KR102260088B1 - Anion-exchange membrane, preparation method thereof and alkaline anion-exchange membrane fuel cell comprising the same - Google Patents

Abstract

The present invention relates to an anion exchange membrane, a method for manufacturing the same, and an alkali anion exchange membrane fuel cell comprising the same, and more particularly, to quaternary ammonium polyphenylene oxide and quaternary ammonium oligomeric silsesquioxane. Prepare an anion exchange membrane containing a, and can be applied as an anion exchange membrane fuel cell having excellent ion conductivity and alkali stability due to the steric hindrance of the long chain present in the quaternary ammonium polyhedral oligomeric silsesquioxane have.

Description

Anion exchange membrane, manufacturing method thereof, and alkaline anion exchange membrane fuel cell comprising same

The present invention relates to an anion exchange membrane, a method for manufacturing the same, and an alkali anion exchange membrane fuel cell comprising the same, and more particularly, to quaternary ammonium polyphenylene oxide and quaternary ammonium oligomeric silsesquioxane. To prepare an anion exchange membrane comprising a, and to apply it as an anion exchange membrane fuel cell having excellent ion conductivity and alkali stability due to the steric hindrance of a long chain present in the quaternary ammonium polyhedral oligomeric silsesquioxane It's about technology.

A fuel cell is a power generation system that continuously supplies fuel and an oxidizer and extracts chemical energy when they react as electric power. Depending on the type of electrolyte used, the fuel cell may be an alkaline fuel cell, a phosphoric acid fuel cell, and a solid polymer electrolyte fuel cell having a relatively low operating temperature, or a molten carbonate fuel cell or a solid oxide electrolyte fuel cell operating at a high temperature. is distinguished by

On the other hand, in the case of a fuel cell using an anion exchange membrane (AEM), the availability of non-noble metal electrode catalysts, easy oxidation of fuel, fast reduction rate of oxygen, crossover of reduced fuel, catalyst Due to its many advantages, such as enhanced carbon monoxide resistance and relatively simple water management, it has recently received a lot of attention compared to the proton exchange membrane fuel cell (PEMFC). Accordingly, research on an anion exchange membrane as an alternative to the proton exchange membrane (PEM) is proceeding. is becoming

Such an anion exchange membrane fuel cell generates electrical energy through a process ^{in which OH − ions are generated at the anode through a chemical reaction and conducted to the cathode.} Such an anion exchange membrane generally has a structure in which a conductor capable of conducting ^{OH − ions is introduced at a benzylic position of a polymer backbone or a conductor is attached to a side chain.} Further, PBI (poly (benzimidazolium)) or poly (arylene piperidinium) the main chain itself, OH ttieo cations, such as the series ^polymer is gatgido a structure capable of performing a group capable of conducting an ion conduction.

The anion exchange membrane forms ion clusters due to electrostatic attraction between hydrophilic conductive groups, as well as phase separation from the hydrophobic region of the polymer, allowing OH ^- ions to It forms an ionic channel, which is a conduction path. However, since the OH ⁻ ion has strong nucleophilicity, a chemical side reaction with a conductive group having electrophilicity is accompanied, which is accelerated at high temperature. Not only the degradation reaction of the conductor but also the decomposition reaction of the polymer main chain occur, reducing the loss of ionic conductivity and physical properties of the anion exchange membrane, thereby lowering the performance of the alkaline fuel cell and ultimately reducing the long-term lifespan. There is a need for research to develop an anion exchange membrane having ion conductivity.

Accordingly, the present inventors prepare an anion exchange membrane comprising quaternary ammonium polyphenylene oxide and quaternary ammonium oligomeric silsesquioxane, and the quaternary ammonium oligomeric silses Due to the steric hindrance of the long chain present in sesocquiic acid, the present invention was completed by focusing on the application as an anion exchange membrane fuel cell having excellent ionic conductivity and alkali stability.

Patent Document 1. Japanese Patent Application Laid-Open No. 10-2010-0107010 Patent Document 2. Korean Patent Publication No. 10-1545229 Patent Document 3. Korean Patent Publication No. 10-0776375

The present invention has been devised in consideration of the above problems, and an object of the present invention is to prepare an anion exchange membrane comprising quaternary ammonium polyphenylene oxide and quaternary ammonium oligomeric silsesquioxane and to provide an anion exchange membrane fuel cell having excellent ion conductivity and alkali stability due to the steric hindrance of a long chain present in the quaternary ammonium polyhedral oligomeric silsesquioxane.

The present invention for achieving the above object is a quaternary ammonium-containing polyphenylene oxide (QPPO) and polyhedral oligomeric silsesquioxane (POSS) having a repeating unit represented by the following formula (1) An anion exchange membrane is provided.

