JP2020169287A - Compound, precursor, electrolyte membrane, fuel cell, water electrolysis and electrolytic technique - Google Patents

Abstract

To provide a compound having excellent chemical durability, and a precursor suitable for producing the compound, an electrolyte membrane including the compound and having excellent chemical durability, a fuel cell including the electrolyte membrane, water electrolysis and an electrolytic technique.SOLUTION: A compound has a repeating unit represented by formula (1), where, R1 is a group having an ion exchange group, Ar1 is an optionally substituted divalent aromatic group, where a plurality of R1 and Ar1 may be the same or different.SELECTED DRAWING: None

Description

The present invention relates to compounds, precursors, electrolyte membranes, fuel cells, water electrolysis and electrolysis techniques.

Electrolyte membranes are used in various fuel cells such as polymer electrolyte fuel cells and solid alkaline fuel cells, and in various electrolysis technologies such as water electrolysis. The electrolyte membrane is required to have durability that can withstand long-term use.

In Patent Document 1, the present inventors have described a specific hydrophilic portion and a specific hydrophobic portion as proton conductive materials for an electrolyte membrane having high swelling resistance and high proton conductivity in which ion exchange groups are accumulated at high density. Discloses a proton conductive material having a repeating unit containing a specific cyclic compound in at least one of the hydrophilic part and the hydrophobic part. The proton conductive material has a structure in which a hydrophilic portion and a hydrophobic portion are bonded via an ether bond.

Further, in Patent Document 2, the present inventors have described a divalent aromatic group having an ionic functional group as a polymer for an electrolyte membrane having excellent chemical durability and excellent solubility in a solvent. A polymer having a structure in which a spirobifluorene skeleton is alternately repeated is disclosed.

Japanese Unexamined Patent Publication No. 2016-44242 JP-A-2018-135487

The present inventors have obtained the knowledge that the proton conductive material described in Patent Document 1 may be deteriorated by cleaving the ether bond of the main chain in an alkaline environment.
The polymer of Patent Document 2 has excellent chemical durability, but its production requires a multi-step synthesis step, and a material for an ion conductive membrane having more excellent productivity is required.

The present invention solves such a problem, and a compound having excellent chemical durability, a precursor suitable for producing the compound, an electrolyte membrane having excellent chemical durability using the compound, and the electrolyte. It is an object of the present invention to provide a fuel cell using a membrane, water electrolysis and electrolysis technology.

The first compound according to the present invention has a repeating unit represented by the following formula (1).

但し、式（１）中、
Ｒ^１は、イオン交換基を有する基であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であって、
複数あるＲ^１及びＡｒ^１は各々同一であっても異なっていてもよい。

However, in equation (1),
R ¹ is a group having an ion exchange group and
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
The plurality of R ¹ and Ar ¹ may be the same or different from each other.

In one embodiment of the first compound, at least one of the repeating units represented by the formula (1) is a repeating unit represented by the following formula (1a).

但し、式（１ａ）中、
Ｒ^２は、イオン交換基であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であり、
ｐは１以上２０以下の整数であって、
複数あるＲ^２、Ａｒ^１及びｐは、各々同一であっても異なっていてもよい。

However, in equation (1a),
R ² is an ion exchange group and
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
The plurality of R ² , Ar ¹ and p may be the same or different from each other.

In one embodiment of the first compound, the ion exchange group is quaternary ammonium.

The second compound according to the present invention is a compound represented by the following formula (3).

但し、式（３）中、
Ｒ^２は、イオン交換基であり、
ｐは１以上２０以下の整数であり、
ｑは０以上５以下の整数であり、
Ｒ^３は１価の有機基、又は２つのＲ^３が連結した環構造であって、
Ｒ^３が複数ある場合、当該複数あるＲ^３は同一であっても異なっていてもよい。

However, in equation (3),
R ² is an ion exchange group and
p is an integer of 1 or more and 20 or less,
q is an integer of 0 or more and 5 or less,
R ³ is a monovalent organic group or a ring structure in which two R ^3s are linked.
If there are a plurality of R ^3, the plurality of R ³ may be be the same or different.

In one embodiment of the second compound, the ion exchange group is quaternary ammonium.

The precursor according to the present invention is the precursor for producing the first compound, and has a repeating unit represented by the following formula (4).

但し、式（４）中、
Ｘは、水素原子、又はハロゲン原子であって、複数あるＸのうち少なくとも一つはハロゲン原子であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であり、
ｐは１以上２０以下の整数であって、
複数あるＸ、Ａｒ^１及びｐは、各々同一であっても異なっていてもよい。

However, in equation (4),
X is a hydrogen atom or a halogen atom, and at least one of a plurality of Xs is a halogen atom.
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
A plurality of X, Ar ¹ and p may be the same or different from each other.

The electrolyte membrane according to the present invention contains the first compound or the second compound.

The fuel cell according to the present invention is characterized by including the electrolyte membrane.
Further, the water electrolysis and electrolysis technology according to the present invention is characterized by using the electrolyte membrane.

According to the present invention, a compound having excellent chemical durability, a precursor suitable for producing the compound, an electrolyte membrane having excellent chemical durability using the compound, a fuel cell using the electrolyte membrane, and water. Electrolysis and electrolysis techniques can be provided.

