KR100750290B1 - Synchronous crosslinking-imidized polyelectrolyte membranes having an interpenetrating polymer network structure for fuel cell and method for preparation the same - Google Patents

Abstract

Provided are a polymer electrolyte membrane for a fuel cell which is excellent in proton transfer property and is low in penetration in case of the use of hydrogen, methanol and dimethyl ether, and a method for preparing the polymer electrolyte membrane. A polymer electrolyte membrane comprises a polymer (1) having a repeating unit represented by a formula 1, and a polymer (2) having a repeating unit represented by a formula 2 or a specific other polymer which are simultaneously crosslinked-imidated into a form of interpenetrating polymer network structure, wherein A1 and A2 are a polymerizable monomer having at least one double bond; n and m are 0.001-1 mol; n/m is 0.3-0.7; and the aromatic group containing Ar is a divalent aromatic cyclic group having at least one sulfonic acid group.

Description

Synchronous crosslinking-imidized polyelectrolyte membranes having an interpenetrating polymer network structure for fuel cell and method for preparation the same}

1 is a cross-linked-imide polyelectrolyte membrane prepared in Examples 1 and 3 of the present invention, wherein (a) the interpenetrating net structure of Examples 1 and 2 (b) the interpenetration of Example 3 It shows the net structure.

2 is a graph showing hydrogen ion conductivity values according to the temperatures of Examples 1 to 3 of the present invention and Nafion (Comparative Example 1) which are commercial membranes.

3 is a graph illustrating methanol permeability values according to the temperatures of Examples 1 to 3 of the present invention and Nafion (Comparative Example 1) which are commercial membranes.

4 is a graph showing dimethyl ether permeability values according to the temperatures of Examples 1 to 3 of the present invention and Nafion (Comparative Example 1) which are commercial membranes.

The present invention relates to a simultaneous cross-linked-imide polymer electrolyte membrane for a fuel cell having an interpenetrating polymer network structure and a method for preparing the same, and more specifically, to a polya copolymer obtained by copolymerizing a maleic acid monomer and a polymerizable monomer including at least one double bond. Simultaneous crosslinking and imidization process to polymerize mic acid and to imidize the polyamic acid alone or a specific polymer with aromatic diamine, form interpenetrating polymer networks to form high temperature characteristics and excellent proton transfer function, The present invention relates to a simultaneous cross-linked-imide polymer electrolyte membrane for fuel cells and a method for producing the same, which exhibit low permeability when using hydrogen, methanol, dimethyl ether, and the like.

The electrolyte membranes for fuel cells are currently available under the trade name Nafion ™ from Dupont, ASIPLEX-S from Asahi Chemicals, Dow from Dow Chemicals Although many copolymers having sulfonic acid groups are used in the perfluorinated polymer backbone, such as Asahi Glass's Flemion, the fuel is expensive due to its high price and permeability to fuel gas and liquid (methanol). There are drawbacks such as reduced utilization and deterioration of driving performance, and new types of electrolyte materials or manufacturing methods have been studied.

Among these new types of materials and methods, as in U.S. Pat.Nos. 5,547,551, 5,599,614, 5,635,041 and 6,130,175, a method for preparing an impregnated ion conductive polymer in a porous polytetrafluoroethylene (PTFE) film and In the form of filling different ion conductive polymers on both sides of porous polytetrafluoroethylene (PTFE) film, methods for improving ion conductivity and mechanical properties have been disclosed. The present invention discloses a method for preparing a porous polybenzimidazole (PBI) electrolyte membrane obtained by coating polyimide (PI) on polybenzimidazole (PBI) to prepare a film, and then dissolving and extracting polyimide (PI). In European Patent No. 0,094,679 (Asahi Glass Co. Ltd.), a fluorine-based ion conductive polymer and a polytetrafluoroethylene microfiber are mixed and stretched. Methods of making reinforced composite membranes are disclosed.

In addition, polyphosphogen [WO 00/77874], polyether sulfone [Japanese Patent Laid-Open Nos. 11-116679 and 11-67224], polyether ether ketone and poly (4-phenoxybenzoyl-1,4-phenylene After sulfonating a polymer such as), methods for preparing an electrolyte film by adding an organic or inorganic ion conductor have been proposed as an efficiency in reducing the crossover phenomenon of fuel gas or liquid and a method for reducing the film manufacturing cost. .

