KR102307778B1 - Conductive crosslinked membranes and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a conductive cross-linked film and a method for manufacturing the same, and more particularly, to a conductive cross-linked film formed by cross-linking a high molecular polymer including an aromatic ring substituted with sulfonated polyarylene ether sulfone and sulfonate (-SO3M), and the same It relates to a manufacturing method.
The conductive crosslinked film according to the present invention improves dimensional stability and thus has excellent mechanical properties and excellent water uptake and electrical conductivity.
In addition, the method for manufacturing the conductive cross-linked membrane according to the present invention can easily control the cross-linking density and proton conductivity, and the manufacturing method is simple, so that the conductive cross-linked membrane can be manufactured very easily.

Description

Conductive crosslinked film and its manufacturing method TECHNICAL FIELD

The present invention relates to a conductive cross-linked film and a method for manufacturing the same, and more particularly, to a conductive cross-linked film formed by cross-linking a high molecular polymer comprising an aromatic ring substituted with a sulfonated polyarylene ether sulfone and a sulfonate (-SO3M), and the same It relates to a manufacturing method. The conductive crosslinked membrane according to the present invention can be applied to a fuel cell.

PEMFC (Proton Exchange Membrane Fuel Cell) is a fuel cell that uses a polymer having the property of delivering protons as an electrolyte. The Proton Exchange Membrane (PEM) is not only a conductor of protons, but also acts as a separator for the crossover of reactants. Therefore, the proton exchange membrane should have high proton conductivity, chemical and mechanical stability, and should be inexpensive.

Currently, the most commercially used proton exchange membrane is Nafion, which has high proton conductivity and chemical stability. However, this has problems in that it is expensive and the crossover of the reactants is high. On the other hand, aromatic hydrocarbon polymers such as polyarylene ether sulfone are attracting attention as promising candidates to replace PFSA (Perfluoro sulfonic acid) due to their low manufacturing cost and high physicochemical stability. However, the hydrocarbon-based proton exchange membrane has a problem in that proton conductivity is lowered at low relative humidity.

In order to improve the proton conductivity of the hydrocarbon-based proton exchange membrane, a high degree of sulfonation is required, and a membrane having a high degree of sulfonation (DS) deteriorates dimensional stability due to excessive expansion.

Therefore, in order to solve the trade-off relationship between hydrogen ion conductivity and dimensional stability of hydrocarbon-based polymer membranes, introducing a semi-IPN structure or a cross-linked structure, synthesizing a polymer in the form of a block copolymer, or manufacturing a composite membrane using a filler Studies on hydrocarbon-based polymer membranes are being made in various forms.

Among several strategies, the introduction of cross-linked structures is one of the most widely used, since physicochemical stability after cross-linking is significantly increased.

Korea Patent No. 1827728 provides a polymer electrolyte membrane crosslinked by including cellulose to improve thermal stability and hydrogen ion conductivity, and Korea Patent Publication No. 2009-0088646 discloses a polysulfone-based crosslinked polymer membrane using a crosslinkable acrylic resin. It relates to a coating composition having excellent mechanical properties and low methanol permeability.

However, there is a limitation in that the synthesis of the polymer is not easy because many steps are required for the modification of such a polymer.

Korea Patent No. 1827728 (Registered on Feb. 12, 2018) Korean Patent Publication No. 2009-0088646 (published on August 20, 2009)

The conductive cross-linking membrane of the present invention was devised to solve the above problems, and a conductive cross-linking formed by cross-linking a high molecular polymer including an aromatic ring substituted with _{sulfonated polyarylene ether sulfone and sulfonate (-SO 3 M).} Its purpose is to provide a membrane.

Another object of the present invention is to provide a method for manufacturing a conductive cross-linked membrane that very simply and easily cross-links a high molecular polymer including an aromatic ring substituted with sulfonated polyarylene ether sulfone and sulfonate (-SO _{3 M).} The purpose.

The present invention may also have as its object to achieve these objects and other objects that can be easily derived by a person skilled in the art from the general description of the present specification in addition to the above clear objects.

The conductive crosslinked film of the present invention is characterized in that in order to achieve the above object, a high molecular polymer including an aromatic ring substituted with _{sulfonated poly(ether ether ketone) and sulfonate (-SO 3 M) is crosslinked.} .

