Polymer electrolyte membrane, and electrolyte membranes with catalyst layers using the same, membrane electrode composites, polymer electrolyte fuel cells, and water electrolysis hydrogen generators.

Abstract

To achieve a polymer electrolyte membrane having excellent proton conductivity even in low humidity conditions and also having excellent mechanical strength and chemical stability.SOLUTION: There is provided a polymer electrolyte membrane comprising a block copolymer having one or more, respectively, of ionic segments and non-ionic segments. The block copolymer has an ion exchange capacity (meq / g) of more than 2.0 and less than 3.1, the polymer electrolyte membrane has a co-continuous phase separation structure, an average period size (nm) of the co-continuous phase separation structure as observed by a transmission electron microscope is less than 110 nm, and the average period size (nm) and the ion exchange capacity (meq / g) of the co-continuous phase separation structure satisfy a relationship, average period size (nm) / ion exchange capacity (meq / g)≥21.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer electrolyte membrane, and to a catalyst-layered electrolyte membrane, a membrane electrode composite, a polymer electrolyte fuel cell, and a water electrolysis hydrogen generator using the same. [Background technology]

[0002] Fuel cells are a type of power generation device that extracts electrical energy by electrochemically oxidizing fuels such as hydrogen and methanol, and have recently attracted attention as a clean energy source. Among them, polymer electrolyte fuel cells have a low standard operating temperature of around 100°C and high energy density, making them promising for a wide range of applications as power generation devices in relatively small-scale distributed power generation facilities and in mobile devices such as automobiles and ships. Polymer electrolyte fuel cells are also attracting attention as a power source for small mobile devices and portable devices, and are expected to be used as a replacement for secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries in mobile phones and personal computers.

[0003] Fuel cells typically consist of a cell unit in which a membrane electrode assembly (MEA) is sandwiched between separators. An MEA has catalyst layers on both sides of an electrolyte membrane, with gas diffusion layers further positioned on either side of the catalyst layers. In an MEA, the catalyst layers and gas diffusion layers on either side of the electrolyte membrane form a pair of electrode layers, one of which is the anode electrode and the other the cathode electrode. Electricity is generated by an electrochemical reaction when a hydrogen-containing fuel gas comes into contact with the anode electrode and air comes into contact with the cathode electrode. The electrolyte membrane is primarily composed of polymer electrolyte material. Polymer electrolyte material is also used as a binder for the catalyst layer.

[0004] Heretofore, "Nafion" (registered trademark) (manufactured by Chemours Co., Ltd.), which is a fluorine-based polymer electrolyte, has been widely used as a polymer electrolyte material. On the other hand, development of inexpensive hydrocarbon-based electrolyte materials having excellent membrane properties, which can replace "Nafion" (registered trademark), has been active in recent years. Hydrocarbon-based electrolyte materials are excellent in low gas permeability and heat resistance, and electrolyte materials using aromatic polyether ketone or aromatic polyether sulfone have been particularly actively studied. However, while conventional hydrocarbon-based electrolyte materials exhibit proton conductivity equivalent to or more advantageous than that of fluorine-based electrolyte materials under high humidification conditions, their proton conductivity is insufficient under low humidification conditions.

[0005] As a hydrocarbon-based polymer electrolyte material that has excellent proton conductivity even under low humidification conditions and is excellent in mechanical strength and chemical stability, a block copolymer composed of a segment containing an ionic group (hereinafter referred to as "ionic segment") and a segment containing no ionic group (hereinafter referred to as "nonionic segment") has been proposed (see, for example, Patent Documents 1 to 3). PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0006] PATENT DOCUMENT 1 International Publication No. WO 2008 / 018487 PATENT DOCUMENT 2 International Publication No. WO 2013 / 031675 PATENT DOCUMENT 3 Japanese Patent Application Laid-Open No. 2006-278321 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0007] However, even when the polymer electrolyte membranes described in Patent Documents 1 to 3 are used, the effect of improving proton conductivity and mechanical strength under low humidification conditions is still insufficient, and further improvement has been desired for an industrially useful polymer electrolyte membrane.

[0008] In view of the background of the prior art, the present invention aims to realize a polymer electrolyte membrane that has excellent proton conductivity even under low humidity conditions, and also exhibits excellent mechanical strength and physical durability. [Means for solving the problem]

[0009] The inventors of the present invention hypothesized that the reason the prior art had the above problems was that the morphology of the phase separation structure in the polymer electrolyte membrane was not of a co-continuous phase separation size and was not optimal for proton conduction, and that the ion exchange capacity was not suppressed relative to the periodic size of the phase separation, and that the periodic size of the phase separation and the ion exchange capacity were not within an appropriate range that could balance proton conductivity and dimensional stability.

[0010] Based on that hypothesis, the following findings were discovered. By increasing the periodic size of cocontinuous phase separation, a large proton conduction channel can be maintained even under low humidity conditions, thereby improving proton conductivity. On the other hand, if the ion exchange capacity is increased in order to expand the periodic size of phase separation, dimensional stability decreases as the ion exchange capacity increases, and mechanical strength and physical durability also decrease.

[0011] In other words, the inventors of the present invention have found that in order to achieve both proton conductivity and dimensional stability, it is necessary to increase the period size of co-continuous phase separation while keeping the ion exchange capacity below a certain value relative to the period size of co-continuous phase separation, and this led to the present invention.

[0012] The present invention has the following configuration. (1) A polymer electrolyte membrane comprising a block copolymer having one or more segments containing ionic groups (hereinafter referred to as "ionic segments") and one or more segments not containing ionic groups (hereinafter referred to as "nonionic segments"), wherein the block copolymer has an ion exchange capacity (meq / g) greater than 2.0 and less than 3.1, the polymer electrolyte membrane has a co-continuous phase separation structure, and the average period size (nm) of the co-continuous phase separation structure observed by a transmission electron microscope is 100 The average period size (nm) of the co-continuous phase separation structure and the ion exchange capacity (meq / g) satisfy the relationship: average period size (nm) / ion exchange capacity (meq / g) ≥ 21. Furthermore, the crystallization heat of the polymer electrolyte membrane, as measured by differential scanning calorimetry, is 0.1 J / g or more, or the degree of crystallinity of the polymer electrolyte membrane, as measured by wide-angle X-ray diffraction, is 0.5% or more. A polymer electrolyte membrane characterized by the following features. ( 2 ) The block copolymer is characterized in that the block copolymer is an aromatic hydrocarbon copolymer. (1) The polymer electrolyte membrane described above. ( 3 )The aforementioned aromatic hydrocarbon copolymer is characterized in that it is an aromatic polyether copolymer. 2 A polymer electrolyte membrane as described in ). ( 4 )The aromatic polyether copolymer is characterized in that it is an aromatic polyether ketone copolymer. 3 A polymer electrolyte membrane as described in ). ( 5 )The block copolymer is characterized in that it has a linker portion that connects the ionic segment and the nonionic segment. 4 A polymer electrolyte membrane as described in any of the following. ( 6 )The ionic segment is characterized in that it contains a structure represented by the following general formula (S1) (1)~( 5 A polymer electrolyte membrane as described in any of the following.

[0013] [ka]

[0014] In general formula (S1), Ar 1 to Ar 4 each independently represent a substituted or unsubstituted arylene group, and at least one of Ar 1 to Ar 4 has an ionic group. Y 1 and Y 2 each independently represent a ketone group or a protecting group that can be derived into a ketone group. * represents a bond to general formula (S1) or another structural unit.) ( 7 ) The polymer electrolyte membrane according to the above 6 , wherein the structure represented by the general formula (S1) is a structure represented by the following general formula (S2).

[0015]

Chemical formula

[0016] (In general formula (S2), Y 1 and Y 2 each independently represent a ketone group or a protecting group that can be derived into a ketone group. M 1 to M 4 each independently represent a hydrogen atom, a metal cation or an ammonium cation. n1 to n4 are each independently 0 or 1, and at least one of n1 to n4 is 1. * represents a bond to general formula (S2) or another structural unit.) ( 8 ) The polymer electrolyte membrane according to any one of the above (1) to 7 , wherein the nonionic segment contains a structure represented by the following general formula (S3).

[0017]

Chemical formula

[0018] (In general formula (S3), Ar 5 to Ar 8 each independently represent an arylene group, provided that Ar 5 to Ar8 None of them have ionic groups. 3 and Y 4 Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with the general formula (S3) or other constituent units. ( 9 )The structure represented by the general formula (S3) is characterized in that the structure represented by the general formula (S4) is as follows: 8 A polymer electrolyte membrane as described in ).

[0019] [ka]

[0020] (In general formula (S4), Y 3 and Y 4 Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with the general formula (S4) or other constituent units. ( 10 )The above (1)~( 9 A catalyst-layered electrolyte membrane characterized by being composed of a polymer electrolyte membrane as described in any of the ) ( 11 )The above (1)~( 9 A membrane electrode composite characterized by being composed of a polymer electrolyte membrane as described in any of the ) ( 12 )The above (1)~( 9 A solid polymer fuel cell characterized by being composed of a polymer electrolyte membrane as described in any of the ) ( 13 )The above (1)~( 9 A water electrolysis hydrogen generator characterized by being constructed using a polymer electrolyte membrane as described in any of the ) [Effects of the Invention]

[0021] The polymer electrolyte membrane of the present invention exhibits excellent proton conductivity even under low humidity conditions, and also boasts superior mechanical strength and physical durability. In this invention, good mechanical strength and physical durability mean good dimensional stability, and good dimensional stability means a small rate of change between dry and wet dimensions. The rate of change between dry and wet dimensions can be measured by the method described in the examples. [Brief explanation of the drawing]

[0022] [Figure 1] Figure 1 is a schematic diagram of the phase separation structure in a polymer electrolyte material. [Modes for carrying out the invention]

[0023] The embodiments of the present invention will be described in detail below, but the present invention is not limited to the embodiments described below and can be implemented with various modifications depending on the purpose and application.

[0024] The polymer electrolyte membrane of the present invention comprises a block copolymer having one or more ionic segments and one or more nonionic segments. In this invention, the nonionic segments may contain small amounts of ionic groups as long as they do not adversely affect the effects of the present invention. Hereinafter, "containing no ionic groups" and "nonionic" may be used interchangeably. In this invention, a segment is a partial structure within the block copolymer of a macromonomer used in the synthesis of the block copolymer.

[0025] The polymer electrolyte membrane of the present invention has a co-continuous phase separation structure. The phase separation structure can be controlled by the aggregation state and shape of the ionic and nonionic segments. An example of the morphology of the phase separation structure of the polymer electrolyte membrane is shown in Figure 1. Phase separation structures are broadly classified into four types: co-continuous (M1), lamellar (M2), cylindrical (M3), and sea-island (M4). The polymer electrolyte membrane of the present invention has a phase separation structure of type (M1).

[0026] In Figure 1 (M1) to (M4), the continuous phase (Phase 1) in the white area is formed by one segment selected from the ionic segment and the nonionic segment, and the continuous or dispersed phase (Phase 2) in the gray area is formed by the other segment.

[0027] The above phase separation structure is described, for example, in the Annual Review of Physical Chemistry, 41, 1990, p. 525.

[0028] By controlling the higher-order structure and shape of the ionic and nonionic segments, excellent proton conductivity can be achieved even under low humidity and low temperature conditions. In other words, the polymer electrolyte membrane having a phase separation structure of (M1) to (M4) enables the formation of continuous proton conduction channels, thereby improving proton conductivity.

