KR102204890B1 - Method of mxene thin film and mxene thin film manufactured therefrom - Google Patents

Abstract

The present invention relates to a method of manufacturing a Maxine thin film that forms a thin film on the surface of a dispersion containing Maxine, and to a Maxine thin film prepared therefrom. In addition, the present invention relates to a method of manufacturing a Maxine composite thin film for forming a thin film on the surface of a dispersion containing Maxine and nanomaterials, and to a Maxine composite thin film prepared therefrom.

Description

Manufacturing method of Maxine thin film and Maxine thin film manufactured therefrom {METHOD OF MXENE THIN FILM AND MXENE THIN FILM MANUFACTURED THEREFROM}

The present invention relates to a method of manufacturing a Maxine thin film and to a Maxine thin film prepared therefrom. In addition, the present invention relates to a method for manufacturing a Maxine composite thin film further comprising a nanomaterial, and to a Maxine composite thin film prepared therefrom.

Graphene, a single atomic layer material composed of honeycomb-shaped carbon atoms, has attracted a lot of attention worldwide for its excellent physical properties. As such research on graphene is explosively interested, interest in two-dimensional materials similar to graphene is increasing in recent years.

One of these two-dimensional materials, Maxine (MXene), is a two-dimensional material obtained from MAX having a three-dimensional crystal structure consisting of an M layer, an A layer, and an X layer, where M is a transition metal and A is a group 13 or 14 element. , X is carbon or nitrogen. This max is a crystalline substance in which A, which is a different metal element than MX or M of ceramic properties, is combined and has excellent physical properties such as electrical conductivity, oxidation resistance, and machinability. In theory, there may be thousands or hundreds of them, but it is known that up to now 300 types of max have been synthesized.

The max is a three-dimensional material, but unlike graphite or metal dichalcogenide material, transition metal carbide is stacked on each other by weak chemical bonds between A element and M transition metal. Therefore, it is not easy to peel it into a two-dimensional structure using a general mechanical peeling method or a chemical peeling method.

Recently, a two-dimensional material was obtained by exfoliating Max using a strong acid, and it was named as Maxine. The Maxine has a two-dimensional plate-like structure like graphene, but a functional group such as -O-, -OH, or -F is obtained in the form of bonded to a transition metal M on the surface of Maxine peeled under strong acid conditions. There is a problem in that the characteristics of Maxine are altered according to the surface formula of.

In addition, there have been many attempts to manufacture Maxine as a thin film. However, since Maxine is not stable at high temperatures, chemical vapor deposition is limited, so the existing solution processes such as spin coating and spraying have been made. A thin film is manufactured using a method such as spray coating or dip coating. Such an existing solution process method has a limitation in obtaining a uniform thin film by maintaining low coverage by unevenly controlling the thickness of the Maxine thin film.

Accordingly, in order to realize the excellent physical properties of Maxine, it is necessary to develop a thin film of Maxine that can provide excellent coverage with a single layer or a uniform multilayer structure.

In order to solve the above problems, an object of the present invention is to provide a method of manufacturing a Maxine thin film and a Maxine composite thin film having a single layer or a uniform multilayer structure.

Another object of the present invention is to provide a method of manufacturing a Maxine thin film and a Maxine composite thin film capable of providing a uniform thin film over a large area.

Another object of the present invention is to provide a Maxine thin film and a Maxine composite thin film capable of realizing high electromagnetic wave shielding efficiency compared to thickness and weight.

As a result of research in order to achieve the above object, the method of manufacturing a Maxine thin film according to the present invention comprises the steps of: a) preparing a first dispersion containing Maxine; And b) forming a thin film on the surface of the first dispersion. Includes.

Step b) according to an aspect of the present invention may be forming a thin film at the interface by adding an immiscible organic solvent to the first dispersion.

Step b) according to an aspect of the present invention may be to induce self-assembly at the interface to form a thin film.

An acid solution may be further included in the first dispersion of step a) according to an aspect of the present invention.

The organic solvent according to an aspect of the present invention may be volatile.

After the step b) according to an aspect of the present invention, a step of transferring the thin film to the substrate may be further included.

The transferring step according to an embodiment of the present invention may be repeated two or more times to form a multilayer thin film.

After the step b) according to an aspect of the present invention, it may further include a step of heat-treating the thin film at 300 to 500 ℃.

In another aspect of the present invention, A) preparing a mixed dispersion by mixing a first dispersion containing maxine and a second dispersion containing nanomaterials; And B) forming a thin film on the surface of the mixed dispersion. It is a method of manufacturing a Maxine composite thin film comprising a.

The step B) according to an aspect of the present invention may be forming a thin film at the interface by adding an immiscible organic solvent to the first mixed dispersion.

The nanomaterial according to an aspect of the present invention may be any one or a mixture of two or more selected from carbon-based materials, ceramic-based materials, and organic materials.

The first dispersion and the second dispersion according to an aspect of the present invention may be mixed in a weight ratio of 1:0.5 to 1:5.

Another aspect of the present invention is a Maxine thin film manufactured by the above-described method for producing a Maxine thin film and having a coverage of 90% or more.

The Maxine thin film according to an aspect of the present invention may have a single layer or a multilayer structure of two or more layers.

The Maxine thin film according to an aspect of the present invention may have an electromagnetic wave shielding efficiency (specific EMI SE) of 1.0×10 ⁴ dB·cm 2 /g or more.