It is a scheme which shows the synthetic route of the polymer of Example 1. It is a scheme which shows the synthetic route of the polymer of Example 2. It is a scheme which shows the synthetic route of the polymer of Example 3. 1 ¹ H-NMR spectrum of compound 1. ^{1 1} H-NMR spectrum of compound 2. ^{1 1} H-NMR spectrum of compound 3. ^{1 1} H-NMR spectrum of compound 4. ^{1 1} H-NMR spectrum of compound 5. ^{1 1} H-NMR spectrum of compound 6. ^{1 1} H-NMR spectrum of compound 7. ^{1 1} H-NMR spectrum of compound 8. ^{1 1} H-NMR spectrum of compound 9. ^{1 1} H-NMR spectrum of compound 10. ^{1 1} H-NMR spectrum of compound 11. ¹ H-NMR spectrum of Polymer (C3) -Br. ^{1 1} H-NMR spectrum of Polymer (C3) -TMA. ¹ H-NMR spectrum of Polymer (C4) -Br. ^{1 1} H-NMR spectrum of Polymer (C4) -TMA. FIG. 3 is a ¹ H-NMR spectrum of Polymer (C5) -Br. ^{1 1} H-NMR spectrum of Polymer (C5) -TMA. ¹ H-NMR spectrum before and after the alkali durability test of the polymer of Example 1. ¹ H-NMR spectrum before and after the alkali durability test of the polymer of Example 2. ¹ H-NMR spectrum before and after the alkali durability test of the polymer of Example 3. It is a graph which shows the measurement result of the ionic conductivity of the electrolyte membrane obtained by forming the polymer of Examples 1 to 3 into a film.

1. 1. First Compound The first compound according to the present invention has a repeating unit represented by the following formula (1) (hereinafter, may be referred to as a constituent unit (1)).

但し、式（１）中、
Ｒ^１は、イオン交換基を有する基であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であって、
複数あるＲ^１及びＡｒ^１は各々同一であっても異なっていてもよい。

However, in equation (1),
R ¹ is a group having an ion exchange group and
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
The plurality of R ¹ and Ar ¹ may be the same or different from each other.

The first compound is a polymer having two or more of the structural units (1), and the main chain is a fully aromatic compound. Since the first compound has such a structure, it has excellent durability against alkalis and radicals.

Ar ¹ of the structural unit (1) is a divalent aromatic group which may have a substituent. Aromatic ring constituting the aromatic groups constituting the main chain of the polymer together with the benzene ring having R ^1. The aromatic ring constituting the aromatic group may be a fused ring such as a naphthalene ring or an anthracene ring in addition to the benzene ring, or a chain such as biphenyl or terphenyl in which the benzene ring is linked in a chain. It may be a polycyclic hydrocarbon. Further, the aromatic ring may be a heterocycle containing O (oxygen atom), N (nitrogen atom) and S (sulfur atom).

The divalent aromatic group in Ar ¹ is preferably a phenylene group, a biphenylene group, or a terphenylene group, preferably a p-phenylene group (lower formula (Ar-1)) or a 4,4'-biphenylene group (lower formula (lower formula (lower formula)). Ar-2)) or 4,4''-terphenylene group (formula (Ar-3) below) is more preferable.

但し、上式中、Ｒは式（１）におけるＡｒ^１が有していてもよい置換基であり、ｒは０〜４の整数であり、複数あるＲ及びｒは同一であっても異なっていてもよい。

However, in the above equation, R is a substituent that Ar ¹ in the equation (1) may have, r is an integer of 0 to 4, and a plurality of R and r are different even if they are the same. You may.

When Ar ¹ is a p-phenylene group, a 4,4'-biphenylene group, or a 4,4''-terphenylene group, the first compound has a zigzag arrangement of the main chain skeleton as shown in the following formula. Cheap. The following formula typically shows the case where Ar ¹ is a p-phenylene group, but the same applies to a 4,4'-biphenylene group or a 4,4''-terphenylene group. As shown in the following formula, in the first compound, the main clavicle skeleton is likely to be arranged in a zigzag shape, and each R ¹ is likely to be arranged outside the fold of the skeleton. Therefore, intramolecular aggregation due to folding back of the main chain is suppressed. Further, each R ¹ is arranged at a position relatively distant from each other, and aggregation of ion exchange groups is suppressed. As a result, it becomes a polymer capable of forming an electrolyte membrane having excellent ionic conductivity.

但し、上式中、Ｒ^１は構成単位（１）と同様である。

However, in the above equation, R ¹ is the same as the structural unit (1).

Examples of the substituent that Ar ¹ may have include a hydrocarbon group having 1 to 5 carbon atoms and a halogen atom which may have a substituent. Specific examples of the hydrocarbon group include a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group and the like, and may further have a halogen atom as a substituent. Examples of the halogen atom include F, Cl, Br and I, and Br or I is preferable. Further, the hydrocarbon groups of Ar ¹ may be linked to form a ring structure.
A preferred specific example of Ar ¹ is shown below.

但し、Ｒは水素原子、ハロゲン原子、又は置換基を有していてもよい炭素数１〜２０のアルキル基であり、複数あるＲは同一であっても異なっていてもよい。炭素数１〜２０のアルキル基が有していてもよい置換基としては、ハロゲン原子が挙げられ、中でも、Ｂｒ又はＩが好ましい。

However, R is an alkyl group having 1 to 20 carbon atoms which may have a hydrogen atom, a halogen atom, or a substituent, and a plurality of Rs may be the same or different. Examples of the substituent that the alkyl group having 1 to 20 carbon atoms may have include a halogen atom, and among them, Br or I is preferable.

R ¹ is a group having an ion exchange group. In the present invention, the ion exchange group refers to a functional group having dissociative properties and capable of ion exchange, and contributes to ion conduction of the first compound. The ion exchange group in R ¹ can be appropriately selected from such functional groups according to the application. When imparting proton conductivity to the first compound, the ion-exchange group is an acid group are preferable, and a sulfo group (-SO 3 _H group), a phosphoric acid group (-HPO ₃ group), or a carboxy group ( -COOH group) is more preferable, and a sulfo group is further preferable. Further, when imparting anionic conductivity to the first compound, the ionic functional group is preferably a quaternary ammonium group or an imidazolium group, and more preferably a quaternary ammonium group. The quaternary ammonium group is preferably a quaternary alkylammonium group. The quaternary alkylammonium group also includes those in which alkyl groups bonded to a nitrogen atom are bonded to each other to form a ring structure. Specific examples thereof include an azaadamantyl group and a quinucridinium group.

