JP2011241299A - Block copolymer, and proton-exchange membrane for fuel cell using the copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proton-exchange membrane higher in swelling resistance to hot water than ever as well as being excellent in proton conductivity, and also excellent in radical resistance, and to provide a block copolymer constituting the proton-exchange membrane.SOLUTION: The block copolymer comprises: a hydrophobic segment represented by (chemical formula 1); and a hydrophilic segment represented by (chemical formula 2); wherein the hydrophobic segment and the hydrophilic segment are bound to each other via a fluorine-substituted aromatic group. In (chemical formula 1), Z groups are each independently an O atom or S atom; Argroups are each independently a bivalent aromatic group; and n is 1-100. In (chemical formula 2), X groups are each independently H or a monovalent cation; Y is a sulfonyl or carbonyl group; Argroups are each independently a bivalent aromatic group; L groups are each independently a sulfide or sulfonyl group; and m is 1-100.

Description

  The present invention relates to a block copolymer, a molded product using the copolymer, a proton exchange membrane for a fuel cell, and an electrode assembly for a fuel cell.

  In recent years, new power generation technology with excellent power generation efficiency and environmental performance has been attracting attention. In particular, solid polymer fuel cells using polymer membranes as proton exchange membranes have high power density, and are easier to start and stop because of their lower operating temperatures than other types of fuel cells. Development is progressing as a power supply device for power generation and distributed power generation.

  In addition to proton conductivity, the proton exchange membrane is required to have fuel permeation deterrence and mechanical strength that prevent the permeation of fuel (such as hydrogen). As a material for such a proton exchange membrane, for example, a fluorine-based polymer represented by Nafion (registered trademark) manufactured by DuPont, USA is known. However, such fluoropolymers are expensive and have a problem of high fuel permeability. Furthermore, when used in a fuel cell, the fluorine-based polymer also has a problem that harmful hydrofluoric acid is mixed into the exhaust gas depending on the operating conditions, or a large load is given to the environment at the time of disposal. Therefore, in order to solve such a problem, development of a polymer (hydrocarbon polymer) composed of a hydrocarbon polymer is being actively conducted.

  However, such hydrocarbon polymers also have various problems. For example, in a fuel cell using hydrogen as a fuel, a radical is generated by a side reaction. However, a hydrocarbon polymer has a problem that its radical resistance is inferior to that of a fluorine polymer. This is considered to be because the hydrocarbon skeleton is liable to cause a degradation reaction due to radicals (oxidation reaction due to peroxide radicals). In addition, the proton exchange membrane also has a problem in that physical destruction due to repeated swelling / shrinking due to operation / stop is added.

  Accordingly, various methods have been proposed for the purpose of providing a hydrocarbon polymer having radical resistance equivalent to or higher than that of a fluorine polymer, or practically sufficient, and can be produced at low cost. . For example, a highly durable solid polymer electrolyte (for example, Patent Documents 1 and 2) made of a polymer compound having a hydrocarbon part and having a functional group containing phosphorus, or a polymer compound having an electrolyte group and a hydrocarbon part And a highly durable solid polymer electrolyte composition (for example, Patent Document 3) obtained by mixing a phosphorus-containing polymer compound and the like.

  However, the method of introducing a functional group containing phosphorus has drawbacks that the preparation of the hydrocarbon polymer is complicated and the structure of the applicable hydrocarbon polymer is limited. In the method of mixing the phosphorus-containing polymer compound, the phosphorus-containing polymer compound may be eluted under the operating conditions of the fuel cell.

  In addition, a technique for improving radical resistance of a polymer electrolyte by introducing an electron-withdrawing group such as a sulfone bond into a hydrocarbon polymer main chain has been proposed (for example, Patent Document 4 and Non-Patent Document 1). ). However, when the proton conductivity is increased, the polymer electrolyte disclosed herein also has higher swellability, and sufficient mechanical durability may not be obtained.

  The present applicant has previously proposed a block copolymer having two types of segments as a hydrocarbon polymer having low swellability and high proton conductivity, wherein one segment has a benzonitrile structure. The polymer which contains is disclosed (patent document 5). However, in such a polymer, it may be difficult to improve radical resistance by introducing a large number of electron-withdrawing groups such as sulfone bonds into the polymer main chain.

JP 2000-11755 A JP 2004-79252 A JP 2000-11756 A JP 2000-80166 A JP 2006-176666 A

Michael Schuster and three other authors, “Sulfoated Polyphenylenesulfone Polymers as Hydrolytically Stable Proton Conducting Ionomer” (Sulfonate Polysulfide Polymer) Macromolecules, (USA), American Chemical Society, 2007, No. 40, p. 598-607

  The present invention has been made in order to solve the above problems, and is not only excellent in proton conductivity, but also has higher swelling resistance to hot water, and further has excellent radical resistance, and a proton exchange membrane, and An object was to provide a block copolymer constituting the proton exchange membrane.

  As a result of diligent research, the present inventors have found that a block copolymer in which a hydrophilic segment having a large number of sulfone bonds in the hydrocarbon polymer main chain and a hydrophobic segment having a benzonitrile structure are bonded by a specific linking group. The present inventors have found that a polymer can provide a proton exchange membrane that not only has excellent proton conductivity, but also has low swelling in the area direction and excellent resistance to radicals, leading to the present invention.

  That is, the block copolymer according to the present invention has the chemical formula 1

(Chemical formula 1)

(In the formula, each Z independently represents an O atom or an S atom, Ar ¹ independently represents a divalent aromatic group, and n represents a number of 1 to 100, respectively.)
A hydrophobic segment represented by the formula 2

(Chemical formula 2)

(Wherein X is independently H or monovalent cation, Y is sulfonyl group or carbonyl group, Ar ² is independently divalent aromatic group, and L is independently sulfide. A sulfonyl group or a sulfonyl group, wherein m represents a number of 1 to 100), and the hydrophobic segment and the hydrophilic segment are represented by the chemical formula 3

(Chemical formula 3)

(In the formula, p represents 0 or 1, and when p is 1, W represents one or more selected from the group consisting of a direct bond, a sulfonyl group, and a carbonyl group.)
It is combined with the group represented by these.

In the present invention, Ar ² is represented by the chemical formula 4

(Chemical formula 4)
Is a preferred embodiment.

  In the preferred embodiment, the block copolymer has a logarithmic viscosity of 0.5 to 5.0 dL / g at 30 ° C. in a 0.5 g / dL solution using N-methyl-2-pyrrolidone as a solvent. is there.

  The present invention employs a molded product characterized by using the block copolymer, a proton exchange membrane for a fuel cell characterized by using the molded product, and a proton exchange membrane for a fuel cell. An electrode assembly for a fuel cell characterized by the above is also included.

  By using the block copolymer of the present invention, it is possible to provide a proton exchange membrane that not only has excellent swelling resistance against hot water but also has excellent radical resistance.

¹ is a ¹ H-NMR spectrum of a block copolymer obtained in Example 13.

  The block copolymer of the present invention comprises a hydrophobic segment represented by the above chemical formula 1 and a hydrophilic segment represented by the above chemical formula 2, and the hydrophobic segment and the hydrophilic segment are represented by the above chemical formula 3 It is couple | bonded with the coupling group represented by these, It is characterized by the above-mentioned.

  Hereafter, each segment which comprises the block copolymer of this invention, its manufacturing method, the specific aspect of the copolymer comprised from the said segment, its characteristic, and the manufacturing method of the said copolymer are demonstrated.

(Hydrophobic segment)
The structure of the hydrophobic segment constituting the block copolymer of the present invention is expressed by the following chemical formula 1 in order to express the swelling resistance when the proton exchange membrane obtained using the block copolymer is immersed in hot water.

(Chemical formula 1)

(In the formula, each Z independently represents an O atom or an S atom, Ar ¹ independently represents a divalent aromatic group, and n represents a number of 1 to 100, respectively.)
It is necessary to be represented by

  In Chemical Formula 1, Z is preferably an O atom from the viewpoint of availability of raw materials and ease of synthesis. However, when Z is an S atom, the oxidation resistance of the proton exchange membrane may be improved.

Ar ¹ may be any known divalent aromatic group mainly composed of an aromatic group, and examples thereof include divalent aromatic groups represented by the following chemical formulas 5A to 5P. .

(In the formula, R represents a methyl group, and q represents an integer of 0 to 2, respectively.)

In Chemical Formulas 5A to 5P, when q is 1 or 2, it may be difficult to obtain a high molecular weight hydrophobic segment, and therefore q is preferably 0. Ar ¹ is more preferably a divalent aromatic group represented by the chemical formulas 5A, 5C, 5E, 5F, 5K, 5M, and 5N, represented by the following chemical formulas 5A ′, 5F ′, and 5M ′. The divalent aromatic group is more preferably a divalent aromatic group represented by the chemical formula 5A ′. Ar ¹ may be composed of different divalent aromatic groups. In that case, in order to show more excellent characteristics, it preferably contains at least one of the divalent aromatic groups represented by the chemical formulas 5A ′, 5F ′, and 5M ′. It is more preferable that any of the bivalent aromatic groups represented by these is included. When a divalent aromatic group represented by the chemical formula 5A ′ is contained, a proton exchange membrane having excellent swelling resistance and durability can be obtained. When a divalent aromatic group represented by the chemical formula 5M ′ is contained, a proton exchange membrane having excellent durability can be obtained.

