Crosslinked copolymer, polymer membrane comprising same, and anion exchange membrane comprising polymer membrane

Abstract

The present invention relates to a crosslinked copolymer having excellent stability under basic conditions, a polymer membrane comprising same, and an anion exchange membrane comprising the polymer membrane.

Description

Crosslinked copolymer, polymer membrane comprising the same, and anion exchange membrane comprising the polymer membrane

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0081337, filed June 21, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a crosslinked copolymer, a polymer membrane comprising the same, and an anion exchange membrane comprising the polymer membrane.

[0004]

[0005] Water electrolysis technology, which utilizes electrolysis of water, offers the advantages of not emitting greenhouse gases, utilizing an infinite water source, and linking it with renewable energy sources to store unused electricity in large quantities and over long periods. A water electrolysis device consists of electrodes that generate hydrogen and oxygen, and an ion exchange membrane that prevents gas mixing and transports ions. The ion exchange membrane is a key component that determines the efficiency and stability of the device.

[0006] Low-temperature water electrolysis technologies include alkaline water electrolysis, polymer electrolyte membrane (PEM) electrolysis, and anion exchange membrane (ANM) electrolysis. Among these, ANM is considered an ideal technology, combining the advantages of both. Anion exchange membrane electrolysis shares a similar structure to PEM electrolysis, making it easy to operate at high pressure and differential pressure. It also operates at high current densities, enabling miniaturization of the device. Unlike PEM electrolysis, it operates in an alkaline environment, allowing the use of non-precious metal catalysts rather than platinum-based catalysts. This reduces the cost of materials and contributes to the economic feasibility of green hydrogen production. Anion exchange membrane electrolysis is still in the R&D phase, and commercialization requires overcoming issues such as the low ionic conductivity of anion exchange membranes and the performance and reliability of non-precious metal catalysts.

[0007] Poly(styrene-ethylene-co-butylene-styrene) (hereinafter referred to as SEBS), a type of triblock copolymer, has been widely used as an anion exchange membrane polymer material due to its high ionic conductivity resulting from the excellent morphology of block polymers and high alkaline stability resulting from the non-aryl-ether type polymer structure.

[0008] However, in the case of SEBS-based anion exchange membranes, due to the elasticity of SEBS, when the ion exchange capacity (IEC) increases, the moisture content and swelling rate increase rapidly, which results in a decrease in conductivity due to the dilution effect, or the low tensile strength and high water absorption and swelling rate deteriorate the mechanical and physical stability, making it very inconvenient to handle the membrane.

[0009] To address these issues, cross-linked polymers composed of SEBS and polyphenylene oxide have been proposed (J. Membr. Sci. 564 (2018), 492-500 and Korean Patent No. 10-2184530, etc.). However, these cross-linked copolymers have the disadvantage of somewhat reduced chemical stability, as the ether bonds of polyphenylene oxide can be decomposed under alkaline conditions.

[0010] Additionally, a polymer cross-linked with a relatively stable polystyrene polymer under alkaline conditions and a SEBS polymer has been proposed (J. Appl. Polm. Sci. 138 (2021), e50540 and Chinese Patent No. 109265715). However, conductivity measurements of this cross-linked copolymer also showed reduced long-term chemical stability under alkaline conditions.

[0011]

[0012] [Prior Art Literature]

[0013] (Patent Document 1) Korean Registered Patent No. 10-2184530

[0014] (Patent Document 2) Chinese Registered Patent No. 109265715

[0015] (Non-patent Document 1) Zhihua Wang, Ziming Li, Nanjun Chen, Chuanrui Lu, Fanghui Wang, Hong Zhu, Crosslinked poly (2,6-dimethyl-1,4-phenylene oxide) polyelectrolyte enhanced with poly (styrene-b-(ethylene-co-butylene)-b-styrene) for anion exchange membrane applications, J. Membr. Sci.564 (2018), 492-500.

[0016] (Non-patent Document 2) Hybrid anion exchange membrane with adjustable ion transport channels designed by compounding SEBS and homo-polystyrene,J. Appl. Polm. Sci.138 (2021), e50540

[0017]

[0018] The present invention aims to provide a novel crosslinked copolymer that has excellent stability under alkaline conditions and can be suitably used as an anion exchange membrane for water electrolysis.

[0019]

[0020] According to one embodiment of the present invention, a crosslinked copolymer is provided, comprising a first chain represented by the following chemical formula 1; and a second chain represented by the following chemical formula 2:

[0021] [Chemical Formula 1]

[0022]

[0023] In the above chemical formula 1,

[0024] b stands for block,

[0025] The sum of q1 to q6 is 1 to 30,000,

[0026] The sum of q7 and q8 is 10 to 15,000,

[0027] A1 to A6 are each independently hydrogen; -(CH2) x -T; or -(CH2) x -Q, but at least one of A1 to A6 is -(CH2) x -Q,

[0028] T is , , , , or And,

[0029] Q is any one of the crosslinking groups represented by the following chemical formulas 3-1 to 3-4,

[0030] x is an integer from 1 to 10, each independently,

[0031] [Chemical Formula 2]

[0032]

[0033] In the above chemical formula 2,

[0034] The sum of w1 and w2 is 1 to 30,000,

[0035] B1 and B2 are each independently hydrogen; or -C(R a )(R b )-(CH2) y -Q, but at least one of B1 to B2 is -C(R a )(R b )-(CH2) y -Q,

