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. 10-2024-0081338, 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 SEBS polymer, a relatively stable polystyrene polymer under alkaline conditions, has been proposed (J. Appl. Polm. Sci. 138 (2021), e50540 and Chinese patent 109265715 B). 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 to w4 is 1 to 30,000,

[0035] B1 to B4 are each independently hydrogen; -C(R a )(R b )-(CH2) y -T; or -C(R a )(R b )-(CH2) y -Q, but at least one of B1 to B4 is -C(R a )(R b )-(CH2) y -Q,

[0036] T and Q are as defined in the above chemical formula 1,

[0037] R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms,

[0038] y is an integer from 1 to 10, each independently,

[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] are each independently a bond with chemical formula 1 or chemical formula 2.

[0056]

[0057] 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 and a crosslinking agent:

[0058] [Chemical Formula 1-1]

[0059]

[0060] In the above chemical formula 1-1,

[0061] b stands for block,

[0062] The sum of q1 to q6 is 1 to 30,000,

[0063] The sum of q7 and q8 is 10 to 15,000,

[0064] A'1 to A'6 are each independently hydrogen or -(CH2) x-X'1,

[0065] x is an integer from 1 to 10,

[0066] X'1 is each independently a halogen,

[0067] [Chemical Formula 2-1]

[0068]

[0069] In the above chemical formula 2-1,

[0070] The sum of w1 to w4 is 1 to 30,000,

[0071] B'1 to B'4 are each independently hydrogen or -C(R a )(R b )-(CH2) y -X'2,

[0072] R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms,

[0073] y is an integer from 1 to 10,

[0074] X'2 are each independently a halogen.

[0075]

[0076] In addition, according to another embodiment of the present invention, a method for producing a crosslinked copolymer is provided, comprising the steps of: crosslinking a first polymer represented by the chemical formula 1-1 and a second polymer represented by the chemical formula 2-1 in the presence of a crosslinking agent to produce a crosslinked copolymer; and reacting the crosslinked copolymer with a functionalizing agent.

[0077]

[0078] 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.

[0079]

[0080] 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.

[0081]

[0082] 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.

[0083] 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.

[0084] In this specification, and means a bond that connects to another substituent.

[0085] 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.

[0086] Hereinafter, the present invention will be described in detail.

[0087]

[0088] The crosslinked copolymer of the present invention comprises a first chain derived from poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) and a second chain derived from polystyrene. Specifically, the crosslinked copolymer may comprise at least one of a structure in which the first chain and the first chain are crosslinked via a crosslinking group represented by any one of Chemical Formulae 3-1 to 3-4; a structure in which the first chain and the second chain are crosslinked; and a structure in which the second chain and the second chain are crosslinked. Preferably, the crosslinked copolymer comprises a structure in which the first chain and the second chain are crosslinked to each other.

[0089]

[0090] 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, and thus can be suitably used as an anion exchange membrane for water electrolysis to produce high-purity hydrogen and oxygen. In addition, the crosslinked copolymer exhibits excellent chemical stability under alkaline conditions, and thus can be stably used even in long-term operation of a water electrolysis cell.

[0091]

[0092] 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.

[0093]

[0094] 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.

[0095]

[0096] 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.

[0097]

[0098] 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.

[0099]

[0100] 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.

[0101]

[0102] In one embodiment, one, two, three, four, or five of A1 to A6 can be hydrogen.

[0103]

[0104] In one embodiment, one, two, three, four, or five of A1 to A6 are -(CH2) x -It could be T.

[0105]

[0106] In one embodiment, one, two, three, four, or five of A1 to A6 are -(CH2) x -It could be Q.

[0107]

[0108] The above crosslinked copolymer may include a plurality of first chains, and each first chain may have a different configuration of A1 to A6.

[0109]

[0110] In the above second edition, the sum of w1 to w4 is 1 to 30,000.

[0111]

[0112] Preferably, the sum of w1 to w4 may be 5 or more, or 10 or more, and 25,000 or less, or 20,000 or less.