  In Chemical Formula 1, n represents a number from 1 to 100. It should be noted that n should be an integer in the case of individual hydrophobic segments, but when there is a distribution in the molecular weight of the segments within or between molecules, if n is an average value, n is not necessarily an integer. Disappear. Therefore, when defining the structure of the copolymer, it is substantially effective to express the average value. n can be determined by any known method such as NMR or gel permeation chromatography. n is preferably 10 to 70, more preferably 13 to 50, and particularly preferably 15 to 30. When n is 15 to 30, a proton exchange membrane with further improved proton conductivity and durability can be obtained. If n is less than 1, the swellability of the proton exchange membrane may become too large or the durability may be lowered. When n exceeds 100, it may be difficult to control the molecular weight of the hydrophobic segment, and it may be difficult to synthesize a copolymer having a designed structure.

(Method for producing hydrophobic segment)
The method for producing the hydrophobic segment (hydrophobic oligomer) is not particularly limited. For example, a monomer represented by the following chemical formula 6A or 6B is converted into various bisphenols or various bisthiophenols (for example, the above chemical formula 5A). It can be synthesized by reacting with a compound having both ends of ˜5M ′ at the OH group or SH group.

  In that case, it is preferable that various bisphenols or various bisthiophenols are excessive so that the terminal group of the oligomer is an OH group or an SH group. The degree of polymerization of the oligomer can be adjusted by the molar ratio of the monomer of chemical formula 6A or 6B and various bisphenols or various bisthiophenols.

  The monomer of formula 6A or 6B and various bisphenols or various bisthiophenols can be reacted by any known method, but they can be reacted by an aromatic nucleophilic substitution reaction in the presence of a basic compound. Is preferred.

  Although reaction temperature can be performed in 0-350 degreeC, it is preferable to carry out in 50-250 degreeC. When the reaction temperature is lower than 0 ° C, the reaction may not proceed sufficiently, and when it is higher than 350 ° C, the oligomer may be decomposed.

  The reaction can be carried out in the absence of a solvent, but is preferably carried out in a solvent. Examples of the solvent that can be used include aprotic polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, and sulfolane. It is not limited to this, and any material that can be used as a stable solvent in the aromatic nucleophilic substitution reaction may be used. These solvents may be used alone or in combination of two or more.

  When the aromatic nucleophilic substitution reaction is carried out in a solvent, it is preferable to charge monomers and the like such that the resulting oligomer concentration is 1 to 25% by mass, more preferably 5 to 15% by mass. If it is less than 1% by mass, the degree of polymerization tends to be difficult to increase. On the other hand, when it exceeds 25 mass%, an oligomer may precipitate and reaction may stop.

  The basic compound is not particularly limited as long as it can form various bisphenols and various bisthiophenols into an active phenoxide structure or thiophenoxide structure. For example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate , Sodium hydrogen carbonate, potassium hydrogen carbonate and the like.

  Water generated as a by-product during the reaction is removed by distilling it off with an azeotropic solvent such as toluene, or by using a water-absorbing material such as molecular sieve, or by distilling it off with a polymerization solvent. can do.

  The inorganic salt produced as a by-product during the reaction can be removed by any known method such as dropping the reaction solution into a poor solvent of the hydrophobic oligomer or washing the hydrophobic oligomer with the poor solvent. Examples of the poor solvent for the oligomer include water and an arbitrary organic solvent, and water is preferable for removing the inorganic salt. As the poor solvent to which the reaction solution is first dropped, either water or an organic solvent may be used.

  The organic solvent for the poor solvent can be selected from any organic solvent, but is preferably miscible with the aprotic polar solvent used in the reaction. Examples thereof include ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, dibutyl ketone, dipropyl ketone, diisopropyl ketone, and cyclohexanone, and alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol. These organic solvents may be used alone or in combination of two or more.

  It is preferable to remove the organic solvent used in the synthesis and purification as much as possible. The removal of the organic solvent is preferably performed by drying, and more preferably, the hydrophobic oligomer is dried under reduced pressure at a temperature in the range of 10 to 150 ° C.

(Hydrophilic segment)
The structure of the hydrophilic segment constituting the block copolymer of the present invention is represented by the following chemical formula 2

(Chemical formula 2)

(Wherein X is independently H or monovalent cation, Y is sulfonyl group or carbonyl group, Ar ² is independently divalent aromatic group, and L is independently sulfide. And m represents a number of 1 to 100.)

  In Chemical Formula 2, it is preferable that X is H because proton conductivity increases. When processing and molding the block copolymer, it is preferable that X is a monovalent metal ion such as Na, K, or Li because the stability of the copolymer is increased. X may be an organic cation such as monoamine.

  In Formula 2, it is preferable that Y is a sulfonyl group because the solubility of the block copolymer in a solvent tends to increase.

Ar ² may be any known divalent aromatic group mainly composed of aromatic groups, and examples thereof include divalent aromatic groups represented by the following chemical formulas 4A to 4C. A divalent aromatic group represented by 4B is preferable because of excellent swelling resistance and polymerization reactivity.

(In the formula, L represents a sulfide group or a sulfonyl group.)

(Method for producing hydrophilic segment)
The method for producing the hydrophilic segment (hydrophilic oligomer) is not particularly limited, and for example, it can be synthesized by reacting a sulfonated monomer represented by the following chemical formula 7 with various bisthiophenols. In addition, by using a dihalide such as 4,4′-dichlorodiphenylsulfone or 2,6-dichlorobenzonitrile together with a sulfonated monomer represented by the following chemical formula 7, it is synthesized by reacting with various bisthiophenols. Also good.

(Chemical formula 7)

  In Chemical Formula 7, X represents H or a monovalent cation, Y represents a sulfonyl group or a carbonyl group, and A represents a halogen element. X is preferably Na or K, and A is preferably F or Cl, respectively. In addition, it is preferable that various bisthiophenols become excessive so that the terminal group of the oligomer becomes an SH group. The degree of polymerization of the oligomer can be adjusted by the molar ratio of the monomer of formula 7 and various bisthiophenols.

  Although the monomer of Chemical formula 7 and various bisthiophenols can be reacted by any known method, it is preferably reacted by an aromatic nucleophilic substitution reaction in the presence of a basic compound.

  Regarding the reaction temperature, the basic compound that can be used, and the method for removing water produced as a by-product, the reaction temperature, basic compound, and removal method that can be used in the production of the hydrophobic segment can be used.

  When the aromatic nucleophilic substitution reaction is carried out in a solvent, it is preferable to prepare monomers and the like so that the resulting oligomer concentration is 5 to 50% by mass, and more preferably 20 to 40% by mass. If it is less than 5% by mass, the degree of polymerization tends to be difficult to increase. On the other hand, if it exceeds 50% by mass, the reaction system tends to be too viscous to make post-treatment of the reaction product difficult.

  The inorganic salt produced as a by-product during the reaction can be removed by any known method such as filtration of the reaction solution, decantation after centrifugal sedimentation, dialysis or salting out after adding water to the reaction solution. Filtration is preferable in terms of production efficiency and yield. When the inorganic salt is removed by filtration or centrifugal sedimentation, the hydrophilic oligomer can be recovered by dropping the reaction solution into a poor solvent for the hydrophilic oligomer. When the inorganic salt is removed by dialysis, the hydrophilic oligomer can be recovered by evaporation to dryness, and when the inorganic salt is removed by salting out, the hydrophilic oligomer can be recovered by filtration.

  The isolated hydrophilic oligomer is preferably purified by washing with a poor solvent, reprecipitation, dialysis or the like, and washing is preferred from the viewpoint of work efficiency and purification efficiency. As a poor solvent, the poor solvent enumerated as what can be used in the case of manufacture of a hydrophobic oligomer can be used.

  It is preferable to remove the organic solvent used in the synthesis and purification as much as possible. The removal of the organic solvent is preferably performed by drying, and more preferably dried under reduced pressure at 10 to 150 ° C.

  In addition, the block copolymer obtained using the hydrophilic oligomer synthesized by the above method has a hydrophilic segment represented by the following chemical formula 8 (that is, a block copolymer in which L in the chemical formula 2 is a sulfide group) Is obtained).

(Chemical formula 8)

  A block copolymer in which at least a part of L in Chemical Formula 2 is a sulfonyl group can be obtained by oxidizing a block copolymer having a hydrophilic segment represented by Chemical Formula 8 with an oxidizing agent. Examples of the oxidizing agent include at least one selected from the group consisting of peracetic acid, perbenzoic acid, perpropionic acid, perbutyric acid, hydrogen peroxide, sodium hypochlorite, chlorine, bromine, nitric acid, and peroxymonosulfuric acid. It is preferable to use a combination of acetic acid and hydrogen peroxide. Details of oxidation conditions and the like will be described later.