[Formula 1]

Wherein x is a mole fraction (%) in the repeating unit, wherein x is an integer of 1 to 99.

The POSS may be a quaternary ammonium POSS (QPOSS) represented by the following Chemical Formula 2.

[Formula 2]

R is a compound represented by the following Chemical Formula 2-1.

[Formula 2-1]

The weight ratio of the QPOSS to the QPPO may be 0.1 to 10% by weight.

In addition, the present invention provides an alkaline fuel cell comprising the anion exchange membrane according to the present invention.

In addition, the present invention comprises the steps of (a) dissolving a quaternary ammonium polyphenylene oxide (QPPO) having a repeating unit represented by the following Chemical Formula 3 in a first solvent to obtain a QPPO solution; (b) mixing polyhedral oligomeric silsesquioxane (POSS) in a second solvent to obtain a POSS solution; (c) mixing the QPPO solution and the POSS solution; (d) forming the mixture of step (c) in the form of a film; And (e) provides a method for producing an anion exchange membrane comprising the step of immersing the formed membrane in a hydroxide solution and then drying again.

[Formula 3]

Wherein x is a mole fraction (%) in the repeating unit, wherein x is an integer of 1 to 99.

The POSS may be a quaternary ammonium POSS (QPOSS) represented by the following Chemical Formula 2.

[Formula 2]

R is a compound represented by the following Chemical Formula 2-1.

[Formula 2-1]

The first solvent and the second solvent are the same as or different from each other, and each independently N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylformamide, diethylformamide, dimethylacetamide, methanol, ethanol and ether It may be one or a mixture of two or more selected from among.

Step (c) may be performed at room temperature for 0.5 to 24 hours.

The weight ratio of the POSS to QPPO in step (c) may be 0.1 to 10% by weight.

Step (d) may be performed by casting the mixture of step (c) on a substrate and then drying the cast film.

The first solvent is N-methyl-2-pyrrolidone, the second solvent is dimethylsulfoxide, and the step (c) is performed at room temperature for 3 to 5 hours, and in the step (c), QPPO is The weight ratio of the POSS for the POSS is 2 to 4% by weight, and the step (d) is performed by casting the mixture of step (c) on a substrate and then drying the cast film, and the drying temperature of the casting film is 50 to 70 ℃, the drying time of the casting film is carried out for 11 to 13 hours, the hydroxide solution is 0.8 to 1.2 M potassium hydroxide solution, the immersion time in step (e) is 22 to 26 hours, after the immersion Drying time may be 22 to 26 hours.

According to the present invention, an anion exchange membrane comprising quaternary ammonium polyphenylene oxide and quaternary ammonium oligomeric silsesquioxane is prepared, and the quaternary ammonium polyhedral oligomeric sil It is possible to provide an anion exchange membrane fuel cell having excellent ion conductivity and alkali stability due to the steric hindrance of the long chain present in sesquioxane.

1 is (a) the process of synthesizing quaternary ammonium polyphenylene oxide (QPPO) from Preparation Example 1 and (b) quaternary ammonated polyhedral oligomeric silsesqui from Preparation Example 2 of the present invention. It is a schematic diagram showing the process of synthesis of oxane (QPOSS).
2 is (a) polyphenylene oxide (PPO) and (b) brominated polyphenylene oxide (Br-) used in the synthesis of quaternary ammonium polyphenylene oxide (QPPO) from Preparation Example 1 of the present invention; PPO) and (c) ¹ H NMR (nuclear magnetic resonance) of quaternary ammonium polyphenylene oxide (QPPO) and (d) FTIR (Fourier transform infrared) spectra of PPO, Br-PPO and QPPO.
^{3 is (a) 1} H NMR (nuclear magnetic resonance) and (b) FTIR (Fourier transform infrared) spectra of QPPO synthesized in Preparation Example 1 and QPOSS synthesized in Preparation Example 2 of the present invention.
4 is a FTIR (Fourier transform infrared) spectrum of QPPO synthesized in Preparation Example 1 and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3 of the present invention.
5 is a TGA (thermogravimetric analysis) graph of QPPO synthesized in Preparation Example 1 and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3 of the present invention.
Figure 6 is (a) of the QPPO synthesized from Preparation Example 1 of the present invention and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized from Examples 1 to 3 (a) water uptake, ( b) dimensional stability and (c) a graph showing the content of bound water.
7 shows (a) hydroxide ion conductivity and (b) of QPPO synthesized in Preparation Example 1 of the present invention and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3; This is the Arrhenius plot.
8 is a view showing the hydroxide ions over time at 80° C. of QPPO synthesized in Preparation Example 1 and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3 of the present invention. This is a graph showing the conductivity.