[0113]

[0114] Preferably, w1 to w4 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.

[0115]

[0116] 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.

[0117]

[0118] 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.

[0119]

[0120] 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.

[0121]

[0122] 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.

[0123]

[0124] In one embodiment, one, two, or three of B1 to B4 can be hydrogen.

[0125]

[0126] In one embodiment, one, two, or three of B1 to B4 are -C(Ra )(R b )-(CH2) y -It could be T.

[0127]

[0128] In one embodiment, one, two, or three of B1 to B4 are -C(R a )(R b )-(CH2) y -It could be Q.

[0129]

[0130] The above crosslinked copolymer may include a plurality of second chains, and each second chain may have a different configuration of B1 to B4.

[0131]

[0132] Chemical formulae 3-1 to 3-4 are cross-linking groups, and both ends of the cross-linking group can be connected to either the first chain or the second chain. That is, the cross-linking group can connect the first chain to the first chain, or the first chain to the second chain, or the second chain to the second chain.

[0133]

[0134] Preferably, the crosslinked copolymer comprises two or more crosslinking groups of Chemical Formulae 3-1 to 3-4, at least one of which may connect the first chain and the second chain. That is, at least one crosslinking group may bind the first chain to one end and bind the second chain to the other end. In this way, the crosslinked copolymer may be one in which the first chain and the second chain are crosslinked to each other.

[0135]

[0136] Preferably, the crosslinked copolymer comprises two or more crosslinking groups of chemical formulae 3-1 to 3-4, at least one of which connects the first chain and the second chain, and at least one of the remaining groups connects the first chain and the first chain.

[0137]

[0138] Preferably, the crosslinked copolymer comprises two or more crosslinking groups of chemical formulae 3-1 to 3-4, at least one of which connects the first chain and the second chain, and at least one of the remaining groups connects the second chain and the second chain.

[0139]

[0140] 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.

[0141]

[0142] 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.

[0143]

[0144] In one embodiment, the crosslinked copolymer may have a structure in which the first chain and the first chain, the first chain and the second chain, and the second chain and the second chain are each crosslinked with the crosslinking group. Accordingly, the crosslinked copolymer may include a structure represented by the following chemical formula 3:

[0145] [Chemical Formula 3]

[0146]

[0147] In the above chemical formula 3,

[0148] b, q1 to q8, w1 to w4, R a , R b , x, y, T, and Q are as defined in Chemical Formula 1 and Chemical Formula 2.

[0149]

[0150] According to one embodiment, the sum of q1 and q4 in each first chain of the chemical formula 3 may be an integer of 0 or more and 7,000 or less, and preferably 40 or more and 1,250 or less.

[0151]

[0152] According to one embodiment, the sum of q2 and q5 in each first chain of the chemical formula 3 may be an integer of 1 or more and 4,400 or less, and preferably 1 or more and 430 or less.

[0153]

[0154] According to one embodiment, in each of the first chains of the chemical formula 3, the sum of q3 and q6 may be an integer of 1 or more and 8,700 or less, and preferably 40 or more and 1,400 or less.

[0155]

[0156] According to one embodiment, in each of the first chains of the chemical formula 3, the sum of q7 and q8 may be an integer of 15 or more and 15,000 or less, and preferably 260 or more and 3,800 or less.

[0157]

[0158] According to one embodiment, in each of the first chains of the above chemical formula 3, the sum of q2 and q5 relative to the sum of q2, q3, q5, and q6 may be 1% or more, or 5% or more, or 10% or more, and 80% or less, or 70% or less, or 60% or less.

[0159]

[0160] According to one embodiment, in each of the first chains of the above chemical formula 3, the sum of q1 and q4 relative to the sum of q1 to q6 may be 1% or more, or 5% or more, or 10% or more, and 80% or less, or 70% or less, or 60% or less.

[0161]

[0162] According to one embodiment, in each of the two chains of the above chemical formula 3, w1 may be an integer of 0 or more and 8,000 or less, and preferably 140 or more and 1,800 or less.