[0029] In particular, when a co-continuous structure is present, a three-dimensionally continuous proton conduction channel is formed, resulting in excellent proton conductivity. Similarly, nonionic hydrophobic segments also form three-dimensionally continuous domains, providing excellent fuel barrier properties, solvent resistance, dimensional stability, mechanical strength, and physical durability.

[0030] The domains mentioned above refer to aggregates of similar segments within one or more polymer chains.

[0031] The presence of a (M1) phase separation structure in a polymer electrolyte membrane can be confirmed by the following method, specifically, if the desired image is observed, it is defined as having this structure. The method involves comparing three digital slice views, cut from the length, width, and height directions, with a three-dimensional image obtained by TEM tomography observation. For example, in a polymer electrolyte membrane containing a block copolymer having ionic and nonionic segments, if its phase separation structure is the (M1) structure, then in all three views, hydrophilic domains containing ionic segments and hydrophobic domains containing nonionic segments form an intricate continuous phase.

[0032] Here, a continuous phase refers to a phase in which, macroscopically speaking, individual domains are connected rather than isolated, although it is acceptable for some parts to be unconnected.

[0033] On the other hand, in the case of structure (M2), a pattern is shown in which hydrophilic domains containing ionic segments and hydrophobic domains containing nonionic segments are layered, so it can be distinguished from (M1), and in the case of (M3) and (M4), at least one of the domains does not form a continuous phase, so it can be distinguished from (M1).

[0034] In observing the phase separation structure, to clarify the aggregation state and contrast of ionic and nonionic segments, for example, the polymer electrolyte membrane can be immersed in a 2 wt% lead acetate aqueous solution for two days to exchange the ionic groups with lead, and then subjected to transmission electron microscopy (TEM) and TEM tomography observation.

[0035] Phase separation structures can be analyzed not only by transmission electron microscopy (TEM), but also by small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and other methods.

[0036] The ion exchange capacity of the block copolymer contained in the polymer electrolyte membrane of the present invention is greater than 2.0 meq / g and less than 3.1 meq / g, from the viewpoint of balancing proton conductivity and dimensional stability. When the ion exchange capacity exceeds 2.0 meq / g, the effects of the present invention can be fully obtained from the viewpoint of proton conductivity. The ion exchange capacity is preferably 2.1 meq / g or more. When the ion exchange capacity is less than 3.1 meq / g, the effects of the present invention can be fully obtained from the viewpoint of dimensional stability. From the viewpoint of dimensional stability, the ion exchange capacity is preferably less than 2.8 meq / g, and more preferably less than 2.7 meq / g.

[0037] The ion exchange capacity of the ionic segment is preferably high from the viewpoint of proton conductivity under low humidity conditions, and its lower limit is preferably 2.5 meq / g or more, more preferably 3 meq / g or more, and even more preferably 3.5 meq / g or more. There is no particular limit to its upper limit, but it is preferably 6.5 meq / g or less, more preferably 5 meq / g or less, and even more preferably 4.5 meq / g or less.

[0038] The ion exchange capacity of the nonionic segment is preferably low, from the viewpoint of hot water resistance, mechanical strength, dimensional stability, and physical durability, preferably 1.0 meq / g or less, more preferably 0.5 meq / g or less, and even more preferably 0.1 meq / g or less.

[0039] Here, ion exchange capacity refers to the molar amount of ion exchange groups introduced per unit dry weight of a block copolymer, polymer electrolyte material, and polymer electrolyte membrane. Ion exchange capacity can be measured by elemental analysis, neutralization titration, etc. When the ion exchange group is a sulfonic acid group, it can also be calculated from the S / C ratio using elemental analysis, but it is difficult to measure when a sulfur source other than a sulfonic acid group is included. Therefore, in this invention, ion exchange capacity is defined as the value obtained by the neutralization titration method described later.

[0040] In the polymer electrolyte membrane of the present invention, a co-continuous phase separation structure is observed when observed by TEM, and the average period size of the co-continuous phase separation structure is 100 The above average period size is less than nm. 100 When the value is less than nm, the effects of the present invention can be fully achieved in terms of mechanical strength and dimensional stability. ru. Furthermore, the average period size is preferably greater than 42 nm, more preferably 50 nm or greater, and even more preferably 55 nm or greater, from the viewpoint of further enhancing the effects of the present invention in terms of proton conductivity.

[0041] In this invention, period size refers to the period length of the domains formed by the aggregation of ionic segments and the domains formed by the aggregation of nonionic segments, and average period size refers to the period length of the domains calculated by fast Fourier transform (FFT) using the method described in the examples.

[0042] The polymer electrolyte membrane of the present invention satisfies the relationship between the average period size (nm) of the co-continuous phase separation structure and the ion exchange capacity (meq / g) of the co-continuous phase separation structure, where average period size (nm) / ion exchange capacity (meq / g) ≥ 21. High proton conductivity can be achieved by increasing the average period size. On the other hand, high dimensional stability can be achieved by keeping the ion exchange capacity below a certain value relative to the average period size. In other words, by satisfying the above relationship, a polymer electrolyte membrane is obtained that has excellent proton conductivity even under low humidity conditions, as well as excellent mechanical strength and chemical stability.

[0043] From the viewpoint of proton conductivity and dimensional stability, it is more preferable that the relationship between average period size (nm) and ion exchange capacity (meq / g) ≥ 22 is satisfied, and it is even more preferable that the relationship between average period size (nm) and ion exchange capacity (meq / g) ≥ 23 is satisfied. On the other hand, from the viewpoint of maintaining better mechanical strength and dimensional stability, it is preferable that the relationship between average period size (nm) and ion exchange capacity (meq / g) ≤ 52 is satisfied.

[0044] There are no particular limitations on the method for obtaining a polymer electrolyte membrane that satisfies the relationship between average period size (nm) and ion exchange capacity (meq / g) ≥ 21. However, as a method to expand the period size of the co-continuous phase separation structure without increasing the ion exchange capacity, examples include: (1) adjusting the temperature and humidity conditions and the drying rate of the solvent during film formation; (2) appropriately selecting the film formation solvent to obtain a desirable phase separation size according to the polarity of the block copolymer; and (3) controlling the molecular weight, i.e., the molecular chain length, of the ionic and nonionic segments that form the block copolymer.

[0045] Of these, method (3) is preferred. The molecular chain length of the ionic segment is one of the factors that influence the size of the hydrophilic domain that forms the proton conduction channel in the cocontinuous phase separation structure. From the viewpoint of expanding the hydrophilic domain size, the number-average molecular weight Mn1 of the ionic segment is preferably greater than 45,000. Mn1 is more preferably greater than 50,000, even more preferably greater than 60,000, and most preferably greater than 80,000. There is no particular upper limit to Mn1, but from the viewpoint of further improving the dimensional stability of the polymer electrolyte membrane at high temperature and high humidity, it is preferably less than 150,000.

[0046] The molecular chain length of the nonionic segment is one of the factors that influence the size of the hydrophobic domains, which contribute to crystallinity and water resistance. The number-average molecular weight Mn2 of the nonionic segment is preferably 10,000 or more, and more preferably 15,000 or more. There is no particular upper limit to Mn2, but from the viewpoint of polymerizability, it is preferably 50,000 or less.

[0047] As a method for adjusting Mn1 to the desired molecular weight, the method is not particularly limited as long as the desired molecular weight can be achieved. For example, this could involve synthesizing a segment with a number-average molecular weight of the desired molecular weight by an aromatic nucleophilic substitution reaction or a coupling reaction, or synthesizing a polymer having a number-average molecular weight smaller than the desired number-average molecular weight, and then using this polymer as the constituent unit of the segment and linking the polymers together with a linker (L1). The method of linking polymers together with a linker is particularly preferred because it has fewer process constraints. Suitable specific examples of the linker (L1) include decafluorobiphenyl, hexafluorobenzene, 4,4'-difluorodiphenylsulfone, 2,6-difluorobenzonitrile, etc., but the present invention is not limited to these.

[0048] The block copolymer contained in the polymer electrolyte membrane of the present invention is preferably a hydrocarbon copolymer from the viewpoint of mechanical strength. In the present invention, a hydrocarbon copolymer means a copolymer other than a perfluoro copolymer. Furthermore, a block copolymer being an aromatic hydrocarbon copolymer means that at least one of the ionic segment and the nonionic segment contained in the block copolymer is an aromatic hydrocarbon polymer.

[0049] The block copolymer contained in the polymer electrolyte membrane of the present invention is preferably an aromatic hydrocarbon copolymer from the viewpoint of crystallinity, dimensional stability, and mechanical strength. An aromatic hydrocarbon copolymer is a copolymer mainly composed of aromatic rings.

[0050] In the present invention, the aromatic rings contained in the aromatic hydrocarbon copolymer may include not only hydrocarbon aromatic rings but also heterocycles. Furthermore, some aliphatic units may constitute the copolymer together with the aromatic ring units. Specific examples of polymers that are constituent elements of the aromatic hydrocarbon copolymer include polymers having a structure selected from polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene polymers, polyarylene ketone, polyether ketone, polyarylene phosphine foxide, polyetherphosphine foxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, and polyimide sulfone in the main chain together with the aromatic rings.

[0051] Among these, aromatic polyether polymers are preferred from the viewpoint of cost and polymerizability. In other words, it is preferable that the aromatic hydrocarbon copolymer is an aromatic polyether copolymer.

[0052] Aromatic polyether polymers are polymers primarily composed of aromatic rings, in which at least ether bonds are included in the repeating units as a way in which aromatic ring units are linked. Examples of aromatic polyether polymer structures include, but are not limited to, aromatic polyethers, aromatic polyether ketones, aromatic polyether ether ketones, aromatic polyether ketone ketones, aromatic polyether ketone ketones, aromatic polyether ketone ether ketone ketones, aromatic polyether imide, and aromatic polyether sulfone.

[0053] Among these, aromatic polyether ketone polymers and polyether sulfone polymers are preferred in terms of chemical stability and cost, and aromatic polyether ketone polymers are most preferred in terms of mechanical strength, dimensional stability, and physical durability. In other words, it is most preferable that the aromatic hydrocarbon copolymer is an aromatic polyether ketone copolymer.

[0054] Aromatic polyetherketone polymers are polymers primarily composed of aromatic rings, in which the repeating units contain at least ether bonds and ketone bonds as a way in which the aromatic ring units are linked.

[0055] Aromatic polyethersulfone polymers are polymers mainly composed of aromatic rings in which at least ether bonds and sulfone bonds are included in the manner in which the aromatic ring units are linked within the repeating unit.

[0056] In the polymer electrolyte membrane of the present invention, it is preferable from the viewpoint of mechanical strength and dimensional stability that the ionic segment contained in the block copolymer contains a structure represented by the following general formula (S1).

[0057] [ka]

[0058] In general formula (S1), Ar 1 ~Ar 4 Each of these independently represents a substituted or unsubstituted arylene group, and Ar 1 ~Ar 4 At least one of them has an ionic group. 1 and Y 2 Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with general formula (S1) or other constituent units.

[0059] Here, Ar 1 ~Ar 4Preferred aromatic rings include, but are not limited to, hydrocarbon arylene groups such as phenylene groups, naphthylene groups, biphenylene groups, and fluoroorangeyl groups, and heteroarylene groups such as pyridinediyl, quinoxalinediyl, and thiophenediyl.

[0060] In the present invention, the ionic group is preferably a group of atoms having a negative charge, and preferably one that has proton exchange ability. Suitable functional groups include sulfonic acid groups, sulfonimide groups, sulfate groups, phosphonic acid groups, phosphoric acid groups, and carboxylic acid groups, as shown below.

