WO2023085592A1 - Fluorene- and biphenyl-based branched copolymer polymer electrolyte membrane and water electrolysis system using same - Google Patents

Abstract

The present invention relates to a fluorine- and biphenyl-based branched copolymer polymer electrolyte membrane that is chemically stable because a polymer main chain thereof is composed of carbon single bonds, and has high hydrogen ion conductivity due to a cation exchange functional group introduced at the end of a carbon branch, and to a water electrolysis device and a fuel cell using same.

Description

Fluorene and biphenyl-based branched copolymer polymer electrolyte membrane and water electrolysis system using the same

The present invention relates to a fluorene- and biphenyl-based branched copolymer polymer electrolyte membrane having high hydrogen ion conductivity with a cation exchange functional group introduced at the end of a carbon branch and a chemically stable polymer main chain composed of carbon single bonds, and water electrolysis using the same. It's about the system.

Cation Exchange Membrane (CEM), a core material used in various energy conversion and storage devices including water electrolysis systems, serves as an electrolyte and separation membrane to selectively transfer only positive ions. Therefore, CEM has 1) high ion conductivity, 2) outstanding physicochemical stability, 3) easy to scalable, and 4) low cost for production. characteristics are required.

Currently, the most widely used CEMs are DuPont's perfluorine-based electrolyte Nafion® and Gore's perfluorine-based porous filled structural membrane Gore-Select®, both of which have high ionic conductivity and chemical stability. Therefore, it is used in most commercial or pilot fuel cells, oxidation/reduction flow cells, and electrochemical hydrogen compressor systems, but all existing perfluorinated CEMs have 1) decomposition problems due to oxygen radicals, 2) problems in the incineration process. Environmental pollution caused by hydrofluoric acid and pollutants and 3) high unit cost due to complex manufacturing processes act as obstacles to the spread of eco-friendly and high-efficiency low-cost energy conversion and storage systems.

It is required to develop a non-perfluorocarbon-based branched polymer electrolyte membrane that has excellent ionic conductivity and mechanical strength and can be easily used as a membrane electrode assembly for polymer electrolyte membrane water electrolysis.

In order to develop an electrolyte membrane that satisfies all the above-described requirements for manufacturing additives for hydrogen ion exchange membranes and can be applied in water electrolysis systems, 1) introduction of ion exchange functional groups is easy, and 2) carbon-carbon with excellent chemical stability is required. It has a branched side chain composed of bonds, 3) free volume between polymer chains increases due to radical stable fluorene, which lowers crystallinity and increases solubility, 4) can withstand high temperature and high pressure. Excellent physical stability is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a polymer electrolyte membrane for water electrolysis, which has excellent hydrogen ion conductivity and mechanical properties, and operates under high temperature and pressurized conditions.

In addition, the present invention is to provide a polymer electrolyte membrane for water electrolysis that can solve the problem of decomposition of oxygen radicals and environmental pollution caused by incineration of hydrofluoric acid, which are problems of the perfluorine-based electrolyte membrane for water electrolysis.

In addition, the present invention provides a polymer electrolyte membrane for water electrolysis having a branched side chain composed of carbon single bonds with easy introduction of ion exchange functional groups and excellent chemical stability.

In addition, the present invention is to provide a polymer electrolyte membrane for water electrolysis that is stable to radicals and has low crystallinity and increased solubility due to an increase in free volume between polymer chains.

The technical problems to be solved by the invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below. You will be able to.

The polymer electrolyte membrane of the present invention is characterized by including a polymer having a repeating unit represented by the following [Formula 1].

[Formula 1]

(Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).

The polymer electrolyte membrane including the polymer having the repeating unit of [Formula 1] has a tensile strength of 30 MPa or more and an elongation of 50% or more.

The polymer electrolyte membrane including the polymer having the repeating unit of [Formula 1] is characterized in that the ion conductivity is 50 to 350 mS/cm under running conditions in water.

The polymer electrolyte membrane including the polymer having the repeating unit of [Formula 1] is characterized in that the ion exchange capacity (IEC) is 2.0 to 5.0 meq / g.

The method for manufacturing a polymer electrolyte membrane of the present invention,

9,9-Dimethylfluorene, Biphenyl and 7-Bromo-1,1,1-trifluoroheptan-2-one (7-Bromo-1,1,1 A first step of preparing a fluorene-biphenyl-based polymer by reacting -trifluoroheptan-2-one);

A second step of preparing a fluorene-biphenyl-based polymer to which thioacetic acid is bonded by reacting the fluorene-biphenyl-based polymer prepared in the first step with potassium thioacetate; and

After mixing the thioacetic acid-coupled fluorene-biphenyl-based polymer prepared in the second step with a mixed solution of formic acid and distilled water, hydrogen peroxide is slowly added to prepare a fluorene-biphenyl-based ionomer It is characterized in that it includes; a third step to do.

