JP2023037179A - Method for producing polymer, polymer, electrolyte membrane, fuel cell, and electrolysis device - Google Patents

Abstract

Kind Code: A1 A method for producing a polymer by which a polymer having a high molecular weight is obtained, a polymer obtained by the production method, an electrolyte membrane having excellent chemical durability using the polymer, and a fuel cell and an electrolyzer using the electrolyte membrane. provide. A method for producing a polymer containing a structural unit represented by the following formula (1), comprising reacting a combination of two compounds having specific structures in the presence of a specific catalyst. manufacturing method. TIFF2023037179000022.tif1147 where Ar1 is a group containing an aromatic ring having an ion exchange group, and Ar2 is a group containing an aromatic ring. [Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to a method for producing a polymer, a polymer, an electrolyte membrane, a fuel cell, and an electrolyser.

Electrolyte membranes and electrolyte ionomers are used in various fuel cells such as polymer electrolyte fuel cells and solid alkaline fuel cells, and in various electrolysis techniques such as water electrolysis. The electrolyte membrane is required to have excellent ionic conductivity as well as chemical and mechanical durability to withstand long-term use. In addition, electrolyte ionomers are required to have high fuel gas permeability as well as high chemical durability.

The present inventors have disclosed in Patent Document 1 that a specific hydrophilic portion and a specific hydrophobic portion are used as a proton conductive material for an electrolyte membrane having high swelling resistance and high proton conductivity in which ion exchange groups are densely accumulated. and a repeating unit containing a specific cyclic compound in at least one of the hydrophilic portion and the hydrophobic portion. The proton conductive material has a structure in which a hydrophilic portion and a hydrophobic portion are linked via an ether bond.
A proton conductive material having an ether bond in its main chain has a problem that the ether bond is cleaved and degraded particularly in an alkaline environment.

In Patent Document 2, the present inventors disclose a polymer containing no ether bond in its main chain and a method for producing the same. The electrolyte membrane using the polymer of Patent Document 2 is excellent in chemical durability and membrane strength.

JP 2016-44242 A JP 2021-42351 A

According to the method for producing a polymer disclosed in Patent Document 2, a polymer having a relatively high molecular weight can be produced. On the other hand, since the polymer of Patent Document 2 uses a fluorine-substituted aromatic compound as a raw material, it contains a relatively large amount of fluorine atoms.
From the viewpoint of SDGs and the like, the present inventors have investigated a method for producing a polymer that does not contain a fluorine atom, taking recycling of the polymer into consideration. However, for example, when an aromatic compound having no fluorine atom was used and the manufacturing method steps of Patent Document 2 were applied, only a polymer with a relatively small molecular weight was obtained. From the viewpoint of film strength, etc., it is required to produce a polymer having a large molecular weight.

The present invention provides a method for producing a polymer by which a polymer having a high molecular weight can be obtained, a polymer obtained by the production method, an electrolyte membrane having excellent chemical durability using the polymer, and a fuel cell and an electrolyzer using the electrolyte membrane. intended to provide

ただし、
Ａｒ^１はイオン交換基を有する芳香環を含む基であり、
Ａｒ^２は芳香環を含む基であり、
Ａｒ^３はハロゲノ基、スルホン酸エステル基、リン酸エステル基、カルボン酸エステル基、イミダゾール基及びアミノ基より選択される官能基を有する芳香環を含む基であり、
Ｘ^１及びＸ^２は、各々独立に、Ｂｒ又はＩであり、
Ｒ^１及びＲ^２は、各々独立に、－Ｂ（ＯＨ）_２、－Ｂ（ＯＲ^１１）_２、－ＢＦ_３Ｘ^１１、又は、ボロン酸ＭＩＤＡエステルであり、
Ｒ^１１は、置換基を有していてもよいアルキル基であって、２つのＲ^１１が連結して環構造を形成してもよく、
Ｘ^１１は１価のカチオンであり、
Ｌは、ホスフィン配位子である。 The method for producing the polymer according to the present invention comprises:
A method for producing a polymer containing a structural unit represented by the following formula (1),
A compound represented by the following formula (2A) and a compound represented by the following formula (3A), or
A compound represented by the following formula (2B) and a compound represented by the following formula (3B),
It includes reacting in the presence of a catalyst represented by the following formula (4).

however,
Ar ¹ is a group containing an aromatic ring with an ion exchange group,
Ar ² is a group containing an aromatic ring,
Ar ³ is a group containing an aromatic ring having a functional group selected from a halogeno group, a sulfonate group, a phosphate group, a carboxylate group, an imidazole group and an amino group;
X ¹ and X ² are each independently Br or I;
R ¹ and R ² are each independently -B(OH) ₂ , -B(OR ¹¹ ) ₂ , -BF ₃ X ¹¹ , or MIDA boronic acid ester;
R ¹¹ is an optionally substituted alkyl group, and two R ¹¹ may be linked to form a ring structure,
X ¹¹ is a monovalent cation,
L is a phosphine ligand.

In one embodiment of the production method, the reaction is carried out in the presence of a base.

In one embodiment of the above production method, the catalyst acts as L-PdCl during the reaction.

In one embodiment of the above production method, the phosphine ligands are tri-tert-butylphosphine, triphenylphosphine, tricyclohexylphosphine, and 2-dicyclohexylphosphino-2′,4′,6′-triisopropyl It is one or more selected from biphenyl.

