Styrenic block copolymer composition and anion exchange membranes made thereof

Abstract

To provide polymers having improved thermal and dimensional stability, longer durability and enhanced ion exchange capacity (IEC), particularly polymers with good phase separation between hydrophilic and hydrophobic phases for use as anion-exchange membranes.SOLUTION: The disclosure relates to a hydrogenated styrene-based multiblock copolymer composition, having selectively quaternized midblock, for forming anion-exchange membranes (AEMs). The quaternized hydrogenated styrene-based multiblock copolymer has a high glass transition temperature from the hydrophobic end-blocks, low vinyl (rubber) content and quaternized mid-block. AEMs made of the composition have improved thermal and dimensional stability in electrolyzer operations.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to styrene block copolymer anion exchange membranes (AEMs), methods for preparing them, and applications. [Background technology]

[0002] Electrochemical water splitting is one of the practical systems for green hydrogen production. In recent decades, alkaline electrolytic cells and proton exchange membrane (PEM) electrolytic cells have been the most widely used techniques in the hydrogen processing industry. Both techniques have several challenges for cell construction, such as hydrogen handling, large structures, and the need for platinum (Pt). Anion exchange membrane (AEM) electrolytic cells can help overcome these challenges, including the ability to use non-Pt materials, high hydrogen storage density, and high-density microcell structures. Polymeric alkali membranes are a critical component that affects the efficiency of AEM electrolytic cells. The lifespan of an AEM electrolytic cell can be determined by the polymer backbone used to manufacture the AEM.

[0003] Hydrogenated styrene-butadiene block copolymer (SEBS) has broad potential applications due to its unique properties of alternating soft and hard blocks and a full carbon backbone, resulting in phase separation and good alkali resistance. However, SEBS-based alkali films exhibit significant swelling and low dimensional stability due to their characteristic fatty chain skeletal structure, and their mechanical properties are generally insufficient in aqueous environments. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] There is still a need for polymers with improved thermal and dimensional stability, longer durability, and higher ion exchange capacity (IEC), particularly polymers with good phase separation between hydrophilic and hydrophobic phases used as anion exchange membranes. [Means for solving the problem]

[0005] (Summary of the invention) In a first embodiment, the disclosure relates to a selectively quaternized styrene multiblock copolymer comprising, or consisting thereof, basically a block A derived from either (i) a para-substituted vinyl aromatic monomer or (ii) an unsubstituted vinyl aromatic monomer, a block B comprising polymerized hydrogenated 1,4-isoprene units or 1,2 and 1,4-butadiene units, and a block C derived from a vinyl aromatic monomer that is susceptible to quaternization as an intermediate or terminal block, and having a general configuration of a pentablock, a tetrablock, or a triblock having a random structure including B / C or C / B. The selectively quaternized hydrogenated styrene block copolymer has an ion exchange capacity (IEC) of 0.5 to 4.0 meq / g, and block C is quaternized and has a quaternary ammonium cation and a degree of quaternization of 30 mol% to 95 mol%.

[0006] In another embodiment, selectively quaternized hydrogenated styrene block copolymers are pentablocks having structures selected from ABCBA, CBABA, ACBCA, BCACB, and mixtures thereof.

[0007] In another embodiment, an anion exchange membrane comprising the selectively quaternized styrene multiblock copolymer described in the first embodiment can be used as an ionomer and membrane in any of the following applications: water electrolytic cell electrolyte, fuel cell separator, anion exchange membrane, proton exchange membrane, electrode assembly, and water electrolytic cell. [Modes for carrying out the invention]

[0008] The following terms have the following meanings:

[0009] "[A, B, and C, etc.] at least one of these groups" or "[A, B, and C, etc.] any of these groups" means a single member from a group, multiple members from a group, or a combination of members from a group. For example, "A, B, and C, at least one of these groups" includes, for example, A only, B only, or C only, as well as A and B, A and C, B and C; or A, B, and C or all other combinations of A, B, and C.

[0010] "X1, X2, X3, ...X n "Selected from and mixtures thereof" means a single member of the group or multiple members of the group, for example X1, X2, X3, ... X n or group X1~X n Some or all of the members exist.

[0011] The list of embodiments presented as "A, B, or C" should be interpreted as including embodiments: A only, B only, C only, "A or B", "A or C", "B or C", or "A, B, or C".

[0012] As used herein, "block" refers to a section of polymer molecules containing multiple identical constituent units (monomers) and having at least one constitutive or arrangemental feature that does not appear in an immediately adjacent section (block).

[0013] "Conjugated diene" refers to an organic compound containing a total of 4 to 12 carbon atoms, such as a conjugated carbon-carbon double bond and 4 to 8 carbon atoms, and may include, but not limited to, any substituted butadiene such as 1,3-butadiene and 1,3-cyclohexadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1,3-pentadiene, 3-butyl-1,3-octadiene, chloroprene and piperine, or any combination thereof. In embodiments, the conjugated diene block contains a mixture of butadiene and isoprene monomers. In embodiments, 1,3-butadiene is used alone.