When imparting anion conducting the first compound, the ion-exchange group is preferably a substituent selected from the following formula (R 1 ^-1) ~ the formula (R 1 ^-4).

但し、
Ｒ^１１〜Ｒ^１３は、各々独立に、炭素原子数が１以上６以下の、直鎖、分岐、又は環状のアルキル基であり、
Ｒ^１４〜Ｒ^１７は、各々独立に、炭素原子数１以上４以下のアルキル基、フェニル基、又は、置換基としてメチル基を有してもよいフェニル基であり、
Ａ⁻は、１価、又は２価以上のアニオンである。

However,
R ^{11 to} R ¹³ are linear, branched, or cyclic alkyl groups having 1 or more and 6 or less carbon atoms, respectively.
R ^{14 to} R ¹⁷ are phenyl groups which may independently have an alkyl group having 1 or more and 4 or less carbon atoms, a phenyl group, or a methyl group as a substituent.
A ⁻ is a monovalent or divalent or higher anion.

Suitable specific examples of the linear, branched, or cyclic alkyl group having 1 or more and 6 or less carbon atoms in R ^{11 to} R ¹³ include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Examples include a hexyl group and a cyclohexyl group. Examples of the alkyl group having 1 or more and 4 or less carbon atoms in R ^{14 to} R ¹⁷ include a methyl group, an ethyl group, a propyl group, a butyl group and the like. Moreover, as a phenyl group which may have a methyl group as a substituent, 3,5-dimethylphenyl group and the like can be mentioned.
Further, A in the formula ^(R 1 -1) ~ formula ^(R 1 -4) ^- is a counter anion is not limited to monovalent ones, may be of 2 or more valences. The A ⁻ is preferably an inorganic anion, and specifically, a chloride ion (Cl ⁻ ), a bromide ion (Br ⁻ ), an iodide ion (I ⁻ ), and a hydrogen carbonate ion (HCO ₃ ⁻ ). , Bicarbonate ion (CO ₃ ^2- ), hydroxide ion (OH ⁻ ) and the like.

The group having an ion-exchange group in R ¹ may be the above-mentioned ion-exchange group itself and may be directly bonded to the benzene ring, or may be bonded to benzene via an alkylene group. When it has an alkylene group, examples of the alkylene group include a linear or branched alkylene group having 1 to 30 carbon atoms.
When R ¹ having an alkylene group, ^{R 1} is preferably a group represented by the following formula ^(R 1 -1).

但し、Ｒ^２は、イオン交換基であり、ｐは１以上２０以下の整数である。また、波線はＲ^１とベンゼン環との結合部分を示す。

However, R ² is an ion exchange group, and p is an integer of 1 or more and 20 or less. The wavy line shows the bonding portion between R ¹ and the benzene ring.

In the group represented by the above formula (R 1 ^-1), the alkylene group, the carbon atom adjacent to a benzene ring constituting the main chain has a quaternary carbon. Therefore, the π-π stacking that may occur between the molecules of the first compound is suppressed. As a result, the first compound suppresses intermolecular aggregation and becomes easily dissolved in a solvent, and is excellent in handleability at the time of forming an electrolyte membrane, for example.
R ² is the same as the ion exchange group described in R ¹ .
p represents ^{(R carbon number from ² to quaternary carbon) -1}, it may be appropriately adjusted within the range of 1 to 20. Of these, 1 to 15 are preferable, 1 to 12 are more preferable, and 1 to 6 are even more preferable. The method for adjusting p (carbon chain length) is not particularly limited, but as an example, the step (i) of FIG. 3 described later may be repeated. According to step (i) of FIG. 3, a carboxylic acid having one longer carbon chain can be synthesized.
Since Ar ¹ and R ² in the formula (1a) are as described above, the description thereof is omitted here.

That is, in the first compound, it is preferable that at least one of the repeating units represented by the formula (1) is a repeating unit represented by the following formula (1a).

但し、式（１ａ）中、
Ｒ^２は、イオン交換基であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であり、
ｐは１以上２０以下の整数であって、
なお、式（１ａ）中の各符号は前述の通りである。

However, in equation (1a),
R ² is an ion exchange group and
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
Each reference numeral in the formula (1a) is as described above.

(Other building blocks)
The first compound may be a polymer having only the above-mentioned structural unit (1), or may be a copolymer having another structural unit.
Examples of the other structural unit include a repeating unit (also referred to as a structural unit (2)) represented by the following equation (2).

但し、式（２）中、
Ｒ^１０は、置換基を有していてもよい炭素数１〜３０のアルキル基であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であって、
複数あるＲ^１０及びＡｒ^１は各々同一であっても異なっていてもよい。

However, in equation (2),
R ¹⁰ is an alkyl group having 1 to 30 carbon atoms which may have a substituent.
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
The plurality of R ¹⁰ and Ar ¹ may be the same or different from each other.

Ar ¹ in the structural unit (2), the description thereof will not be here because it is similar to Ar ¹ of the structural units described above (1).
Examples of the alkyl group of R ¹⁰ include a linear or branched alkylene group having 1 to 30 carbon atoms. Examples of the substituent contained in the alkyl group of R ¹⁰ include a halogen atom, with F, Cl, Br and I being preferred, and Br or I being more preferred.

Among them, from the viewpoint of inhibiting the [pi-[pi stacking of the main chain, it is preferred that R ¹⁰ is a group represented by the following formula (R ^{10 -1).}

但し、Ｘは、水素原子又はハロゲン原子であり、ｐは１以上２０以下の整数である。また、波線はＲ^１とベンゼン環との結合部分を示す。

However, X is a hydrogen atom or a halogen atom, and p is an integer of 1 or more and 20 or less. The wavy line shows the bonding portion between R ¹ and the benzene ring.

That is, the structural unit (2) is preferably the structural unit represented by the following formula (2a).

