KR101697693B1 - Porous support and polymer electrolyte membrane for fuel cell including the same - Google Patents

Abstract

There is provided a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide. The porous support has fine pores and picopores existing in the polymer derived from the polyamic acid or in a polymer derived from the polyimide, wherein the polyamic acid and the polyimide have an orthosilicate And a repeating unit prepared from an aromatic diamine and a dianhydride containing at least one functional group present in the repeating unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a porous support and a polymer electrolyte membrane for a fuel cell including the porous support,

The present invention relates to a porous support and a polymer electrolyte membrane for a fuel cell comprising the porous support.

A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in a hydrocarbon-based material such as methanol, ethanol, and natural gas into electrical energy. Such a fuel cell is attracting attention as a clean energy source that can replace fossil energy.

Representative examples of the fuel cell include a polymer electrolyte membrane fuel cell (PEMFC) and a direct oxidation fuel cell. When methanol is used as the fuel in the direct oxidation fuel cell, it is referred to as a direct methanol fuel cell (DMFC).

In such a fuel cell system, the stack which substantially generates electricity has a structure in which several to several tens of unit cells each consisting of a membrane-electrode assembly (MEA) and a separator are stacked. The membrane-electrode assembly has a structure in which an anode and a cathode are opposed to each other with a polymer electrolyte membrane including a cation exchange resin having hydrogen ion conductivity interposed therebetween.

The principle of generating electricity in the fuel cell is that the fuel is supplied to the anode, which is the anode, and adsorbed to the anode catalyst, and the fuel is ionized by the oxidation reaction to generate electrons. And the hydrogen ions pass through the polymer electrolyte membrane and are transferred to the cathode. An oxidant is supplied to the cathode, and the oxidant, hydrogen ions, and electrons react with each other on the cathode catalyst to generate electricity while generating water.

At present, researches for improving hydrogen ion conductivity, mechanical properties, dimensional stability and chemical resistance of the polymer electrolyte membrane have been actively carried out.

A polymer electrolyte membrane for a fuel cell, comprising: a porous support having excellent mechanical properties, dimensional stability, and chemical resistance; and a porous support including the porous support and having excellent hydrogen ion conductivity, mechanical properties, dimensional stability and chemical resistance, And a method for producing the porous support and the polymer electrolyte membrane for a fuel cell.

The present invention provides a membrane-electrode assembly including the porous support and the polymer electrolyte membrane for a fuel cell, and provides a fuel cell system including the membrane-electrode assembly.

According to one aspect of the invention, the porous support comprises a polymer derived from polyamic acid or a polymer derived from polyimide. The porous support has fine pores and picopores existing in the polymer derived from the polyamic acid or in a polymer derived from the polyimide, wherein the polyamic acid and the polyimide have an orthosilicate And a repeating unit prepared from an aromatic diamine and a dianhydride containing at least one functional group present in the repeating unit.

The functional groups may include OH, SH or NH ₂ .

(100 mol%) of the repeating units contained in the polyamic acid or the polyimide, the ratio of the repeating units to be thermally converted (thermoelectric conversion rate ) Can be from about 10 mole% to about 100 mole%.

The polymer derived from the polyamic acid and the polymer derived from the polyimide may have a free volume degree (FFV) of about 0.18 to about 0.40.

Also, the polymer derived from the polyamic acid and the polymer derived from the polyimide may have an interplanar distance by XRD measurement of about 550 pm to about 800 pm.

Two or more of the picopores may be connected to each other to form an hourglass shape.

Also, the picopores may have a full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) ranging from about 10 pm to about 40 pm.

The porous support may have a porosity of about 10% by volume to about 95% by volume based on the total volume of the support. The porous support may also be formed to a thickness of about 10 [mu] m to about 200 [mu] m.

The polyamic acid may be selected from the group consisting of polyamic acid containing repeating units represented by the following Chemical Formulas 1 to 4, polyamic acid copolymer containing repeating units represented by Chemical Formulas 5 to 8, copolymers thereof, and blends thereof And the polyimide may be selected from the group consisting of a polyimide including the repeating units represented by the following formulas (19) to (22), a polyimide copolymer including the repeating units represented by the following formulas (23) to ≪ / RTI > blend.

[Chemical Formula 1]

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Chemical Formula 22]

(23)

≪ EMI ID =

(25)

(26)

In the above Chemical Formulas 1 to 8 and Chemical Formulas 19 to 26,

Ar ₁ is an aromatic ring group selected from a substituted or unsubstituted quadrivalent C6 to C24 arylene group and a substituted or unsubstituted quadrivalent C4 to C24 heterocyclic group, and the aromatic ring group is present alone; Two or more are bonded to each other to form a condensed ring; Two or more single bond, O, S, C (= O), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10) , (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, and connected by a C (CF _{3) 2} or C (= O) NH functional group,

Ar ₂ is an aromatic ring group selected from a substituted or unsubstituted divalent C6 to C24 arylene group and a substituted or unsubstituted divalent C4 to C24 heterocyclic group, and the aromatic ring group is present alone; Two or more are bonded to each other to form a condensed ring; Two or more single bond, O, S, C (= O), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10) , (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, and connected by a C (CF _{3) 2} or C (= O) NH functional group,

Q is O, S, C (= O ), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10), (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, C (CF 3) 2, C (= O) NH, C (CH 3) (CF 3), or a substituted or unsubstituted phenylene group (Wherein the substituted phenylene group is substituted with a C1 to C6 alkyl group or a C1 to C6 haloalkyl group), wherein Q is connected to both aromatic rings at the positions of mm, mp, pm, or pp,

Y is the same or different from each other in each repeating unit, and is independently OH, SH or NH ₂ ,

n is an integer satisfying 20? n? 200,

m is an integer satisfying 10? m? 400,

l is an integer satisfying 10?

The mole ratio of each repeating unit in the copolymer of the polyamic acid containing the repeating units represented by the above formulas 1 to 4, the molar ratio of m: 1 in the above formulas 5 to 8, and the repeating units represented by the above formulas 19 to 22 The molar ratio between the respective repeating units in the copolymer of the polyimide or the molar ratio of m: 1 in the above formulas 23 to 26 may be about 0.1: 9.9 to about 9.9: 0.1.

The polymer derived from the polyamic acid and the polymer derived from the polyimide may include a polymer containing a repeating unit represented by any one of the following formulas (37) to (50), or a copolymer thereof.

(37)

(38)

[Chemical Formula 39]

(40)

(41)

(42)

(43)

(44)

[Chemical Formula 45]

(46)

(47)

(48)

(49)

(50)

In the above formulas 37 to 50,

_{Ar 1, Ar 2, Q,} n, m and l are the same as described in each of the above Chemical Formulas 1 to 8 and Chemical Formulas 19 to 26, _{Ar 1, Ar 2, Q,} n, m and l,

Ar ₁ 'is an aromatic ring group selected from a substituted or unsubstituted divalent C6 to C24 arylene group and a substituted or unsubstituted divalent C4 to C24 heterocyclic group, and the aromatic ring group is present alone; Two or more are bonded to each other to form a condensed ring; Two or more single bond, O, S, C (= O), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10) , (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, and connected by a C (CF _{3) 2} or C (= O) NH functional group,

Y " is O or S;

In Formulas 1 to 8, Formulas 19 to 26 and Formulas 37 to 50, examples of Ar ₁ may be selected from those represented by the following formulas.

In this formula,

X _1, X _2, X ₃ and X ₄ are in the same or different, each independently O, S, C (= O ), CH (OH), S (= O) 2, Si (CH 3) 2, ( CH _{2) p (where, 1≤p≤10), (CF 2)} q ( _{where, 1≤q≤10), C (CH 3} ) 2, C (CF 3) 2, or C (= O) NH ego,

W ₁ and W ₂ are the same or different and each independently O, S, or C (= O)

Z ₁ is O, S, CR ₁₀₀ R ₁₀₁ or NR ₁₀₂ wherein R ₁₀₀ , R ₁₀₁ and R ₁₀₂ are the same or different and each independently hydrogen or a C 1 to C 5 alkyl group,

Z ₂ and Z ₃ are the same or the different and each is independently N or CR ₁₀₃ to each other (wherein, R ₁₀₃ is hydrogen or C1 to C5 alkyl group) or CR ₁₀₃ at the same time is not,

R ₁ to R ₄₂ are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C10 aliphatic organic group,

k1 to k3, k8 to k14, k24 and k25 are integers of 0 to 2,

k5, k15, k16, k19, k21 and k23 are integers of 0 or 1,

k32, k26, k29, k31, k34 to k36, k38, k39 and k42 are integers of 0 to 3, and k4, k6, k7, k17, k18, k20,

k30, k37, k40 and k41 are integers from 0 to 4,

and k32 and k33 are integers of 0 to 5.

In Formulas 1 to 8, Formulas 19 to 26 and Formulas 37 to 50, specific examples of Ar ₁ may be selected from those represented by the following formulas.

In the above Chemical Formulas 1 to 8 and Chemical Formulas 19 to 32, examples of Ar ₂ may be selected from those represented by the following formulas.

