Membrane and method for manufacturing the same

Abstract

The purpose of the present disclosure is to provide a film in which a decrease in conductivity over time is suppressed, and preferably, to provide a film in which a decrease in conductivity over time is suppressed even under high temperature and high humidity conditions. Also, the purpose of the present disclosure is to provide a method for producing said film.　This film comprises a two-dimensional particle having at least one layer and containing N-methylformamide, wherein the layer include: a layer body represented by formula MmXn (in the formula, M is at least one among the Group 3, 4, 5, 6, and 7 metal elements, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1-4, and m is greater than n and less than or equal to 5); and a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom), the N-methylformamide is disposed between two adjacent layers, and the content of N-methylformamide in the film is at least 0.104 moles per 1 mole of MmXn.

Description

[Technical Field]

[0001] This disclosure relates to a film and a method for producing the same, and more particularly to a film containing two-dimensional particles and a method for producing the same. [Background technology]

[0002] In recent years, MXene has attracted attention as a novel conductive material. MXene is a type of so-called two-dimensional material, and as described later, it is a layered material having the form of one or more layers. Generally, MXene has the form of particles of such layered material (which may include powder, flakes, nanosheets, etc.).

[0003] Currently, various studies are being conducted to apply MXene to various electrical devices. For example, research is being conducted to improve the conductivity of materials containing MXene and to expand the potential applications of MXene-containing materials.

[0004] Patent Document 1 describes that the conductivity can be improved by removing the intercalator used in the manufacture of MXene by acid treatment.

[0005] Furthermore, Non-Patent Document 1 describes dispersing MXene in solvents such as N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, and ethanol to create an ink, which is then directly printed onto a microsupercapacitor. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Chinese Patent Publication No. 112795209 [Non-patent literature]

[0007] [Non-Patent Document 1] Chuanfang (John) Zhang, et al., "Additive-free MXene inks and direct printing of micro-supercapacitors" NATURE COMMUNICATIONS 2019, 10, 1795 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the case of MXene described in Patent Document 1 and Non-Patent Document 1, the conductivity sometimes decreased over time.

[0009] This disclosure aims to provide a film in which the decrease in conductivity over time is suppressed, and preferably a film in which the decrease in conductivity over time is suppressed even under high temperature and high humidity conditions. This disclosure also aims to provide a method for manufacturing such a film. [Means for solving the problem]

[0010] The film of this disclosure is a film containing two-dimensional particles, The above two-dimensional particle is a two-dimensional particle having one or more layers, and containing N-methylformamide. The above layer is represented by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer body, The above N-methylformamide is placed between two adjacent layers. The content of N-methylformamide in the above film is 1 mole of M m X n The amount is 0.104 moles or more.

[0011] Furthermore, the method for manufacturing the film described herein is (a) The following equation: M m AX n (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal containing at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product. (e) Stirring the intercalation-treated material to obtain a delamination-treated material in which the intercalation-treated material is delaminated. (f) Mixing the above delamination treatment product with N-methylformamide to obtain a mixture, and (h) Form a precursor film using the above mixture, (i) The process includes drying the precursor film under normal pressure to form a film. [Effects of the Invention]

[0012] According to the present disclosure, a film with suppressed decrease in conductivity over time can be provided, and preferably, a film with suppressed decrease in conductivity over time even under high temperature and high humidity can be provided. Further, the present disclosure can provide a method for manufacturing such a film.

Brief Description of Drawings

[0013] [Figure 1] It is a schematic cross-sectional view showing MXene particles of a layered material in one embodiment of the present disclosure, where (a) shows single-layer MXene particles and (b) shows multi-layer (exemplarily two-layer) MXene particles. [Figure 2] It is a schematic cross-sectional view showing a film in one embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0014] Hereinafter, a film and a manufacturing method thereof in one embodiment of the present disclosure will be described.

[0015] The film of the present disclosure is a film containing two-dimensional particles, The two-dimensional particles are two-dimensional particles having one or more layers, containing N-methylformamide, The layer has the following formula: M m X n (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 or more and 4 or less, m is greater than n and 5 or less) and includes a layer main body represented by the formula and a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer main body, The N-methylformamide is disposed between two adjacent layers, The content of N-methylformamide in the film is 1 mole of M m Xn In contrast, It is 0.104 moles or more.

[0016] The film of this disclosure exhibits suppressed degradation of conductivity over time, preferably even under high temperature and high humidity conditions. Although it should not be interpreted as being limited to any particular theory, in the film of this disclosure, a certain amount of N-methylformamide is present between the layers contained in the two-dimensional particles, and it is thought that hydrogen bonding groups contained in the N-methylformamide can form hydrogen bonds with the layer modifications or terminal T. Therefore, it is thought that the N-methylformamide is stably present between the layers, suppressing the penetration of water into the interlayers and suppressing the expansion of the interlayer distance. As a result, it is thought that the degradation of conductivity due to the expansion of the interlayer distance can be suppressed.

[0017] In this disclosure, when we refer to an element as an "atom," the oxidation number of that element is not limited to 0, but can be any number within the range of oxidation numbers that the element can take.

[0018] In this disclosure, the two-dimensional particles may be understood as a layered material or layered compound, and "M m X n T s It can also be expressed as , where s is any number, and traditionally, x or z have sometimes been used instead of s. Typically, n can be 1, 2, 3, or 4, but is not limited to these.

[0019] Furthermore, in this disclosure, the above layer may be referred to as the MXene layer, and the above two-dimensional particles may be referred to as MXene two-dimensional particles or MXene particles.

[0020] In the above formula for MXene, M is preferably at least one selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn, and more preferably at least one selected from the group consisting of Ti, V, Cr, and Mo.

[0021] MXene is expressed in the above formula: M m Xn However, the following expressions are known: Sc2C, Ti2C, Ti2N, Zr2C, Zr2N, Hf2C, Hf2N, V2C, V2N, Nb2C, Ta2C, Cr2C, Cr2N, Mo2C, Mo 1.3 C, Cr 1.3 C, (Ti,V)2C, (Ti,Nb)2C, W2C, W 1.3 C, Mo2N, Nb 1.3 C, Mo 1.3 Y 0.6 C (In the above formula, "1.3" and "0.6" mean approximately 1.3 (=4 / 3) and approximately 0.6 (=2 / 3), respectively.) Ti3C2, Ti3N2, Ti3(CN), Zr3C2, (Ti,V)3C2, (Ti2Nb)C2, (Ti2Ta)C2, (Ti2Mn)C2, Hf3C2, (Hf2V)C2, (Hf2Mn)C2, (V2Ti)C2, (Cr2Ti)C2, (Cr2V)C2, (Cr2Nb)C2, (Cr2Ta)C2, (Mo2Sc)C2, (Mo2Ti)C2, (Mo2Zr)C2, (Mo2Hf)C2, (Mo2V)C2, (Mo2Nb)C2, (Mo2Ta)C2, (W2Ti)C2, (W2Zr)C2, (W2Hf)C2, Ti4N3, V4C3, Nb4C3, Ta4C3, (Ti,Nb)4C3, (Nb,Zr)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (V2Nb2)C3, (V2Ta2)C3, (Nb2Ta2)C3, (Cr2Ti2)C3, (Cr2V2)C3, (Cr2Nb2)C3, (Cr2Ta2)C3, (Mo2Ti2)C3, (Mo2Zr2)C3, (Mo2Hf2)C3, (Mo2V2)C3, (Mo2Nb2)C3, (Mo2Ta2)C3, (W2Ti2)C3, (W2Zr2)C3, (W2Hf2)C3, (Mo 2.7 V 1.3 )C3 (In the above formula, "2.7" and "1.3" mean approximately 2.7 (=8 / 3) and approximately 1.3 (=4 / 3), respectively.)

