KR20210132492A - Copolymer, polymer membrane comprising the same, gas separation membrane comprising the polymer membrane, manufacturing method of the copolymer, and manufacturing method of the gas separation membrane - Google Patents

Abstract

The present invention relates to a copolymer, a polymer membrane including the copolymer, a gas separation membrane including the polymer membrane, a method for preparing the copolymer and a method for manufacturing the gas separation membrane. Particularly, a first monomer having an imidazole group is mixed with a second monomer having a polyalkylene oxide repeating unit at a suitable ratio to form a graft copolymer, which forms a gas permeation path through microphase separation when being applied to a gas separation membrane, thereby providing improved gas permeability and selectivity. In addition, the copolymer according to the present invention has excellent mechanical rigidity, while showing adhesiveness and flexibility, is dissolved in non-toxic water or alcohol with high compatibility, and thus can be applied to various industrial fields using the same.

Description

A copolymer, a polymer membrane comprising the same, a gas separation membrane comprising the polymer membrane, a method of manufacturing the copolymer, and a method of manufacturing the gas separation membrane copolymer, and manufacturing method of the gas separation membrane}

The present invention relates to a copolymer, a polymer membrane including the same, a gas separation membrane including the polymer membrane, a method for manufacturing the copolymer, and a method for manufacturing the gas separation membrane.

Along with the rapid growth of the industrial sector, various environmental pollution factors are threatening mankind. As one of them, the technology of capturing/separating greenhouse gases such as _{CO 2 is a very important issue.} From this point of view, the polymer membrane technology is emerging as the next best solution to improve pollution because it can efficiently separate gas using a small amount of energy.

A flat membrane for gas separation can be broadly divided into two types, a free-standing membrane and a composite membrane. One of them, a composite membrane, is manufactured by coating a thin polymer layer that selectively separates gas on the surface of a porous support that allows gas to pass through quickly and complements physical properties.

This composite membrane for gas separation is very easy to manufacture, can be manufactured in a short time, and the process is simple because a low concentration polymer solution is bar-coated or spin-coated on a porous support using a thin bar. There is an advantage that

However, the polymer layer formed in the conventional composite membrane is mainly composed of polymers having a functional group such as polyethylene oxide with high carbon dioxide affinity. These polymers have low mechanical strength and low adhesion, so that they penetrate through the pores of the porous support due to their flow properties. Therefore, gas permeation was not prevented or a film was not formed.

Korean Patent Registration No. 10-1063697

In order to solve the above problems, an object of the present invention is to provide a copolymer having improved gas permeability and selectivity while being dissolved in water or alcohol and having excellent compatibility.

Another object of the present invention is to provide a polymer membrane excellent in mechanical rigidity while having adhesiveness and flexibility.

Another object of the present invention is to provide a gas separation membrane having improved separation performance of gas permeability and selectivity.

Another object of the present invention is to provide a method for preparing a copolymer.

Another object of the present invention is to provide a method for manufacturing a gas separation membrane.

The present invention provides a copolymer in which a second monomer having a polyalkylene oxide repeating unit is grafted onto a first monomer having an imidazole group.

The first monomer may be a compound represented by Formula 1 below.

[Formula 1]

(In Formula 1, n is an integer of 0 to 30.)

The second monomer may be polyoxyethylene methacrylate represented by Formula 2 below.

[Formula 2]

(In Formula 2, R ₁ and R ₂ are the same as or different from each other, and are each independently selected from H, COOH, and an alkyl group having 1 to 20 carbon atoms, and m is an integer of 1 to 50.)

The copolymer may be one in which the first monomer and the second monomer are polymerized in a weight ratio of 22 to 40: 60 to 78.

The copolymer may be a compound represented by the following formula (3).

[Formula 3]

(In Formula 3, R ₁ and R ₂ are the same as or different from each other, and are each independently selected from H, COOH and an alkyl group having 1 to 20 carbon atoms, and x and y are 65 to 85 as a polymerization molar ratio of each repeating unit: 15 to 35, n is an integer from 0 to 30, and m is an integer from 1 to 50.)

In Formula 3, R ₁ and R ₂ are the same as each other, each independently an alkyl group having 1 to 8 carbon atoms, x and y are 71 to 82: 18 to 29 as a polymerization molar ratio of each repeating unit, and n is 0 to It is an integer of 10, and m may be an integer of 1 to 15.

The copolymer may be a compound represented by the following Chemical Formula 3a.

[Formula 3a]

(In Formula 3a, x and y are 77-80: 20-23 as a polymerization molar ratio of each repeating unit.)

On the other hand, the present invention provides a polymer membrane comprising the copolymer.

The polymer membrane may be for an ionic electrolyte membrane, an ion exchange membrane, or a gas separation membrane.

In addition, the present invention is a porous support; and the polymer membrane coated on one or both surfaces of the porous support.

The porous support is polysulfone, polyester sulfone, polymethyl methacrylate, polyethylene, polypropylene, polyoxymethylene, polyether ether ketone, polyethylene terephthalate, polyacrylonitrile, cellulose acetate, polyamide, polyimide, poly It may be at least one selected from the group consisting of amideimide, polyetherimide, polyvinylidene fluoride, polyvinyl alcohol, and polyarylate.

The porous support may further include a surface coating layer having a surface coated with poly(1-trimethylsilyl-1-propyne).