(Linking group)
In the block copolymer of the present invention, the hydrophobic segment and the hydrophilic segment have the following chemical formula 3

(Chemical formula 3)

(Wherein p represents 0 or 1, and when p is 1, W represents one or more selected from the group consisting of a direct bond (single bond), a sulfonyl group, and a carbonyl group). Connected by a group. With this configuration, it is possible to obtain a proton exchange membrane having high swelling resistance against hot water.

  In Chemical Formula 3, when p is 0, synthesis of the block copolymer is somewhat difficult, and therefore, p is preferably 1. When W is a direct bond between benzene rings, the characteristics and durability of the proton exchange membrane can be improved. When W is a sulfonyl group, side reactions during the synthesis of the block copolymer can be reduced.

(Block copolymer structure)
The block copolymer of the present invention has at least one hydrophobic segment represented by the above chemical formula 1, at least one hydrophilic segment represented by the above chemical formula 2, and a linking group in the molecule. It is a multi-block copolymer. Since the strength of the proton exchange membrane is improved, a multi-block copolymer is preferable.

  In the block copolymer of the present invention, the hydrophobic segment and the hydrophilic segment may be bonded to each other through the linking group. For example, a block copolymer in which hydrophilic segments and hydrophobic segments are alternately connected via a linking group, or each segment is randomly connected, and the hydrophilic segment and the hydrophobic segment have a linking group. And a block copolymer connected via each other.

  Since the hydrophilic segment is highly water-soluble, a block (co) polymer consisting only of the hydrophilic segment may cause problems such as elution when used as a proton exchange membrane. For this reason, the block copolymer of this invention needs to contain the hydrophilic segment and the hydrophobic segment in a molecule | numerator. The content of the hydrophilic segment in the block copolymer is preferably 10% to 70%, and more preferably 30% to 60%. When the content of the hydrophilic segment is less than 10%, proton conductivity may be remarkably lowered. When the content of the hydrophilic segment exceeds 70%, the swellability with respect to water increases, and the film strength may be significantly reduced.

  In the block copolymer of the present invention, the average molecular weight (A) of the hydrophilic segment and the average molecular weight (B) of the hydrophobic segment are each in the range of 4000 to 16000 (more preferably 4000 to 12000). And A / B is in the range of 0.7 to 2.5 (more preferably 0.7 to 2.2, still more preferably 0.7 to 1.3, particularly preferably 0.8 to 1.2). It is preferable because a proton exchange membrane excellent in characteristics such as durability and proton conductivity can be obtained.

In addition, although the molecular weight of each segment (oligomer) can be calculated | required by well-known arbitrary methods, such as a gel permeation chromatography method, it is preferable to quantitate a terminal group and to obtain | require a number average molecular weight. The end group can be quantified by any known method such as titration, colorimetric method, labeling method, NMR method, elemental analysis, but is preferable because the NMR method is simple and excellent in accuracy. ¹ H-NMR The method is more preferred.

  The hydrophobic oligomer constituting the block copolymer of the present invention is characterized by having a benzonitrile structure, but its solubility in a solvent is poor due to its structure. Therefore, in the case of NMR measurement, if it is not dissolved in a suitable deuterated solvent, deuterated dimethyl sulfoxide is added to a solution dissolved in a normal solvent in which a hydrophobic oligomer is dissolved, such as N-methyl-2-pyrrolidone. It is preferable to measure by adding a deuterated solvent such as

  The sulfonic acid group of the block copolymer of the present invention may be an acid or a salt with a cation, but is preferably a salt with a cation from the viewpoint of the stability of the sulfonic acid group. Conversion to an acid when the sulfonic acid group is a salt can be performed, for example, by acid treatment after molding.

  Although the preferable structure of the block copolymer of this invention is illustrated below below, the scope of the present invention is not limited to these. Further, in the block copolymer, the hydrophilic segment and the hydrophobic segment are not necessarily connected alternately. In the following formula, Ar is any one of the above linking groups, or a mixture thereof, X is H or a monovalent cation, L is independently a sulfide group or a sulfonyl group, and n and m are independently , Each represents a number from 1 to 100.

(Characteristics of block copolymer)
The block copolymer of the present invention has a logarithmic viscosity measured at 30 ° C. of a 0.5 g / dL solution using N-methyl-2-pyrrolidone as a solvent in a range of 0.5 to 5.0 dL / g. Preferably there is. If the logarithmic viscosity is less than 0.5 dL / g, the moldability may be poor and it may be difficult to form a film or the like. On the other hand, when the logarithmic viscosity exceeds 5.0 dL / g, the viscosity of the solution in which the block copolymer is dissolved becomes too high, which adversely affects workability. The logarithmic viscosity is more preferably in the range of 1.0 to 4.0 dL / g, and still more preferably in the range of 1.5 to 3.5 dL / g.

  The ion exchange capacity of the block copolymer of the present invention is preferably from 0.5 to 2.7 meq / g. When the ion exchange capacity is less than 0.5 meq / g, the proton conductivity of the proton exchange membrane obtained using the copolymer may be too low. On the other hand, if the ion exchange capacity exceeds 2.7 meq / g, the swelling property of the proton exchange membrane may increase and the mechanical durability may decrease. It is preferable for the ion exchange capacity to be 0.7 to 2.0 meq / g since a proton exchange membrane with even better proton conductivity and swelling resistance can be obtained. When the ion exchange capacity is 0.7 to 1.6 meq / g, the methanol permeability of the proton exchange membrane becomes small, so that a proton exchange membrane for a direct methanol fuel cell can be obtained, which is more preferable.

(Method for producing block copolymer)
The block copolymer of the present invention can be synthesized by any known method. For example, it can be produced by combining a previously synthesized hydrophilic oligomer and hydrophobic oligomer with a linking agent. The molar ratio of the linking agent to the sum of both oligomers is preferably close to 1.

  It can also be produced by modifying one end group of a previously synthesized hydrophilic oligomer or hydrophobic oligomer with a linking agent and then reacting the other oligomer. In this case, the modified oligomer and the other oligomer are preferably reacted in an equimolar amount. However, in order to prevent gelation due to a side reaction during the reaction, it is preferable that the modified oligomer is slightly excessive. The degree of excess varies depending on the molecular weight of the oligomer and the molecular weight of the target copolymer, but is preferably in the range of 0.1 to 50 mol%, more preferably in the range of 0.5 to 10 mol%. preferable. In addition, the hydrophobic oligomer is preferably modified with the linking agent. Depending on the structure of the hydrophilic oligomer, the modification reaction may not proceed well.

  Examples of the linking agent that bonds oligomers or modifies the end of one oligomer include compounds having structures represented by the following chemical formulas 9A to 9D. Among them, compounds of chemical formulas 9A and 9B are preferred, More preferred are compounds.

  As the hydrophobic oligomer and the hydrophilic oligomer, one or more kinds of oligomers selected from the group consisting of oligomers having different structures, molecular weights, and molecular weight distributions can be used.

  The block copolymer may be produced using an oligomer purified and isolated after oligomer synthesis or using a solution of this oligomer. Moreover, you may manufacture a block copolymer using an unpurified thing (reaction solution after oligomer synthesis | combination). Any oligomer may be purified and isolated, but a hydrophobic oligomer is preferred because it is easier.

  In the production of the block copolymer, the sulfonic acid group in the hydrophilic oligomer is preferably an alkali metal salt, more preferably Na or K. When ions forming a salt with a sulfonic acid group are of a plurality of types, an accurate molecular weight can be obtained by analyzing the composition in advance by elemental analysis. Alternatively, the hydrophilic oligomer may be once treated with an excess of acid and then treated with a metal salt or an alkali metal hydroxide to form one kind of ion that forms a salt with a sulfonic acid group. The hydrophilic oligomer is preferably dried immediately before the synthesis of the block copolymer to remove the adsorbed moisture. Drying may be performed by heating the hydrophilic oligomer to 100 ° C. or higher, and it is more preferable to dry under reduced pressure.

  The linking agent used in the production of the block copolymer of the present invention is preferably an aromatic linking agent substituted with fluorine. This is because fluorine is highly reactive and can suppress side reactions such as a decrease in segment length. The aromatic linking agent preferably has 3 or more fluorine atoms in one molecule, more preferably 2 or more fluorine atoms are adjacent to each other, and is a perfluoro compound. More preferred. This is because the reactivity is higher.

  The aromatic coupling agent may have an electron-withdrawing property as a substituent, and the electron-withdrawing group is preferably in the ortho position or the para position with respect to the fluorine atom. Examples of the electron withdrawing group include a cyano group, a sulfonyl group, a sulfinyl group, and a carbonyl group.

