Nanosheet-like particles of polythiophene compounds and method for producing the same

Abstract

Provided are: nanosheet-like particles of a polythiophene-based compound, which cannot be obtained using conventional methods and which have a thickness of 10 nm or less; and a method for producing same. In particular, provided is a dispersion liquid composition containing nanosheet-like particles of a polythiophene-based compound, in which particles are stably present without aggregating. These nanosheet-like particles of a polythiophene-based compound have a thickness of 0.5-10 nm and an aspect ratio (maximum width / thickness of a particle) of 100 or more.

Description

[Technical Field]

[0001] The present invention relates to nanosheet-like particles of polythiophene compounds and a method for producing the same. This application claims priority based on Japanese Patent Application No. 2022-165782, filed in Japan on October 14, 2022, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Polythiophenes possess conductivity due to their polymeric structure, which consists of linked π-conjugated systems. Furthermore, they exhibit excellent processability and relatively high environmental and thermal stability. For these reasons, polythiophenes have recently attracted attention as a material that can be used in electrical components, such as organic thin-film solar cells, organic thin-film transistors, photoelectric conversion materials, organic EL materials, diodes, triodes, electro-optical displays, reflective films, and nonlinear optical materials.

[0003] Various methods have been reported for producing polythiophene, but generally, one method involves polymerizing thiophene using a catalyst for polythiophene polymerization. For example, one method for producing poly(3,4-ethylenedioxythiophene) (PEDOT), a derivative of polythiophene, is to obtain it by oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in an aqueous solution of polystyrene sulfonic acid using an oxidizing agent suitable for the oxidative polymerization of pyrrole, such as ferric salt, alkali metal persulfate, or ammonium persulfate (see, for example, Patent Document 1). Since PEDOT is insoluble, in the above production method, it is obtained in a state contained in a dispersion of colloidal particles. Another method for forming thin film-like PEDOT is to directly polymerize EDOT monomer, the oxidative polymerization agent ferric p-toluenesulfonic acid, a low-temperature curing binder, and a solvent on a support substrate (see, for example, Patent Document 1). Methods for forming films using a liquid containing EDOT raw materials include the gelation film formation process, the drop casting method, and the spin coating method. The film thickness of the PEDOT thin film obtained by this film deposition method is in the range of tens of nanometers to hundreds of nanometers to several micrometers (for example, Non-Patent Document 1, Patent Document 2).

[0004] Meanwhile, various methods have been investigated for producing nanosheet-like particles. For example, in a case where a bilayer film forms a super-swollen lamellar phase in a solvent, a method for producing metal-organic structure nanosheet-like particles has been disclosed in which a sheet-like metal-organic structure is formed between the two monolayers constituting the bilayer film (for example, Patent Document 3). Also, for example, in a case where a bilayer film forms a super-swollen lamellar phase in a solvent, a method for producing zeolite nanosheet-like particles has been disclosed in which a zeolite precursor (aluminosilicate) is formed between the two monolayers constituting the bilayer film (for example, Patent Document 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1-313521 [Patent Document 2] Japanese Patent Publication No. 2011-181724 [Patent Document 3] International Publication No. 2018 / 016650 [Patent Document 4] International Publication No. 2020 / 250985 [Non-patent literature]

[0006] [Non-Patent Document 1] Proceedings of the 65th Spring Meeting of the Japan Society of Applied Physics (2018 Waseda University, Nishi-Waseda Campus), Presentation Number: 18p-P3-11 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the method of forming a thin film by directly polymerizing a liquid containing EDOT raw materials has problems such as difficulty in forming thin films smaller than 10 nm and the need for expensive equipment. Furthermore, Patent Documents 3 and 4 do not disclose a method for forming nanosheet-like particles of polymers such as PEDOT by forming a layer of monomers such as EDOT and then polymerizing it. In particular, there is no disclosure of a method for forming nanosheet-like particles of polythiophene compounds.

[0008] The present invention has been made in view of the above circumstances, and aims to provide nanosheet-like particles of polythiophene compounds and a method for producing the same. It also aims to provide a dispersion containing nanosheet-like particles of polythiophene compounds. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides the following means. [1] Nanosheet-like particles of polythiophene compounds, The thickness of the nanosheet-like particles is 0.5 nm or more and 10 nm or less. Nanosheet-like particles characterized in that the aspect ratio (maximum width / thickness within the particle) of the nanosheet-like particles is 100 or more. [2] The nanosheet-like particles according to [1], characterized in that the polythiophene compound is poly(3,4-ethylenedioxythiophene). [3] The thickness of the nanosheet-like particles is 1 nm or more and 5 nm or less. The nanosheet-like particles according to [1] or [2], characterized in that the width of the nanosheet-like particles in the planar direction is 200 nm or more and 100 μm or less. [4] A first step is to form a bilayer in a solvent, add a thiophene compound to the solvent to form a super-swelled lamellar phase of the bilayer, thereby forming a layer of the thiophene compound between the two monolayers constituting one of the bilayers; The thiophene-based compound formed in the first step is subjected to oxidative polymerization using a polymerization catalyst to form nanosheet-like particles of polythiophene-based compound in the second step; A method for producing nanosheet-like particles of polythiophene compounds, characterized by containing the compound. [5] The nanosheet-like particles according to [4], wherein in the first step, the super-swelled lamellar phase of the bilayer film is formed under temperature conditions of 20°C or higher and 40°C or lower. [6] The thiophene compound is 3,4-ethylenedioxythiophene, A method for producing nanosheet-like particles of a polythiophene compound according to [4] or [5], wherein the polythiophene compound is poly(3,4-ethylenedioxythiophene). [7] A method for producing nanosheet-like particles of a polythiophene compound according to [4] or [5], wherein the polymerization catalyst is iron(III) chloride. [8] The solvent is a solvent consisting only of water or a mixed solvent containing a hydrocarbon solvent and water. A method for producing nanosheet-like particles of a polythiophene compound according to [4] or [5], wherein the mass ratio of the hydrocarbon solvent to water in the solvent is hydrocarbon solvent:water = 0:100 to 15:85. [9] The solvent is a mixed solvent containing a hydrocarbon solvent and water, A method for producing nanosheet-like particles of a polythiophene compound according to [4] or [5], wherein the mass ratio of the hydrocarbon solvent to water in the solvent is hydrocarbon solvent:water = 0.01:99.99 to 15:85.

[10] A method for producing nanosheet-like particles of a polythiophene compound according to [9], wherein the hydrocarbon solvent is hexane.

[11] A method for producing nanosheet-like particles of a polythiophene compound according to either [4] or [5], wherein the amphiphilic substance constituting the bilayer is polyethylene glycol monoalkyl ether.

[12] A method for producing nanosheet-like particles of a polythiophene compound according to

[11] , wherein the polyethylene glycol monoalkyl ether is tetraethylene glycol monomethyl ether.

[13] A method for producing nanosheet-like particles of a polythiophene compound according to

[11] , wherein the polyethylene glycol monoalkyl ether is a tetraethylene glycol monododecyl ether with a number average molecular weight of 362 or less.

[14] The method for producing nanosheet-like particles of the polythiophene-based compound according to [4] or [5], wherein the solvent contains a monohydric alcohol.

[15] The method for producing nanosheet-like particles of the polythiophene-based compound according to

[14] , wherein the monohydric alcohol is at least one selected from the group consisting of 1-propanol, 2-propanol, and 1-butanol.

[16] The method for producing nanosheet-like particles of the polythiophene-based compound according to

[15] , wherein the monohydric alcohol is 1-propanol.

[17] The method for producing nanosheet-like particles of the polythiophene-based compound according to

[15] , wherein in the solvent, the content of the monohydric alcohol is 0.1% by mass or more and 10% by mass or less.

[18] The thickness of the nanosheet-like particles is 0.5 nm or more and 10 nm or less, the width in the planar direction of the nanosheet-like particles is 200 nm or more and 100 μm or less, and the aspect ratio (maximum width in the particle / thickness) of the nanosheet-like particles is 100 or more. The method for producing nanosheet-like particles of the polythiophene-based compound according to [4] or [5].

[19] A dispersion liquid composition containing the nanosheet-like particles according to [1] or [2].

[20] Further containing a monohydric alcohol and being substantially free of water. The dispersion liquid composition according to

[19] .