The polymer film may have a thickness of 1 to 20 μm.

The gas may be at least one selected from carbon dioxide, nitrogen, and methane.

The gas separation membrane may form a gas permeation passage through which microphase separation with a size of 20 to 40 nm occurs.

The gas separation membrane may have a carbon dioxide (CO ₂ ) permeability of 148 barrer or more, a carbon dioxide/nitrogen (CO ₂ /N ₂ ) selectivity of 43 or more, and a carbon dioxide/methane (CO ₂ /CH ₄ ) selectivity of 23 or more. .

In addition, the present invention provides a method for preparing a copolymer comprising: preparing a copolymer by polymerizing a first monomer having an imidazole group and a second monomer having a polyalkylene oxide repeating unit in the presence of an initiator .

In preparing the copolymer, the first monomer and the second monomer may be polymerized in a weight ratio of 22 to 40: 60 to 78.

The step of preparing the copolymer may be a free radical reaction at 50 to 100 °C for 10 to 30 hours.

In addition, the present invention comprises the steps of preparing a copolymer by polymerizing a first monomer having an imidazole group and a second monomer having a polyalkylene oxide repeating unit in the presence of an initiator; dissolving the copolymer in a solvent to prepare a coating solution; forming a polymer film by coating the coating solution on one or both surfaces of the porous support; and drying the porous support on which the polymer membrane is formed to prepare a gas separation membrane.

In the step of preparing the coating solution, the copolymer may include 10 to 30 wt% of the total amount of the coating solution.

The solvent may be at least one selected from the group consisting of water, methanol, ethanol, propanol, butanol, isopropanol, tetrahydrofuran, ethyl acetate, chloroform, dimethyl sulfoxide, dimethylformamide and N-methyl-2-pyrrolidone. have.

The copolymer according to the present invention forms a grafted copolymer by mixing a first monomer having an imidazole group with a second monomer having a polyalkylene oxide repeating unit in an appropriate ratio to form a grafted copolymer through microphase separation when applied to a gas separation membrane. A gas permeation path may be formed to improve gas permeability and selectivity.

In addition, the copolymer according to the present invention has excellent mechanical rigidity while having adhesiveness and flexibility, and is soluble in non-toxic water or alcohol, thereby having excellent compatibility.

The effects of the present invention are not limited to the above-mentioned effects. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

1 is a photograph showing the synthesis results of PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6 according to the present invention.
Figure 2 shows the FT-IR (a) and H-NMR (b, c, d) analysis results of VIm, POEM and PVIm-POEM copolymers synthesized in Example 2 and Comparative Examples 2 and 3 according to the present invention It is a graph.
3 is a graph showing FT-IR results of PVIm and PVIm-POEM copolymers synthesized in Example 1 and Comparative Examples 1, 4, and 5 according to the present invention.
4 is a graph showing DSC results for PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6 according to the present invention.
5 is a graph showing TGA results for PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6 according to the present invention.
6 is a SAXS analysis (a) and XRD of the gas separation membranes prepared in Example 4 (PVIm-POEM37) and Comparative Examples 8 (PVIm-POEM73), 9 (PVIm-POEM55), and 12 (PPOEM) according to the present invention; It is a graph showing the analysis (b) result.
7 is a gas prepared in Example 4 (PVIm-POEM37) (e, f) and Comparative Examples 8 (PVIm-POEM73) (a, b), 9 (PVIm-POEM55) (c, d) according to the present invention This is a TEM picture of the separator.
FIG. 8 shows the phase separation of the gas separation membranes prepared in Example 4 (PVIm-POEM37) and Comparative Example 8 (PVIm-POEM73) according to the present invention.
9 is an FE-SEM photograph of a cross section of the gas separation membranes prepared in Examples 3 to 4 and Comparative Examples 7 to 12 according to the present invention.
_{10 is a graph showing the permeability of carbon dioxide (CO 2} ), carbon dioxide/nitrogen (CO ₂ /N ₂ ) and carbon dioxide/methane (CO ₂ ) for the gas separation membranes prepared in Examples 3 to 4 and Comparative Examples 7 to 12 according to the present invention; /CH ₄ ) is a graph showing the selectivity results.
11 shows the gas permeability and flat membranes made of different polymers for the gas separation membranes prepared in Example 4 (PVIm-POEM37), Comparative Example 8 (PVIm-POEM73), and Comparative Example 9 (PVIm-POEM55) according to the present invention; This is a graph comparing the separation performance of selectivity.

Hereinafter, the present invention will be described in more detail by way of one embodiment.

The present invention relates to a copolymer, a polymer membrane including the same, a gas separation membrane including the polymer membrane, a method for manufacturing the copolymer, and a method for manufacturing the gas separation membrane.

Among polymers with high carbon dioxide affinity, a polymer having an imidazole group may break on a flexible porous polysulfone support because it is too hard and inflexible, and a polymer having an ethylene glycol group does not form a membrane by penetrating through the pores due to its flowing property. There are characteristics that cannot be

In the present invention, the physical properties can be complemented by copolymerization by mixing each of these polymers in an appropriate ratio, and excellent miscibility between polymers compared to other polymerization ratios allows fine phase separation to occur well and provides a path for efficient gas permeation can do. In addition, in the polymer having an ethylene glycol group, the ethylene glycol group is one of the representative Lewis base groups, and may form a selective gas permeation path through acid-base interaction with _{CO 2 which is a Lewis acid.} Accordingly, it is possible _{to increase the solubility of CO 2} , thereby increasing the transmittance and selectivity at the same time.

