KR20190088212A - Conductive polymer and preparation method of polymer electrolyte membrane using the same - Google Patents

Abstract

The present invention relates to an ion conductive polymer and a method for manufacturing a polymer electrolyte membrane using the same. More specifically, the present invention is to provide the polymer electrolyte membrane having excellent ion conductivity, mechanical properties, and chemical stability by using a cross-linked polymer, and the method for manufacturing the same. According to various embodiments of the present invention, it is possible to manufacture the cross-linked polymer having a spacer-type conductive group introduced into a polyphenylene oxide polymer having no electron attractors, being cheap, and having excellent mechanical strength by using an acylation reaction and a reduction reaction. In addition, the polymer electrolyte membrane manufactured by using the cross-linked polymer exhibits excellent characteristics such as ion conductivity, alkali stability, mechanical strength and the like.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion conductive polymer and a polymer electrolyte membrane using the ion conductive polymer.

The present invention relates to an ion conductive polymer and a method for producing a polymer electrolyte membrane using the same, and more particularly, to provide a polymer electrolyte membrane having excellent ion conductivity, mechanical properties, and chemical stability using a crosslinked polymer and a method for producing the same. .

Problems caused by the emission of greenhouse gases and pollutants such as carbon dioxide, which are caused by the indiscriminate use of fossil fuels, have been a long-standing issue since they have caused global warming and climate change and threatened the survival of mankind. As a result, much research has been conducted on new and renewable energy and environmentally friendly alternative energy sources, and interest in fuel cells including proton exchange membrane fuel cells (PEMFC) among various alternative energy sources is increasing. The cation exchange membrane fuel cell uses a cation exchange membrane having hydrogen ion exchange characteristics as an electrolyte, and is composed of an oxidation electrode and a reduction electrode therebetween.

Theoretically, fuel cells are pollution-free technologies that use oxygen and hydrogen as fuels to generate no pollutants other than water as electrical energy and by-products. Unlike other power generation methods, it has a 60% -80% efficiency as compared with a diesel engine that has 20% energy conversion efficiency as well as a clean energy source that has no pollution such as noise and heat. Despite these advantages, it is difficult to commercialize platinum as expensive noble metal due to electrochemical reasons as well as a low oxygen reduction reaction in an acidic atmosphere which is an operating condition. To solve this problem, anion exchange membrane alkaline fuel cell (AEMAFC) has received much attention in recent years. Unlike cation exchange membrane fuel cell, anion exchange membrane fuel cell operates by using OH ^- as a conduction medium instead of H ⁺ . By operating the fuel cell under high pH conditions, the oxygen reduction reaction is very fast and the cell efficiency is high and the desired activity is obtained even by using a low-cost metal catalyst such as silver or nickel other than platinum, which is advantageous for commercialization in terms of price.

On the other hand, despite these advantages, it is difficult to develop due to its low ionic conductivity and low chemical stability under alkaline conditions compared with cation exchange membrane fuel cells. Particularly, solving the chemical stability is a more urgent problem, and various studies are under way.

Factors affecting the chemical stability of the anion exchange membrane are degradation of the main chain polymer and the conductivity. In the case of the main chain polymer, poly (ether ether ketone) and poly (ether sulfone ketone) in which an electron attracting agent exists are deteriorated by OH ^- (Non-Patent Document 1).

Therefore, in order to prepare a reducing agent having excellent alkali stability, the present invention utilizes Friedel-Crafts acylation and reduction to a poly (2,6-dimethyl-1,4-phenylene oxide) polymer having no electron attracting agent, Spacer-type conductors were introduced without any change in molecular weight, and this exhibited excellent properties such as ionic conductivity, alkali stability and mechanical strength when prepared as an anion exchange membrane.

 Y.-K. Choe, C. Fujimoto, K.-S. Lee, L. T. Dalton, K. Ayers, N.J. Henson, and Y. S. Kim, "Alkaline stability of benzyl trimethyl ammonium functionalized polyaromatics: A computational and experimental study" Chem. Mater., 26, 5675 (2014).

An object of the present invention is to provide a polymer electrolyte membrane having excellent alkali stability which is a problem of conventional polymer electrolyte membranes, and it is an object of the present invention to provide a polyelectrolyte membrane which is free from an electron attracting agent, The present invention provides a crosslinked polymer having a spacer-type conductive agent without any change.

Also, it is an object of the present invention to provide a polymer electrolyte membrane having excellent characteristics such as ionic conductivity, alkali stability and mechanical strength by using the crosslinked polymer as a polymer electrolyte membrane.