In addition, the polymer may have at least one of the structures represented by the following Chemical Formulas 1 to 3 as a repeating unit.

[Formula 1]

[Formula 2]

[Formula 3]

In Formulas 1 to 3,

이고,X _{1 To} X ₈ are each independently SO ₂ , CO ₂ , O, S, CH ₂ , CF ₂ , or

ego,

R _{1 To} R ₉ are each independently SO ₃ M or H,

wherein M is a metal.

And, M is an alkali metal, and may be Na or K.

In addition, the sulfonated poly(ether ether ketone) may include a sulfonic acid group represented by _{-SO 3 H.}

And, the cross-linking can be made through _{-SO 2 -.}

In addition, the sulfonation degree of the sulfonated poly(ether ether ketone) may be 25 to 95, preferably 33 to 93, more preferably 50 to 90.

And, the sulfonation degree of the polymer may be 25 to 95, preferably 33 to 93, more preferably 50 to 90.

In addition, the polymer may be poly(arylene ether sulfone) including a repeating unit represented by the following Chemical Formula 4 and a repeating unit represented by Chemical Formula 5.

[Formula 4]

[Formula 5]

In Formulas 4 and 5, x and y are prime numbers between 0 and 1 having a relationship of x+y=1, and x:y is 0.8:0.2 to 0.1:0.9, preferably 0.5:0.5 to 0.1:0.9 , more preferably 0.3:0.7 to 0.1:0.9.

In addition, the sulfonated poly(ether ether ketone) may include a repeating unit represented by Chemical Formula 6 and a repeating unit represented by Chemical Formula 7 below.

[Formula 6]

[Formula 7]

In Formulas 6 and 7, p and q are prime numbers between 0 and 1 having a relationship of p+q=1, and p:q is 0.8:0.2 to 0.1:0.9, preferably 0.5:0.5 to 0.1:0.9 , more preferably 0.2:0.8 to 0.1:0.9.

And, the conductive cross-linking film,

100 parts by weight of a sulfonated poly(ether ether ketone); and

1 to 500 parts by weight of the polymer polymer, preferably 10 to 300 parts by weight, more preferably 50 to 200 parts by weight; may include.

On the other hand, the manufacturing method of the conductive crosslinked film of the present invention,

(A) dissolving a high molecular polymer comprising an aromatic ring substituted with a sulfonated poly(ether ether ketone) and a sulfonate (-SO _{3 M) in a solvent;} and

(B) heating to induce a crosslinking reaction of the sulfonated poly(ether ether ketone).

In addition, the polymer may have at least one of the structures represented by the following Chemical Formulas 1 to 3 as a repeating unit.

[Formula 1]

[Formula 2]

[Formula 3]

In Formulas 1 to 3,

이고,X _{1 To} X ₈ are each independently SO ₂ , CO ₂ , O, S, CH ₂ , CF ₂ , or

ego,

R _{1 To} R ₉ are each independently SO ₃ M or H,

wherein M is a metal.

In addition, the sulfonated poly(ether ether ketone) may include a sulfonic acid group represented by _{-SO 3 H.}

In addition, in the method for preparing the conductive cross-linked film, the cross-linking density of the cross-linked film can be arbitrarily adjusted by adjusting the ratio of the sulfonated poly(ether ether ketone) and the polymer polymer.

And, the step (A) may be a step _{in which -SO 2 is introduced into the sulfonated poly(ether ether ketone).}

In addition, the polymer may be poly(arylene ether sulfone) including a repeating unit represented by the following Chemical Formula 4 and a repeating unit represented by Chemical Formula 5.

[Formula 4]

[Formula 5]

In Formulas 4 and 5, x and y are prime numbers between 0 and 1 having a relationship of x+y=1, and x:y is 0.8:0.2 to 0.1:0.9, preferably 0.5:0.5 to 0.1:0.9 , more preferably 0.3:0.7 to 0.1:0.9.

In addition, the sulfonated poly(ether ether ketone) may include a repeating unit represented by Chemical Formula 6 and a repeating unit represented by Chemical Formula 7 below.

[Formula 6]

[Formula 7]

In Formulas 6 and 7, p and q are prime numbers between 0 and 1 having a relationship of p+q=1, and p:q is 0.8:0.2 to 0.1:0.9, preferably 0.5:0.5 to 0.1:0.9 , more preferably 0.2:0.8 to 0.1:0.9.