[0061] [ka]

[0062] Such ionic groups include cases where the above functional groups (f1) to (f7) are salts. Examples of cations that form such salts include any metal cation, NR4 + Examples include (where R is any organic group). There are no particular restrictions on the metal cation, but Na, K, and Li are preferred because they are inexpensive and can be easily proton-substituted.

[0063] These ionic groups can be present in two or more types in the block copolymer, and the combination of ionic groups is appropriately determined depending on the polymer structure and other factors. In particular, from the viewpoint of high proton conductivity, it is more preferable to have at least a sulfonic acid group, a sulfonimide group, and a sulfate group, and from the viewpoint of raw material cost, it is most preferable to have a sulfonic acid group.

[0064] In the present invention, the block copolymer whose structure is represented by general formula (S1) is preferably the structure represented by general formula (P1) below, from the viewpoint of dimensional stability and raw material availability, and whose structure is preferably the structure represented by general formula (S2) below, from the viewpoint of raw material availability and polymerizability.

[0065] [ka]

[0066] In general formulas (P1) and (S2), Y 1 and Y 2 Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. 1 ~M 4 Each of the following independently represents a hydrogen atom, a metal cation, or an ammonium cation. Each of n1 to n4 is independently 0 or 1, and at least one of n1 to n4 is 1. * represents a bond with the general formula (P1)(S2) or other constituent units.

[0067] Furthermore, from the standpoint of raw material availability and polymerizability, it is most preferable that n1=1, n2=1, n3=0, n4=0 or n1=0, n2=0, n3=1, n4=1.

[0068] The content of the constituent unit represented by general formula (S1) contained in the ionic segment is more preferably 20 mol% or more, even more preferably 50 mol% or more, and most preferably 80 mol% or more.

[0069] Examples of ionic monomers used to synthesize the ionic segments described above include aromatic active dihalide compounds. Using compounds obtained by introducing an ionic acid group into an aromatic active dihalide compound is preferable as the aromatic active dihalide compound used in the ionic segment due to its chemical stability, manufacturing cost, and the ability to precisely control the amount of ionic group. Suitable specific examples of monomers having a sulfonic acid group as an ionic group include, but are not limited to, 3,3'-disulfonate-4,4'-dichlorodiphenylsulfone, 3,3'-disulfonate-4,4'-difluorodiphenylsulfone, 3,3'-disulfonate-4,4'-dichlorodiphenylketone, 3,3'-disulfonate-4,4'-difluorodiphenylketone, 3,3'-disulfonate-4,4'-dichlorodiphenylphenylphosphine oxide, and 3,3'-disulfonate-4,4'-difluorodiphenylphenylphosphine oxide.

[0070] From the viewpoint of proton conductivity and hydrolysis resistance, a sulfonic acid group is the most preferred ionic group, but monomers having the above-mentioned ionic group may also have other ionic groups.

[0071] Among the monomers having sulfonic acid groups described above, 3,3'-disulfonate-4,4'-dichlorodiphenyl ketone and 3,3'-disulfonate-4,4'-difluorodiphenyl ketone are more preferred in terms of chemical stability and physical durability, and 3,3'-disulfonate-4,4'-difluorodiphenyl ketone is most preferred in terms of polymerization activity.

[0072] As monomers having ionic groups, ionic segments synthesized using 3,3'-disulfonate-4,4'-dichlorodiphenyl ketone and 3,3'-disulfonate-4,4'-difluorodiphenyl ketone contain the constituent units represented by the following general formula (p1) and are preferably used. These aromatic polyether polymers, in addition to the high crystallinity properties of ketone groups, are components with superior heat and water resistance compared to sulfone groups, and are therefore more preferably used as effective components for materials with excellent dimensional stability, mechanical strength, and physical durability under high temperature and high humidity conditions. When polymerizing these sulfonic acid groups, it is preferable that the sulfonic acid groups are salts with monovalent cation species. The monovalent cation species may be sodium, potassium, other metal species, or various amines, and is not limited to these. These aromatic active dihalide compounds can be used individually, but it is also possible to use multiple aromatic active dihalide compounds in combination.

[0073] [ka]

[0074] (In general formula (p1), M 1 and M 2 (where a1 and a2 represent integers from 1 to 4, where a1 represents hydrogen, a metal cation, or an ammonium cation.) Furthermore, the density of ionic groups in aromatic active dihalide compounds can be controlled by copolymerizing compounds with and without ionic groups. However, from the viewpoint of ensuring the continuity of the proton conduction path, it is more preferable not to copolymerize aromatic active dihalide compounds without ionic groups into the ionic segment.

[0075] More suitable examples of aromatic active dihalide compounds that do not have ionic groups include 4,4'-dichlorodiphenyl sulfone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorodiphenyl ketone, 4,4'-difluorodiphenyl ketone, 4,4'-dichlorodiphenylphenylphosphine oxide, 4,4'-difluorodiphenylphenylphosphine oxide, 2,6-dichlorobenzonitrile, and 2,6-difluorobenzonitrile. Among these, 4,4'-dichlorodiphenyl ketone and 4,4'-difluorodiphenyl ketone are more preferred in terms of imparting crystallinity, mechanical strength, physical durability, and hot water resistance, while 4,4'-difluorodiphenyl ketone is most preferred in terms of polymerization activity. These aromatic active dihalide compounds can be used individually, but it is also possible to use multiple aromatic active dihalide compounds in combination.

[0076] A polymer electrolyte material synthesized using 4,4'-dichlorodiphenyl ketone and 4,4'-difluorodiphenyl ketone as aromatic active dihalide compounds further contains the constituent units represented by the following general formula (p2), and is preferably used. These constituent units serve as components that impart intermolecular cohesive force and crystallinity, resulting in a material with excellent dimensional stability, mechanical strength, and physical durability under high temperature and high humidity conditions, and is therefore preferably used.

[0077] [ka]

[0078] (The constituent units represented by general formula (p2) may be substituted as desired, but ionic groups are not included.) Furthermore, aromatic diphenol compounds are examples of nonionic monomers used to synthesize ionic segments, and aromatic diphenol compounds having a protecting group, as described later, are particularly preferred. The monomers used to synthesize ionic segments have been described above.

[0079] In the polymer electrolyte membrane of the present invention, it is preferable that the nonionic segment contained in the block copolymer contains a structure represented by the following general formula (S3) from the viewpoint of mechanical strength and dimensional stability.

[0080] [ka]

[0081] In general formula (S3), Ar 5 ~Ar 8 Each of these independently represents an arylene group. However, Ar 5 ~Ar 8 None of them have ionic groups. 3 and Y 4 Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with the general formula (S3) or other constituent units.

[0082] Here, Ar 5 ~Ar 8 Preferred aromatic rings include, but are not limited to, hydrocarbon arylene groups such as phenylene groups, naphthylene groups, biphenylene groups, and fluoroorangeyl groups, and heteroarylene groups such as pyridinediyl, quinoxalinediyl, and thiophenediyl.

[0083] In the block copolymer of the present invention, it is preferable from the viewpoint of raw material availability that the structure represented by general formula (S3) contains the structure represented by the following formula (P2). In particular, it is even more preferable from the viewpoint of mechanical strength due to crystallinity, dimensional stability, and physical durability that the copolymer contains the constituent unit represented by the following formula (S4).

[0084] [ka]

[0085] In general formulas (P2) and (S4), Y 3 and Y 4Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with general formulas (P2) and (S4) or other constituent units.

[0086] The content of the structures represented by the general formulas (S3) or (P2) and (S4) in the nonionic segment is preferably higher, more preferably 20 mol% or more, even more preferably 50 mol% or more, and most preferably 80 mol% or more. When the content is 20 mol% or more, the effects of the present invention on mechanical strength, dimensional stability, and physical durability due to crystallinity are excellent.

[0087] The block copolymer used in the present invention is preferably composed of a block copolymer having an ionic segment containing a structural unit represented by the general formula (S1) and a nonionic segment containing a structural unit represented by the general formula (S3).

[0088] Nonionic segments are crystalline segments when they contain a structural unit represented by the general formula (S3). Block copolymers containing such nonionic segments can be produced by molding a block copolymer precursor in which protecting groups have been introduced to at least the nonionic segments, and then deprotecting at least a portion of the protecting groups contained in the molded article. Block copolymers tend to have poorer processability than random copolymers due to the crystallization of the polymer that forms domains; therefore, it is preferable to introduce protecting groups to at least the nonionic segments to improve processability, and it is also preferable to introduce protecting groups to the ionic segments if the processability is poor.

[0089] Examples of such protecting groups include, preferably, those containing at least one selected from the following general formulas (P3) and (P4).

[0090] [ka]

[0091] (In equations (P3) and (P4), Ar 11 ~Ar 14 R is any divalent arylene group. 1 and R 2 H is at least one group selected from alkyl groups, R 3 represents any alkylene group, E represents O or S, and each may represent two or more different groups. The groups represented by formulas (P3) and (P4) may be substituted as desired. In particular, in terms of the odor, reactivity, and stability of the compound, the method in which E is O in the general formulas (P3) and (P4), that is, the method of protecting / deprotecting the ketone moiety with the ketal moiety, is the most preferred.

[0092] R in the general formula (P3) 1 and R 2 In terms of stability, alkyl groups are more preferable, even more preferably alkyl groups having 1 to 6 carbon atoms, and most preferably alkyl groups having 1 to 3 carbon atoms. Also, R in general formula (P4) 3 In terms of stability, an alkylene group having 1 to 7 carbon atoms is more preferable, and most preferably an alkylene group having 1 to 4 carbon atoms. 3 Specific examples include, but are not limited to, -CH2CH2-, -CH(CH3)CH2-, -CH(CH3)CH(CH3)-, -C(CH3)2CH2-, -C(CH3)2CH(CH3)-, -C(CH3)2O(CH3)2-, -CH2CH2CH2-, -CH2C(CH3)2CH2-, etc.

[0093] Ar in the above general formulas (P3) and (P4) 11 ~Ar 14 Preferred organic groups are phenylene groups, naphthylene groups, or biphenylene groups. These may be optionally substituted. As for aromatic polyether polymers, due to their solubility and the ease of obtaining raw materials, Ar in the general formula (P4) is preferred. 13 and Ar 14 It is more preferable that both are phenylene groups, and most preferably Ar 13and Ar 14 Both are p-phenylene groups.

[0094] One method for protecting the ketone moiety with a ketal involves reacting a precursor compound having a ketone group with a monofunctional and / or bifunctional alcohol in the presence of an acid catalyst. For example, it can be produced by reacting the ketone precursor 4,4'-dihydroxybenzophenone with a monofunctional and / or bifunctional alcohol in a solvent such as an aliphatic or aromatic hydrocarbon in the presence of an acid catalyst such as hydrogen bromide. The alcohol is an aliphatic alcohol having 1 to 20 carbon atoms.

[0095] An improved method for producing ketal monomers involves reacting a ketone precursor, 4,4'-dihydroxybenzophenone, with a difunctional alcohol in the presence of an alkyl orthoester and a solid catalyst.

[0096] The method for deprotecting at least a portion of the ketone moiety protected with ketal to create the ketone moiety is not particularly limited. The deprotection reaction can be carried out in the presence of water and acid under heterogeneous or homogeneous conditions, but from the viewpoint of mechanical strength, physical durability and solvent resistance, a method of acid treatment after forming into a film is more preferable. Specifically, deprotection can be carried out by immersing the formed film in an aqueous hydrochloric acid solution or an aqueous sulfuric acid solution, and the concentration of the acid and the temperature of the aqueous solution can be appropriately selected.