According to a representative aspect of the present invention, there is provided an ion conductive polymer represented by the following general formula (1).

[Chemical Formula 1]

(Wherein, in the above formula (1)

R ₁ and R ₂ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₃ and R ₅ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₆ and R ₈ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₉ and R ₁₀ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

,

,

및

중에서 선택되며,R ₄ is - (CH 2) xN ⁺ (A) ₂ -,

,

,

And

Lt; / RTI >

,

,

및

중에서 선택되며,Wherein R < ₇ > is - (CH) xN ⁺ (A) ₃ ,

,

,

And

Lt; / RTI >

Wherein A is - (CH) y,

Where l is a natural number of 56-66, m is a natural number of 8-14, n is a natural number of 26-30, x is a natural number of 1-7, and y is a natural number of 1-3.

According to another exemplary aspect of the present invention, an ion conductive crosslinked polymer is formed by crosslinking the polymer.

It is preferable that the ionically conductive crosslinked polymer has a skeleton represented by the following formula (3).

(3)

(Wherein, in Formula 3,

R ₁ and R ₂ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₃ and R ₅ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₆ and R ₈ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₉ and R ₁₀ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

,

,

및

중에서 선택되며,R ₄ is - (CH 2) xN ⁺ (A) ₂ -,

,

,

And

Lt; / RTI >

,

,

및

중에서 선택되며,Wherein R < ₇ > is - (CH) xN ⁺ (A) ₃ ,

,

,

And

Lt; / RTI >

Wherein R < ₁₁ > is - (CH) x-,

A is - (CH) y,

Where l is a natural number of 56-66, m is a natural number of 8-14, n is a natural number of 26-30, x is a natural number of 1-7, and y is a natural number of 1-3.

According to another exemplary aspect of the present invention, there is provided a polymer electrolyte membrane comprising the ionically conductive crosslinked polymer.

The polymer electrolyte membrane preferably has an ion conductivity of 60 to 70 mS / cm (80 DEG C).

According to another exemplary aspect of the present invention, there is provided a fuel cell including the polymer electrolyte membrane.

According to another exemplary aspect of the present invention, there is provided a method for producing a polyphenylene oxide polymer, comprising: (A) acylating a polyphenylene oxide polymer;

(B) reducing the acylated polymer;

(C) preparing a crosslinked polymer by adding a crosslinking agent to the reduced polymer solution to prepare a crosslinked polymer, and then producing the polymer electrolyte membrane.

The method may further include (D) supporting the membrane prepared in the step (C) in a replacement solution.

Preferably, the replacement solution is selected from trimethylamine, imidazole, morpholine, piperidine, and guanidine.

The crosslinking agent may be selected from the group consisting of N, N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N', N'-Tetramethyl- -1,8-octanediamine, and the like.

In the step (C), the reduced polymer is dissolved in a solvent to prepare a solution,

The solvent is preferably at least one selected from N-methyl-2-pyrrolidone, N, N-dimethylmethanamide, dimethyl sulfoxide and acetonitrile.

The step (C) may include: a primary drying step in which a crosslinking agent is added to the reduced polymer solution and poured into a Patry Dish and dried in a vacuum oven at a temperature of 50 to 70 ° C for 10 to 30 hours; And

And a second drying step in which the drying is performed at a temperature of 70 to 90 DEG C for 1 to 10 hours after the primary drying step.

According to various embodiments of the present invention, a crosslinked polymer having a spacer-type conductive group introduced into a polyphenylene oxide polymer having no electron attracting agent, low cost, and excellent mechanical strength and having no molecular weight change by acylation reaction and reduction reaction Can be manufactured.

In addition, the polymer electrolyte membrane prepared using the crosslinked polymer exhibits excellent properties such as ionic conductivity, alkali stability, and mechanical strength.

1 is an image showing a polymer electrolyte membrane (X11AQ27-PPO) of Example 1 according to an embodiment of the present invention.
Fig. 2 shows the result of measurement of the polymer of the production example by ¹ H NMR spectra, wherein (a) shows Production Example 1 (Ac38-PPO) and (b) shows Production Example 2 (A38-PPO) in CDCl ₃ .
(A38-PPO) in Production Example 1 (Ac38-PPO), (c) in Production Example 2 (A38-PPO) .
4 shows the measurement results of polymers of Production Example 1 (Ac38-PPO), 2 (A38-PPO) by GPC.
5 is an image of the polymer electrolyte membrane (X11AQ27-PPO) AFM of Example 1. Fig.
6 shows the stress-strain curves of the polymer electrolyte membrane (X11AQ27-PPO) of Example 1. Fig.
7 shows FT-IR measurement results obtained by dividing the polymer electrolyte membrane (X11AQ27-PPO) of Example 1 by water (0 h) and after (1000 h) before storage at 80 ° C for 1000 hours .