In this formula,

X _1, X _2, X ₃ and X ₄ are in the same or different, each independently O, S, C (= O ), CH (OH), S (= O) 2, Si (CH 3) 2, ( CH _{2) p (where, 1≤p≤10), (CF 2)} q ( _{where, 1≤q≤10), C (CH 3} ) 2, C (CF 3) 2, or C (= O) NH ego,

W ₁ and W ₂ are the same or different and each independently O, S, or C (= O)

Z ₁ is O, S, CR ₁₀₀ R ₁₀₁ or NR ₁₀₂ wherein R ₁₀₀ , R ₁₀₁ and R ₁₀₂ are the same or different and each independently hydrogen or a C 1 to C 5 alkyl group,

Z ₂ and Z ₃ are the same or the different and each is independently N or CR ₁₀₃ to each other (wherein, R ₁₀₃ is hydrogen or C1 to C5 alkyl group) or CR ₁₀₃ at the same time is not,

R ₄₃ to R ₈₉ are the same or different and are each independently hydrogen, a substituted or unsubstituted C1 to C10 aliphatic organic group, or a metal sulfonate group,

k43, k49, k64 to k68, k72 to k76, and k82 to k89 are integers of 0 to 4,

k44 to k46, k48, k51, k54, k55, k57, k58, k61 and k63 are integers of 0 to 3,

k57, k56, k59, k60, k62, k70, k78, k80 and k81 are integers of 0 to 2,

k50 is an integer of 0 or 1,

k69, k71, k77, and k79 are integers from 0 to 5.

In Formulas 1 to 8, Formulas 19 to 26 and Formulas 37 to 50, specific examples of Ar ₂ may be selected from those represented by the following formulas.

Wherein M is a metal and the metal may be sodium, potassium, lithium, an alloy thereof, or a combination thereof.

Examples of Q in Formulas 1 to 8, 19 to 26 and 37 to 50 are C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O, S, S (= O) ₂ or C ). ≪ / RTI >

Examples and specific examples of Ar ₁ 'in the above-mentioned formulas (37) to (50) are the same as those mentioned in the examples and specific examples of Ar _{2 in} the above formulas (1) to (8), (19) to (26)

In the above Chemical Formulas 1 to 8 and Chemical Formulas 19 to 26, Ar ₁ may be a functional group represented by any one of the following formulas A1 to A8, Ar ₂ may be a functional group represented by any one of the following formulas B1 to B11, C (CF ₃₎ may be _two days.

[Formula A1] [Formula A2] [Formula A3]

[Chemical Formula A4] [Chemical Formula A5] [Chemical Formula A6]

                  [Chemical formula A7] [Chemical formula A8]

[Formula B1] [Formula B2] [Formula B3]

[Chemical formula B4] [Chemical formula B5] [Chemical formula B6] [Chemical formula B7]

[Chemical formula B8] [Chemical formula B9]

(B11)

In the general formula 37 to 50, Ar ₁ may be a functional group represented by any of the general formula A1 to A8, Ar ₁ 'is to may be a functional group represented by any one of formulas C1 to C8, Ar ₂ has the formula B1 to B11 and of the number of functional group represented by any one, Q may be C (CF _{3) 2.}

≪ RTI ID = 0.0 > (C3) < / RTI &

[Formula C4] [Formula C5] Formula [C6]

(C8) < RTI ID = 0.0 > (C8)

The porous support may include fibers including the polymer having the picopores, and the fibers may be randomly arranged.

Meanwhile, the porous support includes fibers including the polymer having picopores, and the fibers may be arranged in one direction.

According to another aspect of the present invention, the porous support; And a cation exchange resin formed on the inside, the surface, or the inside and the surface of the porous support.

The cation exchange resin may be a polymer including a cation exchanger selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof.

In the polymer electrolyte membrane for a fuel cell, the porous support and the cation exchange resin may be contained in a weight ratio of about 99: 1 to about 10: 90.

According to another aspect of the present invention, there is provided a polyelectrolyte membrane for a fuel cell comprising the porous support, wherein the porous support is formed by doping the inside, the surface, or the inside and the surface of the porous support.

The doped acid may be selected from the group consisting of sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid, and derivatives thereof.

According to another aspect of the present invention, there is provided a polymer electrolyte membrane for a fuel cell comprising a porous support and comprising a fluorine group on the surface of the porous support.

The polymer electrolyte membrane for fuel cells may be formed to a thickness of about 20 탆 to about 300 탆.

According to another aspect of the present invention, there is provided a polyamic acid or polyimide having a repeating unit prepared from an aromatic diamine and dianhydride containing at least one functional group existing at ortho position with respect to an amine group; And a composition for forming a porous support comprising an organic solvent. The organic solvent may include dimethylsulfoxide; N-methyl-2-pyrrolidone; N-methylpyrrolidone; N, N-dimethylformamide; N, N-dimethylacetamide; ketones selected from the group consisting of? -butyrolactone, cyclohexanone, 3-hexanone, 3-heptanone and 3-octanone; And combinations thereof.

The composition for forming a porous support contains about 1 wt% to about 40 wt% of the polyamic acid or the polyimide and about 60 wt% to about 99 wt% of the organic solvent, based on the total amount of the composition for forming a porous support can do.

The composition for forming a porous support may be water; Alcohols selected from the group consisting of methanol, ethanol, 2-methyl-1-butanol, 2-methyl-2-butanol, glycerol, ethylene glycol, diethylene glycol and propylene glycol; Ketones selected from the group consisting of acetone and methyl ethyl ketone; A polymer compound selected from the group consisting of polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyethylene glycol, polypropylene glycol, chitosan, chitin, dextran and polyvinylpyrrolidone; Tetrahydrofuran; Trichloroethane; And combinations thereof. ≪ Desc / Clms Page number 7 > In this case, the composition for forming a porous support may contain about 1% by weight to about 40% by weight of the polyamic acid or the polyimide, about 10% by weight to about 10% by weight, based on the total amount of the composition for forming a porous support, About 95% by weight, and about 4% to about 70% by weight of the adjuvant.

The polyamic acid and the polyimide may each have a weight average molecular weight (Mw) of from about 10,000 g / mol to about 500,000 g / mol.

The composition for forming a porous support may have a viscosity of about 0.01 Pa · s to about 100 Pa · s.

According to another aspect of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; And heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide.

According to another aspect of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; Heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide; And forming a cation exchange resin on the inside, the surface, or the inside and the surface of the porous support, as well as a method for manufacturing a polymer electrolyte membrane for a fuel cell.

According to another aspect of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; Heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide; And a step of doping the inside, the surface, or the inside and the surface of the porous support with an acid. The present invention also provides a method for manufacturing a polymer electrolyte membrane for a fuel cell.

The acid may be selected from the group consisting of sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid, and derivatives thereof.

According to another aspect of the present invention, there is provided a method of preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; Heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide; And introducing a fluorine group to the surface of the porous support. The present invention also provides a method for manufacturing a polymer electrolyte membrane for a fuel cell.

The electrospinning may be performed by applying a voltage of about 1 kV to about 1,000 kV.

The nonwoven fabric formed by the electrospinning may have fibers randomly arranged including a composition for forming a porous support.

On the other hand, the nonwoven fabric formed by the electrospinning may have the fibers including the composition for forming a porous support arranged in one direction.

(100 mol%) of the repeating units contained in the polyamic acid or the polyimide, the ratio of the repeating units to be thermally converted (thermoelectric conversion rate ) Can be from about 10 mole% to about 100 mole%.

The heat treatment may be conducted at a temperature of about 250 ° C to about 550 ° C, and may be conducted for about 10 minutes to about 5 hours. Also, the rate of temperature rise during the heat treatment may be from about 1 占 폚 / min to about 20 占 폚 / min.

According to another aspect of the present invention, there is provided a plasma display panel comprising: an anode and a cathode disposed opposite to each other; And a polymer electrolyte membrane for a fuel cell, the membrane-electrode assembly being disposed between the anode and the cathode.

According to another aspect of the present invention, there is provided a fuel cell system including: an electricity generating unit including at least one of the membrane-electrode assembly and the separator and generating electricity through an electrochemical reaction between a fuel and an oxidant; A fuel supply unit for supplying fuel to the electricity generation unit; And an oxidant supplier for supplying the oxidant to the electricity generator.

Other aspects of the present invention are included in the following detailed description.

The porous support is excellent in mechanical properties, dimensional stability, and chemical resistance. The polymer electrolyte membrane for a fuel cell has excellent hydrogen ion conductivity, mechanical properties, dimensional stability, and chemical resistance, Can be improved.

1 is a schematic view of a membrane-electrode assembly for a fuel cell according to an embodiment of the present invention.
2 is a schematic view showing the structure of a fuel cell system according to another embodiment of the present invention.
3 is a photograph of the porous support prepared in Example 4. Fig.
4 is a photograph of the polymer electrolyte membrane for fuel cells manufactured in Example 4. Fig.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

In the drawings, the thickness is enlarged in order to clearly represent layers and regions. Like reference numerals are used to designate like parts throughout the specification.

&Quot; Pico pore "means a pore having an average diameter of several hundred picometers, specifically, about 100 pm to about 1,000 pm, unless otherwise defined herein, and" Refers to pores having a diameter of from about 2 nm to about 50 μm, specifically, from about 10 nm to about 10 μm.

Unless defined otherwise herein, "substituted" or "substituted" means that the hydrogen or the hydrogen in the compound or functional group is comprised of a C1 to C10 alkyl group, a C1 to C10 alkoxy group, a C1 to C10 haloalkyl group, and a C1 to C10 haloalkoxy group Quot; heterocyclic group "means a heteroatom selected from the group consisting of O, S, N, P, Si, and combinations thereof, in which one to three A substituted or unsubstituted C2 to C30 cycloalkyl group, a substituted or unsubstituted C2 to C30 cycloalkenyl group, a substituted or unsubstituted C2 to C30 cycloalkynyl group, a substituted or unsubstituted C2 to C30 hetero An aryl group, a substituted or unsubstituted C2 to C30 cycloalkylene group, a substituted or unsubstituted C2 to C30 cycloalkenylene group, a substituted or unsubstituted C2 to C30 cyclo Kinil means group, or a substituted or unsubstituted C2 to C30 heteroarylene group ring.