The water electrolysis device of the present invention is characterized in that it includes a polymer electrolyte membrane including a polymer having a repeating unit represented by the following [Chemical Formula 1].

[Formula 1]

(Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).

The fuel cell of the present invention is characterized in that it includes a polymer electrolyte membrane including a polymer having a repeating unit of [Formula 1] below.

[Formula 1]

(Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).

By means of solving the above problems, the present invention uses an electrophilic substitution reaction under strong acid conditions, rather than developing a cation exchange material through condensation polymerization under a conventional basic catalyst, so that there is no chemically weak bond in the polymer backbone, so that it can be chemically It has a stabilizing effect.

In addition, the present invention can manufacture a chemically stable polymer electrolyte membrane composed of fluorene that is stable to radicals and a water electrolysis system using the same.

In addition, according to the present invention, a polymer electrolyte membrane having excellent chemical stability and a water electrolysis system using the polymer electrolyte membrane having an entire polymer main chain composed of only carbon single bonds can be manufactured.

In addition, the present invention is a branched copolymer polymer in which a cation exchange functional group is introduced at the end of a side chain, and a molecular electrolyte membrane that simultaneously improves ion conduction behavior and physicochemical stability due to a distinct hydrophilic or hydrophobic phase separation effect and a water electrolysis system using the same can be manufactured

In addition, since the present invention is obtained through condensation polymerization at room temperature under an acid catalyst, a molecular electrolyte membrane that can be easily mass-produced and a water electrolysis system using the same can be manufactured.

1 is an F1B-SA-10 polymer electrolyte membrane (a) and an F1B-SA-30 polymer electrolyte membrane (b) according to an embodiment of the present invention.

2 is ^{a 1} H-NMR analysis result of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30 according to an embodiment of the present invention.

3 is an FT-IR analysis result of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30 according to an embodiment of the present invention.

4 is a TGA analysis result of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30 according to an embodiment of the present invention.

5 is a chemical structure of a conventional hydrocarbon-based electrolyte membrane (SPAES-50, SPAES-65) and an F1B-SA-n polymer electrolyte membrane according to an embodiment of the present invention.

6 is a chemical durability test result of F1B-SA-10 and F1B-SA-30 polymer electrolyte membranes according to an embodiment of the present invention.

7 is a water absorption and dimensional change test results at 30 ° C. of F1B-SA-10 and F1B-SA-30 polymer electrolyte membranes according to an embodiment of the present invention.

8 is a test result of water absorption and dimensional change at 80 ° C. of F1B-SA-10 and F1B-SA-30 polymer electrolyte membranes according to an embodiment of the present invention.

9 is an evaluation result of mechanical properties (strain-stress) of F1B-SA-10 and F1B-SA-30 polymer electrolyte membranes according to an embodiment of the present invention.

10 is an evaluation result of proton conductivity of F1B-SA-10 and F1B-SA-30 polymer electrolyte membranes according to an embodiment of the present invention.

The terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected from general terms that are currently widely used as much as possible while considering the functions in the present invention, but these may vary depending on the intention of a person skilled in the art or precedent, the emergence of new technologies, and the like. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, not simply the name of the term.

In the entire specification, when a part is said to "include" a certain component, it means that it may further include other components, not excluding other components unless otherwise stated.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The specific details, including the problem to be solved, the means for solving the problem, and the effect of the invention with respect to the present invention are included in the embodiments and drawings to be described below. Advantages and features of the present invention, and methods for achieving them, will become clear with reference to the embodiments described below in detail in conjunction with the accompanying drawings.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The fluorene- and biphenyl-based branched copolymer polymer electrolyte membrane of the present invention is characterized in that it includes a polymer having a repeating unit represented by the following [Formula 1].

[Formula 1]

(Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).

In the polymer electrolyte membrane according to an embodiment of the present invention, a chemically weak bond such as an ether bond is formed in a polymer backbone by using an electrophilic substitution reaction under strong acid conditions, rather than developing a cation exchange material through condensation polymerization under a conventional basic catalyst. designed so that there is no In addition, a cation exchange membrane with a fine phase separation structure was developed by synthesizing a polymer precursor with a branched structure in which various ion exchange functional groups can be introduced only to the side chain end of the polymer, and it was applied to a water electrolysis system. When a CEM is developed using a polymer electrolyte membrane according to an embodiment of the present invention, the hydrophilic/hydrophobic phase separation effect is maximized and the ion conduction channel structure can be controlled according to the application field.

The polymer electrolyte membrane according to an embodiment of the present invention is chemically stable because it is composed of fluorene that is stable to radicals. As the fluorene content in the polymer backbone increases, the free volume between chains increases, resulting in lower crystallinity and higher solubility. That is, when the ratio of fluorene is 0.5 or more, the film is easily broken, so synthesis in an appropriate ratio is required.