However, in the case of the manufacturing method using a porous PTFE film among these, due to the hydrophobic polytetrafluoroethylene film, the ion conductive polymer has to be impregnated repeatedly, and because the micro-pores (pin-hole) is easily formed during the manufacturing process, the interface Due to the washing process accompanied by the use of the active agent, the film manufacturing time is relatively long, and the price of the porous polytetrafluoroethylene is expensive, so it has a disadvantage that the price is not competitive compared to fluorine-based polymers such as Nafion.

In addition, in the case of the additives of the organic and inorganic forms proposed as a method for maintaining the conductivity of the electrolyte film, the problem is extracted by the transfer of moisture during the operation of the battery when the water-soluble material, and dispersed in a non-uniform form when the water-insoluble material This results in brittleness and physical problems of the film.

On the other hand, in the case of non-fluorine-based polymer electrolyte film production, because the ion conductivity is proportional to the degree of sulfonation, sulfonation above the critical concentration shows disadvantages such as lower molecular weight and decrease of mechanical properties due to hydration. Electrolyte films have been prepared by sulfonation methods (US Pat. Nos. 5,585,74,567,941,61,106,16,624,581). However, this method does not completely solve the problems caused by high temperature stability and long-term use.

Therefore, there is an urgent need for a method of preparing a new type of polymer electrolyte membrane, which has excellent electrochemical properties and excellent high temperature stability and is easy to manufacture into a thin film.

Accordingly, the present inventors have tried to prepare a non-fluorine-type proton conductive polymer membrane having excellent high temperature stability and mechanical properties such as groups, low permeability to fuels such as methanol and dimethyl ether, and easy to manufacture. As a result, the polymer electrolyte membrane containing a specific compound having both crosslinking and imide bonds through interpenetration process has high temperature characteristics and excellent proton transfer function, and has low permeability when using fuels such as toil, methanol and dimethyl ether. It was found that the present invention was completed to complete the present invention.

Accordingly, an object of the present invention is to provide a polymer electrolyte membrane for a fuel cell comprising a specific compound having a structure that is simultaneously crosslinked and imidized by interpenetration, and a method for producing the same.

The present invention is a polymer (1) having a repeating unit of the following formula (1),

The polymer (2) or polyvinyl difluoride, sulfonated polyvinyl difluoride, aminated polyvinyl difluoride, carboxylated polyvinyl difluoride, imidazole, Polyvinyldifluoride, polysulfone, sulfonated polysulfone, aminated polysulfone, carboxylated polysulfone, imidazole polysulfone, polyethersulfone, sulfonated polyethersulfone, aminated Polyethersulfones, carboxylated polyethersulfones, imidazoleated polyethersulfones, polyimides, sulfonated polyimides, aminated polyimides, carboxylated polyimides, imidazoleated polyimides, poly Etherimides, sulfonated polyetherimides, aminated polyetherimides, carboxylated polyetherimides, imidazoleated polyetherimides, polyketones, sulfonated polyketones, aminated Lyketone, carboxylated polyketone, imidazole polyketone, polyether ketone, sulfonated polyether ketone, aminated polyether ketone, carboxylated polyether ketone, imidazole polyether ketone , Polymer compounds selected from polyvinylsulfonic acid, polyacrylic acid, polyimidazole, polybenzimidazole and perfluorinated polymer

It is characterized by the simultaneous crosslinking-imide-bonded polymer electrolyte membrane in the form of an interpenetrating network structure.

In Chemical Formulas 1 and 2,

The A ₁ and A ₂ is a polymerizable monomer containing one or more double bonds, specifically, 1 to 8 carbon atoms such as styrene or methylene, ethylene, propylene, isopropylene, butylene, t-butylene and isobutylene. Linear or ground alkylene, methyl vinyl ether, partially 2-butyl / methyl mixed ester styrene, partially isobutyl ester styrene, partially isobutyl / methyl mixed ester styrene and sulfonic acid styrene;

은 술폰산기를 1개 이상 갖는 방향족 2가 고리기, 구체적으로

, ,

,

,

,

,

,

,

,

중에서 선택된 술폰산기가 1개 이상 갖는 방향족 2가기이고,

Is an aromatic divalent ring group having one or more sulfonic acid groups, specifically

,,

,

,

,

,

,

,

,

An aromatic divalent group having at least one sulfonic acid group selected from

n and m are 0.001-1 mol, and represent n / m 0.3-0.7 molar ratio.