Unless defined otherwise herein, the term "aliphatic organic group" means a C1 to C30 alkyl group, a C2 to C30 alkenyl group, or a C2 to C30 alkynyl group, specifically a C1 to C15 alkyl group, a C2 to C15 alkenyl group, More preferably a C1 to C10 alkyl group, a C2 to C10 alkenyl group, or a C2 to C10 alkynyl group.

As used herein, unless otherwise defined, "combination" means mixing or copolymerization. "Copolymerization" means block copolymerization or random copolymerization, and "copolymer" means block copolymer or random copolymer.

1 is a schematic view of a membrane-electrode assembly for a fuel cell according to an embodiment of the present invention.

Referring to FIG. 1, a fuel cell membrane-electrode assembly 20 includes an anode 22, a polymer electrolyte membrane 24, and a cathode 26.

The anode 22 and the cathode 26 include an electrode substrate and a catalyst layer formed on the electrode substrate.

By the presence of the catalyst layer, the oxidation reaction of the fuel can be promoted at the anode, and the reaction of the oxidant, the hydrogen ion and the electron supplied to the cathode at the cathode can be promoted, and the efficiency of the fuel cell can be improved.

Examples of the catalyst included in the catalyst layer include platinum, ruthenium, osmium, a platinum-ruthenium alloy, a platinum-osmium alloy, a platinum-palladium alloy, a platinum-M alloy wherein M is gallium (Ga), titanium (Ti) (V), Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Mo, (W), rhodium (Rh), ruthenium (Ru), and combinations thereof, and combinations thereof, but are not limited thereto. More specific examples of the catalyst include Pt, Ru, Pt / W, Pt / Ni, Pt / Sn, Pt / Mo, Pt / Pd, Pt / Fe, Pt / , At least one selected from the group consisting of Pt / Ru / Mo, Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni and Pt / Ru / Sn / W.

The catalyst may be used as a catalyst itself or may be supported on a carrier. The carrier may be a carbonaceous material such as graphite, denka black, ketjen black, acetylene black, carbon nanotubes, carbon nanofibers, carbon nanowires, carbon nanoballs or activated carbon, or may be alumina, silica, zirconia, Inorganic fine particles such as titania may be used, but the present invention is not limited thereto.

The polymer electrolyte membrane 24 for a fuel cell is positioned between the anode 22 and the cathode 26 and includes a porous support 244 and a cation exchange resin 244 disposed on the inside, 242). The cation exchange resin 242 may be one having cation conductivity, for example, hydrogen ion conductivity.

The polymer electrolyte membrane 24 functions as an insulator for electrically separating the anode 22 and the cathode 26 or as an agent for transferring hydrogen ions from the anode 22 to the cathode 26 during the operation of the battery, Gas or liquid.

Since the polymer electrolyte membrane 24 includes the porous support 244, the anode 22 and the cathode 26 can be electrically separated from each other, and the polymer electrolyte membrane 24 can have excellent mechanical properties and dimensional stability. Whereby the membrane-electrode assembly comprising the same can facilitate stacking.

The porous support 244 comprises a polymer derived from polyamic acid or a polymer derived from polyimide. The polyamic acid, the polyimide and the polymer derived therefrom will be described later. The porous support 244 has fine pores and picopores existing in the polymer derived from the polyamic acid or picopores present in the polymer derived from the polyimide. The polyamic acid and the polyimide have a And repeating units prepared from an aromatic diamine and dianhydride containing at least one functional group present in ortho position. This allows the porous support 244 to have a high porosity to efficiently contain the cation exchange resin within the pores, thereby allowing positive ions, such as hydrogen ions, to be easily transferred from the anode 22 to the cathode 26, The efficiency of the battery can be improved. In particular, when the cation exchange resin is adsorbed to the picopores of the porous support 244 or the acid is doped, the adsorbed cation exchange resin and the doped acid are not separated from the porous support well. As a result, positive ions such as hydrogen ions can be more stably transferred from the anode 22 to the cathode 26, thereby improving the efficiency and lifetime characteristics of the fuel cell.

The functional group present at the ortho position with respect to the amine group may include OH, SH or NH ₂ .

The polyamic acid and the polyimide can be prepared by a general method.

For example, the polyamic acid may be prepared by reacting an aromatic diamine containing an OH, SH, or NH2 group at an ortho position with respect to an amine group, and a tetracarboxylic acid anhydride. The polyimide may be prepared by imidizing the polyamic acid , For example, by thermal solution imidization or chemical imidization.

For example, the thermal solution imidization may be carried out by adding an organic solvent such as benzene, toluene, xylene, cresol or the like, an aliphatic organic solvent such as hexane or cyclohexane to the organic solvent such as N-methylpyrrolidone (NMP) And the like.

The polyamic acid and the polyimide are thermally converted by a predetermined heat treatment to be converted into a polymer such as polybenzoxazole, polybenzothiazole, or polypyrrolone having picopores and excellent mechanical strength and high free volume .

Specifically, the ratio (thermoelectric conversion rate) of the repeating units to be thermally converted with respect to the total amount of the repeating units contained in the polyamic acid or the polyimide may be about 10 mol% to about 100 mol%. In this case, the heat resistance and the mechanical strength of the porous support can be effectively improved, and the wettability with respect to the cation exchange resin is improved, so that the compatibility between the porous support and the cation exchange resin can be effectively improved. In addition, delamination between the porous support and the cation exchange resin can be prevented, and the durability of the polymer electrolyte membrane for a fuel cell including the porous support can be effectively improved. Specifically, the ratio of the repeating units to be thermally converted (thermoelectric conversion rate) relative to the total amount of the repeating units contained in the polyamic acid or the polyimide may be about 40 mol% to about 100 mol%.

The polymer derived from the polyamic acid and the polymer derived from the polyimide may have a free volume degree (FFV) of about 0.18 to about 0.40 and a d-spacing by XRD measurement of about 550 pm to about 800 < / RTI > As a result, the polymer derived from the polyamic acid and the polymer derived from the polyimide can easily transmit or separate low molecular weight molecules.

The polymer derived from the polyamic acid and the polymer derived from the polyimide include picopores, and two or more of the picopores may be connected to form an hourglass shape. As a result, the polymer has a high porosity, so that the low molecular weight can be efficiently transmitted or selectively separated.

Also, the average diameter of the picopores may be from about 600 pm to about 800 pm, but is not limited thereto. The picopores may have a full width at half maximum (FWHM) of from about 10 pm to about 40 pm as measured by positron annihilation lifetime spectroscopy (PALS). This indicates that the size of the generated picopores is fairly uniform. The PALS data show that the time difference τ ₁ , τ ₂ , τ ₃ between γ _{0 of} 1.27 MeV generated at the time of generation and positron generated from the 22Na isotope and γ ₁ and γ ₂ of 0.511 MeV generated at the time of extinction . ≪ / RTI >

The porous support 244 may include micropores and picopores as a whole to thereby have a porosity of from about 10% to about 95% by volume based on the total volume of the support, wherein the pores include a cation exchange resin It is possible to effectively improve the efficiency of the fuel cell by improving the cation conductivity, for example, the hydrogen ion conductivity.

The porous support 244 may be formed by electrospinning so that the fibers including the polymer having the picopores are randomly arranged in the porous support 244 by adjusting the electrospinning process or the process conditions. .

Meanwhile, when the porous support 244 is formed, the fibers including the polymer having the picopores may be formed in one direction in the porous support 244 by adjusting the method of electrospinning or the process conditions have. In this case, the strength in the direction in which the fibers are arranged can be effectively improved. Also, in the polymer electrolyte membrane for a fuel cell including the porous support 244, the hydrogen ions can be rapidly transferred along the direction in which the fibers are arranged, and the hydrogen ion conductivity can be effectively improved.

The porous support 244 may be formed to have a thickness of about 10 [mu] m to about 200 [mu] m. When the thickness of the porous support 244 is within the above range, the mechanical properties, chemical resistance and dimensional stability of the polymer electrolyte membrane 24 including the porous support 24 can be improved. Specifically, the porous support 244 may be formed to have a thickness of about 20 μm to about 180 μm.

Further, the polymer electrolyte membrane 24 for a fuel cell includes the cation exchange resin 242, thereby improving the cation conductivity, for example, the hydrogen ion conductivity and suppressing the crossover of the fuel.

The cation exchange resin 242 is present on the inside, on the surface, or inside and on the surface of the porous support 244. If the cation exchange resin is present in the interior of the porous support, it may be present in the micropores and picopores of the porous support.

Thereby, it is possible to provide the polymer electrolyte membrane 24 for a fuel cell which is excellent in mechanical strength and dimensional stability, and at the same time, has excellent cation conductivity, for example, hydrogen ion conductivity.

The cation exchange resin can improve the cation conductivity (e.g., proton conductivity) of the polymer electrolyte membrane 24 for a fuel cell and improve the efficiency of the fuel cell.

The cation exchange resin is a polymer comprising a cation-exchange group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof, and examples thereof include fluorine-based polymers, benzimidazole-based polymers, polyimide Based polymer, polyetherimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, polysulfone-based polymer, polyether sulfone-based polymer, polyether ketone-based polymer, polyether-ether ketone-based polymer, polyphenylquinoxaline- Combinations thereof, but are not limited thereto.

