Polymer electrolyte membrane based on monomers for polymerization and polymers formed by polymerization, having a high density of functional groups via spacer structures

Abstract

The present invention provides a monomer having a functional group via a spacer structure and capable of constituting a polymer, and a polymer.SOLUTION: The monomer and the polymer have a functional group through a spacer structure and can constitute a polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer electrolyte membrane based on a polymer formed by polymerization of a polymerization monomer having a high density of functional groups via a spacer structure. [Background technology]

[0002] Fuel cells, which are expected to be a clean power generation system, generate electrical energy by electrochemically reacting hydrogen and oxygen using the reverse reaction of water electrolysis. In particular, solid polymer fuel cells, which use a polymer electrolyte membrane, are used in fuel cell vehicles and other applications.

[0003] The basic component of a polymer electrolyte fuel cell is a membrane electrode assembly (MEA), which is made by sandwiching a proton-conducting membrane called a polymer electrolyte membrane between gas diffusion electrodes consisting of a gas diffusion layer and a catalyst layer containing ionomer.If protons do not move properly in the electrolyte membrane, the fuel cell reaction will not occur, and excellent power generation characteristics (high output) will not be obtained.

[0004] For this reason, it is important to use a polymer electrolyte membrane that exhibits high proton conductivity (for example, 0.1 S / cm or higher), and the polymer electrolyte membrane is considered to be one of the most important parts in a fuel cell.

[0005] Currently, the electrolyte membranes used in commercially available fuel cell vehicles and other devices are made of perfluorosulfonic acid polymers, such as Nafion® developed by DuPont. By wetting the membrane at temperatures between 70°C and 90°C, protons move through the water molecules, achieving high proton transport capacity (proton conductivity > 0.1 S / cm).

[0006] Furthermore, by humidifying a chemically cross-linked random copolymer of polystyrene and polystyrene sulfonic acid, which is obtained by sulfonating a chemically cross-linked polystyrene, a proton conductivity of approximately 0.1 S / cm can be achieved if the proportion of polystyrene sulfonic acid is high.

[0007] While development of polymer electrolyte membranes that exhibit high proton conductivity of 0.1 S / cm or more under such humidified conditions continues, progress is also being made in the development of proton-conducting polymer electrolyte membranes that exhibit high proton conductivity of around 0.1 S / cm even when the membrane is not sufficiently humidified and not sufficiently wetted.

[0008] Patent Document 1 discloses a polymer electrolyte membrane. The polymer electrolyte membrane of Patent Document 1 includes a polymer having an acidic functional group, and the polymer is (i) a block copolymer having ab-type units in which at least an a block and a b block are covalently linked, (ii) a chemically crosslinkable polymer having an acidic functional group in a side chain, and / or (iii) a polymer composed of a monomer unit having a phosphonic acid group via a spacer structure, and the polymer does not contain a highly hydrolyzable functional group between the main chain skeleton and the phosphonic acid group.

[0009] The (i) a block is composed of a hydrophobic polymer or a water-repellent polymer, and the (i) b block is composed of a polymer having an acidic functional group in the side chain or the (iii) polymer, or the side chain of the (i) b block is composed of a graft chain containing an acidic functional group in the monomer unit.

[0010] This polymer electrolyte membrane has phosphonic acid and / or phosphonate ester units via a spacer structure, and the membrane does not contain a small molecular weight electrolyte. -3 The polymer electrolyte membrane exhibits a good conductivity of 1000 S / cm or more. This polymer electrolyte membrane can be suitably used as a proton conducting membrane in a fuel cell.

[0011] Patent Document 2 discloses the polymerization and copolymerization of a monomer containing two acid groups, an aryl group, and two carbon atoms between the acid group and the aryl group.

[0012] Non-Patent Document 1 discloses the synthesis and reactivity of alkyl-1,1,1-trisphosphonate esters, which have three phosphonate ester groups on one carbon atom, and a 2-propenyl group (-CH-CH=CH) or a 5-hexenyl group (-CH-CH-CH-CH-CH=CH). [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication WO2023 / 120731A1 [Patent Document 2] International Publication WO2010 / 135167A1 [Non-patent literature]

[0014] [Non-Patent Document 1] J. Org. Chem. 2011, 76, 21, 8807-8813 Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention provides a novel monomer and polymer that have a functional group via a spacer structure and can constitute a polymer. [Means for solving the problem]

[0016] The present invention that achieves the above object is as follows.

[0017] Section 1. It is a monomer that has a functional group via a spacer structure and can constitute a polymer, The functional group is phosphonic acid groups and / or phosphonate ester units; a basic functional group; or a cationic functional group based on a basic functional group; The spacer structure is Does not contain highly hydrolyzable functional groups, Per one spacer structure, two or more of the phosphonic acid groups and / or phosphonate ester units; one or more of the basic functional groups; or one or more cationic functional groups based on the basic functional group; monomer.

[0018] Section 2. Item 2. The monomer according to item 1, wherein the functional group is present at an end of the spacer structure.

[0019] Section 3. When the functional group is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms; When the functional group is a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 3 to 20 carbon atoms; or Item 1. The monomer according to item 1, wherein when the functional group is a cationic functional group based on a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

[0020] Section 4. Item 1, comprising a monomer unit consisting of the monomer described in Item 1; The functional group of the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, and the monomer unit has two or more of the phosphonic acid group and / or the phosphonate ester unit per spacer structure. The functional group of the monomer unit is a basic functional group, and the monomer unit has one or more basic functional groups per spacer structure, or the monomer unit is not a fluorene-based monomer unit, the functional group is a cationic functional group based on a basic functional group, and each spacer structure has one or more cationic functional groups based on the basic functional group; polymer.

[0021] Section 5. Item 5. The polymer according to item 4, wherein the polymer is formed by chain polymerization or step-growth polymerization.

[0022] Section 6. It is a block polymer in which at least an a block and a b block are connected by a covalent bond, The a block is The polymer according to item 4, or a polymer comprising a monomer unit having a functional group via a spacer structure and composed of a monomer capable of constituting a polymer, wherein the functional group in the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure does not contain a highly hydrolyzable functional group, and the polymer comprises a monomer unit having one phosphonic acid group and / or one phosphonate ester unit per spacer structure; The b block is It is made of hydrophobic or water-repellent polymers, The polymer has a glass transition temperature (Tg) of 50°C or less. Block polymer.

[0023] Section 7. Item 7. The block polymer according to item 6, wherein the b block is a polymer in which an alkyl chain is directly bonded to the main chain skeleton.

[0024] Section 8. a block polymer in which at least the a block, the b block, and the c block are linked by a covalent bond; The c block is It is made of hydrophobic or water-repellent polymers, A polymer with a glass transition temperature (Tg) of 120°C or higher. Item 8. The block polymer according to item 6 or 7.

[0025] Section 9. The polymer according to item 4 or 5, or Item 6, 7, or 8, comprising the block polymer Polymer electrolyte membrane.

[0026] Section 10. Item 10. The polymer electrolyte membrane according to item 9, which is water resistant.

[0027] Section 11. The polymer according to item 4 or 5, or Item 6, 7, or 8, comprising the block polymer Ionomer, or membrane electrode assembly (MEA).

[0028] Section 12. Item 12. The ionomer or membrane electrode assembly (MEA) according to item 11, which has water resistance.

[0029] Section 13. Item 10. The polymer electrolyte membrane according to Item 9, or Item 12. The ionomer according to Item 11 is contained therein. A sheet-like material reinforced membrane that is reinforced with a sheet-like material having voids.

[0030] Section 14. Item 14. The sheet-like material-reinforced membrane according to Item 13, wherein the sheet-like material having voids is a nonwoven fabric and / or a porous sheet.

[0031] Section 15. The polymer according to item 4 or 5, or Item 6, 7, or 8, comprising the block polymer a fuel cell including a fuel cell electrolyte membrane; A water electrolysis device including an electrolyte membrane for water electrolysis, or An ion exchange device comprising an ion exchange membrane.

[0032] Section 16. The polymer according to item 4 or 5, or Item 6, 7, or 8, comprising the block polymer Separation membrane, anion exchange membrane, or cation exchange membrane. [Effects of the Invention]

[0033] The present invention can provide a novel monomer and polymer that have a functional group via a spacer structure and can constitute a polymer. [Brief explanation of the drawings]

[0034] [Figure 1] (Example 1) 1H-NMR spectrum, chain line: p-bromostyrene, dotted line: p-(8-bromooctyl)styrene, dashed line: 8-(p-styryl)-1-octanephosphonic acid diethyl ester, solid line: 8-(p-styryl)-1,1-octanediphosphonic acid tetraethyl ester. [Figure 2] (Example 1) C-NMR spectrum, chain line: p-bromostyrene, dotted line: p-(8-bromooctyl)styrene, dashed line: 8-(p-styryl)-1-octanephosphonic acid diethyl ester, solid line: 8-(p-styryl)-1,1-octanediphosphonic acid tetraethyl ester. [Figure 3] (Example 1) 31P-NMR spectrum, dashed line: diethyl 8-(p-styryl)-1-octanephosphonate, solid line: tetraethyl 8-(p-styryl)-1,1-octanediphosphonate. [Figure 4] (Example 1) 1H-NMR spectrum, dashed line: poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate), solid line: sodPA. [Figure 5] (Example 1) GPC chromatogram of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate). [Figure 6]Proton conductivity at 100°C, ●: Example 1 (sodPA membrane), ▲: Comparative Example 1 (soPA membrane), ■: Comparative Example 2 (sPA membrane). [Figure 7] Proton conductivity at 120°C, ●: Example 1 (sodPA membrane), ▲: Comparative Example 1 (soPA membrane), ■: Comparative Example 2 (sPA membrane). [Figure 8] (Example 2) 1H-NMR spectrum of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. [Figure 9] (Example 2) 13C-NMR spectrum of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. [Figure 10] (Example 2) 31P-NMR spectrum of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. [Figure 11] (Example 2) 1H-NMR spectrum, dashed line: poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate), solid line: sndPA. [Figure 12] (Example 2) GPC chromatogram of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate). [Figure 13] (Example 3) 1H-NMR spectrum, dotted line: p-(4-bromobutyl)styrene, dashed line: 4-(p-styryl)-1-butanephosphonic acid diethyl ester, solid line: 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl ester. [Figure 14] (Example 3) 13C-NMR spectrum, dotted line: p-(4-bromobutyl)styrene, dashed line: 4-(p-styryl)-1-butanephosphonic acid diethyl ester, solid line: 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl ester. [Figure 15] (Example 3) 31P-NMR spectrum, dashed line: 4-(p-styryl)-1-butanephosphonic acid diethyl ester, solid line: 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl ester. [Figure 16](Example 3) 1H-NMR spectrum, dashed line: poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate), solid line: sbdPA. [Figure 17] (Example 3) GPC chromatogram of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate). [Figure 18] (Example 4) 1H-NMR spectrum of hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate. [Figure 19] (Example 4) 1H-NMR spectrum, dashed line: poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate), solid line: sotPA. [Figure 20] (Example 4) GPC chromatogram of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate). [Figure 21] (Example 5) 1H-NMR spectrum of p-(9-(p-styryl)-nonyl)pyridine. [Figure 22] (Example 5) 13C-NMR spectrum of p-(9-(p-styryl)-nonyl)pyridine. [Figure 23] (Example 5) 1H-NMR spectrum of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)). [Figure 24] (Example 5) GPC chromatogram of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)). [Figure 25] (Example 6) 1H-NMR spectrum of 1-ethyl-p-(9-(p-styryl)-nonyl)pyridinium bromide. [Figure 26] (Example 7) 1H-NMR spectrum, dotted line: so, dashed line: so-soPdE, solid line: so-soPA. [Figure 27] (Example 7) GPC chromatogram, dashed line: so, solid line: so-soPdE. [Figure 28](Example 9) Stress-strain curves of sbPA / PPS membranes. [Figure 29] (Examples 15-17, Comparative Example 4) Stress-strain curves [Figure 30] (Examples 18 and 19) H-NMR spectra, solid line (Example 18): 7,7′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate), dashed line (Example 19): 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene. [Figure 31] (Example 18) 1H-NMR spectrum, dashed line: poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)), solid line: fb(hpdPA). [Figure 32] (Example 18) GPC chromatogram of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)). [Figure 33] Proton conductivity at 100°C, ●: Example 18 (fb(hpdPA) membrane) [Figure 34] Proton conductivity at 120°C, ●: Example 18 (fb(hpdPA) membrane) [Figure 35] (Comparative sample) 1H-NMR spectrum of 6,6'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate). [Figure 36] (Example 19) 1H-NMR spectrum of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate). DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention will be described in detail below.

[0036] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0037] In this specification, when a numerical range is expressed as "X to Y", it means X or more and Y or less.

[0038] As used herein, the prefix "poly" refers to a polymer containing two or more monomer units.

[0039] [1] Monomer The monomers of the present invention are monomers that contain functional groups via spacer structures and can be used to construct polymers, preferably by chain polymerization, in which monomer molecules are added one at a time to active sites on a growing polymer chain, or by step polymerization, in which multifunctional (usually bifunctional) monomers react to form first multifunctional dimers, then multifunctional trimers, longer multifunctional oligomers, and finally multifunctional long-chain polymers.

[0040] (monomer) The monomer is preferably a chain polymerization monomer capable of forming a polymer by chain polymerization such as addition polymerization, that is, radical polymerization, anionic polymerization, or cationic polymerization.

[0041] The monomer is preferably a monomer for step-growth polymerization that can form a polymer by step-growth polymerization such as condensation polymerization and addition condensation.

[0042] (Monomer for chain polymerization) The monomer is preferably a chain polymerization monomer that can be used to form, through chain polymerization, a vinyl polymer such as a styrene-based polymer having a monomer unit with a styrene skeleton, or an ethylene-based polymer having a monomer unit with an ethylene skeleton.

[0043] Monomers with a styrene skeleton or ethylene skeleton may have any number of substituents (R) at any position. In the case of monomers with an ethylene skeleton, R is not a phenyl group.

[0044] [ka]

[0045] (monomer for step-growth polymerization) The monomer is preferably a monomer for step-growth polymerization that can be used to form, by step-growth polymerization, a fluorene-based polymer having a monomer having a fluorene skeleton as a monomer unit, a phenylene-based polymer having a monomer having a phenylene skeleton as a monomer unit, a furan-based polymer having a monomer having a furan skeleton as a monomer unit, a thiophene-based polymer having a monomer having a thiophene skeleton as a monomer unit, or the like.

[0046] Monomers with a fluorene skeleton, a phenylene skeleton, a furan skeleton, or a thiophene skeleton may have multiple substituents (R) at any position. X1 and X2 in the monomer's chemical structure are usually halogens (Cl, Br, I, etc.).

[0047] [ka]

[0048] (functional group) The functional groups are phosphonic acid groups and / or phosphonate ester units; basic functional groups; or cationic functional groups based on basic functional groups.

[0049] (Phosphonic acid group and / or phosphonate ester unit) The phosphonic acid group and / or phosphonate ester unit is preferably a functional group composed of at least one member selected from the group consisting of a phosphonic acid group and a phosphonate ester unit.

[0050] The phosphonate ester unit refers to a phosphonate diester unit or a phosphonate monoester unit in which a protecting group is attached to the phosphonic acid group, and particularly refers to a phosphonate diester unit.

[0051] The phosphonic acid group can be easily prepared by deprotecting the phosphonate ester unit.

[0052] The phosphonic acid group and / or phosphonate ester unit is preferably a functional group composed of at least one selected from the group consisting of a phosphonic acid group, a diethyl phosphonate unit, and a diisopropyl phosphonate unit, but is not limited thereto.

[0053] (basic functional group) The basic functional group is preferably at least one basic functional group selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, a pyrimidyl group, a pyrazinyl group, and a triazolyl group, but is not limited thereto as long as it exhibits basicity (the property of accepting a proton or donating an electron pair).

[0054] (cationic functional group based on basic functional group) A cationic functional group based on a basic functional group is one in which the basic functional group is quaternized with an organic halogen compound or the like to generate a cation.

[0055] The monomer preferably does not contain a highly hydrolyzable functional group at a position that will become the main chain of the polymer after polymerization.

[0056] The monomer preferably does not contain a highly hydrolyzable functional group or bond at a position that will become a connecting portion of the main chain of the polymer after polymerization.

[0057] (Spacer structure) The spacer structure does not contain a highly hydrolyzable functional group.

[0058] The monomer does not contain a highly hydrolyzable functional group between the portion that will become the main chain skeleton of the polymer after polymerization and the phosphonic acid group and / or phosphonate ester unit, basic functional group, or cationic functional group based on a basic functional group that is part of the side chain of the polymer after polymerization (spacer structure).

[0059] The monomer preferably does not contain a highly hydrolyzable functional group between the part that will become the main chain skeleton of the polymer after polymerization and the spacer structure (the part where the spacer structure is connected to the main chain skeleton, the root part of the side chain), and / or between the phosphonic acid group and / or phosphonate ester unit that is part of the side chain of the polymer after polymerization; the basic functional group; or the cationic functional group based on the basic functional group and the spacer structure.

[0060] The part that becomes the main chain skeleton of the polymer after polymerization is a chain compound (generally a polymer, which can contain not only straight-chain units but also cyclic units), and represents the part that becomes the main chain (corresponding to the center of the chain, the trunk). It is also called the main chain skeleton. In the case of a vinyl monomer, it is generally the vinyl group CH2=CH-. The functional groups branching off from the part that becomes the main chain skeleton, and the units containing functional groups, represent side chains.

[0061] Examples of highly hydrolyzable functional groups include amide bonds, imide bonds, urethane bonds, ester bonds, ether bonds, thioether bonds, thioester bonds, etc. However, the above bonds incorporated into heteroaromatic rings are not considered to be highly hydrolyzable functional groups.

[0062] Each spacer structure has two or more phosphonic acid groups and / or phosphonate ester units; one or more basic functional groups; or one or more cationic functional groups based on a basic functional group.

[0063] The number of phosphonic acid groups and / or phosphonate ester units present via a spacer structure may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more per monomer unit.

[0064] The number of basic functional groups present via the spacer structure may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more per monomer unit.

[0065] The number of cationic functional groups based on basic functional groups present via a spacer structure per monomer unit may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more.

[0066] The spacer structure is preferably a hydrocarbon spacer, and some and / or all of the hydrogen atoms of the hydrocarbon spacer may be substituted with fluorine.

[0067] In the monomer of the present invention having a functional group via a spacer structure and capable of constituting a polymer, when the functional group is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

[0068] In the monomer of the present invention having a functional group via a spacer structure and capable of constituting a polymer, when the functional group is a basic functional group, the spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 3 to 20 carbon atoms.

[0069] In the monomer of the present invention having a functional group via a spacer structure and capable of constituting a polymer, when the functional group is a cationic functional group based on a basic functional group, the spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

[0070] The monomer preferably has a functional group at the end of the spacer structure. When the spacer structure is linear, the functional group is present at the terminal carbon (one position) of the linear chain. When the spacer structure is branched, the functional group is present at the terminal carbon of the branched chain.

[0071] For example, in the case of a three-branched structure, functional groups are present at the terminal carbon atoms of two of the branched chains, and in the case of a four-branched structure, functional groups are present at the terminal carbon atoms of three of the branched chains. In the case of a cyclic spacer, all carbon atoms that constitute the cyclic spacer and are not directly bonded to the main chain skeleton are considered to be terminal carbons.

[0072] The spacer structure is preferably a hydrocarbon spacer. The spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms. The spacer structure preferably has a repeating number of methylene (methylene: -CH2-) groups of 2 to 12 (-(CH2) n -unit, n=2 to 12).

[0073] When two of the above functional groups are bonded to a carbon atom, the spacer is a combination of a methine group (>CH-) and an alkylene (repeated methylene), and when three of the above functional groups are bonded to a carbon atom, the spacer is a combination of a tetrasubstituted carbon atom (>C<) and an alkylene; strictly speaking, such a combination should be called a straight-chain hydrocarbon spacer, but since the main component is alkylene, it will also be called an alkylene spacer.