[0163]

[0164] According to one embodiment, in each of the two chains of the above chemical formula 3, the sum of w2 and w4 may be an integer of 1 or more and 5,000 or less, and preferably 1 or more and 610 or less.

[0165]

[0166] According to one embodiment, in each of the two chains of the above chemical formula 3, w3 may be an integer of 5 or more and 10,000 or less, and preferably 130 or more and 2,000 or less.

[0167]

[0168] 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.

[0169]

[0170] Accordingly, according to one embodiment of the present invention, a polymer membrane comprising the crosslinked copolymer is provided.

[0171]

[0172] 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.

[0173]

[0174] 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.

[0175]

[0176] Accordingly, a polymer membrane having the above properties can be suitably used as an anion exchange membrane for water electrolysis.

[0177]

[0178] 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 2-1 in the presence of a functionalizing agent and a crosslinking agent:

[0179] [Chemical Formula 1-1]

[0180]

[0181] In the above chemical formula 1-1,

[0182] b stands for block,

[0183] The sum of q1 to q6 is 1 to 30,000,

[0184] The sum of q7 and q8 is 10 to 15,000,

[0185] A'1 to A'6 are each independently hydrogen or -(CH2) x -X'1,

[0186] x is an integer from 1 to 10,

[0187] X'1 is each independently a halogen,

[0188] [Chemical Formula 2-1]

[0189]

[0190] In the above chemical formula 2-1,

[0191] The sum of w1 to w4 is 1 to 30,000,

[0192] B'1 to B'4 are each independently hydrogen or -C(R a )(R b )-(CH2) y -X'2,

[0193] R a and R b are each independently hydrogen or an aliphatic hydrocarbon group having 1 to 10 carbon atoms,

[0194] y is an integer from 1 to 10,

[0195] X'2 are each independently a halogen.

[0196]

[0197] Alternatively, the crosslinked copolymer may be manufactured according to a manufacturing method including a step of crosslinking the first polymer and the second polymer in the presence of a crosslinking agent to manufacture a crosslinked copolymer; and a step of reacting the crosslinked copolymer with a functionalizing agent.

[0198]

[0199] 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.

[0200]

[0201] q1 to q8, w1 to w4, 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.

[0202]

[0203] The above X'1 and X'2 are each independently F, Cl, Br, or I, and preferably Br.

[0204]

[0205] The first polymer represented by the above chemical formula 1-1 is a poly(styrene-b-ethylene-co-butylene-b-styrene) polymer. The method for producing the first polymer is not particularly limited, but for example, it can be produced through a Friedel-Crafts acylation reaction of SEBS and a reduction reaction of a carbonyl group.

[0206]

[0207] The acyl halide used in the above acylation reaction is selected considering the number of x desired. Specifically, the acyl halide is X''-R-COCl (X'' is 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.

[0208]

[0209] 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.

[0210]

[0211] 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.

[0212]

[0213] 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.

[0214]

[0215] The second polymer represented by the above chemical formula 2-1 is a styrene-based polymer, and the method for its preparation is not limited, but for example, it can be prepared through a Friedel-Crafts acylation reaction and a reduction reaction of a carbonyl group of polystyrene. The acylation reaction and the reduction reaction of a carbonyl group can be carried out by the same method as described in the method for preparing the first polymer.

[0216]

[0217] Both the first polymer and the second polymer contain halogen groups, and crosslinking is achieved through a nucleophilic substitution reaction using a secondary amine or tertiary amine crosslinking agent. That is, the secondary amine or tertiary amine crosslinking agent acts as a crosslinking chain that connects the first polymer and the second polymer.

[0218]

[0219] In the above crosslinking reaction, since the first polymer and the second polymer have the same functional group (halogen group), there is no positional selectivity in the nucleophilic substitution reaction of the crosslinking agent. Therefore, crosslinking occurs not only between the first polymer and the second polymer, but also between the first polymer and the first polymer, and between the second polymer and the second polymer, and as a result, a crosslinked copolymer having the structure of the above chemical formula 3 can be produced.

