KR20120108611A - Proton conducting copolymer containing diphenyl fuorene-sulfonic acid group, manufacturing method thereof, proton conducting polymer membrane, membrane-electrolyte assembly, and polymer electrolyte membrane fuel cell using the same - Google Patents

Abstract

PURPOSE: A proton-conducting copolymer is provided to have flexible and strong mechanical performance, to have excellent hydrogen ion conductivity, thereby capable of providing a polymer electrolyte membrane with high thermal and mechanical stability, dimensional stability and hydrogen ion conductivity. CONSTITUTION: A proton-conductive copolymer comprises a diphenyl fluorene group in which a sulfone group is accepted in a molecule and is represented by chemical formula 1. In chemical formula 1, A is -H or -SO3H, L1 and L2 is an ether group or a sulfone group, but at least one is sulfone group, m and n is an integer fro 2-500, and m/(n+m) is 0.05-50. A proton-conductive polymer electrolyte membrane is manufactured by dissolving the proton-conductive copolymer into an organic solvent, casting the solution on a glass or teflon plate, and drying the casted material.

Description

Hydrogen ion conductive copolymer comprising a diphenylfluorene group having sulfonic acid group introduced therein, a method for preparing the same, a polymer electrolyte membrane prepared therefrom, a membrane-electrode assembly using the same, and a polymer electrolyte membrane fuel cell employing the same -SULFONIC ACID GROUP, MANUFACTURING METHOD THEREOF, PROTON CONDUCTING POLYMER MEMBRANE, MEMBRANE-ELECTROLYTE ASSEMBLY, AND POLYMER ELECTROLYTE MEMBRANE FUEL CELL USING THE SAME}

The present invention relates to a hydrogen ion conductive copolymer comprising diphenyl fluorene having sulfonic acid groups, a method for preparing the same, a polymer electrolyte membrane prepared therefrom, a membrane-electrode assembly using the same, and a polymer electrolyte membrane fuel cell employing the same. In more detail, by containing a diphenyl fluorene group having a sulfonic acid group introduced into the copolymer and a phenyl ether group and a phenyl sulfone group in an appropriate ratio, it is excellent in mechanical stability and dimensional stability, sulfonic acid of high hydrogen conductivity characteristics The present invention relates to a copolymer having excellent hydrogen ion conductivity, a method for producing the same, a polymer electrolyte membrane prepared therefrom, a membrane-electrode assembly using the same, and a polymer electrolyte membrane fuel cell employing the same.

The polymer electrolyte fuel cell means an entire fuel cell using a polymer electrolyte membrane as an electrolyte, and typical polymer electrolyte membrane fuel cells using hydrogen as a fuel and a direct methanol fuel cell using methanol as a fuel.

The polymer electrolyte fuel cell uses a hydrogen ion conductive polymer membrane (PEM) as an electrolyte, so there is no electrolyte loss, and it is not affected by the pressure change of the reactor, and the volume and It has the advantage of small weight. Compared to the output density of the polymer electrolyte fuel cell, the polymer electrolyte membrane fuel cell is superior to the direct methanol fuel cell, but the polymer electrolyte membrane fuel cell has a relatively high thermal and mechanical stability due to its relatively high operating temperature. shall.

The polymer electrolyte membrane fuel cell has a basic configuration of a polymer electrolyte membrane, a fuel electrode and an air electrode. Hydrogen introduced into the anode is oxidized by a catalyst and separated into hydrogen ions (H ⁺ ) and electrons (e ⁻ ), and are moved to the cathode through the electrolyte and the external circuit, respectively. Oxygen or air introduced into the cathode reduces hydrogen ions transferred through the electrolyte membrane to generate water and heat, and electrical energy is generated by electrons moved through an external circuit in the process. At this time, the oxidation-reduction reaction generated at each electrode is as follows:

A fuel electrode ^{_{(Anode): H 2 2H +}} + 2e -

Cathode: 1 / 2O ₂ + 2H ⁺ + 2e ^- H ₂ O + heat

The polymer electrolyte membrane for a fuel cell should also serve as a separator for separating fuel and reactant gases while providing a passage for hydrogen ions. Furthermore, the polymer electrolyte membrane, which is intended for application to the polymer electrolyte membrane, should not exhibit deterioration even during long-term repeated operation under high temperature and low humidification conditions or high temperature and non-humidity conditions of 80 ^° C. or higher, even in high temperature and strong acidic environments. Thermal, physical and chemical stability should be good.

Perfluoro-based ion exchange membranes such as Dupont's Nafion, which have been used in most fuel cells to date, have been spotlighted for their excellent chemical resistance, oxidation resistance, and high ion conductivity. When incinerated, there is a disadvantage in that fluorine-based gas is emitted, which may pollute the environment.

In order to improve this problem, as a Nafion membrane replacement material, polysulfone (polysulfone), polyether sulfone (poly (ether sulfone)), polyether ketone (poly (ether ketone)), polyimide (polyimide) Research into imparting hydrogen ion conductivity by introducing sulfonic acid groups into hydrocarbon-based heat-resistant polymers such as these is being actively conducted.

The method for producing a hydrocarbon-based ion conductor having a sulfonic acid group can be divided into two types according to the method of introducing a sulfonic acid group. First, a method using a post-sulfonation method of polymerizing a hydrocarbon-based heat resistant polymer first using only a monomer having no sulfonic acid group and then introducing a sulfonic acid group using an appropriate sulfonation agent and a sulfonic acid group have already been introduced. Direct polymerization is used to obtain a polymer through a polymerization reaction using a monomer in an appropriate ratio.

In the case of the direct polymerization method, a high purity sulfonated monomer that can be used for polymerization is required. The preparation and purification process using sulfonating agents such as fuming sulfuric acid is very difficult, expensive, and commercially available. The structure sold is very limited. In addition, even in the polymerization reaction using the sulfonated monomer, it is very difficult to control the equivalent weight of the monomer necessary for obtaining a high degree of polymerization by the high hydrophilicity of the sulfonic acid group. In addition, the polymerization temperature is very difficult to control because the sulfonic acid group of the sulfonated monomer starts to desorb around about 250 ^° C. As such, when the direct polymerization method is used, it is expensive and disadvantageous for mass production due to the securing of monomers and difficult polymerization conditions.

