G-c3n4 polymer and method for producing same

Abstract

The present invention relates to a g-C3N4 polymer containing a graphitic carbon nitride repeating unit represented by chemical formula 1. The polymer can achieve excellent thermal and chemical stability, electrical properties, visible light absorption, porous structure, and ease of production of graphitic carbon nitride, and can have excellent water solubility and excellent solubility in organic solvents. [Chemical formula 1] In chemical formula 1, R1, L1, and ring A are as described in the specification.

Description

G-C3N4 polymer and method for manufacturing the same

[0001] The present disclosure relates to a g-C3N4 polymer containing graphitic carbon nitride and a method for manufacturing the same.

[0002] Graphitic carbon nitride (g-C3N4) is a material in which nitrogen and carbon atoms are bonded to form two-dimensional sheets, and similar to graphite, these two-dimensional sheets form a layered structure. Due to advantages such as excellent thermal and chemical stability, electrical properties, visible light absorption, porous structure, low cost, and easy accessibility, graphitic carbon nitride is gaining attention as a next-generation material in various industrial fields, including photocatalysts, semiconductors, and energy storage materials.

[0003] However, bulk g-C3N4 has fundamental limitations, such as very low solubility and dispersibility due to strong hydrogen bonding and stacking behavior, which makes it difficult to expand its application fields. Although various studies have been proposed to address these issues, the effect of improving solubility is insufficient, and even if solubility is improved somewhat, there are limitations such as deterioration of physical properties like thermal and chemical stability and electrical characteristics, or increased complexity in the synthesis process.

[0004] One aspect of the present invention provides a g-C3N4 polymer and a method for manufacturing the same, which secures excellent physical properties of graphitic carbon nitride while significantly improving water solubility and solubility in organic solvents.

[0005] One embodiment of the present invention provides a g-C3N4 polymer comprising a graphitic carbon nitride repeating unit represented by the following chemical formula 1.

[0006] [Chemical Formula 1]

[0007]

[0008] (In the above chemical formula 1,

[0009] The A ring is substituted or unsubstituted graphitic carbon nitride (g-C3N4);

[0010] L 1 is a divalent organic group;

[0011] R 1 It is hydrogen or (C1-C4)alkyl.

[0012] According to one embodiment, the g-C3N4 polymer may further comprise a hydrophilic repeating unit in which a hydrophilic group is bonded as a side chain.

[0013] The above hydrophilic group may be a hydroxyl group, an amino group, an ammonium group, an amide group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphonic acid group or a salt thereof, a cyano group, a tri(C1-C4)alkoxysilane, a morpholine group, a pyrrolidone group, a polyoxy(C1-C4)alkylene group, or a combination thereof.

[0014] The above hydrophilic repeating unit may be represented by the following chemical formula 2.

[0015] [Chemical Formula 2]

[0016]

[0017] (In the above chemical formula 2,

[0018] X is a hydroxyl group, amino group, ammonium group, amide group, carboxyl group or a salt thereof, sulfonic acid group or a salt thereof, phosphonic acid group or a salt thereof, cyano group, tri(C1-C4)alkoxysilane, morpholine group, pyrrolidone group, or And;

[0019] L 2 is a divalent organic group;

[0020] L 3 is a C1-C4 alkylene;

[0021] n is an integer from 2 to 100;

[0022] R 2 and R 3 Each is independently hydrogen or C1-C4 alkyl.)

[0023] The above graphitic carbon nitride repeating unit may contain 0.1 to 50 moles of hydrophilic repeating units for every 1 mole of graphitic carbon nitride repeating unit.

[0024] The graphitic carbon nitride mentioned above may be triazine-based carbon nitride or heptazine-based carbon nitride.

[0025] The above L 1 It may be a single bond, (C1-C4)alkylene, -C(=O)-, -NH-, (C6-C12)arylene, or a combination thereof.

[0026] The above L 2 It can be a single bond, (C1-C4)alkylene, or (C6-C12)arylene.

[0027] Another aspect of the present invention provides a method for producing a g-C3N4 polymer, comprising: a step of radically polymerizing a monomer solution containing a radically polymerizable nitrogen-providing precursor represented by the following formula 11 to produce a carbon nitride precursor polymer containing repeating units represented by the following formula 12; and a step of performing a hydrothermal or solvothermal reaction between the carbon nitride precursor polymer and urea to produce a g-C3N4 polymer containing graphitic carbon nitride repeating units represented by the following formula 1.

