Molded body, laminate, and method for manufacturing a molded body

Abstract

The present invention provides a molded article having a novel structure including an organometallic structure, which exhibits excellent moisture resistance and high mechanical strength. [Solution] A molded body comprising a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, having a processed wall processed along a direction parallel to and intersecting the surface of the molded body, wherein the average angle between the surface of the processed wall and the surface of the molded body is 75° to 105°. A method for manufacturing a molded body that can produce a molded body with a desired shape imparted to the metal-organic structure includes performing an etching treatment on the composite comprising the metal-organic structure and the ionic liquid held within the pores of the metal-organic structure.

Description

Technical Field

[0001] The present disclosure relates to a molded body, a laminate, and a method for manufacturing a molded body.

Background Art

[0002] A metal-organic framework (MOF) is a porous three-dimensional structure, and its application to various uses is being studied. For example, Patent Document 1 describes a porous coordination polymer-ion liquid composite having an insulating structure composed of a porous coordination polymer and an ionic liquid held in the pores of the porous coordination polymer. Patent Document 2 describes an ion conductive composite characterized by having crystalline particles of a porous coordination polymer with an average primary particle diameter of 50 nm or less and a first ionic liquid held in a first pore provided in the porous coordination polymer. Patent Document 3 describes a molecular sensor provided with a sensitive film in which a porous member and an ionic liquid coexist, and capable of detecting a target molecule by measuring a change in a physical quantity due to the adhesion of the target molecule to the sensitive film. Patent Document 4 describes a carbon dioxide absorbent comprising at least a porous carrier and an ionic liquid supported on the porous carrier, wherein the ionic liquid is a specific phosphonium-based ionic liquid. Patent Document 5 describes a method for producing a surface-functionalized porous organic-inorganic hybrid material produced by reacting a porous organic-inorganic hybrid material or a porous organic-inorganic mesoporous material having an unsaturated metal site with an organic substance, an inorganic substance, an ionic liquid, and an organometallic compound.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

[0004] Traditionally, organometallic structures have had the problem of their porous three-dimensional structure being destroyed when they absorb moisture, for example, from the air. For instance, it is known that MOF-5, synthesized as a hydrogen storage material, gradually loses its hydrogen storage capacity when left exposed to air. This is because water molecules that penetrate the pores of MOF-5 from the air destroy the framework of the porous three-dimensional structure. Specifically, it is thought that the bonds between the organic ligands and metal ions are broken by hydrolysis reactions caused by water molecules. Furthermore, the skeletal structure of organometallic structures has extremely low mechanical strength, and its porous three-dimensional structure is destroyed by irradiation with charged particles, such as metal ion beams. For this reason, even when organometallic structures are irradiated with a metal ion beam, such as gallium ions, using a focused ion beam apparatus, the porous three-dimensional structure is destroyed, making it impossible to process them into molded bodies with the desired shape.

[0005] Therefore, there is a need for molded articles having a new structure, including an organometallic structure, that exhibits excellent moisture resistance and high mechanical strength.

[0006] This disclosure has been made in view of the circumstances described herein, and the problem that one embodiment of this disclosure aims to solve is to provide a molded article and a laminate having a novel structure. Furthermore, other embodiments of this disclosure aim to solve the problem of providing a method for manufacturing a molded article that can produce a molded article in which a desired shape is imparted to a metal-organic structure. [Means for solving the problem]

[0007] This disclosure includes the following aspects: <1> A molded body comprising a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, A molded body having processed walls machined along directions parallel to and intersecting the surface of the molded body, wherein the average angle between the surface of the processed walls and the surface of the molded body is between 75° and 105°. <2> Ionic liquids contain imidazolium cations. <1> The molded body described above. <3> The imidazolium cation is either 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, or 1-methyl-3-n-octylimidazolium cation. <2> The molded body described above. <4> The ionic liquid includes a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a bis(trifluoromethanesulfonyl)imide anion, or a dicyanamide anion. <1> ~ <3> A molded body as described in any one of the following. <5> A circuit board and, placed on the circuit board, <1> ~ <4> A laminate comprising a molded body described in any one of the following. <6> A method for manufacturing a molded article, comprising performing an etching treatment on a composite containing a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure. <7> The etching process is dry etching. <6> A method for manufacturing a molded article as described above. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, a molded body and a laminate having a novel structure are provided. Further, according to another embodiment of the present disclosure, a method for manufacturing a molded body capable of producing a molded body having a desired shape imparted to a metal organic structure is provided.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is an electron micrograph of the molded body of Example 1. [Figure 2A] FIG. 2A is a diagram showing the etching rate during FIB processing in Example 1-1. [Figure 2B] FIG. 2B is a diagram showing the etching rate during FIB processing in Example 1-2. [Figure 2C] FIG. 2C is a diagram showing the etching rate during FIB processing in Example 1-3. [Figure 3] FIG. 3 is an electron micrograph when attempting FIB processing on a metal organic structure not containing an ionic liquid.

