Polymer membrane for generating fine water particles

Abstract

A polymer membrane 10 for generating fine water particles comprises: a plurality of particles 20 that each have a core-shell structure having a rod-shaped core 22, which contains PEDOT, and a shell 24 containing PSS and covering the core 22; and nanochannels 30 that are formed between the plurality of particles 20 so as to extend in the long-side direction of the cores 22.

Description

Polymer membrane for generating fine water particles

[0001] The present invention relates to a polymer membrane for generating fine water particles.

[0002] Conventionally, techniques for generating fine water particles have been proposed for use in cosmetics, medicine, etc. As an example of such a technique, for example, Patent Documents 1 and 2 listed below propose a technique for generating fine water particles using particles with a core-shell structure formed from poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonic acid).

[0003] Patent No. 7091692 Patent No. 7196923

[0004] In the techniques of Patent Documents 1 and 2, the core-shell structured particles are generally spherical, and water particles flow through channels formed between the core-shell structures to generate fine water particles. However, when the core-shell structured particles are generally spherical, the channels formed between the core-shell structured particles curve significantly along the outer periphery of the spherical particles, resulting in a problem of a small amount of generated fine water particles.

[0005] The present invention has been made to solve the above-mentioned problems in the conventional technology, and aims to reduce the curvature of the flow paths formed between multiple core-shell structured particles, thereby ensuring the amount of fine water particles generated.

[0006] In order to achieve the above object, one aspect of the present invention is a polymer membrane for generating fine water droplets, which comprises a plurality of particles with a core-shell structure, each having a rod-shaped core containing poly(3,4-ethylenedioxythiophene) and a shell containing poly(styrenesulfonic acid) covering the core, and a flow path formed between the plurality of particles so as to extend in the direction of the long side of the core.

[0007] According to the polymer membrane for generating fine water particles having the above-described configuration, rod-shaped cores are used as the cores of the core-shell structured particles, and the flow paths formed between the particles are formed so as to extend in the direction of the long sides of the rod-shaped cores. This reduces the curvature of the flow paths formed between the core-shell structured particles, making it possible to ensure the amount of fine water particles generated.

[0008] FIG. 2 is a schematic diagram showing a polymer membrane for generating fine water droplets according to an embodiment. FIG. 3 is a schematic diagram showing particles with a core-shell structure that constitute the polymer membrane for generating fine water droplets of FIG. 1. FIG. 4 is a graph in which the relationship between the scattering intensity and the scattering vector of Example Sample 1 is plotted on a double logarithm. FIG. 5 is a graph in which the relationship between the scattering intensity and the scattering vector of Example Sample 1 is plotted on a double logarithm. FIG. 6 is a graph in which the relationship between the scattering intensity and the scattering vector of Example Sample 1 is plotted on a double logarithm. FIG. 7 is a graph in which the relationship between the scattering intensity and the scattering vector of Example Sample 1 is plotted on a double logarithm. FIG. 8 is a graph in which the relationship between the scattering intensity and the scattering vector of Example Sample 2 is plotted on a double logarithm. FIG. 9 is a graph in which the relationship between the scattering intensity and the scattering vector of Example Sample 2 is plotted on a double logarithm. 17 is a graph showing a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Comparative Sample 1. FIG. 18 is a graph showing a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Comparative Sample 2. FIG. 19 is a graph showing a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Comparative Sample 2. FIG. 19 is a graph showing a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Comparative Sample 2. FIG. 19 is a graph showing the slope of the Guinier plots of FIGS. 3 to 17 for each sample. FIG. 19 is a schematic diagram showing a specific shape including dimensions of Example Sample 1. FIG. 19 is a schematic diagram showing a specific shape including dimensions of Example Sample 2. FIG. 19 is a schematic diagram showing a specific shape including dimensions of Comparative Sample 1. FIG. 19 is a schematic diagram showing a polymer film for generating fine water droplets formed from PEDOT / PSS particles containing spherical PEDOT. FIG. 20 is a graph showing the moisture absorption rate of Example Sample 1, Example Sample 2, and Comparative Sample 1. FIG. 21 is a graph showing a small-angle X-ray scattering profile. FIG. 22 is a graph showing a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 3.1 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 3. FIG. 2 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 3. FIG. 3 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 3. FIG. 4 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 4. FIG. 5 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 4. FIG. 6 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 4. FIG. 7 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 5. FIG. 8 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 5. FIG. 9 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 5. FIG. 10 is a double logarithmic plot of the relationship between the scattering intensity and the scattering vector of Example Sample 6. 44. FIG. 44 is a graph showing the slope of the Guinier plots of FIGS. 3 to 13 and 25 to 44 for each sample. FIG. 44 is a graph showing the slope of the Guinier plots for each sample when measured under measurement conditions of room temperature and low humidity, for each PEDOT ratio of the sample. FIG. 44 is a graph showing the slope of the Guinier plot for each sample when measured under measurement conditions of room temperature and high humidity, for each PEDOT ratio of the sample. 1 is a graph showing the slope of a Guinier plot for each PEDOT ratio of a sample when measured under high temperature and low humidity conditions.1 is a graph showing the slope of a Guinier plot for each PEDOT ratio of a sample when measured under high-temperature and high-humidity measurement conditions. It is also a diagram showing the moisture absorption rate of each of Example Sample 1, Example Sample 2, Comparative Example Sample 1, and Comparative Example Sample 3.

[0009] Hereinafter, the polymer membrane for generating fine water particles according to the present invention will be described in detail with reference to the drawings, particularly an embodiment embodied as a polymer membrane 10 for generating fine water particles that generates fine water particles (hereinafter referred to as fine water particles) with a particle size of several nanometers.

