Anion exchange membrane comprising cross-linked polymer of SEBS and polyfluorene, and method for manufacturing same

Abstract

The present invention relates to an anion exchange membrane comprising a cross-linked polymer in which polyfluorene is cross-linked with styrene-ethylene-butylene-styrene (SEBS). The anion exchange membrane according to the present invention has excellent mechanical properties and thermal stability while having high ionic conductivity, and can be applied to a water electrolysis device.

Description

Anion exchange membrane comprising a cross-linked polymer of SEBS and polyfluorene and a method for manufacturing the same

[0001] The present invention relates to an anion exchange membrane comprising a cross-linked polymer of SEBS and polyfluorene and a method for manufacturing the same.

[0002] A representative example of a water electrolysis device is the one utilizing a Proton Exchange Membrane (PEM). PEM water electrolysis technology is characterized by high energy efficiency and very high hydrogen purity due to the use of platinum catalysts; however, it has the disadvantage of high system manufacturing costs due to the use of precious metal catalysts and perfluorocarbon (PFC) cation exchange membranes. Additionally, there is the Alkaline Electrolysis (AEC) method, which electrolyzes water using an alkaline electrolyte. This method has the advantages of low unit cost and high durability due to the use of non-precious metal catalysts, but it has disadvantages such as corrosion caused by alkaline components, low current density and efficiency, and difficulty in high-pressure operation. Therefore, research has been conducted on new electrolyte membranes that can replace these methods. Recently, Anion Exchange Membranes (AEMs) have been receiving significant attention as an alternative capable of solving these problems.

[0003] Since the anion exchange electrolyte membrane allows for oxygen reduction in a basic atmosphere, it has the advantage of being able to use inexpensive non-precious metals such as Ni and Mn as electrode catalysts instead of platinum, and to operate at low power and / or high pressure, thereby increasing the efficiency and purity of hydrogen production.

[0004] However, recent research results indicate that issues regarding the chemical and mechanical stability of anion exchange membranes are emerging. Water electrolysis technology using anion exchange membranes requires operating temperatures above 60°C and the ability to withstand differential pressure conditions caused by gases generated at the electrodes; however, existing anion exchange membranes exhibit degraded mechanical performance due to swelling caused by moisture absorption as ion conductivity increases, and polymer chains with polar covalent bonds [regarding] anions (OH- There is a problem in that thermal stability decreases in high-temperature operating environments because it is decomposed by ).

[0005] Specifically, Patent Document 1 describes an anion exchange membrane manufactured by crosslinking SEBS and polyphenylene oxide, but the polyphenylene oxide has low thermal stability and has few crosslinking points during crosslinking, so there is a problem that a large amount of polyfluorene is required to achieve the desired mechanical strength.

[0006] Therefore, research and development are needed on anion exchange membranes that have high ion conductivity and excellent mechanical properties and thermal stability.

[0007] [Prior Art Literature]

[0008] [Patent Literature]

[0009] (Patent Document 1) Korean Registered Patent No. 10-2184530

[0010] The present invention aims to provide an anion exchange membrane comprising a cross-linked polymer of SEBS and polyfluorene that can improve the problems of the aforementioned anion exchange membrane, and a method for manufacturing the same.

[0011] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0012] One embodiment of the present invention provides an anion exchange membrane comprising a cross-linked polymer in which a polyfluorene represented by the following chemical formula 1 is cross-linked with SEBS (Styrene-Ethylene-Butylene-Styrene).

[0013] [Chemical Formula 1]

[0014]

[0015] In Chemical Formula 1, represents the position where it cross-links with SEBS, and R1 is a hydrogen, substituted, or unsubstituted C 1-30 Alkyl groups, substituted or unsubstituted C 2-30 alkenyl group, substituted or unsubstituted C 1-30 Alkoxy groups, substituted or unsubstituted C 2-30 Alkoxyalkyl group, or substituted or unsubstituted C 6-30 It is an aryl group, l is an integer from 2 to 10, m is an integer from 1 to 4, and when m is 2 or greater, R1 is the same or different, and n is an integer from 2 to 50.

[0016] Another embodiment of the present invention provides a method for manufacturing the anion exchange membrane. Specifically, another embodiment of the present invention comprises the steps of: reacting a polyfluorene with an aromatic compound to form a polyfluorene having an arylene group bonded within a repeating unit; and C having an amine group in at least one styrene repeating unit of SEBS. 6-30 The present invention provides a method for manufacturing an anion exchange membrane, comprising: a step of manufacturing SEBS-amine by bonding an aryl group; and a step of forming a cross-linked polymer by cross-linking the SEBS-amine and a polyfluorene in which an arylene group is bonded within the repeating unit.