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

The present invention provides an anion exchange membrane comprising quaternary ammoniumized polyphenylene oxide (QPPO) and polyhedral oligomeric silsesquioxane (POSS) having a repeating unit represented by the following formula (1).

[Formula 1]

Wherein x is a mole fraction (%) in the repeating unit, wherein x is an integer of 1 to 99.

Conventional anion exchange membranes of alkali anion exchange membrane fuel cells have a problem in that ion conduction characteristics and alkali stability are inversely proportional to each other. In the present invention, by mixing the quaternary ammonium polyhedral oligomeric silsesquioxane with the quaternary ammonium polyphenylene oxide, the quaternary ammonium oligomeric silsesquioxane present in the quaternary ammonium polyhedral oligomeric silsesquioxane is mixed. An object of the present invention is to provide an anion exchange membrane having excellent ion conductivity and alkali stability due to steric hindrance of the chain.

The POSS may be a quaternary ammonium POSS (QPOSS) represented by the following Chemical Formula 2.

[Formula 2]

R is a compound represented by the following Chemical Formula 2-1.

[Formula 2-1]

The weight ratio of the QPOSS to the QPPO may be 0.1 to 10% by weight, specifically 0.5 to 8% by weight, more specifically 1 to 6% by weight, more specifically 2 to 4% by weight.

In addition, the present invention provides an alkaline fuel cell comprising the anion exchange membrane according to the present invention.

In addition, the present invention comprises the steps of (a) dissolving a quaternary ammonium polyphenylene oxide (QPPO) having a repeating unit represented by the following Chemical Formula 3 in a first solvent to obtain a QPPO solution; (b) mixing polyhedral oligomeric silsesquioxane (POSS) in a second solvent to obtain a POSS solution; (c) mixing the QPPO solution and the POSS solution; (d) forming the mixture of step (c) in the form of a film; And (e) provides a method for producing an anion exchange membrane comprising the step of immersing the formed membrane in a hydroxide solution and then drying again.

[Formula 3]

Wherein x is a mole fraction (%) in the repeating unit, wherein x is an integer of 1 to 99.

The POSS may be a quaternary ammonium POSS (QPOSS) represented by the following Chemical Formula 2.

[Formula 2]

R is a compound represented by the following Chemical Formula 2-1.

[Formula 2-1]

The first solvent and the second solvent are the same as or different from each other, and each independently N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylformamide, diethylformamide, dimethylacetamide, methanol, ethanol and ether It may be one or a mixture of two or more selected from among. Specifically, the first solvent may be N-methyl-2-pyrrolidone, and the second solvent may be dimethyl sulfoxide, but is not limited thereto.

Step (c) may be performed at room temperature for 0.5 to 24 hours, specifically for 1 to 12 hours, more specifically for 2 to 8 hours, and more specifically for 3 to 5 hours.

The weight ratio of the POSS to QPPO in step (c) may be 0.1 to 10% by weight, specifically 0.5 to 8% by weight, more specifically 1 to 6% by weight, more specifically 2 to 4% by weight have.

Step (d) may be performed by casting the mixture of step (c) on a substrate and then drying the cast film.

The process of drying the casting film is specifically 30 to 150 ℃, more specifically 40 to 100 ℃, more specifically 50 to 70 ℃ at a temperature of, specifically 1 to 24 hours, more specifically 5 to It may be carried out for 20 hours, more specifically 11 to 13 hours, and preferably vacuum drying, but is not limited thereto.

In step (e), the hydroxide solution may specifically be potassium hydroxide at a concentration of 0.1 to 5 M, more specifically 0.5 to 3 M concentration, and more specifically 0.8 to 1.2 M concentration, but is limited thereto. no.

In addition, the immersion time may be specifically 1 to 50 hours, more specifically 10 to 30 hours, more specifically 22 to 26 hours, and the drying time after the immersion is specifically 1 to 50 hours, more Specifically, it may be 10 to 30 hours, more specifically 22 to 26 hours. Through this process, the bromination group (Br ⁻ ) present in the resulting film can be converted into the form of a hydroxyl group (OH ^{− ).}

Specifically, the quaternary ammonium polyphenylene oxide (QPPO) having a repeating unit represented by Formula 3 is (1) poly(2,6-dimethyl-1,4-phenylene oxide), N-bromo After mixing succinimide (NBS) and azobisisobutyronitrile (AIBN), specifically 100 to 200 ° C, more specifically 120 to 160 ° C, more specifically 125 to 150 ° C. obtaining phenylene oxide (Br-PPO); (2) The brominated polyphenylene oxide and trimethylammonium (TMA) solution are mixed and reacted at 30 to 200 ° C., more specifically 40 to 150 ° C., more specifically 50 to 70 ° C. It may be prepared including; producing an ammoniumized PPO (QPPO).