The Maxine thin film according to an aspect of the present invention may have a contact angle of 90° or more after a heat treatment step.

Another aspect of the present invention is a Maxine composite thin film prepared by the method for manufacturing a Maxine composite thin film described above, and including Maxine and nanomaterials.

The Maxine composite thin film according to an aspect of the present invention may have a shape in which nanomaterials are dispersed in Maxine in a layer-by-layer (LBL) method or arranged on the same plane.

In the Maxine composite thin film according to an aspect of the present invention, Maxine and nanomaterials may be in a weight ratio of 1:0.01 to 1:2.

The method of manufacturing a Maxine thin film and a Maxine composite thin film according to the present invention has the advantage of providing a Maxine thin film and a Maxine composite thin film having a single layer or a multilayer structure having a uniform thickness over a large area.

In addition, the Maxine thin film and the Maxine composite thin film manufactured by the manufacturing method according to the present invention have the advantage of having a uniform and high coverage.

In addition, the Maxine thin film and the Maxine composite thin film according to the present invention have the advantage of being able to control the transmittance and electrical conductivity by controlling the thickness.

In addition, the Maxine thin film and the Maxine composite thin film according to the present invention have an advantage in that an excellent electromagnetic wave shielding effect can be implemented even at a thin thickness of a nanometer level.

In addition, the Maxine composite thin film according to the present invention has the advantage of being able to manufacture a uniform thin film at a thin thickness even when a multidimensional nanomaterial is further included.

1 is a photograph of visual observation of a Maxine thin film according to a transfer substrate according to an embodiment of the present invention. Fig. 1A is transferred to a glass substrate, and Fig. 1B is transferred to a polyethylene terephthalate film.
2 is a photograph of the Maxine thin film of Example 1 according to an embodiment of the present invention observed with a scanning electron microscope.
3 is a photograph of a Maxine thin film of Comparative Example 1 observed with a scanning electron microscope according to a comparative example of the present invention.
4 is a graph showing a result of measuring absorbance according to the number of transfers of a Maxine thin film according to an embodiment of the present invention.
5 is an XPS analysis result values according to heat treatment of a Maxine thin film manufactured according to an embodiment of the present invention. 5A is an XPS spectrum result for Ti2p, and FIG. 5B is an XPS spectrum result for O1s.
6 is a result of measuring a contact angle according to heat treatment of a Maxine thin film manufactured according to an embodiment of the present invention.
7 is a sheet resistance, charge mobility, and charge carrier density values according to heat treatment of a Maxine thin film manufactured according to an embodiment of the present invention.
8 is a result of measuring the electromagnetic wave shielding decibels according to heat treatment compared to the number of transfers of the Maxine thin film in an embodiment of the present invention.
9 is a graph comparing the density and thickness of a Maxine thin film and a conventional electromagnetic shielding material and electromagnetic shielding efficiency (specific EMI SE) according to an embodiment of the present invention.
10 is a photograph of a Maxine composite thin film including Maxine and graphene prepared according to an embodiment of the present invention observed with a scanning electron microscope.
11 is a photograph of a Maxine composite thin film including Maxine and carbon nanotubes manufactured according to an embodiment of the present invention observed with a scanning electron microscope.

Hereinafter, a method of manufacturing a Maxine thin film according to the present invention and a Maxine thin film prepared therefrom will be described in more detail through Examples. However, the following examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

In addition, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The terms used in the description herein are merely for effectively describing specific embodiments, and are not intended to limit the invention.

The conventional manufacturing method of Maxine thin film has a problem in that it is difficult to manufacture a single layer, and even if a single layer is formed, the thickness uniformity is not good, so that the coverage is significantly lowered, thereby deteriorating the inherent properties of Maxine. Accordingly, there is a need to develop a method of manufacturing a Maxine thin film capable of implementing excellent physical properties while having a uniform thickness even in a single layer or nanometer-level structure.

As a result of research in order to achieve the above object, the method of manufacturing a Maxine thin film according to the present invention comprises the steps of: a) preparing a first dispersion containing Maxine; And b) forming a thin film on the surface of the first dispersion. Includes.

The Maxine thin film manufactured through the method of manufacturing a Maxine thin film according to the present invention may implement excellent electrical conductivity and electromagnetic wave shielding effect compared to the thickness, and may have high coverage.

According to an aspect of the present invention, the first dispersion may include maxine, and for example, maxine may be dispersed in a polar solvent. The polar solvent may be, for example, any one or a mixture of two or more selected from water, ethanol, methanol, dimethylformamide (DMF), dimethylacetamide, n-methylpyrrolidinone (NMP) and tetrahydrofuran. . Preferably, it may be dispersed in water such as purified water or distilled water for which Maxine is easily dispersed.

According to one aspect of the present invention, the first dispersion may contain 0.1 to 10% by weight of Maxine based on the total weight. Preferably, it may contain 0.1 to 5% by weight of Maxine. When included in the above range, it is possible to promote the formation of a thin film on the surface of the first dispersion, thereby producing a thin film having a uniform thickness.

According to an aspect of the present invention, an acid solution may be further included in the first dispersion of step a). Specifically, the acid solution may contain a strong acid, and may be, for example, a strong acid solution containing one or two or more selected from sulfuric acid, nitric acid, hydrochloric acid, and the like. When the acid solution is further included as described above, aggregation between maxines can be prevented, and a large-area thin film can be formed with a uniform thickness.

