WO2011102467A1

WO2011102467A1 - Method for producing crystalline metal oxide structure

Info

Publication number: WO2011102467A1
Application number: PCT/JP2011/053518
Authority: WO
Inventors: 達也大久保; 敦下嶋; 彩絵菅原; 軍政王
Original assignee: 国立大学法人東京大学
Priority date: 2010-02-19
Filing date: 2011-02-18
Publication date: 2011-08-25
Also published as: JP5555925B2; JPWO2011102467A1

Abstract

Proposed is method for producing a crystalline metal oxide structure wherein crystalline metal oxide particles are arrayed in a controlled manner so that the application range of the crystalline metal oxide particles can be considerably broadened compared with the prior art. The pH value of a titania sol (14), wherein spherical titania nanoparticles (2) are dispersed, is adjusted to a preset pH level and a definite amount of a block copolymer is added to the titania sol. Then, the titania sol is heated at a preset heating temperature for a preset heating time. Thus, a crystalline metal oxide structure (1), wherein the titania nanoparticles (2), having been dispersed, are one-dimensionally arrayed and adjacent titania nanoparticles (2) are bonded together at such a strength as not to be dispersed even an external force is applied thereto, can be formed in the reaction solution. By arraying the titania nanoparticles (2), having been dispersed, in a controlled manner as described above, it becomes possible to employ these nanoparticles for various purposes compared with the conventional art. Thus, a crystalline metal oxide structure (1), whereby the application range of the titania nanoparticles (2) can be considerably broadened compared with the prior art, can be provided.

Description

Method for producing crystalline metal oxide structure

The present invention relates to a method for producing a structure (hereinafter referred to as a crystalline metal oxide structure) composed of particles composed of a crystalline metal oxide (hereinafter referred to as crystalline metal oxide particles). For example, it is suitable for manufacturing a crystalline metal oxide structure made of titania (titanium dioxide).

In general, titania has excellent properties such as UV absorption and adsorption, and is used in various fields such as pigments, paints, cosmetics, UV blocking materials, catalysts, catalyst carriers, and various electronic materials. ing. In recent years, a method for producing titania sol or the like in which such fine particles of titania (hereinafter referred to as titania nanoparticles) are dispersed in a solution has been considered (for example, see Patent Document 1).

JP-A 64-3020

However, at present, a method for controlling the arrangement of such crystalline metal oxide particles such as titania nanoparticles has not yet been established.

Therefore, the present invention has been made in consideration of the above points, and the crystalline metal oxide particles can be arranged and controlled to further expand the field of use of the crystalline metal oxide particles. It aims at proposing the manufacturing method of a structure.

In order to solve this problem, claim 1 of the present invention adjusts the pH of a solution containing crystalline metal oxide particles to a predetermined pH and dissolves a one-dimensional structure-forming substance having a one-dimensional structure-forming ability. A crystalline step in which the crystalline metal oxide particles are connected in a one-dimensional array by heating the reaction solution for a predetermined heating time at a predetermined heating temperature. And a generation step of generating an oxide structure.

Further, according to claim 2 of the present invention, the crystalline metal oxide particles are arranged one-dimensionally by adjusting the pH in the dissolving step and the heating temperature and the heating time in the generating step. Then, the adjacent crystalline metal oxide particles are connected with a predetermined strength.

The third aspect of the present invention is characterized in that, in the dissolving step, the crystalline metal oxide particles are titania nanoparticles, and the one-dimensional structure forming substance is a block copolymer.

According to a fourth aspect of the present invention, in the dissolution step, the crystalline metal oxide particles are nanoparticles having conductivity, and the one-dimensional structure forming substance is a block copolymer. It is.

Further, claim 5 of the present invention is characterized in that the nanoparticles include tin oxide.

According to the method for producing a crystalline metal oxide structure of claim 1 of the present invention, the arrangement of the crystalline metal oxide particles can be controlled, and thus the field of use of the crystalline metal oxide particles is further enhanced than before. Can expand.

It is a SEM image which shows the whole structure of the crystalline metal oxide structure by this invention. It is a flowchart which shows a titania nanoparticle production | generation process procedure. It is a flowchart which shows a crystalline metal oxide structure production | generation process procedure. It is the schematic where it uses for description of dialysis. It is the schematic which shows the chemical formula of F127. It is a flowchart which shows the verification procedure of a crystalline metal oxide structure. It is a graph which shows the XRD pattern of the crystalline metal oxide structure before and behind baking. It is a SEM image when titania sol which adjusted pH to 1.6, 3.38, 3.58, or 4.0 is used, respectively. It is a SEM image when the addition amount of F127 is adjusted to 0.1, 0.3, 0.5, 0.7, or 1.0. It is a SEM image when heating time is 1st, 2nd, 7th, or 14th. It is a SEM image when heating temperature is 80 degreeC, 100 degreeC, 120 degreeC, 150 degreeC, 175 degreeC, or 190 degreeC. It is a graph which shows the relationship between heating time and pH. It is a SEM image which shows the structure of the crystalline metal oxide structure in the tin oxide sol which adjusted pH to 7.0, 8.0, or 9.0. They are the TEM image which shows the structure of the crystalline metal oxide structure in the tin oxide sol which adjusted pH to 8.0, and an electron beam diffraction image.