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

According to an aspect of the present invention, there is provided an ion conductive polymer represented by the following general formula (1).

[Chemical Formula 1]

In Formula 1,

R ₁ and R ₂ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₃ and R ₅ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₆ and R ₈ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₉ and R ₁₀ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

,

,

및

중에서 선택되며,R ₄ is - (CH 2) xN ⁺ (A) ₂ -,

,

,

And

Lt; / RTI >

,

,

및

중에서 선택되며,Wherein R < ₇ > is - (CH) xN ⁺ (A) ₃ ,

,

,

And

Lt; / RTI >

Wherein A is - (CH) y,

Wherein l is a natural number of 56-66, m is a natural number of 8-14, n is a natural number of 26-30, x is a natural number of 1-7, and y is a natural number of 1-3.

The R ₄ or R ₇ may be selected from a transition metal ion such as a phosphonium ion, a sulfonium ion and Mn, Fe, Co, Ni, Cu, and Zn in addition to the nitrogen-based cation described above.

The ion conductive polymer is more preferably represented by the following formula (2).

(2)

(Note that the R ₁ to _{R 3, R 5, R 6} , R 8 to R ₁₀ are as defined in the general formula 1, wherein R ₄ is ^{- (CH) xN + (CH} 3) 2 - , and wherein R ₇ It is ^{- (CH) xN + (CH} 3) 3 a (a natural number of x = 1-7)).

According to another aspect of the present invention, there is provided an ionically conductive crosslinked polymer in which the polymer is formed by crosslinking.

It is preferable that the ionically conductive crosslinked polymer has a skeleton represented by the following formula (3).

(3)

(Wherein, in Formula 3,

R ₁ and R ₂ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₃ and R ₅ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₆ and R ₈ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

R ₉ and R ₁₀ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,

,

,

및

중에서 선택되며,R ₄ is - (CH 2) xN ⁺ (A) ₂ -,

,

,

And

Lt; / RTI >

,

,

및

중에서 선택되며,Wherein R < ₇ > is - (CH) xN ⁺ (A) ₃ ,

,

,

And

Lt; / RTI >

Wherein R < ₁₁ > is - (CH) x-,

A is - (CH) y,

Where l is a natural number of 65-70, m is a natural number of 20-25, n is a natural number of 5-10, x is a natural number of 1-7, and y is a natural number of 1-3.

More preferably, R ₄ is - (CH 2) xN ⁺ (CH ₃ ) ₂ -, and R ₇ is - (CH 2) xN ⁺ (CH ₃ ) ₃ and the ionic conductivity and mechanical properties of the electrolyte membrane are most effective I confirmed it was excellent.

According to another aspect of the present invention, there is provided a process for producing a polyphenylene oxide polymer, comprising: (A) acylating a polyphenylene oxide polymer;

(B) reducing the acylated polymer;

(C) preparing a crosslinked polymer by adding a crosslinking agent to the reduced polymer solution to form a crosslinked polymer, and then producing the polymer electrolyte membrane.

The method may further include (D) supporting the membrane prepared in the step (C) in a replacement solution.

The step (A) is a step of acylating the polyphenylene oxide polymer.

(I) the polyphenylene oxide polymer is dissolved in a solvent at a temperature of 30 to 50 DEG C, and the solution is cooled to room temperature. Thereafter, a precursor for introducing a conductive group is added thereto and dispersed . And stirring is carried out at room temperature for 1 to 5 hours so that sufficient reaction can occur when the dispersion is completed. When the reaction is completed, it is preferable to wash with washing water and then to dry by filtration.

The precursor for introducing the conductive group is preferably at least one selected from AlCl ₃ , 6-bromohexanoyl chloride, 4-bromobutyryl chloride, 5-bromobutyryl chloride, 6-bromobutyryl chloride, 7-bromobytyryl chlorride and 8-bromoctanoyl chloride.

More preferably, when AlCl ₃ and 6-bromohexanoyl chloride are used as AlCl ₃ , the conversion of acylation is 30% or more.

The step (B) is a step of reducing the acylated polymer through the step (A), wherein the acid which is adjacent to the carbonyl group in the polymer is reduced by OH ^- to form a carbanion and the deterioration of the conductivity It is a necessary process because it causes problems to promote.

The acylated polymer is dissolved in a solvent and then charged into a reactor. (Ii) Trifluoroacetic acid and triethylsilane are added thereto, and the temperature of the reactor is elevated to 80 to 120 ° C., and the reaction is carried out for 10 to 30 hours. The solution in which the reaction has been completed is preferably neutralized with a basic solution such as KOH, washed, filtered and dried.

