KR20100085388A - Polyphenylehter based copolymer, method for preparing the copolymer, polymer electrolyte membrane comprising the copolymer, and fuel cell comprising the membrane - Google Patents

Abstract

PURPOSE: A method for manufacturing a polyphenylether-based copolymer is provided to obtain a polymer electrolyte membrane having improved properties including hydrogen ion conductivity, methanol transmittance, and the percentage of water content. CONSTITUTION: A polyphenylether-based copolymer includes a repeating unit which is marked as a chemical formula 1a and a repeating unit which is marked as a chemical formula 1b. In the chemical formulas, M1, M2, and M3 are hydrogen, lithium, sodium, or potassium. In the chemical formulas, Ar1 and Ar2 are an arylene group with a carbon number of 1-20, an alkyl group with a carbon number of 1-20, an aryl group with a carbon number of 6-20, or a hetereoaryl group with a carbon number of 2-20.

Description

Polyphenylether copolymer, method for preparing the same, polymer electrolyte membrane comprising same, and fuel cell employing same {Polyphenylehter based copolymer, method for preparing the copolymer, polymer electrolyte membrane comprising the copolymer, and fuel cell comprising the membrane}

The present invention relates to a polyphenyl ether copolymer, a method for preparing the same, a polymer electrolyte membrane including the same, and a fuel cell employing the same. More specifically, a polyphenyl ether copolymer having a new structure, a method for preparing the same, It relates to a polymer electrolyte membrane comprising, and a fuel cell comprising the same.

The fuel cells are polymer electrolyte membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxides depending on the type of electrolyte. It is classified into a solid oxide fuel cell (SOFC), and the operating temperature of the fuel cell and the material of components vary according to the type of electrolyte used. Polymer Electrolyte Membrane Fuel Cell (PEMFC) has better output, lower operating temperature and faster response than other fuel cells.

Fuel cells are classified into a direct fuel supply type or internal reforming type according to a method of supplying fuel to the anode, and a direct methanol fuel cell (DMFC) is a typical direct fuel supply type. Direct methanol fuel cell belongs to polymer electrolyte fuel cell because it uses polymer electrolyte membrane as electrolyte. Direct methanol fuel cells do not use hydrogen reformers because they use methanol as fuel, and operate at low temperatures, making the system simple and compact, making them suitable for powering small and portable devices.

The fuel cell is composed of a power generation unit for generating electricity, a reformer, a fuel tank and a fuel pump. The power generation unit forms a main body of the fuel cell, and the fuel pump supplies the fuel in the fuel tank to the reformer. Hydrogen gas is generated through the reformer and fuel is supplied to the power generation unit by a pump to generate electrical energy by an electrochemical reaction. The power generation unit may be composed of a membrane electrode assembly (MEA) consisting of an anode, a cathode, and a polymer electrolyte membrane.

As the electrolyte membrane of the polymer electrolyte fuel cell, a functional hydrogen ion exchange membrane having a cation exchange capacity is used. Commercially, hydrophobic exchange membranes containing sulfonic acid groups are mainly used. This is because sulfonic acid groups have very high acidity and C-S bonds are stable even under oxidizing conditions. In the hydrogen ion exchange membrane where sulfonic acid group is present, water molecules must be present together to maintain high hydrogen ion conductivity. In the presence of water molecules, sulfonic acid groups present in the electrolyte membrane are dissociated into sulfonate anions and hydrogen ions. As in the sulfuric acid solution electrolyte, the hydrogen ions move by the hydrogen ion concentration gradient or the electric field. Hydrogen ion conductivity is affected by the number of sulfonic acid groups included in the polymer electrolyte membrane, the structure of the polymer electrolyte membrane, the amount of water contained in the polymer electrolyte membrane, and the like.

