KR20090053231A - Polymer membranes containing partially fluorinated copolymer, manufacturing method thereof and polymer electrolyte fuel cell using them - Google Patents

Abstract

The present invention relates to a polymer electrolyte membrane containing an ion conductive copolymer partially introduced with fluorine, a method for preparing the same, and a polymer electrolyte fuel cell employing the polymer electrolyte membrane.

The polymer electrolyte membrane of the present invention is manufactured by partially introducing fluorine into a sulfonated polyarylene ether copolymer, thereby maintaining high ionic conductivity due to chemically stable properties of the fluorinated material, and achieving low water absorption and low methanol permeability. As a result, it is possible to replace the conventional polymer electrolyte membrane, and to improve the performance of the polymer electrolyte fuel cell including the polymer electrolyte membrane having improved physical properties.

Ion conductive polymers, polymer electrolyte membranes, polymer electrolyte fuel cells, partially fluorinated copolymers

Description

POLYMER MEMBRANES CONTAINING PARTIALLY FLUORINATED COPOLYMER, MANUFACTURING METHOD THEREOF AND POLYMER ELECTROLYTE FUEL CELL USING THEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte membrane containing an ion conductive copolymer partially introduced with fluorine, a method for preparing the same, and a polymer electrolyte fuel cell employing the polymer electrolyte membrane, and more particularly, to sulfonated polyarylene ether air. A polymer electrolyte membrane containing a partially fluorine-incorporated ion-conducting copolymer in which high ionic conductivity is maintained and low water absorption and low methanol permeability are realized by partially introducing fluorine into the copolymer, thereby A polymer electrolyte fuel cell employing a manufacturing method and a polymer electrolyte membrane.

A fuel cell is an electrical device in which chemical energy generated by combustion of fuel can be directly converted into electrical energy. A fuel cell is a cathode (sometimes called a “fuel electrode” or an “anode”) that physically oxidizes a fuel, an anode (also called an “air electrode” or a “reduction electrode”) in which reduction of an oxidant occurs, and an electrolyte membrane. It is composed of a structure connected to an external circuit. Hydrogen ions formed by the oxidation reaction at the cathode react with the oxidant introduced from the outside through the electrolyte and electrons moved through the circuit to generate water as a byproduct. In a typical fuel cell, the electrochemical reactions occurring at the cathode and the anode are as follows.

_{Anode: H 2 (g) → 2H} + + 2e -

_{Anode: ½ O 2 (g) +} 2H + + 2e - → H 2 O

Overall Reaction: H _{2 (g)} + ½ O ₂ → H ₂ O

In other words, a fuel cell is a pollution-free energy source that directly converts chemical reaction energy of hydrogen and oxygen into electrical energy, and has high power density and energy conversion efficiency, and miniaturization and use of various fuels enable portable power sources such as mobile communication equipment. It can be applied to a wide range of fields such as power supply for transportation of automobiles, power generation system for home and military.

Fuel cells are classified into a polymer electrolyte fuel cell, an alkaline fuel cell, a phosphate fuel cell, a molten carbonate fuel cell, and a solid oxide fuel cell according to the operating temperature and the type of the electrolyte. In particular, the polymer electrolyte fuel cell has attracted attention as a fuel cell due to its low operating temperature, high output density, and low environmental load, which, in turn, is directly converted into methanol without a hydrogen ion exchange membrane fuel cell and a reformer in which hydrogen gas is used as a fuel. It is divided into direct methanol fuel cell used as fuel.

In a fuel cell, a stack that substantially generates electricity has a structure in which several to tens of unit cells are formed of a membrane-electrode assembly (Membrane Electrode Assembly) and a separator, to which a cathode and an anode are bonded, with a polymer electrolyte membrane interposed therebetween. Have

The anode and cathode of a polymer electrolyte fuel cell are composed of a carbon-based ionic support on which metal particles such as platinum are deposited, and Nafion (Nafion ^®) is used to improve the adhesion between the polymer electrolyte membrane and the hydrogen ion conductivity in the three-phase interface. ) Coating layer is added at a rate of 1-10 mg / cm ² .

In particular, the electrochemical reaction of the direct methanol fuel cell is as follows.

