).

[0514] In the term "B-sSA," "B" is an abbreviation for poly(4-tert-butylstyrene), and "B" is a hydrophobic block having no proton-accepting group, which aggregates with each other to form a glassy domain at the temperature and humidity in use of the proton-conductive electrolyte membrane, i.e., the "a block" as referred to in the present invention.

[0515] In addition, in the term "B-sSA," "sSA" is an abbreviation for poly(4-styrenesulfonic acid), which is a polymer having a proton-donating group, that is, the "b block" as referred to in the present disclosure.

[0516]

[0517] (1-1) First Step Step 1-1 Commercially available 4-tert-butylstyrene monomer was purified. Unpurified 4-tert-butylstyrene monomer was passed through a column packed with basic alumina. Furthermore, the 4-tert-butylstyrene monomer was purified using an alkyl metal compound.

[0518] The purified 4-tert-butylstyrene monomer, RAFT agent, azobisisobutyronitrile (AIBN), and diethylbenzene (isomer mixture) were weighed out in amounts of 8.84 g (0.0552 mol), 269 mg (0.738 mmol), and 8.70 g (0.0648 mol), respectively, and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0519] Nitrogen gas was then bubbled through the mixture for 30 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 130° C. while stirring at 500 rpm. After 2.5 hours, the flask was immersed in liquid nitrogen to completely stop the polymerization reaction.

[0520] The RAFT agent used was 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid.

[0521] Approximately 20 mL of tetrahydrofuran (THF) was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 300 mL of methanol to precipitate a powdery polymer (crude poly(4-tert-butylstyrenestyrene)). The resulting polymer was separated by suction filtration and thoroughly dried under vacuum. It was then dissolved again in THF and added dropwise to methanol to precipitate the polymer.

[0522] The polymer precipitation process was repeated three times to remove unreacted monomers and low-molecular-weight oligomers, yielding purified poly(4-tert-butylstyrene). Hereinafter, this purified poly(4-tert-butylstyrene) will also be referred to as "B-1."

[0523] Using deuterated chloroform, proton nuclear magnetic resonance spectroscopy ( １ The average degree of polymerization of B-1 was estimated by H-NMR to be 280, and the average molecular weight was about 45,000.

[0524] B-1 was dissolved in THF to prepare a solution of about 0.1% by mass, and the molecular weight distribution (Mw / Mn) was determined by gel permeation chromatography (GPC). The GPC chromatogram of B-1 is shown by the dashed line in Figure 1.

[0525] Standard polymethyl methacrylate was used for molecular weight calibration.

[0526] The eluent used was a solvent mainly composed of THF, and the flow rate was 1 mL / min, the temperature was 45°C, and the measurement was carried out using two TSK-GEL columns α-M (manufactured by Tosoh Corporation) connected together.

[0527] Step 1-2: Since B-1 obtained in the above-mentioned step 1-1 had a RAFT agent residue introduced at the molecular chain terminal, it was used as a macro RAFT agent (a RAFT agent with a large molecular weight, and therefore referred to as a "macro RAFT agent") to undergo polymerization with 4-n-butyl styrenesulfonate monomer.

[0528] The n-butyl 4-styrenesulfonate monomer was synthesized according to the literature (Bull. Chem. Soc. Jpn., 1983, 56, 762-765. and Polymer, 2002, 43, 3155-3162.).

[0529] The n-butyl 4-styrenesulfonate monomer was purified by passing it through a column packed with basic alumina.

[0530] A solution was prepared by weighing out 10.0 g (0.0417 mol), 0.229 g (0.00520 mmol), 0.2 mg (0.001 mmol), 4.3 g, and 4.7 g of purified n-butyl 4-styrenesulfonate monomer, macroRAFT agent, AIBN, toluene, and DMF, respectively, and mixing them in a round-bottom flask equipped with a stopcock.

[0531] Nitrogen gas was then bubbled through the mixture for 30 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 85°C and 500 rpm while stirring. After 4.5 hours, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0532] THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 300 mL of hexane to precipitate a crude B-nBsS diblock copolymer. The resulting polymer was separated by suction filtration and thoroughly dried under vacuum. It was then dissolved again in THF and added dropwise to hexane to precipitate the polymer.

[0533] The polymer precipitation process was repeated twice to remove unreacted monomers, low-molecular-weight oligomers, etc., to obtain a purified B-sSnB diblock copolymer. The purified B-sSnB diblock copolymer of Example 1 is also referred to as "B-sSnB-1."

[0534] B-nBsS-1 was dissolved in deuterated chloroform to prepare a solution of about 2% by mass. １ The average degree of polymerization was determined by H-NMR. １ The H-NMR spectrum shows that the average degree of polymerization of the A block component chains was 280, the average degree of polymerization of the B block component chains was 960, and the overall number average molecular weight was about 275,000.

[0535] B-nBsS-1 was dissolved in THF to prepare a solution of approximately 0.1% by mass, and then subjected to GPC measurement. The eluent was a solvent mainly composed of THF, and the flow rate was 1 mL / min, the temperature was 45°C, and the measurement was performed using two TSK-GEL columns α-M (Tosoh Corporation) connected together.

[0536] The GPC chromatogram of B-nBsS-1 is shown by the solid line in Figure 1. The peak of B-nBsS-1 was shifted to the lower elution time side, confirming the formation of a block copolymer.

[0537] (1-2) Second Step: 4.00 g (0.100 mol) of sodium hydroxide was dissolved in a mixed solvent of 67 mL of THF and 33 mL of ethanol to prepare a basic solution. Approximately 3.0 g of B-nBsS-1 obtained in the first step was dissolved in this basic solution, and a deprotection reaction by hydrolysis was carried out at 50°C for 3 hours.

[0538] The above solution was concentrated by rotary evaporation at 45° C., and 100 mL of pure water and 100 mL of approximately 35 wt % hydrochloric acid were added thereto, followed by stirring at room temperature for 12 hours to exchange the sodium ions in the polymer with protons.

[0539] To remove sodium chloride generated during protonation, the solution was transferred to a cellulose dialysis tube and dialyzed by immersing in pure water for approximately 3 hours. This dialysis was repeated three times. The dialyzed solution was dried at 100°C to obtain a polymer.

[0540] This polymer was added to 20 mL of approximately 0.1 mol / L hydrochloric acid, transferred to a cellulose dialysis tube, and dialyzed by immersing in approximately 0.1 mol / L hydrochloric acid for approximately 3 hours. This dialysis was repeated three times. The solution after dialysis was dried at 100°C to obtain a B-sSA diblock copolymer.

[0541] The B-sSA diblock copolymer obtained in Example 1 is also referred to as "B-sSA-1."

[0542] B-sSA-1 was dissolved in deuterated chloroform / deuterated methanol = 6 / 4 (volume ratio) to prepare a solution of about 2 mass %; １ H-NMR measurement was carried out.

[0543] In Figure 2, the solid line indicates B-sSA-1. １ The H-NMR spectrum shows that the signal at around δ = 4.0, which is assigned to the ester of poly(n-butyl 4-styrenesulfonate), disappeared, confirming that the hydrolysis had almost progressed.

[0544] The sharp peaks around 3.4 and 7.5 ppm are due to methanol and chloroform, respectively, and the peak around 4.9 ppm is due to residual water in the polymer.

[0545] To confirm the Tg of B-sSA-1, differential scanning calorimetry (DSC) was performed in accordance with JIS K 7121:2012. Figure 10 shows the thermogram of B-sSA-1. A small step was observed near 149°C in the DSC curve, and a small peak was observed near 149°C in the differential DSC curve, confirming the presence of a Tg at 149°C. Since the Tg of a B homopolymer is generally considered to be approximately 150°C, this Tg is thought to be derived from the B block.

[0546] (1-3) Third Step: 0.50 g of B-sSA-1 was dissolved in 5 mL of a solvent mainly composed of a THF / ethanol mixed solvent, and the solution was transferred to a polypropylene container. The solution was allowed to stand at 50°C for about 1 day to evaporate the solvent. The solution was then dried in a vacuum dryer at 50°C for about 1 day to remove the solvent, and a B-sSA-1 membrane was prepared.

[0547] (1-4) Evaluation AC Impedance Measurement Using a platinum mesh with a thickness of 0.1 mm as an electrode, AC impedance measurement was carried out on the sample of the proton-conductive electrolyte membrane of Example 1.

[0548] A sample of the proton-conductive electrolyte membrane of Example 1 cut into a strip (thickness: 0.24 mm, width: 2.25 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.159 cm.

[0549] The sample sandwiched between the electrodes was placed in a small environmental test chamber (SH-242, manufactured by Espec Corporation) and subjected to a temperature of 80°C and a relative humidity of 50% RH (partial pressure of water vapor p Ｈ２Ｏ The mixture was left standing under the condition of 237 hPa (pressure).

[0550] Using a potentio / galvanostat VERSASTAT 4-400 (manufactured by BioLogic Science Instruments), the voltage was set to 50 mV and the frequency to 10 ６Hz to 10 ０ The AC impedance was measured under humidified conditions of 50% RH while changing the temperature in the range of Hz. The resistance value at the minimum point of the Nyquist plot was read to be 3.2 × 10 ３ It was Omega.

[0551] The proton conductivity of this sample of proton-conductive electrolyte membrane was calculated using the following formula (1) and was found to be 0.057 S / cm.

[0552] Proton conductivity = electrode distance / (membrane thickness × electrode width × resistance at the minimum point of the Nyquist plot) (1)

[0553] Next, the measurement conditions were changed to a temperature of 80°C and a relative humidity of 60% RH (p Ｈ２Ｏ The resistance at the minimum point of the Nyquist plot was 1.7 × 10 ３ The proton conductivity was 0.11 S / cm at Ω, which was very high.

[0554] Next, the measurement conditions were changed to a temperature of 80°C and a relative humidity of 70% RH (p Ｈ２Ｏ The resistance at the minimum point of the Nyquist plot was 8.1 × 10 ２ The proton conductivity was 0.23 S / cm at Ω, which was very high.

[0555] Next, the measurement conditions were changed to a temperature of 80°C and a relative humidity of 80% RH (p Ｈ２Ｏ The resistance at the minimum point of the Nyquist plot was 4.0 × 10 ２ The proton conductivity was 0.46 S / cm at Ω, which was very high.

[0556] Similarly, a sample of the proton-conductive electrolyte membrane of Example 1 cut into a strip (thickness: 0.48 mm, width: 2.15 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.159 cm, and the sample was heated at a temperature of 95° C. and a relative humidity of 50% RH (pＨ２Ｏ When AC impedance measurement was performed under the condition of σ = 423 hPa, the resistance value at the minimum point of the Nyquist plot was 1.3 × 10 ３ The proton conductivity was 0.071 S / cm at Ω, indicating high proton conductivity.

[0557] Next, the measurement conditions were changed to a temperature of 95°C and a relative humidity of 60% RH (p Ｈ２Ｏ = 508 hPa), temperature 95°C, relative humidity 70% RH (p Ｈ２Ｏ = 592 hPa), temperature 95°C, relative humidity 80% RH (p Ｈ２Ｏ When AC impedance measurements were performed under different conditions (pressure, pressure, and pressure), the resistance at the minimum point of the Nyquist plot under each condition was 6.5 × 10 ２ Ω, 3.1 x 10 ２ Ω, 1.7 x 10 ２ The proton conductivities at Ω were 0.14 S / cm, 0.30 S / cm, and 0.53 S / cm, respectively, which showed very high proton conductivities.

[0558] The measurement results of the proton conductivity of Example 1 at 80° C. and 95° C. are shown by black circles (●) in FIGS. 3 and 4, respectively, and are summarized in Table 1.

[0559] As described above, the proton conductivity of the proton conductive membrane of Example 1 tended to increase with increasing humidity. This is thought to be because the water content in the sSA block increased with increasing humidity, making it easier for the protons of the sulfonic acid groups to migrate along the water molecules.

[0560] [2] Comparative Example 1 In Comparative Example 1, a Nafion membrane (registered trademark, NR212, Aldrich) was used, and AC impedance measurement was carried out in the same manner as in Example 1, and the proton conductivity was measured.

[0561] The measurement results of the proton conductivity of Comparative Example 1 at 80° C. and 95° C. are shown by cross marks (x) in FIGS. 3 and 4, respectively, and are summarized in Table 1.

[0562] For example, the membrane of Comparative Example 1 exhibited a proton conductivity of 0.061 S / cm at 80° C. and 80% RH, and 0.049 S / cm at 95° C. and 80% RH.

[0563] It can be seen that the B-sSA-1 membrane of Example 1 exhibits higher proton conductivity than the Nafion membrane of Comparative Example 1. This is thought to be because in the Nafion membrane, sulfonic acid groups are randomly present in the polymer chain and have a low density (equivalent mass EW=1100, which indicates the ion exchange capacity), whereas in the B-sSA-1 membrane, sulfonic acid groups are contained more densely in the sSA block (EW=184 in the sSA block), making it more susceptible to moisture absorption.

[0564] Furthermore, the NR212 membrane was sandwiched between electrodes and dried for at least 1 hour at a temperature of 125°C and a relative humidity of essentially 0% RH. The proton conductivity was determined by AC impedance measurement under non-humidified conditions, and showed a low conductivity of 0.00014 S / cm.

[0565] [3] Example 2 In Example 2, a B-nBsS diblock copolymer (degree of polymerization of B block: 291, degree of polymerization of nBsS block: 690, number average molecular weight: 210,000; hereinafter referred to as "B-nBsS-2") was synthesized in the same manner as in Example 1, except that the amounts of 4-tert-butylstyrene monomer and 4-n-butylstyrenesulfonate monomer were appropriately changed. This was then hydrolyzed in the same manner as in Example 1 to synthesize a B-sSA diblock copolymer (hereinafter referred to as "B-sSA-2"), and a B-sSA-2 membrane was prepared.

[0566] B-nBsS-2 and B-sSA-2 １ The H-NMR spectra are shown in FIG. 5 by the dotted line and the solid line, respectively.

[0567] In the spectrum of B-sSA-2, the sharp peaks near 3.4 and 7.5 ppm are due to methanol and chloroform, respectively, the peaks near 1.9 and 3.8 ppm are due to residual THF in the polymer, the peak near 3.6 ppm is due to residual ethanol in the polymer, and the peak near 4.9 ppm is due to residual water in the polymer.

[0568] The GPC chromatograms of B-nBsS-2 and its precursor poly(4-tert-butylstyrene) (hereinafter referred to as "B-2") are shown in FIG. 6 by the solid line and the dashed line, respectively.

[0569] The peak of B-nBsS-2 was shifted to the lower elution time side, confirming that a block copolymer had been synthesized.

[0570] The proton conductivity of the B-sSA-2 membrane was measured by AC impedance measurement in the same manner as in Example 1. The proton conductivity measurement results for Example 2 at 80°C and 95°C are shown by gray triangles (▲) in Figures 3 and 4, respectively, and are summarized in Table 1.

[0571] The membrane of Example 2 exhibited a proton conductivity of 0.45 S / cm at 80°C and 80% RH and 0.41 S / cm at 95°C and 80% RH, for example, and it was found that the B-sSA-2 membrane of Example 2 exhibited a higher proton conductivity than the Nafion membrane of Comparative Example 1.

[0572] This is thought to be because in the Nafion membrane, sulfonic acid groups are randomly distributed in the polymer chain and their density is low, whereas in the B-sSA-2 membrane, sulfonic acid groups are contained in the sSA block at a higher density, making it more susceptible to moisture absorption.

[0573] [4] Example 3 In Example 3, a proton conductive membrane of Example 3 (hereinafter also referred to as "B-3 / B-sSA-1 membrane") was fabricated by mixing a homopolymer of poly(4-tert-butylstyrene) (hereinafter also referred to as "B-3") and the B-sSA-1 synthesized in Example 1.

