Novel polymer and anion exchange membrane comprising same

Abstract

The present invention provides a novel polymer and an anion exchange membrane having improved ionic conductivity and improved durability due to the inclusion of the novel polymer.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from Korean Patent Application No. 10-2022-0176765 filed on December 16, 2022, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

[0003] The present invention relates to a novel polymer and an anion exchange membrane, which contains the polymer and thus has improved ion conductivity and durability. Background Art

[0004] Anion exchange membrane refers to a membrane with positively charged ion groups. Due to the repulsive force of like charges, cations are difficult to pass through, and only anions are selectively allowed to pass through.

[0005] Since alkaline electrolysis cells (AECs) using this type of anion exchange membrane can use cheap metals such as nickel and manganese instead of precious metal platinum as electrode catalysts, their price advantage can overcome the shortcomings of existing commercially available cation exchange membranes (such as high price and fuel permeation), and are widely used in electrochemical devices such as fuel cells, water electrolysis cells and redox flow batteries.

[0006] However, current anion exchange membranes have lower ionic conductivity than cation exchange membranes and have been difficult to commercialize due to chemical and mechanical stability issues under alkaline conditions. Therefore, in order to develop AEC water electrolyzers to ensure their competitiveness in the hydrogen production field, a technology that can produce high-performance and highly durable anion exchange membranes at a lower cost than before is needed.

[0007] Therefore, there is a continuous need to develop cost-competitive anion exchange membranes with improved ionic conductivity and durability. Summary of the Invention

[0008]

Technical Issues

[0009] An object of the present invention is to provide a novel polymer, a method for preparing the same, an anion exchange membrane comprising the novel polymer and thus having improved ion conductivity and durability, and a method for preparing the anion exchange membrane.

[0010]

Technical solution

[0011] According to one embodiment of the present invention, a polymer comprising a cross-linked structure shown in the following Chemical Formula 1 is provided:

[0012] [Chemical Formula 1]

[0013]

[0014] Wherein, in Chemical Formula 1,

[0015] R1 and R2 are each independently halogen or C 1-4 alkyl,

[0016] a and b are each independently an integer from 0 to 3,

[0017] R3 and R4 are each independently hydrogen or C 1-4 alkyl,

[0018] R5 is C 1-10 alkyl,

[0019] R6 to R9 are each independently C 1-4 alkyl,

[0020] L is C 1-10 Alkylene,

[0021] Q is a halogen,

[0022] n is an integer from 1 to 3,

[0023] x, y and z represent the mole fractions of the repeating units in the polymer.

[0024] According to another embodiment of the present invention, there is provided a method for preparing a polymer comprising a cross-linked structure represented by the following Chemical Formula 1, the method comprising the following steps:

[0025] Reacting a first polymer with hydrogen halide to prepare a second polymer, wherein the first polymer is an ABC triblock copolymer represented by the following chemical formula 1-1, and the second polymer is an A-B'-C triblock copolymer represented by the following chemical formula 1-2 (step 1);

[0026] Reacting the second polymer represented by the following Chemical Formula 1-2 with the olefin represented by the following Chemical Formula 1a to prepare a third polymer, which is an AB"-C triblock copolymer represented by the following Chemical Formula 1-3 (step 2); and

[0027] The third polymer represented by the following Chemical Formula 1-3 is reacted with the diamine represented by the following Chemical Formula 1b to prepare a polymer having a cross-linked structure represented by Chemical Formula 1 (step 3):

[0028] [Chemical Formula 1-1]

[0029]

[0030] [Chemical formula 1-2]

[0031]

[0032] [Chemical formula 1-3]

[0033]

[0034] [Chemical Formula 1a]

[0035]

[0036] [Chemical Formula 1b]

[0037]

[0038] Among them, in Chemical Formulas 1-1 to 1-3, 1a, and 1b,

[0039] R1 to R9, L, Q, a, b, n, x, y, and z are as defined in Chemical Formula 1.

[0040] According to another embodiment of the present invention, an anion exchange membrane comprising the above polymer is provided.

[0041] According to another embodiment of the present invention, there is provided a method for manufacturing an anion exchange membrane, the method comprising the following steps:

[0042] reacting the third polymer represented by Chemical Formula 1-3 with the diamine represented by Chemical Formula 1b in an organic solvent to prepare a polymer solution including a cross-linked structure represented by Chemical Formula 1 (step 1); and

[0043] The polymer solution is cast onto a substrate and the cast film is then dried (step 2).