[0017] The anion exchange membrane according to the present invention has the advantage of having high ion conductivity, high thermal stability and / or high mechanical properties.

[0018] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0019] Figure 1 is a graph showing the mechanical properties of anion exchange membranes according to Examples 1 to 3 and Comparative Example 1.

[0020] Figure 2 is a graph showing the ionic conductivity of anion exchange membranes according to Examples 1 to 3.

[0021] Figure 3 is a graph showing the thermal stability of anion exchange membranes according to Examples 1 to 3 and Comparative Example 1.

[0022] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0023] In this specification, "C 1-30 The "alkyl group" can be a straight-chain, branched-chain, or cyclic alkyl. Specifically, C 1-30 The alkyl group may be a straight-chain alkyl having 1 to 30 carbon atoms; a straight-chain alkyl having 1 to 20 carbon atoms; a straight-chain alkyl having 1 to 10 carbon atoms; a straight-chain alkyl having 1 to 5 carbon atoms; a branched-chain or cyclic alkyl having 3 to 20 carbon atoms; a branched-chain or cyclic alkyl having 3 to 15 carbon atoms; or a branched-chain or cyclic alkyl having 3 to 10 carbon atoms. More specifically, the alkyl having 1 to 30 carbon atoms may be a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, an iso-pentyl group, or a cyclohexyl group, etc.

[0024] In this specification, "C 2-30 The "alkenyl group" may be a straight-chain, branched-chain, or cyclic alkenyl. Specifically, the above C 2-30The alkenyl group may be a straight-chain alkenyl having 2 to 30 carbon atoms, a straight-chain alkenyl having 2 to 20 carbon atoms, a straight-chain alkenyl having 2 to 10 carbon atoms, a straight-chain alkenyl having 2 to 5 carbon atoms, a branched-chain alkenyl having 3 to 30 carbon atoms, a branched-chain alkenyl having 3 to 20 carbon atoms, a branched-chain alkenyl having 3 to 15 carbon atoms, a branched-chain alkenyl having 3 to 10 carbon atoms, a cyclic alkenyl having 5 to 30 carbon atoms, a cyclic alkenyl having 5 to 20 carbon atoms, or a cyclic alkenyl having 5 to 10 carbon atoms. More specifically, the alkenyl having 2 to 30 carbon atoms may be ethenyl, propenyl, butenyl, pentenyl, or cyclohexanyl, etc.

[0025] In this specification, "C 1-30 The "alkoxy group" may be a straight-chain, branched-chain, or cyclic alkoxy group. Specifically, the above C 1-30 The alkoxy group may be a straight-chain alkoxy group having 1 to 30 carbon atoms; a straight-chain alkoxy group having 1 to 20 carbon atoms; a straight-chain alkoxy group having 1 to 10 carbon atoms; a straight-chain alkoxy group having 1 to 5 carbon atoms; a branched-chain or cyclic alkoxy group having 3 to 30 carbon atoms; a branched-chain or cyclic alkoxy group having 3 to 20 carbon atoms; a branched-chain or cyclic alkoxy group having 3 to 15 carbon atoms; or a branched-chain or cyclic alkoxy group having 3 to 10 carbon atoms. More specifically, the alkoxy group having 1 to 30 carbon atoms may be a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a tert-butoxy group, an n-pentoxy group, an iso-pentoxy group, a neo-pentoxy group, or a cyclohexoxy group, etc.

[0026] In this specification, "C 2-30 The alkoxyalkyl group is -R y -OR z A structure containing alkyl(-R y One or more hydrogens of ) are alkoxy(-OR z It may be a substituent substituted with ). The above C 2-30 The alkoxyalkyl group is R yand R z The total number of carbons included is 2 to 30, and specifically, it may be a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an iso-propoxymethyl group, an iso-propoxyethyl group, an iso-propoxyhexyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, or a tert-butoxyhexyl group, etc.

[0027] In this specification, "C 6-30 "Aryl group" can refer to monocyclic, bicyclic, or tricyclic aromatic hydrocarbons. Specifically, C 6-30 The aryl group may be a phenyl group, a naphthyl group, or anthracenyl group, etc.