[0574] 0.0098 g of B-3 (number average molecular weight 832,400, Mw / Mn = 1.40, manufactured by Polymer Source Inc.) and 0.039 g of B-sSA-1 were dissolved in 10.0 g of a mixed solvent of THF / methanol = 2 / 1 (weight ratio), and the solvent was evaporated by rotary evaporation. The mixture was vacuum dried at 50 ° C for approximately 4 hours, and the resulting mixture was hot-pressed at 180 ° C for approximately 30 seconds. This hot-pressing was repeated five times to prepare a B-3 / B-sSA-1 membrane (weight ratio 2 / 8).

[0575] The proton conductivity of the B-3 / B-sSA-1 membrane (weight ratio 2 / 8) was measured by AC impedance measurement in the same manner as in Example 1. The proton conductivity measurement results of Example 3 at 80°C and 95°C are shown by black squares (■) in Figures 3 and 4, respectively, and are summarized in Table 1.

[0576] For example, the membrane of Example 3 exhibited a proton conductivity of 0.19 S / cm at 80°C and 80% RH and 0.19 S / cm at 95°C and 80% RH. It was also found that the B-sSA-2 membrane of Example 2 exhibited a higher proton conductivity than the Nafion membrane of Comparative Example 1.

[0577] [5] Example 4 In Example 4, a B-3 / B-sSA-1 membrane with a weight ratio of 3 / 7 was prepared in the same manner as in Example 3, and sulfuric acid (H ２ SO ４ ) was introduced to prepare a proton-conducting electrolyte membrane.

[0578] A solution of 0.0555 g of concentrated sulfuric acid (97%) dissolved in 2.08 g of methanol was poured into a polypropylene container, and 0.0801 g of the above B-3 / B-sSA-1 membrane was immersed in the solution. The solution was then left to stand at 50°C for about 1 day to evaporate the volatile solvent (methanol).

[0579] Thereafter, the volatile solvent was removed by drying at 50°C for about 1 day using a vacuum dryer, and the B-3 / B-sSA-1 membrane was then dried. ２ SO ４ B-3 / B-sSA-1 / H ２ SO ４ A film was obtained. ２ SO ４ is thought to penetrate only the sSA component of B-sSA-1.

[0580] Here, B-3, B-sSA-1 and H in the proton-conducting electrolyte membrane of Example 4 ２ SO ４ The weight ratio of these was 18:42:40, and the molar ratio of sulfuric acid to sulfonic acid groups was 2.2.

[0581] AC impedance measurement: B-3 / B-sSA-1 / H as in Example 1 ２SO ４ The membrane was sandwiched between electrodes, and the sample was placed in a small environmental test chamber and dried for at least 1 hour under conditions of a temperature of 125°C and a relative humidity of substantially 0% RH. The proton conductivity was determined by AC impedance measurement under non-humidified conditions, and was found to be 0.056 S / cm, which was a much higher value than the conductivity of the Nafion membrane of Comparative Example 1 under non-humidified conditions (Table 2).

[0582] Tensile Test A tensile test was carried out on the proton-conductive electrolyte membrane of Example 4. A strip-shaped test piece having a length of 20 mm and a width of 3 mm was prepared from the proton-conductive electrolyte membrane of Example 4. The thickness of the test piece was 0.30 mm.

[0583] A tensile test was carried out using an ARES-G2 manufactured by TA Instruments as a measuring device at 125° C., with a jig distance of 5.95 mm and an initial strain rate of 0.1 / s (tensile rate of 0.595 mm / s).

[0584] The stress-strain curve resulting from the tensile test is shown by the solid line in Figure 7. The Young's modulus, tensile strength, breaking elongation, and inner area value of the stress-strain curve (an index of the toughness of the material) were 12 MPa, 1.1 MPa, 20%, and 0.11 MJ / m, respectively. ３ The Young's modulus was determined from the initial gradient of the stress-strain curve (within 3% strain).

[0585] [6] Comparative Example 2 In Comparative Example 2, poly(4-tert-butylstyrene)-b-poly(2-vinylpyridine) (hereinafter also referred to as "B-2VP diblock copolymer") was synthesized as a block copolymer using a 2-vinylpyridine monomer having a basic functional group instead of an acidic functional group, and a B-3 / B-2VP membrane with a weight ratio of 3 / 7 was prepared in the same manner as in Example 4. ２ SO ４ By introducing the above, a proton-conducting electrolyte membrane was fabricated.

[0586] A B-2VP diblock copolymer (degree of polymerization of B block: 255, degree of polymerization of 2VP block: 1950, number average molecular weight: 250,000) was synthesized in the same manner as in Example 1, except that the amount of 4-tert-butylstyrene monomer was appropriately changed and 2-vinylpyridine monomer was used instead of 4-n-butylstyrenesulfonate monomer.

[0587] B-3, B-2VP and H in the proton-conducting electrolyte membrane of Comparative Example 2 ２ SO ４ The weight ratio of the pyridyl groups was 14:34:52, and the molar ratio of sulfuric acid to pyridyl groups was 2.0. The proton conductivity was measured under conditions of a temperature of 125°C and a relative humidity of substantially 0% RH, and was found to be 0.022 S / cm. ２ SO ４ The proton-conductive electrolyte membrane of Example 6, which contained a smaller amount of PEG, exhibited higher conductivity than the proton-conductive electrolyte membrane of Comparative Example 2.

[0588] In Comparative Example 2, the basic functional group (proton-accepting functional group) and the equimolar amount of H ２ SO ４ The molecule is consumed in the formation of an ionic complex, and the basic functional group and the equimolar amount of H ２ SO ４ Although free protons that contribute to proton conduction are not released from the molecules, the membrane of Example 6 does not have a basic functional group, so almost all of the permeated H ２ SO ４ It is believed that the molecules exhibited high conductivity because they could release free protons that participate in proton transport.

[0589] [7] Comparative Example 3 In Comparative Example 3, poly(4-tert-butylstyrene)-b-poly(2-vinylpyridine)-b-poly(4-tert-butylstyrene) (hereinafter also referred to as "B-2VP-B triblock copolymer") was synthesized as a block copolymer, and H ２ SO ４ By introducing the above, a proton-conducting electrolyte membrane was fabricated.

[0590] A B-2VP-B triblock copolymer (degree of polymerization of the B block combined at both ends: 486, degree of polymerization of the 2VP block: 970, number average molecular weight: 180,000) was synthesized in the same manner as in Comparative Example 2, except that the amounts of 4-tert-butylstyrene monomer and 2-vinylpyridine monomer were appropriately changed and a bifunctional RAFT agent was used.

[0591] B-2VP-B and H in the proton-conducting electrolyte membrane of Comparative Example 3 ２ SO ４ The weight ratio of these groups was 30:70, and the molar ratio of sulfuric acid to pyridyl groups was 4.4. The proton conductivity was measured at a temperature of 125° C. and a relative humidity of substantially 0% RH, and was found to be 0.091 S / cm.

[0592] A tensile test was carried out in the same manner as in Example 4. The stress-strain curve resulting from the tensile test is shown by the dotted line in Figure 7. The Young's modulus, tensile strength, elongation at break, and inner area of ​​the stress-strain curve were 1.9 MPa, 0.10 MPa, 5%, and 5.6 × 10, respectively. -４ MJ / m ３ It was.

[0593] The reason why the membrane of Example 4 exhibited a higher tensile strength than the membrane of Comparative Example 3 is thought to be that the B homopolymer, which is in a glassy state at the temperature and humidity conditions in which the proton-conductive electrolyte membrane is used, is the same component as the B block in the B-sSA, which contributes to the development of the mechanical strength of the membrane, and therefore the B homopolymer and the B block in the B-sSA are moderately compatible with each other, and the B homopolymer has a high molecular weight and is relatively strong, which contributed to improving the mechanical strength of the membrane.

[0594] [8] Example 5 In Example 5, the B-3 / B-sSA-1 membrane (weight ratio 2 / 8) of Example 3 was subjected to H ２ SO ４ Instead of phosphoric acid (H ３ P.O. ４ The same procedure as in Example 4 was repeated except that B-3 / B-sSA-1 / H was introduced into the membrane. ３ P.O. ４ A membrane was prepared.

[0595] B-3, B-sSA-1 and H ２ SO ４The weight ratio of the sulfonic acid groups to the phosphoric acid groups was 6:24:70, and the molar ratio of the phosphoric acid groups to the sulfonic acid groups was 6.9. The proton conductivity was measured at a temperature of 125°C and a relative humidity of substantially 0% RH, and was 0.10 S / cm, which was higher than that of the Nafion membrane of Comparative Example 1, even though the membrane was not humidified (Table 2).

[0596] [9] Example 6 In Example 6, B-3, B-sSA-1 and H ２ SO ４ A proton-conductive electrolyte membrane was prepared in the same manner as in Example 4, except that the weight ratio of sulfuric acid to sulfonic acid groups was 14:34:52. The molar ratio of sulfuric acid to sulfonic acid groups was 3.6.

[0597] The proton conductivity was measured at a temperature of 125°C and a relative humidity of substantially 0% RH, and was found to be 0.079 S / cm, which was higher than that of the Nafion membrane of Comparative Example 1, despite being unhumidified (Table 2).

[0598]

[10] Example 7 In Example 7, B-3, B-sSA-1 and H ２ SO ４ A proton-conductive electrolyte membrane was prepared in the same manner as in Example 4, except that the weight ratio of sulfuric acid to sulfonic acid groups was 12:28:60. The molar ratio of sulfuric acid to sulfonic acid groups was 5.0.

[0599] The proton conductivity was measured at a temperature of 125°C and a relative humidity of substantially 0% RH, and was found to be 0.094 S / cm, which was higher than that of the Nafion membrane of Comparative Example 1, despite being unhumidified (Table 2).

[0600]

[11] Comparative Example 4 In Comparative Example 4, B-3, B-2VP and H ２ SO ４ A proton-conductive electrolyte membrane was prepared in the same manner as in Example 4, except that the weight ratio of the above was 18:42:40. The molar ratio of sulfuric acid to pyridyl groups was 1.3.

[0601] The proton conductivity was measured under conditions of a temperature of 125°C and a relative humidity of substantially 0% RH, and was found to be 0.00093 S / cm. ２ SO ４The proton-conductive electrolyte membrane of Example 4, which had a similar content, exhibited higher conductivity than the proton-conductive electrolyte membrane of Comparative Example 4.

[0602] In Comparative Example 4, the basic functional group (proton-accepting functional group) and the equimolar amount of H ２ SO ４ The molecule is consumed in the formation of an ionic complex, and the basic functional group and the equimolar amount of H ２ SO ４ Although free protons that contribute to proton conduction are not released from the molecules, the membrane of Example 4 does not have a basic functional group, so almost all of the permeated H ２ SO ４ It is believed that the high conductivity was due to the release of free protons that are involved in the proton transport of the molecules.

[0603]

[12] Comparative Example 5 In Comparative Example 5, B-3, B-2VP and H ２ SO ４ A proton-conductive electrolyte membrane was prepared in the same manner as in Example 4, except that the weight ratio of sulfuric acid to sulfonic acid groups was 12:28:60. The molar ratio of sulfuric acid to sulfonic acid groups was 2.8.

[0604] The proton conductivity was measured under conditions of a temperature of 125°C and a relative humidity of substantially 0% RH, and was found to be 0.040 S / cm. ２ SO ４ The proton-conductive electrolyte membrane of Example 7, which had a similar content, exhibited higher conductivity than the proton-conductive electrolyte membrane of Comparative Example 5.

[0605] In Comparative Example 5, the basic functional group (proton-accepting functional group) and the equimolar amount of H ２ SO ４ The molecule is consumed in the formation of an ionic complex, and the basic functional group and the equimolar amount of H ２ SO ４ Although free protons that contribute to proton conduction are not released from the molecules, the membrane of Example 7 does not have a basic functional group, so almost all of the permeated H ２ SO ４ It is believed that the high conductivity was due to the release of free protons that are involved in the proton transport of the molecules.

[0606]

[13] Example 8 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 8 In Example 8, poly(4-tert-butylstyrene)-b-poly(diethyl 4-styrenephosphonate) (hereinafter also referred to as "B-EsP diblock copolymer") was synthesized as a block copolymer according to the following Scheme 2 (first step).

[0607] Next, the alkyl protecting groups of the poly(diethyl 4-styrenephosphonate) block were deprotected to synthesize poly(4-tert-butylstyrene)-b-poly(4-styrenephosphonic acid) (hereinafter also referred to as "B-sPA-1 diblock copolymer") having a proton-donating group (second step).

[0608] This B-sPA-1 diblock copolymer was formed into a membrane to produce the proton conductive membrane of Example 8 (hereinafter also referred to as "B-sPA-1 membrane") (third step).

[0609]

[0610] In the literature (Org. Lett. 2011, 13(8), 2110-2113.), 4-diethyl styrenephosphonate monomer is synthesized by reacting p-styrylboronic acid with diethyl phosphite in the presence of 1,10-phenanthroline and copper(I) oxide as a catalyst. 4-Diethyl styrenephosphonate monomer was synthesized in a similar manner to this reaction.

[0611] (1-1) First Step In Example 8, a B-EsP diblock copolymer (degree of polymerization of the B block: 255, degree of polymerization of the EsP block: 1,260, number average molecular weight: 340,000) was synthesized in the same manner as in Example 1, except that the amount of 4-tert-butylstyrene monomer in Step 1-1 and the amount of 4-diethylstyrenephosphonate monomer were appropriately changed instead of n-butyl 4-styrenesulfonate monomer in Step 1-2.

[0612] The GPC chromatograms of B-EsP and its precursor poly(4-tert-butylstyrene) (hereinafter referred to as "B-4") are shown in FIG. 8 by the solid line and the dashed line, respectively.

[0613] The peak of B-EsP was shifted to the lower elution time side, confirming that a block copolymer had been synthesized. Mw / Mn was 2.3.

[0614] The 1H-NMR spectra of B-4 and B-EsP are shown in FIG. 9 by the dotted line and dashed line, respectively.

[0615] (1-2) Second Step In a literature study (Macromolecules, 2018, 51, 1120-1128), poly(diethyl 4-styrenephosphonate) was reacted with bromotrimethylsilane and then dialyzed using a methanol solvent to deprotect the alkyl groups of poly(diethyl 4-styrenephosphonate) and synthesize poly(4-styrenephosphonic acid) without an alkyl spacer. Based on this reaction, the B-EsP obtained in the first step was reacted with bromotrimethylsilane and then dialyzed using water instead of methanol to carry out the deprotection reaction.

[0616] Specifically, 0.855 g of B-EsP (phosphonic acid diester: 3.1 mmol) was dissolved in 5.0 mL of chloroform, 2.5 mL of bromotrimethylsilane (2.9 g, 0.019 mol) was added, and the mixture was placed in an oil bath at 40° C. and stirred for 19 hours.

[0617] This solution was concentrated by rotary evaporation and then mixed with approximately 5 mL of pure water. The mixture was transferred to a cellulose dialysis tube and dialyzed by immersing it in pure water for approximately 3 hours. This dialysis was repeated three times. The contents of the cellulose tube were removed and dried at 100°C to obtain B-sPA-1.

[0618] B-sPA-1 was dissolved in deuterated THF / heavy water (volume ratio: 5 / 5) to prepare a solution of approximately 2% by mass, and 1H-NMR measurement was performed. The 1H-NMR spectrum of B-sPA is shown by the solid line in Figure 9.