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

The present invention is a co-crosslinking and imidization process of polymerizing a polyamic acid copolymerized with a maleic acid monomer and a polymerizable monomer including at least one double bond, and imidating the polyamic acid alone or a specific polymer compound with an aromatic diamine. By forming interpenetrating polymer networks, it has high temperature characteristics, excellent proton transfer function, and low permeability when using hydrogen, methanol, dimethyl ether, and the like.

1 is a diagram illustrating an electrolyte polymer membrane prepared in Examples 1 to 3 of the present invention. Specifically, FIG. 1 (a) is prepared using two kinds of polyamic acids in Examples 1 and 2. 1 (b) is a polymer electrolyte membrane manufactured using polyamic acid and polyvinyl difluoride. As shown in FIG. 1, the polymer electrolyte membrane of the present invention is cross-imide bonded in the form of mutual permeation net structure, and thus has excellent thermal stability, mechanical properties, stability against hydrolysis under acidic atmosphere, durability, and proton conductivity.

On the other hand, the polymer electrolyte membrane for a fuel cell according to the present invention is prepared by the following process.

Copolymerizing the maleic acid monomer and the polymerizable monomer including one or more double bonds to polymerize the polyamic acid represented by the following Formula 3;

In Chemical Formula 3, A ₁ , n and m are as defined in claim 1, respectively,

Polyamic acid represented by the formula (3), and polyvinyl difluoride, sulfonated polyvinyl difluoride, aminated polyvinyl difluoride, carboxylated polyvinyl difluoride, imidazole polyvinyl Difluoride, polysulfone, sulfonated polysulfone, aminated polysulfone, carboxylated polysulfone, imidazole polysulfone, polyethersulfone, sulfonated polyethersulfone, aminated polyethersulfone , Carboxylated polyethersulfone, imidazoleated polyethersulfone, polyimide, sulfonated polyimide, aminated polyimide, carboxylated polyimide, imidazole polyimide, polyetherimide, Sulfonated polyetherimide, aminated polyetherimide, carboxylated polyetherimide, imidazoleated polyetherimide, polyketone, sulfonated polyketone, aminated polyke , Carboxylated polyketone, imidazole polyketone, polyether ketone, sulfonated polyether ketone, aminated polyether ketone, carboxylated polyether ketone, imidazole polyether ketone, poly Imidation of a polymer compound selected from vinylsulfonic acid, polyacrylic acid, polyimidazole, polybenzimidazole, and perfluorinated polymer and the aromatic diamine represented by the following formula (5)

A polymer electrolyte membrane in which a polymer (1) having a repeating unit of Formula 1 and a polymer (2) or a polymer compound having a repeating unit of Formula 2 is co-cross-imide-bonded in the form of an interpenetrating network structure is prepared.

은 각각 상기에서 정의된 바와 같다.In Chemical Formula 5,

Are each as defined above.

The polymer electrolyte membrane of the present invention forms a membrane using a solution-casting method. The solution-casting method is a conventional manufacturing method including a process of dissolving a constituent compound in an organic solvent, followed by casting and drying, and the polymer electrolyte membrane for a fuel cell of the present invention is also prepared by the solution-casting method. Since the reaction and film form are carried out simultaneously by the casting method, the manufacturing method is very easy, and after the polymer polymerization, which is involved in preparing the sulfonated polyimide membrane, the extraction-purification-drying process and the film forming step are unnecessary. Do.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Example 1

In 50 mL flask styrene-maleic anhydride polymer ^{2.065 g (1 × 10 -2 mol} ) and methyl vinyl ether-maleic anhydride polymer ^{1.5614 g (1 × 10 -2 mol} ) was completely dissolved in the solvent, dimethyl sulfoxide (DMSO), Both solutions were mixed-stirred at room temperature to produce a homogeneous interpenetrating polymer solution.