The solvent for dissolving the polymer in the steps (A) and (B) is preferably at least one selected from 1,2-dichloroethane, dichloromethane and chloroform.

(Iii) using AlCl ₃ and 6-bromohexanoyl chloride as precursors for introducing the conductive group, and (iv) using the reaction mixture obtained in step (B) It is most preferable to use trifluoroacetic acid and triethylsilane as the reactants for reduction. If the conditions (i) to (iv) are exceeded, the yield of the polymer sharply decreases to 80% or less.

In the step (C), a cross-linking agent is added to the polymer solution reduced through the step (B), and the cross-linked polymer is synthesized to react as a membrane.

More specifically, a primary drying step in which a crosslinking agent is added to the reduced polymer solution through the step (B), poured into a Patri dish and dried in a vacuum oven at a temperature of 50 to 70 ° C for 10 to 30 hours; And

And a second drying step in which the drying is performed at a temperature of 70 to 90 DEG C for 1 to 10 hours after the primary drying step.

The solvent is preferably at least one selected from N-methyl-2-pyrrolidone, N, N-dimethylmethanamide, dimethyl sulfoxide and acetonitrile.

Wherein the crosslinking agent is selected from the group consisting of N, N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N', N'- And tetramethyl-1,8-octanediamine.

In the step (D), the membrane prepared in the step (C) is supported on a replacement solution to introduce a substituent.

Preferably, the replacement solution is selected from trimethylamine, imidazole, morpholine, piperidine, and guanidine.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope and content of the present invention can not be construed to be limited or limited by the following Examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. It is natural that it belongs to the claims.

In addition, the experimental results presented below only show representative experimental results of the embodiments and the comparative examples, and the respective effects of various embodiments of the present invention which are not explicitly described below will be specifically described in the corresponding part.

reagent

As the main polymer used in this example, 20.5 kg mol ^-1 of Mn, 49.7 kg mol ^{-1 of} Mw, 2 mol of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO, Asahi Kasei, Japan) PDI: 2.42 product was used. 1,2-dichloroethane (DCE,> 99%, Sigma-Aldrich) and N-methyl-2-pyrrolidone (NMP, 99%, Daejung chemical, Korea) were used as solvents. Aluminum chloride (AlCl ₃ , 99.9%, Sigma-Aldrich) and 6-bromohexanoyl chloride (97%, Sigma-Aldrich) were used as reaction compounds for the acylation reaction. Trifluoroacetic acid (TFA,> 99%, TCI), triethylsilane (Et3SiH,> 98%, TCI) was used as a reaction compound for the reduction, and the crosslinking agent was N, N, N`, N`-Tetramethyl- 6-hexanediamine (TMHDA, 99%, Sigma-Aldrich) was used. Methanol (Methanol, Daejung chemical, Korea) was used as a precipitation and washing solvent and trimethylamine solution (TMA, ~ 45 wt% in H ₂ O, Sigma-Aldrich) was used to introduce ammonium into the amination reaction.

How to measure

1. Polymer Analysis

The polymer was analyzed by ¹ H-nuclear magnetic resonance spectroscopy (NMR, 400-MR, Agilent) and Fourier transform infrared spectroscopy (FT-IR, PerkinElmer) Was confirmed by CHCl ₃ Gel permeation chromatography (GPC, Alliance e2695, Waters) calibrated with polystyrene (600-106 g / mol).

2. Water uptake (WU) and swelling ratio (SR)

In order to measure the water content and dimensional stability, a circular separator with a diameter of 2 cm and a thickness of 50 μm substituted with OH- was sufficiently swelled in distilled water at 20 ° C and 80 ° C for 12 hours, respectively. Then, the moisture on the surface of the membrane was removed, and the weight (Wwet), the thickness (twet) and the length (lwet) were measured. The measured membranes were dried in a vacuum oven at 80 ° C and the dried weight (Wdry), thickness (tdry) and length (ldry) were measured. The measured values were substituted into the following equations (1) - (3) Stability was calculated.

Water absorption (WU _W ) (wt%) = [(W _wet - W _dry ) / W _dry ]

(T _wet - t _dry ) / t _dry ] x 100 (2)

Dimensional change (? 1) = [(l _wet - l _dry ) / l _dry ] x 100 (3)

(Where W _wet and W _dry are respectively the weight of the wet film and the weight of the dried film, t _wet and t _dry are respectively the thickness of the wet film and the thickness of the dried film, and l _wet And l _dry are the wet film length and the dried film length, respectively.)

