KR101435607B1 - Ion-conducting polymer comprising sulfonated poly(phenylene sulfone) without ether linkage and use thereof - Google Patents

Abstract

The present invention relates to a cross-linked copolymer including a hydrophilic repeating unit represented by the following Formula 1 and a hydrophobic repeating unit represented by the following Formula 2; a method of preparing the cross-linked copolymer; an ion-conducting polymer including the cross-linked copolymer; an ion conducting material including the ion-conducting polymer; a battery provided with an electrolyte membrane or a separator molded from a resin composition including the ion conducting polymer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion-conducting polymer comprising a polyphenylene sulfone structure having no sulfonic acid group-substituted ether bond and a use thereof,

The present invention relates to a crosslinked copolymer comprising a hydrophilic repeating unit represented by the following formula (1) and a hydrophobic repeating unit represented by the following formula (2); A method for producing the cross-linked copolymer; An ion conductive polymer including the cross-linked copolymer; An ion conductor including the ion conductive polymer; An electrolyte membrane formed from a resin composition containing the ion conductive polymer, or a battery having a separation membrane.

[Chemical Formula 1]

(2)

Fuel cells are energy conversion devices that convert the chemical energy of fuels directly into electric energy, and have been developed as a next generation energy source with high energy efficiency and eco-friendly characteristics with less pollutant emissions. Proton exchange membrane fuel cells (PEMFCs) containing a polymer electrolyte membrane have advantages such as low operating temperature, leakage problem caused by the use of solid electrolytes, and quick drive, Devices.

In general, an electrolyte membrane used in a polymer electrolyte fuel cell can be divided into a perfluorinated polymer electrolyte and a hydrocarbon polymer electrolyte. The fluorinated polymer electrolyte is chemically stable due to a strong binding force between carbon-fluorine (CF) and a shielding effect which is a characteristic of a fluorine atom, and has excellent mechanical properties. Particularly, And has been commercialized as a polymer membrane of an electrolyte type fuel cell. Nafion (perfluorosulfonic acid polymer), which is a commercially available product from DuPont, USA, is a typical example of a proton exchange membrane and has been widely used since it has excellent ionic conductivity, chemical stability and ion selectivity. For example, Nafion generally exhibits excellent chemical stability and proton conductivity at high relative humidity (RH) and low temperature. However, the fluorinated polymer electrolyte membrane typified by Nafion has a limited efficiency of the polymer membrane at a temperature of 80 ° C or higher compared with the above-mentioned excellent performance, so that the driving temperature (0 to 80 ° C) is limited and the industrial utilization is low And the fuel permeability (that is, the methanol permeability (methanol crossover)) through which the fuel such as methanol passes through the polymer membrane is high. This prompted the development of low cost, high performance, non-fluorinated polymers (e.g., hydrocarbon polymers) proton conducting materials.

As part of this effort, polymer families such as polyphosphazenes, polybenzimidazole, poly (ether sulfone), and poly (ether ketone) Was prepared. The polymers have high thermal, oxidation and chemical stability in the driving environment of the fuel cell, and thus have the potential to be utilized in fuel cells. However, although most of the hydrocarbon polymers have excellent thermal stability close to that of Nafion, they have a structure having an acidic functional group attached to the main chain and a chemical structure close to Nafion which is commercialized due to the ether bond which is susceptible to attack by a nucleophile It is difficult to secure stability. Therefore, since the polymer electrolyte membrane used in the fuel cell must be stable under the conditions required for driving the fuel cell, the usable polymer among them is very limited by aromatic polyether (APE) and the like.

In addition, hydrolysis, oxidation, and reduction reactions during the operation of the fuel cell cause degradation of the polymer membrane, thereby deteriorating the performance of the fuel cell. Accordingly, polyetherketone and polyethersulfone-based polyaryleneether polymers have been studied for their application to fuel cells due to their excellent chemical stability and mechanical properties.

As a method for improving the ionic conductivity, a method of producing a polymer having a hydrophilic functional group introduced therein has been used. U.S. Patent No. 4,625,000 discloses a post-sulfonation process of a polyethersufone with a polymer electrolyte membrane. The post-treatment sulfonation method disclosed in the above document uses a strong acid such as sulfuric acid as a sulfonating agent and randomly introduces a sulfonic acid group (-SO ₃ H) into the polymer skeleton, so that the distribution of sulfonic acid groups, It is difficult to control the position, number, and the like.

In addition, European Patent No. 1,113,517 A2 discloses a block copolymer polyelectrolyte membrane composed of a block having a sulfonic acid group and a block having no sulfonic acid group. There is a problem such that the chemical bond of the aliphatic polymer is decomposed during the sulfonation process because the block copolymer composed of the aliphatic block and the aromatic block is sulfonated using sulfuric acid which is a strong acid, It was difficult to control the position and number of sulfonic acid groups in the polymer skeleton.

On the other hand, Japanese Patent Application Laid-Open No. 2003-147074 discloses a method of introducing a sulfonic acid group into a fluorene of a polymer by using a chlorosulfonic acid (HSO ₃ Cl) or a sulfuric acid as a copolymer containing a fluorene compound Method. In this method, a sulfone group is randomly introduced into a ring constituting a fluorene compound.