[0044] Beneficial effects

[0045] The novel polymer of the present invention not only reduces the cost of the preparation process by using a styrene-isoprene-styrene triblock copolymer, offering the advantages of a simple and low-cost synthesis process, but also allows for subsequent atom transfer radical polymerization of the copolymer to extend the distance between the ionic bond and the main chain, thereby improving the ionic conductivity of anion exchange membranes containing the polymer. Furthermore, by forming dozens of nanostructures, fine phase separation is achieved, which facilitates the movement of ions within nanochannels. Furthermore, the polymer exhibits mechanical strength far superior to that of a single polymer, thereby improving the durability of the anion exchange membrane containing the polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a photo of the anion exchange membrane prepared in Example 1.

[0047] Figure 2 The second polymer (SIS-Cl) and the third polymer (SIS-hex-Cl) prepared in Example 11 H NMR analysis spectrum.

[0048] Figure 3 The starting material first polymer (SIS) of Example 1 1 H NMR analysis spectrum.

[0049] Figure 4 FT-IR analysis spectra of the first polymer (SIS) as the starting material of Example 1, as well as the second polymer (SIS-Cl), the third polymer (SIS-hex-Cl) and the anion exchange membrane (XI-SIS-hex-QA) prepared in Example 1. DETAILED DESCRIPTION

[0050] The technical terms used herein are only used to describe exemplary embodiments and are not intended to limit the scope of the present invention. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms. It should be understood that the terms "comprising", "including", "having", etc. used herein to specify the presence of the features, integers, steps, components, or combinations thereof, do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0051] In addition, herein, when it is mentioned that a layer or element is formed “on” a layer or element, it means that the layer or element is directly formed on these layers or elements, or that other layers or elements may be additionally formed between these layers, on the object, or on the substrate.

[0052] Although the present invention may have many forms and various modifications thereof, specific examples will be illustrated and explained in detail herein. However, this is not intended to limit the present invention to any particular disclosed form, and it should be understood that all modifications, equivalents, or alternatives within the scope of the present invention are encompassed by this disclosure.

[0053] In addition, the technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present invention. Unless the context otherwise indicates, singular expressions used herein may include plural expressions.

[0054] On the other hand, the term "polymer" used herein refers to a compound produced by polymerizing monomer compounds, and includes homopolymers and copolymers.

[0055] In addition, the alkyl group used herein may be linear or branched, and its carbon number is not particularly limited, but is preferably 1 to 10. According to one embodiment, the alkyl group has 1 to 6 carbon atoms. According to another embodiment, the alkyl group has 1 to 4 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1-ethylpropyl, 1,1-dimethylpropyl, hexyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2,4,4-trimethyl-1-pentyl, 2,4,4-trimethyl-2-pentyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, and the like, but are not limited thereto.

[0056] In the present invention, the alkyl group is as defined above, but the alkylene group is not a monovalent group but a divalent group.

[0057] In the present invention, halogen means fluorine, chlorine, bromine or iodine.

[0058] In recent years, with the growing demand for fuel cells as a next-generation energy source, interest in anion exchange membranes has grown to overcome the limitations of cation exchange membrane fuel cells. However, increasing the degree of crosslinking to improve the durability of anion exchange membranes, such as dimensional stability and alkaline stability, has led to a decrease in ionic conductivity.

[0059] To this end, the inventors discovered that by preparing a polymer with a halogenated alkyl group introduced into the side chain through the hydrogenation reaction and atom transfer radical polymerization reaction of a styrene-isoprene-styrene triblock copolymer, and then cross-linking the polymer with a diamine compound, the distance between the ionic bond and the main chain can be extended, thereby improving the ionic conductivity; at the same time, by forming dozens of nanostructures, fine phase separation is achieved, which is conducive to the movement of ions in the nanochannel, and its mechanical strength far exceeds that of a single polymer, thereby enabling the preparation of a more durable anion exchange membrane, and completing the present invention.

[0060] Now, the novel polymer according to specific embodiments of the present invention, the preparation method thereof, the anion exchange membrane including the polymer, and the method for preparing the anion exchange membrane will be described in more detail.

[0061] Polymer and preparation method thereof

[0062] In one embodiment, a polymer comprising a cross-linked structure shown in the following Chemical Formula 1 is provided:

[0063] [Chemical Formula 1]

[0064]

[0065] Wherein, in Chemical Formula 1,

[0066] R1 and R2 are each independently halogen or C 1-4 alkyl,

[0067] a and b are each independently an integer from 0 to 3,

[0068] R3 and R4 are each independently hydrogen or C 1-4 alkyl,

[0069] R5 is C 1-10 alkyl,

[0070] R6 to R9 are each independently C 1-4 alkyl,

[0071] L is C 1-10 Alkylene,

[0072] Q is a halogen,

[0073] n is an integer from 1 to 3,

[0074] x, y and z represent the mole fraction of each repeating unit in the polymer, and x+y+z=1.

[0075] The polymer is an ionomer, the main chain of which is neutral and the side chains have ionic bonds, so the polymer exhibits ion conductivity.