In addition, the quaternary ammonated polyhedral oligomeric silsesquioxane (QPOSS) represented by Chemical Formula 2 is polyhedral oligomeric silsesquioxane (POSS) represented by the following Chemical Formula 4 and a quaternary ammonium reagent It can be prepared through the step of reacting.

[Formula 4]

R is a compound represented by the following Chemical Formula 4-1.

[Formula 4-1]

The step of reacting the POSS and the quaternary ammonium reagent may be performed in the presence of a solvent, and triethyleneamine and tetrahydrofuran (THF) may be used as the solvent, but is not limited thereto.

The reaction of the POSS and the quaternary ammonium reagent may be specifically carried out at 30 to 200 °C, more specifically 40 to 150 °C, more specifically 50 to 70 °C.

The quaternary ammonium reagent is selected from glycidyltrimethylammonium chloride (GTMAC), glycidyltriethylammonium chloride (GTEAC), glycidyltrimethylammonium bromide (GTMAB) and chloromethylbenzyltrimethylammonium chloride (CMBTMAC) One or more types may be used, but the present invention is not limited thereto. Specifically, glycidyltrimethylammonium chloride can be used.

In particular, although not explicitly described in the following Examples or Comparative Examples, in the process of manufacturing the anion exchange membrane of the present invention, various types of POSS and solvents, (c) step performing conditions, (c) QPPO in step (c) The torsional strength was measured for the anion exchange membrane prepared by varying the weight ratio of the POSS to the POSS, the conditions for performing step (d) and the conditions for performing step (e), and the roughness of the outer surface was measured through a scanning electron microscope (SEM). Confirmed.

As a result, unlike other types of POSS and solvents and in different numerical ranges, when all of the following conditions were satisfied, there was no fracture even after 300 torsional strength measurements, and the initial outer surface roughness was quite smooth, and the torsional strength was 300 times. No change in roughness and defects of the outer surface were observed even after measurement.

However, when any one of the following conditions was not satisfied, not only failure occurred according to torsional strength measurement, but also significant defects and changes in roughness were observed on the outer surface.

(i) POSS is quaternary ammonium POSS (QPOSS) represented by the following formula (2), (ii) the first solvent is N-methyl-2-pyrrolidone, (iii) the second solvent is dimethyl sulfoxide, ( iv) (c) is carried out at room temperature for 3 to 5 hours, (v) the weight ratio of the POSS to QPPO in (c) is 2 to 4 wt%, (vi) (d) is the step (c) ) after casting the mixture on the substrate and then drying the cast film, (vii) the drying temperature of the casting film is 50 to 70 ℃, (viii) the drying time of the casting film is carried out for 11 to 13 hours, (vii) ) hydroxide solution is 0.8 to 1.2 M potassium hydroxide solution, (x) the immersion time in step (e) is 22 to 26 hours, (xi) the drying time after soaking in step (e) is 22 to 26 hours

[Formula 2]

R is a compound represented by the following Chemical Formula 2-1.

[Formula 2-1]

Hereinafter, manufacturing examples and embodiments according to the present invention will be described in detail with accompanying drawings.

Preparation Example 1: Synthesis of quaternary ammonated polyphenylene oxide (QPPO)

Poly(2,6-dimethyl-1,4-phenylene oxide) was mixed with N-bromosuccinimide (NBS) and azobisisobutyronitrile (AIBN) and reacted at 135° C. to brominated polyphenyl Renoxide was obtained. A trimethylamine solution was mixed with the brominated polyphenylene oxide and reacted at 60 ° C. to synthesize quaternary ammonium polyphenylene oxide (QPPO) (FIG. 1(a)).

Preparation Example 2: Synthesis of quaternary ammonated polyhedral oligomeric silsesquioxane (QPOSS)

Polyhedral oligomeric silsesquioxane (POSS), triethylamine, and glycidyltrimethylammonium chloride were reacted at 60° C. in a tetrahydrofuran (THF) solvent, and the quaternary ammonium polyhead represented by the following Chemical Formula 2 Ral oligomeric silsesquioxane (QPOSS) was synthesized (FIG. 1(b)).