[0022] Typically, in the above formula, M can be titanium or vanadium, and X can be a carbon atom or a nitrogen atom. For example, the MAX phase is Ti3AlC2, the main layer is Ti3C2, and MXene is Ti3C2T s It is possible (in other words, M is Ti, X is C, n is 2, and m is 3).

[0023] In this disclosure, MXene may contain a relatively small amount of A atoms derived from the precursor MAX phase, for example, 10% by mass or less relative to the original A atoms. The residual amount of A atoms may preferably be 8% by mass or less, more preferably 6% by mass or less, relative to the original A atoms. However, even if the residual amount of A atoms exceeds 10% by mass, this may not be a problem depending on the application and usage conditions of the two-dimensional particles.

[0024] The above two-dimensional particle is an aggregate containing one layer of MXene particles (hereinafter simply referred to as "MXene particles") 10a (single-layer MXene particles), schematically illustrated in Figure 1(a). More specifically, the MXene particle 10a is M m X n The layer body (M) represented by m X n The MXene layer 7a has a layer 1a and modifications or terminations T3a, 5a present on the surface of the layer body 1a (more specifically, at least one of the two surfaces facing each other in each layer). Therefore, the MXene layer 7a is "M m X n T s It can also be expressed as , where s is any number. Note that N-methylformamide is not shown in Figure 1(a).

[0025] The above two-dimensional particles may include one or more layers. As an example of MXene particles with multiple layers (multilayer MXene particles), two layers of MXene particles 10b are shown schematically in Figure 1(b), but the example is not limited to these. In Figure 1(b), 1b, 3b, 5b, and 7b are the same as 1a, 3a, 5a, and 7a in Figure 1(a) described above. Two adjacent MXene layers of multilayer MXene particles (e.g., 7a and 7b) do not necessarily have to be completely separated, but may be partially in contact. The above MXene particle 10a is one in which the multilayer MXene particle 10b is individually separated and exists as a single layer, while unseparated multilayer MXene particles 10b remain, and it may be a mixture of the above single-layer MXene particle 10a and multilayer MXene particle 10b. Note that N-methylformamide is not shown in Figure 1(b).

[0026] Although not limited to this embodiment, the thickness of each layer contained in the MXene particles (corresponding to the MXene layers 7a and 7b described above) is, for example, 0.8 nm to 5 nm, and more particularly 0.8 nm to 3 nm (this may vary mainly depending on the number of M atomic layers contained in each layer). For each stack of the multilayer MXene particles that may be contained, the interlayer distance (or void dimension, shown as Δd in Figure 1(b)) may be, for example, 0.8 nm to 10 nm, more particularly 0.8 nm to 5 nm, and more specifically 0.8 nm to 1.5 nm. The total number of layers may be 2 or more and 20,000 or less.

[0027] In one embodiment, the two-dimensional particles in this embodiment preferably include two-dimensional particles with a small number of layers, obtained by delamination, which may be included as described above. "Small number of layers" means, for example, that the number of stacked MXene layers is 6 or less. Furthermore, the thickness in the stacking direction of the multilayer MXene particles with a small number of layers is preferably 15 nm or less, and more preferably 10 nm or less. Hereinafter, these "multilayer MXene particles with a small number of layers" may be referred to as "low-layer MXene particles." Also, single-layer MXene particles and low-layer MXene particles may be collectively referred to as "single-layer / low-layer MXene particles." By including single-layer / low-layer MXene particles, the conductivity of the resulting film can be increased.

[0028] The two-dimensional particles in this embodiment preferably include single-layer MXene particles and thin-layer MXene particles, i.e., single-layer and thin-layer MXene particles. In the two-dimensional particles of this embodiment, the proportion of single-layer and thin-layer MXene particles with a thickness of 15 nm or less is preferably 90% by volume or more, and more preferably 95% by volume or more.

[0029] In one embodiment, the ratio of (average value of the major axis of the two-dimensional surface of the two-dimensional particle) / (average value of the thickness of the two-dimensional particle) is 1.2 or more, preferably 1.5 or more, and more preferably 2 or more. The average value of the major axis of the two-dimensional surface of the two-dimensional particle and the average value of the thickness of the two-dimensional particle can be determined by the method described later.

[0030] (Average value of the major axis of the two-dimensional plane of a two-dimensional particle) In this embodiment, the two-dimensional particles have an average major axis of the two-dimensional surface of 1 μm or more and 20 μm or less. Hereinafter, the average major axis of the two-dimensional surface may be referred to as the "average flake size".

[0031] The larger the average flake size, the higher the conductivity of the film. In this embodiment, the two-dimensional particles have a large average flake size of 1.0 μm or more, so a film formed using these two-dimensional particles, for example, a film obtained by stacking these two-dimensional particles, can achieve a conductivity of 2000 S / cm or more. The average value of the major axis of the two-dimensional surface is preferably 1.5 μm or more, more preferably 2.5 μm or more. When MXene is delaminated by ultrasonic treatment, most of the MXene is reduced in diameter to about several hundred nm by ultrasonic treatment, so a film formed from single-layer MXene delaminated by ultrasonic treatment is considered to have low conductivity.

[0032] The average value of the major axis of the two-dimensional surface is 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less, from the viewpoint of dispersibility in the dispersion medium.

[0033] The major axis of the above two-dimensional plane refers to the major axis when each MXene particle is approximated as an ellipse in an electron microscope image, as shown in the examples below. The average value of the major axis of the above two-dimensional plane refers to the average number of major axes for 80 or more particles. Scanning electron microscopes (SEM) and transmission electron microscopes (TEM) can be used as electron microscopes.

[0034] The average length of the two-dimensional particles in this embodiment may be measured by dissolving the film containing the two-dimensional particles in a solvent and dispersing the two-dimensional particles in the solvent. Alternatively, it may be measured from an SEM image of the film.

[0035] (Average thickness of 2D particles) The average thickness of the two-dimensional particles in this embodiment is preferably between 1 nm and 15 nm. The above thickness is preferably 10 nm or less, more preferably 7 nm or less, and even more preferably 5 nm or less. On the other hand, considering the thickness of the single-layer MXene particles, the lower limit of the two-dimensional particle thickness can be 1 nm.

[0036] The average thickness of the above two-dimensional particles is determined as a number-average dimension (e.g., a number-average of at least 40 particles) based on atomic force microscope (AFM) or transmission electron microscope (TEM) images.

[0037] The above two-dimensional particle contains N-methylformamide. In the two-dimensional particle, N-methylformamide is positioned between two adjacent layers. Here, both adjacent layers may be contained in a single two-dimensional particle having multiple layers, or one may be contained in a two-dimensional particle having one or more layers, and the other may be contained in another two-dimensional particle having one or more layers. For example, N-methylformamide may be present on the surface of the two-dimensional particle. That is, N-methylformamide may be present on the surface side of the layer located on the outermost surface of the two-dimensional particle, in contact with that layer. Even in this case, it is thought that N-methylformamide can form hydrogen bonds between the outermost layer of one two-dimensional particle and the outermost layer of another two-dimensional particle, and that this can contribute to suppressing the decrease in conductivity over time, and furthermore, to suppressing the decrease in conductivity over time even under high temperature and high humidity conditions.