Advantages of the Invention

[0010] According to the present invention, it is possible to provide nanosheet-like particles of a polythiophene-based compound having a thickness of 10 nm or less, which cannot be obtained by conventional methods, and a method for producing the same. In particular, it is possible to provide a dispersion liquid composition containing nanosheet-like particles of a polythiophene-based compound that are stably present without aggregation.

Brief Description of the Drawings

[0011] [Figure 1] AFM data of the nanosheet-like particles of the polythiophene-based compound obtained in Example A-1. [Figure 2] This is AFM data for nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 3] This is the FT-IR spectrum of the nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 4] This is a TEM image of the nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 5] This is a TEM image of the nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 6] This is a TEM image of the nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 7] This is DLS data for nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 8] This is SEM-EDX data of nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 9] This is the TG data for the nanosheet-like particles of the polythiophene compound obtained in Example A-1. [Figure 10] This is AFM data for nanosheet-like particles of polythiophene compounds obtained in Example D-1. [Figure 11] This is AFM data for nanosheet-like particles of polythiophene compounds obtained in Example D-1. [Figure 12] This is a TEM image of the nanosheet-like particles of the polythiophene compound obtained in Example D-1. [Figure 13] This is DLS data for nanosheet-like particles of polythiophene compounds obtained in Example D-1. [Figure 14] This is a photograph showing the test results of the coating properties of PEDOT nanosheet-like particles. [Figure 15] This is a photograph showing the test results for the applicability of PEDOT bulk particles. [Figure 16] This is a simulated diagram showing the coating properties of PEDOT nanosheet-like particles. [Figure 17]This is a simulated diagram showing the coating properties of PEDOT bulk particles. [Figure 18] This photograph shows the test results evaluating the effect of manufacturing conditions (pH) on the expression of PEDOT nanosheet-like particles. [Figure 19] This figure shows the test results evaluating the effect of manufacturing conditions (pH) on the yield of PEDOT nanosheet-like particles. [Figure 20] This photograph shows the results of a test evaluating the effect of manufacturing conditions (addition of SDS) on the yield of PEDOT nanosheet-like particles. [Modes for carrying out the invention]

[0012] The following describes nanosheet-like particles of polythiophene compounds and methods for producing the same according to embodiments of the present invention. These embodiments are described specifically to better illustrate the spirit of the invention and do not limit the present invention unless otherwise specified.

[0013] (Nanosheet-like particles of polythiophene compounds) The nanosheet-like particles of a polythiophene compound according to one embodiment of the present invention (also referred to as the nanosheet-like particles of this embodiment) are nanosheet-like particles formed from a polythiophene compound. The thickness of the nanosheet-like particles of this embodiment is 0.5 nm or more and 10 nm or less. The aspect ratio of the nanosheet-like particles is 100 or more. Here, the aspect ratio is the ratio of the maximum width to the thickness in the particle (maximum width / thickness). Preferably, the thickness of the nanosheet-like particles is 1 nm or more and 5 nm or less. The width of the nanosheet-like particles in the planar direction may be 200 nm or more and 100 μm or less. Here, "thiophene-based compound" means thiophene or its derivatives (for example, thiophene which may have substituents). Furthermore, "polythiophene-based compound" means polythiophene or its derivatives (for example, polymers of the aforementioned thiophene-based compounds). The nanosheet-like particles of this embodiment exhibit excellent uniformity in thickness and aspect ratio, as well as high flexibility and high adhesion due to their ultra-thin nature.

[0014] The nanosheet-like particles of this embodiment are not necessarily those obtained by the "Method for Producing Nanosheet-like Particles of Polythiophene Compounds" described later, but are preferably nanosheet-like particles having the same size, dispersion characteristics, or conductivity as those obtained by the "Method for Producing Nanosheet-like Particles of Polythiophene Compounds" described later, and are more preferably nanosheet-like particles obtained by the "Method for Producing Nanosheet-like Particles of Polythiophene Compounds" described later.

[0015] The nanosheet-like particles of this embodiment are not limited in their existing form (bulk state), and examples include being dispersed in a fluid medium, in powder form, in thin film form formed on a support substrate, or in independent sheet form. The nanosheet-like particles of this embodiment may be, for example, monodisperse nanosheet-like particles before the removal of the solution when produced by the "Method for Producing Nanosheet-like Particles of Polythiophene Compounds" described later, or they may be secondary particles formed by aggregating (e.g., stacking) the monodisperse nanosheet-like particles as primary particles. For example, it can be determined from the TEM and AFM measurement results shown in the examples described later that it is a single nanosheet-like particle as a primary particle. The width of the nanosheet-like particles in the planar direction is not particularly limited, but may be 200 nm or more and 100 μm or less. Furthermore, for example, when manufactured by the "Method for Producing Nanosheet-like Particles of Polythiophene Compounds" described later, nanosheet-like particles may be formed by depositing monodisperse nanosheet-like particles (for example, those with a planar width of 200 nm or more and 100 μm or less) onto a substrate. These nanosheet-like particles are sheets with a thickness of 0.5 nm or more and 10 nm or less (preferably 1 nm or more and 5 nm or less), and their planar width may exceed 100 μm. The nanosheet-like particles of this embodiment may include such nanosheet-like particles.

[0016] [Polythiophene compounds] The polythiophene compound of one embodiment of the present invention (also referred to as the polythiophene compound of this embodiment) is a polymer compound having a structure containing a polymer of a thiophene compound, and a polymer compound having thiophene as a partial skeleton. The degree of polymerization of the polythiophene compound of this embodiment can be estimated by a method that assumes that one nanosheet-like particle of this embodiment is made up of one molecule. For example, an example of the polythiophene compound of this embodiment may be a polymer compound having a structure containing a polymer of a thiophene compound of 150,000 to 15,000,000 units, and a polymer compound having thiophene as a partial skeleton. The thiophene compound is preferably at least one selected from the group consisting of thiophenes and their derivatives. The polythiophene compound of this embodiment may be at least one polymer selected from the group consisting of thiophenes and their derivatives, or at least one selected from the group consisting of polythiophene and its derivatives.

[0017] Examples of thiophene compounds according to this embodiment include thiophene, 3-methylthiophene, 3-ethylthiophene, 3-propylthiophene, 3-butylthiophene, 3-hexylthiophene, 3-heptylthiophene, 3-octylthiophene, 3-nonylthiophene, 3-decylthiophene, 3-methoxythiophene, 3-ethoxythiophene, 3-butoxythiophene, 3-methyl-4-methoxythiophene, 3,4-ethylenedioxythiophene, benzothiophene, and benzodithiophene. Among these, 3,4-ethylenedioxythiophene (EDOT) is preferred because it exhibits a moderate polymerization rate and excellent heat resistance of the polymer.

[0018] The polythiophene and its derivatives in this embodiment are preferably homopolymers. A homopolymer is a polymer in which multiple groups selected from the group consisting of thiophenediyl groups and substituted thiophenediyl groups are bonded together. The thiophenediyl group is preferably a thiophene-2,5-diyl group, and the substituted thiophenediyl group is preferably a 3,4-ethylenedioxythiophene-2,5-diyl group or an alkylthiophene-2,5-diyl group. Specific examples of homopolymer polythiophene and its derivatives include poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(3-octylthiophene-2,5-diyl), poly(3-dodecylthiophene-2,5-diyl), and poly(3-octadecylthiophene-2,5-diyl). Among the homopolymers of polythiophene and its derivatives, polythiophene homopolymers comprising a 3,4-ethylenedioxy group and a thiophenediyl group substituted with an alkyl group having 6 to 30 carbon atoms are preferred, and poly(3,4-ethylenedioxythiophene)(PEDOT) represented by the following formula (A) is more preferred.

[0019] [ka]

[0020] (Method for producing nanosheet-like particles of polythiophene compounds) A method for producing nanosheet-like particles of a polythiophene compound according to one embodiment of the present invention (also referred to as this embodiment) comprises a first step of forming a layer of a thiophene compound which is a monomer of the polythiophene compound, and a second step of oxidative polymerization of the thiophene compound from the layer of thiophene compound to produce nanosheet-like particles of the polythiophene compound. Here, "polythiophene compounds" and "thiophene compounds" are the same as those described in the section above (nanosheet-like particles of polythiophene compounds). The preferred examples of these are also the same.