Specifically, the present invention provides a copolymer in which a second monomer having a polyalkylene oxide repeating unit is grafted onto a first monomer having an imidazole group.

The first monomer may have a polymerizable C═C bond and at the same time include an imidazole ring. Accordingly, the first monomer can form a complex with metal ions or can be variously modified as an ionic liquid, is friendly with a gas such as carbon dioxide, and has low flexibility and hardness, thereby improving the mechanical rigidity of the polymer membrane. Preferably, the first monomer has an imidazole group and may be a compound represented by the following formula (1).

[Formula 1]

(In Formula 1, n is an integer of 0 to 30.)

More preferably, n in Formula 1 may be an integer of 0 to 10, and most preferably, when Formula 1 is 1-vinylimidazole, n is 0.

The second monomer may serve to increase the adhesiveness and flexibility of the polymer by being similar to rubber. In addition, since the second monomer has a polyalkylene oxide repeating unit such as polyethylene oxide or polypropylene oxide, it has excellent affinity with a gas such as carbon dioxide and can induce fast and efficient gas separation. Specifically, the alkylene oxide functional group may have high affinity by dipole-quadrupole interaction with carbon dioxide. In addition, since carbon dioxide is an electron acceptor that can accept electrons as Lewis acid, it can dissolve a partially negatively charged domain, so that it can have selective solubility in oxygen in the COC bond of the second monomer. have.

Preferably, the second monomer may be polyoxyethylene methacrylate (POEM) represented by the following Chemical Formula 2 having a polyalkylene oxide repeating unit.

[Formula 2]

(In Formula 2, R ₁ and R ₂ are the same as or different from each other, and are each independently selected from H, COOH, and an alkyl group having 1 to 20 carbon atoms, and m is an integer of 1 to 50.)

Preferably, in Formula 2, R ₁ and R ₂ may be the same as each other, and each independently an alkyl group having 1 to 20 carbon atoms. Most preferably, R ₁ and R ₂ may be the same as each other, and each independently CH ₄ , C ₂ H ₅ or C ₃ H ₇ . The polyoxyethylene methacrylate may implement high gas permeability compared to other second monomers.

In the copolymer, the first monomer and the second monomer are 22-40: 60-78 weight ratio, preferably 25-35: 65-75 weight ratio, more preferably 28-32: 68-72 most preferably 30 It can be polymerized in a weight ratio of :70. In particular, when the content of the second monomer is less than 60 weight ratio, gas permeability may decrease during polymerization, and macro-phase may occur. Conversely, if the content of the second monomer is greater than 78 weight ratio, the content of the first monomer may be relatively decreased, thereby reducing the mechanical rigidity and gas selectivity of the polymer film.

The copolymer may be a compound represented by the following formula (3).

[Formula 3]

(In Formula 3, R ₁ and R ₂ are the same as or different from each other, and are each independently selected from H, COOH and an alkyl group having 1 to 20 carbon atoms, and x and y are 65 to 85 as a polymerization molar ratio of each repeating unit: 15 to 35, n is an integer from 0 to 30, and m is an integer from 1 to 50.)

Preferably, in Formula 3, R ₁ and R ₂ are the same as each other, each independently an alkyl group having 1 to 8 carbon atoms, x and y are 71 to 82: 18 to 29 as a polymerization molar ratio of each repeating unit, and n may be an integer from 0 to 10, and m may be an integer from 3 to 15.

Most preferably, the copolymer may be a compound represented by the following Chemical Formula 3a.

[Formula 3a]

(In Formula 3a, x and y are 77-80: 20-23 as a polymerization molar ratio of each repeating unit.)

The copolymer may have a weight average molecular weight (Mw) of 5,000 to 100,000 g/mol, preferably 25,000 to 80,000 g/mol, more preferably 48,000 to 53,000 g/mol, and most preferably 50,000 g/mol. .

The copolymer to also show the first and second valid peak valid peak in FT-IR analysis results, the wavelength range of 1722 to 1724cm ^-1 and a wavelength range of 1098 to 1100 cm ^-1 of the as shown in Fig. 2, the ( The absorbance ratio of the first effective peak)/(the second effective peak) may be 0.2 to 0.3, preferably 0.22 to 0.27, and most preferably 0.24 to 0.26.

In particular, although not explicitly described in the following Examples or Comparative Examples, after preparing the copolymer according to the present invention and commercial polymers PEO (Polyethylene Oxide) and PEBAX (Polyether-block-amide) as a control, the type of solvent Solubility evaluation was performed according to the following.

As a result, it was confirmed that the copolymer of the present invention was completely dissolved in water, ethanol, and an ethanol/water (1:1 weight ratio) mixed solvent at room temperature (25° C.), respectively, and thus had very good water solubility.

On the other hand, in the case of the PEO (with a weight average molecular weight of 1,000,000 g/mol), solubility in water, ethanol, and an ethanol/water mixed solvent of 2% by weight or less, respectively, was shown at room temperature, indicating an unstable state. It was confirmed that the PEO was completely dissolved in an ethanol/water mixed solvent at a temperature of about 50 °C. In addition, the PEBAX was dissolved in water, ethanol, and an ethanol/water mixed solvent at a temperature of about 70° C., but showed a solubility of 20 wt% or less.