[0038] While it should not be interpreted in isolation from any particular theory, N-methylformamide possesses a secondary amino group (-NH-) acting as a hydrogen donor and an oxygen atom (O=) acting as a hydrogen acceptor as hydrogen bonding groups, and is therefore thought to readily form hydrogen bonds with the layer modification or terminal T in the two-dimensional particles. For this reason, N-methylformamide can stably exist between the layers of the two-dimensional particles, suppressing the penetration of water into the interlayers while simultaneously maintaining the multilayer structure.

[0039] The presence of N-methylformamide between the layers in the above two-dimensional particles was confirmed by X-ray diffraction (XRD) measurements, which showed an interlayer distance (d 002 This can be confirmed by measuring the interlayer distance (d 002) can be, for example, 1.1 nm to 1.5 nm, and further 1.2 nm to 1.4 nm. On the other hand, in two-dimensional particles that do not contain enough N-methylformamide, the interlayer distance (d 002 These particles may be, for example, 0.8 nm or more and less than 1.1 nm in size, and can be distinguished from the two-dimensional particles containing the above-mentioned N-methylformamide.

[0040] In the above two-dimensional particle (1), d 002 The full width at half maximum of the corresponding peak can be, for example, 0° or more and 0.5° or less, preferably 0° or more and 0.3° or less, and may be 0.1° or more, with 2θ being such. In a two-dimensional particle (1), d 002 The full width at half maximum of the corresponding peak falls within the above range, suggesting that the interlayer distances are well-defined.

[0041] The N-methylformamide content in the film of this embodiment is 1 mole of M m X n The amount is 0.104 moles or more. This is thought to sufficiently suppress the penetration of water into the interlayers of the two-dimensional particles. The content of N-methylformamide in the film of this embodiment is 1 mole of M m X n The amount may preferably be 0.104 moles or more and 0.5 moles or less, and more preferably 0.12 moles or more and 0.3 moles or less.

[0042] The N-methylformamide content in the film of this embodiment can be measured by thermogravimetric analysis (TG). For example, when the temperature is raised from 150°C to 450°C at a rate of 10°C / min or 20°C / min, the difference between the mass at 150°C and the mass at 450°C may be used as the N-methylformamide content. m X n The amount of substance is calculated by taking the mass before heating to above 150°C and then adding M. m X n Assuming the mass is M, m X n It can be calculated by dividing by the formula quantity.

[0043] (Embodiment 2: Method for manufacturing two-dimensional particles) The following describes in detail a method for producing two-dimensional particles in one embodiment of the present disclosure, but the present disclosure is not limited to this embodiment.

[0044] The method for manufacturing two-dimensional particles in this embodiment is: (a) Prepare a predetermined precursor, (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mixing the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product, and (e) Stirring the intercalation material to obtain a delamination material in which the intercalation material has been delaminated, (f) A mixture (slurry) containing the above two-dimensional particles can be prepared by mixing the delamination treatment product with N-methylformamide. (g) The delamination treatment may be dried before being mixed with N-methylformamide.

[0045] The following details each step.

[0046] ·Process (a) First, a predetermined precursor is prepared. In this embodiment, the predetermined precursor that can be used is the MAX phase, which is a precursor of MXene. The following formula: M m AX n (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal containing at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. It is represented as follows.

[0047] The above M, X, n, and m are as described above.

[0048] A is at least one element from groups 12, 13, 14, 15, or 16, usually a group A element, typically from groups IIIA and IVA, and more specifically, may include at least one selected from the group consisting of Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, S, and Cd, preferably Al.

[0049] The MAX phase is M m X n The MAX phase has a crystal structure in which a layer composed of A atoms is located between two layers represented by (each X may have a crystal lattice located within an octahedral array of M). Typically, in the case of m=n+1, one layer of X atoms is placed between each of the n+1 layers of M atoms (these together are called "M"). m X n It has, but is not limited to, a repeating unit in which a layer of A atoms ("A atomic layer") is placed as the layer following the n+1th M atom layer (also called a "layer").

[0050] The MAX phase described above can be manufactured by known methods. For example, TiC powder, Ti powder, and Al powder can be mixed in a ball mill, and the resulting mixed powder can be calcined in an Ar atmosphere to obtain a calcined body (block-shaped MAX phase). The calcined body can then be crushed with an end mill to obtain powdered MAX phase for the next process.

[0051] ·Process (b) In step (b), the above precursor M is removed using an etching solution. m AX n An etching process is performed to remove at least some of the A atoms from the precursor. m X n A processed material is obtained in which the layer represented by remains intact, while at least a portion of the layer composed of A atoms is removed.

[0052] The etching solution described above may contain acids such as HF, HCl, HBr, HI, sulfuric acid, phosphoric acid, and nitric acid, and typically an etching solution containing F atoms can be used. Examples of such etching solutions include a mixture of LiF and hydrochloric acid; a mixture of hydrofluoric acid and hydrochloric acid; and a mixture containing hydrofluoric acid. These mixtures may further contain phosphoric acid or the like. The etching solution described above is typically an aqueous solution.

[0053] Conventional conditions can be used for the etching operation using the above-mentioned etching solution and other related conditions.

[0054] ·Process (c) In step (c), the etched material obtained by the etching process is washed to obtain an etched-cleaned material. Washing thoroughly removes the acid and other substances used in the etching process.

[0055] Cleaning can be carried out using a cleaning solution, typically by mixing the etched material with the cleaning solution. Such a cleaning solution typically contains water, and pure water is preferred. Alternatively, it may also contain a small amount of hydrochloric acid or the like. The amount of cleaning solution mixed with the etched material and the method of mixing are not particularly limited. For example, such mixing methods include allowing the etched material and cleaning solution to coexist and performing stirring, centrifugation, etc. Stirring methods include using a handshake, automatic shaker, shear mixer, pot mill, etc. The degree of stirring, such as stirring speed and stirring time, should be adjusted according to the amount and concentration of the etched material to be treated. One or more cleanings with the above cleaning solution are sufficient, and it is preferable to perform multiple cleanings. For example, the washing with the washing solution described above may be carried out by sequentially performing steps (i) adding the washing solution (to the treated material or the remaining precipitate obtained in (iii) below) and stirring, step (ii) centrifuging the stirred material, and step (iii) discarding the supernatant after centrifugation. Steps (i) to (iii) may be repeated two or more times, for example, up to 15 times.

[0056] ·Process (d) In step (d), an intercalation process is performed using an intercalator to obtain an intercalated product.

[0057] Examples of the above-mentioned intercalators include metal compounds containing metal cations, organic compounds, and organic salts.

[0058] The above-mentioned metal cation may be the same as the metal cation contained in the above-mentioned two-dimensional particle.

[0059] Examples of the above-mentioned metal compounds include ionic compounds in which the above-mentioned metal cation and anion are bonded. For example, examples of the above-mentioned metal cation include iodide, phosphate, sulfate, sulfide salt, nitrate, acetate, and carboxylate salts. As the above-mentioned metal cation, alkali metal ions and alkaline earth metal cations are preferred, and lithium ions are more preferred. As the metal compound, metal compounds containing alkali metal ions and alkaline earth metal ions are preferred, metal compounds containing lithium ions are more preferred, ionic compounds of lithium ions are even more preferred, and one or more of lithium ion iodide, phosphate, and sulfide salts are particularly preferred. If lithium ions are used as the metal ions, it is thought that monolayer formation is easier because the water hydrated with the lithium ions has the most negative dielectric constant.

[0060] When a metal compound containing metal cations is used as an intercalator, metal cations can be intercalated into the etched and cleaned material. This allows the above metal cations to intercalate into two adjacent M m X n An intercalated product is obtained, in which layers are intercalated between each other.