On the other hand, in the case of using the phonation reaction described below, it is possible to easily use inexpensive monomers of various commercialized structures in polymer polymerization. In addition, since hydrophilic sulfonated monomers are not used, water absorption does not occur, and thus the equivalent weight control between monomers is simple and free from sulfonic acid desorption problems. In the case of the following phonation reaction in which the sulfonic acid group is introduced into the polymerized polymer as described above, the reaction conditions and the purification process are simple, so that the economic efficiency of the process is excellent and the mass production is very effective.

However, the biggest obstacle when using the phonation reaction described later is that it is difficult to control the rate of introduction of sulfonic acid groups, that is, the degree of sulfonation, and, in some cases, the degradation of the polymer chain due to the strong acidity of the sulfonating agent. Is that there is. In general, sulfonating agents of strong acids such as fuming sulfuric acid, concentrated sulfuric acid, and chlorosulfonic acid are used, and sulfonic acid groups are introduced around carbons having high electron density in the benzene ring of aromatic polymers. At this time, as the sulfonation reaction time elapses, more sulfonic acid groups are introduced. If the sulfonation degree is too high, the swelling caused by water may be very large or dissolved at all when the electrolyte membrane is manufactured in the future. . In addition, when exposed to strong acid for a long time, there will also appear a problem that the polymer chain is decomposed. Therefore, in the case of the phonation reaction described later, it is difficult to control temperature and time, and there is a limit in establishing and reproducing manufacturing conditions.

As an approach to overcome this problem, studies have recently been conducted to limit the parts to which sulfonic acid groups can be attached in the polymer structure by using a low electron density (electron-plug) monomer. The sulfonic acid group is not easily introduced to the monomer having a low electron density, so that the sulfonation degree can be controlled so that excessive sulfonic acid group is not introduced to the structure including the electron withdrawing. However, when only monomers having a low electron density are used, it is difficult to form a high molecular weight by monomers having low reactivity during polymerization. As a method for overcoming these disadvantages, the present invention provides a high molecular weight by first forming a high molecular weight through a polymerization reaction of a monomer having an electron donor property, and then converting the electron withdrawal property through an oxidation reaction, and then performing a phonation reaction described later. There is provided a new production method capable of both easy sulfonation control and a new structure copolymer prepared therefrom.

The present inventors have made efforts to solve the conventional problems and to provide a hydrocarbon polymer of low cost and excellent conductivity. As a result, a random copolymer or a thiol or alcohol monomer having a diphenyl fluorene alcohol monomer and a thioether linking group is used. By preparing a block copolymer and preparing a sulfonated copolymer through selective phonation reaction after the oxidation reaction of such a polymer, a hydrogen ion conductive copolymer having excellent hydrogen ion conductivity characteristics and dimensional stability which is inexpensive and advantageous for mass production A polymer electrolyte membrane, a membrane-electrode assembly, and a polymer electrolyte membrane fuel cell using the same were prepared. Through the evaluation of unit cell performance, the polymer electrolyte membrane of the present invention can replace the conventional commercial Nafion membrane. Ionic Conductivity Characteristics By checking, and completed the present invention.

It is an object of the present invention to provide a hydrogen ion conductive copolymer comprising a diphenylfluorene group having a sulfonic acid group introduced therein.

It is another object of the present invention to provide a method for preparing a sulfonated hydrogen ion conductive copolymer through polymerization reaction and oxidation of polymerized polymer using an unsulfonated monomer, and optionally later phonation reaction.

Another object of the present invention is to provide a sulfonated polymer electrolyte membrane using a sulfonated hydrogen ion conductive copolymer.

It is another object of the present invention to provide a membrane-electrode assembly composed of a polymer electrolyte membrane having improved physical properties and a polymer electrolyte membrane fuel cell employing the same.

The hydrogen ion conductive copolymer of the present invention for achieving the above object is a copolymer containing a diphenyl fluorene group introduced with a sulfonic acid group, represented by the following general formula (1):

[Formula 1]

Wherein A is -H or -SO ₃ H, L ₁ , and L ₂ are ether group (-O-) or sulfone group (-SO _2- ) with at least one sulfone group, m and n are 2 It is an integer of -500, and m / (n + m) is 0.05-50.

The copolymer may be a random copolymer in which diphenylfluorene groups into which sulfonic acid groups are introduced are evenly distributed in the polymer chain, or a block copolymer in which diphenylfluorene groups into which sulfonic acid groups are introduced are separated in a block form.

It is preferable that the intrinsic viscosity of the copolymer is 0.1 to 3.0 dl / g on 25 NMP (N-methyl-a-pyrrolidinone).

Method for producing a hydrogen ion conductive copolymer of the present invention,

A) Copolymerization of an aromatic halogen monomer (compound 2), a monomer having a diphenyl fluorene group (compound 3), and a monomer having a ether or thioether group (compound 4) to copolymerize the ether or thioether linking group in the main chain First step of obtaining (Compound 5);

B) a second step of obtaining a copolymer (compound 6) containing a diphenyl fluorene group and having a sulfone and ether linkage by oxidizing the thioether linking group in the copolymer (compound 5) to a sulfone linker; And

C) a copolymer having a sulfone and an ether linkage group (Compound 6) reacted with a sulfonating agent to introduce a sulfonic acid group, including a diphenylfluorene group having a sulfonic acid group introduced therein, and having a phenyl sulfone and a phenylether group (Compound 1) Obtaining a third step;

It is carried out by the following Scheme 1:

[Reaction Scheme 1]

In the above scheme, X is -F, -Cl or -NO ₂ , J ₁ is -OH or -SH, J ₂ is -O- or -S-, K ₁ , K ₂ is -O- or- S-, L ₁ , and L ₂ are ether groups (-O-) or sulfone groups (-SO _2- ), at least one is a sulfone group, m and n are integers from 2 to 500, and m / (n + m) is 0.05-50, A is -H or -SO ₃ H.

