Copolymer, anion exchange membrane containing copolymer, anion exchange membrane type water electrolytic cell or fuel cell, and manufacturing method for hydrogen using anion exchange membrane water electrolytic cell

Abstract

To solve the problem of the conventional copolymers in which it is difficult to enhance both ion conductivity and ion exchange capacity while maintaining functionality as an anion exchange membrane and achieve sufficient durability under sufficient alkaline conditions.SOLUTION: This is achieved by a copolymer containing repeating unit formula (I) and repeating unit formula (II), an anion exchange membrane containing the copolymer, an anion exchange membrane type water electrolytic cell or fuel cell, and a manufacturing method for hydrogen using an anion exchange membrane water electrolytic cell.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copolymer, an anion exchange membrane containing the copolymer, an anion exchange membrane water electrolysis cell or fuel cell, and a method for producing hydrogen using the anion exchange membrane water electrolysis cell. [Background technology]

[0002] In order to move away from a society dependent on fossil fuels that generate greenhouse gases, there is a need to produce and use clean energy that will virtually eliminate carbon dioxide emissions. Hydrogen is colorless, odorless, lightweight, diffuses quickly, and has a high combustion temperature. It can also be produced, stored, and transported from a variety of energy sources. Hydrogen produced by water electrolysis, in particular, does not emit carbon dioxide upon combustion, and fuel cells made from the resulting hydrogen also do not emit carbon dioxide. Therefore, because it is a useful clean energy source, active research is being conducted on it.

[0003] Water electrolysis technologies can be classified into alkaline water electrolysis, which uses alkaline compounds such as potassium hydroxide as the electrolyte; solid polymer water electrolysis, which uses ion-exchange membranes as the electrolyte; and solid oxide water electrolysis, which uses ceramics as the electrolyte. Water electrolysis and fuel cells use ion-exchange membranes (electrolyte membranes), which are required to have excellent ionic conductivity and membrane durability. Anion-exchange membrane electrolysis, which electrolyzes water to produce hydrogen using anion-exchange membranes, has attracted particular attention because it allows for the elimination of precious metals in catalysts and gas diffusion layers, simplifies device structure, and significantly reduces costs compared to proton-exchange membranes, the mainstream solid polymer water electrolysis technology. Research has been conducted to improve the ionic conductivity and ion-exchange capacity of anion-exchange membranes and enhance their durability under alkaline conditions.

[0004] Patent Documents 1 and 2 disclose hydroxide exchange membranes or hydroxide exchange ionomers formed from poly(arylpiperidinium) polymers having piperidinium, an alkali-stable cation, incorporated into a rigid aromatic polymer backbone that does not contain ether bonds.

[0005] However, the anion exchange membranes produced from the polymers disclosed in Patent Documents 1 and 2 have insufficient ionic conductivity and ion exchange capacity due to the small number of cations contained in the molecule. Furthermore, there is no disclosure about durability under alkaline conditions, which are the driving environment for water electrolysis.

[0006] Non-Patent Document 1 discloses a poly(fluorenylarylpiperidinium) copolymer as a copolymer used in an anion exchange membrane of a fuel cell.

[0007] However, the anion exchange membrane produced from the copolymer disclosed in Non-Patent Document 1 also has insufficient durability under alkaline conditions. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2019-518809 [Patent Document 2] Special Publication No. 2020-536165 [Non-patent literature]

[0009] [Non-Patent Document 1] Nanjun Chen et al., NATURE COMMUNICATIONS, 12, 2367 (2021) Summary of the Invention [Problem to be solved by the invention]

[0010] It has been difficult for polymers obtained by conventional techniques to have high ionic conductivity and ion exchange capacity while maintaining the function as an anion exchange membrane, and to have sufficient durability under alkaline conditions.

[0011] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a copolymer for producing an anion exchange membrane that has high ionic conductivity and ion exchange capacity and is excellent in durability under alkaline conditions, an anion exchange membrane containing the copolymer, an anion exchange membrane water electrolysis cell or fuel cell, and a method for producing hydrogen using the anion exchange membrane water electrolysis cell. [Means for solving the problem]

[0012] The present inventors have conducted extensive research into the above-mentioned problems and have arrived at the present invention. That is, the object of the present invention is achieved by the following aspects.