As described above, the copolymer is a copolymer grafted with a first monomer excellent in various modifications and mechanical rigidity and a second monomer excellent in affinity for a gas such as carbon dioxide. It has excellent mechanical rigidity, and can improve the separation performance of gas permeability and selectivity in a balanced way by increasing the solubility of carbon dioxide.

In addition, general copolymers are mostly soluble in organic solvents and not well soluble in water or alcohol, but the copolymer is well soluble in nontoxic water-soluble water or volatile alcohol-based solvents, so that it is easy for commercial use and has a low evaporation rate. It has the advantage of being fast and suitable for application to commercial membranes. In addition, since the co-polymer contains a first monomer having various modifying properties, it can be applied to various fields such as a complex combined with a metal ion, biomimetic or modification into an ionic liquid.

On the other hand, the present invention provides a polymer membrane comprising the copolymer.

The polymer membrane may be for an ionic electrolyte membrane, an ion exchange membrane, or a gas separation membrane, but is not limited thereto.

In addition, the present invention is a porous support; and the polymer membrane coated on one or both surfaces of the porous support.

The porous support is polysulfone, polyester sulfone, polymethyl methacrylate, polyethylene, polypropylene, polyoxymethylene, polyether ether ketone, polyethylene terephthalate, polyacrylonitrile, cellulose acetate, polyamide, polyimide, poly It may be at least one selected from the group consisting of amideimide, polyetherimide, polyvinylidene fluoride, polyvinyl alcohol, and polyarylate. Preferably, it may be at least one selected from the group consisting of polysulfone, polyester sulfone and polymethyl methacrylate, and most preferably polysulfone. The polysulfone has an advantage in that it has a very good gas permeability while being inexpensive compared to other porous supports.

The porous support may further include a surface coating layer having a surface coated with poly(1-trimethylsilyl-1-propyne). The surface coating layer is coated with a polymer having excellent gas permeability on the surface of the porous support, and the coating solution penetrates the pores of the porous support to prevent defects or empty spaces.

The polymer film may have a thickness of 1 to 20 μm, preferably 3 to 15 μm, more preferably 4 to 12 μm, and most preferably 5 to 10 μm. At this time, if the thickness of the polymer membrane is less than 1 μm, the gas separation performance of the polymer membrane is excellent, but mechanical rigidity may be reduced. .

The gas may be at least one selected from carbon dioxide, nitrogen, and methane, preferably carbon dioxide.

The gas separation membrane may have a carbon dioxide (CO ₂ ) permeability of 148 barrer or more, a carbon dioxide/nitrogen (CO ₂ /N ₂ ) selectivity of 43 or more, and a carbon dioxide/methane (CO ₂ /CH ₄ ) selectivity of 23 or more. . Preferably, the carbon dioxide (CO ₂ ) transmittance is 148 barrer or more, the carbon dioxide/nitrogen (CO ₂ /N ₂ ) selectivity is 65 or more, and the carbon dioxide/methane (CO ₂ /CH ₄ ) selectivity is 35 or more.

The gas separation membrane can increase the solubility of carbon dioxide by applying a polymer membrane including both imidazoling and ethylene glycol, which is friendly to carbon dioxide, thereby increasing selectivity. The polymer membrane may induce micro-phase separation of a size of 20 to 40 nm due to different chemical properties by mixing the first monomer and the second monomer in an appropriate ratio. In the microphase separation, gases such as carbon dioxide form a permeation path to separate gases more quickly and efficiently.

In addition, the present invention provides a method for preparing a copolymer comprising: preparing a copolymer by polymerizing a first monomer having an imidazole group and a second monomer having a polyalkylene oxide repeating unit in the presence of an initiator .

In the step of preparing the copolymer, the first monomer and the second monomer are 22-40: 60-78 weight ratio, preferably 25-35: 65-75 weight ratio, more preferably 28-32: 68-72 weight ratio , most preferably in a weight ratio of 30:70.

The initiator may be mixed in an amount of 0.01 to 1 parts by weight, preferably 0.03 to 0.5 parts by weight, and most preferably 0.05 parts by weight based on 100 parts by weight of the mixed solution of the first monomer and the second monomer. In this case, if the content of the initiator is less than 0.01 part by weight, radical polymerization may not occur properly, and if it exceeds 1 part by weight, gas separation performance and mechanical properties may be deteriorated due to excessive radical polymerization.

The initiator may be at least one selected from the group consisting of azobisisobutyronitrile (AIBN), ammonium persulfate and hydroperoxide, and preferably azobisisobutyronitrile may be used. have.

The step of preparing the copolymer may be a free radical reaction at 50 to 100 °C for 10 to 30 hours. Preferably, the reaction may be carried out at 60 to 80 °C for 11 to 26 hours, more preferably at 60 to 75 °C for 12 to 24 hours, and most preferably at 70 °C for 18 hours. At this time, if the polymerization temperature is less than 50 ℃ or the polymerization time is less than 10 hours, the free radical polymerization reaction may not occur properly. chemical and physical properties may be degraded.