The cation exchange resin may include a polymer having a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in the polymer. In addition, the cation exchange resin may include a polymer in which the functional group is substituted for the polymer having no functional group, and an acid having the functional group may be added to the polymer having no functional group. And may include a doped polymer.

Examples of the polymer having a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof in the original polymer include Nafion (Dupont), sulfonated poly Sulfonated-poly (phenylene sulfide sulfone nitrile: s-PSSN), sulfonated-poly (arylene ether sulfone: s-PAES), sulfonated poly (Ether ether ketone: s-PEEK)), but the present invention is not limited thereto.

Examples of the polymer capable of forming a cation exchange resin by substituting a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof, or an acid having the above- Include, but are not limited to, polybenzimidazole, polyimide, polyphenylene sulfide, polysulfone, polysulfone derivatives, polyphenylene oxide, polyphenylene sulfide, and polyphosphazene.

The polymer electrolyte membrane (24) for a fuel cell may contain the porous support and the cation exchange resin at a weight ratio of about 99: 1 to about 10:90. When the content ratio of the porous support to the cation exchange resin is within the above range, the polymer electrolyte membrane for a fuel cell having the porous support and the cation exchange resin may have excellent mechanical strength and dimensional stability. Specifically, the porous support and the cation exchange resin may be contained in a weight ratio of about 95: 5 to about 30: 70.

Although not shown in FIG. 1, a polymer electrolyte for a fuel cell, which is located between the anode 22 and the cathode 26 and contains a porous support 244 but does not include a separate cation exchange resin 242, Membrane 24 may be used. In this case, the polymer electrolyte membrane 24 for a fuel cell is formed by doping the inside, the surface, or the inside and the surface with acid. The acid may be selected from the group consisting of sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid, and derivatives thereof, but is not limited thereto. The acid doped in the porous support 244 plays a role similar to that of the cation exchange resin 242. Therefore, the acid doped in the porous support 244 can improve the cation conductivity, for example, the proton conductivity of the polymer electrolyte membrane 24 for the fuel cell, and improve the efficiency of the fuel cell.

The polymer electrolyte membrane (24) for a fuel cell may have a thickness of about 20 [mu] m to about 300 [mu] m. When the thickness of the polymer electrolyte membrane 24 for a fuel cell is within the above range, excellent cation conductivity, for example, hydrogen ion conductivity can be achieved, fuel crossover can be suppressed, and excellent mechanical strength, dimensional stability, Chemical properties can be effectively achieved. Specifically, the polymer electrolyte membrane 24 for a fuel cell may have a thickness of about 20 μm to about 250 μm.

Hereinafter, the polymer forming the porous support will be specifically described.

The polyamic acid used to form the porous support is a polyamic acid containing repeating units represented by the following Chemical Formulas 1 to 4, a polyamic acid copolymer containing repeating units represented by Chemical Formulas 5 to 8, And blends thereof.

[Chemical Formula 1]

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

In the above Chemical Formulas 1 to 8,

Ar ₁ is an aromatic ring group selected from a substituted or unsubstituted quadrivalent C6 to C24 arylene group and a substituted or unsubstituted quadrivalent C4 to C24 heterocyclic group, and the aromatic ring group is present alone; Two or more are bonded to each other to form a condensed ring; Two or more single bond, O, S, C (= O), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10) , (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, and connected by a C (CF _{3) 2} or C (= O) NH functional group,

Ar ₂ is an aromatic ring group selected from a substituted or unsubstituted divalent C6 to C24 arylene group and a substituted or unsubstituted divalent C4 to C24 heterocyclic group, and the aromatic ring group is present alone; Two or more are bonded to each other to form a condensed ring; Two or more single bond, O, S, C (= O), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10) , (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, and connected by a C (CF _{3) 2} or C (= O) NH functional group,

Q is O, S, C (= O ), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10), (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, C (CF 3) 2, C (= O) NH, C (CH 3) (CF 3), or a substituted or unsubstituted phenylene group (Wherein the substituted phenylene group is substituted with a C1 to C6 alkyl group or a C1 to C6 haloalkyl group), wherein Q is connected to both aromatic rings at the positions of mm, mp, pm, or pp,

Y is the same or different from each other in each repeating unit, and is independently OH, SH or NH ₂ ,

n is an integer satisfying 20? n? 200,

m is an integer satisfying 10? m? 400,

l is an integer satisfying 10?

Examples of the polyamic acid copolymer containing the repeating units represented by the above formulas (1) to (4) include polyamic acid copolymers containing the repeating units represented by the following formulas (9) to (18).

[Chemical Formula 9]

[Chemical formula 10]

(11)

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

In the above Chemical Formulas 9 to 18,

Ar ₁ , Q, n, m and l are as defined in the above Chemical Formulas 1 to 8,

Y and Y 'are different from each other, and each independently is OH, SH or NH ₂ .

The polyimide used to form the porous support is a polyimide including the repeating units represented by the following formulas (19) to (22), a polyimide copolymer containing repeating units represented by the following formulas (23) to And blends thereof. However, the present invention is not limited thereto.

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Chemical Formula 22]

(23)

≪ EMI ID =

(25)

(26)

In the above Formulas 19 to 26,

Ar ₁ , Ar ₂ , Q, Y, n, m and l are as defined in the above formulas 1 to 8.

Examples of the polyimide copolymer containing the repeating units represented by the above formulas (19) to (22) include polyimide copolymers including repeating units represented by the following formulas (27) to (36).

(27)

(28)

[Chemical Formula 29]

(30)

(31)

(32)

(33)

(34)

(35)

(36)

In the above formulas 27 to 36,

Ar ₁ , Q, m and l are as defined in the above formulas (1) to (8)

Y and Y 'are the same or different from each other in each repeating unit, and are each independently OH, SH or NH ₂ .

In the above formulas (1) to (36), examples of Ar ₁ may be selected from the following formulas, but are not limited thereto.

In this formula,

X _1, X _2, X ₃ and X ₄ are in the same or different, each independently O, S, C (= O ), CH (OH), S (= O) 2, Si (CH 3) 2, ( CH _{2) p (where, 1≤p≤10), (CF 2)} q ( _{where, 1≤q≤10), C (CH 3} ) 2, C (CF 3) 2, or C (= O) NH ego,

W ₁ and W ₂ are the same or different and each independently O, S, or C (= O)

Z ₁ is O, S, CR ₁₀₀ R ₁₀₁ or NR ₁₀₂ wherein R ₁₀₀ , R ₁₀₁ and R ₁₀₂ are the same or different and each independently hydrogen or a C 1 to C 5 alkyl group,

Z ₂ and Z ₃ are the same or the different and each is independently N or CR ₁₀₃ to each other (wherein, R ₁₀₃ is hydrogen or C1 to C5 alkyl group) or CR ₁₀₃ at the same time is not,

R ₁ to R ₄₂ are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C10 aliphatic organic group,

k1 to k3, k8 to k14, k24 and k25 are integers of 0 to 2,

k5, k15, k16, k19, k21 and k23 are integers of 0 or 1,

k32, k26, k29, k31, k34 to k36, k38, k39 and k42 are integers of 0 to 3, and k4, k6, k7, k17, k18, k20,

k30, k37, k40 and k41 are integers from 0 to 4,

and k32 and k33 are integers of 0 to 5.

In the above Formulas 1 to 36, specific examples of Ar ₁ may be selected from the following formulas, but are not limited thereto.

In the above formulas (1) to (36), Ar ₂ may be selected from the following formulas, but is not limited thereto.

In this formula,

X _1, X _2, X ₃ and X ₄ are in the same or different, each independently O, S, C (= O ), CH (OH), S (= O) 2, Si (CH 3) 2, ( CH _{2) p (where, 1≤p≤10), (CF 2)} q ( _{where, 1≤q≤10), C (CH 3} ) 2, C (CF 3) 2, or C (= O) NH ego,

W ₁ and W ₂ are the same or different and each independently O, S, or C (= O)

Z ₁ is O, S, CR ₁₀₀ R ₁₀₁ or NR ₁₀₂ wherein R ₁₀₀ , R ₁₀₁ and R ₁₀₂ are the same or different and each independently hydrogen or a C 1 to C 5 alkyl group,

Z ₂ and Z ₃ are the same or the different and each is independently N or CR ₁₀₃ to each other (wherein, R ₁₀₃ is hydrogen or C1 to C5 alkyl group) or CR ₁₀₃ at the same time is not,

R ₄₃ to R ₈₉ are the same or different and are each independently hydrogen, a substituted or unsubstituted C1 to C10 aliphatic organic group, or a metal sulfonate group,

k43, k49, k64 to k68, k72 to k76, and k82 to k89 are integers of 0 to 4,

k44 to k46, k48, k51, k54, k55, k57, k58, k61 and k63 are integers of 0 to 3,

k57, k56, k59, k60, k62, k70, k78, k80 and k81 are integers of 0 to 2,

k50 is an integer of 0 or 1,

k69, k71, k77, and k79 are integers from 0 to 5.

In the above Formulas 1 to 36, specific examples of Ar ₂ may be selected from the following formulas, but are not limited thereto.

Wherein M is a metal and the metal may be sodium, potassium, lithium, an alloy thereof, or combinations thereof, but is not limited thereto.

Examples of Q in the above Chemical Formulas 1 to 36 may be selected from C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O, S, S (= O) ₂ or C It is not.