Modes for Carrying Out the Invention

[0010] In the present disclosure, the numerical range indicated by using "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range of other stepwise descriptions. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, the amount of each component means the total amount of a plurality of substances when there are a plurality of substances corresponding to each component, unless otherwise specified. In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved.

[0011] The drawings referenced in the following description are illustrative and schematic, and this disclosure is not limited to these drawings. The same reference numerals indicate the same components. Reference numerals in the drawings may also be omitted.

[0012] [Molded body] The molded article according to this disclosure comprises a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, and has a processed wall processed along a direction parallel to and intersecting the surface of the molded article, wherein the average angle between the surface of the processed wall and the surface of the molded article is 75° to 105°.

[0013] Metal-organic structures are difficult to process on their own. The inventors have discovered that a molded article with a novel structure can be obtained by combining a metal-organic structure with an ionic liquid. The molded article according to this disclosure not only possesses the physical properties and functions of both the metal-organic structure and the ionic liquid, but also exhibits new physical properties and functions through the interaction between the metal-organic structure and the ionic liquid. For example, the molded article according to this disclosure has improved gas adsorption and separation capabilities compared to a metal-organic structure alone, and is expected to be introduced into semiconductor processes.

[0014] Furthermore, in the molded article according to this disclosure, since the ionic liquid is retained within the pores of the metal-organic structure, it does not absorb moisture even when left in an atmosphere with normal humidity for a long period of time, and the porous three-dimensional structure is not destroyed by hydrolysis. In other words, the molded article according to this disclosure has excellent moisture resistance. Therefore, the molded article relating to this disclosure can be applied to devices such as gas sensors, even in high-humidity environments.

[0015] The molded article relating to this disclosure has processed walls that are processed along directions parallel to and intersecting the surface of the molded article. The number of processed walls is not particularly limited. For example, the molded article according to the present disclosure may have recesses, and may have four processed walls in each recess.

[0016] The shape of the molded article relating to this disclosure is not particularly limited and may be adjusted as appropriate depending on the application. When the molded body of this disclosure is provided on a substrate as described later, the thickness of the molded body is, for example, 1.0 nm to 100.0 μm.

[0017] The average angle between the processed wall surface and the surface of the molded body is 75° to 105°, preferably 80° to 100°, and more preferably 85° to 95°. By having an average angle of 75° to 105° between the processed wall surface and the surface of the molded body, it becomes possible to fabricate finer and denser devices.

[0018] One way to achieve an average angle of 75° to 105° between the processed wall surface and the surface of the molded body is, for example, by the etching process described later.

[0019] Furthermore, when etching is performed on a metal-organic structure, it is difficult to form a processed wall due to the insufficient strength of the metal-organic structure. In contrast, the molded article according to this disclosure contains a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, and therefore has higher strength compared to the metal-organic structure. As a result, the average angle between the wall surface of the processed wall and the surface of the molded article can be set to 75° to 105° by etching.

[0020] The angle between the processed wall surface and the surface of the molded body is measured using a scanning electron microscope or a transmission electron microscope. The angle between the processed wall surface and the surface of the molded body is measured for three or more processed areas, and the average value is adopted.

[0021] (Metal-organic structure) The molded article relating to this disclosure includes a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure.

[0022] A metal-organic structure includes, for example, an organic ligand and a metal ion. The organic ligand and metal ion are not particularly limited.

[0023] Examples of organic ligands include dicarboxylic acids, tricarboxylic acids, imidazoles, benzimidazoles, and azabenzimidazoles. Examples of metal ions include Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Pt, Au, Ag, and Mg.

[0024] Examples of metal-organic structures include MOF-5:Zn4O(bdc)3, HKUST-1:Cu3(btc)2, UiO-66:Zr6O4(OH)4(bdc)6, MOF-74:M2(dobdc), ELM-11:Cu(bpy)2(BF4)2, UIO-67, ZIF-8, ELM-11, MIL-53, MIL-100, MIL-101, and DUT-5.