[0061] The above organic compounds are soluble in or miscible with water. The solubility of the above organic compounds in water is 5 g / 100 g H2O or more at 25°C, and more preferably 10 g / 100 g H2O or more. In this specification, solubility when miscible with water is treated as infinite.

[0062] The above organic compound is preferably a highly polar compound. In this specification, a highly polar compound is defined not only as a compound exhibiting clear charge separation, but also as a compound with high hydrophilicity. The polarity of a compound can be evaluated using its solubility parameter as an indicator. The Hildebrand solubility parameter (also called the "SP value") of the above organic compound is 19.0 MPa. 1 / 2 That concludes the explanation. The SP value of the organic compound is preferably less than or equal to the SP value of water, at 47.8 MPa. 1 / 2 The following applies: The SP value is an indicator of a compound's polarity; the larger the SP value, the more polar the compound. Compounds with similar SP values ​​tend to be more compatible with each other.

[0063] The boiling point of the above organic compound is, for example, 285°C or lower, preferably 240°C or lower, more preferably 200°C or lower, and for example, 50°C or higher.

[0064] The molecular weight of the above organic compound is, for example, 500 or less, preferably 300 or less, more preferably 200 or less, and for example, 30 or more.

[0065] Examples of the above organic compounds include organic compounds having one or more of the following groups: carbonyl group, ester group, amide group, formamide group, carbamoyl group, carbonate group, aldehyde group, ether group, sulfonyl group, sulfinyl group, hydroxyl group, cyano group, and nitro group. Specifically, examples of organic compounds include alcohols such as methanol (MeOH), ethanol (EtOH), and 2-propanol; sulfone compounds such as sulfolane; sulfoxides such as dimethyl sulfoxide (DMSO); carbonic acid such as propylene carbonate (PC); amides such as N-methylformamide (NMF), N,N-dimethylformamide, N-methylpyrrolidone (NMP), and dimethylacetamide (DMAc); ketones such as acetone and methyl ethyl ketone (MEK); and tetrahydrofuran (THF).

[0066] When an organic compound is used as an intercalator, the organic compound is intercalated into the etched and cleaned material. As a result, the above organic compound intercalates into two adjacent M m X n An intercalated product is obtained, in which layers are intercalated between each other.

[0067] Examples of the above organic salts include organic salts containing an organic cation and anion. Examples of the above organic cation include ammonium cation, and examples of the above anion include hydroxide ions and chloride ions. Examples of the above organic salts include ammonium salts. Specific examples of the above organic salts include tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), and tetrabutylammonium chloride.

[0068] When an organic salt is used as an intercalator, the organic cations constituting the organic salt can be intercalated into the etched and cleaned material. As a result, the organic cations can intercalate into two adjacent M m X n An intercalated product is obtained, in which layers are intercalated between each other.

[0069] Such intercalation processing may be carried out in a dispersed medium. The specific method of intercalation processing is not particularly limited; for example, the etched and cleaned material and the metal compound may be mixed and stirred, or left to stand. For example, stirring at room temperature is one option. Examples of the stirring methods include using a stirring bar such as a stirrer, using a stirring blade, using a mixer, and using a centrifugal apparatus. The stirring time can be set according to the production scale of single-layer and small-layer MXene particles, for example, between 12 and 24 hours.

[0070] Intercalation processing may be carried out in the presence of a dispersion medium. Examples of dispersion media include water; organic media such as N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, methanol, ethanol, dimethyl sulfoxide, ethylene glycol, and acetic acid.

[0071] The mixing order of the dispersion medium, the etched and cleaned material, and the metal compound is not particularly limited, but in one embodiment, the metal compound may be mixed after the dispersion medium and the etched and cleaned material have been mixed. Typically, the etching solution after etching may be used as the dispersion medium.

[0072] Intercalation treatment can typically be performed on an etched and cleaned product, but in another embodiment, it may be performed on the precursor simultaneously with the etching treatment. Specifically, such etching and intercalation treatment involves mixing the precursor, an etching solution, and a metal compound containing metal cations to remove at least some A atoms from the precursor, and intercalating the metal cations into the precursor from which the A atoms have been removed, thereby obtaining an intercalated product. As a result, at least some A atoms are removed from the precursor (MAX), and M in the precursor is also removed. m X n The layer remains, and multiple adjacent M m X n An intercalated product is obtained in which metal cations are intercalated between the layers.

[0073] The etching solution and metal compound used in the above etching and intercalation processes can be the same as those used in step (b), respectively.

[0074] ·Process (e) In step (e), the intercalation material is stirred to perform a delamination process, thereby obtaining a delaminated material. This stirring applies shear stress to the intercalation material, causing two adjacent M m X n At least a portion of the layers may be separated, and the MXene particles may be made into single or multiple layers.

[0075] The conditions for delamination are not particularly limited and can be carried out by known methods. For example, one method of applying shear stress to the intercalation material is to disperse the intercalation material in a dispersion medium and stir it. Stirring methods include stirring using a mechanical shaker, vortex mixer, homogenizer, ultrasonic treatment, handshake, or automatic shaker. The degree of stirring, such as stirring speed and stirring time, should be adjusted according to the amount and concentration of the material to be treated. For example, after the above intercalation slurry is centrifuged and the supernatant is discarded, pure water is added to the remaining precipitate, and layer separation (delamination) is performed by stirring, for example, by handshake or automatic shaker. Removal of undelaminate material can be done by centrifuging, discarding the supernatant, and then washing the remaining precipitate with water. For example, (i) pure water is added to the remaining precipitate after discarding the supernatant and stirred, (ii) centrifuged, and (iii) the supernatant is recovered. One possible method is to repeat the operations (i) to (iii) once or more, preferably two or more, and no more than ten times, to obtain a supernatant liquid containing single-layer and thin-layer MXene particles as the delamination product. Alternatively, this supernatant liquid may be centrifuged, the supernatant liquid after centrifugation discarded, and clay containing single-layer and thin-layer MXene particles may be obtained as the delamination product.

[0076] The delamination treatment materials described above may be further washed before being subjected to the next process.

[0077] In one embodiment, the above cleaning may be carried out using a cleaning solution, typically by mixing the delamination product with the cleaning solution. In another embodiment, the above cleaning may be carried out by acid-treating the delamination product and then mixing the acid-treated product with the cleaning solution. The acid used for such acid treatment may be an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, hydroiodic acid, hydrobromic acid, or hydrofluoric acid; or an organic acid such as acetic acid, citric acid, oxalic acid, benzoic acid, or sorbic acid, and the concentration of the acid in the acid solution may be adjusted as appropriate depending on the delamination product. Furthermore, the cleaning with the above cleaning solution may be carried out by sequentially performing steps (i) adding the cleaning solution (to the treated product or the remaining precipitate obtained in (iii) below) and stirring, step (ii) centrifuging the stirred product, and step (iii) discarding the supernatant after centrifugation, and steps (i) to (iii) may be repeated two or more times, for example, up to 15 times. The above stirring can be carried out using a handshake, automatic shaker, shear mixer, pot mill, etc. The acid treatment only needs to be performed once or more times, and if necessary, the operation of mixing with a fresh acid solution (an acid solution not used in the acid treatment) and stirring may be performed two or more times, for example, within a range of 10 times or less. The washing solution can be the same as the washing solution in step (c), for example, water may be used as the washing solution, and pure water is preferred. The above mixing can be carried out by the same method as the mixing method in step (c), for example, stirring, centrifugation, etc. Examples of stirring methods include using a handshake, automatic shaker, shear mixer, pot mill, etc.