_{Anode: CH 3 OH + H 2 O} → CO 2 + 6H + + 6e -

^{_{Anode: ⅔O 2 + 6H + + 6e}} - → CO 2 + 2H 2 O

Overall Reaction: CH ₃ OH + ⅔O ₂ → 2H ₂ O + CO ₂

Since the polymer electrolyte membrane for a polymer electrolyte fuel cell plays a role of a conductive polymer for transferring hydrogen ions from a cathode to an anode, chemical, thermal, mechanical, and electrochemical stability is required in addition to high ionic conductivity. In particular, in the case of the direct methanol fuel cell, the role of suppressing the movement of the fuel methanol from the cathode to the anode is further required. Accordingly, the polymer electrolyte membrane preferably has a thickness of 5 to 175 μm with high density, low porosity, and low methanol permeability, and should have excellent mechanical stability and adhesion to the electrode.

It must also be durable, thermally, physically and chemically stable to operate in high temperatures above 90 ° C and in extreme acidic environments. For this reason, research on polymer electrolyte membranes has been recognized as a key factor in fuel cell development.

A film currently commercially polymer electrolyte membrane that US DuPont Nafion (Nafion ^®) film and a Japanese player lukewarm (Flemion ^®). It is a perfluorinated sulfonic acid electrolyte membrane, which has excellent conductivity, mechanical properties, and chemical resistance, but has a high production cost due to complex synthetic raw materials or manufacturing processes, and is a poisonous intermediate product generated by fluorine forming a polymer main chain, causing environmental pollution. do. In addition, the perfluorinated sulfonic acid electrolyte membrane shows high methanol permeation and ionic conductivity rapidly decreases above 100 ° C. Accordingly, researches on new copolymers for supplementing the above problems have been actively conducted. As examples thereof, sulfonated polyarylene ether sulfones, sulfonated polyether ether ketones and sulfonated polyimides have been disclosed. [ J. Membr . Sci . , 197 (2002) 231; J. Electrochem . Soc . 151 (21) (2004) A2150; Micromol . Symp . 175 (2001) 387; J. Membr . Sci ., 185 (2001) 73; J. Membr . Sci . , 281 (2006) 121. United States Patent Nos. 2005-026144, 2006-0134493, 5,438,082 and 6,245,881.

However, most of the above-mentioned operations to lower the methanol permeability resulted in a decrease in the concentration of the hydrophilic ion exchange group, leading to an adverse effect of lowering the ionic conductivity of the electrolyte membrane, and the methanol permeability and water absorption rate of the electrolyte membrane were greatly increased as the sulfonation degree increased. However, the performance of the fuel cell is degraded and the durability is not sufficient to be used as a fuel cell membrane.

On the other hand, new polyarylethers containing perfluoroalkyl groups were reported in 1990 ( Macromolecules , 1990, 23, 5371 and US Pat. No. 5,155,175), but these reports do not disclose electrochemical, mechanical properties and ion conductivity. .

Accordingly, the present inventors have tried to obtain a polymer electrolyte membrane having improved physical properties, and partially introduce fluorine into a sulfonated polyarylene ether to form a copolymer, to prepare an electrolyte membrane using the polymer electrolyte membrane, and the polymer electrolyte membrane has excellent ion conductivity. The present invention was completed by confirming having a water absorption and low methanol permeability at the same time.

An object of the present invention is to provide a polymer electrolyte membrane containing a sulfonated polyarylene ether copolymer partially introduced with fluorine.

Another object of the present invention is to provide a method for preparing a polymer electrolyte membrane containing a copolymer partially introduced with fluorine.

Still another object of the present invention is to provide a membrane-electrode assembly composed of a polymer electrolyte membrane containing a copolymer partially introduced with fluorine and a polymer electrolyte fuel cell employing the membrane.

In order to achieve the above object, the present invention provides a polymer electrolyte membrane containing a sulfonated polyarylene ether copolymer partially introduced with fluorine represented by the following formula (1).

Wherein Y is any one selected from the group consisting of -S-, -SO ₂ -and -C = O- or a combination thereof, and Z is a bond, -O-, -SO ₂ -, -C = O-, -C (CH ₃ ) ₂ -and -C (CF ₃ ) _2- , any one selected from p, p is 1 to 6, n + m = k, and n / (n + m) is 0.1 to 0.99)

At this time, it is more preferable that n / (n + m) is 0.4-0.5.