[0021] <First step> In the first step, a layer of thiophene compounds, which are monomers of polythiophene compounds, is formed using a super-swelled lamellar phase. A bilayer film is formed in a solvent, and a thiophene-based compound is added to the solvent to form a super-swollen lamellar phase of the bilayer film. As a result, a layer of the thiophene-based compound is formed between the two monomolecular phases constituting one of the bilayer films. In other words, by forming the super-swollen lamellar phase of the bilayer film, the thiophene-based compound can be confined between the two monomolecular phases constituting one of the bilayer films. This forms a layer of the thiophene-based compound between the two monomolecular phases constituting one of the bilayer films.

[0022] In the layer of thiophene compound formed between the two monomolecular phases, for example, the monomer molecules of the thiophene compound contained in the layer of thiophene compound exist in the super-swollen lamellar phase in a state that is substantially not aggregated with each other. The molecules of the thiophene compound may be arranged in a thin two-dimensional planar space formed between the two monomolecular phases. The molecules of the thiophene compound in the thin two-dimensional planar space may have a certain orientation or a random orientation. Furthermore, one layer of thiophene compound formed between a pair of the two monomolecular phases may be arranged in the thickness direction of the layers with other similarly formed layers of thiophene compound to form a layered structure. Furthermore, the layer of thiophene compound formed between the two monomolecular phases in this manner imparts high orientation to the polythiophene compound (i.e., the nanosheet-like particles of this embodiment) obtained after subsequent polymerization, and suppresses the insulating effect caused by the presence of intermolecular spaces (i.e., exhibits high conductivity). As a result, the polythiophene compound (i.e., the nanosheet-like particles of this embodiment) obtained after polymerization can be given excellent uniformity in thickness and aspect ratio, as well as high flexibility and high adhesion due to its thinness.

[0023] Furthermore, a "polythiophene compound" (i.e., the nanosheet-like particles of this embodiment) is formed from the layer of thiophene compound (monomer layer) formed between the two monomolecular phases by a subsequent polymerization reaction. Because the space for the polymerization reaction is restricted, it is expected to grow in the planar direction. Also, considering the physical properties of the polythiophene compound, one nanosheet-like particle may be formed from one polymer. Alternatively, one nanosheet-like particle may be formed by stacking several polymers. Regarding the state and arrangement of the polymer of the polythiophene compound within the nanosheet-like particles, if the nanosheet-like particles of this embodiment contain a polythiophene compound and are nanosheet-like particles as described above, then the state and arrangement of the polymer within the nanosheet-like particles are not limited to these.

[0024] In this embodiment, first, a super-swelling lamellar phase is formed, and then a thiophene-based compound is added. As a method for forming the super-swelling lamellar phase, a bilayer film is formed in a solvent, and an amphiphilic substance is added to the solvent to form the super-swelling lamellar phase of the bilayer film.

[0025] The hyper-swollen lamellar phase refers to a specific lamellar phase that has been swollen by a solvent. More specifically, it refers to a phase in which multiple bilayer films constituting the lamellar phase are stacked in layers, with a layer of solvent in between. The phases constituting the hyper-swollen lamellar phase may exhibit coloration due to Bragg reflection in the visible light region. The hyper-swollen lamellar phase may also be the hyper-swollen lyotropic lamellar phase.

[0026] In the super-swelling lamellar phase, the mass percentage of the solvent in the whole is not particularly limited as long as the objectives of the present invention are satisfied, but is usually 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably 99% by mass or more. The upper limit is not particularly limited as long as the super-swelling lamellar phase can be formed between the solute and the solvent, and the theoretical upper limit is the limiting concentration at which the super-swelling lamellar phase can be formed between the solvents used. The term "whole" means the total sum of all the mixed substances, including the solute and the solvent. In the super-swelling lamellar phase, the upper limit of the mass percentage of the solvent in the whole can be, for example, 99% by mass.

[0027] In the super-swelled lamellar phase, the distance between adjacent bilayers (hereinafter also referred to as "interlayer distance") is not particularly limited and can be set appropriately depending on the material used and the intended application. It is usually between 50 nm and 1000 nm (including the values ​​at both ends, the same applies hereinafter). When thinning the target nanosheet-like particles, a thinner interlayer distance is preferable, for example, preferably 500 nm or less. The interlayer distance between bilayers means the distance from the edge of the solvent-affinity portion of one bilayer to the edge of the solvent-affinity portion of another bilayer adjacent to that bilayer. Furthermore, the interlayer distance may depend on the content of the molecules (amphiphilic molecules) constituting the bilayers.

[0028] The thickness of the bilayer itself is not particularly limited, but is usually between 1 nm and 20 nm. Preferably, for example, it is between 1 nm and 10 nm, and more preferably, for example, between 1 nm and 5 nm.

[0029] The super-swelling lamellar phase is maintained stably even in solutions of nonionic amphiphilic substances, due to the undulation of each layer or Helfrich interactions.

[0030] By encapsulating thiophene compounds within a bilayer of a super-swellable lamellar phase, layers of thiophene compounds can be fabricated. In particular, layers of thiophene compounds can be arranged.

[0031] After forming a super-swelled lamellar phase, a thiophene-based compound is added to the solvent to form a layer of the thiophene-based compound between the two monolayers constituting the bilayer film of 1.

[0032] In the method for forming a layer of thiophene compounds, the hydrophilic portion faces the solvent side, forming a layer of thiophene compounds between the hydrophobic portions of the two monolayers constituting the bilayer. By changing the combination of the solvent and amphiphilic molecules to be mixed, the hydrophobic and hydrophilic portions of the bilayer are arranged as described above. In this embodiment, since a layer of thiophene compounds is formed between portions that are incompatible with the solvent, a layer of thiophene compounds can be produced not only in hydrophobic reaction fields but also in hydrophilic reaction fields, depending on the type of solvent.

[0033] <Solvent> In this embodiment of the method for producing the thiophene compound layer, the solvent may consist solely of water, but it is preferable to include an organic solvent other than water. The organic solvent may be a hydrocarbon solvent. Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as cyclohexane, methylcyclohexane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-dodecane, and bicyclohexyl; and aromatic hydrocarbon solvents such as toluene, xylene, mesitylene, ethylbenzene, n-hexylbenzene, and cyclohexylbenzene. Furthermore, the solvent may consist solely of a hydrocarbon solvent, or it may be a combination of a hydrocarbon solvent and other organic solvents. Other organic solvents include ketone solvents such as acetone, acetylacetone, methyl ethyl ketone, cyclohexanone, and acetophenone; alcohol solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, cyclohexanol, ethylene glycol, diethylene glycol, propylene glycol, and glycerin; chlorine solvents such as 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene, and o-dichlorobenzene; and ether solvents such as tetrahydrofuran, dioxane, anisole, and 4-methylanisole. When using a hydrocarbon solvent and another organic solvent as the aforementioned solvent, the mass ratio of the two is preferably hydrocarbon solvent:other organic solvent = 80:20 to 99.99:0.01, and more preferably 85:15 to 99.9:0.1.

[0034] Furthermore, in this embodiment of the method for producing the thiophene compound layer, if the solvent is, for example, a solvent consisting only of water or a mixed solvent containing the organic solvent and water, the mass ratio of the two is preferably organic solvent:water = 0:100 to 15:85, and more preferably 0:100 to 10:90. Also, if the solvent is a mixed solvent containing the organic solvent and water, the mass ratio of the two is preferably organic solvent:water = 0.01:99.99 to 15:85, and more preferably 0.1:99.9 to 10:90. In addition, in these preferred embodiments, as the solvent, an acidic aqueous solution such as hydrochloric acid, nitric acid, or sulfuric acid; or a basic aqueous solution such as sodium hydroxide aqueous solution may be used instead of or in addition to water, depending on the type of reaction when synthesizing the target nanosheet-like particles. In this embodiment, the organic solvent is preferably a hydrocarbon solvent. The solvent is preferably a mixture of water and a hydrocarbon solvent, and more preferably a mixture of water and hexane. The mass ratio of the two is preferably hexane:water = 0.01:99.99 to 15:85, and more preferably 0.1:99.9 to 10:90.

[0035] <Amphiphilic substances> In this embodiment, examples of amphiphilic substances include nonionic amphiphilic substances. The amount of amphiphilic substance added per 100 parts by mass of the above solution (total amount including surfactants, if any) may be 1 to 50 parts by mass, 1 to 10 parts by mass, or 1 to 5 parts by mass.