[0078] ·Process (f) In step (f), the delamination material and N-methylformamide are mixed. This allows N-methylformamide to be inserted between the layers. In step (f), the mixing of the delamination material and N-methylformamide means mixing them from a state where the delamination material and N-methylformamide are completely separated to a state where N-methylformamide can be present in the delamination material. For example, the mixing of the delamination material and N-methylformamide may include stirring the undried delamination material and N-methylformamide, and impregnating the dried delamination material with N-methylformamide.

[0079] The method for mixing the delamination product and N-methylformamide is not particularly limited and can be carried out by known methods. For example, one method is to stir and disperse the N-methylformamide and the delamination product. Stirring methods include stirring using a mechanical shaker, vortex mixer, homogenizer, ultrasonic treatment, handshake, automatic shaker, etc. The degree of stirring, such as the stirring speed and stirring time, can be adjusted according to the amount and concentration of the product to be treated. Another mixing method is to impregnate the dried delamination product with N-methylformamide. Such impregnation can be carried out, for example, by immersing the dried delamination product in N-methylformamide. In one embodiment, the content of the delamination product in a mixture containing the delamination product and N-methylformamide may be, for example, 0.5% by mass or more and 10% by mass or less, and more specifically, 1% by mass or more and 5% by mass or less.

[0080] When mixing the delamination treatment product with N-methylformamide, other dispersion media may be present. Examples of other dispersion media include water. The N-methylformamide and other dispersion media may be mixed such that the volume ratio of N-methylformamide to other dispersion media (N-methylformamide / other dispersion media) is, for example, 50 / 50 or more, preferably 55 / 45 or more.

[0081] ·Process (g) In step (g), the delamination treatment material may be dried before being subjected to step (f). This removes the moisture contained in the delamination treatment material. Hereinafter, the material obtained by drying the delamination treatment material will also be referred to as the dried material.

[0082] The drying method may be carried out under mild conditions such as natural drying (typically placed in an air atmosphere at room temperature and atmospheric pressure) or air drying (blowing air), or under relatively active conditions such as hot air drying (blowing heated air), heat drying, vacuum drying and / or freeze drying. In step (g), it is preferable to remove as much water as possible contained in the delamination material, and from this viewpoint, drying under active conditions is preferable. Also, in step (g), it is preferable to remove water without heating to a high temperature. For example, the drying temperature in step (g) may be preferably 190°C or lower, more preferably 150°C or lower, even further 140°C or lower, and particularly 120°C or lower. In one embodiment, it may be less than 20°C, and even further 10°C or lower. From this viewpoint, vacuum drying and / or freeze drying are preferred as drying methods, and freeze drying is even more preferred.

[0083] In this drying process, the dispersion medium can be removed from the delamination treatment material, and typically a film-like dried material is obtained.

[0084] If step (g) is included, the method for producing the two-dimensional particles is, for example, (a) Prepare a predetermined precursor, (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mixing the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product, and (e) Stirring the intercalation-treated material to obtain a delamination-treated material in which the intercalation-treated material is delaminated. (g) Drying the delamination-treated material to obtain a dried product, and (f1) This may include impregnating the dried delamination product with N-methylformamide.

[0085] In this embodiment, when impregnating the dried delamination product with N-methylformamide, the amount of the dried delamination product may be, for example, 0.5 parts by mass or more and 1 part by mass or more and 5 parts by mass per 100 parts by mass of N-methylformamide.

[0086] In one embodiment, the content of two-dimensional particles in the film of this embodiment may preferably be 70% by volume or more and 100% by volume or less, more preferably 90% by volume or more and 100% by volume or less, and even more preferably 95% by volume or more and 100% by volume or less.

[0087] In one embodiment, the film of this embodiment may further contain a resin in addition to the two-dimensional particles. Examples of such resins include acrylic resin, polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, polycarbonate resin, polyurethane resin, polystyrene resin, polyether resin, polylactic acid, and polyvinyl alcohol. Furthermore, the above-mentioned film may further contain other additives.

[0088] The method for manufacturing a film in this embodiment includes forming a film using the above-mentioned two-dimensional particles, and in one embodiment, (a) Prepare a predetermined precursor, (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching-cleaned material with a metal compound containing a metal cation to obtain an intercalated material in which the metal cation is intercalated into the etching-cleaned material. (e) Stirring the intercalation-treated material to obtain a delamination-treated material in which the intercalation-treated material is delaminated. (f) Mixing the above delamination treatment product with N-methylformamide to obtain a mixture, and (h) Form a precursor film using the above mixture, (i) The process includes drying the precursor film under normal pressure to form a film.

[0089] In another embodiment, the method for manufacturing the film in this embodiment is: (a) Prepare a predetermined precursor, (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching-cleaned material with a metal compound containing a metal cation to obtain an intercalated material in which the metal cation is intercalated into the etching-cleaned material. (e) Stirring the intercalation-treated material to obtain a delamination-treated material in which the intercalation-treated material is delaminated. (g) Dry the delamination-treated material to obtain a dried product. (f1) Permeating the dried delamination product with N-methylformamide to form a precursor film, and (i) The precursor film may be dried under normal pressure to form a film.

[0090] The mixture in step (f) above comprises the delamination product and / or the dried product and N-methylformamide, and may further contain the resin as needed. The formation of the precursor film can be carried out, for example, by suction filtration of the mixture, or by coating the mixture and drying it under atmospheric pressure one or more times.

[0091] One method for applying the above-mentioned mixture is, for example, by spraying. The spraying method may be, for example, an airless spraying method or an air spraying method, and specifically, a method of spraying using a nozzle such as a one-fluid nozzle, a two-fluid nozzle, or an airbrush.

[0092] The above mixture may contain a dispersion medium other than N-methylformamide. Examples of other dispersion media include water. N-methylformamide and the other dispersion medium may be mixed such that the volume ratio of N-methylformamide to the other dispersion medium (N-methylformamide / other dispersion medium) is, for example, 50 / 50 or more, preferably 55 / 45 or more.

[0093] In one embodiment, the drying of the precursor film may be carried out under atmospheric pressure. The precursor film comprises two-dimensional particles, N-methylformamide, and other dispersion media used as needed. By drying the precursor film, at least a portion of the N-methylformamide and other dispersion media contained in the precursor film is removed to obtain the film. Carrying out under atmospheric pressure means carrying out the process under conditions without vacuum or pressurization. In one embodiment, the atmospheric pressure may be 900 hPa or more and 1,200 hPa or less as absolute pressure, and more preferably 950 hPa or more and 1,160 hPa or less as absolute pressure. The drying temperature may be, for example, 190°C or less, preferably 150°C or less, more preferably 140°C or less, even more preferably 120°C or less, and even more preferably 110°C or less, for example 80°C or more, preferably 90°C or more. The drying time is, for example, 30 minutes or more and 10 hours or less, preferably 1 hour or more and 5 hours or less. By drying the dispersion medium under these conditions, it may be easier to produce a film in which N-methylformamide exists between the layers of two-dimensional particles.

[0094] One application of the film of this embodiment is an electrode. Such an electrode only needs to include the above-mentioned film, and is not limited to a specific form. The electrode can range from a solid state to a flexible, soft state.

[0095] In the electrode of this embodiment, the film may be exposed to the outside air so as to be in direct contact with the object to be measured, or it may be covered with a substrate and / or a protective film.