In addition, the polymer electrolyte membrane according to an embodiment of the present invention has excellent chemical stability because the entire polymer main chain is composed of only carbon single bonds. According to recent research results, when an aryl ether bond (C _sp2 -O) or a bond with low binding energy (benzylic CH bond, etc.) exists in a polymer used in CEM, the polymer decomposes under various operating conditions in which CEM is used. problems are being reported. Therefore, in the present invention, a polymer composed of only carbon-carbon bonds, which ultimately does not contain any decomposable weak bonds, was synthesized and used as a precursor material for the branched polymer to be finally developed.

In addition, the polymer electrolyte membrane according to an embodiment of the present invention is a branched copolymer polymer in which a cation exchange functional group is introduced at the end of a side chain. In the case of water/electrolyte, which plays an important role in the ion conduction of CEM, most of them are distributed around the ion exchange functional groups. Therefore, the present invention aims to simultaneously improve ionic conduction behavior and physicochemical stability due to a distinct hydrophilic/hydrophobic phase separation effect by synthesizing a branched polymer precursor capable of promoting a hydrophilic/hydrophobic fine phase separation structure.

In addition, the polymer electrolyte membrane according to an embodiment of the present invention was developed through the use of a monomer that is easy to mass-produce and a synthesis method. Branched polymers were developed using monomers capable of mass-scale and industrialization of actual synthesis. Hydrocarbon-based polymers used in conventional cation exchange membranes can be obtained through condensation polymerization at high temperature and for a long time under a base catalyst, but in the case of the polymer electrolyte membrane developed through the present invention, condensation polymerization at room temperature and 2 to 3 hours under an acid catalyst can be obtained through

Since the polymer electrolyte membrane of the present invention is a branched copolymer based on fluorene and biphenyl represented by Chemical Formula 1, it can exhibit high tensile strength, elongation, ionic conductivity, and ion exchange capacity (IEC). The polymer electrolyte membrane including the polymer having the repeating unit of [Formula 1] has a tensile strength of 30 MPa or more and an elongation of 50% or more. The polymer electrolyte membrane including the polymer having the repeating unit of [Formula 1] is characterized in that the ion conductivity is 50 to 350 mS/cm under running conditions in water. The polymer electrolyte membrane including the polymer having the repeating unit of [Formula 1] is characterized in that the ion exchange capacity (IEC) is 2.0 to 5.0 meq / g.

The method for manufacturing a polymer electrolyte membrane of the present invention is 9,9-dimethylfluorene, biphenyl and 7-bromo-1,1,1-trifluoroheptan-2-one (7 -Bromo-1,1,1-trifluoroheptan-2-one) to react to prepare a fluorene-biphenyl-based polymer, the fluorene-biphenyl-based polymer prepared in the first step and potassium thio The second step of preparing a thioacetic acid-bound fluorene-biphenyl-based polymer by reacting acetate (Potassium thioacetate) and the fluorene-biphenyl-based polymer prepared in the second step in a mixed solution of formic acid and distilled water. It is characterized in that it comprises a third step of preparing a fluorene-biphenyl-based ionomer by mixing a phenyl-based polymer and then slowly adding hydrogen peroxide.

As shown in the synthetic schematic diagram (Formula 2) below, the detailed description of each step is as follows.

[Formula 2]

Step 1: Preparation of fluorene-biphenyl-based polymer (hereinafter referred to as F1BC ₇ Br-n)

The first step is 9,9-dimethylfluorene (9,9-Dimethylfluorene), biphenyl (Biphenyl) and 7-bromo-1,1,1-trifluoroheptan-2-one (7-Bromo- 1,1,1-trifluoroheptan-2-one) and the 1-2 steps of precipitating the polymer solution produced in the 1-1 step in methanol.

The 1-1 step is the 9,9-dimethylfluorene (9,9-Dimethylfluorene), biphenyl (Biphenyl) and 7-bromo-1,1,1-trifluoroheptan-2-one (7 -Bromo-1,1,1-trifluoroheptan-2-one) 20 to 25 parts by weight of dichloromethane (DCM) is mixed with a solvent based on 1 part by weight of the mixture. More preferably, 23 parts by weight of the dichloromethane (DCM) is mixed as a solvent based on 1 part by weight of the mixture. At this time, trifluoromethanesulfonic acid (TFSA) is mixed as a catalyst.

After mixing the mixture, the solvent and the catalyst, the mixture is synthesized by maintaining the mixture at 4 to 6° C. for 20 to 40 minutes and then reacting at room temperature for 3 to 4 hours. More preferably, it is synthesized by maintaining at 5° C. for 30 minutes and then reacting at room temperature for 3.5 hours.

In step 1-2, the polymer solution produced in step 1-1 is precipitated in methanol, washed several times with methanol, and then dried in a vacuum oven at 35 to 45 °C.