In particular, although not explicitly described in the following Examples or Comparative Examples, in the method for preparing the copolymer according to the present invention, the mixing ratio of the first monomer and the second monomer, the content and type of the initiator, and the polymerization step carbon dioxide for 100 hours to a copolymer produced by varying the temperature and time conditions at from 10 ~ 40 psig pressure conditions, after applying to the gas separation membrane (CO ₂₎ permeability, carbon dioxide / nitrogen (CO ₂ / N ₂₎ selectivity, and carbon dioxide /methane (CO ₂ /CH ₄ ) selectivity was evaluated.

As a result, it was confirmed that the excellent gas separation performance (permeability and selectivity) was maintained for a long time in all pressure ranges, unlike the conventional membrane, when all of the following conditions were satisfied, unlike other conditions and other numerical ranges.

① In the step of preparing the copolymer, the first monomer and the second monomer are mixed in a weight ratio of 28 to 32: 68 to 72, and ② the initiator is 0.03 parts by weight based on 100 parts by weight of a mixed solution of the first monomer and the second monomer. to 0.5 parts by weight, ③ the initiator is azobisobutyronitrile, ④ preparing the copolymer may be a free radical reaction at 60 to 75 ° C. for 12 to 24 hours.

However, when any one of the above four conditions was not satisfied, the gas separation performance was abruptly deteriorated as the pressure increased, and the gas separation performance did not last for a long time.

In addition, the present invention comprises the steps of preparing a copolymer by polymerizing a first monomer having an imidazole group and a second monomer having a polyalkylene oxide repeating unit in the presence of an initiator; dissolving the copolymer in a solvent to prepare a coating solution; forming a polymer film by coating the coating solution on one or both surfaces of the porous support; and drying the porous support on which the polymer membrane is formed to prepare a gas separation membrane.

The porous support may further include a surface coating layer having a surface coated with poly(1-trimethylsilyl-1-propyne).

In the step of preparing the coating solution, the content of the copolymer in the coating solution may be 10 to 30% by weight, preferably 13 to 25% by weight, and most preferably 15 to 20% by weight.

The solvent may be at least one selected from the group consisting of water, methanol, ethanol, propanol, butanol, isopropanol, tetrahydrofuran, ethyl acetate, chloroform, dimethyl sulfoxide, dimethylformamide and N-methyl-2-pyrrolidone. have. Preferably, the solvent may be water, ethanol, or a mixture thereof, and most preferably, a mixed solvent in which ethanol and water are mixed in a 7:3 weight ratio.

The forming of the polymer film may include primary drying at room temperature for 10 to 15 hours and then secondary drying in a vacuum oven for 4 to 8 hours. Preferably, after primary drying at room temperature for 11 to 13 hours, secondary drying may be performed in a vacuum oven for 5 to 7 hours.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by the following examples.

Examples 1-2 and Comparative Examples 1-6: PVIm, PVIm-POEM copolymer and PPOEM polymer synthesis

[Scheme 1]

(In Scheme 1, x is 78.7, and y is 21.3.)

In 100 ml of ethanol, a total of 10 g was mixed with VIm (1-vinylimidazole) and POEM (poly(oxyethylene methacrylate) in different weight ratios, respectively, as shown in Table 1. The initiator was 0.05 g of DMF (Dimethylformamide) in 5 ml. AIBN (Azobisisobutyronitrile) was dissolved. Then, 0.05 parts by weight of AIBN initiator was mixed with 100 parts by weight of the mixed solution. Then, the mixture was purged with nitrogen gas, and then free radical polymerization at 70 ° C. for 18 hours ( After the polymerization, the reactant was precipitated in a mixed solvent of hexane/ethyl acetate (hexane:ethyl acetate = 2:1 by weight), stirred and washed three times while replacing the mixed solvent. The washed reactant was first dried at room temperature for 48 hours and then dried in a vacuum oven for 24 hours to synthesize a PVIm-POEM copolymer.

Examples 3 to 4 and Comparative Examples 7 to 12: Preparation of gas separation membrane

A surface coating layer is formed by coating a PTMSP (poly[1-(trimethylsilyl)-1-propyne]) solution diluted in a cyclohexane solvent to a concentration of 1.5 wt% on the surface of a porous polysulfone support by a bar coating method. did. Then, the PVIm, PVIm-POEM copolymer and PPOEM polymer prepared in Examples 1 to 2 and Comparative Examples 7 to 12 were dissolved in an ethanol/water (7:3 weight ratio) mixed solvent, respectively, and 15 to 20% by weight relative to the mass. A coating solution was prepared so as to have a concentration. Then, the coating solution was coated on the PTMSP-coated porous polysulfone support by a bar coating method, dried first at room temperature for 12 hours, and then dried in a vacuum oven for about 6 hours, and then dried on the porous polysulfone support for 5~ A gas separation membrane in which a polymer membrane having a thickness of 10 μm was formed was prepared.

Experimental Example 1: Form of PVIm-POEM copolymer, FT-IR and H-NMR analysis

The structures of PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6 were analyzed using FT-IR and H-NMR spectroscopic analysis. The results are shown in FIGS. 1 to 3 and Table 2.

1 is a photograph showing the synthesis results of PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6; Referring to FIG. 1 , as the ratio of PVIm increased, a harder and brittle polymer was formed, and as the ratio of POEM increased, a soft and sticky polymer was formed. In addition, it was confirmed that the PPOEM of Comparative Example 6 made of only POEM had flow properties similar to that of a liquid.