[0028] [Chemical Formula 11]

[0029]

[0030] [Chemical Formula 12]

[0031]

[0032] [Chemical Formula 1]

[0033]

[0034] (In the above chemical formulas 1, 11 and 12,

[0035] A 1 is a cyano group or an amide group;

[0036] The A ring is graphitic carbon nitride (g-C3N4);

[0037] L 1 is a divalent organic group;

[0038] R 1 It is hydrogen or (C1-C4)alkyl.

[0039] The above monomer solution may further include a radical polymerizable comonomer containing a hydrophilic group.

[0040] The above g-C3N4 polymer may further include a repeating unit represented by the above chemical formula 12.

[0041] Another aspect of the present invention provides a method for producing a g-C3N4 polymer, comprising: a step of producing a radical polymerizable carbon nitride monomer represented by the following formula 13 by performing a hydrothermal or solvothermal reaction between a radical polymerizable nitrogen-giving precursor represented by the following formula 11 and urea; and a step of producing a g-C3N4 polymer comprising graphitic carbon nitride repeating units represented by the following formula 1 by radical polymerizing a monomer solution containing the radical polymerizable carbon nitride monomer.

[0042] [Chemical Formula 11]

[0043]

[0044] [Chemical Formula 13]

[0045]

[0046] [Chemical Formula 1]

[0047]

[0048] (In the above chemical formulas 1, 11 and 13,

[0049] A 1 is a cyano group or an amide group;

[0050] The A ring is graphitic carbon nitride (g-C3N4);

[0051] L 1 is a divalent organic group;

[0052] R 1 It is hydrogen or (C1-C4)alkyl.

[0053] The above monomer solution may further include a radical polymerizable comonomer containing a hydrophilic group.

[0054] The g-C3N4 polymer according to one embodiment can secure the excellent thermal and chemical stability, electrical properties, visible light absorption, porous structure, and ease of manufacturing of conventional graphitic carbon nitride, and exhibits excellent water solubility and solubility in organic solvents. Furthermore, the g-C3N4 polymer according to one embodiment allows for easy control of functional groups and composition, enabling the physical properties and functionality of the polymer to be adjusted according to the application, and can be applied to various uses such as carbon nanomaterial dispersants, secondary battery materials, and catalysts.

[0055] Figure 1 is a TEM measurement image of the g-C3N4 polymer prepared in Example 1.

[0056] Figure 2 is a fluorescence image of the powder of the g-C3N4 polymer prepared in Example 6 and the DMSO solution.

[0057] Unless otherwise defined in this specification, all technical and scientific terms have the same meaning as generally understood by those skilled in the art to which the present invention pertains. The terms used in the description herein are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention.

[0058] The singular form used in this specification is intended to include the plural form unless specifically indicated otherwise in the context.

[0059] Throughout this specification, the terms “comprising,” “having,” “containing,” or “having” any component mean that, unless specifically stated otherwise, other components are not excluded but may be included, and do not exclude elements, materials, or processes not additionally listed.

[0060] The numerical ranges used herein include lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of which are limited, and all possible combinations of upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in this specification, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0061] Unless otherwise specifically defined in this specification, “about” may be considered to be a value within 30%, 25%, 20%, 15%, 10%, or 5% of the specified value.

[0062] The present disclosure will be described in detail below. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively.

[0063] One embodiment of the present invention provides a g-C3N4 polymer comprising a graphitic carbon nitride (g-C3N4) repeating unit. Specifically, the g-C3N4 polymer according to one embodiment may comprise a repeating unit in which a graphitic carbon nitride unit is bonded as a side chain, and specifically, may comprise a graphitic carbon nitride repeating unit represented by the following chemical formula 1.

[0064] [Chemical Formula 1]

[0065]

[0066] (In the above chemical formula 1,

[0067] The A ring is substituted or unsubstituted graphitic carbon nitride (g-C3N4);

[0068] L 1 is a divalent organic group;

[0069] R 1 It is hydrogen or (C1-C4)alkyl.

[0070] According to one embodiment, the g-C3N4 polymer includes repeating units in which graphitic carbon nitride units are bonded as side chains as described above, and additional repeating units having appropriate functional groups can be introduced depending on the purpose, and since the control of functional groups and composition is easy, the physical properties and functionality of the g-C3N4 polymer can be adjusted according to the application.

[0071] For example, in the above-mentioned substituted graphitic carbon nitride, the substituent may include a hydrophilic group.

[0072] For example, according to one embodiment, the g-C3N4 polymer may further comprise a hydrophilic repeating unit in which a hydrophilic group is bonded as a side chain.