Examples 1 to 3: Preparation of QPPO-QPOSS anion exchange membrane

A first solution was obtained by dissolving QPPO synthesized in Preparation Example 1 in N-methyl-2-pyrrolidone, and QPOSS synthesized in Preparation Example 2 was mixed with dimethyl sulfoxide to obtain a second solution. Then, the first solution and the second solution were mixed at room temperature for 4 hours. The mixture was cast on a clear glass Petri dish and then dried under vacuum at 60° C. for 12 hours to form a film. A QPPO/QPOSS anion exchange membrane was prepared by immersing the formed membrane in 1 M potassium hydroxide solution at room temperature for 24 hours, and then drying it again at room temperature for 24 hours. The weight ratios of QPOSS to QPPO were 1, 3, and 5 wt%, respectively, to Examples 1 to 3, and QPPO-QPOSS-1, QPPO-QPOSS-3 and QPPO-QPOSS-5 according to the weight ratio. named.

2 is (a) polyphenylene oxide (PPO) and (b) brominated polyphenylene oxide (Br-) used in the synthesis of quaternary ammonium polyphenylene oxide (QPPO) from Preparation Example 1 of the present invention; PPO) and (c) ¹ H NMR (nuclear magnetic resonance) of quaternary ammonium polyphenylene oxide (QPPO) and (d) FTIR (Fourier transform infrared) spectra of PPO, Br-PPO and QPPO.

2 (a) to (b), the shift at 6.4 to 6.8 ppm is assigned to the aryl proton of PPO (Fig. 2 (a)). The proton corresponding to the benzyl group was found to be 1.92 to 2.25 ppm (FIG. 2(a)). In addition, the successful formation of brominated PPO can be confirmed through the sharp peak observed at about 4.27 ppm (Fig. 2(b)). In addition, the peak corresponding to the methylene peak (-CH ₂ Br) was reduced to 4.5 ppm, and a sharp new chemical shift corresponding to the proton of the trimethylammonium cation appeared at about 3.2 ppm, confirming that successful quaternary ammoniumization was achieved ( Figure 2(c)).

Referring to FIG. 2(d), in FTIR analysis, 1600 cm ^{−1 corresponds} to C=C bond stretching, and ^{the peak at 1190 cm −1} is determined to be due to COC stretching of PPO. The extension oscillation bands (C-Br) observed at 730 cm ^-1 and 1080 cm ^{-1 in brominated PPO can confirm the bromination of PPO.} After quaternary ammonium treatment, ^{the peak at 730 cm −1} disappears and a new band assigned to NH stretch is stimulated near ^{3325 cm −1} _{to convert the -CH 2} Br group to the -N ⁺ (CH ₃ ) ₃ group. conversion was confirmed.

^{3 is (a) 1} H NMR (nuclear magnetic resonance) and (b) FTIR (Fourier transform infrared) spectra of QPPO synthesized in Preparation Example 1 and QPOSS synthesized in Preparation Example 2 of the present invention.

Referring to FIG. 3 , peaks near 1.73 ppm (Ha), 2.79 ppm (Hb) and 3.4 ppm (Hc) are related to chemical shifts of protons from _{-CH 2} Si, -CH ₂ - and -CH _{2 N, respectively.} has been The new peak appearing near 4.02 ppm (Hd) in QPOSS corresponds to the chemical shift of the methyl proton of glycytyltrimethyl ammonium chloride (GTMAC), confirming the successful quaternary ammoniumization of OPOSS. In addition, NH ₃ ⁺ stretching and banding oscillations were observed at ^{3430 cm -1} and 1610 cm ^{-1 , respectively, and the peaks at 1225 cm -1} , 1080 cm ^-1 and 705 cm ^-1 were CN stretching, Si-O-Si, respectively. It can be confirmed that this is due to the presence of symmetrical stretching and Si-C stretching. In addition, ^{the absorption peaks at 2810 cm -1} and 2897 cm ^-1 were assigned to the CH extensions of the methoxy and methylene groups, respectively, and in QPOSS, the absorption bands with moderate intensity observed at ^{1475 cm -1 were 4} It was confirmed that this is due to the symmetric stretching of the NC bond in the secondary ammonium group. In addition, in reaction with glycidyltrimethyl ammonium chloride, the peak corresponding _{to NH 3} ^{+ banding shifted to 1580 cm -1} , and a new peak belongs to the quaternary ammonium group appeared ^{at 1738 cm -1 , and nanocages such as OPOSS material} It can be confirmed that was successfully grafted with a quaternary ammonium group.

4 is a FTIR (Fourier transform infrared) spectrum of QPPO synthesized in Preparation Example 1 and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3 of the present invention.