[0097] The required weight ratio of acidic aqueous solution to polymer is preferably 1 to 100 times, but even larger amounts of water can be used. The acid catalyst is preferably used at a concentration of 0.1 to 50% by weight of the present water. Suitable acid catalysts include strong mineral acids such as hydrochloric acid, nitric acid, fluorosulfonic acid, and sulfuric acid, and strong organic acids such as p-toluenesulfonic acid and trifluoromethanesulfonic acid. The amount of acid catalyst and excess water, reaction pressure, etc., can be appropriately selected depending on the polymer film thickness, etc.

[0098] For example, a film with a thickness of 50 μm can be almost completely deprotected by immersing it in an acidic aqueous solution, such as a 6N hydrochloric acid aqueous solution, and heating it at 95°C for 1 to 48 hours. Alternatively, immersion in a 1N hydrochloric acid aqueous solution at 25°C for 24 hours can also deprotect most of the protecting groups. However, the deprotection method is not limited to these methods; deprotection can also be performed using acidic gases, organic acids, or heat treatment.

[0099] Even when the aromatic polyether polymer includes bonding modes other than ether bonding, such as direct bonding, it is more preferable for the protective group to be introduced to be located in the aromatic ether polymer portion, from the viewpoint of improving processability.

[0100] Specifically, for example, aromatic polyether polymers containing the constituent units represented by the general formulas (P3) and (P4) can be synthesized by aromatic nucleophilic substitution reaction with aromatic active dihalide compounds, using compounds represented by the following general formulas (P3-1) and (P4-1) as aromatic diphenol compounds, respectively. The constituent units represented by the general formulas (P3) and (P4) may originate from either the aromatic diphenol compound or the aromatic active dihalide compound, but it is more preferable to use those derived from the aromatic diphenol compound, considering the reactivity of the monomer.

[0101] [ka]

[0102] (In general formulas (P3-1) and (P4-1), Ar 11 ~Ar 14 R is any divalent arylene group. 1 and R 2 H is at least one group selected from alkyl groups, R 3 is any alkylene group, and E represents O or S. The compounds represented by general formulas (P3-1) and (P4-1) may be optionally substituted. The preferred protecting groups have been described above.

[0103] The block copolymer contained in the polymer electrolyte membrane of the present invention preferably contains one or more linker regions that connect the ionic segment and the nonionic segment. In the present invention, a linker is defined as a region that connects the ionic segment and the nonionic segment and has a different chemical structure from the ionic segment or the nonionic segment. This linker is sometimes called linker (L2) to distinguish it from the aforementioned linker (L1).

[0104] This linker (L2) links different segments while suppressing randomization of the copolymer by ether exchange reactions, segment cleavage, and other side reactions that may occur during copolymer synthesis. Therefore, by using compounds that provide such linkers as raw materials, block copolymers can be obtained without reducing the molecular weight of each segment.

[0105] Suitable specific examples of the linker (L2) include decafluorobiphenyl, hexafluorobenzene, 4,4'-difluorodiphenylsulfone, and 2,6-difluorobenzonitrile, but the present invention is not limited to these.

[0106] The polymer electrolyte membrane of the present invention preferably has crystallinity while possessing a phase-separated structure, from the viewpoint of dimensional stability and mechanical strength. Generally, dimensional stability and mechanical strength are negatively correlated with ion exchange capacity, but the polymer electrolyte membrane of the present invention achieves high dimensional stability when compared to polymer electrolyte membranes with similar ion exchange capacity due to its crystallinity.

[0107] The presence or absence of crystallinity can be confirmed by differential scanning calorimetry (DSC) or wide-angle X-ray diffraction. Here, "having crystallinity" means that the heat of crystallization of the block copolymer measured by differential scanning calorimetry is 0.1 J / g or more, or the degree of crystallinity of the block copolymer measured by wide-angle X-ray diffraction is 0.5% or more. In other words, in this invention, "having crystallinity" means that the polymer can crystallize when heated, has properties that allow it to crystallize, or has already crystallized. Furthermore, an amorphous polymer means that it is not a crystalline polymer, or that it is a polymer in which crystallization does not substantially proceed. Therefore, even if it is a crystalline polymer, if crystallization has not progressed sufficiently, the state of the polymer at that point may be amorphous.

[0108] The polymer electrolyte membrane of the present invention can be formed from a solution state or from a molten state, in which it has a protecting group such as a ketal. In the former case, for example, an example is to dissolve the polymer electrolyte material in a solvent such as N-methyl-2-pyrrolidone, cast the solution onto a glass plate or the like, and then remove the solvent to form a film.

[0109] The solvent used for film formation can be any solvent that dissolves the block copolymer and can then be removed. For example, aprotic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, and hexamethylphosphontriamide are preferred; ester solvents such as γ-butyrolactone and butyl acetate are preferred; carbonate solvents such as ethylene carbonate and propylene carbonate are preferred; alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether are preferred; or alcohol solvents such as isopropanol, water, and mixtures thereof are preferred. However, aprotic polar solvents have the highest solubility and are therefore preferred. In addition, it is preferable to add crown ethers such as 18-crown-6 to increase the solubility of the ionic segment.

[0110] A preferred method for obtaining a tough membrane is to remove foreign matter present in the polymer electrolyte solution by subjecting the polymer solution, which has been prepared to the required solid content concentration, to filtration at atmospheric pressure or by pressure filtration. The filter material used here is not particularly limited, but glass filters or metallic filters are preferred. In this filtration, the minimum pore size of the filter through which the polymer solution passes is preferably 1 μm or less.

[0111] One method for converting the block copolymer used in the present invention into a polymer electrolyte membrane is, for example, to fabricate a membrane composed of the block copolymer using the above method, and then deprotect at least a portion of the protected portion with a protecting group. For example, if the protecting group has a ketal moiety, at least a portion of the ketone moiety protected by the ketal is deprotected to become a ketone moiety. This method makes it possible to fabricate a solution membrane of a block copolymer with poor solubility, and to achieve both proton conductivity, dimensional stability, mechanical strength, and physical durability. Alternatively, after forming the electrolyte membrane with the ionic groups forming salts with alkali metal or alkaline earth metal cations, a step may be performed to exchange the alkali metal or alkaline earth metal cations for protons. This step is preferably a step of contacting the formed membrane with an acidic aqueous solution, and more preferably a step of immersing the formed membrane in an acidic aqueous solution. In this step, protons in the acidic aqueous solution are replaced by cations ionically bonded to the ionic groups, and residual water-soluble impurities, residual monomers, solvents, and residual salts are simultaneously removed.

[0112] The acidic aqueous solution is not particularly limited, but it is preferable to use sulfuric acid, hydrochloric acid, nitric acid, acetic acid, trifluoromethanesulfonic acid, methanesulfonic acid, phosphoric acid, citric acid, etc. The temperature and concentration of the acidic aqueous solution should be determined as appropriate, but from the viewpoint of productivity, it is preferable to use a sulfuric acid aqueous solution with a concentration of 3% to 30% by mass at a temperature of 0°C to 80°C.

[0113] In the present invention, the film thickness of the polymer electrolyte membrane is preferably 1 μm or more to obtain mechanical strength and physical durability of a membrane that can withstand practical use, and preferably 2000 μm or less to reduce membrane resistance, i.e., to improve power generation performance. A more preferable range for film thickness is 3 μm to 200 μm. The film thickness can be controlled by the solution concentration or the coating thickness on the substrate.

[0114] Furthermore, the polymer electrolyte membrane in the present invention may contain additives such as crystallization nucleating agents, plasticizers, stabilizers, antioxidants, or mold release agents commonly used in polymer compounds, to the extent that they do not contradict the objectives of the present invention.

[0115] Furthermore, the polymer electrolyte membrane of the present invention may contain various polymers, elastomers, fillers, fine particles, various additives, etc., to improve mechanical strength, thermal stability, processability, etc., within a range that does not adversely affect the aforementioned properties. The polymer electrolyte membrane may also be reinforced with a microporous membrane, nonwoven fabric, mesh, etc.

[0116] The polymer electrolyte membrane of the present invention is applicable to a variety of uses. For example, it can be used in medical applications such as artificial skin, filtration applications, ion exchange resin applications such as chlorine-resistant reverse osmosis membranes, various structural material applications, electrochemical applications, humidifying membranes, anti-fogging membranes, antistatic membranes, deoxygenation membranes, solar cell membranes, and gas barrier membranes. Among these, it is most preferably used in various electrochemical applications. Examples of electrochemical applications include polymer electrolyte fuel cells, redox flow batteries, water electrolyzers, chloro-alkali electrolyzers, electrochemical hydrogen pumps, and water electrolysis hydrogen generators.

[0117] In polymer electrolyte fuel cells, electrochemical hydrogen pumps, and water electrolysis hydrogen generators, polymer electrolyte membranes are used in structures in which a catalyst layer, an electrode substrate, and a separator are sequentially laminated on both sides. Of these, those in which catalyst layers are laminated on both sides of the electrolyte membrane (i.e., a layer configuration of catalyst layer / electrolyte membrane / catalyst layer) are called catalyst-coated electrolyte membranes (CCMs), and those in which a catalyst layer and a gas diffusion substrate are sequentially laminated on both sides of the electrolyte membrane (i.e., a layer configuration of gas diffusion substrate / catalyst layer / electrolyte membrane / catalyst layer / gas diffusion substrate) are called membrane electrode composites (MEAs). The polymer electrolyte membrane of the present invention is particularly suitable for use as a polymer electrolyte membrane constituting such CCMs and MEAs. [Examples]

[0118] (1) Molecular weight of polymer The number-average molecular weight and weight-average molecular weight of polymers were measured by GPC. A Tosoh Corporation HLC-8022GPC integrated system with a UV detector and differential refractometer was used, along with a Tosoh Corporation TSKgelGuardColumnSuperH-H (4.6 mm inner diameter, 3.5 cm length) as the guard column and two Tosoh Corporation TSKgelSuperHM-H (6.0 mm inner diameter, 15 cm length) GPC columns. Measurements were taken in N-methyl-2-pyrrolidone solvent (containing 10 mmol / L lithium bromide) at a sample concentration of 0.1 wt%, a flow rate of 0.2 mL / min, a temperature of 40°C, and a measurement wavelength of 265 nm. The number-average molecular weight and weight-average molecular weight were then determined using standard polystyrene equivalents.

[0119] (2) Ion exchange capacity (IEC) The measurement was performed using the neutralization titration method described in 1] to 4] below. Three measurements were taken, and the average value was calculated. 1) After proton substitution and thorough washing with pure water, the moisture from the block copolymer was wiped off, and then vacuum-dried at 100°C for more than 12 hours, and the dry weight was determined. 2) 50 mL of 5 wt% sodium sulfate aqueous solution was added to the block copolymer and allowed to stand for 12 hours for ion exchange. 3] The resulting sulfuric acid was titrated using a 0.01 mol / L sodium hydroxide aqueous solution. A commercially available 0.1 w / v% titration phenolphthalein solution was added as an indicator, and the endpoint was defined as the point at which the solution turned a pale reddish-purple. 4]IEC was calculated using the following formula. IEC (meq / g) = [Concentration of sodium hydroxide solution (mmol / mL) × Droplet volume (mL)] / Dry weight of sample (g).