[0096] If the electrode of this embodiment has a substrate, the film and the substrate may be in direct contact. The material of the substrate is not particularly limited and may be an inorganic material such as ceramic or glass, or an organic material. Examples of such organic materials include flexible organic materials, specifically thermoplastic polyurethane elastomer (TPU), PET film, polyimide film, etc. The material of the substrate may also be a fibrous material such as paper or cloth (for example, a sheet-like fibrous material).

[0097] The protective layer described above may be a layer that covers at least a part or all of the film, and preferably a layer that covers at least a part of the film. The protective layer may be an organic material, and specifically may be a resin such as acrylic resin, polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, polycarbonate resin, polyurethane resin, polystyrene resin, polyether resin, polylactic acid, or polyvinyl alcohol.

[0098] The electrodes described above can be used for any suitable application. Examples include counter electrodes and reference electrodes in electrochemical measurements, electrodes for electrochemical capacitors, battery electrodes, bioelectrodes, sensor electrodes, and antenna electrodes. They can also be used in applications requiring high conductivity (reducing the decrease in initial conductivity and preventing oxidation), such as electromagnetic shielding (EMI shielding). Details of these applications are described below.

[0099] The electrodes are not particularly limited, but may include, for example, electrodes for capacitors, electrodes for batteries, electrodes for biosignal sensing, electrodes for sensors, and electrodes for antennas. By using the above film, large-capacity capacitors and batteries, low-impedance biosignal sensing electrodes, and highly sensitive sensors and antennas can be obtained even in a smaller volume (device occupied volume).

[0100] A capacitor can be an electrochemical capacitor. An electrochemical capacitor is a capacitor that utilizes the capacitance that arises from a physicochemical reaction between electrodes (electrode active material) and ions in an electrolyte (electrolyte ions), and can be used as a device for storing electrical energy (energy storage device). A battery can be a chemical battery that can be repeatedly charged and discharged. A battery can be, for example, a lithium-ion battery, a magnesium-ion battery, a lithium-sulfur battery, a sodium-ion battery, etc., but is not limited to these.

[0101] Biosignal sensing electrodes are electrodes used to acquire biological signals. Biosignal sensing electrodes may, but are not limited to, electrodes used to measure EEG (electroencephalography), ECG (electrocardiogram), EMG (electromyography), and EIT (electrical impedance tomography).

[0102] Sensor electrodes are electrodes used to detect a target substance, state, abnormality, etc. Sensors may include, but are not limited to, gas sensors or biosensors (chemical sensors that utilize molecular recognition mechanisms of biological origin).

[0103] Antenna electrodes are electrodes that radiate electromagnetic waves into space and / or receive electromagnetic waves in space. The antennas that antenna electrodes make up are not particularly limited and include antennas for mobile communications such as mobile phones (so-called 3G, 4G, and 5G antennas), antennas for RFID, or antennas for NFC (Near Field Communication).

[0104] The above describes in detail a film and two-dimensional particles in one embodiment of the present disclosure, but various modifications are possible. It should be noted that the film and two-dimensional particles of the present disclosure may be manufactured by methods different from those described in the above embodiment, and that the manufacturing methods of the film and two-dimensional particles of the present disclosure are not limited to those that provide the film and two-dimensional particles in the above embodiment. [Examples]

[0105] The present disclosure will be further illustrated by the following embodiments, but will not be limited thereto.

[0106] [Example 1] [Fabrication of 2D particles] In Example 1, two-dimensional particles were prepared by sequentially carrying out the following steps, as detailed below: (1) preparation of the precursor (MAX), (2) etching of the precursor, (3) washing, (4) intercalation, (5) delamination and washing, (6) drying, and (7) mixing with N-methylformamide.

[0107] (1) Preparation of the precursor (MAX) TiC powder, Ti powder, and Al powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were placed in a ball mill containing zirconia balls in a molar ratio of 2:1:1 and mixed for 24 hours. The resulting mixed powder was calcined at 1350°C for 2 hours under an Ar atmosphere. The resulting calcined body (block) was then pulverized with an end mill to a maximum size of 40 μm or less. This yielded Ti3AlC2 particles as MAX particles.

[0108] (2) Etching of the precursor (ACID method) Using the Ti3AlC2 particles (powder) prepared by the above method, etching was performed under the following etching conditions to obtain a solid-liquid mixture (slurry) containing solid components derived from the Ti3AlC2 powder. (Etching conditions) • Precursor: Ti3AlC2 (passed through a sieve with a mesh size of 45 μm) • Etching solution composition: 49% HF 6 mL H2O 18mL HCl (12M) 36mL • Amount of precursor added: 3.0g • Etching container: 100mL iBoy Etching temperature: 35℃ Etching time: 24 hours • Stirrer rotation speed: 400 rpm

[0109] (3) Washing The slurry was divided into two portions and placed into two 50 mL centrifuge tubes. Centrifugation was performed at 3500 G using a centrifuge, and the supernatant was discarded. 40 mL of pure water was added to the remaining precipitate in each centrifuge tube, and the process of separating and removing the supernatant was repeated 11 times by centrifugation at 3500 G. After the final centrifugation, the supernatant was discarded, and Ti3C2T was extracted. x - A water-based clay was obtained.

[0110] (4) Intercalation The above Ti3C2T sLi intercalation was performed on clay with a water medium using LiCl as the Li-containing compound, stirring at 20°C to 25°C for 12 hours, under the following conditions. (Conditions for intercalation of Li) ·Ti3C2T x - Moisture-based clay (MXene after washing): Solid content 0.75g • LiCl: 0.75g ·Pure water: 37.2g Intercalation container: 100mL iBoy ·Temperature: 20℃ or higher and 25℃ or lower (room temperature) ·Time: 10h • Stirrer rotation speed: 800 rpm

[0111] (5) Delamination and washing The above Ti3C2T x - To the water medium clay, (i) 40 mL of pure water was added and stirred in a shaker for 15 minutes, then (ii) centrifuged at 3,500 G, and (iii) the supernatant was collected as a single layer MXene-containing liquid. This procedure (i) to (iii) was repeated a total of four times to obtain a single layer MXene-containing supernatant. Furthermore, this supernatant was centrifuged using a centrifuge at 4,300 G for 2 hours, and the supernatant was discarded to obtain clay containing delamination material.

[0112] (6) Drying The clay containing the delamination treatment described above was frozen for 16 hours, followed by freeze-drying for 20 hours to obtain a dried product. The freezing temperature during freezing and freeze-drying was -35°C or lower, and the pressure during freeze-drying was 30 Pa or lower.

[0113] (7) Mixing with N-methylformamide The above-mentioned dried product and N-methylformamide were mixed so that the content of the dried product in the resulting mixture was 1.5% by mass. Next, this mixture was dispersed for 15 minutes using an ultrasonic cleaner (AS482, manufactured by AS ONE Corporation) to obtain a slurry containing two-dimensional particles.

[0114] [Membrane fabrication] The slurry was placed in a 25 mL syringe and then set in a spray coater. Next, a 3 cm square glass substrate (manufactured by SCHOTT, Tempax) was cleaned with oxygen plasma and set on the suction-equipped stage of the spray coater. The slurry was applied to the cleaned surface and dried with hot air, a process that was repeated 20 times to produce a spray film. (Conditions for spray coating) • Atomization pressure: 0.5 MPa • Distance between nozzle tip and substrate: 15cm • Fluid delivery rate: 5 mL / s ·Sweep speed: 150mm / s Stage heater: 100~150℃

[0115] The above spray film was dried at 100°C for 2 hours using an atmospheric pressure oven to create a film.