Step 2: Preparation of a fluorene-biphenyl-based polymer to which thioacetic acid is bonded (hereinafter referred to as F1B-TA-n)

In the second step, the 2-1 step of reacting F1BC ₇ Br-n prepared in the 1st step with potassium thioacetate and the polymer solution produced in the 2-1 step with methanol and hydrochloric acid It consists of the 2-2 step of precipitating in a mixed solution.

In step 2-1, 5 to 10 parts by weight of tetrahydrofuran (THF) is mixed as a solvent with respect to 1 part by weight of the mixture of F1BC ₇ Br-n and potassium thioacetate. More preferably, 6 parts by weight of tetrahydrofuran (THF) is mixed as a solvent.

After mixing the mixture, the solvent and the catalyst, they are reacted at 45 to 55° C. for 9 to 11 hours. More preferably, it is synthesized by reacting at 50°C for 10 h.

In step 2-2, the polymer solution produced in step 2-1 is precipitated in a mixture of methanol and hydrochloric acid, washed several times with distilled water, and then dried in a vacuum oven at 35 to 45 °C.

Step 3: Preparation of ionomer based on fluorene-biphenyl (hereinafter referred to as F1B-SA-n)

In the third step, after mixing the F1B-TA-n in a mixed solution of formic acid and distilled water, hydrogen peroxide is slowly added to prepare a fluorene-biphenyl-based ionomer (F1B-SA-n) do. More specifically, after mixing the F1B-TA-n with the formic acid and distilled water at a temperature of 55 to 65 ° C, hydrogen peroxide was slowly added, and at 60 to 70 ° C for 5 to 7 hours. synthesize After synthesis, washed several times with distilled water, and then dried with a gel dryer at 40 to 60° C. for 0.5 to 1.5 hours to prepare F1B-SA-n.

The fluorene- and biphenyl-based branched copolymer polymer electrolyte membrane according to the present invention described above is included in the present invention as long as it is used for ion exchangeability in its use. Preferably, it can be usefully applied as an ion exchange membrane (electrolyte membrane) for electrolysis of water (water electrolysis) or fuel cells.

Accordingly, the present invention can provide a water electrolysis device and a fuel cell including the polymer electrolyte membrane. In addition, a fuel cell system including the fuel cell may be provided.

On the other hand, the water electrolysis device and fuel cell according to the present invention may have the same structure as usual, and if the polymer electrolyte membrane according to the present invention is used as an electrolyte, it is included in the present invention.

The water electrolysis device according to the present invention includes, for example, at least a membrane-electrode assembly (MEA) having an electrolyte membrane, anode and cathode catalyst layers formed on both surfaces of the electrolyte membrane, as usual, and supplying electrons, reactants, and products. It may be configured to include a frame, separator (separation plate), MEA support, gasket (packing), etc. arranged in a form in which excessive discharge is possible.

In this case, the electrolyte membrane constituting the membrane-electrode assembly (MEA) is composed of the fluorene and biphenyl-based branched copolymer polymer electrolyte membrane according to the present invention.

In addition, the fuel cell according to the present invention is, for example, a solid polymer fuel cell (PEFC) having the same structure as usual, and includes an electrolyte membrane, a catalyst layer bonded to both sides of the electrolyte membrane, and a gas diffusion layer bonded to the outside of the catalyst layer. A membrane-electrode assembly (MEA) comprising A separator may be disposed on the membrane-electrode assembly (MEA), and a gas flow path supplying fuel gas or oxidant gas may be formed at a contact portion between the membrane-electrode assembly (MEA) and the separator or in the separator. In addition, it has a fuel electrode to which fuel gas such as hydrogen or methanol is supplied, and an oxygen electrode to which oxidant gas such as air or oxygen is supplied. At this time, the electrolyte membrane constituting the membrane-electrode assembly (MEA) is composed of the polymer electrolyte membrane according to the present invention.

In addition, the fuel cell system according to the present invention may have a conventional structure, and as long as the fuel cell according to the present invention is used as a constituting fuel cell, it is included in the present invention. For example, the fuel cell system according to the present invention includes a fuel cell, a hydrogen generating device generating hydrogen from source gas and supplying hydrogen to the fuel electrode of the fuel cell, and an oxidant gas (air, oxygen, etc.) to the oxygen electrode of the fuel cell. ), a fuel gas opening/closing means for opening and closing the entrance and exit of the fuel electrode, an oxidizing agent gas opening and closing means for opening and closing the entrance and exit of the oxygen electrode, a hydrogen opening and closing means for opening and closing the entrance and exit of the hydrogen generating device, the fuel gas It may include a control device for controlling the opening/closing operation of the opening/closing means, the oxidizing agent gas opening/closing means, and the hydrogen opening/closing means. At this time, the fuel cell is composed of a fuel cell including the branched copolymer polymer electrolyte membrane based on fluorene and biphenyl according to the present invention. In addition, the water electrolysis device according to the present invention may be applied as the hydrogen generating device constituting the fuel cell system according to the present invention.