1 Crystalline metal oxide structure 2 Titania nanoparticles (crystalline metal oxide particles)

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Overall Configuration of Crystalline Metal Oxide Structure FIG. 1 is an SEM (Scanning Electron Microscope) image obtained by photographing a crystalline metal oxide structure 1 according to the present invention with a scanning microscope. As shown in FIG. 1, each crystalline metal oxide structure 1 has a plurality of titania nanoparticles 2 arranged in a line in a straight line or a curved line and arranged in a ball chain shape (hereinafter referred to as a one-dimensional arrangement). ) And adjacent titania nanoparticles 2 are connected with a predetermined strength.

Such a crystalline metal oxide structure 1 is connected to titania nanoparticles 2 according to the pH change in the solution during the production process described later, the heating temperature during the production process, the heating time, and the content of the one-dimensional structure forming substance. The number and state of the one-dimensional array can change.

In the case of this embodiment, the titania nanoparticle 2 is made of titania, and has a configuration in which the particle diameter is controlled to a nano size having a spherical shape and a particle size of about 5 to 8 nm. The titania nanoparticle 2 forms a crystalline metal oxide structure 1 with several to several tens as one unit, and has such a hardness that it cannot be dispersed even when an external force such as ultrasonic waves is applied. Are connected to each other.

(2) Method for Producing Crystalline Metal Oxide Structure In such a crystalline metal oxide structure 1 according to the present invention, first, particulate titania nanoparticles 2 are first generated, and the crystalline metal oxidation described later is performed. It can be generated by connecting a plurality of titanias 3 in a one-dimensional array in accordance with a physical structure generation processing procedure. Here, after first describing the titania nanoparticle generation process for generating the titania nanoparticles 2, the crystalline metal oxide structure generation process for generating the crystalline metal oxide structure 1 using the titania 3 will be described in order. To do.

(2-1) Titania Nanoparticle Generation Processing Procedure Here, a typical generation procedure of the titania nanoparticle 2 will be described below using the flowchart shown in FIG. As shown in FIG. 2, the routine proceeds from the start routine RT1 to the next step SP1, for example, preparing an aqueous solution 5 in which 130 to 220 g of 2-propanol is contained in 11.7 to 15.2 ml of water, and 9.6 to 12 g of the aqueous solution 5 is prepared. Titanium isopropoxide (Ti (iOPr) 4) is added and dissolved by vigorous stirring at room temperature to produce a hydrolyzed hydrolysis solution 6, and the process proceeds to the next step SP2.

In step SP2, the hydrolyzed solution 6 of step SP1 is filtered to obtain a precipitate 7. In the next step SP3, the precipitate 7 is washed several times to remove the washed precipitate from which excess 2-propanol has been removed. And move to the next step SP4. In step SP4, the washing precipitate 11 is redispersed in a predetermined amount of water 10 to produce a washing precipitate-containing solution 12, and the process proceeds to the next step SP5.

In step SP5, a predetermined amount of nitric acid (HNO ₃ ) is added to the washing precipitate-containing solution 12 to produce a mixed solution in which the H + / Ti4 + ratio is adjusted to 0.5 to 1.0, and then the mixed solution is stirred at room temperature for a predetermined time. Then, the colloidal titania sol 14 is generated by peptization (peptization), and the above-described titania nanoparticle generation processing procedure is completed (step SP6). In the titania sol 14 thus produced, spherical titania nanoparticles 2 having a nano size are dispersed in a solution, and titania crystals are stably present.

(2-2) Crystalline Metal Oxide Structure Generation Processing Procedure Next, using the titania nanoparticles 2 generated according to the above-described titania nanoparticle generation processing procedure, the crystallinity in which the titania nanoparticles 2 are connected in a one-dimensional array. A crystalline metal oxide structure generation processing procedure for generating the metal oxide structure 1 will be described below with reference to the flowchart shown in FIG. First, the routine proceeds from the start routine RT2 to the next step SP11, where the colloidal titania sol (solution containing the titania nanoparticles 2) 14 obtained by the above-described titania nanoparticle generation processing procedure is adjusted to pH 1 to 4 by dialysis. .