[0013] [1] A copolymer comprising a repeating unit formula (I) and a repeating unit formula (IIA) or (IIB):

[0014] [ka]

[0015] [In formulas (I), (IIA) and (IIB), R 1 are each independently an organic group containing N or P, and R 2 is an arylene group, and R 3 are each independently selected from the group consisting of alkyl groups, cycloalkyl groups, arylalkyl groups, aryl groups, alkylaryl groups, alkoxy groups, and alkylthio groups, each having 2 to 20 carbon atoms; R 4 is a substituted or unsubstituted trivalent aromatic group, and Y - are each independently a counter anion, n1 is an integer of 1 to 10, and n2 is an integer of 1 to 10.

[0016] [2]R 1+are each independently an organic group containing N or P selected from the group consisting of an ammonium ion, an imidazolium ion, a pyrrolidinium ion, a pyridinium ion, a pyridazinium ion, a pyrimidinium ion, a pyrazinium ion, a pyrazolium ion, a piperidinium ion, a morpholinium ion, and a phosphonium ion.

[0017] [3]R 2 is selected from the group consisting of a phenylene group, a methylphenylene group, an ethylphenylene group, a naphthylene group, a biphenylylene group, a terphenylene group, an anthrylene group, and a phenanthrylene group.

[0018] [4]R 3 are each independently selected from the group consisting of an alkyl group, a cycloalkyl group, an arylalkyl group, an aryl group, and an alkylaryl group, each having 3 to 15 carbon atoms.

[0019] [5]R 4 However, the following groups: [ka] The copolymer according to any one of [1] to [4], wherein

[0020] [6] The counter anions are each independently OH - , COO - , F - , Cl - , Br - , I - , CO3 2- , NO3 - , SO4 2- and PO4 3- The copolymer according to any one of [1] to [5], wherein the copolymer is one or more selected from the group consisting of:

[0021] [7] An anion exchange membrane comprising the copolymer according to any one of [1] to [6].

[0022] [8] An anion exchange membrane water electrolysis cell comprising the anion exchange membrane according to [7].

[0023] [9] A method for producing hydrogen, comprising a step of electrolyzing water using the anion exchange membrane water electrolysis cell according to [8].

[0024]

[10] A fuel cell comprising the anion exchange membrane according to [7]. [Effects of the Invention]

[0025] The copolymer of the present invention comprising the repeating unit formula (I) and the repeating unit formula (IIA) or (IIB) can provide an anion exchange membrane, an anion exchange membrane water electrolysis cell or fuel cell, and a method for producing hydrogen using an anion exchange membrane water electrolysis cell, which have high ionic conductivity, high ion exchange capacity, and excellent durability under alkaline conditions. DETAILED DESCRIPTION OF THE INVENTION

[0026] [Copolymer] The copolymer of the present invention is characterized by comprising a repeating unit formula (I) and a repeating unit formula (IIA) or (IIB):

[0027] [ka]

[0028] [In formulas (I), (IIA) and (IIB), R 1 are each independently an organic group containing N or P, and R 2 is an arylene group, and R 3 are each independently selected from the group consisting of alkyl groups, cycloalkyl groups, arylalkyl groups, aryl groups, alkylaryl groups, alkoxy groups, and alkylthio groups, each having 2 to 20 carbon atoms; R 4 is a substituted or unsubstituted trivalent aromatic group, and Y -are each independently a counter anion, n1 is an integer of 1 to 10, and n2 is an integer of 1 to 10.

[0029] In one embodiment, the alkyl group is a linear or branched monovalent saturated hydrocarbon group and may be selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl. The alkyl group preferably has 2 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and even more preferably 5 to 12 carbon atoms.

[0030] In one embodiment, the cycloalkyl group is a cyclic monovalent saturated hydrocarbon group and may be selected from the group consisting of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and cyclododecyl. The cycloalkyl group preferably has 3 to 20 carbon atoms, more preferably 4 to 15 carbon atoms, and even more preferably 5 to 12 carbon atoms.