Hereinafter, the present invention will be described in more detail through examples. Objects, features, and advantages of the present invention will be easily understood through the following examples. The present invention is not limited to the embodiments described herein and may be embodied in other forms. The embodiments introduced here are provided to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention belongs. Therefore, the present invention should not be limited by the following examples.

Example 1: Preparation of fluorene-biphenyl-based polymers (hereinafter referred to as F1BC ₇ Br-10 and F1BC ₇ Br-30)

F1BC ₇ Br-10 is 9,9-Dimethylfluorene (1 g, 5.15 mmol), Biphenyl (7.14 g, 46.33 mmol) and 7-Bromo-1,1,1-trifluoroheptan-2-one (13.99 g, 56.62 mmol) as a monomer, Trifluoromethanesulfonic acid (TFSA) (77.25 g, 514.75 mmol) as a catalyst, and 23 wt% Dichloromethane (DCM) as a reaction solvent, maintained at 5 ℃ for 30 m and then reacted at RT for 3 h 30 m. It became. After the reaction, the resulting polymer solution was precipitated in methanol (1300 ml), washed several times with methanol, and then dried in a vacuum oven at 40 °C.

F1BC ₇ Br-30 is 9,9-Dimethylfluorene (2 g, 10.29 mmol), Biphenyl (3.70 g, 24.02 mmol) and 7-Bromo-1,1,1-trifluoroheptan-2-one (9.33 g, 37.75 mmol) as a monomer, TFSA (51.50 g, 343.17 mmol) as a catalyst, 23 wt% DCM based on the weight of the monomer as a reaction solvent, maintained at 5 ° C, 30 m, and then reacted at RT for 3 h. Precipitation and obtaining method were the same as above do.

Example 2: Preparation of thioacetic acid-coupled fluorene-biphenyl-based polymers (hereinafter referred to as F1B-TA-10 and F1B-TA-30)

For F1B-TA-10, FL1C ₇ Br-10 (2 g, 5.16 mmol) and Potassium thioacetate (1.12 g, 9.81 mmol) synthesized above were used as reaction materials, and 6 wt% Tetrahydrofuran (THF) based on the weight of the reactants was used as the reaction solvent. was synthesized by reacting at 50 °C for 10 h. After the reaction, the resulting polymer solution was precipitated in a mixture of methanol (1000 ml) and hydrochloric acid (100 ml, 2M), washed several times with distilled water, and then dried in a vacuum oven at 40 °C.

F1B-TA-30 was prepared by using FL1C7Br-30 (2 g, 5.06 mmol) and Potassium thioacetate (1.04 g, 9.11 mmol) synthesized above as reaction materials and 6 wt% Tetrahydrofuran (THF) as a reaction solvent. It was synthesized by reacting at ℃, 10 h, and the precipitation and obtaining methods are the same as above.

Example 3: Preparation of ionomers based on fluorene-biphenyl (hereinafter referred to as F1B-SA-10 and F1B-SA-30)

A cation exchange membrane using F1B-SA-n (n = 10, 30) was prepared by the following process.

In a 100 ml colorimetric tube, put an 8x8 cm2, 50 im F1B-TA-n (n = 10, 30) membrane in a solution of 15 ml of formic acid and 60 ml of distilled water at 60 ° C. After maintaining for 30 m, slowly add 15 ml of hydrogen peroxide. added and synthesized at 65 °C for 6 h. After the reaction, it was prepared by washing several times with distilled water and then drying with a 50 ℃, 1h gel dryer.

A cation exchange membrane using the fluorene-biphenyl-based ionomer (hereinafter referred to as F1B-SA-10 and F1B-SA-30) prepared in Example 3 was prepared, and an F1B-SA-10 polymer electrolyte membrane (a ) and F1B-SA-30 polymer electrolyte membrane (b).

The F1B-SA-10 polymer electrolyte membrane (a) and the F1B-SA-30 polymer electrolyte membrane (b) prepared above were tested as follows.

Experimental Example 1: Results of 1H NMR analysis of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30

¹ H-NMR confirmation results of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30 are shown in FIG. 2 . The progress of the reaction was determined by changing the NMR peak of CH ₂ (11) next to the modifyable position (-Br) at the terminal of the F1BC ₇ Br-30 branch.

From the F1B-TA-30 data, it was confirmed that F1BC ₇ Br-30, a pre-reaction material, was synthesized at 100% conversion through complete shift (11') of peak 11 and generation of peak 12. In addition, in the F1B-SA-30 data, it was confirmed that the reaction proceeded as the 11' peak shifted and the 12 peak disappeared.

Experimental Example 2: FT-IR analysis results of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30

As a result of checking the FT-IR of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30, a CH peak around 3000-2840 cm ^-1 can be confirmed, and C around 1725-1705 cm ^-1 The =O peak was confirmed to confirm the change of the terminal functional group. In addition, a CF peak around 1400-1000 cm ^-1 and an S=O peak around 1070-1030 cm ^-1 can be confirmed.