[0014] "Butadiene" refers to 1,3-butadiene.

[0015] "Monovylarene," "monoalkenylarene," or "vinyl aromatic" refers to an organic compound containing a single carbon-carbon double bond, at least one aromatic moiety, and a total of 8 to 18 carbon atoms, such as 8 to 12 carbon atoms. Examples include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, alpha-methylstyrene, vinylnaphthalene, vinyltoluene, vinylxylene, or any mixture thereof. In embodiments, the monoalkenylarene block contains substantially pure monoalkenylarene monomer. In some embodiments, styrene is the main component, but a small proportion (less than 10% by weight) of structurally related vinyl aromatic monomers is included, such as o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, alpha-methylstyrene, vinylnaphthalene, vinyltoluene, vinylxylene, or a combination thereof. In embodiments, only styrene is used.

[0016] "Vinyl content" refers to the content of conjugated dienes polymerized via 1,2-addition in the case of butadiene, or via 3,4-addition in the case of isoprene, resulting in monosubstituted olefins or vinyl groups adjacent to the polymer backbone. Vinyl content can be measured by nuclear magnetic resonance spectroscopy (NMR).

[0017] The "coupling efficiency," expressed as % CE, is calculated using the weight percentages of the linked and unlinked polymers. The weight percentages of the linked and unlinked polymers are determined using the output of a differential refractive index detector. The signal intensity at a particular elution volume is proportional to the amount of material with the molecular weight corresponding to the polystyrene standard detected at that elution volume.

[0018] "Coupling agent" or "X" refers to coupling agents commonly used in styrene block copolymer (SBC) manufacturing technology, such as silane coupling agents like isobutyl-trimethoxysilane and methyltrimethoxysilane; polyvinyl compounds, polyvinylarenes, di- or multivinylarene compounds; di- or multiepoxides; di- or multiisocyanates; di- or multialkoxysilanes; di- or multiimines; di- or multialdehydes; di- or multiketones; alkoxytin compounds; di- or multihalides such as silicon halides and halosilanes; mono-, di- or multianhydrides; di- or multiesters; tin tetrachloride; and tetramethyl orthosilicate.

[0019] The "polystyrene content" or PSC of a block copolymer refers to the weight percentage of polystyrene in the vinyl aromatics, such as polystyrene, calculated by dividing the total molecular weight of all vinyl aromatic blocks by the total molecular weight of the block copolymer. PSC can be determined using any suitable methodology, such as proton nuclear magnetic resonance (NMR).

[0020] "Molecular weight" or MW refers to the styrene-equivalent molecular weight (kg / mol) of a polymer block or block copolymer. MW can be measured using gel permeation chromatography (GPC) with a polystyrene calibration standard, for example, according to ASTM 5296-19. The GPC detector may be an ultraviolet detector, a refractive index detector, or a combination thereof. The chromatograph is calibrated using a commercially available polystyrene molecular weight standard. The MW of a polymer measured using such a calibrated GPC is the styrene-equivalent molecular weight or apparent molecular weight. As expressed herein, MW is measured at the peak of the GPC trace and is generally referred to as the styrene-equivalent "peak molecular weight". p This is shown as follows.

[0021] When used in connection with a specified monomer, "primary" means that the monomer can be used in a substantially pure form or that the monomer can be intentionally mixed with a certain small amount of comonomer (less than 20% by weight or less than 10% by weight or less than 5% by weight or less than 1% by weight), which may be structurally similar or different from the main monomer component of the block segment.

[0022] "Anion exchange membrane" or "alkali exchange membrane" or "AEM" generally refers to a semipermeable membrane made from an ionomer and designed to conduct anions and repel cations.

[0023] "Anion exchange membrane electrolyzer (AEME)" or "anion exchange membrane water electrolyzer (AEMWE)" refers to an electrolyzer having an ion-conductive polymer electrolyte membrane that separates the cathode from the anode. The electrolyzer uses electricity to split water (H2O) into hydrogen and oxygen by an electrochemical reaction.

[0024] "Fuel cell" refers to an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidant (often oxygen) into electricity by a pair of redox reactions.

[0025] "Selectively quaternized" refers to a controlled quaternization selectively directed to either the middle block or the end block of a multiblock copolymer.

[0026] "Ion exchange capacity" or IEC refers to the entire active site or functional group of a polymer that is responsible for ion exchange. Generally, conventional acid-base titration methods are used to determine IEC; see, for example, International Journal of Hydrogen Energy, Volume 39, Issue 10, March 26, 2014, pp. 5054-5062, "Determination of the ion exchange capacity of anion-selective membrane". IEC is the "equivalent" or reciprocal of EW, and is the weight of polymer required to give 1 mole of exchangeable protons.

[0027] The disclosure relates to styrene-based multiblock copolymers, and more particularly to a) styrene copolymers having at least four blocks, such as tetrablocks or pentablocks, in which at least one of the blocks is selectively functionalized (quaternized) with quaternary ammonium ("QA"); or b) styrene copolymers having triblocks having an AB / CA structure in which at least three blocks, e.g., C is quaternized with QA and the B / C block is a random block containing both monomers B and C. QA-functionalized polymers are used in anion exchange membranes (AEMs) in AEM electrolytic cells.