[0073] The above hydrophilic group is, for example, a hydroxyl group (-OH), an amino group (-NH2), or an ammonium group (-NH3 + ), amide group (-CONH2), carboxyl group (-COOH) or a salt thereof, sulfonic acid group (-SO3H) or a salt thereof, phosphonic acid group (-PO3H2) or a salt thereof, cyano group, tri(C1-C4)alkoxysilane, morpholine group, pyrrolidone group, polyoxy(C1-C4)alkylene group or a combination thereof, may be, but is not limited thereto.

[0074] For example, the above hydrophilic repeating unit may be represented by the following chemical formula 2.

[0075] [Chemical Formula 2]

[0076]

[0077] (In the above chemical formula 2,

[0078] X is a hydroxyl group (-OH), an amino group (-NH2), or an ammonium group (-NH3 + ), amide group (-CONH2), carboxyl group (-COOH) or a salt thereof, sulfonic acid group (-SO3H) or a salt thereof, phosphonic acid group (-PO3H2) or a salt thereof, cyano group, tri(C1-C4)alkoxysilane, morpholine group, pyrrolidone group, or And;

[0079] L 2 is a divalent organic group;

[0080] L 3 is a C1-C4 alkylene;

[0081] R 2 and R 3 Each is independently hydrogen or (C1-C4)alkyl.

[0082] Specifically, according to one embodiment, the g-C3N4 polymer may comprise a graphitic carbon nitride repeating unit represented by the following chemical formula 1 and a hydrophilic repeating unit represented by the following chemical formula 2.

[0083] [Chemical Formula 1]

[0084]

[0085] [Chemical Formula 2]

[0086]

[0087] (In the above chemical formulas 1 and 2,

[0088] The A ring is substituted or unsubstituted graphitic carbon nitride (g-C3N4);

[0089] X is a hydroxyl group (-OH), an amino group (-NH2), or an ammonium group (-NH3 + ), amide group (-CONH2), carboxyl group (-COOH) or a salt thereof, sulfonic acid group (-SO3H) or a salt thereof, phosphonic acid group (-PO3H2) or a salt thereof, cyano group, tri(C1-C4)alkoxysilane, morpholine group, pyrrolidone group, or And;

[0090] L 1 and L 2 Each is independently a divalent organic group;

[0091] L 3 is a (C1-C4)alkylene;

[0092] n is an integer from 2 to 100;

[0093] R 1 Silver to R 3 Each is independently hydrogen or (C1-C4)alkyl.

[0094] For example, the graphitic carbon nitride of the above A ring may be triazine-based carbon nitride or heptazine-based carbon nitride.

[0095] For example, the triazine-based carbon nitride may include a structural unit represented by the following structural formula 1, and the heptazine-based carbon nitride may include a structural unit represented by the following structural formula 2, and each may be a two-dimensional sheet structure in which the corresponding structural unit is horizontally arranged in two dimensions.

[0096] [Structural Formula 1]

[0097]

[0098] [Structural Formula 2]

[0099]

[0100] For example, the above L 1 It may be a single bond, (C1-C4)alkylene, -C(=O)-, -NH-, (C6-C12)arylene, or a combination thereof.

[0101] For example, the above L 2 It can be a single bond, (C1-C4)alkylene or (C6-C12)arylene.

[0102] For example, the above R 1 to R 3 Each can independently be hydrogen or methyl.

[0103] For example, the above n may be an integer from 2 to 80, an integer from 2 to 60, an integer from 2 to 40, an integer from 2 to 30, an integer from 5 to 30, or an integer from 10 to 30.

[0104] Specifically, according to one embodiment, the g-C3N4 polymer may comprise a graphitic carbon nitride repeating unit represented by the following chemical formula 3 and a hydrophilic repeating unit represented by the following chemical formula 4.

[0105] [Chemical Formula 3]

[0106]

[0107] [Chemical Formula 4]

[0108]

[0109] (In the above chemical formulas 3 and 4,

[0110] R 1 , R 2 , ring A and X are as described above)

[0111] According to one embodiment, the g-C3N4 polymer may contain hydrophilic repeating units with respect to 1 mole of graphitic carbon nitride repeating unit in an amount of 0.1 mole or more, 1 mole or more, 5 mole or more, 10 mole or more, or 100 mole or less, 80 mole or less, 60 mole or less, or 50 mole or less, or 40 mole or less, or 30 mole or less, but is not limited thereto, and it goes without saying that this amount can be appropriately adjusted depending on the use of the g-C3N4 polymer.