According to an aspect of the present invention, the acid solution may be further included in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the first dispersion. When included in the above range, it is possible to provide a thin film having a higher coverage by reducing the surface charge of Maxine to prevent aggregation between Maxine.

According to one aspect of the present invention, step b) may be to form a thin film at the interface by adding an immiscible organic solvent to the first dispersion. Specifically, according to an aspect of the present invention, step b) may be to induce self-assembly at the interface to form a thin film.

As described above, in the manufacturing method of the Maxine thin film, a thin film may be formed by inducing self-assembly of Maxine at the interface between the first dispersion containing Maxine and an immiscible organic solvent. When manufactured by the above manufacturing method, a Maxine thin film having a uniform thickness over a large area can be manufactured. In addition, the Maxine thin film manufactured by the above-described manufacturing method can realize excellent electrical conductivity and electromagnetic wave shielding effect compared to the thickness with high coverage.

Specifically, according to an aspect of the present invention, a method of manufacturing a Maxine thin film comprises the steps of: a) preparing an aqueous dispersion containing Maxine; And b) forming a thin film at the interface by adding a non-water-miscible organic solvent to the aqueous dispersion.

According to an aspect of the present invention, the Maxine may be prepared through chemical exfoliation of Max, a precursor.

According to an aspect of the present invention, the max is a three-dimensional crystal structure material consisting of an M layer, an A layer, and an X layer, where M is a transition metal, A is a Group 13 or 14 element, and X is carbon or nitrogen. For a specific example, the MAX structure is a crystal in which at least 10 or more unit layers in the MAX structure are stacked, and a transition metal atomic layer corresponding to Group 13 or 14 is disposed between a two-dimensional transition metal layer or nitride transition metal layer. The two-dimensional transition metal layer or the transition metal nitride layer is bonded to each other by the transition metal atomic layer. That is, a structure in which a single crystal is formed by alternately arranging transition metal atomic layers corresponding to groups 13 or 14 on a transition metal layer or a transition metal nitride layer.

The chemical exfoliation for exfoliating the Max into Maxine may specifically be performed by injecting Max into a strong acid solution containing a fluorine-containing compound. Specific examples of the fluorine-containing compound include lithium fluoride (LiF), sodium fluoride (NaF), magnesium fluoride (MgF ₂ ), strontium fluoride (SrF ₂ ), beryllium fluoride (BeF ₂ ), calcium fluoride (CaF ₂ ), Ammonium fluoride (NH ₄ F), ammonium difluoride (NH ₄ HF ₂ ) and ammonium hexafluoro aluminate ((NH ₄ ) ₃ AlF ₆ ) It may include any one or a mixture of two or more selected from. The strong acid solution used in the reaction may include any one or a mixture of two or more selected from hydrofluoric acid (HF), hydrochloric acid (HCl), and aqueous sulfuric acid (HSO ₄ ).

According to an aspect of the present invention, the chemical exfoliation may be performed at 20 to 100°C, preferably 20 to 60°C for 1 to 48 hours, preferably 10 to 40 hours, but is not limited thereto.

By undergoing such chemical exfoliation, the Maxine A layer is etched to form a transition metal layer and a carbon layer or a transition metal layer and a nitrogen layer to have a transition metal carbide or transition metal nitride structure.

According to one aspect of the present invention, the organic solvent may be immiscible with the polar solvent of the first dispersion, preferably non-water miscible, and is not miscible with the first dispersion containing maxine, so that the liquid-liquid It may be to form an interface. By forming the interface as described above, Maxine can induce self-assembly at the interface.

According to an aspect of the present invention, the organic solvent may be volatile. Specifically, the vapor pressure at 20° C. may be 30 Torr or more. Preferably, the vapor pressure may be 30 to 250 Torr, more preferably 30 to 200 Torr. As described above, the volatile organic solvent forms an interface with the first dispersion and evaporates from the surface to induce a difference in surface tension, thereby further promoting self-assembly of Maxine. In addition, it is possible to form a thin film having a uniform and dense structure while realizing high coverage of the manufactured Maxine thin film.

According to one aspect of the present invention, the organic solvent is not particularly limited as long as it is non-water-miscible and volatile as described above, but specific examples include ethyl acetate, propyl acetate, methyl acetate, diethyl ether, dichloro It may be any one or a mixture of two or more selected from methane, dichlorobenzene, chloroform and hexane.

According to an aspect of the present invention, in step b), the first dispersion and the organic solvent may be provided in a weight ratio of 1:0.01 to 1:1. Preferably, it may be provided in a weight ratio of 1:0.01 to 1:0.5, more preferably 1:0.01 to 1:0.2. If provided in the above range, it is possible to further promote Maxine's self-assembly at the interface.

According to an aspect of the present invention, after step b), a step of transferring the thin film to the substrate may be further included. As described above, since a thin film can be easily transferred onto a substrate, a thin film having a small area of a micrometer level can be provided according to the size of the substrate, and a large-area thin film of millimeters, centimeters, or meters or more can be easily manufactured.