[0036] R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms,

[0037] y is an integer from 1 to 10, each independently,

[0038] Q is any one of the crosslinking groups represented by the following chemical formulas 3-1 to 3-4,

[0039] [Chemical Formula 3-1]

[0040]

[0041] [Chemical Formula 3-2]

[0042]

[0043] In the above chemical formula 3-2,

[0044] n1 is an integer from 1 to 10,

[0045] R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms,

[0046] [Chemical Formula 3-3]

[0047]

[0048] In the above chemical formula 3-3,

[0049] n2 is an integer from 1 to 10,

[0050] [Chemical Formula 3-4]

[0051]

[0052] In the above chemical formula 3-4,

[0053] n3 is an integer from 1 to 10,

[0054] In the above chemical formulas 3-1 to 3-4,

[0055] M1 is a bond with chemical formula 2,

[0056] M2 is a bond with chemical formula 1.

[0057]

[0058] According to another embodiment of the present invention, a method for producing a crosslinked copolymer is provided, comprising the step of crosslinking a first polymer represented by the following chemical formula 1-1 and a second polymer represented by the following chemical formula 2-1 in the presence of a functionalizing agent:

[0059] [Chemical Formula 1-1]

[0060]

[0061] In the above chemical formula 1-1,

[0062] b stands for block,

[0063] The sum of q1 to q6 is 1 to 30,000,

[0064] The sum of q7 and q8 is 10 to 15,000,

[0065] A'1 to A'6 are each independently hydrogen or -(CH2) x -X'1,

[0066] x is an integer from 1 to 10,

[0067] X'1 is each independently a halogen,

[0068] [Chemical Formula 2-1]

[0069]

[0070] In the above chemical formula 2-1,

[0071] The sum of w1 and w2 is 1 to 30,000,

[0072] B'1 to B'2 are each independently hydrogen or -C(R a )(R b )-(CH2) y -X'2,

[0073] R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms,

[0074] y is an integer from 1 to 10,

[0075] X'2 is , , , or And,

[0076] n1 to n3 are each independently integers from 1 to 10,

[0077] R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms.

[0078]

[0079] In addition, according to another embodiment of the present invention, a method for producing a crosslinked copolymer is provided, comprising: a step of producing a crosslinked copolymer by crosslinking a first polymer represented by the chemical formula 1-1 and a second polymer represented by the chemical formula 2-1; and a step of reacting the crosslinked copolymer with a functionalizing agent.

[0080]

[0081] The crosslinked copolymer of the present invention exhibits excellent electrical conductivity and excellent chemical stability under alkaline conditions. Therefore, the crosslinked copolymer of the present invention can be suitably used as an anion exchange membrane for water electrolysis.

[0082]

[0083] Figure 1 shows the results of alkaline resistance tests of anion exchange membranes manufactured in Examples 1 and 2 together with the results of Example 9 described in Figure 2 of Chinese registered patent No. 109265715.

[0084]

[0085] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0086] In this specification, it should be understood that terms such as “include,” “comprising,” or “having” are intended to specify the presence of a feature, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, steps, components, or combinations thereof.

[0087] In this specification, and means a bond that connects to another substituent.

[0088] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated and described in detail below. However, this is not intended to limit the present invention to specific disclosed forms, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0089] Hereinafter, the present invention will be described in detail.

[0090]

[0091] The crosslinked copolymer of the present invention includes a structure in which a first chain derived from poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) and a second chain derived from polystyrene are crosslinked via a crosslinking group represented by any one of Chemical Formulas 3-1 to 3-4.

[0092]

[0093] Due to the above structural characteristics, the crosslinked copolymer exhibits high ion exchange capacity, hydroxide ion conductivity, moisture content, and swelling ratio, and exhibits higher density and lower hydrogen permeability than conventional ion exchange membranes, making it suitable for use as an anion exchange membrane for water electrolysis to produce high-purity hydrogen and oxygen. In addition, it exhibits excellent chemical stability under alkaline conditions, making it stable for long-term operation of water electrolysis cells.

[0094]

[0095] q1 to q8 in the above chemical formula 1 and w1 to w4 in the chemical formula 2 represent the number of each repeating unit.

[0096]

[0097] In the above first edition, the sum of q1 to q6 is 1 to 30,000, and the sum of q7 and q8 is 10 to 15,000.

[0098]

[0099] Preferably, the sum of q1 to q6 may be 10 or more, or 20 or more, and 25,000 or less, or 20,000 or less.

[0100]

[0101] Preferably, the sum of q7 and q8 may be 30 or more, or 50 or more, and 12,000 or less, or 10,000 or less.

[0102]

[0103] Preferably, q1 to q6 may each independently be 0 or more, 1 or more, or 5 or more, and 5,000 or less, 4,800 or less, or 4,500 or less.

[0104]

[0105] In one embodiment, one, two, three, four, or five of A1 to A6 can be hydrogen.

[0106]

[0107] In one embodiment, one, two, three, four, or five of A1 to A6 are -(CH2) x -It could be T.

[0108]

[0109] In one embodiment, one, two, three, four, or five of A1 to A6 are -(CH2) x -It could be Q.

[0110]

[0111] In the above second edition, the sum of w1 to w2 is 1 to 30,000.

[0112]

[0113] Preferably, the sum of w1 and w2 may be 5 or more, or 10 or more, and 25,000 or less, or 20,000 or less.