An electrolyte membrane of a typical polymer electrolyte fuel cell is a fluorine-based polymer electrolyte membrane such as a Nafion membrane, an Aciplex membrane, a Flemion membrane, or a Dow membrane. The fluorine-based polymer electrolyte membranes have a low hydrogen ion conductivity at a high temperature of 100 ° C. or higher, high permeability of fuel gas, and high price. In addition, the fluorine-based polymer electrolyte membrane has a high hydrogen ion conductivity, but also has a high permeability of fuel (eg, methanol) in the polymer electrolyte membrane. Therefore, it is difficult to secure high ion conductivity and low fuel permeability simultaneously required in the fuel cell.

Therefore, there is still a need for a polymer electrolyte membrane having low production cost and high hydrogen ion conductivity and low permeability to fuel.

One aspect of the present invention is to provide a polyphenylether copolymer having a novel structure.

Another aspect of the present invention is to provide a method for preparing the polyphenylether copolymer.

Another aspect of the present invention to provide a polymer electrolyte membrane comprising the copolymer.

Yet another aspect of the present invention is to provide a fuel cell including the polymer electrolyte membrane.

According to an aspect of the present invention, there is provided a polyphenylether copolymer comprising a repeating unit represented by the following Formula 1a and a repeating unit represented by the following Formula 1b:

<Formula 1a> <Formula 1b>

In the above equations,

M ₁ , M ₂ and M ₃ are independently of each other hydrogen, lithium, sodium, or potassium;

Ar ₁ and Ar ₂ are each independently an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms;

R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms;

X is a halogen atom;

m and n are mole fractions, m + n = 1, and 0 <m <1, 0 <n <1.

According to another aspect of the present invention, a method for producing a polyphenyl ether copolymer represented by the following formula (1),

Preparing a compound represented by Chemical Formula 6 by reacting the compound represented by Chemical Formula 4 with the compound represented by Chemical Formula 5;

Preparing a compound represented by Chemical Formula 7 by reacting a compound represented by Chemical Formula 6 with halogen; And

Preparing a compound represented by Chemical Formula 1 by sulfonating a compound represented by Chemical Formula 7;

<Formula 1>

<Formula 4> <Formula 5>

<Formula 6>

<Formula 7>

In the above equations,

M ₁ , M ₂ and M ₃ are independently of each other hydrogen, lithium, sodium, or potassium;

Ar ₁ and Ar ₂ are each independently an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms;

R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms;

X is a halogen atom;

m and n are mole fractions, m + n = 1, and 0 <m <1, 0 <n <1.

According to another aspect of the invention there is provided a polymer electrolyte membrane comprising the copolymer.

According to another aspect of the invention there is provided a fuel cell comprising the polymer electrolyte membrane.

According to an aspect of the present invention, the fuel cell employing the polymer electrolyte membrane including the polyphenyl ether copolymer has improved properties such as hydrogen ion conductivity, methanol permeability, and water content.

Hereinafter, a polyphenyl ether copolymer according to an embodiment of the present invention, a polymer electrolyte including the same, and a fuel cell employing the same will be described in more detail.

The polyphenylether copolymer according to one embodiment of the present invention includes a repeating unit represented by the following Formula 1a and a repeating unit represented by the following Formula 1b:

<Formula 1a> <Formula 1b>

In the above formulas, M ₁ , M ₂ and M ₃ are independently of each other hydrogen, lithium, sodium, or potassium; Ar ₁ and Ar ₂ are each independently an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms; R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms; X is a halogen atom; m and n are mole fractions, m + n = 1, and 0 <m <1, 0 <n <1.

The arylene group is a divalent group having an aromatic ring system, and may include two or more ring systems, and the two or more ring systems may exist in a bonded or fused form with each other. The heteroarylene group refers to a group in which at least one carbon of the aryl group is substituted with at least one selected from the group consisting of N, O, S, and P. The aryl group is a monovalent group corresponding to the arylene group, and the heteroaryl group is a monovalent group corresponding to the heteroaryl group.

Since the sulfonic acid group of Formula 1a, which is spaced apart from the main chain in the sulfonic acid group included in the copolymer, may move relatively freely, it forms a micelle like a surfactant in the copolymer to act as an ion channel. It is easy to adjust the size of the ion channel by adjusting the length of the side chain. Therefore, the polyphenylether copolymer may easily control the amount of water contained in the ion channel and may have high hydrogen ion conductivity.