Experimental Example 3: TGA analysis results of F1BC ₇ Br-10, F1B-TA-30, and F1B-SA-30

The TGA of the electrolyte membrane was measured in the following way. After raising the temperature from room temperature to 120 °C at 20 °C min ^{-1 ,} the remaining water was removed and stabilized by maintaining for 10 min. Thereafter, after cooling at 20 °C min ^-1 to 60 °C, the weight change of the polymer sample was measured from 60 °C to 700 °C at 10 °C min ^-1 in a nitrogen atmosphere.

As shown in FIG. 4, it was confirmed that F1B-SA-10 and F1B-SA-30 exhibit stable thermal stability to be introduced into a polymer electrolyte membrane fuel cell system. As shown in FIG. 4 and Table 1, as a result of measuring the decomposition temperature of 5 wt.%, it was confirmed that they were 312 °C and 305 °C, respectively.

	F1B-SA-10	F1B-SA-30
T d5 ( ℃ )	312	305

Experimental Example 4: Chemical composition of F1B-SA-10 and F1B-SA-30 electrolyte membranes

The chemical durability of the electrolyte membrane was measured in the following way. Prepare Fenton's reagent by adding 4 ppm Iron(II) sulfate to 3% (w/w) hydrogen peroxide aqueous solution. The dried electrolyte membrane was cut into a size of 1 cm × 1 cm, put into a vial together with the prepared Fenton's reagent, placed in an oven at 80 ° C, and the state of the membrane was observed at intervals of 30 minutes to measure chemical durability through decomposition of the membrane. In the case of τ ₁ , it means the time when the film starts to decompose, and in the case of τ ₂ , it means the time when the film completely decomposes and disappears from the naked eye. Three measurements were taken for each sample.

When comparing the hydrocarbon-based electrolyte membranes (SPAES-50, SPAES-65) shown in FIG. 5 with the polymer electrolyte membrane prepared according to an embodiment of the present invention, as shown in FIG. 6 and Table 2, first decomposition and final decomposition It was confirmed that it was chemically stable by increasing the time taken to 2 to 6 times.

Sample	SPAES-65	SPAES-50	F1B-SA-10	F1B-SA-30
τ 1	65 ± 8.7	210±0.0	420±0.0	385 ± 8.7
τ 2	95 ± 8.7	240±0.0	610±0.0	568 ± 36

Experimental Example 5: Water absorption and dimensional change of F1B-SA-10 and F1B-SA-30 electrolyte membranes

Water absorption and dimensional change were measured in the following manner. The film dried through a desiccator was cut into a size of 1 cm × 4 cm, and the thickness and weight of the dried film were measured. Then, in a dry state, the membranes whose area, thickness, and weight were measured were placed in a vial, filled with distilled water, and placed in a drying oven at 30 °C and 80 °C, respectively. After 12 h, the swollen film was taken out of the oven, and the area, thickness, and weight were measured, and the dimensional change was measured using the following formula. Measurements were made three times for each sample.

Water uptake [%] = [(W _wet - W _dry ) / W _dry ] × 100

Change in dimension [%] = [((A _wet × T _wet ) - (A _dry × T _dry )) / (A _dry × T _dry )] × 100

(Where, W _dry and W _wet are the weights of the dried and swollen membranes, A _dry and A _wet are the areas of the dried and swollen membranes, and T _dry and T _wet are the thicknesses of the dried and swollen membranes)

	WU (%)	△V (%)	△A (%)
F1B SA-10 (IEC : 2.19 meq/g)	50.84 ± 2.51	56.14 ± 5.96	37.01 ± 2.08
F1B SA-30 (IEC: 2.22 meq/g)	53.23 ± 0.43	58.34 ± 1.84	41.50 ± 0.71

	WU (%)	△V (%)	△A (%)
F1B SA-10 (IEC: 2.19 meq/g)	58.59 ± 2.76	70.06 ± 2.62	48.67 ± 1.96
F1B SA-30 (IEC: 2.22 meq/g)	61.49 ± 1.99	69.75 ± 2.23	50.00 ± 1.22
Nafion 212	27.74 ± 0.29	51.25 ± 1.84	27.99 ± 4.40

Table 3 and FIG. 7 show dimensional changes of the electrolyte membrane at 30° C., and Table 4 and FIG. 8 show dimensional changes of the electrolyte membrane at 80° C. At 30 ° C and 80 ° C, F1B-SA-30 had higher water absorption and volumetric change than F1B-SA-10, and F1B-SA-n had a smaller change with temperature than Nafion 212.