The polymer sulfonation methods proposed in the above-mentioned prior arts have the disadvantages that when the sulfonate group content (sulfonation degree: DS, degree of sulfonation) is increased in order to realize hydrogen ion conductivity similar to that of commercialized Nafion, Dupont, The water content and the methanol content are excessively increased to dissolve the electrolyte membrane in methanol, and the mechanical densities of the electrolyte membranes are remarkably decreased, failing to satisfy the physical properties of the electrolyte membrane required for fuel cell operation.

On the other hand, Fujimoto et al. (Macromolecules, 2005, 38: 5010-5016) disclosed in Macromolecules can reduce the cost and thermal stability of conventional thermoplastic sulphonation, In order to improve the stability lower than Nafion, a complete aromatic polymer was prepared and then sulfonated to produce an ion conductive polymer. However, the thermo-chemical stability of the polymer is improved, but the polymer is difficult to be formed into a membrane due to its rigid chemical structure.

It is an object of the present invention to provide a method for producing a polymer electrolyte membrane in which an ion conductive polymer prepared by copolymerizing an intact aromatic polymer is prepared by only carbon-carbon bonds and has a skeletal rigidity, Which is difficult to control.

The present invention provides a cross-linked copolymer comprising a hydrophilic repeating unit represented by the following formula (1) and a hydrophobic repeating unit represented by the following formula (2)

[Chemical Formula 1]

(2)

In Formula 1, x is an integer of 0 to 5.

The present invention also provides a method for producing a cross-linked copolymer, comprising the steps of: preparing a benzene compound in which two molecules of cyclopentadienone substituted with two or more phenyl groups are bonded to each other in a para position; A second step of preparing a compound containing two or more benzene rings including alkene groups at both terminals and connected to a sulfonyl group; A third step of mixing the compounds prepared in the first and second steps to form a cross-linked copolymer by Diels-Alder reaction; And a fourth step of post-curing the cross-copolymer of the third step.

Further, the present invention provides an ion conductive polymer represented by the following general formula (5) including the cross-linked copolymer:

[Chemical Formula 5]

In Formula 5, x is an integer of 0 to 5.

Furthermore, the present invention provides an ion conductor as a molding formed of the resin composition containing the ion conductive polymer of the present invention. The molded body may be an electrolyte membrane, a separation membrane, or a water treatment membrane.

The present invention also provides a battery having an electrolyte membrane or a separator formed from the resin composition comprising the ion conductive polymer of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention is based on the discovery that the ion conductive polymer prepared by the post-sulfonation of a complete aromatic polymer is composed of only carbon-carbon bonds, and thus the skeletal strength is strong, In order to solve this difficulty, an ion conductive polymer having hydrophobicity and hydrophobicity crossing and having improved phase separation performance is provided by introducing a sulfonic acid group into a hydrophobic part and imparting flexibility while selectively introducing a sulfonic acid group into a benzene ring not adjacent to a sulfonic acid group The polymer is improved in thermal and chemical stability by eliminating highly reactive ether groups and the like, and is characterized in that flexibility is imparted by introducing a sulfonyl group into the main chain.

The ion conductive polymer according to the present invention is prepared such that the hydrophobic portion and the hydrophilic portion cross each other. The ion conductive polymer includes a phenyl group substituted with a plurality of benzene rings in the main chain including a benzene ring directly bonded to the carbon- Part includes a benzene ring connected to a sulfonyl group introduced to impart flexibility to the benzene ring adjacent to the sulfonyl group and the benzene ring adjacent to the main chain when the sulfonation proceeds after the polymerization reaction, Is achieved by post-sulfonation in which a group is introduced. Furthermore, the content of sulfonic acid group varies depending on the amount of chlorosulfonic acid used in the subsequent sulfonation.

The method for preparing a cross-copolymer according to the present invention comprises: a first step of preparing a benzene compound in which two molecules of cyclopentadienone substituted with at least two phenyl groups are bonded to each other in a para position; A second step of preparing a compound containing two or more benzene rings including alkene groups at both terminals and connected to a sulfonyl group; A third step of mixing the compounds prepared in the first and second steps to form a cross-linked copolymer by Diels-Alder reaction; And a fourth step of post-curing the cross-linked copolymer of the third step.

Preferably, the benzene compound of the first step may be a compound represented by the following formula (3), and the compound of the second step may be a compound represented by the following formula (4). However, the present invention is not limited to the above-mentioned compounds, and includes benzene rings each of which is connected to the main chain by a carbon-carbon bond by Diels-Alder reaction and contains a plurality of phenyl groups, including a diene or a dienophile, And a benzene ring bonded with a sulfonyl group as a repeating unit can be used as a reactant for the third stage Diels-Alder reaction.

(3)

[Chemical Formula 4]

The compounds represented by Formula 3 or 4 may be prepared by commercially available compounds or synthesized by methods known in the art.

In a specific example of the present invention, the Sonogashira coupling reaction of 1,4-diiodobenzene and phenylacetylene, the oxidation reaction, and the condensation reaction with 1,3-diphenylacetone catalyzed by potassium hydroxide are carried out in sequence, 3, and 1,4'-bis (2,4,5-triphenylcyclopentadienone) benzene (BTPCPB) were synthesized. In addition, Friedel-Craft acylation reaction of phenylsulfide and acetyl chloride, formation of bis-chloroaldehyde by reaction with POCl ₃ , alkynation using NaOH, and oxidation reaction with mCPBA are carried out in order to obtain the compound represented by Formula 4, Bis (4-ethynylphenyl) sulfone (BEPS) was synthesized. Then, Diels-Alder reaction is carried out using the two synthesized compounds as a reactant to form a cross-linked copolymer, and then sulfonated with chlorosulfuric acid to introduce a sulfonic acid group into the pendant phenyl group substituted in the side chain to impart hydrophilicity. Was prepared.