Referring to FIG. 4 , a ^{broad band of about 3500 cm −1} is assigned to the extension vibration of OH and ^{a band of 1020 cm −1} corresponds to the extension vibration of C—OH, respectively. The bands at 1460 cm ⁻¹ and 1600 cm ⁻¹ _{belong to the characteristic CH 2} bending and C=C stretching of the phenyl group ^{, and the peak at 1190 cm −1} is due to the COC stretching of PPO, respectively. was confirmed. In addition, ^{the band at 1300 cm −1} is considered to belong to the quaternized CN stretching of PPO. ^{In addition, a new absorption band at 1688 cm −1} in all membranes other than the pure QPPO membrane originates from QPOSS, indicating the formation of a hybrid composite membrane.

5 is a TGA (thermogravimetric analysis) graph of QPPO synthesized from Preparation Example 1 and Q-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized from Examples 1 to 3 of the present invention.

Referring to FIG. 5 , it was confirmed that the primordial degradation below 230° C. with a weight loss of 6 to 12% resulted from the absorption/bound water present in the membrane and evaporation of the residual solvent. In addition, it was confirmed that the second weight loss from 230 °C to 350 °C belonged to the cleavage of the quaternary ammonium group present in the membrane, and the final weight loss above 350 °C was due to decomposition of the polymer backbone. In addition, it was confirmed that, except for decomposition that occurred up to 230 °C, the thermal stability of the composite material was improved through the addition of QPOSS nanoparticles below 450 °C, which was attributed to the strong interfacial interaction between the filler particles and the polymer matrix. However, compared to the pure membrane (QPPO), the composite membrane (QPPO-QPOSS) showed more weight loss at high temperature. It is considered that this may be due to the decomposition of QPOSS, which has lower thermal stability than that of the polymer main chain at high temperature in the composite membrane. It was confirmed that all the prepared membranes exhibited a thermal decomposition temperature of 200 °C or higher, thereby providing sufficient thermal stability for application to fuel cells operating at 100 °C or lower.

Properties Sample designation QPPO QPPO-QPOSS-1 QPPO-QPOSS-3 QPPO-QPOSS-5 Tensile strength ( MPa ) 9.3±0.5 12.9±1.0 15.4±0.4 8.6±0.8 Elongation at break (%) 25.3±1.2 22.9±2.2 18.8±1.9 26.2±1.8 IEC ( meq g ^-One ) 2.33±0.03 3.95±0.02 4.81±0.04 4.47±0.03 Bound water (%) 1.68 1.71 1.75 2.26 Bulk water (%) 15.72 4.99 6.35 5.64 Activation energy
( KJ mol ^-One ) 9.15 7.17 8.56 9.00

Table 1 shows the tensile strength, elongation at break, and ion exchange capacity (IEC) of QPPO synthesized in Preparation Example 1 and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3 ), bound water, free water and activation energy are shown.

Referring to Table 1, the pure QPPO membrane exhibited a tensile strength of 9.3 MPa and an elongation at break of 25.3%. It can be seen that the tensile strength of the membrane increased as the QPOSS increased to 3 wt%. Conversely, the trend of elongation is considered to be contrary to that a high content of filler results in increased stiffness and decreased flexibility of the membrane. In addition, it can be confirmed that the maximum tensile strength of 15.4 MPa with an elongation at break of 18.8% of the QPPO-QPOSS-3 membrane was achieved. do.

In addition, although water as a medium facilitates the transport of charge carriers, it can be seen that an excess of water leads to loss of mechanical stability and lowering of ionic conductivity, and an ideal anion exchange membrane has adequate water uptake, mechanical properties and It can be seen that excellent conductivity must be maintained. The wettability and longitudinal expansion of QPPO-QPOSS-3 (WU = 8.1 %; Swelling = 6.3 %) were QPPO-QPOSS-1 (WU = 6.7 %; Swelling = 5.3 %) and QPPO-QPOSS-5 QPPO-QPOSS-5 (WU = 7.9 %; Swelling = 5.2 %) was found to be higher than that of the membrane, and this value was also relatively smaller than that of the QPPO membrane (WU = 17.4 %, swelling = 7.2 %) with better stability. The increased hydrophilicity occurred due to the presence ^{of a large number of -N +} (CH ₃ ) ₃ groups in the membrane at high concentrations of QPOSS. In addition, grafting of glycidyltrimethylammonium chloride (GTMAC) may reduce the crystallinity of POSS, which may lead to deterioration of the crystallinity of the composite film. These are believed to be attributable to the water-membrane interaction and the high adsorption of water due to up to 3 wt % of the filler.

Figure 6 is (a) of the QPPO synthesized from Preparation Example 1 of the present invention and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized from Examples 1 to 3 (a) water uptake, ( b) dimensional stability and (c) a graph showing the content of bound water.