[0619] The peak at around 4.1 ppm, which is derived from the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester, disappeared, and the peak at around 1.2 ppm, which is derived from the proton of the adjacent methyl group, became smaller, confirming that the deprotection had almost progressed.

[0620] The sharp peak near 4.0 ppm is a peak derived from water, and the peaks near 1.8 and 3.7 ppm are peaks derived from THF.

[0621] To confirm the Tg of B-sPA-1, DSC was performed in accordance with JIS K 7121:2012. The thermogram of B-sPA-1 is shown in Figure 10. A small step was observed near 155°C on the DSC curve, and a small peak was observed near 155°C on the differential DSC curve, confirming that the Tg was at 155°C.

[0622] (1-3) Third Step 0.100 g of B-sPA-1 was dispersed in 4.2 g of a solvent mainly composed of a 1-propanol / water mixed solvent, and the dispersion was allowed to stand at 60°C for about 12 hours to evaporate the solvent, thereby preparing the proton-conducting electrolyte membrane of Example 8.

[0623] (1-4) Evaluation AC Impedance Measurement AC impedance measurement was performed in the same manner as in Example 1 to measure the proton conductivity of the B-sPA-1 membrane. The proton conductivity was 0.00066 S / cm at 80°C and 80% RH, 0.00089 S / cm at 95°C and 80% RH, and 0.0080 S / cm at 95°C and 98% RH.

[0624]

[14] Example 9 In Example 9, a B-nBsS diblock copolymer was synthesized in the same manner as in Example 1, except that the amounts of the 4-tert-butylstyrene monomer and the 4-n-butyl styrenesulfonate monomer were appropriately changed. This was then hydrolyzed in the same manner as in Example 1 to synthesize a B-sSA diblock copolymer (degree of polymerization of the B block: 255, degree of polymerization of the sSA block: 3,474, number average molecular weight: 680,000; hereinafter, referred to as B-sSA-3).

[0625] The proton conductivity of the B-sSA-3 membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 9 at 80° C. are summarized in Table 1.

[0626] The membrane of Example 9 exhibited a proton conductivity of 1.4 S / cm at 80°C and 80% RH and 0.13 S / cm at 80°C and 40% RH, for example, and it was found that the B-sSA-3 membrane of Example 9 exhibited a higher proton conductivity than the Nafion membrane of Comparative Example 1.

[0627] This is thought to be because in the Nafion membrane, sulfonic acid groups are randomly distributed in the polymer chain and their density is low, whereas in the B-sSA-3 membrane, sulfonic acid groups are contained in the sSA block at a higher density, making it more susceptible to moisture absorption.

[0628]

[15] Example 10 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 10 In Example 10, poly(4-tert-butylstyrene)-b-poly(butyl 4-styrenesulfonate-co-diethyl 4-styrenephosphonate) (hereinafter also referred to as "B-(nBsS-co-EsP) diblock copolymer") was synthesized as a block copolymer according to the following Scheme 3 (first step).

[0629] Next, the alkyl protecting groups of the poly(butyl 4-styrenesulfonate-co-diethyl 4-styrenephosphonate) block were deprotected to synthesize poly(4-tert-butylstyrene)-b-poly(4-styrenesulfonic acid-co-4-styrenephosphonic acid) having a proton-donating group (hereinafter also referred to as "B-(sSA-co-sPA) diblock copolymer"; degree of polymerization of the B block: 525, degree of polymerization of the sSA component in the sSA-co-sPA block: 1265, degree of polymerization of the sPA component in the sSA-co-sPA block: 597, number average molecular weight: 430,000) (second step).

[0630] This B-(sSA-co-sPA) diblock copolymer was formed into a membrane to prepare the proton conductive membrane of Example 10 (hereinafter also referred to as "B-(sSA-co-sPA)-1 membrane") (third step).

[0631]

[0632] (1-1) First Step In Example 10, a B-(nBsS-co-EsP)-1 diblock copolymer was synthesized in the same manner as in Example 1, except that in Step 1-1, the amount of 4-tert-butylstyrene monomer was changed, and in Step 1-2, the 4-diethylstyrenephosphonate monomer synthesized in Example 8 was randomly copolymerized in addition to the n-butyl 4-styrenesulfonate monomer.

[0633] The 1H-NMR spectra of B-5 and B-(nBsS-co-EsP)-1 are shown in FIG. 11 by the dotted line and dashed line, respectively.

[0634] (1-2) Second Step In the same manner as in the second step of Example 8, B-(nBsS-co-EsP)-1 was reacted with bromotrimethylsilane, and then the reaction mixture was dialyzed against water to deprotect the alkyl groups of the poly(butyl 4-styrenesulfonate-co-diethyl 4-styrenephosphonate) block, thereby obtaining B-(sSA-co-sPA)-1.

[0635] B-(sSA-co-sPA)-1 was dissolved in a 5 / 5 volume ratio of deuterated THF / heavy water to prepare a solution of approximately 2% by mass, and 1H-NMR measurement was performed. The 1H-NMR spectrum of B-(sSA-co-sPA)-1 is shown by the solid line in Figure 11.

[0636] The peaks at around 4.1 ppm resulting from the protons of the methylene groups adjacent to the oxygen atoms of the sulfonate ester and phosphonate diester became smaller and disappeared, and it was confirmed from the integral ratio that the deprotection had progressed by 92%.

[0637] The sharp peak near 4.7 ppm is a peak derived from water.

[0638] (1-3) Third Step: 0.050 g of B-(sSA-co-sPA)-1 was dispersed in 1.67 g of a solvent mainly composed of a 1-propanol / water mixed solvent, and the dispersion was allowed to stand at 60°C for about 12 hours to evaporate the solvent, thereby preparing the proton-conducting electrolyte membrane of Example 10.

[0639] (1-4) Evaluation: AC Impedance Measurement AC impedance measurement was performed in the same manner as in Example 1 to measure the proton conductivity of the B-(sSA-co-sPA)-1 membrane. The membrane showed a proton conductivity of 0.14 S / cm at 80°C and 80% RH and 0.0092 S / cm at 80°C and 40% RH.

[0640]

[16] Example 11 In Example 11, a B-(nBsS-co-EsP) diblock copolymer was synthesized in the same manner as in Example 10, except that the amounts of 4-tert-butylstyrene monomer, n-butyl 4-styrenesulfonate monomer, and diethyl 4-styrenephosphonate monomer were appropriately changed. This diblock copolymer was then hydrolyzed in the same manner as in Example 10 to synthesize a B-(sSA-co-sPA) diblock copolymer (degree of polymerization of the B block: 480; degree of polymerization of the sSA component in the sSA-co-sPA block: 465; degree of polymerization of the sPA component in the sSA-co-sPA block: 555; number-average molecular weight: 260,000; hereinafter, also referred to as "B-(sSA-co-sPA)-2").

[0641] The proton conductivity of the B-(sSA-co-sPA)-2 membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 11 at 80° C. are summarized in Table 1.

[0642] The membrane of Example 11 exhibited, for example, a proton conductivity of 0.080 S / cm at 80° C. and 80% RH, and 0.00084 S / cm at 80° C. and 40% RH.

[0643]

[17] Example 12 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 12 In Example 12, a crosslinked poly(n-butyl 4-styrenesulfonate) membrane (hereinafter also referred to as "CL-nBsS membrane") was synthesized according to the following Scheme 4 (first step).

[0644] Next, the ester protecting groups in the poly(n-butylstyrenesulfonate) were deprotected by hydrolysis to prepare a crosslinked poly(4-styrenesulfonic acid) membrane having proton-donating groups (hereinafter also referred to as a "CL-sSA membrane") (second step).

[0645] In the term "CL-sSA," "CL-" is an abbreviation for chemically crosslinked polymer.

[0646] In the term "CL-sSA," "sSA" is an abbreviation for poly(4-styrenesulfonic acid), which is a polymer having a proton-donating group.

[0647]

[0648] (1-1) First Step: AIBN, divinylbenzene, 4-styrenesulfonate n-butyl monomer synthesized in the same manner as in Example 1, and dimethyl sulfoxide (DMSO) were weighed out in amounts of 0.0050 g (0.03 mmol), 0.021 g (0.13 mmol), 3.0 g (13 mmol), and 2.0 g, respectively, to prepare a homogeneous solution. Here, the molar ratio of 4-styrenesulfonate n-butyl monomer to divinylbenzene was 99:1. The resulting solution was transferred to a sealable glass container, bubbled with nitrogen gas for 30 minutes, and then placed in an oil bath at 75°C under atmospheric pressure to allow polymerization for 20 hours. The resulting membrane was immersed in THF multiple times to remove unreacted monomers and uncrosslinked oligomers, yielding a CL-nBsS membrane.

[0649] A part of the CL-nBsS membrane was crushed into powder, and the powder was swollen with deuterated DMSO. １ H-NMR measurement was performed. １ The H-NMR spectrum is shown.

[0650] 2.65 g (0.011 mol in monomer units) of the CL-nBsS membrane was swollen with 44 g of DMSO and mixed with 78.6 g (0.11 mol) of a 37% methanol solution of tetrabutylammonium hydroxide. The mixture was heated to 50°C for one day to carry out a deprotection reaction by hydrolysis. The membrane sample after the deprotection reaction was collected and immersed in pure water to remove excess tetrabutylammonium hydroxide. The membrane was protonated by immersing it in approximately 200 mL of 1 M hydrochloric acid for 24 hours, and then immersed in pure water to wash, preparing a CL-sSA membrane.

[0651] A part of the CL-sSA membrane was crushed into powder, and the powder was swollen with deuterated DMSO. １ H-NMR measurement was performed. The solid line in the lower part of Figure 12 shows the １ The H-NMR spectrum is shown. The four signals attributed to the n-butyl sulfonate group seen in CL-nBsS have almost disappeared, indicating that the deprotection reaction has progressed. When compared with the integral ratio of CL-nBsS, the progress rate of the deprotection reaction was approximately 99%.

[0652] (1-3) Evaluation The proton conductivity of the CL-sSA membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 12 at 80° C. are summarized in Table 1.

[0653] For example, the membrane of Example 12 exhibited a proton conductivity of 0.58 S / cm at 80°C and 90% RH and 0.33 S / cm at 80°C and 80% RH. It was also found that the CL-sSA membrane of Example 9 exhibited a higher proton conductivity than the Nafion membrane of Comparative Example 1.

[0654]

[18] Example 13 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 13 In Example 13, a crosslinked poly(diethyl 4-styrenephosphonate) membrane (hereinafter also referred to as "CL-EsP membrane") was synthesized according to the following Scheme 5 (first step).

[0655] Next, the ester protecting groups in the poly(diethylstyrenephosphonate) were deprotected by hydrolysis to prepare a crosslinked poly(4-styrenephosphonic acid) membrane having proton-donating groups (hereinafter also referred to as a "CL-sPA membrane") (second step).

[0656] In the term "CL-sPA," "CL-" is an abbreviation for chemically crosslinked polymer.

[0657] In the term "CL-sPA," "sPA" is an abbreviation for poly(4-styrenephosphonic acid), which is a polymer having a proton-donating group.

[0658]

[0659] (1-1) First Step: A CL-EsP membrane was obtained by copolymerizing 4-styrenephosphonic acid diethyl monomer and divinylbenzene in the same manner as in Example 12, except that the 4-styrenephosphonic acid diethyl monomer was synthesized in the same manner as in Example 8. The molar ratio of the 4-styrenephosphonic acid diethyl monomer to divinylbenzene used was 98:2.

[0660] A portion of the CL-EsP membrane was crushed into powder, and the powder was swollen with deuterated DMSO. １ H-NMR measurement was performed. １ The H-NMR spectrum is shown.

[0661] 0.581 g (2.42 mmol in monomer units) of the CL-EsP film was swollen with 18.8 g of dehydrated chloroform, 1.8 mL (2.2 g, 0.014 mol) of bromotrimethylsilane was added, and the mixture was placed in a 40°C oil bath and stirred for approximately 12 hours.

[0662] After the reaction, the membrane sample was collected and immersed in methanol for about 12 hours to carry out hydrolysis, and excess bromotrimethylsilane and by-products were removed to prepare a CL-sPA membrane.

[0663] A part of the CL-sPA membrane was crushed into powder, and the powder was swollen with deuterated DMSO. １ H-NMR measurement was performed. １ The H-NMR spectrum is shown. The signals attributed to the diethyl phosphonate group seen in CL-EsP have almost disappeared, indicating that the deprotection reaction has progressed. When compared with the integral ratio of CL-EsP, the progress rate of the deprotection reaction was approximately 98%.

[0664] (1-3) Evaluation The proton conductivity of the CL-sPA membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 13 at 80° C. are summarized in Table 1.

[0665] For example, the membrane of Example 13 exhibited a proton conductivity of 0.012 S / cm at 80° C. and 80% RH, and 0.0045 S / cm at 80° C. and 60% RH.

[0666]

[19] Example 14 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 14 In Example 14, first, poly(4-bromostyrene)-b-poly(4-tert-butylstyrene) (hereinafter also referred to as “Brs-B diblock copolymer”) was synthesized as a block copolymer according to the following Scheme 6 (first step).

[0667] Next, a graft polymer (hereinafter also referred to as "(Brs-g-EvP)-B") in which polyvinyl diethyl phosphonate was attached as a branch chain to the Brs block of the Brs-B diblock copolymer was synthesized (second step).

[0668] Next, the ester protecting groups in the branched polyvinylphosphonic acid diethyl were deprotected by hydrolysis to synthesize a graft polymer (hereinafter also referred to as "(Brs-g-vPA)-B") in which polyvinylphosphonic acid was grown as a branched chain on the Brs block of a Brs-B diblock copolymer having a proton-donating group (third step).

[0669] This (Brs-g-vPA)-B was formed into a membrane to prepare the proton conductive membrane of Example 11 (hereinafter also referred to as "(Brs-g-vPA)-B membrane") (fourth step).

[0670]

[0671] (1-1) First Step Step 1-1 Commercially available 4-bromostyrene was passed through a column packed with basic alumina to purify the 4-bromostyrene monomer.

[0672] The purified 4-bromostyrene monomer, RAFT agent, and azobisisobutyronitrile (AIBN) were weighed out in amounts of 6.00 g (0.037 mol), 68.0 mg (0.19 mmol), and 3.0 mg (0.019 mmol), respectively, and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0673] Nitrogen gas was then bubbled through the mixture for 20 minutes, and polymerization was carried out at normal pressure using an oil bath at 90° C. while stirring at 500 rpm. After 4 hours, the flask was immersed in liquid nitrogen to completely stop the polymerization reaction.

[0674] The RAFT agent used was 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid.

[0675] Approximately 40 mL of THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 300 mL of n-hexane to precipitate a powdery polymer (crude poly(4-bromostyrene)). The resulting polymer was separated by suction filtration and thoroughly dried under vacuum. It was then dissolved again in THF and added dropwise to methanol to precipitate the polymer.

[0676] The polymer precipitation process was repeated three times to remove unreacted monomers and low-molecular-weight oligomers, yielding purified poly(4-bromostyrene). Hereinafter, this purified poly(4-bromostyrene) will also be referred to as "Brs."

[0677] Using deuterated chloroform, １ The average degree of polymerization of Brs was estimated by H-NMR (FIG. 14a), and the average degree of polymerization was 100, and the average molecular weight was approximately 18,000.

[0678] Brs was dissolved in THF to prepare a solution of about 0.1% by mass, and the molecular weight distribution (Mw / Mn) was determined by GPC. The GPC chromatogram of Brs is shown by the dotted line in Figure 15. The Mw / Mn of Brs was 1.1.