The term "Diels-Alder reaction" of the present invention is a method for synthesizing cyclic compounds, which means the cyclization of one or more unsaturated compounds by a single-step, concerted pathway . The Diels-Alder reaction can be used to cyclize unsaturated compounds with little or no ionic or free radical properties. The two reactants of the Diels-Alder reaction are each a diene (a conjugated system of four pi electrons) and a dienophile (a conjugate system of two pi electrons), which contains an unsaturated bond as described above, The bond may be a double or triple bond of a carbon-carbon or non-carbon atom.

In a specific example of the present invention, a polymer was formed through Diels-Alder reaction between 1,4'-bis (2,4,5-triphenylcyclopentadienone) benzene and bis (4-ethynylphenyl) sulfone, At this time, the cyclopentadienone moiety of 1,4'-bis (2,4,5-triphenylcyclopentadienone) benzene is substituted with diene and the ethynyl moiety of bis (4-ethynylphenyl) The reaction can be performed by acting as a dienophile. Thus, each compound contains dienes and dienophiles at both ends of the molecule, so that a cross-linked copolymer in which the two molecules are cross-linked by a chain reaction can be obtained.

Finally, the sulfonation in the fourth step selectively introduces a sulfonic acid group into a phenyl group substituted on the side chain which is not a main chain to impart hydrophilicity, so that the cross-copolymer produced in the third step has partial hydrophilicity, Ion conductivity can be improved. At this time, the content of the introduced sulfonic acid group can be controlled by controlling the amount of chlorosulfonic acid used.

In a specific embodiment of the present invention, 2.5 g of the cross-copolymer PPS were reacted with 0.69 g, 0.92 g and 1.16 g of chlorosulfonic acid, respectively, to give an ion-conducting cross-linker containing sulfonic acid groups in an amount of 23%, 29% Lt; / RTI >

The present invention also provides an ion conductive polymer represented by the following general formula (5), which comprises the cross-linked copolymer or the cross-linked copolymer produced by the above method.

[Chemical Formula 5]

In Formula 5, x is an integer of 0 to 5.

The ion conductive polymer according to the present invention preferably contains sulfonic acid groups substituted in the hydrophilic part in an amount of 10 to 50 mol% (or mass%, substitution number per unit pendant phenyl group, etc.). Accordingly, x in the formula (5) is preferably 1 to 5. For example, when the content of the sulfonic acid group is less than 10%, the ionic conductivity is almost zero. When the content of the sulfonic acid group is more than 50%, the polymer is dissolved in water and can not act as an actual separation membrane. More preferably, the content of the sulfonic acid group may be 20 to 50%, more preferably 20 to 40%.

Preferably, the molecular weight of the cross-linked copolymer according to the present invention is Mn (number-average molecular weight) of 10,000 to 1,000,000 or molecular weight of Mw (weight-average molecular weight) of 10,000 to 10,000,000 . More preferably from 10,000 to 300,000, or from 10,000 to 2,000,000. When the molecular weight is low, for example, when it is 10,000 or less, film formation is difficult, the moisture content is increased, and it is easily decomposed by the attack of radical, so that conductivity and durability may be decreased. On the other hand, in the case where the molecular weight is high, for example, 1,000,000 or more, the rapidly increasing viscosity may make the preparation of the polymer solution and molding into a film difficult, making the film production process impossible.

The ion conductive polymer according to the present invention provides an ion conductor comprising a sulfonic acid group or an alkali metal salt thereof.

The molded article can be formed from the resin composition containing the ion conductive polymer or block copolymer according to the present invention. Non-limiting examples of the molded body include an electrolyte membrane, a separation membrane, or a water treatment membrane.

The resin composition of the present invention may further contain various additives such as an antioxidant, a heat stabilizer, a lubricant, a tackifier, a plasticizer, a crosslinking agent, a defoaming agent, and a dispersant.

The resin composition containing the ion conductive polymer according to the present invention can be extruded and formed into a molded article in the form of fiber or film by any method such as spinning, rolling or casting.

For example, the resin composition containing the ion conductive polymer or block copolymer of the present invention can be molded to produce an electrolyte membrane. Specifically, the block copolymer is dissolved in a solvent such as N-methylpyrrolidone (NMP), dimethylformamide, dimethylsulfoxide or dimethylacetamide, and the solution is poured into a plate such as a glass plate, To obtain a film having a thickness of several to several hundreds of μm, preferably 10 to 120 μm, more preferably 50 to 100 μm, and then desorbing from the plate. The above-mentioned solvent is only illustrative, and the scope of the present invention is not limited thereto. Conventional organic solvents may be used as long as they dissolve the polymer and can be evaporated under the drying condition. Specifically, the same organic solvent as that used in the preparation of the polymer may be used.