Experimental Example 6: Measurement of ion exchange capacity of F1B-SA-10 and F1B-SA-30 electrolyte membranes

To measure the ion exchange capacity, the dried polymer electrolyte membrane was weighed, put into a 30 ml vial, 15 ml of 1M NaCl solution was added, and stirred at 60° C. for 6 h or more to prepare a sample. A 0.01M NaOH solution was checked using an automatic potentiometric titrator [Potentiometric titrator (TITRANDO 888)] until the pH of the solution containing the polymer electrolyte membrane reached pH = 7.0, and then the volume of NaOH entered was calculated using the following formula.

IEC _w = ( C _NaOH * ΔV _NaOH / W _s ) * 1000 [meq/g]

(Where C _NaOH is the NaOH concentration (0.01M), ΔV _NaOH is the volume of NaOH, and W _s is the weight of the dried film)

Sample	Theoretical IEC (meq/g)	Experimental IEC (meq/g)	Conversion (%)
F1B-SA-10	2.57	2.19±0.00	85.2
F1B-SA-30	2.52	2.22 ± 0.01	87.9

As shown in Table 5, the theoretical IEC of F1B-SA-10 was 2.57 meq g ^-1 and the experimental IEC was 2.19 meq g ^-1 , confirming the response rate of 85.2%. The theoretical IEC of F1B-SA-30 was 2.52 meq g ^-1 and the experimental IEC was 2.22 meq g ^-1 , confirming the response rate of 87.9%.

Experimental Example 7: Evaluation of mechanical properties of F1B-SA-10 and F1B-SA-30 electrolyte membranes

In order to measure the mechanical properties, after coupling a load cell of 250 N to the LLOYD UTM LS1 device, specimens cut according to ASTM D 638 type V were fastened. The extension rate was 5 mm/min, and at least 6 samples were measured for each type of electrolyte membrane to obtain the average and standard deviation of the strain-stress curve, Young's modulus, and elongation.

Sample	Tensile Strength (MPa)	Young's Modulus (MPa)	Elongation at Break (%)
F1B-SA-10	39.28 ± 4.64	695.41 ± 11.56	66.78 ± 9.05
F1B-SA-30	34.11 ± 2.33	877.30 ± 8.60	60.09 ± 2.35

As shown in Table 6 and FIG. 9, it was confirmed that F1B-SA-10 had higher tensile strength and elongation than F1B-SA-30.

Experimental Example 8: Proton Conductivity of F1B-SA-10 and F1B-SA-30 Electrolyte Membrane

To measure the hydrogen ion conductivity, a sample of 0.5 × 3 cm 2 was prepared, connected to a 4-probe cell, and then measured using electrochemical spectroscopy (SP-240, Bio Logic Science Instrument, France) equipment. The measurement condition was 100% RH condition in which the cell was placed in secondary distilled water, and the resistance value according to the temperature change from 30 ℃ to 90 ℃ was measured and calculated through the following formula.

Proton conductivity (σ) [mS cm ^-1 ] = d/RS

(Where, D is the distance between electrodes, R is the resistance value, and S is the thickness * width of the sample)

The resistance value was measured when reaching each temperature from 30 ℃ to 90 ℃ at intervals of 10 ℃ in the distilled water containing the cell, and the resistance value was measured and recorded 6 times at each temperature.

	Nafion 212	F1B-SA-10 IEC:2.19	F1B-SA-30 IEC: 2.22
30	76.29 ± 0.53	116.65 ± 2.67	124.22 ± 1.63
40	91.47 ± 1.73	138.01 ± 1.80	141.01 ± 3.15
50	105.34 ± 2.02	157.38 ± 1.05	157.82 ± 2.02
60	125.44 ± 1.79	172.95 ± 1.73	177.17 ± 1.43
70	139.24 ± 1.41	194.11 ± 1.61	194.76 ± 1.71
80	161.39 ± 3.09	215.03 ± 1.35	213.55 ± 0.86
90	185.79 ± 3.51	226.43 ± 2.50	228.61 ± 1.73

As shown in Table 7 and FIG. 10, the proton conductivity of F1B-SA-n was higher than that of Nafion 212 at all temperatures, and F1B-SA-30 and F1B-SA-10 showed similar conductivity values.

By means of solving the above problems, the present invention uses an electrophilic substitution reaction under strong acid conditions, rather than developing a cation exchange material through condensation polymerization under a conventional basic catalyst, so that there is no chemically weak bond in the polymer backbone, so that it can be chemically It has a stabilizing effect. In addition, the present invention can manufacture a chemically stable polymer electrolyte membrane composed of fluorene that is stable to radicals and a water electrolysis system using the same. In addition, according to the present invention, a polymer electrolyte membrane having excellent chemical stability and a water electrolysis system using the polymer electrolyte membrane having an entire polymer main chain composed of only carbon single bonds can be manufactured. In addition, the present invention is a branched copolymer polymer in which a cation exchange functional group is introduced at the end of a side chain, and a molecular electrolyte membrane that simultaneously improves ion conduction behavior and physicochemical stability due to a distinct hydrophilic or hydrophobic phase separation effect and a water electrolysis system using the same can be manufactured In addition, since the present invention is obtained through condensation polymerization at room temperature under an acid catalyst, a molecular electrolyte membrane that can be easily mass-produced and a water electrolysis system using the same can be manufactured.