[0679] Step 1-2: Polymerization was carried out in the same manner as in Step 1-1 of Example 1, except that the Brs macro-RAFT obtained in the above-mentioned Step 1-1 was used as the RAFT agent and the amount of 4-tert-butylstyrene monomer was appropriately changed, to obtain a Brs-B diblock copolymer.

[0680] Brs-B is dissolved in deuterated chloroform to prepare a solution of about 2% by mass, １ The average degree of polymerization was determined by H-NMR. １ The H-NMR spectrum shows that the average degree of polymerization of the Brs block was 100, the average degree of polymerization of the B block was 468, and the overall number average molecular weight was about 93,000.

[0681] GPC measurement of Brs-B was carried out. The GPC chromatogram of Brs-B is shown by the dashed line in FIG.

[0682] The Brs-B peak was shifted toward the lower elution time side of B compared with the Brs peak, confirming that a block copolymer had been synthesized. Mw / Mn was 1.5.

[0683] (1-2) Second Step: 1.0 g of Brs-B (bromo groups in the polymer: 1.2 mmol) was weighed out and placed in a round-bottom flask equipped with a stopcock. The gas in the flask was replaced with nitrogen. Approximately 500 g of dehydrated THF was added to prepare a solution, and the flask was placed in a cooling bath and cooled to approximately -78°C. 1.5 mL (2.4 mmol) of an n-hexane solution of n-butyllithium (concentration: 1.59 mol / L) was added and stirred for approximately 15 minutes. The temperature was raised to approximately -40°C, and 6.3 g (38.5 mmol) of diethyl vinylphosphonate monomer, previously dried overnight or more using molecular sieves 5A, was added and stirred for 1.5 hours. 0.79 g (25 mmol) of methanol was added to terminate the reaction.

[0684] The above solution was concentrated by rotary evaporation at 45°C, about 40 mL of THF was added, and the mixture was added dropwise to about 500 mL of n-hexane to precipitate (Brs-g-EvP)-B. The resulting polymer was separated by suction filtration and thoroughly dried in a vacuum to obtain (Brs-g-EvP)-B.

[0685] (Brs-g-EvP)-B was dissolved in deuterated chloroform to prepare a solution of about 2% by mass, １ The average degree of polymerization was determined by H-NMR. １ The H-NMR spectrum shows that the average degree of polymerization of the Brs block was 100, that of the B block was 468, and the total degree of polymerization of the EvP component chain was approximately 1310 (assuming that one EvP branch polymer grows per one bromo group of the Brs-B polymer, the average degree of polymerization of the EvP branch polymer was 13).

[0686] GPC measurement of (Brs-g-EvP)-B was carried out. The GPC chromatogram of (Brs-g-EvP)-B is shown by the solid line in Figure 15.

[0687] Compared with the peak of Brs-B, the peak of (Brs-g-EvP)-B is shifted to the lower elution time side, which suggests that EvP branch polymers have grown in almost all Brs-B. Note that multiple peaks are observed, and it is thought that these represent polymers with three or more EvP branch polymers, two EvP branch polymers, and one EvP branch polymer, respectively, from the lower elution time side.

[0688] (1-3) Third Step A hydrolysis reaction was carried out in the same manner as in Example 8, except that (Brs-g-EvP)-B was used as the polymer, to obtain (Brs-g-vPA)-B.

[0689] (Brs-g-vPA)-B was dissolved in a mixed solvent of deuterated THF / heavy water (volume ratio 1 / 1) to prepare a solution of about 2% by mass; １ H-NMR measurement was performed. The solid line in Figure 14d shows (Brs-g-vPA)-B １ The H-NMR spectrum shows that the signal attributable to the ester of the EvP branch polymer around δ = 4.0 was small, and the integral ratio confirmed that the deprotection reaction had progressed to 96%.

[0690] The sharp peaks around 3.6 and 1.8 ppm are due to THF, and the large peak around 4.6 ppm is due to water.

[0691] (1-4) Fourth Step: 0.50 g of (Brs-g-vPA)-B was dispersed in 4.2 g of a solvent mainly composed of a 1-propanol / water mixed solvent, and the dispersion was allowed to stand at 60°C for about 12 hours to evaporate the solvent, thereby preparing a proton-conducting electrolyte membrane of Example 14.

[0692] (1-4) Evaluation AC Impedance Measurement AC impedance measurement was performed in the same manner as in Example 1 to measure the proton conductivity of the (Brs-g-EvP)-B membrane. The measurement results of the proton conductivity of Example 14 are summarized in Table 1. The membrane of Example 14 exhibited, for example, a proton conductivity of 0.0095 S / cm at 80°C and 80% RH, 0.00063 S / cm at 80°C and 40% RH, and 0.19 S / cm at 95°C and 98% RH.

[0693]

[20] Example 15 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 15 In Example 15, a B-nBsS diblock copolymer was synthesized in the same manner as in Example 1, except that the amounts of 4-tert-butylstyrene monomer and 4-n-butylstyrenesulfonate monomer were appropriately changed. This was then hydrolyzed in the same manner as in Example 1 to synthesize a B-sSA diblock copolymer (B block polymerization degree 324, sSA block polymerization degree 2916, number average molecular weight 590,000, B-sSA-4). A membrane (hereinafter also referred to as a "B-sSA-4 / EMImBr membrane") was prepared by mixing the obtained B-sSA-4 with commercially available 1-ethyl-3-methylimidazolium bromide (hereinafter also referred to as "EMImBr") shown below, and this was used as the proton conductive electrolyte membrane of Example 15.

[0694] A mixed membrane of B-sSA-4 and EMImBr was prepared as follows: 0.047 g of B-sSA-4 and 0.046 g of EMImBr were dispersed in 0.50 g of a solvent primarily composed of a 1-propanol / water mixed solvent, and dissolved in 1.0 g of EMImBr. After mixing the respective solutions, the mixture was left to stand at 60°C for approximately 12 hours to evaporate the solvent, thereby preparing the proton-conducting electrolyte membrane of Example 15. The weight ratio of B-sSA-4 to EMImBr was 51:49.

[0695] The proton conductivity of the B-sSA-4 / EMImBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 15 at 80° C. are summarized in Table 1.

[0696] The membrane of Example 15 exhibited, for example, a proton conductivity of 0.36 S / cm at 80° C. and 80% RH, and 0.018 S / cm at 80° C. and 40% RH.

[0697]

[21] Example 16 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 16 In Example 16, a membrane comprising a mixture of B-sSA-4 and EPyBr (hereinafter also referred to as a "B-sSA-4 / EPyBr membrane") was prepared in the same manner as in Example 15, except that commercially available 1-ethylpyridinium bromide (hereinafter also referred to as "EPyBr") shown below was used instead of EMImBr, and this was used as the proton conductive electrolyte membrane of Example 16. The weight ratio of B-sSA-4 to EPyBr was 50:50.

[0698] The proton conductivity of the B-sSA-4 / EPyBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 16 at 80° C. are summarized in Table 1.

[0699] The membrane of Example 16 exhibited, for example, a proton conductivity of 0.34 S / cm at 80° C. and 80% RH, and 0.031 S / cm at 80° C. and 40% RH.

[0700]

[22] Example 17 (1) Preparation of the polymer electrolyte membrane (proton-conducting membrane) of Example 17 In Example 17, a membrane containing a mixture of B-sSA-4 and TBAmBr (hereinafter also referred to as a "B-sSA-4 / TBAmBr membrane") was prepared in the same manner as in Example 15, except that commercially available tetrabutylammonium bromide (hereinafter also referred to as "TBAmBr") shown below was used instead of EMImBr, and this was used as the proton-conducting electrolyte membrane of Example 17. The weight ratio of B-sSA-4 to TBAmBr was 37:63.

[0701] The proton conductivity of the B-sSA-4 / TBAmBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 17 at 80° C. are summarized in Table 1.

[0702] The membrane of Example 17 exhibited, for example, a proton conductivity of 0.027 S / cm at 80° C. and 80% RH, and 0.00067 S / cm at 80° C. and 40% RH.

[0703]

[23] Example 18 (1) Preparation of the Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 18 In Example 18, a B-EsP diblock copolymer was synthesized in the same manner as in Example 8, except that the amounts of 4-tert-butylstyrene monomer and 4-styrenephosphonic acid diethyl monomer were appropriately changed. This B-EsP diblock copolymer was then hydrolyzed in the same manner as in Example 8 to synthesize a B-sPA diblock copolymer (B block polymerization degree 324, sPA block polymerization degree 1466, number average molecular weight 320,000, B-sPA-2). A membrane containing a mixture of B-sPA-2 and EMImBr (hereinafter also referred to as a "B-sPA-2 / EMImBr membrane") was prepared in the same manner as in Example 15, except that B-sPA-2 was used. This membrane was used as the proton-conductive electrolyte membrane of Example 18. The weight ratio of B-sPA-2 to EMImBr was 52:48.

[0704] The proton conductivity of the B-sPA-2 / EMImBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 18 at 80° C. are summarized in Table 1.

[0705] The membrane of Example 18 exhibited, for example, a proton conductivity of 0.12 S / cm at 80° C. and 80% RH, and 0.035 S / cm at 80° C. and 40% RH.

[0706]

[24] Example 19 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 19 In Example 19, a membrane containing a mixture of B-sPA-2 and EPyBr (hereinafter also referred to as "B-sPA-2 / EPyBr membrane") was prepared in the same manner as in Example 18, except that EPyBr was used instead of EMImBr, and this was used as the proton conductive electrolyte membrane of Example 19. The weight ratio of B-sPA-2 to EPyBr was 54:46.

[0707] The proton conductivity of the B-sPA-2 / EPyBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 19 at 80° C. are summarized in Table 1.

[0708] The membrane of Example 19 exhibited, for example, a proton conductivity of 0.11 S / cm at 80° C. and 80% RH, and 0.023 S / cm at 80° C. and 40% RH.

[0709]

[25] Example 20 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 20 In Example 20, a membrane containing a mixture of B-sPA-2 and TBAmBr (hereinafter also referred to as a "B-sPA-2 / TBAmBr membrane") was prepared in the same manner as in Example 20, except that TBAmBr was used instead of EMImBr, and this was used as the proton conductive electrolyte membrane of Example 20. The weight ratio of B-sPA-2 to TBAmBr was 40:60.

[0710] The proton conductivity of the B-sPA-2 / TBAmBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 20 at 80° C. are summarized in Table 1.

[0711] The membrane of Example 20 exhibited, for example, a proton conductivity of 0.014 S / cm at 80° C. and 80% RH, and 0.0010 S / cm at 80° C. and 40% RH.

[0712]

[26] Example 21 (1) Preparation of the Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 21 In Example 21, the CL-sSA synthesized in Example 12 was immersed in an aqueous solution of EMImBr (concentration: approximately 3 wt %) and allowed to stand at 60°C for approximately 12 hours to evaporate the solvent. Approximately 1 g of water was added, and the mixture was again allowed to stand at 60°C for approximately 12 hours to evaporate the water. EMImBr was then allowed to penetrate into the CL-sSA, thereby preparing the proton-conductive electrolyte membrane of Example 21 (hereinafter also referred to as the "CL-sSA / EMImBr membrane"). The weight ratio of CL-sSA to EMImBr was 49:51.

[0713] The proton conductivity of the CL-sSA / EMImBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 21 at 80° C. are summarized in Table 1.

[0714] The membrane of Example 21 exhibited, for example, a proton conductivity of 0.37 S / cm at 80° C. and 80% RH, and 0.028 S / cm at 80° C. and 40% RH.

[0715]

[27] Example 22 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 22 In Example 22, a membrane containing CL-sSA and EPyBr (hereinafter also referred to as "CL-sSA / EPyBr membrane") was prepared in the same manner as in Example 21, except that EPyBr was used instead of EMImBr, and this was used as the proton conductive electrolyte membrane of Example 22. The weight ratio of CL-sSA to EPyBr was 50:50.

[0716] The proton conductivity of the CL-sSA / EPyBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 22 at 80° C. are summarized in Table 1.

[0717] The membrane of Example 22 exhibited, for example, a proton conductivity of 0.40 S / cm at 80° C. and 80% RH, and 0.043 S / cm at 80° C. and 40% RH.

[0718]

[28] Example 23 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 23 In Example 23, a membrane comprising a mixture of CL-sPA and EMImBr (hereinafter also referred to as "CL-sPA / EMImBr membrane") was prepared in the same manner as in Example 21, except that the CL-sPA synthesized in Example 13 was used, and this was used as the proton conductive electrolyte membrane of Example 24. The weight ratio of CL-sPA to EMImBr was 49:51.

[0719] The proton conductivity of the CL-sPA / EMImBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 24 at 80° C. are summarized in Table 1.

[0720] The membrane of Example 24 exhibited, for example, a proton conductivity of 0.12 S / cm at 80° C. and 80% RH, and 0.0039 S / cm at 80° C. and 40% RH.

[0721]

[29] Example 24 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 24 In Example 24, a membrane containing CL-sPA and EPyBr (hereinafter also referred to as "CL-sPA / EPyBr membrane") was prepared in the same manner as in Example 21, except that EPyBr was used instead of EMImBr, and this was used as the proton conductive electrolyte membrane of Example 24. The weight ratio of CL-sPA to EPyBr was 50:50.

[0722] The proton conductivity of the CL-sPA / EPyBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 24 at 80° C. are summarized in Table 1.

[0723] The membrane of Example 24 exhibited, for example, a proton conductivity of 0.12 S / cm at 80° C. and 80% RH, and 0.15 S / cm at 100° C. and 80% RH.

[0724]

[30] Example 25 (1) Preparation of Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 25 In Example 25, a membrane comprising a mixture of (Brs-g-vPA)-B and EMImBr (hereinafter also referred to as "(Brs-g-vPA)-B / EMImBr membrane") was prepared in the same manner as in Example 15, except that (Brs-g-vPA)-B synthesized in Example 14 was used, and this was used as the proton conductive electrolyte membrane of Example 25. The weight ratio of (Brs-g-vPA)-B to EMImBr was 36:64.

[0725] The proton conductivity of the (Brs-g-vPA)-B / EMImBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 25 at 80° C. are summarized in Table 1.

[0726] The membrane of Example 25 exhibited, for example, a proton conductivity of 0.26 S / cm at 80° C. and 80% RH, and 0.034 S / cm at 80° C. and 40% RH.

[0727]

[31] Example 26 (1) Preparation of the polymer electrolyte membrane (proton-conducting membrane) of Example 26 In Example 26, a membrane containing a mixture of (Brs-g-vPA)-B and EPyBr (hereinafter also referred to as "(Brs-g-vPA)-B / EPyBr membrane") was prepared in the same manner as in Example 27, except that EPyBr was used instead of EMImBr. This was used as the proton-conducting electrolyte membrane of Example 28. The weight ratio of (Brs-g-vPA)-B to EPyBr was 37.4:62.6.

[0728] The proton conductivity of the (Brs-g-vPA)-B / EPyBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 26 at 80° C. are summarized in Table 1.

[0729] The membrane of Example 26 exhibited, for example, a proton conductivity of 0.12 S / cm at 80° C. and 80% RH, and 0.016 S / cm at 80° C. and 40% RH.

[0730]

[32] Example 27 (1) Preparation of the Polymer Electrolyte Membrane (Proton Conductive Membrane) of Example 27 In Example 27, a membrane containing a mixture of (Brs-g-vPA)-B and TBAmBr (hereinafter also referred to as "(Brs-g-vPA)-B / TBAmBr membrane") was prepared in the same manner as in Example 15, except that TBAmBr was used instead of EMImBr. This was used as the proton conductive electrolyte membrane of Example 27. The weight ratio of (Brs-g-vPA)-B to TBAmBr was 26:74.