According to an aspect of the present invention, the substrate may be applied in various ways depending on the use of the Maxine thin film, so it is not particularly limited, but specifically, the substrate is any one or two or more selected from polymers, glass, ceramics, metals, etc. It may include a mixture. For example, it may be any one or a mixture of two or more selected from silica, silicon, silicon wafer, glass, metal substrate, and polymer film. In addition, the polymer film may be selected from polyester-based, polycarbonate-based, polyacrylic-based, polyolefin-based and polyethersulfone-based, but is not limited thereto. The metal substrate may include any one or two or more selected from gold, silver, aluminum, copper, nickel, tin, titanium, platinum, and iron, but is not limited thereto.

According to an aspect of the present invention, when transferring a thin film to the substrate, the substrate may be coated with the thin film to be transferred by contacting the substrate with Maxine self-assembled at the interface. For example, after immersing the substrate at the interface between the aqueous dispersion and the organic solvent in which the Maxine thin film is formed, the substrate may be taken out in a direction perpendicular to the interface and transferred. In this case, when the transfer is performed once, a thin film formed of a single layer of Maxine can be obtained. The Maxine thin film thus obtained can be formed in a uniform and dense structure over the entire surface with high coverage, although it is a thin film formed as a single layer.

According to an aspect of the present invention, the transferring step may be repeated two or more times to form a multilayered Maxine thin film. When the transfer is performed more than two times, the substrate on which the Maxine thin film has been transferred once can be transferred so that the Maxine thin film is stacked by contacting the self-assembled Maxine at the interface again. Three or more times can be repeatedly performed as described above. As described above, by repeating the transfer step two or more times, two or more layers of Maxine can be formed, and in this case, even if the number of transfers increases, a thin film can be formed uniformly, and the transfer can be performed with a uniform thickness. The desired transmittance, electrical conductivity, sheet resistance, and electromagnetic wave shielding effects can be achieved by adjusting the desired thickness.

According to an aspect of the present invention, after the transfer, the step of drying the thin film at room temperature for 10 minutes to 5 hours may be further performed. Preferably, it can be dried for 30 to 2 hours, more preferably for 30 to 1 hour.

According to an aspect of the present invention, the thin film may be provided with an average thickness of 1 nm to 100 μm. It is possible to provide a thin film having a thickness of various ranges according to the number of transfers as described above. In order to provide a flexible device or a transparent device, it may be provided with an average thickness of preferably 1 to 100 nm, more preferably 1 to 50 nm, and most preferably 1 to 20 nm. Even if a thin film having a thickness of a nanometer level is formed as described above, it can be provided with a uniform thickness over the whole, and excellent transmittance, as well as remarkably excellent electrical conductivity and electromagnetic shielding efficiency compared to the thickness can be provided.

According to an aspect of the present invention, in step b), the thin film may be dried to remove an organic solvent or a polar solvent. Specifically, it may be performed at 20 to 200°C, preferably at 20 to 100°C for 1 to 48 hours, but is not limited thereto.

According to an aspect of the present invention, after step b), the step of heat-treating the thin film at 300 to 500°C may be further included. Preferably, the heat treatment may be performed at 350 to 500°C. In addition, the heat treatment may be performed for 30 minutes to 5 hours, preferably 30 minutes to 2 hours. The heat treatment is a process different from the drying, and by further performing the heat treatment, moisture remaining on the surface of the Maxine thin film and oxygen functional groups present may be removed, and stability may be further improved. In addition, electrical conductivity and electromagnetic wave shielding effects can be further improved.

According to an aspect of the present invention, the heat treatment may be performed under an inert gas. The inert gas may include any one or two or more selected from nitrogen, argon, neon, and helium.

The method of manufacturing a Maxine thin film according to the present invention can provide a dense, high coverage Maxine thin film as well as being able to adjust the thickness to a uniform thickness even at the nanometer level.

Another aspect of the present invention is a Maxine thin film manufactured by the above-described manufacturing method and having a coverage of 90% or more. According to an aspect of the present invention, the coverage may be 90 to 99.9%, preferably 95 to 99%.

The Maxine thin film manufactured by the conventional solution process such as spin coating, spray coating, or dip coating provides remarkably low coverage of about 70%, making it difficult to provide uniform thickness, resulting in large variations in physical properties and loss. .

In contrast, the Maxine thin film according to the present invention is manufactured by the above-described manufacturing method, thereby providing a uniform thickness with a high coverage of 95% or more, thereby realizing uniform properties over the whole, and having excellent electrical conductivity and electromagnetic wave shielding effect.

According to an aspect of the present invention, the Maxine thin film may have a single layer or a multilayer structure of two or more layers. Even if it is provided as a single layer having a thickness of 1 to 2 nm as described above, it is possible to realize excellent electrical conductivity and electromagnetic wave shielding effect by providing high coverage even at a thin thickness of a nanometer level. In addition, even if it is provided in a multilayer structure of two or more layers, it is possible to provide a uniform thickness over the whole, and can be adjusted to a desired thickness.

According to an aspect of the present invention, the Maxine thin film may have a specific electromagnetic interference shielding effectiveness (EMI SE) of 1.0×10 ⁴ dB·cm 2 /g or more. Specifically, it may be 1.0×10 ⁴ to 1.0×10 ⁷ dB·cm 2 /g at a thickness of 1 to 50 nm, preferably 1.0×10 ⁶ to 1.0×10 ⁷ dB·cm 2 /g, and more Preferably, it may be 2.0×10 ⁶ to 1.0×10 ⁷ dB·cm 2 /g. The electromagnetic shielding efficiency as described above realizes a remarkably high value compared to the density and thickness, which is more than 1,000 times compared to the existing carbon composite material, and more than 100 times more than other Maxine composite materials.