According to a specific embodiment of the present invention, the prepared polymer is dissolved in DMAc and / or DMSO and poured onto a glass plate and dried at 60 to 100 ° C, preferably 70 to 90 ° C for 12 to 36 hours, preferably 18 to 30 hours So that a film can be obtained. The drying can be performed using a halogen lamp in a nitrogen atmosphere. The obtained membrane may be washed with a sulfuric acid solution and distilled water in turn to convert it into a proton-type polymer membrane.

Accordingly, the polymer membrane according to the present invention can use a polymer having sulfonate group or its alkali salt substituted as a reactant, and can be easily converted into a proton form by an additional washing process with sulfuric acid. On the other hand, in the conventional polymer membrane production method, monomers which protect the sulfonic acid group substituted with the hydrophilic monomer by the alkyl or alkoxy group in two steps are used in order to increase the degree of polymerization. Thus, such an additional process was required. However, according to the production method of the present invention, since the process for protecting the substituent is not required, the synthesis step can be simplified and the remarkable cost saving effect can be obtained.

The polymer membrane including the ion conductive polymer or the block copolymer according to the present invention may be used as a battery electrolyte membrane or a separator membrane.

The present invention provides a battery having an electrolyte membrane formed from a resin composition containing the ion conductive polymer.

The electrolyte membrane formed from the resin composition comprising the ion conductive polymer or block copolymer according to the present invention has high hydrogen ion conductivity, mechanical strength, and excellent chemical stability, and thus can be used as a hydrogen ion electrolyte membrane. In particular, The present invention can be used as an ion exchange membrane in a proton exchange membrane fuel cell aka polymer electrolyte membrane fuel cell (PEMFC), a direct methanol fuel cell (DMFC), or a redox flow battery.

The cross-copolymer of the present invention comprises a main chain composed of benzene linked by a carbon-carbon bond, and a hydrophilic part substituted with a phenyl group including a sulfonic acid group on the benzene ring constituting the main chain, thereby imparting thermal and chemical strength, And a benzene ring connected to the hydrophobic moiety by a sulfonyl group in order to prevent the film from being scratched during manufacture. On the other hand, the polymer membranes prepared from the cross-linked copolymers exhibit proton conductivity, ion exchange capacity and water absorption rate similar to those of Nafion, which are commercially available, and have excellent thermochemical stability, and thus can be used as an electrolyte membrane for fuel cells.

1 is a schematic view illustrating a process of synthesizing BTPCPB and BEPS monomers according to the present invention.
2 is a schematic view illustrating a process of synthesizing PPS and SPPS polymers according to the present invention. Specifically, the PPS polymer was synthesized from BTPCPB and BEPS monomers by Diels-Alder reaction and sulfonated with chlorosulfuric acid to prepare SPPS. At this time, a series of SPPS in which the content of sulfonic acid group was controlled by adjusting the amount of chlorosulfuric acid to be reacted was prepared (SPPS 1 to SPPS 3).
3 is a chart showing ¹ H NMR spectra of (a) BTPCPB and (b) BEPS monomers according to the present invention.
4 is a chart showing ¹ H NMR spectra of (a) PPS and (b) SPPS polymer according to the present invention.
FIG. 5 is a graph showing a result of thermogravimetric analysis of polymers according to the present invention. FIG.
FIG. 6 is a graph showing the IEC and the water absorption rate of the polymer according to the present invention at 80 ° C compared with Nafion 211. FIG.
7 is a graph showing the proton conductivity of the polymer according to the present invention at relative humidity (RH) at 80 ° C compared to Nafion 211. FIG.
8 is a graph showing proton conductivity at 80% RH of the polymer according to the present invention compared with Nafion 211. FIG.
9 is a graph showing the film decomposition rate of the polymer according to the present invention. Accelerated chemical degradation tests were performed using 4 ppm Fe2 + Fenton reagent and Nafion 211 was used as a control.
10 is a graph showing the performance of a battery having a polymer membrane according to the present invention. Polarization and power density were shown as a function of current density roll. Nafion 211 was used as a control. It was confirmed that the battery having the SPPS 3 polymer membrane according to the present invention exhibited superior performance to the battery having the Nafion 211 at the entire current density interval.

Hereinafter, the constitution and effects of the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and the scope of the present invention is not limited by these examples.

Example  1: substance

But are not limited to, 1,4-diiodobenzene, phenylacetylene, bis (triphenylphosphine) palladium dichloride, copper iodide, Ortho-periodic acid, 1,3-diphenylacetone, aetylchloride, aluminum chloride, m-chloroperbenzoic acid, m-chloroperbenzoic acid, (S) selected from the group consisting of triethylamine, phenyl sulfide, glacial acetic acid, chlorosulfuric acid, m-chloroperoxybenzoic acid (mCPBA), sodium hydroxide Potassium hydroxide was purchased from Sigma-Aldrich and TCI and used as such. Other commercially available solvents include, for example, 1,4-dioxane, carbon disulfide, tetrahydrofuran (THF), dichloromethane (MC), ethyl ether ether, diphenyl ether, ethyl acetate, n-hexane, chloroform, ethanol, acetone, methanol and water separately. Without purification.