The first step,

A-1) Synthesizing oligomer 1 by polymerizing an aromatic halogen monomer (compound 2) and a monomer having a diphenylfluorene group (compound 3), and separately a monomer having an aromatic halogen monomer (compound 2) and an ether or thioether group. Sub 1-1 to polymerize (Compound 4) to synthesize oligomer 2; And

A-2) first and second substeps of copolymerizing the oligomer 1 and oligomer 2 again to obtain a copolymer (compound 5) in which an ether or thioether linking group is present in the main chain;

It may be to include.

The hydrogen ion conductive polymer electrolyte membrane of the present invention is prepared by dissolving the hydrogen ion conductive copolymer in an organic solvent and then casting it on a glass or Teflon plate and then drying.

The thickness of the polymer electrolyte membrane is preferably 30 ~ 50㎛.

Preferably, the polymer electrolyte membrane has an ion conductivity of 0.05 S / cm or more at 80 degrees.

The membrane-electrode assembly for an electrolyte membrane fuel cell of the present invention comprises the hydrogen ion conductive polymer electrolyte membrane.

The present invention provides a copolymer comprising a diphenyl fluorene group having a sulfonic acid group introduced therein, thereby providing a hydrogen ion conductive polymer electrolyte membrane which is inexpensive, advantageous for mass production, and has excellent hydrogen ion conductivity characteristics and dimensional stability. It can replace the Nafion (eg Nafion-112) membrane.

In addition, by providing a membrane-electrode assembly for a polymer electrolyte membrane fuel cell composed of the polymer electrolyte membrane of the present invention, and ultimately employed, the polymer electrolyte membrane fuel cell with improved durability and performance by improving mechanical stability and dimensional stability and ion conductivity characteristics Can be provided.

Hereinafter, the present invention will be described in detail.

The present invention provides a copolymer containing a diphenyl fluorene group introduced with a sulfonic acid group, a hydrogen ion conductive copolymer represented by the following general formula (1):

[Formula 1]

Wherein A is -H or -SO ₃ H, L ₁ , and L ₂ are ether group (-O-) or sulfone group (-SO _2- ) with at least one sulfone group, m and n are 2 It is an integer of -500, and m / (n + m) is 0.05-50.

The copolymer includes a random copolymer in which diphenylfluorene groups into which sulfonic acid groups are introduced are evenly distributed in the polymer chain, or a block copolymer in which diphenylfluorene groups into which sulfonic acid groups are introduced are separated into blocks.

The intrinsic viscosity of the copolymer is preferably in the range of 0.1 to 3.0 dl / g on NMP (N-methyl-a-pyrrolidinone) at 25 ° C., more preferably in the range of 0.8 to 3.0 dl / g. When the intrinsic viscosity of the copolymer is less than 0.1dl / g, it is difficult to apply it to a polymer electrolyte membrane due to a problem of dissolving in a fuel cell working solvent such as water or methanol, a problem of fine cracking due to a decrease in physical strength of the prepared membrane, and the like. If it exceeds 3.0 dl / g, solution preparation and dispersion, solvent separation from the electrolyte membrane, etc. are not smooth, so that a non-uniform and porous membrane is formed, which is not preferable.

Method for producing a hydrogen ion conductive copolymer of the present invention,

A) A copolymer in which an ether or thioether linking group is present in the main chain by copolymerizing an aromatic halogen monomer (compound 2), a monomer having a diphenylfluorene group (compound 3), and a monomer having a ether or thioether group (compound 4) ( First step to obtain compound 5);

B) a second step of obtaining a copolymer (compound 6) containing a diphenyl fluorene group and having a sulfone and ether linkage by oxidizing the thioether linking group in the copolymer to a sulfone linker; And

C) a copolymer having a sulfonate and an ether linkage group (Compound 6) reacted with a sulfonating agent to introduce a sulfonic acid group, including a diphenylfluorene group having a sulfonic acid group introduced therein and having a phenylsulfone and a phenylether group (Compound 1) Obtaining a third step;

It includes, characterized in that carried out by the following Scheme 1:

[Reaction Scheme 1]

In the above scheme, X is -F, -Cl or -NO ₂ , J ₁ is -OH or -SH, J ₂ is -O- or -S-, K ₁ , K ₂ is -O- or- S-, L ₁ , and L ₂ are ether groups (-O-) or sulfone groups (-SO _2- ), at least one is a sulfone group, m and n are integers from 2 to 500, and m / (n + m) is 0.05-50, A is -H or -SO ₃ H.

At this time, the first step is again a small step,

A-1) Synthesizing oligomer 1 by polymerizing an aromatic halogen monomer (compound 2) and a monomer having a diphenylfluorene group (compound 3), and separately a monomer having an aromatic halogen monomer (compound 2) and an ether or thioether group. 1-1 substep of polymerizing (Compound 4) to synthesize oligomer 2; And

A-2) 1-2 sub-polymerization of the oligomer 1 and oligomer 2 to obtain a copolymer (compound 5) in which the ether or thioether linking group is present in the main chain;

It may be configured to include.

In Scheme 1, the monomer having a ether or thioether group (Compound 4) is oxybis (4-benzenethiol), thiobis (4-phenol) (thiobis (4-phenol)), It may be thiobis (4-benzenethiol) or a mixture of these in various ratios.

From Scheme 1, the proportion of the diphenylfluorene group of the final hydrogen ion conductive copolymer and the polymer electrolyte membrane prepared using the same varies depending on the hybrid ratio of the reaction monomers. The value of m / (n + m) is preferably in the range of 0.05 to 0.50, and the mixing ratio of the monomer can be appropriately adjusted according to the user's desired value. The sulfonic acid group may be selectively introduced into the diphenyl fluorene group during the third step of the phonation reaction described later, and introduced into one diphenyl fluorene group according to the type of sulfonating agent, the concentration of the sulfonating agent in the reaction solution, and the concentration of the copolymer. The number of sulfonic acid groups to be can be adjusted. When two sulfonic acid groups are introduced, A in Scheme 1 is -H, and when four sulfonic acid groups are introduced, A in Scheme 1 is -SO ₃ H.

In the preparation method, the first step copolymerizes an aromatic halogen monomer (compound 2), a monomer having a diphenylfluorene group (compound 3) and a monomer having a ether or thioether group (compound 4) in an appropriate ratio to form a random copolymer. An oligomer prepared or synthesized using an aromatic halogen monomer (compound 2) and a monomer (compound 3) having a diphenylfluorene group; A block copolymer is prepared by copolymerizing an oligomer synthesized using an aromatic halogen monomer (compound 2) and a monomer (compound 4) having an ether or thioether group.