[0028] Quaternary ammonium-containing multiblock polymers (SEBS multiblock QA): Styrene-based multiblock copolymers refer to SEBS (styrene-ethylenebutylene-styrene) in this specification, i.e., quaternary ammonium cations, for example, structure NR + It is a hydrogenated block copolymer having a positively charged polyatomic ion of 4 (where R is an alkyl group or aryl group).

[0029] In the embodiment, the SEBS-multiblock QA is one of the following: a) a pentablock structure including blocks A, B, and C; b) a tetrablock structure including blocks A, B, and C; and c) a triblock having a random structure including B / C or C / B. In all of the above structures, C is susceptible to quaternization, and C may be either an intermediate block or a terminal block in any of the above structures.

[0030] Each A block is derived from a para-substituted vinyl aromatic monomer, each B block from a conjugated diene, and each C block from a vinyl aromatic monomer, and is susceptible to quaternization (functionalization). Each A block and B block are polymer blocks resistant to quaternization.

[0031] In a configuration containing multiple A, B, or C blocks, the multiple A, B, or C blocks may be identical or different.

[0032] In embodiments, before hydrogenation and quaternization, the SEBS-multiblock QA copolymer has a general configuration selected from: (ABC)n'(A), (ACB)n'A, (ABC)n'X, ABCBA, CBABA, ACBCA, BCACB, ABCA, ABAC, AB / CA, or AC / BA or mixtures thereof (wherein n' is an integer from 2 to 30 or 2 to 20 in embodiments, and X is a residue of a coupling agent).

[0033] In embodiments, Block A is one or more segments selected from polymerized (i) para-substituted styrene monomers, (ii) ethylene, (iii) alpha-olefins of 3 to 18 carbon atoms, (iv) conjugated diene monomers having a vinyl content of less than 35 mol percent before hydrogenation, (v) acrylic acid esters, (vi) methacrylic acid esters, and (vii) mixtures thereof.

[0034] In embodiments, Block A is a para-substituted styrene monomer selected from para-methylstyrene, para-ethylstyrene, para-n-propylstyrene, para-iso-propylstyrene, para-n-butylstyrene, para-sec-butylstyrene, para-iso-butylstyrene, para-t-butylstyrene, isomers of para-decylstyrene, isomers of para-dodecylstyrene, and mixtures of the above monomers. Examples of para-substituted styrene monomers include para-t-butylstyrene and para-methylstyrene, with para-t-butylstyrene being the most preferred. The monomer may also be a mixture of monomers that depend on a specific source.

[0035] In this embodiment, polymer block A constitutes 30-80% by weight, 35-75% by weight, 40-70% by weight, or 45-65% by weight of the total weight of the multiblock copolymer.

[0036] Block B comprises a hydrogenated polymer or copolymer of conjugated dienes derived from isoprene, butadiene, and mixtures thereof. After hydrogenation, each isoprene unit is converted to an ethylene-propylene (EP) block, and each butadiene unit is converted to an ethylene-butylene (EB) block. In other examples, Block B is an acrylate, silicone polymer, or isobutylene polymer having a number average molecular weight greater than 1000, or greater than 2000, or greater than 4000, or greater than 6000, or greater than 10000. In yet another example, Block B is an isobutylene polymer having a number average molecular weight of at least 1000.

[0037] In the embodiments, the hydrogenation level of block B (conjugated diene block) is greater than 80%, greater than 90%, greater than 95%, greater than 98%, or less than 99.5%. The hydrogenation level refers to the percentage of the original unsaturated bonds that are saturated by hydrogenation. The hydrogenation level of hydrogenated vinyl aromatic polymers can be determined using UV-VIS spectroscopy and / or proton NMR. The hydrogenation level in hydrogenated diene polymers can be determined using proton NMR.

[0038] In the embodiment, polymer block B has a vinyl content of 8 to 85% by weight, or more than 15% by weight, or less than 50% by weight, or 20 to 75% by weight, or 30 to 50% by weight, relative to the total weight of the polymerized conjugated diene of polymer block B. The vinyl content can be measured by proton NMR before and after hydrogenation.

[0039] In one embodiment, polymer block B constitutes 25% by weight or less, or 5 to 25%, or 10 to 25%, or 15 to 25%, or 5 to 20%, or 5 to 15%, or 5 to 20% by weight of the total weight of the multiblock copolymer.

[0040] In embodiments, block C comprises a segment of one or more polymerized vinyl aromatic monomers selected from unsubstituted styrene monomers, orthosubstituted styrene monomers, parasubstituted styrene monomers, metasubstituted styrene monomers, alpha-methylstyrene monomers, 1,1-diphenylethylene monomers, 1,2-diphenylethylene monomers, and mixtures thereof. In addition to the monomers and polymers noted, block C may also comprise hydrogenated copolymers of such monomers having a conjugated diene selected from 1,3-butadiene, isoprene, and mixtures thereof, having a vinyl content between 20 and 80 mol%. These copolymers containing the hydrogenated diene may be any random copolymers, tapered copolymers, block copolymers, or copolymers with a controlled distribution.