According to an aspect of the present invention, the Maxine thin film may have an average thickness of 1 nm to 100 μm. It may have a thickness in a wide range as described above, and preferably 1 to 100 nm, more preferably 1 to 50 nm, and most preferably 1 to 20 nm average thickness to provide a flexible device or a transparent device. have. Even though the thin film has a nanometer-level thickness as described above, it can be provided with a uniform thickness throughout, and excellent transmittance, as well as remarkably excellent electrical conductivity and electromagnetic wave shielding efficiency compared to the thickness.

According to an aspect of the present invention, after the Maxine thin film undergoes a heat treatment step, the contact angle may be 90° or more. Specifically, the contact angle may be 90 to 160°, and preferably 95 to 130°. Existing Maxine thin films have hydrophilic properties and are well dispersed in water, but by passing through the manufacturing method according to the present invention, by implementing the overall hydrophobicity of the thin film, it has excellent stability even in a humid external environment, preventing damage and performance reduction of the thin film. Electrical conductivity and electromagnetic wave shielding efficiency can be maintained.

According to an aspect of the present invention, the sheet resistance of the thin film after heat treatment may be reduced by 10 to 60%, and preferably by 20 to 50%, compared to the sheet resistance of the thin film without heat treatment. When the heat treatment is performed as described above, a more compact structure can be induced and electrical conductivity can be improved.

According to one aspect of the present invention, after heat treatment at a thickness of 1 to 50 nm, the Maxine thin film may have a sheet resistance of 250 Ω/□ or less. Preferably it may be 20 to 210Ω/□, more preferably 20 to 190Ω/□, and more preferably 20 to 180Ω/□. By implementing the low sheet resistance as described above, it is possible to have more excellent electrical conductivity.

According to an aspect of the present invention, the Maxine thin film may be heat-treated at 300 to 500°C. Preferably, the heat treatment may be performed at 350 to 500°C. In addition, the heat treatment may be performed for 30 minutes to 5 hours, preferably 30 minutes to 2 hours. The heat treatment is a process different from the drying, and by further performing the heat treatment, oxygen functional groups present on the surface of the Maxine thin film may be removed, and stability may be further improved. In particular, the oxygen functional group may be a hydroxyl group (-OH). In addition, electrical conductivity and electromagnetic wave shielding effects can be further improved.

In this way, the Maxine thin film may realize further improved electrical conductivity and electromagnetic wave shielding efficiency after heat treatment.

Specifically, in the Maxine thin film, the sheet resistance of the thin film after heat treatment may decrease by 10% or more, specifically 10 to 50%, and preferably 20 to 50%, compared to the sheet resistance of the thin film without heat treatment. Even though the Maxine thin film without heat treatment has excellent electrical conductivity and electromagnetic wave shielding efficiency, it is possible to achieve more excellent electrical conductivity and electromagnetic wave shielding efficiency after heat treatment.

According to an aspect of the present invention, the Maxine thin film may have an oxygen content of 10 atomic% or less based on the total atomic content. Preferably it may be 7 atomic% or less. More preferably, when the heat treatment is performed, the oxygen content of the thin film after the heat treatment may be reduced by 10 to 50%, and preferably by 15 to 50%, compared to the oxygen content of the thin film without heat treatment. When subjected to the heat treatment as described above, the stability of the Maxine surface, electrical conductivity, and electromagnetic wave shielding efficiency may be further improved.

In another aspect of the present invention, A) preparing a mixed dispersion by mixing a first dispersion containing maxine and a second dispersion containing nanomaterials; And B) forming a thin film on the surface of the mixed dispersion. It is a method of manufacturing a Maxine composite thin film comprising a. Details of the first dispersion and the configuration of forming the thin film are described in the above-described method for manufacturing the Maxine thin film, and thus description thereof will be omitted.

The Maxine composite thin film according to the present invention further includes not only Maxine but also nanomaterials, thereby providing a Maxine composite thin film having a uniform thickness over a large area, as well as further improved electrical properties and electromagnetic wave shielding effects.

According to an aspect of the present invention, the second dispersion may include a nanomaterial, and for example, the nanomaterial may be dispersed in a polar solvent. The polar solvent may be the same or different from the polar solvent of the first dispersion, for example, water, ethanol, methanol, dimethylformamide (DMF), dimethylacetamide, n-methylpyrrolidinone (NMP), and tetra It may be any one or a mixture of two or more selected from hydrofuran and the like. Preferably, it may have miscibility with the first dispersion, and it is not particularly limited as long as the nanomaterial is easily dispersed.

According to one aspect of the present invention, the second dispersion may contain 0.01 to 5% by weight of nanomaterials based on the total weight. Preferably, it may contain 0.01 to 3% by weight of nanomaterials. When included in the above range, it is possible to form a thin film uniformly on the surface without causing aggregation between Maxine and the nanomaterial, thereby producing a composite thin film having a uniform thickness.