The aromatic halogen monomer (compound 1) contains an electron attracting sulfone group capable of activating leaving group X. In the case of an alcohol or thiol monomer (compound 4), an electron that can increase the reactivity of the alcohol group or thiol group It is characterized by having an excellent polymerization degree, that is, having a high molecular weight, by including each of a main pulleyrene group, a thioether linking group, and an ether linking group. According to these characteristics, the copolymer prepared in the first step may produce a hydrogen ion conductive copolymer having excellent mechanical stability after the second and third steps. In this case, the copolymer may use oxybis (4-benzenethiol), thiobis (4-phenol), thiobis (4-benzenethiol) as monomers having an ether or thioether group (compound 4), or various ratios thereof. By using as a mixture, it is possible to freely adjust the content of the ether group of the flexible characteristics and the sulfone group of the robust characteristics.

In addition, the copolymer by controlling the molar ratio of the monomer (compound 3) having a diphenyl fluorene group and the monomer (compound 4) having an ether or thioether group, by controlling the content of the diphenyl fluorene group and the ether and theoether linking group, The ion conductivity and mechanical properties of the final polymer electrolyte membrane can be appropriately adjusted according to the application purpose. As a preferred example, oxybis (4-benzenethiol), thiobis (4-phenol), 4,4 '-(9H-fluorene-9,9-diyl) di per 1 equivalent of thiobis (4-benzenethiol) The equivalent ratio of phenol (4,4 '-(9H-fluorene-9,9-diyl) diphenol) may be performed at 1: 5: 1, but is not limited thereto.

In this case, the copolymer may be a random copolymer in which a monomer (compound 3) having a diphenylfluorene group and a monomer (compound 4) having an ether or a thioether group are simultaneously added and polymerized with a halogen monomer. Alternatively, the copolymer may be an oligomer having an appropriate molecular weight obtained by polymerizing a monomer (compound 3) having a diphenylfluorene group and a halogen monomer (compound 2); It may be a block copolymer obtained by reacting a monomer (compound 4) having an ether or a thioether group with an oligomer having an appropriate molecular weight obtained by polymerizing a halogen monomer (compound 2).

The second step is a step of obtaining a copolymer containing a diphenyl fluorene group having a sulfone and ether linkage by converting the thioether linking group in the copolymer prepared in the first step into a sulfone linker through oxidation reaction. to be. In the second step, by adjusting the amount of the oxidizing agent added according to the content of the thioether linking group in the copolymer prepared in the first step, and reacting for at least 1 minute at a reaction temperature of 0 to 30, all of the thioether linking group Oxidize.

About one equivalent of a thioether linking group present in the copolymer in the preferred example, equivalent ratio of m- chloroperoxybenzoic acid (m -chloroperoxybenzoic acid. M -CPBA), but this can be carried out in a 2.2 equivalent, and the like.

In the structure of the copolymer prepared in the second step, a continuous phenylsulfone structure having very low solubility in various solvents including alcohol and water may be formed, thereby improving mechanical stability and dimensional stability of the final polymer electrolyte membrane. In addition, the thioether linking group having the electron donor property is changed to the sulfone linking group having the electron withdrawing property through the oxidation reaction, so that the sulfonic acid group may be introduced into the structure of the copolymer prepared in the second step at the following phonation reaction conditions of the third step. The portion which can be limited is diphenylfluorene group.

The third step is to introduce a sulfonic acid group using a sulfonating agent such as fuming sulfuric acid, concentrated sulfuric acid, chlorosulfonic acid, etc., comprising a diphenylfluorene group into which the sulfonic acid group is introduced, and a sulfone and an ether. Copolymers having a linking group can be prepared.

In the third step, the sulfonating agent is added according to the content of the diphenyl fluorene group in the copolymer prepared in the second step, and the sulfonic acid group is introduced into the diphenyl fluorene group by reacting for 30 minutes or more at room temperature. do.

As a preferred example, the chlorosulfonic acid group may be used in a ratio of 20 equivalents to 1 equivalent of the diphenylfluorene group in the copolymer prepared in the second step, but is not limited thereto.

Through the above production method, the hydrogen ion conductive copolymer including a diphenyl fluorene group in which the sulfonic acid group prepared is introduced may contain a sulfonic acid group as an ion exchange group, and thus may be used as a polymer electrolyte membrane.

The hydrogen ion conductive polymer electrolyte membrane of the present invention is prepared by dissolving the hydrogen ion conductive copolymer prepared in an organic solvent to obtain a solution, then casting the solution on a glass or teflon plate and drying.

In this case, the organic solvent may be any one selected from N-methyl-a-pyrrolidinone (NMP) or N, N-dimethylacetamide (DMAc) or a mixed solvent thereof.

The hydrogen-ion conductive polymer electrolyte membrane prepared by the above method has a high ionic conductivity and excellent mechanical properties due to the phenyl sulfone structure having a very high swelling effect on a sulfonic acid group having high hydrogen ion conductivity characteristics and a solvent such as water and alcohol, and an ether group having excellent flexibility. Dimensional stability can be combined at the same time.

At this time, the thickness of the final polymer electrolyte membrane is preferably 30 ~ 150㎛, if the thickness is less than 30㎛, the permeation of fuel and reaction gas through the membrane to reduce the efficiency of the fuel cell, if exceeding 150㎛, hydrogen ions The propagation path of is excessively increased and the resistance of the unit cell is increased.

As a result of measuring the ionic conductivity of the Nafion membrane compatible with the polymer electrolyte membrane of the present invention at an operating temperature of 25 ° C. and 100% humidification condition, the polymer electrolyte membrane of the present invention exhibited the same or superior results as that of the Nafion membrane. The polymer electrolyte membrane provided by may replace the existing commercially available Nafion electrolyte membrane (Dupont).

In addition, the final polymer electrolyte membrane provided by the present invention has an ion conductivity of 0.05 S / cm or more as measured at 80 degrees.

While maintaining the polymer electrolyte membrane of the present invention on deionized water at 100 ° C., the mass change was measured every 24 hours. As a result, there was no mass loss up to 10 days or more. It is possible to provide a polymer electrolyte membrane fuel cell capable of stable long-term operation even in the high temperature and strong acidic environment.