[0041] In the embodiment, polymer block C constitutes 40-60% by weight, 45-55% by weight, or 40-50% by weight of the total weight of the multiblock copolymer.

[0042] In embodiments, the SEBS multiblock copolymer is an alkyl halide-substituted SEBS polymer (before quaternization). Examples of halides include chlorine, bromine, and iodine. Block C, which is susceptible to quaternization, can be selectively halogenated (brominated) by (i) a nucleophilic substitution reaction (SN2) or (ii) the Friedel Craft (FC) alkylation electrophilic aromatic substitution reaction, which is well known in the art. In the SN2 type reaction, the para-methyl group from the aromatic monomer is halogenated, resulting in para substitution. In the FC alkylation reaction, the alkyl halide is bonded to the polymerized vinyl aromatic monomer at the para position with a C1-C8 alkyl halide chain before quaternization. In embodiments, block C has a linear side chain containing a CH2 spacer group having C1-C12 carbon atoms.

[0043] In embodiments, the SEBS multiblock copolymer is functionalized with a quaternary ammonium (QA) group. Examples include benzyltrimethylammonium (TMA), dimethylpiperazinium (DMP), benzyldicyclohexylmethylammonium (MCH), benzyldiisopropylmethylammonium (MiPr), trimethylhexylammonium (TMHA), benzyldimethylhexylammonium (DMHA), dimethylamine or trimethylamine (TMA) or triethylamine, or alkyl(C12-16)dimethylbenzylammonium chloride, benzethonium chloride, and benzyl-C12-18-alkyldimethyl(benzyl(coconut oil alkyl)dimethyl) This includes ammonium chloride, cetylpyridinium chloride, decylisononyldimethylammonium chloride, dioctyldimethylammonium chloride, didecyldimethylammonium chloride, laurylamine dipropylenediamine, N-octadecyldimethyl{3-(trimethoxysilyl)propyl}ammonium chloride or tetradecyldimethyl(3-(trimethoxysilyl)propyl)ammonium chloride, pyrrolidinium, imidazole, tetra-pyrrolidinium, benzylphosphonium, piperidinium, bisammonium, quinuclidine, and mixtures thereof.

[0044] In SEBS multiblock copolymers, the degree of quaternization is in the range of 30 mol% to 95 mol%, or 15 to 80 mol%, or 20 to 70 mol%, or 25 to 60 mol%, or greater than 20 mol%, or greater than 50 mol%, relative to the total number of monomer units.

[0045] In embodiments, the SEBS multiblock copolymer (with or without halide groups) is also functionalized by incorporating additional functional groups into the C-block of the base (precursor) polymer. Examples of functional groups include primary amines, acrylates, sulfides, epoxides, and sulfur.

[0046] In the embodiment, the SEBS-multiblock QA copolymer has formula (I).

[0047] [ka] (In the formula, z = 2 to 10, m, n, p, x and y ≥ 1, N + Me3 is a quaternary ammonium (QA) group in formula (I), where R1=Me or t-butyl, R2=H or Me, A is a terminal block containing a polymerized substituted styrene monomer, C is an intermediate block of polymerized styrene monomer, and B is a polymerized conjugated diene block consisting of an x ​​block of polymerized ethylene units and a y block of polymerized butylene or propylene units; QA in formula (I) may be any other QA shown in formula (II) below:

[0048] [ka] In formula (II), R1 and R2 are independently either a linear alkyl chain or a cyclic alkyl chain, and Z is selected from the group consisting of linear alkyl chains, cyclic alkyl chains, and alkylene ether chains.

[0049] Method for forming selectively quaternized SEBS multiblock copolymers: Selectively quaternized SEBS multiblock copolymers can be formed in a series of reaction steps. In the first step, precursor SEBS are prepared by methods known in the art. See, for example, U.S. Patent Nos. 4,894,417, 4,904,731, 4,898,914, 5,057,582, 5,705,571, 7,592,390, and 8,445,087. In embodiments, the precursor is prepared by sequential (or continuous) polymerization of monomers in solution (solvent) in the presence of an initiator, with the monomers and initiator added stepwise, followed by hydrogenation. In embodiments, the precursor is prepared by coupling the resulting block copolymer with a coupling agent prior to the hydrogenation step.

[0050] In the post-hydrogenation embodiment, the hydrogenated multiblock, i.e., the SEBS multiblock copolymer, is converted to an alkyl halide-substituted polymer by reacting it with an alkyl halide in a nucleophilic substitution (SN2) reaction known in the Friedel Craft (FC) and / or art. Examples of halides include fluorine, chlorine, bromine, or iodine, and the substituted alkyl chain is C1-C 12 The polymer may be linear, branched, or cyclic, having atoms. Alternatively, any brominating agent, such as 1,1-dimethyl-6-bromo-1-hexanol, can be used to obtain alkyl-halogenated SEBS. In embodiments, the polymer block susceptible to quaternization has C1-C1 atoms at the para position of the polymerized vinyl aromatic monomer. 12 It is selectively halogenated by bonding an alkyl halide.