The present invention also provides a method for preparing a polymer electrolyte membrane composed of a sulfonated polyarylene ether copolymer partially containing fluorine. a) a sulfonated aromatic monomer represented by the following formula (2), a fluorine-containing monomer represented by the following formula (3) and a dihydroxyl monomer represented by the following formula (4) by a direct polymerization reaction, B) preparing a copolymer, b) dissolving a copolymer represented by the following formula (5) in a polar solvent and casting it on a glass plate or a teflon plate, and evaporating the solvent to remove it, followed by conversion into a sulfonic acid form, represented by the following formula (1) It provides a method for producing a polymer electrolyte membrane consisting of a sulfonated polyarylene ether copolymer in which partially fluorine is introduced.

(In the above, Y, Z, p, n, m and k are as defined above, X is a halogen atom or a nitro group containing F, Cl, Br as leaving group.)

The degree of sulfonation of the sulfonated polyarylene ether copolymer is 40 to 50 mol%, wherein the sulfonated aromatic sulfonated polyarylene ether copolymer is represented by Formula 2 Reaction is determined by reacting with 100 parts by weight of the dihydroxyl monomer represented by Formula 4 with respect to 100 parts by weight of a copolymer composed of 40 to 50 mol% of monomers and 50 to 60 mol% of monomers containing fluorine represented by Formula 3. do.

In addition, the polar solvent is any one selected from the group consisting of 1-methyl-2-pyrrolidinone, N, N-dimethylacetamide and dimethylformamide, the copolymer represented by the formula (5) is N-methyl- The intrinsic viscosity is above 0.8 on the 2-pyrrolidinone solvent.

In this case, the thickness of the polymer electrolyte membrane is preferably 1 to 1000㎛.

The present invention also provides a membrane-electrode assembly for a polymer electrolyte fuel cell having a polymer electrolyte membrane containing a sulfonated polyarylene ether copolymer partially introduced with fluorine.

Further, a polymer electrolyte fuel cell employing the membrane-electrode assembly is provided.

Furthermore, the present invention provides a sulfonated polyarylene ether copolymer for producing a polymer electrolyte membrane partially containing fluorine represented by the following formula (1).

Formula 1

(In the above, Y, Z, p, n, m and k are as defined above.)

According to the present invention, a copolymer is prepared by partially introducing fluorine into a sulfonated polyarylene ether copolymer, and the polymer electrolyte membrane made of the copolymer maintains high ionic conductivity, low water absorption and low methanol permeability. . Accordingly, the polymer electrolyte membrane having improved physical properties may be replaced with a conventional polymer electrolyte membrane, and a polymer electrolyte fuel cell employing the polymer electrolyte membrane may be provided.

Hereinafter, the present invention will be described in more detail.

The present invention provides a polymer electrolyte membrane containing a sulfonated polyarylene ether copolymer partially introduced with fluorine represented by the following general formula (1).

Formula 1

Wherein Y is any one selected from the group consisting of -S-, -SO ₂ -and -C = O- or a combination thereof, and Z is a bond, -O-, -SO ₂ -, -C = O-, -C (CH ₃ ) ₂ -and -C (CF ₃ ) _2- , any one selected from p, p is 1 to 6, n + m = k, and n / (n + m) is 0.1 to 0.99)

The polymer electrolyte membrane of the present invention is characterized in that fluorine is partially introduced into a conventional sulfonated polyarylene ether. Due to the chemically stable properties of the fluorinated material, when it is applied to the polymer electrolyte membrane, it has high ionic conductivity and low methanol permeability and low water absorption. At this time, the degree of fluorination is possible by controlling the p of the formula (1), and if the p exceeds 6, the mechanical stability of the polymer is reduced by increasing the length of the linear structure -CF ₂ -bond that can be rotated methanol Since the permeability is significantly increased, it is preferable to satisfy the above range.