ただし、
Ａｒ^１はイオン交換基を有する芳香環を含む基であり、
Ａｒ^２は芳香環を含む基である。 The polymer according to the present invention contains a structural unit represented by the following formula (1) and has a weight average molecular weight of 100,000 or more.

however,
Ar ¹ is a group containing an aromatic ring with an ion exchange group,
Ar ² is a group containing an aromatic ring.

One embodiment of the polymer has no fluorine atoms.

The present invention provides an electrolyte membrane comprising the polymer according to the present invention.
The present invention also provides a fuel cell and an electrolyzer comprising the electrolyte membrane according to the present invention.

INDUSTRIAL APPLICABILITY According to the present invention, a polymer production method for obtaining a polymer having a high molecular weight, a polymer obtained by the production method, an electrolyte membrane excellent in chemical durability using the polymer, a fuel cell and an electrolysis apparatus using the electrolyte membrane is provided.

It is a scheme which shows an example of the manufacturing method of a polymer. 4 is a table and a graph showing evaluation results of swelling and ionic conduction properties. It is an NMR spectrum which shows the evaluation result of alkali durability.

In the following, the polymer, separation membrane, electrolyte membrane, fuel cell, and electrolyzer, as well as the method for producing the polymer according to the present invention, will be described in detail.
In the present invention, "polymer" includes "copolymer" unless otherwise specified.
In the present invention, the term "ion exchange group" refers to a dissociative functional group capable of ion exchange.
In the present invention, "-" indicating a numerical range means that the numerical values described before and after it are included as a lower limit and an upper limit.
In this specification, the "structural unit represented by formula (1)" may be referred to as "structural unit (1)". Structural units represented by other formulas also conform to this.
In this specification, the "compound represented by formula (2A)" may be referred to as "compound (2A)". Compounds, substituents, etc. represented by other formulas also follow this.

ただし、
Ａｒ^１はイオン交換基を有する芳香環を含む基であり、
Ａｒ^２は芳香環を含む基であり、
Ａｒ^３はハロゲノ基、スルホン酸エステル基、リン酸エステル基、カルボン酸エステル基、イミダゾール基及びアミノ基より選択される官能基を有する芳香環を含む基であり、
Ｘ^１及びＸ^２は、各々独立に、Ｂｒ又はＩであり、
Ｒ^１及びＲ^２は、各々独立に、－Ｂ（ＯＨ）_２、－Ｂ（ＯＲ^１１）_２、－ＢＦ_３Ｘ^１１、又は、ボロン酸ＭＩＤＡエステルであり、
Ｒ^１１は、置換基を有していてもよいアルキル基であって、２つのＲ^１１が連結して環構造を形成してもよく、
Ｘ^１１は１価のカチオンであり、
Ｌは、ホスフィン配位子である。 1. Method for Producing Polymer and Polymer The method for producing a polymer according to the present invention (hereinafter also referred to as the present production method) comprises:
A method for producing a polymer containing a structural unit represented by the following formula (1),
A compound represented by the following formula (2A) and a compound represented by the following formula (3A), or
A compound represented by the following formula (2B) and a compound represented by the following formula (3B),
It includes reacting in the presence of a catalyst represented by the following formula (4).

however,
Ar ¹ is a group containing an aromatic ring with an ion exchange group,
Ar ² is a group containing an aromatic ring,
Ar ³ is a group containing an aromatic ring having a functional group selected from a halogeno group, a sulfonate group, a phosphate group, a carboxylate group, an imidazole group and an amino group;
X ¹ and X ² are each independently Br or I;
R ¹ and R ² are each independently -B(OH) ₂ , -B(OR ¹¹ ) ₂ , -BF ₃ X ¹¹ , or MIDA boronic acid ester;
R ¹¹ is an optionally substituted alkyl group, and two R ¹¹ may be linked to form a ring structure,
X ¹¹ is a monovalent cation,
L is a phosphine ligand.

The production method comprises reacting compound (2A) or compound (2B), which is an aryl halide, with compound (3A) or compound (3B), which is an organoboron compound, in the presence of the catalyst (4). Characterized by By using the catalyst (4), a polymer having a relatively high molecular weight can be produced without using a fluorine-substituted aromatic compound as a raw material.
According to the present production method, for example, a linear polymer in which Ar ¹ and Ar ² are alternately arranged, having no ether bond in the main chain and no fluorine atom in the polymer, Polymers with a weight average molecular weight of 100,000 or more can be obtained.
Each configuration of this manufacturing method will be described below.

Ar ¹ in each of the above formulas is a group containing an aromatic ring having an ion exchange group as a substituent. Since Ar ¹ contains an aromatic ring that constitutes the main chain of the polymer, this polymer is excellent in chemical durability and mechanical strength after film formation. The Ar ¹ ion-exchange group also contributes to the ionic conductivity of the polymer.