In addition, by including a hydrophobic halogen atom in addition to the benzene ring in the main chain in the copolymer, the permeation of methanol by the hydrophobic main chain can be suppressed and the water content is low. In addition, the polyphenylene ether copolymer has excellent thermal stability and stability against oxidation / reduction reaction.

On the other hand, the conventional polysulfone-based copolymer is a sulfonic acid group is directly connected to the main chain only when the content of the sulfonic acid group in the polymer is increased, the polymer itself is dissolved in water and the function of the electrolyte membrane can be lost, so the content of sulfonic acid group is limited do. Therefore, since it is difficult to have high hydrogen ion conductivity and a sulfonic acid group is directly connected to the main chain, permeation through the main chain of methanol may be easy.

According to another embodiment of the present invention, the copolymer preferably includes a repeating unit represented by the following Formula 2a and a repeating unit represented by the following Formula 2b:

<Formula 2a> <Formula 2b>

According to another embodiment of the present invention, the copolymer preferably includes a repeating unit represented by the following Formula 3a and a repeating unit represented by the following Formula 3b:

<Formula 3a> <Formula 3b>

According to another embodiment of the present invention, the ratio of m and n in the copolymer is preferably 1: 9 to 9: 1. The ratio of m and n is suitable for achieving the object of the present invention.

According to another embodiment of the present invention, the weight average molecular weight of the copolymer is preferably 10,000 to 200,000, more preferably 30,000 to 150,000. The weight average molecular weight range is suitable for achieving the object of the present invention.

According to another embodiment of the present invention, as a method for producing a polyphenyl ether copolymer represented by the formula (1), by reacting the compound represented by the formula (4) and the compound represented by the formula (5) to Preparing a compound to be displayed; Preparing a compound represented by Chemical Formula 7 by reacting a compound represented by Chemical Formula 6 with halogen; And sulfonating a compound represented by Chemical Formula 7 to prepare a compound represented by Chemical Formula 1;

<Formula 1>

<Formula 4> <Formula 5>

<Formula 6>

<Formula 7>

Wherein M ₁ , M ₂ and M ₃ are independently of each other hydrogen, lithium, sodium, or potassium; Ar ₁ and Ar ₂ are each independently an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms; R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms; X is a halogen atom; m and n are mole fractions, m + n = 1, and 0 <m <1, 0 <n <1.

According to another embodiment of the present invention, a polymer electrolyte membrane including the polyphenylene ether-based copolymer is provided. The polymer electrolyte membrane has a low methanol permeability and high hydrogen ion conductivity by including the sulfone copolymer of any one of Chemical Formulas 1 to 3. And moisture content characteristics are also excellent.

According to another embodiment of the present invention, the hydrogen ion conductivity of the polymer electrolyte membrane is preferably 1 × 10 ^-3 S / cm or more at 100% relative humidity and 25 ℃, more preferably 8 × 10 ^-3 S / cm or more, most preferably 10 × 10 ⁻³ S / cm to 200 × 10 ⁻³ S / cm.

According to another embodiment of the present invention, the methanol permeability of the polymer electrolyte membrane is preferably 20 × 10 ^-7 cm ² / s or less at 100% relative humidity and 25 ℃, more preferably 5.9 × 10 ^-7 cm ² / s or less, most preferably 4 x 10 ^-7 cm ² / s to 0.01 ㅧ 10 ^-7 cm ² / s.

According to another embodiment of the present invention, the polymer electrolyte membrane has a hydrogen ion conductivity of the electrolyte membrane of 1 × 10 ^-3 S / cm or more, methanol transmittance is preferably 5 × 10 ^-7 cm ² / S or less, More preferably, the hydrogen ion conductivity is 10 × 10 ⁻³ S / cm to 200 × 10 ⁻³ S / cm, and the methanol transmittance is 4 × 10 ⁻⁷ cm ² / s to 0.01 × 10 ^-7 cm ² / s .