Also, 2.7236 g (5 × 10 ⁻³ mol) of 2,2-benzidine disulfonic acid-complex salt was completely dissolved in DMSO in the same flask, and reacted with the mixed polymer solution at room temperature to prepare an amic acid crosslinked polymer solution. Next, the reaction was carried out for 24 hours in a 60 ℃ vacuum oven well cast on a glass plate prepared in advance. After the reaction to completely remove the residual solvent, vacuum-drying at 80 ℃ for 24 hours to prepare a network sulfonic acid-complex salt cross-amic acid polymer film of 20 to 100 ㎛ thickness.

The prepared polymer film was imidized while increasing the temperature stepwise at 100 ° C. for 12 hours, 120 ° C. for 6 hours, 150 ° C. for 3 hours, 180 ° C. for 1 hour, and 240 ° C. for 30 minutes to prepare a brown polymer film.

Subsequently, the sulfonic acid-complex salt was converted into an acidic form using 1M sulfuric acid, and then washed several times with pure water to prepare a sulfonated crosslinked-imide polymer membrane having an interpenetrating network structure.

The prepared polymer electrolyte membrane for a fuel cell was confirmed to be a compound represented by Chemical Formula 1 based on an infrared spectroscopy analysis.

Example 2

The polymer electrolyte membrane was prepared in the same manner as in Example 1, using 1.5416 g (1 × 10 ⁻² mol) of isobutylene-maleic anhydride instead of the methyl vinyl ether-maleic anhydride polymer.

Example 3

The polymer electrolyte membrane was prepared in the same manner as in Example 1, using 0.64 g (1 × 10 ⁻² mol) of polyvinyl difluoride (PVDF) instead of the methyl vinyl ether-maleic anhydride polymer.

Comparative Example 1

Nafion 112, which is widely used as a polymer electrolyte membrane for a fuel cell, is set as Comparative Example 1.

Experimental Example 1: Hydrogen ion conductivity

Hydrogen ion conductivity according to the temperature of the polymer membrane obtained in Examples 1 to 3 and Comparative Example 1 was measured by the dipole method in the AC impedance measurement form and is shown in FIG. 2.

As can be seen in Figure 2 it can be seen that the excellent hydrogen ion conductivity of the polymer membrane according to the present invention.

Experimental Example 2 Fuel Crossover Measurement

The direct methanol crossover of the polymer membranes obtained in Examples 1 to 3 and Comparative Example 1 was used to check the concentration of the detection unit with a refractive index detector at regular intervals using a transmission cell composed of an electrolyte separator between the fuel supply unit and the detection unit. The concentration of methanol per unit time was measured and the results are shown in FIG. 3. It can be seen that it shows a very low methanol permeability compared to Nafion which is a commercial membrane of Comparative Example 1.

4 shows the dimethyl ether crossover results of the polymer membranes obtained in Examples 1, 2, 3 and Comparative Example 1. FIG. In the case of Nafion which is a commercial film, the crossover phenomenon gradually increases with temperature, but in the case of the present invention, it can be seen that there is no crossover phenomenon.

The co-crosslinked-imide polymer electrolyte membrane of the interpenetrating net structure according to the present invention has a lower manufacturing cost than a commercial membrane Nafion perfluorine membrane which exhibits the best performance of the prior art, and is prepared in comparison with the conventional sulfonated polyimide membrane. It is easy to use and has excellent thermal, mechanical and chemical stability and film durability because the net structure is constructed from the cross-imide structure. In addition, high hydrogen ion conductivity and very low methanol permeability are shown for fuels such as methanol and dimethyl ether even at high temperatures, so that application to a fuel cell polymer electrolyte membrane is sufficiently possible.

Since the co-crosslinking-imide polymer electrolyte membrane of the interpenetrating net structure according to the present invention is very easy to manufacture, mass production on an industrial scale is also easy.