Example  2: 1,4'- Of bis (2-phenylethynyl) benzene  synthesis

(10 g, 0.03 mol), phenylacetylene (8.10 g, 0.08 mol) and bis (triphenylphosphine) palladium dichloride (1.066 g, 0.08 mol) in a three-necked flask equipped with a magnetic stirrer under nitrogen. 1.52 mmol) and copper iodide (0.576 g, 3.04 mmol) were mixed in THF (40 ml) at room temperature. 80 ml of triethylamine was added dropwise to the mixed solution. The reaction was then stirred at room temperature for 20 hours. After confirming the completion of the reaction by TLC, the mixture was poured into 200 ml of MC and stirred for 20 minutes. The organic layer was washed with water (100 ml x 3), dried over anhydrous magnesium sulphate and evaporated to give the product. The crude product was purified by simple recrystallization from a mixture of MC and methanol. The product was filtered and dried in vacuo at 60 < 0 > C for 24 h (75% yield).

Example  3: p- Of di (phenylglyoxalyl) benzene  synthesis

1,4-bis (2-phenylethynyl) benzene (3.5 g, 0.025 mol) and ortho-periodic acid (5.7 g, 0.025 mol) were dissolved in a flask with 188 ml of glacial acetic acid. The mixture was stirred at 55 < 0 > C for 20 hours. After the reaction, the mixture was poured into a mixture of water / chloroform (200 ml / 100 ml). The organic layer was washed with a 5 wt% aqueous sodium bicarbonate solution (100 ml) and water (100 ml x 2). The organic layer was separated, dried over anhydrous magnesium sulfate and evaporated to give a yellow crystalline solid in 70% yield.

Example  4: 1,4'- Bis (2,4,5- Triphenylcyclopentadienone ) ≪ / RTI > benzene (BTPCPB)

P-Di (phenylglyoxalyl) benzene (10 g, 0.03 mol) and 1,3'-diphenylacetone were dissolved in a flask with 100 ml of ethanol containing 10 ml of toluene. A solution of potassium hydroxide (2.1 g, 0.04 mol) in methanol (10 ml) was added dropwise to the reaction solution at room temperature. After the addition, the mixture was refluxed at 130 DEG C for 1 hour. The mixture was cooled to 0 < 0 > C and crystallized. The solid was collected by filtration and washed with cold ethanol. The filtered product was dried in vacuo at 60 < 0 > C for 24 hours (80% yield).

Example  5: Of bis (p-acetylphenyl) sulfide  Produce

Phenylsulfide (25 g, 0.13 mol) and acetyl chloride (31.58 g, 0.40 mol) were dissolved in 250 ml of carbon disulfide at 0 ° C in a flask. To this solution at 0 < 0 > C was slowly added aluminum chloride (62.64 g, 0.47 mol). After the addition, the temperature was raised to room temperature and stirred for 8 hours. The reaction was terminated by pouring into 500 ml of crushed ice and the organic layer was extracted with chloroform. The combined organic layers were washed with saturated brine solution, dried over anhydrous magnesium sulfate and the solvent was evaporated. The product was purified by simple recrystallization from a mixture of MC and n-hexane. The filtered product was dried in vacuo at 60 DEG C for 24 hours (94% yield).

Example  6: 3,3 '- ( Thiol di -4,1'- Phenylene ) - Bis [3-chloro-2-propenal]  Produce

Phosphorus oxytrichloride (91.2 g, 0.59 mol) was dissolved in a flask with 230 ml DMF at 0 ° C for 10 minutes and a solution of bis (p-acetylphenyl) sulfide dissolved in 200 ml DMF was slowly added. After 2 hours, the reaction mixture was poured into an excess amount of aqueous sodium acetate solution to terminate the reaction. The organic layer was extracted with MC and the combined organic layers were washed with 5 wt% aqueous sodium bicarbonate, dried over anhydrous magnesium sulfate and the solvent was evaporated. The product was purified by simple recrystallization from a mixture of MC and ethyl ether. The filtered product was dried in vacuo at 60 < 0 > C for 24 hours (yield 45%).

Example  7: Bis (4-ethynylphenyl) sulfide  Produce

Sodium hydroxide (10 g, 0.25 mol) was dissolved in the flask with 80 ml water at 80 占 폚. To this solution was added a solution of 3,3 '- (thiodi-4,1'-phenylene) -bis [3-chloro-2-propenal] (8 g, 0.02 mol) dissolved in 100 ml of 1,4'- Was added dropwise and stirred at 80 < 0 > C for 2 hours. The reaction mixture was poured into 500 ml water. The organic layer was extracted with ethyl ether, and the combined organic layer was washed with a saturated solution of brine, dried over anhydrous magnesium sulfate and the solvent was evaporated to obtain a viscous red oil. Simple recrystallization gave a crystalline solid in 37% yield.

Example  8: Bis (4- Ethynyl phenyl ) Sulphone (BEPS)

To a solution of bis (4-ethynylphenyl) sulfide (6 g, 0.03 mol) in 300 ml MC was added mCPBA (22.1 g, 0.13 mol) and the mixture was stirred overnight. The reaction mixture was poured into 200 ml of water. The organic layer was extracted with MC, and the combined organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and the product was separated by silica gel chromatography eluting with MC (80% yield).

Example  9: Diels - Alder  By reaction Of polyphenylene sulfone (PPS)  Produce

BTPCPB (5 g, 7.24 mmol) and BEPS (1.928 g, 7.24 mmol) were added to 50 ml diphenyl ether and heated at 180 <0> C for 24 h under nitrogen atmosphere. In addition to the viscous slurry, BEPS (0.02 g, 0.08 mmol) was added and the mixture was stirred at 180 &lt; 0 &gt; C for an additional 12 hours. The reaction flask was cooled to room temperature. The polymer was precipitated in 200 ml acetone. The resulting white solid was washed with acetone and dried in a vacuum oven at 80 &lt; 0 &gt; C for 24 hours.