[0010] As shown in Fig. 1, the polymer membrane 10 for generating fine water droplets is formed in a sheet shape and is in close contact with a thin plate-shaped substrate 12. The substrate 12 is a conductive metal foil made of, for example, stainless steel, a stainless metal, selected from conductive materials such as stainless steel or copper-based metals, carbon materials (carbon paper, graphite, etc.), conductive ceramic materials (e.g., ITO, etc.), and conductive resin materials (e.g., metal-deposited films, nanosilver coatings, CNT coatings, etc.). The substrate 12 generates heat when electricity is applied.

[0011] The polymer film 10 for generating fine water droplets is formed by dispersing particles 20 having a core-shell structure in a solvent, applying the dispersion containing the particles 20 to the outer surface of a substrate 12, and then drying. That is, the polymer film 10 for generating fine water droplets is manufactured by a manufacturing method that includes a coating step in which the dispersion containing the particles 20 is applied to a conductive substrate 12, and a drying step in which the particles 20 applied to the substrate 12 are dried after the coating step. By this manufacturing method, as conceptually shown in FIG. 1 , a plurality of particles 20 are stacked in multiple layers in a close-packed structure with a certain degree of regularity, thereby forming a sheet shape (film shape). The solvent for the dispersion is, for example, water.

[0012] The particles 20 transition from a release state to an adsorption state as the temperature of the fine water particle generating polymer film 10 decreases toward room temperature when the substrate 12 is in a non-energized state, and transition from the adsorption state to a release state as the temperature of the fine water particle generating polymer film 10 increases from room temperature when the substrate 12 is in a power-on state. The particles 20 in this embodiment have a particle size set to approximately 1 nanometer to 500 nanometers. As a result, multiple particles 20 are closely packed and stacked on the outer surface of the substrate 12 to form the fine water particle generating polymer film 10. The fine water particle generating polymer film 10 is formed so that the thickness (film thickness) of the multiple particles 20 stacked on the outer surface of the substrate 12 is 1 to 30 μm. The particles 20 in this embodiment are formed from PEDOT / PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)).

[0013] As shown in FIG. 2, the particle 20 is composed of a core 22 and a shell 24. The core 22 of the particle 20 is crystalline and forms the skeleton of the particle, and is made of poly(3,4-ethylenedioxythiophene), i.e., PEDOT. The shell 24 of the particle 20 is amorphous and is made of poly(styrenesulfonic acid), i.e., PSS, which is a polymer material having sulfonic acid groups (—SO3H) 24a capable of hydrogen bonding, and covers the core 22. In other words, the shape of the particle 20 changes depending on the shape of the core 22. For this reason, the shape of the particle 20 with a core-shell structure can be considered to be a spheroid depending on the shape of the core 22.

[0014] In this structure, when the substrate 12 is not energized, the polymer film 10 for generating fine water particles increases the amount of water adsorbed by the shells 24 of the particles 20 over time, and stabilizes at a saturated moisture absorption rate. On the other hand, when the substrate 12 is energized and the temperature of the particles 20 increases, the polymer film 10 for generating fine water particles releases the moisture adsorbed in the shells 24 of the particles 20 in the form of water particles.

[0015] In the polymer film 10 for generating fine water droplets, which is configured to include particles 20 with this core-shell structure, the speed at which moisture in the air is adsorbed in the adsorption state and the speed at which moisture is released into the air in the release state are faster than those of general moisture absorbents such as silica gel. Also, in the polymer film 10 for generating fine water droplets, which is configured to include particles 20 with a core-shell structure, the size of the water droplets of moisture released in the release state is distributed in an extremely small particle size distribution range of about 1 nanometer to 40 nanometers, more specifically, 1 nanometer to 10 nanometers.

[0016] Specifically, we will first explain the speed of moisture adsorption and release. The polymer film 10 for generating fine water droplets has particles 20 made of PEDOT / PSS laminated on a substrate 12. In this case, the shells 24 of the particles 20 are laminated in an aligned state in the polymer film 10 for generating fine water droplets, as shown in FIG. 1. Furthermore, as shown in FIG. 2, the PSS constituting the shell 24 of the particle 20 has numerous sulfonic acid groups (—SO3H) 24a, which are polar functional groups capable of forming hydrogen bonds, on the outer surface of the shell 24. Therefore, moisture contained in the air is adsorbed by hydrogen bonding to the sulfonic acid groups 24a in contact with the air.

[0017] In this case, if the moisture content on the surface of the fine water particle generating polymer membrane 10 is high and the moisture content inside the fine water particle generating polymer membrane 10 is low, the shells 24 of the particles 20 attempt to move the adsorbed moisture from the surface of the fine water particle generating polymer membrane 10 toward the interior of the fine water particle generating polymer membrane 10 using the moisture concentration difference as a driving force. Furthermore, as indicated by the thick arrows in FIG. 1 , nanometer-sized flow paths 30 (hereinafter referred to as "nanochannels 30") are formed between the stacked particles 20 inside the fine water particle generating polymer membrane 10. These nanochannels 30 contain a large number of sulfonic acid groups 24a, and moisture adsorbed on the surface of the fine water particle generating polymer membrane 10 moves rapidly through the sulfonic acid groups 24a present in the nanochannels 30 into the interior of the fine water particle generating polymer membrane 10. In other words, moisture adsorbed on the surface of the fine water particle generating polymer membrane 10 moves through the nanochannels 30 into the interior of the fine water particle generating polymer membrane 10. As a result, the moisture adsorbed on the surface of the polymer membrane 10 for generating fine water particles moves at high speed into the interior of the polymer membrane 10 for generating fine water particles due to the difference in moisture concentration, and a large amount of moisture can be adsorbed and retained from the air at a high speed.