When imparting proton conductivity _to the present polymer _, the ion exchange group preferably contains an acidic group. ₄ groups), or a carboxylic acid group (--COOH group), more preferably a sulfonic acid group. Incidentally, H in the acidic group may be substituted with an alkali metal ion, an alkaline earth metal ion, or the like.
When imparting anion conductivity to the present polymer, the ion exchange group preferably contains a quaternary ammonium group or an imidazolium group, more preferably a quaternary ammonium group. The quaternary ammonium group is preferably a quaternary alkylammonium group from the viewpoint of alkali durability. The quaternary alkylammonium group includes those in which alkyl groups bonded to nitrogen atoms are bonded to each other to form a ring structure, and may be, for example, an azaadamantyl group, a quinuclidinium group, or the like. .
Preferred specific examples of the quaternary ammonium group include groups represented by the following formulas (e-1) to (e-8). Further, preferred specific examples of the imidazolium group include a group represented by the following formula (f-1), furthermore, a group represented by the following formula (f-2) or a group represented by the following formula (f-3) are more preferred.

式中、Ｒ^ｅは、各々独立に、炭素数１～６の、直鎖状、分岐状又は環状のアルキル基であり、Ｒ^ｆは、各々独立に、水素原子、炭素数１～４の直鎖状又は分岐状のアルキル基、若しくは、置換基を有していてもよい芳香族基であり、Ａ^－は１価又は２価以上のアニオンであり、Ｒ^ｅ又はＲ^ｆが複数ある場合、当該複数あるＲ^ｅ又はＲ^ｆは各々同一であっても異なっていてもよい。なお、式中の波線は、Ａｒ^１中の芳香環側に結合する結合手を示す。

In the formula, each R ^e is independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and each R ^f is independently a hydrogen atom or a linear alkyl group having 1 to 4 carbon atoms. A chain or branched alkyl group, or an optionally substituted aromatic group, A ^- is a monovalent or divalent or higher valent anion, and when there are a plurality of R ^e or R ^f , The plurality of R ^e or R ^f may be the same or different. The wavy line in the formula indicates a bond that bonds to the aromatic ring side in ^Ar1 .

Specific examples of the alkyl group for R ^e above include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group and a cyclohexyl group. Specific examples of the alkyl group for R ^f above include a methyl group, an ethyl group, a propyl group, and a butyl group. In addition, examples of the aromatic group for R ^f include a phenyl group and the like, and examples of a substituent for the phenyl group include an alkyl group having 1 to 6 carbon atoms.

The above A ⁻ is preferably an inorganic anion such as chloride ion (Cl ⁻ ), bromide ion (Br ⁻ ), iodide ion (I ⁻ ), hydrogen carbonate ion (HCO ₃ ⁻ ), carbonate ion (CO ₃ ²⁻ ), hydroxide ion (OH ⁻ ), and the like.

The ion-exchange group may be directly bonded to the aromatic ring in Ar ¹ , or may further have a linking group and bond to the aromatic ring via the linking group. Here, the connecting group represents an organic group that connects the acidic group, quaternary ammonium group or imidazolium group of the ion exchange group and the aromatic ring. As the organic group, a linear or branched alkylene group is preferable, and a linear alkylene group is particularly preferable. The number of carbon atoms in the alkylene group can be appropriately adjusted according to the physical properties required for the polymer. For example, by setting the number of carbon atoms in the alkylene group to 20 or less, preferably 16 or less, more preferably 12 or less, the ion exchange group capacity of the present polymer increases. On the other hand, by setting the number of carbon atoms in the alkylene group to 2 or more, preferably 4 or more, and more preferably 6 or more, the present polymer having excellent solubility and swelling resistance can be obtained.
The number of ion-exchange groups in Ar ¹ may be 1 or more, preferably 1-2 from the viewpoint of ion conductivity and polymer stability.

The aromatic ring in Ar ¹ constitutes part of the backbone of the polymer. Since Ar ¹ has an aromatic ring, the polymer is excellent in chemical durability and mechanical strength after film formation.
The aromatic ring may be a condensed ring such as a naphthalene ring, an anthracene ring, etc., in addition to a benzene ring, and a heterocyclic ring containing an oxygen atom (O), a nitrogen atom (N), a sulfur atom (S) ( For example, thiophene, etc.), or a structure in which these rings are linked via a single bond or a linking group. Structures in which multiple rings are linked by single bonds include, for example, biphenyl, terphenyl, and fluorene. Examples of the linking group include linear or branched alkylene groups which may have double bonds, and specific examples include diphenylmethane, triphenylmethane, stilbene, and the like.

The aromatic ring for Ar ¹ may further have a substituent other than the ion-exchange group, in addition to the ion-exchange group described above. Examples of the substituent include an optionally substituted alkyl group having 1 to 20 carbon atoms, and an optionally substituted phenyl group.
Specific examples of the alkyl group include alkyl groups such as methyl group, ethyl group, propyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group and octyl group. etc. In addition, examples of the substituent that the phenyl group may have include an alkyl group having 1 to 6 carbon atoms.

From the viewpoint of excellent mechanical strength, chemical durability, and film-forming properties of the present polymer, Ar ¹ has an ion-exchange group and is a divalent aromatic group that may have a substituent other than the ion-exchange group. Group groups are preferred, and groups represented by any one of the following formulas (a-1) to (a-10) are particularly preferred.
A plurality of Ar ¹ 's in the polymer may be the same or different.