3. Ion exchange capacity (IEC)

Ion exchange capacity (IEC) is an indicator of the amount of conductive material relative to the weight of polymer. The ion exchange capacity was determined by back-titration. In order to measure the ion exchange capacity for the anion exchange membrane, Br ^- anion was replaced with OH ^- group by impregnation with 1 M KOH solution. 20-30 mg of exchange membrane was then neutralized by impregnation with 20 mL of 0.01 M HCl and the residual H ⁺ group was reversed with 0.01 M NaOH solution to calculate the ion exchange capacity. The volume and molarity of the neutralized NaOH solution without the exchange membrane, the volume of the neutralized NaOH solution with VxNaOH and CNaOH exchanged membrane, and the weight of the dried sample, respectively.

4. Mechanical Strength

The mechanical properties of the polymer electrolyte membranes were (1 × 4) cm ² membranes OH ^- treated using a Universal Testing Machine (UTM, EZ-TEST E2-L, Shimadzu) at room temperature and a relative humidity of 50% .

5. Ion conductivity

The ionic conductivity of the anion-exchange membrane was measured by SP-300 electrochemical impedance spectroscope (Bio-Logic Science Instrument, UK). First, the OH ^- treated film was cut into (1 × 4) cm ² and fixed between the Teflon cell electrodes of four platinum electrodes. It was then measured by a 4-probe AC impedance method with a frequency range of 2 MHz to 100 Hz under water conditions and the conductivity was calculated by the following formula. Where L is the distance between the electrodes and R and A are the impedance and area of the membrane, respectively.

6. Atomic Force Microscopy (AFM)

AFM was used to observe morphology of OH ^- treated anion exchange membranes. AFM was performed using a Bruker multimode instrument and non-contact tapping mode with a silcon cantilever (NCH-8, nanosensors, f = 300 kHz) with a radius of 10 nm and a force constant of 40 N / %.

7. Alkali stability

In order to measure the chemical stability of the polymer electrolyte membrane, the OH-substituted anion exchange membrane was impregnated with a glass bottle containing water and stored for 1000 hours in an oven at 80 ° C. The IEC of the membranes before and after storage was measured and the reduced values were expressed as a percentage (%). The structure of each anion-exchange membrane was analyzed using FT-IR.

Manufacturing example  One: PPO  Polymeric acylation anger( Ac38 - PPO )

First, a polymer solution for the acylation reaction was prepared. The polymer solution was prepared by adding 6 g (50 mmol) of PPO polymer and 90 mL of 1,2-dichloroethane solvent to a 2-neck round bottom flask, heating to 40 ° C, dissolving, and cooling to room temperature. Followed by _{AlCl 3 (2.66 g, 20 mmol} ) then gave was evenly dispersed in the polymeric solution 6-bromohexanoyl chloride (4.27 g, 20 mmol) a, then it gave into the reactor in the same equivalent weight with AlCl ₃ 3 hours at room temperature Lt; / RTI > After the reaction was completed, the reaction solution was precipitated in methanol (500 mL) and washed three times. The washed polymer was filtered and dried in a vacuum oven at 80 ° C. The synthesized polymer had a yield of 92% in the form of a white powder and an acylation conversion of 38% (see the following reaction formula).

Manufacturing example  2: Acylation anger PPO  Reduction of polymer (A38- PPO )

The polymer solution was prepared by adding 1,2-dichloroethane (200 mL) to a 2-necked round bottom flask equipped with a reflux condenser and then completely dissolving Ac38-PPO (6 g, mmol) of Preparation Example 1 after the synthesis. To the completely dissolved solution, TFA (150 mL) and Et ₃ SiH (20 g) were added to the reactor and stirred. Thereafter, the temperature was raised to 100 DEG C and the reaction was carried out for 24 hours. After the reaction was completed, the reaction solution was neutralized by slowly adding the solution to 2M KOH aqueous solution and washed for 2 hours. Thereafter, the reaction solution and the KOH aqueous solution were separated using a separating funnel, and the reaction solution layer was precipitated with methanol (500 mL). The same procedure was repeated three times with methanol, followed by drying under a vacuum oven at 80 ° C. The synthesized polymer is in the form of a white powder with a yield of 86% (see the reaction scheme below).