[0018] Furthermore, since moisture moves using the difference in moisture concentration as a driving force, when the moisture content inside the fine-water-particle-generating polymer membrane 10 is high and the moisture content on the surface of the fine-water-particle-generating polymer membrane 10 is low, i.e., when the air is dry, moisture held inside moves at high speed from the inside of the fine-water-particle-generating polymer membrane 10 toward the surface of the fine-water-particle-generating polymer membrane 10 by traveling along the sulfonic acid groups 24a present in the nanochannels 30, in contrast to the adsorption described above. That is, moisture held inside the fine-water-particle-generating polymer membrane 10 moves to the surface of the fine-water-particle-generating polymer membrane 10 through the nanochannels 30. As a result, moisture held inside the fine-water-particle-generating polymer membrane 10 moves at high speed to the surface of the fine-water-particle-generating polymer membrane 10 due to the difference in moisture concentration, and the fine-water-particle-generating polymer membrane 10 can release a large amount of moisture into the air at a high speed. Furthermore, even when the humidity of the outside air is high, by passing electricity through the substrate 12, the temperature of the polymer film 10 for generating fine water particles can be raised, and the polymer film 10 for generating fine water particles can release a large amount of moisture into the air at a high speed.

[0019] Next, we will explain why the size of the water particles released from the polymer membrane 10 for generating fine water particles is small in the release state. As described above, the particles 20 having a core-shell structure are PEDOT / PSS, with PEDOT in the core and PSS in the shell 24. The PSS has sulfonic acid groups 24a, which are hydrophilic groups, and many of these groups are distributed on the outer surface and inside the shell 24. Because the polymer membrane 10 for generating fine water particles is formed by stacking the particles 20 having a core-shell structure, nanochannels 30 with a flow path width of several nanometers exist between adjacent particles 20, and many sulfonic acid groups 24a are distributed inside the nanochannels 30.

[0020] Therefore, inside the nanochannel 30, there are many water clusters of several nanometers that are further hydrated with respect to the water molecules bonded to the sulfonic acid groups 24a.

[0021] The reason why water particles of a few nanometers in size are released during moisture release is that when the substrate 12 is energized, the temperature of the polymer film 10 for generating fine water particles rises and thermal energy is supplied to the water particles. This increases the mobility of the water particles in the polymer film 10 for generating fine water particles, causing water clusters present in the nanochannels 30 to fly out from the numerous nozzle holes present on the surface of the polymer film 10 for generating fine water particles that correspond to the nanochannels 30.

[0022] The reason why the water particles (moisture) emitted from the fine water particle generating polymer membrane 10 have a small water particle diameter is thought to be due to a characteristic process in which multiple water molecules gather to form the water particles. For example, if a substance that can serve as a nucleus for water particles, such as ions, is present immediately after the water molecules are emitted from the nozzle, the water molecules gather around the ions, forming a relatively large water particle diameter. However, when the fine water particle generating polymer membrane 10 is used, there is no source of the substance that can serve as a nucleus for water particles, such as ions. Therefore, it is reasonable to think that in the fine water particle generating polymer membrane 10, the water molecules are less likely to gather even after the water molecules present in the nanochannels 30 are ejected from the surface of the fine water particle generating polymer membrane 10 by thermal energy, and that the water particle diameter can be maintained relatively small.

[0023] In this way, in the fine water particle generating polymer membrane 10, when the substrate 12 is in a non-conductive state and the temperature of the fine water particle generating polymer membrane 10 decreases, the moisture adsorbed on the surface of the fine water particle generating polymer membrane 10 moves through the nanochannels 30 into the interior of the fine water particle generating polymer membrane 10. This allows the moisture adsorbed on the surface of the fine water particle generating polymer membrane 10 to be retained inside the fine water particle generating polymer membrane 10. On the other hand, in the fine water particle generating polymer membrane 10, when the substrate 12 is in a conductive state and the temperature of the fine water particle generating polymer membrane 10 increases, the moisture retained inside the fine water particle generating polymer membrane 10 moves through the nanochannels 30 to the surface of the fine water particle generating polymer membrane 10. This allows the moisture retained inside the fine water particle generating polymer membrane 10 to be released into the air as fine particles on the surface of the fine water particle generating polymer membrane 10.

[0024] In this way, in the polymer membrane 10 for generating fine water particles, moisture flows between the surface of the polymer membrane 10 for generating fine water particles and the interior of the polymer membrane 10 for generating fine water particles through the nanochannels 30. Therefore, in order to ensure the flow of moisture in the nanochannels 30, the core 22 of the PEDOT / PSS particles 20 with a core-shell structure that separates the nanochannels 30 is made rod-shaped.

[0025] Specifically, in the PEDOT / PSS particles 20, the weight ratio of ethylenedioxythiophene (EDOT), a PEDOT monomer, to PSS is set to be greater than 1:3 and equal to or less than 1:8. Furthermore, the weight ratio of ethylenedioxythiophene (EDOT), a PEDOT monomer, to PSS is set to be greater than 1:3 and equal to or less than 1:7. By setting the weight ratio of EDOT to PSS in this manner, the PEDOT, which is the core 22, in the PEDOT / PSS particles 20 with a core-shell structure, has a rod-like shape.

[0026] Specifically, small-angle X-ray scattering measurements were performed on Example Samples 1 to 6 and Comparative Samples 1 to 3 to create Guinier plots and evaluate the shape of the core 22.