In this case, as shown in FIG. 4, for example, a cellophane tube 22 in which titania sol 14 is sealed is introduced into a beaker 21 in which distilled water 20 is placed. Next, a magnetic stirrer (not shown) is used to rotate the stirrer 23 in the beaker 21 by using magnetic force, dialyzed by stirring the distilled water 20, and the titania sol 14 in the cellophane tube 22 is adjusted to pH 1-4. adjust.

Here, when the titania sol 14 has a pH of less than 1, the density of positive charges (hydrogen ions) on the surface of the titania nanoparticles 2 becomes very high, and because of the repulsive interaction between the titania nanoparticles 2, after the heat treatment described later. In this case, the titania nanoparticles 2 are not in a one-dimensional array. On the other hand, when the titania sol 14 has a pH exceeding 4, when the density of the positive charges on the surface of the titania nanoparticles 2 decreases and the pH of the titania sol becomes close to the isoelectric point of the titania nanoparticles 2, the titania nanoparticles 2 after the heat treatment described later. However, a plurality of titania nanoparticles 2 are densely packed and solidified without being one-dimensionally arranged. Accordingly, the titania sol preferably has a pH of 1 to 4, preferably 3.5 to 4.

Next, after adding a predetermined amount of block copolymer to the pH-adjusted titania sol in step SP12, in step SP13, a reaction solution is generated by dissolving the block copolymer in the titania sol by heat treatment. At this time, for example, while maintaining the heating temperature at 25 to 190 ° C., the block copolymer is dissolved in the titania sol while stirring for a heating time of 1 to 30 days to produce a reaction solution. In addition, when the heating time is set to pH 3.5 to 4, if the length is increased, the number of titania nanoparticles 2 connected gradually increases. However, if the heating time is too long, a plurality of titania nanoparticles 2 arranged one-dimensionally are connected to each other. Aggregates and can become aggregates. Therefore, it is preferable that the heating time is less than 30 days so as not to form an aggregate.

The addition amount of the block copolymer is based on the amount of titania in the titania sol 14, and when titania (TiO ₂ ): block copolymer = 1: x (w: w (mass ratio)), x is 0.1 to 1 0.0 is preferred. That is, when x is less than 0.1, the amount of F127 adsorbed on the surface of the titania nanoparticles 2 is small, and the titania nanoparticles 2 are monodispersed without being one-dimensionally arranged, whereas when x exceeds 1.0 Since the amount of F127 adsorbed on the surface of the titania nanoparticle 2 increases and the one-dimensionally arranged titania nanoparticle 2 aggregates to form an aggregate, x is preferably 0.1 to 1.0.

Here, the block copolymer is a molecule obtained by chemically bonding polymers having different properties. Specifically, examples of the block copolymer include a triblock copolymer represented by R ₁ O— (R ₂ O) _s — (R ₃ O) _t — (R ₄ O) _u —R ₅ , R ₁ O— (R A diblock copolymer represented by ₂ O) _s- (R ₄ O) _u -R ₅ can be applied. In this case, R ₁ and R ₅ represent H or a lower alkylene group having 1 to 6 carbon atoms, R ₂ , R ₃ and R ₄ represent a lower alkylene group having 2 to 6 carbon atoms, s, t And u represents a number from 2 to 200. Such block copolymers are sold, for example, as Pluronic series from BASF.

In addition, as another block copolymer, a block copolymer in which the hydrophilic block is polyethylene oxide (hereinafter referred to as PEO) and the hydrophobic block is polystyrene (hereinafter referred to as PS) or polyisoprene (hereinafter referred to as PI) is applied. In this case, there are a triblock copolymer composed of PEO-PS (or PI) -PEO and a diblock block copolymer composed of PEO-PS (or PI), and the polymerization degree of the PEO block is represented by 2 to 200. The degree of polymerization of the PS (or PI) block is represented by 2-50.

Then, in the reaction solution generated in this manner, a crystalline metal oxide structure 1 in which several to several tens of titania nanoparticles 2 are connected in a one-dimensional array can be generated (step SP14).

(3) Operation and effect In the above configuration, the titania sol 14 in which the spherical titania nanoparticles 2 are dispersed is adjusted to a predetermined pH, and a predetermined amount of a block copolymer is added to the titania sol, and predetermined heating is performed. Heat at a predetermined heating temperature over time. As a result, the crystalline metal oxide structure 1 in which the dispersed titania nanoparticles 2 are one-dimensionally arranged and connected with such a hardness that the adjacent titania nanoparticles 2 cannot be dispersed even when an external force is applied is obtained as a reaction solution. Can be generated inside. Thus, by controlling the arrangement of the dispersed titania nanoparticles 2, the crystalline metal oxide structure 1 can be used for various applications as compared with the conventional case, and the field of use of the titania nanoparticles 2 can be further expanded than before. Can provide.