Example  One: PPO  membrane ( X11AQ27 - PPO )

After the synthesis and drying, 400 mg of the A38-PPO polymer of Preparation Example 2 was completely dissolved in NMP to prepare a 3 wt% solution. Twenty milligrams of TMHDA, a crosslinking agent, was added to the completely dissolved solution, and the solution was poured into a petri dish to volatilize the solvent in a vacuum oven at 60 ° C for 24 hours and then dried at 80 ° C for 4 hours to prepare a membrane. The membrane was washed with water for 1 hour to remove residual solvent of the prepared membrane, and then the membrane was dried at room temperature. In order to aminize the dried crosslinked PPO membrane, it was impregnated with 20 wt% TMA solution for 24 hours to replace with ammonium group. The fully substituted crosslinked PPO membrane was washed several times with distilled water and stored (see the reaction scheme below).

[Reaction Scheme]

Experimental Example : Structure and Molecular Weight Analysis of Ion Conducting Crosslinked Polymer and Electrolyte Membrane Using the Crosslinked Polymer

A method of synthesizing crosslinked PPO polymer 5 (X11AQ27-PPO) having a spacer-type conductive group is shown in the above reaction scheme as described above. First, the Friedel-Crafts acyaltion reaction was carried out using 40 mol% of 6-bromohexanoyl chloride and AlCl ₃ as a repeating unit (120 g / mol) as a precursor for introducing a conductive group into polymer 1 (PPO) Polymer 2 (Ac38-PPO) was synthesized. After that, the carbonyl group of the polymer 2 (Ac38-PPO) was excessively reacted with Et ₃ SiH and TFA and then reduced to -CH ₂ - to synthesize Polymer 3 (A38-PPO). This is because the acidic hydrogen next to the carbonyl group forms a carbo-anion by OH- and promotes deterioration of the conductivity. Thus, the polymers of the preparation examples and examples synthesized by the above method were confirmed by ¹ H-NMR, FT-IR and GPC for each reaction step, and the results are shown in FIGS. 2 to 4.

In the polymer (Ac38-PPO) of Production Example 1, the benzene hydrogen peak H ₂ (6.47 ppm) of PPO was moved to H _2a (6.07 ppm) due to the influence of the precursor introduced after acylation, and additionally the alpha hydrogen H ₆ (2.97 ppm) and H ₇ (3.37 ppm) which is hydrogen beside the bromine group were observed. The conversion of the introduced acyl monomer was calculated by the ratio of H ₂ (6.47 ppm) and H _{2 a} (6.07 ppm) or H ₇ (3.37 ppm) and H ₁ (2.07 ppm) (Fig. 2A). Thereafter, analysis was carried out using ¹ H-NMR and FT-IR spectroscopy to confirm the reduction of the carbonyl group of the polymer (A38-PPO) of Production Example 2 which was reduced. First ^one hydrogen peak of H _2a (6.07 ppm) after reduction on H-NMR were all disappear H _2b had a new peak appeared in (6.00 ppm), like lost all H ₆ next to the carbonyl group H ₈ New benzyl . At this time, the integral ratio of the disappearing peak was equal to the integral ratio of the generated peak, and it was considered that all the reduction occurred (FIG. 2B). In addition, FT-IR was measured to confirm the reduction of the carbonyl group. As a result, the C = O mode peak of the carbonyl group was observed at 1700 cm ^-1 after acylation in the spectrum, but not after the reduction (FIG.

In addition, the molecular weights of the polymers were measured at each synthesis step, and the results are shown in the following (1) and (4). After acylation, the molecular weight of the polymer (Ac38-PPO) of Preparation Example 1 increased in both Mn and Mw compared to the PPO polymer, but the increase was about the weight of the monomer and there was no significant change in PDI. Also, Mn and Mw of the polymer (A38-PPO) of Production Example 2 after the reduction were lower than those of the polymer of Production Example 1 (Ac38-PPO) but higher than that of PPO polymer and no change of PDI was observed. As a result, it was confirmed that no additional crosslinking or deterioration of the polymer main chain occurred at each reaction step.

division Mn Mw PDI PPO 22,000 52,000 2.37 Ac38-PPO 31,000 66,000 2.11 A38-PPO 26,000 54,000 2.09

4.2. Crosslinked polymer electrolyte membrane

The crosslinking degree of the prepared polymer electrolyte membrane prepared in Example 1 was assumed to be all of the added crosslinking agent. The amount (20 mg, 116 mmol) of the added crosslinking agent was converted into the number of moles of the total reaction sites (834 mmol) in 400 mg of the polymer (A38-PPO) of Production Example 2 (116/834 × 100% ) X 2 (the cross-linking agent has two reaction sites), and the crosslinking rate is 28%. Gel fraction test and solubility test were conducted to confirm the success of crosslinking. Gel fraction test was carried out by placing a dried polymer electrolyte membrane weighed in NMP solvent for 24 hours at room temperature, measuring the remaining weight after solvent treatment and calculating the weight fraction (%) of the polymer electrolyte membrane. As a result, a gel fraction of 96.2% was obtained and exhibited a high degree of crosslinking such as NMP, DMSO, DMF, DMAc and the like, which were not dissolved in solvents previously dissolved before crosslinking (Table 2 below).