式（ａ－１）～式（ａ－１０）中、
Ｒ^ａは、各々独立に、水素原子、イオン交換基、又はイオン交換基を有しない置換基であり、複数あるＲ^ａは互いに同一であっても異なっていてもよく、Ｒ^ａのうち少なくとも１つはイオン交換基である。
なお波線は、Ａｒ^２に結合する結合手を示す。

In formulas (a-1) to (a-10),
Each R ^a is ^{independently} a hydrogen atom, an ion-exchange group ^, or a substituent having no ion-exchange group; is an ion exchange group.
Note that the wavy line indicates a bond that binds to Ar ² .

Ar ² in each of the above formulas is a group containing an aromatic ring. The aromatic ring in ^Ar2 constitutes part of the backbone of the polymer. Since Ar ² has an aromatic ring, the chemical durability of the polymer and the mechanical strength after film formation are excellent.
Examples of the aromatic ring for Ar ² include the same aromatic rings as those for Ar ¹ above. Moreover, the aromatic ring in Ar ² may have a substituent. As the substituent, a substituent other than an ion exchange group is preferable. Examples of the substituent include an optionally substituted alkyl group having 1 to 20 carbon atoms, and an optionally substituted phenyl group.
Specific examples of the alkyl group include alkyl groups such as methyl group, ethyl group, propyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group and octyl group. etc. In addition, examples of the substituent that the phenyl group may have include an alkyl group having 1 to 6 carbon atoms.

From the viewpoint of excellent mechanical strength, chemical durability, and film-forming properties of the present polymer, Ar ² is preferably a divalent aromatic group that may have a substituent other than an ion-exchange group. A group represented by any one of formulas (b-1) to (b-10) below is preferred.
A plurality of Ar ² in the polymer may be the same or different.

式（ｂ－１）～式（ｂ－１０）中、
Ｒ^ｂは、各々独立に、水素原子又はイオン交換基を有しない置換基であり、複数あるＲ^ｂは互いに同一であっても異なっていてもよい。
なお波線は、Ａｒ^１、Ｘ^１、Ｘ^２又はＢに結合する結合手を示す。

In formulas (b-1) to (b-10),
Each ^Rb is independently a hydrogen atom or a substituent having no ion-exchange group, and a plurality of ^Rb 's may be the same or different.
A wavy line indicates a bond that binds to Ar ¹ , X ¹ , X ² or B.

Ar ³ is a portion corresponding to Ar ¹ in the formula (1). The functional group of Ar ³ is converted into an ion-exchange group in the conversion step described later. Examples of the aromatic ring constituting the aromatic group for Ar ³ include the same as those for Ar ¹ above.
Ar ³ is a group containing an aromatic ring having a functional group convertible to an ion exchange group as a substituent. Ar ³ is, as the substituent, a halogeno group, a sulfonate group (--SO ₃ R ²¹ group), a phosphate group (--R ²¹ ₂ PO ₄ group), a carboxylate group (--COOR ²¹ group), It has an imidazole group (see formula (h-1) below) or an amino group (-NRR').
Here, each R ²¹ is independently an organic group which may have a substituent. Examples of the organic group include an alkyl group and an aryl group. Examples of the substituent include an optionally substituted alkyl group having 1 to 20 carbon atoms, and an optionally substituted phenyl group.

ただし、Ｒ、Ｒ’及びＲ’’は、各々独立に、水素原子又は有機基である。

However, R, R' and R'' are each independently a hydrogen atom or an organic group.

Moreover, R and R' in the above amino group each independently include a hydrogen atom or an organic group. Examples of the organic group for the imidazole group and the amino group include the same organic groups as the optionally substituted organic group for R ²¹ .

The functional group may be directly bonded to the aromatic ring, or may further have a linking group and be bonded to the aromatic ring via the linking group. Here, the linking group includes those similar to Ar ¹ above. The number of ion-exchange groups in Ar ³ may be 1 or more, preferably 1-2 from the viewpoint of ion conductivity and polymer stability.

In addition to the above functional groups, the aromatic ring in Ar ³ may further have substituents other than the above functional groups. Examples of the substituent include the same substituents other than the ion-exchange group for Ar ¹ .

From the viewpoint of excellent mechanical strength, chemical durability, and film-forming properties of the present polymer, Ar ³ is one or more selected from the following formulas (c-1) to (c-10). preferable.

式（ｃ－１）～式（ｃ－１０）中、
Ｒ^ｃは、各々独立に、水素原子、ハロゲノ基、スルホン酸エステル基、リン酸エステル基、カルボン酸エステル基、イミダゾール基及びアミノ基より選択される官能基を有する基、又は前記官能基を有しない置換基であり、複数あるＲ^ｃは互いに同一であっても異なっていてもよく、Ｒ^ｃのうち少なくとも１つは前記官能基である。
なお波線は、Ｘ^１、Ｘ^２又はＢに結合する結合手を示す。

In formulas (c-1) to (c-10),
Each R ^c is independently a group having a functional group selected from a hydrogen atom, a halogeno group, a sulfonate group, a phosphate ester group, a carboxylate ester group, an imidazole group and an amino group, or a group having the functional group A plurality of R ^c may be the same or different, and at least one of R ^c is the above functional group.
A wavy line indicates a bond that binds to X ¹ , X ² or B.

X ¹ and X ² are each independently Br (bromo group) or I (iodo group). Although not particularly limited, X ¹ and X ² are preferably the same, more preferably a bromo group, from the viewpoint of ease of synthesis of compound (2A) and compound (2B).