[0031] In one embodiment, the aryl group is a substituted or unsubstituted monovalent aromatic group and may be selected from the group consisting of phenyl, tolyl, xylyl, benzyl, ethylbenzyl, naphthyl, and biphenyl. When the aromatic group is substituted, it may contain hydroxyl, halogen, C1-C6 alkyl, aryl, aryl- ... 12 or an alkyl group of C1 to C 12 The aryl group may be substituted with an alkoxy group such as the following: The aryl group preferably has 6 to 20 carbon atoms, and more preferably has 6 to 15 carbon atoms.

[0032] In one embodiment, the alkoxy group is a monovalent group having a hydrocarbon group bonded via an ether bond, and may be selected from the group consisting of methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, and dodecyloxy. The alkoxy group preferably has 2 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and even more preferably 5 to 12 carbon atoms.

[0033] In one embodiment, the alkylthio group is a group in which the oxygen atom in the ether bond of an alkoxy group is substituted with a sulfur atom, and may be selected from the group consisting of methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio, heptylthio, octylthio, nonylthio, decylthio, undecylthio, and dodecylthio. The alkylthio group preferably has 2 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and even more preferably 5 to 12 carbon atoms.

[0034] In one embodiment, the arylalkyl group represents a monovalent group in which an aryl group is bonded to an alkyl group. The alkyl group in the arylalkyl group can be a group described above as an "alkyl group," and the aryl group in the arylalkyl group can be a group described above as an "aryl group." The number of carbon atoms in the arylalkyl group is preferably 7 to 20, and more preferably 7 to 15.

[0035] In one embodiment, the alkylaryl group represents a monovalent group in which an alkyl group is bonded to an aryl group. The aryl group in the alkylaryl group can be a group described above as an "aryl group," and the alkyl group in the alkylaryl group can be a group described above as an "alkyl group." The number of carbon atoms in the alkylaryl group is preferably 7 to 20, and more preferably 7 to 15.

[0036] In one embodiment, the molar ratio of the repeating unit formula (I) to the repeating unit formula (IIA) or (IIB) [(I):(IIA) or (IIB)] may be in the range of 1:0.8 to 1:15, preferably 1:0.9 to 1:12, and more preferably 1:0.9 to 1:10.

[0037] In one embodiment, the repeating unit formula (I) and the repeating unit formula (IIA) or (IIB) may be linked alternately. When the copolymer contains the repeating unit formula (I) and the repeating unit formula (IIA) or (IIB), an anion exchange membrane having high ionic conductivity and ion exchange capacity and excellent durability under alkaline conditions can be obtained.

[0038] In one embodiment, R 1+ may each independently form an organic group containing N or P selected from the group consisting of an ammonium ion, an imidazolium ion, a pyrrolidinium ion, a pyridinium ion, a pyridazinium ion, a pyrimidinium ion, a pyrazinium ion, a pyrazolium ion, a piperidinium ion, a morpholinium ion, and a phosphonium ion.

[0039] In one embodiment, R 1 are each independently a group selected from the following groups:

[0040] [ka]

[0041] [wherein each n is independently an integer of 1 to 10].

[0042] In one embodiment, R 2The arylene group in R is a substituted or unsubstituted divalent aromatic group, and the aromatic group may be selected from the group consisting of benzene, toluene, xylene, ethylbenzene, cumene, phenol, benzyl alcohol, anisole, acetophenone, cresol, catechol, resorcinol, hydroquinone, benzophenone, naphthalene, biphenyl, anthracene, phenanthrene, terphenyl, triphenylmethane, pyrene, and tetracene, and is preferably phenyl, biphenyl, or terphenyl, and more preferably biphenyl or terphenyl. When the aromatic group is substituted, it may be substituted with a hydroxyl group, a halogen, an alkyl group, or an alkoxy group. The arylene group may preferably be selected from the group consisting of a phenylene group, a methylphenylene group, an ethylphenylene group, a naphthylene group, a biphenylylene group, a terphenylene group, an anthrylene group, and a phenanthrylene group. 2 The number of carbon atoms is preferably 6 to 30, and more preferably 6 to 20.