但し、式（２ａ）中、
Ｘは、水素原子又はハロゲン原子であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であり、
ｐは１以上２０以下の整数であって、
複数あるＸ、Ａｒ^１及びｐは、各々同一であっても異なっていてもよい。
なお、式（２ａ）中の各符号の詳細は前述の通りである。

However, in equation (2a),
X is a hydrogen atom or a halogen atom,
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
A plurality of X, Ar ¹ and p may be the same or different from each other.
The details of each code in the formula (2a) are as described above.

When the first compound has a structural unit (2), the order of linking the structural unit (1) and the structural unit (2) is not particularly limited. It may be a random copolymer, a block copolymer in which the constituent units (1) and the constituent units (2) are arranged in blocks, or an alternating copolymer in which the constituent units (1) and the constituent units (2) are arranged alternately. Often, these may be partially combined.

When the first compound has a constituent unit (2), the ratio of the constituent unit (1) may be appropriately adjusted according to the ion exchange ability required for the electrolyte membrane to be produced. The proportion of the constituent unit (1) in the total constituent units of the first compound is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more. ..

The weight average molecular weight of the first compound may be prepared, for example, in the range of 2,000 to 500,000, preferably 5,000 to 200,000, and more preferably 10,000 to 200,000. The weight average molecular weight is a polystyrene-equivalent value measured by GPC (gel permeation chromatography).

(Method for producing the first compound)
The method for synthesizing the first compound is not particularly limited, but a preferable example is the method of the following scheme (A).

但し、スキーム（Ａ）中のＸ^１はハロゲン原子を表し、Ｘ、Ａｒ^１、及びｐは前述のとおりである。Ｘ^１のハロゲン原子としてはＢｒが好ましい。

However, X ¹ in the scheme (A) represents a halogen atom, and X, Ar ¹ , and p are as described above. The halogen atom of X ¹ Br is preferred.

In the example of the above scheme (A), first, a compound (A) corresponding to the formula (1a) and a compound (B) having a desired Ar ¹ are prepared, and the compound (A) and the compound (B) are combined. Polymerization is carried out to obtain a polymer having a repeating unit (also referred to as a constituent unit (4)) represented by (4). The first compound is then obtained by introducing the desired ion exchange group into the building block (4). An ionic functional group is introduced into the structural unit (4) in which X is a halogen atom. In the above scheme A, quaternary ammonium is introduced, but other ionic functional groups can be introduced accordingly.
The details of each of the above reaction conditions can be referred to in Examples described later, and thus the description thereof will be omitted here.

The compound (4) is a novel compound and is a precursor suitable for synthesizing the first compound.

但し、式（４）中、
Ｘは、水素原子、又はハロゲン原子であって、複数あるＸのうち少なくとも一つはハロゲン原子であり、
Ａｒ^１は置換基を有していてもよい２価の芳香族基であり、
ｐは１以上２０以下の整数であって、
複数あるＸ、Ａｒ^１及びｐは、各々同一であっても異なっていてもよい。

However, in equation (4),
X is a hydrogen atom or a halogen atom, and at least one of a plurality of Xs is a halogen atom.
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
A plurality of X, Ar ¹ and p may be the same or different from each other.

2. Second Compound The second compound according to the present invention is a compound represented by the following formula (3).

但し、式（３）中、
Ｒ^２は、イオン交換基であり、
ｐは１以上２０以下の整数であり、
ｑは０以上５以下の整数であり、
Ｒ^３は１価の有機基、又は２つのＲ^３が連結した環構造であって、
Ｒ^３が複数ある場合、当該複数あるＲ^３は同一であっても異なっていてもよい。

However, in equation (3),
R ² is an ion exchange group and
p is an integer of 1 or more and 20 or less,
q is an integer of 0 or more and 5 or less,
R ³ is a monovalent organic group or a ring structure in which two R ^3s are linked.
If there are a plurality of R ^3, the plurality of R ³ may be be the same or different.

In the second compound, the carbon atom adjacent to the benzene ring is quaternary carbon. Therefore, π-π stacking that can occur between molecules is suppressed. As a result, the second compound suppresses intermolecular aggregation, becomes easily dissolved in a solvent, and has excellent handleability.

In the second compound, it is described here for R ² and p are the same as R ² and p in the first compound will be omitted.

Examples of the organic group in R ³ include an alkyl group which may have a substituent or an aryl group which may have a substituent.
Examples of the alkyl group include a linear or branched alkyl group having 1 to 20 carbon atoms, and among them, a linear or branched alkyl group having 1 to 8 carbon atoms is preferable, and a direct group having 1 to 5 carbon atoms is preferable. Chain or branched alkyl groups are preferred. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group and the like. Examples of the substituent which the alkyl group may have include a halogen atom and a phenyl group, and the phenyl group may further have an alkyl group or a halogen atom as the substituent.
Further, examples of the aryl group include a phenyl group and a naphthyl group. Examples of the substituent which the aryl group may have include an alkyl group having 1 to 5 carbon atoms, a halogen atom and the like, and the alkyl group may further have a halogen atom as a substituent.
The ring structure in which two R ^3s are connected means that R ³ contains a carbon atom contained in the benzene ring in the formula (3) to form a ring structure, specifically, the formula (3). It means that a naphthalene ring, anthracene ring, etc. are formed including the benzene ring inside.

The R ^3, an alkyl group having 1 to 5 carbon atoms, a phenyl group, or a naphthalene ring bonded two R ^3, it is preferable to form an anthracene ring.

A suitable specific example of the second compound is shown.

但し、Ｒ^２及びｐは前述のとおりである。

However, R ² and p are as described above.

(Method for producing the second compound)
The method for synthesizing the second compound is not particularly limited, and examples thereof include the method of the following scheme (B).

但し、ここでのＸはハロゲン原子であり、Ｒ^３、ｐ及びｑは前述のとおりである。
なお、上各反応条件の詳細は、後述の実施例のモノマー合成と同様であり、当該実施例を参照できる。

However, X here is a halogen atom, and R ³ , p and q are as described above.
The details of the above reaction conditions are the same as those of the monomer synthesis of Examples described later, and the Examples can be referred to.