  Examples of the aromatic linking agent include a single aromatic ring (which may have an electron-withdrawing group as a substituent), or an aromatic ring in which a plurality of aromatic groups are linked with an electron-withdrawing group. Mention may be made of perfluorinated compounds. Specific examples include hexafluorobenzene, decafluorobiphenyl, decafluorobenzophenone, decafluorodiphenyl sulfone, and pentafluorobenzonitrile. Decafluorobiphenyl and decafluorodiphenyl sulfone are preferable, and decafluorobiphenyl is more preferable. These linking agents may be used alone or in combination of two or more.

  In addition, compounds in which some of the fluorine atoms in these compounds are substituted can be used as a linking agent. Examples of the substituent for the fluorine atom include a hydrogen atom, other halogen atoms such as chlorine, bromine and iodine, hydrocarbon groups such as a phenoxy group, a phenyl group and a methyl group.

  When a block copolymer is produced by combining a hydrophilic oligomer and a hydrophobic oligomer with a linking agent, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide In an aprotic polar solvent such as diphenylsulfone and sulfolane, in the range of 50 to 160 ° C. in the presence of a basic compound such as potassium carbonate or sodium carbonate in an amount of 1 to 5 mol times the oligomeric phenol or thiophenol end. The reaction is preferably carried out, more preferably in the range of 70 to 130 ° C.

  The reaction is preferably carried out under an inert gas stream such as nitrogen. The solid content concentration in the reaction solution may be 1 to 25% by mass, but it is preferably 5 to 20% by mass in consideration of poor reactivity and solubility of the hydrophobic oligomer. Most preferably, it is 8-15 mass%. The solid content concentration here is the concentration of the block copolymer in the solution. Whether or not the hydrophobic oligomer is dissolved can be determined by whether it is transparent by visual inspection or not.

  The degree of polymerization of the block copolymer and the content of the hydrophilic segment and the hydrophobic segment in the block copolymer can be adjusted by the molar ratio of the oligomer used in the reaction. Alternatively, the end point may be determined from the viscosity of the reaction solution, and the polymerization degree may be adjusted by stopping the polymerization reaction by cooling or stopping the end.

  Isolation and purification of the block copolymer from the reaction solution can be performed by any known method. For example, there is a method of solidifying the block copolymer by dropping the reaction solution into a poor solvent of the block copolymer such as water, acetone or methanol. As the poor solvent, water is preferable because it is easy to handle and inorganic salts can be removed. Further, in order to remove residual oligomer components and highly hydrophilic components, hot water at 60 ° C. to 100 ° C., water and organic solvents (ketone solvents such as acetone, alcohol solvents such as methanol, ethanol, and isopropanol). It is preferable to wash with a mixed solvent or the like.

  The block copolymer in which at least a part of L in Chemical Formula 2 is a sulfonyl group can be produced by oxidizing the block copolymer in which L obtained by the above method is a sulfide group. Specifically, L is a sulfide in an oxidizing agent such as peracetic acid, perbenzoic acid, perpropionic acid, perbutyric acid, hydrogen peroxide, sodium hypochlorite, chlorine, bromine, nitric acid and peroxymonosulfuric acid. The sulfide block can be converted to the sulfone bond by immersing the block copolymer of the group and heating to 30 to 80 ° C. Among these, it is preferable to oxidize in a mixed system of acetic acid and hydrogen peroxide. The oxidized oxidizing agent can be easily removed by immersing the block copolymer in water. The oxidation reaction can be carried out on either the copolymer powder or the membrane, but when the powder is oxidized, the reaction time may be longer if the diameter is large.

(Composition containing block copolymer)
The block copolymer of the present invention can also be used as a composition by mixing a third component. Examples of the third component include fibrous substances; heteropolyacids such as phosphotungstic acid and phosphomolybdic acid; acidic compounds such as low-molecular sulfonic acid, phosphonic acid and phosphoric acid derivatives; silicic acid compounds and zirconium phosphoric acid. Can be mentioned. The content of the third component is preferably less than 50% by mass in the composition. If it is 50% by mass or more, the physical properties of the molded product may be impaired. As the third component, a fibrous substance is preferable in order to suppress the swellability of a molded product obtained using the composition, and an inorganic fibrous substance such as potassium titanate fiber is more preferable.

  Moreover, it can replace with the said 3rd component or it can replace with a 3rd component, and can also be used as a composition which mixed the other polymer. Examples of these polymers include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon 6, nylon 6,6, nylon 6,10, and nylon 12; poly (meth) acrylic acid ester Acrylate resins such as polyphenols; poly (meth) acrylic acid resins; various polyolefins including diene polymers such as polyethylene, polypropylene and polystyrene; polyurethane resins; cellulose resins such as cellulose acetate and ethyl cellulose; polyarylate, aramid, Polycarbonate, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polyimide, polyamide , Polybenzimidazole, polybenzoxazole, aromatic polymers such as poly benzthiazole; epoxy resins, phenolic resins, novolak resins, thermosetting resins such as benzoxazine resins.

  When using a block copolymer as a composition, it is preferable that the block copolymer of this invention is contained 50 to 100 mass% of the whole composition. More preferably, it is 70 mass% or more and less than 100 mass%. When the content of the block copolymer is less than 50% by mass of the entire composition, the sulfonic acid group concentration of the proton exchange membrane obtained using this composition is low, and good proton conductivity cannot be obtained. In some cases, a unit containing a sulfonic acid group becomes a discontinuous phase and the mobility of ions to be conducted is lowered.

  The composition of the present invention can be used as necessary, for example, antioxidants, heat stabilizers, lubricants, tackifiers, plasticizers, crosslinking agents, viscosity modifiers, antistatic agents, antibacterial agents, antifoaming agents, and dispersing agents. Various additives such as a polymerization inhibitor may be included.

  The block copolymer of the present invention may be used as a solution dissolved in an appropriate solvent. Examples of the solvent include aprotic polar solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, diphenylsulfone, N-methyl-2-pyrrolidone, and hexamethylphosphonamide. Methyl-2-pyrrolidone and N, N-dimethylacetamide are preferred. These solvents may be used alone or in combination of two or more. The concentration of the block copolymer in the solution is preferably 0.1 to 50% by mass, more preferably 5 to 20% by mass, and further preferably 5 to 15% by mass. If the copolymer concentration in the solution is less than 0.1% by mass, it may be difficult to obtain a good molded product, and if it exceeds 50% by mass, the workability may be deteriorated. In this invention, you may use what mixed the above-mentioned 3rd component etc. in the said solution as a composition.

(Molded product, proton exchange membrane)
The block copolymer of the present invention and the composition thereof can be formed into a molded product such as a fiber or a film by any method such as extrusion, spinning, rolling or casting. The molded product is preferably obtained by molding using a solution in which a copolymer or a composition is dissolved in an appropriate solvent.

  As a method for obtaining a molded product from a solution, a conventionally known method can be used. For example, the method of heating a solution, drying under reduced pressure, adding a solution to the poor solvent of the copolymer which can be mixed with the solvent in a solution, and removing a solvent and obtaining a molding is mentioned. When the solvent is an organic solvent, the solvent is preferably distilled off by heating or drying under reduced pressure. At this time, it may be formed into various shapes such as a fiber shape, a film shape, a pellet shape, a plate shape, a rod shape, a pipe shape, a ball shape, and a block shape in a form combined with other compounds as necessary. it can. When combined with a compound having a similar dissolution behavior, it is preferable in that good molding can be achieved. The sulfonic acid groups in the molded product thus obtained may include those in the form of a salt with a cation, but if necessary, free sulfonic acid groups can be obtained by acid treatment of the molded product. Can also be converted.

  A proton exchange membrane can also be produced from the block copolymer of the present invention and the composition thereof. The proton exchange membrane may be composed only of the block copolymer membrane of the present invention, but may also be composed of a composite membrane with a support such as a porous membrane, nonwoven fabric, fibril, or paper. The obtained proton exchange membrane can be suitably used as a proton exchange membrane for a fuel cell.

  The most preferable method for obtaining a proton exchange membrane is casting from a solution, and the proton exchange membrane can be obtained by removing the solvent from the cast solution by the above method. The removal of the solvent is preferably performed by drying the solution in that a uniform proton exchange membrane can be obtained. Further, in order to avoid decomposition or alteration of the block copolymer or the solvent, it may be dried at a temperature as low as possible under reduced pressure. Further, when the viscosity of the solution is high, when the substrate or the solution is heated and cast at a high temperature, the viscosity of the solution is lowered and the casting can be easily performed. The thickness of the solution at the time of casting is not particularly limited, but is preferably 10 to 1000 μm, and more preferably 50 to 500 μm. If the thickness of the solution is thinner than 10 μm, the form as a proton exchange membrane may not be maintained. Moreover, when the thickness of the solution is larger than 1000 μm, a non-uniform proton exchange membrane is easily formed. As a method for controlling the cast thickness of the solution, a known method can be used. For example, a method of making the thickness constant by using an applicator, a doctor blade, etc., making the cast area constant by using a glass petri dish, etc., and controlling the thickness by the amount and concentration of the solution can be mentioned. Further, a more uniform film can be obtained by adjusting the removal rate of the solvent from the cast solution. For example, when removing the solvent by heating, there may be mentioned a method of lowering the evaporation rate by lowering the temperature in the first stage. When the cast solution is immersed in a poor solvent such as water, the solidification rate of the block copolymer is adjusted by, for example, leaving the cast solution in air or an inert gas for an appropriate time. Also, a uniform film can be obtained.

