Method for producing colloidal crystal structure, method for transferring colloidal crystal structure, transferred article, colloidal particles, colloidal crystal structure, colloidal crystal film, and composition for producing colloidal crystal structure

Abstract

To provide a method for producing a colloidal crystal structure which enables a colloidal crystal structure of high quality and large area to be easily produced in a short time.SOLUTION: Light is applied to a composition comprising colloidal particles dispersed in a dispersion medium, where the colloidal particles comprise polymer chains with photo-crosslinkable sites introduced onto the surfaces of core particles.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for producing a colloidal crystal structure, a method for transferring a colloidal crystal structure, a transferred product, colloidal particles, a colloidal crystal structure, a colloidal crystal film, and a composition for producing a colloidal crystal structure. [Background technology]

[0002] Colloidal crystal structures, in which colloidal particles are regularly arranged, exhibit various optical properties depending on the composition and particle size of the colloidal particles. For example, colloidal crystal structures made of polymeric or inorganic fine particles exhibit structural colors that are angle-dependent, in which the color changes depending on the viewing angle due to light scattering or interference, and are therefore used as paint materials or film materials. In addition, colloidal crystal structures made of metal nanoparticles exhibit plasmon resonance, and are therefore used as sensor materials.

[0003] Conventionally, a method for producing a colloidal crystal structure is known in which a close-packed structure is formed in a self-organized manner when the dispersion medium evaporates from a dispersion liquid in which colloidal particles are dispersed. The simplest method among such production methods is the natural drying method, in which a dispersion liquid of colloidal particles is dropped onto a substrate and the dispersion medium is volatilized to produce a colloidal crystal structure (see Patent Document 1). However, the natural drying method not only requires a long time to produce a colloidal crystal structure, but also has problems in that it is difficult to achieve high quality (uniformity) and large area. Therefore, various methods such as spin coating, spraying, dip coating, roll-to-roll, and Langmuir-Blodgett (LB) methods have been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-23631 A (Page 8, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the spin coating method and spray method can easily produce colloidal crystal structures in a relatively short time, it is difficult to produce high-quality, large-area colloidal crystal structures. In addition, the dip coating method, roll-to-roll method, and LB method can produce high-quality, large-area colloidal crystal structures, but they have the disadvantages of not only taking time to produce them, but also requiring expensive, precise equipment. In order to develop applications and products using colloidal crystal structures, there is a demand for the development of technology that can easily produce high-quality, large-area colloidal crystal structures in a short time without using special equipment.

[0006] The present invention has been made in light of these problems, and has an object to provide a method for producing a colloidal crystal structure, which enables a high-quality, large-area colloidal crystal structure to be easily produced in a short period of time. [Means for solving the problem]

[0007] The present inventors have conducted intensive research into the above-mentioned problems and have discovered that colloidal crystallization can be induced in a short period of time by irradiating light to a composition in which colloidal particles, having polymer chains having photocrosslinking sites introduced on the surfaces of core particles, are dispersed in a dispersion medium. This discovery led to the completion of the present invention.

[0008] The polymer chain may also be a copolymer polymer chain having a hydrophilic portion and a photocrosslinkable portion.

[0009] The core particles may also be polymer particles.

[0010] A method for transferring a colloidal crystal structure according to another aspect of the present invention comprises the steps of: a step of irradiating light to a composition in which colloidal particles, each of which has a polymer chain having a photocrosslinking site introduced on the surface of a core particle, are dispersed in a dispersion medium, to obtain a colloidal crystal structure; and transferring the resulting colloidal crystal structure to a substrate.

[0011] A transcript according to another aspect of the present invention comprises: This can be achieved by irradiating a composition in which colloidal particles, in which polymer chains having photocrosslinking sites have been introduced onto the surface of the core particle, are dispersed in a dispersion medium, and the resulting colloidal crystal structure is transferred to a substrate.

[0012] The colloidal particles according to another aspect of the present invention are A core particle; and a polymer chain having a photocrosslinking site.

[0013] The polymer chain may also be a copolymer polymer chain having a hydrophilic portion and a photocrosslinkable portion.

[0014] The core particles may also be polymer particles.

[0015] A colloidal crystal structure according to another aspect of the present invention comprises: It has a close-packed structure of colloidal particles including a core particle and a polymer chain having a photocrosslinking site.

[0016] A colloidal crystal film according to another aspect of the present invention comprises: It has a colloidal crystal structure with a close-packed structure of colloidal particles.

[0017] A composition for producing a colloidal crystal structure according to another aspect of the present invention comprises: A colloidal particle including a core particle and a polymer chain having a photocrosslinking site; and a dispersion medium for dispersing the colloidal particles. Effect of the Invention

[0018] According to the method for producing a colloidal crystal structure of the present invention, a high-quality, large-area colloidal crystal structure can be easily produced in a short time without using any special equipment. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is an explanatory diagram showing an example of introduction of a polymer chain into a core particle constituting a colloidal particle according to an embodiment of the present invention. [Diagram 2] FIG. 1(a) is a photograph showing a state in which a colloidal crystal structure is formed on the surface (air interface) of a dispersion of colloidal particles according to an embodiment of the present invention in a petri dish by irradiating it with white light, and FIG. 1(b) is a photograph showing that the colloidal crystal structure of (a) has an angle-dependent structural color. [Diagram 3] FIG. 3 is a photograph showing the state in which the colloidal crystal structure (colloidal crystal film) formed on the surface of the dispersion liquid in FIG. 2 has been transferred onto a glass substrate. [Figure 4] FIG. 2 is a photograph showing a state in which a colloidal crystal structure is formed by coating a dispersion of colloidal particles according to an embodiment of the present invention on a glass substrate in the form of a thin film and irradiating the substrate with white light. [Diagram 5] FIG. 5 is a photograph showing that the colloidal crystal structure of FIG. 4 has an angle dependence of structural color. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to Fig. 1. However, the present invention can be embodied in many different forms and is not limited to the following embodiments and examples.