[0074] The spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer having 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more carbon atoms, and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less carbon atoms.

[0075] The spacer structure has a large carbon number, for example, about 6 or more, so that the polymer is less likely to dissolve in water and is useful as an electrolyte membrane. The spacer structure has a small carbon number, for example, about 14 or less, so that the monomer is easy to produce. The carbon number of the spacer structure is more preferably 7 to 12, and even more preferably 8 to 11.

[0076] The spacer structure preferably contains a monomer having an ethylene skeleton (an alkylene spacer having repeating methylene groups), and is particularly preferably a linear, branched, or cyclic hydrocarbon spacer having 6 or more, 7 or more, or 8 or more carbon atoms and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less carbon atoms.

[0077] The spacer structure preferably contains a monomer having a styrene skeleton, and is particularly preferably a linear, branched, or cyclic hydrocarbon spacer having 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more carbon atoms, and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less carbon atoms.

[0078] The spacer structure is preferably a linear, branched, or cyclic hydrocarbon spacer. Examples of the hydrocarbon spacer include a linear or branched alkylene spacer having 1 to 18 carbon atoms, such as a methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, 1-ethylpropylene group, n-pentylene group, isopentylene group, n-hexylene group, isohexylene group, 3-methylpentylene group, n-heptylene group, n-octylene group, n-nonylene group, n-decylene group, n-undecylene group, n-dodecylene group, 5-propylnonylene group, n-tridecylene group, n-tetradecylene group, n-pentadecylene group, hexadecylene group, heptadecylene group, or octadecylene group.

[0079] The spacer structure is preferably a cyclic spacer having 3 to 8 carbon atoms, such as a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, or a phenylene group.

[0080] Preferably, the spacer structure may be a combination of a plurality of the structures listed above.

[0081] The spacer structure is preferably bonded to the styrene-based monomer constituting the monomer at any of the o-, m- and p-positions, for example, with a bonding number of 1 to 5.

[0082] [2] Polymer The polymer of the present invention contains a monomer unit consisting of a monomer of the present invention having a functional group via a spacer structure and capable of constituting a polymer.

[0083] The polymer is preferably one formed by step polymerization, in which multifunctional (usually difunctional) monomers react to form first multifunctional dimers, then multifunctional trimers, then longer multifunctional oligomers, and finally multifunctional long-chain polymers.

[0084] The polymer is preferably one formed by chain polymerization, in which monomer molecules are added one at a time to active sites on a growing polymer chain.

[0085] The polymer of the present invention is preferably a hydrocarbon-based or hydrogen fluoride-based polymer, more preferably a polymer formed by chain polymerization or a polymer formed by step-growth polymerization. The side chain represents a functional group or a unit containing a functional group branched from the main chain (corresponding to the central part of the chain, the trunk).

[0086] The polymer is preferably a polymer formed by addition polymerization, i.e., chain polymerization of radical, anionic, and cationic polymerization, or a polymer formed by condensation polymerization and step-growth polymerization of addition condensation.

[0087] (polymer formed by chain polymerization) The polymer is preferably a polymer formed by chain polymerization, such as a styrene-based polymer or an ethylene-based polymer.

[0088] (Polymer formed by step-growth polymerization) The polymer is preferably a polymer formed by step-growth polymerization, such as a fluorene-based polymer, a phenylene-based polymer, a furan-based polymer, or a thiophene-based polymer.

[0089] The polymer preferably does not contain a highly hydrolyzable functional group in the main chain.

[0090] The polymer preferably does not contain any highly hydrolyzable functional groups or bonds at the connecting portions of the main chain skeleton.

[0091] The polymer preferably does not contain a highly hydrolyzable functional group between the main chain skeleton and the spacer structure (the portion where the spacer structure is connected to the main chain skeleton, the base portion of the side chain), and / or between the spacer structure and a phosphonic acid group and / or a phosphonate ester unit that is part of the side chain of the polymer; a basic functional group; or a cationic functional group based on a basic functional group.

[0092] (Polymer having phosphonic acid groups and / or phosphonate ester units in the side chain via a spacer structure) The polymer includes monomer units composed of monomers, and the functional group of the monomer units is a phosphonic acid group and / or a phosphonate ester unit, and each spacer structure has two or more of the phosphonic acid group and / or phosphonate ester units.

[0093] The polymer having a phosphonic acid group and / or a phosphonate ester unit in the side chain is composed of a monomer unit that has a functional group via a spacer structure and can constitute a polymer.

[0094] The polymer may have, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more phosphonic acid groups and / or phosphonate ester units present via a spacer structure per monomer unit.

[0095] The polymer having a phosphonic acid group and / or a phosphonate ester unit in its side chain may be a homopolymer consisting of only monomer units having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure, or a radandum copolymer consisting of a monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure and other monomer units.

[0096] In the case of a random copolymer, the ratio of the monomer units is preferably such that the monomer units having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure account for 50 mol % or more.

[0097] Monomer units other than those having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure may include monomer units having a basic functional group via a spacer structure, and monomer units having a cationic functional group based on a basic functional group via a spacer structure.

[0098] A polymer having a phosphonic acid group in a side chain via a spacer structure can be preferably converted to a phosphonic acid group by deprotecting a phosphonate ester unit. For example, when synthesizing a polymer, the polymer is formed in a state in which a protecting group is attached, and then deprotected to form a polymer having a phosphonic acid group.

[0099] After polymerizing a monomer having a phosphonate ester unit via a spacer structure, the monomer unit is deprotected to obtain a polymer containing a phosphonic acid group, which is an acidic functional group. The deprotection rate in the polymer is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, and particularly preferably 95% or more.

[0100] A polymer having a phosphonic acid group on a side chain via a spacer structure preferably does not contain a highly hydrolyzable functional group between the main chain skeleton of the polymer and the phosphonic acid group (spacer structure).

[0101] (Polymer having basic functional groups in the side chains via a spacer structure) The polymer contains a monomer unit made of a monomer, and the functional group of the monomer unit is a basic functional group, and the monomer unit has one or more basic functional groups per spacer structure.

[0102] The polymer having a basic functional group in its side chain via a spacer structure is preferably a polymer having a basic functional group composed of at least one selected from the group consisting of an amino group, an imino group, a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyrrolyl group, a pyrimidyl group, a pyrazinyl group, and a triazolyl group, but is not limited to this as long as it exhibits basicity (the property of accepting a proton or donating an electron pair).

[0103] The polymer may have, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more basic functional groups present via a spacer structure per monomer unit.

[0104] The polymer having basic functional groups in its side chains via a spacer structure is preferably a polymer having 5 or more basic functional groups, more preferably 10 or more, and even more preferably 15 or more.

[0105] The molecular weight of the polymer having a basic functional group in a side chain via a spacer structure is preferably 200 or more, 500 or more, or 1,000 or more, and more preferably 2,000 or more, 5,000 or more, 10,000 or more, 20,000 or more, 40,000 or more, or 80,000 or more.

[0106] (Polymers with cationic functional groups based on basic functional groups in the side chains via spacer structures) The polymer includes a monomer unit made of a monomer, and the monomer unit is not a fluorene-based monomer unit, but the functional group is a cationic functional group based on a basic functional group, and each spacer structure has one or more cationic functional groups based on the basic functional group.

[0107] The polymer having a basic functional group in a side chain via a spacer structure may be a polymer having a cationic functional group based on the basic functional group, or may be a polymer in which a part of the basic functional group has been quaternized with an organic halogen compound to become a cation, thereby forming a cationic functional group based on the basic functional group.

[0108] The polymer may have, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more cationic functional groups based on basic functional groups present via a spacer structure per monomer unit.

[0109] The proportion of cationic functional groups based on basic functional groups among the basic functional groups may be 10 mol % or more, or may be 30 mol %, 50 mol %, 70 mol %, 90 mol %, or 100 mol %.

[0110] An organic halogen compound is, for example, a compound having an alkyl halide moiety.

[0111] As a compound having an alkyl halide moiety, alkyl halides are C n H 2n+1 -X (n: natural number, X=F, Cl, Br, I) or RC n H 2n A compound representing -X (R: any organic functional group, N: natural number, X=F, Cl, Br, I), and particularly preferred is an alkyl halide.

[0112] [3] Block polymer The polymer of the present invention is preferably a block polymer (a block polymer having ab-type units) in which at least an a block and a b block are connected by a covalent bond. Block polymers also include so-called graft copolymers and star copolymers having a branched structure.

[0113] The polymer of the present invention is preferably a block polymer in which at least an a block, a b block, and a c block are connected by a covalent bond. Block polymers also include so-called graft copolymers and star copolymers having a branched structure.

[0114] (Block A) The a block of the present invention is a polymer having a phosphonic acid group and / or a phosphonate ester unit in its side chain via a spacer structure. The polymer constituting the a block is preferably a hydrocarbon-based polymer, more preferably a polystyrene-based polymer. The a block has a phosphonic acid group in its side chain via a spacer structure, and can exhibit good conductivity.

[0115] The a block preferably contains a monomer unit consisting of a monomer that has the functional group via a spacer structure and can constitute a polymer, wherein the functional group in the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure does not contain a highly hydrolyzable functional group, and each spacer structure is a polymer having one or more of the phosphonic acid group and / or phosphonate ester unit.

[0116] The a block preferably contains a monomer unit consisting of a monomer that has the functional group via a spacer structure and can constitute a polymer, wherein the functional group in the monomer unit is a basic functional group, the spacer structure does not contain a highly hydrolyzable functional group, and each spacer structure is a polymer that has one or more basic functional groups.

[0117] The a block preferably contains a monomer unit consisting of a monomer that has the functional group via a spacer structure and can constitute a polymer, the monomer unit is not a fluorene-based monomer unit, the functional group in the monomer unit is a cationic functional group based on a basic functional group, the spacer structure does not contain a highly hydrolyzable functional group, and each spacer structure is a polymer that has one or more cationic functional groups based on the basic functional group.

[0118] The a block may be a homopolymer consisting of only monomer units having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure, or a random copolymer consisting of monomer units having a phosphonic acid group and / or a phosphonate ester unit in a side chain via a spacer structure and other monomer units. In a random copolymer, the abundance ratio of the two or more types of monomer units contained in the polymer is preferably 50 mol % or more of the monomer units having a phosphonic acid group and / or a phosphonate ester unit in a side chain via a spacer structure.

[0119] In the random copolymer, the monomer unit other than the monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure may be a monomer unit having a basic functional group via a spacer structure or a monomer unit having a cationic functional group based on a basic functional group via a spacer structure.

[0120] A polymer having phosphonic acid groups and / or phosphonate ester units in its side chains via a spacer structure has phosphonic acid groups, and the spacer structure makes it easy for phase separation to occur between the hydrophobic portion consisting of the main chain skeleton and the spacer structure and the hydrophilic portion consisting of the phosphonic acid groups.As a result, the phosphonic acid groups tend to be aligned closely together, making it easier to form continuous ion conduction channels (ion conduction paths) compared to when the polymer does not have a spacer structure, and exhibiting good conductivity.

[0121] Furthermore, the spacer structure allows the functional groups to move freely, providing a proton conduction mechanism in which the functional groups move while retaining protons, known as the vehicle mechanism. Furthermore, the proton conduction mechanism in which protons hop from one functional group retaining a proton to another functional group, known as the Grotus mechanism, also exists. Because proton conduction is achieved through the vehicle mechanism of the functional groups and the Grotus mechanism between functional groups, the material exhibits good proton conductivity even in the absence of low molecular weight electrolytes such as water molecules or inorganic acids.

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] m≧2 R1: Polymerizable unit (e.g., vinyl group, unit with two halogen groups) R1': Main chain skeleton of the monomer unit Spacer: Spacer structure R2: Protecting group (alkyl group, etc.) or H

[0126] R1' represents the main chain skeleton of a monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure. When R1 represents a vinyl group, R1' is -CH2-CH-. When R1 represents a p-substituted styrene unit, R1' is -CH2-CH(C6H4)-.

[0127] The a block preferably contains a monomer unit consisting of a monomer that has a functional group via a spacer structure and can constitute a polymer, the functional group of the monomer unit being a phosphonic acid group and / or a phosphonate ester unit, the spacer structure not containing a highly hydrolyzable functional group, and the polymer contains a monomer unit having one or more of the phosphonic acid group and / or phosphonate ester unit per spacer structure.

[0128] (Block b) The b block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg, measured by DSC) of 50° C. or lower. The polymer constituting the b block preferably has a Tg of 35° C. or lower, more preferably 20° C. or lower.

[0129] The b block is preferably a polymer that does not contain highly hydrolyzable functional groups, and is best suited to polymers in which alkyl chains are directly bonded to the main chain, such as poly(pn-alkylstyrene) and poly(di(n-alkyl)fluorene). The number of alkyl chains can be two or more.

[0130] These polymers can be formed by polymerizing monomers such as pn-alkylstyrene and di(n-alkyl)fluorene.

[0131] The alkyl group may be an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, or the like, and the number of carbon atoms in the alkyl group (m+1) is preferably 2 to 20. The molecular weight is preferably 50,000 or more.

[0132] [ka]

[0133] [ka]

[0134] The b block may be a homopolymer consisting of only monomer units in which an alkyl chain is directly bonded to the main chain skeleton, or a raddam copolymer consisting of monomer units in which an alkyl chain is directly bonded to the main chain skeleton and other monomer units.

[0135] When the block polymer is made into a membrane, the b block appropriately distributes the stress applied to the membrane, contributing to mechanical strength at low temperatures (below 100°C) and high temperatures (above 100°C).

[0136] (c block) The c block is composed of a hydrophobic polymer or a water-repellent polymer, and is a polymer having a glass transition temperature (Tg, measured by DSC) of 120° C. or higher. The polymer constituting the c block preferably has a Tg of 130° C. or higher, more preferably 140° C. or higher.

[0137] The c block may be a homopolymer consisting of a single monomer unit, a ladandum copolymer consisting of two or more types of monomer units, or the like.

[0138] When the block polymer is made into a membrane, the c-block prevents the membrane from flowing and contributes to mechanical strength at low temperatures (below 100°C) and high temperatures (above 100°C).

[0139] The glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121:2012 based on a DSC curve obtained by measurement at a temperature rise rate of 10°C / min.

[0140] When it is difficult to determine the glass transition temperature (Tg) in a DSC curve, the glass transition temperature (Tg) can also be determined as the peak value of the loss tangent (tan δ) in dynamic mechanical analysis (DMA).

[0141] The hydrophobic polymer or water-repellent polymer of the c-block is preferably a hydrophobic hydrocarbon polymer, and the hydrophobic polymer preferably has a molecular weight of 50,000 or more.

[0142] The water-repellent polymer is a polymer that has the property of repelling water droplets when they are dropped onto its surface (water repellency), and the contact angle is preferably 90° or more, and more preferably 100° or more.

[0143] More preferred examples of the hydrophobic or water-repellent hydrocarbon styrene polymers that are c blocks include poly(p-phenylstyrene), poly(p-tert-butylstyrene) (glass transition temperature: 150°C), etc. Also, more preferred examples of the hydrophobic or water-repellent hydrocarbon fluorene polymers that are c blocks include polyfluorene, etc.

[0144] The water-repellent polymer of the c-block preferably includes a silicone compound or a fluorinated polymer. As the fluorocarbon vinyl polymer, more preferably, polyperfluorostyrene, polyperfluoromethylstyrene, etc.

[0145] The average degree of polymerization of the a block, the b block, or the c block is preferably an integer of 2 or more, for example, 2 or more, 10 or more, 30 or more, 50 or more, 100 or more, 200 or more, 500 or more, 800 or more, 1,000 or more, 1,500 or more, or 2,000 or more. The average degree of polymerization of the a block is preferably 20,000 or less, 15,000 or less, 10,000 or less, 8,000 or less, 5,000 or less, or 4,000 or less.

[0146] The average degree of polymerization can be determined by gel permeation chromatography (GPC) using standard polystyrene or by comparing the proton intensity of initiator residues with the proton intensity of the repeating units of the polymer. 1 Determined by H-NMR.

[0147] The molecular weight of the block polymer is preferably 50,000 or more, 100,000 or more, 200,000 or more, 400,000 or more, 600,000 or more, or 800,000 or more.

[0148] The molecular weight of the polymer is determined by gel permeation chromatography (GPC) to determine the molecular weight distribution (Mw / Mn) using polystyrene standards for molecular weight calibration.

[0149] [4] A combination of a polymer having a phosphonic acid group and / or a phosphonate ester unit in the side chain via a spacer structure and a polymer having a basic functional group and / or a cationic functional group based on a basic functional group in the side chain via a spacer structure. A polymer (random polymer or homopolymer) containing a monomer unit having a phosphonic acid group and / or a phosphonate ester unit via a spacer structure may be combined with a polymer (random polymer or homopolymer) containing a monomer unit having a basic group and / or a cationic functional group based on a basic functional group via a spacer structure. The combination can be achieved by mixing or copolymerization.

[0150] [ka]

[0151] Z: Basic functional group

[0152] A polymer having a basic functional group in a side chain via a spacer structure contains Z (basic functional group). In a homopolymer, random copolymer, or block polymer having a basic functional group in a side chain via a spacer structure, Z (basic functional group) represents a basic functional group, such as an amino group, imino group, pyridyl group, imidazoyl group, pyrazolyl group, pyrrolyl group, pyrimidyl group, pyrazinyl group, or triazolyl group.

[0153] [ka]

[0154] (+)ZR: Cationic functional group based on basic functional group X(-): Counter anion of cationic functional group

[0155] The polymer having a basic functional group and / or a cationic functional group based on a basic functional group in its side chain via a spacer structure may contain a monomer unit having a basic functional group and a cationic functional group ((+)ZR) via a spacer structure.

[0156] [ka]

[0157] (PO3H)(-)(+)ZR: an ion pair consisting of a phosphonate group and a cationic functional group (POH)(-)(+)ZH: An acid-base complex consisting of a phosphonic acid group and a basic functional group (an ion pair consisting of the acid and base themselves) The volatile acid HX is removed from the system by humidification. n, p, q≧1 m≧2 0 <v,w,x,y≦1 v+w=1

[0158] [ka]

[0159] (PO3H)(-)(+)ZR: an ion pair consisting of a phosphonate group and a cationic functional group (POH)(-)(+)ZH: An acid-base complex consisting of a phosphonic acid group and a basic functional group (an ion pair consisting of the acid and base themselves) The volatile acid HX is removed from the system by humidification. n, p, q, r≧1 m≧2 0 <v,w,x,y≦1 v+w=1 R3: Hydrophobic or water-repellent functional group with Tg≦50℃

[0160] [ka]

[0161] (PO3H)(-)(+)ZR: an ion pair consisting of a phosphonate group and a cationic functional group (POH)(-)(+)ZH: An acid-base complex consisting of a phosphonic acid group and a basic functional group (an ion pair consisting of the acid and base themselves) The volatile acid HX is removed from the system by humidification. n,p,q,r,s≧1 m≧2 0 <v,w,x,y≦1 v+w=1 R4: A hydrophobic or water-repellent functional group that has a Tg of 120°C or higher

[0162] A polymer (random polymer, homopolymer, or block polymer) having a phosphonic acid group and / or a phosphonate ester unit in the side chain via a spacer structure may be combined with a polymer (random polymer, homopolymer, or block polymer) having a basic functional group in the side chain via a spacer structure and a polymer (random polymer, homopolymer, or block polymer) having a cationic functional group in the side chain via a spacer structure. The combination can be achieved by physical mixing or copolymerization. Block polymers also include graft copolymers and star copolymers.

[0163] A pair of a phosphonic acid group and Z (basic functional group) represents an acid-base complex. A free phosphonic acid group that is not paired with Z can ionize protons that contribute to proton conductivity. A Z that is not paired with a phosphonic acid group is a free basic functional group.