The physical properties of the polymer electrolyte membrane of the present invention can also be adjusted by determining the range of n, m and k in Formula 1, wherein k in Formula 1 is defined as n + m, and n / (n + m) is 0.01 To 0.99, more preferably 0.4 to 0.5. When n / (n + m) is less than 0.01, the sulfonation degree of the copolymer of Chemical Formula 1 is not sufficient, so that its ion conductivity is low, and its utilization is poor. When n / (n + m) is more than 0.99, hydrophilic properties are not achieved. There is a problem in that the sulfonation degree to have a high water absorption rate and methanol permeability increases.

In the polymer electrolyte membrane of the present invention, a copolymer is formed by partially introducing fluorine into sulfonated polyarylene ether to prepare a polymer electrolyte membrane using the copolymer. Due to the chemically stable nature of the fluorinated material, the polymer electrolyte membrane of the present invention maintains high ionic conductivity and at the same time has excellent mechanical properties, thermal stability, low water absorption and low methanol permeability (FIGS. 3 to 5).

The present invention also provides a method for producing a polymer electrolyte membrane composed of a sulfonated polyarylene ether copolymer partially containing fluorine represented by Chemical Formula 1. A copolymer represented by the following formula (5) by directly polymerizing a sulfonated aromatic monomer represented by the following formula (2), a monomer containing fluorine represented by the following formula (3) and a dihydroxyl monomer represented by the following formula (4) by a direct polymerization reaction: To prepare a, the copolymer represented by the following formula (5) is dissolved in a polar solvent and then cast on a glass plate or teflon plate, the solvent is evaporated to remove, then converted to the sulfonic acid form, partially represented by the formula (1) To prepare a polymer electrolyte membrane composed of a sulfonated polyarylene ether copolymer having been introduced.

Scheme 1

(In the above, Y, Z, p, n, m, k and X are as defined above.)

The properties of the polymer electrolyte membrane of the present invention are determined according to the molar ratio of the sulfonated aromatic monomer, the fluorine-containing monomer and the dihydroxyl monomer, and in particular, the ionic conductivity of the electrolyte membrane is determined in proportion to the degree of sulfonation. Therefore, the sulfonation degree of the sulfonated polyarylene ether copolymer of the present invention is preferably 40 to 50 mol%. When the sulfonation degree is less than 40 mol%, the sulfonation degree of the copolymer of Chemical Formula 1 is not sufficient, and thus the ion conductivity is low, and thus the function as an electrolyte membrane is poor. There is a problem that the increase in water absorption and methanol permeability increases.

Furthermore, the sulfonation degree of the sulfonated polyarylene ether copolymer is 40 to 50 mol% of the sulfonated aromatic monomer represented by Formula 2 and 50 to 60 mol% of the monomer containing fluorine represented by Formula 3 100 parts by weight of the dihydroxyl group monomer represented by Formula 4 with respect to 100 parts by weight of the copolymer formed.

In this case, the polar solvent is preferably any one selected from the group consisting of 1-methyl-2-pyrrolidinone, N, N-dimethylacetamide and dimethylformamide, but is not limited thereto.

In addition, the intrinsic viscosity measured on 1-methyl-2-pyrrolidinone (NMP) of the copolymer represented by Formula 5 is 0.1 or more, more preferably 0.8 or more, even more preferably 0.8 to 10 in consideration of ionic conductivity. 1.6. If the viscosity is less than 0.8, the mechanical strength of the electrolyte membrane prepared therefrom is significantly reduced, which is not preferable. In this case, the viscosity is measured at 25 ℃, which is precisely controlled by adjusting the reaction environment, such as the reaction temperature, the reaction time and the sulfonated monomer content of the copolymer.

The thickness of the polymer electrolyte membrane is preferably as thin as possible in consideration of ion conductivity, but in order to apply it as an electrolyte membrane, it is recommended that it be in the range of 1 to 1000 μm, preferably 30 to 200 μm. At this time, when the membrane thickness is less than 1 μm, the strength of the membrane is significantly reduced, and application to the electrolyte membrane is difficult, and when it exceeds 1000 μm, protons (H ⁺ ), which are ion carriers, or hydrates thereof and methanol fuel are difficult to pass. In addition, since the volume per unit performance of the fuel cell stack is increased, application to a high performance fuel cell is difficult, which is not preferable.