And, the step (A) is,

100 parts by weight of a sulfonated poly(ether ether ketone); and

1 to 500 parts by weight of the polymer polymer, preferably 10 to 300 parts by weight, more preferably 50 to 200 parts by weight; may be dissolved in a solvent.

And, in the step (A), the high molecular polymer and the sulfonated poly(ether ether ketone) may be dissolved together in one solvent.

In addition, the solvent may include dimethyl sulfoxide (DMSO).

In addition, the step (B) may be carried out at 140 to 300 ℃, preferably 150 to 220 ℃, more preferably 155 to 190 ℃.

In addition, the sulfonated poly(ether ether ketone) may introduce a sulfonic acid group by reacting the poly(ether ether ketone) with sulfuric acid.

And, the polymer is, by polymerizing the monomers 3,3'-Disulfonate-4,4'-difluorodiphenyl sulfone (SDFDPS), 4,4'-Difluorodiphenyl sulfone (DFDPS), and 4,4'-Dihydroxybiphenyl (BP) prepared sulfonated poly(arylene ether sulfone).

The sulfonation degree of the sulfonated poly(arylene ether sulfone) may be arbitrarily selected by adjusting the molar ratio of SDFDPS and DFDPS.

In addition, the method for preparing the conductive crosslinked film may further include (C) substituting a sulfonic acid group for a sulfonic acid group.

On the other hand, the fuel cell of the present invention is characterized in that it includes the conductive cross-linked membrane according to the present invention.

And, the sulfonation index of the conductive crosslinked film may be 0.01 to 6.5, preferably 0.07 to 3.9, preferably 0.3 to 2.6.

The conductive crosslinked film according to the present invention can provide a conductive crosslinked film having excellent mechanical properties as well as excellent electrical conductivity by improving dimensional stability.

In addition, the method for producing a conductive cross-linked film according to the present invention can easily control the cross-linking density and proton conductivity by adjusting the ratio of the cross-linking compound, so that it is possible to obtain a cross-linked film with desired properties depending on the application, and thus has excellent utility. In addition, unlike the conventional conductive cross-linked membrane prepared through a very multi-step reaction, the present invention has a simple manufacturing method, so that the membrane can be easily and quickly manufactured, as well as economical and versatile.

1 is a schematic diagram schematically showing the structure of a conductive cross-linked film according to the present invention.
2 is a gel fraction test result of membranes prepared according to Examples and Comparative Examples of the present invention.
3 is a gel fraction test result of membranes prepared according to Examples and Comparative Examples of the present invention.
4 is an FT-IR analysis result of the films prepared according to Examples and Comparative Examples of the present invention.
5 is a digital image of a film prepared according to Examples and Comparative Examples of the present invention.
6 is a measurement result of absorption and swelling ratio of membranes prepared according to Examples and Comparative Examples of the present invention.
7 is an SEM image of the membranes prepared according to Examples and Comparative Examples of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.

However, the present invention is not limited to the specific exemplary embodiments, since the following is only to be described in detail by exemplifying specific embodiments, and since the present invention may be variously changed and may have various forms. It should be understood that the present invention includes all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In addition, in the following description, many specific details such as specific components are described, which are provided to help a more general understanding of the present invention, and it is common in the art that the present invention can be practiced without these specific details. It will be self-evident to those who have the knowledge of And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

And, the terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In this application, the singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as 'comprise', 'contain' or 'have' are intended to refer to the presence of a feature, component (or component), etc. described in the specification, but one or more other features or It does not mean that the component or the like is not present or cannot be added.

In the present invention, the sulfonation index is defined as follows:

Sulfonation index = {(Sulphonation degree of polymer A) x (weight of polymer A)}/{(degree of sulfonation of polymer B) x (weight of polymer B)}

In the sulfonation index, the polymer A is _{a polymer containing an aromatic ring substituted with a sulfonate (-SO 3} M), and the polymer B means a sulfonated poly(ether ether ketone).

The conductive cross-linked film of the present invention is characterized in that a high molecular polymer including an aromatic ring substituted with sulfonated poly(ether ether ketone) (SPEEK) and sulfonate (-SO _{3 M) is cross-linked.} do. By using two types of sulfonated polymers, it is possible to provide a cross-linked membrane satisfying both mechanical properties and conductivity, and in particular, when applied to a proton exchange membrane fuel cell, excellent performance can be exhibited.