[0114]

[0115] Preferably, w1 to w2 may each independently be 0 or more, 1 or more, or 2 or more, and 10,000 or less, 9,000 or less, or 8,000 or less.

[0116]

[0117] The above x and y are each independently integers from 1 to 10. In this way, by having the length of the carbon chain between the aromatic ring of the SEBS-based chain and the polystyrene-based chain and the amine group of the cross-linked chain within an appropriate range, further improved chemical stability and durability can be exhibited.

[0118]

[0119] In one implementation, x and y can each independently be an integer greater than or equal to 2, or greater than or equal to 3, or greater than or equal to 4, and less than or equal to 10, less than or equal to 9, or less than or equal to 8, or less than or equal to 7, or less than or equal to 6.

[0120]

[0121] In one implementation, R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms. The aliphatic hydrocarbon group may be alkyl, alkenyl, or alkyl.

[0122]

[0123] Preferably R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and specifically, the aliphatic hydrocarbon group having 1 to 3 carbon atoms is -(CH2) x1 -CH3, and x1 can be an integer from 0 to 2.

[0124]

[0125] In one embodiment, one of B1 and B2 is hydrogen, and the other is -C(R a )(R b )-(CH2) y -It could be Q.

[0126]

[0127] The above n1 to n3 are each independently integers from 1 to 10. Specifically, the above n1 to n3 may be integers of 2 or more, or 3 or more, or 4 or more, and 9 or less, or 8 or less, or 7 or less, or 6 or less.

[0128]

[0129] The above R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms. Preferably, R1 to R4 can each independently be methyl, ethyl, n-propyl, isopropyl, n-butyl, cyclopentyl, or cyclohexyl.

[0130]

[0131] Chemical formulae 3-1 to 3-4 are crosslinking groups, one side of each crosslinking group is bonded to the first chain, and the other side is bonded to the second chain. Accordingly, a crosslinked copolymer according to one embodiment of the present invention may include a structure represented by the following chemical formula 3:

[0132] [Chemical Formula 3]

[0133]

[0134] In the above chemical formula 3,

[0135] b, q1 to q8, w1 to w2, R a , R b , x, y, T, and Q are as defined in Chemical Formula 1 and Chemical Formula 2.

[0136]

[0137] In one embodiment, the sum of q1 and q4 of the above chemical formula 3 may be an integer greater than or equal to 0 and less than or equal to 6,100, and preferably an integer greater than or equal to 0 and less than or equal to 1,100.

[0138]

[0139] In one embodiment, the sum of q2 and q5 of the above chemical formula 3 may be an integer greater than or equal to 1 and less than or equal to 8,700, and preferably an integer greater than or equal to 1 and less than or equal to 2,100.

[0140]

[0141] In one embodiment, the sum of q3 and q6 of the above chemical formula 3 may be an integer greater than or equal to 0 and less than or equal to 8,600, and preferably an integer greater than or equal to 0 and less than or equal to 1,900.

[0142]

[0143] In one embodiment, the sum of q7 and q8 of the above chemical formula 3 may be an integer of 15 or more and 15,000 or less, and preferably an integer of 260 or more and 3,800 or less.

[0144]

[0145] In one embodiment, the percentage of the sum of q2 and q5 relative to the sum of q2, q3, q5, and q6 in the above chemical formula 3 may be 10% or more, 20% or more, 30% or more, or 40% or more, and 99% or less, 95% or less, 90% or less, or 85% or less.

[0146]

[0147] In one embodiment, w1 of the chemical formula 3 may be an integer of 0 or more and 8,000 or less, and preferably an integer of 140 or more and 1,800 or less.

[0148]

[0149] In one embodiment, w2 of the chemical formula 3 may be an integer of 1 or more and 10,000 or less, and preferably an integer of 1 or more and 2,100 or less.

[0150]

[0151] The cross-linked copolymer described above has a positively charged quaternary ammonium group, so that only anions can be selectively passed through. Therefore, the cross-linked copolymer can be applied as an anion exchange membrane. The counter ion (anion) group for the cation (quaternary ammonium group) of the cross-linked copolymer is OH - , Br - , Cl - or HCO3 - It can be, and preferably OH - It could be.

[0152]

[0153] Accordingly, according to one embodiment of the present invention, a polymer membrane comprising the crosslinked copolymer is provided.

[0154]

[0155] The polymer membrane comprising the cross-linked copolymer may have a thickness of 10 μm or more. While a thicker polymer membrane has the advantage of lower hydrogen permeability, it also has the disadvantage of higher electrical resistance. Therefore, the thickness of the polymer membrane is preferably no more than 300 μm, and the thickness of the polymer membrane can be appropriately adjusted within the above-described range, taking into account the desired effect.

[0156]

[0157] The polymer membrane, which includes the cross-linked copolymer described above, can exhibit higher output characteristics when used in a water electrolysis tank. Furthermore, the polymer membrane has a high density and low hydrogen permeability, making it advantageous for the production of high-purity hydrogen and oxygen.

[0158]

[0159] Accordingly, a polymer membrane having the above properties can be suitably used as an anion exchange membrane for water electrolysis.