  The proton exchange membrane of the present invention can have any thickness depending on the purpose, but is preferably as thin as possible from the viewpoint of proton conductivity. Specifically, the thickness is preferably 5 to 200 μm, more preferably 5 to 100 μm, and most preferably 10 to 70 μm. If the thickness of the proton exchange membrane is less than 5 μm, it is difficult to handle the proton exchange membrane, and a short circuit may occur when a fuel cell is manufactured. On the other hand, if the thickness is greater than 200 μm, the electric resistance value of the proton exchange membrane may increase and the power generation performance of the fuel cell may deteriorate.

  The proton exchange membrane of the present invention may include those in which the sulfonic acid group in the membrane is a metal salt, but can be converted to free sulfonic acid by an appropriate acid treatment. The conversion to sulfonic acid is effectively carried out by immersing the proton exchange membrane in an aqueous solution of sulfuric acid, hydrochloric acid or the like at room temperature or under heating.

The proton conductivity of the proton exchange membrane of the present invention is preferably 1.0 × 10 ⁻³ S / cm or more. As a result, a good output tends to be obtained in a fuel cell using a proton exchange membrane. When the proton conductivity is less than 1.0 × 10 ⁻³ S / cm, the output of the fuel cell may decrease. The proton conductivity is more preferably 1.0 × 10 ^{−2 to} 1.0 S / cm.

  The proton exchange membrane of the present invention preferably has as little swelling as possible. If the swellability is too large, the film strength is lowered, and the durability may be lowered. However, if the amount is too small, necessary proton conductivity may not be obtained. When used as a proton exchange membrane of a fuel cell, the proton exchange membrane preferably has a water absorption rate (mass% of water absorbed relative to the dry mass of the proton exchange membrane) of 20 to 130 mass%, and 30 to 110 mass. % Is more preferable, and 50 to 95% by mass is even more preferable. Further, the area swelling rate of the proton exchange membrane (ratio of the increase in the area due to swelling relative to the area of the membrane before swelling) is preferably in the range of 0 to 20%, and in the range of 0 to 15%. More preferably, it is more preferably in the range of 0 to 13%, and particularly preferably in the range of 0 to 7%. Details of the swelling evaluation method will be described later.

  The swelling property of the proton exchange membrane can be adjusted by the amount of sulfonic acid group in the block copolymer, the chain length of the hydrophilic segment, the chain length of the hydrophobic segment, and the like. Increasing the amount of sulfonic acid groups can increase water absorption, and increasing the hydrophilic segment chain length can further increase water absorption. By reducing the amount of sulfonic acid groups or increasing the chain length of the hydrophobic segment, the area swelling rate can be reduced. The swelling property of the film can also be controlled by the process conditions (drying temperature, drying speed, solution concentration, solvent composition) for producing the film from the block copolymer.

  Since the proton exchange membrane of the present invention is composed of a block copolymer containing a hydrophobic segment and a hydrophilic segment, it usually forms a phase separation structure just by forming a membrane by the method described above. For the purpose of promoting the formation of phase separation, a poor solvent such as water may be added to the block copolymer solution to form a film, or the film may be formed in a humidified atmosphere.

  The proton exchange membrane of the present invention is also excellent in radical resistance. Specifically, the remaining rate of the film after 1 hour in the Fenton test can be 95% or more (more preferably 98% or more). Furthermore, the residual rate of the film after 3 hours can be 20% or more (more preferably 30% or more).

(Fuel cell electrode assembly)
By using the proton exchange membrane of the present invention, a fuel cell assembly can be obtained. As a method for producing this joined body, a conventionally known method can be used. For example, a method of applying an adhesive to the electrode surface and bonding the proton exchange membrane and the electrode, or a proton exchange membrane and the electrode There is a method of heating and pressurizing. Among these, the method of applying and bonding the sulfonic acid group-containing block copolymer or sulfonic acid group-containing random copolymer of the present invention and an adhesive mainly comprising the composition to the electrode surface is preferable. This is because the adhesion between the proton exchange membrane and the electrode is improved, and it is considered that the proton conductivity of the proton exchange membrane is less impaired.

  A fuel cell can also be produced using the above-mentioned joined body. Since the proton exchange membrane of the present invention is excellent in heat resistance, processability, and proton conductivity, it can withstand operation at high temperatures and can provide a fuel cell having good output. The proton exchange membrane of the present invention is suitable not only for polymer electrolyte fuel cells (PEFC) using hydrogen as fuel, but also for methanol direct fuel cells (DMFC) using methanol as fuel because of its low methanol permeability. ing. Moreover, since it is excellent in heat resistance and barrier properties, it is also suitable for a fuel cell of a type in which hydrogen is taken out from a hydrocarbon such as methanol, gasoline, ether, etc. by a reformer.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and can be implemented with appropriate modifications within a range that can be adapted to the above and the gist described below. These are all included in the technical scope of the present invention.

  First, the number average molecular weight of the segments produced by Examples and Comparative Examples, the logarithmic viscosity of the block copolymer, the ion exchange capacity of the proton exchange membrane, the proton conductivity, the swellability, and various measurement methods of the Fenton test will be described below. .

<Number average molecular weight>
Hydrophilic oligomer (sulfonic acid group is Na salt or K salt) or hydrophobic oligomer is dissolved in a solvent, and ¹ H-NMR is room temperature and ¹³ C-NMR is 70 ° C. using UNITY-500 manufactured by VARIAN. Each was measured. As the solvent, a mixed solvent of N-methyl-2-pyrrolidone and deuterated dimethyl sulfoxide (85/15 vol./vol.) Was used. The number average molecular weight was determined from the respective integration ratios of the peak derived from the end group and the peak of the skeleton in the obtained spectrum. For example, in the following hydrophobic oligomer A of Synthesis Example 1, the proton peak at the ortho position of the ether bond in the biphenyl structure is detected at 7.2 ppm from the end group (where it is bonded to perfluorobiphenyl). Since the amount in the skeleton was detected at 7.3 ppm, the number average molecular weight was determined from the integration ratio of these peaks. Further, when the molecular weight could not be calculated by the NMR method, the number average molecular weight obtained by the gel permeation chromatography method or the molecular weight calculated from the charged amount of the monomer was used as necessary.

<Logarithmic viscosity>
The copolymer powder was dissolved in N-methyl-2-pyrrolidone at a concentration of 0.5 g / dL, and the viscosity was measured using a Ubbelohde viscometer in a constant temperature bath at 30 ° C. to obtain a logarithmic viscosity (ln [ta / tb]) / c (ta represents the falling seconds of the sample solution, tb represents the falling seconds of the solvent alone, and c represents the copolymer concentration).

<Ion exchange capacity>
100 mg of the dried proton exchange membrane was immersed in 50 ml of 0.01N NaOH aqueous solution and stirred overnight at 25 ° C. Then, neutralization titration with 0.05N HCl aqueous solution was performed. For neutralization titration, a potentiometric titrator COMMITE-980 manufactured by Hiranuma Sangyo Co., Ltd. was used. The ion exchange capacity was determined from the following formula.
Ion exchange capacity [meq / g] = (10-titration [ml]) / 2

<Proton conductivity>
On a self-made measurement probe (made of polytetrafluoroethylene), a platinum wire (diameter: 0.2 mm) was pressed against the surface of the strip-shaped proton exchange membrane, and a constant temperature / humidity oven at 80 ° C. and 95% RH (Co., Ltd.) The proton exchange membrane was held in Nagano Kagaku Seisakusho, LH-20-01), and the impedance between the platinum wires was measured by SOLARTRON 1250 FREQUENCY RESPONSE ANALYSER. Conductivity measured by changing the interelectrode distance, and canceling the contact resistance between the proton exchange membrane and the platinum wire according to the following formula from the gradient obtained by plotting the interelectrode distance and the resistance measurement value estimated from the CC plot. Was calculated.
Conductivity [S / cm] = 1 / film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω / cm]

<Swellability>
A proton exchange membrane that had been left in a room at 23 ° C. and 50% RH for one day was cut out in a 50 mm square, and then immersed in hot water at 80 ° C. for 24 hours. After soaking, the dimensions and mass of the membrane were quickly measured. The membrane was dried at 120 ° C. for 3 hours, and the dry mass was measured. The water absorption rate and area swelling rate were calculated according to the following formula. In addition, the dimension of the film | membrane was calculated | required by measuring the length (A and B) of two orthogonal sides couple | bonded with the specific vertex.
Water absorption (%) = 100 × {mass after immersion (g) −dry mass (g)} ÷ dry mass (g)
Area swelling ratio (%) = 100 × {side length A (mm) after immersion × side length B (mm) after immersion} ÷ {50 × 50} −100

<Fenton test>
Ferrous sulfate (7 hydrate) 0.149 g was dissolved in 1 L of water to prepare a 30 ppm Fe aqueous solution. Fenton reagent was prepared by adding 50 g of 30% aqueous hydrogen peroxide to 50 ml of 30 ppm Fe aqueous solution, further adding water and stirring well to make the total amount 500 ml. 52 mg of proton exchange membrane whose mass was measured after drying at 100 ° C. for 1 hour in advance was immersed in 29 ml of Fenton reagent in a reagent bottle, treated at 60 ° C. for 1 hour or 3 hours, and the membrane was taken out. After washing with water and drying at 100 ° C. for 1 hour, the mass was measured. When the film did not retain its shape, the residue was filtered through a glass filter, dried at 100 ° C. for 1 hour, and then the mass was measured. The residual ratio (%) of the mass after the treatment relative to the mass before the treatment was determined.