The sulfonic acid salt (-SO ₃ M) of the high molecular weight polymer including a substituted aromatic ring may have at least one of the structures represented by the following Chemical Formulas 1 to 3 as a repeating unit.

[Formula 1]

[Formula 2]

[Formula 3]

In Formulas 1 to 3,

이고,X _{1 To} X ₈ are each independently SO ₂ , CO ₂ , O, S, CH ₂ , CF ₂ , or

ego,

R _{1 To} R ₉ are each independently SO ₃ M or H,

M is a metal, and may be Na or K, which is an alkali metal.

The high molecular polymer may have more sulfone groups per unit than SPEEK, thereby improving the proton conductivity of the conductive cross-linked film.

The sulfonated poly(ether ether ketone) has a sulfonic acid group, but the sulfonic acid group is not in the form of a sulfonate, but -SO ₃ H(H Form). That is, it should be noted that both polymers used as the material of the crosslinked film according to the present invention are sulfonated polymers, but one of them has a sulfonic acid group and the other has a sulfonate form.

It is SPEEK having a sulfonic acid group that forms a cross-link to improve the dimensional stability of the cross-linked film. This is because, as will be described later, the crosslinking reaction may proceed through the intermediate due to the presence of the sulfonic acid group, thereby forming crosslinking between polymers. Therefore, in the conductive crosslinked film of the present invention, _{there may be crosslinking between SPEEK - (SO 3} M) polymer as well as crosslinking between SPEEK - SPEEK. Since crosslinking is formed through a sulfonic acid group, the crosslinking may include a —SO ₂ — structure.

In the present invention, the 'degree of sulfonation (DS)' refers to the ratio of sulfonic acid groups in the repeating unit in the polymer. The sulfonation degree of the sulfonated poly(ether ether ketone) may be 25 to 95, preferably 33 to 93, more preferably 50 to 90. If the sulfonation degree is less than the above range, the conductivity may be poor.

In addition, the sulfonation degree of the polymer may be 25 to 95, preferably 33 to 93, more preferably 50 to 90. When the sulfonation degree is less than the above range, the conductivity is low, whereas when it exceeds the above range, mechanical properties are deteriorated.

The high molecular weight polymer including the aromatic ring substituted with the sulfonic acid salt (-SO ₃ M) may be poly(arylene ether sulfone) including a repeating unit represented by Chemical Formula 4 and a repeating unit represented by Chemical Formula 5 below.

[Formula 4]

[Formula 5]

In Formulas 4 and 5, x and y are prime numbers between 0 and 1 having a relationship of x+y=1, and x:y is 0.8:0.2 to 0.1:0.9, preferably 0.5:0.5 to 0.1:0.9 , more preferably 0.3:0.7 to 0.1:0.9. When y is less than the above range, the prepared film has low conductivity, and when it exceeds the above range, dimensional stability may decrease.

The sulfonated poly(arylene ether sulfone) (SPAES) may have a repeating unit as in Chemical Formula 5 by sulfonation, and since two or more sulfone groups may be introduced, it is excellent for a cross-linking film. It can impart proton conductivity.

In addition, the sulfonated poly(ether ether ketone) may include a repeating unit represented by Formula 6 and a repeating unit represented by Formula 7 below.

[Formula 6]

[Formula 7]

In Formulas 6 and 7, p and q are prime numbers between 0 and 1 having a relationship of p+q=1, and p:q is 0.8:0.2 to 0.1:0.9, preferably 0.5:0.5 to 0.1:0.9 , more preferably 0.2:0.8 to 0.1:0.9. When the q is less than the above range, a film having low conductivity may be prepared.

In Formulas 4 to 7, x, y, p, and q are indicators indicating the degree of sulfonation of each chemical, and the degree of sulfonation is {y/(x+y)}*100 or {q/(p+q) }*100 is calculated.

And, the conductive cross-linking film,

100 parts by weight of sulfonated poly(ether ether ketone) (SPEEK); and

1 to 500 parts by weight of the polymer polymer, preferably 10 to 300 parts by weight, more preferably 50 to 200 parts by weight; may include.