[0160]

[0161] The above crosslinked copolymer can be produced, for example, according to a production method including a step of crosslinking a first polymer represented by the following chemical formula 1-1 and a second polymer represented by the following chemical formula 1-2 in the presence of a functionalizing agent:

[0162] [Chemical Formula 1-1]

[0163]

[0164] In the above chemical formula 1-1,

[0165] b stands for block,

[0166] The sum of q1 to q6 is 1 to 30,000,

[0167] The sum of q7 and q8 is 10 to 15,000,

[0168] A'1 to A'6 are each independently hydrogen or -(CH2) x -X'1,

[0169] x is an integer from 1 to 10,

[0170] X'1 is each independently a halogen,

[0171] [Chemical Formula 2-1]

[0172]

[0173] In the above chemical formula 2-1,

[0174] The sum of w1 and w2 is 1 to 30,000,

[0175] B'1 to B'2 are each independently hydrogen or -C(R a )(R b )-(CH2) y -X'2,

[0176] R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms,

[0177] y is an integer from 1 to 10,

[0178] X'2 is , , , or And,

[0179] n1 to n3 are each independently integers from 1 to 10,

[0180] R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms.

[0181]

[0182] Preferably, at least one of B'1 to B'2 of the above chemical formula 2-1 is -C(R a )(R b )-(CH2) y -X'2.

[0183]

[0184] Alternatively, the crosslinked copolymer may be manufactured according to a manufacturing method including a step of crosslinking the first polymer and the second polymer to manufacture a crosslinked copolymer; and a step of reacting the crosslinked copolymer with a functionalizing agent.

[0185]

[0186] In this specification, the “functionalizing agent” means a compound that reacts with a polymer and a crosslinked copolymer to impart an ammonium group to the polymer and the crosslinked copolymer.

[0187]

[0188] q1 to q8, w1 to w2, x, y, R of the above chemical formula 1-1 and chemical formula 2-1 a , R b , the preferred ranges of R1 to R4, and n1 to n3 are as described above in Chemical Formula 1.

[0189]

[0190] The above X'1 and X'2 are each independently F, Cl, Br, or I, and preferably Br.

[0191]

[0192] The first polymer represented by the above chemical formula 1-1 is a poly(styrene-b-ethylene-co-butylene-b-styrene) polymer, and the method for producing the first polymer is not particularly limited, but as an example, it can be produced through a Friedel-Crafts acylation reaction of SEBS and a reduction reaction of a carbonyl group.

[0193]

[0194] The acyl halide used in the above acylation reaction is selected considering the number of x desired. Specifically, the acyl halide is XR-COCl (X is a halogen, R is C 1-9 Alkanoyl chlorides having a halogen group at the end of the alkyl chain, represented by alkyl, can be used.

[0195]

[0196] Aluminum chloride (AlCl3) can be used as a catalyst for the acylation reaction, and the reaction can be performed at 20 to 30°C for 8 to 24 hours.

[0197]

[0198] The reduction reaction of the above carbonyl group can be performed using any method known in the art without limitation. For example, triethylsilane and trifluoroacetic acid can be added and reacted at 90 to 120°C for 20 to 30 hours to reduce the carbonyl group. Through this reaction, a poly(styrene-b-ethylene-co-butylene-b-styrene) polymer represented by the above chemical formula 1-1 can be obtained.

[0199]

[0200] The above poly(styrene-b-ethylene-co-butylene-b-styrene) copolymer preferably contains 30 mol or more, 40 mol or more, 50 mol or more, 55 mol or more, or 60 mol or more, and 90 mol or less, 85 mol or less, 80 mol or less, or 75 mol or less of halogen groups per 100 mol of styrene repeating units. The molar number of halogen groups per styrene repeating unit can be controlled by controlling the molar number of acyl halide relative to the molar number of styrene in the SEBS polymer during the acylation reaction.

[0201]

[0202] The second polymer represented by the above chemical formula 2-1 is a styrene-based polymer, and the method for its production is not limited, but for example, it can be produced by sequentially performing a Friedel-Crafts acylation reaction of polystyrene, a reduction reaction of a carbonyl group, and an amination reaction with a crosslinked amine.

[0203]

[0204] The acylation reaction and carbonyl group reduction reaction of the above styrene polymer can be carried out in the same manner as described in the method for producing the first polymer. Next, an amination reaction is performed in which the thus obtained styrene polymer containing a haloalkyl group on the benzene ring is reacted with a crosslinking amine.

[0205]

[0206] In the above amination reaction, the crosslinking amine may be used in an amount of 2 equivalents or more, or 3 equivalents or more, but no more than 5 equivalents, relative to 1 equivalent of the halogen group contained in the styrene polymer. The crosslinking amine is a compound having two amine groups, and specifically, at least one selected from the group consisting of dimethylamine and compounds represented by the following chemical formulae 4-1 to 4-3 may be used.

[0207] [Chemical Formula 4-1]

[0208] R'1R'2N-(CH2) n’1 -N R'3R'4

[0209] In the above chemical formula 4-1,

[0210] n'1 is an integer from 1 to 10,

[0211] R'1 to R'4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms,

[0212] [Chemical Formula 4-2]

[0213]

[0214] In the above chemical formula 4-2,

[0215] n'2 is an integer from 1 to 10,

[0216] [Chemical Formula 4-3]

[0217]

[0218] In the above chemical formula 4-3,

[0219] n'3 is an integer from 1 to 10.

[0220]

[0221] The solvent used in the above amination reaction is not particularly limited as long as it can dissolve the reactants and products, and for example, at least one selected from the group consisting of methanol, ethanol, propanol, acetone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and water may be used. The amount of the solvent is not particularly limited, but for example, it may be used in an amount of 5 to 10 parts by weight per 1 part by weight of the styrene-based polymer to be reacted.