2 is a graph showing the FT-IR (a) and H-NMR (b, c, d) analysis results of VIm, POEM and the PVIm-POEM copolymer synthesized in Examples 2 and 3 and Comparative Examples 2 and 3.

3 is a graph showing FT-IR results of PVIm and PVIm-POEM copolymers synthesized in Example 1 and Comparative Examples 1, 4, and 5;

Referring to FIG. 2(a) and FIG. 3, after the synthesis of the PVIm-POEM copolymer, the C=C band observed at the ^{wavenumbers 1646 and 1637 cm −1 of the existing VIm and POEM of the copolymer is} It was confirmed that it disappeared with polymerization. In addition, as the amount of PVIm increased, the relative intensity increased in the wavy regions of ^{1226, 1106, and 1078 cm -1} corresponding to CN bonds, which are typical bonds of imidazoling. In addition, as the amount of POEM increased, it was confirmed that the relative strength of the repeated CO bonds at ^{1099 cm -1 increased. In addition, the 1717 cm -1} stretching band in which the C=O bond, which is a representative bond of POEM, moved to a lower wavenumber region as the weight ratio of PVIm increased, which is the case of the C=O bond according to Hooke's law. It means that the age has weakened. That is, it was confirmed that the imidazole functional group of PVIm interacts with the C=O bond of POEM.

In addition, referring to (b), (c), and (d) of FIG. 2, as a result of analyzing the protons of PVIm-POEM73(b), PVIm-POEM55(c), and PVIm-POEM37(d), representative of PVIm A proton of an imidazole ring, which is a functional group, was observed in all three polymers, and a methyl group (-CH ₃ ) of POEM was observed.

In Table 1, the area was calculated by integrating the representative peak of FIG. 2, and the actually synthesized molar ratio and integral ratio were calculated using this. As the synthesis ratio of POEM increased, the POEM ratio of the actual PVIm-POEM increased, and the amount of POEM slightly decreased than the weight ratio used for the actual synthesis. It can be seen that this is due to the lower polymerization rate due to steric hindrance during synthesis because POEM has a larger molecular size than VIm.

Experimental Example 2: DSC, TGA analysis of PVIm-POEM copolymer

Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) were performed on the PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6 did. The results are shown in Figures 4, 5 and Table 3.

4 is a graph showing DSC results for PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6; 4, in the PPOEM of Comparative Example 6, which is a very rubbery polymer, a glass transition temperature (T _g , glass transition temperature) was observed at -58.2 ° C., through which the PPOEM of Comparative Example 6 It was found that silver was very sticky and had high fluidity at room temperature.

In the case of PVIm of Comparative Example 1, it is a very glassy polymer at room temperature, and since its physical properties are excellent, T _g was observed at 173.1 °C. In the case of Examples 1 to 2 and Comparative Examples 2 to 5, it was confirmed that as the content of PVIm increased, the T _g corresponding to POEM also increased. It was found that this was because the hard PVIm interacted with the POEM monomer. Through this, it was confirmed through the DSC result that it is important to improve the physical stability because too much fluidity of the polymer during the manufacture of the gas separation membrane is rather detrimental to the manufacture and stability of the membrane.

5 is a graph showing TGA results for PVIm, PVIm-POEM copolymer and PPOEM polymer synthesized in Examples 1 to 2 and Comparative Examples 1 to 6; Referring to FIG. 5 , as a result of analyzing the temperature-dependent behavior of the polymer through TGA analysis, the organic material decomposed at about 100 to 200° C. is water strongly bound to the polymer, and the PVIm of Comparative Example 1 is about 400 degrees Celsius. ℃, it was confirmed that the PPOEM of Comparative Example 6 starts to decompose at about 230 °C. Through this, PVIm of Comparative Example 1, which is a glassy polymer having an imidazoling group, has excellent thermal stability due to its very hard physical properties, whereas PPOEM of Comparative Example 6, which consists mostly of ethylene glycol groups, is 200 It was found that the COC bond was broken at ℃ and rapidly decomposed. In addition, in the case of Examples 1 and 2, it was confirmed that the thermal stability exhibited intermediate stability.

Table 3 is the result of confirming the relative decomposition numerically with respect to the TGA result. As a result of calculating the mass ratio of the polymer and the polymer (PVIm monomer) remaining at 400 ° C after all the water has evaporated, the ratio of PVIm is in the polymerization ratio. It can be seen that the change is almost proportional. Through this, it can be seen that PVIm has superior thermal stability compared to PPOEM, and polymerization was successfully performed for the PVIm-POEM copolymers of Examples 1 and 2 and Comparative Examples 2-5.

Experimental Example 3: SAXS and XRD analysis of gas separation membrane

With respect to the gas separation membranes prepared in Example 4 (PVIm-POEM37) and Comparative Examples 8 (PVIm-POEM73), 9 (PVIm-POEM55), and 12 (PPOEM), the distance between molecular chains or monomer, which is a very important element of the gas separation membrane In order to analyze the distance between them, small-angle x-ray scattering (SAXS) and X-ray diffraction (XRD) analysis were performed. The SAXS analysis may determine the distance between the polymer domains, and the XRD may analyze the distance between the polymer chains. The results are shown in FIG. 6 .