When the weight part of the polymer is less than the above range, the conductivity of the membrane is not good. On the other hand, when it exceeds the above range, mechanical properties may be adversely affected, and the surface of the membrane will be dissolved in water during the membrane manufacturing process to lower the uniformity. can be a contributing factor. However, the weight ratio of the SPEEK and the polymer may be adjusted according to the sulfonation degree of each compound.

Accordingly, the present inventor introduced a new index called sulfonation index by considering the relationship between the degree of sulfonation and parts by weight of each polymer. This can be an indicator showing the mechanical properties and proton conductivity of the conductive cross-linked film, and is defined as follows:

Sulfonation index = {(Sulphonation degree of polymer A) x (weight of polymer A)}/{(degree of sulfonation of polymer B) x (weight of polymer B)}

The sulfonation index of the conductive crosslinked film according to the present invention is 0.01 to 6.5, preferably 0.07 to 3.9, preferably 0.3 to 2.6. When the sulfonation index is within the above range, the dimensional stability and proton conductivity of the cross-linked film are excellent, and surface non-uniformity can be minimized.

On the other hand, the manufacturing method of the conductive crosslinked film of the present invention,

(A) dissolving a high molecular polymer comprising an aromatic ring substituted with a sulfonated poly(ether ether ketone) and a sulfonate (-SO _{3 M) in a solvent;} and

(B) heating to induce a crosslinking reaction of the sulfonated poly(ether ether ketone).

The structure or repeating unit of the high molecular weight polymer including the aromatic ring substituted with the _{sulfonated poly(ether ether ketone) and the sulfonate (-SO 3} M), which are the two high molecular compounds used as the material, is as described above. In addition, the sulfonated poly(ether ether ketone) is characterized in that it contains a sulfonic acid group represented by _{-SO 3 H.}

Hereinafter, the manufacturing method of the conductive crosslinked film of the present invention will be described in detail for each step.

First, a high molecular polymer including an aromatic ring substituted with sulfonated poly(ether ether ketone) and sulfonate (-SO ₃ M) is prepared and dissolved in a solvent (step (A)).

At this time, it is an important technical feature of the present invention that the crosslinking density and conductivity of the crosslinked film can be easily controlled by controlling the ratio of the sulfonated poly(ether ether ketone) and the high polymer dissolved in the solvent. More specifically, if the ratio of sulfonated poly(ether ether ketone) is increased, the crosslinking density of the crosslinked film is increased and mechanical properties are improved. can be improved Therefore, the present invention can provide a useful method for preparing a conductive cross-linked film, in which the physical properties of the cross-linked film can be arbitrarily adjusted as necessary.

The solvent may be dimethyl sulfoxide (DMSO), and _{a polymer polymer including an aromatic ring substituted with sulfonated poly(ether ether ketone) and sulfonate (-SO 3} M) may be dissolved together in one solvent. DMSO can form electrophilic species by interaction with SPEEK.

In addition, the _{high molecular weight polymer including the aromatic ring substituted with the sulfonate (-SO 3} M) may be sulfonated poly(arylene ether sulfone) (SPAES), and the structure thereof is the same as described above.

In addition, the step (A) may be a step _{in which -SO 2 is introduced into the polymer.} One possible mechanism is shown in Scheme 1 and Scheme 2 below. According to the following mechanism, ion pairs are first formed by strong hydrogen bonding and dipole-dipole interaction between DMSO and the sulfonic acid group (-SO _{3 H) of SPEEK, and then the electrophilic species -SO 2} ⁺ is formed through a series of reactions. is formed

[Scheme 1]

[Scheme 2]

The electrophilic species generated in this way form a bond with the active site of SPEEK or the active site of the polymer polymer including an aromatic ring substituted with a _{sulfonate (-SO 3 M), and cross-linking proceeds.} The activation site is a site capable of reacting with an electrophilic species, and may be present in the aromatic ring. The cross-linking reaction according to an embodiment of the present invention may be represented by Scheme 3 below.

[Scheme 3]

The method for manufacturing the conductive crosslinked film of the present invention is characterized in that it is possible to easily control the crosslinking density and ionic conductivity by controlling the weight ratio of the two materials SPEEK and SPAES. As the content of SPEEK causing the crosslinking reaction increases, the crosslinking density increases. As the crosslinking density increases, the oxidation and thermal stability of the crosslinked film tend to increase. Conversely, the higher the content of SPAES, the better the conductivity is because SPAES has a large amount of sulfonate groups.