More specifically, the copolymer represented by the formula (5) is used in the preparation of the electrolyte membrane in the form of a salt, the copolymer represented by the formula (5) is K ₂ CO ₃ base and 1-methyl-2-pyrrolidinone (NMP ), N, N-dimethylacetamide (DMAc) or dimethylformamide (DMF) in a polar solvent selected from a cosolvent selected from toluene or benzene at 150 to 170 ℃ for 10 to 15 hours, the polymer After casting to a support, the solvent is evaporated to remove, and then converted to sulfonic acid form at room temperature or high temperature (100 ℃) using sulfuric acid or the like to obtain an electrolyte membrane. The removal of the solvent is preferably carried out by drying in view of the uniformity of the membrane, and is preferably dried at a temperature as low as possible under reduced pressure to avoid decomposition and deterioration of the solvent. Moreover, the method of leaving it to stand in air or inert gas for a suitable time can also be used.

Furthermore, the present invention provides a membrane-electrode assembly for a polymer electrolyte fuel cell including the polymer electrolyte membrane and a polymer electrolyte fuel cell employing the membrane-electrode assembly. When the membrane-electrode assembly is manufactured using the polymer electrolyte membrane of the present invention, the adhesion to the electrode is improved, and thus, when the membrane-electrode assembly is applied to the polymer electrolyte fuel cell, the performance of a unit cell is improved. . This is equivalent to or better than that of commercially available polymer membranes, and therefore can replace conventional electrolyte membranes and can be readily applied as polymer electrolyte membranes for polymer electrolyte fuel cells.

Furthermore, the present invention provides a sulfonated polyarylene ether copolymer for producing a polymer electrolyte membrane partially containing fluorine represented by the following formula (1).

Formula 1

(In the above, Y, Z, p, n, m and k are as defined above.).

Wherein p is 1 to 6, n + m = k, and n / (n + m) satisfies 0.1 to 0.99, the basis of which is the same as described above.

Hereinafter, the present invention will be described in detail by way of examples.

The following examples are merely illustrative of the present invention, but the scope of the present invention is not limited to the following examples.

< Example  1 and 2> partially containing fluorine Sulfonation Polyarylene ether  Preparation of Copolymer

Step 1 : Monomers for producing copolymers [1,6- Vis (4- Fluorophenyl )- Perfluorohexane ]Produce

A 300 ml four-necked round bottom flask was equipped with a mechanical stirrer, a nitrogen injector (N ₂ inlet), a condenser and a thermometer, 24.0498 g (108.34 mmol) 1-fluoro-4-iodobenzene, dodecafluor-1,6-diode 30.0000 g (54.17 mmol) of hexane and 15.4913 g (243.77 mmol) of copper catalysts were dissolved in 150 ml of DMSO, followed by Ullmann Coupling reaction at 120 ° C. for 48 hours, followed by purification under reduced pressure. bp: 128 ° C., 4 mmHg) to prepare 1,6-bis (4-fluorophenyl) -perfluorohexane in a yield of 76.5%.

¹ H-NMR analysis of 1,6-bis (4-fluorophenyl) -perfluorohexane (FPPFH) is shown in FIG. 1.

Step 2 : Copolymer Preparation for Polymer Electrolyte Membrane

A 100 ml four-necked round bottom flask was equipped with a mechanical stirrer, a nitrogen injector (N ₂ inlet), a Dean-Stark trap, a condenser and a thermometer, and as a dihydroxyl monomer, 6F-bisphenol A (hereinafter, 4.2365 g (12.60 mmol) of “6F-BPA”) 3.7061 g (7.56 mmol) of 1,6-bis (4-fluorophenyl) -perfluorohexane (hereinafter referred to as “FPPFH”) prepared in Step 1 ), 3,3′-disulfonated-4,4-difluorodiphenylsulfone (hereinafter referred to as “SDFDPS”) 2.3101 g (5.04 mmol), K ₂ CO ₃ 1.9156 g (13.86 mmol) and 40 ml of 1-methyl-2-pyrrolidinone (NMP) and 20 ml of toluene (NMP / toluene = 2/1, v / v) were added as a cosolvent, and the temperature was raised to 150 ° C. for 2 hours. After the toluene was refluxed for 4 hours to remove water as a reaction product, the toluene was removed, the temperature was raised to 170 ° C, and reacted by direct polymerization for 12 hours to synthesize a polymer. At this time, the molar ratio of FPPFH and SDFDPS was synthesized to be 60:40. After the reaction was completed, the reaction mixture was cooled to room temperature, precipitated in water, and the reactants were pulverized and filtered. Thereafter, the obtained reaction product was dried in a vacuum oven at 120 ° C. for 24 hours to obtain a partially fluorine-containing sulfonated polyarylethersulfone (F-SPAES-40) as a copolymer for preparing a polymer electrolyte membrane in 98% yield.