[0220]

[0221] In the above crosslinking reaction, the ratio of the first polymer to the second polymer may be 1:0.5 or more, or 1:0.7 or more, and 1:5 or less, or 1:4 or less. When the reaction is carried out within this ratio, a better hydroxide ion conductivity can be obtained, and the mechanical properties of the final anion exchange membrane can be controlled by changing the ratio between the polymers, which is preferable.

[0222]

[0223] In the above crosslinking reaction, at least one selected from the group consisting of dimethylamine and compounds represented by the following chemical formulas 4-1 to 4-3 may be used as a crosslinking agent.

[0224] [Chemical Formula 4-1]

[0225] R'1R'2N-(CH2) n’1 -N R'3R'4

[0226] In the above chemical formula 4-1,

[0227] n'1 is an integer from 1 to 10,

[0228] R'1 to R'4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms,

[0229] [Chemical Formula 4-2]

[0230]

[0231] In the above chemical formula 4-2,

[0232] n'2 is an integer from 1 to 10,

[0233] [Chemical Formula 4-3]

[0234]

[0235] In the above chemical formula 4-3,

[0236] n'3 is an integer from 1 to 10.

[0237]

[0238] The above n'1 to n'3 are each independently integers from 1 to 10. Specifically, the above n'1 to n'3 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.

[0239]

[0240] The above R'1 to R'4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms. Preferably, R'1 to R'4 can each independently be methyl, ethyl, n-propyl, isopropyl, n-butyl, cyclopentyl, or cyclohexyl.

[0241]

[0242] The amount of the crosslinking agent added can be appropriately adjusted depending on the desired degree of crosslinking. For example, the crosslinking agent can be added in an amount of 0.02 to 24 parts by weight, or 0.2 to 12 parts by weight, based on a total of 100 parts by weight of the first polymer and the second polymer.

[0243]

[0244] Crosslinking of the first polymer and the second polymer to obtain a crosslinked copolymer including the first chain, the second chain, and the crosslinking group can be performed in the presence of a functionalizing agent together with the secondary amine and tertiary amine crosslinking agents.

[0245]

[0246] 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.

[0247]

[0248] Previously, no solvent was known that could simultaneously dissolve a polymer having a halogen group; a compound containing an amine group, such as the crosslinking agent and functionalizing agent; and a crosslinked polymer having an ammonium group formed by crosslinking and reaction thereof. Therefore, a method was used in which a membrane was first prepared from a reaction mixture obtained by crosslinking the polymer, and then the membrane was impregnated with a functionalizing agent to undergo an ammonium reaction. However, this method had the disadvantage of being difficult to commercialize because continuous membrane formation was impossible.

[0249]

[0250] 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.

[0251]

[0252] The above mixed solvent may be a mixture of two or more of the solvents listed above, and the types and ratios of the mixed solvents are not particularly limited. Accordingly, suitable solvents may be combined and used among the solvents listed above, taking into account smooth dissolution and dispersion of the solute before and after the reaction. For example, the mixed solvent may be a mixed solvent containing 10 to 100 parts by weight of ethanol per 100 parts by weight of chloroform, but is not limited thereto, and the solvent combination may be selected taking into account the structural characteristics of the first polymer, the second polymer, and the crosslinking agent.

[0253]

[0254] 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.

[0255]

[0256] 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.

[0257]

[0258] When preparing the above functionalizing agent solution, the amount of solvent is not particularly limited, but when adding the functionalizing agent simultaneously with the crosslinking agent, the functionalizing agent solution can be prepared using 100 to 400 parts by weight of solvent per 100 parts by weight of the functionalizing agent.

[0259]

[0260] Alternatively, the crosslinked copolymer represented by the above chemical formula 1 may be obtained by first crosslinking the first polymer and the second polymer in the presence of a crosslinking agent, 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.

[0261]

[0262] And, the ammonium treatment of the obtained crosslinked copolymer can be performed 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.

[0263]

[0264] At this time, the functionalizing agent can 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, 10 to 300 parts by weight of the solvent can be used for 100 parts by weight of the functionalizing agent.