[0164] The pairing of a phosphonate group with a (+)ZR (cationic functional group) represents an ion pair. A free phosphonic acid group that is not paired with a (+)ZR can ionize a proton that contributes to proton conductivity. A (+)ZR that is not paired with a phosphonic acid group is a free cationic functional group.

[0165] [5] Method for producing a monomer having two or more phosphonic acid groups and / or phosphonate ester units via a spacer structure (1) (A) A monomer for chain polymerization having two phosphonate ester units per spacer structure: tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, 9-(p-Styryl)-1,1-nonanediphosphonic acid tetraisopropyl ester 4-(p-styryl)-1,1-butanediphosphonic acid tetraethyl ester, etc.

[0166] (B) A monomer for chain polymerization having three phosphonate ester units per spacer structure: hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate, and the like. These can be synthesized by the following steps.

[0167] (Step 1-1 of the first step (A)) Under a nitrogen atmosphere, a monomer such as p-bromostyrene is dissolved in dehydrated tetrahydrofuran (THF) and cooled to -78°C. A polymerization initiator (such as n-butyllithium) in n-hexane is added. An alkylene dibromide (such as 1,8-dibromooctane or 1,4-dibromobutane) is added, the temperature is raised to -40°C, and the mixture is stirred, then further stirred at room temperature. Methanol is then added to terminate the reaction, synthesizing a monomer with an alkylene spacer (such as p-(8-bromooctyl)styrene or p-(4-bromobutyl)styrene).

[0168] (Step 1-2 of the first step (A)) The precursor monomer having an alkylene spacer obtained in step 1-1 (p-(8-bromooctyl)styrene, p-(4-bromobutyl)styrene, etc.) is dissolved in phenylacetonitrile, triethyl phosphite is added, and the mixture is stirred in an oil bath at 120°C. After separation and purification, diethyl 8-(p-styryl)-1-octanephosphonate, diethyl 4-(p-styryl)-1-butanephosphonate, etc. are obtained.

[0169] (Steps 1-3 of the first step (A)) Tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate, etc. are synthesized.

[0170] Under an argon atmosphere, diethyl 8-(p-styryl)-1-octanephosphonate, diethyl 4-(p-styryl)-1-butanephosphonate, etc. are dissolved in dehydrated THF and cooled to -78°C. A solution of lithium diisopropylamide (LDA) in THF / heptane / ethylbenzene is added and stirred. Diethyl chlorophosphate is added and stirred for a while, then the mixture is stirred at room temperature. Chain polymerization monomers (tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) are obtained, each having two phosphonate ester units via an alkylene spacer.

[0171] (First step (B)) Sodium hydride dispersed in liquid paraffin is dissolved in dehydrated THF under a nitrogen atmosphere, and tetraisopropyl methylenediphosphonate is added. A monomer having an alkylene spacer (e.g., p-(8-bromooctyl)styrene) is then added, and the mixture is stirred at 70°C, followed by further stirring at 55°C. After separation and purification, a chain polymerization monomer (e.g., tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) is obtained, which has two phosphonate ester units per spacer via the alkylene spacer.

[0172] (First step (C)) A chain polymerization monomer having two phosphonate ester units per spacer (e.g., tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) is dissolved in dehydrated THF under a nitrogen atmosphere and cooled to 0°C. A THF solution of sodium bis(trimethylsilyl)amide is added to the solution and stirred. Diethyl chlorophosphite is added to the solution and stirred, and then aqueous hydrogen peroxide is added and stirred again to obtain a chain polymerization monomer having three phosphonate ester units per spacer (e.g., hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate).

[0173] After the first step, the volatile solvent is evaporated by rotary evaporation, followed by extraction by liquid separation to remove the solvent, and then by vacuum distillation to remove unreacted raw material compounds and by-products.

[0174] [ka]

[0175] (2) (A) Monomer for step-growth polymerization having two phosphonate ester units per spacer structure: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) and the like.

[0176] (B) Monomers for step-growth polymerization having three phosphonate ester units per spacer structure: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) and the like. These can be synthesized by the following steps.

[0177] (Step 1 of 1). Sodium hydride (60 wt%) dispersed in liquid paraffin is dissolved in dehydrated THF under a nitrogen atmosphere, and tetraisopropyl methylenediphosphonate is added. Then, a precursor monomer (2,7-dibromo-9,9-bis(6-bromohexyl)fluorene, etc.) is added and heated with stirring. Saturated ammonium chloride solution is then added to terminate the reaction.

[0178] Extraction is performed by a separation operation, and the solvent used in the separation operation is removed using rotary evaporation. Further separation and purification are carried out by passing through a silica gel column to obtain a monomer for step-growth polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(1,1-heptanediphosphonate tetraisopropyl)) having two phosphonate ester units per spacer structure. Ethyl acetate and 2-propanol are used as developing solvents.

[0179] (Step 2 of the first step). In the first step, a monomer for step-growth polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) having two phosphonate ester units per spacer structure to be synthesized) is dissolved in dehydrated THF under an argon gas atmosphere and cooled to 0°C.

[0180] Add a THF solution of sodium bis(trimethylsilyl)amide, add diethyl chlorophosphite, and then add hydrogen peroxide and stir to synthesize a monomer for step-growth polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate)) with three phosphonate ester units per spacer structure.

[0181] The volatile solvent (THF) is evaporated by rotary evaporation. Extraction is performed by separation, and the solvent used in the separation is removed by rotary evaporation. Further, unreacted diethyl chlorophosphite and by-products are removed by vacuum distillation.

[0182] The resulting liquid is separated and purified by passing it through a silica gel column to obtain a monomer for step-growth polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate)) having three phosphonate ester units per spacer structure. Ethyl acetate, methanol, and propanol are used as developing solvents.

[0183] [ka]

[0184] [6] Method for producing a monomer having a basic functional group via a spacer structure (1) Monomers for chain polymerization having basic functional groups: p-(9-(p-styryl)-nonyl)pyridine and the like. These can be synthesized by the following steps.

[0185] A compound with a basic functional group (e.g., p-methylpyridine) is dissolved in dehydrated THF and cooled to -80°C. A tetrahydrofuran (THF) / heptane / ethylbenzene solution of a strong base (e.g., lithium diisopropylamide (LDA)) is added and stirred. A precursor monomer with an alkylene spacer (e.g., p-(8-bromooctyl)styrene) is added and stirred to obtain a chain polymerization monomer (e.g., p-(9-(p-styryl)-nonyl)pyridine) that contains a basic functional group via a spacer structure.

[0186] After the above steps, the volatile solvent is evaporated by rotary evaporation, and the solvent is removed by extraction using a liquid separation operation. The resulting liquid is then passed through a silica gel column or the like for separation and purification, yielding a chain polymerization monomer (e.g., p-(9-(p-styryl)-nonyl)pyridine) having a basic functional group via a spacer structure.

[0187] [ka]

[0188] (2) Monomers for step-growth polymerization having basic functional groups: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(pn-heptylpyridine) and the like. These can be synthesized by the following steps.

[0189] A compound with a basic functional group (e.g., p-methylpyridine) is dissolved in a dehydrated solvent and cooled. A strong base (e.g., lithium diisopropylamide (LDA)) is added and stirred. A precursor monomer with an alkylene spacer (e.g., 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene) is added and stirred to obtain a chain polymerization monomer (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(pn-heptylpyridine)) that contains a basic functional group via a spacer structure.

[0190] After the above steps, the volatile solvent is evaporated by rotary evaporation, and the solvent is removed by extraction using a liquid separation operation. The resulting liquid is then passed through a silica gel column or the like for separation and purification, yielding a chain polymerization monomer (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(pn-heptylpyridine)) having a basic functional group via a spacer structure.

[0191] [ka]

[0192] [7] A method for producing a monomer having a cationic functional group based on a basic functional group via a spacer structure (1) Monomers for chain polymerization having a cationic functional group based on a basic functional group: 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide, etc. These can be synthesized by the following steps.

[0193] A compound with a basic functional group (e.g., p-methylpyridine) is dissolved in dehydrated THF and cooled to -80°C. A tetrahydrofuran (THF) / heptane / ethylbenzene solution of a strong base (e.g., lithium diisopropylamide (LDA)) is added and stirred. A precursor monomer with an alkylene spacer (e.g., p-(8-bromooctyl)styrene) is added and stirred to obtain a monomer with a basic functional group via a spacer structure (e.g., p-(9-(p-styryl)-nonyl)pyridine).

[0194] An organic halogen compound (bromoethane, etc.) is added to a monomer (p-(9-(p-styryl)-nonyl)pyridine, etc.) having a basic functional group via a spacer structure, and the mixture is stirred, quaternized, and cationized to obtain a monomer (1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide, etc.) having a cationic functional group based on the basic functional group via a spacer structure. The resulting mixture is then vacuum dried.

[0195] [ka]

[0196] The above-mentioned organic halogen compounds (bromoethane, etc.) are compounds having a halogenated alkyl moiety.

[0197] Among the compounds having the above alkyl halide moiety, alkyl halide is C n H 2n+1 -X (n: natural number, X=F, Cl, Br, I), and other compounds with alkyl halide moieties include RC n H 2n A compound representing -X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and particularly preferred is an alkyl halide.

[0198] (2) Monomers for step-growth polymerization having a cationic functional group based on a basic functional group: 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(N-ethyl-pn-heptylpyridinium bromide), etc. These can be synthesized by the following steps.

[0199] A compound with a basic functional group (e.g., p-methylpyridine) is dissolved in a dehydrated solvent and cooled. A strong base (e.g., lithium diisopropylamide (LDA)) is added and stirred. A precursor monomer with an alkylene spacer (e.g., 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene) is added and stirred to obtain a monomer for step-growth polymerization (e.g., 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(pn-heptylpyridine)) that contains a basic functional group via a spacer structure.

[0200] An organic halogen compound (bromoethane, etc.) is added to a monomer (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(pn-heptylpyridine, etc.) having a basic functional group via a spacer structure, and the mixture is stirred, quaternized, and cationized to obtain a monomer for sequential polymerization (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(N-ethyl-pn-heptylpyridinium bromide, etc.) having a cationic functional group based on the basic functional group via a spacer structure. The resulting mixture is then vacuum dried.

[0201] [ka]

[0202] The above-mentioned organic halogen compounds (bromoethane, etc.) are compounds having a halogenated alkyl moiety.

[0203] Among the compounds having the above alkyl halide moiety, alkyl halide is C n H 2n+1-X (n: natural number, X=F, Cl, Br, I), and other compounds with alkyl halide moieties include RC n H 2n A compound representing -X (R: any organic functional group, n: natural number, X=F, Cl, Br, I), and particularly preferred is an alkyl halide.

[0204] [8] Polymer and method for producing block polymer (1) A method for producing a polymer formed by chain polymerization and a block polymer formed by chain polymerization RAFT Agents (Reversible Addition-Fragmentation Chain Transfer Agents) RAFT agents preferably include thiocarbonylthio compounds such as dithioesters, dithiocarbamates, trithiocarbonates, and xanthates.

[0205] The RAFT agent is preferably a RAFT agent such as 4-[(2-carboxyethylsulfanylthiocarbonyl)sulfanyl]-4-cyanopentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid, or methyl 2-(dodecylthiocarbonothioylthio)-2-methylpropionate.

[0206] The RAFT agent is preferably 2-(dodecylthiocarbonothioylthio)propionic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid pentafluorophenyl ester, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid 3-azido-1-propanol ester, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, methyl 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoate, or N-hydroxysuccinimidyl 2-(dodecylthiocarbonothioylthio)-2-methylpropionate.

[0207] The RAFT agent is preferably a RAFT agent such as 3-[[(benzylthio)carbonothioyl]thio]propionic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid, cyanomethyl[3-(trimethoxysilyl)propyl]trithiocarbonate, 3-butenyl-2-(dodecylthiocarbonothioylthio)-2-methylpropane, phthalimidomethylbutyltrithiocarbonate, 2-(2-carboxyethylsulfanylthiocarbonylsulfanyl)propionic acid, or 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid.

[0208] The RAFT agent is preferably 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanol, cyanomethyl dodecyl trithiocarbonate 1,4-phenylenebis(methylene) didodecyl bis(carbonotrithioate), 1,4-phenylenebis(methylene) dibutyl bis(carbonotrithioate), 1,4-phenylenebis(methylene) dioctadecyl bis(carbonotrithioate), or the like.

[0209] By appropriately selecting the RAFT agent, polymers can be synthesized by radical polymerization.

[0210] polymerization initiator The polymerization initiator is preferably an azo-based radical polymerization initiator, a peroxide-based radical polymerization initiator, or the like.

[0211] The polymerization initiator is preferably an azo-based radical polymerization initiator such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or dimethyl 2,2'-azobisisobutyrate.

[0212] The polymerization initiator is preferably a peroxide radical polymerization initiator such as benzoyl peroxide, t-butyl hydroperoxide, or cumene hydroperoxide.

[0213] The method for synthesizing the polymer and block polymer is not particularly limited as long as it is addition polymerization such as anionic polymerization, cationic polymerization, radical polymerization, etc. Depending on the type of monomer, synthesis may also be performed by condensation polymerization.

[0214] The following describes an example of a method for synthesizing a block polymer having an a block and a b block.

[0215] (A) A step of synthesizing a hydrophobic polymer and producing a b-block A monomer constituting the b block (e.g., 4-alkylstyrene monomer), a RAFT agent (reversible addition-fragmentation chain transfer agent), and a polymerization initiator are mixed and polymerized, followed by isolation and purification by reprecipitation or other methods to synthesize a macro RAFT agent containing the b block.

[0216] The solvent used in the synthesis and isolation is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and etheric solvents such as dimethyl ether, diethyl ether and tetrahydrofuran. The solvent is not limited to these.

[0217] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0218] (B) A step of polymerizing a monomer having a phosphonic acid group protected by a protecting group via a spacer structure to the b block to form an a block, thereby producing a block polymer having ab-type units in which the b block and the a block composed of units of the monomer are linked by a covalent bond through polymerization. Next, in the presence of a polymerization initiator, b a macro RAFT agent comprising a block; aA block copolymer having ab-type units in which the a block and the b block are linked by a covalent bond is produced by polymerizing a monomer (e.g., tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) having a protecting group (e.g., ethyl group) on the phosphonic acid group that constitutes the block.

[0219] The solvent used in the synthesis, isolation, and purification is preferably a solvent that evaporates relatively easily. Examples of the solvent include water, alcoholic solvents such as methanol and ethanol, and etheric solvents such as dimethyl ether, diethyl ether, and tetrahydrofuran. The solvent is not limited to these.

[0220] The means for removing the solvent is not particularly limited. The means for removing the solvent is preferably evaporation at room temperature or by heating. The means for removing the solvent may include an appropriate operation such as drying.

[0221] (C) a step of producing a block polymer containing approximately 2.0 or more phosphonic acid groups in the monomer units constituting the a block by deprotecting the protecting group possessed by the a block. By deprotecting the protecting group of the a block using a basic solution (e.g., aqueous sodium hydroxide solution) or bromotrimethylsilane (see Tetrahedron Letters 1977, 18, 155-158), if the deprotection rate is approximately 100%, a polymer having approximately 2.0 or more phosphonic acid groups per monomer unit is produced.

[0222] The polymer having a phosphonic acid group in the side chain constituting the a block via a spacer structure is more preferably a polymer containing approximately 2.0 or more phosphonic acid groups per monomer unit.

[0223] (2) Polymers formed by step-growth polymerization and methods for producing block polymers formed by step-growth polymerization (A) Polymer synthesis Bis(1,5-cyclooctadiene)nickel(0), 2,2'-bipyridyl, and 1,5-cyclooctadiene are weighed out and added to N,N-dimethylformamide (DMF), followed by heating and stirring.

[0224] Toluene is added to a monomer for sequential polymerization (7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) etc.) having two phosphonate ester units per spacer structure, and the mixture is stirred.

[0225] The resulting solution is washed with chloroform, hydrochloric acid, pure water, and saturated saline, and then reprecipitated with n-hexane to obtain a purified polymer formed by step-growth polymerization (e.g., poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate))).

[0226] (B) Deprotection of alkyl protecting groups A polymer formed by step-growth polymerization (such as poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) is dissolved in chloroform, bromotrimethylsilane is added, the mixture is placed in a 40°C oil bath, and the mixture is stirred overnight.

[0227] The polymer is reacted and dissolved in an excess amount of methanol, and then purified by dialysis using a cellulose dialysis tube and pure water. Finally, the water is evaporated to obtain the polymer formed by step-growth polymerization in which the alkyl protecting groups have been deprotected.

[0228] [9]Polymer electrolyte membrane The polymer electrolyte membrane of the present invention comprises the polymer or block polymer of the present invention.

[0229] Polymer electrolyte membranes can be produced by, for example, solvent casting or press molding using polymers or block polymers. For example, the polymer or block polymer is dissolved in a mixed solvent of methanol and acidic water (pH 1 or less). The resulting solution is transferred to a polypropylene container and left to stand overnight at 60°C to evaporate the solvent, producing a cast membrane.

[0230] Formation of polymer electrolyte membrane When the polymer electrolyte membrane is formed into a membrane, it is preferably formed by a method such as a casting method or a pressing method before removing the solvent, or preferably by a method such as a hot melt method.

[0231] The polymer electrolyte membrane can be used in the medium temperature range of 100°C or higher and 150°C or lower.

[0232] The temperature at which the polymer electrolyte membrane is used is the temperature at which the proton conductive membrane is used, and is preferably room temperature or higher, more preferably 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, or 90° C. or higher, and in some cases 100° C. or higher. The temperature at which the polymer electrolyte membrane is used is 200° C. or lower, 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, or 110° C. or lower, in some cases.

[0233]

[10] Ionomers and membrane electrode assemblies (MEAs) The polymer or block polymer of the present invention can be used as an ionomer (proton-conducting polymer) to form a catalyst layer for a polymer electrolyte fuel cell. Furthermore, a membrane electrode assembly (MEA) can be produced by combining an electrolyte membrane, a catalyst layer (ionomer + catalyst), and a gas diffusion layer.

[0234] (water resistance) Some of the polymer electrolyte membranes, ionomers, and membrane / electrode assemblies made of the polymer of the present invention may exhibit good water resistance even when immersed in water (e.g., at 60°C for 3 hours) because they have a large proportion of hydrophobic moieties, that is, because the monomer of the present invention constituting the polymer of the present invention has a functional group via a spacer structure (a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms).

[0235] The water immersion conditions for evaluating the water resistance of a polymer film are, for example, immersion in water at 20°C to 90°C for 1 to 3 hours. Even after such water immersion (for example, immersion in water at 60°C for 3 hours), the weight retention (%) compared to before immersion is preferably 90% by weight or more (weight loss (%) is within 10% by weight), more preferably 95% by weight or more (weight loss (%) is within 5% by weight), and even more preferably 99% by weight or more (weight loss (%) is within 1% by weight).

[0236]

[11] Sheet-like material reinforced membrane The sheet-like material-reinforced membrane of the present invention is reinforced with a sheet-like material having voids, which contains the polymer electrolyte membrane of the present invention or the ionomer of the present invention.

[0237] The sheet-like material having voids is preferably heat-resistant and is a nonwoven fabric and / or a porous sheet (such as polyphenylene sulfide).

[0238]

[12] A fuel cell including a fuel cell electrolyte membrane; A water electrolysis device including an electrolyte membrane for water electrolysis, and Ion exchange device including ion exchange membrane (Fuel cell including electrolyte membrane for fuel cell) A fuel cell including the electrolyte membrane for a fuel cell of the present invention includes the polymer (polymer electrolyte membrane) of the present invention or the block polymer (polymer electrolyte membrane) of the present invention.

[0239] The polymer or block polymer exhibits conductivity even at temperatures above 100° C. and low humidity, and can be used in fuel cells, particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0240] The polymer electrolyte membrane exhibits high proton conductivity even at temperatures above 100°C in the absence of humidity (for example, 125°C). The polymer electrolyte membrane can be used in the medium temperature range of 100°C or above and 150°C or below in the absence of humidity, and can be used in fuel cells in the absence of humidity.