[0051] In the embodiment, the alkyl-substituted SEBS has a degree of halogenation of up to 100, or 1 to 99, or 5 to 90, or 10 to 80, or 20 to 70, or 30 to 90, or 40 to 80%, or more than 40%, or more than 50%, relative to the polymer block susceptible to quaternization.

[0052] In embodiments, quaternization of alkyl halide-substituted SEBS is carried out by reacting the alkyl halide-substituted SEBS with a compound containing at least one quaternizing agent (QA), for example, (i) a di- or multi-amino group and / or (ii) a mixture of trimethylamine and dimethylamine groups in a weight ratio of 50:50, 40:60, 30:70, 20:80, 10:90, 90:10, 80:20, 70:30, or 60:40.

[0053] Quaternization of alkyl halide-substituted SEBS can be carried out by two methods. In one embodiment, alkyl halide-substituted SEBS is dissolved in an organic solvent having a concentration of 5-50%, 10-40%, 5-30%, 10-30%, or more than 5%, or more than 15%, to obtain an alkyl halide-substituted SEBS polymer solution. This solution is then mixed with a pre-dissolved quaternizing agent (QA) solution to obtain a quaternized SEBS multiblock copolymer. The resulting mixture is then cast onto a substrate to form a film or membrane.

[0054] In another embodiment, an alkyl halide-substituted SEBS polymer solution is first cast onto a substrate to form a film. The film is then subjected to quaternization by a method including, but not limited to, spray coating, dip coating, or treatment of the film with the QA solution, followed by drying to obtain the SEBS multiblock-QA copolymer. Multiple coatings can be applied sequentially. In embodiments, the film is formed in ordinary planar shapes, bags, hollow fibers, or hollow tubes.

[0055] A membrane or film containing SEBS multiblock-QA copolymer: The copolymer formed is used to manufacture a membrane or film. In embodiments, in addition to the SEBS multiblock-QA copolymer, optional components including crosslinking agents, additives, and polymers other than alkyl-halogenated SEBS may also be used / added to form the membrane / film.

[0056] Other examples of polymers include polytetrafluoroethylene (PTFE), polyolefins, polyimides, polyamides, polyesters, polystyrene, polysulfones, polyketones, poly(2,6-dimethyl-1,4-phenylene) ether, poly(p-phenylene oxide) (PPO), polyphenylene ether, polyisoprene, polybutadiene, polyvinylidene fluoride, polycarbonate, polyetherimide, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylate, polytert-butylstyrene, and mixtures thereof.

[0057] The molecular weight of the optional polymer component can be individually adjusted to obtain miscibility between the selectively quaternized styrene multiblock copolymer and the second (optional) polymer. In embodiments, the optional polymer component is selected from PPO having molecular weights in the range of 5–15 kg / mol, 7–12 kg / mol, 7–9 kg / mol, or 10–12 kg / mol. In embodiments, the MW ratio of the second (optional) polymer to the MW of block A is in the range of 5:1–1:2, 4:1–3:1, or 2:1–1:1.

[0058] In the embodiments, the polymer blended with the selectively quaternized styrene multiblock copolymer is present in an amount of 0.1 to 50% by weight, or 1 to 35% by weight, or 5 to 30% by weight, or more than 15% by weight, or less than 25% by weight, or 15 to 25% by weight, relative to the weight of the selectively quaternized styrene multiblock copolymer.

[0059] Optional components can be mixed with / added directly to the alkyl-substituted SEBS, or added to an organic solvent before or after quaternization.

[0060] In embodiments, the anionic exchange film may be formed by any of the following methods: casting, electrospinning, extrusion, compression, dip coating, pour coating, roll coating, bar coating, spray coating, curtain coating, rotary gravure, brushing, wire-wound rod coating, pan-fed reverse roll coating, nip-fed coating, spraying, knife coating, spin coating, dipping, slot die coating, ultrasonic spray coating, etc. The film can be dried with or without vacuum at room temperature to 80°C, or 30 to 70°C, or 35 to 65°C for a period of 1 hour to 7 days, or 5 hours to 5 days, or 10 hours to 2 days. In embodiments, the film may be a self-supporting film or supported by a substrate such as glass, plastic, ceramic, or porcelain. In embodiments, the resulting film may have a specific morphology, such as lamellae, or hexagonal-filled cylinders, spheres, or cylinders.

[0061] Examples of solvents include aliphatic hydrocarbons such as hexane and cyclohexane, halogenated hydrocarbons such as methylene chloride or ethylene chloride, water, isopropyl alcohol, acetone, N,N-dimethylacetamide, 1-methyl-2-pyrrolidinone, 1,3-dioxolane, 2-methoxyethanol, dimethylformamide, or benzyl alcohol, or mixtures thereof.

[0062] Properties of SEBS multiblock-QA copolymer membranes (films): Due to the selective quaternization of the internal segments (block "C") of the block copolymer, membranes or films (such as AEMs) produced from the composition exhibit balanced physical properties, including elasticity and low swelling.