3. 3. Electrolyte Membrane The electrolyte membrane according to the present invention is characterized by containing the first compound or the second compound. The electrolyte membrane has excellent durability against alkalis and radicals, and can be suitably used as an electrolyte membrane for fuel cells, water electrolysis, and electrolysis technology.

When the first compound is used, the electrolyte membrane is formed by dissolving the first compound in a soluble solvent to prepare a solution of the first compound, forming a coating film using a known coating means, and drying the film. Can be manufactured.
When the second compound is used, for example, a solution of the second compound is prepared, the solution is immersed in the porous membrane, and the second compound is supported on the porous membrane to form an electrolyte membrane. Can be done.

By using the ion exchange group as an acidic group in the first compound or the second compound, a proton-conducting electrolyte membrane can be obtained. Further, by using the ion exchange group as the quaternary ammonium group, an anion conductive electrolyte membrane can be obtained.

4. Fuel cell The fuel cell according to the present invention is characterized by including the electrolyte membrane of the present invention. 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 known configuration.
For example, a membrane electrode assembly in which a cathode is arranged on one surface of an electrolyte membrane and an anode is arranged on the other surface is formed, oxygen is supplied to the cathode, fuel is supplied to the anode, and OH ⁻ generated at the cathode is generated. Power is generated by moving to the anode via an electrolyte membrane and generating water there.
The fuel can be appropriately selected from known fuels, and examples thereof include, but are not limited to, hydrogen, methanol, ethanol, ethylene glycol, formate, hydrazine, sodium borohydride, and ammonia.
Representatively, the reaction at each pole when hydrogen, methanol and formate are used as fuel is shown.
○ Fuel cell using hydrogen Anode: 2OH ⁻ + H ₂ → H ₂ O
The _{cathode: O 2 + 2H 2 O +} 4e - → 4OH -
○ Fuel cell using methanol Anode: 6OH ⁻ + CH ₃ OH → CO ₂ + 5H ₂ O
The _{cathode: O 2 + 2H 2 O +} 4e - → 4OH -
○ Fuel cell using formate Anode: HCOO ⁻ + 3OH ⁻ → 2H ₂ O + CO ₃ ^2-2 + 2e ⁻
The _{cathode: O 2 + 2H 2 O +} 4e - → 4OH -

When the electrolyte membrane is applied to a polymer electrolyte fuel cell, an aproton conductive electrolyte membrane is used as the electrolyte membrane. The structure of the polymer electrolyte fuel cell can be a known structure.
For example, a membrane electrode assembly in which a cathode is arranged on one surface of an electrolyte membrane and an anode is arranged on the other surface is formed, oxygen is supplied to the cathode, fuel is supplied to the anode, and protons generated at the anode are electrolytes. It moves to the anode through the membrane, where it generates water to generate power.
The fuel can be appropriately selected from known fuels, and specific examples thereof include the same fuels as those exemplified in the solid alkaline fuel cell.
As a representative, the reaction at each pole when hydrogen is used as a fuel is shown.
Anode: H ₂ → 2H ⁺ + 2e ^{−
_{Cathode: O 2 + 4H + + 4e}} - → 2H 2 O

5. Water electrolysis and electrolysis technology The electrolyte membrane of the present invention can be suitably used for water electrolysis and other electrolysis technologies.

When the electrolyte membrane is applied to water electrolysis, a proton conductive or anion conductive electrolyte membrane is used as the electrolyte membrane. For example, an anode is placed on one surface of a proton-conducting electrolyte membrane, and a cathode is placed on the other surface. Protons generated at the anode are moved to the cathode via the electrolyte membrane and bonded to electrons at the cathode. Hydrogen can be obtained. The reaction formula at each pole is as follows.
Anode: H ₂ O → O ₂ + 4H ⁺ + 4e ^{−
Cathode: 2H + + 2e - → H} 2

Further, as another electrolysis technique, there is an electrolysis technique for electrolyzing carbon dioxide to generate formic acid. For example, formic acid can be obtained by moving the protons generated at the anode to the cathode via the electrolyte membrane and reacting with carbon dioxide supplied to the cathode. The reaction formula at each pole is as follows.
Anode: H ₂ O → O ₂ + 4H ⁺ + 4e ^{−
_{Cathode: CO 2 + 2H + + 2e}} - → HCOOH

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. It should be noted that these descriptions do not limit the present invention.

Three polymers were synthesized according to schemes 1-3 shown in FIGS. 1-3. Each synthesis method will be described with reference to FIGS. 1 to 3. In the following, for example, step (i) of Scheme 1 is described as step (1-i), and other steps follow this.

<Step (1-i): Synthesis of compound 1>
Acetone with 3,5-dibromophenylboronic acid (14.0 g, 50 mmol), 3-methylcrotonic acid (6.0 g, 60 mmol), palladium acetate (0) (561 mg, 2.5 mmol), bipyridine (781 mg, 5 mmol) It was mixed with a (50 mL) / water (150 mL) mixed solvent and reacted at 80 ° C. in the air for 48 hours. The solvent in the reaction solution was evaporated by an evaporator and concentrated, and then the residue was dissolved in chloroform (300 mL). The organic layer is washed several times with water (100 mL × 2) in a separating funnel and then dried over magnesium sulfate. Magnesium sulfate was removed by filtration, and chloroform was evaporated with an evaporator to obtain a crude product (17.4 g), which was used as it was in the next reaction. The crude product was purified by a silica gel column (developing solvent: chloroform: hexane = 1: 1) to obtain the desired compound 1 having high purity. The ¹ H-NMR spectrum of Compound 1 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.51 (1H, s), δ 7.42 (2H, d), δ 2.63 (2H, s), δ 1.43 (6H, s)