[0116] (Measurement of N-methylformamide content) In an inert gas atmosphere (He gas atmosphere), a thermogravimetric analyzer (NETZSCH) was used to heat the film from room temperature to 100°C at a rate of 20°C / min, hold it at 100°C for 10 minutes, and then heat it from 100°C to 150°C at a rate of 20°C / min. Subsequently, the film was heated from 150°C to 450°C at a rate of 20°C / min, and thermogravimetric analysis of the film was performed. The difference between the mass of the film at 150°C and the mass of the film at 450°C was taken as the N-methylformamide content, and the mass of the film at 450°C was taken as the mass of Ti3C2, and the content of N-methylformamide (moles) per mole of Ti3C2 was calculated.

[0117] (interlayer distance (d 002 (Measurement) As follows, the interlayer distance (d 002 Measurements were taken of the following: (a) The film fabricated on the glass substrate was cut into 2 cm squares, and XRD measurements (characteristic X-ray: CuKα 1.541 Å) were performed using an X-ray diffractometer (manufactured by Rigaku Corporation, SmartLab3 and SmartLab Studio II software) to obtain XRD profiles of the θ-axis scan in the range of 2θ = 2 to 50 degrees. The step size was 0.02 degrees, and the scan speed was 5 degrees / minute. (b) Around 2θ = 7 degrees, MXene(Ti3C2T s A peak corresponding to the (002) plane appears, so by applying the θ, n=1, and λ=1.541 Å (wavelength of CuKα) of the peak to Bragg's equation (2dsinθ=nλ), the interplanar spacing d of the (002) plane is obtained. 002 The value was calculated as the interlayer distance. The interlayer distance was 13.2 Å, which is wider than the interlayer distance (10.9 Å) in the film of Comparative Example 4, which was prepared without using N-methylformamide. This confirms that N-methylformamide is present between the layers in the two-dimensional particles contained in the film of Example 1.

[0118] (Measurement of electrical conductivity) The conductivity of the obtained film was determined. For each sample, resistivity (Ω) and thickness (μm) were measured at three locations, and the conductivity (S / cm) was calculated from these measurements. The average of these three conductivity values ​​was then adopted. For resistivity measurement, a low-resistance conductivity meter (Loresta AX MCP-T370, Mitsubishi Chemical Analytical Corporation) was used to measure the surface resistance of the film using the four-terminal method. For thickness measurement, a stylus-type surface shape analyzer (DEKTAK8, Bruker Japan Co., Ltd.) was used. The thickness immediately before the start of the conductivity change measurement described later was defined as the film thickness. Then, the volume resistivity was calculated from the obtained surface resistance and film thickness, and the conductivity was calculated by taking the reciprocal of this value, which was defined as E0.

[0119] (Measurement of changes in conductivity) A membrane was placed in a constant temperature and humidity chamber with a relative humidity of 85% and a temperature of 60°C. After standing for one day, the conductivity was measured and defined as E. The conductivity retention rate was calculated by dividing E by E0.

[0120] [Example 2] [Fabrication of 2D particles] (1) Preparation of the precursor (MAX), (2) Etching of the precursor, (3) Washing, (4) Intercalation, and (5) Delamination and washing were performed in the same manner as in Example 1 to obtain a delaminate product, and then the following step (7) was performed to produce two-dimensional particles.

[0121] (7) Mixing with N-methylformamide A mixture of 55 parts by volume of N-methylformamide and 45 parts by volume of water was prepared as a mixed dispersion medium. The delamination material and the mixed dispersion medium were then mixed so that the content of the delamination material in the resulting mixture was 1.5% by mass. Subsequently, this mixture was dispersed for 15 minutes using an ultrasonic cleaner (AS ONE Corporation, AS482) to obtain a slurry containing two-dimensional particles.

[0122] [Membrane fabrication] Using the slurry obtained by the above method, a spray film was prepared in the same manner as in Example 1. The spray film was dried in an atmospheric pressure oven at 100°C for 2 hours to form a film.

[0123] (Measurement of N-methylformamide content) In an inert gas atmosphere (nitrogen gas atmosphere), a thermogravimetric analyzer (manufactured by Hitachi High-Tech Science) was used to heat the film from room temperature to 100°C at a heating rate of 10°C / min, hold it at 100°C for 10 minutes, and then heat it from 100°C to 150°C at a heating rate of 10°C / min. Subsequently, the film was heated from 150°C to 450°C at a heating rate of 10°C / min, and thermogravimetric analysis of the film was performed. The difference between the mass of the film at 150°C and the mass of the film at 450°C was taken as the N-methylformamide content, and the mass of the film at 450°C was taken as the mass of Ti3C2, and the content of N-methylformamide (moles) per mole of Ti3C2 was calculated.

[0124] (interlayer distance (d 002 (Measurement) Similar to Example 1, the correlation distance (d 002 Measurements of ) were taken. The interlayer distance was 13.0 Å, and it was confirmed that N-methylformamide was present between the layers in the two-dimensional particles contained in the film of Example 2.

[0125] (Measurement of conductivity and changes in conductivity) Conductivity and changes in conductivity were measured in the same manner as in Example 1.

[0126] [Example 3] [Fabrication of 2D particles] (1) Preparation of the precursor (MAX), (2) Etching of the precursor, (3) Washing, (4) Intercalation, (5) Delamination and washing, (6) Drying, and (7) Mixing with N-methylformamide were carried out in the same manner as in Example 1 to obtain a slurry containing two-dimensional particles.

[0127] [Membrane fabrication] A filtration membrane was prepared by suction filtration of the slurry obtained by the above method. A membrane filter (Merck, Durapore, pore size 0.45 μm) was used as the filter for suction filtration. The filtration membrane was dried in an atmospheric pressure oven at 100°C for 2 hours to prepare the membrane.

[0128] (Measurement of N-methylformamide content) Similar to Example 2, 1 mole of M m X n The amount (moles) of N-methylformamide in the given sample was measured.

[0129] (interlayer distance (d 002 (Measurement) Similar to Example 1, the correlation distance (d 002 Measurements of ) were taken. The interlayer distance was 13.4 Å, and it was confirmed that N-methylformamide was present between the layers in the two-dimensional particles contained in the film of Example 3.

[0130] (Measurement of conductivity and changes in conductivity) Conductivity and changes in conductivity were measured in the same manner as in Example 1.

[0131] [Comparative Example 1] [Fabrication of 2D particles] (1) Preparation of the precursor (MAX), (2) Etching of the precursor, (3) Washing, (4) Intercalation, (5) Delamination and washing, (6) Drying, and (7) Mixing with N-methylformamide were carried out in the same manner as in Example 1 to obtain a slurry containing two-dimensional particles.

[0132] [Membrane fabrication] Using the slurry obtained by the above method, a spray film was prepared in the same manner as in Example 1. The spray film was dried at 100°C for 2 hours using an atmospheric pressure oven, and then further dried at 150°C for 16 hours using a vacuum oven to prepare a film.

[0133] (Measurement of N-methylformamide content) Similar to Example 2, 1 mole of M m X n The amount (moles) of N-methylformamide in the given sample was measured.

[0134] (Measurement of conductivity and changes in conductivity) Conductivity and changes in conductivity were measured in the same manner as in Example 1.

[0135] [Comparative Example 2] [Fabrication of 2D particles] (1) Preparation of the precursor (MAX), (2) Etching of the precursor, (3) Washing, (4) Intercalation, (5) Delamination and washing, (6) Drying, and (7) Mixing with N-methylformamide were carried out in the same manner as in Example 1 to obtain a slurry containing two-dimensional particles.