[0027] For example sample 1, a polymer film for generating fine water particles was formed on a silicon wafer using PEDOT / PSS particles 20 in which the weight ratio of EDOT to PSS was 1:4. For example sample 2, a polymer film for generating fine water particles was formed on a silicon wafer using PEDOT / PSS particles 20 in which the weight ratio of EDOT to PSS was 1:6. For example sample 3, a polymer film for generating fine water particles was formed on a PET film using PEDOT / PSS particles 20 in which the weight ratio of EDOT to PSS was 1:4. For example sample 4, a polymer film for generating fine water particles was formed on a PET film using PEDOT / PSS particles 20 in which the weight ratio of EDOT to PSS was 1:5. For example sample 5, a polymer film for generating fine water particles was formed on a PET film using PEDOT / PSS particles 20 in which the weight ratio of EDOT to PSS was 1:7. As Example Sample 6, a polymer membrane for generating fine water particles was formed on a PET film using PEDOT / PSS particles 20 with a weight ratio of EDOT to PSS of 1:8. As Comparative Example Sample 1, a polymer membrane for generating fine water particles was formed on a silicon wafer using PEDOT / PSS particles 20 with a weight ratio of 1:2.5. As Comparative Example Sample 2, a commercially available Nafion (registered trademark) (NR211 (25 μm thick) solution-cast membrane) was used. As Comparative Example Sample 3, a polymer membrane for generating fine water particles was formed on a PET film using PEDOT / PSS particles 20 with a weight ratio of 1:3.

[0028] Scattered radiation measurements for each sample were performed at beamline BL8S3 of the Aichi Synchrotron Light Center, a public interest incorporated foundation for science and technology, under conditions of an X-ray energy of 13.9 keV (wavelength of 0.92 Å) and a camera length of 4 m, using a two-dimensional semiconductor detector (PILATUS 2M) and an automatic reading imaging plate detector (R-AXIS IV) manufactured by DECTRIS, Inc. Scattered radiation measurements for each of Example Samples 1 and 2 and Comparative Samples 1 and 2 were performed using a two-dimensional semiconductor detector (PILATUS 2M), and scattered radiation measurements for each of Example Samples 3 to 6 and Comparative Sample 3 were performed using an automatic reading imaging plate detector (R-AXIS IV). Furthermore, for Example Samples 1 and 2 and Comparative Samples 1 and 2, scattered radiation measurements were performed under the following measurement conditions: temperature 30°C and humidity 11%, temperature 30°C and humidity 74%, temperature 70°C and humidity 11%, and temperature 70°C and humidity 74%, and for Example Samples 3 to 6 and Comparative Sample 3, scattered radiation measurements were performed under the following measurement conditions: temperature 25°C and humidity 11%, temperature 25°C and humidity 63%, temperature 68°C and humidity 12%, and temperature 68°C and humidity 56%. Then, the small-angle X-ray scattering profile shown in FIG. 24 was created. The measurement conditions of 30°C temperature and 11% humidity and 25°C temperature and 11% humidity are referred to as "room temperature and low humidity," while the measurement conditions of 30°C temperature and 74% humidity and 25°C temperature and 63% humidity are referred to as "room temperature and high humidity," while the measurement conditions of 70°C temperature and 11% humidity and 68°C temperature and 12% humidity are referred to as "high temperature and low humidity," and the measurement conditions of 70°C temperature and 74% humidity and 68°C temperature and 56% humidity are referred to as "high temperature and high humidity." The relationship between the scattering intensity and scattering vector in the shape-dependent region between the Guinier region and the Polode region (the region corresponding to a PEDOT:PSS particle diameter of 20 to 40 nm) was then plotted logarithmically from the obtained scattering diffraction data, and the slope of the shape-dependent region was determined. Graphs plotting the relationship between scattering intensity and scattering vector are shown in Figures 3 to 17 and 25 to 44.The slopes of the shape-dependent regions (slope in the scattering intensity range of 0.15 to 0.3) of Example Samples 1 and 2 and Comparative Samples 1 and 2, that is, the slopes of the Guinier plots, are shown in FIG. 18 , and the slopes of the shape-dependent regions (slope in the scattering intensity range of 0.15 to 0.3) of Example Samples 1 to 6 and Comparative Samples 1 and 3, that is, the slopes of the Guinier plots, are shown in FIG. 45 .

[0029] 18 , for Example Sample 1, the slope of the Guinier plot under each of the four measurement conditions was −1.164 to −0.918, and for Example Sample 2, the slope of the Guinier plot under each of the three measurement conditions was −1.262 to −0.518. Note that for Example Sample 2, the slope of the Guinier plot could not be calculated under the measurement conditions of a temperature of 70°C and a humidity of 11%. Considering that the slope of the Guinier plot could be calculated under three of the four measurement conditions for Example Sample 2, but could not be calculated under only one of the four measurement conditions, it can be inferred that there was not a problem with Example Sample 2, but rather a problem with the measurement itself, such as an inability to properly perform scattered radiation measurement under the measurement conditions of a temperature of 70°C and a humidity of 11%. Furthermore, for Comparative Sample 1, the slope of the Guinier plot under each of the four measurement conditions was −3.265 to −2.276, and for Comparative Sample 2, the slope of the Guinier plot under each of the four measurement conditions was −3.381 to −1.864.

