KR101573191B1 - Polyphenylehter based copolymer method for preparing the copolymer polymer electrolyte membrane comprising the copolymer and fuel cell comprising the membrane - Google Patents

Abstract

The present invention discloses a polyphenyl ether-based copolymer comprising a repeating unit represented by the following formula (1a) and a repeating unit represented by the following formula (1b):

&Lt; Formula 1a > < EMI ID =

In this formula,

M ₁ , M ₂ , M ₃ , Ar ₁ , A4 ₂ , R ₁ , R ₂ , R ₃ , R ₄ , X, m and n refer to the detailed description of the invention.

Polyphenyl ether, fuel cell

Description

TECHNICAL FIELD The present invention relates to a polyphenylene ether-based copolymer, a method for producing the same, a polymer electrolyte membrane containing the same, and a fuel cell employing the same.

The present invention relates to a polyphenyl ether-based copolymer, a method for producing the same, a polymer electrolyte membrane containing the same, and a fuel cell employing the same. More particularly, the present invention relates to a polyphenyl ether- And a fuel cell including the polymer electrolyte membrane.

The fuel cell can be classified into a polymer electrolyte membrane fuel cell (PEMFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide And a solid oxide fuel cell (SOFC). The operating temperature of the fuel cell, the material of the component parts, and the like depend on the type of electrolyte used. PEMFC (Polymer Electrolyte Membrane Fuel Cell) has superior power, lower operating temperature, and faster response characteristics than other fuel cells.

Fuel cells are divided into fuel direct supply type or internal reforming type according to the manner in which fuel is supplied to the anode. Direct methanol fuel cell (DMFC) is a typical direct fuel supply type. A direct methanol fuel cell uses a polymer electrolyte membrane as an electrolyte and therefore belongs to a polymer electrolyte fuel cell. Since direct methanol fuel cell uses methanol as fuel, it does not use a hydrogen reformer, and because it operates at a low temperature, it is possible to construct a system simple and compact, which is suitable as a power source for small devices and portable devices.

A fuel cell is composed of a power generation unit, a reformer, a fuel tank, and a fuel pump, in which electricity is generated. The power generation portion forms the 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 the pump to generate electric energy by electrochemical reaction. The power generation unit may include a membrane electrode assembly (MEA) composed 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 ability is used. Commercially, a hydrophobic ion exchange membrane containing a sulfonic acid group is mainly used. This is because the acidity of the sulfonic acid group is very large and the C-S bond is stable even under the oxidizing conditions. In the proton exchange membrane where sulfonic acid groups are present, water molecules must be present together to maintain the proton conductivity. In the presence of water molecules, the sulfonic acid groups present in the electrolyte membrane dissociate into sulfonate anions and hydrogen ions, and hydrogen ions migrate by the gradient of hydrogen ion concentration or electric field as in the case of sulfuric acid solution electrolytes. The hydrogen ion conductivity is affected by the number of sulfonic acid groups contained in the polymer electrolyte membrane, the structure of the polymer electrolyte membrane, and the amount of water contained in the polymer electrolyte membrane.

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

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

One aspect of the present invention is to provide a polyphenyl ether-based copolymer having a novel structure.

Another aspect of the present invention is to provide a process for producing the polyphenyl ether-based copolymer.

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

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

According to one aspect of the present invention, there is provided a polyphenyl ether-based copolymer comprising a repeating unit represented by the following formula (1a) and a repeating unit represented by the following formula (1b):

&Lt; Formula 1a > < EMI ID =

In the above equations,

M ₁ , M ₂ and M ₃ independently of one another are 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, and m + n = 1, 0 <m <1, 0 <n <1.

According to another aspect of the present invention, there is provided a process for producing a polyphenyl ether-

Reacting a compound represented by the following formula (4) with a compound represented by the following formula (5) to prepare a compound represented by the following formula (6);

Reacting a compound represented by the following formula (6) with a halogen to prepare a compound represented by the following formula (7); And

And subjecting the compound represented by the following formula (7) to sulfonation to prepare a compound represented by the following formula (1): &lt; EMI ID =

&Lt; Formula 1 >

&Lt; Formula 4 > < EMI ID =

(6)

&Lt; Formula 7 >

In the above equations,

M ₁ , M ₂ and M ₃ independently of one another are 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, and m + n = 1, 0 <m <1, 0 <n <1.

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

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

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

Hereinafter, a polyphenyl ether-based copolymer, a polymer electrolyte including the same, and a fuel cell employing the same will be described in more detail.