[0120] (3) Change rate of dimensions when wet A film-like sample was taken measuring 3 mm x 20 mm and placed in the sample holder of a thermomechanical analyzer TMA / SS6100 (manufactured by Hitachi High-Tech Science Co., Ltd.) equipped with a temperature and humidity control furnace, with the longer side of the sample facing the measurement direction. The sample was allowed to stabilize in the furnace at 23°C and 50% RH for 1 hour, and the length of this sample was set as the zero point. The furnace temperature was fixed at 23°C, and the humidity was adjusted to 30% RH (dry conditions) over 30 minutes and held for 20 minutes. Next, the humidity was adjusted to 90% RH (humidified conditions) over 30 minutes. This dry-wet cycle (30% RH - 90% RH) was considered one cycle, and the difference between the dimensional change rate (%) at 30% RH and the dimensional change rate (%) at 90% RH after 10 cycles was defined as the dry-wet dimensional change rate (%).

[0121] The dimensional change rate between dry and wet surfaces is preferably 7.0% or less, more preferably 6.5% or less, and particularly preferably 6.0% or less.

[0122] (4) Observation of phase separation structure using a transmission electron microscope (TEM) The sample pieces were immersed in a 2 wt% lead acetate aqueous solution as a staining agent and left at 25°C for 72 hours. The stained samples were removed and embedded in epoxy resin. Using an ultramicrotome, 80 nm thin sections were cut at room temperature, and the obtained sections were collected on a Cu grid and subjected to TEM observation. Observation was performed at an accelerating voltage of 100 kV, and images were taken at magnifications of ×20,000 and ×40,000. The instrument used was an HT7700 (Hitachi High-Tech Corporation). In addition, the TEM images were subjected to a Fast Fourier Transform (FFT), and the spatial frequency in the TD direction was measured from the resulting ring-shaped FFT pattern, from which the average period length of phase separation was calculated. The spatial frequency was measured from the center of the image to the center of the ring thickness. FFT and measurement were performed using a DigitalMicrograph (Gatan).

[0123] (5) Observation of phase separation structure by transmission electron microscopy (TEM) tomography The thin section samples prepared by the method described in (4) above were mounted on a collodion film, and observations were performed according to the following conditions. Equipment: Field emission electron microscope (HRTEM), JEOL Ltd. JEM 2100F Image acquisition: DigitalMicrograph (Gatan Corporation) System: Marker Method Acceleration voltage: 200kV Magnification: 30,000x Tilt angle: +60° to -62° Reconstruction resolution: 0.71nm / pixel.

[0124] Three-dimensional reconstruction was performed using the marker method. Au colloidal particles attached to a collodion film were used as alignment markers during three-dimensional reconstruction. Using the markers as a reference, the sample was tilted in 1° increments within the range of +61° to -62°, and TEM images were acquired from a series of 124 TEM images. CT reconstruction was performed based on these images, and the three-dimensional phase separation structure was observed.

[0125] (6) Proton conductivity An isopropanol-based carbon paste (G7711, manufactured by EM Japan Co., Ltd.) was applied to the platinum electrode of the cell, and a diffusion layer electrode (ELAT GDL 140-HT, manufactured by E-TEK) cut to 18 mm x 6 mm was attached. An electrolyte membrane cut to 30 mm x 8 mm was placed between the electrodes of the cell, and the cell was fastened at 1 MPa and placed inside the chamber of the MTS740. The proton resistance in the film thickness direction of the electrolyte membrane was evaluated using the MTS740 film resistance measurement system (manufactured by Scribner). The MTS740 housed the cell in a temperature-controlled chamber, and air gas was supplied into the chamber via a mass flow controller through a humidifier. A frequency response analyzer PSM1735 (manufactured by Newtons4th) was connected to the cell, and the resistance could be determined by sweeping the AC signal from 1 MHz to 1 kHz.

[0126] The MTS740 and PSM1735 can be connected to a PC and controlled by software. After setting the chamber temperature to 80°C, 90%RH air gas was supplied and held for 1 hour to sufficiently moisten the electrolyte membrane. Then, 20%RH air was supplied to dry it, and 30%RH air was supplied and held for 30 minutes, and the resistance was measured. During this time, the frequency was swept from 1MHz to 1kHz. Then, 80%RH air was supplied and held for 30 minutes, and the resistance was measured again. A Cole-Cole plot was created from the measured resistance data. Since the frequency band around 1MHz is affected by the inductance component of the cable connecting the cell and the PSM1735, the value on the real axis at 200kHz, where this effect is minimal, was used as the resistance value (Ω). The proton conductivity when 30%RH air was supplied was defined as low-humidified proton conductivity, and the proton conductivity when 80%RH air was supplied as high-humidified proton conductivity. The proton conductivity was calculated using the measured resistance values ​​with the following formula. Proton conductivity (mS / cm) = 1 / (resistance (Ω) × active area (cm) 2 ) / Sample thickness (cm). The low-humidified proton conductivity is preferably 0.90 mS / cm or higher, more preferably 1.00 mS / cm or higher, and particularly preferably 1.10 mS / cm or higher. The high-humidified proton conductivity is preferably 9.50 mS / cm or higher, more preferably 11.00 mS / cm or higher, and particularly preferably 12.00 mS / cm or higher.

[0127] (7) Measurement of crystallization calorimetry by differential scanning calorimetry (DSC) A 10 mg polymer electrolyte membrane sample was pre-dried in a DSC instrument at 110°C for 3 hours. Then, without removing the sample from the DSC instrument, the temperature was raised to 200°C under the following conditions, and temperature-modulated differential scanning calorimetry was performed during the heating phase. DSC device: DSC7000X (manufactured by Hitachi High-Tech Corporation) Measurement temperature range: 30℃~200℃ Temperature control: AC temperature control Heating rate: 2°C / min Amplitude: ±3℃ Applied frequency: 0.02Hz Sample pan: Aluminum crimped pan Measurement, pre-drying atmosphere: 100 mL / min nitrogen Pre-drying: 110°C, 3 hours.

[0128] (8) Crystallinity measurement by wide-angle X-ray diffraction (XRD) The polymer electrolyte membrane sample was placed in a diffractometer, and X-ray diffraction measurements were performed under the following conditions. X-ray diffractometer: Bruker D8 ADVANCE X-ray: Cu-Kα X-ray output: 40kV-40mA Optical system: Concentration optical system Scan speed: 2θ = 2 / min Scanning method: 2θ-θ Scan range: 2θ = 5~60° Slits: Divergent slit -1 / 2°, Receiving slit -0.15mm, Scattering slit -1 / 2° The degree of crystallinity is determined by separating each component through profile fitting, and each component The diffraction angle and integrated intensity were determined, and the obtained crystalline peak and the integrated intensity of the amorphous halo were used to determine the diffraction angle. The degree of crystallinity was calculated using the formula shown below.

[0129] Crystallinity (%) = Sum of integrated intensities of all crystalline peaks / Sum of integrated intensities of all crystalline peaks and amorphous halos × 100.

[0130] In the following synthesis examples 1-3, the structure of the obtained compound is 1 The purity was confirmed by 1H-NMR. Purity was quantitatively analyzed by capillary electrophoresis (organic substances) and ion chromatography (inorganic substances).

[0131] Synthesis Example 1 (Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP), represented by the following formula (G1)) In a 500 ml flask equipped with a stirrer, thermometer, and distillation tube, 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate, and 0.50 g of p-toluenesulfonic acid monohydrate were charged to form a solution. The solution was then kept warm and stirred at 78-82°C for 2 hours. The internal temperature was then gradually increased to 120°C and maintained at 120°C until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling the reaction solution to room temperature, it was diluted with ethyl acetate. The organic layer was washed with 100 ml of 5% potassium carbonate aqueous solution, and after liquid-liquid extraction, the solvent was removed by distillation. 80 ml of dichloromethane was added to the residue to precipitate crystals, which were filtered and dried to obtain 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane. The purity was 99.9%.

[0132] [ka]

[0133] Synthesis Example 2 (Synthesis of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone represented by the following formula (G2)) 109.1 g of 4,4'-difluorobenzophenone (Aldrich reagent) was reacted in 150 mL of fuming sulfuric acid (50% SO3) (Wako Pure Chemical Industries reagent) at 100°C for 10 hours. Then, the mixture was gradually added to a large volume of water, neutralized with NaOH, and 200 g of sodium chloride (NaCl) was added to precipitate the product. The resulting precipitate was filtered and recrystallized in an aqueous ethanol solution to obtain disodium-3,3'-disulfonate-4,4'-difluorobenzophenone. The purity was 99.3%.

[0134] [ka]

[0135] Synthesis Example 3 (Synthesis of 3,3'-disulfonate sodium salt-4,4'-difluorodiphenyl sulfone, represented by the formula (G3) below) 109.1 g of 4,4-difluorodiphenylsulfone (Aldrich reagent) was reacted in 150 mL of fuming sulfuric acid (50% SO3) (Wako Pure Chemical Industries reagent) at 100°C for 10 hours. Then, the mixture was gradually added to a large volume of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the product. The precipitate was filtered and recrystallized in an aqueous ethanol solution to obtain 3,3'-disulfonate sodium salt-4,4'-difluorodiphenylsulfone. The purity was 99.3%.

[0136] [ka]

[0137] Example 1 (Synthesis of nonionic oligomer a1 represented by the general formula (G4) below) In a 2,000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.83 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and 21.38 g of 4,4'-difluorobenzophenone (Aldrich reagent, 98 mmol) were added. After purging the apparatus with nitrogen, 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene were added. Dehydration was performed at 150°C, followed by heating to remove the toluene, and polymerization was carried out at 170°C for 3 hours. Reprecipitation and purification in a large amount of methanol were performed to obtain the terminal hydroxyl derivative of nonionic oligomer a1. The number-average molecular weight of this terminal hydroxyl derivative of nonionic oligomer a1 was 20,000. In a 500 mL three-necked flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 20.0 g (1 mmol) of the terminal hydroxyl group of the nonionic oligomer a1 were added. After purging the apparatus with nitrogen, 100 mL of NMP and 30 mL of toluene were added, and the mixture was dehydrated at 100 °C. The temperature was then raised to remove the toluene. Furthermore, 1.1 g of hexafluorobenzene (Aldrich reagent, 6 mmol) was added, and the reaction was carried out at 105 °C for 12 hours. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain nonionic oligomer a1 (terminal: fluoro group) represented by the following formula (G4). The number-average molecular weight of this nonionic oligomer a1 was 21,000.

[0138] [ka]

[0139] (Synthesis of ionic oligomer a2 represented by the following formula (G5)) In a 2,000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 27.64 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.91 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.31 g of 4,4'-biphenol (Aldrich reagent, 50 mmol), 41.60 g (98.5 mmol) of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2, and 26.40 g of 18-crown-6 (Wako Pure Chemical Industries, 100 mmol) were added. After purging the apparatus with nitrogen, 300 mL of NMP and 100 mL of toluene were added, dehydration was performed at 150°C, the temperature was raised to remove the toluene, and polymerization was carried out at 170°C for 6 hours. The oligomer was purified by reprecipitation with a large amount of isopropyl alcohol to obtain the ionic oligomer a2 (terminal: hydroxyl group) shown in formula (G5) below. The number-average molecular weight of this ionic oligomer a2 was 45,000. In formula (G5), M represents a hydrogen atom, Na, or K.

[0140] [ka]

[0141] (Synthesis of the ionic oligomer a2' represented by the following formula (G6)) In a 2,000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 400 mmol) and 49.0 g of ionic oligomer a2 were added. After purging the apparatus with nitrogen, 500 mL of NMP was added, and the contents were dissolved at 60°C. Then, 19.8 g of hexafluorobenzene / NMP solution (1 wt%) was added. The reaction was carried out at 80°C for 18 hours to obtain an NMP solution containing ionic oligomer a2' (terminus: OM) represented by formula (G6). The number-average molecular weight of this ionic oligomer a2' was 90,000. In formula (G6), M represents a hydrogen atom, Na, or K.