[0076] The polymer includes the cross-linked structure shown in Chemical Formula 1 and ultimately exhibits a film-like shape, so the weight-average molecular weight of the polymer is not limited. However, for example, if the number of cross-linked structures shown in Chemical Formula 1 in the polymer is defined as m, then m can be 1 to 100,000,000.

[0077] In addition, the polymer may include not only the cross-linked structure shown in Chemical Formula 1 but also the non-cross-linked structure shown in the following Chemical Formula 2.

[0078] [Chemical Formula 2]

[0079]

[0080] In other words, the polymer may have a partially cross-linked structure.

[0081] At this time, the cross-linked structure represented by Chemical Formula 1 and the non-cross-linked structure represented by Chemical Formula 2 may be included in the polymer at a molar ratio of 1:0.5 to 1:10.

[0082] In addition, in Chemical Formula 1, a and b represent the number of R1 and R2, respectively. When a is 2 or more, two or more R1s may be the same or different; when b is 2 or more, two or more R2s may be the same or different.

[0083] More specifically, R1 and R2 are each independently chlorine, bromine, methyl or tert-butyl,

[0084] a and b can each independently be 0 or 1.

[0085] At this time, R1 and R2 can be the same as each other,

[0086] a and b may be identical to each other.

[0087] Furthermore, R3 and R4 may each independently be hydrogen or methyl.

[0088] For example, R3 can be methyl.

[0089] Additionally, for example, R4 can be hydrogen.

[0090] In addition, R5 can be C 1-10 alkyl.

[0091] For example, R5 can be n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, or n-octyl.

[0092] Preferably, R4 may be hydrogen, and

[0093] R5 can be n-pentyl, n-hexyl, n-heptyl or n-octyl.

[0094] Furthermore, R6 to R9 may all be the same.

[0095] For example, R6 to R9 may all be methyl groups or ethyl groups.

[0096] In addition, L can be C 4-10 Alkylene.

[0097] For example, L can be butylene, pentylene, hexylene, or heptylene.

[0098] Additionally, Q may be chlorine (Cl).

[0099] In Chemical Formula 1, x, y, and z are each the value obtained by dividing the number of moles of the repeating unit in the brackets by half the number of moles of all repeating units in the cross-linked structure represented by Chemical Formula 1, and x + y + z is 1. In addition, x, y, and z are each the mole fractions of each block in the triblock copolymer used as a starting material for preparing a polymer containing the cross-linked structure represented by Chemical Formula 1. Specifically, when each block in the triblock copolymer is defined as A, B, and C, and the number of repetitions thereof is defined as a, b, and c, x can be calculated as a / (a+b+c), y can be calculated as b / (a+b+c), and z can be calculated as c / (a+b+c).

[0100] Specifically, x, y, and z are each independently a real number greater than 0 and less than 1.

[0101] More specifically, x and z may each independently be a real number between 0.01 and 0.5, and y may be a real number between 0.3 and 0.9.

[0102] For example, x may be a real number between 0.1 and 0.25, y may be a real number between 0.5 and 0.8, and z may be a real number between 0.1 and 0.25.

[0103] Furthermore, x+z may be 0.2 to 0.5. More specifically, x+z may be 0.2 or more, 0.21 or more, 0.22 or more, 0.23 or more, or 0.24 or more, and may be 0.5 or less, 0.45 or less, 0.4 or less, 0.35 or less, 0.3 or less, or 0.25 or less.

[0104] At this time, x and z may be the same as each other.

[0105] Furthermore, y may more specifically be 0.5 or more, 0.55 or more, 0.6 or more, 0.65 or more, 0.7 or more, or 0.75 or more, and may be 0.8 or less, 0.79 or less, 0.78 or less, or 0.77 or less, or 0.76 or less.

[0106] In addition, the polymer may be derived from a triblock copolymer represented by the following Chemical Formula 1-1, having a weight average molecular weight of 50,000 to 400,000 g / mol:

[0107] [Chemical Formula 1-1]

[0108]

[0109] In Chemical Formula 1-1,

[0110] R1, R2, a, b, x, y and z are as defined in Chemical Formula 1.

[0111] In another embodiment, a method for preparing a polymer comprising a cross-linked structure as shown in Chemical Formula 1 is provided, wherein the polymer is prepared by steps 1 to 3 in the following Reaction Formula 1:

[0112] [Reaction formula 1]

[0113]

[0114] Among them, in the reaction formula,

[0115] R1 to R9, L, Q, a, b, n, x, y, and z are as defined in Chemical Formula 1.