Referring to FIG. 6 , the moisture content and expansion rate increased with temperature. This is thought to be due to the increased mobility of the polymer chains at high temperatures, resulting in a wider space to contain water. The in-plane expansion of the QPPO-QPOSS-3 membrane was found to be 2.3 times lower than that of the pure QPPO membrane at 80 °C, confirming that the dimensional stability was improved. As the QPOSS content increased to 3% by weight, the ^{IEC of the OH-} form membrane showed that every single QPOSS molecule contained eight quaternary ammonium ion exchangers, due to the large amount of hydroxide ion clusters formed in the quaternized POSS structure. It increased from 2.33 meq g ⁻¹ to 4.81 meq g ⁻¹ of the pristine QPPO membrane. On the other hand, it was confirmed that the reduction in the number of polar groups available for aggregation and blocking of ion-exchangeable sites and thus for water absorption and reduction of free volume decreased IEC and moisture content in high concentration fillers.

There are two main types of water present in membranes, free water and bound water, where free water can fill ion conducting channels and bound water forms an ionic solvent shell. Bound water has a greater effect on ion conduction at high temperatures and therefore does not evaporate as easily as bulk/free water. QPPO-QPOSS-5 showed the highest bound water content (2.26%) among all membranes. However, the bulk water (free water) was lower than that of the QPPO-QPOSS-3 membrane due to insufficient free space as a result of QPOSS aggregation. The presence of high bulk water (15.72%) and low bound water (1.68%) decreased the conductivity (18.4 mS cm- ¹ at 80 °C) for the pure QPPO membrane, and the low free water (4.99%) of the QPPO-QPOSS-1 membrane. ) was also found to be insufficient to support effective ion transport. The observed ionic conductivity was about 33.8 mS cm ⁻¹ at 80° C., and was higher for the QPPPO-QPOSS-3 membrane (71.3 mS cm ⁻¹ at 80° C.) with 1.75% and 6.35% bound and bulk/free water. A high conductivity was observed. Therefore, it can be confirmed that the best balance between bound water and bulk water (free water) is required to support effective ion transport.

7 shows (a) hydroxide ion conductivity and (b) of QPPO synthesized in Preparation Example 1 of the present invention and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3; This is the Arrhenius plot.

The ^{ionic conductivity of OH-} type membranes is an important parameter affecting the performance of anion exchange membranes, which has a significant impact on the practical application of fuel cells. Referring to Figure 7 (a), QPPO-QPOSS -3 film was a pure hydroxide ion conductivity than 327% increase QPPO membrane, ion-exchange at ambient temperature due to the surface area of the high density and the group QPOSS 5.12 × 10 ^-2 Scm ^{- The maximum value of 1} was reached and the resistance to hydroxyl ion migration decreased. In addition, as reported in other literatures, the free volume of the composite membrane increases through the mobility of QPPO chains, which increases the conductivity of both composite membranes with temperature in the temperature range of 25 to 80 °C, thus accelerating the diffusion of ionic clusters at high temperatures. can be verified. The QPPO-QPOSS-3 membrane exhibited ^{a conductivity of 8.77 × 10 -2} Scm ^-1 at 80 ° C. As described above, it exhibited excellent water retention ability and it can be confirmed that the distance between functional ammonium groups was reduced. In addition, when the QPOSS concentration exceeds 3% by weight, it is judged that the denser structure of the membrane increases the torsion to weaken the anion transport in the composite membrane.

Referring to FIG. 7(b), the ionic conductivity of the membrane followed the Arrhenius behavior. The activation energy was calculated using the slope of the regression line of ln σ versus 1000/T(° K ⁻¹ ), and the values are summarized in Table 1 above. It was confirmed that the activation energy of the composite membrane was lower than that of the initial QPPO membrane, demonstrating the demand for less energy in the composite membrane due to the contribution of the ionizable groups from the QPOSS nanoparticles, and the well-linear fit obtained from the conduction mechanism It has been shown that this is mainly governed by Grotthuss/hopping of conductive species.

8 is a view showing the hydroxide ions over time at 80 ° C. of QPPO synthesized in Preparation Example 1 and QPPO-QPOSS-1, QPPO-QPOSS-2 and QPPO-QPOSS-3 synthesized in Examples 1 to 3 of the present invention. This is a graph showing the conductivity.

Long-term stability makes electrochemical applications particularly attractive under alkaline conditions due to the well-known degradation pathways of quaternary ammonium groups, including direct nucleophilic substitution, Hofmann elimination, and formation of nitrogen ylide. Another bottleneck for AEM for To investigate the reliability of the prepared composite membrane, the hydroxide conductivity of the membrane aged at 80 °C (1M KOH solution at room temperature) was recorded as a function of time.