Furthermore, due to the phenyl sulfone group in the conductive copolymer in which the sulfonic acid group is introduced, the mechanical and chemical stability of the final polymer electrolyte membrane is greatly improved, and thus the membrane-electrode assembly is not only easily manufactured, but also the performance and efficiency are deteriorated even during long-term operation. Implement a polymer electrolyte membrane fuel cell with excellent characteristics.

Accordingly, the present invention provides a membrane-electrode assembly composed of a polymer electrolyte membrane or a polymer electrolyte membrane prepared using a hydrogen ion conductive copolymer including a diphenylfluorene group having sulfonic acid group introduced therein, and a polymer electrolyte employing the membrane-electrode assembly. It provides a membrane fuel cell.

Hereinafter, the present invention will be described in more detail with reference to Examples. This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

Example 1-1 . Preparation of SBP-SHPF Random Copolymer (r-SBP-SHPF-75 / 25)

First step; Copolymerization Process: 100mmol, 4,4- (9H-fluorene-9.9-diyl) diphenol (4,4 '-(4,4'-difluorodiphenylsulfone, DFDPS) 9H-fluorene-9,9-diyl) diphenol, HPF) 25mmol, thiobis ((4-phenol (thiobis (4-phenol), TBP) 75mmol, K ₂ CO ₃ 120mmol) Dean-Stark device The solution was added to a stirred tank and dissolved in DMAc, which is four times the total monomer mass, and toluene, which is 2.5 times, dissolved in. The solution was heated to 150 ° C. over 2 hours and then slowly heated to 160 ° C. The mixture was slowly warmed up to 175 ° C., and after 12 hours, the polymerization solution was poured into water to precipitate The precipitated polymer was washed with water and isopropyl alcohol and dried.

Second step; Copolymer oxidation by: dissolving the copolymer prepared in 5g in dichloromethane (dichloromethane) was added m- chloroperoxybenzoic acid (m -chloroperoxybenzoic acid, m -CPBA) of 4.4g 12 sigan oxidation reaction at 0 ℃ After the reaction solution was poured into isopropyl alcohol to precipitate. The precipitated polymer was washed with isopropyl alcohol and dried.

The third step; Copolymer sulfonation reaction method: Concentrated sulfuric acid 100mL was added to 5 g of the copolymer prepared above, followed by sulfonation at room temperature for 24 hours, and the reaction solution was poured into iced water to precipitate. The precipitated polymer was washed with isopropyl alcohol and water and dried.

Example 1-2 . Preparation of OBS-SHPF Random Copolymer (r-OBS-SHPF-75 / 25)

First step; Copolymerization Process: The same procedure as in Example 1-1 except that 75 mmol of oxybis (4-thiophenol, OBT) was used instead of 75 mmol of TBP in the first step of Example 1-1. Polymerization was carried out.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-1 except that 8.5 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: It proceeded similarly to Example 1-1.

Example 1-3 . Preparation of SBBS-SHPF Random Copolymer (r-SBBS-SHPF-75 / 25)

First step; Copolymerization Process: The same process as in Example 1-1 except that 75 mmol of thiobis (4-benzenethiol), TBBT was used instead of 75 mmol of TBP in the first step of Example 1-1. Polymerization was carried out.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-1 except that 12.5 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: It proceeded similarly to Example 1-1.

Example 1-4 . Preparation of SBP-SBBS-SHPF Random Copolymer (r-SBP-SBBS-SHPF-65 / 10/25)

First step; Copolymerization Process: DFDPS 100mmol, HPF 25mmol, TBP 65mmol, TBBT 10mmol, K ₂ CO ₃ 120mmol in a Dean-Stark device, DMAc equivalent to 4 times the total monomer mass And toluene equivalent to 2.5 times was dissolved. The solution was heated to 150 ° C. over 2 hours, and then slowly heated to 160 ° C. to remove all of toluene. The temperature was slowly raised to 175 ° C and after 12 hours, the polymerization solution was poured into water to precipitate. The precipitated polymer was washed with water and isopropyl alcohol and dried.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-1 except that 5.5 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: It proceeded similarly to Example 1-1.

Example 1-5 . Preparation of SBP-OBS-SHPF Random Copolymer (r-SBP-OBS-SHPF-65 / 10/25)

First step; Copolymerization Process: The polymerization was carried out in the same manner as in Example 4 except that 10 mmol of OBT was used instead of 10 mmol of TBBP in Example 1-4.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-1 except that 4.9 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: It proceeded similarly to Example 1-1.

Example 1-6 . Preparation of SBBS-OBS-SHPF Random Copolymer (r-SBBS-OBS-SHPF-10 / 65/25)

First step; Copolymerization Process: Polymerization was carried out in the same manner as in Example 1-4 except that OBT 65mmol and TBBT 10mmol were used instead of TBP 65mmol and TBBP 10mmol in Example 1-4.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-1, except that 9.1 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: It proceeded similarly to Example 1-1.

Example 1-7 . Preparation of SBP-SBBS-OBS-SHPF Random Copolymer (r-SBP-SBBS-OBS-SHPF-55 / 10/10/25)

First step; Copolymerization Process: 100mmol of DFDPS, 25mmol of HPF, 55mmol of TBP, 10mmol of TBBT, 10mmol of OBT, 120mmol of K ₂ CO ₃ is placed in a Dean-Stark unit and is stirred at 4 times of the total monomer mass. It was dissolved by adding DMAc and 2.5 times of toluene. The solution was heated to 150 ° C. over 2 hours, and then slowly heated to 160 ° C. to remove all of toluene. The temperature was slowly raised to 175 ° C and after 12 hours, the polymerization solution was poured into water to precipitate. The precipitated polymer was washed with water and isopropyl alcohol and dried.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-1 except that 6.1 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: It proceeded similarly to Example 1-1.