[0731] The proton conductivity of the (Brs-g-vPA)-B / TBAmBr membrane was measured by AC impedance measurement in the same manner as in Example 1. The measurement results of the proton conductivity of Example 27 at 80° C. are summarized in Table 1.

[0732] The membrane of Example 27 exhibited, for example, a proton conductivity of 0.028 S / cm at 80° C. and 80% RH, and 0.0023 S / cm at 80° C. and 40% RH.

[0733]

[0734]

[0735] Example 28 In Example 28, diethyl 4-(4-vinylphenyl)butylphosphonate was synthesized as a phosphonate ester monomer having an alkyl spacer according to Scheme 1 below (first step), and then this monomer was polymerized according to Scheme 2 below (second step). The alkyl protecting groups of the resulting poly(diethyl 4-(4-vinylphenyl)butylphosphonate) were deprotected to synthesize poly(4-(4-vinylphenyl)butylphosphonic acid) (also known as poly(4-(4-phosphonobutyl)styrene)), which is a phosphonate polymer having an alkyl spacer (third step).

[0736] This poly(4-(4-vinylphenyl)butylphosphonic acid) was formed into a membrane to prepare the proton-conductive electrolyte membrane of Example 28 (fourth step).

[0737]

[0738]

[0739] (First Step) Step 1-1: In a stopcock-equipped recovery flask, 7.18 g (0.0392 mol) of 4-bromostyrene was dissolved in 100 mL of dehydrated tetrahydrofuran (THF) and cooled in a -80°C cooling bath. While still in the cooling bath, 24.7 mL (0.0392 mol) of an n-hexane solution of n-butyllithium (concentration: 1.59 mol / L) was added and stirred for 1 hour. 46 mL (85 g, 0.39 mol) of 1,4-dibromobutane was added, and the recovery flask was removed from the cooling bath and stirred at room temperature for 20 hours to synthesize 1-(4-bromobutyl)-4-vinylbenzene.

[0740] After adding 50 mL of pure water, the volatile solvents (THF and n-hexane) were evaporated by rotary evaporation. Separation using dichloromethane was performed five times, and the dichloromethane phase was washed twice with saturated saline, after which the dichloromethane was removed by rotary evaporation. 1.04 g of the polymerization inhibitor 4-tert-butylcatechol (TBC) was added, and the pressure was reduced using a vacuum pump in an oil bath at 120°C for 10 hours to remove unreacted 1,4-dibromobutane and by-products.

[0741] The liquid obtained after the pressure reduction was dissolved in deuterated chloroform to prepare a solution of about 1% by mass. １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown in Figure 16. The dotted line in Figure 16 indicates the １ The H-NMR spectrum is shown.

[0742] The precursor 4-bromostyrene １ In the H-NMR spectrum, protons (a, b, c) attached to the vinyl group were observed around 5.2, 5.7, and 6.7 ppm, and protons (d, e) attached to the benzene ring were observed around 7.3 and 7.4 ppm.

[0743] After the reaction １ In the H-NMR spectrum, the chemical shifts of the protons (a, b, c) attached to the vinyl group were almost unchanged, and the peaks derived from the protons (d, e) attached to the benzene ring were shifted to around 7.1 and 7.3 ppm.

[0744] Furthermore, the peak of the methylene group proton (f) adjacent to the benzene ring was observed at 2.6 ppm, the peak of the methylene group proton (g) next to that at 1.9 ppm, the peak of the methylene group proton (h) next to that at 1.8 ppm, and the peak of the methylene group proton (i) with a bromo group at around 3.4 ppm, and the integral ratio of each peak was approximately 1:1:1:1, which suggests that 1-(4-bromobutyl)-4-vinylbenzene was obtained. The peak at 7.27 ppm is derived from chloroform, and the peaks around 1.9 and 6.8-6.9 ppm are derived from TBC.

[0745] The liquid obtained after the pressure reduction was dissolved in deuterated chloroform to prepare a solution of about 3% by mass. １３ C-NMR measurements were also carried out. １３ The C-NMR spectrum is shown in Fig. 17. The dotted line in Fig. 17 indicates the C-NMR spectrum of 4-bromostyrene. １３ The C-NMR spectrum is shown.

[0746] The precursor 4-bromostyrene １３In the C-NMR spectrum, the carbon atoms (a, b, c) of the vinyl group were observed around 115, 136, and 137 ppm, respectively, and the carbon atoms (d, e, f) attached to the benzene ring were observed around 128, 132, and 122 ppm.

[0747] After the reaction １３ In the C-NMR spectrum, the chemical shifts of the protons (a, b, c) attached to the vinyl group shifted to around 113, 137, and 135 ppm, and the peaks derived from the protons (d, e, f) attached to the benzene ring shifted to around 129 and 126 ppm. This change in chemical shift is thought to be due to the disappearance of the bromo group attached to the benzene ring.

[0748] Furthermore, a peak derived from the carbon atoms (g, h, i, j) of the methylene group was observed at 30 to 35 ppm, suggesting that 1-(4-bromobutyl)-4-vinylbenzene was obtained. The peak near 77 ppm is derived from chloroform.

[0749] Step 1-2: 5.31 g (0.0222 mol) of 1-(4-bromobutyl)-4-vinylbenzene was dissolved in 5.02 g of phenylacetonitrile, and 0.74 g (0.0044 mol) of TBC was added. 7.40 g (0.0444 mol) of triethyl phosphite was added, and the mixture was stirred in a 120°C oil bath for 24 hours. The mixture was then depressurized using a vacuum pump in a 120°C oil bath for 10 hours to remove the solvent phenylacetonitrile and unreacted triethyl phosphite.

[0750] The resulting liquid was separated and purified by passing it through a silica gel column. A mixed solvent consisting of n-hexane and 2-propanol was used as the developing solvent. The resulting monomer was dissolved in approximately 10 mL of THF, passed through an alumina column to remove TBC, and then rotary evaporated to remove the THF, yielding diethyl 4-(4-vinylphenyl)butylphosphonate monomer.

[0751] The liquid obtained after purification was dissolved in deuterated chloroform to prepare a solution of about 1% by mass, １ H-NMR measurements were carried out. １The H-NMR spectrum is shown.

[0752] The chemical shifts of the vinyl group, benzene ring, and protons attached to the benzyl position (a to f) were almost unchanged, while the peak derived from the proton i of 1-(4-bromobutyl)-4-vinylbenzene disappeared.

[0753] Furthermore, a new peak derived from the proton (j) of the methylene group next to the oxygen atom of the phosphate ester appeared near 4.1 ppm, and a peak derived from the proton (k) of the methyl group next to that appeared near 1.3 ppm. Peaks derived from the proton attached to the methylene group next to the benzyl position, the proton (h) of the methylene group next to that, and the proton (i) of the methylene group next to the phosphorus atom were observed at 1.6 to 1.8 ppm, and the integral ratio of the peaks j, k, and g to i was approximately 2:3:3, confirming that a 4-(4-vinylphenyl)butylphosphonic acid diethyl monomer was obtained. The peak at 7.27 ppm is derived from chloroform, and the peaks near 1.9 and 6.8 to 6.9 ppm are derived from TBC.

[0754] The liquid obtained after purification was dissolved in deuterated chloroform to prepare a solution of about 3% by mass, １３ C-NMR measurements were also carried out. １３ The C-NMR spectrum is shown.

[0755] The chemical shifts of the vinyl group and the carbon atoms (a to f) of the benzene ring were almost unchanged, while the peaks derived from the carbon atoms of the methylene group (g to j) were shifted in the range of 22 to 35 ppm.

[0756] Furthermore, a new peak at around 62 ppm derived from the carbon (k) of the methylene group next to the oxygen atom of the phosphate ester and a new peak at around 17 ppm derived from the proton (l) of the methyl group next to that peak confirmed that diethyl 4-(4-vinylphenyl)butylphosphonate monomer was obtained. The peak at around 77 ppm is a peak derived from chloroform.

[0757] The liquid obtained after purification was dissolved in deuterated dimethyl sulfoxide to prepare a solution of about 6% by mass, and an 85% aqueous solution of phosphoric acid was added to the solution as an internal standard. ３１ P-NMR measurement was carried out. ３１ The P-NMR spectrum is shown.

[0758] Since only a peak at around 33 ppm due to the phosphorus atom of the phosphonate diester was observed, it is believed that no phosphorus compounds other than the target phosphonate diester were present. From the above NMR measurement results, it was confirmed that 4-(4-vinylphenyl)butylphosphonic acid diethyl monomer was obtained.

[0759] (Second Step) The diethyl 4-(4-vinylphenyl)butylphosphonate monomer obtained in the first step was weighed out with azobisisobutyronitrile (AIBN) and phenylacetonitrile in amounts of 0.503 g (1.68 mmol), 2.0 mg (0.012 mmol), and 0.5 g, respectively, and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0760] Nitrogen gas was then bubbled through the mixture for 30 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 120° C. while stirring at 500 rpm. After 5 hours, the flask was immersed in liquid nitrogen to completely stop the polymerization reaction.

[0761] The above reaction solution was dissolved in approximately 1 mL of chloroform and added dropwise to approximately 20 mL of n-hexane to precipitate an oily polymer (crude poly(4-(4-vinylphenyl)butylphosphonate)). The resulting polymer was separated by decantation and thoroughly dried by vacuum drying, and then redissolved in chloroform and added dropwise to n-hexane to precipitate the polymer. Unreacted monomers and low-molecular-weight oligomers were removed, and purified poly(4-(4-vinylphenyl)butylphosphonate) was obtained.

[0762] Using deuterated chloroform, １ H-NMR measurement was carried out. Poly(4-(4-vinylphenyl)butylphosphonic acid diethyl) １ The H-NMR spectrum is shown by the dashed line in FIG.

[0763] The peaks derived from the vinyl group protons disappeared, and broad signals derived from protons c to j were observed at positions almost identical to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0764] Poly(diethyl 4-(4-vinylphenyl)butylphosphonate) was dissolved in THF to prepare a solution of approximately 0.1% by mass, and the molecular weight distribution (Mw / Mn) was determined by gel permeation chromatography (GPC). The Mw / Mn and Mw determined by molecular weight calibration using standard polystyrene were 2.5 and 45 kJ, respectively.

[0765] The GPC chromatogram of poly(diethyl 4-(4-vinylphenyl)butylphosphonate) is shown in Figure 20. Standard polystyrene was used for molecular weight calibration. The eluent was a solvent mainly composed of THF, with a flow rate of 1 mL / min and a temperature of 40°C, and the chromatogram was collected using a TSKgel column GMH manufactured by Tosoh Corporation. ＨＲ Measurements were carried out with two -Ms linked together.

[0766] (Third Step) In a literature article (Macromolecules, 2018, 51, 1120-1128.), poly(diethyl 4-styrenephosphonate) is reacted with bromotrimethylsilane, and then the reaction mixture is dialyzed using a methanol solvent to deprotect the alkyl groups of poly(diethyl 4-styrenephosphonate), thereby synthesizing poly(4-styrenephosphonic acid) having no alkyl spacer.

[0767] Based on this reaction, poly(diethyl 4-(4-vinylphenyl)butylphosphonate) obtained in the second step was reacted with bromotrimethylsilane, and then the resulting mixture was dialyzed using water instead of methanol to carry out a deprotection reaction.

[0768] Specifically, 0.30 g (1.0 mmol in monomer units) of poly(diethyl 4-(4-vinylphenyl)butylphosphonate) was dissolved in 3.0 mL of chloroform, 2.3 g (0.015 mol) of bromotrimethylsilane was added, and the mixture was placed in an oil bath at 40°C and stirred for 15 hours. This solution was concentrated by rotary evaporation and then mixed with approximately 5 mL of pure water. The mixture was transferred to a cellulose dialysis tube and dialyzed by immersing it in pure water for approximately 3 hours. This dialysis was repeated three times in total. The dialyzed solution was dried at 100°C to obtain poly(4-(4-vinylphenyl)butylphosphonic acid).

[0769] Poly(4-(4-vinylphenyl)butylphosphonic acid) was dissolved in a 6 / 4 (volume ratio) mixture of deuterated chloroform and deuterated methanol to prepare a solution of approximately 2% by mass. １ 1H-NMR measurement was carried out. In FIG. 19, the solid line indicates the １ The H-NMR spectrum is shown.

[0770] The peak at about 4.1 ppm resulting from the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester almost disappeared, confirming that deprotection had proceeded to 96%.

[0771] The sharp peak near 3.3 ppm is a peak derived from methanol, the peak near 4.8 ppm is a peak derived from residual water in the polymer, the peaks near 1.8 and 3.7 ppm are peaks derived from THF, the peaks near 0.9 and 1.3 ppm are peaks derived from n-hexane, and the peak near 2.3 ppm is a peak derived from by-products and impurities of the deprotection reaction.

[0772] (Fourth Step) 0.050 g of poly(4-(4-vinylphenyl)butylphosphonic acid) was dissolved in 1.5 g of a solvent mainly composed of a 1-propanol / water mixed solvent, and the solution was transferred to a polypropylene container. The solution was left to stand at 70°C for about 6 hours to evaporate the solvent, and a poly(4-(4-vinylphenyl)butylphosphonic acid) membrane was prepared.

[0773] <Evaluation> (AC Impedance Measurement) Using a platinum mesh with a thickness of 0.1 mm as an electrode, AC impedance measurement was carried out on the sample of the proton-conductive electrolyte membrane of Example 28.

[0774] A sample of the proton-conductive electrolyte membrane of Example 28 cut into a strip (thickness: 0.11 mm, width: 2.5 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.203 cm. The sample sandwiched between the electrodes was placed in a small environmental test chamber (SH-242, manufactured by Espec Corporation) and subjected to a temperature of 80°C, a relative humidity of 80% RH (partial pressure of water vapor p Ｈ２Ｏ The mixture was left standing under the condition of 379 hPa (pressure).

[0775] Using a potentio / galvanostat VSP-300 (manufactured by BioLogic Science Instruments), the voltage was set to 50 mV and the frequency to 7 × 10 ６ Hz to 10 ０ The AC impedance was measured under humidified conditions of 80% RH with the temperature changed in the range of Hz. The resistance value at the minimum point of the Nyquist plot was read to be 1.3 × 10 ５ It was Omega.

[0776] The proton conductivity of the sample of the proton-conductive electrolyte membrane was calculated using the following formula (1), and was found to be 2.3 × 10 －３ S / cm (Table 3).

[0777] Proton conductivity = distance between electrodes / (membrane thickness x electrode width x resistance at the minimum point of the Nyquist plot) (1)

[0778] The measurement conditions were a temperature of 80°C and a relative humidity of 50% RH (p Ｈ２Ｏ The resistance at the minimum point of the Nyquist plot was 8.7 × 10 ５ Ω, and the proton conductivity is 3.5 × 10 －４ S / cm (Table 3).

[0779] The measurement conditions were a temperature of 80°C and a relative humidity of 30% RH (p Ｈ２ＯThe resistance at the minimum point of the Nyquist plot was 3.0 × 10 ６ Ω, and the proton conductivity is 1.0 × 10 －４ S / cm (Table 3).

[0780] The results of the measurement of the proton conductivity of Example 28 at 80° C. are shown by the filled circles (●) in FIG.

[0781] Comparative Example 6 In Comparative Example 6, poly(4-styrenephosphonic acid) (hereinafter also referred to as "sPA") having no alkyl spacer was synthesized, and AC impedance measurement was performed in the same manner as in Example 28 to measure its proton conductivity.

[0782] In the literature (Org. Lett. 2011, 13(8), 2110-2113.), 4-diethyl styrenephosphonate monomer is synthesized by reacting p-styrylboronic acid with diethyl phosphite in the presence of 1,10-phenanthroline and copper(I) oxide catalysts. 4-Diethyl styrenephosphonate monomer was synthesized in a similar manner to this reaction. The monomer was purified by passing through basic alumina immediately before use.