Further, in this crystalline metal oxide structure 1, by adjusting the pH of the titania sol 14 to 1 to 4 in the production process, the titania nanoparticles 2 are one-dimensionally arranged in a single chain shape and remain in this state. The titania nanoparticles 2 can be linked. Further, in the crystalline metal oxide structure 1, by increasing the heating temperature during the heat treatment in the generation process, a plurality of titania nanoparticles 2 in a one-dimensional array state can be aggregated, and thus the density of the titania nanoparticles 2 is increased. It is possible to form a crystalline metal oxide structure (shown in “Example (5-4) Heating temperature” described later), which is an aggregate having a high density.

In the crystalline metal oxide structure 1, the density of the titania nanoparticles 2 can be controlled by controlling the one-dimensional arrangement state of the titania nanoparticles 2, thereby easily controlling the dielectric constant and the refractive index. Further, it is possible to control characteristics such as a photocatalytic action and an ultraviolet shielding action.

(4) Manufacture of crystalline metal oxide structure Next, it verified that the crystalline metal oxide structure 1 mentioned above could be produced | generated. First, titania nanoparticles 2 were generated according to the flowchart shown in FIG. Here, after forming an aqueous solution in which 130 g of 2-propanol was dissolved in 14 ml of water, 12 g of titanium isopropoxide (Ti (iOPr) 4) was added to this aqueous solution and dissolved by vigorous stirring at room temperature. A hydrolyzed hydrolysis solution was produced.

Subsequently, this aqueous solution was filtered to obtain a precipitate, and the obtained precipitate was washed with water many times to produce a washed precipitate in which excess 2-propanol was removed from the precipitate. Then, a washing precipitate-containing solution in which the washing precipitate is re-dispersed in 183 ml of water is generated, and the washing precipitate-containing solution is adjusted so that the H + / Ti4 + ratio of the washing precipitate-containing solution is 0.5. Nitric acid (HNO ₃ ) was added to form a mixed solution.

Next, this mixed solution was stirred at room temperature for 3 days and peptized (peptized) to produce a colloidal titania sol. The titania sol thus obtained had a translucent ride blue color, and spherical titania nanoparticles 2 having a nano size were dispersed in the solution.

Next, according to the flowchart shown in FIG. 3, a crystalline metal oxide structure 1 was produced using this titania sol. Specifically, a cellophane tube filled with titania sol is put into a beaker containing distilled water, and the stirrer in the beaker is rotated by a magnetic stirrer, and the titania sol is dialyzed by stirring the distilled water. Was adjusted to pH 4.

Next, F127 (Pluronic F127) as shown in FIG. 5 was added to the titania sol as a block copolymer. In FIG. 5, MW indicates the molecular weight, HLB (Hydrophilic-Lipophilic Balance) indicates the property of the surfactant, and CMC (critical micelle concentration) indicates the critical micelle concentration. The amount of F127 added was set to F127: TiO ₂ = 0.1: 1 (W: W) based on the amount of titania (TiO ₂ ) in the titania sol. Next, as a heat treatment, the titania sol was continuously stirred for 7 days with the heating temperature maintained at 60 ° C., and F127 was completely dissolved in the titania sol to produce a reaction solution.

Next, the structure in the reaction solution thus produced was confirmed. FIG. 6 is a flowchart showing a verification procedure of the crystalline metal oxide structure 1, the process proceeds from start step RT 3 to step SP 15, where the reaction solution is diluted to about 1/10 with distilled water, and the structure in the reaction solution is obtained. Thus, it was made easier to determine the arrangement form of the titania nanoparticles 2 during the dip coating described later.

Next, in step SP16, in order to verify the structure in the reaction solution, the structure in the reaction solution was attached to the Si substrate by dip coating. Next, in step SP17, the Si substrate having the structure in the reaction solution attached to the surface is subjected to UV ozone treatment (ultraviolet wavelength 172 nm, pressure 50 Pa, irradiation time 30 min) to remove organic components, and then step SP18. The surface of this Si substrate was photographed with a scanning microscope to obtain an SEM image, and the verification procedure for the crystalline metal oxide structure 1 was completed (step SP19).

The SEM image obtained at this time is shown in FIG. As shown in FIG. 1, it was confirmed that a crystalline metal oxide structure 1 in which several to several tens of titania nanoparticles 2 are connected in a one-dimensional array is generated.

Further, the XRD pattern of the crystalline metal oxide structure 1 was measured using an X-ray diffraction (XRD (X-ray diffraction)) apparatus. Further, the crystalline metal oxide structure 1 was fired at about 300 ° C., and the XRD pattern was measured in the same manner for the fired crystalline metal oxide structure 1. As a result, XRD patterns as shown in FIG. 7 were obtained. From this XRD pattern, it was confirmed that the crystalline metal oxide structures 1 before and after firing were both made of anatase crystal-type titania.