[0036] "Nonionic amphiphilic substances" Examples of nonionic amphiphilic substances in this embodiment include ester-type surfactants, ether-type surfactants, ester-ether-type surfactants, alkanolamide-type surfactants, alkyl glycosides, and higher alcohols. Commercially available nonionic amphiphilic substances can be used.

[0037] Ester-type surfactants include sucrose fatty acid esters such as sucrose laurate, sucrose oleate, and sucrose monopalmitate; and sorbitan caprylic acid monoester, sorbitan caprylic acid diester, sorbitan caproic acid monoester, sorbitan caproic acid diester, sorbitan capric acid monoester, sorbitan capric acid diester, sorbitan laurate monoester, sorbitan laurate diester, sorbitan myristic acid monoester, and sorbitan myristic acid diester. Vitamin fatty acid esters; monoglycerin fatty acid esters such as glyceryl caprylate, glyceryl caprate, glyceryl laurate, glyceryl myristate, and di(laurate / myristic acid)glyceryl; diglyceryl monostearate, diglyceryl monooleate, diglyceryl dioleate, diglyceryl monoisostearate, tetraglyceryl monostearate, tetraglyceryl tristearate, tetraglyceryl pentastearate, tetraglyceryl pentaoleate, hexaglyceryl monolaurate, monomyristate Hexaglyceryl stearate, hexaglyceryl monostearate, hexaglyceryl monooleate, hexaglyceryl tristearate, hexaglyceryl pentastearate, hexaglyceryl pentastearate, hexaglyceryl polyricinoleate, decaglyceryl monolaurate, decaglyceryl monomyristate, decaglyceryl monostearate, decaglyceryl monooleate, decaglyceryl monolinoleate, decaglyceryl monoisostearate, decaglyceryl distearate, decaglyceryl dioleate, ji Examples include polyglycerin fatty acid esters such as decaglyceryl sostearate, decaglyceryl tristearate, decaglyceryl trioleate, decaglyceryl triisostearate, decaglyceryl pentastearate, decaglyceryl pentaoleate, decaglyceryl pentaisostearate, decaglyceryl heptastearate, decaglyceryl heptaoleate, decaglyceryl heptastearate, decaglyceryl decastearate, decaglyceryl decaoleate, and decaglyceryl decaisostearate.

[0038] Examples of ether-type surfactants include those shown in formula (1) below.

[0039] [ka]

[0040] (In the formula, n represents the number of carbon atoms in the alkyl group of the hydrophobic part, and m represents the number of ethylene oxide atoms in the hydrophilic part. n may be 3 to 40, 5 to 20, or 20 to 14. m may be 1 to 10, 2 to 8, or 3 to 6.) Polyethylene glycol monoalkyl ether (C) represented by (In the formula, n represents the number of carbon atoms in the alkyl group of the hydrophobic part, and m represents the number of ethylene oxide atoms in the hydrophilic part. n may be 3 to 40, 5 to 20, or 20 to 14. m may be 1 to 10, 2 to 8, or 3 to 6.) n E m ) Polyethylene glycol monoalkyl ether containing the following formula (2)

[0041] [ka]

[0042] (The number of moles of ethylene oxide added, p, may be 3 to 40 or 5 to 20) Poly(oxyethylene) octylphenyl ether represented by the following formula (3)

[0043] [ka]

[0044] Examples include polyoxyethylene alkylphenyl ethers such as poly(oxyethylene) nonylphenyl ether, which are represented by (the number of moles of ethylene oxide added, q, may be 3 to 40 or 5 to 20).

[0045] Examples of ester ether type surfactants include polyoxyethylene fatty acid esters such as polyethylene glycol monostearate, polyethylene glycol monooleate, and polyethylene glycol dioleate; polyoxyethylene hexitane fatty acid esters; polyoxyethylene sorbitan fatty acid esters (the sorbitan fatty acid ester portion is the same as that of the ester type surfactants mentioned above); and polyethylene glycol sorbitan fatty acid esters (the sorbitan fatty acid ester portion is the same as that of the ester type surfactants mentioned above).

[0046] Examples of alkanolamide-type surfactants include lauric acid monoethanolamide, lauric acid monoisopropanolamide, lauric acid diethanolamide, oleic acid diethanolamide, stearate diethanolamide, and cocamide DEA fatty acid alkanolamides.

[0047] Examples of alkyl glycosides include n-octyl-β-D-glucoside, n-octyl-β-D-maltoside, n-decyl-β-D-glucoside (decyl glucoside), n-decyl-β-D-maltoside, n-undecyl-β-D-glucoside, n-dodecyl-β-D-glucoside (lauryl glucoside), n-tridecyl-β-D-glucoside, n-octadecyl-β-D-glucoside, n-heptyl-β-D-thioglucoside, n-octyl-β-D-thioglucoside, and n-nonyl-β-D-thiomaltoside.

[0048] Examples of higher alcohols include cetanol, stearyl alcohol, lauryl alcohol, and oleyl alcohol, which have 12 to 18 carbon atoms.

[0049] In a preferred embodiment, the nonionic amphiphilic substance is the following formula (1)

[0050] [ka]

[0051] (wherein n and m have the same meanings as described above). The polyethylene glycol monoalkyl ether (C n E m ) may be used. Examples of the polyethylene glycol monoalkyl ether include tetraethylene glycol monomethyl ether, tetraethylene glycol monolauryl ether, and the like.

[0052] In a certain embodiment, in the above formula (1), 2 < n / m < 6 may be satisfied, 2.2 < n / m < 5 may be satisfied, or 2.4 ≤ n / m ≤ 4 may be satisfied. The lower limit value of n / m is not particularly limited, and may be 2, 2.2, or 2.4. The upper limit value of n / m is not particularly limited, and may be 6, 5, 4, or 3. The nonionic amphiphilic substance according to this embodiment is preferably tetraethylene glycol monolauryl ether (C12E4). Examples of tetraethylene glycol monolauryl ether (C12E4) include polyethylene glycol dodecyl ether (Brij (registered trademark) L4 manufactured by Sigma-Aldrich) used in the examples described later.

[0053] [Surfactant adjuvant] In addition, in this embodiment, the solvent may contain a surfactant adjuvant for stabilizing the amphiphilic substance. Examples of the surfactant adjuvant include monohydric alcohols, glycol-based polyhydric alcohols, and derivatives thereof. In this embodiment, it is particularly preferable that the solvent contains a monohydric alcohol. Examples of monohydric alcohols include ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 2-methyl-1-pentanol, 4-methyl Examples include monohydric alcohols having 1 to 10 carbon atoms, such as ethyl-2-pentanol, 2-ethyl-1-butanol, 2-heptanol, 3-heptanol, 2-octanol, 2-ethyl-1-hexanol, and 3,5,5-trimethyl-1-hexanol; cholesterol, cholesteryl alkenylsuccinate, cholestanol, cholesteryl esters having saturated or unsaturated linear or branched hydrocarbon groups with 12 to 36 carbon atoms (preferably 14 to 28 carbon atoms), cholesterol and its derivatives, such as dehydrocholesterol.

[0054] Examples of glycol-based polyhydric alcohols or their derivatives include glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol-1-methyl ether, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and triethylene glycol dimethyl ether; glycol ether acetates such as ethylene glycol methyl ether acetate and diethylene glycol ethyl ether acetate; diols such as ethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, and hexylene glycol; and polyols such as glycerin, pentaerythritol, and sorbitol.

[0055] In this embodiment, the solvent is a mixed solvent of a hydrocarbon solvent such as hexane and water, the amphiphilic substance is a nonionic amphiphilic substance such as polyethylene glycol monoalkyl ether (CnEm), and the solvent may further contain a surfactant such as a monohydric alcohol.

[0056] The thiophene compound layer according to this embodiment may also contain other compounds.

[0057] In this embodiment, the formation temperature for the super-swelling lamellar phase is preferably 15°C to 60°C, more preferably 20°C to 40°C, and even more preferably 25°C to 35°C. It is even more preferably 28°C to 32°C.

[0058] In the first step according to this embodiment, the pH of the system for forming the super-swollen lamellar phase of the bilayer film may be controlled in advance. For example, instead of water used as the solvent, a buffer solution that has been adjusted to a desired pH in advance may be used. The pH of the mixture in the system can be, for example, in the range of 2 to 7. Preferably, it is in the range of 2 to 4.

[0059] In the first step according to this embodiment, sodium dodecyl sulfate (hereinafter referred to as SDS) may be added to the system for forming the super-swollen lamellar phase of the bilayer film. For example, the concentration of SDS in the mixed solution in the system can preferably be 0.15% by mass or less.