[0028] In this specification, "arylene group" refers to a substituted or unsubstituted C 6-30 It may be an aryl group. The above arylene group may refer to a divalent monocyclic, bicyclic, or tricyclic aromatic hydrocarbon. Specifically, C 6-30 The arylene group may be a phenylene group, a naphthylene group, or anthracenylene group, etc.

[0029] In this specification, the term “substituted or unsubstituted” means substituted or unsubstituted with one or more substituents selected from the group consisting of deuterium; halogen group; cyano group; nitro group; hydroxyl group; carbonyl group; ester group; imide group; amide group; primary amino group; carboxyl group; sulfonic acid group; sulfonamide group; phosphine oxide group; alkoxy group; aryloxy group; alkylthioxy group; arylthioxy group; alkyl sulfoxy group; aryl sulfoxy group; silyl group; boron group; alkyl group; cycloalkyl group; alkenyl group; aryl group; aralkyl group; aralkenyl group; alkylaryl group; alkoxysilylalkyl group; arylphosphine group; or heterocyclic groups comprising one or more of N, O, and S atoms, or substituted or unsubstituted with two or more of the exemplified substituents connected.

[0030] The inventors recognized the problem that, in the case of previously developed anion exchange membranes, mechanical performance deteriorates as ion conductivity increases and thermal stability decreases in high-temperature operating environments, and as a result of conducting research to improve this, developed an anion exchange membrane as described below. Specifically, the anion exchange membrane according to the present invention comprises a cross-linked polymer formed by cross-linking SEBS with polyfluorene containing arylene groups that impart rigid properties within repeating units, and can have high ion conductivity, excellent mechanical properties, and thermal stability.

[0031] The present invention will be described in detail below.

[0032] One embodiment of the present invention provides an anion exchange membrane comprising a cross-linked polymer in which a polyfluorene represented by the following chemical formula 1 is cross-linked with SEBS (Styrene-Ethylene-Butylene-Styrene).

[0033] [Chemical Formula 1]

[0034]

[0035] In Chemical Formula 1, represents the position where it cross-links with SEBS, and R1 is a hydrogen, substituted, or unsubstituted C 1-30 Alkyl groups, substituted or unsubstituted C 2-30 alkenyl group, substituted or unsubstituted C 1-30 Alkoxy groups, substituted or unsubstituted C 2-30 Alkoxyalkyl group, or substituted or unsubstituted C 6-30 It is an aryl group, l is an integer from 2 to 10, m is an integer from 1 to 4, and when m is 2 or greater, R1 is the same or different, and n is an integer from 2 to 50.

[0036] According to one embodiment of the present invention, l in the above formula 1 may be an integer from 3 to 7, specifically 5.

[0037] According to one embodiment of the present invention, R1 in Chemical Formula 1 may all be hydrogen.

[0038] According to one embodiment of the present invention, in the formula 1 represents a location that crosslinks with SEBS (hereinafter referred to as a crosslinking point). Since the polyfluorene of the crosslinked polymer according to the present invention has two crosslinking points, it is possible to form more crosslinking points with SEBS with a relatively small amount of polyfluorene, or for one repeating unit of polyfluorene to bond with strands of different SEBS to form a more robust three-dimensional network.

[0039] According to one embodiment of the present invention, the polyfluorene represented by the chemical formula 1 may be named as 'polyfluorene in which an arylene group is bonded within a repeating unit'.

[0040] According to one embodiment of the present invention, the SEBS-polyfluorene crosslinked polymer of the present invention may have at least one repeating unit of polyfluorene represented by the above formula 1 crosslinked with each other SEBS chain to form a three-dimensional polymer network.

[0041] According to one embodiment of the present invention, the polyfluorene represented by Formula 1 may be crosslinked in a range of 0.5 mol% to 10 mol% with respect to SEBS. Specifically, the polyfluorene represented by Formula 1 may be in a range of 2 mol% to 7 mol% with respect to SEBS. More specifically, the polyfluorene represented by Formula 1 may be in a range of about 5 mol% with respect to SEBS. When the content of polyfluorene is within the above range, excellent mechanical properties can be achieved by controlling the degree of crosslinking without the problem of not dissolving in a solvent due to excessive crosslinking, and high ionic conductivity and thermal stability can be achieved.

[0042] Unlike in existing inventions where polyfluorene is used in an amount of 50 mol% relative to SEBS when preparing a crosslinked polymer of SEBS and polyfluorene applied to anion exchange membranes, the crosslinked polymer according to the present invention uses polyfluorene having two crosslinking sites. Accordingly, it is possible to manufacture anion exchange membranes containing a crosslinked polymer having high mechanical strength and ion conductivity even when crosslinking a significantly smaller amount of polyfluorene compared to the existing crosslinked polymer of SEBS and polyfluorene.