Of the above monomers, the ratio of 6F-bisphenol A (6F-BPA) :( FPPFH + SDFDPS) was fixed at 50:50, and again, 1,6-bis (4-fluorophenyl) -perfluorohexane (FPPFH) was used. Partially fluorine-containing sulfonated polyarylethersulfones for the preparation of electrolyte membranes by adjusting the dosage of 3,3′-disulfonated-4,4-difluorodiphenylsulfone (SDFDPS) to 40 and 50 mol% Copolymers (F-SPAES-40 and 50) were prepared. The properties of the copolymer according to the mixing ratio in the preparation are shown in Table 1 below, prepared in Examples 1 to 2 Results of ¹ H NMR, ¹⁹ F NMR and FT-IR analysis of partially fluorinated sulfonated polyarylether copolymers are shown in FIGS. 2A, 2B and 2C.

Sulfonated Polyarylene Ether Copolymer Containing Partially Fluorine division Monomer Mixing Ratio Yield (%) Sulfonation degree (%) Intrinsic Viscosity (dL / g) 6F-BPA FPPFH SDFDPS Example 1 F-SPAES-40 100 60 40 98 39.5 0.91 Example 2 F-SPAES-50 100 50 50 98 46.8 0.90 6F-BPA: 6F-bisphenol A FPPFH: 1,6-bis (4-fluorophenyl) -perfluorohexane SDFDPS: 3,3`-disulfonated-4,4-difluorodiphenylsulfone

< Example  3 and 4> Preparation of Polymer Electrolyte Membrane

The partially fluorine-containing copolymers prepared in Examples 1 and 2 above were dissolved in 1-methyl-2-pyrrolidinone (NMP), filtered using a 5.0 μm polytetrafluoroethylene separator filter, and then cleaned. Casting on the plate glass, the solvent used in the casting solution was dried in a reduced pressure oven below 50 ℃. The prepared electrolyte membrane was acid treated with 0.5MH ₂ SO ₄ at 100 ° C. for 2 hours, thereby preparing a sulfonated polyarylethersulfone polymer electrolyte membrane partially containing fluorine. At this time, the thickness of the final film was set to 70 to 150㎛.

The physical property evaluation results of the polymer electrolyte membrane using the sulfonated polyarylethersulfone copolymer containing partially fluorine prepared above are shown in Table 2 below.

Characteristics of Polymer Electrolyte Membrane Using Partially Fluorinated Sulfonated Polyarylene Ether Copolymer division Film thickness (㎛) Water absorption rate (%) Ionic Conductivity (S / cm, 30 ℃) Methanol Permeability (cm ² / s, 30 ℃) Example 3 70 32 0.099 1.07 × 10 ^-6 Example 4 144 88 0.124 1.61 × 10 ^-6

As shown in Table 2, the polymer electrolyte membranes of Examples 3 and 4 maintained high ionic conductivity, and confirmed low water absorption and low methanol permeability.

< Comparative example  1>

The polymer electrolyte fuel cell was used as the polymer electrolyte membrane of Nafion (Nafion-117 ^®) electrolyte membrane which is commercially available as. In this case, a Nafion (Nafion-117 ^®) is a thickness of the electrolyte membrane 180 ㎛, were stored in deionized water until embodiment after treatment at 100 ℃ 0.5 M sulfuric acid for 4 hours.

The Nafion (Nafion-117 ^®) electrolyte membrane property evaluation results are shown in Fig.