(5) Dependence of various parameters (5-1) pH of titania sol
Next, in the crystalline metal oxide structure generation process shown in FIG. 3, the pH value in step SP11 was changed. Here, three types of titania sols with pH adjusted to 1.6, 3.38, and 3.58 were generated. It should be noted that the amount of F127 added in step SP12 and the heat treatment conditions in step SP13 remain unchanged, F127: TiO ₂ = 0.1: 1 (W: W), the heating temperature is 60 ° C., the heating time, respectively. For 7 days, and F127 was completely dissolved in titania sol to form a reaction solution.

Then, after diluting each reaction solution to about 1/10 with distilled water (step SP15), the structure in each reaction solution is adhered to the Si substrate by dip coating (step SP16), and UV ozone treatment is performed. (Step SP17). Each Si substrate to which the structure in the reaction solution was adhered in this manner was photographed with a scanning microscope (step SP18), and SEM images as shown in FIGS. 8A to 8C were obtained. FIG. 8D is the same SEM image as FIG. 1 and uses the titania sol whose pH is adjusted to 4 in step SP11. As described above, a plurality of titania nanoparticles 2 are primary in a single chain shape. The crystalline metal oxide structure 1 connected in the original arrayed state is generated.

As shown in FIG. 8A, even when the pH is adjusted to 1.6, the titania nanoparticles 2 in a one-dimensional array state may be aggregated, but a plurality of titania nanoparticles 2 are primary in a single chain shape. It was confirmed that the crystalline metal oxide structure 1 connected in the original arrayed state can be generated.

Further, as shown in FIGS. 8B and 8C, even when the pH is adjusted to 3.38 and 3.58, the crystalline metal oxide in which the titania nanoparticles 2 are connected in a one-dimensionally arranged state in one chain shape. It was confirmed that the structure 1 can be generated. Further, when the pH of the titania sol is adjusted to 3.38 and 3.58, it can be confirmed that the crystalline metal oxide structure 1 is dispersed as compared with the case where the pH of the titania sol is adjusted to 1.6. It was.

(5-2) Addition amount of F127 Next, in the crystalline metal oxide structure generation process shown in FIG. 3, when the addition amount of the block copolymer added to the titania sol having a pH of 4 is changed in step SP12, the crystalline property It was verified whether or not a metal oxide structure could be generated. Here, F127 as shown in FIG. 5 was used as the block copolymer. The amount of F127 added to the titania sol was TiO ₂ : F127 = 1: x (W: W) based on the amount of titania (TiO ₂ ) in the titania sol, and the value of x was changed.

Specifically, x of TiO ₂ : F127 = 1: x indicating the addition amount of F127 is adjusted to 0.1, 0.3, 0.5, 0.7, or 1.0, and the heat treatment in step SP13 is performed. The conditions were left unchanged, and the reaction temperature was 60 ° C., the heating time was 7 days, and five types of reaction solutions in which F127 was completely dissolved in titania sol were produced.

Then, after diluting each reaction solution to about 1/10 with distilled water (step SP15), the structure in each reaction solution is adhered to the Si substrate by dip coating (step SP16), and UV ozone treatment is performed. (Step SP17). Each Si substrate to which the structure in the reaction solution was attached in this manner was photographed with a scanning microscope (step SP18), and the SEM image obtained thereby was verified.

As shown in FIGS. 9A to 9E, titania nanoparticles 2 are one-dimensionally arrayed using any reaction solution in which x is adjusted to 0.1, 0.3, 0.5, 0.7, or 1.0. It was confirmed that the crystalline metal oxide structure 1 connected in a state can be generated.

(5-3) Heating time Next, in the crystalline metal oxide structure generation process shown in FIG. 3, when the heating time in step SP13 is changed, what crystalline metal oxide structure 1 is generated. We verified whether Here, the pH in step SP11 was 4.0, and the amount of F127 added in step SP12 was TiO ₂ : F127 = 1: 0.7. Under these conditions, four types of reaction solutions were generated with the heating temperature in step SP13 being 60 ° C. and the heating time being 1, 2, 7, or 14 days.

10A shows an SEM image when using a reaction solution with a heating time of 1 day (24 hours), FIG. 10B shows an SEM image when using a reaction solution with a heating time of 2 days, and FIG. Shows an SEM image when using a reaction solution with a heating time of 7 days, and FIG. 10D shows an SEM image when using a reaction solution with a heating time of 14 days.