[0116] (Step 1)

[0117] Step 1 is a step of reacting a first polymer (an ABC triblock copolymer as shown in Chemical Formula 1-1) with hydrogen halide (HQ; wherein Q is a halogen) to prepare a second polymer (an A-B'-C triblock copolymer as shown in Chemical Formula 1-2), wherein the reaction is a hydrogen halide addition reaction in which hydrogen halide is added to the double bonds of the first polymer.

[0118] The first polymer represented by Chemical Formula 1-1 is an ABC triblock copolymer formed by copolymerization of a styrene-based monomer, a conjugated diene-based monomer having 4 carbon atoms, and a styrene-based monomer, and has a one-dimensional linear polymer structure in which repeating units are arranged in a long chain. More specifically, in the first polymer, block A represents the block represented by the following Chemical Formula A, block B represents the block represented by the following Chemical Formula B, and block C represents the block represented by the following Chemical Formula C.

[0119] [Chemical Formula A]

[0120]

[0121] [Chemical Formula B]

[0122]

[0123] [Chemical Formula C]

[0124]

[0125] For example, considering the ease of synthesis and production cost, the first polymer represented by Chemical Formula 1-1 is preferably a styrene-isoprene-styrene triblock copolymer (styrene-b-isoprene-b-styrene; SIS).

[0126] In addition, as described above, the weight average molecular weight of the first polymer can be 50,000 to 400,000 g / mol. Here, the weight average molecular weight of the triblock copolymer can be determined by gel permeation chromatography (GPC) using a calibration curve created with polystyrene standards. More specifically, the weight average molecular weight (Mw, g / mol) of the polymer can be 50,000 or more, 60,000 or more, 70,000 or more, or 80,000 or more, and 400,000 or less, 300,000 or less, 200,000 or less, or 100,000 or less.

[0127] In the above steps, the amount of hydrogen halide used can be 2 to 3 moles relative to 1 mole of the B block unit in the first polymer represented by Chemical Formula 1-1. If the amount of hydrogen halide used is too low, there is a risk of prolonged reaction time, and even if the amount of hydrogen halide used is too large, the reaction time will not be different. Therefore, it is preferred to use hydrogen halide within the above range. More specifically, in the above steps, the amount of hydrogen halide used can be 2 moles or more, 2.1 moles or more, 2.2 moles or more, 2.3 moles or more, 2.4 moles or more, or 2.5 moles or more, and 3 moles or less or 2.95 moles or less, relative to 1 mole of the B block unit in the first polymer represented by Chemical Formula 1-1.

[0128] In addition, the reaction can be carried out in an organic solvent, such as toluene, dichloromethane, chloroform, dimethylformamide, dioxane, tetrahydrofuran, etc. The amount (mL / g) of the organic solvent can be 5 to 20 times (by volume) the weight of the first polymer represented by Chemical Formula 1-1. More specifically, the amount (mL / g) of the organic solvent can be 10 to 15 times (by volume) the weight of the first polymer represented by Chemical Formula 1-1.

[0129] In addition, the reaction can be carried out for 12 to 24 hours at 20 to 30° C. The above range is preferred from the viewpoints of reaction rate and yield.

[0130] (Step 2)

[0131] Step 2 is a step of reacting the second polymer (the A-B'-C triblock copolymer shown in Chemical Formula 1-2) with the olefin shown in Chemical Formula 1a to prepare a third polymer (the A-B'-C triblock copolymer shown in Chemical Formula 1-3), wherein the reaction is carried out by atom transfer radical polymerization (ATRM).

[0132] In the second polymer, the A block and the C block are the same as described above, and the B' block refers to a block represented by the following chemical formula B'.

[0133] [Chemical Formula B']

[0134]

[0135] In the above steps, the amount of the olefin represented by Chemical Formula 1a can be 10 to 100 moles relative to 1 mole of the B' block unit in the second polymer represented by Chemical Formula 1-2. If the amount of the olefin is too low, the length of the side chain may be shortened, thereby reducing the durability of the film; and if the amount of the olefin is too large, there is a problem of inhibiting the reaction. Therefore, the amount of the olefin is preferably within the above range. More specifically, in the above steps, the amount of the olefin represented by Chemical Formula 1a can be 10 moles or more, 20 moles or more, 30 moles or more, or 40 moles or more, and 100 moles or less, 90 moles or less, 80 moles or less, 70 moles or less, or 60 moles or less, relative to 1 mole of the B' block unit in the second polymer represented by Chemical Formula 1-2.

[0136] In addition, the reaction can be carried out in an organic solvent, such as toluene, dichloromethane, chloroform, dimethylformamide, dioxane, dimethylformamide, tetrahydrofuran, etc. Here, the amount (mL / g) of the organic solvent can be 10 to 30 times (by volume) the weight of the second polymer represented by Chemical Formula 1-2. More specifically, the amount (mL / g) can be 15 to 20 times (by volume) the weight of the second polymer represented by Chemical Formula 1-2.