[0025] The cations that make up the ionic liquid are not particularly limited. Examples of cations that constitute ionic liquids include ammonium cations, pyridinium cations, pyrrolidinium cations, pyrrolium cations, oxazolium cations, oxazolinium cations, imidazolium cations, phosphonium cations, and sulfonium cations.

[0026] In particular, from the viewpoint of high physicochemical stability and the ability to broadly control physicochemical properties by introducing various substituents, it is preferable that the cation constituting the ionic liquid includes an imidazolium cation. The cations constituting the ionic liquid may be one type or two or more types.

[0027] Examples of imidazolium cations include 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-methyl-3-n-octylimidazolium cation, 1-allyl-3-methylimidazolium cation, and 1,3-diarylimidazolium cation.

[0028] In particular, the imidazolium cation is preferably 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, or 1-methyl-3-n-octylimidazolium cation.

[0029] In a composite comprising a metal-organic structure and an ionic liquid, where the cation constituting the ionic liquid is an imidazolium cation, the etching rate takes a minimum value at 4 carbon atoms other than the imidazole ring. From the viewpoint of improving the flatness of the etched surface, it is preferable that the imidazolium cation has close to 4 carbon atoms other than the imidazole ring. The upper limit of the carbon number is, for example, 12.

[0030] The anions that make up the ionic liquid are not particularly limited. Examples of anions that constitute an ionic liquid include halide ions, hexafluorophosphate anions, tetrafluoroborate anions, trifluoromethanesulfonic acid anions, bis(trifluoromethanesulfonyl)imide anions, and dicyanamide anions. The anions that make up the ionic liquid may be one type or two or more types.

[0031] In particular, the anions constituting the ionic liquid are preferably hexafluorophosphate anions, tetrafluoroborate anions, trifluoromethanesulfonic acid anions, bis(trifluoromethanesulfonyl)imide anions, or dicyanamide anions, more preferably hexafluorophosphate anions or tetrafluoroborate anions, and even more preferably hexafluorophosphate anions.

[0032] The ionic liquid is retained within the pores of the metal-organic structure. This retention of the ionic liquid within the pores of the metal-organic structure can be confirmed by differential scanning calorimetry.

[0033] [Laminated structure] The molded body relating to this disclosure may be placed on a substrate. The laminate relating to this disclosure includes a substrate and a molded body of this disclosure disposed on the substrate.

[0034] (substrate) The material of the substrate is not particularly limited. The substrate may be made of only one material, or it may be made of two or more materials stacked together. Examples of substrate materials include semiconductors (e.g., Si, silicon, InP, GaN, GaAs, InGaAs, InGaAlAs, SiC, etc.); Oxides, carbides, or nitrides (e.g., borosilicate glass, quartz glass (SiO2), sapphire, ZrO2, Si3N4, AlN, etc.); Piezoelectric materials or dielectrics (e.g., BaTiO3, LiNbO3, SrTiO3, diamond, etc.); Metals (e.g. Al, Ti, Fe, Cu, Ag, Au, Pt, Pd, Ta, Nb, etc.); Resins (e.g., polydimethylsiloxane (PDMS), epoxy resins, phenolic resins, polyimides, benzocyclobutene resins, polybenzoxazoles, etc.); These are some examples.

[0035] The shape of the substrate is not particularly limited. From the viewpoint of compatibility with semiconductor processes including spin coating processes, a disc-shaped substrate with high surface flatness is preferred. In order to improve the adhesion between the substrate and the molded body, for example, a porous alumina substrate may be used for the substrate to create an uneven surface shape.

[0036] From the standpoint of availability, the substrate is preferably a silicon (Si) substrate, SiC substrate, glass substrate, quartz substrate, glass substrate, sapphire substrate, porous alumina substrate, or polymer substrate. The substrate may have a multilayer structure.

[0037] The thickness of the substrate is not particularly limited, but for example, it is between 0.1 mm and 1.0 mm.

[0038] [Method for manufacturing molded products] The method for manufacturing a molded article according to this disclosure includes etching a composite containing a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure. The molded article according to this disclosure can be manufactured, for example, by obtaining a composite containing a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, and then performing an etching treatment on the composite.