<Step (1-ii): Synthesis of compound 2>
Compound 1 (6.72 g, 20 mmol) was dissolved in dehydrated tetrahydrofuran (20 mL). The borane dimethyl sulfide complex (5.7 mL, 60 mmol) was slowly added with a syringe, and then reacted under nitrogen for 3 hours. The reaction solution was concentrated on an evaporator and then dissolved in dichloromethane (150 mL). A 4M sodium hydroxide solution (30 mL) was slowly added to this solution, followed by stirring for 30 minutes. The organic layer was collected with a separating funnel and washed with water (50 mL × 3). After removing dichloromethane, the residue was subjected to a silica gel short column (developing solvent: hexane, then hexane: chloroform = 1: 1) to obtain the desired compound 2 (5.86 g, 18.2 mmol). The ¹ H-NMR spectrum of Compound 2 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.50 (1H, t), δ 7.40 (2H, d), δ 3.49 (2H, t), δ 1.91 (2H, t), δ 1.32 (6H, s)

<Step (1-iii): Synthesis of compound 3>
Compound 2 (3.22 g, 10 mmol) is dissolved in dehydrated dichloromethane (20 mL), and triethylamine (2.8 mL, 20 mmol) and methanesulfonyl chloride (1.2 mL, 15 mmol) are slowly added at 0 ° C. After reacting at room temperature for 3 hours, dichloromethane (80 mL) was added to the obtained solution, and the mixture was washed with water (50 mL × 3). The organic layer was dried over magnesium sulfate, and magnesium sulfate was removed by filtration. After removing dichloromethane with an evaporator, tetrahydrofuran (50 mL) and lithium bromide (4.34 g, 50 mmol) were added to the residue. After reacting at 60 ° C. for 4 hours, the solvent is removed by an evaporator. The residue was extracted with chloroform (100 mL) and then washed with water (50 mL x 2). After removing chloroform with an evaporator, the residue was purified by short column chromatography (developing solvent: hexane) to obtain the target compound 3 (3.58 g, 9.3 mmol). The ¹ H-NMR spectrum of Compound 3 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.53 (1H, s), δ 7.37 (2H, d), δ 3.10 (2H, t), δ 2.20 (2H, t), δ 1.32 (6H, s)

<Step (2-i): Synthesis of compound 4>
Dehydrated tetrahydrofuran (20 mL) was added to methyl 3,5-dibromobenzoate (23.5 g, 80 mmol), and a 1 M magnesium bromide solution (170 mL, 170 mmol) was slowly added at 0 ° C. After reacting the reaction solution at room temperature for 2 hours, water (30 mL) was added to stop the reaction. After removing the solvent with an evaporator, chloroform (300 mL) and 1M hydrochloric acid were added to the residue and mixed well. The chloroform layer was recovered with a separating funnel and washed with water (50 mL × 2). After removing chloroform with an evaporator, the residue was purified by column chromatography (developing solvent: chloroform: hexane = 1: 1) to obtain Compound 4 (17.9 g, 61 mmol). The ¹ H-NMR spectrum of Compound 4 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.56 (1H, d), δ 7.53 (2H, t), δ 1.54 (6H, s)

<Step (2-ii): Synthesis of compound 5>
Pre-prepared Ti (collidine) complex (31.2 g, 100 mmol), manganese (5.5 g, 100 mmol) and Collidine (8.1 mL, 60 mmol) are dissolved in dehydrated tetrahydrofuran (250 mL) and stirred under room temperature nitrogen flow. Let me. When the color of the solution turned dark green, a dehydrated tetrahydrofuran solution (30 mL) of acrylonitrile (15.9 g, 300 mmol) and compound 4 (14.7 g, 50 mmol) was added. After stirring at 80 ° C. under nitrogen for 24 hours, the solvent was removed by an evaporator and the mixture was concentrated. Chloroform and hydrochloric acid were added to the residue at 0 ° C., and the mixture was stirred well. The chloroform layer was extracted with a separating funnel (150 mL × 3) and washed with water (100 mL × 2).
After removing chloroform with an evaporator, a crude organism (6.1 g) was obtained by short column chromatography and used as it was in the next reaction. High-purity compound 5 was obtained by repeating column chromatography (developing solvent: chloroform: hexane = 1: 4). The ¹ H-NMR spectrum of Compound 5 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.54 (1H, t), δ 7.35 (2H, d), δ 2.08-1.98 (4H, m), δ 1.32 (6H, s)

<Step (2-iii): Synthesis of compound 6>
Methanol (60 mL) and sodium hydroxide (3.6 g, 90 mmol) were added to compound 5 (5.96 g, 18 mmol), and the mixture was reacted at 70 ° C. for 6 hours. After removing methanol with an evaporator, water (150 mL) was added. After washing the aqueous layer with toluene (30 mL × 3), hydrochloric acid was slowly added to bring the pH to 2 or less. The obtained solution was extracted with chloroform (100 mL × 3), dried over magnesium sulfate, and then magnesium sulfate was removed by filtration. Chloroform was removed by an evaporator and dried to obtain the target compound 6 (4.5 g, 13.1 mmol). The ¹ H-NMR spectrum of Compound 6 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.50 (1H, t), δ 7.37 (2H, d), δ 2.11 (2H, m), δ 1.95 (2H, m), δ 1.30 (2H, m)

<Step (2-iv): Synthesis of Compound 7>
In the step (1-ii), the target compound 7 (3.09 g) was used in the same manner as in the step (1-ii) except that compound 6 (3.5 g, 10 mmol) was used instead of compound 1. , 9.2 mmol) was obtained. The ¹ H-NMR spectrum of Compound 7 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.48 (1H, t), δ 7.38 (2H, d), δ 3.55 (2H, t), δ 1.63 (2H, m), δ 1.33 (2H, m) , δ 1.28 (6H, s)

<Step (2-v): Synthesis of Compound 8>
In the step (1-iii), the target compound 8 (3.31 g) was used in the same manner as in the step (1-iii) except that compound 7 (3.02 g, 9 mmol) was used instead of compound 2. , 8.3 mmol) was obtained. The ¹ H-NMR spectrum of Compound 8 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.50 (1H, t), δ 7.38 (2H, d), δ 3.31 (2H, t), δ 1.72 (2H, m), δ 1.62 (2H, m) , δ 1.29 (6H, s)