In the above Chemical Formulas 1 to 36, Ar ₁ may be a functional group represented by any one of the following formulas A1 to A8, Ar ₂ may be a functional group represented by any one of the following formulas B1 to B11, Q is C (CF ₃ ) ₂ , but is not limited thereto.

[Formula A1] [Formula A2] [Formula A3]

[Chemical Formula A4] [Chemical Formula A5] [Chemical Formula A6]

                  [Chemical formula A7] [Chemical formula A8]

[Formula B1] [Formula B2] [Formula B3]

[Chemical formula B4] [Chemical formula B5] [Chemical formula B6] [Chemical formula B7]

[Chemical formula B8] [Chemical formula B9]

(B11)

The polyamic acid including the repeating units represented by the above formulas (1) to (4) and the polyimide including the repeating units represented by the above formulas (19) to (22) can be produced through a general production method. As an example, a monomer is prepared by reacting an aromatic diamine containing a tetracarboxylic acid anhydride with an OH, SH or NH ₂ group.

The polyamic acid containing the repeating units represented by the above Chemical Formulas 1 to 4 is imidized and thermally converted by a predetermined heat treatment and the polyimide containing the repeating units represented by Chemical Formulas 19 to 22 is subjected to a predetermined heat treatment And converted into polymers such as polybenzoxazole, polybenzothiazole, and polypyrrolone having picopores and excellent mechanical properties and high free volume. Here, the polyhydroxyamic acid represented by the general formulas (1) to (4) is OH or the polybenzoxazole derived from the polyhydroxyimide wherein Y is OH in the general formulas (19) to (22), polythiol amic acid wherein Y is SH A porous support comprising polypyrrolone derived from polybenzothiazole derived from polythiol imide, polyaminoamic acid with Y = NH ₂ or polyaminoimide is prepared.

A molar ratio between repeating units in a copolymer of a polyamic acid containing repeating units represented by the above Chemical Formulas 1 to 4; Or by adjusting the molar ratio between the respective repeating units in the copolymer of polyimide containing the repeating units represented by the above-mentioned chemical formulas (19) to (22), the physical properties of the prepared porous substrate can be controlled.

The polyamic acid copolymer containing the repeating units represented by Chemical Formulas 5 to 8 may be imidized and thermally converted by a predetermined heat treatment. The polyimide copolymer containing the repeating units represented by the above Chemical Formulas 23 to 26 may be thermally converted by a predetermined heat treatment. Thus, the polyimide copolymer containing the repeating units represented by the above Chemical Formulas 5 to 8 and the repeating units represented by the above Chemical Formulas 23 to 26 has pico pores and has excellent mechanical properties and high freedom (Benzooxazole-imide) copolymer, poly (benzothiazole-imide) copolymer or poly (pyrrolone-imide) copolymer having a volumetric degree, To form a porous support. At this time, it is possible to control the physical properties of the prepared porous support by controlling the copolymerization ratio (molar ratio) between the block which is thermally converted into polybenzoxazole, polybenzothiazole or polypyrrolone and the block of polyimide by intramolecular and intermolecular rearrangement Do.

The polyamic acid copolymer containing the repeating units represented by Chemical Formulas 9 to 18 may be imidized and thermally converted by a predetermined heat treatment. The polyimide copolymer containing the repeating units represented by the above formulas (27) to (36) may be thermally converted by a predetermined heat treatment. Thus, the copolymer of the polyamic acid containing the repeating units represented by the above formulas (9) to (18) and the repeating unit represented by the above formulas (27) to (36) has pico pores and excellent mechanical properties A polybenzoxazole, a polybenzothiazole and a polypyrrolone having a high degree of free volume can be converted into a copolymer to form a porous support comprising the copolymer. At this time, the physical properties of the prepared porous support can be controlled by controlling the copolymerization ratio (molar ratio) between the blocks converted into polybenzoxazole, polybenzothiazole and polypyrrolone, respectively.

A molar ratio between repeating units in a copolymer of a polyamic acid containing repeating units represented by the above Chemical Formulas 1 to 4; Or the polyamic acid copolymer containing the repeating units represented by the above formulas (5) to (8) has a block copolymerization ratio m: 1 of about 0.1: 9.9 to about 9.9: 0.1, specifically about 2: 8 to about 8: 2, more specifically about 5: 5.

The molar ratio between the respective repeating units in the copolymer of polyimide including the repeating units represented by the above Chemical Formulas 19 to 22; Or the copolymerization ratio (molar ratio) m: l of the polyimide copolymer containing the repeating units represented by the above Chemical Formulas 23 to 26 is about 0.1: 9.9 to about 9.9: 0.1, specifically about 2: 8 to about 8: 2, more specifically about 5: 5.

Such molar ratio to copolymerization ratio affects the morphology of the porous support to be produced. Such morphological changes are related to pore characteristics, heat resistance, surface hardness and the like. When the molar ratio or the copolymerization ratio is within the above range, the porous support to be produced can have excellent mechanical properties and dimensional stability, can have excellent porosity, and can have excellent processability and shorten the process time and cost. .

In the porous support, the polymer derived from the polyamic acid and the polymer derived from the polyimide may include a polymer containing a repeating unit represented by any one of the following formulas (37) to (50), or a copolymer thereof, It is not.

(37)

(38)

[Chemical Formula 39]

(40)

(41)

(42)

(43)

(44)

[Chemical Formula 45]

(46)

(47)

(48)

(49)

(50)

In the above formulas 37 to 50,

Ar ₁ , Ar ₂ , Q, n, m and l are as described in Ar ₁ , Ar ₂ , Q, n,

Ar ₁ 'is an aromatic ring group selected from a substituted or unsubstituted divalent C6 to C24 arylene group and a substituted or unsubstituted divalent C4 to C24 heterocyclic group, and the aromatic ring group is present alone; Two or more are bonded to each other to form a condensed ring; Two or more single bond, O, S, C (= O), CH (OH), S (= O) 2, Si (CH 3) 2, (CH 2) p ( where, 1≤p≤10) , (CF _{2) q (where, 1≤q≤10), C (CH 3} ) 2, and connected by a C (CF _{3) 2} or C (= O) NH functional group,

Y " is O or S;

Examples and specific examples of Ar ₁ , Ar ₂ and Q in the above formulas (37) to (50) are the same as the examples and specific examples of Ar ₁ , Ar ₂ and Q in the above formulas (1) to (36), respectively.

In the above formulas (37) to (50), examples of Ar _{1 '} and specific examples thereof are the same as those mentioned in the examples and specific examples of Ar _{2 in} the above formulas (1) to (36).

In the general formula 37 to 50, Ar ₁ may be a functional group represented by any of the general formula A1 to A8, Ar ₁ 'is to may be a functional group represented by any one of formulas C1 to C8, Ar ₂ has the formula B1 be an action to B11 represented by any one of, and, Q is C (CF ₃₎ may be a _2, and the like.

≪ RTI ID = 0.0 > (C3) < / RTI &

[Formula C4] [Formula C5] Formula [C6]

(C8) < RTI ID = 0.0 > (C8)

On the other hand, in the polymer electrolyte membrane for a fuel cell, the porous support may include a fluorine group on its surface. In this case, the adhesion to the ionic conductor can be improved, and the wettability, permeation, electrical conductivity, grafting property, and mechanical behavior of the porous support can be improved Can be improved.

The fluorine group may be introduced by a direct fluorination method, a plasma deposition method, or the like using, for example, fluorine or fluoride, but is not limited thereto.

The porous support has an excellent dimensional stability with less than about 10% shrinkage even after the heat treatment.

According to another embodiment of the present invention, there is provided a polyamic acid or polyimide having a repeating unit prepared from an aromatic diamine and a dianhydride containing at least one functional group existing ortho to an amine group; And a composition for forming a porous support comprising an organic solvent. The organic solvent may include dimethylsulfoxide; N-methyl-2-pyrrolidone; N-methylpyrrolidone; N, N-dimethylformamide; N, N-dimethylacetamide; ketones selected from the group consisting of? -butyrolactone, cyclohexanone, 3-hexanone, 3-heptanone and 3-octanone; And combinations thereof.

When the organic solvent is used, the polymer such as the polyamic acid or the polyimide can be easily dissolved. In addition, the composition for forming a porous support can be formed in a meta-stable state by mixing well with an adjuvant described later, thereby easily forming a porous support.

The composition for forming a porous support contains about 1 wt% to about 40 wt% of the polyamic acid or the polyimide and about 60 wt% to about 99 wt% of the organic solvent, based on the total amount of the composition for forming a porous support . When the content of each component of the composition for forming a porous support is within the above range, the viscosity of the composition for forming a porous support can be appropriately maintained to facilitate the production of the porous support, and the surface of the formed porous support and the size of the inner pore It can be adjusted appropriately. In addition, it is possible to maintain the strength of the porous support to be excellent, thereby easily forming a porous support having excellent mechanical strength and dimensional stability and a polymer electrolyte membrane for a fuel cell comprising the porous support.

The composition for forming a porous support may be water; Alcohols selected from the group consisting of methanol, ethanol, 2-methyl-1-butanol, 2-methyl-2-butanol, glycerol, ethylene glycol, diethylene glycol and propylene glycol; Ketones selected from the group consisting of acetone and methyl ethyl ketone; A polymer compound selected from the group consisting of polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyethylene glycol, polypropylene glycol, chitosan, chitin, dextran and polyvinylpyrrolidone; Tetrahydrofuran; Trichloroethane; And combinations thereof. ≪ Desc / Clms Page number 7 >

Since the adjuvant is not excellent in solubility with polyamic acid or polyimide, it can not be used alone, but when mixed with an organic solvent, it is possible to prepare a composition for forming a meta-stable porous support, and a composition for forming a porous support When electrospun, it is possible to effectively form a nonwoven fabric having appropriate pore size, pore distribution and porosity.