Example 1-8 . Preparation of SBP-SHPF Block Copolymer (b-SBP-SHPF-75 / 25)

1-1 sub-step; Preparation method of oligomer 1: DFDPS 25mmol, HPF 26mmol, K ₂ CO ₃ 31.2mmol in Dean-Stark apparatus and 2.5 times with DMAc equivalent to 4 times the total monomer mass Toluene was added and dissolved. The solution was heated to 150 ° C. over 2 hours, and then slowly heated to 160 ° C. to remove all of toluene. The temperature was slowly raised to 175 ° C and after 12 hours, the polymerization solution was poured into water to precipitate. The precipitated oligomer was washed with water and isopropyl alcohol and dried.

Preparation method of oligomer 2: DFDPS 75mmol, TBP 76mmol, K ₂ CO ₃ 91.2mmol in Dean-Stark apparatus, 2.5 times with DMAc equivalent to 4 times the total monomer mass Toluene was added and dissolved. The solution was heated to 150 ° C. over 2 hours, and then slowly heated to 160 ° C. to remove all of toluene. The temperature was slowly raised to 175 ° C and after 12 hours, the polymerization solution was poured into water to precipitate. The precipitated polymer was washed with water and isopropyl alcohol and dried.

Step 1-2; Method for producing block copolymer: Using oligomer 1 and oligomer 2 prepared above, 1 mmol each and 2.4 mmol of K ₂ CO ₃ , which is a Dean-Stark device and placed in a stirred tank. Four times the total oligomer mass was dissolved in DMAc and 2.5 times toluene. The solution was heated to 150 ° C. over 2 hours, and then slowly heated to 160 ° C. to remove all of toluene. After slowly lowering the temperature to 80 ° C., 2 mmol of decaflourobiphenyl (DFBP) was added thereto, and the reaction was performed at 90 ° C. After 48 hours, the polymerization solution was poured into water to precipitate, and the precipitated polymer was washed with water and isopropyl alcohol and dried.

Second step; Copolymer Oxidation Method: 5 g of the block copolymer prepared above was dissolved in dichloromethane, 4.4 g of m- chloroperoxybenzoic acid ( m- CPBA) was added, followed by oxidation reaction at 0 ° C. for 12 hours. Pour into propyl alcohol to precipitate. The precipitated polymer was washed with isopropyl alcohol and dried.

The third step; Copolymer sulfonation reaction method: Concentrated sulfuric acid 100mL was added to 5 g of the copolymer prepared above, followed by sulfonation at room temperature for 24 hours, and the reaction solution was poured into iced water to precipitate. The precipitated polymer was washed with isopropyl alcohol and water and dried.

Example 1-9 . Preparation of OBS-SHPF Block Copolymer (b-OBS-SHPF-75 / 25)

1-1 sub-step; Polymerization process of oligomer 1: It proceeded in the same manner as in Example 1-8.

Polymerization process of oligomer 2: It proceeded in the same manner as in Example 1-8 except that OBT 76mmol was used instead of TBP 76mmol of Example 1-8.

1-2 small step; Manufacturing method of block copolymer: It proceeded similarly to Example 1-8.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-8 except that 8.5 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: the same procedure as in Example 1-8.

Example 1-10 . Preparation of SBBS-SHPF Block Copolymer (b-SBBS-SHPF-75 / 25)

1-1 sub-step; Preparation method of oligomer 1: It proceeded in the same manner as in Example 1-8.

Preparation method of oligomer 2: It proceeded in the same manner as in Example 1-8 except that TBBT 76mmol was used instead of TBP 76mmol of Example 1-8.

1-2 small step; Manufacturing method of block copolymer: It proceeded similarly to Example 1-8.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-8 except that 12.5 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: the same procedure as in Example 1-8.

Example 1-11 . Preparation of SBP-SBBS-SHPF Block Copolymer (b-SBS-SBBS-SHPF-65 / 10/25)

1-1 sub-step; Preparation method of oligomer 1: It proceeded in the same manner as in Example 1-8.

Preparation method of oligomer 2: The procedure was the same as in Example 1-8 except that TBP 65.87 mmol and TBBT 10.13 mmol were used instead of TBP 76 mmol of Example 1-8.

Step 1-2; Manufacturing method of block copolymer: It proceeded similarly to Example 1-8.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-8 except that 5.5 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: the same procedure as in Example 1-8.

Example 1-12 . Preparation of SBP-OBS-SHPF Block Copolymer (b-SBS-OBS-SHPF-65 / 10/25)

1-1 sub-step; Preparation method of oligomer 1: It proceeded in the same manner as in Example 1-8.

Preparation method of oligomer 2: The same procedure as in Example 1-11 was carried out in Example 1-11 except that 10.13 mmol of OBT was used instead of 10.13 mmol of TBBT.

1-2 small step; Manufacturing method of block copolymer: It proceeded similarly to Example 1-8.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-8 except that 4.93 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: the same procedure as in Example 1-8.

Example 1-13 . Preparation of SBBS-OBS-SHPF Block Copolymer (b-SBBS-OBS-SHPF-10 / 65/25)

1-1 sub-step; Preparation method of oligomer 1: It proceeded in the same manner as in Example 1-8.

Preparation method of oligomer 2: The procedure was the same as in Example 1-11 except that 65.87 mmol of OBT was used instead of 65.87 mmol of TBP in Example 1-11.

1-2 small step; Manufacturing method of block copolymer: It proceeded similarly to Example 1-8.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-8 except that 9.1 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: the same procedure as in Example 1-8.

Example 1-14 . Preparation of SBP-SBBS-OBS-SHPF Block Copolymer

1-1 sub-step; Preparation method of oligomer 1: It proceeded in the same manner as in Example 1-8.

Preparation method of oligomer 2: The same procedure as in Example 1-8 was performed except that TBP 55.73 mmol, TBBT 10.13 mmol, and OBT 10.13 mmol were used in place of TBP 76 mmol in Example 1-8.

1-2 small step; Manufacturing method of block copolymer: It proceeded similarly to Example 1-8.

Second step; Copolymer oxidation reaction method: The procedure was the same as in Example 1-8 except that 6.1 g of m- CPBA was used.

The third step; Copolymer sulfonation reaction method: the same procedure as in Example 1-8.