[0222]

[0223] Since the first polymer contains a halogen group and the second polymer contains a tertiary amine group, the two polymers can be easily crosslinked through a nucleophilic substitution reaction without a separate crosslinking agent.

[0224]

[0225] At this time, it is preferable that the second polymer be used in an amount of 10 mol or more, or 20 mol or more, or 30 mol or more, or 40 mol or more, but 80 mol or less, 70 mol or less, or 60 mol or less, or 50 mol or less, per 100 mol of halogen groups contained in the first polymer. When the above molar ratio is satisfied, excellent hydroxide ion conductivity and mechanical properties can be exhibited.

[0226]

[0227] Crosslinking of the first polymer and the second polymer to obtain a crosslinked copolymer represented by the above chemical formula 1 can be performed in the presence of a functionalizing agent.

[0228]

[0229] When crosslinking of the first polymer and the second polymer is performed in the presence of a functionalizing agent, an ammonization reaction in which all halogen groups remaining in the crosslinked copolymer are replaced with ammonium groups can occur simultaneously with the crosslinking reaction.

[0230]

[0231] Previously, no solvent was known that could simultaneously dissolve a polymer containing a halogen group, a polymer containing an amine group, and a crosslinked polymer containing an ammonium group formed by their crosslinking. Therefore, a method was used in which the polymers were first crosslinked, a membrane was prepared from the resulting reaction mixture, and then the membrane was impregnated with trimethylamine to initiate the ammonification reaction. However, this method had the disadvantage of being unable to form continuous membranes, making it difficult to commercialize.

[0232]

[0233] Accordingly, the present inventors studied a method capable of performing crosslinking of a first polymer and a second polymer and simultaneously performing an ammonium reaction, and as a result, a method capable of performing crosslinking of a first polymer and a second polymer and simultaneously performing an ammonium reaction was studied in ethyl acetate, chloroform, dichloromethane, trichloromethane, carbon tetrachloride, 1,2-dichloroethane, acetonitrile, acetic acid, tetrahydrofuran, 1,4-dioxane, diethyl ether, n-pentane, n-hexane, n-heptane, cyclohexane, cyclohexanone, cyclohexanol, benzene, toluene, o-xylene, m-xylene, p-xylene, chlorobenzene, o-dichlorobenzene, trichlorobenzene, anisole, acetophenone, nitrobenzene, benzonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, It was confirmed that the crosslinking and ammonium reaction of the first polymer and the second polymer can proceed simultaneously in a mixed solvent of two or more selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-2-butanol, acetone, 2-butanone, 2-pentanone, 3-pentanone, and water. Accordingly, according to the production method of the present invention, a polymer film can be mass-produced by continuously producing a film from the reaction mixture obtained after the reaction.

[0234]

[0235] For example, in the crosslinking step of the first polymer and the second polymer, a mixed solvent containing 10 to 100 parts by weight of ethanol per 100 parts by weight of chloroform or toluene may be used, but is not limited thereto, and the solvent combination may be selected in consideration of the structural characteristics of the first polymer and the second polymer.

[0236]

[0237] As the functionalizing agent, at least one selected from the group consisting of trimethylamine, triethylamine, N-methylpiperidine, N-methylpyrrolidine, and 1,2-dimethylimidazole can be used.

[0238]

[0239] The functionalizing agent is preferably added in an amount of 0.1 to 85 parts by weight, or 1 to 33 parts by weight, based on 100 parts by weight of the first polymer and the second polymer. At this time, the functionalizing agent may be added in the form of a solution dissolved in a solvent, and the solvent may be at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and water. The amount of the solvent is not particularly limited, but for example, 100 to 400 parts by weight of the solvent may be used based on 100 parts by weight of the functionalizing agent.

[0240]

[0241] When performing a crosslinking reaction in the presence of a functionalizing agent as described above, the reaction temperature may be 20°C to 70°C, or 20°C to 50°C; and the reaction time may be 30 minutes to 120 hours, or 2 hours to 48 hours.

[0242]

[0243] Alternatively, the crosslinked copolymer represented by the chemical formula 1 may be obtained by first crosslinking the first polymer and the second polymer, and then reacting the obtained crosslinked copolymer with a functionalizing agent to ammoniumize the remaining halogen groups. In this case, the reaction temperature of the crosslinking step may be 20°C to 70°C, or 20°C to 50°C; and the reaction time may be 30 minutes to 120 hours, or 2 hours to 48 hours.

[0244]

[0245] And, the ammonium treatment of the obtained crosslinked copolymer can be carried out by adding 0.1 to 85 parts by weight, or 1 to 33 parts by weight, of a functionalizing agent to 100 parts by weight of the crosslinked copolymer and stirring at 30 to 60°C for 10 to 30 hours, preferably at 40 to 50°C for 20 to 30 hours. At this time, the functionalizing agent can be added in the form of a solution dissolved in a solvent, and as the solvent, at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and water can be used. The amount of solvent is not particularly limited, but for example, 10 to 300 parts by weight of solvent can be used for 100 parts by weight of functionalizing agent.

[0246]

[0247] As described above, in the present invention, a halogen group is introduced into a first polymer and reacted with a second polymer containing an amine group to produce a crosslinked copolymer, thereby suppressing a reaction between the first polymers or the second polymers and quantitatively crosslinking the first polymer and the second polymer. Accordingly, the crosslinked copolymer does not undergo phase separation during membrane production and can achieve a consistent quality.