[0142] [ka]

[0143] (Synthesis of block copolymer b1 containing oligomer a2' as the ionic segment and oligomer a1 as the nonionic segment) In a 2000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 49.0 g of ionic oligomer a2' and 7.65 g of nonionic oligomer a1 were added. NMP was added to bring the total amount of oligomers to 7 wt%, and the reaction was carried out at 105°C for 24 hours. Reprecipitation was performed in a large amount of isopropyl alcohol / NMP mixture (weight ratio 2 / 1), and purification was performed with a large amount of isopropyl alcohol to obtain block copolymer b1. The number-average molecular weight of this block copolymer b1 was 170,000, and the weight-average molecular weight was 410,000.

[0144] The obtained block copolymer b1 was dissolved in a 20 wt% NMP solution, which was pressure filtered through a glass fiber filter. The solution was then cast onto a glass substrate and dried at 100°C for 4 hours to obtain a film-like molded body. This molded body was immersed in a 10 wt% sulfuric acid aqueous solution at 80°C for 24 hours to undergo proton substitution and deprotection reactions. After that, it was thoroughly washed by immersion in a large excess of pure water for 24 hours to obtain a polymer electrolyte membrane A (film thickness 10 μm). TEM and TEM tomography observations confirmed a co-continuous-like phase separation structure, with both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups forming a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 15.8 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0145] Example 2 (Synthesis of block copolymer b2 containing oligomer a2' as an ionic segment and oligomer a1 as a nonionic segment) Block copolymer b2 was obtained in the same manner as in Example 1, except that the amount of nonionic oligomer a1 used was 5.4 g. The number-average molecular weight of this block copolymer b2 was 180,000, and the weight-average molecular weight was 430,000.

[0146] A polymer electrolyte membrane B (thickness 11 μm) was obtained in the same manner as in Example 1, except that block copolymer b2 was used instead of block copolymer b1. Cocontinuous-like phase separation structure was confirmed by TEM and TEM tomography observation, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 13.2 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0147] Example 3 (Synthesis of nonionic oligomer a3 represented by formula (G4)) The terminal hydroxy compound of oligomer a3 was obtained in the same manner as the synthesis of the terminal hydroxy compound of oligomer a1, except that 21.45 g of 4,4'-difluorobenzophenone was used. The number-average molecular weight of this terminal hydroxy compound of oligomer a3 was 25,000.

[0148] Nonionic oligomer a3 (terminal: fluoro group) represented by formula (G4) was obtained in the same manner as the synthesis of oligomer a1, except that 25.0 g of the terminal hydroxyl group of oligomer a3 was used instead of the terminal hydroxyl group of oligomer a1. The number-average molecular weight of this nonionic oligomer a3 was 26,000.

[0149] (Synthesis of block copolymer b3 containing oligomer a2' as the ionic segment and oligomer a3 as the nonionic segment) Block copolymer b3 was obtained in the same manner as the synthesis of block copolymer b1, except that nonionic oligomer a3 (12.3g) was used instead of nonionic oligomer a1 (7.65g). The number-average molecular weight of block copolymer b3 was 160,000, and the weight-average molecular weight was 390,000.

[0150] A polymer electrolyte membrane C (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b3 was used instead of block copolymer b1. Cocontinuous-like phase separation structures were confirmed by TEM and TEM tomography observations, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 22.1 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0151] Example 4 (Synthesis of ionic oligomer a4 represented by formula (G5)) Ionic oligomer a4 was obtained in the same manner as the synthesis of ionic oligomer a2, except that the amount of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone used was 41.38 g (98.0 mmol). The number-average molecular weight of this ionic oligomer a4 was 35,000.

[0152] (Synthesis of ionic oligomer a4' represented by general formula (G6)) An NMP solution containing the ionic oligomer a4' (terminus: OM) represented by formula (G6) was obtained in the same manner as the synthesis of ionic oligomer a2', except that ionic oligomer a4 (37.16 g) was used instead of ionic oligomer a2 (49.0 g), the amount of NMP used was 400 mL, and the amount of hexafluorobenzene / NMP solution (1 wt%) used was 15.3 g. The number-average molecular weight of this oligomer a4' was 70,000.

[0153] (Synthesis of block copolymer b4 containing oligomer a4' as the ionic segment and oligomer a1 as the nonionic segment) Block copolymer b4 was obtained in the same manner as the synthesis of block copolymer b1, except that ionic oligomer a4' (37.16 g) was used instead of ionic oligomer a2' (49.0 g) in a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, and the amount of nonionic oligomer a1 used was 5.80 g. The number average molecular weight of this block copolymer b4 was 190,000, and the weight average molecular weight was 440,000.

[0154] A polymer electrolyte membrane D (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b4 was used instead of block copolymer b1. Cocontinuous-like phase separation structures were confirmed by TEM and TEM tomography observations, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 16.6 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0155] Example 5 (Synthesis of nonionic oligomer a5 represented by general formula (G4)) The terminal hydroxylated form of nonionic oligomer a5 was obtained in the same manner as the synthesis of the terminal hydroxylated form of nonionic oligomer a1, except that 21.27 g of 4,4'-difluorobenzophenone was used. The number-average molecular weight of this terminal hydroxylated form of nonionic oligomer a5 was 16,000.

[0156] Nonionic oligomer a5 (terminal: fluoro group) represented by formula (G4) was obtained in the same manner as the synthesis of nonionic oligomer a1, except that 16.0 g of the terminal hydroxyl group of nonionic oligomer a5 was used instead of 20.0 g of the terminal hydroxyl group of nonionic oligomer a1. The number-average molecular weight of this nonionic oligomer a5 was 17,000.

[0157] (Synthesis of ionic oligomer a6 represented by formula (G5)) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 27.64 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.91 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.31 g (50 mmol) of 4,4'-biphenol (Aldrich reagent, 50 mmol), and 41.85 g (99.1 mmol) of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2 were added. After purging the apparatus with nitrogen, 300 mL of dimethyl sulfoxide (DMSO) and 100 mL of toluene were added. Dehydration was carried out at 133°C, followed by heating to remove toluene, polymerization was carried out at 150°C for 2 hours, and then the temperature was raised to 155°C for a further 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain the ionic oligomer a6 (terminus: hydroxyl group) shown in formula (G5). The number-average molecular weight of this ionic oligomer a6 was 56,000.

[0158] (Synthesis of block copolymer b5 containing oligomer a6 as an ionic segment and oligomer a5 as a nonionic segment) Block copolymer b5 was obtained in the same manner as the synthesis of block copolymer b1, except that ionic oligomer a6 (32.79 g) was used instead of ionic oligomer a2' (49.0 g), and nonionic oligomer a5 (8.19 g) was used instead of nonionic oligomer a1 (7.65 g). The number-average molecular weight of this block copolymer b5 was 140,000, and the weight-average molecular weight was 360,000.

[0159] A polymer electrolyte membrane E (thickness 12 μm) was obtained in the same manner as in Example 1, except that block copolymer b5 was used instead of block copolymer b1. Cocontinuous-like phase separation structures were confirmed by TEM and TEM tomography observations, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 21.1 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0160] Example 6 (Synthesis of nonionic oligomer a7 represented by general formula (G7)) The terminal hydroxyl derivative of nonionic oligomer a7 was obtained in the same manner as the synthesis of the terminal hydroxyl derivative of nonionic oligomer a1, except that 23.65 g of 4,4'-difluorodiphenylsulfone was used instead of 4,4'-difluorobenzophenone. The number-average molecular weight of the terminal hydroxyl derivative of this nonionic oligomer a7 was 10,000.

[0161] Nonionic oligomer a7 (terminal fluoro group) represented by formula (G7) was obtained in the same manner as the synthesis of nonionic oligomer a1, except that the terminal hydroxyl form (10.0 g) of nonionic oligomer a7 was used instead of the terminal hydroxyl form (20.0 g) of nonionic oligomer a1. The number-average molecular weight of this nonionic oligomer a7 was 11,000.

[0162] [ka]

[0163] (Synthesis of ionic group oligomer a8 represented by formula (G8)) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.3 g of 4,4'-biphenol (Aldrich reagent, 50 mmol), and 45.12 g (99.1 mmol) of 3,3'-sodium disulfonate-4,4'-difluorodiphenylsulfone obtained in Synthesis Example 3 were added. After purging the apparatus with nitrogen, 300 mL of DMSO and 100 mL of toluene were added. Dehydration was performed at 130°C, followed by heating to remove the toluene, and polymerization was carried out at 155°C for 3 hours. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain the ionic oligomer a8 (terminal hydroxyl group) represented by formula (G8). The number-average molecular weight of this ionic oligomer a8 was 57,000.

[0164] [ka]

[0165] (Synthesis of block copolymer b6 containing oligomer a8 as an ionic segment and oligomer a7 as a nonionic segment) Block copolymer b10 was obtained in the same manner as the synthesis of block copolymer b1, except that ionic oligomer a8 (65.82 g) was used instead of ionic oligomer a2' (49.0 g), and nonionic oligomer a7 (10.28 g) was used instead of nonionic oligomer a1 (7.65 g). The number-average molecular weight of this block copolymer b6 was 110,000, and the weight-average molecular weight was 280,000.

[0166] A polymer electrolyte membrane F (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b6 was used instead of block copolymer b1. Co-continuous phase separation structure was confirmed by TEM and TEM tomography observation, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. No crystallization peak was observed by DSC (calculation heat 0 J / g). Furthermore, no crystalline peak was observed by wide-angle X-ray diffraction (crystallinity 0%).

[0167] Example 7 (Synthesis of ionic oligomer precursor a9 represented by the following general formula (G9)) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 200 mL of dry N,N-dimethylacetamide (DMAc), 16.9 g (42 mmol) of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate, and 0.09 g (0.7 mmol) of 4-chlorophenol were added and stirred at 80°C for 2 hours under a nitrogen atmosphere. Then, 30 g (109 mmol) of bis(1,5-cyclooctadiene)nickel was added and stirred for 4 hours. Dilution with 300 mL of dry DMAc, 1 L of acetone was added, and after coagulation, the mixture was vacuum-dried at 80°C to obtain ionic oligomer precursor a9 (terminus: hydroxyl group) represented by the following formula (G9). The number-average molecular weight was 22,000.

[0168] [ka]

[0169] (Synthesis of the ionic oligomer precursor a9' represented by the following formula (G10)) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 400 mmol) and 11.1 g of ionic oligomer a10 were added. After purging the apparatus with nitrogen, 200 mL of dry DMAc was added, and the contents were dissolved at 60°C. Then, 30.6 g of hexafluorobenzene / DMAc solution (1 wt%) was added. The reaction was carried out at 80°C for 24 hours to obtain a DMAc solution containing the ionic oligomer precursor a9' (terminus: OM) represented by the following formula (G10). The number-average molecular weight of the ionic oligomer precursor a9' was 67,000. In formula (G10), M represents a hydrogen atom, Na, or K.

[0170] [ka]

[0171] (Synthesis of nonionic oligomer a10 represented by the general formula (G11) below) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 200 mL of dry NMP, 10.08 g (40 mmol) of 2,5-dichlorobenzophenone, and 0.12 g (0.9 mmol) of 4-chlorophenol were added and stirred at 80°C for 2 hours under a nitrogen atmosphere. Then, 30 g (109 mmol) of bis(1,5-cyclooctadiene)nickel was added and the mixture was stirred for 4 hours. The mixture was diluted with 300 mL of dry NMP, precipitated in 1 L of 10 wt% hydrochloric acid aqueous solution, and then vacuum-dried at 80°C to obtain the terminal hydroxyl derivative of the nonionic oligomer a10 represented by the following formula (G11). The number-average molecular weight was 9,000.