< Comparative example  2 and 3> Sulfonation Polyarylene ether  Preparation of Electrolyte Membrane

In preparing a copolymer for preparing a polymer electrolyte membrane, the molar ratio for FPPFH and SDFDPS was fixed in the same manner as in Example 1, but instead of 6F-bisphenol A (6F-BPA), which is the dihydroxyl monomer used in Example 1 Using biphenol, a sulfonated polyaryl ether copolymer (SPAES-40 and 50) for preparing a polymer electrolyte membrane was prepared.

< Experimental Example  1> Physical property measurement

1. Water absorption rate measurement

For the polymer electrolyte membrane, the acid-treated membrane was washed several times with deionized water to measure water absorption, and then immersed in distilled water purified at room temperature for 24 hours and then taken out to remove water from the surface and weighed (W _wet ). The membrane is then dried in a reduced pressure dryer at 120 ° C. for 24 hours and then weighed (W _dry ). The water content was calculated by the above equation (1).

2. Methanol Permeability Measurement

For the polymer electrolyte membrane, the phases of two vessels in constant concentration of methanol and water

After the polymer electrolyte membranes prepared in Examples and Comparative Examples were mounted in the arc connecting passage in a direction perpendicular to the fluid flow, gas chromatography (GC) was used at an operating temperature of 30 ° C., and the amount of methanol permeated over time was measured. It measured and computed by following formula (2).

In the above, a is the slope in the time-concentration graph, V _B is the volume of methanol permeated (cm ³ ), L is the thickness of the electrolyte membrane (cm), A is the area of the electrolyte membrane (cm ² ), C _A is The concentration of methanol used is shown.

3. Ionic Conductivity Measurement

About the polymer electrolyte membrane of the said Example 1, 2 and the comparative example 3, the ion conductivity in the measurement temperature range 30-80 degreeC was measured.

Ionic conductivity was measured using a Solartron analyzer (Solartron 1260 Impedance / Gain-Phase analyzer), the impedance spectrum (impedance spectrum) was recorded from 10MHz to 10Hz, it was calculated by the following equation (3).

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

Figure 3 shows the ionic conductivity of the polymer electrolyte membrane of the present invention and the commercially available Nafion-117 ^® electrolyte membrane, the polymer electrolyte membrane prepared in Example 4 is relatively higher than the commercial electrolyte membrane of Comparative Example 1 Ionic conductivity was shown.

4 and 5 for the polymer electrolyte membrane prepared from Nafion (Nafion-117 ^®) electrolyte membrane and Comparative Examples 2 and 3 of the polymer electrolyte membrane of Comparative Example 1 prepared in Examples 3 and 4 of the present invention, Methanol permeability and water absorption rate are shown. The polymer electrolyte membranes prepared in Examples 3 and 4 showed lower methanol permeability and lower water absorption than Comparative Examples 2 and 3 containing no fluorine. Also showed the polymer electrolyte of Example 3 film is low in methanol, and low water absorption than the commercial Nafion (Nafion-117 ^®) electrolyte membrane.

Accordingly, it was confirmed that the physical properties of the polymer electrolyte membrane were improved by partially introducing fluorine into the conventional sulfonated polyarylene ether copolymer.

6 is a unit cell performance evaluation in respect to that of Nafion (Nafion-117 ^®) electrolyte membrane which is commercially available sulfonated polyarylene ether polymer electrolyte membrane and containing fluorine as according to the present invention in part, the same environment (single cell performance test ) Is the result. As a result, the polymer electrolyte membrane prepared by the present invention was excellent in battery performance in terms of current density and power density. Also, when I compared to the Nafion (Nafion-117 ^®) electrolyte membrane is used, equal or by identifying the more excellent properties, expensive Nafion (Nafion-117 ^®) electrolyte replacement may be prevented, and directly employing him methanol fuel cell Can improve the characteristics.

As a result, the present invention provides a polymer electrolyte membrane containing an ion conductive copolymer partially introduced with fluorine, a method for preparing the same, a polymer electrolyte fuel cell employing a polymer electrolyte membrane, and a polymer electrolyte membrane partially containing fluorine. A preparative copolymer was provided. The partially fluorine-containing sulfonated polyarylene ether polymer electrolyte membrane has a low water absorption rate and low methanol permeability while having ionic conductivity comparable to or superior to that of a commercial Nafion-117 ^® electrolyte membrane. It can be used to replace the polymer electrolyte membrane used, it is possible to improve the performance of the polymer electrolyte fuel cell having a polymer electrolyte membrane with 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.