According to an aspect of the present invention, the nanomaterial may be any one or a mixture of two or more selected from carbon-based materials, ceramic-based materials, and organic materials. For example, reduced graphene (RG, Reduced Graphene), reduced graphene oxide (RGO, Reduced Graphene Oxide), graphene, graphene oxide (GO, Graphene Oxide), carbon nanotubes, fullerene , Carbon nanoribbon, boron nitride, silica, alumina, aluminum nitride, cellulose and lignin may be any one or a mixture of two or more selected from. In order to improve the electrical properties, preferably reduced graphene (RG, Reduced Graphene), reduced graphene oxide (RGO, Reduced Graphene Oxide), graphene, graphene oxide (GO, Graphene Oxide), carbon nano It may be a carbon-based material selected from a tube, fullerene, and carbon nanoribbon.

According to an aspect of the present invention, the nanomaterial may have a one-dimensional, two-dimensional, or three-dimensional structure in shape, and specific examples, for example, spherical, plate-shaped, needle-shaped, scale-shaped. It may be provided in various shapes selected from a rod shape and a polygon, but is not limited thereto.

According to an aspect of the present invention, the nanomaterial may have a thickness of a nanometer level, preferably 1 to 100 nm, more preferably 1 to 50 nm, most preferably 1 to 20 nm average It may have a thickness, but is not limited thereto.

According to an aspect of the present invention, step B) may be to form a thin film at the interface by adding an immiscible organic solvent to the first mixed dispersion. Specifically, according to an aspect of the present invention, step B) may be to induce self-assembly at the interface to form a thin film. The organic solvent is as described above, and evaporation occurs on the surface while forming an interface with the mixed dispersion to induce a difference in surface tension, thereby further promoting self-assembly of Maxine and nanomaterials. In addition, it is possible to form a thin film having a uniform and dense structure while realizing high coverage of the manufactured Maxine composite thin film.

According to an aspect of the present invention, the first dispersion and the second dispersion may be mixed in a weight ratio of 1:0.5 to 1:5. Preferably, it may be mixed in a weight ratio of 1:0.5 to 1:3, more preferably in a weight ratio of 1:0.5 to 1:2. By dispersing in the above amount, it is possible to maximize electrical properties and electromagnetic shielding effect, and to induce uniform dispersion while preventing the aggregation of Maxine and nanomaterials, respectively.

Another aspect of the present invention is a Maxine composite thin film prepared by the method for manufacturing a Maxine composite thin film described above, and including Maxine and nanomaterials. According to one aspect of the present invention, the Maxine composite thin film may have excellent coverage, preferably 70 to 99.9%, and preferably 90 to 99%.

The Maxine thin film manufactured by the conventional solution process such as spin coating, spray coating, or dip coating provides remarkably low coverage of about 70%, making it difficult to provide uniform thickness, resulting in large variations in physical properties and loss. .

In contrast, the Maxine composite thin film according to the present invention is manufactured by the above-described manufacturing method, thereby providing a uniform thickness with a high coverage of 95% or more, thereby realizing uniform physical properties throughout, and having more excellent electrical characteristics and electromagnetic wave shielding effects. have.

According to an aspect of the present invention, the Maxine composite thin film may have a shape in which nanomaterials are dispersed in Maxine in a layer-by-layer (LBL) method or arranged on the same plane. Specifically, the two-dimensional nanomaterial may have a shape that is horizontally arranged on the same plane in the plane direction with the maxine. Alternatively, nanomaterials having a one-dimensional structure may be stacked on the surface of Maxine in a layer-by-layer (LBL) method to be prepared in a dispersed shape.

In the Maxine composite thin film according to an aspect of the present invention, Maxine and nanomaterials may be in a weight ratio of 1:0.01 to 1:2. Preferably, the maxine and the nanomaterial may be in a weight ratio of 1:0.05 to 1:2, more preferably the maxine and the nanomaterial may be in a weight ratio of 1:0.1 to 1:2, but the present invention is not limited thereto. The content of the nanomaterials as described above can be adjusted according to the desired physical properties, but the above-described content can be satisfied in order to further maximize the physical properties of Maxine.

The Maxine thin film or Maxine composite thin film according to the present invention can be applied to various fields to which excellent electrical properties and electromagnetic shielding efficiency can be applied, for example, in various fields such as electrochemistry, electronics, textiles, aviation, military and automobiles. It can be applied to fields requiring the effect according to the present invention.

Hereinafter, a method of manufacturing a Maxine thin film according to the present invention and a Maxine thin film prepared therefrom will be described in more detail through Examples. However, the following examples are only one reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Further, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The terms used in the description herein are merely to effectively describe specific embodiments and are not intended to limit the invention.

In addition, the unit of the additive not specifically described in the specification may be a weight %.

[Method of measuring properties]

1. Coverage

The coverage of the Maxine thin films of Examples and Comparative Examples was calculated from the difference in light and dark through the Image J program from an electron scanning microscope (S-4800, Hitachi) image.

2. Contact angle

At room temperature, 3 µl of water was placed on the surface of Maxine obtained in Examples and Comparative Examples, and the static contact angle was measured using a GSS device manufactured by Surface Tech Co., Ltd.

3. Electrical conductivity

For the electrical conductivity of the Maxine thin films of Examples and Comparative Examples, a 4-point probe measurement method using the MCP-TP06P model with a spacing of 1.5 mm between the probe pins was used using the MCP-T610 equipment of Mitsubishi Corporation.