Referring to FIG. 8 , it can be seen that all pure water and composite membranes have improved conductivity even after alkali treatment for 200 hours, so that there is no polymer chain cleavage during that period. It is believed that the absorbed potassium hydroxide solution can be well trapped inside the ion channel and the OH ⁻ ions can be better solvated in deionized water and participate in conduction, delaying the decomposition of the quaternary ammonium group. A decrease in conductivity was observed only after 200 h of chemical exposure, but not less than the initial value may indicate good alkali stability of the prepared membrane. Consequently, the improved chemical stability is judged to be due to the steric hindrance provided by QPPO and QPOSS.

As described above, the anion exchange membrane included in the quaternary ammonium PPO and the quaternary ammonium POSS showed application stability up to 230 °C without decomposition of the cation group and the polymer backbone, and QPPO-QPOSS having an IEC value of ^{4.81 meq -1 The -3 membrane exhibited a conductivity of 8.77 × 10 -2} Scm ^-1 at 80 ° C, and showed excellent water retention ability. In addition, even after exposure to alkali for 1200 hours in 1M KOH at room temperature, it showed an initial conductivity of 102% at 80 °C, indicating excellent chemical stability.

Therefore, according to the present invention, an anion exchange membrane comprising quaternary ammonium polyphenylene oxide and quaternary ammonium polyhedral oligomeric silsesquioxane is prepared, and the quaternary ammonium polyhedral oligomeric Due to the steric hindrance of the long chain present in silsesquioxane, it can be applied as an anion exchange membrane fuel cell with excellent ion conductivity and alkali stability.

Claims (11)

Quaternary ammonated polyphenylene oxide (QPPO) having a repeating unit represented by the following formula (1)
[Formula 1]

(In Formula 1, x is a mole fraction (%) in the repeating unit, wherein x is an integer from 1 to 99) and
An anion exchange membrane comprising quaternary ammonium polyhedral oligomeric silsesquioxane (QPOSS) represented by Formula 2 below.
[Formula 2]

(In Chemical Formula 2, R is a compound represented by the following Chemical Formula 2-1)
[Formula 2-1]

delete According to claim 1,
Anion exchange membrane, characterized in that the weight ratio of the QPOSS to the QPPO is 0.1 to 10% by weight. An alkali fuel cell comprising the anion exchange membrane according to claim 1 . (a) dissolving a quaternary ammonium polyphenylene oxide (QPPO) having a repeating unit represented by the following Chemical Formula 3 in a first solvent to obtain a QPPO solution;
(b) mixing polyhedral oligomeric silsesquioxane (POSS) in a second solvent to obtain a POSS solution;
(c) mixing the QPPO solution and the POSS solution;
(d) forming the mixture of step (c) in the form of a film; and
(e) a method for producing an anion exchange membrane comprising the step of immersing the formed membrane in a hydroxide solution and then drying again.
[Formula 3]

Wherein x is a mole fraction (%) in the repeating unit, wherein x is an integer of 1 to 99. 6. The method of claim 5,
The POSS is a method of manufacturing an anion exchange membrane, characterized in that the quaternary ammonium POSS (QPOSS) represented by the following formula (2).
[Formula 2]

R is a compound represented by the following Chemical Formula 2-1.
[Formula 2-1]

6. The method of claim 5,
The first solvent and the second solvent are the same as or different from each other, and each independently N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylformamide, diethylformamide, dimethylacetamide, methanol, ethanol and ether A method for producing an anion exchange membrane, characterized in that it is one or a mixture of two or more selected from among. 6. The method of claim 5,
Step (c) is a method for producing an anion exchange membrane, characterized in that carried out for 0.5 to 24 hours at room temperature. 6. The method of claim 5,
The method for producing an anion exchange membrane, characterized in that the weight ratio of the POSS to QPPO in step (c) is 0.1 to 10% by weight. 6. The method of claim 5,
Step (d) is a method for producing an anion exchange membrane, characterized in that the casting of the mixture of step (c) on a substrate and then drying the cast membrane. 7. The method of claim 6,
The first solvent is N-methyl-2-pyrrolidone,
The second solvent is dimethyl sulfoxide,
Step (c) is carried out at room temperature for 3 to 5 hours,
The weight ratio of the POSS to QPPO in step (c) is 2 to 4% by weight,
Step (d) is performed by casting the mixture of step (c) on a substrate and then drying the cast film,
The drying temperature of the casting film is 50 to 70 ℃,
The drying time of the casting film is carried out for 11 to 13 hours,
The hydroxide solution is 0.8 to 1.2 M potassium hydroxide solution,
The immersion time of step (e) is 22 to 26 hours,
The method for producing an anion exchange membrane, characterized in that the drying time after the immersion in step (e) is 22 to 26 hours.

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