[0248]

[0249] In addition, according to the above method, a crosslinked copolymer can be produced more easily and with a high yield, thereby increasing the productivity of the process and reducing costs.

[0250]

[0251] Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention solely to these examples.

[0252]

[0253] [Example]

[0254] Unless otherwise stated in the following examples and comparative examples, the reaction pressure is atmospheric pressure (760±10 torr). In addition, 'room temperature' means 25°C.

[0255]

[0256] Example 1

[0257] (1) Manufacturing of Reduced-SEBS (mSEBS)

[0258] (1-1) Preparation of Acylated-SEBS (Ac-SEBS)

[0259]

[0260] (In the above, the sum of q1 to q6 is 400, the sum of q7 and q8 is 1000,

[0261] The sum of q1 and q4 is 10% of the sum of q1 to q6, and q2, q 3, q 5, and the sum of q6 is 90% of the sum of q1 to q6, and the sum of q7 and q8 is 72% of the sum of q1 to q8.)

[0262] In a two-necked round-bottom flask combined with a dropping funnel, 5 g (1 equivalent of styrene) of poly(styrene-ethylene-butylene-styrene) (SEBS, Kraton A1535H) and 150 mL of dichloromethane (DCM) (30 mL per 1 g of polymer) were added and completely dissolved to prepare a polymer solution.

[0263] Separately, a mixture of 4.02 g (1.1 equivalents) of aluminum chloride and 4.61 mL (1.1 equivalents) of 6-bromohexanoyl chloride dissolved in 50 mL of dichloromethane was prepared, and this was slowly (over 2 hours for 80 mL) added dropwise to the stirring polymer solution in a dropping funnel. After the addition of the mixture was completed, the reaction was carried out at room temperature with stirring for 24 hours.

[0264] 800 ml of ethanol was added to the reaction mixture to precipitate the polymer, and the precipitated polymer was washed twice with ethanol and then dried in a vacuum oven at room temperature for 12 hours to obtain Ac-SEBS.

[0265]

[0266] (1-2) Preparation of Reduced-SEBS (mSEBS)

[0267]

[0268] In a two-necked round-bottom flask, 5 g of the above Ac-SEBS (1 equivalent of Br functional group) and 125 mL of chloroform (HPLC grade) (25 mL per 1 g of polymer) were added to dissolve the polymer.

[0269] After the polymer was completely dissolved, 18.83 ml (10 equivalents) of triethylsilane was added, followed by 45.11 mL (50 equivalents) of trifluoroacetic acid (TFA). A reflux condenser was attached to the flask, the temperature was raised to 105°C, and the reaction was carried out with stirring for 48 hours.

[0270] The reaction mixture was cooled to room temperature, 150 ml of 1 M KOH aqueous solution was added, and the mixture was stirred at 500 rpm for 30 minutes. The reaction mixture was then separated using a separating funnel to obtain the lower layer (chloroform layer), which was precipitated in 800 ml of methanol. The precipitated polymer was washed four times with methanol, and the obtained polymer was dried at room temperature under vacuum for 24 hours to obtain mSEBS.

[0271]

[0272] (2) Manufacturing of PS-DMA

[0273] (2-1) Preparation of Acylated-PS (Ac-PS)

[0274]

[0275] (In the above, w1 and w2 are each 1000.)

[0276] A polymer solution was prepared by adding 12 g (1 equivalent of styrene) of polystyrene (PS, Aldrich 430102), 216 mL of dichloromethane (18 mL per 1 g of polymer), and 108 mL of nitrobenzene (9 mL per 1 g of polymer) to a round-bottom flask and completely dissolving them.

[0277] Separately, a mixture of 11.5 g (0.8 equivalents) of aluminum chloride and 22.14 g (0.9 equivalents) of 6-bromohexanoyl chloride in 80 mL of dichloromethane was prepared, added to the polymer solution while stirring, and washed with 28 mL of dichloromethane. After the addition of the mixture, the reaction was carried out while stirring at room temperature for 24 hours.

[0278] The reaction mixture was slowly added to 1 L of methanol to precipitate the polymer, and the solution was removed. A solution of the precipitated polymer dissolved in chloroform (15 mL per 1 g of polymer) was placed in a dropping funnel, and the polymer was precipitated while adding methanol in an amount 5 times that of the chloroform used little by little, and the remaining solution was removed by filtering. The obtained polymer was dried in a vacuum oven at room temperature for 12 hours to obtain Ac-PS.

[0279]

[0280] (2-2) Manufacturing of Reduced-PS (Re-PS)

[0281]

[0282] 23 g of Ac-PS (1 equivalent of Br functional group) and 460 mL of chlorobenzene (20 mL per 1 g of polymer) were added to a round-bottom flask to dissolve the polymer.

[0283] After the polymer was completely dissolved, 100 mL (10 equivalents) of triethylsilane was added, followed by 96 mL (20 equivalents) of trifluoroacetic acid (TFA). A reflux condenser was attached to the flask, the temperature was raised to 105°C, and the reaction was carried out while stirring for 48 hours.