[0137] Furthermore, the reaction may be performed at 50 to 100° C. for 1 to 72 hours. The above range is preferable from the viewpoints of reaction rate and yield.

[0138] (Step 3)

[0139] Step 3 is a step of reacting a third polymer (AB"-C triblock copolymer shown in Chemical Formula 1-3) with a diamine shown in Chemical Formula 1b to prepare a polymer having a cross-linked structure shown in Chemical Formula 1, wherein two third polymers shown in Chemical Formula 1-3 are cross-linked by the diamine through the above reaction.

[0140] In the third polymer, the A block and the C block are the same as described above, and the B" block refers to a block represented by the following chemical formula B".

[0141] [Chemical Formula B"]

[0142]

[0143] In the above steps, the amount of the diamine represented by Chemical Formula 1b can be 0.1 to 0.3 mol relative to 1 mol of the B" block units in the third polymer represented by Chemical Formula 1-3. If the amount of the diamine used is too low, there is a risk of reduced crosslinking, resulting in decreased mechanical properties of the membrane; while if the amount of the diamine used is too high, there is a risk of reduced ionic conductivity or decreased physical properties of the membrane due to residual unreacted diamine. Therefore, it is preferred to use the diamine within the above range. More specifically, in the above steps, the amount of the diamine represented by Chemical Formula 1b can be 0.1 mol or more, 0.11 mol or more, 0.12 mol or more, 0.13 mol or more, or 0.14 mol or more, and 0.3 mol or less, 0.25 mol or less, 0.2 mol or less, 0.19 mol or less, 0.18 mol or less, 0.17 mol or less, or 0.16 mol or less, relative to 1 mol of the B" block units in the third polymer represented by Chemical Formula 1-3.

[0144] In addition, the reaction can be carried out in one or more organic solvents selected from tetrahydrofuran, chloroform, dichloromethane, and toluene. The amount (mL / g) of the organic solvent can be 10 to 30 times (by volume) the weight of the third polymer represented by Chemical Formula 1-3. More specifically, the amount (mL / g) can be 15 to 25 times (by volume) the weight of the third polymer represented by Chemical Formula 1-3.

[0145] In addition, the reaction can be carried out by stirring at 20 to 30°C for 1 minute to 3 hours.

[0146] More specifically, after stirring, the organic solvent is removed under vacuum at 40 to 80° C. for 12 to 24 hours, and then further reacted under vacuum at 80 to 150° C. for 24 to 72 hours.

[0147] Anion exchange membrane and preparation method thereof

[0148] On the other hand, in another embodiment, an anion exchange membrane is provided, which includes a polymer having a cross-linked structure shown in Chemical Formula 1.

[0149] In another embodiment, a method for preparing the above-mentioned anion exchange membrane is provided, the method comprising the following steps 1 to 3:

[0150] reacting the third polymer represented by Chemical Formula 1-3 with the diamine represented by Chemical Formula 1b in an organic solvent to prepare a polymer solution containing a cross-linked structure represented by Chemical Formula 1 (step 1); and

[0151] The polymer solution is cast onto a substrate and the cast film is then dried (step 2).

[0152] (Step 1)

[0153] Step 1 is a step of using a diamine compound as a crosslinking agent in an organic solvent to crosslink the third polymer represented by Chemical Formula 1-3 and prepare a polymer solution for coating in the form of a thin film.

[0154] In step 1, the organic solvent may be one or more selected from tetrahydrofuran, chloroform, dichloromethane, and toluene. The amount (mL / g) of the organic solvent may be 10 to 30 times (by volume) the weight of the third polymer represented by Chemical Formula 1-3. More specifically, the amount may be 15 to 25 times (by volume) the weight of the third polymer represented by Chemical Formula 1-3.

[0155] (Step 2)

[0156] In addition, step 2 is a step of casting the polymer solution onto a substrate and then drying the cast film. In the above step, the polymer solution is applied to the substrate to a certain thickness and then dried to remove the organic solvent in step 1, thereby preparing a thin film.

[0157] The substrate used at this time may be a glass substrate that is easy to peel off the cast anion exchange membrane. In addition, the polymer solution may be applied to the substrate to a thickness of 20 to 80 μm.

[0158] Furthermore, the drying in step 2 may be performed at 40 to 80° C. for 12 to 24 hours. Specifically, the drying may be performed by vacuum drying, and the organic solvent in step 1 may be completely removed by the drying step.

[0159] Furthermore, a heat treatment step at 80 to 150° C. for 24 to 72 hours may be further performed after step 2. The heat treatment may be performed in a vacuum, and the crosslinking reaction may be further performed by the heat treatment step.

[0160] The anion exchange membrane prepared by this method can be made into a thickness of 20 to 80 μm.