[0039] Metal-organic structures can be synthesized by methods such as hydrothermal synthesis, spin coating, doctor blade, chemical vapor deposition, inkjet printing, and electrochemical growth. By forming a self-assembled monolayer (SAM) on a semiconductor substrate or electrode, metal-organic structures can be selectively grown. Furthermore, by pre-depositing the metals constituting the metal-organic structure onto a substrate and then synthesizing the metal-organic structure while the substrate is immersed in a metal-organic structure synthesis solution, the metal-organic structure can be selectively grown on the deposited metal portions.

[0040] One method for obtaining a composite containing a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure is to empty the pores of the metal-organic structure and then immerse it in the ionic liquid.

[0041] The etching process may be dry etching or wet etching. Generally, wet etching proceeds isotropically, while dry etching proceeds anisotropically. Therefore, from the viewpoint of microfabrication, dry etching is preferred, and dry etching using a focused ion beam or milling is more preferred.

[0042] For etching, for example, a focused ion beam (FIB) device is used. The FIB apparatus is equipped with a liquid metal ion source to generate a metal ion beam for processing materials. Gallium ions are preferred as the liquid metal ions because they provide a sufficient sputtering speed for processing, have a low melting point of 29.8°C, and, once heated, operate in a liquid state even at room temperature due to supercooling. Furthermore, the method of irradiating with ions for etching purposes is not limited to the method using a FIB (Fiber-Injection Irradiation) device. In combination with lithography techniques known as semiconductor manufacturing methods, dry etching devices such as high-frequency plasma etching devices and microwave plasma etching devices, which are generally commercially available as semiconductor manufacturing equipment, may also be used. In this case, the ions irradiated may be argon ions, nitrogen ions, carbon ions, hydrocarbon ions, fluorinated hydrocarbon ions, halide ions, etc.

[0043] A molded body according to this disclosure may be formed on a substrate to manufacture a laminate. The molded articles according to this disclosure are preferably used in gas detection devices and batteries. [Examples]

[0044] The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to these examples.

[0045] <Example 1-1> -Fabrication of Cu3(btc)2 single crystals- A precursor solution was prepared by mixing 0.45 g of copper(II) nitrate trihydrate (Cu(NO3)2·3H2O), 0.25 g of 1,3,5-benzenetricarboxylic acid (H3(btc)), and 20 mL of 10% by mass nitric acid (HNO3) with 10 mL of N,N-dimethylformamide (DMF). The prepared precursor solution was sealed in a vial and stored at 65°C for 5 days using a constant-temperature drying oven. A Cu3(btc)2 single crystal was formed by heating. The Cu3(btc)2 single crystal was washed three times with ethanol, and then immersed in dichloromethane for three days. Dichloromethane was removed from the pores of the Cu3(btc)2 single crystal after immersion by vacuum heating at 190°C for 3 hours. A Cu3(btc)2 single crystal with empty pores was obtained.

[0046] -Filling with ionic liquid- A Cu3(btc)2 single crystal was immersed in an ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide) and vacuum-heated at 120°C for 12 hours. This resulted in a composite in which an ionic liquid was filled into the pores of a Cu3(btc)2 single crystal.

[0047] - Fabrication of molded bodies - A composite in which an ionic liquid was filled into the pores of a Cu3(btc)2 single crystal was introduced into the vacuum chamber of a FIB apparatus. As a metal ion, gallium ions accelerated to 30 keV were irradiated onto a square region of, for example, 5 micrometers x 5 micrometers, and etching was performed. As a result, molded bodies were obtained in which the average angle between the processed wall surface and the surface of the molded body was 75° to 105°.

[0048] <Example 1-2> A molded article was obtained in the same manner as in Example 1-1, except that 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide was used as the ionic liquid instead of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0049] <Examples 1-3> A molded article was obtained in the same manner as in Example 1-1, except that 1-methyl-3-n-octylimidazolium bis(trifluoromethanesulfonyl)imide was used as the ionic liquid instead of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0050] Figure 1 shows electron microscope images of the molded bodies of Examples 1-3. In FIB processing, the dose of gallium ions is 0.5 nC / μm 2 The result was that although the surface was etched to a depth of several hundred nanometers, the sidewalls remained almost vertical, and a molded body was formed in which the bottom surface, the unetched surface, and the sidewalls all maintained flat surfaces. In other words, it was shown that the angle between the processed wall surface and the surface of the molded body was approximately 90°.