<Step (3-i): Synthesis of compound 9>
Compound 6 (3.5 g, 10 mmol) was dissolved in dehydrated tetrahydrofuran (10 mL), thionyl chloride (1 mL) was added, and the mixture was stirred for 6 hours. After removing thionyl chloride and tetrahydrofuran under reduced pressure, dehydrated THF (10 mL) and dehydrated acetonitrile (10 mL) were added. A 2M diethyl ether solution of trimethylsilyldiazomethane (7.5 mL, 15 mmol) was added at 0 ° C., and the mixture was stirred for 4 hours. After removing the solvent and unreacted trimethylsilyldiazomethane under reduced pressure, the diazozate of Compound 6 was purified by column chromatography. Dioxane (10 mL), water (10 mL), and silver benzoate (229 mg, 1 mmol) were added to the obtained compound, and the reaction was carried out by applying ultrasonic waves for 1 hour. After removing the solvent with an evaporator, purification was performed by short column chromatography (developing solvent: hexane: chloroform = 1: 1) to obtain the target compound 9 (2.29 g, 6.3 mmol). The ¹ H-NMR spectrum of Compound 9 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.49 (1H, s), δ 7.38 (2H, d), δ 2.29 (2H, t), δ 1.62 (2H, m), δ 1.40 (2H, t), δ 1.28 (6H, s)

<Step (3-ii): Synthesis of compound 10>
In the step (1-ii), the target compound 10 (1.93 g) was used in the same manner as in the step (1-ii) except that compound 9 (2.18 g, 6 mmol) was used instead of compound 1. , 5.5 mmol) was obtained. The ¹ H-NMR spectrum of Compound 10 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.48 (1H, s), δ 7.37 (2H, d), δ 3.58 (2H, t), δ 1.59 (2H, t), δ 1.49 (2H, m), δ 1.27 (6H, s), δ 1.12 (2H, m)

<Step (3-iii): Synthesis of compound 11>
In the step (1-iii), the target compound 11 (1.89 g) was used in the same manner as in the step (1-iii) except that compound 10 (1.75 g, 5 mmol) was used instead of compound 2. , 4.6 mmol) was obtained. The ¹ H-NMR spectrum of Compound 11 is shown in FIG.
^{1 1} H-NMR (CDCl ₃ ): δ 7.49 (1H, t), δ 7.37 (2H, d), δ 3.35 (2H, t), δ 1.78 (2H, m), δ 1.58 (2H, t) , δ 1.27 (6H, s), δ 1.20 (2H, m)

<Step (1-iv): Synthesis of Polymer (C3) -Br>
Tetrahydrofuran (40 ml) and water (13 ml) were added to compound 3 (1155 mg, 3 mmol), 1,4-benzenediboronic acid bispinacol ester (990 mg, 3 mmol), and potassium carbonate (2.49 g, 18 mmol). A pre-prepared Pd (L) ₃ (L = 4-diphenylphosphinobenzoic acid) catalyst (130 mg) was added, and the inside of the system was replaced with nitrogen. After reacting at 80 ° C. under nitrogen for 48 hours, the solvent was removed by an evaporator. Water (50 mL) was added to the residue, and the mixture was stirred and then filtered. The obtained solid was dissolved in chloroform (100 mL) (dispersed if partially insoluble) and reprecipitated in methanol (300 mL). The precipitate was collected by filtration and then reprecipitated in acetone (300 mL) in a similar manner. The obtained solid was vacuum dried to obtain the desired Polymer (C3) -Br (387 mg).
Polymer (C3) -Br: Mn = 9800, Mw / Mn = 1.75 (GPC in o-dichlorobenzene)
The ¹ H-NMR spectrum of Polymer (C3) -Br is shown in FIG.

<Example 1 Step (1-v): Synthesis of Polymer (C3) -TMA>
It was added to Polymer (C3) -Br (180 mg) in o-dichlorobenzene (50 mL) and dissolved at 150 ° C. If there are some insoluble components, remove the insoluble parts by filtration. After cooling the solution, a 3.2 M trimethylamine methanol solution (2 mL) was added, and the mixture was stirred at 100 ° C. for 12 hours. During this period, the quaternization reaction proceeds to increase the polarity of the polymer and make it insoluble in o-dichlorobenzene. After removing o-dichlorobenzene with an evaporator, the polymer is dissolved by adding dimethyl sulfoxide (20 mL). The reaction was completed by adding a 3.2 M trimethylamine methanol solution (2 mL) to this solution and stirring again at 100 ° C. for 12 hours. After removing dimethyl sulfoxide under reduced pressure, water (50 mL) is added to the residue, and the mixture is stirred at 80 ° C. for 3 hours. The solution was filtered and the resulting solid was vacuum dried to give the desired Polymer (C3) -TMA (136 mg).
The ¹ H-NMR spectrum of Polymer (C3) -TMA is shown in FIG.

<Step (2-vi): Synthesis of Polymer (C4) -Br>
Polymer (C4) -Br (380 mg) was prepared in the same manner as in step (1-iv) except that compound 8 (1197 mg, 3 mmol) was used in place of compound 3. Obtained.
Polymer (C4) -Br: Mn = 16800, Mw / Mn = 1.61 (GPC in o-dichlorobenzene)
The ¹ H-NMR spectrum of Polymer (C4) -Br is shown in FIG.