division Gel fraction (%) Solubility DMF DMAc DMSO NMP Example 1 96.2 × × × ×

4.3. Ion Exchange Capacity (IEC)

Ion Exchange Capacity (IEC) is an indicator of the amount of conductors relative to the molecular weight of the polymer, which means that the higher the IEC, the greater the number of conductors introduced into the polymer electrolyte membrane. Theoretical IEC of crosslinked spacer-type Example 1 (X11AQ27-PPO) membrane was calculated from the amount of crosslinker and the conversion rate of acylation, and the theoretical IEC was calculated by the back titration method using NaOH. The theoretical IEC and experimental IEC are 2.03 and 1.86, respectively, and the experimental IEC is lower than the theoretical IEC because the strong electrostatic attraction of OH- and the electrostatic attraction and the neutralization reaction of H + and OH- due to polymer steric hindrance are not completely realized (Table 3).

division Theoretical IEC Experimental IEC OH ^- Conductivity (mS / cm) 20 ℃ 40 ℃ 60 ° C 80 ℃ Example 1 2.03 1.86 + 0.04 32.7 ± 0.3 44.8 ± 0.3 57.2 + 1.7 67.9 ± 1.5

4.4. Moisture content (WU) and dimensional stability (SR)

Since water plays an important role in the conduction of OH ^- in anion exchange membranes, OH ^- conductivity is generally improved as the water content increases. In addition, recent literature suggests that water dissociates OH ^- from electroconductors to reduce the nucleophilicity of OH ^- , thus lowering the deterioration of electrical conductors and main chain polymers. However, in general, the high water content increases the swelling of the film and lowers the mechanical properties of the film, so dimensional stability is also an important factor. The water content and the dimensional stability of the crosslinked anion exchange membrane were measured at 20 and 80 캜, and the results are shown in Table 4. The water content increased by 2 times at 80 ℃ compared to 20 and contained considerably more water. On the other hand, due to the effect of crosslinking, the dimensional stability of thickness and length are lower than those of water content at 20 and 80 ℃.

division Example 1 Water uptake (%) 20 ℃ 42.1 ± 3.3 80 ℃ 81.2 ± 7.0 Swelling ratio (%) 20 < 0 > C (DELTA l) 10.8 ± 1.2 80 DEG C (DELTA l) 25.2 ± 3.3 20 캜 (Δt) 6.3 ± 0.7 80 DEG C (DELTA l) 13.8 ± 1.7

4.5. Morphology and ion conductivity

An AFM image was obtained to analyze the morphology of the X11AQ27-PPO polyelectrolyte membrane of Example 1, and the results are shown in FIG. According to FIG. 5, even though the polymer main chain is not a block-type polymer or copolymer, distinct phase separation and large size ion clusters are observed. By introducing a spacer-type conductivity, flowability of the electroplating increases, Respectively. The results of AFM images with distinct phase separation mean that the polymer electrolyte membrane can have a high ionic conductivity. Based on this, the OH-ion conductivity was measured in water at a temperature range of 20 ° C to 80 ° C, Table 3 shows the results. As a result, it was confirmed that the prepared X11AQ27-PPO film of Example 1 exhibited a high conductivity of 32.7 mS cm ^-1 at 20 ° C and 67.9 mS cm ^-1 at 80 ° C, even though the crosslinking ratio was 28%.

4.6. Mechanical Stability and Alkali Stability

In order to operate an anion exchange membrane fuel cell for a long time, a strong mechanical strength and chemical stability of the membrane are required. The mechanical properties of the prepared polymer electrolyte membranes were measured at a room temperature relative humidity of 50%, and the values were suitable for driving a fuel cell having a tensile strength of 16.4 MPa, a tensile strength of 36% and a Young's modulus of 0.53 GPa (FIG. 6). These results are due to the increase of the interchain interactions of the polymer due to crosslinking of the polymer. In order to confirm the long-term stability of the crosslinked polymer electrolyte membrane, OH ^- treated membranes were stored in water at 80 ° C. for 1000 hours. Structural changes were confirmed by IEC measurement and IR after storage, and the results are shown in FIG. 7 .