Comparative Example 1 . Preparation of sulfonated polyarylene sulfide sulfone-40 copolymer

TBBT 15mmol, K ₂ CO ₃ 17.5mmol was added to the Dean-Stark apparatus and stirred in a stirred tank, 40mL of NMP and 20mL of toluene were dissolved. The solution was heated to 150 ° C. over 2 hours, and then slowly heated to 160 ° C. to remove all of toluene. 6 mmol of DFDPS and 9 mmol of bisfluoro4-sulfophenyl sulfone disodium salt (SDFDPS) were added to the solution, and the temperature was slowly raised to 190 ° C. Poured into and precipitated. The precipitated polymer was washed with water and isopropyl alcohol and dried.

Comparative Example 2 . Preparation of sulfonated polyarylene sulfide sulfone-50 copolymer

DFDPS 6mmol, SDFDPS 9mmol Instead of using DFDPS 7.5mmol, SDFDPS 7.5mmol was carried out in the same process as in Comparative Example 1.

Example 2 . Preparation of Random and Block Copolymer Electrolyte Membranes

The copolymers prepared in Examples 1-1 to 1-14 and Comparative Examples 1 to 2 were prepared as polymer electrolyte membranes as follows. 0.80 g of the copolymer was dissolved in 8 ml NMP, and then filtered through a 0.45 µm pore Teflon filter to prepare a 10-weight / vol% (w / v-%) membrane solution for preparing a membrane. The prepared solution is poured into a clean glass or Teflon plate without surface scratches, dried slowly over 12 hours using a halogen lamp in an inert gas atmosphere at 60 ° C, and then dried in a reduced pressure dryer at 120 ° C for at least 12 hours. By completely removing the solvent used in the preparation, a polymer electrolyte membrane having an average film thickness of 50 μm was prepared.

Example 3 . Preparation of Polymer Electrolyte Membrane-electrode Assembly

A membrane-electrode assembly for a polymer electrolyte membrane fuel cell was prepared using the polymer electrolyte membrane prepared in Example 2. In the preparation of the membrane-electrode assembly, platinum-carbon (Pt / C, Pt 40%) catalyst was used as the anode and cathode catalyst, and the gas diffusion layer supporting the catalyst layer was carbon paper (Toray, TGPH) treated with Teflon. -060, 20% PTFE by mass) was used. After preparing the catalyst ink uniformly dispersed from the catalyst and the solution for producing the polymer electrolyte membrane, and then evenly sprayed on carbon paper to form a catalyst layer of the anode and the cathode and pressed at high temperature, to prepare a membrane-electrode assembly of the present invention It was.

<Evaluation>

1.Ion Conductivity Measurement

The thickness of the electrolyte membrane prepared by the method of Example 2 using the copolymers synthesized in Examples 1 to 1 to 14 and 1 to 2 was compared to that of the commercially available Nafion-112 film thickness 50. It was prepared by adjusting within ± 5%, and the ion conductivity was measured under the condition of 25% relative humidity 100%.

Ion conductivity was measured using a Solartron analyzer (Solatron 1260 Impedance / Gain-Phase analyzer) and the impedance spectrum was recorded to 10MHz ~ 0Hz, the ion conductivity was calculated by the following equation (1).

[Equation 1]

Ion conductivity (S / cm); δ = 1 / R × L / A

(In the above, R is the measurement resistance (ohm), L is the length (cm) between the measurement electrodes, A is the cross-sectional area (cm ² ) of the prepared electrolyte membrane.)

In the sulfonated polymer electrolyte membrane of the present invention, the ion conductivity of the b-SBP-SHPF-75 / 25 polymer electrolyte membrane was measured. As a result, it was 1.1 × 10 ⁻¹ S / cm at an operating temperature of 25 ° C. and a relative humidity of 100%. Ionic conductivity is shown.

2. Measurement of dimensional change in hygroscopic state

Using the copolymer synthesized in Examples 1-1 to 1-14, the electrolyte membrane prepared by the method of Example 2 was immersed in distilled water for 3 hours or more at room temperature, then taken out to remove water on the surface, and the thickness of the film Volume was measured from transverse and longitudinal lengths (Vw). Thereafter, the film was placed in a vacuum oven at 80 ° C. and dried for at least 24 hours to completely remove moisture in the film, and then the volume was measured again (Vd) to calculate the dimensional change according to Equation 2 below.

&Quot; (2) &quot;

Dimensional variation (vol%); DV = (Vw-Vd) / Vd x 100

In the sulfonated polymer electrolyte membrane of the present invention, the dimensional change of the b-SBP-SHPF-75 / 25 polymer electrolyte membrane was measured, and the dimensional change of 120 vol% was shown.

3. Intrinsic viscosity measurement

After dissolving the copolymers synthesized in Examples 1-1 to 1-14 and Comparative Examples 1 to 2 at a concentration of 0.05 g / dL in NMP, the prepared solution was prepared at 25 ° C. using a Canon-Uberod viscometer. Measured.

4. Unit Battery Performance Evaluation

For the membrane-electrode assembly prepared in Example 3, a unit cell performance test was performed under operating conditions of an operating temperature of 80 ° C., and the sulfonated polymer electrolyte membrane of the present invention was used at 0.6V. Comparing with the performance of the commercial Nafion (Nafion-112) (about 1000mA) it was confirmed that the equivalent or superior performance. Table 1 shows the current density results at 0.6 V when the unit cell performance was evaluated.

The evaluation results are summarized in Table 1 below.

division Copolymer inherence
Viscosity
(dL / g) size
Gradient
(%) ion
conductivity
(S / cm) Unit cell
Performance
(mA) Example 1-1
Examples 1-2
Example 1-3
Example 1-4
Example 1-5
Example 1-6
Example 1-7
Examples 1-8
Example 1-9
Example 1-10
Example 1-11
Example 1-12
Example 1-13
Example 1-14
Comparative Example 1
Comparative Example 2 r-SBP-SHPF-75 / 25
r-OBS-SHPF-75 / 25
r-SBBS-SHPF-75 / 25
r-SBP-SBBS-SHPF-65 / 10/25
r-SBP-OBS-SHPF-65 / 10/25
r-SBBS-OBS-SHPF-10 / 65/25
r-SBP-SBBS-OBS-SHPF-55 / 10/10/25
b-SBP-SHPF-75 / 25
b-OBS-SHPF-75 / 25
b-SBBS-SHPF-75 / 25
b-SBS-SBBS-SHPF-65 / 10/25
b-SBS-OBS-SHPF-65 / 10/25
b-SBBS-OBS-SHPF-10 / 65/25
b-SBP-SBBS-OBS-SHPF-55 / 10/10/25
Sulfonated polyarylene sulfide sulfone-40
Sulfonated polyarylene sulfide sulfone-50 2.51
1.73
1.67
2.12
2.05
1.31
1.37
1.52
1.36
1.38
1.42
1.46
1.08
1.02
0.8
1.0 120
92
58
101
105
76
96
88
79
53
84
85
67
87
200
500 0.10
0.07
0.05
0.08
0.09
0.06
0.06
0.12
0.07
0.06
0.08
0.08
0.05
0.06
0.10
0.12 1050
910
790
950
1000
820
810
1100
920
850
950
970
780
830
950
-