As such, it will be understood that the technical configuration of the present invention described above can be implemented in other specific forms without changing the technical spirit or essential features of the present invention by those skilled in the art to which the present invention pertains.

Therefore, the embodiments described above should be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the claims to be described later rather than the detailed description, and the meaning and scope of the claims and their All changes or modified forms derived from equivalent concepts should be construed as being included in the scope of the present invention.

Claims (15)

1. A polymer electrolyte membrane comprising a polymer having a repeating unit of the following [Formula 1]:

   [Formula 1]

   

   (Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).
2. According to claim 1,

   A polymer electrolyte membrane comprising a polymer having a repeating unit of Formula 1,

   A polymer electrolyte membrane having a tensile strength of 30 MPa or more and an elongation of 50% or more.
3. According to claim 1,

   A polymer electrolyte membrane comprising a polymer having a repeating unit of Formula 1,

   A polymer electrolyte membrane, characterized in that the ion conductivity is 50 to 350 mS / cm.
4. According to claim 1,

   A polymer electrolyte membrane comprising a polymer having a repeating unit of Formula 1,

   A polymer electrolyte membrane, characterized in that the ion exchange capacity (IEC) is 2.0 to 5.0 meq / g.
5. 9,9-Dimethylfluorene, Biphenyl and 7-Bromo-1,1,1-trifluoroheptan-2-one (7-Bromo-1,1,1 A first step of preparing a fluorene-biphenyl-based polymer by reacting -trifluoroheptan-2-one);

   A second step of preparing a fluorene-biphenyl-based polymer to which thioacetic acid is bonded by reacting the fluorene-biphenyl-based polymer prepared in the first step with potassium thioacetate;

   After mixing the thioacetic acid-coupled fluorene-biphenyl-based polymer prepared in the second step with a mixed solution of formic acid and distilled water, hydrogen peroxide is slowly added to prepare a fluorene-biphenyl-based ionomer A polymer electrolyte membrane manufacturing method comprising the; third step of doing.
6. According to claim 5,

   The first step is

   9,9-Dimethylfluorene, Biphenyl and 7-Bromo-1,1,1-trifluoroheptan-2-one (7-Bromo-1,1,1 -1-1st step of reacting with trifluoroheptan-2-one); and

   A method for manufacturing a polymer electrolyte membrane comprising a 1-2 step of precipitating the polymer solution produced in the 1-1 step in methanol.
7. According to claim 5,

   The second step is

   Step 2-1 of reacting the fluorene-biphenyl-based polymer prepared in step 1 with potassium thioacetate; and

   A method for manufacturing a polymer electrolyte membrane comprising a 2-2 step of precipitating the polymer solution produced in the 2-1 step in a mixture of methanol and hydrochloric acid.
8. According to claim 5,

   The first step is a polymer electrolyte membrane manufacturing method, characterized in that using trifluoromethanesulfonic acid (TFSA) as a catalyst.
9. According to claim 5,

   The first step is

   The 9,9-dimethylfluorene (9,9-Dimethylfluorene), biphenyl (Biphenyl) and 7-bromo-1,1,1-trifluoroheptan-2-one (7-Bromo-1,1, A method for producing a polymer electrolyte membrane, characterized in that 20 to 25 parts by weight of dichloromethane (DCM) is used as a solvent based on 1 part by weight of a 1-trifluoroheptan-2-one) mixture.
10. According to claim 5,

    The first step is

    Polymer electrolyte membrane manufacturing method, characterized in that the reaction for 3 to 4 hours at room temperature.
11. According to claim 5,

    The second step is

    Characterized in that 5 to 10 parts by weight of tetrahydrofuran (THF) is used as a solvent based on 1 part by weight of the mixture of the fluorene-biphenyl-based polymer and potassium thioacetate prepared in the first step Polymer electrolyte membrane manufacturing method.
12. According to claim 5,

    In the second step,

    A method for producing a polymer electrolyte membrane, characterized by reacting at 45 to 55 ° C. for 9 to 11 hours.
13. According to claim 5,

    The third step,

    Polymer electrolyte membrane manufacturing method, characterized in that the reaction for 5 to 7 hours at 60 to 70 ℃.
14. A water electrolysis device comprising a polymer electrolyte membrane including a polymer having a repeating unit of the following [Formula 1]:

    [Formula 1]

    

    (Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).
15. A fuel cell comprising a polymer electrolyte membrane including a polymer having a repeating unit of the following [Formula 1]:

    [Formula 1]

    

    (Where n is an integer of 1-50 and m is an integer of 1-3, R is SO ₃ H or CH ₂ -SO ₃ H).

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