This is because the condition under which the fuel cell is actually driven is not a KOH solution but a relative humidity of 60 ° C and 95%. Compared with the IEC measured before storage, the reduction rate was calculated to be 6.8% after 1000 hours, but no change was observed in FT-IR. This means that there is no significant influence on the polymer backbone or the conductive phase of the polymer electrolyte membrane during storage, and it is estimated to be within the error range in IEC. Based on these results, it was confirmed that the polymer electrolyte membrane manufactured is suitable for long-term operation of the fuel cell.

Therefore, according to the present invention, a PPO polymer having a spacer of spacertype was synthesized using acylation and reduction. The structure and conversion of the synthesized polymer were confirmed by ¹ H NMR and FT-IR. The high molecular weight of each synthesis step was confirmed by GPC. The anion exchange membrane with high chemical stability was prepared by cross-linking the synthesized polymer with N, N, N ', N'-tetramethyl-1,6-hexanediamine and introducing ammonium protector into TMA. The X11AQ27-PPO polyelectrolyte membrane prepared in Example 1 was not dissolved in organic solvents such as DMSO, NMP, and DMF, and showed a gel fraction of 96.2%, indicating that the crosslinking was successful. And the Young's modulus was 0.53 GPa. In addition, it has been confirmed through AFM image that it has excellent chemical stability such as excellent phase separation and high conductivity of 67.9 mS cm ^-1 at 80 ° C water and no change at 80 ° C water temperature for 1000 hours.

Claims (12)

An ion conductive polymer represented by the following general formula (1)
[Chemical Formula 1]

In Formula 1,
R ₁ and R ₂ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₃ and R ₅ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₆ and R ₈ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₉ and R ₁₀ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₄ is - (CH 2) xN ⁺ (A) ₂ -,

,

,

And

Lt; / RTI >
Wherein R < ₇ > is - (CH) xN ⁺ (A) ₃ ,

,

,

And

Lt; / RTI >
Wherein A is - (CH) y,
Where l is a natural number of 56-66, m is a natural number of 8-14, n is a natural number of 26-30, x is a natural number of 1-7, and y is a natural number of 1-3.
The ionically conductive crosslinked polymer according to claim 1, wherein the polymer is formed by crosslinking.
3. The method of claim 2,
Wherein the ionically conductive crosslinked polymer has a skeleton represented by the following formula (3): < EMI ID =
(3)

In Formula 3,
R ₁ and R ₂ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₃ and R ₅ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₆ and R ₈ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₉ and R ₁₀ are the same as each other and are hydrogen or a C ₁ -C ₅ alkyl group,
R ₄ is - (CH 2) xN ⁺ (A) ₂ -,

,

,

And

Lt; / RTI >
Wherein R < ₇ > is - (CH) xN ⁺ (A) ₃ ,

,

,

And

Lt; / RTI >
Wherein R < ₁₁ > is - (CH) x-,
A is - (CH) y,
Where l is a natural number of 56-66, m is a natural number of 8-14, n is a natural number of 26-30, x is a natural number of 1-7, and y is a natural number of 1-3.
A polymer electrolyte membrane comprising the ionically conductive crosslinked polymer according to claim 2.
5. The method of claim 4,
Wherein the polymer electrolyte membrane has an ion conductivity of 60 to 70 mS / cm (80 캜).
A fuel cell comprising the polymer electrolyte membrane according to claim 4 or 5.
(A) acylating a polyphenylene oxide polymer;
(B) reducing the acylated polymer;
(C) preparing a crosslinked polymer by adding a crosslinking agent to the reduced polymer solution to form a crosslinked polymer.
8. The method of claim 7,
The method may further include (D) supporting the membrane prepared in the step (C) in a replacement solution.
9. The method of claim 8,
Wherein the replacement solution is selected from the group consisting of trimethylamine, imidazole, morpholine, piperidine, and guanidine.
8. The method of claim 7,
The crosslinking agent may be selected from the group consisting of N, N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N', N'-Tetramethyl- -1,8-octanediamine. ≪ RTI ID = 0.0 > 11. < / RTI >
8. The method of claim 7,
In the step (C), the reduced polymer is dissolved in a solvent to prepare a solution,
Wherein the solvent is at least one selected from the group consisting of N-methyl-2-pyrrolidone, N, N-dimethylmethanamide, dimethyl sulfoxide and acetonitrile.
8. The method of claim 7,
The step (C) may include: a primary drying step in which a crosslinking agent is added to the reduced polymer solution and poured into a Patry Dish and dried in a vacuum oven at a temperature of 50 to 70 ° C for 10 to 30 hours; And
And a second drying step of drying the polymer electrolyte membrane at a temperature of 70 to 90 DEG C for 1 to 10 hours after the primary drying step.

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