[0043] In one embodiment, R 3 may each independently be selected from the group consisting of an alkyl group, a cycloalkyl group, an arylalkyl group, an aryl group, and an alkylaryl group having 3 to 15 carbon atoms.

[0044] In one embodiment, R 3 are each independently a group selected from the following groups:

[0045] [ka]

[0046] In one embodiment, R 4R is a substituted or unsubstituted trivalent aromatic group, which may be selected from the group consisting of benzene, naphthalene, biphenyl, anthracene, phenanthrene, terphenyl, triphenylbenzene, pyrene, and tetracene, and is preferably phenyl, biphenyl, terphenyl, or triphenylbenzene. When the aromatic group is substituted, it may be substituted with a hydroxyl group, a halogen, an alkyl group, or an alkoxy group. 4 The number of carbon atoms is preferably 6 to 30, and more preferably 6 to 20.

[0047] In one embodiment, R 4 is the following group: [ka] is.

[0048] In one embodiment, the counter anion is OH - , COO - , F - , Cl - , Br - , I - , CO3 2- , NO3 - , SO4 2- and PO4 3- The counter anion may be one or more selected from the group consisting of: - , COO - , Cl - , or I - and more preferably OH - is.

[0049] In one embodiment, n1 and n2 are integers of 1 to 10, preferably integers of 2 to 8, and more preferably integers of 3 to 7.

[0050] In one embodiment, the copolymer preferably has a weight average molecular weight of 5000 to 500000. The weight average molecular weight may be measured by gel permeation chromatography (GPC) analysis.

[0051] [Anion exchange membrane] The anion exchange membrane of the present invention is characterized by containing the above copolymer.

[0052] In one embodiment, the copolymer may be dissolved in a solvent capable of dissolving the copolymer (e.g., dimethyl sulfoxide, alcohol, an aqueous alcohol solution, etc.) to prepare a polymer solution, which may then be coated using a coating method known in the art and dried to produce an anion exchange membrane.

[0053] In one embodiment, the thickness of the anion exchange membrane is not particularly limited, but may be, for example, 1 μm to 200 μm, specifically 5 μm to 200 μm, and more specifically 10 μm to 200 μm. When the thickness of the anion exchange membrane is within the above range, it is possible to reduce electric shorts and crossover of electrolytes, raw materials in fuel cells, products in electrolysis, and the like.

[0054] In one embodiment, the ionic conductivity of the anion exchange membrane is 20 mS / cm to 500 mS / cm, preferably 50 mS / cm to 300 mS / cm, and more preferably 100 mS / cm to 250 mS / cm.

[0055] The ionic conductivity of the anion exchange membrane may be measured by AC impedance measurement. Specific measurement methods are not particularly limited as long as they are known in the art. For example, the anion exchange membrane is placed in an ionic conductivity measurement cell in which 0.5 cm square platinum electrodes are arranged at a distance of 1.0 cm, and the cell is immersed in pure water. The voltage is scanned at 50 mV over a frequency range of 10 MHz to 100 Hz at a temperature range of 20°C to 80°C.

[0056] In one embodiment, the ionic conductivity of the anion exchange membrane may be measured under humidified conditions. In this specification, humidified conditions refer to a relative humidity (RH) of 10% to 100%. More preferably, the ionic conductivity of the anion exchange membrane is measured under a relative humidity (RH) of 95%.

[0057] In one embodiment, the anion exchange membrane has an ion exchange capacity (IEC) value of 1.0 meq / g to 7.5 meq / g, preferably 1.5 meq / g to 6.0 meq / g, and more preferably 1.5 meq / g to 5.5 meq / g. When the ion exchange capacity of the anion exchange membrane is within the above range, ion channels are formed in the anion exchange membrane, allowing the copolymer to conduct ions.