[0043] According to one embodiment of the present invention, the number average molecular weight (Mn) of the polyfluorene may be 1,000 to 30,000 g / mol. Specifically, the number average molecular weight of the polyfluorene may be 5,000 to 30,000 g / mol, 10,000 to 25,000 g / mol, 10,000 to 20,000 g / mol, 10,000 to 18,000 g / mol, 12,000 to 16,000 g / mol, 13,000 to 15,000 g / mol, or 13,000 to 14,000 g / mol. By using polyfluorene within the above range, the mechanical properties of the anion exchange membrane can be improved.

[0044] According to one embodiment of the present invention, at least one styrene repeating unit of the SEBS has an amine group C 6-30 It is a polystyrene-amine bonded to an aryl group, and the polystyrene-amine may be cross-linked with a polyfluorene represented by Chemical Formula 1. Specifically, the SEBS is a C having an amine group on at least one styrene repeating unit of the SEBS. 6-30 It may be a SEBS-amine with an aryl group attached. The SEBS-amine according to the present invention is C rather than one in which an amine group is directly substituted on styrene. 6-30 Including aryl groups as spacers can help improve the alkali stability of ion exchange membranes.

[0045] According to one embodiment of the present invention, the crosslinking point of the SEBS and the polyfluorene represented by Formula 1 is OH - It may be bonded to an amine group substituted with an ammonium group capable of conducting. Unlike SEBS used in the prior art, the SEBS-amine according to the present invention includes an aryl group that imparts rigid properties, thereby improving the mechanical properties of the ion exchange membrane, and OH - By including an amine group substituted with an ammonium group capable of conducting, the ion conductivity of the ion exchange membrane can be improved.

[0046] According to one embodiment of the present invention, the polystyrene content of the SEBS-amine may be 0 to 30 mol%, and specifically 10 mol% to 20 mol%.

[0047] According to one embodiment of the present invention, the content of polystyrene-amine of the SEBS-amine may be 5 to 20 mol%, and specifically 10 mol% to 15 mol%.

[0048] According to one embodiment of the present invention, the number average molecular weight (Mn) of SEBS-amine may be 50,000 to 150,000 g / mol, specifically 60,000 to 150,000 g / mol, 80,000 to 150,000 g / mol, 100,000 to 150,000 g / mol, 100,000 to 130,000 g / mol, or 100,000 to 120,000 g / mol. By using SEBS within the above range, the mechanical properties of the anion exchange membrane can be improved.

[0049] According to one embodiment of the present invention, the SEBS-polyfluorene crosslinked polymer may have a structure represented by the following formula 2-1 or formula 2-2.

[0050] [Chemical Formula 2-1]

[0051]

[0052] [Chemical Formula 2-2]

[0053]

[0054] In the above formulas 2-1 and 2-2, x is an integer from 200 to 400, y is an integer from 1000 to 1300, PF means bonded to another crosslinking group of the polyfluorene of formula 2-1 or formula 2-2, or bonded to a crosslinking group of a polyfluorene of a different chain from the polyfluorene of formula 2-1 or formula 2-2, SEBS means bonded to another crosslinking group of SEBS of formula 2-1 or formula 2-2, or bonded to a crosslinking group of SEBS of a different chain from SEBS of formula 2-1 or formula 2-2, l, m, n and R1 are the same as the definitions of formula 1, and o is an integer from 1 to 10.

[0055] The above crosslinking group refers to a crosslinkable functional group capable of being bonded to polymer chains by chemical bonding, and the chemical bonding may be mainly a covalent bond. The crosslinking group of the polyfluorene is a crosslinkable functional group bonded to the pentagonal ring of the fluorene and can crosslink with SEBS-amine, and the crosslinking group of the SEBS is a crosslinkable functional group bonded to the terminal of the amine group and can crosslink with the crosslinking group of the polyfluorene.

[0056] According to one embodiment of the present invention, the amine group substituted with an ammonium group in Formula 2-1 and Formula 2-2 is OH - It can be replaced with. Accordingly, the ionic conductivity of the ion exchange membrane can be improved.