[0063] In an embodiment, the film has a thickness of 0.1 to 500 μm, or 1 to 200 μm, or 10 to 100 μm, or 1 to 50 μm, or 20 to 150 μm, or 50 to 300 μm.

[0064] In an embodiment, the film has a water uptake capacity of 5 to 100, or 10 to 90, or 20 to 80, or 30 to 60, or 10 to 50, 30 to 80% by weight based on the total weight of the film.

[0065] In an embodiment, the dry film has a tensile strength at break according to ASTM D412 of at least 200 psi, or more than 1,000 psi, or more than 1,500 psi, or at least 4,000 psi.

[0066] In an embodiment, the film has a wet tensile strength according to ASTM D412 of more than 100 psi, or more than 500 psi, or more than 1,000 psi, or more than 1,500 psi.

[0067] In an embodiment, the film has an elongation at break of at least 40%, or more than 100%, or more than 200%, or more than 250%.

[0068] In an embodiment, the film has an ion exchange capacity (IEC) of 1.0 to 3.5, or 1.2 to 3.0, or 1.5 to 3 meq / g, or more than 1 meq / g, or less than 3 meq / g, or more than 0.5 meq / g.

[0069] In an embodiment, the film has a water vapor transmission value of more than 1,000 g per day at a relative humidity (RH) of 10% or more and 50°C or less using the gravimetric inverted cup method based on ASTM E 96 / E 96M-05. 2 1 day.

[0070] In the embodiment, the film has a degree of swelling of less than 200% by weight, or less than 100%, or less than 75%, or less than 50%, or less than 30%. The degree of swelling refers to the change in shape with respect to dimensional stability or the dimensions of the film, in this case a percentage change, and refers to the change in shape rather than the water content of the polymer.

[0071] Applications: Beyond AEM, SEBS multiblock-QA copolymers can be used in a variety of applications and end-uses. When selectively quaternized internal blocks are present, the copolymers can be used in applications where a combination of good wet strength, good water and proton transport properties, good methanol resistance, easy film or membrane formation, barrier properties, controllable flexibility and elasticity, tunable hardness, and thermal / oxidative stability is important.

[0072] In embodiments, SEBS multiblock-QA copolymers are used as ionomers or membranes in electrochemical applications such as water electrolyzers (electrolytes), fuel cells (separator phases), proton exchange membranes for fuel cells, dispersions of metal-impregnated carbon particles in quaternized polymer cement used in electrode assemblies, acid batteries (electrolyte separators), supercapacitors (electrolytes), separation cells for metal recovery processes (electrolyte barriers), and sensors (particularly for humidity sensing). In embodiments, AEMs can be used in applications other than electrolyzers or fuel cells that may include humidity control devices, energy storage solutions, such as vanadium or iron redox fluid battery membranes, or lithium-ion battery solid polymer electrolytes. [Examples]

[0073] The following examples are intended to be non-limiting.

[0074] The degree of halogenation of alkyl-substituted SEBS can be determined by proton nuclear magnetic resonance spectroscopy (1H NMR; Varian 500 MHz spectrometer, 23°C) using CD2Cl2 as the solvent.

[0075] Mechanical properties, including toughness, Young's modulus, tensile strength, and elongation at break, can be measured according to ASTM D412.

[0076] The components used in the examples include: SBC-1: 22% by weight polymer block B content, molecular weight (M) 90 kg / mol p A pentablock copolymer comprising the structure tBS-EP-S-EP-tBS, having a coupling efficiency of 68%.

[0077] SBC-2: 12% by weight polymer block B content, molecular weight (M) 84 kg / mol p A pentablock copolymer comprising the structure tBS-EP-S-EP-tBS, having a coupling efficiency of 75%.

[0078] Since SEBS multiblock-QA copolymers exhibit nanoscale phase separation morphology, they also exhibit nanoscale ion transport channels, enabling highly efficient ion conduction.

[0079] Example 1 In this example, SEBS multiblock-QA is prepared from a pentablock copolymer (SEBS-tBS-EP-S-EP-tBS) without using a transition metal catalyst such as iridium or palladium. The reaction mechanism involves the alcohol decomposition of a caprolactam molecule to obtain 6-(dimethylamino)hexanoic acid, followed by esterification and subsequent methylation to a tertiary alcohol, which is then used to prepare the target SEBS multiblock-QA copolymer.

[0080] Preparation of SEBS Pentablock QA polymer begins with SEBS Pentablock copolymer compound (5) (0.50 g, 2.07 mmol of styrene units), to which a tertiary alcohol (1.29 g, 6.22 mmol) is added, for example, in a 20 mL vial. The vial is then emptied and purged with nitrogen.

[0081] [ka] (In the formula, R1 = t-butyl, R2 = H, and A, B, C, m, n, p, x, and y are as previously defined.)