[0112] The g-C3N4 polymer according to one embodiment can secure properties such as the excellent thermal and chemical stability, electrical properties, visible light absorption, and porous structure of conventional graphitic carbon nitride, while simultaneously exhibiting excellent water solubility and solubility in organic solvents. Accordingly, the g-C3N4 polymer according to one embodiment can overcome the limitations of conventional technology, which faced difficulties in expanding application fields due to very low solubility and dispersibility despite its excellent physical properties. It is expected to be applicable not only as a photocatalyst, semiconductor, and energy storage material, but also as a carbon nanomaterial dispersant, and to various other industrial fields.

[0113] Hereinafter, a method for manufacturing a g-C3N4 polymer according to one embodiment is described.

[0114] A first embodiment of a method for preparing a g-C3N4 polymer according to one embodiment may comprise: a step of radically polymerizing a monomer solution containing a radically polymerizable nitrogen-giving precursor represented by the following chemical formula 11 to produce a carbon nitride precursor polymer containing repeating units represented by the following chemical formula 12; and a step of performing a hydrothermal or solvothermal reaction between the carbon nitride precursor polymer and urea to produce a g-C3N4 polymer containing graphitic carbon nitride repeating units represented by the following chemical formula 1.

[0115] [Chemical Formula 11]

[0116]

[0117] [Chemical Formula 12]

[0118]

[0119] [Chemical Formula 1]

[0120]

[0121] (In the above chemical formulas 1, 11 and 12,

[0122] A 1 is a cyano group or an amide group;

[0123] The A ring is graphitic carbon nitride (g-C3N4);

[0124] L 1 is a divalent organic group;

[0125] R 1 It is hydrogen or (C1-C4)alkyl.

[0126] The g-C3N4 polymer produced in the first embodiment of the above manufacturing method may further include repeating units represented by the above chemical formula 12.

[0127] A second embodiment of a method for producing a g-C3N4 polymer according to one embodiment may comprise: a step of producing a radically polymerizable carbon nitride monomer represented by the following formula 21 by performing a hydrothermal or solvothermal reaction between a radically polymerizable nitrogen-giving precursor represented by the following formula 11 and urea; and a step of producing a g-C3N4 polymer comprising graphitic carbon nitride repeating units represented by the following formula 1 by radically polymerizing a monomer solution containing the radically polymerizable carbon nitride monomer.

[0128] [Chemical Formula 11]

[0129]

[0130] [Chemical Formula 13]

[0131]

[0132] [Chemical Formula 1]

[0133]

[0134] (In the above chemical formulas 1, 11 and 13,

[0135] A 1 is a cyano group or an amide group;

[0136] The A ring is graphitic carbon nitride (g-C3N4);

[0137] L 1is a divalent organic group;

[0138] R 1 It is hydrogen or (C1-C4)alkyl.

[0139] A first embodiment of the method for manufacturing the g-C3N4 polymer can be represented by Formula 1 below, and a second embodiment of the method for manufacturing the g-C3N4 polymer can be represented by Formula 2 below.

[0140] [Equation 1]

[0141]

[0142] [Equation 2]

[0143]

[0144] For example, the radical polymerization described above can be used without limitation as long as it is a method commonly used in the relevant technical field, and as a non-limiting example, it can be performed at 50 to 100°C or 50 to 80°C for 1 to 10 hours or 1 to 5 hours, and can be performed including a thermal initiator or a photoinitiator.

[0145] For example, the hydrothermal and solvothermal reactions of the above elements may be used without limitation as long as they are methods commonly used in the relevant technical field, and as a non-limiting example, they may be performed at 100 to 300 ℃, or 150 to 300 ℃, or 150 to 200 ℃ for 1 to 10 hours, or 3 to 10 hours, and may be performed in a high-pressure reactor.

[0146] For example, the monomer solution of the above manufacturing method may further include a radical polymerizable comonomer having an appropriate functional group depending on the purpose, and accordingly, the g-C3N4 polymer according to one embodiment allows for easy control of the functional group and composition, thereby enabling the physical properties and functionality of the g-C3N4 polymer to be adjusted according to the application.

[0147] For example, in the first and second embodiments above, the monomer solution may further comprise a radical polymerizable comonomer comprising a hydrophilic group, and the radical polymerizable comonomer comprising a hydrophilic group may be represented by the following Chemical Formula 21. For example, in the manufacturing method above, if the monomer solution further comprises a radical polymerizable comonomer comprising a hydrophilic group represented by the above Chemical Formula 21, the g-C3N4 polymer produced may further comprise a repeating unit represented by the following Chemical Formula 2.

[0148] [Chemical Formula 21]

[0149]

[0150] [Chemical Formula 2]

[0151]

[0152] (In the above chemical formulas 2 and 21, R 2 , L 2 and X are as described above.)