  Next, a method for producing a proton exchange membrane from the block copolymers produced in Examples and Comparative Examples will be described.

<Method for producing proton exchange membrane>
On a film made of polyethylene terephthalate having a thickness of 190 μm, 20.0 g of a block copolymer (having a sulfonic acid group in a salt form) was dissolved in 180 mL of N-methyl-2-pyrrolidone (abbreviation: NMP) and filtered under pressure. The film was continuously cast at a thickness of 140 μm, dried by heating at 130 ° C. for 30 minutes, and the obtained film was wound with a film made of polyethylene terephthalate. The obtained membrane was continuously immersed in pure water in a state of being attached to a polyethylene terephthalate film, and then continuously immersed in a 1 mol / L sulfuric acid aqueous solution for 30 minutes to convert the sulfonic acid group into an acid form. It was converted, washed with pure water to remove free sulfuric acid, dried, and peeled from a polyethylene terephthalate film to obtain a proton exchange membrane.

  Hereinafter, the hydrophilic oligomer and the hydrophobic oligomer used in Examples and Comparative Examples will be described.

<Synthesis Example 1: Hydrophobic oligomer A>
2,6-dichlorobenzonitrile (abbreviation: DCBN) 70.50 g (408 mmol), 4,4′-biphenol (abbreviation: BP) 79.32 g (426 mmol), potassium carbonate 64.71 g (468 mmol), NMP 1046 mL, toluene 105 mL Was placed in a 2000 mL branch flask equipped with a nitrogen introduction tube, a stirring blade, a Dean-Stark trap, and a thermometer, and heated in a nitrogen stream while stirring in an oil bath. After dehydration by azeotropy with toluene at 140 ° C., all toluene was distilled off. Then, it heated up at 180 degreeC and heated for 6 hours. Then, it stood to cool to room temperature and obtained the hydrophobic oligomer A (liquid). When ¹ H-NMR measurement was performed on the obtained hydrophobic oligomer A, the number average molecular weight was determined to be 7050. The chemical structure of hydrophobic oligomer A is shown below.

<Synthesis Example 2: Hydrophobic oligomer B>
The hydrophobic oligomer was the same as in Synthesis Example 1 except that the amount of DCBN was 71.15 g (412 mmol), the amount of BP was 78.68 g (422 mmol), and the amount of potassium carbonate was 64.19 g (464 mmol). B (liquid) was obtained. The liquid was poured into 5 L of pure water little by little and solidified, and then immersed in pure water 5 times and in acetone 3 times to wash. Then, solid content was separated by filtration and dried under reduced pressure at 120 ° C. for 12 hours to obtain a hydrophobic oligomer B (solid). ^The number average molecular weight determined by ¹ H-NMR measurement was 12150. The chemical structure of hydrophobic oligomer B is shown below.

<Synthesis Example 3: Hydrophobic oligomer C>
96.143 g (286 mmol) of 2,2- (4-hydroxyphenyl) hexafluoropropane was used instead of BP, the amount of DCBN was 46.22 g (268 mmol), and the amount of potassium carbonate was 43.44 g (314 mmol). Except for the above, hydrophobic oligomer C (liquid) was obtained in the same manner as in Synthesis Example 1. ^The number average molecular weight determined by ¹ H-NMR measurement was 7211. The chemical structure of hydrophobic oligomer C is shown below.

<Synthesis Example 4: Hydrophobic oligomer D>
Instead of BP, 97.63 g (304 mmol) of 1,3-bis (4-hydroxyphenyl) adamantane was used, the amount of DCBN was 49.44 g (287 mmol), and the amount of potassium carbonate was 46.29 g (335 mmol). In the same manner as in Synthesis Example 1, a hydrophobic oligomer D (liquid) was obtained. ^The number average molecular weight determined by ¹ H-NMR measurement was 6977. The chemical structure of the hydrophobic oligomer D is shown below.

<Synthesis Example 5: Hydrophobic oligomer E>
In another 2000 mL branch flask equipped with a nitrogen introduction tube, stirring blade, cooling reflux tube, and thermometer, NMP200 mL and decafluorobiphenyl 34.08 g (102 mmol) were placed and stirred in an oil bath under a nitrogen stream. Heated to 110 ° C. Hydrophobic oligomer A was added thereto with stirring over 2 hours using a dropping funnel, and further stirred for 3 hours after completion of the addition. The reaction solution was cooled to room temperature and poured into 3000 mL of acetone to solidify the reaction product. The supernatant containing fine precipitates was removed, and further washed twice with acetone and then washed three times with pure water to remove NMP and inorganic salts. Thereafter, the reaction product was filtered off and dried under reduced pressure at 120 ° C. for 16 hours to obtain a hydrophobic oligomer E (solid) having a linking group. ^The number average molecular weight determined by ¹ H-NMR measurement was 7440. The chemical structure of hydrophobic oligomer E is shown below.

<Synthesis Example 6: Hydrophobic oligomer F>
The hydrophobic oligomer was the same as in Synthesis Example 1 except that the amount of BP was 91.63 g (492 mmol), the amount of DCBN was 81.30 g (471 mmol), and the amount of potassium carbonate was 74.76 g (541 mmol). (Liquid) was obtained. A hydrophobic oligomer F having a linking group was obtained in the same manner as in Synthesis Example 5, except that 48.94 g (122 mmol) of perfluorodiphenylsulfone was used instead of decafluorobiphenyl. ^The number average molecular weight determined by ¹ H-NMR measurement was 7553. The chemical structure of the hydrophobic oligomer F is shown below.

<Synthesis Example 7: Hydrophobic oligomer G>
The hydrophobic oligomer was the same as in Synthesis Example 1 except that the amount of BP was 70.19 g (377 mmol), the amount of DCBN was 62.28 g (361 mmol), and the amount of potassium carbonate was 57.27 g (414 mmol). (Liquid) was obtained. A hydrophobic oligomer G having a linking group was obtained in the same manner as in Synthesis Example 5, except that 34.04 g (94 mmol) of perfluorobenzophenone was used instead of decafluorobiphenyl. ^The number average molecular weight determined by ¹ H-NMR measurement was 7311. The chemical structure of the hydrophobic oligomer G is shown below.

<Synthesis Example 8: Hydrophobic oligomer H>
A hydrophobic oligomer H (solid) having a linking group was obtained in the same manner as in Synthesis Example 5 except that 18.98 g (102 mmol) of perfluorobenzene was used instead of decafluorobiphenyl. ^The number average molecular weight determined by ¹ H-NMR measurement was 7115. The chemical structure of the hydrophobic oligomer H is shown below.

<Synthesis Example 9: Hydrophobic oligomer I>
The synthesis was performed except that the amount of DCBN was 88.23 g (511 mmol), 117.32 g (537 mmol) of 4,4′-dimercaptobiphenyl was used instead of BP, and the amount of potassium carbonate was 81.64 g (591 mmol). In the same manner as in Example 1, a hydrophobic oligomer I (liquid) was obtained. ^The number average molecular weight determined by ¹ H-NMR measurement was 6845. The chemical structure of hydrophobic oligomer I is shown below.

<Synthesis Example 10: hydrophilic oligomer a>
255.65 g (520 mmol) of 4,4′-dichlorodiphenylsulfone-3,3′-disulfonic acid soda (abbreviation: S-DCDPS), 118.51 g (543 mmol) of 4,4′-dimercaptobiphenyl (abbreviation: DMBP) , 82.48 g (597 mmol) of potassium carbonate, 980 mL of NMP, and 99 mL of toluene were placed in a 2000 mL branch flask equipped with a nitrogen introduction tube, a stirring blade, a Dean-Stark trap, and a thermometer, and stirred in an oil bath under a nitrogen stream Heated. After dehydration by azeotropy with toluene at 140 ° C., all toluene was distilled off. Then, it heated up at 200 degreeC and heated for 2 hours. Subsequently, 500 mL of NMP was added, and the mixture was cooled to room temperature while stirring to obtain hydrophilic oligomer a (liquid). ^The number average molecular weight determined by ¹ H-NMR measurement was 15024. The chemical structure of the hydrophilic oligomer a is shown below.