[0172] Nonionic oligomer a10 (terminal fluoro group) represented by the following formula (G11) was obtained in the same manner as the synthesis of nonionic oligomer a1, except that the terminal hydroxyl form (9.0 g (1 mmol)) of nonionic oligomer a10 was used instead of the terminal hydroxyl form (20.0 g) of nonionic oligomer a10. The number-average molecular weight of this nonionic oligomer a10 was 10,000.

[0173] [ka]

[0174] (Synthesis of block copolymer b7 containing ionic oligomer a9'' as an ionic segment and oligomer a10 as a nonionic segment) In a 2,000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 11.1 g of ionic oligomer precursor a9' and 5.71 g of nonionic oligomer a10 were added. DMAc was added to bring the total oligomer content to 7 wt%, and the reaction was carried out at 105°C for 24 hours. The polymerization reaction solution was diluted with 500 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.

[0175] The filtrate was concentrated using an evaporator, and 21.9 g (0.253 mol) of lithium bromide was added to the residue. The reaction was carried out at an internal temperature of 110°C for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 3 L of acetone, and allowed to solidify. The solidified material was filtered, air-dried, pulverized in a mixer, and washed with 1500 mL of 1N hydrochloric acid while stirring. After filtration, the product was washed with deionized water until the pH of the washing solution was 5 or higher. The mixture was then dried overnight at 80°C to obtain block copolymer b7 having the ionic oligomer a9'' represented by the following formula (G12). From the structural formula and number-average molecular weight of formula (G12), the number-average molecular weight of ionic oligomer a9'' is calculated to be 53,000. The number-average molecular weight of block copolymer b7 was 90,000, and the weight-average molecular weight was 210,000. In formula (G12), * represents bonding with a nonionic segment.

[0176] [ka]

[0177] Block copolymer b7 was dissolved in a solvent consisting of NMP / methanol = 30 / 70 (mass%) at a concentration of 0.1 g / g. After pressure filtration through a glass fiber filter, the solution was cast onto a glass substrate and dried at 100°C for 4 hours to obtain a film-like molded body. This molded body was immersed in a 10 mass% sulfuric acid aqueous solution at 80°C for 24 hours, and then thoroughly washed by immersion in a large excess of pure water for 24 hours to obtain a polymer electrolyte membrane G (film thickness 10 μm). Co-continuous phase separation structure was confirmed by TEM and TEM tomography observation, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. No crystallization peak was observed by DSC. However, a crystalline peak was observed by wide-angle X-ray diffraction, and its crystallinity was 10.4%.

[0178] Comparative Example 1 (Synthesis of nonionic oligomer a11 represented by general formula (G4)) The terminal hydroxyl derivative of nonionic oligomer a11 was obtained in the same manner as the synthesis of the terminal hydroxyl derivative of nonionic oligomer a1, except that 20.84 g of 4,4'-difluorobenzophenone was used. The number-average molecular weight of this terminal hydroxyl derivative of nonionic oligomer a9 was 9,000.

[0179] Nonionic oligomer a11 (terminal: fluoro group) represented by formula (G4) was obtained in the same manner as the synthesis of nonionic oligomer a1, except that the terminal hydroxyl form (9.0 g) of nonionic oligomer a11 was used instead of the terminal hydroxyl form (20.0 g) of nonionic oligomer a11. The number-average molecular weight of this nonionic oligomer a11 was 10,000.

[0180] (Synthesis of ionic oligomer a12 represented by general formula (G5)) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 27.64 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.91 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.31 g (50 mmol) of 4,4'-biphenol (Aldrich reagent, 50 mmol), 41.47 g (98.2 mmol) of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2, and 26.40 g of 18-crown-6 (Wako Pure Chemical Industries, 100 mmol) were added. After purging the apparatus with nitrogen, 300 mL of NMP and 100 mL of toluene were added, dehydration was performed at 150°C, the temperature was raised to remove the toluene, and polymerization was carried out at 170°C for 6 hours. The oligomer was purified by reprecipitation with a large amount of isopropyl alcohol to obtain the ionic oligomer a12 (terminal: hydroxyl group) represented by formula (G5). The number-average molecular weight of this ionic oligomer a12 was 42,000.

[0181] (Synthesis of block copolymer b8 containing oligomer a12 as an ionic segment and oligomer a11 as a nonionic segment) Block copolymer b8 was obtained in the same manner as the synthesis of block copolymer b1, except that ionic oligomer a12 (43.57 g) was used instead of ionic oligomer a2' (49.0 g), and nonionic oligomer a11 (10.89 g) was used instead of nonionic oligomer a1 (7.65 g). The number-average molecular weight of this block copolymer b8 was 140,000, and the weight-average molecular weight was 400,000.

[0182] A polymer electrolyte membrane H (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b8 was used instead of block copolymer b1. Co-continuity-like phase separation structure was confirmed by TEM and TEM tomography observation, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 15.1 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0183] Comparative Example 2 (Synthesis of nonionic oligomer a13 represented by formula (G4)) The terminal hydroxyl derivative of nonionic oligomer a15 was obtained in the same manner as the synthesis of the terminal hydroxyl derivative of nonionic oligomer a1, except that 20.18 g of 4,4'-difluorobenzophenone was used. The number-average molecular weight of this terminal hydroxyl derivative of nonionic oligomer a15 was 5,000.

[0184] In a 500 mL three-necked flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 2.2 g of potassium carbonate (Aldrich reagent, 16 mmol) and 10.0 g of the terminal hydroxyl group of nonionic oligomer a13 were placed. After purging the apparatus with nitrogen, 100 mL of NMP and 30 mL of toluene were added, and the mixture was dehydrated at 100 °C. After raising the temperature to remove the toluene, 2.2 g of hexafluorobenzene (Aldrich reagent, 12 mmol) was added, and the reaction was carried out at 105 °C for 12 hours. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain nonionic oligomer a13 (terminal: fluoro group) represented by formula (G4). The number-average molecular weight of this nonionic oligomer a13 was 6,000.

[0185] (Synthesis of block copolymer b9 containing oligomer a12 as an ionic segment and oligomer a13 as a nonionic segment) Block copolymer b9 was obtained in the same manner as the synthesis of block copolymer b8, except that nonionic oligomer a13 (6.81 g) was used instead of nonionic oligomer a11 (10.89 g). The number-average molecular weight of block copolymer b9 was 130,000, and the weight-average molecular weight was 400,000.

[0186] A polymer electrolyte membrane I (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b9 was used instead of block copolymer b1. Co-continuous phase separation structures were confirmed by TEM and TEM tomography observations, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase, although some discontinuous structures were observed. Crystallization peaks were observed by DSC, and the heat of crystallization was 6.4 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0187] Comparative Example 3 (Synthesis of nonionic oligomer a14 represented by formula (G4)) A terminal hydroxy-terminated non-ionic oligomer a14 was obtained in the same manner as the synthesis of the terminal hydroxy-terminated non-ionic oligomer a1, except that the amount of 4,4'-difluorobenzophenone used was changed to 19.99 g. The number-average molecular weight of this terminal hydroxy-terminated non-ionic oligomer a14 was 4,000.

[0188] A non-ionic oligomer a14 represented by formula (G4) (terminal: fluoro group) was obtained in the same manner as the synthesis of the non-ionic oligomer a13, except that 8.0 g of the terminal hydroxy-terminated non-ionic oligomer a14 was used instead of 10.0 g of the terminal hydroxy-terminated non-ionic oligomer a13. The number-average molecular weight of this non-ionic oligomer a14 was 5,000.

[0189] (Synthesis of block copolymer b10 containing oligomer a12 as an ionic segment and oligomer a14 as a non-ionic segment) A block copolymer b10 was obtained in the same manner as the synthesis of block copolymer b9, except that 4.84 g of non-ionic oligomer a14 was used instead of 6.81 g of non-ionic oligomer a13. The number-average molecular weight of this block copolymer b10 was 130,000, and the weight-average molecular weight was 400,000.

[0190] A polymer electrolyte membrane J (film thickness: 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b10 was used instead of block copolymer b1. A co-continuous phase separation structure was confirmed by TEM and TEM tomography observation, and both the hydrophilic domain containing ionic groups and the hydrophobic domain containing no ionic groups formed a continuous phase, although some discontinuous structures were observed. A crystallization peak was observed by DSC, and the heat of crystallization was 2.9 J / g. Further, no crystalline peak was observed by wide-angle X-ray diffraction (crystallinity: 0%).

[0191] Comparative Example 4 (Synthesis of ionic oligomer a15 represented by the following general formula (G8)) Disodium 3,3'-disulfonate-4,4'-difluorobenzophenone, except that 44.94 g (98.1 mmol) of 3,3'-disulfonic acid sodium salt-4,4'-difluorodiphenyl sulfone obtained in Synthesis Example 3 was used instead of 41.60 g of the above compound, ionic oligomer a15 (terminal hydroxy group) represented by formula (G8) was obtained in the same manner as the synthesis of ionic oligomer a2. The number average molecular weight of this ionic oligomer a15 was 41,000. In formula (G8), M represents a hydrogen atom, Na or K.

[0192] (Synthesis of Block Copolymer b11 Containing Oligomer a15 as Ionic Segment and Oligomer a7 as Nonionic Segment) Into a 2,000 mL SUS polymerization apparatus equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 45.76 g of ionic oligomer a15 and 8.93 g of nonionic oligomer a7 were added, NMP was added so that the total charged amount of oligomers was 7 wt%, and the reaction was carried out at 105°C for 24 hours. Reprecipitation was performed in a large amount of isopropyl alcohol / NMP mixed solution (weight ratio 2 / 1), purification was performed with a large amount of isopropyl alcohol, and block copolymer b11 was obtained. The number average molecular weight of this block copolymer b11 was 120,000, and the weight average molecular weight was 290,000.

[0193] A polymer electrolyte membrane K (membrane thickness: 10 µm) was obtained in the same manner as in Example 1, except that block copolymer b11 was used instead of block copolymer b1. By TEM and TEM tomography observation, a co-continuous phase separation structure was confirmed, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. No crystallization peak was observed by DSC (heat of crystallization: 0 J / g). Further, no crystalline peak was observed by wide-angle X-ray diffraction (degree of crystallinity: 0%).

[0194] Comparative Example 5 (Synthesis of Nonionic Oligomer a16 Represented by General Formula (G13) Below) Except for using 25.22 g of K-DHBP and 21.82 g of 4,4'-difluorobenzophenone, the nonionic oligomer a16 (terminal: fluoro group) represented by formula (G13) was obtained in the same manner as the synthesis of the terminal hydroxyl form of nonionic oligomer a1. The number-average molecular weight of this ionic oligomer a16 was 17,000.

[0195] [ka]

[0196] (Synthesis of block copolymer b12 containing oligomer a12 as an ionic segment and oligomer a16 as a nonionic segment) In a 2,000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 43.57 g of ionic oligomer a12 and 10.89 g of nonionic oligomer a16 were added. NMP was added to bring the total amount of oligomers to 21 wt%, and the reaction was carried out at 180°C for 24 hours. Reprecipitation was performed in a large amount of isopropyl alcohol / NMP mixture (weight ratio 2 / 1), and purification was performed with a large amount of isopropyl alcohol to obtain block copolymer b12. The number-average molecular weight of this block copolymer b12 was 90,000, and the weight-average molecular weight was 210,000.