R ¹ and R ² in formulas (3A) and (3B) are sites capable of coupling reaction with X ¹ and X ² in formulas (2A) and (2B). R ¹ and R ² each independently represent -B(OH) ₂ (boronic acid group), -B(OR ¹¹ ) ₂ (boronic acid ester group), -BF ₃ X ¹¹ (trifluoroborate salt), or , MIDA boronic acid esters. R ¹¹ is an optionally substituted alkyl group, and two R ¹¹ may be linked to form a ring structure. Also, X ¹¹ is a monovalent cation such as an alkali metal ion. Specific examples of R ¹ and R ² include formulas (d-1) to (d-5) below, but are not limited thereto. Note that formula (d-3) is an example in which two R ¹¹ form a ring structure, formula (d-4) is a MIDA boronic acid ester, and formula (d-5) is a trifluoroborate salt. is an example of The wavy line in the formula indicates a bond that bonds to the aromatic ring in Ar ² or Ar ³ . Although not particularly limited, R ¹ and R ² are preferably the same from the viewpoint of ease of synthesis of compound (3A) and compound (3B).

In this production method, the compound (2A) and the compound (3A), or the compound (2B) and the compound (3B) are reacted in the presence of a catalyst represented by the following formula (4). By using the catalyst (4), for example, a polymer having a weight average molecular weight of 100,000 or more can be synthesized.

L is a phosphine ligand, and from the viewpoint of obtaining a polymer with a high weight average molecular weight, among them, tri-tert-butylphosphine, triphenylphosphine, tricyclohexylphosphine, or 2-dicyclohexylphosphino-2′,4 ',6'-Triisopropylbiphenyl is preferred.

The method for synthesizing the catalyst (4) is not particularly limited. For example, 2-aminobiphenyl and palladium (II) acetate are mixed and reacted by heating, and then the ligand L and lithium chloride are mixed. obtained by reacting with

The reaction between compound (2A) and compound (3A) or between compound (2B) and compound (3B) is usually carried out in a solvent such as tetrahydrofuran (THF), preferably in the presence of a base. The base _is not particularly limited, but examples thereof include _K2CO3 , _{Na2CO3 , KF} , _K3PO4 , _{K2HPO4 and} the like. Catalyst (4) acts as L-PdCl in the presence of a base. The reaction conditions may be appropriately adjusted according to the desired molecular weight of the polymer, etc. For example, the reaction temperature is around 60° C. (for example, 40 to 80° C.) and the reaction time is 1 hour or more, so that the weight average molecular weight is 100. ,000 or more polymers can be obtained.

Next, the Ar ³ functional group is converted to an ion-exchange group (conversion step). The conversion step may be performed immediately after the above reaction, or may be performed immediately before using the polymer.
A method for conversion to an ion-exchange group can be appropriately selected according to the functional group. For example, when the functional group is a halogeno group (eg, —Cl), a quaternary ammonium group can be introduced by mixing with trimethylamine and heating. Further, when the functional group is a sulfonate ester group, a phosphate ester group or a carboxylate ester group, by hydrolyzing these groups, ion exchange groups (sulfonic acid group, phosphoric acid group and carboxylic acid group ) can be converted to

ただし、Ａｒ^１はイオン交換基を有する芳香環を含む基であり、
Ａｒ^２は芳香環を含む基である。 According to the method for producing a polymer according to the present invention, it is possible to produce a polymer containing a structural unit represented by the following formula (1) and having a weight average molecular weight of 100,000 or more.

However, Ar ¹ is a group containing an aromatic ring having an ion exchange group,
Ar ² is a group containing an aromatic ring.

Since this polymer does not have an ether bond in its main chain, it has excellent durability in an alkaline environment. The polymer can also have a wholly aromatic hydrocarbon backbone, in which case it is more chemically durable. Since this polymer has a weight average molecular weight of 100,000 or more, the mechanical strength of the membrane produced using this polymer is excellent. In addition, the present polymer is an alternating copolymer of Ar ¹ and Ar ² , and since it has approximately equal ion exchange groups, it can be suitably used for electrolyte membrane applications and the like. Furthermore, since the present polymer does not contain fluorine atoms, it is excellent in handleability during disposal and recycling after use.
Note that Ar ¹ and Ar ² in formula (1) are as described above, and preferred embodiments are also as described above, so descriptions thereof are omitted here. The weight-average molecular weight is determined by gel permeation chromatography (GPC) as a standard polystyrene conversion value.

2. Electrolyte Membrane The electrolyte membrane according to the present invention is characterized by comprising the present polymer. Electrolyte membranes using this polymer are excellent in chemical durability, ionic conductivity and membrane mechanical strength, and can be suitably used as electrolyte membranes for fuel cells and electrolyzers. In addition, the polymer, which has ion-exchange groups, can be easily dissolved in solvents (alcohol, mixed solvents of alcohol and water, etc.) commonly used in the production of membrane electrode assemblies (MEAs) for fuel cells, and has good gas permeability. It can also be used as an electrolyte ionomer in these batteries and electrolytic devices.
In addition, the polymer has a high ionic functional group capacity (IEC) and exhibits very high ionic conductivity. The IEC of the present polymer is preferably 0.5 meq·g ⁻¹ or more and 4.0 meq·g ⁻¹ or less. In addition, the electrolyte membrane using this polymer is excellent in swelling resistance, and the water content at 80° C. is suppressed to 40% or less.