Claims (4)

The polymer (1) having a repeating unit represented by Formula 1, The polymer (2) or polyvinyl difluoride, sulfonated polyvinyl difluoride, aminated polyvinyl difluoride, carboxylated polyvinyl difluoride, imidazole, Polyvinyldifluoride, polysulfone, sulfonated polysulfone, aminated polysulfone, carboxylated polysulfone, imidazole polysulfone, polyethersulfone, sulfonated polyethersulfone, aminated Polyethersulfones, carboxylated polyethersulfones, imidazoleated polyethersulfones, polyimides, sulfonated polyimides, aminated polyimides, carboxylated polyimides, imidazoleated polyimides, poly Etherimides, sulfonated polyetherimides, aminated polyetherimides, carboxylated polyetherimides, imidazoleated polyetherimides, polyketones, sulfonated polyketones, aminated Lyketone, carboxylated polyketone, imidazole polyketone, polyether ketone, sulfonated polyether ketone, aminated polyether ketone, carboxylated polyether ketone, imidazole polyether ketone , Polymer compounds selected from polyvinylsulfonic acid, polyacrylic acid, polyimidazole, polybenzimidazole and perfluorinated polymer Polymer electrolyte membrane, characterized in that the simultaneous cross-linked in the form of interpenetrating network structure: [Formula 1]

[Formula 2]

In Chemical Formulas 1 and 2, A ₁ and A ₂ are polymerizable monomers including one or more double bonds;

Is an aromatic divalent ring group having at least one sulfonic acid group; n and m are 0.001-1 mol, and represent n / m 0.3-0.7 molar ratio. The method of claim 1, A ₁ and A ₂ are styrene, linear or pulverized alkylene having 1 to 8 carbon atoms, methyl vinyl ether, partially 2-butyl / methyl mixed ester styrene, partially isobutyl ester styrene, partially isobutyl / methyl mixed ester styrene and Selected from sulfonic acid styrene, remind

silver

,

,

,

,

,

,

,

,

An aromatic divalent group having at least one sulfonic acid group selected from The high molecular compound is polyvinyldifluoride, sulfonated polyvinyldifluoride, aminated polyvinyldifluoride, carboxylated polyvinyldifluoride, imidazoleated polyvinyldifluoride, N and m are 0.001-1 mol, and represent n / m 0.3-0.7 molar ratio. The method of claim 1, The polymerizable monomer of A ₁ is styrene or linear or pulverized alkylene having 1 to 6 carbon atoms, remind

silver

,

,

An aromatic divalent group having at least one sulfonic acid group selected from The polymer compound is polyvinyl difluoride, N and m are 0.001-1 mol, and represent n / m 0.3-0.7 molar ratio. Method for producing a polymer electrolyte membrane, comprising the following manufacturing process: Copolymerizing the maleic acid monomer and the polymerizable monomer including one or more double bonds to polymerize the polyamic acid represented by the following Formula 3; [Formula 3]

In Chemical Formula 3, A ₁ , n and m are as defined in claim 1, respectively, Polyamic acid represented by the formula (3) and polyvinyl difluoride, sulfonated polyvinyl difluoride, aminated polyvinyl difluoride, carboxylated polyvinyl difloride, imidazole polyvinyl Difluoride, polysulfone, sulfonated polysulfone, aminated polysulfone, carboxylated polysulfone, imidazole polysulfone, polyethersulfone, sulfonated polyethersulfone, aminated polyethersulfone , Carboxylated polyethersulfone, imidazoleated polyethersulfone, polyimide, sulfonated polyimide, aminated polyimide, carboxylated polyimide, imidazole polyimide, polyetherimide, Sulfonated polyetherimide, aminated polyetherimide, carboxylated polyetherimide, imidazoleated polyetherimide, polyketone, sulfonated polyketone, aminated polyke , Carboxylated polyketone, imidazole polyketone, polyether ketone, sulfonated polyether ketone, aminated polyether ketone, carboxylated polyether ketone, imidazole polyether ketone, poly Imidation of a polymer compound selected from vinylsulfonic acid, polyacrylic acid, polyimidazole, polybenzimidazole, and perfluorinated polymer and the aromatic diamine represented by the following formula (5) Preparing a polymer electrolyte membrane in which a polymer (1) having a repeating unit of Formula 1 and a polymer (2) or a polymer compound having a repeating unit of the following Formula 2 are simultaneously cross-imide-bonded in an interpenetrating network structure; [Formula 5]

 [Formula 1]

[Formula 2]

In Formulas 1, 2 and 5, A ₁ , A ₂

, n and m are as defined in claim 1, respectively.

Images