[0161] On the other hand, in another embodiment, a fuel cell comprising the above anion exchange membrane is provided.

[0162] Furthermore, in another embodiment, an alkaline electrolytic cell comprising the above anion exchange membrane is provided.

[0163] In order to better understand the present invention, preferred embodiments are provided below. However, these embodiments are only for illustrative purposes, and the scope of the present invention is not limited thereto.

[0164] Example 1: Preparation of a polymer containing a cross-linked structure represented by XL-SIS-hex-Cl and an anion exchange membrane containing the polymer

[0165]

[0166] (Step 1) Hydrochlorination Reaction

[0167] In a 250 mL flask, 5 g of the first polymer, i.e., styrene-isoprene-styrene triblock copolymer (styrene-b-isoprene-b-styrene; SIS, the number of blocks in the copolymer: styrene (136), isoprene (838), styrene (136); x = 0.1225, y = 0.7550, z = 0.1225); Mw = 90,000 g / mol) (the number of moles of isoprene in the B block in 5 g: 0.04194 mmol), 120 mL of toluene, 120 mL of hydrogen chloride dissolved in acetic acid (pure hydrogen chloride: 3 mL, 0.1226 mmol, 2.923 mol relative to 1 mol of isoprene) and a magnetic bar were added, and the reaction was carried out at room temperature for 24 hours. After the reaction, the precipitate was collected in 5 L of methanol, and then collected in 5 L of methanol again. Water and solvent were removed under vacuum at room temperature to obtain a chloro-substituted styrene-isoprene-styrene second polymer (SIS-Cl).

[0168] (Step 2) ATRP (alkylation)

[0169] In a 250 mL flask, 5 g of the second polymer (SIS-Cl) obtained in step 1 (the number of moles of the isoprene-derived B' block in 5 g: 31.765 mmol), 200 mL of toluene, 196.9 mL of 1-hexene (1588.5 mmol, 50 mol per 1 mol of B' block), 1.8 g of copper (I) bromide, 2.6 mL of pentamethyldiethylenetriamine, and a magnetic bar were added and reacted at 60°C for 1.5 hours. After the reaction was complete, the solution was filtered through an alumina column, and the solvent was removed in vacuo at 60°C. The precipitate was then collected in 2 liters of methanol, and the precipitate was collected in 2 liters of methanol. The water and solvent were removed in vacuo at room temperature to obtain a third polymer, styrene-isoprene-styrene (SIS-hex-Cl), which contains 1-hexene units and has chlorine groups substituted at the end of the side chains.

[0170] (Step 3) Cross-linking

[0171] To a 20 mL vial, 0.3 g of the third polymer (SIS-hex-Cl) obtained in step 2 (the number of moles of the isoprene-derived B" block in 0.3 g: 1.88 mmol), 6 mL of the organic solvent tetrahydrofuran, 0.0487 g of N,N,N',N'-tetramethyl-1,6-hexanediamine (0.283 mmol, 0.15 mol per 1 mol of the B" block), and a magnetic bar were added, and the mixture was stirred at room temperature for 5 minutes to prepare a polymer solution containing the cross-linked structure shown in XL-SIS-hex-Cl.

[0172] Subsequently, the polymer solution was uniformly applied to a Petri dish having a diameter of 9 cm to a thickness of 60 μm, cast, and vacuum-dried at 60° C. for 24 hours to remove the solvent, thereby preparing a membrane.

[0173] Next, the membrane was heat treated at 100°C in a vacuum state for 48 hours to further promote the reaction, thereby obtaining a transparent anion exchange membrane (XL-SIS-hex-QA) with a thickness of 30 μm, as shown in the following photo. Figure 1 shown.

[0174] Test Example 1: 1 H NMR analysis

[0175] The second polymer (SIS-Cl) and the third polymer (SIS-hex-Cl) prepared in steps 1 and 2 of Example 1 1 H NMR analysis spectrum Figure 2 In addition, in order to confirm whether the synthesis is going smoothly, Figure 3 The first polymer (SIS) is also shown in 1 H NMR analysis spectrum. At this time, CDCl3 was used as a reference or a built-in deuterium lock device on an Agilent 400-MR (400 MHz) instrument to obtain 1 H NMR spectrum.

[0176] Compare Figure 2 The spectrum of the second polymer (SIS-Cl) and Figure 3 From the spectrum of the first polymer (SIS), it can be seen that Figure 3 The peak intensity of the isoprene group in the first polymer (SIS) is higher at 4.5 to 5.3 ppm, while Figure 2 The second polymer (SIS-Cl) showed almost no peak of isoprene groups, which means that the synthesis of the first polymer to the second polymer was satisfactory, and the conversion rate of the synthesis from the first polymer to the second polymer was above 98%, calculated based on the ratio of the isoprene group peaks.