[0284] The reaction mixture was cooled to room temperature, 150 ml of 2 M KOH aqueous solution was added, and stirred for 30 minutes. After that, the reaction mixture was separated using a separatory funnel to obtain the supernatant (chlorobenzene layer), and the supernatant was slowly added to 1 L of methanol to precipitate the polymer, and the solution was removed. After dissolving the obtained polymer in chloroform (15 mL per 1 g of polymer), a solution was placed in a dropping funnel, and the polymer was precipitated while adding methanol in an amount 5 times that of the chloroform used little by little, and the remaining solution was filtered to remove the remaining solution. The obtained polymer was dried in a vacuum oven at room temperature for 12 hours to obtain Re-PS.

[0285]

[0286] (2-3) Preparation of PS-DMA

[0287]

[0288] 25 g of Re-PS (1 equivalent of Br functional group) and 250 mL of NMP (N-Methyl-2-pyrollidone) (10 mL per 1 g of polymer) were added to a round-bottom flask, and the polymer was dissolved at 70°C.

[0289] After the polymer was completely dissolved, 106.4 ml (3 equivalents, 2 M THF solution) of DMA (Dimethylamine) was added and the reaction was allowed to proceed for more than 12 hours while maintaining the temperature at 70°C.

[0290] The reaction mixture was cooled to room temperature and precipitated in a solution of methanol and 1 M KOH aqueous solution in a 3:1 volume ratio. The precipitated polymer was washed with methanol at least four times. The obtained polymer was dried in a vacuum oven for 12 hours to obtain PS-DMA.

[0291]

[0292] (3) Preparation of cross-linked SEBS-PS membrane

[0293]

[0294] The above mSEBS and PS-DMA were placed in a 70 ml vial, and a mixed solvent of 80 wt% chloroform and 20 wt% ethanol was added, and the mixture was stirred until the entire polymer was completely dissolved at a concentration of 20 wt%. mSEBS was used at a ratio of 150 wt% to PS-DMA. 7.5 g of the completely dissolved polymer solution was stirred to induce cross-linking at room temperature. 0.28 g of TMA was then added to the cross-linked polymer solution to induce ammonium treatment. The polymer solution was degassed and formed into a 500 μm thick film on a glass plate. The membrane was then dried at 80°C for 24 hours to obtain an anion-exchange membrane with a thickness of 70 μm.

[0295]

[0296] Example 2

[0297] (1) Preparation of cross-linked SEBS-PS membrane

[0298]

[0299]

[0300] mSEBS and PS-DMA, prepared in the same manner as in Example 1, were placed in a 70 ml vial, and a mixed solvent of 75 wt% toluene and 25 wt% ethanol was added, and the mixture was stirred until the entire polymer was completely dissolved at a concentration of 20 wt%. mSEBS was used at a ratio of 200 wt% to PS-DMA. 7.5 g of the completely dissolved polymer solution was stirred to induce cross-linking at room temperature. 0.42 g of TMA was then added to the cross-linked polymer solution to induce ammonium treatment. The polymer solution was degassed and formed into a 500 μm thick film on a glass plate. The membrane was then dried at 80°C for 24 hours to obtain an anion exchange membrane with a thickness of 70 μm.

[0301]

[0302] Experimental Example: Alkali Resistance Test of Anion Exchange Membrane

[0303] A portion of the anion exchange membrane manufactured in Examples 1 and 2 was taken as a sample and an alkaline resistance test was performed.

[0304] The alkaline resistance test was performed in the same manner as the comparative example of Chinese Patent No. 109265715 in a 2M NaOH aqueous solution at 60°C. The specific test method is as follows.

[0305] Ionic conductivity was measured using a BT-512 membrane analyzer from Bekkech. At least three membrane samples, each 0.7 cm wide and 4 cm long, were prepared. The samples were immersed in a 2 M NaOH aqueous solution and stored at 60°C. After a certain period of time, the samples were removed from the NaOH aqueous solution and washed with distilled water. After measuring the width and thickness of the samples, they were attached to a 4-probe cell, immersed in distilled water bubbled with an inert gas such as nitrogen or argon, and connected to the instrument. National Instruments LabVIEW 2018 was used as the ionic conductivity measurement program, and ionic conductivity was measured at 60°C. The average value measured for three or more samples taken from the same anion exchange membrane was reported as the result.

[0306]

[0307] The results of the alkali resistance test performed at 60°C in 2M NaOH for the anion exchange membrane of Example 1 are as shown in Table 1 below.

[0308] time (h)conductivity @60°C(mS / cm)conductivity change(%)060.64100.0010062.55103.1520060.5699.8750060.1499.18

[0309]

[0310] The results of the alkali resistance test performed at 60°C in 2M NaOH for the anion exchange membrane of Example 2 are as shown in Table 2 below.

[0311]

[0312] time (h)conductivity @60°C(mS / cm)conductivity change(%)065.60100.0010063.6997.0920060.8992.8250061.4693.69

[0313]

[0314] Referring to Figure 2 of Chinese registered patent No. 109265715, it was confirmed that the ionic conductivity of the anion exchange membrane of Chinese registered patent Example 9 in an alkaline resistance test at 2M NaOH 60°C initially decreased by 25% from about 32 mS / cm to about 23 mS / cm after 500 hours.

[0315] On the other hand, under the same conditions, the ionic conductivity of the anion exchange membrane of Example 1 decreased by about 0.8% (Table 1), and the ionic conductivity of the anion exchange membrane of Example 2 decreased by about 6.4% (Table 2).

[0316] For comparison, the alkaline resistance test results of the anion exchange membranes of Examples 1 and 2 and the results of Example 9 described in Figure 2 of Chinese Patent No. 109265715 are shown together in Figure 1.