[0030] Here, the slope of the Guinier plot indicates the shape of the object to be measured, and indicates the shape of PEDOT, which is the core 22 of the particle 20 to be measured. A slope of the Guinier plot of approximately -1 indicates a rod shape. Therefore, the shape of PEDOT in Example Sample 1 is rod-shaped under each of the four measurement conditions. Furthermore, the shape of PEDOT in Example Sample 2 is rod-shaped under each of the three measurement conditions. As described above, it can be inferred that there was not a problem with Example Sample 2, but rather a problem with the measurement itself, such as the inability to properly perform scattered radiation measurement under the measurement conditions of Example Sample 2, which was a temperature of 70°C and a humidity of 11%, and therefore it can be said that the shapes of PEDOT in Example Samples 1 and 2 were rod-shaped.

[0031] Furthermore, a slope of approximately -2 in the Guinier plot indicates a disk shape or a Gaussian coil shape, and a slope of approximately -4 indicates a spherical shape. Therefore, the shape of PEDOT in Comparative Sample 1 was disk shape or a Gaussian coil shape under each of the three measurement conditions, and spherical under one measurement condition. Furthermore, the shape of PEDOT in Comparative Sample 2 was disk shape or a Gaussian coil shape under each of the three measurement conditions, and spherical under one measurement condition. Comparative Sample 2 is a polymer membrane formed from commercially available Nafion, and it is known that the actual shape of the internal structure of Nafion is close to a disk shape, a Gaussian coil shape, or a sphere. Therefore, the shape indicated by the slope of the Guinier plot in Comparative Sample 2 is the same as the actual shape of Comparative Sample 2. From this, it can be said that the shape indicated by the slope of the Guinier plot indicates the actual shape of each sample.

[0032] Furthermore, by using the scattered diffraction data used in calculating the slope of the Guinier plot, it is possible to calculate the specific shape of PEDOT, including its dimensions. Specifically, a bar shape with the dimensions shown in FIG. 19 is calculated as the specific shape of Example Sample 1 at a temperature of 30°C and a humidity of 74%. A bar shape with the dimensions shown in FIG. 20 is calculated as the specific shape of Example Sample 2 at a temperature of 30°C and a humidity of 74%. Meanwhile, a disk shape with the dimensions shown in FIG. 21 is calculated as the specific shape of Comparative Example Sample 1 at a temperature of 30°C and a humidity of 74%. From this, it can be seen that when the weight ratio of EDOT to PSS is 1:2.5, the shape of PEDOT becomes a disk, whereas when the weight ratio of EDOT to PSS is 1:4 or 1:6, the shape of PEDOT becomes a thin, elongated rod.

[0033] Thus, the PEDOT has a rod-like shape in Example Sample 1 and Example Sample 2, but not in Comparative Example Sample 1 and Comparative Example Sample 2. For this reason, the PEDOT has a rod-like shape when the weight ratio of ethylenedioxythiophene (EDOT), a PEDOT monomer, to PSS is set to 1:4 (Example Sample 1) or 1:6 (Example Sample 2). In other words, taking into account errors and the like, the PEDOT has a rod-like shape when the weight ratio of EDOT to PSS is set to more than 1:3.

[0034] The minimum value of the Guinier plot slope for Comparative Sample 2 (a polymer membrane formed from commercially available Nafion) is −1.864, and the actual shape of Comparative Sample 2 is a disk or Gaussian coil shape. A Guinier plot slope of approximately −1 indicates a rod shape. Therefore, a Guinier plot slope greater than −1.8 indicates that the PEDOT shape is rod-shaped. In other words, by increasing the weight ratio of EDOT to PSS to more than 1:3, the Guinier plot slope becomes greater than −1.8, and the PEDOT shape becomes rod-shaped.

[0035] In this way, by making the shape of the PEDOT core 22 rod-shaped, the rod-shaped PEDOT core 22 is covered with the PSS shell 24, and the particle 20 becomes a spheroid, as shown in Fig. 2. In the polymer film 10 for generating fine water droplets, which is formed by closely stacking a plurality of such spheroid particles 20, the plurality of particles 20 are arranged to extend in the vertical direction, and nanochannels 30 are formed between the plurality of particles 20, as shown in Fig. 1.

[0036] When the PEDOT / PSS particles 20 are dispersed in water, a solution in which the PEDOT / PSS is dispersed as colloids (hereinafter referred to as a "PEDOT / PSS dispersion") is formed. When the PEDOT / PSS dispersion is applied to a metal plate such as stainless steel and dried to form a film, the colloids dispersed in the water aggregate as the water evaporates, forming a higher-order structure in which a crystalline PEDOT core 22 is covered by a hydrophilic PSS shell 24. The colloids dispersed in the water undergo rotational and translational movements, but as the water evaporates, they are thought to spontaneously orient in a predetermined direction due to the anisotropy of the colloidal shape. Therefore, in the polymer film 10 for generating fine water droplets, multiple particles 20 are arranged so as to extend vertically, as shown in FIG. 1.

[0037] When a plurality of particles 20 are arranged to extend in the vertical direction in this manner, the nanochannels 30 formed between the plurality of particles 20 are formed in a generally linear shape extending in the vertical direction, i.e., in the direction of the long sides of the spheroidal particles 20. Furthermore, the PEDOT that forms the core 22 of the particle 20 is rod-shaped and is encapsulated within the particle 20 along the direction of the long sides of the particle 20. Therefore, the nanochannels 30 are formed in a generally linear shape extending in the direction of the long sides of the rod-shaped PEDOT that forms the core 22. Note that the linear shape here does not only refer to a straight line, but also includes a shape in which straight lines extend in the same direction in a zigzag pattern. Furthermore, a shape in which a line is slightly curved and extends in the same direction is also included in the linear shape.