The auxiliary agent may be removed by diffusion, evaporation, or the like at the time of forming the porous support, and micropores may be formed in the porous support, thereby increasing the porosity of the porous support. Specifically, the polymer compound may be used as a porosity regulator. The adjuvant may also be used for phase separation temperature or for viscosity control of the composition for forming a porous support.

Wherein the composition for forming a porous support comprises about 1 wt% to about 40 wt% of the polyamic acid or the polyimide and about 10 wt% to about 95 wt% of the organic solvent, based on the total amount of the composition for forming a porous support, By weight, and from about 4% to about 70% by weight of the adjuvant. When the content of each component in the composition for forming a porous support is within the above range, the viscosity of the composition for forming a porous support can be appropriately maintained to facilitate the production of the porous support, and the surface of the formed porous support and the size of the internal pore It can be adjusted appropriately. In addition, it is possible to maintain the strength of the porous support to be excellent, thereby easily forming a porous support having excellent mechanical strength and dimensional stability and a polymer electrolyte membrane for a fuel cell comprising the porous support.

 The composition for forming a porous support may have a viscosity of about 0.01 Pa · s to about 100 Pa · s. If the viscosity of the composition for forming a porous support is within the above range, the composition for forming a porous support can be easily electrospun and the porous support can be solidified easily through solid phase transition.

In the composition for forming a porous support, the polyamic acid and the polyimide may have a weight average molecular weight (Mw) of about 10,000 g / mol to about 500,000 g / mol, respectively. When the weight average molecular weight of the polyamic acid and the polyimide is within the above range, its synthesis is easy, the viscosity of the composition for forming a porous support containing the polyamic acid and the polyimide is appropriately maintained, and the processability is excellent, and the polymer derived from the polyamic acid and the poly The polymer derived from the mid-chain can maintain excellent mechanical strength and dimensional stability.

In the composition for forming a porous support, the polyamic acid may be at least one selected from the group consisting of a polyamic acid including the repeating units represented by the above formulas (1) to (4), a polyamic acid copolymer containing the repeating units represented by the above formulas And blends thereof. The polyimide may be a polyimide including the repeating units represented by the above formulas 19 to 22, a polyimide copolymer containing the repeating units represented by the above formulas 23 to 26, a copolymer thereof, and a blend thereof Lt; / RTI >

According to another embodiment of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; And heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide.

According to another embodiment of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; Heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide; And forming a cation exchange resin on the inside, the surface, or the inside and the surface of the porous support, as well as a method for manufacturing a polymer electrolyte membrane for a fuel cell.

A nonwoven fabric containing fibers having a diameter of several nanometers to several tens of micrometers can be formed by electrospinning the composition for forming a porous support. The nonwoven fabric containing the fibers may have a large specific surface area and may have a considerable surface roughness. Also, the formed nonwoven fabric may include micropores.

The nonwoven fabric may be formed by randomly arranging fibers including the composition for forming a porous support by adjusting the method of electrospinning and the process conditions.

On the other hand, the nonwoven fabric may be formed by arranging the fibers including the composition for forming a porous support in one direction by controlling the electrospinning method and the process conditions. Advantages of this are as described above.

The electrospinning may be performed by applying a high voltage of about 1 kV to about 1,000 kV. Since electrospinning can be performed according to a general method, detailed description will be omitted.

Then, the nonwoven fabric is heat-treated. The polyamic acid or polyimide contained in the nonwoven fabric by the heat treatment is a polymer having excellent mechanical strength and dimensional stability due to thermal conversion and high free volume, such as polybenzoxazole, polybenzothiazole, polypyrrolone And is converted into a polymer. As a result, a porous support excellent in physical properties such as mechanical strength and dimensional stability can be formed.

Specifically, the ratio (thermal transfer rate) of the repeating units to be thermally converted relative to the total amount of the repeating units contained in the polyamic acid or the polyimide may be about 10 mol% to about 100 mol%, and specifically about 40 mol% Mol% to about 100 mol%. Advantages that the thermal exchange rate may have in the above range are as described above.

The heat treatment may be performed at a temperature of from about 250 ° C to about 550 ° C, and may be performed from about 10 minutes to about 5 hours, and the rate of temperature rise during the heat treatment may be from about 1 ° C / minute to about 20 ° C / minute. When the heat treatment is performed under the above conditions, heat conversion of the polyamic acid and the polyimide can be effectively performed. That is, by easily converting the polyamic acid and the polyimide into a polymer such as polybenzoxazole, polybenzothiazole or polypyrrolone having pico porosity and excellent mechanical properties and high free volume, mechanical properties and dimensional stability , Has excellent chemical resistance and heat resistance, can effectively contain a cation exchange resin, and can form a porous support. Specifically, the heat treatment may be performed at a temperature of from about 350 ° C. to about 450 ° C., and may be performed for from about 1 hour to about 3 hours, and the rate of temperature rise during the heat treatment may be from about 5 ° C./min to about 10 ° C./min .

Subsequently, a cation exchange resin is formed on the inside, the surface, or the inside and the surface of the porous support. As a method for forming a cation exchange resin on the inside, the surface, or the inside and the surface of the porous support, it is possible to employ a method in which a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, A method of immersing the porous support in a solution containing the polymer; And the porous support is immersed in a solution containing the polymer having no functional group as described above, dried, and then immersed again in an acid aqueous solution containing the functional groups as described above to replace with the functional groups as described above, A method of doping with an acid having a functional group, but the present invention is not limited thereto.

The solution containing the polymer for forming the cation exchange resin may be prepared by dissolving the polymer in a solvent such as N, N-dimethylacetamide (DMAc), N-methyl pyrrolidone (NMP) In an organic solvent. Specifically, the solution containing the polymer may be prepared by dissolving the polymer in an organic solvent such as N, N-dimethylacetamide or N-methylpyrrolidone so that the polymer is about 1% by weight to about 40% by weight.

The porous support is immersed in a solution containing the prepared polymer at a temperature of from room temperature to about 200 DEG C, specifically, at a temperature of from about 80 DEG C to about 200 DEG C, and then the porous support is allowed to stand for about 1 hour to about 20 hours.

For example, when the porous support is immersed in a solution containing a polymer having a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof, The polymer electrolyte membrane for a fuel cell can be formed by drying in an oven. However, the present invention is not limited thereto. After drying, the polymer electrolyte membrane for a fuel cell may be formed by immersing it in an acid aqueous solution having a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, have.

When the porous support is immersed in a solution containing a polymer which does not have a functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonous acid group and derivatives thereof, it is dried in a vacuum oven , Followed by immersion in an aqueous solution containing an acid selected from the group consisting of sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid and derivatives thereof, followed by removal, washing with distilled water (deionized water) and drying, A polymer electrolyte membrane can be formed.

According to another embodiment of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; Heat treating the nonwoven fabric to form a porous support comprising a polymer derived from the polyimide; And a step of doping the inside, the surface, or the inside and the surface of the porous support with an acid. The present invention also provides a method for manufacturing a polymer electrolyte membrane for a fuel cell.

The acid may be selected from the group consisting of sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid, and derivatives thereof, but is not limited thereto.

In this case, a polymer electrolyte membrane for a fuel cell is formed by directly dipping the inside, the surface, or the inside and the surface of the porous support without forming a separate cation exchange resin on the inside, the surface, or the inside and the surface of the porous support .

Specifically, the porous support is immersed in an aqueous solution containing an acid selected from the group consisting of a sulfonic acid, a carboxylic acid, a phosphoric acid, a phosphonic acid, and derivatives thereof, and a solution containing about 1 For about 24 hours, and then dried to form a polymer electrolyte membrane for a fuel cell. As the acid aqueous solution, an aqueous acid solution having a concentration of about 1 M to about 30 M can be used. The description of the electrospinning and the heat treatment is as described above.

According to another embodiment of the present invention, there is provided a method for preparing a porous support, comprising: electrospinning a composition for forming a porous support to form a nonwoven fabric; Heat treating the nonwoven fabric to form a porous support comprising a polymer derived from polyamic acid or a polymer derived from polyimide; And introducing a fluorine group to the surface of the porous support. The present invention also provides a method for manufacturing a polymer electrolyte membrane for a fuel cell. In this case, the adhesion between the porous support and the cation exchange resin, for example, can be improved, and the wettability of the porous support to the cation exchange resin can be improved. In addition, the permeation, electrical conductivity, grafting, and mechanical behavior of the polymer electrolyte membrane for a fuel cell including the porous support can be improved. The fluorine group can be introduced directly to the porous support by using fluorine or fluoride, for example, by a fluorination method, a plasma deposition method, or the like, whereby a surface-fluorinated porous support can be produced.

Then, the porous support may be impregnated with a cation exchange resin to prepare a polymer electrolyte membrane for a fuel cell, as described above.

The description of the electrospinning and the heat treatment is as described above.

A schematic structure of a fuel cell system according to an embodiment of the present invention is shown in Fig. Referring to FIG. 2, a system for supplying fuel and an oxidant to a generator using a pump is shown. However, the present invention is not limited thereto and may be used in a fuel cell system structure using a pump-free diffusion system .