-Sheet resistance reduction rate = [(Example sheet resistance without heat treatment-Example sheet resistance after heat treatment) / Example sheet resistance without heat treatment] × 100

4. Absorbance

The absorbance of the Maxine thin films of Examples and Comparative Examples was measured using a UV-2600 equipment manufactured by Shimadzu Corporation. The specimen was prepared by using Corning's Eagle XG glass wafer substrate in a 12.7mm×25.4mm rectangular shape, and then the thin film was transferred.

5.Electromagnetic shielding efficiency

The electromagnetic wave shielding efficiency (dB) of the Maxine thin films of Examples and Comparative Examples is that Corning's Eagle XG glass wafer substrate is cut into 12.7mm×25.4mm suitable for a WR-90 rectangular waveguide, and the thin film is transferred to Agilent Technologies' ENA5071C equipment. It was measured over the 8.2 ~ 12.4GHz (X-band) region using.

[Example 1]

Maxine was prepared by adding 3 g of MAX powder, a precursor of Maxine, to 4.8 g of lithium fluoride (LiF) and 60 ml of 9M aqueous hydrochloric acid (HCl) solution, and reacting at 35° C. for 24 hours to chemically peel off. . Max that did not peel off in the solution was removed through centrifugation at 3,500 rpm. After the maxine prepared as described above was prepared as a maxine aqueous dispersion at a concentration of 0.5 mg/ml, 1 M nitric acid (HNO ₃ ) 1 part by weight was added to 100 parts by weight of the maxine aqueous dispersion. After that, 5 parts by weight of ethyl acetate was added to confirm that a Maxine thin film was formed at the interface. The physical properties were measured after transferring the Maxine thin film to the glass substrate by contacting the glass substrate with the Maxine thin film formed at the interface.

The Maxine thin film prepared in Example 1 was confirmed to have a dense structure through a scanning electron microscope (SEM, Hitachi S-4800) as shown in FIG. 2, and it was confirmed that the coverage was 96.7%.

[Example 2-5]

In the same manner as in Example 1, the number of transfers of the manufactured Maxine thin film was performed 3, 5, 7 and 9 times, respectively, and examples 2 to 5 were sequentially performed.

[Example 6]

The same procedure was performed except that the Maxine thin film prepared in Example 1 was heat-treated at 400° C. for 1 hour in an argon atmosphere.

[Example 7]

Mixing in which the aqueous dispersion of Maxine prepared in Example 1 and graphene (manufactured by the standard graphene Co. Hummer's method) were dispersed in NMP at a concentration of 0.5 mg/ml in a ratio of 1:1 by weight based on solid content A dispersion was prepared. With respect to 100 parts by weight of the mixed dispersion, 1 part by weight of 1M nitric acid (HNO ₃ ) was added. Thereafter, 5 parts by weight of ethyl acetate was added to confirm that a Maxine composite thin film was formed at the interface.

After transferring the Maxine composite thin film to the glass substrate by contacting the glass substrate with the Maxine composite thin film formed at the interface, the Maxine and graphene thin films were formed through a scanning electron microscope (SEM, Hitachi S-4800) as shown in FIG. It was confirmed that it was uniformly arranged on the same plane in the plane direction and had a dense structure.

[Example 8]

The Maxine aqueous dispersion and multi-carbon nanotubes (MWCNTs, Hanwha Chemical, CM-280) prepared in Example 1 were mixed in a 1:1 weight ratio of carbon nanotube dispersions dispersed in NMP at a concentration of 0.5mg/ml. A mixed dispersion was prepared. With respect to 100 parts by weight of the mixed dispersion, 1 part by weight of 1M nitric acid (HNO ₃ ) was added. Thereafter, 5 parts by weight of ethyl acetate was added to confirm that a Maxine composite thin film was formed at the interface. After transferring the Maxine composite thin film to the glass substrate by contacting the glass substrate with the Maxine composite thin film formed at the interface, carbon nanoparticles on the surface of Maxine through a scanning electron microscope (SEM, Hitachi S-4800) as shown in FIG. It was confirmed that the tubes were stacked by the LBL method and had a compact structure.

[Comparative Example 1]

The Maxine aqueous dispersion prepared in Example 1 was spin-coated on a silicon wafer at 3,000 rpm to prepare a Maxine thin film.

The Maxine thin film prepared in Comparative Example 1 was confirmed to have a large number of voids through a scanning electron microscope (SEM, Hitachi S-4800) as shown in FIG. 3, and the sheet resistance was measured at 2 nm thickness due to the number of voids. It could not be done, and it was confirmed that the coverage was 74.0%.

[Experimental Example 1]

Analysis of physical properties according to Maxine thin film shape and number of transfers.

As shown in Figure 1, the Maxine thin film prepared in Example 1 can be confirmed that both the one transferred to the glass substrate (a) and the one transferred to the polyethylene terephthalate film (b) are transparent, and flexibility by forming a single layer It can be seen that even if transferred to a polymer substrate having and bent, excellent flexibility is realized without damage.

When transferred to Example 1 (1L), Example 2 (3L), Example 3 (5L), Example 4 (7L) and Example 5 (9L) as shown in Fig. 4, depending on the number of transfers By increasing the measured absorbance in a linear relationship, it means that the Maxine thin film can be formed with a uniform thickness, and accordingly, it can be confirmed that the uniform and accurate thickness can be adjusted by the number of transfers.