[0038] In this way, nanochannels 30 extending in the long side direction of the rod-shaped PEDOT, i.e., in the long side direction of the spheroid particles 20, are formed between the spheroid particles 20 containing rod-shaped PEDOT as the core 22, thereby making it possible to ensure the flow of moisture in the nanochannels 30.

[0039] Specifically, as shown in FIG. 22 , for example, a particle 52 with a core-shell structure containing spherical PEDOT as a core 50 becomes spherical when the spherical PEDOT is coated with PSS as a shell 54. Then, a polymer film 60 for generating fine water particles is formed on a substrate 12 using the core-shell PEDOT / PSS particles 52. In this polymer film 60 for generating fine water particles, nanochannels 70 are formed between the multiple spherical particles 52, and water molecules flow through the nanochannels 70. In the nanochannels 70, water flows along the outer periphery of the spherical particles, so the amount of water flowing per unit time is small. In other words, in the nanochannels 70, water flows through a highly curved flow path, so the amount of water flowing per unit time is small.

[0040] On the other hand, as shown in FIG. 1 , in the polymer film 10 for generating fine water particles, nanochannels 30 are formed between spheroidal particles 20 containing rod-shaped PEDOT as cores 22, extending in the direction of the long sides of the rod-shaped PEDOT, i.e., in the direction of the long sides of the spheroidal particles 20. Therefore, the nanochannels 30 of the polymer film 10 for generating fine water particles have a shape that extends more linearly than the nanochannels 70 of the polymer film 60 for generating fine water particles. In other words, the nanochannels 30 of the polymer film 10 for generating fine water particles have a shape that is less curved than the nanochannels 70 of the polymer film 60 for generating fine water particles. Therefore, in the nanochannels 30, water flows through a flow path with less curvature, making it possible to increase the amount of water flowing per unit time. In other words, by increasing the amount of water flowing through the nanochannels 30 per unit time, it becomes possible to increase the rate at which water is absorbed by the polymer film 10 for generating fine water particles. The moisture absorption rate of the polymer membrane 10 for generating fine water particles will be described below.

[0041] Each test piece of Example Sample 1, Example Sample 2, and Comparative Sample 1 was exposed to an environment of constant temperature and constant humidity for a certain period of time, and the weight of the test piece was measured using a differential thermal-thermogravimetric simultaneous analyzer (TG-DTA SE model, manufactured by NETZSCH). The moisture absorption rate was calculated by measuring the weight of each test piece using a differential thermal-thermogravimetric simultaneous analyzer (TG-DTA SE model, manufactured by NETZSCH). Specifically, each test piece of Example Sample 1, Example Sample 2, and Comparative Sample 1 was left in an absolutely dry state at 70°C with nitrogen introduced until the weight of each test piece stabilized. Then, the weight of the test piece in the absolutely dry state was set as the zero point, and the test piece was controlled to have a temperature of 30°C and a humidity of 10%. The rate at which the test piece absorbed moisture, that is, the ratio of the increase in weight of the test piece to the time required for the test piece to reach a temperature of 30°C and a humidity of 10%, was calculated. The moisture absorption rate (wt% / min) was then calculated by dividing the rate at which the test piece absorbed moisture by the weight of the test piece in the absolutely dry state. In addition, the moisture absorption rate (wt% / min) of the test piece is calculated using the above procedure for every 10% humidity in the humidity range of 20% to 60% at a temperature of 30°C.

[0042] The moisture absorption rates calculated in this manner for each humidity level of Example Sample 1, Example Sample 2, and Comparative Example Sample 1 are shown in Figure 23. As can be seen from Figure 23, the moisture absorption rates of Example Sample 1 and Example Sample 2 are clearly faster than the moisture absorption rate of Comparative Example Sample 1. This clearly shows that by making the PEDOT core 22 rod-shaped, the moisture absorption rate of the polymer film 10 for generating fine water particles becomes approximately 2.6 to 4.6 times faster.

[0043] 45, the gradient of the Guinier plot for each of the four measurement conditions for Example Sample 1 is −1.164 to −0.918, and the gradient of the Guinier plot for each of the three measurement conditions for Example Sample 2 is −1.262 to −0.518. Note that the calculation results for Example Samples 1 and 2 in FIG. 45 are the same as the calculation results for Example Samples 1 and 2 in FIG. Furthermore, for Example Sample 3, the slope of the Guinier plot under each of the four measurement conditions was −2.159 to −1.197, for Example Sample 4, the slope of the Guinier plot under each of the four measurement conditions was −1.441 to −1.065, for Example Sample 5, the slope of the Guinier plot under each of the four measurement conditions was −1.13 to −0.957, and for Example Sample 6, the slope of the Guinier plot under each of the four measurement conditions was −2.053 to −0.952. For Comparative Example Sample 1, the slope of the Guinier plot under each of the four measurement conditions was −3.265 to −2.276, and for Comparative Example Sample 2, the slope of the Guinier plot under each of the four measurement conditions was −3.381 to −1.864. The calculation results for comparative samples 1 and 2 in Fig. 45 are the same as the calculation results for example samples 1 and 2 in Fig. 18. For comparative sample 3, the slopes of the Guinier plots under each of the four measurement conditions are −3.278 to −1.736.