[0057] The cross-linked polymer according to the present invention overcomes the disadvantages of SEBS, which has mechanical properties of high strain and low modulus, by introducing polyfluorene having characteristics of low strain but high modulus, and further enables high ionic conductivity, high mechanical properties, and high thermal stability. In addition, the cross-linked polymer OH - High ionic conductivity can be achieved by including crosslinking points substituted with ammonium groups capable of conducting, and high thermal stability can be achieved because the main chain of the crosslinked polymer is made of carbon.

[0058] According to one embodiment of the present invention, the thickness of the anion exchange membrane comprising the SEBS-polyfluorene crosslinked polymer may be 5 μm to 50 μm. Specifically, the thickness of the anion exchange membrane may be 10 μm to 40 μm, 10 μm to 30 μm, 15 μm to 30 μm, or 20 μm to 30 μm. If the polymer membrane is less than the lower limit of the above range, the membrane thickness is thin, which has the disadvantage of significantly reducing mechanical properties; conversely, if it exceeds the upper limit of the above range, the resistance due to thickness in the Membrane Electrode Assembly (MEA) increases, which has the disadvantage of lowering the current density. Specifically, within the above range, the thinner the membrane thickness, the lower the resistance in the MEA, allowing for the output of a high current density.

[0059] Another embodiment of the present invention provides a method for manufacturing the anion exchange membrane. Specifically, another embodiment of the present invention comprises the steps of: reacting a polyfluorene with an aromatic compound to form a polyfluorene having an arylene group bonded within a repeating unit; and C having an amine group in at least one styrene repeating unit of SEBS. 6-30The present invention provides a method for manufacturing an anion exchange membrane, comprising: a step of manufacturing SEBS-amine by bonding an aryl group; and a step of forming a cross-linked polymer by cross-linking the SEBS-amine and a polyfluorene in which an arylene group is bonded within the repeating unit.

[0060] According to one embodiment of the present invention, a polyfluorene with an arylene group bonded within the repeating unit can be represented by the following chemical formula 3.

[0061] [Chemical Formula 3]

[0062]

[0063] In Chemical Formula 3, R1 is hydrogen, substituted or unsubstituted C 1-30 Alkyl groups, substituted or unsubstituted C 2-30 alkenyl group, substituted or unsubstituted C 1-30 Alkoxy groups, substituted or unsubstituted C 2-30 Alkoxyalkyl group, or substituted or unsubstituted C 6-30 It is an aryl group, l is an integer from 2 to 10, m is an integer from 1 to 4, and when m is 2 or greater, R1 is the same or different, n is an integer from 2 to 50, and Q is a halogen element.

[0064] According to one embodiment of the present invention, R1 in the above chemical formula 3 may all be hydrogen.

[0065] According to one embodiment of the present invention, Q in the above formula 3 may be F, Cl, Br, or I, and specifically may be Br.

[0066] According to one embodiment of the present invention, l in the above formula 3 may be an integer from 3 to 7, specifically 5.

[0067] According to one embodiment of the present invention, the SEBS-amine may be represented by the following chemical formula 4 or chemical formula 5.

[0068] [Chemical Formula 4]

[0069]

[0070] [Chemical Formula 5]

[0071]

[0072] In chemical formulas 4 and 5, x is an integer from 200 to 400, y is an integer from 1000 to 1300, and o is an integer from 1 to 10.

[0073] According to one embodiment of the present invention, the content of polyfluorene with an arylene group bonded within the repeating unit may be in the range of 0.5 mol% to 10 mol% with respect to the SEBS of the SEBS-amine.

[0074] According to one embodiment of the present invention, the SEBS-amine may be represented by the following formula 4-1 or formula 5-1.

[0075] [Chemical Formula 4-1]

[0076]

[0077] [Chemical Formula 5-1]

[0078]

[0079] According to one embodiment of the present invention, a crosslinking agent may not be used when crosslinking SEBS and polyfluorene. Specifically, according to one embodiment of the present invention, since the crosslinking reaction occurs spontaneously by an SN2 reaction, a crosslinking agent may not be used. Specifically, a halogen element of polyfluorene may detach and an amine of SEBS may react to spontaneously crosslink.

[0080] According to one embodiment of the present invention, the anion exchange membrane comprising the cross-linked polymer may be used for water electrolysis. When the anion exchange membrane is used for water electrolysis, it is advantageous for pressurized and differential pressure operation of the water electrolysis, and has the advantage of high durability, which can suppress the decomposition of the anion exchange membrane when operated for a long time.