[0783] 2.03 g (0.00845 mol), 1.2 mg (0.0033 mmol), and 0.6 mg (0.0033 mmol) of purified 4-styrenephosphonic acid diethyl monomer, RAFT agent, and AIBN were weighed out and mixed in a round-bottom flask equipped with a stopcock to prepare a solution. Nitrogen gas was then bubbled through the solution for 30 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 85°C and 500 rpm with stirring. After 30 minutes, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0784] The RAFT agent used was 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid.

[0785] Approximately 10 mL of THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 150 mL of n-hexane to precipitate a powdery polymer (crude poly(4-styrenediethylphosphonate)). The resulting polymer was separated by suction filtration and thoroughly dried by vacuum drying, then re-dissolved in THF and added dropwise to n-hexane to precipitate the polymer. This polymer precipitation process was repeated three times to remove unreacted monomers and low-molecular-weight oligomers, yielding purified poly(4-styrenediethylphosphonate).

[0786] The purified poly(diethyl 4-styrenephosphonate) was dissolved in THF to prepare an approximately 0.1% by mass solution, and the Mw / Mn and Mw of the poly(diethyl 4-styrenephosphonate) were determined by GPC in the same manner as in Example 28, and were found to be Mw / Mn = 1.45 and Mw = 110kJ.

[0787] The deprotection reaction of poly(diethyl 4-styrenephosphonate) was carried out in the same manner as in the third step of Example 28 to obtain poly(4-styrenephosphonic acid), and a poly(4-styrenephosphonic acid) membrane was prepared in the same manner as in the fourth step of Example 28. The deprotection rate of the alkyl protecting group was １ The purity was determined by H-NMR to be around or above 99%.

[0788] The proton conductivity of the poly(4-styrenephosphonic acid) membrane was measured in the same manner as in Example 28. The measurement results of the proton conductivity of Comparative Example 6 at 80°C are shown by crosses (x) in Figure 21 and are also summarized in Table 3.

[0789] The film of Comparative Example 6 had a viscosity of 7.5 × 10 at 95°C and 98% RH. －３ S / cm, 95°C, 80% RH 3.2 × 10 －３ S / cm, 80°C, 80% RH 1.5 x 10 －３ S / cm, 80°C, 50% RH 1.2 × 10 －４ S / cm, 80°C, 30% RH 4.0 x 10 －５ The proton conductivity was 1.0 S / cm.

[0790] The poly(4-(4-vinylphenyl)butylphosphonic acid) membrane having an alkyl spacer of Example 28 (equivalent mass (EW) indicating ion exchange capacity = 240, pKa (indicator of acidity) of a phosphonic acid low molecule having a similar structure to the monomer unit = about 2.4 (ACS Appl. Mater. Interfaces 2019, 11(37), 33931-33940.)) had a similar ion exchange capacity to the poly(4-styrenephosphonic acid) membrane having no alkyl spacer of Comparative Example 6 (EW = 184, pKa of a phosphonic acid low molecule having a similar structure to the monomer unit = about 1.8 to 2.0 (ACS Appl. Mater. Interfaces 2019, 11(37), 33931-33940. )), it exhibits a higher proton conductivity despite having a larger EW (lower molar concentration of acid groups) and lower acidity (higher pKa), and it can be seen that the difference in conductivity is particularly large when the number of water molecules in the membrane is small at low humidification.

[0791] In the poly(4-styrenephosphonic acid) of Comparative Example 6, the absence of an alkyl spacer made it difficult for the phosphonic acid groups to come close to each other, and conductive paths consisting of water molecules and phosphonic acid groups were likely to be formed discontinuously. In contrast, in the poly(4-(4-vinylphenyl)butylphosphonic acid) of Example 28, the alkyl spacer made it easier for the phosphonic acid groups to come close to each other, and conductive paths were likely to be formed continuously, which is thought to have resulted in a large EW and higher conductivity despite low acidity.

[0792] When the above membrane was immersed in water at approximately 20°C, 60°C, and 70°C for 1 hour, poly(4-styrenephosphonic acid) was gradually dissolved from the electrolyte membrane of Comparative Example 6 into the liquid water and finally dissolved completely to form a homogeneous (transparent) solution.

[0793] Example 29 In Example 29, a composite polymer membrane (proton-conducting electrolyte membrane) was prepared, which consisted of poly(4-(4-vinylphenyl)butylphosphonic acid) obtained in Example 28 and polyethyleneimine, which was a basic polymer.

[0794] 0.049 g of poly(4-(4-vinylphenyl)butylphosphonic acid) was dissolved in 1.5 g of a mixed solvent mainly composed of 1-propanol and water. Separately, 0.0006 g of polyethyleneimine (molecular weight 10,000, manufactured by Junsei Chemical Co., Ltd.) was dissolved in 0.15 g of a mixed solvent mainly composed of 1-propanol and water.

[0795] The solution containing polyethyleneimine was added to the solution containing poly(4-(4-vinylphenyl)butylphosphonic acid) and mixed, and then transferred to a polypropylene container. The mixture was left to stand at 70°C for about 6 hours to evaporate the solvent, thereby preparing a proton-conducting electrolyte membrane of Example 29.

[0796] The proton conductivity of the membrane was measured in the same manner as in Example 28. After standing at 95°C and 98% RH for about 3 hours, the conductivity was 9.4 x 10 －３ After standing at 80°C and 80% RH for approximately 3 hours, the conductivity was 3.8 x 10 －３ S / cm (Table 3).

[0797] Even when the above membrane was immersed in water at about 20°C for 1 hour before conductivity measurement, the water remained clear and no dissolution of the membrane was observed. Also, even when the membrane was immersed in water at 70°C for 1 hour, the water remained clear and no dissolution of the membrane was observed.

[0798] Furthermore, when the composite polymer membrane after immersion in water was removed from the water and its conductivity was measured, it was found to have almost the same conductivity as a membrane that had not been immersed in water (the conductivity after standing at 95°C and 98% RH for about 3 hours was 9.6 × 10 －３ After standing at 80°C and 80% RH for approximately 3 hours, the conductivity was 3.6 x 10 －３ S / cm), it is believed that the polymer in the membrane was hardly dissolved in liquid water (Table 3).

[0799] The membrane of Comparative Example 6 is a simple acidic polymer and therefore easily dissolves in liquid water, whereas in the composite polymer membrane of Example 29, acid-base complexes are formed at multiple points between the multiple acidic groups (phosphonic acid groups) in poly(4-(4-vinylphenyl)butylphosphonic acid) and the multiple basic groups (amino groups) in polyethyleneimine, which is thought to make the polymer in the membrane less likely to dissolve or elute in liquid water.

[0800] Comparative Example 7 In Comparative Example 7, a proton-conductive electrolyte membrane made of polybenzimidazole (hereinafter referred to as "PBI") and phosphoric acid was prepared.

[0801] 0.501 g of commercially available PBI (Hozole C) and 10.0 g of dimethylacetamide were mixed and stirred at 130 ° C for 4 hours. The resulting solution was filtered to remove insoluble matter, yielding a PBI solution. The resulting solution was transferred to a polytetrafluoroethylene container and cast at 60 ° C for 3 days to obtain a PBI membrane.

[0802] 0.0467 g of an aqueous solution of phosphoric acid (85%) was added to 0.358 g of methanol, and 0.0099 g of the PBI membrane was immersed in the solution and cast at 50°C for 1 day to evaporate the methanol. The membrane was then vacuum dried at 60°C for 2 days. The weight of the membrane obtained was 0.0367 g, and the phosphoric acid content of the membrane was approximately 73 wt%.

[0803] In the same manner as in Example 28, the above membrane was left standing at 80°C and 80% RH for about 3 hours, after which the conductivity was 2.4 x 10 －１ The proton conductivity was 1.0 S / cm.

[0804] Before measuring the conductivity, the membrane was immersed in water at 70°C for 1 hour, removed from the water, and the conductivity was measured. The conductivity was 1 / 520 of that of the membrane before immersion in water (the conductivity after standing at 80°C and 80% RH for about 3 hours was 4.6 × 10 －４ Since the electrical conductivity decreased to 0.25 S / cm, it is believed that phosphoric acid was eluted into the liquid water.

[0805] In the membrane of Comparative Example 7, phosphoric acid could only form an acid-base complex with a basic imidazole group in polybenzimidazole at one point, and the complex easily disintegrated, causing phosphoric acid to elute and dissolve in the liquid water in which it was immersed.

[0806] Comparative Example 8 In Comparative Example 8, a proton-conducting electrolyte membrane was prepared from polystyrene-b-poly(4-vinylpyridine)-b-polystyrene triblock copolymer (hereinafter also referred to as "S-P-S") and sulfuric acid.

[0807] In a literature article (RSC Adv. 2021, 11(31), 19012-19020.), S-P-S is synthesized by two-stage RAFT polymerization. Using this as a reference, we synthesized S-P-S with a polystyrene volume fraction of 0.20 and an overall molecular weight of 170,000. Furthermore, in the above literature, an S-P-S membrane containing 10 to 80 wt% sulfuric acid was prepared using methanol. Using this as a reference, we prepared an S-P-S membrane containing 70 wt% sulfuric acid.

[0808] The proton conductivity of the membrane was measured in the same manner as in Example 28. After standing at 80°C and 80% RH for about 3 hours, the conductivity was 9.1 x 10 －１ S / cm.

[0809] Before measuring the conductivity, the membrane was immersed in water at 70°C for 1 hour, removed from the water, and the conductivity was measured. The conductivity was 1 / 13 of that of the membrane that was not immersed in water (the conductivity after standing at 80°C and 80% RH for about 3 hours was 7.0 x 10 －２ Since the electrical conductivity decreased to 1000 vol. S / cm, it is believed that sulfuric acid was dissolved into the liquid water.

[0810] In the membrane of Comparative Example 8, sulfuric acid could only form an acid-base complex at one point with the basic group (pyridyl group) in the poly(4-vinylpyridine) of S-P-S, and the complex was easily unraveled, which is thought to have resulted in the sulfuric acid eluting and dissolving in the liquid water in which it was immersed.

[0811] Example 30 A composite membrane (proton-conductive electrolyte membrane) was prepared from poly(4-(4-vinylphenyl)butylphosphonic acid) obtained in Example 28 and polyallylamine, a basic polymer.

[0812] Example 31 In Example 31, a phosphonic acid polymer having an alkyl spacer (poly(6-(4-vinylphenyl)hexylphosphonic acid) (also known as poly(4-(6-phosphonohexyl)styrene)) was synthesized in substantially the same manner as in Example 28, except that 1,6-dibromohexane was used instead of 1,4-dibromobutane in the first step of Example 28.

[0813] Example 32 In Example 32, poly(4-tert-butylstyrene)-b-poly(4-(4-vinylphenyl)butylphosphonate) (hereinafter also referred to as "B-EsbP diblock copolymer") was synthesized as a block copolymer according to Scheme 3 below, using diethyl 4-(4-vinylphenyl)butylphosphonate, which is a phosphonate ester monomer having an alkyl spacer, synthesized in Example 28. The alkyl protecting groups of the poly(4-(4-vinylphenyl)butylphosphonate) block were then deprotected to synthesize poly(4-tert-butylstyrene)-b-poly(4-(4-vinylphenyl)butylphosphonic acid) (hereinafter also referred to as "B-sbPA diblock copolymer"). The glass transition temperature (Tg, measured by DSC) of poly(4-tert-butylstyrene) was approximately 150°C.

[0814]

[0815] Crude 4-tert-butylstyrene monomer was passed through a column packed with basic alumina, and the 4-tert-butylstyrene monomer was further purified using an alkylmetal compound. The purified 4-tert-butylstyrene monomer, RAFT agent, azobisisobutyronitrile (AIBN), and diethylbenzene (isomer mixture) were weighed out in amounts of 8.84 g (0.0552 mol), 269 mg (0.738 mmol), and 8.70 g (0.0648 mol), respectively, and mixed in a round-bottom flask equipped with a stopcock to prepare a solution. Nitrogen gas was then bubbled through the mixture for 30 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 130 °C while stirring at 500 rpm. After 2.5 hours, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0816] The RAFT agent used was 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid.

[0817] Approximately 20 mL of THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 300 mL of methanol to precipitate a powdery polymer (crude poly(4-tert-butylstyrenestyrene)). The resulting polymer was separated by suction filtration and thoroughly dried by vacuum drying, then dissolved again in THF and added dropwise to methanol to precipitate the polymer. This polymer precipitation process was performed a total of three times to remove unreacted monomers and low-molecular-weight oligomers, and purified poly(4-tert-butylstyrene) was obtained. Hereinafter, this purified poly(4-tert-butylstyrene) will also be referred to as "B".

[0818] B was dissolved in THF to prepare a solution of about 0.1% by mass, and GPC measurement was carried out in the same manner as in Example 28. The GPC chromatogram of B is shown by the dashed line in Figure 22.

[0819] Using deuterated chloroform, １ H-NMR measurement was carried out. １ The H-NMR spectrum is shown. １ The average degree of polymerization of B was estimated by H-NMR measurement to be 255, and the average molecular weight was about 41,000.

[0820] Since the above-mentioned B has a RAFT agent residue introduced at the molecular chain terminal, it was used as a macro RAFT agent (a RAFT agent with a large molecular weight, hence referred to as a "macro RAFT agent") to carry out polymerization with diethyl 4-(4-vinylphenyl)butylphosphonate monomer.

[0821] A solution was prepared by weighing out 0.303 g (0.00102 mol), 0.0200 g (48.8 μmol), 0.1 mg (0.0006 mmol), and 0.146 g of diethyl 4-(4-vinylphenyl)butylphosphonate monomer, macroRAFT agent, AIBN, and diethylbenzene, respectively, and mixing them in a round-bottom flask equipped with a stopcock. Nitrogen gas was then bubbled through the solution for 10 minutes, and polymerization was carried out at atmospheric pressure in an oil bath at 85°C and 500 rpm with stirring. After 1 hour, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0822] 0.5 mL of THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 50 mL of hexane to precipitate a crude B-EsbP diblock copolymer. The resulting polymer was separated by suction filtration and thoroughly dried by vacuum drying. Then, it was dissolved again in THF and added dropwise to hexane to precipitate the polymer. This polymer precipitation process was performed twice in total to remove unreacted monomers, low-molecular-weight oligomers, etc., and a purified B-EsbP diblock copolymer was obtained.

[0823] B-EsbP was dissolved in deuterated chloroform to prepare a solution of about 2% by mass. １ The average degree of polymerization was determined by H-NMR measurement. １ The H-NMR spectrum shows that the average degree of polymerization of the B component chain was 255, the average degree of polymerization of the EsbP component chain was 456, and the overall number average molecular weight was approximately 180,000.

[0824] B-EsbP was dissolved in THF to prepare a solution of approximately 0.1% by mass, and GPC measurement was carried out in the same manner as in Example 28. The GPC chromatogram of B-EsbP is shown by the solid line in Figure 22. The peak of B-EsbP was shifted to the lower elution time side, confirming the formation of a block copolymer.

[0825] The deprotection reaction of B-EsbP was carried out in the same manner as in the third step of Example 28 to obtain a B-sbPA diblock copolymer.

[0826] B-sbPA was dissolved in a 6 / 4 (volume ratio) mixture of deuterated chloroform and deuterated methanol to prepare a solution of approximately 2% by mass. １ H-NMR measurement was performed. １ The H-NMR spectrum shows that the peak at around 4.1 ppm due to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester had disappeared, confirming that the deprotection had almost progressed.