The copolymers prepared in Examples 1-1 to 1-14 were prepared in Comparative Examples 1 to 2 and prepared in comparison with the copolymers using sulfonated monomers as described below. It can be seen that it has an excellent degree of polymerization.

In addition, it can be seen that the copolymers prepared in Examples 1-1 to 1-14 have excellent dimensional stability as compared to the copolymers having sulfide groups prepared in Comparative Examples 1 to 2 as including the rigid phenyl sulfone groups.

In addition, the copolymers prepared in Examples 1-8 to 1-14 have better dimensional stability and ionic conductivity than the random copolymers prepared in Examples 1-1 to 1-7 as they have the form of block copolymers. It can be seen that.

As described above,

First, the present invention includes a diphenyl fluorene group in which a sulfonic acid group is introduced into the copolymer, and the ether group and the sulfone group can be adjusted at an appropriate ratio, thereby having high hydrogen ion conductivity and excellent mechanical properties and dimensional stability. A hydrogen ion conductive copolymer was provided.

 Second, the present invention is suitable for mass production by performing a polymerization reaction using a monomer having excellent reactivity in the preparation of the copolymer, an oxidation reaction for effectively controlling the degree of sulfonation, and selective phonation reaction described later. Provided a new copolymer production method that can easily obtain the degree of polymerization and can be precisely controlled sulfonation degree.

Third, the present invention provides a membrane-electrode assembly that can implement a performance and efficiency equivalent to or better than that of a commercial Nafion 112 membrane in terms of unit cell performance evaluation using a sulfonated polymer electrolyte membrane.

Fourth, the present invention provides a polymer electrolyte membrane fuel cell having improved performance and durability of a fuel cell by employing a membrane-electrode assembly composed of a polymer electrolyte membrane having improved physical properties.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims. .

Claims (10)

A hydrogen ion conductive copolymer containing a diphenylfluorene group having a sulfonic acid group introduced therein and represented by Chemical Formula 1 below:
[Chemical Formula 1]

Wherein A is -H or -SO ₃ H, L ₁ , and L ₂ are ether group (-O-) or sulfone group (-SO _2- ) with at least one sulfone group, m and n are 2 It is an integer of -500, and m / (n + m) is 0.05-50. The method of claim 1, wherein the copolymer is a random copolymer in which the diphenyl fluorene group into which the sulfonic acid group is introduced is evenly distributed in the polymer chain, or a block copolymer in which the diphenyl fluorene group into which the sulfonic acid group is introduced is separated in a block form. The hydrogen ion conductive copolymer, characterized in that. The hydrogen ion conductive copolymer of claim 1, wherein the intrinsic viscosity of the copolymer is 0.1-3.0 dl / g on N-methyl-a-pyrrolidinone (NMP) of 25. A) A copolymer in which an ether or thioether linking group is present in the main chain by copolymerizing an aromatic halogen monomer (compound 2), a monomer having a diphenylfluorene group (compound 3), and a monomer having a ether or thioether group (compound 4) ( First step to obtain compound 5);
B) a second step of obtaining a copolymer (compound 6) containing a diphenyl fluorene group and having a sulfone and ether linkage by oxidizing the thioether linking group in the copolymer (compound 5) to a sulfone linker; And
C) a copolymer having a sulfonate and an ether linkage group (Compound 6) introduced with a sulfonate group by reacting with a sulfonating agent, including a diphenylfluorene group having a sulfonate group introduced therein, and having a phenylsulphone and a phenylether group (Compound 1) Obtaining a third step;
To include, the method of producing a hydrogen ion conductive copolymer carried out by the following Scheme 1:
[Reaction Scheme 1]

In the above scheme, X is -F, -Cl or -NO ₂ , J ₁ is -OH or -SH, J ₂ is -O- or -S-, K ₁ and K ₂ is -O- or- S-, L ₁ , and L ₂ are ether groups (-O-) or sulfone groups (-SO _2- ), at least one is a sulfone group, m and n are integers from 2 to 500, and m / (n + m) is 0.05 ~ 50, and a is -H or -SO ₃ H,. The method of claim 4, wherein the first step is
A-1) Synthesizing oligomer 1 by polymerizing an aromatic halogen monomer (compound 2) and a monomer having a diphenylfluorene group (compound 3), and separately a monomer having an aromatic halogen monomer (compound 2) and an ether or thioether group. Sub 1-1 to polymerize (Compound 4) to synthesize oligomer 2; And
A-2) first and second substeps of copolymerizing the oligomer 1 and oligomer 2 again to obtain a copolymer (compound 5) in which an ether or thioether linking group is present in the main chain;
Method for producing the hydrogen ion conductive copolymer, characterized in that it comprises a. A hydrogen ion conductive polymer electrolyte membrane prepared by dissolving the hydrogen ion conductive copolymer of claim 1 in an organic solvent and then casting on a glass or teflon plate. The hydrogen ion conductive polymer electrolyte membrane according to claim 6, wherein the polymer electrolyte membrane has a thickness of 30 to 50 µm. 7. The hydrogen ion conductive polymer electrolyte membrane of Claim 6, wherein the polymer electrolyte membrane has an ion conductivity of 0.05 S / cm or more at 80. A membrane-electrode assembly for an electrolyte membrane fuel cell comprising the hydrogen ion conductive polymer electrolyte membrane of claim 6. A polymer electrolyte membrane fuel cell, wherein the membrane-electrode assembly of claim 9 is employed.