[0317] From the above results, it can be confirmed that the anion exchange membrane using the styrene-based cross-linked copolymer manufactured according to the present invention has excellent chemical stability.

Claims

1. A crosslinked copolymer comprising a first chain represented by the following chemical formula 1; and a second chain represented by the following chemical formula 2: [Chemical Formula 1] In the above chemical formula 1, b stands for block, The sum of q1 to q6 is 1 to 30,000, The sum of q7 and q8 is 10 to 15,000, A1 to A6 are each independently hydrogen; -(CH2) x -T; or -(CH2) x -Q, but at least one of A1 to A6 is -(CH2) x -Q, T is , , , , or And, Q is any one of the crosslinking groups represented by the following chemical formulas 3-1 to 3-4, x is an integer from 1 to 10, each independently, [Chemical Formula 2] In the above chemical formula 2, The sum of w1 and w2 is 1 to 30,000, B1 and B2 are each independently hydrogen; or -C(R a )(R b )-(CH2) y -Q, but at least one of B1 to B2 is -C(R a )(R b )-(CH2) y -Q, R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, y is an integer from 1 to 10, each independently, Q is any one of the crosslinking groups represented by the following chemical formulas 3-1 to 3-4, [Chemical Formula 3-1] [Chemical Formula 3-2] In the above chemical formula 3-2, n1 is an integer from 1 to 10, R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms, [Chemical Formula 3-3] In the above chemical formula 3-3, n2 is an integer from 1 to 10, [Chemical Formula 3-4] In the above chemical formula 3-4, n3 is an integer from 1 to 10, In the above chemical formulas 3-1 to 3-4, M1 is a bond with chemical formula 2, M2 is a bond with chemical formula 1.

2. In paragraph 1, A crosslinked copolymer, wherein x and y are each independently integers from 2 to 10.

3. In paragraph 1 or 2, R a and R b A crosslinked copolymer, wherein each independently represents hydrogen or an aliphatic hydrocarbon group having 1 to 3 carbon atoms.

4. In any one of paragraphs 1 to 3, A crosslinked copolymer comprising a structure represented by the following chemical formula 3: [Chemical Formula 3] In the above chemical formula 3, b, q1 to q8, w1 to w2, R a , R b , x, y, T, and Q are as defined in paragraph 1.

5. In paragraph 4, A crosslinked copolymer wherein the sum of q1 and q4 is 0 or more and 6,100 or less, the sum of q2 and q5 is 1 or more and 8,700 or less, and the sum of q3 and q6 is 0 or more and 8,600 or less.

6. In paragraph 4 or 5, A crosslinked copolymer wherein w1 is 0 to 8,000 and w2 is 1 to 10,000.

7. In any one of paragraphs 4 to 6, A crosslinked copolymer in which the sum of q2 and q5 is 10 to 99% of the sum of q2, q3, q5, and q6.

8. A polymer membrane comprising a crosslinked copolymer according to any one of claims 1 to 7.

9. An anion exchange membrane for water electrolysis comprising the polymer membrane of Article 8.

10. A method for producing a crosslinked copolymer, comprising a step of crosslinking a first polymer represented by the following chemical formula 1-1 and a second polymer represented by the following chemical formula 2-1 in the presence of a functionalizing agent: [Chemical Formula 1-1] In the above chemical formula 1-1, b stands for block, The sum of q1 to q6 is 1 to 30,000, The sum of q7 and q8 is 10 to 15,000, A'1 to A'6 are each independently hydrogen or -(CH2) x -X'1, x is an integer from 1 to 10, X'1 is each independently a halogen, [Chemical Formula 2-1] In the above chemical formula 2-1, The sum of w1 and w2 is 1 to 30,000, B'1 to B'2 are each independently hydrogen or -C(R a )(R b )-(CH2) y -X'2, R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, y is an integer from 1 to 10, X'2 is , , , or And, n1 to n3 are each independently integers from 1 to 10, R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms.

11. A step of preparing a crosslinked copolymer by crosslinking a first polymer represented by the following chemical formula 1-1 and a second polymer represented by the following chemical formula 2-1; and A method for producing a crosslinked copolymer, comprising a step of reacting the crosslinked copolymer with a functionalizing agent: [Chemical Formula 1-1] In the above chemical formula 1-1, b stands for block, The sum of q1 to q6 is 1 to 30,000, The sum of q7 and q8 is 10 to 15,000, A'1 to A'6 are each independently hydrogen or -(CH2) x -X'1, x is an integer from 1 to 10, X'1 is each independently a halogen, [Chemical Formula 2-1] In the above chemical formula 2-1, The sum of w1 and w2 is 1 to 30,000, B'1 to B'2 are each independently hydrogen or -C(R a )(R b )-(CH2) y -X'2, R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, y is an integer from 1 to 10, X'2 is , , , or And, n1 to n3 are each independently integers from 1 to 10, R1 to R4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms.

12. In paragraph 10 or 11, A method for producing a crosslinked copolymer, wherein the functionalizing agent is at least one selected from the group consisting of trimethylamine, triethylamine, N-methylpiperidine, N-methylpyrrolidine, and 1,2-dimethylimidazole.

13. In any one of paragraphs 10 to 12, A method for producing a crosslinked copolymer, wherein the ratio of the first polymer to the second polymer is 1:0.5 to 1:5.

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