[0081] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0082] [Preparation Example 1]

[0083] 1. Synthesis of Polyfluorene

[0084] Fluorene (120 mg, 1.2 eq), Benzene (50.7 mg, 1.0 eq), and Pd(PPh3)4 (5.3 mg, 0.03 eq) were reacted at 90 °C for 24 hours under vacuum and nitrogen atmosphere by adding 2 M K2CO3 aqueous solution (0.6 ml), Toluene (10 ml), and Aliquat (2 drops). The obtained product was subjected to the Soxhlet extraction method (MeOH-Acetone-Hexane-DCM) to obtain polyfluorene (Mn=13.6 kg / mol, PDI: 2.4) with arylene groups attached to repeating units.

[0085] 2. Synthesis of SEBS-amine

[0086] To SEBS (1 g, Mw=105 kg / mol, polystyrene content: 18 mol%, purchased from Sigma Aldrich), BPin (7 g, 7 eq of PS), IrCl(COD)2 (290 mg, 1.5 mol% of BPin), Dtbpy (232 mg, 3 mol% of BPin), and 15 ml of THF were added, and a borylation reaction was carried out for 4 days at 80 ℃ under an N2 atmosphere to obtain borylated SEBS. To 500 mg of the above borylated SEBS, benzenemethanamine, 4-bromo-N,N-dimethyl-(1.9 ml, 7 eq of Bpin), Pd(dPPf)Cl2([1,1´-Bis(diphenylphosphino)ferrocene]dichloropalladium(II))(41 mg, 3 mol% of Bpin), 3 M K2CO3 aqueous solution, and 4 ml of THF were added, and a Suzuki coupling reaction was performed for 4 days at 80 ℃ under an N2 atmosphere to obtain SEBS-amine.

[0087] [Example 1]

[0088] SEBS-amine obtained from the above preparation example and polyfluorene containing 4 mol% relative to SEBS were added to a CHCl3 solvent to form a solution with a concentration of 2.4 wt%, and then reacted at approximately 50 °C for 12 hours to prepare cross-linked SEBS-polyfluorene. Subsequently, CH3I was added in an amount 200 equivalents relative to the amine content of SEBS and reacted at 60 °C for approximately 2 days, after which water was added to remove the unreacted CH3I. At room temperature, trimethylamine (TMA) was added in an amount 200 equivalents relative to the Br content of the polyfluorene and reacted at 40 °C for approximately 2 days, after which water was added to remove the unreacted TMA. The amine and Br groups in the reaction mixture were substituted with ammonium groups, and 1 M KOH was added to I - and Br- OH - A SEBS-polyfluorene cross-linked polymer membrane was prepared by ion substitution.

[0089] [Example 2]

[0090] A SEBS-polyfluorene crosslinked polymer membrane was prepared using the same method as in Example 1, except that the content of polyfluorene relative to SEBS in SEBS-amine was adjusted to 5 mol%.

[0091] [Example 3]

[0092] A SEBS-polyfluorene crosslinked polymer membrane was prepared using the same method as in Example 1, except that the content of polyfluorene relative to SEBS in SEBS-amine was adjusted to 6 mol%.

[0093] Calculation of reaction moles of polyfluorene

[0094] 1. Calculation of moles of amine

[0095] The repeating units of 30 mg of polystyrene (x) and ethylene-butylene (y) in SEBS-amine (Mn=118 kg / mol, PS content: 18 mol%, amine content based on PS: 72 mol%) were determined by solving the system of equations: ① x : y = 18 (polystyrene content ratio) : 82 (ethylene-butylene content ratio), and ② 105 (styrene molecular weight)*x + 83 (ethylene-butylene molecular weight)*y = 118,000. The amine content of SEBS-amine was calculated according to the formula (moles of PS in SEBS) * (amine content based on PS, %), The value was obtained. The number of moles of amine according to the mass of different SEBS-amines can be determined in the same way.

[0096] 2. Calculation of reaction moles of 5 mol % polyfluorene

[0097] Assuming the polyfluorene content based on SEBS is 5 mol%, the moles of the amine obtained above The reaction moles (x) of polyfluorene were calculated by substituting into the formula. Since there are 2 crosslinking sites, 0.01 mol of reaction moles of polyfluorene was obtained. The reaction moles of polyfluorene according to different SEBS standards and polyfluorene content can be calculated in the same way.

[0098] [Comparative Example 1]

[0099] After obtaining SEBS-amine using the same method as in Preparation Example 1, a polymer membrane containing SEBS-ammonium was prepared by substituting the amine group of SEBS-amine with an ammonium group.