According to another embodiment of the present invention, a fuel cell including the polymer electrolyte membrane is provided. The fuel cell includes a cathode, an anode, and the polymer electrolyte membrane interposed therebetween.

The cathode and anode consist of a gas diffusion layer and a catalyst layer. The catalyst layer includes a metal catalyst for promoting oxidation of hydrogen and reduction of oxygen. The catalyst layer is made of platinum, ruthenium, osmium, platinum-osmium alloy, platinum-palladium alloy, and platinum-M alloy (M is Ga, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn). It is preferable to include at least one selected from the group. In particular, it is preferable to include platinum, ruthenium, osmium, platinum-ruthenium alloys, platinum-osmium alloys, platinum-palladium alloys, platinum-cobalt alloys, platinum-nickel alloys or mixtures thereof.

The metal catalyst is generally used while supported on a carrier. The carrier may be a carbon-based material such as acetylene black or black salt; Or inorganic fine particles such as alumina and silica;

The gas diffusion layer may be carbon paper or carbon cloth, but is not limited thereto. The gas diffusion layer serves to support the fuel cell electrode and serves to make the reaction gas easily accessible to the catalyst layer by diffusing the reaction gas into the catalyst layer. As the gas diffusion layer, it is preferable to use a water repellent treatment of carbon paper or carbon cloth with a fluorine resin such as polytetrafluoroethylene. The water repellent treated carbon paper or carbon cloth may prevent the gas diffusion efficiency from being lowered by water generated when the fuel cell is driven.

The electrode may further include a microporous layer to further enhance the gas diffusion effect between the gas diffusion layer and the catalyst layer. The microporous layer may be prepared by applying a composition including an ionomer according to a filler and a filler such as carbon powder, carbon black, activated carbon, acetylene black, a conductive material such as polytetrafluoroethylene, and the like.

According to another embodiment of the present invention, it is preferable that the Sykes fuel cell is a direct methanol fuel cell. A schematic of the direct methanol fuel cell is shown in FIG. 1.

As shown in FIG. 1, the direct methanol fuel cell includes an anode 32 supplied with fuel, a cathode 30 supplied with an oxidant, and an electrolyte membrane 41 positioned between the anode 32 and the cathode 30. It includes. The anode 32 is composed of an anode diffusion layer 22 and an anode catalyst layer 33, and the cathode 30 is composed of a cathode diffusion layer 32 and a cathode catalyst layer 31.

The aqueous methanol solution transferred to the anode catalyst layer 33 through the anode diffusion layer 22 is decomposed into electrons, hydrogen ions, carbon dioxide, and the like by the catalyst. Hydrogen ions are transferred to the cathode catalyst layer 31 through the electrolyte membrane 41, electrons are transferred to an external circuit, and idealized carbon is discharged to the outside. In the cathode catalyst layer 31, water is generated by reaction of hydrogen ions transferred through the electrolyte membrane, electrons supplied from an external circuit, and oxygen in the air supplied through the cathode diffusion layer 32.

Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

(Production of Polyphenyl Ether Copolymer)

Example 1

First step: preparation of polyphenyl ether

A condenser was placed in a 500 mL three-neck flask, 12.25 g of 2,6-dimethylphenol, 2.745 g of 2,6-diphenylphenol, 0.15 g of CuCl (I), and 50 mL of pyridine was dissolved in 400 mL of 4-chlorotoluene. The solution was reacted for 18 hours at room temperature under oxygen bubbling conditions to obtain a polymer. During the reaction, the reaction solution was changed from light orange color to dark brown color. The completed polymer solution was precipitated in 2 L of methanol to obtain a solid.

¹ H NMR (400 MHz, CDCl ₃ ,): δ2.35 (s, C (CH ₃ ) ₂ ), δ6.51 (aromatic methylgroup), δ7.36 [aromatic phenylgroup]. ^{FT-IR (Film) 1500-1600cm -1} (aromatic), 2800-3100cm -1 (-CH 3).