[0051] Figures 2A and 2C are graphs showing the relationship between the length of the molecular chain of imidazolium cation contained in the ionic liquid and the etching rate during FIB processing. Figure 2A shows the etching rate during FIB processing in Example 1-1. Figure 2B shows the etching rate during FIB processing in Example 1-2. Figure 2C shows the etching rates during FIB processing in Examples 1-3.

[0052] In Figures 2A to 2C, the horizontal axis represents the amount of gallium ion charge irradiated per unit irradiation area. Under constant conditions of irradiation area and ion beam current, the value on the horizontal axis is proportional to the etching time; therefore, the slope of the graphs in Figures 2A to 2C can be interpreted as the etching rate. Figures 2A to 2C show that the etching rate depends on the length of the imidazolium cation molecular chain. In other words, it was found that the etching rate was fastest when 1-ethyl-3-methylimidazolium cation was used as the ionic liquid (Example 1-1), and the etching rate was slowest when 1-butyl-3-methylimidazolium cation was used (Example 1-2).

[0053] Figure 3 is an electron microscope image of a metal-organic structure that was subjected to FIB processing without an ionic liquid. The gallium ion dose was 0.3 nC / μm 2 As shown in Figure 3, when an ionic liquid was not included, uniform etching was not possible, and cracks appeared around the area being etched. It was found that processing for device applications was impossible.

[0054] <Example 2> A 100 nm thick Cu3(btc)2 single crystal thin film was formed on a Si substrate with a diameter of 2 inches and a thickness of 280 micrometers using the same method as in Examples 1-1 to 1-3. Next, an optimal pattern for device fabrication was formed using known lithography techniques. Specifically, the process involved coating the photoresist using a spin coater, pre-baking, exposure, post-baking, development, and hard-baking. The optimal pattern for device fabrication was a square with a width of 100 micrometers and a length of 100 micrometers. Next, the Si substrate with the Cu3(btc)2 single crystal thin film on which the above pattern was formed was introduced into the vacuum chamber of the dry etching apparatus. After introducing carbon tetrafluoride (CF4) and oxygen gas, dry etching was performed by introducing high-frequency power. Subsequently, the photoresist was removed using a commercially available resist stripping solution (Tokyo Ohka Kogyo Stripping Solution 502A) and a deposit-compatible stripping solution (Tokyo Ohka Kogyo Deposit-Compatible Stripping Solution SST-A2), obtaining a Si substrate equipped with a Cu3(btc)2 single-crystal thin film having the desired pattern. For the process of removing the photoresist, if the damage to the MOF and ionic liquid is minimal, an ashing apparatus using, for example, oxygen plasma may be used. The Cu3(btc)2 single crystal thin film had a processed wall, and the average angle between the processed wall surface and the thin film surface was 75° to 105°. Next, metal electrodes mainly composed of gold were formed at both ends in the longitudinal direction of the Cu3(btc)2 single crystal thin film, which had been processed into a square with a width of 100 micrometers and a length of 100 micrometers by the above process, using known lithography, electron beam vacuum deposition, and resist lift-off processes. A Cu3(btc)2 single-crystal thin film equipped with metal electrodes formed in this manner exhibits the property of reduced electrical resistance when absorbing CO2 (carbon dioxide), for example, and can be applied as a CO2 gas sensor.

[0055] The molded articles and laminates relating to this disclosure include a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, and have a novel structure. Various combinations of metal-organic structures and various ionic liquids are possible, and applications to gas sensors are expected.

Claims

1. A molded body comprising a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure, A molded body having a processed wall processed along a direction parallel to and intersecting the surface of the molded body, wherein the average angle between the surface of the processed wall and the surface of the molded body is 75° to 105°.

2. The molded article according to claim 1, wherein the ionic liquid contains an imidazolium cation.

3. The molded article according to claim 2, wherein the imidazolium cation is 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, or 1-methyl-3-n-octylimidazolium cation.

4. The molded article according to claim 1, wherein the ionic liquid comprises a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonic acid anion, a bis(trifluoromethanesulfonyl)imide anion, or a dicyanamide anion.

5. A laminate comprising a substrate and a molded body according to any one of claims 1 to 4 disposed on the substrate.

6. A method for manufacturing a molded article, comprising performing an etching treatment on a composite comprising a metal-organic structure and an ionic liquid held within the pores of the metal-organic structure.

7. The method for manufacturing a molded article according to claim 6, wherein the etching process is dry etching.

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