<Example 2 Step (2-vii): Synthesis of Polymer (C4) -TMA>
Add o-dichlorobenzene (50 mL) to Polymer (C4) -Br (189 mg) and dissolve at 150 ° C. If there are some insoluble components, remove the insoluble parts by filtration. After cooling the solution, a 3.2 M trimethylamine methanol solution (2 mL) was added, and the mixture was stirred at 80 ° C. for 3 hours. During this period, the quaternization reaction proceeds to increase the polarity of the polymer and make it insoluble in o-dichlorobenzene. After removing o-dichlorobenzene with an evaporator, the polymer is dissolved by adding methanol (30 mL). A 3M trimethylamine methanol solution (2 mL) was added to this solution, and the reaction was completed by stirring again at 80 ° C. for 3 hours. After removing methanol with an evaporator, water (50 mL) is added to the residue, and the mixture is stirred at 80 ° C. for 3 hours. The solution was filtered and the resulting solid was vacuum dried to give the desired polymer Polymer (C4) -TMA (158 mg). The ¹ H-NMR spectrum of Polymer (C4) -TMA is shown in FIG.

<Step (3-iv): Synthesis of Polymer (C5) -Br>
Polymer (C5) -Br (403 mg) was prepared in the same manner as in step (1-iv) except that compound 11 (1239 mg, 3 mmol) was used in place of compound 3. Obtained.
Polymer (C5) -Br: Mn = 25100, Mw / Mn = 1.77 (GPC in o-dichlorobenzene)
The ¹ H-NMR spectrum of Polymer (C5) -Br is shown in FIG.

<Example 3 Step (3-v): Synthesis of Polymer (C5) -TMA>
Polymer (C5)-in the same manner as in step (2-vii), except that Polymer (C5) -Br (197 mg) was used instead of Polymer (C4) -Br in step (2-vii). TMA (118 mg) was obtained. The ¹ H-NMR spectrum of Polymer (C5) -TMA is shown in FIG.

[Alkaline durability evaluation]
The polymers obtained in Examples 1 to 3 were immersed in two aqueous solutions of 4M NaOH aqueous solution and 8M NaOH aqueous solution, respectively, at 80 ° C. for 1 week. The ¹ H-NMR spectrum of each polymer before and after immersion was measured to evaluate the structural change. The ¹ H-NMR spectra of Examples 1 to 3 are shown in FIGS. 21 to 23 in order. In FIGS. 21 to 23, (A) is a superposition of three ¹ H-NMR spectra with their axes aligned, and (B) is a superposition of the three ¹ H-NMR spectra with their axes shifted. It is. As shown in FIGS. 21 to 23, all of the polymers of Examples 1 to 3 have no change in the main chain and the peak derived from the ion exchange group in the ¹ H-NMR spectrum before and after immersion, and are stable to alkali. Was shown.

[Manufacturing of electrolyte membrane]
For each of the polymers of Examples 1 to 3, a solution (20 mg / ml) dissolved in methyl sulfoxide was prepared. Each of the solutions was cast on a PTFE substrate and dried by heating at 120 ° C. to form a film. Then, the substrate was immersed in pure water to peel off the polymer membrane from the substrate to obtain an electrolyte membrane. The film thickness of the electrolyte membrane was 48 μm (Polymer (C3) -TMA), 28 μm (Polymer (C4) -TMA), and 30 μm (Polymer (C5) -TMA), respectively.

(Measurement of ionic conductivity)
For each of the obtained electrolyte membrane, Br membrane ^- the ionic conductivity was measured of the ions. The ionic conductivity was calculated from the electrical resistance value measured by AC impedance measurement. The AC impedance measurement in the In-plane was performed by the two-terminal method using a platinum electrode as the electrode. The distance between the electrodes for measuring the voltage was 5 mm to 15 mm, and the low current side electrode and the low voltage side electrode were brought into contact with each other on the opposite side of the electrolyte membrane with respect to the high current side electrode and the high voltage side electrode. The electrolyte membrane was sandwiched between two slide glasses together with the platinum electrodes, and both ends of the slide glasses were fixed with clips. The electrolyte membrane is placed in a constant temperature bath (Espec SH-241 Bench-Top Type Temperature & Humidity chamber) and stabilized at a humidity of 100 RH at each temperature (40 ° C. to 70 ° C.) for at least 2 hours. The measurement was performed from. A Solartron 1260 (manufactured by Solartron, UK) was used as an AC impedance measuring device, AC Amplitude was performed at 10 to 100 mV as a measuring condition, and the frequency was scanned from 100,000 Hz to 1 Hz. The results are shown in FIG. As shown in FIG. 24, it was shown that all the electrolyte films obtained by forming the polymers obtained in Examples 1 to 3 were excellent in ionic conductivity.

Claims (10)

A compound having a repeating unit represented by the following formula (1).

However, in equation (1),
R ¹ is a group having an ion exchange group and
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
The plurality of R ¹ and Ar ¹ may be the same or different from each other. The compound according to claim 1, wherein at least one of the repeating units represented by the formula (1) is a repeating unit represented by the following formula (1a).

However, in equation (1a),
R ² is an ion exchange group and
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
The plurality of R ² , Ar ¹ and p may be the same or different from each other. The compound according to claim 1 or 2, wherein the ion exchange group is quaternary ammonium. A compound represented by the following formula (3).

However, in equation (3),
R ² is an ion exchange group and
p is an integer of 1 or more and 20 or less,
q is an integer of 0 or more and 5 or less,
R ³ is a monovalent organic group or a ring structure in which two R ^3s are linked.
If there are a plurality of R ^3, the plurality of R ³ may be be the same or different. The compound according to claim 4, wherein the ion exchange group is quaternary ammonium. The precursor for producing a compound according to any one of claims 1 to 3, which has a repeating unit represented by the following formula (4).

However, in equation (4),
X is a hydrogen atom or a halogen atom, and at least one of a plurality of Xs is a halogen atom.
Ar ¹ is a divalent aromatic group which may have a substituent and is a divalent aromatic group.
p is an integer of 1 or more and 20 or less,
A plurality of X, Ar ¹ and p may be the same or different from each other. An electrolyte membrane comprising the compound according to any one of claims 1 to 5. A fuel cell comprising the electrolyte membrane according to claim 7. Water electrolysis using the electrolyte membrane according to claim 7. The electrolysis technique using the electrolyte membrane according to claim 7.

Images