[0060] [Specific example of the first step] A preferred example of the first step of the manufacturing method of this embodiment will be described. The reagents and conditions to be used are as follows: Thiophene compounds: For example, 3,4-ethylenedioxythiophene (EDOT) Solvent: For example, water, or a mixed solvent of hexane and water. Surface surfactant: 1-propanol Amphiphilic substances: For example, tetraethylene glycol monododecyl ether (C12E4) Formation temperature: For example, 25°C to 35°C Stirring time: For example, 15-30 hours Stirring speed: For example, 100-500 rpm

[0061] First, the thiophene compound, amphiphilic substance, surfactant, and solvent are mixed. The mixing order of each reagent is not particularly limited, but for example, the thiophene compound, amphiphilic substance, surfactant, and solvent may be mixed in that order. The resulting mixture is stirred at a predetermined stirring temperature. The stirring speed may vary depending on the stirring device, but for example, when using a hot stirrer, it may be 100-500 rpm or 200-400 rpm.

[0062] Examples of the amounts of each reagent added to the aforementioned mixture include the following: The thiophene compound may be present in an amount of 0.05 to 0.5% by mass, or 0.10 to 0.2% by mass. The amphiphilic substance may be 2.5 to 7.5% by mass, or 4.0 to 5.0% by mass; the solvent may be 5.0 to 8.0% by mass, or 6.0 to 7.0% by mass. Water: 70.0-95.0% by mass is acceptable, and 86.0-90.0% by mass is also acceptable.

[0063] The thickness of the thiophene compound layer can be adjusted by appropriately combining conditions such as the thickness of the bilayer film, the composition ratio of the raw materials, the reaction temperature, and the reaction time. Furthermore, for example, the texture derived from the super-swollen lamellar phase can be confirmed using a polarizing plate, thereby confirming the formation of the super-swollen lamellar phase.

[0064] <Second process> In the second step according to this embodiment, an oxidative polymerization catalyst is added to the solution as a polymerization catalyst to oxidatively polymerize the thiophene compound and produce nanosheet-like particles of the polythiophene compound.

[0065] [Polymerization catalyst] The polymerization catalyst according to this embodiment is not particularly limited as long as it can polymerize the thiophene compound in the layer of thiophene compound obtained in the first step to synthesize a polythiophene compound. The polymerization catalyst according to this embodiment is preferably, for example, an oxidative polymerization catalyst. Examples of known oxidative polymerization catalysts include iron(III) chloride, iron p-toluenesulfonate, copper perchlorate, palladium acetate, and copper acetate.

[0066] In the second step of this embodiment, the reaction conditions for synthesizing the polythiophene compound using a polymerization catalyst are not particularly limited, but the following range is preferred. The reaction temperature may be 25-40°C or 30-35°C. Amount of polymerization catalyst to add: For example, 0.05 to 0.2 parts by mass or 0.075 to 0.12 parts by mass per 100 parts by mass of the mixture obtained in the first step.

[0067] In the second step of this embodiment, the polymerization reaction time may be 8 to 48 hours or 12 to 24 hours. The completion of the polymerization reaction can be confirmed by infrared spectroscopy.

[0068] In the second step according to this embodiment, the pH of the reaction field for oxidative polymerization of the thiophene compound that has formed a layer using a polymerization catalyst may be controlled in advance. For example, instead of water used as the solvent, a buffer solution that has been adjusted to a desired pH in advance may be used. The pH of the mixed solution that forms the reaction field can be, for example, in the range of 2 to 7. Preferably, it is in the range of 2 to 4. Lowering the pH of the reaction field allows the oxidizing agent (e.g., Fe) to be used as a polymerization catalyst. 3+ The oxidation-reduction potential of the oxidizing agent increases, and it is expected that the oxidizing power of the oxidizing agent will increase, thereby promoting the oxidative polymerization.

[0069] In the second step according to this embodiment, SDS may be added to the reaction field for oxidative polymerization of the thiophene compound that has formed a layer using a polymerization catalyst. For example, the concentration of SDS in the mixed solution that forms the reaction field can preferably be 0.15% by mass or less. If a small amount of SDS is present in the reaction field, the electrostatic attraction of the SDS will cause the oxidizing agent (for example, Fe) to act as a polymerization catalyst. 3+ It is expected that this will attract ) and, as a result, the oxidative polymerization can be promoted.

[0070] <Third step> The method for producing nanosheet-like particles according to this embodiment preferably further includes a third step. In the third step, the solvent is removed from the solution containing the nanosheet-like particles obtained in the second step, and the solution is dried. The resulting dried solid may be in the form of a powder, granules, or other molded body, or it may be supported on a substrate. To form the dried solid into granules, known granulation methods such as extrusion, spray drying, agitation granulation, and tumbling granulation can be used.

[0071] For example, the solvent, surfactant, amphiphilic substance, or polymerization catalyst added in the first step can be removed by centrifugation. Ethanol and water are used as solvents for washing. The added solvent, water, surfactant, and amphiphilic substance are removed with ethanol, and the polymerization catalyst is removed with water. After washing, the nanosheet-like particles of this embodiment may be dispersed in ethanol or the like without drying. Alternatively, they may be dried. In that case, for example, the solvent may be evaporated by leaving them in an oven set to a certain drying temperature. The drying temperature can be adjusted as appropriate in relation to the drying time, and is not particularly limited as long as drying is achieved. For example, it may be 50-95°C or 80-95°C.

[0072] Furthermore, it is more preferable that the nanosheet-like particles obtained in this embodiment are arranged in an orderly manner such that they have high orientation and suppress the insulating effect caused by the presence of intermolecular spaces (i.e., exhibit high conductivity) in the arrangement state of the polythiophene-based compound. Such nanosheet-like particles have excellent uniformity in thickness and aspect ratio, and possess high flexibility and high adhesion due to their thinness.

[0073] Incidentally, when using conventional film deposition methods such as drop casting and spin coating, observing the surface microstructure of nanosheet particles of thiophene compounds after film deposition using STM imaging often reveals that the thiophene compound layer exhibits a random granular structure, weak orientation, or variations depending on the location.

[0074] (Dispersion composition containing nanosheet-like particles of polythiophene compounds) A dispersion composition containing nanosheet-like particles of a polythiophene compound according to one embodiment of the present invention (the dispersion composition of this embodiment) is a dispersion composition containing the aforementioned nanosheet-like particles of a polythiophene compound. Alternatively, the dispersion composition of this embodiment is a dispersion composition containing nanosheet-like particles of a polythiophene compound obtained by the method for producing the nanosheet-like particles of the polythiophene compound. The dispersion composition of this embodiment preferably further contains a monohydric alcohol and is substantially water-free. Here, "substantially water-free" means that the dispersion composition contains 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less of water. It may also contain 0.0001% by mass (1 ppm) or more of water. The monohydric alcohol is the same specific example as the monohydric alcohol described in the method for producing nanosheet-like particles of this embodiment described above. The monohydric alcohol contained in the dispersion composition of this embodiment may be the same as or different from the monohydric alcohol used as a surfactant in the method for producing nanosheet-like particles of this embodiment. In the dispersion composition of this embodiment, the content of the nanosheet-like particles of this embodiment may be 0 to 100% by mass, or 0 to 1% by mass. A method for producing the dispersion composition of this embodiment is to add a monohydric alcohol to a solution containing nanosheet particles obtained after the second step of the method for producing nanosheet particles of this embodiment described above, and then remove water from the solution.

[0075] [Applications of nanosheet-like particles] Applications of the nanosheet-like particles of this embodiment include, for example, use as conductive polymer nanosheet materials, thermoelectric thin film materials, organic strain sensors, and biological information monitors.

[0076] <Conductive polymer nanosheet material> Specific applications of conductive polymer nanosheet materials include products such as antistatic films, solid electrolytic capacitors, and organic electroluminescent devices, as well as fields such as organic solar cells, organic transistors, and transparent electrodes. For example, the electrical conductivity can range from 0.1 S / cm to 10,000 S / cm, preferably 1 S / cm to 1,000 S / cm.