[0058] The ion exchange capacity of the anion exchange membrane may be measured by titration using silver nitrate according to the Mohr method. The specific measurement method is not particularly limited as long as it is a method known in the art. For example, - The weight of the anion exchange membrane (before exchange treatment) is measured, and it is immersed in a 1.0 mol / L NaNO3 aqueous solution for 24 hours. The anion exchange membrane is then removed and titrated with an AgNO3 aqueous solution of known concentration using a K2CrO4 aqueous solution as an indicator. The ion exchange capacity is calculated from the amount of AgNO3 required to reach the neutralization point.

[0059] [Anion exchange membrane water electrolysis cell] The anion exchange water electrolysis cell of the present invention is characterized by comprising the above-described anion exchange membrane.

[0060] In one embodiment, the anion exchange water electrolysis cell may include, but is not limited to, a membrane electrode assembly including an anode and a cathode separated by an anion exchange membrane, a separator, a power supply for applying voltage, a system for supplying water to the cell, a system for discharging oxygen produced at the anode, and a system for discharging hydrogen at the cathode, etc. These may be assembled by methods well known in the art.

[0061] [Hydrogen production methods] The method for producing hydrogen of the present invention is characterized by comprising a step of electrolyzing water using the anion exchange membrane water electrolysis cell described above.

[0062] In one embodiment, the reactions at the anode and cathode of the water electrolysis cell may be, for example, as follows: (Anode) 4OH - →O2+2H2O+4e - (cathode) 4H2O + 4e - →2H2+4OH - OH from the cathode to the anode through the anion exchange membrane of the present invention - Ions are supplied.

[0063] In the above reaction, the cell system becomes alkaline, but the anion exchange membrane of the present invention is stable even under alkaline conditions and can therefore function as an anion exchange membrane.

[0064] The hydrogen obtained at the cathode may be recovered by methods known in the art and used, for example, as a fuel cell material.

[0065] [Fuel cell] The fuel cell of the present invention is characterized by comprising the above-described anion exchange membrane.

[0066] In one embodiment, the fuel cell may include, but is not limited to, a membrane electrode assembly including an anode and a cathode separated by an anion exchange membrane, a cathode catalyst layer and an anode gas diffusion layer included in the anode, and a cathode catalyst layer and a cathode gas diffusion layer included in the cathode, which may be assembled by methods known in the art.

[0067] In one embodiment, the fuel may be selected from those known in the art, such as, but not limited to, hydrogen, methanol, ethanol, propanol, butanol, ethylene glycol, or natural gas.

[0068] The reactions at the anode and cathode of a hydrogen fueled fuel cell may be, for example, as follows: (Anode) 2OH -+H2→2H2O+2e - (cathode) O2 + 2H2O + 4e - →4OH - OH from the cathode to the anode through the anion exchange membrane of the present invention - Ions are supplied.

[0069] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. [Example]

[0070] (Comparative Example 1) Preparation of copolymer 1. Monomer synthesis [ka]

[0071] Potassium hydroxide (KOH) (150 g) and tetrabutylammonium chloride (n-BuNCl) (556 mg) were added to a 500 mL recovery flask and dissolved in 300 mL of purified water under an Ar stream. The mixture was stirred at 90 °C. Fluorene (2.5 g) was dissolved in 1,6-dichlorohexane (23.3 g) and added all at once to the recovery flask. After 3 hours, the mixture was cooled to room temperature and extracted three times with dichloromethane (200 mL). After drying with sodium sulfate (50 g), the mixture was filtered through filter paper and concentrated under vacuum. The product was purified by silica gel column chromatography (eluent: hexane:dichloromethane = 5:1) to obtain 2.46 g of the compound in 40% yield.

[0072] 2. Copolymer Production [ka]

[0073] The compound obtained in 1 (0.2 mmol, 80.5 mg), 1-methyl-4-piperidone (2.2 mmol, 249 mg), p-terphenyl (1.8 mmol, 415 mg), and dichloromethane (3.2 mL) were added to a 13.5 mL mighty vial. Trifluoroacetic acid (0.24 mL) was then added and the mixture was stirred at 0°C. Trifluoromethanesulfonic acid (3.2 mL) was then added portionwise and the mixture was stirred at 4°C for 18 hours. The reaction solution was poured into a 1 mol / L aqueous KOH solution (100 mL). The copolymer was recovered by suction filtration and washed with purified water until the pH was neutral. The recovered copolymer was dried under vacuum at 80°C for 3 hours, yielding 2.3 g of copolymer.