[0100] [Experimental Example]

[0101] The mechanical properties, ion conductivity, and thermal stability of the anion exchange membranes prepared from Examples 1 to 3 and Comparative Example 1 of the present invention were measured by the following method.

[0102] (1) Measurement of mechanical properties

[0103] Measurements were taken at a speed of 10 mm / min using a UTM instrument, and the film thickness was measured based on 20 μm to 30 μm.

[0104] (2) Measurement of ion conductivity

[0105] SEBS-polyfluorene crosslinks at 80 ℃ OH - To prevent side reactions with carbon dioxide, measurements were taken using a potentiostat EIS while immersed in water and maintaining an argon environment, in the frequency range of 6 MHz to 1 Hz.

[0106] (3) Measurement of thermal stability

[0107] OH - To prevent side reactions with carbon dioxide, an argon environment was maintained, and the rate of decrease in ion conductivity was measured at 80°C for 5 hours using the same method as in (2) above.

[0108] Table 1 below shows the strain, modulus, ion conductivity, and thermal stability values ​​of the anion exchange membranes prepared from Examples 1 to 3 and Comparative Example 1.

[0109] Materials Used Strain [%] Modulus [MPa] Ionic Conductivity [mS / cm] (80 ℃) Thermal Stability (Rate of decrease in ionic conductivity over 5 hours) Comparative Example 1 SEBS-ammonium 9243.8205% (at 60 ℃) Example 1 4 mol% * crosslinked SEBS-Polyfluorene 82.98823.54% (at 80 ℃) Example 25 mol% * crosslinked SEBS-Polyfluorene 61.224828.72.5% (at 80 ℃) Example 36 mol% * crosslinked SEBS-Polyfluorene24.524032.51%(at 80℃)

[0110] *: mol% is based on the amount of polyfluorene added according to SEBS standards.

[0111] Figure 1 shows the measurement results of the mechanical properties of anion exchange membranes prepared from Examples 1 to 3 (SEBS-polyfluorene crosslinked membranes) and Comparative Example 1 (SEBS-ammonium membrane).

[0112] As shown in Figure 1 and Table 1, the anion exchange membrane having a cross-linked structure prepared from Examples 1 to 3 of the present invention cross-links SEBS with polyfluorene containing aryl groups that impart hard properties, and compared to an anion exchange membrane without a cross-linked structure as in Comparative Example 1, the modulus of elasticity increases. In particular, when the cross-linking reaction is carried out by adding polyfluorene with a content of 5 mol% relative to SEBS of SEBS-amine, the modulus of elasticity increases significantly to 248 MPa, and it can be confirmed that it has excellent mechanical strength.

[0113] Figure 2 shows the measurement results of the ion conductivity of the anion exchange membranes prepared from Examples 1 to 3 and Comparative Example 1.

[0114] As shown in FIG. 2 and Table 1, the cross-linked anion exchange membranes prepared from Examples 1 to 3 of the present invention exhibit 23.5 mS / cm² depending on the polyfluorene content relative to SEBS in an environment of 80 °C. It increases to 32.5 mS / cm, which is higher than the ionic conductivity value of 20 mS / cm in an 80 ℃ environment of Comparative Example 1. It can be seen that the increase in ionic conductivity with respect to the polyfluorene content relative to SEBS is due to the additional substitution of the Br groups, which did not undergo cross-linking reactions in polyfluorene, with ammonium groups.

[0115] Figure 3 shows the measurement results of the thermal stability (rate of reduction in ion conductivity) of the anion exchange membranes prepared from Examples 1 to 3 and Comparative Example 1.

[0116] As shown in Figure 3 and Table 1, the anion exchange membrane prepared from Comparative Example 1 showed the lowest thermal stability with a reduction rate of 5% when the reduction rate of ion conductivity was measured for 5 hours in an environment of 60°C, whereas the anion exchange membranes prepared from Examples 1 to 3 showed excellent thermal stability at a level of 1% in an environment of 80°C, which is a higher temperature than the Comparative Example.

[0117] Accordingly, the anion exchange membrane comprising a cross-linked structure according to the present invention comprises an aryl group that imparts rigid properties, and OH - It can be seen that by having a cross-linked structure substituted with ammonium groups capable of conducting, it exhibits excellent mechanical properties, ionic conductivity, and thermal stability, thereby possessing high power density and durability.