[0077] <Thermoelectric thin film materials> Specific applications of thermoelectric thin-film materials include, for example, sheets or fibers that utilize the flexible properties of thermoelectric materials that recover a portion of the waste heat discharged into the atmosphere and reuse it as electrical energy, from everyday products such as automobiles and home appliances to large-scale facilities such as power plants and factories. Examples include adhesive thermoelectric power generation sheets (e.g., utilizing waste heat from factory piping) and self-contained power supplies for IoT sensors (e.g., utilizing waste heat from electrical appliances).

[0078] <Organic Strain Sensor> Specific applications of organic strain sensors include, for example, the need to accurately measure the deformation of flexible biological tissue in order to create artificial organs that can reproduce movements similar to those of living organs. This includes products such as sensors for measuring strain data generated on the surface of such biological tissue, as well as hybrid artificial organs that combine such sensors with cells and tissues.

[0079] <Vital Signs Monitor> Specific applications as a bio-information monitor include, for example, ultra-thin electrodes that can be attached to the skin to measure bioelectrical signals (e.g., body temperature, pH, heart rate, electromyography) (i.e., electronic nano-bandages), self-powered devices for wearable sensor devices used not only in daily life but also in healthcare, medical, and sports settings (e.g., utilizing body temperature), and next-generation wearable devices.

[0080] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Examples]

[0081] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0082] (Evaluation method)

[0083] [AFM (Atomic Force Microscopy)] Equipment: Veeco Instruments, Product Name: MMAFM-2 Measurement conditions: Room temperature, under atmospheric conditions Preparation of evaluation samples: Add a few milligrams of the sample to ethanol and apply ultrasound to prepare an ethanol dispersion. Drop the prepared dispersion onto a mica substrate. Absorb any excess dispersion and dry it to complete the preparation.

[0084] [FT-IR (Fourier Transform Infrared Spectroscopy)] Measurement conditions: Room temperature, under atmospheric conditions Equipment: Manufactured by JASCO Product name: FT / IR-4600 Preparation of evaluation samples: Sample powder is fixed onto a metallic disc to prepare the sample.

[0085] [TEM (Transmission Electron Microscopy)] Measurement conditions: 1 × 10 -6 Pa Equipment: Hitachi Corporation, Product Name: H-800 Preparation of evaluation samples: A few milligrams of the sample are added to ethanol, and an ethanol dispersion is prepared by applying ultrasound. The prepared dispersion is then dropped onto a TEM microgrid and dried to create the final sample.

[0086] [DLS (Dynamic Light Scattering)] Device: Manufactured by Otsuka Electronics Co., Ltd. Product name: ELSZ-2000 Measurement conditions: Room temperature, under atmospheric conditions Preparation of evaluation samples: An ethanol dispersion is prepared by adding a few mg of the sample to ethanol and applying ultrasound. The prepared dispersion (approximately 1.5 ml) is added to a plastic cuvette for DLS and measured.

[0087] [Electrical Conductivity] Device: ATTO Corporation, Product Name: CROSSPOWER500 Measurement conditions: Room temperature, under atmospheric conditions Preparation of evaluation samples: Add a few milligrams of the sample to ethanol and apply ultrasound to prepare an ethanol dispersion. The prepared dispersion is then dropped onto a glass slide and dried.

[0088] (Example) 0.0050 g of PEDOT nanosheet-like particles were dispersed in 2 g of 0.1 MHCL solution. The resulting mixture was stirred with ultrasound to prepare a dispersion. This dispersion was applied to a glass substrate by drop casting, and a thin film of polythiophene was obtained by drying. The electrical conductivity of the 1 μm thick thin film obtained in this way was evaluated using a small digital tester. The measurement result was 1 S / cm. By comparing this with a commercially available PEDOT:PSS measured by the same method, the electrical conductivity was calculated to be approximately 1 S / cm. The calculation method involved treating the applied area as a rectangular parallelepiped with a height of 1 μm and a width of 1 cm, and measuring the resistance at 1 cm intervals.

[0089] [SEM-EDX (Energy Dispersive X-ray Spectroscopy)] Equipment: Manufactured by JEOL Product name: JCM-7000 Measurement conditions: High vacuum Preparation of evaluation samples: Samples are prepared by attaching the powder sample to carbon tape.

[0090] [TG(Thermogravimetric Analysis)] Device: Shimadzu Corporation, Product Name: DTG-60 Measurement conditions: Under a nitrogen atmosphere Preparation of evaluation sample: Place the powder sample (20 mg) into an aluminum cell.

[0091] [Electrical conductivity measurement] "Preparation of measurement samples" PEDOT bulk particles and PEDOT nanosheet particles are dispersed in water, and the respective aqueous dispersions (concentration: 3.4 × 10⁻⁶) are prepared. -4 A solution (g / ml) was prepared. "Measurement method" The obtained aqueous dispersion was dropped onto a comb-shaped electrode (with a 2-μm gap between the Pt teeth, manufactured by PSS), and then the electrode was dried. After drying, the conductivity of the electrode was measured using an impedance analyzer (SI1260 model, manufactured by Toyo Technica).

[0092] [Coating property evaluation] "Preparation of measurement samples" PEDOT bulk particles and PEDOT nanosheet-like particles were each dispersed in water, and aqueous dispersions (concentration: 3.4×10 -4 g / ml) were prepared. "Evaluation method" The obtained aqueous dispersion was dropped onto a comb-shaped electrode (with a 2-μm gap between the Pt teeth), and then the electrode was dried. After drying, the electrode was visually observed using a research system microscope BX-51 (manufactured by Olympus). Judgment criteria: Regarding the state of being uniformly dispersed so that no voids occur between the particles, if the particle thickness is substantially uniform and based on the degree of adhesion between the particles, and these aspects are good, it was evaluated as having excellent coating properties.

[0093] (Example A-1) [[ID=CO21]] (Production of PEDOT nanosheet-like particles)

[0094] <First step> (That is, a bilayer membrane composed of tetraethylene glycol monododecyl ether having a number average molecular weight of 362 or less in water containing 1-propanol and having a content of the 1-propanol of 0.1% by mass or more and 10% by mass or less is formed, 3,4-ethylenedioxythiophene is added to the solvent, and a super swollen lamellar phase of the bilayer membrane is formed under temperature conditions of 20°C or higher and 40°C or lower, and a layer of the 3,4-ethylenedioxythiophene is formed between two unimolecular phases constituting one bilayer membrane, the first step)

[0095] <Reagents used and reaction conditions> EDOT (manufactured by Fujifilm Wako Pure Chemical Industries, 0.13% by mass) 0.04 g Deionized water (88.6% by mass) 27g 1-Propanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 6.56% by mass) 2.0g Polyethylene glycol dodecyl ether (Brij L4 Sigma-Aldrich, 4.59% by mass) 1.4g Reaction temperature: 30℃ Stirring speed: 300rpm

[0096] 0.04 g of EDOT, 1.4 g of Brij® L4, 2.0 g of 1 propanol, and 27 g of water were quantitatively added to a 50 ml screw-cap tube. The mixture was then stirred at 30°C and 300 rpm. After confirming the texture derived from the super-swollen lamellar phase using a polarizing plate, a mixture containing the super-swollen lamellar phase was obtained.

[0097] <Second process> (That is, the second step involves oxidative polymerization of the 3,4-ethylenedioxythiophene contained in the 3,4-ethylenedioxythiophene layer using iron(III) chloride to form a nanosheet of poly(2,3-dihydrothieno-1,4-dioxin).)

[0098] <Reagents used and reaction conditions> Deionized water (3ml) FeCl3·6H2O (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 0.0039g Reaction temperature: 30℃ Reaction time: 24 hours We confirmed that the reaction proceeded while maintaining the bilayer film. A 3 ml aqueous solution of iron(III) chloride was prepared using 0.0039 g of iron(III) chloride. The mixture obtained in the first step was heated to 30°C, and 3 ml of the above iron(III) chloride aqueous solution was added dropwise to the 30°C mixture using a pipette.

[0099] <Third step> (That is, the third step involves removing the solvent from the solution containing the nanosheet-like particles obtained in the second step and drying it.) The solvents, water, polymerization catalyst, surfactants, and amphiphilic substances added in the first and second steps were removed by centrifugation. Ethanol and water were used as solvents for washing. The added solvents, water, surfactants, and amphiphilic substances were removed with ethanol, and the polymerization catalyst was removed with water. After washing, the mixture may be stored as a dispersion of ethanol or the like without drying. Alternatively, drying was performed by leaving the mixture in an oven set to 90°C to evaporate the solvent.