A general film formation method can be applied to the method for producing the electrolyte membrane. For example, the present polymer is dissolved in a solvent capable of dissolving it (for example, dimethyl sulfoxide, alcohol, alcohol aqueous solution, etc.), and a polymer solution is obtained. An electrolyte membrane can be produced by preparing, forming a coating film using a known coating means, and drying.

In this polymer, a proton-conducting electrolyte membrane can be obtained by using an acidic group as the ion-exchange group. Further, by using basic groups such as the quaternary ammonium groups as the ion exchange groups, an anion conductive electrolyte membrane can be obtained.

3. Fuel Cell A fuel cell according to the present invention is characterized by comprising the electrolyte membrane. The electrolyte membrane of the present invention can be suitably used for both solid alkaline fuel cells and polymer electrolyte fuel cells.

When the electrolyte membrane is applied to a solid alkaline fuel cell, an anion conductive electrolyte membrane is used as the electrolyte membrane. The configuration of the solid alkaline fuel cell can be a conventionally known configuration.
For example, a membrane electrode assembly is formed by arranging a cathode on one side of an electrolyte membrane and an anode on the other side, oxygen is supplied to the cathode, fuel is supplied to the anode, and OH generated at the cathode ^is Electricity is generated by moving to the anode through the electrolyte membrane and generating water there.
The fuel can be appropriately selected from conventionally known fuels, and examples thereof include, but are not limited to, hydrogen, methanol, ethanol, ethylene glycol, formate, hydrazine, sodium borohydride, and ammonia.
As a representative example, the reaction at each electrode when hydrogen, methanol and formate are used as fuel is shown.
・Fuel cell using hydrogen Anode: 2OH ⁻ + H ₂ → 2H ₂ O
Cathode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻
・Fuel cell using methanol Anode: 6OH ⁻ + CH ₃ OH → CO ₂ + 5H ₂ O
Cathode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻
・Fuel cell using formate Anode: HCOO ⁻ + 3OH ⁻ → 2H ₂ O + CO ₃ ²⁻ + 2e ⁻
Cathode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻

When the electrolyte polymer is applied to a polymer electrolyte fuel cell, a proton conductive electrolyte membrane is used as the electrolyte membrane. The configuration of the polymer electrolyte fuel cell can be a conventionally known configuration.
For example, a membrane electrode assembly is formed by arranging a cathode on one side of an electrolyte membrane and an anode on the other side, oxygen is supplied to the cathode, fuel is supplied to the anode, and protons generated at the anode are converted into an electrolyte. Electricity is generated by moving through the membrane to the anode where water is generated.
The fuel can be appropriately selected from known ones, and specific examples thereof include those exemplified for the solid alkaline fuel cell.
Reaction at each electrode when hydrogen is used as a representative fuel is shown.
Anode: H ₂ → 2H ⁺ + 2e ⁻
Cathode: O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O

4. Electrolytic Apparatus The electrolyte membrane of the present invention can be suitably used for water electrolysis, other electrolysis techniques (electrolytic methods), and electrolytic apparatuses using these electrolysis methods. The electrolytic device can be configured to have, for example, the electrolyte membrane of the present invention, an anode and a cathode in an electrolytic cell, and electrolyze (oxidation-reduction reaction) an object through the electrolyte membrane of the present invention. can obtain the object.

When the electrolyte membrane is applied to water electrolysis, a proton-conducting or anion-conducting electrolyte membrane is used as the electrolyte membrane. For example, an anode is arranged on one side of a proton-conducting electrolyte membrane and a cathode is arranged on the other side, and protons generated at the anode are transferred to the cathode through the electrolyte membrane and combined with electrons at the cathode. Hydrogen can be obtained. The reaction formula at each electrode is as follows.
Anode: 2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻
Cathode: 2H ⁺ + 2e ⁻ → H ₂

Another electrolysis technique includes an electrolysis technique in which carbon dioxide is electrolyzed to produce formic acid. For example, protons generated at the anode can be transferred to the cathode through the electrolyte membrane and reacted with carbon dioxide supplied to the cathode to obtain formic acid. The reaction formula at each electrode is as follows.
Anode: 2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻
Cathode: CO ₂ + 2H ⁺ + 2e ⁻ → HCOOH

EXAMPLES The present invention will now be described more specifically with reference to examples and comparative examples. In addition, these descriptions do not limit the present invention.

[Example 1: Production of polymer]
A polymer was synthesized according to Scheme 1 shown in FIG. In the following description, the symbols ((i), etc.) in Scheme 1 are appropriately referred to.