[0177] Compare Figure 2 From the spectra of the second polymer (SIS-Cl) and the third polymer (SIS-hex-Cl), it can be seen that in the third polymer (SIS-hex-Cl), the peak intensity at 2.2 ppm of the third carbon atom is higher than that in the second polymer (SIS-Cl).

[0178] This is because the carbon atom shown by b is introduced by the 1-hexene compound. Therefore, by comparing these peaks, it can be confirmed that the third polymer has been successfully synthesized in Step 2 of Example 1.

[0179] On the other hand, the n value of the third polymer (SIS-hex-Cl) prepared in step 2 of Example 1 can be obtained by 1 The value of n was determined by the integrated value of peak a and the integrated value of peak a+b in the H NMR analysis spectrum.

[0180] Test Example 2: FT-IR analysis

[0181] The first polymer (SIS) as the starting material of Example 1, as well as the second polymer (SIS-Cl), the third polymer (SIS-hex-Cl) and the anion exchange membrane (XI-SIS-hex-QA) prepared in Example 1 were analyzed by FT-IR. The results are as follows: Figure 4 shown.

[0182] See also Figure 4 , comparing the spectrum of the third polymer (SIS-hex-Cl) and the spectrum of the anion exchange membrane (Xl-SIS-hex-QA), it can be seen that the third polymer (SIS-hex-Cl) has a peak at 985 cm -1 The peaks associated with carbon-nitrogen bonds in the quaternary ammonium structure do not appear at [C], whereas the peak intensity for the anion exchange membrane (Xl-SIS-hex-QA) is higher. This confirms that the anion exchange membrane (Xl-SIS-hex-QA) with a quaternary ammonium structure was successfully prepared using the third polymer (SIS-hex-Cl).

[0183] Test Example 3: Anion Exchange Membrane Performance Measurement

[0184] By comparing and calculating 1 The relative integral width between the protons of the aromatic group and the methyl group in the H NMR spectrum was used to determine the ion exchange capacity of the anion exchange membrane prepared in the example. The results are shown in Table 1 and compared with the commercial anion exchange membrane ( FAA-3-50, produced by Fumatech Corporation) was compared.

[0185] In addition, the OH-type moisture content and swelling degree of the anion exchange membrane and FAA-3-50 prepared in the example were also measured. Specifically, after ion exchange, the membrane of a specific form was rinsed several times with ultrapure water, and then the hydrated membrane was quickly wiped with filter paper to remove surface moisture. Then, the weight (m wet) and unidirectional length (L wet) of the hydrated membrane were recorded, and then the filter paper was covered to prevent the membrane from shrinking and dried in a vacuum oven at 90°C for 24 hours to maintain a constant weight. The weight of the dried membrane (m wet) was then immediately recorded. 干 ) and one-way length (L 干Finally, the moisture content and swelling degree were calculated according to the following formula 1 and formula 2, respectively. The results are listed in the following Table 1.

[0186] [Formula 1]

[0187] Moisture content (%) = [(m 湿 -m 干 ) / m 干 ]x 100

[0188] [Formula 2]

[0189] Expansion (%) = [(L 湿 -L 干 ) / L 干 ]x 100

[0190] In addition, the thickness of each anion exchange membrane was measured using high-purity deionized water produced by Deoksan Chemical Co., Ltd. Then, four Bekktech probe conductivity cells were connected to an alternating current (AC) impedance test to measure the ionic conductivity of the anion exchange membranes prepared in the examples and FAA-3-50 under 80°C / 100% RH conditions. The results are shown in Table 1 below.

[0191] [Table 1]

[0192]

[0193] Referring to Table 1, it can be confirmed that the anion exchange membrane of Example 1 including the polymer having a cross-linked structure represented by Chemical Formula 1 exhibits improved ion exchange performance, water content, swelling degree, and ion conductivity compared to the anion exchange membrane of Comparative Example 1 (FAA-3-50).

Claims

1. A polymer comprising a cross-linked structure represented by the following Chemical Formula 1: [Chemical Formula 1] in, In Chemical Formula 1, R1 and R2 are each independently halogen or C 1-4 alkyl, a and b are each independently an integer from 0 to 3, R3 and R4 are each independently hydrogen or C 1-4 alkyl, R5 is C 1-10 alkyl, R6 to R9 are each independently C 1-4 alkyl, L is C 1-10 Alkylene, Q is a halogen, n is an integer from 1 to 3, and x, y and z represent the mole fraction of each repeating unit in the polymer, respectively, and x+y+z=1.

2. The polymer according to claim 1, wherein: R1 and R2 are each independently chlorine, bromine, methyl or tert-butyl, and a and b are each independently 0 or 1.