The fuel cell system 1 according to an embodiment of the present invention includes at least one electricity generating unit 3 for generating electric energy through an oxidation reaction of a fuel and an oxidizing agent reduction reaction, And an oxidant supply part 7 for supplying an oxidant to the electricity generation part 3. The oxidant supply part 5 supplies the oxidant to the electricity generation part 3,

The fuel supply unit 5 for supplying the fuel may include a fuel tank 9 for storing the fuel and a fuel pump 11 connected to the fuel tank 9. The fuel pump 11 functions to discharge the fuel stored in the fuel tank 9 by a predetermined pumping force.

The oxidant supply part (7) for supplying the oxidant to the electricity generating part (3) is provided with at least one oxidant pump (13) for sucking the oxidant with a predetermined pumping power.

The electricity generating portion 3 is composed of a membrane-electrode assembly 17 for oxidizing and reducing the fuel and oxidizing agent, and a separator 19, 19 'for supplying fuel and oxidant to both sides of the membrane- , And at least one such electricity generating portion 17 is gathered to constitute the stack 15.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples and comparative examples are for illustrative purposes only and are not intended to limit the present invention.

Example  1: Preparation of Polymer Electrolyte Membrane for Fuel Cell

A polymer electrolyte membrane for a fuel cell comprising a polybenzoxazole-containing polymer containing a repeating unit represented by the following formula (51) was prepared from a polyhydroxyimide as shown in the following Reaction Scheme 1.

[Reaction Scheme 1]

(1) Production of polyhydroxyimide

3.66 g (10 mmol) of 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane and 4.44 g of 4,4 '- (hexafluoroisopropylidene) diphthalic anhydride ) Was added to 32.4 g of N-methylpyrrolidone (NMP), and stirred vigorously for 4 hours. The polyhydroxyimide was then prepared by adding 32 ml of xylene as the azeotropic mixture and removing the mixture of water and xylene with imidization of the thermal solution at 180 占 폚 for 12 hours.

(2) Preparation of Porous Support Containing Polybenzoxazole

Dimethylformamide (DMF) was added to the solution containing the polyhydroxyimide to prepare a composition for forming a porous support containing 25 wt% of the polyhydroxyimide.

The composition for forming a porous support was applied with a voltage of +10 kV to the cylinder portion and a voltage of -4 kV to the drum portion using a drum-type electrospinning equipment ESR200RD (manufactured by NanoNC), and a spinning rate of 15 cm and a flow rate of 0.1 Mu] l / min, and a drum speed of 50 rpm to prepare a nonwoven fabric containing fibers.

Then, the nonwoven fabric was heat-treated at 300 ° C for 1 hour, and further heat-treated at 400 ° C for 1 hour. Then, the nonwoven fabric was slowly cooled to room temperature to prepare a porous support containing polybenzoxazole. The rate of temperature rise during the heat treatment was 5 ° C / min.

The porosity of the porous support measured using a capillary flow porometer instrument CFP-1500-AE (manufactured by Porous Materials) was 91%. The thickness of the porous support was 40 mu m.

(3) Preparation of polyelectrolyte membrane for fuel cell including polybenzoxazole

The porous support was immersed in a solution of 10 g of sulfonated poly (arylene ether sulfone: s-PAES) in 90 g of N, N-dimethylacetamide (DMAc) for 1 hour After immersion, the membrane was slowly dried in an oven to prepare a polyelectrolyte membrane for fuel cells containing polybenzoxazole. The thermoelectric conversion rate was 46 mol%.

As a result of FT-IR analysis of the mid-poly hydroxyimino polybenzoxazole characteristic band, which did not exist 1,553 cm ^- the band of ^{1, 1,480 cm -1 (C =} N) and 1,058 cm ^-1 (CO) it was observed. The free volume of the prepared polymer was 0.193 and interplanar distance was 558 pm.

The density of the polymer is related to the free volume.

First, the density of the film was measured by a buoyancy method using a Sartorius LA 310S analytical balance according to Equation (1).

[Equation 1]

In the above equation (1)

는 고분자의 밀도이고,

Is the density of the polymer,

는 탈이온수의 밀도이고,

Is the density of deionized water,

는 공기 중에서 측정한 고분자의 무게이고,

Is the weight of the polymer measured in air,

는 탈이온수에서 측정한 고분자의 무게이다.

Is the weight of the polymer measured in deionized water.

The free volume diagrams (FFV, V _f ) were calculated from the above data according to the following equation (2).

&Quot; (2) "

In Equation (2)

V is the specific volume of the polymer,

Vw is a specific Van der Waals volume.

The interplanar distance was calculated according to the Bragg's equation from the results of the X-ray diffraction pattern.

Also, the full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 16.1 pm in the porous support containing the polybenzoxazole.

PALS measurements were performed on nitrogen at ambient temperature using an automated EG & G Ortec fast-fast coincidence spectrometer. The time resolution of the system was 240..

Polymer membranes were installed on both sides of the ²² Na-Ti foil source ( ²² Na-Ti foil source) to a thickness of 1 mm. There was no source correction for the Ti foil (thickness 2.5 占 퐉). Each spectrum was made up of about 10 million unified counts and was made up of the sum of three decaying exponentials or a continuous distribution. The PALS data show that the time difference τ ₁ , τ ₂ , τ ₃ between γ ₀ of 1.27 MeV and γ ₁ and γ ₂ of 0.511 MeV generated at the time of extinction by irradiating positron generated from ²² Na isotopes And so on.

The pore size was calculated by the following equation (3) using the disappearance time of two? Signals of 0.511 MeV.

&Quot; (3) "

In Equation (3)

τ _{o- Ps} is the decay time of the positron,

R is the pore size,

ΔR is the empirical parameter of the assumption that the pore is spherical.

Example  2: Preparation of Polymer Electrolyte Membrane for Fuel Cell

Polybenzoxazole-containing polymer electrolyte membrane containing the repeating unit represented by Chemical Formula 51 was prepared in the same manner as in Example 1, except that the non-woven fabric was heat-treated at 400 ° C for 2 hours. The heat exchange rate was 61%.

FT-IR analysis showed that polybenzoxazole characteristic bands of 1,553 cm ^-1 , 1,480 cm ^-1 (C = N) and 1,058 cm ^-1 (CO) were not present in the polyhydroxyimide. The free volume of the prepared polymer was 0.200 and the interplanar distance was 564.4 pm.

The full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 19.4 pm.

Example  3: Preparation of Polymer Electrolyte Membrane for Fuel Cell

Polybenzoxazole-containing polybenzoxazole-containing polymer electrolyte membrane was prepared in the same manner as in Example 1, except that the non-woven fabric was heat-treated at 400 ° C for 3 hours. The thermal exchange rate was 69%.

FT-IR analysis showed that polybenzoxazole characteristic bands of 1,553 cm ^-1 , 1,480 cm ^-1 (C = N) and 1,058 cm ^-1 (CO) were not present in the polyhydroxyimide. The free volume of the prepared polymer was 0.204 and the interplanar distance was 567.6 pm.

The full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 21.1 pm.

Example  4: Preparation of polymer electrolyte membrane for fuel cell

The polymer electrolyte membrane for fuel cells including polybenzoxazole containing the repeating unit represented by Chemical Formula 51 was prepared in the same manner as in Example 1 except that the nonwoven fabric was heat-treated at 425 ° C for 1 hour. The thermal exchange rate was 80%.

FT-IR analysis showed that polybenzoxazole characteristic bands of 1,553 cm ^-1 , 1,480 cm ^-1 (C = N) and 1,058 cm ^-1 (CO) were not present in the polyhydroxyimide. The free volume of the prepared polymer was 0.210 and the interplanar distance was 572 pm.

The full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 23.6 pm.

Example  5: Preparation of polymer electrolyte membrane for fuel cell

A polyelectrolyte membrane for a fuel cell comprising a polybenzoxazole containing a repeating unit represented by the formula (51) was prepared in the same manner as in Example 1 except that the nonwoven fabric was heat-treated at 425 ° C for 2 hours. The thermal exchange rate was 88%.

FT-IR analysis showed that polybenzoxazole characteristic bands of 1,553 cm ^-1 , 1,480 cm ^-1 (C = N) and 1,058 cm ^-1 (CO) were not present in the polyhydroxyimide. The free volume of the prepared polymer was 0.214 and the interplanar distance was 575.2 pm.

The full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 25.3 pm.

Example  6: Preparation of Polymer Electrolyte Membrane for Fuel Cell

Polybenzoxazole-containing polybenzoxazole-containing polymer electrolyte membrane was prepared in the same manner as in Example 1, except that the non-woven fabric was heat-treated at 425 ° C for 3 hours. The thermal exchange rate was 91%.

FT-IR analysis showed that polybenzoxazole characteristic bands of 1,553 cm ^-1 , 1,480 cm ^-1 (C = N) and 1,058 cm ^-1 (CO) were not present in the polyhydroxyimide. The free volume of the prepared polymer was 0.215 and interplanar distance was 576.4 pm.

The full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 26.2 pm.

Example  7: Preparation of polymer electrolyte membrane for fuel cell

A polyelectrolyte membrane for a fuel cell comprising a polybenzoxazole containing the repeating unit represented by the formula (51) was prepared in the same manner as in Example 1, except that the nonwoven fabric was heat-treated at 450 ° C for 1 hour. The thermal exchange rate was 95%.

FT-IR analysis showed that polybenzoxazole characteristic bands of 1,553 cm ^-1 , 1,480 cm ^-1 (C = N) and 1,058 cm ^-1 (CO) were not present in the polyhydroxyimide. The free volume of the prepared polymer was 0.217 and the interplanar distance was 578 pm.