10A to 10D, it was confirmed that the crystalline metal oxide structure 1 in which the titania nanoparticles 2 are connected in a one-dimensional array in one chain can be generated. In particular, even when the heating time is shortened to one day, the addition amount of F127 is set to x = 0.7, the heating temperature is set to 60 ° C., and the pH is set to 4, whereby the crystalline metal oxide structure 1 is generated. It was confirmed that

(5-4) Heating temperature Next, in the crystalline metal oxide structure generation process shown in FIG. 3, when the heating temperature in step SP13 is changed, what kind of crystalline metal oxide structure 1 is generated. We verified whether Here, the pH in step SP11 was 3.38, and the amount of F127 added in step SP12 was TiO ₂ : F127 = 1: 0.1. Under these conditions, the heating time in step SP13 was set to 3 days, and six types of reaction solutions with heating temperatures of 80 ° C., 100 ° C., 120 ° C., 150 ° C., 175 ° C. or 190 ° C. were produced.

FIG. 11A shows an SEM image when using a reaction solution with a heating temperature of 80 ° C., FIG. 11B shows an SEM image when using a reaction solution with a heating temperature of 100 ° C., and FIG. 11C shows the heating temperature. FIG. 11D shows an SEM image when using a reaction solution with a heating temperature of 150 ° C., and FIG. 11E shows a reaction solution with a heating temperature of 175 ° C. FIG. 11F shows an SEM image when a reaction solution having a heating temperature of 190 ° C. is used.

11A to 11C, it can be confirmed that even when the heating temperature is changed to 80 to 120 ° C., the crystalline metal oxide structure 1 in which the titania nanoparticles 2 are connected in a one-dimensional array in a single chain can be generated. It was. Further, from FIG. 11D, even when the heating temperature is changed to 150 ° C., an aggregate in which the titania nanoparticles 2 in a one-dimensional array state are aggregated and bonded can be formed, but part of the crystalline metal oxide structure 1 can also be generated. It was confirmed that

However, from FIGS. 11E and 11F, when the heating temperature was changed to 175 to 190 ° C., aggregates were formed in which the titania nanoparticles 2 in a one-dimensional array were aggregated and bonded. Thus, it has been confirmed that as the heating temperature is increased, an aggregate in which the titania nanoparticles 2 in a one-dimensional array are aggregated is easily generated. Therefore, when manufacturing the crystalline metal oxide structure 1 in which the titania nanoparticles 2 are connected in a one-dimensional array in a single chain, the heating temperature is preferably 80 to 150 ° C.

(5-5) Relationship between heating time and pH Next, assuming that the pH in step SP11 is 4, in step SP12, x of TiO ₂ : F127 = 1: x is set to 0.1, 0.3, 0.5 Five kinds of reaction solutions having different F127 addition amounts adjusted to 0.7 or 1.0 were prepared. And in step SP13, when heat-processing with respect to these 5 types of reaction solutions, it verified about how the pH of each reaction solution would change when heating time was lengthened.

As a result, a result as shown in FIG. 12 was obtained. From the results shown in FIG. 12, it was confirmed that the pH of the reaction solution was lowered as the heating time was increased. Therefore, even if the pH is adjusted at the stage of dialysis, it is confirmed that the pH changes due to the heat treatment, and the above numerical value of the pH range is confirmed to be the pH range at the time of dialysis. did.

(6) About connection degree of titania nanoparticles in crystalline metal oxide structure Next, the connection strength of the obtained crystalline metal oxide structure 1 was verified. From the TEM image of the crystalline metal oxide structure 1, a clean crystal lattice was observed between the titania nanoparticles 2 and the titania nanoparticles 2. It was also confirmed that the one-dimensional arrangement state of the titania nanoparticles 2 was not broken even when an external force such as ultrasonic irradiation was applied to the crystalline metal oxide structure 1.

(7) Other Embodiments The present invention is not limited to the present embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the embodiment described above, the titania nanoparticles 2 made of titania are used as the crystalline metal oxide particles, and the plurality of titania nanoparticles 2 are connected in a one-dimensional array in a single chain shape. However, the present invention is not limited to this. For example, alumina, aluminosilicate, zeolite, zirconia, stable zirconia, ceria, magnesia, calcia, strontium oxide, barium oxide, oxide Scandium, yttria, hafnia, vanadium oxide, niobium, tantalum oxide, chromia, molybdenum oxide, tungsten oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, silver oxide, zinc oxide, gallium oxide, indium oxide, oxide Germanium, tin oxide, ITO (oxide oxide In addition to various crystalline metal oxide particles made of various types of crystalline metal oxides, such as tin oxide, lead oxide, antimony oxide, bismuth oxide, neodymium oxide, lanthanum oxide, samarium oxide, dysprosium oxide, ytterbium oxide, europium oxide, etc. A crystalline metal oxide structure in which oxide particles are connected in a one-dimensional array in a single chain may be generated.