<Synthesis Example 11: hydrophilic oligomer b>
It was obtained in the same manner as in Synthesis Example 10, except that the amount of S-DCDPS was 274.52 g (559 mmol), the amount of DMBP was 128.48 g (588 mmol), and the amount of potassium carbonate was 89.43 g (647 mmol). The obtained reaction product (liquid) was subjected to suction filtration with a 25G2 glass filter, whereby a yellow transparent reaction product (liquid) was obtained. The obtained reaction product (liquid) was dropped into 5 L of acetone and solidified to obtain a reaction product (solid). The reaction product (solid) was washed three times with acetone, then filtered and dried under reduced pressure to obtain hydrophilic oligomer b (solid). ^The number average molecular weight determined by ¹ H-NMR measurement was 12083. The chemical structure of the hydrophilic oligomer b is shown below.

<Synthesis Example 12: hydrophilic oligomer c>
Instead of S-DCDPS, 284.33 g (625 mmol) of 4,4′-difluorobenzophenone-3,3′-disulfonic acid soda was used, the amount of DMBP was changed to 143.25 g (656 mmol), and the amount of potassium carbonate was changed to 99. A hydrophilic oligomer c (solid) was obtained in the same manner as in Synthesis Example 11 except that the amount was 0.71 g (721 mmol). ^The number average molecular weight determined by ¹ H-NMR measurement was 12054. The chemical structure of the hydrophilic oligomer c is shown below.

<Synthesis Example 13: hydrophilic oligomer d>
The amount of S-DCDPS was 286.92 g (584 mmol), and 154.44 g (617 mmol) of 4,4′-thiobisbenzenedithiol was used instead of DMBP, and the amount of potassium carbonate was 93.73 g (678 mmol). Others were carried out similarly to the synthesis example 11, and obtained the hydrophilic oligomer d (solid). ^The number average molecular weight determined by ¹ H-NMR measurement was 12285. The chemical structure of the hydrophilic oligomer d is shown below.

<Synthesis Example 14: hydrophilic oligomer e>
The amount of S-DCDPS was changed to 283.11 g (576 mmol), 1,4′-benzenedithiol was used instead of DMBP, 85.73 g (603 mmol), and the amount of potassium carbonate was changed to 91.60 g (663 mmol). In the same manner as in Synthesis Example 11, a hydrophilic oligomer e (solid) was obtained. ^The number average molecular weight determined by ¹ H-NMR measurement was 12219. The chemical structure of the hydrophilic oligomer e is shown below.

<Comparative Synthesis Example 1: Hydrophilic oligomer f>
It was hydrophilic in the same manner as in Synthesis Example 10 except that the amount of S-DCDPS was 313.89 g (639 mmol), BP 129.85 g (697 mmol) was used instead of DMBP, and the amount of potassium carbonate was 105.97 g (767 mmol). Sex oligomer f (liquid) was obtained. ^The number average molecular weight determined by ¹ H-NMR measurement was 6721. The chemical structure of the hydrophilic oligomer f is shown below.

<Comparative Synthesis Example 2: Hydrophilic oligomer g>
Hydrophilicity was obtained in the same manner as in Synthesis Example 11 except that the amount of S-DCDPS was 328.33 g (668 mmol), 130.73 g (702 mmol) of BP was used instead of DMBP, and the amount of potassium carbonate was 106.69 g (772 mmol). The resulting oligomer g (solid) was obtained. ^The number average molecular weight determined by ¹ H-NMR measurement was 12132. The chemical structure of the hydrophilic oligomer g is shown below.

  In the above hydrophilic oligomer synthesis examples and comparative synthesis examples, some of the sulfonic acid groups in the polymer seem to be potassium salts. .

<Example 1>
199.54 g of hydrophilic oligomer a, 294.06 g of hydrophobic oligomer A, 0.94 g of potassium carbonate, 2.34 g of decafluorobiphenyl, and 277 mL of NMP, a 1000 mL branch flask equipped with a nitrogen introduction tube, a stirring blade, a Dean-Stark trap, and a thermometer And stirred in an oil bath at 50 ° C. for 1 hour under a nitrogen stream, and then heated to 110 ° C. and allowed to react for 8 hours. Thereafter, the reaction solution was cooled to room temperature and dropped into 1 L of pure water to solidify the product (block copolymer) in the reaction solution. It was treated at 80 ° C. for 2 hours while immersed in pure water, and then the block copolymer was separated by filtration, and this operation was repeated 4 times. Then, it dried under reduced pressure at 120 degreeC for 12 hours. The logarithmic viscosity of the obtained block copolymer was 2.2 dL / g. A proton exchange membrane A was obtained from the block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 2>
A block copolymer was obtained in the same manner as in Example 1 except that 53.21 g of hydrophilic oligomer b, 37.45 g of hydrophobic oligomer B, 1.14 g of sodium carbonate, 2.51 g of decafluorobiphenyl, and 811 mL of NMP were used. The resulting block copolymer had a logarithmic viscosity of 2.4 dL / g. A proton exchange membrane B was obtained from the block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 3>
A block copolymer was obtained in the same manner as in Example 1, except that hydrophilic oligomer solution a 114.61 g, hydrophobic oligomer solution C 182.55 g, potassium carbonate 0.63 g, decafluorobiphenyl 1.38 g, and NMP 160 mL were used. . The logarithmic viscosity of the obtained block copolymer was 2.3 dL / g. A proton exchange membrane C was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 4>
A block copolymer was obtained in the same manner as in Example 1 except that 138.73 g of the hydrophilic oligomer solution a, 217.96 g of the hydrophobic oligomer solution D, 0.77 g of potassium carbonate, 1.699 g of decafluorobiphenyl, and 198 mL of NMP were used. . The logarithmic viscosity of the obtained block copolymer was 2.3 dL / g. A proton exchange membrane D was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 5>
A block copolymer was obtained in the same manner as in Example 1 except that 52.90 g of hydrophilic oligomer b, 32.57 g of hydrophobic oligomer E, 1.33 g of potassium carbonate, and 817 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 1.6 dL / g. A proton exchange membrane E was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 6>
A block copolymer was obtained in the same manner as in Example 1 except that 54.13 g of hydrophilic oligomer b, 33.84 g of hydrophobic oligomer F, 1.36 g of potassium carbonate, and 840 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 1.5 dL / g. A proton exchange membrane F was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 7>
A block copolymer was obtained in the same manner as in Example 1 except that 51.19 g of the hydrophilic oligomer b, 30.97 g of the hydrophobic oligomer G, 1.29 g of potassium carbonate, and 785 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 1.7 dL / g. A proton exchange membrane G was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 8>
A block copolymer was obtained in the same manner as in Example 1 except that 54.38 g of hydrophilic oligomer b, 32.02 g of hydrophobic oligomer H, 1.37 g of potassium carbonate, and 825 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 1.4 dL / g. A proton exchange membrane H was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 9>
A block copolymer was obtained in the same manner as in Example 1 except that 55.16 g of hydrophilic oligomer c, 38.92 g of hydrophobic oligomer B, 1.18 g of potassium carbonate, 2.60 g of decafluorobiphenyl, and 842 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 2.1 dL / g. A proton exchange membrane I was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 10>
A block copolymer was obtained in the same manner as in Example 1 except that 53.76 g of the hydrophilic oligomer d, 37.22 g of the hydrophobic oligomer B, 1.13 g of potassium carbonate, 2.96 g of perfluorodiphenylsulfone and 818 mL of NMP were used. The resulting block copolymer had a logarithmic viscosity of 2.6 dL / g. A proton exchange membrane J was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 11>
A block copolymer was obtained in the same manner as in Example 1 except that 51.45 g of hydrophilic oligomer e, 35.81 g of hydrophobic oligomer B, 1.09 g of potassium carbonate, 2.59 g of perfluorobenzophenone, and 782 mL of NMP were used. The resulting block copolymer had a logarithmic viscosity of 2.5 dL / g. A proton exchange membrane K was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 12>
A block copolymer was obtained in the same manner as in Example 1 except that 50.58 g of the hydrophilic oligomer e, 212.41 g of the hydrophobic oligomer solution I12.41 g, 1.07 g of potassium carbonate, 1.31 g of perfluorobenzene, and 451 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 2.2 dL / g. A proton exchange membrane L was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Comparative Example 1>
A block copolymer was obtained in the same manner as in Example 1 except that hydrophilic oligomer solution f373.15 g, hydrophobic oligomer solution A663.15 g, potassium carbonate 3.22 g, decafluorobiphenyl 7.07 g, and NMP 550 mL were used. . The resulting block copolymer had a logarithmic viscosity of 2.4 dL / g. A proton exchange membrane M was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Comparative example 2>
A block copolymer was obtained in the same manner as in Example 1 except that 85.10 g of hydrophilic oligomer g, 59.66 g of hydrophobic oligomer B, 1.81 g of potassium carbonate, 3.98 g of decafluorobiphenyl, and 1295 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 2.8 L / g. A proton exchange membrane N was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Comparative Example 3>
<Hydrophobic oligomer J>
The hydrophobic oligomer was the same as in Synthesis Example 1 except that the amount of DCBN was 73.14 g (424 mmol), the amount of BP was 77.42 g (415 mmol), and the amount of potassium carbonate was 63.16 g (457 mmol). J (liquid) was obtained. The liquid was poured into 5 L of pure water little by little and solidified, and then immersed in pure water 5 times and in acetone 3 times to wash. Then, solid content was separated by filtration and dried under reduced pressure at 120 ° C. for 12 hours to obtain a hydrophobic oligomer J (solid). ^The number average molecular weight determined by ¹ H-NMR measurement was 14210. The chemical structure of the hydrophobic oligomer J is shown below.