The full width at half maximum (FWHM) measured by positron annihilation lifetime spectroscopy (PALS) was 26.9 pm.

Comparative Example  1: Preparation of Polymer Electrolyte Membrane for Fuel Cell

A polymer electrolyte membrane for a fuel cell including a polyimide-containing polymer comprising a repeating unit represented by the following Chemical Formula 52 was prepared from polyamic acid as shown in Reaction Scheme 2 below.

[Reaction Scheme 2]

(1) Preparation of polyamic acid

2.94 g (10 mmol) of 3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride (3,3', 4,4'-biphenyl tetracarboxylic dianhydride) and 4,4'-diaminodiphenyl 2.00 g (10 mmol) of ether (4,4'-diaminodiphenyl ether) was added to 20 ml of dimethylacetamide (DMAc) and reacted at 15 ° C for 4 hours to prepare a pale yellow viscous polyamic acid solution. The weight average molecular weight of the polyamic acid was 120,000.

(2) Preparation of a porous support containing polyimide

Dimethylformamide (DMF) was added to the prepared polyamic acid solution having a viscosity to prepare a composition for forming a porous support containing 25 wt% of the polyamic acid.

Using the drum-type electrospinning apparatus for forming a porous support, electricity of +12 kV was applied to the cylinder portion and -4 kV to the drum portion. The spinning rate was set to 15 cm, the flow rate was 0.1 μL / min, and the drum speed was 50 rpm To prepare a nonwoven fabric containing fibers.

Then, the nonwoven fabric was heat-treated at 350 ° C. for 1 hour and slowly cooled to room temperature to prepare a porous support containing polyimide. The rate of temperature rise during the heat treatment was 5 ° C / min.

The porosity of the porous support measured using a capillary flow porometer was 65%. The thickness of the porous support was 43 탆.

(4) Production of polyelectrolyte membrane for fuel cell containing polyimide

The porous support was immersed in a solution of 10 g of sulfonated poly (arylene ether sulfone: s-PAES) in 90 g of dimethylformamide (DMF) for 1 hour, By slowly drying in an oven, a polymer electrolyte membrane for a fuel cell including polyimide was produced.

A result of FT-IR analysis, it was confirmed that a polyimide characteristic band of 1787 cm ^-1, a band of 1731cm ^-1, 1360 cm ^-1 and 724 cm ^-1. The free volume of the prepared polymer was 0.12 and the interplanar distance was 520 pm.

Test Example  1: Photos

The porous support prepared in Examples 1 to 7 and Comparative Example 1 was photographed using a general camera. Among them, the photograph of the porous support prepared in Example 4 is shown in Fig.

The polymer electrolyte membrane for fuel cells prepared in Examples 1 to 7 and Comparative Example 1 was photographed using a general camera. 4 shows a photograph of the polymer electrolyte membrane for a fuel cell manufactured in Example 4. FIG.

As shown in FIG. 3 and FIG. 4, it can be confirmed that the porous support prepared in Example 4 is effectively wetted on the cation exchange resin and changed transparently. As a result, it can be confirmed that the porous support prepared in Example 4 is excellent in wettability with respect to the cation exchange resin, so that the cation exchange resin is well impregnated.

Test Example  2: Proton conductivity evaluation

The polymer electrolyte membrane for fuel cells prepared in Examples 1 to 7 and Comparative Example 1 was cut into a size of 1 cm x 4 cm and then analyzed with an impedance / gainphase analyzer (Solartron 1260) and an electrochemical interface (Solartron 1287, Farnborough, Hampshire, UK The polymer electrolyte membrane for each fuel cell was fixed to the equipment and the R value was measured. The proton conductivity was calculated by the following equation (4). Among them, the results of Example 4 are shown in Table 1 below.

&Quot; (4) "

Proton conductivity = d / (L _s x W _s x R)

d: distance between electrodes

L _s : thickness of polymer electrolyte membrane for fuel cell

W _s : width of polymer electrolyte membrane for fuel cell (1 cm)

R: Resistance

Test Example  3: Water Absorption Rate ( water uptake ) Characteristic evaluation

The polymer electrolyte membrane for fuel cells prepared in Examples 1 to 7 and Comparative Example 1 was cut into a size of 4 cm x 4 cm.

Then, the dry weight (W _d ) of each of the polymer electrolyte membranes for fuel cells was measured.

Each of the polymer electrolyte membranes for fuel cells was immersed in distilled water (deionized water) at 80 ° C for 24 hours. Then, each of the polymer electrolyte membranes for fuel cells was taken out, and the weight (W _w ) of the polymer electrolyte membrane for a fuel cell was measured.

The water absorption rate was calculated by substituting the measured weight value into the following equation (5).

&Quot; (5) "

Water absorption _{(%) = ((W w} -W d) / W d) ⅹ100

W _d : weight of dried polymer electrolyte membrane for fuel cell

W _w : weight of polymer electrolyte membrane for fuel cell after hydration

Test Example  4: Evaluation of dimensional stability

The polymer electrolyte membrane for fuel cells prepared in Examples 1 to 7 and Comparative Example 1 was cut into a size of 4 cm x 4 cm. Then, each of the polymer electrolyte membranes for fuel cells was dried in a vacuum oven at 100 캜 for 24 hours. In the dried state, the length and width of each of the polymer electrolyte membranes for fuel cells were measured.

Subsequently, each of the polymer electrolyte membranes for fuel cells was immersed in distilled water (deionized water) at 80 DEG C, and left for one day. Each of the hydrated polymer electrolyte membranes for fuel cells was taken out and the length and width of the polymer electrolyte membrane for a fuel cell were measured.

The length and width of the polymer electrolyte membrane for a fuel cell were measured using a video microscope system ICS-305B (manufactured by Sometech) in order to reduce errors due to rapid desorption of water molecules in the polymer electrolyte membrane for a fuel cell Respectively.

The measured length and width of the polymer electrolyte membrane for fuel cells were substituted into the following equation (6) to evaluate the dimensional stability. Here, the dimensional stability was evaluated using the length of the polymer electrolyte membrane for a fuel cell.

&Quot; (6) "

Dimensional stability (% change) = ((D _{wet -} D _dry ) / D _dry )

D _dry : Dimensions (length or width) of a polymer electrolyte membrane for a dry fuel cell

D _wet : Dimensions (length or width) of the polymer electrolyte membrane for hydrated fuel cells

Proton conductivity
(S / cm, 80 DEG C) Water absorption rate
(%, 80 DEG C) Dimensional stability
(%, 80 DEG C) Example 4 0.095 39.28 23.57 Comparative Example 1 0.08 > 100 30

As shown in Table 1, it was confirmed that the polymer electrolyte membrane for fuel cell manufactured in Example 4 exhibited a proton conductivity superior to that of the polymer electrolyte membrane for fuel cell manufactured in Comparative Example 1, and exhibited a low moisture absorption rate and a high dimensional stability have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And it goes without saying that the invention belongs to the scope of the invention.

20: membrane-electrode assembly for a fuel cell, 22: anode,
24: polymer electrolyte membrane, 26: cathode,
244: porous support, 242: cation exchange resin,
1: fuel cell system, 3: electricity generating unit,
5: fuel supply unit, 7: oxidant supply unit,
9: fuel tank, 11: fuel pump,
13: oxidant pump, 17: membrane-electrode assembly,
19, 19 ': separator, 15: stack

Claims (7)

Polyamic acid or polyimide having repeating units prepared from an aromatic diamine and dianhydride containing at least one functional group present in ortho position with respect to the amine group; And
1. A composition for forming a porous support comprising an organic solvent,
The organic solvent may include dimethylsulfoxide; N-methyl-2-pyrrolidone; N-methylpyrrolidone; N, N-dimethylformamide; N, N-dimethylacetamide; ketones selected from the group consisting of? -butyrolactone, cyclohexanone, 3-hexanone, 3-heptanone and 3-octanone; And combinations thereof. ≪ RTI ID = 0.0 >
Wherein the composition is for electrospinning.
The method according to claim 1,
Wherein the polyamic acid or the polyimide is contained in an amount of 1 to 40% by weight and the organic solvent is contained in an amount of 60 to 99% by weight based on the total amount of the composition for forming a porous support.
The method according to claim 1,
The composition for forming a porous support
water; Alcohols selected from the group consisting of methanol, ethanol, 2-methyl-1-butanol, 2-methyl-2-butanol, glycerol, ethylene glycol, diethylene glycol and propylene glycol; Ketones selected from the group consisting of acetone and methyl ethyl ketone; A polymer compound selected from the group consisting of polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyethylene glycol, polypropylene glycol, chitosan, chitin, dextran and polyvinylpyrrolidone; Tetrahydrofuran; Trichloroethane; And a combination thereof. ≪ Desc / Clms Page number 24 >
The method of claim 3,
1 to 40% by weight of the polyamic acid or the polyimide, 10 to 95% by weight of the organic solvent and 4 to 70% by weight of the auxiliary agent, based on the total amount of the composition for forming a porous support including the auxiliary agent / RTI > wherein the composition is a porous support.
The method according to claim 1,
Wherein the polyamic acid and the polyimide each have a weight average molecular weight (Mw) of 10,000 g / mol to 500,000 g / mol.
The method according to claim 1,
Wherein the composition for forming a porous support has a viscosity of 0.01 Pa · s to 100 Pa · s. The method according to claim 1,
Wherein the organic solvent comprises at least one of N-methyl-2-pyrrolidone and N-methylpyrrolidone and N, N-dimethylformamide.

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