The polyphenyl ether-based 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):

&Lt; Formula 1a > < EMI ID =

In the above formulas, M ₁ , M ₂ and M ₃ independently of one another are 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, and m + n = 1, 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 to each other. The heteroarylene group refers to a group in which at least one of the aryl groups is substituted with at least one member 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 the formula (Ia) existing in the sulfonic acid group contained in the copolymer apart from the main chain via the side chain can move relatively freely, a micelle such as a surfactant in the copolymer acts as an ion channel And the size of the ion channel can be adjusted by adjusting the length of the side chain. Therefore, the polyphenyl ether-based copolymer can easily control the amount of water contained in the ion channel and can have a high hydrogen ion conductivity.

Further, in the copolymer, addition of a hydrophobic halogen atom in addition to the benzene ring in the main chain can suppress the permeation of methanol by the backbone which is a minor portion, and the water content is also low. Further, the polyphenylene ether copolymer has excellent thermal stability and stability against oxidation / reduction reaction.

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

According to another embodiment of the present invention, it is preferable that the copolymer includes a repeating unit represented by the following formula (2a) and a repeating unit represented by the following formula (2b)

&Lt; Formula 2a > < EMI ID =

According to another embodiment of the present invention, it is preferable that the copolymer includes a repeating unit represented by the following formula (3a) and a repeating unit represented by the following formula (3b):

&Lt; EMI ID =

According to another embodiment of the present invention, it is preferable that the ratio of m and n in the copolymer is 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, there is provided a process for producing a polyphenyl ether-based copolymer represented by the following general formula (1), comprising reacting a compound represented by the following general formula (4) with a compound represented by the following general formula Preparing a compound to be displayed; Reacting a compound represented by the following formula (6) with a halogen to prepare a compound represented by the following formula (7); And sulfonating the compound represented by the formula (7) to prepare a compound represented by the following formula (1): &lt; EMI ID =

&Lt; Formula 1 >

&Lt; Formula 4 > < EMI ID =

(6)

&Lt; 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, and m + n = 1, 0 <m <1, 0 <n <1.

According to another embodiment of the present invention, there is provided a polymer electrolyte membrane comprising the polyphenylene ether-based copolymer. Since the polyelectrolyte membrane contains a sulfonic copolymer of any one of formulas (1) to (3), methanol permeability is low and hydrogen ion conductivity is high. The water content is also excellent.

According to another embodiment of the present invention, the hydrogen ion conductivity of the polymer electrolyte membrane is preferably 1 x 10 ^-3 S / cm or more at a relative humidity of 100% and 25 ° C, more preferably 8 x 10 ^-3 S / cm or more, and most preferably 10 x ^10-3 S / cm to 200 x ^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 a relative humidity of 100% and 25 ° C., more preferably 5.9 × 10 ^-7 cm ² / s, and most preferably from 4 x 10 ^-7 cm ² / s to 0.01 x 10 ^-7 cm ² / s.

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

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

The cathode and the anode are composed of a gas diffusion layer and a catalyst layer. The catalyst layer includes a metal catalyst that promotes 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, And at least one selected from the group consisting of &lt; RTI ID = 0.0 &gt; In particular, it is preferable to include platinum, ruthenium, osmium, a platinum-ruthenium alloy, a platinum-osmium alloy, a platinum-palladium alloy, a platinum-cobalt alloy, a platinum-nickel alloy or a mixture thereof.

The metal catalyst is generally used while being 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 can be used.

The gas diffusion layer may be made of carbon paper or carbon cloth, but is not limited thereto. The gas diffusion layer plays the role of supporting the electrode for the fuel cell and diffuses the reaction gas into the catalyst layer to make the reaction gas easily accessible to the catalyst layer. The gas diffusion layer is preferably a carbon paper or a carbon cloth which has been subjected to a water-repellent treatment with a fluorine resin such as polytetrafluoroethylene. The water repellent treated carbon paper or carbon cloth can prevent the gas diffusion efficiency from being lowered due to water generated when the fuel cell is driven.

The electrode may further include a microporous layer for further enhancing a gas diffusion effect between the gas diffusion layer and the catalyst layer. The microporous layer may be formed by applying a conductive material such as carbon powder, carbon black, activated carbon, or acetylene black, a binder such as polytetrafluoroethylene, or a composition containing an ionomer according to the purpose of the fill.