[0153] For example, in the first and second embodiments above, the reaction may be carried out by further including melamine during the hydrothermal or solvothermal reaction of urea, and the graphitic carbon nitride (A ring) of the g-C3N4 polymer produced may further include melamine-derived units.

[0154] For example, in the first and second embodiments above, the reaction may be carried out by further including a hydrophilic group-providing compound during the hydrothermal or solvothermal reaction of urea, wherein the graphitic carbon nitride (A ring) may be substituted with a hydrophilic group. For example, the hydrophilic group-providing monomer may be selected from citric acid, aspartic acid, glucose, or sugar.

[0155] The above-described embodiment will be explained in more detail below through examples. However, the following examples are for illustrative purposes only and do not limit the scope of the claims.

[0156] [Example 1] Synthesis of Poly((g-C3N4)-(acrylonitrile)-(acrylic acid))

[0157]

[0158] 5.31 g of acrylonitrile (AN), 21.62 g of acrylic acid (AA), and 2.17 g of 2,2'-azobis(2-methylpropionamidine)dihydrochloride (V50) were dissolved in 332.91 g of distilled water and heated and stirred at 70°C for 2 hours to synthesize a poly(AN-AA) carbon nitride precursor polymer. The carbon nitride precursor polymer solution was used in the next reaction without further purification.

[0159] 134.1 g of the carbon nitride precursor polymer (poly(AN-AA)) solution obtained above, 27.50 g of urea, and 27.90 g of distilled water were placed in a 500 ml autoclave with a Teflon inner container and reacted at 180°C for 5 hours. Afterward, the reacted solution was purified using a hollow fiber tangential flow filtration (TFF) with a molecular weight cut-off (MWCO) of 30,000 MWCO to obtain a g-C3N4 polymer (poly((g-C3N4)-co-AN-co-AA)) containing graphite carbon nitride (g-C3N4) repeating units.

[0160] 1H-NMR (400MHz, DO): δ 3.12 (s, 1H), 2.51 (s, 1H), 2.08 (d, J = 23.1 Hz, 23H), 1.65 (s, 15H), 1.51 (s, 24H), 1.13 (s, 2H).

[0161] 13 C-NMR (400MHz, DO): δ 183.62 (s), 180.58 (s), 178.43 (s), 162.78 (s), 58.84 (s), 48.13 (s), 45.01 (s), 44.55 (s), 42.72 (s), 39.90 (s), 37.59 (s), 36.53 (s), 35.58 (s), 33.63 (s), 20.65 (s).

[0162] [Example 2] Synthesis of Poly((g-C3N4)-(acrylamide)-(acrylic acid))

[0163]

[0164] 9.95 g of acrylamide (AAm), 15.13 g of acrylic acid (AA), and 1.90 g of 2,2'-azobis(2-methylpropionamidine)dihydrochloride (V50) were dissolved in 242.82 g of distilled water and heated and stirred at 70°C for 2 hours to synthesize a poly(AAm-AA) carbon nitride precursor polymer. The carbon nitride precursor polymer solution was used in the following reaction without further purification.

[0165] 88.2 g of the carbon nitride precursor polymer (poly(AAm-AA)) solution obtained above, 19.58 g of urea, and 70.60 g of distilled water were placed in a 500 ml autoclave with a Teflon inner container and reacted at 180°C for 5 hours. Afterward, the reacted solution was purified using a hollow fiber tangential flow filtration (TFF) membrane with a molecular weight cut-off of 30,000 MWCO to obtain a g-C3N4 polymer (poly((g-C3N4)-co-AAm-co-AA)) containing graphite carbon nitride (g-C3N4) repeating units.

[0166] 1 H-NMR (400MHz, DO): δ 3.13 (s, 1H), 3.10 (s, 3H), 3.08 (s, 6H), 3.06 (s, 3H), 2.50 (s, 1H), 2.48 (s, 4H), 2.46 (s, 6H), 2.44 (s, 3H).

[0167] 13 C-NMR (400 MHz, DO): δ 182.32 (s), 178.26 (s), 178.04 (s), 44.32 (s), 36.51 (s), 33.59 (s), 32.48 (s).

[0168] [Example 3] Synthesis of Poly((g-C3N4)-(acrylamide)-(N-vinylpyrrolidone))

[0169] 5.0 g of acrylamide (AAm), 15.0 g of N-vinylpyrrolidone (VP), and 1.08 g of 2,2'-Azobis(2-methylpropionamidine)dihydrochloride (V50) were dissolved in 189.72 g of distilled water and heated and stirred at 70°C for 2 hours to synthesize a poly(AAm-VP) carbon nitride precursor polymer. The carbon nitride precursor polymer solution was used in the next reaction without further purification.