[0100] <Evaluation Results> The AFM measurement results are shown in Figures 1 and 2. AFM measurement results showed that the thickness was 2 nm, the maximum width in the planar direction was 800 nm, and the aspect ratio (maximum width / thickness within the particle) was 600. The FT-IR measurement results are shown in Figure 3. A peak originating from PEDOT was confirmed. The TEM measurement results are shown in Figures 4-6. The TEM measurements confirmed the formation of nanosheet-like particles. The DLS measurement results are shown in Figure 7. TEM and DLS results confirmed the presence of sheet-like nanoparticles. The nanosheet-like particles were found to be composed of interconnected small nanoplatelets, and small aggregates were also observed. Electrical conductivity was measured. The electrical conductivity is approximately 1 S / cm. The SEM-EDX measurement results are shown in Figure 8. Removal of impurities (Fe) was confirmed. The TG measurement results are shown in Figure 9. Iron removal was confirmed.

[0101] (Examples A-2 to A-3) Nanosheet-like particles of PEDOT were obtained using the same method as in Example A-1, except that the amount of 1-propanol added as a surfactant was changed as shown in Table 1.

[0102] [Table 1]

[0103] The evaluation criteria for "stability" in Table 1 are as follows: ◎: Particularly desirable condition ○: Desirable state

[0104] (Examples B-1 to B-2) Nanosheet-like particles of PEDOT were obtained using the same method as in Example A-1, except that the alcohols shown in Table 2 were used as surfactants.

[0105] [Table 2]

[0106] The evaluation criteria for "lamellar layer expression" in Table 2 are as follows: ◎: Particularly desirable condition

[0107] (Examples C-1 to C-5, Comparative Examples C-1 to C-6) Nanosheet-like particles of PEDOT obtained in Example A-1 (3.4 × 10⁻⁶) -4 A dispersion was obtained by dispersing g) in the solvents (1 ml) shown in Tables 3 and 4 (Comparative Examples). Dispersion in the solvent by nanosheet particle formation was confirmed.

[0108] [Table 3]

[0109] [Table 4]

[0110] The evaluation criteria for "degree of variance" in Tables 3 and 4 are as follows: ◎: Particularly desirable condition ○: Desirable state △: Partially favorable condition ×: Undesirable state

[0111] The evaluation criteria for "stability" in Tables 3 and 4 are as follows: ◎: Particularly desirable condition ○: Desirable state △: Partially favorable condition ×: Undesirable state

[0112] The evaluation criteria for "electrical conductivity" in Tables 3 and 4 are as follows: ◎: Particularly desirable condition ○: Desirable state △: A state that has deteriorated from a favorable state.

[0113] (Consideration) From the results above, it was found that the obtained PEDOT nanosheet-like particles can be dispersed in a solvent without PSS, and that the nanosheet-like particles can be dispersed in both polar and nonpolar solvents.

[0114] (Example D-1) (Manufacturing of polythiophene (PT) nanosheet-like particles) <First step>

[0115] <Reagents used and reaction conditions> Thiofen (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 0.12% by mass) 0.0356g Deionized water (88.8% by mass) 27.0g Hexane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 0.042% by mass) 0.0127 g 1-Propanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 6.74% by mass) 2.05g Polyethylene glycol dodecyl ether (Brij L4 Sigma-Aldrich, 4.31% by mass) 1.31 g Reaction temperature: 30℃ Stirring speed: 300rpm

[0116] 0.0356 g of thiophene, 1.31 g of Brij® L4, 2.05 g of 1-propanol, 0.0127 g of hexane, and 27.0 g of water were quantitatively added to a 50 ml screw-cap tube. The mixture was then stirred at 30°C and 300 rpm. After confirming the texture derived from the super-swollen lamellar phase using a polarizing plate, a mixture containing the super-swollen lamellar phase was obtained.

[0117] <Second process> <Reagents used and reaction conditions> Deionized water (3ml) FeCl3·6H2O (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 0.0010g Reaction temperature: 30℃ Reaction time: 24 hours We confirmed that the reaction proceeded while maintaining the bilayer film. A 3 ml aqueous solution of iron(III) chloride was prepared using 0.0039 g of iron(III) chloride. The mixture obtained in the first step was heated to 30°C, and 3 ml of the above iron(III) chloride aqueous solution was added dropwise to the 30°C mixture using a pipette.

[0118] <Third step> The solvents, water, polymerization catalyst, surfactants, and amphiphilic substances added in the first and second steps were removed by centrifugation. Ethanol and water were used as solvents for washing. The added hexane, water, surfactants, and amphiphilic substances were removed with ethanol, and the polymerization catalyst was removed with water. After washing, the mixture may be stored as a dispersion of ethanol or the like without drying. Alternatively, drying was performed by leaving the mixture in an oven set to 90°C to evaporate the solvent.

[0119] <Evaluation Results> The AFM measurement results are shown in Figures 10 and 11. AFM measurement results showed that the thickness was 3.5 nm, the maximum width in the planar direction was 150 nm, and the aspect ratio (maximum width / thickness within the particle) was approximately 40. The TEM measurement results are shown in Figure 12. The TEM measurements confirmed the formation of nanosheet-like particles. The DLS measurement results are shown in Figure 13. TEM and DLS results confirmed the presence of sheet-like nanoparticles. The nanosheet-like particles were found to be composed of interconnected small nanoplatelets, and small aggregates were also observed.

[0120] (Example E-1) (Measurement of electrical conductivity of PEDOT nanosheet-like particles) Nanosheet-like particles of PEDOT were obtained using the same method as in Example A1. The conductivity of the nanosheet-like particles of PEDOT was measured using the measurement method described in [Conductivity Measurement] above. The results are shown in Table 5.

[0121] (Comparative Example E-1) (Measurement of electrical conductivity of bulk particles using PEDOT) The conductivity of PEDOT bulk particles, prepared in the same manner as in Example A-1 except for the use of a solvent system that does not contain polyethylene glycol dodecyl ether, was measured in the same manner as in Example E-1. The results are shown in Table 5. [Table 5]

[0122] <Discussion of Evaluation Results> It was confirmed that PEDOT nanosheet particles exhibit superior conductivity compared to PEDOT bulk particles.

[0123] (Example E-2) Using PEDOT nanosheet-like particles similar to those in Example E-1, the coating properties were evaluated using the evaluation method described in [Coating Properties Evaluation] above. Visual inspection confirmed excellent dispersion and uniformity. A photograph of the evaluation sample using the BX-51 microscope (manufactured by Olympus Corporation) is shown in Figure 14.

[0124] (Comparative Example E-2) Using PEDOT bulk particles similar to those in Comparative Example E-1, the coating properties were evaluated in the same manner as in Example E-2. Visual inspection revealed that the dispersion and uniformity were inferior compared to Example E-2. A photograph of the evaluation sample using the BX-51 microscope (manufactured by Olympus Corporation) is shown in Figure 15.

[0125] <Discussion of Evaluation Results> Figures 16 and 17 are schematic diagrams of the samples obtained in Example E-2 and Comparative Example E-2, respectively. The results from Example E-2 and Comparative Example E-2 confirmed that PEDOT nanosheet particles exhibited superior dispersion and uniformity compared to PEDOT bulk particles. Specifically, as can be seen from the micrographs in Figures 14 and 15, PEDOT nanosheet particles were able to be coated more evenly and uniformly onto the comb-shaped electrode than PEDOT bulk particles. This is likely because, in the case of PEDOT bulk particles, the particle size is non-uniform, resulting in many gaps between particles when coated. On the other hand, in the case of PEDOT nanosheet particles, the thickness of the particles (i.e., the sheets) is almost uniform, so the particles adhere to each other easily, resulting in fewer gaps between particles (sheets) when coated. Furthermore, the conductivity measurement results for Example E-1 and Comparative Example E-1 suggest that, as the gaps between particles decrease, the contact resistance decreases, and as a result, the conductivity of the PEDOT nanosheet-like particles increases, leading to improved conductivity.

[0126] (Example E-3) "Effect of manufacturing conditions (pH) on the emergence of PEDOT nanosheet-like particles" EDOT (0.13 mass%), hydrogen peroxide (0.65 mass%), Brij L4 (4.57 mass%), 1-propanol (6.52 mass%), and phosphate buffer (88.1 mass%) pre-prepared for various pH values ​​(pH 2, 3, 4, 5, 6, 7) were added to screw-cap tubes and mixed. Each resulting mixture was stirred at room temperature (25°C). During stirring, the presence or absence of the super-swollen lamellar phase was observed while checking for birefringence derived from the super-swollen lamellar phase. The results are shown in Figure 18. The evaluation results from the photograph in Figure 18 are shown in Table 6 below.