[0136] [Membrane fabrication] Using the slurry obtained by the above method, a filtration membrane was prepared in the same manner as in Example 3. The filtration membrane was dried in a vacuum oven at 200°C for 16 hours to prepare the membrane.

[0137] (Measurement of N-methylformamide content) Similar to Example 2, 1 mole of M m X nThe content (mole) of N-methylformamide with respect to it was measured.

[0138] (Measurement of conductivity and change in conductivity) Similar to Example 1, the measurement of conductivity and change in conductivity was carried out.

[0139] [Comparative Example 3] [Preparation of two-dimensional particles] (1) Preparation of precursor (MAX), (2) etching of the precursor, (3) washing, (4) intercalation, (5) delamination and washing, (6) drying, (7) mixing with N-methylformamide were carried out in the same manner as in Example 1 to obtain a slurry containing two-dimensional particles.

[0140] [Preparation of membrane] Using the slurry obtained by the above method, a filtration membrane was prepared in the same manner as in Example 3. After drying the filtration membrane at 100 °C for 2 hours using an atmospheric oven, it was further dried at 150 °C for 16 hours using a vacuum oven to prepare a membrane.

[0141] (Measurement of N-methylformamide content) Similar to Example 2, the content (mole) of N-methylformamide with respect to 1 mole of M m X n was measured.

[0142] (Measurement of conductivity and change in conductivity) Similar to Example 1, the measurement of conductivity and change in conductivity was carried out. ​​​​​​​​​​​​A predetermined amount of the dried material was placed in a 50 mL centrifuge tube, and pure water was added. At this time, the amount of pure water added was adjusted so that the concentration of the delamination material in the mixture was 1.5% by mass. Then, the mixture was stirred in a shaker for 15 minutes to obtain a slurry.

[0145] Next, the slurry was placed in a 25 mL syringe and set in the spray coater. Then, a 3 cm square glass substrate (SCHOTT, Tempax) was cleaned with oxygen plasma and set on the suction stage of the spray coater. The slurry was applied to the cleaned surface and dried with hot air, and this process was repeated 20 times to produce a spray film. (Conditions for spray coating) • Atomization pressure: 0.5 MPa • Distance between nozzle tip and substrate: 15cm • Fluid delivery rate: 5 mL / s ·Sweep speed: 150mm / s Stage heater: 45℃

[0146] The spray film was dried in an atmospheric pressure oven at 80°C for 2 hours, and then further dried in a vacuum oven at 150°C for 16 hours to produce a film.

[0147] (Measurement of N-methylformamide content) Similar to Example 2, 1 mole of M m X n The amount (moles) of N-methylformamide in the given sample was measured.

[0148] (interlayer distance (d 002 (Measurement) Similar to Example 1, the correlation distance (d 002 Measurements were taken. The interlayer distance was 10.9 Å.

[0149] (Measurement of conductivity and changes in conductivity) Conductivity and changes in conductivity were measured in the same manner as in Example 1.

[0150] [Comparative Example 5] [Preparation of two-dimensional particles] (1) Preparation of the precursor (MAX), (2) etching of the precursor, (3) washing, (4) intercalation, (5) delamination and washing, and (6) drying were carried out in the same manner as in Example 1 to obtain a dried product.

[0151] [Preparation of film] The above dried product was taken into a 50 mL centrifuge tube of a predetermined amount, and pure water was added. At this time, the amount of pure water added was adjusted so that the concentration of the delaminated product in the mixture was 1.5% by mass. Then, it was stirred with a shaker for 15 minutes to obtain a slurry.

[0152] The above slurry was suction filtered to produce a filter membrane. A membrane filter (Durapore, pore size 0.45 μm, manufactured by Merck) was used as the filter for suction filtration. The filter membrane was dried at 150 °C for 16 hours using a vacuum oven to produce a membrane.

[0153] (Measurement of N-methylformamide content) Similar to Example 2, the content (mol) of N-methylformamide with respect to 1 mol of M m X n was measured.

[0154] (Measurement of conductivity and change in conductivity) Similar to Example 1, the measurement of conductivity and change in conductivity was carried out.

[0155] 1 mol of M m X n The content of N-methylformamide (NMF), conductivity, and conductivity retention rate with respect to are shown in Table 1.

[0156] [Table 1]

[0157] Examples 1 to 3 are examples of the present disclosure, in which the decrease in conductivity over time is suppressed, and particularly, even under high temperature and high humidity, the decrease in conductivity over time is suppressed.

[0158] Comparative Examples 1-5 use 1 mole of M m X n In cases where the NMF content was less than 0.104 moles, it was confirmed that the conductivity decreased over time.

[0159] This disclosure includes the following: <1> It is a film containing two-dimensional particles, The above two-dimensional particle is a two-dimensional particle having one or more layers, and containing N-methylformamide. The above layer is represented by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer body, The above N-methylformamide is placed between two adjacent layers. The content of N-methylformamide in the above film is 1 mole of M m X n A membrane containing 0.104 moles or more. <2> The above layer body includes Ti3C2, <1> The membrane described above. <3> (a) The following equation: M m AX n (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal containing at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product. (e) Stirring the intercalation-treated material to obtain a delamination-treated material in which the intercalation-treated material is delaminated. (f) Mixing the above delamination treatment product with N-methylformamide to obtain a mixture, and (h) Form a precursor film using the above mixture, (i) A method for producing a film, comprising drying the precursor film under normal pressure to form a film. <4> The drying temperature when drying the above precursor film is 190°C or lower. <3> The manufacturing method described above. <5> (a) The following equation: M m AX n (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal containing at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product. (e) Stirring the intercalation-treated material to obtain a delamination-treated material in which the intercalation-treated material is delaminated. (g) Dry the delamination-treated material to obtain a dried product. (f1) Permeating the dried delamination product with N-methylformamide to form a precursor film, and (i) A method for producing a film, comprising drying the precursor film under normal pressure to form a film. [Explanation of symbols]

[0160] 1a, 1b layer body (M m X n layer) 3a, 5a, 3b, 5b Modifier or Terminus T 7a, 7b MXene layer 10, 10a, 10b MXene particles (two-dimensional particles of layered material)

Claims

1. It is a film containing two-dimensional particles, The aforementioned two-dimensional particle is a two-dimensional particle having one or more layers, and containing N-methylformamide. The aforementioned layer is given by the following formula: M ｍ X ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal,) X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom), The N-methylformamide is placed between two adjacent layers. The content of N-methylformamide in the aforementioned film is 1 mole of M ｍ X ｎ A membrane containing 0.104 moles or more.

2. The aforementioned layer body is Ti ３ C ２ The film according to claim 1, comprising:

3. (a) The following formula: M ｍ AX ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal, which contains at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product. (e) Stirring the intercalation treated material to obtain a delamination treated material in which the intercalation treated material is delaminated. (f) Mixing the above delamination treatment product with N-methylformamide to obtain a mixture, and (h) Form a precursor film using the above mixture, (i) A method for producing a film according to claim 1, comprising drying the precursor film under normal pressure to form a film.

4. The manufacturing method according to claim 3, wherein the drying temperature when drying the above-mentioned precursor film is 190°C or lower.

5. (a) The following formula: M ｍ AX ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal, which contains at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mix the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product. (e) Stirring the intercalation treated material to obtain a delamination treated material in which the intercalation treated material is delaminated. (g) Dry the delamination-treated material to obtain a dried product. (f1) Permeating the dried delamination product with N-methylformamide to form a precursor film, and (i) A method for producing a film according to claim 1, comprising drying the precursor film under normal pressure to form a film.

Images