[0197] A polymer electrolyte membrane L (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b12 was used instead of block copolymer b1. A sea-island-like phase separation structure was confirmed by TEM and TEM tomography observation. Crystallization peaks were observed by DSC, and the heat of crystallization was 3.6 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0198] Comparative Example 6 (Synthesis of nonionic oligomer a17 represented by formula (G4)) The terminal hydroxyl derivative of nonionic oligomer a17 was obtained in the same manner as the synthesis of the terminal hydroxyl derivative of nonionic oligomer a1, except that 19.81 g of 4,4'-difluorobenzophenone was used. The number-average molecular weight of this terminal hydroxyl derivative of nonionic oligomer a17 was 3,000.

[0199] Nonionic oligomer a17 (terminal: fluoro group) represented by formula (G4) was obtained in the same manner as the synthesis of nonionic oligomer a13, except that 6.0 g of the terminal hydroxyl group of nonionic oligomer a17 was used instead of 10.0 g of the terminal hydroxyl group of nonionic oligomer a13. The number average molecular weight of this ionic oligomer a17 was 4,000.

[0200] (Synthesis of block copolymer b13 containing oligomer a12 as an ionic segment and oligomer a17 as a nonionic segment) Block copolymer b13 was obtained in the same manner as the synthesis of block copolymer b9, except that nonionic oligomer a17 (3.63 g) was used instead of nonionic oligomer a13 (6.81 g). The number-average molecular weight of block copolymer b13 was 90,000, and the weight-average molecular weight was 220,000.

[0201] A polymer electrolyte membrane M (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b13 was used instead of block copolymer b1. Co-continuous phase separation structures were confirmed by TEM and TEM tomography observations, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase, although some discontinuous structures were observed. Crystallization peaks were observed by DSC, and the heat of crystallization was 0.5 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%).

[0202] Comparative Example 7 (Synthesis of nonionic oligomer a18 represented by formula (G4)) The terminal hydroxyl derivative of nonionic oligomer a18 was obtained in the same manner as the synthesis of the terminal hydroxyl derivative of nonionic oligomer a1, except that 21.49 g of 4,4'-difluorobenzophenone was used. The number-average molecular weight of this terminal hydroxyl derivative of nonionic oligomer a18 was 27,000.

[0203] Nonionic oligomer a18 (terminal: fluoro group) represented by formula (G4) was obtained in the same manner as the synthesis of oligomer a1, except that 27.0 g of the terminal hydroxyl group of oligomer a18 was used instead of the terminal hydroxyl group of oligomer a1. The number-average molecular weight of this nonionic oligomer a18 was 28,000.

[0204] (Synthesis of block copolymer b14 containing oligomer a12 as an ionic segment and oligomer a18 as a nonionic segment) Block copolymer b13 was obtained in the same manner as the synthesis of block copolymer b8, except that nonionic oligomer a17 (14.52 g) was used instead of nonionic oligomer a11 (10.89 g). The number-average molecular weight of this block copolymer b14 was 70,000, and the weight-average molecular weight was 200,000.

[0205] The resulting block copolymer b14 was dissolved in a 20 wt% NMP solution, which showed poor solubility and the presence of gel-like insoluble matter. The solution was pressure-filtered using a glass fiber filter. The copolymer was cast onto a glass substrate and dried at 100°C for 4 hours to obtain a film-like molded body. However, defects were observed, likely due to the remaining gel-like insoluble matter. After immersion in a 10 wt% sulfuric acid aqueous solution at 80°C for 24 hours to perform proton substitution and deprotection reactions, the film was thoroughly washed by immersion in a large excess of pure water for 24 hours to obtain a polymer electrolyte membrane N (film thickness 13 μm). TEM and TEM tomography observations confirmed a co-continuous-like phase separation structure, with both hydrophilic domains containing ionic groups and hydrophobic domains without ionic groups forming a continuous phase, although some areas were not continuous, resulting in a heterogeneous structure. DSC revealed a crystallization peak, with a crystallization heat of 28.4 J / g. Wide-angle X-ray diffraction did not reveal any crystalline peaks (crystallinity 0%). Comparative Example 8 (Synthesis of nonionic oligomer a19 represented by the general formula (G14) below) In a 1,000 mL three-necked flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and 21.4 g of 4,4'-difluorobenzophenone (Aldrich reagent, 98 mmol) were added. After nitrogen purging, dehydration was carried out at 160°C in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene. The mixture was then heated to remove the toluene, and polymerization was carried out at 180°C for 1 hour. Purification was performed by reprecipitation with a large amount of methanol to obtain the terminal hydroxyl group of oligomer a19, which does not contain ionic groups. The number-average molecular weight was 20,000.

[0206] Into a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube and a Dean-Stark trap, were added 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 40.0 g (2 mmol) of the terminal hydroxyl substrate of said oligomer a19 containing no ionic group. After nitrogen replacement, dehydration was performed at 100°C in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, the temperature was increased to remove cyclohexane, then 3.0 g of bis(4-fluorophenyl sulfone) (Aldrich reagent, 12 mmol) was added, and the reaction was carried out at 105°C for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol, to obtain nonionic group oligomer a19 (terminal fluoro group) represented by the following formula (G14). The number average molecular weight was 21,000.

[0207]

Chemical Formula

[0208] (Synthesis of ionic group oligomer a20 represented by the above general formula (G5)) Into a 1,000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube and a Dean-Stark trap, were added 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 25.8 g (100 mmol) of K-DHBP obtained in the above Synthesis Example 1, 41.4 g (98 mmol) of disodium 3,3'-disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2, and 17.9 g of 18-crown-6 (Wako Pure Chemical Industries, 82 mmol). After nitrogen replacement, dehydration was performed at 170°C in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, the temperature was increased to remove toluene, and polymerization was carried out at 180°C for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol, to obtain the terminal hydroxyl substrate of oligomer a20 containing an ionic group represented by the above formula (G5). The number average molecular weight was 33,000.

[0209] (Synthesis of block copolymer b15 containing oligomer a20 as an ionic segment and oligomer a19 as a nonionic segment) In a 500 mL three-necked flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 33 g (1 mmol) of the terminal hydroxyl group of oligomer a20 containing an ionic group were added. After nitrogen purging, 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane were added, dehydration was carried out at 100°C, and the temperature was raised to remove the cyclohexane. 21 g (1 mmol) of oligomer a19 (terminal fluoro group) that does not contain an ionic group was added, and the reaction was carried out at 105°C for 24 hours. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain block copolymer b15. The number-average molecular weight of this block copolymer b15 was 100,000, and the weight-average molecular weight was 360,000.

[0210] A polymer electrolyte membrane O (thickness 10 μm) was obtained in the same manner as in Example 1, except that block copolymer b15 was used instead of block copolymer b1. Cocontinuous-like phase separation structures were confirmed by TEM and TEM tomography observations, and both hydrophilic domains containing ionic groups and hydrophobic domains not containing ionic groups formed a continuous phase. Crystallization peaks were observed by DSC, and the heat of crystallization was 25.1 J / g. Furthermore, no crystalline peaks were observed by wide-angle X-ray diffraction (crystallinity 0%). [Measurement results] Table 1 shows the measurement results of the polymer electrolyte membranes obtained in the examples and comparative examples.

[0211] [Table 1]

[0212] In the polymer electrolyte membrane of the present invention, from the viewpoint of achieving a relatively high level of balance between mechanical strength, physical durability and proton conductivity, it is preferable that the dry-wet dimensional change rate is 7.0% or less, the low-humidified proton conductivity is 0.90 mS / cm or more, and the high-humidified proton conductivity is 9.50 mS / cm or more; it is more preferable that the dry-wet dimensional change rate is 6.5% or less, the low-humidified proton conductivity is 1.00 mS / cm or more, and the high-humidified proton conductivity is 11.00 mS / cm or more; and it is particularly preferable that the dry-wet dimensional change rate is 6.0% or less, the low-humidified proton conductivity is 1.10 mS / cm or more, and the high-humidified proton conductivity is 12.00 mS / cm or more. [Explanation of Symbols]

[0213] 1 phase 1 2 phase 2

Claims

1. A polymer electrolyte membrane comprising a block copolymer having one or more segments containing ionic groups (hereinafter referred to as "ionic segments") and one or more segments not containing ionic groups (hereinafter referred to as "nonionic segments"), wherein the block copolymer has an ion exchange capacity (meq / g) greater than 2.0 and less than 2.8, the polymer electrolyte membrane has a co-continuous phase separation structure, the average period size (nm) of the co-continuous phase separation structure observed by a transmission electron microscope is less than 100 nm, the relationship between the average period size (nm) of the co-continuous phase separation structure and the ion exchange capacity (meq / g) satisfies average period size (nm) / ion exchange capacity (meq / g) ≥ 23, the crystallization heat of the polymer electrolyte membrane measured by differential scanning calorimetry is 0.1 J / g or more, or the degree of crystallinity of the polymer electrolyte membrane measured by wide-angle X-ray diffraction is 0.5% or more.

2. The polymer electrolyte membrane according to claim 1, characterized in that the block copolymer is an aromatic hydrocarbon copolymer.

3. The polymer electrolyte membrane according to claim 2, characterized in that the aromatic hydrocarbon copolymer is an aromatic polyether copolymer.

4. The polymer electrolyte membrane according to claim 3, characterized in that the aromatic polyether copolymer is an aromatic polyether ketone copolymer.

5. The polymer electrolyte membrane according to claim 1, characterized in that the block copolymer has linker portions that bond the ionic segment and the nonionic segment.

6. The ionic segment is characterized by containing a structure represented by the following general formula (S1). The polymer electrolyte membrane according to claim 1. 【Chemistry 1】 (In general formula (S1), Ar １ ~Ar ４ Each of these independently represents a substituted or unsubstituted arylene group, and Ar １ ~Ar ４ At least one of them has an ionic group. １ and Y ２ Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with general formula (S1) or other constituent units.

7. The polymer electrolyte membrane according to claim 6, characterized in that the structure represented by the general formula (S1) is the structure represented by the following general formula (S2). 【Chemistry 2】 In general formula (S2), Y １ and Y ２ each independently represent a ketone group or a protecting group that can be derivatized into a ketone group. M １ to M ４ each independently represent a hydrogen atom, a metal cation or an ammonium cation. n １ to n ４ are each independently 0 or 1, and n １ to n ４ at least one of which is 1. * represents a bond to general formula (S2) or another constitutional unit.)

8. The polymer electrolyte membrane according to claim 1, characterized in that the nonionic segment contains a structure represented by the following general formula (S3). 【Transformation 3】 (In general formula (S3), Ar ５ ~Ar ８ Each of these independently represents an arylene group. However, Ar ５ ~Ar ８ None of them have ionic groups. ３ and Y ４ Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with the general formula (S3) or other constituent units.

9. The polymer electrolyte membrane according to claim 8, characterized in that the structure represented by the general formula (S3) is the structure represented by the following general formula (S4). 【Chemistry 4】 (In general formula (S4), Y ３ and Y ４ Each of these independently represents a ketone group or a protecting group that can be converted to a ketone group. * represents a bond with the general formula (S4) or other constituent units.

10. A catalyst-layered electrolyte membrane characterized by being constructed using the polymer electrolyte membrane described in claim 1.

11. A membrane electrode composite characterized by being composed of a polymer electrolyte membrane as described in claim 1.

12. A solid polymer fuel cell characterized by being constructed using the polymer electrolyte membrane described in claim 1.

13. A water electrolysis hydrogen generator characterized by being constructed using a polymer electrolyte membrane as described in claim 1.

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