[0265]

[0266] 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.

[0267]

[0268] [Example]

[0269] 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.

[0270]

[0271] Example 1

[0272] (1) Manufacturing of Reduced-SEBS (mSEBS)

[0273] (1-1) Preparation of Acylated-SEBS (Ac-SEBS)

[0274]

[0275] (In the above, the sum of q1 to q6 is 400, the sum of q7 and q8 is 1000,

[0276] The sum of q1 and q4 is 40% of the sum of q1 to q6, and q2, q 3, q 5, and the sum of q6 is 60% of the sum of q1 to q6, and the sum of q7 and q8 is 72% of the sum of q1 to q8.)

[0277] 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 (30 mL per 1 g of polymer) were added and completely dissolved to prepare a polymer solution.

[0278] Separately, a mixture of 2.74 g (0.75 equivalents) of aluminum chloride and 3.14 mL (0.75 equivalents) of 6-bromohexanoyl chloride 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, the reaction was carried out at room temperature with stirring for 24 hours.

[0279] 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.

[0280]

[0281] (1-2) Preparation of Reduced-SEBS (mSEBS)

[0282]

[0283] 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.

[0284] 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.

[0285] 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.

[0286]

[0287] (2) Manufacturing of Reduced-PS (mPS)

[0288] (2-1) Preparation of Acylated-PS (Ac-PS)

[0289]

[0290] (In the above, the sum of w1 to w4 is 2000,

[0291] w1 is 40% of the sum of w1 to w4, and the sum of w2 to w4 is 60% of the sum of w1 to w4.)

[0292] 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.

[0293] Separately, a mixture of 13.8 g (0.9 equivalents) of aluminum chloride and 24.6 g (1.0 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.

[0294] 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.

[0295]

[0296] (2-2) Manufacturing of Reduced-PS (mPS)

[0297]

[0298] 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.

[0299] 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 with stirring for 48 hours.

[0300] 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 added little by little to 5 times the volume of methanol used to precipitate the polymer, and the 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 mPS.

[0301]

[0302] (3) Preparation of cross-linked SEBS-PS membrane

[0303]

[0304] The mSEBS and mPS prepared by the above method 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 and mPS were used in a 1:1 ratio. To 8 g of the completely dissolved polymer solution, 0.16 g of trimethylamine (TMA) and 0.076 g of N,N,N',N'-Tetramethyl-1,6-diaminohexane as a crosslinking agent were added, and the mixture was stirred at 45°C for 1 to 2 days to induce ammonium treatment and crosslinking. The polymer solution was cooled to room temperature, degassed, and formed into a film with a thickness of 500 μm on a glass plate. Thereafter, the membrane was dried at 80°C for 24 hours to obtain an anion exchange membrane with a thickness of 70 μm.

[0305]

[0306] Example 2

[0307]

[0308] mSEBS and mPS 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 and mPS were used in a 1:1 ratio. To 8 g of the completely dissolved polymer solution, 0.16 g of TMA and 0.026 g of dimethylamine as a cross-linking agent were added, and the mixture was stirred at room temperature for 1 to 2 days to induce ammonium treatment and cross-linking. The polymer solution was degassed and formed into a film with a thickness of 500 μm on a glass plate. Thereafter, the membrane was dried at 80°C for 24 hours to obtain an anion exchange membrane with a thickness of 70 μm.

[0309]

[0310] Experimental Example: Alkali Resistance Test of Anion Exchange Membrane

[0311] 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.

[0312] First, data was obtained by performing an alkaline resistance test under conditions of 60°C in a 2M NaOH aqueous solution, the same as the example of the comparative Chinese registered patent No. 109265715, and data was obtained by performing a test under conditions of 80°C in a 1M KOH aqueous solution, which is a typical anion exchange membrane alkaline resistance test condition.

[0313] The specific testing method is as follows.

[0314]

[0315] (1) Alkali resistance test at 60℃ for 2M NaOH aqueous solution

[0316] Ionic conductivity was measured using a BT-512 from Bekkech. Three or more anion exchange 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.