Step 2: Bromination Step

A condenser was installed in a 100 mL three-necked flask, and 5 g of polyphenylether prepared in the first step was dissolved in 50 ml of chloroform under nitrogen conditions. A solution of 1 mL each of chloroform and bromine was added dropwise to the dropping funnel. Subsequently, the mixed solution was reacted at room temperature for 1 hour. After the reaction was completed, the reaction solution was precipitated in 800 ml of methanol to obtain a solid.

¹ H NMR (400 MHz, CDCl ₃ ,): δ2.35 (s, C (CH ₃ ) ₂ ), δ6.51 (aromatic methylgroup), δ7.36 [aromatic phenylgroup], δ6.11 (shifted bromoaromatic methyl) _. FT-IR (Film): 750cm -1 (C-Br), 1500-1600cm -1 (aromatic), 2800-3100cm -1 (-CH 3).

Step 3: sulfonation step

A condenser was installed in a 500 mL three-necked flask, and 5 g of the brominated polyphenyl ether prepared in the second step was dissolved in 250 mL of chlorobenzene in a nitrogen atmosphere. 60 mL of chlorobenzene and chlorosulfonic acid in the solution 9 mL of the mixed solution was slowly added dropwise into a dropping funnel. The mixed solution was then reacted with stirring for 1 hour at room temperature. After the reaction was completed, the reaction solution was precipitated in 2 L of a solution diluted 5: 5 of methanol and water to obtain a solid. Subsequently, the solid was washed several times with methanol and distilled water to obtain a pH of 7 to obtain a resultant represented by the following formula (8).

¹ H NMR (400 MHz, DMSO _d6 ,): δ2.35 (s, C (CH ₃ ) ₂ ), δ6.95 (shifted aromatic methylgroup δ6.51), δ6.51 (disappeared aromatic methylgroup), δ7.78, δ 7.58 [shifted aromatic phenylgroup]. FT-IR (Film): 750cm -1 (C-Br), 1500-1600cm -1 (aromatic), 2800-3100cm -1 (-CH 3), 3300-3500cm -1 (-OH).

<Formula 8>

Wherein M ₁ , M ₂ , and M ₃ are sodium, having a ratio of m = 0.9 and n = 0.1, and a weight average molecular weight of about 50,000.

Example 2

A polyphenylether copolymer was prepared in the same manner as in Example 1 except that the amount of bromine added in the second step of Example 1 was changed to 0.4 mol times with respect to 1 mol of polyphenylether.

Example 3

A polyphenylether copolymer was prepared in the same manner as in Example 1 except that the amount of bromine added in the second step of Example 1 was changed to 0.6 mol times based on 1 mol of polyphenylether.

Example 4

A polyphenylether copolymer was prepared in the same manner as in Example 1, except that the amount of bromine added in the second step of Example 1 was changed to 0.8 mol-fold with respect to 1 mol of polyphenylether.

Example 5

A polyphenylether copolymer was prepared in the same manner as in Example 1 except that the amount of bromine added in the second step of Example 1 was changed to 1.0 mol times based on 1 mol of polyphenylether.

Example 6

A polyphenylether copolymer was prepared in the same manner as in Example 1 except that the amount of bromine added in the second step of Example 1 was changed to 1.2 mol times with respect to 1 mol of polyphenylether.

Example 7

A polyphenylether copolymer was prepared in the same manner as in Example 1, except that the amount of bromine added in the second step of Example 1 was changed to 1.4 mol times based on 1 mol of polyphenylether.

Example 8

A polyphenylether copolymer was prepared in the same manner as in Example 1 except that the amount of bromine added in the second step of Example 1 was changed to 1.6 mol times based on 1 mol of polyphenylether.