In this context, step (A) is

100 parts by weight of a sulfonated poly(ether ether ketone); and

1 to 500 parts by weight of the polymer polymer, preferably 10 to 300 parts by weight, more preferably 50 to 200 parts by weight; may be dissolved in a solvent. When the weight portion of the polymer is less than the above range, the conductivity of the prepared crosslinked membrane is low, whereas when it exceeds the above range, there may be problems in that the tensile strength and elongation at the breaking value of the membrane decrease. On the other hand, when the weight ratio of the polymer such as SPAES exceeds the above range, all of the polymer is dissolved in deionized water during the washing process, which may cause a problem that a crosslinked film cannot be obtained.

In addition, the weight ratio of the two polymers in step (A) may be adjusted according to the degree of sulfonation of each of the polymers represented by SPEEK and SPAES.

Next, the solution formed in step (A) is heated to induce a crosslinking reaction of the sulfonated poly(ether ether ketone) (step (B)).

The step (B) may be to apply or coat the solution formed in step (A) on the substrate and then heat it, and at this time, a solution-casting method may be performed, but is not limited thereto.

The heating temperature in the crosslinking step may be 140 to 300 ℃, preferably 150 to 220 ℃, more preferably 155 to 190 ℃. Also, a temperature of 160° C. or higher is preferred. If the heating temperature is less than the above range, a crosslinked structure may not be introduced, whereas if it exceeds the above range, thermal decomposition of the sulfonic acid group may occur.

As described above, the method for manufacturing the conductive crosslinked film according to the present invention consists of a very simple process of heating after forming a solution. This is due to the self-cross linking ability of SPEEK under high temperature and DMSO, and it is possible to form a film very simply compared to other conventional cross-linking film formation methods by complex stepwise reactions.

The two polymers constituting the crosslinked film may be prepared by sulfonation of the parent polymer. The sulfonated poly (arylene ether sulfone) is a monomer 3,3'-Disulfonate-4,4'-difluorodiphenyl sulfone (SDFDPS), 4,4'-Difluorodiphenyl sulfone (DFDPS), 4,4'-Dihydroxybiphenyl (BP) may be prepared by polymerization of , and in particular, the sulfonation degree of the sulfonated poly(arylene ether sulfone) may be controlled through the molar ratio of SDFDPS and DFDPS. As an embodiment of the present invention, the sulfonated poly(arylene ether sulfone) (SPAES) may be synthesized as shown in the following Reaction Scheme (a).

In addition, as an embodiment of the present invention, the sulfonated poly(ether ether ketone) (SPEEK) may introduce a sulfonic acid group by reacting sulfuric acid with poly(ether ether ketone) (PEEK) as shown in the following reaction formula (b). .

As described above, since SPAES has H+ form and SPEEK has K+ form, it is possible to form a conductive crosslinked film with improved conductivity while having excellent mechanical properties of the crosslinked film. Therefore, SPEEK is taken as an example, but if the sulfonate (-SO ₃ M) contains an aromatic ring substituted and is a high molecular polymer capable of forming a cross-link with SPEEK, a film with excellent physical properties can be obtained together with the SPEEK.

Furthermore, the method for preparing a conductive cross-linked film of the present invention may further include a step (step (C)) of substituting a sulfonic acid group for a sulfonic acid group after step (B). During the formation of the cross-linking film, the sulfonic acid group -SO ₃ H of SPEEK is consumed through the cross-linking reaction, but the sulfonate -SO ₃ K of SPAES is still present after the formation of the cross-linking film, and it can be substituted with a sulfonic acid group through a sulfuric acid solution, etc. . The ability to easily control the conductivity of the cross-linked film through this treatment constitutes an important technical feature of the method for manufacturing the conductive cross-linked film of the present invention.

Meanwhile, the fuel cell of the present invention may include the conductive cross-linked membrane according to the present invention.

Hereinafter, an embodiment of the present invention will be described.

Example

Preparation Example 1: Preparation of sulfonated poly(arylene ether sulfone) SPAES90

Monomer 3,3'-disulfonate-4,4'-difluorodiphenyl sulfone (3,3'-Disulfonate-4,4'-difluorodiphenyl sulfone; SDFDPS), 4,4'-difluorodiphenyl sulfone ( 4,4'-Difluorodiphenyl sulfone;DFDPS) and 4,4'-dihydroxybiphenyl (4,4'-Dihydroxybiphenyl;BP) _{were polymerized under K 2} CO ₃ , CaCO _{3 at} 150° C. for 10 hours.