[0241] The polymer electrolyte membrane can be used, for example, under conditions of 80°C and 60% RH, or 80°C and 80% RH. The polymer electrolyte membrane exhibits conductivity even at low humidity of 100°C or higher, and can be used particularly as a polymer electrolyte membrane for solid polymer fuel cells.

[0242] The fuel cell preferably has a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side catalyst layer, a polymer (polymer electrolyte membrane) or a block polymer (polymer electrolyte membrane), an air electrode-side catalyst layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0243] The fuel cell preferably has a laminate in which a fuel electrode-side separator having a fuel flow channel, a fuel electrode-side gas diffusion layer, a fuel electrode-side catalyst layer, a polymer (polymer electrolyte membrane) or a block polymer (polymer electrolyte membrane), an air electrode-side catalyst layer, an air electrode-side gas diffusion layer, and an air electrode-side separator having an air flow channel are laminated in this order.

[0244] (Water electrolysis device including electrolyte membrane for water electrolysis) A water electrolysis device including the electrolyte membrane for water electrolysis of the present invention includes the polymer of the present invention or the block polymer of the present invention. The polymer (polymer electrolyte membrane) or the block polymer (polymer electrolyte membrane) is useful as an anhydrous electrolyte membrane.

[0245] (Ion exchange device including ion exchange membrane) An ion exchange device comprising the ion exchange membrane of the present invention comprises the polymer (polymer electrolyte membrane) of the present invention or the block polymer (polymer electrolyte membrane) of the present invention.

[0246]

[13] Separation membrane, anion exchange membrane, or cation exchange membrane (separation membrane) The present invention provides a separation technology suited to various applications by using a separation membrane with selective permeability, allowing only the target substance to pass through, and chemical resistance. The separation membrane of the present invention can be used to produce salt from seawater, recover specific valuables, refine and produce food products such as wine and soy sauce, and produce acid and alkali from neutral salt wastewater.

[0247] (CO2 separation membrane) The separation membrane of the present invention is preferably a CO2 separation membrane. The CO2 separation membrane of the present invention comprises the polymer of the present invention or the block polymer of the present invention. The CO2 separation membrane can be used in CO2 capture and storage technologies to curb global warming. The CO2 separation membrane has CO2 permselectivity and N2 permselectivity, and has CO2 / N2 permselectivity.

[0248] (anion exchange membrane) The anion exchange membrane of the present invention comprises the polymer of the present invention or the block polymer of the present invention.

[0249] Anion exchange membranes are generally formed from an anion exchange resin layer having a substrate sheet serving as a core material, which functions as a reinforcing material, and are widely used in applications such as salt production, desalination, and electrodialysis for producing acids or alkalis from neutral salts, etc. Anion exchange membranes have a reduced shrinkage rate and excellent current efficiency and water permeability.

[0250] (cation exchange membrane) The cation exchange membrane of the present invention comprises the polymer of the present invention or the block polymer of the present invention.

[0251] Electrodialysis (ED) is used to concentrate and separate ions in wastewater. ED is a technology that uses ion exchange membranes to concentrate and demineralize ions. In the concentration process, ions are concentrated by moving them, making it particularly effective for separating and concentrating membrane foulants and specific trace ions. Cation exchange membranes have excellent selective permeability for specific cations, allowing them to selectively concentrate specific cations, and also have low membrane resistance. [Example]

[0252] The present disclosure will be described in more detail below with reference to examples.

[0253] The present disclosure is not limited thereto.

[0254] Example 1 In Example 1, tetraethyl 8-(p-styryl)-1,1-octanediphosphonate was synthesized as a monomer having two phosphonate esters per alkylene spacer according to the following scheme 1 (first step).

[0255] [ka]

[0256] Subsequently, this monomer was polymerized according to the following scheme 2 (second step).

[0257] [ka]

[0258] The alkyl protecting groups of the obtained poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) were deprotected to synthesize poly(8-(p-styryl)-1,1-octanediphosphonic acid) (hereinafter also referred to as "sodPA"), a polymer having two phosphonic acid groups per spacer via an alkylene spacer (third step).

[0259] This sodPA was formed into a membrane to produce the proton-conductive electrolyte membrane of Example 1 (fourth step).

[0260] (First step) (Process 1-1) Under a nitrogen atmosphere, 20.9 g (0.159 mol) of p-bromostyrene was dissolved in 340 mL of anhydrous tetrahydrofuran (THF) and cooled to -78°C. 100 mL (0.159 mol) of n-butyllithium n-hexane solution (concentration 1.6 mol / L) was added. 148 mL (218 g, 0.800 mol) of 1,8-dibromooctane was added. Methanol was then added to quench the reaction, synthesizing p-(8-bromooctyl)styrene.

[0261] The volatile solvents (THF, n-hexane, and methanol) were evaporated by rotary evaporation. Extraction was performed by separation, and the solvent used in the separation was removed by rotary evaporation. Furthermore, unreacted 1,8-dibromooctane and by-products were removed by vacuum distillation.

[0262] The liquid obtained after vacuum distillation was dissolved in deuterated chloroform. 1 H-NMR measurements were performed. In Figure 1, the dotted line indicates p-(8-bromooctyl)styrene. 1 The H-NMR spectrum is shown in Figure 1. The dashed line indicates p-bromostyrene. 1 The H-NMR spectrum is shown.

[0263] The liquid obtained after decompression was dissolved in deuterated chloroform. 13 C-NMR measurements were also performed. In Figure 2, the dotted line indicates p-(8-bromooctyl)styrene. 13 The C-NMR spectrum is shown in Figure 2. The dashed line indicates 4-bromostyrene. 13 The C-NMR spectrum is shown.

[0264] of the precursor 4-bromostyrene 1 In the H-NMR spectrum, protons attached to the vinyl group (a''', b''', c''') were observed at around 5.2, 5.7, and 6.7 ppm, and protons attached to the benzene ring (d''', e''') were observed at around 7.3 and 7.4 ppm.

[0265] After the reaction 1 In the H-NMR spectrum, the chemical shifts of the protons (a'', b'', c'') on the vinyl group remained almost unchanged, while the peaks derived from the protons (d'', e'') on the benzene ring shifted to around 7.1 and 7.3 ppm.

[0266] Furthermore, the peak of the methylene group proton (f'') adjacent to the benzene ring was observed at 2.6 ppm, the peak of the methylene group proton (m'') with a bromo group was observed at 3.4 ppm, and the peaks of the methylene group protons (g''-l'') between them were observed at 1.3-1.9 ppm. Since the integral ratio of each peak was approximately 1:1:6, it is believed that p-(8-bromooctyl)styrene was obtained.

[0267] The peak at 7.27 ppm is a peak derived from chloroform.

[0268] of the precursor 4-bromostyrene 13 In the C-NMR spectrum, the carbon atoms of the vinyl group (a'', b'', c''') were found at around 115, 136, and 137 ppm, respectively, and the carbon atoms of the benzene ring (d'', e'', f''') were found at around 132, 128, and 122 ppm, respectively.

[0269] After the reaction 13 In the C-NMR spectrum, the chemical shifts of the protons (a'', b'', c'') attached to the vinyl group shifted to around 113, 137, and 135 ppm, respectively, and the peaks due to the protons (d'', e'', f'') attached to the benzene ring shifted to around 129, 126, and 143 ppm, respectively. This change in chemical shift is thought to be due to the loss of the bromo group attached to the benzene ring.

[0270] Furthermore, eight peaks attributable to the carbon atoms (g'' to n'') of the methylene group were newly observed at 28 to 36 ppm, suggesting that p-(8-bromooctyl)styrene was obtained.

[0271] The peak near 77 ppm is a peak derived from chloroform.

[0272] (Step 1-2) 9.0 g (31 mmol) of p-(8-bromooctyl)styrene obtained in step 1-1 was dissolved in 9.0 g of phenylacetonitrile, 10.1 g (61.0 mmol) of triethyl phosphite was added, and the mixture was stirred for 12 hours in an oil bath at 120° C. Then, the solvent phenylacetonitrile and unreacted triethyl phosphite were removed by distillation under reduced pressure.

[0273] The resulting liquid was passed through a silica gel column for separation and purification to obtain diethyl 8-(p-styryl)-1-octanephosphonate. The developing solvents used were n-hexane and chloroform.

[0274] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. In Figure 1, the dashed line indicates the diethyl 8-(p-styryl)-1-octanephosphonate. 1 The H-NMR spectrum is shown.

[0275] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a'-f') remained almost unchanged, while the peaks due to the m'' proton of p-(8-bromooctyl)styrene disappeared.

[0276] Furthermore, a new peak derived from the proton (n') of the methylene group next to the oxygen atom of the phosphonate diester appeared at around 4.1 ppm, a peak derived from the proton (o') of the methyl group next to that appeared at 1.3 ppm, and peaks derived from the protons (g'-m') of the methylene group next to the benzyl position to the methylene group next to the phosphorus atom appeared at 1.3-1.8 ppm. The peak integral ratio of f':n':g'-m'+o' was approximately 2:4:20, confirming that 8-(p-styryl)-1-octanephosphonic acid diethyl ester had been obtained.

[0277] The peak at 7.27 ppm is a peak derived from chloroform, and the peak at around 0.9 ppm is a peak derived from n-hexane.

[0278] The liquid obtained after purification was dissolved in deuterated chloroform.13 C-NMR measurements were also carried out. In Figure 2, the dashed line indicates 8-(p-styryl)-1-octanephosphonic acid diethyl ester. 13 The C-NMR spectrum is shown.

[0279] The chemical shifts of the vinyl group and the carbon atoms (a' to f') of the benzene ring were almost unchanged, while the peaks derived from the carbon atoms of the methylene group (g' to n') shifted in the range of 22 to 36 ppm.

[0280] Furthermore, a new peak appeared at around 61 ppm, which was attributable to the carbon (o') of the methylene group next to the oxygen atom of the phosphonate diester unit, and a new peak appeared at around 17 ppm, which was attributable to the proton (p') of the methyl group next to that, confirming that 8-(p-styryl)-1-octanephosphonic acid diethyl ester was obtained.

[0281] The peak near 77 ppm is due to chloroform, and the peak near 14 ppm is due to n-hexane.

[0282] The liquid obtained after purification was dissolved in deuterated chloroform and analyzed using an 85% aqueous phosphoric acid solution as an external standard. 31 P-NMR measurement was performed. In Figure 3, the dashed line indicates the diethyl 8-(p-styryl)-1-octanephosphonate. 31 The P-NMR spectrum is shown.

[0283] The presence of a peak at around 33 ppm, which is attributable to the phosphorus atom (a') of the phosphonate diester, suggests the presence of the target phosphorus compound.These NMR measurement results confirmed that 8-(p-styryl)-1-octanephosphonic acid diethyl ester was obtained.

[0284] (Step 1-3) In the literature (Tetrahedron 2009, 65, 7498-7503 and Polym. Int. 2013, 62, 1717-1728), a compound having an alkylene monophosphonic acid diester structure was reacted with lithium diisopropylamide, and then further reacted with diethyl chlorophosphate to synthesize a compound having an alkylene diphosphonic acid tetraester structure. Based on this reaction, 8-(p-styryl)-1,1-octanediphosphonic acid tetraethyl ester was synthesized.

[0285] Specifically, under an argon atmosphere, 6.15 g (17.4 mmol) of diethyl 8-(p-styryl)-1-octanephosphonate was dissolved in 38 mL of dehydrated THF and cooled to -78 °C. To this was added 19.5 mL (39.0 mmol) of a THF / heptane / ethylbenzene solution of lithium diisopropylamide (LDA) (2 mol / L). 3.8 mL (4.5 g, 26 mmol) of diethyl chlorophosphate was added and stirred overnight at room temperature. The reaction was then quenched by adding purified water, synthesizing tetraethyl 8-(p-styryl)-1,1-octanediphosphonate.

[0286] The volatile solvent was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. Furthermore, unreacted diethyl chlorophosphate and by-products were removed by vacuum distillation.

[0287] The resulting liquid was separated and purified by passing it through a silica gel column and an alumina column, to obtain tetraethyl 8-(p-styryl)-1,1-octanediphosphonate.

[0288] The developing solvents used were ethyl acetate, methanol, and chloroform.

[0289] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. In Figure 1, the solid line indicates the tetraethyl 8-(p-styryl)-1,1-octanediphosphonate. 1The H-NMR spectrum is shown.

[0290] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a–f) remained almost unchanged, while a new peak for the methine group protons (m) next to the two phosphorus atoms appeared at 2.3 ppm.

[0291] In addition, a peak derived from the proton (n) of the methylene group next to the oxygen atom of the two phosphonate diester units was observed at 4.2 ppm, a peak derived from the proton (o) of the methyl group next to that was observed around 1.3 ppm, and peaks derived from the protons (g-l) of the methylene group two positions away from the benzylic methylene group to the phosphorus atom were observed between 1.3 and 1.9 ppm. The peak integral ratio of f:m:n:g-l+o was approximately 2:1:8:26, confirming that tetraethyl 8-(p-styryl)-1,1-octanediphosphonate was obtained.

[0292] The peak at 7.27 ppm is a peak derived from chloroform.

[0293] The liquid obtained after purification was dissolved in deuterated chloroform. 13 C-NMR measurements were also carried out. In Figure 2, the solid line indicates the tetraethyl 8-(p-styryl)-1,1-octanediphosphonate. 13 The C-NMR spectrum is shown.

[0294] The chemical shifts of the vinyl group and the carbon atoms (a-f) of the benzene ring were almost unchanged. Meanwhile, the peaks derived from the carbon atoms of the methylene groups (g-m) shifted in the range of 22-35 ppm, and a new peak derived from the carbon atoms of the methine groups adjacent to the two phosphorus atoms appeared near 38 ppm. Furthermore, the peak derived from the carbon atom (o) of the methylene group next to the oxygen atom of the phosphonate diester shifted slightly to near 62 ppm, confirming the formation of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate. The peak near 77 ppm is derived from chloroform.

[0295] The liquid obtained after purification was dissolved in deuterated chloroform and analyzed using an 85% aqueous phosphoric acid solution as an external standard. 31 P-NMR measurements were performed. 31 The P-NMR spectrum is shown.

[0296] The peak of the phosphorus atom (a') of the phosphonate diester disappeared, and a peak at around 25 ppm due to the phosphorus atom (a) of the diphosphonate tetraester unit was observed, suggesting the presence of the target phosphorus compound.These NMR measurement results confirmed that tetraethyl 8-(p-styryl)-1,1-octanediphosphonate was obtained.

[0297] (Second step) 3.02 g (6.18 mmol) of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate obtained in the first step was weighed out. 149 μL (2.0 μmol) of a diethylbenzene solution of a reversible addition-fragmentation chain transfer (RAFT) agent (5.0 mg / mL) and 18 μL (1.1 μmol) of azobisisobutyronitrile (AIBN) (10 mg / mL) were added, respectively, and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0298] The RAFT agent used was 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid (DDMAT).

[0299] Nitrogen gas was bubbled through the mixture for 30 minutes, and polymerization was carried out at atmospheric pressure in an oil bath at 120°C while stirring at 500 rpm. After about 4.5 hours, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0300] The reaction solution was dissolved in approximately 10 mL of THF and added dropwise to approximately 100 mL of n-hexane to precipitate an oily polymer (crude poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate)). The resulting polymer was separated by decantation and thoroughly dried under vacuum. It was then dissolved again in THF and added dropwise to n-hexane to precipitate the polymer. Unreacted monomers and low-molecular-weight oligomers were removed, and purified poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) was obtained.

[0301] Using deuterated chloroform, 1 H-NMR measurement was performed. Figure 4 shows the structure of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate). 1 The H-NMR spectrum is shown by the dashed line.

[0302] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the c' to n' protons were observed at positions almost identical to the chemical shifts in the monomer, which suggests that a polymer was obtained.

[0303] Poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) was dissolved in THF to prepare a solution of approximately 0.1% by mass, and the molecular weight distribution (Mw / Mn) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC).

[0304] The GPC chromatogram of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) is shown in Figure 5. The Mw / Mn and Mn determined by molecular weight calibration using standard polystyrene were 2.03 and 250kJ, respectively.

[0305] The eluent used was a solvent mainly composed of THF, the flow rate was 1 mL / min, the temperature was 40°C, and the measurement was carried out using two connected TSKgel columns GMHHR-M manufactured by Tosoh Corporation.

[0306] (Third step) In the literature (Macromolecules, 2018, 51, 1120-1128.), poly(diethyl p-styrenephosphonate) was reacted with bromotrimethylsilane, then reacted with methanol solvent and dialyzed to deprotect the alkyl groups of poly(diethyl p-styrenephosphonate), synthesizing poly(p-styrenephosphonic acid) without an alkylene spacer.

[0307] Based on this reaction, the poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) obtained in the second step was reacted with bromotrimethylsilane, then with methanol, and the mixture was dialyzed against water to carry out the deprotection reaction.

[0308] Specifically, 1.13 g (2.31 mmol in monomer units) of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) was dissolved in 5.0 mL of chloroform, 3.5 g (2.3 mol) of bromotrimethylsilane was added, and the mixture was immersed in an oil bath at 40°C and stirred overnight. This solution was concentrated by rotary evaporation and then reacted and dissolved in an excess amount of methanol. The resulting mixture was transferred to a cellulose dialysis tube and dialyzed against pure water to purify the polymer. Finally, the water was evaporated to obtain sodPA.

[0309] sodPA was dissolved in deuterated methanol. 1 H-NMR measurements were performed. In Figure 4, the solid line indicates the 1 The H-NMR spectrum is shown.

[0310] The peak at about 4.2 ppm, which is attributable to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester, almost disappeared, confirming that deprotection had proceeded to 99%.

[0311] The sharp peak near 3.3 ppm is a peak derived from methanol, and the peak near 4.8 ppm is a peak derived from residual water in the polymer.

[0312] (Fourth step) 50 mg of sodPA was dissolved in approximately 5 g of a mixed solvent of methanol and alkaline water (pH ~ 12). The resulting solution was transferred to a polypropylene container and left to stand overnight at 60 °C to evaporate the solvent, preparing a cast membrane.

[0313] The obtained cast membrane was immersed in acidic water (pH 1 or more) at 60° C. for 1 hour, and further immersed in pure water at 60° C. for 1 hour. Thereafter, the obtained membrane was heat-pressed at 120° C. for 1 minute to prepare the proton-conductive electrolyte membrane of Example 1.

[0314] <Evaluation> (AC impedance measurement) Using platinum mesh with a thickness of about 0.1 mm as an electrode, AC impedance measurements were carried out on the sample of the proton-conductive electrolyte membrane of Example 1.

[0315] A sample of the proton-conductive electrolyte membrane of Example 1 cut into a strip (thickness: 0.21 mm, width: 0.30 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.22 cm to prepare a measurement cell.

[0316] The measurement cell was placed in a small environmental test chamber (SH-242, manufactured by Espec Corporation) and the temperature was 100°C, the relative humidity was 80% RH (the partial pressure of water vapor p H2O = 818 hPa), and a voltage of 50 mV and a frequency of 7 × 10 were used with a potentio / galvanostat VSP-300 (BioLogic Science Instruments). 6 The AC impedance was measured by changing the frequency in the range of 1 Hz to 1 Hz. The resistance value at the minimum point of the Nyquist plot was read as 4.3 x 10 3 It was Omega.

[0317] The proton conductivity of this proton-conductive electrolyte membrane sample was calculated using the following formula (1) and was found to be 98 mS / cm (Table 1).

[0318] Proton conductivity = electrode distance / (membrane thickness x electrode width x resistance at the minimum point of the Nyquist plot) (1)

[0319] Relative humidity is set to 60%RH (p H2O =613hPa), 40%RH(p H2O =408hPa), 20%RH(p H2O = 204 hPa), and AC impedance measurements were performed. The relative humidity dependence of conductivity at 80°C and 120°C was also measured in the same manner. The membrane of Example 1 exhibited a proton conductivity of 18 mS / cm at 120°C and 30% RH, and 10 mS / cm at 120°C and 20% RH, for example. The conductivity measurement results are summarized in Table 1. In Figures 6 and 7, the conductivities at 100°C and 120°C are represented by filled circles (●), respectively.