[0827] The sharp peaks at 3.3 and 7.7 ppm are due to methanol and chloroform, respectively, the peak at 4.9 ppm is due to residual water in the polymer, and the peaks at 0.9 and 1.3 ppm are thought to be due to n-hexane.

[0828] Example 33 In Example 33, poly(4-tert-butylstyrene)-b-poly(4-styrenephosphonic acid diethyl) (hereinafter also referred to as "B-EsP diblock copolymer") was synthesized in the same manner as in Example 32, except that 4-styrenephosphonic acid diethyl monomer was used instead of 4-(4-vinylphenyl)butylphosphonic acid diethyl monomer. The alkyl protecting groups of the poly(4-styrenephosphonic acid diethyl) block were deprotected to synthesize poly(4-tert-butylstyrene)-b-poly(4-styrenephosphonic acid) (hereinafter also referred to as "B-sPA-1 diblock copolymer"). Furthermore, a composite polymer membrane (proton-conducting electrolyte membrane) consisting of the obtained B-sPA-1 diblock copolymer and the basic polymer polyethyleneimine (hereinafter also referred to as "EI") was prepared.

[0829] The average degree of polymerization of B-EsP is １ When determined by H-NMR, the average degree of polymerization of the B block component chain was 255, the average degree of polymerization of the sPA block component chain was 1,260, and the overall number average molecular weight was approximately 343,000. Furthermore, when GPC measurement was carried out in the same manner as in Example 32, the Mw / Mn was 2.3. For B-sPA-1, the deprotection rate of the alkyl protecting group was １ The purity was determined by H-NMR to be around or above 99%.

[0830] 0.100 g of B-sPA-1 was dispersed in 4.2 g of a solvent primarily composed of a 1-propanol / water mixed solvent. Separately, 0.0021 g of EI was dissolved in 0.71 g of a mixed solvent primarily composed of 1-propanol and water. The dispersion containing B-sPA and the solution containing polyethyleneimine were mixed and transferred to a polypropylene container. The mixture was allowed to stand at 60°C for approximately 12 hours to evaporate the solvent, and the proton-conducting electrolyte membrane of Example 33 was prepared. The molar ratio of acidic groups to basic groups was 90 / 10.

[0831] The proton conductivity of the membrane was measured in the same manner as in Example 28. After standing at 95°C and 98% RH for about 3 hours, the conductivity was 2.3 x 10 －２ S / cm, conductivity after standing at 95°C and 80% RH for about 3 hours was 4.6 x 10 －３ After standing at 80°C and 80% RH for approximately 3 hours, the conductivity was 2.3 x 10 －３ S / cm.

[0832] The proton conductivity measurement results for Example 33 are also summarized in Table 4.

[0833] Before measuring the conductivity, the above membrane was immersed in water at about 60°C for 3 hours. After immersion in water, the composite polymer membrane was removed from the water and the conductivity was measured. After standing at 95°C and 98% RH for about 3 hours, the conductivity was 2.2 × 10 －２ S / cm, conductivity after standing at 95°C and 80% RH for about 3 hours was 4.6 x 10 －３ After standing at 80°C and 80% RH for about 3 hours, the conductivity was 2.4 x 10 －３ The differences in conductivity between the membrane immersed in water and the membrane not immersed in water were -4.5%, 0%, and +4.3%, respectively. Since the conductivity was almost unchanged, it is believed that the polymer in the membrane was hardly dissolved into the liquid water.

[0834] Comparative Example 9 In Comparative Example 9, a membrane of B-sPA-1 synthesized in Example 33 was prepared, and its proton conductivity was measured. When the conductivity was measured under humidified conditions in the same manner as in Example 33, it was found to be 8.0 × 10 at a temperature of 95°C and a relative humidity of 98% RH. －３S / cm, temperature 95°C, relative humidity 80% RH 8.9 × 10 －４ S / cm, temperature 80°C, relative humidity 80% RH 6.6 × 10 －４ S / cm, and the composite polymer membrane of Example 33 showed a higher conductivity despite having fewer free acidic groups. This is thought to be because the formation of an acid-base complex in the composite polymer membrane promotes the ionization of protons from free acidic groups, resulting in an effect of increasing conductivity, which outweighed the effect of the decrease in conductivity due to the reduction in free acidic groups caused by the formation of the acid-base complex.

[0835] When the membrane of Comparative Example 9 was immersed in water at about 60° C. for 3 hours, the membrane dissolved in the liquid water.

[0836] The membrane of Comparative Example 9 is a simple acidic polymer and therefore dissolves in liquid water, whereas in the composite polymer membrane of Example 33, acid-base complexes are formed at multiple points between the multiple acidic groups (phosphonic acid groups) in the sPA block and the multiple basic groups (amino groups) in the EI, which is thought to make the polymer in the membrane less susceptible to elution and dissolution in liquid water.

[0837] Example 34 In Example 34, a composite polymer membrane (proton-conductive electrolyte membrane) composed of sPA synthesized in Comparative Example 6 and EI was prepared.

[0838] A composite polymer membrane consisting of sPA and EI was prepared in the same manner as in Example 33, where the molar ratio of acidic groups to basic groups was 90 / 10.

[0839] The conductivity was measured under humidified conditions in the same manner as in Example 28. The conductivity was 8.1 × 10 at a temperature of 95°C and a relative humidity of 98% RH. －２ S / cm, and showed higher conductivity than the simple acidic polymer membrane of Comparative Example 6, despite the smaller number of free acidic groups. This is thought to be because the formation of an acid-base complex in the composite polymer membrane promotes the ionization of protons from the free acidic groups, resulting in an effect of increasing conductivity, which outweighed the effect of the decrease in conductivity due to the decrease in the number of free acidic groups caused by the formation of the acid-base complex.

[0840] The membrane of Example 34 was immersed in water at about 60°C for 3 hours and then removed from the water. After that, the conductivity was measured. The conductivity was 8.3 x 10 at a temperature of 95°C and a relative humidity of 98% RH. －２ The difference in conductivity from the membrane not immersed in water was +2.9%, and since the conductivity was almost unchanged, it is believed that the polymer in the membrane was hardly dissolved into liquid water (Table 4).

[0841] The membrane of Comparative Example 6 is a simple acidic polymer and therefore easily dissolves in liquid water, whereas in the composite polymer membrane of Example 34, acid-base complexes are formed at multiple points between the multiple acidic groups (phosphonic acid groups) in sPA and the multiple basic groups (amino groups) in EI, which is thought to make the polymer in the membrane less likely to dissolve or elute in liquid water.

[0842] Example 35 In Example 35, a composite polymer membrane (proton-conducting electrolyte membrane) was prepared from the sPA synthesized in Comparative Example 6 and polyallylamine (molecular weight 65 kJ, hereinafter also referred to as "aAm").

[0843] A composite polymer membrane consisting of sPA and aAm was prepared in the same manner as in Example 33, where the molar ratio of acidic groups to basic groups was 90 / 10.

[0844] The conductivity was measured under humidified conditions in the same manner as in Example 28. When the sample was left standing for 0.5 hours at a temperature of 120°C and a relative humidity of 53% RH, the conductivity was 6.3 × 10 －３ S / cm (Table 4). At a temperature of 95°C and a relative humidity of 98% RH, the －１ S / cm, which showed higher conductivity than the simple acidic polymer membrane of Comparative Example 6, despite having fewer free acidic groups. This is thought to be because the formation of an acid-base complex in the composite polymer membrane promotes the ionization of protons from free acidic groups, resulting in an effect of increasing conductivity, which outweighed the effect of the decrease in conductivity due to the decrease in the number of free acidic groups caused by the formation of the acid-base complex.

[0845] The membrane of Example 35 was immersed in water at about 60°C for 3 hours and then removed from the water. After that, the conductivity was measured. The conductivity was 1.3 x 10 at a temperature of 95°C and a relative humidity of 98%RH.－１ The difference in conductivity between the membrane immersed in water and the membrane that was not immersed in water was -1.9%, and since the conductivity was almost unchanged, it is believed that the polymer in the membrane was hardly dissolved into the liquid water.

[0846] The membrane of Comparative Example 6 is a simple acidic polymer and therefore easily dissolves in liquid water, whereas in the composite polymer membrane of Example 35, acid-base complexes are formed at multiple points between the multiple acidic groups (phosphonic acid groups) in sPA and the multiple basic groups (amino groups) in aAm, which is thought to make the polymer in the membrane less likely to dissolve or elute in liquid water.

[0847] Example 36 In Example 36, a composite polymer membrane (proton-conducting electrolyte membrane) was prepared, which consisted of the sPA synthesized in Comparative Example 6 and poly(4-tert-butylstyrene)-b-poly(2-vinylpyridine) (degree of polymerization 291:1950, total molecular weight 251 kJ, hereinafter also referred to as "B-2VP diblock copolymer").

[0848] The B-2VP diblock copolymer was synthesized as in Example 32, except that 2-vinylpyridine monomer was used instead of diethyl styrene phosphonate monomer.

[0849] A composite polymer membrane consisting of sPA and B-2VP was prepared in the same manner as in Example 33, where the molar ratio of acidic groups to basic groups was 90 / 10.

[0850] The conductivity was measured under humidified conditions in the same manner as in Example 28. The conductivity was 3.5 × 10 at a temperature of 95°C and a relative humidity of 80% RH. －３ S / cm, temperature 80°C, relative humidity 80% RH 2.3 × 10 －３ S / cm (Table 4).

[0851] The membrane of Example 36 was immersed in water at about 60°C for 3 hours and then removed from the water. After that, the conductivity was measured. The conductivity was 3.0 x 10 at a temperature of 95°C and a relative humidity of 80% RH. －３ S / cm, temperature 80°C, relative humidity 80% RH 2.1 × 10 －３The difference in conductivity between the membrane immersed in water and the membrane not immersed in water was -14% and -11%, respectively. Since the conductivity did not change significantly, it is believed that the polymer in the membrane was hardly dissolved into the liquid water.

[0852] The membrane of Comparative Example 6 is a simple acidic polymer and therefore easily dissolves in liquid water, whereas in the composite polymer membrane of Example 36, acid-base complexes are formed at multiple points between the multiple acidic groups (phosphonic acid groups) in the sPA and the multiple basic groups (pyridyl groups) in the 2VP block, which is thought to make the polymer in the membrane less likely to dissolve or elute in liquid water.

[0853] Example 37 In Example 37, a composite polymer membrane made of sPA and B-2VP was prepared in the same manner as in Example 36, except that the molar ratio of acidic groups to basic groups was changed to 85 / 15.

[0854] The conductivity was measured under humidified conditions in the same manner as in Example 28. The conductivity was 5.2 × 10 at a temperature of 90°C and a relative humidity of 90% RH. －３ S / cm (Table 4).

[0855] The membrane of Example 37 was immersed in water at about 60°C for 3 hours and then removed from the water. After that, the conductivity was measured. The conductivity was 5.1 x 10 at a temperature of 90°C and a relative humidity of 90% RH. －２ The difference in conductivity from the membrane that was not immersed in water was -1.9%. Since the conductivity was almost unchanged, it is believed that the polymer in the membrane was hardly dissolved into the liquid water.

[0856] The membrane of Comparative Example 6 is a simple acidic polymer and therefore easily dissolves in liquid water, whereas in the composite polymer membrane of Example 37, acid-base complexes are formed at multiple points between the multiple acidic groups (phosphonic acid groups) in the sPA and the multiple basic groups (pyridyl groups) in the 2VP block, which is thought to make the polymer in the membrane less likely to dissolve or elute in liquid water.

[0857] Example 38 In Example 38, a composite polymer membrane (proton-conducting electrolyte membrane) consisting of poly(4-tert-butylstyrene)-b-poly(4-styrenesulfonic acid) (degree of polymerization 255:1780, total molecular weight 361 kJ, hereinafter also referred to as "B-sSA-5") and aAm was prepared. Note that B-sSA was a polymer that was relatively easily soluble in water.

[0858] B-sSA-5 was synthesized in the same manner as B-sbPA in Example 32, except that butyl styrenesulfonate monomer was used instead of diethyl styrenephosphonate monomer, and sodium hydroxide was used instead of bromotrimethylsilane in the deprotection reaction. １ The purity was determined by H-NMR to be around or above 99%.

[0859] A composite polymer membrane consisting of B-sSA-5 and aAm was prepared in the same manner as in the third step of Example 28, where the molar ratio of acidic groups to basic groups was 80 / 20.

[0860] The conductivity was measured under humidified conditions in the same manner as in Example 28. When the sample was left standing for 1 hour at a temperature of 120°C and a relative humidity of 53% RH, the conductivity was 2.0 x 10 －２ S / cm, temperature 90°C, relative humidity 90% RH 5.5 × 10 －２ S / cm (Table 4).

[0861] The membrane of Example 38 that was not used for the conductivity measurement was immersed in water at about 60°C for 3 hours, and after being removed from the water, the conductivity was measured at a temperature of 90°C and a relative humidity of 90% RH. The conductivity was 5.2 x 10 －２ The difference in conductivity from the membrane that was not immersed in water was -5.5%, and since the conductivity was almost unchanged, it is thought that the polymer in the membrane was hardly dissolved into the liquid water.

[0862] B-sSA-5 is an acidic polymer and therefore easily dissolves in liquid water, whereas in the composite polymer membrane of Example 38, acid-base complexes are formed at multiple points between the multiple acidic groups (sulfonic acid groups) in the sSA block and the multiple basic groups (amino groups) in the aAm, which is thought to make the polymer in the membrane less susceptible to elution and dissolution in liquid water.

[0863] Example 39 In Example 39, a composite polymer membrane (proton-conductive electrolyte membrane) was prepared from B-sSA-5 synthesized in Example 37 and B-2VP.

[0864] A composite polymer membrane consisting of B-sSA-5 and B-2VP was prepared in the same manner as in Example 33, where the molar ratio of acidic groups to basic groups was 70 / 30.

[0865] The conductivity was measured under humidified conditions in the same manner as in Example 28. The conductivity was 1.3 × 10 at a temperature of 90°C and a relative humidity of 90% RH. －１ S / cm (Table 4).

[0866] The membrane of Example 39 was immersed in water at about 60°C for 3 hours, and after being taken out of the water, the conductivity was measured. When the temperature was 90°C and the relative humidity was 90%, the conductivity was 1.4 × 10 －１ The difference in conductivity from the membrane not immersed in water was +7.7%, and since the conductivity was almost unchanged, it is believed that the polymer in the membrane was hardly dissolved into the liquid water.

[0867] B-sSA-5 is an acidic polymer and therefore dissolves relatively easily in liquid water, whereas in the composite polymer membrane of Example 39, acid-base complexes are formed at multiple points between the multiple acidic groups (sulfonic acid groups) in the sSA block and the multiple basic groups (pyridyl groups) in the 2VP block, which is thought to make the polymer in the membrane less susceptible to elution and dissolution in liquid water.

[0868] Example 40 In Example 40, polyvinylphosphonic acid (vPA) was synthesized by synthesizing polyvinylphosphonic acid diethyl ester (EvP) and deprotecting the alkyl protecting groups of the polyvinylphosphonic acid diethyl ester. A composite polymer membrane (proton-conducting electrolyte membrane) was then prepared from the resulting vPA and EI. Note that vPA was a polymer that readily dissolved in water.

[0869]

[0870] EvP was synthesized by anionic polymerization with reference to the literature (Macromolecules, 2009, 42, 5146). The Mw / Mn and Mw of EvP, determined by molecular weight calibration using standard polystyrene, were 3.1 and 37 kJ, respectively. The deprotection reaction of EvP was carried out in the same manner as in the third step of Example 28. A composite polymer membrane consisting of vPA and B-2VP was prepared in the same manner as in Example 33. The molar ratio of acidic groups to basic groups was 70 / 30.