<Hydrophilic oligomer h>
The same procedure as in Synthesis Example 10 except that the amount of S-DCDPS was 249.30 g (507 mmol), 96.96 g (520 mmol) of BP was used instead of DMBP, and the amount of potassium carbonate was 79.13 g (573 mmol). The reaction product (liquid) obtained in this manner was subjected to suction filtration with a 25G2 glass filter, whereby a yellow transparent reaction product (liquid) was obtained. The obtained reaction product (liquid) was dropped into 5 L of acetone and solidified to obtain a reaction product (solid). The reaction product (solid) was washed 3 times with acetone, then filtered and dried under reduced pressure to obtain hydrophilic oligomer h (solid). ^The number average molecular weight determined by ¹ H-NMR measurement was 24100. The chemical structure of the hydrophilic oligomer h is shown below.

  A block copolymer was prepared in the same manner as in Example 1 except that 44.06 g of hydrophilic oligomer h, 23.89 g of hydrophobic oligomer J, 0.47 g of sodium carbonate, and 380 mL of NMP were used, the reaction temperature was 160 ° C., and the reaction time was 60 hours. A polymer was obtained. The logarithmic viscosity of the obtained block copolymer was 1.5 dL / g. A proton exchange membrane O was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Comparative example 4>
<Hydrophobic oligomer K>
The amount of BP was 54.19 g (291 mmol), 81.30 g (282 mmol) of 4,4′-dichlorodiphenylsulfone (abbreviation: DCDPS) was used instead of DCBN, and the amount of potassium carbonate was 44.21 g (320 mmol). A hydrophobic oligomer K having a linking group was obtained in the same manner as in Synthesis Example 5, except that 16.37 g (49 mmol) of decafluorobiphenyl was used. ^The number average molecular weight determined by ¹ H-NMR measurement was 14170. The chemical structure of the hydrophobic oligomer K is shown below.

  A block copolymer was obtained in the same manner as in Example 1 except that 44.06 g of hydrophilic oligomer h, 23.87 g of hydrophobic oligomer K, 0.47 g of sodium carbonate, and 380 mL of NMP were used. The logarithmic viscosity of the obtained block copolymer was 1.2 dL / g. A proton exchange membrane P was obtained from the obtained block copolymer by the method for producing a proton exchange membrane. The chemical structure of the block copolymer is shown below.

<Example 13>
0.70 g of proton exchange membrane A was immersed in a mixed solution of 100 ml of acetic acid, 7.5 ml of concentrated sulfuric acid, and 5.5 ml of 36.5% hydrogen peroxide solution at 30 ° C. for 24 hours. Then, it cooled to room temperature and then immersed in pure water for 2 hours. This was repeated 4 times. The membrane after washing with water was dried under reduced pressure at 120 ° C. to obtain a proton exchange membrane a. The chemical structure of the block copolymer constituting the proton exchange membrane a is shown below. The ¹ H-NMR spectrum of the block copolymer is shown in FIG. Peaks ai in the figure belong to protons ai in the chemical formula.

<Example 14>
A proton exchange membrane b was obtained in the same manner as in Example 13 except that 0.83 g of the proton exchange membrane B and a mixed solution of acetic acid 118 ml, concentrated sulfuric acid 8.9 ml, and 36.5% hydrogen peroxide water 6.5 ml were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane b is shown below.

<Example 15>
A proton exchange membrane c was obtained in the same manner as in Example 13 except that 0.67 g of proton exchange membrane C and a mixed solution of 95 ml of acetic acid, 7.2 ml of concentrated sulfuric acid, and 5.2 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane c is shown below.

<Example 16>
A proton exchange membrane d was obtained in the same manner as in Example 13 except that 0.76 g of proton exchange membrane D and a mixed solution of 109 ml of acetic acid, 8.1 ml of concentrated sulfuric acid, and 6.0 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane d is shown below.

<Example 17>
Proton exchange membrane e was obtained in the same manner as in Example 13 except that 0.72 g of proton exchange membrane E and a mixed solution of 104 ml of acetic acid, 7.7 ml of concentrated sulfuric acid, and 6.0 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane e is shown below.

<Example 18>
A proton exchange membrane f was obtained in the same manner as in Example 13 except that 0.56 g of the proton exchange membrane F and a mixed solution of 80 ml of acetic acid, 6.0 ml of concentrated sulfuric acid, and 4.4 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane f is shown below.

<Example 19>
A proton exchange membrane g was obtained in the same manner as in Example 13 except that 0.53 g of the proton exchange membrane G, 76 ml of acetic acid, 5.8 ml of concentrated sulfuric acid, and 4.2 ml of 36.5% hydrogen peroxide water were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane g is shown below.

<Example 20>
A proton exchange membrane h was obtained in the same manner as in Example 13, except that 0.65 g of proton exchange membrane H, 93 ml of acetic acid, 7.0 ml of concentrated sulfuric acid, and 5.1 ml of 36.5% hydrogen peroxide solution were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane h is shown below.

<Example 21>
Proton exchange membrane i was obtained in the same manner as in Example 13 except that 0.78 g of proton exchange membrane I and a mixed solution of acetic acid 111 ml, concentrated sulfuric acid 8.4 ml, and 36.5% hydrogen peroxide solution 6.1 ml were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane i is shown below.

<Example 22>
A proton exchange membrane j was obtained in the same manner as in Example 13 except that 0.55 g of the proton exchange membrane J and a mixed solution of 79 ml of acetic acid, 5.9 ml of concentrated sulfuric acid, and 4.3 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane j is shown below.

<Example 23>
Proton exchange membrane k was obtained in the same manner as in Example 13 except that 0.67 g of proton exchange membrane K and a mixed solution of 95 ml of acetic acid, 7.2 ml of concentrated sulfuric acid, and 5.2 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane k is shown below.

<Example 24>
A proton exchange membrane 1 was obtained in the same manner as in Example 13 except that 0.76 g of the proton exchange membrane L and a mixed solution of 107 ml of acetic acid, 8.2 ml of concentrated sulfuric acid, and 5.9 ml of 36.5% hydrogen peroxide were used. It was. The chemical structure of the block copolymer constituting the proton exchange membrane 1 is shown below.

  Table 1 shows the evaluation results of the proton exchange membranes obtained in the examples and comparative examples.

  Although the proton exchange membrane of the present invention exhibits proton conductivity equivalent to or higher than that of a comparative example with a different structure, the area swelling is smaller and the dimensional stability is excellent. Moreover, it turns out that it is excellent also in radical resistance. This is considered to be derived from the hydrophilic segment structure of the copolymer constituting the proton exchange membrane of the present invention.

  The block copolymer of the present invention can be used as a proton exchange membrane for fuel cells that can exhibit high output and high durability, and greatly contributes to industrial development.

Claims (6)

Chemical formula 1
(Chemical formula 1)
(In the formula, each Z independently represents an O atom or an S atom, Ar ¹ independently represents a divalent aromatic group, and n represents a number of 1 to 100, respectively.)
A hydrophobic segment represented by
Chemical formula 2
(Chemical formula 2)
(Wherein X is independently H or monovalent cation, Y is sulfonyl group or carbonyl group, Ar ² is independently divalent aromatic group, and L is independently sulfide. A group or a sulfonyl group, m represents a number of 1 to 100, respectively.)
The hydrophobic segment and the hydrophilic segment are represented by the chemical formula 3
(Chemical formula 3)
(In the formula, p represents 0 or 1, and when p is 1, W represents one or more selected from the group consisting of a direct bond, a sulfonyl group, and a carbonyl group.)
A block copolymer bonded with a group represented by the formula: Ar ² is represented by the chemical formula 4
(Chemical formula 4)
The block copolymer of Claim 1 represented by these.   The block copolymer according to claim 1 or 2, wherein the 0.5 g / dL solution using N-methyl-2-pyrrolidone as a solvent has a logarithmic viscosity at 30 ° C of 0.5 to 5.0 dL / g.   A molded product comprising the block copolymer according to any one of claims 1 to 3.   A proton exchange membrane for a fuel cell, wherein the molded product according to claim 4 is used.   6. A fuel cell electrode assembly comprising the fuel cell proton exchange membrane according to claim 5.