Then, it was heated at 190° C. under toluene under DMSO and toluene for step-by-step polymerization to prepare a polymer sulfonated poly(arylene ether sulfone) (SPAES). At this time, SPAES90 having a sulfonation degree of 90 was prepared by setting the molar ratio of SDFDPS to DFDPS to 9:1. The sulfonic acid group of the prepared SPAES90 is -SO ₃ K and has a ^{K + form.}

Preparation Example 2: Preparation of sulfonated poly(ether ether ketone) SPEEK88

Poly(ether ether ketone) (PEEK) was sulfonated using sulfuric acid at 60 °C for 3 hours. Thereafter, the reaction solution was precipitated in deionized water to obtain a sulfonated poly(ether ether ketone) (SPEEK) polymer and washed with deionized water to completely remove sulfuric acid. The prepared SPEEK had a sulfonation degree of 88 and was named SPEEK88, and the sulfonic acid group of SPEEK 88 was -SO ₃ H and had an H ⁺ form.

Example 1: Preparation of conductive crosslinked film CP67

The sulfonated polyarylene ether sulfone SPAES90 prepared in Preparation Example 1 and the sulfonated polyether ether ketone SPEEK88 prepared in Preparation Example 2 were dissolved in DMSO at a weight ratio of 1:2.

The resulting solution was cast on a flat glass plate using a doctor blade and heated at 160° C. for 12 hours to induce self-crosslinking of sulfonated poly(ether ether ketone). After this, a cross-linked membrane CP67 was obtained.

Example 2: Preparation of conductive crosslinked film CP50

A crosslinked film was prepared in the same manner as in Example 1, except that the weight ratio of SPAES90 and SPEEK88 was 1:1 to obtain CP50.

Example 3: Preparation of conductive crosslinked film CP33

A crosslinked film was prepared in the same manner as in Example 1, except that the weight ratio of SPAES90 and SPEEK88 was 2:1 to obtain CP33.

Example 4: Preparation of conductive crosslinked film CP25

A crosslinked film was prepared in the same manner as in Example 1, except that the weight ratio of SPAES90 and SPEEK88 was 3:1 to obtain CP25.

Comparative Example 1: Preparation of conductive crosslinked film CP100

SPEEK88 prepared in Preparation Example 2 was dissolved in DMSO. The resulting solution was cast on a flat glass plate using a doctor blade, and heated at 160° C. for 12 hours to induce self-crosslinking of sulfonated polyetheretherketene. After this, a cross-linked membrane CP100 was obtained.

Comparative Example 2: SPEEK (Na ⁺ ) of crosslinking

A cross-linked film was prepared in the same manner as in Example 1, except that SPEEK (Na ⁺ ) in the _{form of sodium sulfonic acid salt -SO 3} Na was used instead of SPEEK 88 in which the _{sulfonic acid group was -SO 3 H.}

Comparative Example 3: Preparation of solution using DMAc solvent

A cross-linked film was prepared in the same manner as in Example 1, except that the solvent was DMAc.

Comparative Example 4: Preparation at 140 °C

A crosslinked film was prepared in the same manner as in Example 1, but the heating temperature was set to 140 °C.

Test Example 1: Gel fraction test

2 is a view of the membranes prepared in Comparative Examples 2, 3, 4, and Example 1 from the left through a gel fractionation test. Unlike the membranes of Example 1, the membranes of Comparative Examples 2 to 4 were dissolved in the solution and the membranes were not maintained. Through this, it can be seen that the sulfonic acid group of SPEEK is in the form of H+ rather than a salt, and the film is well formed when the solvent is DMSO. In addition, it can be inferred that crosslinking can be more easily formed at 160° C. or higher through the gel fraction test result of Comparative Example 4.

Comparative Example 5: Preparation at 120 °C

It was prepared in the same manner as in Example 1, but the heating temperature was 120 °C.

Test Example 2: Gel fraction test

3 is a view showing the cross-linked membranes prepared in Example 1 and Comparative Example 5 through a gel fractionation test. Unlike the crosslinked film of Example 1, the crosslinked film of Comparative Example 5 was completely dissolved in the solution, and it can be seen that no crosslinked structure was introduced at 120 °C.