Example  10: PPS Of sulfonation ( SPPS )

In a typical sulfonation, PPS (2.5 g) was added to the flask under nitrogen and dissolved in 25 ml MC. The solution was cooled to 0 &lt; 0 &gt; C and chlorosulfonic acid (1.16 g, 9.96 mmol) diluted in 5.8 ml MC was added dropwise over 30 minutes. After the addition, the mixture was stirred at the same temperature for 3 hours. After the reaction, the mixture was poured into warm water. The filtered polymer was thoroughly washed with water and dried in vacuo at 80 DEG C for 24 hours. The sulfonation level was adjusted to the amount of chlorosulfuric acid (SPPS 1: 0.69 g, 5.92 mmol; SPPS 2: 0.92 g, 7.89 mmol).

Experimental Example  One: BTPCPB Wow BESP  Monomers and PPS Wow SPPS  Manufacture of Polymers

BTPCPB and BEPS monomers were synthesized according to the methods described in the above examples. Specifically, the BTPCPB monomer was synthesized by the Sonogashira coupling reaction (Example 2), the oxidation (Example 3), and the condensation reaction by the potassium hydroxide catalyst (Example 4). The BEPS monomer can be prepared by Friedel-Craft acylation (Example 5), bis-chloroaldehyde formation by reaction with POCl ₃ (Example 6), alkynation with NaOH (Example 7) and and oxidation with mCPBA (Example 8). The above process is summarized in FIG.

Then, the BPSCPB monomer and BEPS monomer were reacted with Diels-Alder reaction to synthesize a PPS polymer. A series of SPPS polymers were obtained by post-sulfonation of the PPS polymer with different proportions of chlorosulfuric acid. The method of synthesizing the PPS and SPPS polymers is shown in FIG.

The chemical structures of the synthesized BTPCPB and BEPS monomers were confirmed using a ¹ H NMR spectrum recorded with a Bruker DRX (400 MHz) spectrometer using DMSO-d6 as a solvent and tetramethylsilane (TMS) as an internal standard. The results are shown in Fig. As shown in FIG. 3A, the peak (H _a ) due to the phenylene proton located at the center of the BTPCPB was 6.68 to 6.97 ppm, and the peak (H _b ) due to the other protons on the surrounding pendant phenyl ring was the cyclopentadienone electron It moved somewhat downfield due to the dragging effect and appeared at 7.00 to 7.32 ppm. In the ¹ H NMR spectrum of BEPS shown in FIG. 3B, the peak (H _a ) due to the hydrogen atom present at the ortho position of the sulfone group appeared at 7.86 to 7.97 ppm, The peak (H _b ) appeared at 7.62 to 7.71 ppm. On the other hand, the peak (H _c ) of the alkyne group at the terminal was 3.31 ppm.

FIG. 4 shows a ¹ H NMR spectrum for identifying the chemical structure of synthesized PPS and SPPS polymers. As shown in FIG. 4A, the peak (H _a ) due to the phenyl ring protons located at the center of the multiple phenyl unit of the PPS polymer appeared at 6.17 to 6.30 ppm and the peak due to the hydrogen atom existing at the ortho position of the sulfone (H _b ) at 7.65 ppm, which is a down field. The peak (H _c ) due to the other pendant phenyl ring protons appeared at 6.53 to 7.54 ppm. As shown in 4b, peak (H _a) by the phenyl ring proton in the center of a multi-phenylene unit of the SPPS polymer peak due to hydrogen, which appeared at 6.05 to 6.40 ppm, present in the ortho position of the sulfone ( H _b ) remained unchanged at 7.52 to 7.73 ppm. This means that the sulfonation reaction did not occur on the diphenyl sulfone unit. The peak (H _c ) due to other pendant phenyl ring protons appeared at 6.54 to 7.50 ppm. Overall, it was found that the sulfonation reaction occurred selectively only on the six pendant phenyl groups on the side chain. The integration ratio of the proton peaks was confirmed by the molar ratio of each constituent of the copolymer.

Experimental Example  2: SPPS  Properties of Polymers

The thermal oxidation stability of the PPS and SPPS polymers was confirmed by thermogravimetric analysis performed with a Perkin-Elmer TGA-7 analyzer, and the results are shown in FIG. The molecular weight of the polymer was determined relative to polystyrene standards by gel permeation chromatography (GPC) using CHCl ₃ as eluent on a Perkin-Elmer series 200 HPLC and RI detector.