[0317]

[0318] (2) Alkali resistance test at 80℃ for 1M KOH aqueous solution

[0319] An alkaline resistance test for a 1M KOH aqueous solution was performed at 80°C in the same manner as in (1) above, except that a 1M KOH aqueous solution was used instead of a 2M NaOH aqueous solution, and the storage temperature and the temperature at the time of measuring the ionic conductivity in the 1M KOH aqueous solution were set to 80°C.

[0320]

[0321] 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.

[0322] time (h)conductivity @60°C(mS / cm)conductivity change(%)064.48100.0010060.7294.1720063.5598.5550060.7494.20

[0323] 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.

[0324] time (h)conductivity @60°C(mS / cm)conductivity change(%)061.55100.0010062.48101.5120061.2099.4350065.87107.02

[0325] The results of the alkali resistance test performed at 80°C in 1M KOH for the anion exchange membrane of Example 1 are as shown in Table 3 below.

[0326] time (h)conductivity @80°C(mS / cm)conductivity change(%)064.48100.0010062.4596.8520063.9599.1850062.0596.23

[0327] Referring to Figure 2 of Chinese registered patent No. 109265715, it was confirmed that the conductivity of the anion exchange membrane of the Chinese registered patent Example 9 in the 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.

[0328] On the other hand, the alkali resistance test results performed on the anion exchange membrane of Example 1 showed that the conductivity decreased by approximately 5.8% after 500 hours in 2M NaOH at 60°C (Table 1), and that the conductivity decreased by approximately 3.8% after 500 hours in 1M KOH at 80°C (Table 3). In addition, the alkali resistance test results performed on the anion exchange membrane of Example 2 showed that the conductivity did not decrease after 500 hours in 2M NaOH at 60°C (Table 2).

[0329] 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.

[0330] 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 to w4 is 1 to 30,000, B1 to B4 are each independently hydrogen; -C(R a )(R b )-(CH2) y -T; or -C(R a )(R b )-(CH2) y -Q, but at least one of B1 to B4 is -C(R a )(R b )-(CH2) y -Q, T and Q are as defined in the above chemical formula 1, 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, [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, are each independently a bond with chemical formula 1 or chemical formula 2.

2. In paragraph 1, A crosslinked copolymer in which the first chain and the second chain are crosslinked to each other.

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

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

5. In paragraph 1, 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 w4, R a , R b , x, y, T, and Q are as defined in paragraph 1.

6. In paragraph 5, In each first edition, the sum of q1 and q4 is 0 to 7,000, the sum of q2 and q5 is 1 to 4,400, and the sum of q3 and q6 is 1 to 8,700. A crosslinked copolymer wherein in each second strand, w1 is 0 to 8,000, the sum of w2 and w4 is 1 to 5,000, and w3 is 5 to 10,000.

7. In paragraph 5 or 6, A crosslinked copolymer in which the sum of q2 and q5 is 1 to 80% 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 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 and a crosslinking 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 to w4 is 1 to 30,000, B'1 to B'4 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 are each independently a halogen.

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 in the presence of a crosslinking agent; 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 to w4 is 1 to 30,000, B'1 to B'4 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 are each independently a halogen.

12. In paragraph 10 or 11, A method for producing a crosslinked copolymer, wherein the crosslinking agent is at least one selected from the group consisting of dimethylamine and a compound represented by the following chemical formula 4-1 to a compound represented by the following chemical formula 4-3: [Chemical Formula 4-1] R1R2N-(CH2) n1 -NR3R4 In the above chemical formula 4-1, n1 is an integer from 1 to 10, R'1 to R'4 are each independently alkyl having 1 to 6 carbon atoms; or cycloalkyl having 3 to 8 carbon atoms, [Chemical Formula 4-2] In the above chemical formula 4-2, n2 is an integer from 1 to 10, [Chemical Formula 4-3] In the above chemical formula 4-3, n3 is an integer from 1 to 10.

13. 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.

14. In paragraph 10 or 11, 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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