(Production of Polymer Electrolyte Membrane)

Example 9

The polyphenylether copolymer prepared in Example 1 was precipitated in a 1 M concentration sulfuric acid solution at 100 ° C. for 24 hours to exchange cations of sulfonate groups from sodium to hydrogen ions. The hydrogenated copolymer was then washed with deionized water. Subsequently, the hydrogenated copolymer was dissolved in DMSO (dimethyl sulfoxide) and cast on a glass plate using a flat glass plate and a round glass rod, respectively, and dried at 150 ° C. in a vacuum oven to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 μm. Prepared.

Example 10

Using a polyphenyl ether copolymer prepared in Example 2 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 ㎛ in the same manner as in Example 9.

Example 11

Using a polyphenyl ether copolymer prepared in Example 3 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 ㎛ in the same manner as in Example 9.

Example 12

Using a polyphenyl ether copolymer prepared in Example 4 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 ㎛ in the same manner as in Example 9.

Example 13

Using a polyphenyl ether copolymer prepared in Example 5 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 ㎛ in the same manner as in Example 9.

Example 14

Using a polyphenyl ether copolymer prepared in Example 6 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 ㎛ in the same manner as in Example 9.

Example 15

Using a polyphenyl ether copolymer prepared in Example 7 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1㎛ in the same manner as in Example 9.

Example 16

Using a polyphenyl ether copolymer prepared in Example 8 to prepare a polymer electrolyte membrane having a thickness of 0.01-0.1 ㎛ in the same manner as in Example 9.

Comparative Example 1

Polysulfone polymer (BASF, ULTRASON S3010) represented by the following formula (8) was sulfated in the same manner as in Example 9 was used as a polymer electrolyte membrane

<Formula 8>

Comparative Example 2

Nafion 112 (DuPont) was used as the polymer electrolyte membrane.

Nafion 112 was precipitated in a 1 M concentration sulfuric acid solution at 100 ° C. for 24 hours to exchange the cation of the sulfonate group from sodium to hydrogen ions. The hydrogenated copolymer was then washed with deionized water.

Evaluation Example 1 Hydrogen Ion Conductivity Measurement

Proton conductivity was measured for each of the polymer electrolyte membranes of Examples 9 to 16 and Comparative Examples 1 and 2, respectively. Hydrogen ion conductivity was measured by interposing the polymer electrolyte membrane between two platinum electrodes having a width of 2.54 cm ² , and then initial resistance value at 30 ° C. using an electrochemical impedance spectroscopy (EIS) with IM6ex (Zahner). Was measured, and then hydrogen ion conductivity was calculated using Equation 1 below. The results are shown in Table 1 below.

&Quot; (1) &quot;

Hydrogen ion conductivity [S / cm] = (film thickness [cm] / film area [cm ² ]) x initial conductivity [S]

Evaluation Example 2: Methanol Permeability Measurement

After interposing the polymer electrolyte membranes of Examples 9-16 and Comparative Examples 1 and 2 between the two cells, 15 mL of 1 M aqueous methanol solution was injected into one cell, and 15 mL of distilled water was injected into the other cell, followed by distilled water. 10 μl was aliquoted per 10 minutes in a cell containing 10 μl, and then filled with 10 μl of distilled water. The aliquot was sampled and the methanol concentration was measured by gas chromatography. In addition, the change in methanol concentration over time was plotted and the methanol permeability was calculated from the slope using Equation 2 below. The results are shown in Table 1 below.

<Equation 2>

Methanol permeability [cm ² / S] = (Slope [ppm / s] × solution volume × electrolyte membrane thickness) / (electrolyte membrane area × methanol concentration)

In the above formula, the electrolyte membrane thickness 0.05㎛, the diameter of the membrane 3cm; Methanol concentration of 1 mol (32000 ppm); Solution volume 15 ml; Membrane area 7.06cm ²

Evaluation Example 3: Water Content

Each of the polymer electrolyte membranes of Examples 9 to 16 and Comparative Examples 1 and 2 was immersed in 30 ° C. distilled water for 24 hours. After immersion, the polymer electrolyte membrane was taken out, weighed (M _wet ), and placed in a vacuum oven at 100 ° C. for 24 hours. After drying again weighing (M _dry ), the moisture content was calculated by the following equation (3). The results are shown in Table 1 below.