6 is a SAXS analysis (a) and XRD analysis (b) of the gas separation membranes prepared in Example 4 (PVIm-POEM37) and Comparative Examples 8 (PVIm-POEM73), 9 (PVIm-POEM55), and 12 (PPOEM). ) is a graph showing the results. Referring to (a) of FIG. 6 , in the case of Comparative Example 12 (PPOEM polymer), no peak was observed because it was composed of only a single POEM monomer. On the other hand, in the case of Example 4 and Comparative Examples 8 and 9, a peak was observed due to phase separation between VIm and POEM, and the value of q increased as the content of POEM increased. According to the Bragg equation (q = 2π/d), the d-spacing value between monomers gradually decreased, indicating that the distance between the POEM monomers decreased according to the relatively decreased amount of PVIm. could

In addition, referring to FIG. 6(b), as the amount of POEM increased, the d-spacing value increased, which is the imidazolyling of PVIm between the POEM chains by the following equation (nλ = 2d sinθ). Through this interaction, it was found that the gap was narrowed.

Experimental Example 4: TEM and FE-SEM analysis of gas separation membrane

For the gas separation membranes prepared in Example 4 (PVIm-POEM37) and Comparative Examples 8 (PVIm-POEM73) and 9 (PVIm-POEM55), the phase and behavior of the polymer membrane were visually confirmed using TEM. In addition, the gas separation membranes prepared in Examples 3 to 4 and Comparative Examples 7 to 12 were cut in cross section in liquid nitrogen to confirm the shape using FE-SEM. The results are shown in FIGS. 7 to 9 .

7 shows the gas separation membranes prepared in Example 4 (PVIm-POEM37) (e, f) and Comparative Examples 8 (PVIm-POEM73) (a, b), 9 (PVIm-POEM55) (c, d). This is a TEM picture. Referring to FIG. 7, in the case of Comparative Example 8 (PVIm-POEM73) (a, b) and Comparative Example 9 (PVIm-POEM55) (c, d), a macrophase separation of about 300 to 350 nm was the majority. This large phase separation is mainly the result of poor polymer miscibility or weak interaction.

On the other hand, in the case of Example 4 (PVIm-POEM37) (e, f), it was confirmed that macrophase separation was hardly observed, and rather aligned microphase separation of about 20 to 40 nm was predominant. . This behavior is very similar to the result of SAXS, and it was found that a better pathway was formed through microphase separation even in _{CO 2 permeation.}

FIG. 8 shows a comparison of phase separation of the gas separation membranes prepared in Example 4 (PVIm-POEM37) and Comparative Example 8 (PVIm-POEM73). Referring to FIG. 8, in the case of Comparative Example 8 (PVIm-POEM73), the polymer miscibility and interaction between PVIm and POEM is not good, so macrophase separation occurs, gas permeation is not easy, and a defective site is show what exists On the other hand, Example 4 (PVIm-POEM37) shows that excellent polymer miscibility between PVIm and POEM provides a pathway for easy gas permeation while microphase separation occurs.

9 is a FE-SEM photograph of a cross section of the gas separation membranes prepared in Examples 3 to 4 and Comparative Examples 7 to 12. Referring to FIG. 9 , each gas separation membrane is coated with a polymer membrane of PVIm, PVIm-POEM copolymer, and PPOEM polymer having a diameter of 2 to 10 μm, and no cracks or flaws were observed with the naked eye. The lower part of the FE-SEM photo showed a porous polysulfone support with high permeability and good physical strength.

Experimental Example 5: Gas Permeability and Selectivity Analysis of Gas Separation Membrane

For the gas separation membranes prepared in Examples 3 to 4 and Comparative Examples 7 to 12, the separation performance of gas permeability and selectivity was checked using a gas permeation device and a flow meter. The results are shown in Table 4 and FIGS. 10 to 11 .

_{10 is a graph showing the permeability of carbon dioxide (CO 2} ), carbon dioxide/nitrogen (CO ₂ /N ₂ ) and carbon dioxide/methane (CO ₂ /CH ₄ ) for the gas separation membranes prepared in Examples 3 to 4 and Comparative Examples 7 to 12; ) is a graph showing the selectivity results for

According to the results of FIG. 10 and Table 4, Comparative Example 7 showed the highest permeability to carbon dioxide, nitrogen and methane, but exhibited relatively low selectivity. In addition, in the case of Examples 3 to 4 and Comparative Examples 8 to 12, it was confirmed that the gas permeability and selectivity were improved as the content of POEM increased. It was found that as the content of POEM increased, the gas permeability improved as PVIm and POEM, which have different physical properties, complement each other well, and the gas selectivity was improved with the increase of POEM with carbon dioxide affinity.

In particular, in the case of Examples 3 and 4, it was confirmed that the gas permeability and selectivity were uniformly superior to those of Comparative Examples 7 to 12. Among them, in the case of Example 4 (PVIm-POEM37), CO ₂ permeability was about 148.6 barrer, CO ₂ /N ₂ selectivity 65.3, CO ₂ /CH ₄ selectivity 35.0, the highest gas permeability and selectivity performance was shown.