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

1, the direct methanol fuel cell includes an anode 32 to which a fuel is supplied, a cathode 30 to which an oxidizing agent is supplied, and an electrolyte membrane 41 that is disposed between the anode 32 and the cathode 30, . The anode 32 includes an anode diffusion layer 22 and an anode catalyst layer 33. The cathode 30 includes a cathode diffusion layer 32 and a cathode catalyst layer 31. [

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

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

(Preparation of polyphenyl ether-based copolymer)

Example 1

Step 1: Preparation of polyphenyl ether

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

¹ H NMR (400 MHz, CDCl ₃ ):? 2.35 (s, C (CH ₃ ) ₂ ),? 6.51 (aromatic methyl group),? 7.36 [aromatic phenylgroup]. ^{FT-IR (Film) 1500-1600cm -1} (aromatic), 2800-3100cm -1 (-CH 3).

Step 2: Bromination Step

A condenser was placed in a 100 mL three-necked flask, and 5 g of the polyphenyl ether prepared in the first step was dissolved in 50 mL of chloroform under a nitrogen atmosphere. A solution prepared by mixing 1 mL each of chloroform and bromine in the above solution was slowly added dropwise to the dropping funnel. Then, 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 ):? 2.35 (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 placed 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. To the solution was added 60 mL of chlorobenzene, 9 mL of the mixed solution was slowly added dropwise to the dropping funnel. Then, the mixed solution was reacted while stirring at room temperature for 1 hour. After the reaction was completed, the reaction solution was precipitated in 2 L of a 5: 5 dilution of methanol and water to obtain a solid. Subsequently, the solid was washed with methanol and distilled water several times to obtain a pH of 7 to obtain the product represented by the following formula (8).

_{^{1 H NMR (400MHz, DMSO d6}} ,): δ2.35 (s, C (CH 3) 2), δ6.95 (shifted aromatic methylgroup δ6.51), δ6.51 (disappeared aromatic methylgroup), δ7.78,隆 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).

(8)

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

Example 2

A polyphenyl ether 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 the amount of 1 mol of the polyphenyl ether.

Example 3

A polyphenyl ether 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 the amount of 1 mol of the polyphenyl ether.

Example 4

A polyphenyl ether 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 times as much as 1 mol of polyphenyl ether.

Example 5

A polyphenyl ether 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 the amount of 1 mol of the polyphenyl ether.

Example 6

A polyphenyl ether 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 the amount of 1 mol of the polyphenyl ether.

Example 7

A polyphenyl ether 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 the amount of 1 mol of the polyphenyl ether.

Example 8

A polyphenyl ether 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 with respect to 1 mol of the polyphenyl ether.

(Production of polymer electrolyte membrane)

Example 9

The polyphenyl ether copolymer prepared in Example 1 was precipitated in a 1M sulfuric acid solution at 100 ° C for 24 hours to exchange cations of the sulfonate group with sodium ion to hydrogen ion. The hydrogenated copolymer was then washed with deionized water. Next, the hydrogenated copolymer was dissolved in dimethyl sulfoxide (DMSO), cast on a flat glass plate and a round glass rod, and dried in a vacuum oven at 150 ° C. to form a polymer electrolyte membrane having a thickness of 0.01 to 0.1 μm .

Example 10

A polyelectrolyte membrane having a thickness of 0.01 to 0.1 탆 was prepared in the same manner as in Example 9, using the polyphenyl ether-based copolymer prepared in Example 2.

Example 11

A polyelectrolyte membrane having a thickness of 0.01 to 0.1 탆 was prepared in the same manner as in Example 9, using the polyphenyl ether-based copolymer prepared in Example 3.

Example 12

A polyelectrolyte membrane having a thickness of 0.01-0.1 탆 was prepared in the same manner as in Example 9 using the polyphenyl ether-based copolymer prepared in Example 4.

Example 13

A polyelectrolyte membrane having a thickness of 0.01 to 0.1 탆 was prepared in the same manner as in Example 9, using the polyphenyl ether-based copolymer prepared in Example 5.

Example 14

A polyelectrolyte membrane having a thickness of 0.01 to 0.1 탆 was prepared in the same manner as in Example 9, using the polyphenyl ether-based copolymer prepared in Example 6.

Example 15

A polyelectrolyte membrane having a thickness of 0.01 to 0.1 m was prepared in the same manner as in Example 9, using the polyphenyl ether-based copolymer prepared in Example 7.

Example 16

A polyelectrolyte membrane having a thickness of 0.01 to 0.1 탆 was prepared in the same manner as in Example 9, using the polyphenyl ether-based copolymer prepared in Example 8.