[0871] The conductivity was measured under humidified conditions in the same manner as in Example 28. The conductivity was 5.1 × 10 at a temperature of 90°C and a relative humidity of 90% RH. －３ S / cm (Table 4).

[0872] Example 41 In Example 41, commercially available poly(4-vinylpyridine) (manufactured by Aldrich, product number 472352, average degree of polymerization 1522, weight-average molecular weight 160 kJ, hereinafter also referred to as "4VP") was reacted with bromoethane to synthesize ionized 4VP (hereinafter also referred to as "i-4VP"). A composite polymer membrane (proton-conducting electrolyte membrane) consisting of the obtained i-4VP and (Brs-g-vPA)-B synthesized in Example 14 was prepared, and this was designated the membrane of Example 41.

[0873] i-4VP was synthesized according to Scheme 4 below. The specific synthesis procedure is shown below. 0.504 g (4.8 mmol in monomer units) of 4VP was dissolved in 5.09 g of dimethyl sulfoxide (DMSO), and 2.59 g (24 mmol) of bromoethane was added. The reaction was allowed to proceed with stirring at 40°C and 500 rpm for 48 hours. Approximately 10 g of DMSO was added, and the resulting solution was added dropwise to approximately 500 mL of a poor solvent, a mixed solvent of acetone / n-hexane (volume ratio 1:1), to precipitate and purify i-4VP. The solvent and unreacted bromoethane were then removed by vacuum drying at 40°C for 1 day.

[0874] i-4VP was dissolved in deuterated DMSO to prepare a solution of about 1% by mass, １ When H-NMR measurement was carried out, the ionization rate of i-4VP was estimated to be 93 mol %.

[0875] A composite polymer membrane consisting of (Brs-g-vPA)-B and i-4VP was prepared in the same manner as in the third step of Example 28. The molar ratio of acidic groups to (basic groups and cationic groups) was 90 / 10, and the weight ratio of (Brs-g-vPA)-B to i-4VP was 88 / 12.

[0876] The conductivity was measured under humidified conditions in the same manner as in Example 28. For example, when the temperature was 80°C and the relative humidity was 80%, the conductivity was 6.4 × 10 －３ S / cm (Table 5).

[0877] The membrane of Example 41 that was not used for the conductivity measurement was immersed in water at about 60°C for 3 hours, and after being taken out of the water, the conductivity was measured at a temperature of 80°C and a relative humidity of 80% RH. The conductivity was 5.1 x 10 －３ The difference in conductivity between the membrane immersed in water and the membrane that was not immersed in water was -20%, which was a relatively small change in conductivity, suggesting that most of the polymer in the membrane did not dissolve in the liquid water.

[0878] While (Brs-g-vPA)-B is an acidic polymer and therefore readily dissolves in liquid water, in the composite polymer membrane of Example 41, multiple anionic groups (phosphonate groups formed by dissociating protons from phosphonic acid groups) derived from acidic groups in the branched vPA polymer and multiple cationic groups (pyridinium groups) in i-4VP generate ionic interactions at multiple points, which is thought to make the polymer in the membrane less susceptible to elution and dissolution in liquid water. Example 42 In Example 42, B-sSA-6 (degree of polymerization of B block: 255, degree of polymerization of sSA block: 3495, number average molecular weight: 680,000), synthesized in the same manner as in Example 38, was used as the acidic polymer. Instead of i-4VP, a B-2VP diblock copolymer (B block polymerization degree 109, 2VP block polymerization degree 345, number average molecular weight 54,000) synthesized in the same manner as the B-2VP synthesized in Example 36 was ionized in the same manner as in Example 41 to obtain a B-ionized 2VP diblock copolymer (2VP block ionization rate 15 mol%, hereinafter also referred to as "B-(i-2VP)"). B-sSA-6 and B-(i-2VP) were mixed in the same manner as in the third step of Example 28. The obtained membrane sample was then allowed to stand for 1 hour in an environment of 80°C and 80% RH to prepare the composite polymer membrane (proton-conducting electrolyte membrane) of Example 42. The molar ratio of acidic groups / (basic groups and cationic groups) was 80 / 20, and the weight ratio of B-sSA-2 to B-(i-2VP) was 82 / 18.

[0879] When the conductivity was measured under humidified conditions in the same manner as in Example 1, for example, at a temperature of 80°C and a relative humidity of 80% RH, it was 2.8 x 10 －２ S / cm (Table 5).

[0880] The membrane of Example 42 that was not used for the conductivity measurement was immersed in water at about 60°C for 1 hour, and after being taken out of the water, the conductivity was measured at a temperature of 80°C and a relative humidity of 80% RH. The conductivity was 2.6 x 10 －２ The difference in conductivity between the membrane immersed in water and the membrane that was not immersed in water was -7%, meaning that the conductivity was almost unchanged. This suggests that the polymer in the membrane was hardly dissolved into the liquid water.

[0881] B-sSA-6 is an acidic polymer and therefore easily dissolves in liquid water. However, in the composite polymer membrane of Example 42, acid-base complexes are formed at multiple points between the multiple acidic groups (sulfonic acid groups) in the sSA block and the multiple basic groups (pyridyl groups) in the 2VP block. Furthermore, ionic interactions are generated at multiple points between the multiple anionic groups (sulfonate groups formed by dissociating protons from sulfonic acid groups) derived from the acidic groups in the sSA block and the multiple cationic groups (pyridinium groups) in B-(i-2VP). This is thought to make the polymer in the membrane less susceptible to elution and dissolution in liquid water.

[0882]

[0883]

[0884]

[0885] INDUSTRIAL APPLICABILITY The composite polymer membrane (electrolyte membrane) of the present invention is a composite polymer membrane (anhydrous electrolyte membrane) based on a polymer made of a monomer having phosphonic acid and / or phosphonate ester via a spacer structure (preferably an alkyl spacer), and a composite polymer membrane (electrolyte membrane) containing a polymer having an acidic functional group (excluding polymers made of a monomer having phosphonic acid via a spacer structure) and a polymer having a basic functional group, in which elution of polymer electrolytes and low molecular weight electrolytes from the membrane into water is suppressed, and the ... －３ It exhibits good conductivity of 5 S / cm or more.

[0886] The composite polymer membrane (electrolyte membrane) of the present invention can be suitably used particularly as a proton-conducting electrolyte membrane in a fuel cell.

Claims

1. A polymer electrolyte membrane, a polymer having an acidic functional group, The polymer is (i) a block copolymer having at least an a-b type unit in which an a block and a b block are connected by a covalent bond; (ii) a chemically crosslinkable polymer having an acidic functional group in the side chain, and / or (iii) A polymer consisting of a monomer unit having a phosphonic acid group via a spacer structure which is an alkyl spacer having 2 to 12 repeating methylene groups, and which does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group; and the a block of (i) is composed of a hydrophobic polymer or a water-repellent polymer, and the hydrophobic polymer or the water-repellent polymer is a hydrophobic or water-repellent hydrocarbon-based or fluorocarbon-based vinyl polymer having a glass transition temperature (Tg) of 100°C or higher; the hydrophobic or water-repellent hydrocarbon vinyl polymer is a polystyrene-based polymer, and the polystyrene-based polymer includes at least one selected from the group consisting of polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, and polytrimethylstyrene; the fluorocarbon vinyl polymer comprises at least one selected from the group consisting of polyperfluorostyrene, polyperfluoromethylstyrene, and polypentafluorostyrene; The b block of (i) is composed of a polymer having an acidic functional group in a side chain or the polymer of (iii), or the side chain of the b block of (i) is composed of a graft chain containing an acidic functional group in a monomer unit; Polymer electrolyte membrane.

2. 2. The polymer electrolyte membrane according to claim 1, wherein the acidic functional group is an acidic functional group composed of at least one type selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

3. The polymer electrolyte membrane according to claim 1 , further comprising an ionic low-molecular-weight organic salt.

4. In the b block of (i), a polymer having an acidic functional group in a side chain, a polymer of (iii), or a graft chain containing an acidic functional group constituting a side chain in a monomer unit, the polymer (ii), and The polymer (iii) is 2. The polymer electrolyte membrane according to claim 1, which is a hydrocarbon vinyl polymer and contains 0.70 or more acidic functional groups in the monomer unit.

5. In the b block of (i), a polymer having an acidic functional group in a side chain, a polymer of (iii), or a graft chain containing an acidic functional group constituting a side chain in a monomer unit, The polymer (ii), and The polymer (iii) is 2. The polymer electrolyte membrane according to claim 1, which is obtained by polymerizing a monomer in which the acidic functional group or the phosphonic acid group is protected with a protecting group, and then deprotecting the protecting group, and which contains 0.70 or more of the acidic functional groups in the monomer unit.

6. The polymer electrolyte membrane according to claim 1, further comprising a hydrophobic polymer or a water-repellent polymer in addition to the polymer (i) containing a block copolymer having a-b type units in which at least the a block and the b block are linked by a covalent bond.

7. The polymer electrolyte membrane is (i) a block copolymer having at least a-b type units in which the a block and the b block are connected by a covalent bond, and / or (iii) a polymer consisting of a monomer unit having a phosphonic acid group via a spacer structure, and not containing a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group; When including The polymer electrolyte membrane of claim 1 , further comprising a proton donating agent.

8. 8. The polymer electrolyte membrane according to claim 7, wherein the proton donating agent is at least one selected from the group consisting of sulfuric acid and phosphoric acid.

9. A method for producing a polymer electrolyte membrane, comprising: (A) preparing a hydrophobic polymer to produce an a-block; (B) polymerizing a monomer having an acidic functional group protected by a protecting group or a monomer having a phosphonic acid group protected by a protecting group via a spacer structure with the a block to form a b block, thereby producing a block copolymer having a-b type units in which the a block and the b block constituted by units of the monomers are linked by a covalent bond; (C) a step of deprotecting the protecting group of the b block to produce a polymer containing 0.70 or more of the acidic functional group or the phosphonic acid group in the monomer unit constituting the b block and having the acidic functional group or the phosphonic acid group in a side chain; Including, the hydrophobic polymer is a hydrophobic hydrocarbon-based vinyl polymer; The hydrophobic hydrocarbon vinyl polymer is a polystyrene-based polymer, and the polystyrene-based polymer includes at least one selected from the group consisting of polyacetylstyrene, polyanisoylstyrene, polybenzoylstyrene, polybiphenylstyrene, polybromoethoxystyrene, polybromomethoxystyrene, polybromostyrene, polybutoxymethylstyrene, poly-tert-butylstyrene, polybutyrylstyrene, polychlorofluorostyrene, polychloromethylstyrene, polychlorostyrene, polycyanostyrene, polydichlorostyrene, polydifluorostyrene, polydimethylstyrene, polyethoxymethylstyrene, polyethoxystyrene, polyfluoromethylstyrene, polyfluorostyrene, polyiodostyrene, polymethoxycarbonylstyrene, polymethoxymethylstyrene, polymethylstyrene, polymethoxystyrene, polyperfluorostyrene, polyphenoxystyrene, polyphenylacetylstyrene, polyphenylstyrene, polypropoxystyrene, polytoluoylstyrene, and polytrimethylstyrene. Method for producing a polymer electrolyte membrane.

10. Furthermore, (D) a step of mixing a hydrophobic polymer or a water-repellent polymer having a molecular weight of 100,000 or more; The method for producing the polymer electrolyte membrane according to claim 9 , comprising:

11. Furthermore, (E) mixing a proton donating agent; The method for producing the polymer electrolyte membrane according to claim 9 , comprising:

12. (1) a polymer having an acidic functional group; (2) a polymer having a basic functional group, The (1) polymer having an acidic functional group is (i) a block copolymer having at least a-b type units in which the a block and the b block are connected by a covalent bond, and / or (iii) a polymer consisting of a monomer unit having a phosphonic acid group via a spacer structure, and not containing a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group; and The a block of (i) is composed of a hydrophobic polymer or a water-repellent polymer, The b block of (i) is composed of a polymer having an acidic functional group in a side chain or the polymer of (iii), or the side chain of the b block of (i) is composed of a graft chain containing a monomer unit having an acidic functional group; 1.0 x 10 －３ A composite polymer membrane exhibiting a conductivity of 100 S / cm or more.

13. The composite polymer membrane according to claim 12, wherein the acidic functional group is at least one selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

14. The (1) polymer having an acidic functional group is a polymer containing a monomer unit having an acidic functional group composed of at least one selected from the group consisting of 4-styrenesulfonic acid, vinylsulfonic acid, 4-styrenephosphonic acid, and vinylphosphonic acid. The composite polymer membrane of claim 12.

15. The (2) polymer having a basic functional group is a polymer having five or more basic functional groups each composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group, or A block copolymer having a cd type unit in which at least a c block and a d block are connected by a covalent bond, the c block is composed of a hydrophobic polymer or a water-repellent polymer, the d block is composed of a polymer having five or more basic functional groups each consisting of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, and a triazolyl group; block copolymer 13. The composite polymer membrane of claim 12, wherein:

16. The (2) polymer having a basic functional group is a polymer containing five or more monomer units having a basic functional group, which are composed of at least one selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, and vinylpyrrole; or A block copolymer having a cd type unit in which at least a c block and a d block are connected by a covalent bond, the c block is composed of a hydrophobic polymer or a water-repellent polymer, the d block is composed of a polymer containing five or more monomer units composed of at least one selected from the group consisting of ethyleneimine, allylamine, vinylamine, vinylpyridine, 2-vinylpyridine, vinylimidazole, vinylpyrazole, vinylpyrrole, and vinyltriazole; It is a block copolymer, The composite polymer membrane of claim 12.

17. The (2) polymer having a basic functional group is a polymer having a cationic functional group based on the basic functional group, a polymer in which a part of the basic functional groups is quaternized with an organic halogen compound to generate cations, and the polymer has cationic functional groups based on the basic functional groups; The composite polymer membrane of claim 12.

18. 13. The composite polymer membrane according to claim 12, wherein the proportion of cationic functional groups based on basic functional groups among the basic functional groups is 10 mol % or more.

19. 18. The composite polymer membrane of claim 17, wherein the organohalogen compound is a compound having an alkyl halide moiety.

20. a polymer having an anionic group based on an acidic functional group, which is obtained by combining the polymer having the (1) acidic functional group with the polymer having a cationic functional group based on the basic functional group, so that a proton is ionized from the acidic functional group of the polymer having the (1) acidic functional group to form an anionic functional group, and a low-molecular-weight acid consisting of a counter anion of the cationic functional group of the polymer having the cationic functional group based on the basic functional group and a proton escapes from the membrane; a polymer having a cationic group based on the basic group, 1.0 x 10 －３ 18. The composite polymer membrane of claim 17, which exhibits a conductivity of 100 S / cm or greater.

21. The composite polymer membrane according to claim 12, wherein the conductivity of the composite polymer membrane does not differ by 25% or more when immersed in water at 60°C for 1 hour compared to a membrane that is not immersed.

22. A polymer constituting the polymer electrolyte membrane according to any one of claims 1 to 8, or A composite polymer constituting the composite polymer membrane according to any one of claims 12 to 21. An ionomer for a polymer electrolyte fuel cell, comprising:

23. A monomer having a phosphonic acid group and / or a phosphonic acid ester via a spacer structure which is an alkyl spacer having 2 to 12 repeating methylene groups, and which does not contain a highly hydrolyzable functional group between a portion which becomes the main chain skeleton of the polymer after polymerization and the phosphonic acid group and / or phosphonic acid ester which are part of the side chain of the polymer after polymerization.