[0170] 16.8 g of the carbon nitride precursor polymer (poly(AAm-VP)) solution obtained above, 3.53 g of urea, and 33.60 g of distilled water were placed in a 100 ml autoclave with a Teflon inner container and reacted at 180°C for 5 hours. Afterward, the reacted solution was purified using a hollow fiber tangential flow filtration (TFF) with a molecular weight cut-off (MWCO) of 30,000 MWCO to obtain a g-C3N4 polymer (poly((g-C3N4)-co-AAm-co-VP)) containing graphite carbon nitride (g-C3N4) repeating units.

[0171] 1 H-NMR (400 MHz, DO): δ 1.97 (d, J = 36.7 Hz, 1H), 1.46 (d, J = 50.6 Hz, 2H), 1.16 - 1.05 (m, 1H), 1.00 (s, 1H).

[0172] 13C-NMR (400MHz, DO): δ 193.86 (s), 187.52 (s), 183.86 (s), 183.47 (s), 180.12 (s), 175.88 (s), 49.78 (s), 48.01 (s), 45.25 (s), 44.64 (s), 42.57 (s), 38.27 (s), 36.78 (s), 35.78 (s), 34.95 (s), 32.22 (s), 24.84 (s), 21.78 (s), 20.63 (s), 18.80 (s).

[0173] [Example 4] Synthesis of Poly((g-C3N4)-(acrylic acid))

[0174]

[0175] 13.75 g of urea, 1.48 g of acrylamide (AAm), and 150.0 g of distilled water were placed in a 500 ml autoclave with a Teflon inner lining and reacted at 180°C for 5 hours to prepare a radically polymerizable carbon nitride monomer. The prepared carbon nitride monomer was used in the following reaction without further purification.

[0176] 10 g of acrylic acid (AA), 39.94 g of distilled water, and 1.66 g of V50 were mixed and stirred at 70°C for 3 hours. 5 g of the carbon nitride monomer obtained above (200 g of 2.5% aqueous solution) was added to this solution and reacted at 70°C for 12 hours. Afterward, the pH of the reacted solution was adjusted to 4.5 using a 10% NaOH solution, and purified using a hollow fiber tangential flow filtration (TFF) with a molecular weight cut-off (MWCO) of 30,000 to obtain a g-C3N4 polymer (poly((g-C3N4)-co-AA)) containing graphite carbon nitride (g-C3N4) repeating units.

[0177] 1H-NMR (400MHz, DO): δ 2.66 (s, 1H), 2.62 (s, 2H), 2.53 (s, 2H), 2.49 (s, 1H), 1.51 (s, 2H).

[0178] 13 C-NMR (400 MHz, DO): δ 183.76 (s), 181.75 (s), 179.03 (s), 75.13 (s), 45.60 (s), 45.06 (s), 22.73 (s).

[0179] [Example 5] Synthesis of Poly((g-C3N4)-(N-vinylpyrrolidone))

[0180] 13.75 g of urea, 1.48 g of acrylamide (AAm), and 150.0 g of distilled water were placed in a 500 ml autoclave with a Teflon inner container and reacted at 180°C for 5 hours. The precipitate was filtered to prepare a radical polymerizable carbon nitride monomer solution. The prepared carbon nitride monomer solution was used in the following reaction without further purification.

[0181] 5 g of N-vinylpyrrolidone (VP), 189.72 g of distilled water, and 1.08 g of V50 were mixed in a 500 ml 3-neck reactor and stirred at 70°C for 3 hours. 5 g of carbon nitride monomer (200 g of 2.5% aqueous solution) was added to this solution and reacted for 12 hours. Afterward, the reacted solution was purified using a hollow fiber tangential flow filtration (TFF) with a molecular weight cut-off of 30,000 MWCO to obtain a g-C3N4 polymer (poly((gC3N4)-co-VP)) containing graphite carbon nitride (g-C3N4) repeating units.

[0182] 1H-NMR (400 MHz, DO): δ 3.30 (s, 1H), 2.65 (s, 1H), 2.61 (s, 1H), 2.50 (s, 1H), 2.47 (s, 1H), 2.30 (s, 1H), 2.20 (s, 1H), 2.01 (s, 1H).

[0183] 13 C-NMR (400MHz, DO): δ 215.43 (s), 182.02 (s), 179.34 (s), 177.80 (s), 75.25 (s), 45.81 (s), 44.58 (d, J = 29.7 Hz), 42.38 (s), 31.43 (s), 30.36 (s), 17.70 (s).