As shown in FIG. 5, the PPS polymer exhibited excellent thermal oxidation stability with a weight loss of 5% at 550 ° C. On the other hand, thermogravimetric analysis of SPPS in acid form showed three weight loss trends. Although the polymer was dried well at 100 DEG C for 24 hours, SPPS exhibited a primary weight loss of 0.5 to 1.5 wt% at 280 DEG C by water and a solvent. The secondary weight loss of SPPS appeared at 280 to 450 DEG C, corresponding to the decomposition of the sulfonic acid group. The tertiary weight loss above 500 &lt; 0 &gt; C is due to the decomposition of the polymer backbone. These results indicate that the primary weight loss of SPPS is analyzed as a loss of sulfonic acid group. As the sulfonation level increased, SPPS 1, 2 and 3 lost masses of 12.25, 14.70 and 17.72%, which were close to the theoretical values of 11.23, 15.47 and 19.61%, respectively. SPPS was found to dissolve in aprotic polar solvents such as dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) and was cast into DMSO solution to form a pale yellow transparent film. The molecular weight of the polymer was determined by gel permeation chromatography (GPC). The weight average molecular weight (Mw) and polydispersity (Mw / Mn) of the synthesized polymer were 75,000 to 88,000 and 2.3 to 2.7, respectively. As shown in Fig. 6, the IECs of SPPS 1, 2 and 3 are 1.49, 1.81 and 2.34 meq./g, and Nafion 211 is 0.91 meq./g. As the ratio of sulfonic acid groups was increased, the IEC value of the SPPS membrane increased. Figure 6 shows the water uptake of SPPS as a function of sulfonation at 80 &lt; 0 &gt; C. Compared to 32.13% of Nafion 211, the water absorption rates of SPPS 1, 2 and 3 membranes are 38.29, 50.19 and 74.52%. The SPPS membrane exhibited a relatively low water absorption rate as compared with the polyphenylene membrane containing a sulfonic acid group. The Cornelius membrane is randomly sulfonated on the polymer backbone, but the SPPS membrane according to the invention is selectively sulfonated on six pendant phenyl rings, which may affect hydrophilic and hydrophobic forms . Water absorption, on the other hand, is highly dependent on IEC. Therefore, the number of water molecules absorbed per unit sulfonic acid group can be used to evaluate the relationship between the polymer structure and the water absorption rate. ? can be calculated by the following equation:? = (10 x WU) / (IEC x 18). Lambda for SPPS ranges from 14 to 18 in water. SPPS film dimensional change can be evaluated by comparing the hydrated state the through-plane (Δ t) and the in-plane (Δ l) and dry-film. The Δ t values of the SPPS 1, 2 and 3 membranes are 17.21, 20.42 and 27.54%, and the Δ 1 values are 15.28, 19.83 and 27.17%, respectively (Table 1). A small change in through-plane with high proton conductivity is a desirable behavior for maintaining dimensional stability during PEMFC stack operation. The proton conductivity of a series of SPPS was measured as a function of the mole fraction of sulfate groups. The proton conductivity of the SPPS membranes was measured at 80 to 80 DEG C (Fig. 7) under 80% RH and at 80 DEG C (Fig. 8) at 30 to 90% RH. The results were estimated from AC impedance spectroscopy data and the results under different conditions are shown in Figures 7 and 8 compared to Nafion 211. The measured SPPC membranes had proton conductivities in the range of 66.4 to 110.2 mS / cm, and Nafion 211 was 102.7 mS / cm at 80 ° C with 90% humidity. At 80 ℃ and various humidity conditions, the proton conductivity of the SPPS membranes increased with increasing humidity. Conductivity of all samples increased with increasing temperature, and films with higher IEC values showed higher proton conductivity. The proton conductivity of SPPS 3 membrane was 80 ~ 90% RH, higher than Nafion 211 at 80 ℃. For all membranes, SPPS, Nafion 211 and SPES 40 (sulfonated polyether sulfone containing sulfonic acid groups containing 40 mole% of 4,4-biphenol) at ex situ ) Hydrogen peroxide test. Tests were performed on hot Fenton reagents for 9 hours as accelerated chemical degradation tests on membranes. The weight loss of the membrane after testing was expressed as a function of time, as shown in Fig. 9, of the mass of the remaining membrane. It was confirmed that Nafion 211 did not undergo chemical decomposition at all, and all SPPS membranes retained more than 88% by weight after 9 hours. However, S-PES 40 was mostly degraded after 9 hours. This indicates that the hydrocarbon film of all carbon-carbon bonds is relatively stable under extreme chemical-oxidation conditions and can therefore be a substitute candidate for Nafion. Figure 10 compares the measured polarization and power densities for SPPS 1, 2 and 3 and Nafion 211 at fully humidified inlet conditions (RHa / RHc = 100% / 100%). The maximum power densities of SPPS 1, 2 and 3 and Nafion 211 were approximately 0.41, 0.52, 0.67 and 0.62 W / cm ² , respectively. This means that SPPS 3 can exhibit fuel cell performance somewhat higher than Nafion 211 at the full range of current densities. A polyphenylene sulfone film containing a sulfonic acid group having hydrophilic and hydrophobic moieties in its main chain can effectively achieve better cell performance.

Polymer Tertiary IEC
(meq./g) Water Absorption Rate (%)
(@ 30 ℃) Water Absorption Rate (%)
(@ 80 ° C) Δ t (%) Δ 1 (%) Degree of proton
(mS / cm) SPPS 1 1.49 26.43 38.29 17.21 15.28 66.4 SPPS 2 1.81 46.11 50.19 20.42 19.83 90.1 SPPS 3 2.34 68.94 74.52 27.71 26.83 110.2 Nafion 211 0.91 - 32.13 14.10 13.84 102.7

Experimental Example  3: Preparation and Characterization of Polymer Membranes

The polymer was dissolved in DMSO to obtain a 20 wt% transparent solution, which was cast at elevated temperatures of 60, 80, 100 and 120 캜 to prepare a membrane (25 μm).