[0044] The relationship between the PEDOT ratio and the slope of the Guinier plot for Example Samples 1 to 6 and Comparative Examples 1 and 3 at room temperature and low humidity (30°C 11% or 25°C 11%) is plotted in Figure 46, the relationship between the PEDOT ratio and the slope of the Guinier plot for Example Samples 1 to 6 and Comparative Examples 1 and 3 at room temperature and high humidity (30°C 74% or 25°C 63%) is plotted in Figure 47, the relationship between the PEDOT ratio and the slope of the Guinier plot for Example Samples 1 to 6 and Comparative Examples 1 and 3 at high temperature and low humidity (70°C 11% or 68°C 12%) is plotted in Figure 48, and the relationship between the PEDOT ratio and the slope of the Guinier plot for Example Samples 1 to 6 and Comparative Examples 1 and 3 at high temperature and high humidity (70°C 74% or 68°C 56%) is plotted in Figure 49.

[0045] The PEDOT ratio of Comparative Sample 1 (PEDOT / PSS = 1 / 2.5) was 0.4, the PEDOT ratio of Comparative Sample 3 (PEDOT / PSS = 1 / 3) was approximately 0.33, the PEDOT ratio of Example Sample 1 (PEDOT / PSS = 1 / 4) was 0.25, the PEDOT ratio of Example Sample 2 (PEDOT / PSS = 1 / 6) was approximately 0.17, the PEDOT ratio of Example Sample 3 (PEDOT / PSS = 1 / 4) was 0.25, the PEDOT ratio of Example Sample 4 (PEDOT / PSS = 1 / 5) was 0.2, the PEDOT ratio of Example Sample 5 (PEDOT / PSS = 1 / 7) was approximately 0.14, and the PEDOT ratio of Example Sample 6 (PEDOT / PSS = 1 / 8) was 0.125.

[0046] Under measurement conditions of room temperature and low humidity (30°C, 11%, or 25°C, 11%), the slopes of the Guinier plots for Example Samples 1 to 6 (PEDOT ratios of 0.125 to 0.25) were all greater than −1.8, as shown in Figure 46, while the slopes of the Guinier plots for Comparative Samples 1 and 3 (PEDOT ratios of 0.33 to 0.4) were all less than −1.8. Under measurement conditions of room temperature and high humidity (30°C, 74%, or 25°C, 63%), the slopes of the Guinier plots for Example Samples 1 to 6 (PEDOT ratios of 0.125 to 0.25) were all greater than −1.8, while the slope of the Guinier plot for Comparative Sample 1 (PEDOT ratio of 0.4) was less than −1.8, as shown in Figure 47. The slope of the Guinier plot for Comparative Sample 3 (PEDOT ratio of 0.33) was slightly greater than −1.8, but was approximately −1.8. Furthermore, under the measurement conditions of high temperature and low humidity (70°C 11% or 68°C 12%), the slopes of the Guinier plots for Example Samples 1, 2, 4, and 5 (PEDOT ratios of 0.143 to 0.25) were all greater than −1.8, while the slopes of the Guinier plots for Comparative Example Samples 1 and 3 (PEDOT ratios of 0.33 to 0.4) were all significantly smaller than −1.8, as shown in Figure 48. Note that the slopes of the Guinier plots for Example Samples 3 and 6 (PEDOT ratios of 0.25 and 0.125) were smaller than −1.8 but close to −1.8, within the error range of −1.8. Furthermore, under the measurement conditions of high temperature and high humidity (70°C, 74% or 68°C, 56%), as shown in Figure 49, the slopes of the Guinier plots for Example Samples 1 to 6 (PEDOT ratios of 0.125 to 0.25) were all greater than -1.8, while the slopes of the Guinier plots for Comparative Example Samples 1 and 3 (PEDOT ratios of 0.33 to 0.4) were all less than -1.8.

[0047] Taking this into consideration, the slopes of the Guinier plots for Example Samples 1 to 6 (PEDOT ratios of 0.125 to 0.25) are generally greater than −1.8, while the slopes of the Guinier plots for Comparative Samples 1 and 3 (PEDOT ratios of 0.33 to 0.4) are generally less than −1.8. In other words, by setting the weight ratio of EDOT (a PEDOT monomer) to PSS to be greater than 1:3 and equal to or less than 1:8, the slope of the Guinier plot becomes greater than −1.8. Strictly speaking, by setting the weight ratio of EDOT (a PEDOT monomer) to PSS to be greater than 1:3 and equal to or less than 1:7, the slope of the Guinier plot becomes greater than −1.8.

[0048] Furthermore, by increasing the weight ratio of EDOT and PSS, which are PEDOT monomers, to greater than 1:3, the slope of the Guinier plot becomes greater than −1.8, and to clarify that the PEDOT core 22 has a rod-like shape, the moisture absorption rate of Comparative Sample 3 was measured using the same method as described above for Example Sample 1, Example Sample 2, and Comparative Sample 1. The moisture absorption rate of Comparative Sample 3 measured in this manner is shown in FIG. 50 along with the moisture absorption rates of Example Sample 1, Example Sample 2, and Comparative Sample 1. The moisture absorption rates of Example Sample 1, Example Sample 2, and Comparative Sample 1 are the same as those shown in FIG. 23 . As can be seen from FIG. 50 , the moisture absorption rates of Example Sample 1 and Example Sample 2 are approximately 1.7 to 3.1 times faster than the moisture absorption rate of Comparative Sample 3. Furthermore, the moisture absorption rate of Comparative Sample 3 is similar to that of Comparative Sample 1. From this, it can be seen that Comparative Sample 3 has the same shape as Comparative Sample 1, which is presumed to be a disk shape or a Gaussian coil shape, and by increasing the weight ratio of EDOT and PSS, which are PEDOT monomers, in Comparative Sample 3 from 1:3, it is possible to increase the moisture absorption rate as in Example Samples 1 and 2. In other words, by increasing the weight ratio of EDOT and PSS, which are PEDOT monomers, from 1:3, the PEDOT that is the core 22 becomes rod-shaped, and the slope of the Guinier plot becomes greater than −1.8.