[0320] (Water resistance evaluation) The weight of the proton-conductive electrolyte membrane of Example 1 was measured before and after immersion in water at 60°C for 3 hours. The water resistance was evaluated by calculating the weight residual rate (= weight after water immersion / weight before water immersion). The proton-conductive electrolyte membrane of Example 1 had a weight residual rate of 99% or more when immersed in water at 60°C for 3 hours, and the polymer was hardly dissolved in liquid water, demonstrating high water resistance.

[0321] (Durability evaluation by Fenton test) 2 ppm of iron (II) sulfate was dissolved in 3.5% hydrogen peroxide solution, and the proton-conductive electrolyte membrane of Example 1 was immersed in the solution and allowed to stand at 80°C for 1 hour. The weight was measured before and after the Fenton test, and durability was evaluated by calculating the weight retention rate (= weight after Fenton test / weight before Fenton test). The weight retention rate of the proton-conductive electrolyte membrane of Example 1 according to the Fenton test was 97%, indicating high durability.

[0322] <Comparative Example 1> In Comparative Example 1, diethyl 8-(p-styryl)-1-octanephosphonate obtained in step 1-2 of Example 1 was used, and the monomer was polymerized and the alkyl protecting group was deprotected in the same manner as in step 2 and step 3 of Example 1, to synthesize poly(8-(p-styryl)-1-octanephosphonic acid) (hereinafter also referred to as "soPA"), a polymer having one phosphonic acid group per spacer via an alkylene spacer.

[0323] This soPA was made into a membrane in the same manner as in the fourth step of Example 1, to prepare a proton-conductive electrolyte membrane of Comparative Example 1 (hereinafter also referred to as "soPA-1 membrane").

[0324] The proton conductivity of the proton-conducting electrolyte membrane of Comparative Example 1 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Comparative Example 1 at 100°C and 120°C are represented by black triangles (▲) in Figures 6 and 7 and Table 1. The membrane of Comparative Example 1 exhibited proton conductivities of, for example, 15 mS / cm at 100°C and 80% RH, 3.8 mS / cm at 120°C and 30% RH, and 2.8 mS / cm at 120°C and 20% RH, and the sodPA membrane of Example 1 exhibited conductivity about 4 to 6 times higher.

[0325] The sodPA membrane of Example 1 has two phosphonic acid groups per monomer via a spacer, resulting in a phosphonic acid group density of 5.3 mmol / g. The soPA-1 membrane of Comparative Example 1 has only one phosphonic acid group per monomer via a spacer, resulting in a phosphonic acid group density of 3.4 mmol / g. The sodPA membrane of Example 1 has a higher acid group density than the soPA-1 membrane of Comparative Example 1, which is thought to be why the sodPA membrane of Example 1 exhibited a higher conductivity.

[0326] The water resistance of the proton-conductive electrolyte membrane of Comparative Example 1 was evaluated in the same manner as in Example 1. The weight residual rate after immersion in water at 60°C for 3 hours was 99% or more, and the polymer was hardly dissolved in liquid water, demonstrating high water resistance.

[0327] When the Fenton test was carried out on the proton-conductive electrolyte of Comparative Example 1 in the same manner as in Example 1, the weight retention rate was 99% or more, indicating high durability.

[0328] <Comparative Example 2> In Comparative Example 2, poly(p-styrenephosphonic acid) (hereinafter also referred to as "sPA") having no alkyl spacer was synthesized, and AC impedance measurement was carried out in the same manner as in Example 1 to measure its proton conductivity.

[0329] In the literature (Org. Lett. 2011, 13(8), 2110-2113.), p-Styrylboronic acid was reacted with diethyl phosphite in the presence of 1,10-phenanthroline and copper(I) oxide as a catalyst to synthesize diethyl p-styrenephosphonate. Based on this reaction, we synthesized diethyl p-styrenephosphonate monomer.

[0330] The monomer was purified by passing through basic alumina. 10 g (0.042 mol), 5.8 mg (0.016 mmol), and 2.6 mg (0.016 mmol) of the purified 4-styrenephosphonic acid diethyl monomer, DDMAT, and AIBN were weighed out and mixed in a round-bottom flask equipped with a stopcock to prepare a solution. Nitrogen gas was bubbled through the solution for 20 minutes, and polymerization was carried out at 85 °C and 500 rpm in an oil bath under atmospheric pressure while stirring. After 1 hour, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0331] Approximately 20 mL of THF was added to the reaction solution to prepare an approximately 8% by mass polymer solution. This polymer solution was added dropwise to approximately 300 mL of n-hexane to precipitate a powdery polymer (crude poly(diethyl p-styrenephosphonate)). The resulting polymer was separated by suction filtration and thoroughly dried under vacuum. It was then dissolved again in THF and added dropwise to n-hexane to precipitate the polymer. This polymer precipitation process was repeated three times to remove unreacted monomers and low-molecular-weight oligomers, yielding purified poly(diethyl p-styrenephosphonate).

[0332] In the same manner as in Example 1, GPC measurement of poly(diethyl p-styrenephosphonate) was carried out, and the molecular weight was calibrated using standard polystyrene. The Mw / Mn and Mn of poly(diethyl p-styrenephosphonate) were found to be 1.39 and 280kJ, respectively.

[0333] In the same manner as in the third step of Example 1, a deprotection reaction of poly(diethyl p-styrenephosphonate) was carried out to obtain sPA.

[0334] Since sPA dissolves in both acidic and alkaline aqueous solutions, 40 mg of sPA was dissolved in 0.8 g of a mixed solution of 1-propanol / acidic aqueous solution (pH 1) = 4 / 6 (weight ratio). The resulting solution was transferred to a polypropylene container and left to stand at 60°C for one day to evaporate the solvent, preparing a cast membrane. The resulting membrane was then heat-pressed at 120°C for one minute to prepare the proton-conducting electrolyte membrane of Comparative Example 2.

[0335] The proton conductivity of the proton-conducting electrolyte membrane of Comparative Example 2 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Comparative Example 2 at 100°C and 120°C are summarized in Figures 6 and 7 and Table 1, and are represented by black squares (■), respectively.

[0336] The membrane of Comparative Example 2 exhibited proton conductivities of, for example, 5.8 mS / cm at 100°C and 80% RH, 0.082 mS / cm at 120°C and 30% RH, and 0.027 mS / cm at 120°C and 20% RH. Although the phosphonic acid group densities were similar (phosphonic acid group density of sodPA: 5.3 mmol / g, phosphonic acid group density of sPA: 5.4 mmol / g), the sodPA membrane of Example 1 exhibited a conductivity two to three orders of magnitude higher.

[0337] Under highly humidified conditions where a large amount of water molecules are present, it is thought that in both the sodPA membrane of Example 1 and the sPA membrane of Comparative Example 2, water molecules receive protons from phosphonic acid groups, and proton conduction occurs due to proton hopping between water molecules and the movement of water molecules that have received protons.

[0338] On the other hand, when the humidity decreases and the number of water molecules decreases, proton transport by the Grothus and vehicle mechanisms that depend on water molecules becomes difficult to occur, and proton transfer between phosphonic acid groups (Grotus mechanism between phosphonic acid groups) and proton transfer accompanying the movement of the phosphonic acid groups themselves (phosphonic acid group vehicle mechanism) must be relied upon.

[0339] However, in the sPA membrane of Comparative Example 2, the phosphonic acid groups are directly linked to the polystyrene main chain, so the degree of freedom for movement of the phosphonic acid groups is low, and therefore proton exchange between phosphonic acid groups is thought to be difficult to occur.

[0340] On the other hand, in the sodPA membrane of Example 1, the phosphonic acid groups are connected via alkylene spacers, so the degree of freedom of movement of the phosphonic acid groups is much higher than in the sPA membrane, and since there are two phosphonic acid groups per monomer, it is thought that proton transfer (proton hopping) between phosphonic acid groups is also likely to occur.

[0341] It is believed that due to such a proton conduction mechanism, the sodPA membrane of Example 1 exhibited higher conductivity than the sPA membrane, especially in the low humidity range, despite having the same level of acid group density as the sPA membrane.

[0342] As in Example 1, the proton-conductive electrolyte membrane of Comparative Example 2 was immersed in water at 60°C for 3 hours, and the sPA gradually dissolved in the liquid water. It eventually dissolved completely to form a homogeneous (transparent) solution, and it was found that, unlike the proton-conductive electrolyte membrane of Example 1, it had almost no water resistance.

[0343] Since phosphonic acid groups are easily ionized into phosphonate anions and protons and exhibit ionic properties, it is believed that phase separation occurred between the hydrophobic portion consisting of the polystyrene main chain and alkylene spacer and the hydrophilic, ionic phosphonic acid groups within the monomer unit in the sodPA membrane of Example 1. As a result, it is believed that the polymer as a whole was difficult to hydrate, and the sodPA membrane did not dissolve even when immersed in water.

[0344] On the other hand, the sPA of Comparative Example 2 has hydrophilic and ionic phosphonic acid groups directly attached to the polystyrene main chain.

[0345] It is generally known that diblock polymers of equal composition form nanophase-separated structures (also called microphase-separated structures) when χN is 10.5 or greater (χ: interaction parameter between blocks, N: overall degree of polymerization of the block polymer). It is believed that phase separation also occurs between the hydrophobic portion of the monomer unit and the hydrophilic, ionic phosphonic acid group when χN exceeds the critical value of 10.5, just as in diblock copolymers. (Macromolecules 1980, 13, 1602-1617.)

[0346] However, since the sPA of Comparative Example 2 does not have an alkylene spacer like the sodPA, the value corresponding to N is small and χN does not exceed the critical value of 10.5. Therefore, it is thought that a phase separation structure was not formed, resulting in a membrane that is easily dissolved in water.

[0347] <Example 2> In Example 2, according to the following scheme 3, tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was synthesized as a monomer having two phosphonate esters per alkylene spacer using p-(8-bromooctyl)styrene synthesized in step 1-1 of Example 1 (first step).

[0348] [ka]

[0349] Subsequently, this monomer was polymerized according to the following scheme 4 (second step).

[0350] [ka]

[0351] The alkyl protecting groups of the obtained poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) were deprotected to synthesize poly(9-(p-styryl)-1,1-nonanediphosphonic acid) (hereinafter also referred to as "sndPA"), a polymer having two phosphonic acid groups per spacer via an alkylene spacer (third step).

[0352] This sndPA was formed into a membrane to produce the proton-conductive electrolyte membrane of Example 2 (fourth step).

[0353] (First step) In a paper (J. Org. Chem. 2011, 76, 8807-8813), a compound with a bromoalkyl structure was reacted with sodium hydride, and then further reacted with methylene diphosphonic acid tetraester to synthesize a compound with an alkylene diphosphonic acid tetraester. Using this reaction as a reference, we synthesized tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate.

[0354] Specifically, 1.50 g (37.5 mmol) of sodium hydride (concentration 60 wt%) dispersed in liquid paraffin was dissolved in 30 mL of dehydrated THF under a nitrogen atmosphere, and 11.7 g (33.9 mmol) of tetraisopropyl methylenediphosphonate was added. Then, 12.0 g (34.1 mmol) of p-(8-bromooctyl)styrene obtained in step 1-1 of Example 1 was added and stirred. Then, a saturated aqueous ammonium chloride solution was added to terminate the reaction.

[0355] Next, the volatile solvent was evaporated by rotary evaporation, followed by extraction by liquid separation, and the solvent used in the liquid separation was removed again by rotary evaporation. The resulting liquid was separated and purified by passing it through a silica gel column to obtain tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. The developing solvents used were n-hexane, isopropanol, and chloroform.

[0356] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. Figure 8 shows the tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate. 1 The H-NMR spectrum is shown.

[0357] p-(8-bromooctyl)styrene shown in Figure 1 1 Compared with the H-NMR spectrum, the chemical shifts of the vinyl group, benzene ring, and benzyl protons (a–f) were almost unchanged, whereas the peaks due to the m″ proton of p-(8-bromooctyl)styrene disappeared.

[0358] Furthermore, a new peak due to the protons (o) of the methine groups next to the oxygen atoms of the two phosphonate diester units appeared at around 4.8 ppm, a new peak due to the protons (p) of the methyl groups next to those appeared at around 1.3 ppm, and a new peak due to the methine group protons (n) next to the two phosphorus atoms appeared at 2.1 ppm.

[0359] In addition, peaks from the methylene group next to the benzyl position to the methylene group two adjacent to the phosphorus atom (g-m) were observed between 1.3 and 1.9 ppm. The peak integral ratio of f:n:o:g-m+p was approximately 2:1:4:38, confirming that tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was obtained.

[0360] The peak at 7.27 ppm is a peak derived from chloroform.

[0361] The liquid obtained after purification was dissolved in deuterated chloroform. 13 C-NMR measurements were also carried out. Figure 9 shows the tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate 13 The C-NMR spectrum is shown.

[0362] p-(8-bromooctyl)styrene shown in Figure 2 13Compared with the C-NMR spectrum, the chemical shifts of the vinyl group and benzene ring carbons (a–f) were almost unchanged. On the other hand, the peaks derived from the methylene group carbons (g–n) shifted in the range of 24–38 ppm, and a new peak derived from the methine group carbons adjacent to the two phosphorus atoms appeared around 39 ppm.

[0363] Furthermore, a peak derived from the carbon (p) of the methine group next to the oxygen atom of the phosphonate diester unit newly appeared around 71 ppm, confirming that tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate had been obtained.

[0364] The peak near 77 ppm is a peak derived from chloroform.

[0365] The liquid obtained after purification was dissolved in deuterated chloroform and analyzed using an 85% aqueous phosphoric acid solution as an external standard. 31 P-NMR measurement was performed. Figure 10 shows the tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate 31 The P-NMR spectrum is shown.

[0366] Since only the peaks around 23 ppm attributable to the phosphorus atoms of the two phosphonate diester units were observed, it is believed that no phosphorus compounds other than the target phosphonate diester were present.These NMR measurement results confirmed that tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate was obtained.

[0367] (Second step) 1.9 mg (5.22 μmol) of DDAMT and 5.62 g (15.7 mmol) of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate obtained in the first step were weighed out, respectively, and 11.7 μL (0.56 μmol) of a diethylbenzene solution of AIBN (concentration: 7.3 mg / mL) was added and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0368] Nitrogen gas was then bubbled through the mixture for 25 minutes, and polymerization was carried out at atmospheric pressure using an oil bath at 120°C while stirring at 500 rpm. After 12 hours, the polymerization reaction was completely stopped by immersing the flask in liquid nitrogen.

[0369] The above reaction solution was dissolved in approximately 3 mL of THF and added dropwise to approximately 500 mL of n-hexane to precipitate an oily polymer (crude poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)). The resulting polymer was separated by decantation and thoroughly dried under vacuum. It was then dissolved again in THF and added dropwise to n-hexane to precipitate the polymer. Unreacted monomers and low-molecular-weight oligomers were removed, and purified poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) was obtained.

[0370] Using deuterated chloroform, 1 H-NMR measurement was carried out. In FIG. 11, the broken line indicates the 1 The H-NMR spectrum is shown.

[0371] The peaks derived from the vinyl group protons disappeared, and a broad signal derived from the c' to o' protons was observed at a position similar to the chemical shift of the monomer, which suggests that a polymer was obtained.

[0372] GPC measurement of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) was carried out in the same manner as in Example 1. The GPC chromatogram of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) is shown in FIG. 12. When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) were found to be 2.50 and 117 kJ, respectively.

[0373] (Third step) In the same manner as in the third step of Example 1, the poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) obtained in the second step was reacted with bromotrimethylsilane, then with methanol, and dialyzed against water to carry out a deprotection reaction.

[0374] Specifically, 1.46 g (4.07 mmol in monomer units) of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate) was dissolved in 10 mL of chloroform, 6.23 g (40.7 mmol) of bromotrimethylsilane was added, and the mixture was placed in an oil bath at 40°C and stirred overnight.

[0375] The solution was concentrated by rotary evaporation and then dissolved in excess methanol. The resulting mixture was transferred to a cellulose dialysis tube and dialyzed against pure water to purify the polymer. Finally, the water was evaporated to obtain sndPA.

[0376] sndPA was dissolved in deuterated methanol. 1 H-NMR measurements were performed. In Figure 11, the solid line indicates the 1 The H-NMR spectrum is shown.

[0377] The integral ratio of the signals (c, d) at 5.5 to 7.5 ppm derived from the benzene ring protons to the signals (a, b, e-m) at 0.5 to 2.8 ppm derived from other protons was approximately 4:21, which confirmed that the peak (o') derived from the methyl group protons of the two phosphonate diester units had almost disappeared, and that deprotection had progressed by 95% or more.

[0378] The sharp peak near 3.3 ppm is a peak derived from methanol, the peak near 4.8 ppm is a peak derived from residual water in the polymer, the peaks near 1.8 and 3.7 ppm are a peak derived from THF, the peaks near 0.9 and 1.3 ppm are a peak derived from n-hexane, and the peak near 2.3 ppm is a peak derived from by-products and impurities of the deprotection reaction.

[0379] (Fourth step) In the same manner as in the fourth step of Example 1, the proton-conductive electrolyte membrane of Example 3 was prepared by solution casting and heat pressing.

[0380] The proton conductivity of the proton-conductive electrolyte membrane of Example 2 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 2 are summarized in Table 1. The membrane of Example 2 exhibited a proton conductivity of 15 mS / cm at 120°C and 40% RH and 7.3 mS / cm at 120°C and 20% RH, for example, and exhibited a higher conductivity than the proton-conductive electrolyte membranes of Comparative Examples 1 and 2.

[0381] The sndPA membrane of Example 2 has two phosphonic acid groups per monomer via a spacer, resulting in a phosphonic acid group density of 5.1 mmol / g. The soPA membrane of Comparative Example 1 has only one phosphonic acid group per monomer via a spacer, resulting in a phosphonic acid group density of 3.4 mmol / g. The sndPA membrane of Example 2 has a higher acid group density than the soPA membrane of Comparative Example 1, which is thought to be why the sndPA membrane of Example 2 exhibited higher conductivity.

[0382] Under highly humidified conditions where a large amount of water molecules are present, it is thought that in both the sndPA membrane of Example 2 and the sPA membrane of Comparative Example 2, water molecules receive protons from phosphonic acid groups, and proton conduction occurs through proton hopping between water molecules and the movement of water molecules that have received protons.

[0383] On the other hand, when the humidity decreases and the number of water molecules decreases, proton transport by the Grothus and vehicle mechanisms that depend on water molecules becomes difficult to occur, and proton transfer between phosphonic acid groups (Grotus mechanism between phosphonic acid groups) and proton transfer accompanying the movement of the phosphonic acid groups themselves (phosphonic acid group vehicle mechanism) must be relied upon.

[0384] However, in the sPA membrane of Comparative Example 2, the phosphonic acid groups are directly linked to the polystyrene main chain, so the degree of freedom for movement of the phosphonic acid groups is low, and therefore proton exchange between phosphonic acid groups is unlikely to occur.

[0385] On the other hand, in the sndPA membrane of Example 2, the phosphonic acid groups are connected via an alkylene spacer, so the degree of freedom of movement of the phosphonic acid groups is much higher than in the sPA membrane, and since there are two phosphonic acid groups per monomer, it is thought that proton exchange (proton hopping) between phosphonic acid groups is also more likely to occur.

[0386] It is believed that due to such a proton conduction mechanism, the sndPA membrane of Example 2 exhibited higher conductivity than the sPA membrane, especially in the low humidity range, despite having a slightly lower acid group density than the sPA membrane (phosphonic acid group density of sndPA: 5.1 mmol / g, phosphonic acid group density of sPA: 5.4 mmol / g).