Test Example 3: FT-IR spectrum of CP33

4 is an FT-IR spectrum of the SPAES90, CP100, CP33, and CP33 gel fraction residues. In the FT-IR spectrum of the CP33 gel-fraction residue, a characteristic peak of phenylene near the sulfone of SPAES, which is not present in CP100, was observed. Through this, it can be seen that both SPAES and SPEEK in CP33 form a cross-linked structure of the film.

Test Example 4: Crosslinking Density Evaluation

5 is a digital image before and after the gel-fractionation test of the membranes prepared in Examples 1 to 4 and Comparative Example 1, and the results of the gel fractionation test are shown in Table 1 below. From the gel fraction test, it was observed that the crosslinking density increased with the increase of the SPEEK content.

CP100 CP67 CP50 CP33 CP25 Weight percent of SPEEK(%) 100.00 67.00 50.00 33.33 25.00 Residual weight after gel-fraction test (%) 99.81 89.06 82.11 76.75 62.17

Test Example 5: Dimensional stability evaluation

By measuring the water absorption and swelling ratios of the crosslinked films prepared in Examples 1 to 4 and Comparative Example 1, the effect of the crosslinked structure on dimensional stability was confirmed (FIG. 6). As expected, as the SPEEK content increased, the crosslinking density increased, leading to a decrease in the water absorption value of the membrane. The expansion ratio behavior of the membrane was similar to the water absorption behavior, because the volume expansion of the membrane by water is directly affected by the hydration of hydrophilic groups.

Test Example 6: Membrane surface evaluation

The shapes of the crosslinked films prepared in Examples 1 to 4 and Comparative Example 1 were investigated by SEM. 7 is an SEM image of the surface (left) and cross-section (right) of each sample. Phase-separated domains could not be observed in all samples. However, CP33 and CP25 could be observed to have rough surfaces, which may be due to excessive expansion during the washing process.

In the above, preferred embodiments of the present invention have been described, but the present invention is not limited to the specific embodiments described above, and those skilled in the art can implement various modifications without departing from the gist of the present invention. Of course it is possible. Accordingly, the scope of the present invention should not be construed as being limited to the above embodiments, and should be defined by the claims described below as well as the claims and equivalents.

Claims (10)

A sulfonated poly(ether ether ketone) and a high molecular polymer including an aromatic ring substituted with a sulfonate is -SO ₂ - A cross-linked conductive film comprising:
The high molecular weight polymer including the aromatic ring substituted with the sulfonate includes a repeating unit represented by the following Chemical Formula 4 and a repeating unit represented by the Chemical Formula 5,
Wherein the sulfonated poly(ether ether ketone) comprises a repeating unit represented by the following formula (6) and a repeating unit represented by formula (7):
[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

In Formulas 4 and 5, x:y is 0.8:0.2 to 0.1:0.9,
In Formulas 6 and 7, p:q is 0.8:0.2 to 0.1:0.9,
wherein K is a metal. delete delete (A) dissolving a high molecular polymer comprising a sulfonated poly(ether ether ketone) and an aromatic ring substituted with a sulfonate in a solvent; and
_{(B) inducing -SO 2} - crosslinking reaction of the sulfonated poly (ether ether ketone) by heating to 150 to 220 ° C.;
The solvent is characterized in that it contains DMSO (dimethyl sulfoxide),
The high molecular weight polymer including the aromatic ring substituted with the sulfonate includes a repeating unit represented by the following formula (4) and a repeating unit represented by the formula (5),
The sulfonated poly(ether ether ketone) comprises a repeating unit represented by the following formula (6) and a repeating unit represented by formula (7), a method for producing a conductive cross-linked film:
[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

In Formulas 4 and 5, x:y is 0.8:0.2 to 0.1:0.9,
In Formulas 6 and 7, p:q is 0.8:0.2 to 0.1:0.9,
wherein K is a metal. delete 5. The method according to claim 4,
The method for producing the conductive cross-linked film is characterized in that the cross-linking density of the cross-linked film can be arbitrarily adjusted by adjusting the ratio of the sulfonated poly(ether ether ketone) and the polymer polymer. delete delete 5. The method according to claim 4,
The method for producing the conductive cross-linked film,
(C) substituting a sulfonic acid group for a sulfonate; A fuel cell comprising the conductive cross-linked membrane of claim 1.

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