Claims

1. Anion exchange membrane comprising a cross-linked polymer in which a polyfluorene represented by the following chemical formula 1 is cross-linked with SEBS (Styrene-Ethylene-Butylene-Styrene): [Chemical Formula 1] In Chemical Formula 1, refers to the position where it cross-links with SEBS, and R1 is hydrogen, substituted or unsubstituted C 1-30 Alkyl groups, substituted or unsubstituted C 2-30 alkenyl group, substituted or unsubstituted C 1-30 Alkoxy groups, substituted or unsubstituted C 2-30 Alkoxyalkyl group, or substituted or unsubstituted C 6-30 It is Arilgi, and l is an integer from 2 to 10, and m is an integer from 1 to 4, and if m is 2 or greater, R1 is the same or different, respectively, and n is an integer from 2 to 50.

2. In Claim 1, An anion exchange membrane in which at least one repeating unit of polyfluorene represented by the above chemical formula 1 is cross-linked with each other SEBS chain to form a three-dimensional polymer network.

3. In Claim 1, An anion exchange membrane in which the polyfluorene represented by the above chemical formula 1 is crosslinked in a range of 0.5 mol% to 10 mol% with respect to the above SEBS.

4. In Claim 1, At least one styrene repeating unit of the above SEBS is C having an amine group 6-30 An anion exchange membrane, wherein the polystyrene-amine is bonded to an aryl group, and the polystyrene-amine is cross-linked with a polyfluorene represented by the chemical formula 1.

5. In Claim 4, An anion exchange membrane in which the content of the above polystyrene-amine is within the range of 5 mol% to 20 mol% with respect to the above SEBS.

6. In Claim 1, The above SEBS-polyfluorene crosslinked polymer is an anion exchange membrane having a structure represented by the following chemical formula 2-1 or chemical formula 2-2. [Chemical Formula 2-1] [Chemical Formula 2-2] In the above Chemical Formulas 2-1 and 2-2, x is an integer from 200 to 400, and y is an integer from 1000 to 1300, and PF means that it is bonded to another crosslinking group of a polyfluorene of Formula 2-1 or Formula 2-2, or bonded to a crosslinking group of a polyfluorene of a different chain from the polyfluorene of Formula 2-1 or Formula 2-2, and SEBS means that it is bonded to other crosslinking groups of SEBS of Formula 2-1 or Formula 2-2, or bonded to crosslinking groups of SEBS of a different chain from SEBS of Formula 2-1 or Formula 2-2, and l, m, n, and R1 are identical to the definitions of Chemical Formula 1, and o is an integer from 1 to 10.

7. In Claim 1, An anion exchange membrane having a thickness of 5 μm to 50 μm.

8. A step of reacting polyfluorene with an aromatic compound to form polyfluorene in which arylene groups are bonded within repeating units; C having an amine group on at least one styrene repeating unit of SEBS 6-30 A step of preparing SEBS-amine by attaching an aryl group; and A step of forming a cross-linked polymer by cross-linking the above SEBS-amine and a polyfluorene in which an arylene group is bonded within the repeating unit; A method for manufacturing an anion exchange membrane comprising 9. In Claim 8, A method for manufacturing an anion exchange membrane, wherein the polyfluorene with an arylene group bonded within the repeating unit is represented by the following chemical formula 3: [Chemical Formula 3] In Chemical Formula 3, R1 is hydrogen, substituted or unsubstituted C 1-30 Alkyl groups, substituted or unsubstituted C 2-30 alkenyl group, substituted or unsubstituted C 1-30 Alkoxy groups, substituted or unsubstituted C 2-30 Alkoxyalkyl group, or substituted or unsubstituted C 6-30 It is Arilgi, and l is an integer from 2 to 10, and m is an integer from 1 to 4, and if m is 2 or greater, R1 is the same or different, respectively, and n is an integer from 2 to 50, and Q is a halogen element.

10. In Claim 8, A method for manufacturing an anion exchange membrane, wherein the above SEBS-amine is represented by the following chemical formula 4 or chemical formula 5: [Chemical Formula 4] [Chemical Formula 5] In Chemical Formulas 4 and 5, x is an integer from 200 to 400, and y is an integer from 1000 to 1300, and o is an integer from 1 to 10.

11. In Claim 8, A method for manufacturing an anion exchange membrane, wherein the content of polyfluorene with an arylene group bonded within the repeating unit is in the range of 0.5 mol% to 10 mol% relative to the SEBS of the SEBS-amine.

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