[0387] Example 3 In Example 3, tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was synthesized as a monomer having two phosphonate ester units per alkylene spacer via an alkylene spacer according to the following Scheme 5 (first step).

[0388] [ka]

[0389] Subsequently, this monomer was polymerized according to the following scheme 6 (second step).

[0390] [ka]

[0391] The alkyl protecting groups of the obtained poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) were deprotected to synthesize poly(4-(p-styryl)-1,1-butanediphosphonic acid) (hereinafter also referred to as "sbdPA"), a polymer having two phosphonic acid groups per spacer via an alkylene spacer (third step).

[0392] (First step) (Process 1-1) p-(4-Bromobutyl)styrene was synthesized in the same manner as in step 1-1 of Example 1, except that 1,4-dibromobutane was used instead of 1,8-dibromooctane.

[0393] The purified liquid was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. In Figure 13, the dotted line indicates the structure of p-(4-bromobutyl)styrene. 1 The H-NMR spectrum is shown.

[0394] of the precursor 4-bromostyrene 1 Compared with the H-NMR spectrum (chain line in Figure 1), the chemical shifts of the protons (a'', b'', c'') on the vinyl group were almost unchanged, while the peaks derived from the protons (d'' and e'') on the benzene ring shifted to around 7.1 and 7.3 ppm.

[0395] Furthermore, the peak of the methylene group proton (f'') adjacent to the benzene ring was observed at 2.6 ppm, the peak of the methylene group proton (i'') with a bromo group was observed at 3.4 ppm, and the peaks of the methylene group protons (g'' and l'') between them were observed at 1.8 and 1.9 ppm. The integral ratio of each peak was approximately 1:1:1:1, which suggests that p-(4-bromobutyl)styrene was obtained.

[0396] The peak at 7.27 ppm is a peak derived from chloroform.

[0397] The purified liquid was dissolved in deuterated chloroform. 13C-NMR measurements were also carried out. In Figure 14, the dotted line indicates the 13 The C-NMR spectrum is shown.

[0398] of the precursor p-bromostyrene 13 Compared with the C-NMR spectrum (dashed line in Figure 1), 13 In the C-NMR spectrum, the chemical shifts of the protons (a'', b'', c'') attached to the vinyl group shifted to around 113, 137, and 135 ppm, respectively, and the peaks due to the protons (d'', e'', f'') attached to the benzene ring shifted to around 129, 126, and 143 ppm, respectively. This change in chemical shift is thought to be due to the loss of the bromo group attached to the benzene ring.

[0399] Furthermore, peaks attributable to the carbon atoms (g'', h'', i'', j'') of the methylene group were newly observed at 30-35 ppm, suggesting that p-(4-bromobutyl)styrene was obtained.

[0400] The peak near 77 ppm is a peak derived from chloroform.

[0401] (Step 1-2) Diethyl 4-(p-styryl)-1-butanephosphonate was synthesized in the same manner as in Step 1-2 of Example 1, except that p-(4-bromobutyl)styrene was used instead of p-(8-bromooctyl)styrene.

[0402] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. In FIG. 13, the dashed line indicates the 1 The H-NMR spectrum is shown.

[0403] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a'-f') remained almost unchanged, while the peak at i'' of p-(4-bromobutyl)styrene disappeared.

[0404] Furthermore, a new peak derived from the proton (n') of the methylene group next to the oxygen atom of the phosphonate diester unit appeared at around 4.1 ppm, a peak derived from the proton (o') of the methyl group next to that appeared at 1.3 ppm, and peaks derived from the protons (g'-m') of the methylene groups next to the benzyl position to the phosphorus atom appeared at 1.3-1.8 ppm. The peak integral ratio of f':n':g'-m'+o' was approximately 2:4:20, confirming that 8-(p-styryl)-1-octanephosphonic acid diethyl ester had been obtained.

[0405] The peak at 7.27 ppm is a peak derived from chloroform, and the peak at around 0.9 ppm is a peak derived from n-hexane.

[0406] Furthermore, a new peak derived from the proton (j') of the methylene group next to the oxygen atom of the phosphonate diester appeared at around 4.1 ppm, and a peak derived from the proton (k') of the methyl group next to that appeared at around 1.3 ppm. Peaks derived from the proton (g') attached to the methylene group next to the benzyl position, the proton (h') of the adjacent methylene group, and the proton (i') of the methylene group next to the phosphorus atom were observed at 1.6 to 1.8 ppm, and the peak integral ratio of f':g'-i':j':k' was approximately 2:6:4:6, confirming that 4-(p-styryl)-1-butanephosphonic acid diethyl ester had been obtained.

[0407] The peak at 7.27 ppm is a peak derived from chloroform.

[0408] The liquid obtained after purification was dissolved in deuterated chloroform. 13 C-NMR measurements were also carried out. In Figure 14, the dashed line indicates the 13 The C-NMR spectrum is shown.

[0409] The chemical shifts of the vinyl group and the carbon atoms (a' to f') of the benzene ring were almost unchanged, while the peaks derived from the carbon atoms of the methylene group (g' to j') shifted in the range of 22 to 36 ppm.

[0410] Furthermore, a new peak appeared at around 61 ppm, which was derived from the carbon (k') of the methylene group next to the oxygen atom of the phosphonate diester unit, and a new peak appeared at around 17 ppm, which was derived from the proton (l') of the methyl group next to that, confirming that 4-(p-styryl)-1-butanephosphonic acid diethyl ester was obtained.

[0411] The peak near 77 ppm is a peak derived from chloroform.

[0412] The liquid obtained after purification was dissolved in deuterated chloroform and analyzed using 85% aqueous phosphoric acid solution as an external standard. 31 P-NMR measurement was performed. In Figure 15, the dashed line indicates the 31 The P-NMR spectrum is shown.

[0413] The presence of a peak at around 33 ppm, which is attributable to the phosphorus atom (a') of the phosphonate diester unit, suggests the presence of the target phosphorus compound.These NMR measurement results confirmed that 4-(p-styryl)-1-butanephosphonic acid diethyl ester was obtained.

[0414] (Step 1-3) Tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was synthesized in the same manner as in step 1-3 of Example 1, except that diethyl 4-(p-styryl)-1-butanephosphonate was used instead of diethyl 8-(p-styryl)-1-octanephosphonate.

[0415] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. In FIG. 13, the solid line shows the tetraethyl 4-(p-styryl)-1,1-butanediphosphonate. 1 The H-NMR spectrum is shown.

[0416] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a–f) remained almost unchanged, while a new peak for the methine group proton (i) next to the two phosphorus atoms appeared at 2.3 ppm.

[0417] In addition, a peak due to the proton (j) of the methylene group next to the oxygen atoms of the two phosphonate diester units was observed at 4.2 ppm, a peak due to the proton (k) of the methyl group next to that was observed around 1.3 ppm, and a peak due to the proton (g) of the methylene group next to the benzyl position and the proton (h) of the methylene group two positions away from the phosphorus atom was observed at 1.9 ppm. The peak integral ratio of f:g + h:i:j:k was approximately 2:4:1:8:12, confirming that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was obtained.

[0418] The peak at 7.27 ppm is a peak derived from chloroform.

[0419] The liquid obtained after purification was dissolved in deuterated chloroform. 13 C-NMR measurements were also carried out. In Figure 14, the solid line shows the tetraethyl 4-(p-styryl)-1,1-butanediphosphonate 13 The C-NMR spectrum is shown.

[0420] The chemical shifts of the vinyl group and benzene ring carbons (a–f) were almost unchanged, whereas the peaks derived from the methylene group carbons (g–i) shifted in the range of 25–35 ppm, and a new peak derived from the methine group carbons adjacent to the two phosphorus atoms appeared around 38 ppm.

[0421] Furthermore, the peak derived from the carbon (k) of the methylene group next to the oxygen atom of the phosphonate diester was slightly shifted to around 62 ppm, confirming that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was obtained.

[0422] The peak near 77 ppm is a peak derived from chloroform.

[0423] The liquid obtained after purification was dissolved in deuterated chloroform, and 85% aqueous phosphoric acid solution was used as an external standard. 31 P-NMR measurement was performed. In FIG. 15, the solid line shows the P-NMR of tetraethyl 4-(p-styryl)-1,1-butanediphosphonate. 31 The P-NMR spectrum is shown.

[0424] The peak of the phosphorus atom (a') of the phosphonate diester disappeared, and the peaks around 25 ppm derived from the phosphorus atoms (a) of the two phosphonate diester units were observed, suggesting the presence of the target phosphorus compound.These NMR measurement results confirmed that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was obtained.

[0425] (Second step) Monomers were polymerized in the same manner as in the second step of Example 1, except that tetraethyl 4-(p-styryl)-1,1-butanediphosphonate was used instead of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, to obtain poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate).

[0426] Using deuterated chloroform, 1 H-NMR measurement was performed. Figure 16 shows the structure of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate). 1 The H-NMR spectrum is shown by the dashed line.

[0427] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the protons c' to j' were observed at positions similar to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0428] GPC measurement of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) was carried out in the same manner as in Example 1. FIG. 17 shows the GPC chromatogram of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate). When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) were 1.45 and 27 kJ, respectively.

[0429] (Third step) sbdPA was synthesized by carrying out a deprotection reaction in the same manner as in the third step of Example 1, except that poly(tetraethyl 4-(p-styryl)-1,1-butanediphosphonate) was used instead of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate).

[0430] sbdPA was dissolved in deuterated methanol. 1 H-NMR measurements were performed. In Figure 16, the solid line indicates the 1 The H-NMR spectrum is shown.

[0431] The peak at about 4.1 ppm, which is attributable to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester unit, almost disappeared, confirming that deprotection had proceeded to 99%.

[0432] The sharp peak near 3.3 ppm is a peak derived from methanol, and the peak near 4.8 ppm is a peak derived from residual water in the polymer.

[0433] Example 4 In Example 4, hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate was synthesized as a monomer having three phosphonate ester units per alkylene spacer using tetraethyl 8-(p-styryl)-1,1-octanediphosphonate synthesized in the first step of Example 1, according to the following scheme 7 (first step).

[0434] [ka]

[0435] Subsequently, this monomer was polymerized according to the following scheme 8 (second step).

[0436] [ka]

[0437] By deprotecting the alkyl protecting groups of the obtained poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate), a polymer having three phosphonic acid groups per spacer was obtained via alkylene spacers. Poly(8-(p-styryl)-1,1,1-octanetriphosphonic acid) (hereinafter also referred to as "sotPA") was synthesized (third step).

[0438] This sotPA was formed into a membrane to produce the proton-conductive electrolyte membrane of Example 4 (fourth step).

[0439] (First step) In a paper (J. Org. Chem. 2011, 76, 8807-8813.), a compound with an alkylene diphosphonic acid tetraester structure was reacted with sodium bis(trimethylsilyl)amide, then reacted with diethyl chlorophosphite, and then oxidized with hydrogen peroxide to synthesize a compound with an alkylene triphosphonic acid hexaester structure. Based on this reaction, hexaethyl 8-(p-styryl)-1,1,1-octane triphosphonate was synthesized.

[0440] Specifically, 0.500 g (1.02 mmol) of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate synthesized in the first step of Example 1 was dissolved in 6.5 mL of dehydrated THF under a nitrogen atmosphere and cooled to 0° C. To this was added 0.81 mL (1.54 mmol) of a THF solution of sodium bis(trimethylsilyl)amide (concentration 1.9 mol / L), and the mixture was stirred for 30 minutes.

[0441] To this was added 0.40 mL (0.43 g, 2.8 mmol) of diethyl chlorophosphite and stirred for 30 minutes, and then 2.0 mL (2.3 g, 18 mmol) of hydrogen peroxide solution (concentration 35%) was added and stirred for a further 1.5 hours to synthesize hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate.

[0442] The volatile solvent (THF) was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. Furthermore, unreacted diethyl chlorophosphite and by-products were removed by vacuum distillation.

[0443] The resulting liquid was passed through a silica gel column for separation and purification to obtain hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate. The developing solvents used were ethyl acetate, ethanol, and propanol.

[0444] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. 1 The H-NMR spectrum is shown.

[0445] The chemical shifts of the vinyl group, benzene ring, and benzyl protons (a–f) were almost unchanged, whereas the peak at 2.3 ppm due to the methine group protons adjacent to the two phosphorus atoms, which was observed in tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, disappeared.

[0446] Furthermore, the integral ratio of the peak derived from the proton (f) of the methylene group next to the benzyl position to the peak derived from the proton (m) of the methylene group next to the oxygen atom of the phosphonate diester unit was approximately 2:6, confirming that hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate was obtained.

[0447] The peak at 7.27 ppm is due to chloroform, the peaks at 2.1 and 4.1 ppm are due to ethyl acetate, and the peaks at 0.9 and 3.6 ppm are due to 1-propanol.

[0448] (Second step) Monomers were polymerized in the same manner as in the second step of Example 1, except that hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate was used instead of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, to obtain poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate).

[0449] Using deuterated chloroform, 1 H-NMR measurement was performed. Figure 19 shows the structure of poly(8-(p-styryl)-1,1,1-octanetriphosphonic acid hexaethyl). 1 The H-NMR spectrum is shown by the dashed line.

[0450] The peaks derived from the vinyl group protons disappeared, and broad signals derived from the c' to m' protons were observed at positions similar to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0451] GPC measurement of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) was carried out in the same manner as in Example 1. FIG. 20 shows the GPC chromatogram of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate). When the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) were found to be 1.78 and 28kJ, respectively.

[0452] (Third step) SotPA was synthesized by carrying out a deprotection reaction in the same manner as in the third step of Example 1, except that poly(hexaethyl 8-(p-styryl)-1,1,1-octanetriphosphonate) was used instead of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate).

[0453] sotPA was dissolved in deuterated methanol. 1 H-NMR measurements were performed. In Figure 19, the solid line indicates the 1 The H-NMR spectrum is shown.

[0454] The peak at about 4.1 ppm, which is attributable to the proton of the methylene group adjacent to the oxygen atom of the phosphonate diester, almost disappeared, confirming that deprotection had proceeded to 99%.

[0455] The sharp peak near 3.3 ppm is a peak derived from methanol, and the peak near 4.8 ppm is a peak derived from residual water in the polymer.

[0456] <Example 5> In Example 5, p-(9-(p-styryl)-nonyl)pyridine was synthesized as a monomer having a basic functional group using p-(8-bromooctyl)styrene synthesized in Step 1-1 of Example 1 via an alkylene spacer according to the following Scheme 9 (first step).

[0457] [ka]

[0458] Subsequently, according to the following scheme 10, p-(9-(p-styryl)-nonyl)pyridine and tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate synthesized in the first step of Example 2 were copolymerized (second step).

[0459] [ka]

[0460] The alkyl protecting groups of the obtained poly((9-(p-styryl)-1,1-nonanediphosphonic acid tetraisopropyl)-co-(p-(9-(p-styryl)-nonyl)pyridine)) were deprotected to synthesize poly((9-(p-styryl)-1,1-nonanediphosphonic acid)-co-(p-(9-(p-styryl)-nonyl)pyridine)) (hereinafter also referred to as "sndPA-co-snPy") (third step).

[0461] (First step) In the literature (Macromolecules 2010, 43, 1761-1770.), p-methylpyridine (also known as γ-picoline) was reacted with LDA, and then with p-bromomethylstyrene to synthesize p-(2-(p-styryl)-ethyl)pyridine (also known as (p-pyridylethyl)-p-vinylbenzene). Using this reaction as a reference, 4-(9-(p-styryl)-nonyl)pyridine was synthesized.

[0462] Specifically, 0.931 g (10.0 mmol) of p-methylpyridine was dissolved in 5 mL of dehydrated THF and cooled to -80 °C. 5.0 mL (10 mmol) of a THF / heptane / ethylbenzene solution of LDA (concentration: 2 mol / L) was added and stirred for 1 hour. 2.72 g (9.2 mmol) of p-(8-bromooctyl)styrene was added and stirred for 2 hours, then overnight at room temperature. The reaction was then quenched by adding pure water to synthesize p-(9-(p-styryl)-nonyl)pyridine.

[0463] The volatile solvent was evaporated by rotary evaporation. After extraction by liquid separation, the solvent used in the liquid separation was removed by rotary evaporation. The resulting liquid was separated and purified by passing it through a silica gel column to obtain p-(9-(p-styryl)-nonyl)pyridine.

[0464] The developing solvents used were chloroform and methanol.

[0465] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. Figure 21 shows the NMR spectrum of p-(9-(p-styryl)-nonyl)pyridine. 1 The H-NMR spectrum is shown.

[0466] Compared with the H-NMR spectrum of p-(8-bromooctyl)styrene shown in Figure 1, the chemical shifts of the vinyl group, benzene ring, and protons (a-f) attached to the benzyl position were almost unchanged. On the other hand, the peaks derived from the methylene group attached to the bromo group of p-(8-bromooctyl)styrene and the protons (m'', l'') of the adjacent methylene group disappeared.

[0467] Furthermore, a new peak derived from the proton (p) of the methine group next to the nitrogen atom in the pyridyl group appeared around 8.5 ppm, confirming that p-(9-(p-styryl)-nonyl)pyridine had been obtained.

[0468] The peak at 3.5 ppm is due to methanol, and the peak at 7.27 ppm is due to chloroform.

[0469] The liquid obtained after purification was dissolved in deuterated chloroform. 13 C-NMR measurements were also carried out. Figure 22 shows the structure of p-(9-(p-styryl)-nonyl)pyridine. 13 The C-NMR spectrum is shown.

[0470] 4-(8-bromooctyl)styrene shown in Figure 2 13 Compared with the C-NMR spectrum, the chemical shifts of the vinyl group and benzene ring carbons (a-f) were almost unchanged. On the other hand, the peaks derived from the methylene group carbons g-o shifted in the range of 29-36 ppm, and new peaks derived from the pyridyl group carbons (p, q, r) appeared in the vicinity of 124-152 ppm, confirming that p-(9-(p-styryl)-nonyl)pyridine was obtained.

[0471] The peak near 77 ppm is a peak derived from chloroform.

[0472] (Second step) 1.05 g (1.87 mmol) of p-(9-(p-styryl)-nonyl)pyridine and 0.106 g (0.344 mmol) of tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate obtained in the first step of Example 2 were weighed out, respectively, and 21.4 μL (0.38 μmol) of a diethylbenzene solution of DDAMT (concentration: 2.6 mg / mL) and 133 μL (1.1 μmol) of a diethylbenzene solution of AIBN (concentration: 2.9 mg / mL) were added and mixed in a round-bottom flask equipped with a stopcock to prepare a solution.

[0473] A polymerization reaction was carried out at 120°C in the same manner as in the second step of Example 1, and purification was carried out by a reprecipitation method to obtain purified poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)).

[0474] Using deuterated chloroform, 1 H-NMR measurement was performed. Figure 23 shows the H-NMR spectrum of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)).

[0475] The peaks due to the vinyl group protons disappeared, and broad signals due to the c-o and c'-o' protons were observed at positions almost identical to the chemical shifts in the monomer, suggesting that a polymer was obtained.

[0476] In the same manner as in Example 1, GPC measurement of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)) was carried out.

[0477] Figure 24 shows the GPC chromatogram of poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)). The molecular weight was calibrated using standard polystyrene, and the Mw / Mn and Mn of poly(tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)) were 1.56 and 42kJ, respectively.

[0478] (Third step) sndPA-co-snPy was synthesized by carrying out a deprotection reaction in the same manner as in the third step of Example 1, except that poly((tetraisopropyl 9-(p-styryl)-1,1-nonanediphosphonate)-co-(p-(9-(p-styryl)-nonyl)pyridine)) was used instead of poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate).

[0479] Example 6 In Example 6, 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide was synthesized according to the following Scheme 11 using p-(9-(p-styryl)-nonyl)pyridine synthesized in the first step of Example 5.