<Step (i): Synthesis of Compound 1>

A two-necked flask was charged with n-tetrabutylammonium bromide (648 mg) in an aqueous solution (300 mL) of sodium hydroxide (150 g), and the mixture was stirred under nitrogen. Separately, 2,7-dibromofluorene (4.86 g, 15 mmol) was dissolved in 1-bromohexane (24.8 g, 150 mmol) while heating, and this solution was added to the two-necked flask with a syringe. After reacting for 60 minutes at 85° C. under nitrogen, the solution was allowed to cool to room temperature. The organic layer was extracted with dichloromethane (300 mL), washed with 1M hydrochloric acid (5 mL) and water (200 mL×2). Dichloromethane was evaporated with an evaporator, and unreacted 1-bromohexane was removed at 90° C. under vacuum and reduced pressure. The obtained residue was applied to a silica gel column (developing solvent: hexane) to obtain the target compound 1 (6.50 g, 13.2 mmol).
( ¹ H-NMR spectrum of compound 1)
¹ H-NMR (400 MHz, CDCl ₃ ): δ 7.51 (2H, d), δ 7.45 (4H, m), δ 1.91 (4H, m), δ 1.12 (4H, m), δ 1.05 (8H, m ), δ 0.78 (6H, t), δ 0.59 (4H, m)

<Step (ii): Synthesis of compound 2>

Compound 1 above (4.92 g, 10 mmol), bispinacolato diborane (5.59 g, 22 mmol), potassium acetate (5.89 g, 60 mmol), [1,1'-Bis(diphenylphosphino)ferrocene]palladium(II) dichloromethane The adduct (408 mg, 0.5 mmol) was added to a two-neck eggplant flask, and after vacuum degassing, the atmosphere was replaced with nitrogen. Dimethyl sulfoxide (100 mL) is added with a syringe, and the mixture is reacted under nitrogen at 90° C. for 6 hours. After cooling to room temperature, the organic layer was extracted with chloroform (200 ml) and washed with water (150 ml x 3). After removing chloroform with an evaporator, the residue was applied to a silica gel column (developing solvent: hexane:chloroform=7:3) to obtain the desired compound 2 (3.75 g, 6.4 mmol).
( ¹ H-NMR spectrum of compound 2)
¹ H-NMR (400 MHz, CDCl ₃ ): δ 7.80 (2H, d), δ 7.73 (4H, m), δ 1.99 (4H, m), δ 1.39 (24H, s), δ 1.08 (4H, m ), δ 1.02 (8H, m), δ 0.80 (6H, t), δ 0.55 (4H, m)

<Step (iii): Synthesis of compound 3>

A two-necked flask was charged with n-tetrabutylammonium chloride (417 mg) in an aqueous solution (300 mL) of sodium hydroxide (150 g), and the mixture was stirred under nitrogen. Separately, 2,7-dibromofluorene (4.86 g, 15 mmol) was dissolved in 1,6-dichlorohexane (23.3 g, 150 mmol) with heating, and this solution was added to the two-necked flask with a syringe. After reacting for 60 minutes at 85° C. under nitrogen, the solution was allowed to cool to room temperature. The organic layer was extracted with dichloromethane (300 mL), washed with 1M hydrochloric acid (50 mL) and water (200 mL×2). Dichloromethane was evaporated by an evaporator, and unreacted 1,6-dichlorohexane was removed at 90° C. under vacuum and reduced pressure. The obtained residue was applied to a silica gel column (developing solvent: hexane) to obtain the target compound 3 (6.50 g, 13.2 mmol).
( ¹ H-NMR spectrum of compound 3)
¹ H-NMR (400 MHz, CDCl ₃ ): δ 7.52 (2H, d), δ 7.47-7.43 (4H, m), δ 3.42 (4H, t), δ 1.93 (4H,m), δ 1.60 (4H , m), δ 1.19 (4H, m), δ 1.08 (4H, m), δ 0.58 (4H, m)

<Step (iv): Synthesis of Polymer 1 (PFO-Cl)>

Compound 2 (1173 mg, 2 mmol), Compound 3 (1121 mg, 2 mmol), P(t-Bu3)Pd-G2 catalyst (catalyst represented by compound (4), L is tri-tert-butylphosphine, sigma- Aldrich, 20.5 mg, 4 mmol) was added to a two-necked flask, and the flask was deaerated under vacuum and then replaced with nitrogen. After adding tetrahydrofuran (20 ml) and 10 M potassium phosphate aqueous solution (2 ml) with a syringe, the mixture was reacted at 60° C. for 6 hours under nitrogen. The reaction solution was extracted with chloroform (100 ml) and washed with water (50 ml×3). After removing chloroform with a rotary evaporator, the resulting residue was reprecipitated in methanol. After filtering the precipitate, it was vacuum-dried to obtain the desired polymer 1 (1.19 g).
(GPC measurement result of polymer 1)
GPC ( _CHCl3 ): Mn=46000, Mw=123000, Mw/Mn=2.67
In addition, Mn is a number average molecular weight, Mw is a weight average molecular weight.

<Step (V): Synthesis of Polymer 2 (PFO-C ₆ -TMA)>

The above polymer 1 (500 mg) was dissolved in chlorobenzene (20 ml) in a 50 ml vial, 3.2 M trimethylamine methanol solution (1 ml) was added, the lid was closed, and reaction was allowed to proceed at 105° C. for 12 hours. After cooling the solution to room temperature, a dimethylsulfoxide solution (20 ml) and a 3.2 M trimethylamine methanol solution (1 ml) were added, the lid was closed again, and reaction was allowed to proceed at 105° C. for 12 hours. After cooling to room temperature, the reaction solution was transferred to a 100 ml round-bottomed flask and concentrated by removing chlorobenzene with an evaporator. Dimethyl sulfoxide (30 ml) and 3.2 M trimethylamine methanol solution (1 ml) were added to the residue and reacted at 105° C. for 6 hours. After cooling to room temperature, the reaction solution was transferred to a 100 ml round-bottomed flask and dried completely with an evaporator. The dried solid was washed with water, collected by filtration, and then vacuum dried to obtain the desired polymer 2 (505 mg).
( ¹ H-NMR spectrum of polymer 2)
¹ H-NMR (400 MHz, CD ₃ OD): δ 7.94 (4H, br), δ 7.78 (8H, br), δ 3.24 (4H, br), δ 3.05 (18H,s), δ 2.2 (8H, br), δ 1.64 (8H, br), δ 1.17 (16H, br), δ 0.82 (14H, br)

なお、ｎ及びｍは繰り返し単位であることを示す。 [Comparative Example 1]
As a comparative example, the following polymer (PPO-TMA) was prepared.