[0049] As described above in detail, the polymer film 10 for generating fine water droplets according to this embodiment includes a plurality of particles 20 with a core-shell structure, each having a rod-shaped core 22 containing PEDOT and a shell 24 containing PSS covering the core 22, and nanochannels 30 formed between the particles 20 and extending along the long sides of the cores 22. This reduces the curvature of the nanochannels 30 through which water flows, thereby increasing the moisture absorption rate of the polymer film 10 for generating fine water droplets. In other words, increasing the moisture absorption rate of the polymer film 10 for generating fine water droplets enables the generation of a larger number of fine water droplets, thereby ensuring the amount of fine water droplets generated. Furthermore, the slope of the Guinier plot obtained from small-angle X-ray scattering of the cores 22 is greater than −1.8. This allows the PEDOT cores 22 to be rod-shaped, thereby reducing the curvature of the nanochannels 30. Furthermore, the particle 20 encapsulating the rod-shaped PEDOT core 22 is spheroidal, and the nanochannel 30 is formed to extend in the long side direction of the spheroidal particle 20. This reduces curvature of the nanochannel 30. Furthermore, the PEDOT / PSS particle 20 has a weight ratio of EDOT, which is a PEDOT monomer, to PSS set to greater than 1:3 and equal to or less than 1:8. Strictly speaking, the PEDOT / PSS particle 20 has a weight ratio of EDOT, which is a PEDOT monomer, to PSS set to greater than 1:3 and equal to or less than 1:7. This allows the PEDOT core 22 to be rod-shaped, thereby reducing curvature of the nanochannel 30. Furthermore, in this embodiment, the substrate 12 serves as a temperature regulator for the fine water particle generating polymer film 10, and repeatedly lowers and raises the temperature of the fine water particle generating polymer film 10, thereby repeatedly absorbing water and releasing fine water particles. In this case, the moisture absorption rate of the polymer membrane 10 for generating fine water particles increases, thereby increasing the number of times the polymer membrane 10 for generating water particles releases fine water particles within a certain period of time, allowing the release of fine water particles to be repeated at a high frequency.

[0050] The present invention is not limited to the above-described embodiment, and various improvements and modifications are possible without departing from the spirit and scope of the present invention. For example, in this embodiment, the fine water particle generating polymer membrane 10 is formed on a substrate 12, and adsorption and desorption of moisture occur depending on the state of electrical current passing through the substrate 12. Alternatively, the fine water particle generating polymer membrane 10 may adsorb and desorb moisture alone. In other words, the fine water particle generating polymer membrane 10 may adsorb moisture when the moisture content in the air is high, and desorb moisture when the moisture content in the air is low.

[0051] Furthermore, in this embodiment, PEDOT is recognized as being rod-shaped when the slope of the Guinier plot is greater than −1.8. However, considering that PEDOT is rod-shaped when the slope of the Guinier plot is around −1, and PEDOT is disk-shaped or Gaussian coil-shaped when the slope of the Guinier plot is around −2, PEDOT may also be recognized as being rod-shaped when the slope of the Guinier plot is greater than a predetermined value that is greater than or equal to −1.2 and less than −1.8.

[0052] 10... Polymer membrane for generating fine water particles, 20... Particle, 22... Core, 24... Shell, 30... Nanochannel (flow path)

Claims

1. A polymer membrane for generating fine water droplets, comprising: a plurality of particles with a core-shell structure, each having a rod-shaped core containing poly(3,4-ethylenedioxythiophene) and a shell containing poly(styrenesulfonic acid) covering the core; and flow paths formed between the plurality of particles so as to extend in the direction of the long sides of the core.

2. The polymer film for generating fine water droplets according to claim 1, wherein the gradient of a Guinier plot obtained from small-angle X-ray scattering of the core is greater than -1.

8.

3. The polymer membrane for generating fine water droplets according to claim 1, wherein the particles are spheroids, and the flow paths are formed so as to extend in the direction of the longer sides of the spheroids.

4. A polymer membrane for generating fine water particles according to any one of claims 1 to 3, wherein the particles are made of ethylenedioxythiophene, a monomer of poly(3,4-ethylenedioxythiophene), and poly(styrenesulfonic acid), in a weight ratio greater than 1:3 and not greater than 1:

8.

5. A polymer membrane for generating fine water particles as described in claim 4, wherein the particles are made of ethylenedioxythiophene, a monomer of poly(3,4-ethylenedioxythiophene), and poly(styrenesulfonic acid) in a weight ratio greater than 1:3 and less than 1:

7.

6. The polymer membrane for generating fine water droplets according to claim 1, wherein the flow path has a shape with minimal curvature, thereby increasing the rate of moisture absorption by the flow path.

7. A fine water particle generator comprising: a polymer membrane having a plurality of particles with a core-shell structure, each having a rod-shaped core containing poly(3,4-ethylenedioxythiophene) and a shell containing poly(styrenesulfonic acid) covering the core, and a flow path formed between the plurality of particles so as to extend in the direction of the long side of the core; and a temperature adjustment unit that causes the polymer membrane to absorb water by lowering the temperature of the polymer membrane, and releases fine water particles from the polymer membrane by raising the temperature of the polymer membrane.

8. The fine water particle generating device according to claim 7, wherein said temperature adjusting unit repeatedly lowers and raises the temperature of said polymer membrane, thereby repeatedly emitting fine water particles at a high frequency.

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