[0184] [Example 6] Synthesis of Poly((g-C3N4-COOH)-(acrylonitrile)-(acrylic acid))

[0185] 10.0 g of urea, 5.917 g of acrylamide (AAm), 10.50 g of melamine (M), 6.398 g of citric acid (CA), and 200.0 g of ethanol were placed in a 500 ml autoclave and reacted at 160°C for 5 hours. After filtration, 204.6 g of a radical polymerizable carbon nitride monomer (g-C3N4-COOH) ethanol solution (solid content 4.74%) functionalized with COOH was prepared. The prepared carbon nitride monomer ethanol solution was used in the following reaction without further purification.

[0186] 20.09 g of acrylonitrile (AN), 3.03 g of acrylic acid (AA), and 2.455 g of ethanol were mixed in a 500 ml 3-neck reactor and heated to 65 ℃. A dispersion of 0.301 g of AIBN dispersed in 14.03 g of ethanol was added and stirred for 40 minutes. To this solution, 133.6 g of the ethanol solution of the carbon nitride monomer (g-C3N4-COOH) synthesized above was added dropwise, and the mixture was stirred at 70 ℃ for 12 hours. After cooling to room temperature, the pale yellow polymer precipitate was filtered and dried to obtain 17.46 g of a g-C3N4 polymer (poly((g-C3N4-COOH)-co-AN-AA)) containing repeating units of graphite carbon nitride (g-C3N4-COOH) functionalized with COOH.

[0187] 1 H-NMR (400 MHz, DMSO): δ 6.11 (s, 1H), 5.5 (s, trace), 3.21 (s, 33H), 2.60 (s, 7H), 2.13 (t, 59H), 1.93 (t, 7H), 1.53 (s, 1H), 1.48 (s, 1H), 1.21 (s, 1H).

[0188] [Experimental Example]

[0189] Evaluation 1. TEM Analysis

[0190] The results of analyzing the g-C3N4 polymer prepared in Example 1 using transmission electron microscopy (TEM) are shown in Fig. 1. Referring to Fig. 1, it can be seen that graphitic carbon nitride (g-C3N4) exists in the form of quantum dots within the g-C3N4 polymer.

[0191] Evaluation 2. Solubility Evaluation

[0192] The solubility of the g-C3N4 polymers prepared in Examples 4 to 6 above in distilled water (H2O) and organic solvents (ethanol (EtOH), N-methylpyrrolidone (NMP), dimethylformamide (DMF)) was evaluated, and the evaluation results are listed in Table 1 below.

[0193] O: Solubility 2 wt% or more

[0194] △: Solubility 1 wt% or more ~ ​​less than 2 wt%

[0195] X: Solubility less than 1 wt%

[0196] g-C3N4 polymer H2OEtOHNMPDMF Example 4 O△O△ Example 5 O△OO Example 6 XXOO

[0197] Referring to Table 1 above, it can be seen that g-C3N4 according to one embodiment has excellent water solubility despite containing graphitic carbon nitride units, and also has excellent solubility in organic solvents such as NMP, acetonitrile, and DMF.

[0198] Evaluation 3. Preparation of Carbon Nanotube Dispersion

[0199] A carbon nanotube dispersion was prepared using the g-C3N4 polymer prepared in the above example as a dispersant, with the composition listed in Table 2 below. The carbon nanotube dispersion was prepared using a high-speed homogenizer and a high-pressure homogenizer. The viscosity of the prepared dispersion was evaluated and is listed in Table 2 below.

[0200] Carbon nanotube / Content Solvent g-C3N4 Polymer / Content Viscosity (cPs) 1 Single-layer carbon nanotube / 0.5% H2O Example 4 / 1% 2738 2 Single-layer carbon nanotube / 0.5% H2O Example 5 / 1% 1859 3 Single-layer carbon nanotube / 0.5% H2O Example 6 / 1% 3807 4 Multilayer carbon nanotube / 3.0% NMP Example 5 / 1.5% 3611

[0201] Referring to Table 2 above, it can be seen that the g-C3N4 polymer according to the embodiment of the present invention can be usefully applied as a dispersant for carbon nanomaterials such as carbon nanotubes.

[0202] In addition, the fluorescence characteristics of the powder of the g-C3N4 polymer prepared in Example 6 and the DMSO solution were analyzed and are shown in Figure 2. Referring to Figure 2, it can be optically confirmed that the polymer prepared through the example contains carbon nitride quantum dots.