[0127] [Table 6]

[0128] Furthermore, the evaluation criteria for the "expression of the super-swelled lamellar phase" in Figure 18 were as follows. ○: Desirable state △: Partially favorable condition ×: Undesirable state

[0129] <Consideration> The results in Figure 18 show that the super-swollen lamellar phase was observed at all pH values ​​from pH 2 to 7, indicating a favorable state (i.e., a state in which thin nanosheets can be stably produced), and it was confirmed that the pH value does not affect the expression of the super-swollen lamellar phase. In particular, at pH values ​​between pH 2 and 4, the state was especially favorable (i.e., a very stable state in which the largest nanosheets can be produced), and it was found that this did not significantly affect the yield of PEDOT nanosheet-like particles.

[0130] (Example E-4) "Effect of manufacturing conditions (pH) on the yield of PEDOT nanosheet-like particles" EDOT (0.13 mass%), hydrogen peroxide (0.65 mass%), Brij L4 (4.57 mass%), 1-propanol (6.52 mass%), and phosphate buffer (88.1 mass%) pre-prepared for various pH values ​​(pH 2, 3, 4, 5) were added to a screw-cap tube and mixed. Each resulting mixture was stirred at room temperature (25°C). During stirring, the presence or absence of the formation of the super-swollen lamellar phase was observed while checking for birefringence derived from the super-swollen lamellar phase. After the above procedure, an aqueous iron chloride solution was added to the resulting mixture. The resulting mixture was stirred for a further 24 hours. After stirring, the recovered mixture was centrifuged at 11,000 rpm, and the precipitate was collected. The recovered precipitate was washed three times with ethanol, and the mass of the dried product obtained was measured, and the yield of the obtained PEDOT nanosheet-like particles was calculated. The results are shown in Figure 19.

[0131] <Consideration> The results in Figure 19 confirm that pH values ​​between pH 2 and 4 do not significantly affect the yield of PEDOT nanosheet-like particles.

[0132] (Example E-5) "Effect of manufacturing conditions (addition of SDS) on the yield of PEDOT nanosheet-like particles" EDOT (0.13 mass%), hydrogen peroxide solution (0.65 mass%), Brij L4 (4.57 mass%), 1-propanol (6.52 mass%), and water (88.1 mass%) were added to a screw-cap tube and mixed. The resulting mixture was stirred at room temperature (25°C) to form a super-swollen lamellar phase. Next, sodium dodecyl sulfate (SDS) was added to the mixture containing the formed super-swollen lamellar phase at various concentrations (0.098% by mass, 0.130% by mass, 0.147% by mass, 0.166% by mass, 0.180% by mass, 0.195% by mass) and mixed. Each of the resulting mixtures was stirred at room temperature (25°C). During stirring, the maintenance state of the super-swollen lamellar phase was observed while checking the birefringence originating from the super-swollen lamellar phase. The results are shown in Figure 20. The evaluation results from the photograph in Figure 20 are shown in Table 7 below.

[0133] [Table 7]

[0134] Furthermore, the evaluation criteria for the "maintenance of the super-swollen lamellar phase" in Figure 20 were as follows. ○: Desirable state △: Partially favorable condition ×: Undesirable state

[0135] <Consideration> As shown in Figure 20, the SDS concentration between 0.098% by mass and 0.147% by mass was favorable (i.e., a state in which thin nanosheets could be stably formed). Furthermore, all of these values ​​were particularly favorable (i.e., a state in which the largest nanosheets could be formed and which was very stable), confirming that a highly stable super-swelled lamellar phase was maintained.

Claims

1. Nanosheet-like particles of polythiophene compounds, The polythiophene compound is polythiophene or a derivative thereof. The thickness of the nanosheet-like particles is 0.5 nm or more and 10 nm or less. The aspect ratio of the nanosheet-like particles is 100 or more. Nanosheet-like particles characterized by the following features.

2. The polythiophene compound is a polymer of a thiophene compound, which is at least one selected from the group consisting of thiophene, 3-methylthiophene, 3-ethylthiophene, 3-propylthiophene, 3-butylthiophene, 3-hexylthiophene, 3-heptylthiophene, 3-octylthiophene, 3-nonylthiophene, 3-decylthiophene, 3-methoxythiophene, 3-ethoxythiophene, 3-butoxythiophene, 3-methyl-4-methoxythiophene, 3,4-ethylenedioxythiophene, benzothiophene, and benzodithiophene. Nanosheet-like particles according to feature 1.

3. The polythiophene compound is at least one selected from the group consisting of poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene-2,5-diyl), poly(3-octylthiophene-2,5-diyl), poly(3-dodecylthiophene-2,5-diyl), and poly(3-octadecylthiophene-2,5-diyl). Nanosheet-like particles according to claim 1 or 2.

4. The nanosheet-like particles according to claim 1 or 2, characterized in that the polythiophene compound is poly(3,4-ethylenedioxythiophene).

5. The thickness of the nanosheet-like particles is 1 nm or more and 5 nm or less. The width of the nanosheet-like particles in the planar direction is 200 nm or more and 100 μm or less. Nanosheet-like particles according to claim 1 or 2.

6. A first step involves forming a bilayer in a solvent, adding a thiophene-based compound to the solvent to form a super-swelled lamellar phase of the bilayer, thereby forming a layer of the thiophene-based compound between the two monolayers constituting one of the bilayers; The thiophene-based compound formed in the first step is subjected to oxidative polymerization using a polymerization catalyst to form nanosheet-like particles of polythiophene-based compound in the second step; A method for producing nanosheet-like particles of polythiophene compounds, characterized by containing the compound.

7. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6, wherein in the first step, the super-swelled lamellar phase of the bilayer film is formed under temperature conditions of 20°C or higher and 40°C or lower.

8. The thiophene compound is 3,4-ethylenedioxythiophene. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the polythiophene compound is poly(3,4-ethylenedioxythiophene).

9. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the polymerization catalyst is iron(III) chloride.

10. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the solvent is a solvent consisting solely of water or a mixed solvent containing a hydrocarbon solvent and water, and the mass ratio of the hydrocarbon solvent to water in the solvent is hydrocarbon solvent:water = 0:100 to 15:

85.

11. The aforementioned solvent is a mixed solvent containing a hydrocarbon solvent and water. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the mass ratio of the hydrocarbon solvent to water in the solvent is hydrocarbon solvent:water = 0.01:99.99 to 15:

85.

12. A method for producing nanosheet-like particles of a polythiophene compound according to claim 11, wherein the hydrocarbon solvent is hexane.

13. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the amphiphilic substance constituting the bilayer is polyethylene glycol monoalkyl ether.

14. A method for producing nanosheet-like particles of a polythiophene compound according to claim 13, wherein the polyethylene glycol monoalkyl ether is tetraethylene glycol monomethyl ether.

15. The method for producing nanosheet-like particles of a polythiophene compound according to claim 13, wherein the polyethylene glycol monoalkyl ether is a tetraethylene glycol monododecyl ether with a number average molecular weight of 362 or less.

16. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the solvent comprises a monohydric alcohol.

17. A method for producing nanosheet-like particles of a polythiophene compound according to claim 16, wherein the monohydric alcohol is at least one selected from the group consisting of 1-propanol, 2-propanol, and 1-butanol.

18. A method for producing nanosheet-like particles of a polythiophene compound according to claim 16, wherein the monohydric alcohol is 1-propanol.

19. A method for producing nanosheet-like particles of a polythiophene compound according to claim 17, wherein the content of the monohydric alcohol in the solvent is 0.1% by mass or more and 10% by mass or less.

20. The thickness of the nanosheet-like particles is 0.5 nm or more and 10 nm or less. The width of the nanosheet-like particles in the planar direction is 200 nm or more and 100 μm or less. A method for producing nanosheet-like particles of a polythiophene compound according to claim 6 or 7, wherein the aspect ratio (maximum width / thickness within the particle) of the nanosheet-like particles is 100 or more.

21. A dispersion composition comprising nanosheet-like particles according to claim 1 or 2.

22. Furthermore, it contains a monohydric alcohol, The dispersion composition according to claim 21, characterized in that it is substantially free of water.

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