[0074] 3. Cationization reaction of copolymer [ka]

[0075] The copolymer (2.3 g) obtained in 2 was dissolved in dimethyl sulfoxide (DMSO) (20 mL), and potassium carbonate (1.25 g) and iodomethane (0.42 mL) were added. The solution was stirred at room temperature for 18 hours in the dark. After removing the potassium carbonate by filtration, unreacted iodomethane was removed from the reaction solution using an evaporator (30 hPa or less, 70°C, 1 hour). A solution of trimethylamine in methanol (3.2 mol / L, 1.25 mL, 4.0 mmol) was added to the resulting solution, and the mixture was stirred at 100°C for 18 hours. The reaction solution was added to ethyl acetate (400 mL), and the precipitated solid was collected by suction filtration and washed with ethyl acetate and pure water. The resulting copolymer was dried under vacuum at 80°C for 3 hours, yielding 1.7 g of the copolymer of Comparative Example 1.

[0076] The monomer unit composition of the resulting polymer was analyzed by proton nuclear magnetic resonance (H-NMR) measurement, and the weight-average molecular weight (Mw) was analyzed by gel permeation chromatography (GPC). For GPC, 2,2,2-trifluoroethanol containing 10 mmol / L sodium trifluoroacetate was used as the eluent, and polymethyl methacrylate was used as the sample for creating a calibration curve. The resulting polymer was placed in a 1.0 mol / L KOH aqueous solution at 95°C for 100 hours to evaluate its solubility. The results are shown in Table 1.

[0077] Example 1: Preparation of copolymer The copolymer of Example 1 below was obtained in a yield of 2.1 g by the same procedure as in Comparative Example 1, except that 1-ethyl-4-piperidone (2.2 mmol, 280 mg) was used instead of 1-methyl-4-piperidone (2.2 mmol, 249 mg).

[0078] [ka]

[0079] Example 2: Preparation of copolymer The copolymer of Example 2 below was obtained in a yield of 1.2 g by the same procedure as in Comparative Example 1, except that 1-benzyl-4-piperidone (2.2 mmol, 416 mg) was used instead of 1-methyl-4-piperidone (2.2 mmol, 249 mg) in the preparation of the copolymer.

[0080] [ka]

[0081] Example 3: Preparation of copolymer The copolymer of Example 3 below was obtained in a yield of 1.1 g by the same procedure as in Comparative Example 1, except that 1-(2-phenylethyl)-4-piperidone (2.2 mmol, 447 mg) was used instead of 1-methyl-4-piperidone (2.2 mmol, 249 mg) in the preparation of the copolymer.

[0082] [ka]

[0083] Example 4: Preparation of copolymer The copolymer of Example 4 below was obtained in a yield of 1.0 g by carrying out the same operations as in Comparative Example 1, except that in 2. Preparation of the copolymer, 1-benzyl-4-piperidone (2.2 mmol, 416 mg) was used instead of 1-methyl-4-piperidone (2.2 mmol, 249 mg), and in 3. Cationization reaction of the copolymer, triphenylphosphine (4.0 mmol, 1049 mg) was used instead of the methanol solution of trimethylamine (4.0 mmol).

[0084] [ka]

[0085] (Example 5) Preparation of copolymer The copolymer of Example 5 below was obtained in a yield of 1.0 g by carrying out the same operations as in Comparative Example 1, except that in 2. Preparation of the copolymer, 1-benzyl-4-piperidone (2.2 mmol, 416 mg) was used instead of 1-methyl-4-piperidone (2.2 mmol, 249 mg), and in 3. Cationization reaction of the copolymer, 4-methylmorpholine (4.0 mmol, 405 mg) was used instead of the methanol solution of trimethylamine (4.0 mmol).