Comparative Example 1

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

(8)

Comparative Example 2

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

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

Evaluation Example 1: Measurement of hydrogen ion conductivity

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

&Quot; (1) &quot;

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

Evaluation Example 2: Measurement of methanol permeability

After the polymer electrolyte membranes of Examples 9-16 and Comparative Examples 1 and 2 were respectively sandwiched between two cells, 15 mL of 1M aqueous methanol solution was injected into one cell, and 15 mL of distilled water was injected into another cell, 10 [mu] l / 10 min in each cell, and then filled with 10 [mu] l of distilled water. The collected samples were analyzed for methanol concentration by gas chromatography. Further, a change in methanol concentration with time was plotted and a methanol permeability was calculated from the slope using the following equation (2). The results are shown in Table 1 below.

&Quot; (2) &quot;

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

In the above equation, the electrolyte membrane thickness is 0.05 mu m, the membrane diameter is 3 cm; 1 mol of methanol (32000 ppm); Solution volume 15 ml; Membrane area 7.06 cm ²

Evaluation Example 3: Moisture content

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

&Quot; (3) &quot;

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

<Table 1>

Hydrogen ion conductivity [S / cm] Methanol permeability [cm ² / S] Moisture content [%] Example 9 2.30 × 10 ^-3 1.90 × 10 ^-7 7 Example 10 3.57 x 10 ^-3 2.02 × 10 ^-7 16 Example 11 4.45 x 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 x 10 ^-7 49.43 Comparative Example 1 7.0 × 10 ^-3 6.0 × 10 ^-7 54 Comparative Example 2 80 x 10 ^-3 21.7 × 10 ^-7 29.5

As shown in Table 1, the polyelectrolyte membranes of Examples 9 to 16 including the polyphenyl ether-based copolymer according to one embodiment of the present invention show lower methanol permeability and water content than Comparative Example 1. In particular, Examples 13 to 16 show a higher methanol permeability and water content while showing a higher hydrogen ion conductivity than Comparative Example 1. [ In addition, the methanol permeability is significantly lower than that of Comparative Example 2.

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

Claims (10)

A polyphenyl ether-based copolymer comprising a repeating unit represented by the following formula (1a) and a repeating unit represented by the following formula (1b): &Lt; Formula 1a > < EMI ID =

In the above equations, M ₁ , M ₂ and M ₃ independently of one another are hydrogen, lithium, sodium or potassium; Ar ₁ and Ar ₂ are independently of each other an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms, wherein said heteroarylene group is a group consisting of N, O, S and P &Lt; / RTI &gt; R ₁ , R ₂ , R ₃ and R ₄ independently of one another are 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, Is a group substituted with at least one member selected from the group consisting of N, O, S and P; X is a halogen atom; m and n are mole fractions, and m + n = 1, 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): &Lt; Formula 2a > < EMI ID =

The copolymer according to claim 1, wherein the copolymer comprises a repeating unit represented by the following formula (3a) and a repeating unit represented by the following formula (3b): &Lt; EMI ID =

The copolymer according to claim 1, wherein the ratio of m to 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. A process for producing a polyphenyl ether-based copolymer represented by the following formula (1) Reacting a compound represented by the following formula (4) with a compound represented by the following formula (5) to prepare a compound represented by the following formula (6); Reacting a compound represented by the following formula (6) with a halogen to prepare a compound represented by the following formula (7); And And subjecting the compound represented by the following formula (7) to sulfonation to prepare a compound represented by the following formula (1): &lt; EMI ID = &Lt; Formula 1 >

&Lt; Formula 4 > < EMI ID =

(6)

&Lt; Formula 7 >

In this formula, M ₁ , M ₂ and M ₃ independently of one another are hydrogen, lithium, sodium or potassium; Ar ₁ and Ar ₂ are independently of each other an arylene group having 6 to 20 carbon atoms or a heteroarylene group having 2 to 20 carbon atoms, wherein said heteroarylene group is a group consisting of N, O, S and P &Lt; / RTI &gt; R ₁ , R ₂ , R ₃ and R ₄ independently of one another are 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, Is a group substituted with at least one member selected from the group consisting of N, O, S and P; X is a halogen atom; m and n are mole fractions, and m + n = 1, 0 <m <1, 0 <n <1. A polymer electrolyte membrane comprising a copolymer according to any one of claims 1 to 5. The polymer electrolyte membrane according to claim 7, wherein the electrolyte membrane has a hydrogen ion conductivity of 1 x 10 ^-3 S / cm or more and a methanol permeability of 5.9 x ^10-7 cm ² / S or less. A fuel cell employing the polymer electrolyte membrane of claim 8. 10. The fuel cell according to claim 9, wherein the fuel cell is a direct methanol fuel cell.

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