1 shows the ¹ H NMR analysis of the 1,6-bis (4-fluorophenyl) -perfluorohexane monomer prepared in Example 1 of the present invention,

Figure 2a is a ¹ H NMR analysis of the partially fluorinated sulfonated polyarylene ether copolymer (F-SPAES) prepared in Example 1 of the present invention,

Figure 2b is a ¹⁹ F NMR analysis of the partially fluorinated sulfonated polyarylene ether copolymer (F-SPAES) prepared in Example 1 of the present invention,

Figure 2c shows the results of the FT-IR analysis of the partially fluorinated sulfonated polyarylene ether copolymer (F-SPAES-40 and 50) prepared in Example 1 of the present invention,

Figure 3 is a measure of the ionic conductivity of the polymer electrolyte membrane of the present invention and a commercially available Nafion-117 ^® membrane,

Figure 4 shows the methanol permeability of the polymer electrolyte membrane of the present invention and the commercially available Nafion-117 ^® membrane,

Figure 5 shows the water absorption rate of the polymer electrolyte membrane and Nafion-117 ( ^TM ) membrane of the present invention,

Figure 6 shows the results of the unit cell performance evaluation of the polymer electrolyte membrane and the Nafion-117 (Nafion-117 ^® ) membrane of the present invention.

Claims (11)

A polymer electrolyte membrane comprising a sulfonated polyarylene ether copolymer partially introduced with fluorine represented by the following formula (1). Formula 1

Wherein Y is any one selected from the group consisting of -S-, -SO ₂ -and -C = O- or a combination thereof, and Z is a bond, -O-, -SO ₂ -, -C = O-, -C (CH ₃ ) ₂ -and -C (CF ₃ ) _2- , any one selected from p, p is 1 to 6, n + m = k, and n / (n + m) is 0.1 to 0.99) The polymer electrolyte membrane of Claim 1, wherein n / (n + m) is 0.4 to 0.5. a) a sulfonated aromatic monomer represented by the following formula (2), a fluorine-containing monomer represented by the following formula (3) and a dihydroxyl monomer represented by the following formula (4) by a direct polymerization reaction, Preparing a copolymer, b) Partially fluorine represented by the following formula (1) is obtained by dissolving the copolymer represented by the following formula (5) in a polar solvent and casting it on a glass plate or a teflon plate, evaporating the solvent to remove it, and then converting it into a sulfonic acid form. A method for producing a polymer electrolyte membrane composed of a sulfonated polyarylene ether copolymer introduced. Scheme 1

(In the above, Y, Z, p, n, m and k are as defined in claim 1, X is a halogen atom or a nitro group containing F, Cl, Br as leaving group.) The method of claim 3, wherein the sulfonation degree of sulfonation of the sulfonated polyarylene ether copolymer is 40 to 50 mol%. According to claim 4, The sulfonated degree of sulfonated polyarylene ether copolymer 40 to 50 mol% sulfonated aromatic monomer represented by the formula (2) and 50 to 50 monomers containing fluorine represented by the formula (3) A method for producing the polymer electrolyte membrane, characterized in that it is determined by reacting with 100 parts by weight of the dihydroxyl monomer represented by Formula 4 with respect to 100 parts by weight of the copolymer consisting of 60 mol%. The method of claim 3, wherein the polar solvent is any one selected from the group consisting of 1-methyl-2-pyrrolidinone, N, N-dimethylacetamide and dimethylformamide. . The method according to claim 3, wherein the copolymer represented by Chemical Formula 5 has an intrinsic viscosity of 0.8 or more on an N-methyl-2-pyrrolidinone solvent. The method of claim 3, wherein the polymer electrolyte membrane has a thickness of 1 to 1000 μm. A membrane-electrode assembly for a polymer electrolyte fuel cell, comprising the polymer electrolyte membrane of claim 1. A polymer electrolyte fuel cell employing the membrane-electrode assembly of claim 9. A sulfonated polyarylene ether copolymer for producing a polymer electrolyte membrane, which partially contains fluorine represented by the following formula (1). Formula 1

(In the above, Y, Z, p, n, m and k are as defined in claim 1).

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