11 is a flat membrane made of different polymers and gas permeability and selectivity for the gas separation membranes prepared in Example 4 (PVIm-POEM37), Comparative Example 8 (PVIm-POEM73), and Comparative Example 9 (PVIm-POEM55). This is a graph comparing the separation performance. Referring to FIG. 11, in the case of Example 4 (PVIm-POEM37), compared to Comparative Examples 8 and 9 and other flat membranes, the performance nearly approached Robeson upper bound (2008), thereby separating gas permeability and selectivity It was found that the performance was very good.

Claims (22)

A copolymer in which a second monomer having a polyalkylene oxide repeating unit is grafted onto a first monomer having an imidazole group.
According to claim 1,
The first monomer is a copolymer of a compound represented by the following formula (1).
[Formula 1]

(In Formula 1, n is an integer of 0 to 30.)
According to claim 1,
The second monomer is a copolymer of polyoxyethylene methacrylate represented by the following formula (2).
[Formula 2]

(In Formula 2,
R ₁ and R ₂ are the same as or different from each other, and are each independently selected from H, COOH and an alkyl group having 1 to 20 carbon atoms;
m is an integer from 1 to 50.)
According to claim 1,
The copolymer is a copolymer in which the first monomer and the second monomer are polymerized in a weight ratio of 22 to 40: 60 to 78.
According to claim 1,
The copolymer is a copolymer that is a compound represented by the following formula (3).
[Formula 3]

(In Formula 3,
R ₁ and R ₂ are the same as or different from each other, and are each independently selected from H, COOH and an alkyl group having 1 to 20 carbon atoms;
x and y are 65-85: 15-35 as a polymerization molar ratio of each repeating unit,
n is an integer from 0 to 30,
m is an integer from 1 to 50.)
According to claim 1,
In Formula 3,
R ₁ and R ₂ are the same as each other and are each independently an alkyl group having 1 to 8 carbon atoms,
x and y are 71 to 82: 18 to 29 as a polymerization molar ratio of each repeating unit,
n is an integer from 0 to 10,
m is an integer from 3 to 15, the copolymer.
According to claim 1,
The copolymer is a copolymer that is a compound represented by the following formula (3a).
[Formula 3a]

(In Formula 3a,
x and y are 77-80: 20-23 as a polymerization molar ratio of each repeating unit.)
A polymer film comprising the copolymer of claim 1.
9. The method of claim 8,
The polymer membrane is a polymer membrane for an ionic electrolyte membrane, for an ion exchange membrane, or for a gas separation membrane.
porous support; and
A gas separation membrane comprising a; the polymer membrane according to claim 8 coated on one or both sides of the porous support.
11. The method of claim 10,
The porous support is polysulfone, polyester sulfone, polymethyl methacrylate, polyethylene, polypropylene, polyoxymethylene, polyether ether ketone, polyethylene terephthalate, polyacrylonitrile, cellulose acetate, polyamide, polyimide, poly A gas separation membrane that is at least one selected from the group consisting of amideimide, polyetherimide, polyvinylidene fluoride, polyvinyl alcohol, and polyarylate.
11. The method of claim 10,
The porous support is a gas separation membrane that further comprises a surface coating layer having a surface coated with poly (1-trimethylsilyl-1-propyne).
11. The method of claim 10,
The polymer membrane is a gas separation membrane having a thickness of 1 to 20 μm.
11. The method of claim 10,
The gas is a gas separation membrane that is at least one selected from carbon dioxide, nitrogen and methane.
11. The method of claim 10,
The gas separation membrane is a gas separation membrane that forms a gas permeation passage through microphase separation of a size of 20 to 40 nm.
11. The method of claim 10,
The gas separation membrane has a carbon dioxide (CO ₂ ) permeability of 148 barrer or more, a carbon dioxide/nitrogen (CO ₂ /N ₂ ) selectivity of 43 or more, and a carbon dioxide/methane (CO ₂ /CH ₄ ) selectivity of 23 or more. gas separation membrane.
Preparing a copolymer by polymerizing a first monomer having an imidazole group and a second monomer having a polyalkylene oxide repeating unit in the presence of an initiator; Method for producing a copolymer comprising a.
18. The method of claim 17,
The step of preparing the copolymer is a method for producing a copolymer by polymerizing the first monomer and the second monomer in a weight ratio of 22 to 40: 60 to 78.
18. The method of claim 17,
The step of preparing the copolymer is a method for producing a copolymer that is a free radical reaction for 10 to 30 hours at 50 ~ 100 ℃.
preparing a copolymer by polymerizing a first monomer having an imidazole group and a second monomer having a polyalkylene oxide repeating unit in the presence of an initiator;
dissolving the copolymer in a solvent to prepare a coating solution;
forming a polymer film by coating the coating solution on one or both surfaces of the porous support; and
manufacturing a gas separation membrane by drying the porous support on which the polymer membrane is formed;
A method of manufacturing a gas separation membrane comprising a.
21. The method of claim 20,
In the step of preparing the coating solution, the copolymer of the total content of the coating solution is 10 to 30% by weight of the method for producing a gas separation membrane.
21. The method of claim 20,
The solvent is at least one selected from the group consisting of water, methanol, ethanol, propanol, butanol, isopropanol, tetrahydrofuran, ethyl acetate, chloroform, dimethyl sulfoxide, dimethylformamide and N-methyl-2-pyrrolidone A method for manufacturing a phosphorus gas separation membrane.

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