[0082] Add anhydrous dichloromethane (5 mL) and stir the polymer until dissolved. After cooling, add trifluoromethanesulfonic acid (0.55 mL, 6.22 mmol). Stir the reaction in an ice bath for 1 hour, then pour the reaction mixture into methanol to precipitate the polymer.

[0083] The polymer was then filtered, redissolved in chloroform, precipitated in methanol, isolated, and vacuum-dried at room temperature for 6 hours to yield the SEBS-pentablock alkBr polymer compound (6). It was found that 59.3% of the styrene units in compound (6) reacted (17.7 mol% alkyl bromide and 12.2 mol% unfunctionalized styrene units). The molecular weights measured by GPC using THF at 30°C were SEBS-Mn = 106,315 g / mol (PDI = 1.04) and SEBS-alkBr-Mn = 60,228 g / mol (PDI = 2.07). The viscosities measured in toluene at 30°C were SEBS = 0.82 dL / g and SEBS-alkBr = 0.68 dL / g.

[0084] [ka] (In the formula, R1, R2, A, B, C, m, n, p, x, and y are as previously defined, and z = 8.) In this structure, the C block is functionalized to have an average functionalization degree of 30 mol% to 95 mol%. One of the C blocks may have a lower functionalization degree than the other C blocks, or may not be functionalized at all.

[0085] Next, 0.15 g of compound (6) was dissolved in toluene (3 mL), filtered, cast onto a Teflon® plate, and dried at 80°C under a mild flow of air. Then, a thin SEBS Pentablock alkBr film (approximately 30-40 μm thick) was removed from the plate by immersion in water, immersed in an aqueous trimethylamine solution (45 wt%) in water, and heated at 50°C for 48 hours. The film was then ion-exchanged to the hydroxide form by immersion in 1 M NaOH at room temperature for 48 hours to give the SEBS Pentablock QA polymer compound (7).

[0086] [ka] (In the formula, R1, R2, A, B, C, m, n, p, x, y, and z are as defined above, N + Me3 is a quaternary ammonium group.

[0087] Example 2 In this example, the SEBS multiblock-QA copolymer is prepared using caprolactone molecules as an initiator for alkylation in a Grignard-type reaction to prepare the target SEBS multiblock-QA copolymer, without using a transition metal catalyst.

[0088] The preparation of the SEBS multiblock-QA copolymer begins with SEBS pentablock copolymer compound (5) (0.30 g, 4.64 mmol of styrene units), to which 6-bromohexanoyl chloride (1.49 g, 6.96 mmol) is added in a 100 mL round-bottom flask under nitrogen. Anhydrous dichloromethane (15 mL) is added and the mixture is stirred until dissolved. The flask is cooled for the addition of AlCl3 powder (0.93 g, 6.96 mmol). The reaction is stirred further in an ice bath for 1 hour, after which the reaction mixture is poured into a methanol solution to precipitate the polymer. The precipitated polymer is then filtered, redissolved in chloroform, and precipitated again in methanol to give SEBS pentablock acylBr ketone polymer compound (8) (0.38 g). Compound (8) is obtained after isolation and vacuum drying at room temperature for 6 hours.

[0089] In the next step, the SEBS pentablock acylBr ketone polymer compound (8) is reduced to give the SEBS-alk-Br compound (9). The reduced compound (9) is obtained by first dissolving compound (8) (0.38 g, 0.91 mmol of ketone) in 20 ml of anhydrous dichloromethane in a flask and stirring until the polymer is dissolved. Triethylsilane (Et3.SiH; 0.58 mL, 3.64 mmol) and trifluoroacetic acid (0.56 mL, 7.28 mmol) are added to the stirred mixture and then heated at 45°C for 14 hours. After cooling, the reaction mixture is poured into methanol. The precipitated polymer is filtered, redissolved in chloroform, and precipitated again in methanol to give the SEBS pentablock alkBr polymer compound (9) from which the ketone has been reduced.

[0090] [ka] (In the formula, R1, R2, A, B, C, m, n, p, x, y, and z are as previously defined.)

[0091] Next, compound (9) was aminated to give quaternized compound (10). 0.15 g of compound (10) was dissolved in 3 mL of toluene. The solution was then cast onto a Teflon® plate and dried at 80°C under air to form a dry film with a thickness of 30-40 μm. The film was then immersed in an aqueous trimethylamine solution (45% by weight in water) and heated at 50°C for 48 hours. The film was then rinsed with water to obtain SEBS-pentablock alkTMA polymer, which is the quaternized SEBS-pentablock QA polymer compound (10).

[0092] [ka] The values ​​of R1, R2, A, B, C, m, n, p, x, y, and z are as previously defined, and N + Me3 is a quaternary ammonium compound (QA).

[0093] Table 1 illustrates structures that can be formed from the above steps, which have an expected value as IEC(meq. / g).

[0094] [Table 1]

[0095] TMA-trimethylamine; MPI-methylpiperidine; TMHA-N,N,N',N'-tetramethyl-1,6-hexanediamine; C is a styrene unit and A is para-alkyl-substituted styrene.

[0096] The terms “comprising” and “including” are used herein to describe various aspects, but the terms “basically consisting of” and “consisting of” may be used instead of “comprising” and “including” to provide a more limited aspect of the disclosure.