Note that n and m indicate repeating units.

<Evaluation>
[Manufacturing of Electrolyte Membrane]
For each of Polymer 2 of Example 1 and Polymer of Comparative Example 1, a solution (20 mg/ml) in dimethylsulfoxide was prepared. Each of the solutions was cast on a glass substrate and dried by heating at 100° C. to form a film. Then, the substrate was immersed in water to separate the polymer film from the substrate, and after washing with pure water at 80° C., an electrolyte membrane with a thickness of 25 μm was obtained.

[Swelling and ionic conduction property evaluation]
Ionic conductivity was measured for each of the resulting electrolyte membranes. The ionic conductivity was calculated from the electrical resistance value measured by AC impedance measurement. In-plane AC impedance measurement was carried out by the four-probe method using platinum electrodes. The distance between the electrodes for measuring the voltage was 5 mm to 15 mm, and the electrode on the low current side and the electrode on the low voltage side were brought into contact with the opposite side of the electrolyte membrane with respect to the electrode on the high current side and the electrode on the high voltage side. The electrolyte membrane was sandwiched between two sets of high-density polyethylene substrates together with the platinum electrodes, and the ends were fixed with screws. The electrolyte membrane is placed in a constant temperature bath (Espec SH-241 Bench-Top Type Temperature & Humidity chamber), and each temperature (40°C to 80°C) is kept constant at a humidity of 100RH, and then stabilized for at least 3 hours before measurement. did Solartron 1260 (manufactured by Solartron, UK) was used as an AC impedance measuring device, AC amplitude was 10 to 100 mV, and the frequency was scanned from 1000,000 Hz to 1 Hz. The measurement results are shown in the graph of FIG.
In addition, the ionic functional group capacity (IEC), water content at 25° C. and 80° C., and dimensional change rate due to water content were measured for each of the electrolyte membranes. The results are shown in the table of FIG.

The electrolyte membrane obtained from Polymer 2 of Example 1 also exhibited excellent ionic conductivity with good swelling resistance as compared to the electrolyte membrane of Comparative Example 1 having an equivalent IEC.

[Chemical durability evaluation]
Polymer 2 of Example 1 was immersed in an 8M NaOH aqueous solution maintained at 80° C. for one week. ¹ H-NMR spectra of the polymer before and after immersion are shown in FIG. FIG. 3 is a superimposition of the spectra before and after immersion. The peaks derived from hydrogen atoms a and b in FIG.

As described above, according to the method for producing a polymer of the present invention, a polymer having no fluorine atoms and ether bonds in the polymer and having a weight average molecular weight of 100,000 or more can be obtained. It was shown that the material was manufactured well, exhibited excellent ionic conductivity, and had excellent swelling resistance and chemical durability.

Claims (9)

A method for producing a polymer containing a structural unit represented by the following formula (1),
A compound represented by the following formula (2A) and a compound represented by the following formula (3A), or
A compound represented by the following formula (2B) and a compound represented by the following formula (3B),
A method for producing a polymer, comprising reacting in the presence of a catalyst represented by the following formula (4).

however,
Ar ¹ is a group containing an aromatic ring with an ion exchange group,
Ar ² is a group containing an aromatic ring,
Ar ³ is a group containing an aromatic ring having a functional group selected from a halogeno group, a sulfonate group, a phosphate group, a carboxylate group, an imidazole group and an amino group;
X ¹ and X ² are each independently Br or I;
R ¹ and R ² are each independently -B(OH) ₂ , -B(OR ¹¹ ) ₂ , -BF ₃ X ¹¹ , or MIDA boronic acid ester;
R ¹¹ is an optionally substituted alkyl group, and two R ¹¹ may be linked to form a ring structure,
X ¹¹ is a monovalent cation,
L is a phosphine ligand. 2. The method for producing a polymer according to claim 1, wherein the reaction is carried out in the presence of a base. 3. The method for producing a polymer according to claim 1, wherein the catalyst acts as L-PdCl during the reaction. The phosphine ligand is at least one selected from tri-tert-butylphosphine, triphenylphosphine, tricyclohexylphosphine, and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl A method for producing the polymer according to any one of claims 1 to 3. A polymer comprising a structural unit represented by the following formula (1) and having a weight average molecular weight of 100,000 or more.

however,
Ar ¹ is a group containing an aromatic ring with an ion exchange group,
Ar ² is a group containing an aromatic ring. 6. The polymer of claim 5, which has no fluorine atoms. An electrolyte membrane comprising the polymer according to claim 5 or 6. A fuel cell comprising the electrolyte membrane according to claim 7 . An electrolytic device comprising the electrolyte membrane according to claim 7 .

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