[0480] [ka]

[0481] 0.050 g (0.16 mmol) of p-(9-(p-styryl)-nonyl)pyridine and 0.15 g (1.3 mmol) of bromoethane were added and stirred at room temperature for 48 hours. After that, the mixture was dried in vacuo to synthesize 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide.

[0482] The resulting liquid was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. 1 The H-NMR spectrum is shown.

[0483] p-(9-(p-styryl)-nonyl)pyridine shown in Figure 21 1 Compared with the H-NMR spectrum, the chemical shifts of the protons (a to m) attached to the vinyl group, benzene ring, and alkylene group except for those next to the pyridinium group were almost unchanged.

[0484] On the other hand, the methylene group (n) next to the pyridinium group and the protons (o and p) of the pyridinium group appeared at 2.9, 7.8, and 9.3 ppm, respectively, shifted downfield. Furthermore, new peaks due to the protons (q and r) of the ethyl group appeared around 5.0 and 1.7 ppm, confirming that 1-ethyl-4-(9-(p-styryl)-nonyl)pyridinium bromide was obtained.

[0485] The peak at 7.27 ppm is a peak derived from chloroform.

[0486] Example 7 In Example 7, using the diethyl 8-(p-styryl)-1-octanephosphonate obtained in Step 1-2 of Example 1, poly(p-n-octylstyrene)-b-poly(diethyl 8-(p-styryl)-1-octanephosphonate) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(diethyl 8-(p-styryl)-1-octanephosphonate); hereinafter also referred to as "so-soPdE") was synthesized as a block copolymer according to Scheme 12 below (first step).

[0487] [ka]

[0488] Next, the protecting groups of the poly(diethyl 8-(p-styryl)-1-octanephosphonate) block were deprotected to synthesize poly(pn-octylstyrene)-b-poly(8-(p-styryl)-1-octanephosphonic acid) (also called poly(1-(p-styryl)-n-octane)-b-poly(8-(p-styryl)-1-octanephosphonic acid) (hereinafter also referred to as "so-soPA")) having proton-donating groups (second step).

[0489] This so-soPA was formed into a membrane to produce the proton conductive membrane of Example 7 (hereinafter also referred to as "so-soPA-1 membrane") (third step).

[0490] In the term "so-soPA," "so" is an abbreviation for poly(p-n-octylstyrene) (also called poly(1-(p-styryl)-n-octane)), and "so" is a hydrophobic hydrocarbon-based vinyl polymer having a glass transition temperature (Tg) of 30°C or lower, i.e., the "b block" as defined in the present invention.

[0491] In addition, in the term "so-soPA," "soPA" is an abbreviation for poly(8-(p-styryl)-1-octanephosphonic acid), a polymer having a proton-donating group, i.e., the "a block" as referred to in the present disclosure.

[0492] (1-1) First step (Process 1-1) Monomers were polymerized in the same manner as in the second step of Example 1, except that commercially available p-n-octylstyrene was used instead of tetraethyl 8-(p-styryl)-1,1-octanediphosphonate, to synthesize poly(p-n-octylstyrene) (also referred to as poly(1-(p-styryl)-n-octane), hereinafter also referred to as "so").

[0493] Using deuterated chloroform, 1 H-NMR measurement revealed that the number average degree of polymerization was 90 and Mn was estimated to be 19k. 1The H-NMR spectrum is shown.

[0494] GPC measurement of so was carried out in the same manner as in Example 1. The GPC chromatogram of so is shown by the dashed line in Figure 27. When the molecular weight was calibrated using standard polystyrene, the Mw / Mn of so was found to be 1.21.

[0495] (Step 1-2) The so obtained in step 1-1 had a RAFT agent residue introduced at the molecular chain end. The diethyl 8-(p-styryl)-1-octanephosphonate monomer was polymerized in the same manner as in step 1 of Example 1, except that this os was used as a macro RAFT agent (a RAFT agent with a large molecular weight, hence the name "macro RAFT agent"), to obtain an so-soPdE diblock copolymer.

[0496] so-soPdE was dissolved in deuterated chloroform. 1 The number-average degree of polymerization was determined by H-NMR measurement. 1 The H-NMR spectrum shows that the number-average degree of polymerization of the so block was 130, the number-average degree of polymerization of the soPdE block was 1410, and the overall Mn was 516kJ.

[0497] GPC measurement of so-soPdE was carried out in the same manner as in Example 1. The GPC chromatogram of so-soPdE is shown by the solid line in Figure 27. The peak of so-soPdE shifted toward a lower elution time compared to the peak of so, confirming the formation of a block copolymer. The Mw / Mn of so-soPdE was 2.29.

[0498] (1-2) Second step The deprotection reaction of so-soPdE was carried out in the same manner as in the third step of Example 1 to obtain a so-soPA diblock copolymer.

[0499] so-soPA was dissolved in a mixed solvent of deuterated chloroform and deuterated methanol. 1 H-NMR measurements were performed. In Figure 26, the solid line indicates the 1The H-NMR spectrum shows that the signal at around δ = 4.0, which is assigned to the ester of the soPdE block, has disappeared, confirming that the deprotection reaction has progressed to 99% or more.

[0500] The peaks around 3.4 and 7.2 ppm are due to methanol and chloroform, and the peak around 4.9 ppm is due to residual water in the polymer.

[0501] (1-3) Third step A so-soPA-1 membrane was prepared in the same manner as in the fourth step of Example 1, except that a mixed solvent of 1-propanol and acidic water (pH 1 or less) was used as the solvent.

[0502] Example 8 In Example 8, the same procedure as in Example 7 was used to prepare a block copolymer, poly(p-n-octylstyrene)-b-poly(diethyl 4-(p-styryl)-1-butanephosphonate) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(diethyl 4-(p-styryl)-1-butanephosphonate), hereinafter also referred to as "so-sbPdE"). Except for using diethyl 4-(p-styryl)-1-butanephosphonate obtained in step 1-2 of Example 3 instead of diethyl 8-(p-styryl)-1-octanephosphonate, poly(p-n-octylstyrene)-b-poly(diethyl 4-(p-styryl)-1-butanephosphonate) (also referred to as "so-sbPdE").

[0503] The number-average degree of polymerization of the so block was 620, the number-average degree of polymerization of the sbPdE block was 2075, the overall Mn was 749k, and Mw / Mn was 4.72. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) block were deprotected to obtain poly(pn-octylstyrene)-b-poly(4-(p-styryl)-1-butanephosphonic acid) (also called poly(1-(p-styryl)-n-octane)-b-poly(4-(p-styryl)-1-butanephosphonic acid) (hereinafter also referred to as "so-sbPA"). The proton-conducting membrane of Example 8 (hereinafter also referred to as "so-sbPA-1 membrane") was fabricated from this so-sbPA. Scheme 13 shows the polymer synthesis scheme.

[0504] [ka]

[0505] The proton conductivity of the proton-conductive electrolyte membrane of Example 8 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 8 are summarized in Table 1. The membrane of Example 8 exhibited proton conductivities of, for example, 14 mS / cm at 100°C and 80% RH, 6.2 mS / cm at 100°C and 60% RH, 2.6 mS / cm at 100°C and 40% RH, and 1.2 mS / cm at 100°C and 20% RH, which were higher than the proton-conductive electrolyte membranes of Comparative Examples 1 and 2.

[0506] Example 9 In Example 9, diethyl 4-(p-styryl)-1-butanephosphonate obtained in step 1-2 of Example 3 was used, and monomer polymerization and deprotection reactions were carried out in the same manner as in step 2 and step 3 of Example 3, to synthesize poly(4-(p-styryl)-1-butanephosphonic acid) (hereinafter also referred to as "sbPA"), which is a polymer having one phosphonic acid group per spacer via an alkylene spacer.

[0507] By combining this with sbPA and a commercially available nonwoven fabric made of polyphenylene sulfide (manufactured by Hirose Paper Co., Ltd., hereafter also referred to as "PPS nonwoven fabric"), a protonic polymer electrolyte membrane (hereafter also referred to as "sbPA / PPS membrane") was produced.

[0508] Furthermore, when GPC measurement was carried out and the molecular weight was calibrated using standard polystyrene, the Mw / Mn and Mn of the polymer before the deprotection reaction were 1.82 and 130k, respectively.

[0509] The sbPA and PPS nonwoven fabric were composited as follows.

[0510] First, sbPA was dissolved in a mixed solvent of methanol and alkaline water (pH 13 or higher), and the resulting solution was impregnated into a 4 cm square PPS nonwoven fabric. The fabric was then left to stand at 60°C to evaporate the solvent. This procedure was repeated several times, and the resulting membrane was then heat-pressed at 120°C for 1 minute. The resulting membrane was then immersed in acidic water (pH 1 or higher) for 1 hour, and thoroughly dried to prepare the proton-conducting electrolyte membrane of Example 9.

[0511] The proton conductivity of the proton-conducting electrolyte membrane of Example 7 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 9 are summarized in Table 1. The membrane of Example 9 exhibited a proton conductivity of 1.2 mS / cm at 120°C and 40% RH and 0.46 mS / cm at 120°C and 20% RH.

[0512] To evaluate the mechanical properties of the membrane of Example 9, a tensile test was carried out.

[0513] Specifically, the sbPA / PPS membrane was punched using a punching die corresponding to the dumbbell-shaped No. 7 shape specified in the Japanese Industrial Standards (JIS) K6251:2017 (equivalent to Type 4 in the International Organization for Standardization (ISO)37:2017) to prepare test specimens. The thickness of the test specimens was approximately 0.12 mm.

[0514] The measuring equipment used was a Shimadzu AGS-X, a 50N load cell, and a pneumatic flat gripper. The tensile tests were performed at an air pressure of 0.40MPa, room temperature, a distance between the grippers of approximately 10mm, and an initial strain rate of 0.10 / s (tensile rate of approximately 1.0mm / s).

[0515] The stress-strain curve, which is the result of the tensile test, is shown by the solid line in Figure 28. The mechanical strength and breaking elongation were 11.9 MPa and 24%, respectively, indicating good mechanical properties.

[0516] <Comparative Example 3> In Comparative Example 3, the sbPA obtained in Example 9 was processed into a membrane in the same manner as in the fourth step of Example 1, thereby producing a proton-conductive electrolyte membrane of Comparative Example 3.

[0517] The conductivity of the proton-conducting electrolyte membrane of Comparative Example 3 is summarized in Table 1. The membrane of Comparative Example 3 exhibited, for example, a proton conductivity of 2.6 mS / cm at 120°C and 40% RH, and 1.1 mS / cm at 120°C and 20% RH.

[0518] A tensile test was attempted on the membrane of Comparative Example 3 in the same manner as the membrane of Example 9, but the membrane was so brittle that it could not be punched out with a punching blade corresponding to a No. 7 dumbbell shape.

[0519] These results demonstrate that the membrane of Example 9 has superior mechanical strength compared to the membrane of Comparative Example 3. It is believed that the membrane of Example 9 has a higher mechanical strength as a whole than sbPA alone because sbPA is combined with the PSS nonwoven fabric, which has high mechanical strength.

[0520] Example 10 In Example 10, a protonic polymer electrolyte membrane (hereinafter also referred to as "so-soPA / PPS membrane") was prepared by combining so-soPA and PPS nonwoven fabric in the same manner as in Example 9, except that so-soPA obtained in the second step of Example 7 was used instead of sbPA and a mixed solvent of 1-propanol and acidic water (pH 1 or less) was used as the solvent.

[0521] The proton conductivity of the proton-conducting electrolyte membrane of Example 10 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 10 are summarized in Table 1. The membrane of Example 10 exhibited, for example, a proton conductivity of 1.9 mS / cm at 120°C and 40% RH and 1.1 mS / cm at 120°C and 20% RH.

[0522] Example 11 In Example 11, the same procedure as in Example 7 was used to prepare a block copolymer, poly(p-n-octylstyrene)-b-poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) (also referred to as poly(1-(p-styryl)-n-octane)-b-poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate), hereinafter also referred to as "so-sodPAtE"). Except for using tetraethyl 8-(p-styryl)-1,1-octanediphosphonate obtained in step 1-3 of Example 1 instead of diethyl 8-(p-styryl)-1-octanephosphonate, poly(p-n-octylstyrene)-b-poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) (hereinafter also referred to as "so-sodPAtE").

[0523] The number-average degree of polymerization of the so block was 130, the number-average degree of polymerization of the soPdE block was 3120, and the overall Mn was 1552kJ (Mw / Mn = 3.5). The protecting groups of the poly(tetraethyl 8-(p-styryl)-1,1-octanediphosphonate) block were deprotected to obtain poly(pn-octylstyrene)-b-poly(8-(p-styryl)-1,1-octanediphosphonic acid) (also called poly(1-(p-styryl)-n-octane)-b-poly(8-(p-styryl)-1,1-octanediphosphonic acid) (hereinafter also referred to as "so-sodPA"). This so-sodPA was then processed into a membrane to prepare the proton-conducting membrane of Example 13 (hereinafter also referred to as "so-sodPA membrane"). Scheme 14 shows the polymer synthesis scheme.

[0524] [ka]

[0525] The proton conductivity of the proton-conductive electrolyte membrane of Example 11 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 11 are summarized in Table 1. The membrane of Example 13 exhibited, for example, proton conductivities of 140 mS / cm at 100°C and 80% RH, 63 mS / cm at 100°C and 60% RH, 27 mS / cm at 100°C and 40% RH, and 9.1 mS / cm at 100°C and 20% RH, which were higher than the proton-conductive electrolyte membranes of Comparative Examples 1 and 2.

[0526] Example 12 In Example 12, so-sbPdE (number-average degree of polymerization of so blocks: 322, number-average degree of polymerization of sbPdE blocks: 1825, overall Mn: 611k, Mw / Mn = 2.40) was synthesized in the same manner as in Example 8, except that the amounts of pn-octylstyrene monomer and 4-(p-styryl)-1-butanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) blocks were then deprotected to form so-sbPA, which was then converted into a membrane to produce the proton conductive membrane of Example 12 (hereinafter also referred to as "so-sbPA-2 membrane").

[0527] The proton conductivity of the proton-conducting electrolyte membrane of Example 12 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 12 are summarized in Table 1. The membrane of Example 12 exhibited, for example, a proton conductivity of 10 mS / cm at 100°C and 80% RH, 3.8 mS / cm at 100°C and 60% RH, 1.7 mS / cm at 100°C and 40% RH, and 0.64 mS / cm at 100°C and 20% RH.

[0528] Example 13 In Example 13, so-sbPdE (number-average degree of polymerization of so blocks: 322, number-average degree of polymerization of sbPdE blocks: 3703, overall Mn: 1170k, Mw / Mn = 5.13) was synthesized in the same manner as in Example 8, except that the amounts of pn-octylstyrene monomer and 4-(p-styryl)-1-butanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) blocks were then deprotected to form so-sbPA, which was then formed into a membrane to produce the proton conductive membrane of Example 13 (hereinafter also referred to as "so-sbPA-3 membrane").

[0529] The proton conductivity of the proton-conducting electrolyte membrane of Example 13 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 13 are summarized in Table 1. The membrane of Example 13 exhibited, for example, a proton conductivity of 11 mS / cm at 100°C and 80% RH, 6.3 mS / cm at 100°C and 60% RH, 3.0 mS / cm at 100°C and 40% RH, and 1.6 mS / cm at 100°C and 20% RH.

[0530] Example 14 In Example 14, so-sbPdE (number-average degree of polymerization of so blocks: 322, number-average degree of polymerization of sbPdE blocks: 349, overall Mn: 173k, Mw / Mn = 3.55) was synthesized in the same manner as in Example 8, except that the amounts of pn-octylstyrene monomer and 4-(p-styryl)-1-butanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(4-(p-styryl)-1-butanephosphonic acid diethyl) blocks were then deprotected to form so-sbPA, which was then formed into a membrane to produce the proton conductive membrane of Example 14 (hereinafter also referred to as "so-sbPA-4 membrane").

[0531] The proton conductivity of the proton-conducting electrolyte membrane of Example 14 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 14 are summarized in Table 1. The membrane of Example 14 exhibited, for example, a proton conductivity of 6.3 mS / cm at 100°C and 80% RH, 2.1 mS / cm at 100°C and 60% RH, 0.69 mS / cm at 100°C and 40% RH, and 0.18 mS / cm at 100°C and 20% RH.

[0532] Example 15 In Example 15, so-soPdE (number-average degree of polymerization of so blocks: 45, number-average degree of polymerization of soPdE blocks: 255, overall Mn: 100k, Mw / Mn = 1.52) was synthesized in the same manner as in Example 7, except that the amounts of pn-octylstyrene monomer and 8-(p-styryl)-1-octanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) blocks were then deprotected to obtain so-soPA. This so-soPA was then converted into a membrane, thereby producing the proton-conductive membrane of Example 15 (hereinafter also referred to as the "so-soPA-2 membrane").

[0533] The proton conductivity of the proton-conducting electrolyte membrane of Example 15 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 15 are summarized in Table 2. The membrane of Example 15 exhibited, for example, a proton conductivity of 7.9 mS / cm at 120°C and 40% RH and 5.0 mS / cm at 120°C and 20% RH.

[0534] A tensile test was performed on the film of Example 15 in the same manner as the film of Example 9, except that the test specimen was a 5 mm x 20 mm strip, the distance between the grippers was approximately 5 mm, and the initial strain rate was 0.005 / s (tensile rate approximately 0.025 mm / s). Figure 29 shows the stress-strain curve obtained from the tensile test, shown by the dashed line. The Young's modulus (the slope of the stress-strain curve at strains of 0 to 1%), mechanical strength, elongation at break, and toughness (the value of the internal area of ​​the stress-strain curve) were 77 MPa, 3.2 MPa, 6.0%, and 120 kJ / m, respectively. 3 It was.

[0535] <Comparative Example 4> In Comparative Example 4, soPdE (Mn: 55k, Mw / Mn = 1.96) was synthesized in the same manner as in Comparative Example 1, except that the amount of 8-(p-styryl)-1-octanephosphonic acid diethyl was changed appropriately. The protecting group of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) block was deprotected to obtain soPA, and this soPA was converted into a membrane to produce the proton conductive membrane of Comparative Example 4 (hereinafter also referred to as "soPA-2 membrane").

[0536] The proton conductivity of the proton-conducting electrolyte membrane of Comparative Example 4 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Comparative Example 4 are summarized in Table 2. The membrane of Comparative Example 4 exhibited, for example, a proton conductivity of 7.5 mS / cm at 120°C and 40% RH and 4.4 mS / cm at 120°C and 20% RH. Therefore, although the membrane of Example 15 contained so blocks and therefore had a lower acid group density than the membrane of Comparative Example 4, it maintained a conductivity equivalent to that of the membrane of Comparative Example 4.

[0537] In the soPA-2 membrane of Comparative Example 4, phase separation occurs during membrane formation into a phase consisting of hydrophilic phosphonic acid groups and a phase consisting of hydrophobic alkylene spacer groups and polystyrene main chains, and it is thought that each phase tends to be oriented parallel to the membrane surface.

[0538] On the other hand, in the so-soPA-2 membrane of Example 11, in addition to the phase separation within the soPA block, phase separation also occurred between the so and soPA blocks, which is thought to have resulted in the conductive phosphonic acid phase being more likely to be oriented perpendicular to the membrane surface. This change in orientation is thought to have facilitated the efficient formation of a network of phosphonic acid phases, resulting in conductivity equivalent to that of the membrane of Comparative Example 4.

[0539] A tensile test was carried out on the membrane of Comparative Example 4 in the same manner as the membrane of Example 15. The stress-strain curve showing the results of the tensile test is shown by the dotted line in Figure 29. The Young's modulus, mechanical strength, elongation at break, and toughness were 120 MPa, 2.7 MPa, 2.5%, and 44 kJ / m, respectively. 3 The film of Example 15 exhibited better breaking elongation and toughness than the film of Comparative Example 4.

[0540] The membrane of Example 15 stretched more than the membrane of Comparative Example 4. This is thought to be because the stress generated during stretching was dispersed in the flexible domains formed by the so blocks. As a result, premature breakage of the membrane was suppressed, and the membrane of Example 15 exhibited higher toughness than the membrane of Comparative Example 4.