Furthermore, conductive crystalline nanoparticles may be used for the crystalline metal oxide particles of the present invention. Examples of conductive crystalline metal oxides include tin oxide, indium oxide, alumina, zirconia, ceria, magnesia, calcia, strontium oxide, barium oxide, scandium oxide, yttria, hafnia, vanadium oxide, niobium, and tantalum oxide. , Chromia, molybdenum oxide, tungsten oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, silver oxide, zinc oxide, gallium oxide, germanium oxide, tin oxide, lead oxide, antimony oxide, bismuth oxide, neodymium oxide , Lanthanum oxide, samarium oxide, dysprosium oxide, ytterbium oxide, europium oxide, rhenium oxide, etc., which are mixed oxides, or doped with inorganic elements (for example, GZO (gallium-doped zinc oxide), I ZO (Indium Doped Zinc Oxide), AZO (Aluminum Doped Zinc Oxide), etc.) or non-stoichiometric metal oxides may be used to develop conductivity, especially tin oxide, ITO or FTO Those containing tin oxide such as (fluorine-doped tin oxide) and ATO (antimony-doped tin oxide) are preferred.

Furthermore, in the above-described embodiment, the case where the titania nanoparticle 2 is generated according to the titania nanoparticle generation process shown in the flowchart of FIG. 2 has been described. However, the present invention is not limited thereto, and the dispersed titania nanoparticle 2 can be obtained. In addition, the titania nanoparticles 2 may be generated by various generation processes.

Further, in the above-described embodiment, the case where the pH of the titania sol is adjusted by dialysis in step SP11 shown in FIG. 4 is described, but the present invention is not limited to this, and hydrochloric acid, nitric acid, sulfuric acid, The pH of the titania sol may be adjusted using various other pH adjusting agents such as acetic acid.

(7-1) Case where tin oxide nanoparticles are applied as crystalline metal oxide particles Next, even when tin oxide nanoparticles made of tin oxide are used as crystalline metal oxide particles, the tin oxide nanoparticles are linear. It was verified whether or not a crystalline metal oxide structure in which adjacent tin oxide nanoparticles are connected with a predetermined strength can be generated in a linear or curved line in a line.

Here, a colloidal tin oxide sol was prepared in which spherical tin oxide nanoparticles having a particle size of about 5 nm were dispersed in a solution. This tin oxide sol is a tin oxide sol manufactured by Taki Chemical, and has a pH of 9.9 and tin oxide (SnO ₂ ) contained in the solution at a rate of 1 Wt%.

Next, a crystalline metal oxide structure was produced from this tin oxide sol. Specifically, first, as a block copolymer, F127 (Pluronic F127) shown in FIG. 5 was added to the tin oxide sol. The amount of F127 added was F127: SnO ₂ = 1: 1 (W: W) based on the amount of tin oxide (SnO ₂ ) in the tin oxide sol.

Next, hydrochloric acid (HCl) was added as a pH adjusting agent to the tin oxide sol to which F127 was added to adjust to a predetermined pH. Here, three types of tin oxide sols having different pH values, which were adjusted to 7.0, 8.0, and 9.0, were generated.

Next, as a heat treatment, a tin oxide sol was heated and allowed to stand for 5 days while maintaining the heating temperature at 60 ° C. to produce a reaction solution. That is, the addition amount of F127 and the heat treatment conditions are not changed, F127: SnO ₂ = 1: 1 (W: W), the heating temperature is 60 ° C., the heating time is 5 days, and only the pH is set. Three types of reaction solutions with different values were produced.

Then, after diluting each reaction solution to about 1/10 with distilled water (step SP15 in FIG. 6), the structures in each reaction solution are formed on the Si substrate by dip coating (the pulling speed at the time of dip coating is 10 mm / min). Each was adhered (step SP16 in FIG. 6), and UV ozone treatment was performed to remove organic components (step SP17 in FIG. 6). Each of the Si substrates to which the structures in the reaction solution were attached in this manner was photographed with a scanning microscope (step SP18 in FIG. 6), and SEM images as shown in FIGS. 13A to 13C were obtained.

As shown in FIG. 13A, when the pH is adjusted to 7.0, there are some places where the tin oxide nanoparticles 12 in a one-dimensional arrangement state are aggregated, but a plurality of tin oxide nanoparticles 12 are in one chain. It was confirmed that the crystalline metal oxide structure 11 connected in a one-dimensionally arranged state can be generated.