[0086] [ka]

[0087] (Example 6) Preparation of copolymer The copolymer of Example 6 below was obtained in a yield of 1.0 g by carrying out the same operations as in Comparative Example 1, except that in 2. Preparation of the copolymer, 1-benzyl-4-piperidone (2.2 mmol, 416 mg) was used instead of 1-methyl-4-piperidone (2.2 mmol, 249 mg), and in 3. Cationization reaction of the copolymer, N-methyldipropylamine (4.0 mmol, 461 mg) was used instead of the methanol solution of trimethylamine (4.0 mmol).

[0088] [ka]

[0089] (Preparation of anion exchange membrane) The copolymers obtained in Comparative Example 1 and Examples 1 to 6 were dissolved in dimethyl sulfoxide (DMSO) at a concentration of 60 mg / 2 mL while heating to 80°C to obtain a copolymer solution. The copolymer solution was then cast onto a UV / ozone-treated 5 cm x 5 cm glass plate and dried at 90°C to obtain a 20 μm-thick anion exchange membrane.

[0090] (Membrane solubility) The anion exchange membrane was immersed in a 1.0 mol / L aqueous solution of KOH and allowed to stand at 95°C for 100 hours. The state of the membrane after 100 hours was visually inspected to evaluate the solubility of the membrane. The results are shown in Table 1.

[0091] [Table 1]

[0092] As shown in Table 1, Comparative Example 1, which had a methyl group in the piperidone unit, dissolved in a 1.0 mol / L KCl solution at 95°C, while the polymers of Examples 1 to 6, which had other functional groups, did not dissolve. This result suggests that the piperidone unit has a hydrophobic and bulky group, which is effective in improving the durability of the anion exchange membrane in terms of the physical strength against alkali.

[0093] (Durability test) Before conducting the following ion exchange capacity, ion conductivity, and tensile tests, the anion exchange membranes were immersed in a 1.0 mol / L KOH aqueous solution at 80°C for 1,000 hours as a durability test. After 1,000 hours, the membranes were washed with pure water and used to measure the various physical properties. Note that the membrane of Comparative Example 1, which has a methyl group in the piperidone unit, dissolved and could not be used for the measurements. For comparison, similar measurements were also performed on commercially available PiperION-A20 membrane (Versogen, Comparative Example 2) and Sustainion membrane (Dioxide Materials, Comparative Example 3).

[0094] (ion exchange capacity) The ion exchange capacity was measured by titration using silver nitrate using the Mohr method. First, the anion exchange membrane was immersed in a 5.0 mol / L NaCl aqueous solution for 1 hour to measure the Cl content. - The anion exchange membrane was converted to an anion exchange membrane and its dry weight was measured. After immersing the dried membrane in a 1.0 mol / L NaNO3 aqueous solution for 24 hours, the anion exchange membrane was removed and titrated with an AgNO3 aqueous solution of known concentration using a K2CrO4 aqueous solution as an indicator. The ion exchange capacity was calculated from the amount of AgNO3 required to reach the neutralization point. The results are shown in Table 2.

[0095] (ionic conductivity) The ionic conductivity was measured using an AC impedance measuring device (WK6500P Series High Frequency LCR Meter, Wayne Kerr Electronics). The anion exchange membrane was immersed in a 1.0 mol / L KOH aqueous solution for 24 hours to measure the OH conductivity. - After the exchange treatment, the ionic conductivity of the resulting anion exchange membrane was measured. The measurement voltage was 50 mV, and the measurement frequency range was 10 MHz to 100 Hz. The ion exchange membrane was placed in an ionic conductivity measurement cell with 0.5 cm square platinum electrodes positioned 1.0 cm apart, and the cell was immersed in pure water and measured at temperatures ranging from 20°C to 80°C. The results are shown in Table 2.

[0096] (Tensile test) The tensile test was performed using a tensile testing machine (MCT-2150, AND Co.). A No. 7 dumbbell-shaped test piece and a 500 N load cell were used for the measurement. The measurement was performed at room temperature, and the tensile speed was 10 mm / min. The results are shown in Table 2.