[Experimental Example 2]

Analysis of physical properties before and after heat treatment.

The Maxine thin films prepared in Examples 1 and 6 were analyzed through XPS spectrum for Ti2p and XPS (Thermo VG Scientific, Inc.) for O1s. As shown in FIG. 5, when the Ti element of the Maxine thin film of Examples 1 and 6 was analyzed in FIG. 5A, it was confirmed that the heat-treated Example 6 maintained the Maxine phase more stably.

In addition, when analyzing the oxygen element, it was confirmed that the Ti-OH group was significantly reduced in Example 6 compared to Example 1, and that the oxygen functional group, particularly the hydroxyl group (-OH) group, decreased through heat treatment. Specifically, it was confirmed that the oxygen content of the Maxine thin film in Example 1 was 5.4 atomic% with respect to the total atomic content of the thin film, and the oxygen content decreased by about 16% to 4.3 atomic% after heat treatment.

In addition, as shown in FIG. 6, it was confirmed that Example 1 without heat treatment had hydrophilicity at 50.4° when measuring the contact angle, whereas Example 6 had hydrophobicity at 99.9° when measuring the contact angle by heat treatment. Accordingly, it was confirmed that it can be applied to various fields aimed at hydrophilicity or hydrophobicity.

In addition, as shown in FIG. 7, when the sheet resistance of the Maxine thin films prepared in Examples 1 and 6 were measured, all of them had excellent sheet resistance, charge mobility, and charge carrier density, but in Example 6, the sheet resistance was about 45. % Decrease, charge mobility increased by about 2 times, and charge carrier density increased by about 1.2 times, which confirmed that even better electrical conductivity can be realized when heat treatment is performed.

In addition, when the electromagnetic wave shielding efficiency was measured by heat treatment of the Maxine thin films prepared in Examples 1 to 5 according to the present invention, as shown in FIG. 8, not only the excellent electromagnetic wave shielding effect was realized, but also the heat treatment was not performed. Compared to the other examples, it was confirmed that Example 1 implements an improved electromagnetic wave shielding effect of about 10% or more in Examples 2 to 5 by 30% or more.

Moreover, as shown in FIG. 9, it can be seen that it has high electromagnetic wave shielding efficiency even at a significantly thinner thickness compared to the conventional Maxine composite material as well as a metal film, a metal composite material, and a carbon material.

As described above, in the present invention, a method of manufacturing a Maxine thin film and a Maxine thin film manufactured therefrom have been described through specific matters and limited examples, but this is provided only to aid in a more general understanding of the present invention. It is not limited to the embodiments of, and those of ordinary skill in the field to which the present invention pertains, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention is limited to the described embodiments and should not be defined, and all things that are equivalent or equivalent to the claims as well as the claims to be described later fall within the scope of the spirit of the present invention. .

Claims (19)

a) preparing a first dispersion containing Maxine; And
b) forming a thin film at the interface by adding an immiscible organic solvent to the first dispersion;
Maxine thin film manufacturing method comprising a. delete The method of claim 1,
The step b) is a method of manufacturing a Maxine thin film in which a thin film is formed by inducing self-assembly at the interface. The method of claim 1,
A method of manufacturing a Maxine thin film further comprising an acid solution in the first dispersion of step a). The method of claim 1,
The organic solvent is a method of manufacturing a volatile Maxine thin film. The method of claim 1,
After step b), the method of manufacturing a Maxine thin film further comprising the step of transferring the thin film to the substrate. The method of claim 6,
A method of manufacturing a Maxine thin film in which the transferring step is repeated two or more times to form a multilayer thin film. The method of claim 1,
After step b), the method of manufacturing a Maxine thin film further comprising the step of heat-treating the thin film at 300 to 500°C. A) preparing a mixed dispersion by mixing the first dispersion containing Maxine and the second dispersion containing nanomaterials; And
B) forming a thin film on the surface of the mixed dispersion;
Maxine composite thin film manufacturing method comprising a. The method of claim 9,
The step B) is to form a thin film at the interface by adding an immiscible organic solvent to the mixed dispersion. The method of claim 9,
The nanomaterial is any one or a mixture of two or more selected from carbon-based materials, ceramic-based materials, and organic materials. The method of claim 9,
The first dispersion and the second dispersion are mixed in a weight ratio of 1:0.5 to 1:5, the method of manufacturing a Maxine composite thin film. A Maxine thin film manufactured by the manufacturing method of any one of claims 1, 3 to 8, and having a coverage of 90% or more. The method of claim 13,
The Maxine thin film is a Maxine thin film having a single layer or a multilayer structure of two or more layers. The method of claim 13,
The Maxine thin film has an electromagnetic shielding efficiency (specific EMI SE) of 1.0×10 ⁴ dB·㎠/g or more. The method of claim 13,
The Maxine thin film is a Maxine thin film having a contact angle of 90° or more after a heat treatment step. A Maxine composite thin film prepared by the manufacturing method of any one of claims 9 to 12 and comprising Maxine and nanomaterials. The method of claim 17,
The Maxine composite thin film is a Maxine composite thin film in which nanomaterials are dispersed in a layer-by-layer (LBL) method or arranged on the same plane. The method of claim 17,
The Maxine composite thin film is a Maxine composite thin film in which Maxine and nanomaterials are in a weight ratio of 1:0.01 to 1:2.

Images