Further, as shown in FIGS. 13B and 13C, even when the pH is adjusted to 8.0 and 9.0, the crystalline metal in which the tin oxide nanoparticles 12 are connected in a one-dimensional array in a single chain shape. It was confirmed that the oxide structure 11 can be generated. Furthermore, when the pH of the tin oxide sol is adjusted to 8.0 and 9.0, the crystalline metal oxide structure 11 may be dispersed as compared with the case where the pH of the tin oxide sol is adjusted to 7.0. It could be confirmed.

Next, when a TEM image was taken with respect to the crystalline metal oxide structure 11 produced by adjusting the pH to 8.0, results as shown in FIGS. 14A and 14B were obtained. Also from the TEM images shown in FIGS. 14A and 14B, it was confirmed that the crystalline metal oxide structure 11 was joined to the tin oxide nanoparticles 12 and the tin oxide nanoparticles 12. FIG. 14C is an electron diffraction image of the tin oxide nanoparticles 12 in the crystalline metal oxide structure 11 prepared by adjusting the pH to 8.0. From FIG. 14C, the tin oxide nanoparticles 12 have a crystalline property. It was confirmed that it had.

Thus, even when crystalline tin oxide nanoparticles 12 made of tin oxide are used as the crystalline metal oxide particles, a plurality of tin oxide nanoparticles 12 are arranged in a line in a linear or curved line in a ball chain shape. It was confirmed that the linked crystalline metal oxide structure 11 can be generated.

Here, when the tin oxide nanoparticles made of tin oxide are used as the crystalline metal oxide particles, the tin oxide nanoparticles arranged in a linear or curved line in a line in a ball chain shape have a particle size of 5 It may be nano size of about 10 nm.

In addition, the tin oxide sol used in the manufacturing process described above may contain tin oxide in a ratio of 0.5 to 3 wt%, and the ball chain structure can be formed in a shorter time by increasing the concentration of tin oxide. be able to.

The amount of the block copolymer added to the tin oxide sol in the process of manufacturing the crystalline metal oxide structure is based on the amount of tin oxide in the tin oxide sol, and tin oxide: block copolymer = 1: x (w: w (Mass ratio)), x is preferably 0.1 to 4.0. That is, when x is less than 0.1, the amount of F127 adsorbed on the surface of the tin oxide nanoparticles 12 is small, and the tin oxide nanoparticles 12 are in a monodispersed state without being one-dimensionally arranged. Since the amount of F127 adsorbed on the surface of the tin nanoparticles 12 increases and the one-dimensionally arranged tin oxide nanoparticles 12 aggregate to form aggregates, x is preferably 0.1 to 4.0.

The pH adjusted by adding a pH adjuster (hydrochloric acid) to the tin oxide sol to which F127 has been added is preferably 7.0 to 9.0. That is, when the pH is less than 7.0, the one-dimensionally arranged tin oxide nanoparticles 12 tend to aggregate, and when the pH is higher than 9.0, a short ball chain structure is formed. Therefore, the pH is preferably 7.0 to 9.0.

In addition, the heating temperature at the time of heat treatment when the tin oxide sol is allowed to stand in the production process is monodispersed particles when the temperature is lower than 40 ° C, and tin oxide nanoparticles 12 tend to aggregate when the temperature is higher than 80 ° C. 40 to 80 ° C. is preferable.

Furthermore, as the heating time at the time of heat treatment when the tin oxide sol is left to stand in the production process, when it is less than 1 day, it becomes a short ball chain, and when it is longer than 30 days, the tin oxide nanoparticles 12 tend to aggregate. 1 to 30 days is preferable.

Claims

A dissolution step of adjusting the pH of the solution containing the crystalline metal oxide particles to a predetermined pH and dissolving a one-dimensional structure-forming substance having a one-dimensional structure-forming ability to generate a reaction solution;
Generating a crystalline metal oxide structure in which the crystalline metal oxide particles are connected in a one-dimensional array by heating the reaction solution for a predetermined heating time at a predetermined heating temperature; and A method for producing a crystalline metal oxide structure, comprising:
By adjusting the pH in the dissolving step, the heating temperature and the heating time in the generating step, the crystalline metal oxides adjacent to each other in a state where the crystalline metal oxide particles are arranged one-dimensionally The method for producing a crystalline metal oxide structure according to claim 1, wherein the particles are connected with a predetermined strength.
3. The crystalline metal oxide structure according to claim 1, wherein the crystalline metal oxide particles are titania nanoparticles, and the one-dimensional structure forming substance is a block copolymer. Production method.
3. The crystalline metal oxide according to claim 1, wherein in the dissolving step, the crystalline metal oxide particles are nanoparticles having conductivity, and the one-dimensional structure-forming substance is a block copolymer. A method for manufacturing a structure.
The method for producing a crystalline metal oxide structure according to claim 4, wherein the nanoparticles include tin oxide.