<Equation 3>

Water uptake [%] = (M _wet -M _dry ) / M _dry

TABLE 1

Hydrogen ion conductivity [S / cm] Methanol transmittance [cm ² / S] Water content [%] Example 9 2.30 × 10 ^-3 1.90 × 10 ^-7 7 Example 10 3.57 × 10 ^-3 2.02 × 10 ^-7 16 Example 11 4.45 × 10 ^-3 2.21 × 10 ^-7 22 Example 12 6.53 × 10 ^-3 2.64 × 10 ^-7 28 Example 13 8.61 × 10 ^-3 2.78 × 10 ^-7 34 Example 14 9.89 × 10 ^-3 2.98 × 10 ^-7 41 Example 15 12.7 × 10 ^-3 3.21 × 10 ^-7 45 Example 16 14.0 × 10 ^-3 3.50 × 10 ^-7 49.43 Comparative Example 1 7.0 × 10 ^-3 6.0 × 10 ^-7 54 Comparative Example 2 80 × 10 ^-3 21.7 × 10 ^-7 29.5

As shown in Table 1, the polymer electrolyte membranes of Examples 9 to 16 including the polyphenyl ether copolymer according to one embodiment of the present invention show lower methanol permeability and water content than Comparative Example 1. In particular, Examples 13-16 show higher methanol ion conductivity and lower methanol permeability and water content than Comparative Example 1. In addition, it shows a significantly lower methanol permeability compared to Comparative Example 2.

1 is a schematic diagram of a direct methanol fuel cell according to one embodiment of the invention.

Claims (10)

A polyphenyl ether copolymer comprising a repeating unit represented by the following Formula 1a and a repeating unit represented by the following Formula 1b: <Formula 1a> <Formula 1b>

In the above equations, M ₁ , M ₂ and M ₃ are independently of each other hydrogen, lithium, sodium, or potassium; Ar ₁ and Ar ₂ are each independently an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms; R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms; X is a halogen atom; m and n are mole fractions, m + n = 1, and 0 <m <1, 0 <n <1. The copolymer according to claim 1, wherein the copolymer comprises a repeating unit represented by the following Formula 2a and a repeating unit represented by the following Formula 2b: <Formula 2a> <Formula 2b>

The copolymer according to claim 1, wherein the copolymer comprises a repeating unit represented by the following Chemical Formula 3a and a repeating unit represented by the following Chemical Formula 3b: <Formula 3a> <Formula 3b>

The copolymer of claim 1, wherein the ratio of m and n is 1: 9 to 9: 1. The copolymer according to claim 1, wherein the copolymer has a weight average molecular weight of 10,000 to 200,000. As a method for producing a polyphenyl ether copolymer represented by the formula (1), Preparing a compound represented by Chemical Formula 6 by reacting the compound represented by Chemical Formula 4 with the compound represented by Chemical Formula 5; Preparing a compound represented by Chemical Formula 7 by reacting a compound represented by Chemical Formula 6 with halogen; And Preparing a compound represented by Chemical Formula 1 by sulfonating a compound represented by Chemical Formula 7; <Formula 1>

<Formula 4> <Formula 5>

<Formula 6>

<Formula 7>

Where M ₁ , M ₂ and M ₃ are independently of each other hydrogen, lithium, sodium, or potassium; Ar ₁ and Ar ₂ are each independently an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms; R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms; X is a halogen atom; m and n are mole fractions, m + n = 1, and 0 <m <1, 0 <n <1. A polymer electrolyte membrane comprising the copolymer according to any one of claims 1 to 5. 8. The polymer electrolyte membrane according to claim 7, wherein the electrolyte membrane has a hydrogen ion conductivity of 1 × 10 ⁻³ S / cm or more and a methanol transmittance of 5 × 10 ⁻⁷ cm ² / S or less. A fuel cell employing the polymer electrolyte membrane of claim 8. 10. The fuel cell of claim 9, wherein the fuel cell is a direct methanol fuel cell.

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