[0203] As described above, the present disclosure has been explained by specific details and limited embodiments, but this is provided only to aid in a more comprehensive understanding of the present disclosure. The present disclosure is not limited to the above embodiments, and various modifications and variations are possible from this description by those skilled in the art to which the present disclosure pertains.

[0204] Accordingly, the present disclosure is not limited to the embodiments described above, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to be within the scope of the present disclosure.

Claims

g-C3N4 polymer comprising graphitic carbon nitride repeating units represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, The A ring is substituted or unsubstituted graphitic carbon nitride (g-C3N4); L 1 is a divalent organic group; R 1 It is hydrogen or (C1-C4)alkyl. In paragraph 1, The above g-C3N4 polymer is a g-C3N4 polymer that further comprises a hydrophilic repeating unit in which a hydrophilic group is bonded as a side chain. In paragraph 2, g-C3N4 polymer, wherein the hydrophilic group is a hydroxyl group, an amino group, an ammonium group, an amide group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphonic acid group or a salt thereof, a cyano group, a tri(C1-C4)alkoxysilane, a morpholine group, a pyrrolidone group, a polyoxy(C1-C4)alkylene group, or a combination thereof. In paragraph 2, g-C3N4 polymer, wherein the above hydrophilic repeating unit is represented by the following chemical formula 2. [Chemical Formula 2] In the above chemical formula 2, X is a hydroxyl group, amino group, ammonium group, amide group, carboxyl group or a salt thereof, sulfonic acid group or a salt thereof, phosphonic acid group or a salt thereof, cyano group, tri(C1-C4)alkoxysilane, morpholine group, pyrrolidone group, or And; L 2 is a divalent organic group; L 3 is a C1-C4 alkylene; n is an integer from 2 to 100; R 2 and R 3 Each is independently hydrogen or C1-C4 alkyl. In paragraph 2, A g-C3N4 polymer comprising 0.1 to 50 moles of hydrophilic repeating units per 1 mole of graphitic carbon nitride repeating unit. In paragraph 1, The above graphitic carbon nitride is a g-C3N4 polymer, which is triazine-based carbon nitride or heptazine-based carbon nitride. In paragraph 1, The above L 1 g-C3N4 polymer, which is a single bond, (C1-C4)alkylene, -C(=O)-, -NH-, (C6-C12)arylene, or a combination thereof. In paragraph 4, The above L 2 g-C3N4 polymer, which is a single bond, (C1-C4)alkylene, or (C6-C12)arylene. A method for preparing a g-C3N4 polymer, comprising: a step of radically polymerizing a monomer solution containing a radically polymerizable nitrogen-providing precursor represented by the following chemical formula 11 to produce a carbon nitride precursor polymer containing repeating units represented by the following chemical formula 12; and a step of performing a hydrothermal or solvothermal reaction between the carbon nitride precursor polymer and urea to produce a g-C3N4 polymer containing graphitic carbon nitride repeating units represented by the following chemical formula 1. [Chemical Formula 11] [Chemical Formula 12] [Chemical Formula 1] In the above chemical formulas 1, 11, and 12, A 1 is a cyano group or an amide group; The A ring is graphitic carbon nitride (g-C3N4); L 1 is a divalent organic group; R 1 It is hydrogen or (C1-C4)alkyl. In Paragraph 9, A method for preparing a g-C3N4 polymer, wherein the above monomer solution further comprises a radical polymerizable comonomer containing a hydrophilic group. In Paragraph 9, A method for preparing a g-C3N4 polymer, wherein the above g-C3N4 polymer further comprises a repeating unit represented by the above chemical formula 12. A method for producing a g-C3N4 polymer, comprising: a step of producing a radical polymerizable carbon nitride monomer represented by the following chemical formula 13 by performing a hydrothermal or solvothermal reaction between a radical polymerizable nitrogen-providing precursor represented by the following chemical formula 11 and urea; and a step of producing a g-C3N4 polymer comprising graphitic carbon nitride repeating units represented by the following chemical formula 1 by radical polymerizing a monomer solution containing the radical polymerizable carbon nitride monomer. [Chemical Formula 11] [Chemical Formula 13] [Chemical Formula 1] In the above chemical formulas 1, 11, and 13, A 1 is a cyano group or an amide group; The A ring is graphitic carbon nitride (g-C3N4); L 1 is a divalent organic group; R 1 It is hydrogen or (C1-C4)alkyl. In Paragraph 12, A method for preparing a g-C3N4 polymer, wherein the above monomer solution further comprises a radical polymerizable comonomer containing a hydrophilic group.

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