[0541] Example 16 In Example 16, so-soPdE (number-average degree of polymerization of so blocks: 105, number-average degree of polymerization of soPdE blocks: 234, overall Mn: 105k, Mw / Mn = 1.63) was synthesized in the same manner as in Example 7, except that the amounts of pn-octylstyrene monomer and 8-(p-styryl)-1-octanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) blocks were then deprotected to obtain so-soPA, which was then converted into a membrane to produce the proton-conducting membrane of Example 16 (hereinafter also referred to as the "so-soPA-3 membrane").

[0542] The proton conductivity of the proton-conducting electrolyte membrane of Example 16 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 16 are summarized in Table 2. The membrane of Example 16 exhibited, for example, a proton conductivity of 5.4 mS / cm at 120°C and 40% RH and 3.3 mS / cm at 120°C and 20% RH, which was the same order of conductivity as the membrane of Comparative Example 4.

[0543] A tensile test was carried out on the membrane of Example 16 in the same manner as the membrane of Example 15. The stress-strain curve showing the results of the tensile test is shown by the dashed line in Figure 29. The Young's modulus, mechanical strength, elongation at break, and toughness were 83 MPa, 3.4 MPa, 5.5%, and 120 kJ / m, respectively. 3 The film of Example 12 exhibited better breaking elongation and toughness than the film of Comparative Example 4.

[0544] The membrane of Example 16 stretched more than the membrane of Comparative Example 4. This is thought to be because the stress generated during stretching was dispersed in the flexible domains formed by the so blocks. As a result, premature breakage of the membrane was suppressed, and the membrane of Example 16 exhibited higher toughness than the membrane of Comparative Example 4.

[0545] Example 17 In Example 17, so-soPdE (number-average degree of polymerization of so blocks: 130, number-average degree of polymerization of soPdE blocks: 231, overall Mn: 110k, Mw / Mn = 1.69) was synthesized in the same manner as in Example 7, except that the amounts of pn-octylstyrene monomer and 8-(p-styryl)-1-octanephosphonic acid diethyl were appropriately changed. The protecting groups of the poly(8-(p-styryl)-1-octanephosphonic acid diethyl) blocks were then deprotected to obtain so-soPA. This so-soPA was then converted into a membrane, thereby producing the proton-conducting membrane of Example 17 (hereinafter also referred to as the "so-soPA-4 membrane").

[0546] The proton conductivity of the proton-conducting electrolyte membrane of Example 17 was measured in the same manner as in Example 1. The measurement results of the proton conductivity of Example 17 are summarized in Table 2. The membrane of Example 17 exhibited, for example, a proton conductivity of 3.7 mS / cm at 120°C and 40% RH and 2.7 mS / cm at 120°C and 20% RH, which was the same order of conductivity as the membrane of Comparative Example 4.

[0547] A tensile test was carried out on the membrane of Example 17 in the same manner as the membrane of Example 15. The stress-strain curve showing the results of the tensile test is shown by the solid line in Figure 29. The Young's modulus, mechanical strength, elongation at break, and toughness were 51 MPa, 3.5 MPa, 15%, and 360 kJ / m, respectively. 3 The film of Example 13 exhibited better breaking elongation and toughness than the film of Comparative Example 4.

[0548] The membrane of Example 17 stretched more than the membrane of Comparative Example 4. This is thought to be because the stress generated during stretching was dispersed in the flexible domains formed by the so blocks. As a result, premature breakage of the membrane was suppressed, and the membrane of Example 17 exhibited higher toughness than the membrane of Comparative Example 4.

[0549] [Table 1]

[0550] [Table 2]

[0551] Example 18 In Example 18, 7,7′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was synthesized as a monomer having two phosphonate esters per spacer via alkylene spacers according to Scheme 15 below (first step).

[0552] [ka]

[0553] Subsequently, this monomer is polymerized (second step) according to the following Scheme 16, and the alkyl protecting groups of the resulting poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) are deprotected to obtain poly(7,7'-(9H-fluorene-9,9-diyl)bis(1,1-heptanediphosphonic acid)), a polymer having two phosphonic acid groups per spacer via an alkylene spacer (hereinafter referred to as "fb(h p dPA) was synthesized (third step).

[0554] [ka]

[0555] This FB(h p dPA) was formed into a membrane to prepare the proton-conductive electrolyte membrane of Example 1 (fourth step).

[0556] (First step) In a paper (J. Org. Chem. 2011, 76, 8807-8813), a compound with a bromoalkyl structure was reacted with sodium hydride, and then further reacted with methylene diphosphonic acid tetraester to synthesize a compound with an alkylene diphosphonic acid tetraester structure. Based on this reaction, 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was synthesized.

[0557] Specifically, 0.273 g (6.83 mmol) of sodium hydride (60 wt%) dispersed in liquid paraffin was dissolved in 2 mL of dehydrated THF under a nitrogen atmosphere, and 2.22 g (6.45 mmol) of tetraisopropyl methylenediphosphonate was added. 0.998 g (1.53 mmol) of 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene was then added and heated with stirring. The reaction was then quenched by adding saturated aqueous ammonium chloride.

[0558] Extraction was performed by separation, and the solvent used in the separation was removed using rotary evaporation. Further separation and purification were carried out by passing through a silica gel column to obtain 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate). Ethyl acetate and 2-propanol were used as developing solvents.

[0559] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was carried out. In Fig. 30, the solid line (Example 18) shows the 1 The H-NMR spectrum is shown.

[0560] Also, in FIG. 30, the broken line (Example 19) shows the fluorene of 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene. 1 The H-NMR spectrum is shown.

[0561] The precursor, 2,7-dibromo-9,9-bis(6-bromohexyl)fluorene 1 In the H-NMR spectrum, the proton (i') of the methylene group with a bromo group was observed around 3.3 ppm.

[0562] After the reaction 1 In the H-NMR spectrum, the peak due to the proton (i') of the methylene group with a bromo group disappeared, and the peak due to the proton (k) of the methine group next to the oxygen atom of the four phosphonate diester units appeared at around 4.7 ppm, the peak due to the proton (l) of the methyl group next to that appeared at around 1.3 ppm, and the peak due to the methine group proton (j) next to the two phosphorus atoms appeared at 2.1 ppm. This suggests that 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) was obtained.

[0563] The peak at 7.27 ppm is due to chloroform, and the peaks at 1.2 and 4.0 ppm are due to 2-propanol.

[0564] (Second step) In the literature (J. Am. Chem. Soc. 2007, 129, 11910-11911.), 2,7-dibromo-9,9-dioctyl-9H-fluorene was polymerized using a nickel compound. Based on this reaction, we synthesized poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)).

[0565] 0.705 g (2.56 mmol) of bis(1,5-cyclooctadiene)nickel(0), 0.297 g (1.90 mmol) of 2,2'-bipyridyl, and 0.220 g (2.03 mmol) of 1,5-cyclooctadiene were weighed out and added to 4.25 mL of N,N-dimethylformamide (DMF) with heating and stirring. 0.511 g (0.434 mmol) of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) obtained in the first step and 5.0 mL of toluene were added and stirred for an additional 4 days.

[0566] The resulting solution was washed with chloroform, hydrochloric acid, pure water, and saturated saline, and then reprecipitated with n-hexane to obtain purified poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) (0.288 g).

[0567] Using deuterated chloroform, 1 H-NMR measurement was performed. In FIG. 31, the dashed line indicates poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)). 1 The H-NMR spectrum is shown.

[0568] A broad signal was observed at a position almost identical to the chemical shift of the monomer, suggesting that a polymer was obtained.

[0569] Poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) was dissolved in THF to prepare a solution of approximately 0.1% by mass, and the molecular weight distribution (Mw / Mn) and number-average molecular weight (Mn) were determined by gel permeation chromatography (GPC). Figure 32 shows the GPC chromatogram of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)). The Mw / Mn and Mn, determined by molecular weight calibration using standard polystyrene, were 1.82 and 38kJ, respectively.

[0570] The eluent used was a solvent mainly composed of THF, the flow rate was 1 mL / min, the temperature was 40°C, and the measurement was carried out using two connected TSKgel columns GMHHR-M manufactured by Tosoh Corporation.

[0571] (Third step) In the literature (Macromolecules, 2018, 51, 1120-1128.), poly(4-styrenephosphonic acid diethyl) was reacted with bromotrimethylsilane, then reacted with methanol solvent, and dialyzed to deprotect the alkyl groups of poly(4-styrenephosphonic acid diethyl) and synthesize poly(4-styrenephosphonic acid) without an alkylene spacer.

[0572] Using this reaction as a reference, poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) obtained in the second step was reacted with bromotrimethylsilane, then with methanol, and the mixture was dialyzed against water to carry out a deprotection reaction.

[0573] Specifically, 2.88 g (0.275 mmol in monomer units) of poly(7,7'-(9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate)) was dissolved in 5.0 mL of chloroform, 1.7 g (11 mmol) of bromotrimethylsilane was added, and the mixture was placed in a 40 °C oil bath and stirred overnight. The polymer was reacted and dissolved in an excess amount of methanol, and then purified by dialysis using a cellulose dialysis tube and pure water. Finally, the water was evaporated to obtain fb(h p dPA) was obtained.

[0574] fb(h p dPA) was dissolved in a mixed solvent of deuterated methanol and hydrochloric acid, 1 H-NMR measurements were performed. In Figure 31, the solid line indicates fb(h p dPA) 1 The H-NMR spectrum is shown.

[0575] The peak at around 4.8 ppm, which was derived from the proton (k') of the methine group adjacent to the oxygen atom of the phosphonate diester, almost disappeared, confirming that deprotection had proceeded to 99%.

[0576] The peak near 3.3 ppm is a peak derived from methanol, and the peak near 5.7 ppm is a peak derived from hydrochloric acid.

[0577] (Fourth step) 30mg of fb(h p dPA) was dissolved in approximately 1.1 g of a mixed solvent of methanol and acidic water (pH 1 or less). The resulting solution was transferred to a polypropylene container and allowed to stand overnight at 60°C to evaporate the solvent, preparing a cast membrane. The membrane was then immersed in pure water at 60°C for 1 hour to prepare the proton-conducting electrolyte membrane of Example 11.

[0578] <Evaluation> (AC impedance measurement) Using platinum mesh with a thickness of about 0.1 mm as an electrode, AC impedance measurements were carried out on the sample of the proton-conductive electrolyte membrane of Example 1.

[0579] A sample of the proton-conductive electrolyte membrane of Example 1 cut into a strip (thickness: 0.035 mm, width: 5.0 mm, length: 10 mm) was sandwiched between a pair of electrodes arranged opposite each other with an inter-electrode distance of 0.70 cm and an electrode width of 0.18 cm to prepare a measurement cell.

[0580] The measurement cell was placed in a small environmental test chamber (SH-242, manufactured by Espec Corporation) and the conditions were set at a temperature of 100°C and a relative humidity of 80% RH (partial pressure of water vapor pH2O = 818 hPa). Using a potentio / galvanostat VSP-300 (manufactured by BioLogic Science Instruments), the voltage was set to 50 mV and the frequency was set to 7 × 10 6 The AC impedance was measured by varying the frequency in the range of 1 Hz to 1 Hz. The resistance value at the minimum point of the Nyquist plot was found to be 2.7 x 10 4 It was Omega.

[0581] The proton conductivity of this proton-conductive electrolyte membrane sample was calculated using the following formula (1), and was found to be 42 mS / cm (Table 2).

[0582] Proton conductivity = electrode distance / (membrane thickness x electrode width x resistance at the minimum point of the Nyquist plot) (1)

[0583] Relative humidity is set to 60%RH (p H2O =613hPa), 40%RH(p H2O =408hPa), 20%RH(p H2O = 204 hPa), and AC impedance measurements were performed. The relative humidity dependence of conductivity at 120°C was also measured in the same manner. The membrane of Example 18 exhibited a proton conductivity of 7.3 mS / cm at 120°C and 40% RH, and 1.8 mS / cm at 120°C and 20% RH. The conductivity measurement results are summarized in Table 3, and the conductivities at 100°C and 120°C are represented by black circles (●) in Figure 33 (100°C) and Figure 34 (120°C), respectively.

[0584] (Water resistance evaluation) When the proton-conductive electrolyte membrane of Example 18 was immersed in water at 60° C. for 2 hours, there was almost no change in the appearance of the membrane before and after immersion in water, and almost no elution of the polymer into the liquid water was observed.

[0585] Furthermore, fb(h p Poly(6,6'-(9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate)) (fb(h)) was used as a comparative sample for the dPA film. x PA) synthesized 6,6′-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate) as a monomer having one phosphonate ester per spacer via an alkylene spacer according to Scheme 17 below (FIG. 35).

[0586] [ka]

[0587] Next, this monomer is polymerized in the same manner as in the second step of Example 18 according to the following Scheme 18, and the alkyl protecting groups of the resulting poly(6,6'-(9H-fluorene-9,9-diyl)bis(diethyl 1-hexanephosphonate)) are deprotected in the same manner as in the third step of Example 1, thereby completing the synthesis. [ka]

[0588] Example 19 In Example 19, 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) synthesized in the same manner as in the first step of Example 18 was used to synthesize 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl heptane-1,1-diphosphonate-1-diethyl phosphonate) as a monomer having three phosphonate esters per spacer via alkylene spacers, according to Scheme 19 below.

[0589] [ka]

[0590] This monomer serves as a raw material for a polymer having three phosphonic acid groups per spacer via an alkylene spacer.

[0591] In a paper (J. Org. Chem. 2011, 76, 8807-8813), a compound with an alkylene diphosphonic acid tetraester structure was reacted with sodium bis(trimethylsilyl)amide, then reacted with chlorodiethyl phosphite, and then oxidized with hydrogen peroxide to synthesize a compound with an alkylene triphosphonic acid hexaester structure. Based on this reaction, 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) was synthesized.

[0592] Specifically, 0.91 g (0.77 mmol) of 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) synthesized in the same manner as in the first step of Example 18 was dissolved in dehydrated THF under an argon gas atmosphere and cooled to 0°C. 2.0 mL (3.8 mmol) of a THF solution of sodium bis(trimethylsilyl)amide (concentration: 1.9 mol / L) was added.

[0593] 0.88 mL (0.96 g, 6.1 mmol) of diethyl chlorophosphite was added, and 2.8 mL (3.2 g, 93 mmol) of hydrogen peroxide solution (concentration 35%) was further added and stirred for 1.5 hours to synthesize 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate).

[0594] The volatile solvent (THF) was evaporated by rotary evaporation. After extraction by separation, the solvent used in the separation was removed by rotary evaporation. Further distillation under reduced pressure removed unreacted diethyl chlorophosphite and by-products.

[0595] The resulting liquid was purified by passing it through a silica gel column to obtain 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate). Ethyl acetate, methanol, and propanol were used as developing solvents.

[0596] The liquid obtained after purification was dissolved in deuterated chloroform. 1 H-NMR measurement was performed. In FIG. 36, the solid line shows the 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) 1 The H-NMR spectrum is shown.

[0597] The peak at 2.1 ppm, which was observed in 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(tetraisopropyl 1,1-heptanediphosphonate) and originated from the methine group protons next to the two phosphorus atoms, disappeared.

[0598] Furthermore, a peak derived from the protons (j) of the methine group next to the oxygen atoms of the four diisopropyl phosphonate units was observed at around 4.7 to 4.9 ppm, and a peak derived from the protons (k) of the methyl group next to that appeared at around 1.3 ppm. Also, a peak derived from the protons (l) of the methylene group next to the oxygen atoms of the two diethyl phosphonate units appeared at around 4.1 to 4.3 ppm, and a peak derived from the protons (m) of the methyl group next to that appeared at around 1.3 ppm. These facts confirmed that 7,7'-(2,7-dibromo-9H-fluorene-9,9-diyl)bis(heptane-1,1-diphosphonic acid tetraisopropyl-1-diethyl phosphonate) was obtained.

[0599] The peak at 7.27 ppm is due to chloroform, and the peak at 3.5 ppm is due to methanol.

[0600] [Table 3]

[0601] Industrial Applicability The polymer or block polymer (polymer electrolyte membrane) of the present invention is (1) useful as an electrolyte membrane for a fuel cell in the production of a fuel cell, (2) useful as an anhydrous electrolyte membrane, and (3) useful as an ion exchange membrane in the production of an ion exchange device.

Claims

1. It is a monomer that has a functional group via a spacer structure and can constitute a polymer, The functional group is phosphonic acid groups and / or phosphonate ester units; a basic functional group; or a cationic functional group based on a basic functional group; The spacer structure is Does not contain highly hydrolyzable functional groups, Per one spacer structure, two or more of the phosphonic acid groups and / or phosphonate ester units; one or more of the basic functional groups; or one or more cationic functional groups based on the basic functional group; monomer.

2. The monomer according to claim 1 , wherein the functional group is located at an end of the spacer structure.

3. When the functional group is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms; When the functional group is a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 3 to 20 carbon atoms; or 2. The monomer according to claim 1, wherein when the functional group is a cationic functional group based on a basic functional group, the spacer structure is a linear, branched, or cyclic hydrocarbon spacer having 2 to 20 carbon atoms.

4. The monomer unit comprises the monomer of claim 1, the functional group of the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, and the monomer unit has two or more of the phosphonic acid group and / or the phosphonate ester unit per spacer structure; The functional group of the monomer unit is a basic functional group, and the monomer unit has one or more basic functional groups per spacer structure, or the monomer unit is not a fluorene-based monomer unit, the functional group is a cationic functional group based on a basic functional group, and each spacer structure has one or more cationic functional groups based on the basic functional group; polymer.

5. The polymer according to claim 4 , wherein the polymer is a polymer formed by chain polymerization or a polymer formed by step-growth polymerization.

6. It is a block polymer in which at least an a block and a b block are connected by a covalent bond, The a block is a polymer according to claim 4, or a polymer comprising a monomer unit having a functional group via a spacer structure and composed of a monomer capable of constituting a polymer, wherein the functional group of the monomer unit is a phosphonic acid group and / or a phosphonate ester unit, the spacer structure does not contain a highly hydrolyzable functional group, and the polymer comprises a monomer unit having one phosphonic acid group and / or one phosphonate ester unit per spacer structure; The b block is It is made of hydrophobic or water-repellent polymers, The polymer has a glass transition temperature (Tg) of 50°C or less. Block polymer.

7. The block polymer according to claim 6 , wherein the b block is a polymer in which an alkyl chain is directly bonded to a main chain skeleton portion.

8. a block polymer in which at least the a block, the b block, and the c block are linked by a covalent bond; The c block is It is made of hydrophobic or water-repellent polymers, A polymer having a glass transition temperature (Tg) of 120°C or higher. The block polymer according to claim 6 or 7.

9. A polymer according to claim 4 or 5, or The block polymer according to claim 6, 7, or 8, Polymer electrolyte membrane.

10. The polymer electrolyte membrane according to claim 9 , which is water resistant.

11. A polymer according to claim 4 or 5, or The block polymer according to claim 6, 7, or 8, Ionomers, or membrane / electrode assemblies.

12. The ionomer or membrane / electrode assembly according to claim 11, which is water resistant.

13. The polymer electrolyte membrane according to claim 9 , or The ionomer of claim 11, A sheet-like material reinforced membrane that is reinforced with a sheet-like material having voids.

14. 14. The sheet material reinforced membrane according to claim 13, wherein the sheet material having voids is a nonwoven fabric and / or a porous sheet.

15. A polymer according to claim 4 or 5, or The block polymer according to claim 6, 7, or 8, a fuel cell including a fuel cell electrolyte membrane; A water electrolysis device including an electrolyte membrane for water electrolysis, or An ion exchange device comprising an ion exchange membrane.

16. A polymer according to claim 4 or 5, or The block polymer according to claim 6, 7, or 8, Separation membrane, anion exchange membrane, or cation exchange membrane.

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