Claims

1. (i) at least one block A derived from either a para-substituted vinyl aromatic monomer or (ii) an unsubstituted vinyl aromatic monomer, Block B comprising at least one polymerized hydrogenated 1,4-isoprene units or 1,2 and 1,4-butadiene units, Block C, derived from vinyl aromatic monomers that are susceptible to quaternization, as an intermediate or terminal block, A selectively quaternized hydrogenated styrene block copolymer comprising, It has a general configuration of a pentablock, tetrablock, or triblock having a random structure including B / C or C / B, It has an ion exchange capacity (IEC) of 0.5 to 4.0 meq / g, Block C is quaternized, and has a quaternary ammonium cation and a degree of quaternization of 30 mol% to 95 mol%, Selectively quaternized hydrogenated styrene block copolymer.

2. The selectively quaternized hydrogenated styrene block copolymer according to claim 1, which is a pentablock having a structure selected from A-B-C-B-A, C-B-A-B-A, A-C-B-C-A, B-C-A-C-B, and mixtures thereof.

3. structure: 【Chemistry 1】 (In the formula, z = 2 to 10, m, n, p, x and y ≥ 1, N ＋ In formula (I), Me3 is a quaternary ammonium (QA) group, R1 = Me or t-butyl, R2 = H or Me, A is a terminal block containing a polymerized substituted styrene monomer, C is an intermediate intermediate block of polymerized styrene monomer, and B is a polymerized conjugated diene block composed of an x ​​block of polymerized ethylene units and a y block of polymerized butylene or propylene units. A selectively quaternized hydrogenated styrene block copolymer according to claim 1 or 2, having a pentablock.

4. The selectively quaternized hydrogenated styrene block copolymer according to claim 1, which is a tetrablock having a structure selected from A-B-C-A, A-B-A-C, and mixtures thereof.

5. The selectively quaternized hydrogenated styrene block copolymer according to claim 1, which is a triblock having a structure selected from A-B / C-A, A-C / B-A, and mixtures thereof.

6. A selectively quaternized styrene-hydrogenated block copolymer according to any one of claims 1, 2, 4, and 5, having an ion exchange capacity of 0.7 to 3.5 meq / g.

7. The selectively quaternized hydrogenated styrene block copolymer according to any one of claims 1, 2, 4, and 5, wherein block C comprises a linear alkyl side chain readily subject to electrophilic aromatic substitution, the linear alkyl side chain having a CH2 spacer group containing C1 to C12 carbon atoms, and the CH2 spacer group is derived from a monomer selected from the group consisting of caprolactam, caprolactone, and mixtures thereof.

8. The selectively quaternized hydrogenated styrene block copolymer according to any one of claims 1, 2, 4, and 5, wherein each A and B block of the styrene block copolymer is a polymer block resistant to electrophilic aromatic substitution reactions.

9. The selectively quaternized hydrogenated styrene block copolymer according to any one of claims 1, 2, 4, and 5, wherein block A is at least one compound selected from the group consisting of polymerized unsubstituted styrene, para-substituted styrene, ortho-substituted styrene, meta-substituted styrene, alpha-methylstyrene, 1,1-diphenylethylene, 1,2-diphenylethylene, and mixtures thereof.

10. The selectively quaternized hydrogenated styrene block copolymer has a polystyrene content of 70 to 95% by weight. Block B before hydrogenation has a vinyl content of 5 to 80% by weight relative to the total weight of polymerized conjugated diene monomers in Block B. A selectively quaternized hydrogenated styrene block copolymer according to any one of claims 1, 2, 4, and 5.

11. The selectively quaternized hydrogenated styrene block copolymer according to any one of claims 1, 2, 4, and 5, wherein block C is quaternized with a quaternizing agent having amine functional groups obtained from trimethylamine, dimethylamine, monoamine, diamine, multiamine groups, and mixtures thereof.

12. An anion exchange membrane comprising a selectively quaternized hydrogenated styrene block copolymer as described in claim 1, the anion exchange membrane having a thickness of 0.1 to 500 μm.

13. Below 50°C and 10% relative humidity (RH), 1m measurement using ASTM E 96 / E 96M-05. ２ Water vapor transport values ​​exceeding 1,000g per day, Wet tensile strength exceeding 100 psi according to ASTM D412, Swelling degree of less than 200% by weight, less than 100%, less than 75%, less than 50%, or less than 30% An anion exchange membrane according to claim 12, having at least one of the above.

14. The anion exchange membrane according to claim 12, further comprising at least one other polymer selected from the group consisting of polytetrafluoroethylene (PTFE), polyolefin, polyimide, polyamide, polyester, polystyrene, polysulfone, polyketone, poly(p-phenylene oxide) (PPO), polyphenylene ether, polyisoprene, polybutadiene, polyvinylidene fluoride, polycarbonate, polyetherimide, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylate, polytert-butylstyrene, and mixtures thereof.

15. An electrode assembly comprising an anion exchange membrane as described in claim 12.

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