[0097] [Table 2]

[0098] The results in Table 2 show that the ion exchange capacities of the anion exchange membranes of Examples 2 and 5 before the durability test were higher than those of the commercially available Sustainion membrane and comparable to those of the PiperION membrane. The ion exchange capacity of the anion exchange membrane of Example 2 after the durability test was comparable to that of the PiperION membrane. The ionic conductivities of the anion exchange membranes of Examples 2 and 5 before the durability test were lower than those of the commercially available anion exchange membrane, but the retention rates of ionic conductivity after the durability test were higher than those of the commercially available anion exchange membrane. The tensile strengths of the anion exchange membranes of Examples 2 and 5 before and after the durability test were comparable to those of the PiperION membrane. These results demonstrate that the anion exchange membranes of the present invention have superior properties compared to commercially available anion exchange membranes.

[0099] (water electrolysis) A hydrogen generation test was conducted by water electrolysis using an anion exchange membrane made using the copolymer of Example 2. The cathode used Pt / C as the catalyst and commercially available PiperION-A as the ionomer, while the anode used IrO2 as the catalyst and PiperION-C as the ionomer. Water electrolysis was performed at 80°C, and LSV measurements were performed five times in the range of 1.2 V to 2.2 V. For comparison, similar measurements were also performed on a commercially available PiperION membrane. The results are shown in Table 3.

[0100] [Table 3]

[0101] Table 3 shows the maximum current density measured five times when a voltage of 2.0 V was applied. The results in Table 3 show that the anion exchange membrane of Example 2 had about half the ionic conductivity of the commercially available PiperION membrane, but the initial water electrolysis capacity of the membrane was almost the same. [Industrial Applicability]

[0102] An anion exchange membrane containing the copolymer of the present invention has high ionic conductivity and ion exchange capacity, and is also excellent in durability under alkaline conditions, and therefore can exhibit high performance, for example, in anion exchange membrane water electrolysis, which enables efficient extraction of hydrogen gas from water and can contribute to solving energy problems.

Claims

1. A copolymer comprising the repeating unit formula (I) and the repeating unit formula (IIA) or (IIB): 【Chemical 1】 [In formulas (I), (IIA) and (IIB), R １ are each independently an organic group containing N or P, and R ２ is an arylene group, and R ３ are each independently selected from the group consisting of alkyl groups, cycloalkyl groups, arylalkyl groups, aryl groups, alkylaryl groups, alkoxy groups, and alkylthio groups, each having 2 to 20 carbon atoms; R ４ is a substituted or unsubstituted trivalent aromatic group, and Y － are each independently a counter anion, n1 is an integer of 1 to 10, and n2 is an integer of 1 to 10.

2. R １＋ are each independently an N- or P-containing organic group selected from the group consisting of an ammonium ion, an imidazolium ion, a pyrrolidinium ion, a pyridinium ion, a pyridazinium ion, a pyrimidinium ion, a pyrazinium ion, a pyrazolium ion, a piperidinium ion, a morpholinium ion, and a phosphonium ion.

3. R ２ 2. The copolymer of claim 1, wherein is selected from the group consisting of a phenylene group, a methylphenylene group, an ethylphenylene group, a naphthylene group, a biphenylylene group, a terphenylene group, an anthrylene group, and a phenanthrylene group.

4. R ３ are each independently selected from the group consisting of an alkyl group, a cycloalkyl group, an arylalkyl group, an aryl group, and an alkylaryl group, each having 3 to 15 carbon atoms.

5. R ４ is the following group: 【Chemistry 2】 The copolymer of claim 1 ,

6. The counter anions are each independently OH － , COO － , F － , Cl － ,Br － , I － , CO ３ ２－ , NO ３ － , S.O. ４ ２－ and P.O. ４ ３－ The copolymer according to claim 1, wherein the copolymer is one or more selected from the group consisting of:

7. An anion exchange membrane comprising the copolymer according to any one of claims 1 to 6.

8. An anion exchange membrane water electrolysis cell comprising the anion exchange membrane according to claim 7.

9. A method for producing hydrogen, comprising a step of electrolyzing water using the anion exchange membrane water electrolysis cell according to claim 8.

10. A fuel cell comprising the anion exchange membrane according to claim 7.

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