3. The polymer according to claim 1, wherein: R3 is methyl.

4. The polymer according to claim 1, wherein: R4 is hydrogen, and R5 is n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl or n-octyl.

5. The polymer according to claim 1, wherein: R6 to R9 are all methyl or ethyl.

6. The polymer according to claim 1, wherein: L is butylene, pentylene, hexylene or heptylene.

7. The polymer according to claim 1, wherein: Q is chlorine.

8. The polymer of claim 1, wherein: x+z is 0.2 to 0.

5.

9. The polymer of claim 1, wherein: The polymer is derived from a triblock copolymer represented by the following chemical formula 1-1, and has a weight average molecular weight of 50,000 to 400,000 g / mol. [Chemical Formula 1-1] In Chemical Formula 1-1, R1, R2, a, b, x, y and z are as defined in claim 1.

10. A method for preparing a polymer comprising a cross-linked structure represented by the following Chemical Formula 1, the method comprising the following steps: Reacting a first polymer with hydrogen halide to prepare a second polymer, wherein the first polymer is an ABC triblock copolymer represented by the following chemical formula 1-1, and the second polymer is an A-B'-C triblock copolymer represented by the following chemical formula 1-2 (step 1); Reacting the second polymer represented by the following Chemical Formula 1-2 with the olefin represented by the following Chemical Formula 1a to prepare a third polymer, wherein the third polymer is an AB"-C triblock copolymer represented by the following Chemical Formula 1-3 (step 2); and The third polymer represented by the following Chemical Formula 1-3 is reacted with the diamine represented by the following Chemical Formula 1b to prepare a polymer having a cross-linked structure represented by the following Chemical Formula 1 (step 3): [Chemical Formula 1] [Chemical Formula 1-1] [Chemical formula 1-2] [Chemical formula 1-3] [Chemical Formula 1a] [Chemical Formula 1b] Wherein, in Chemical Formulas 1, 1-1 to 1-3, 1a and 1b, R1 and R2 are each independently halogen or C 1-4 alkyl, a and b are each independently an integer from 0 to 3, R3 and R4 are each independently hydrogen or C 1-4 alkyl, R5 is C 1-10 alkyl, R6 to R9 are each independently C 1-4 alkyl, L is C 1-10 Alkylene, Q is a halogen, n is an integer from 1 to 3, and x, y and z each represent the mole fraction of each repeating unit in the polymer, and x+y+z=1.

11. The method according to claim 10, wherein: In step 1, the amount of the hydrogen halide used is 2 to 3 moles relative to 1 mole of the B block unit in the first polymer represented by Chemical Formula 1-1.

12. The method according to claim 10, wherein: In step 2, the amount of the olefin represented by Chemical Formula 1a used is 10 to 100 moles relative to 1 mole of the B' block unit in the second polymer represented by Chemical Formula 1-2.

13. The method according to claim 10, wherein: The reaction in step 2 is carried out at 50 to 100° C. for 1 to 72 hours.

14. The method according to claim 10, wherein: In step 3, the amount of the diamine represented by Chemical Formula 1b is 0.1 to 0.3 moles relative to 1 mole of the B″ block unit in the third polymer represented by Chemical Formula 1-3.

15. An anion exchange membrane comprising the polymer according to claim 1.

16. A method for manufacturing an anion exchange membrane, the method comprising the following steps: reacting a third polymer represented by the following Chemical Formula 1-3 with a diamine represented by the following Chemical Formula 1b in an organic solvent to prepare a polymer solution including a cross-linked structure represented by the following Chemical Formula 1 (step 1); and Casting the polymer solution onto a substrate and then drying the cast film (step 2), [Chemical Formula 1] [Chemical formula 1-3] [Chemical Formula 1b] Wherein, in Chemical Formulas 1, 1-3 and 1b, R1 and R2 are each independently halogen or C 1-4 alkyl, a and b are each independently an integer from 0 to 3, R3 and R4 are each independently hydrogen or C 1-4 alkyl, R5 is C 1-10 alkyl, R6 to R9 are each independently C 1-4 alkyl, L is C 1-10 Alkylene, Q is a halogen, n is an integer from 1 to 3, and x, y and z represent the mole fraction of each repeating unit in the polymer, respectively, and x+y+z=1.

17. The method according to claim 16, wherein: In step 1, the organic solvent is one or more selected from tetrahydrofuran, chloroform, toluene and dichloromethane.

18. The method of claim 16, wherein: The drying in step 2 is performed at 40 to 80° C. for 12 to 24 hours.

19. The method of claim 16, wherein: After step 2, a heat treatment step is further performed at 80 to 150° C. for 24 to 72 hours.

20. The method of claim 16, wherein: The thickness of the prepared anion exchange membrane is 20 to 80 μm.

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