The membrane was vacuum dried at 100 ° C for 24 hours, weighed and immersed in distilled water at 30 ° C and 80 ° C for 24 hours. Wipe the wet film dry and quickly weigh again. The water absorption rate of the membrane was recorded as the following weight percentages: Water Absorption Rate = (W _wet -W _dry ) / W _dry } × 100%, W _wet and W _dry are the weights of the wet film and the dry film, respectively. The membranes were immersed in water at room temperature for 24 hours to confirm dimensional changes. The thickness and the change in length was calculated by the following _{equation: Δt = {(tt s)} / t s} × 100%, Δl = {(ll s) / l s} × 100%, t s and l _s are dried, respectively The thicknesses and diameters of the membranes, t and l, correspond to the similarity of the membranes that were immersed in water for 24 hours each. The titration method was used to determine the IEC of the membrane. The acid form (H ⁺ ) membrane was immersed in a 1.0 M NaCl solution for 24 hours to convert the H ⁺ ion to Na ⁺ ion to convert it to the sodium salt form. The exchanged H ⁺ ions in the solution were titrated with 0.02 N NaOH solution. The theoretical IEC calculated from the sulfonation level was obtained from the following equation: IEC (meq./g) = mmol ion concentration / mass of dry film at 25 ° C. The proton conductivity across the plane direction of the membrane was measured using a Scribner membrane test system (PSM 1735) with a Newtons 4th Ltd (N4L) impedance analysis interface (PSM 1735) at a temperature of 40-80 캜, a humidity of 80% and a temperature of 80 캜 and a humidity of 30-90% MTS-740). The EIS was performed under open circuit conditions by applying a low alternating voltage (10 mV) and varying the frequency of the alternating voltage from 1 to 1 × 10 ⁵ Hz.

A membrane electrode assembly (MEA) with an active area of 9 cm ² was prepared by decal method based on a catalyst coated membrane (CCM). A 20 wt% wet-proofed Toray carbon paper (TGPH-060, Toray Inc.) 190 μm thick was used as a gas diffusion layer (GDL) for the anode and cathode sides. Carbon supported platinum (Hispec 13100, Johnson Matthey Inc.) was used as a catalyst for both the positive and negative electrodes. In the present invention, the load of the catalyst layer on the positive electrode and the negative electrode was 0.2 mgPt / cm &lt; ^{2 &} gt ;. Thereafter, the catalyst layer was transferred to the membrane by decal method at 130 占 폚 and 10 MPa for 5 minutes to form CCM. The GDL was placed on the anode side of the CCM and the negative electrode to form the MEA. The cell performance was confirmed with a PEMFC test station (CNL Energy Co.).

Experimental Example  2: Accelerated chemical Membrane decomposition

The membrane decomposition was studied by immersion in Fenton reagent (4 ppm Fe ^{2 +} , 3% H ₂ O ₂ ) at 75 ° C. SPPS membranes, polyether sulfone (S-PES 40) containing a general linear sulfonic acid group, and Nafion 211 were used as samples. The initial sample weight was measured and the sample was immersed in a solution of iron II sulfate heptahydrate dissolved in 45 ml of water, heated to 75 ° C and 5 ml of 30% hydrogen peroxide was added to the solution. During the experiment, membrane samples were periodically taken out for weighing. The sample was washed with distilled water to terminate the decomposition reaction and the exposed membrane was dried prior to final weight measurement.

Claims (11)

A cross-linked copolymer comprising a hydrophilic repeating unit represented by the following formula (1) and a hydrophobic repeating unit represented by the following formula (2)
[Chemical Formula 1]

(2)

In Formula 1, x is an integer of 0 to 5.
A process for producing a cross-linked copolymer according to claim 1,
A first step of preparing a benzene compound in which two molecules of cyclopentadienone substituted with at least two phenyl groups are bonded to each other at a para position;
A second step of preparing a compound containing two or more benzene rings including alkene groups at both terminals and connected to a sulfonyl group;
A third step of mixing the compounds prepared in the first and second steps to form a cross-linked copolymer by Diels-Alder reaction; And
And a fourth step of post-sulfonating the cross-linked copolymer in the third step.
3. The method of claim 2,
Wherein the benzene compound in the first step is a compound represented by the following formula (3).
(3)

3. The method of claim 2,
Wherein the compound of the second step is a compound represented by the following formula (4).
[Chemical Formula 4]

5. An ion conductive polymer represented by the following formula (5), which comprises the cross-linked copolymer according to claim 1 or a cross-copolymer prepared by the method according to any one of claims 2 to 4.
[Chemical Formula 5]

In Formula 5, x is an integer of 0 to 5.
6. The method of claim 5,
Wherein the sulfonic acid group content is 20 to 40%.
6. The method of claim 5,
Wherein the polymer has a molecular weight of 50,000 to 300,000.
An ion conductor as a molding formed of a resin composition comprising the ion conductive polymer according to claim 5.
9. The method of claim 8,
Wherein the molded body is an electrolyte membrane, a separation membrane, or a water treatment membrane.
A battery comprising an electrolyte membrane or a separation membrane formed from a resin composition comprising the ion conductive polymer according to claim 5.
11. The method of claim 10,
Wherein the battery is a proton exchange membrane fuel cell, a direct methanol fuel cell, or a redox flow cell.

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