[0021] The method for producing a colloidal crystal structure according to the present invention (hereinafter simply referred to as the "production method") induces colloidal crystallization by irradiating light to a composition in which colloidal particles, in which polymer chains having photocrosslinking sites have been introduced onto the surfaces of core particles, are dispersed in a dispersion medium, and a high-quality, large-area colloidal crystal structure is easily produced in a short time without using any special equipment. In addition, since the production method of the present invention utilizes photocrosslinking caused by light irradiation to induce colloidal crystallization, colloidal crystallization can be achieved accurately in a short time by controlling the light intensity and irradiation time.

[0022] First, an example of the introduction of a polymer chain into a core particle constituting a colloidal particle in the production method of this embodiment is shown in FIG.

[0023] As shown in FIG. 1, for example, water (H 2 Polystyrene-polydopamine particles (PSt-PDA particles) as core particles and polymer PMM-SH are added to the mixture O) and reacted at room temperature for 24 hours (Michael addition reaction), to obtain colloidal particles (PSt-PDA-PMM particles) in which polymer chain PMM is graft-polymerized onto the surface of the PSt-PDA particles. Note that, although the present embodiment describes an embodiment in which colloidal particles are obtained by the Michael addition reaction, the present invention is not limited to this, and the colloidal particles may be obtained by utilizing other reactions such as the Schiff base reaction.

[0024] Here, the PSt-PDA particles are core-shell type artificial melanin particles in which the surface of a polystyrene core particle is coated with polydopamine, and serve as the base of the colloidal particles.

[0025] The polymer PMM-SH is a copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) and N-methacryloyl-(L)-tyrosine methyl ester (MAT), where MPC is a hydrophilic monomer with excellent water dispersion properties, and MAT is a photocrosslinkable monomer that reacts under light irradiation.

[0026] That is, the polymer chain PMM introduced onto the surface of the core particle, the PSt-PDA particle, is a copolymer polymer chain having a hydrophilic portion derived from MPC and a photocrosslinking portion derived from MAT.

[0027] In addition, hydrophilic monomers that make up the polymer chain are not limited to MPC, but include hydroxyethyl methacrylate, N-(2-hydroxyethyl)acrylamide, N-isopropylacrylamide, and zwitterionic monomers (phosphobetaine type monomers, carboxybetaine type monomers, sulfobetaine type monomers), etc.

[0028] In addition, the photocrosslinking monomer constituting the polymer chain is not limited to MAT, but may be a monomer containing a cinnamic acid, coumarin, or chalcone skeleton as a photocrosslinking group.

[0029] In the preparation method of this embodiment, it is preferable that the colloidal particles (PSt-PDA-PMM particles) are in a state in which the surface of the PSt-PDA core particle is covered with a layer of many PMM polymer chains (see dot hatching in FIG. 1) by surface-initiated graft polymerization of many PMM polymer chains onto the surface of the PSt-PDA core particle. This makes it easier for the colloidal particles to self-organize into a close-packed structure, and a colloidal crystal structure can be stably prepared.

[0030] Furthermore, in the production method of this embodiment, the core particles are not limited to PSt-PDA particles, which are polymeric microparticles, but may be, for example, polymeric microparticles other than PSt-PDA particles, inorganic microparticles such as silica and titania, or metal microparticles such as gold nanoparticles and silver nanoparticles, as long as they are capable of forming a colloidal crystal structure.

[0031] Furthermore, the core particles are not limited to those having a core-shell structure such as PSt-PDA particles.

[0032] The particle diameter of the core particles is preferably nano-sized, submicron-sized, or micron-sized. Specifically, the particle diameter of the core particles is preferably 20 nm to 1 μm, and more preferably 100 to 300 nm. The particle diameter of the core particles is preferably uniform.

[0033] In order to prepare a colloidal crystal structure that exhibits a vivid structural color, the core particles are preferably fine particles of submicron size, particularly with a particle diameter of 100 to 300 nm.

[0034] Furthermore, in the preparation method of this embodiment, the polymer chain introduced into the colloidal particle is not limited to a copolymer polymer chain having a hydrophilic portion and a photo-crosslinking portion such as the polymer chain PMM, but may be any polymer chain having at least a photo-crosslinking portion.

[0035] Furthermore, the polymer chains introduced into the colloidal particles do not have to be introduced in large numbers so as to cover the surface of the core particle, and may be partially attached to the surface of the core particle as long as a colloidal crystal structure can be formed by photocrosslinking.

[0036] Next, in the preparation method of this embodiment, as described above, colloidal particles having polymer chains with photocrosslinking sites on the surface of the core particles are dispersed in water as a dispersion medium to prepare a dispersion liquid, which is a composition for preparing a colloidal crystal structure, and white light (peak wavelength 450 nm) is irradiated in the presence of a small amount of catalyst (e.g., tris(bipyridine) ruthenium (II) chloride and ammonium persulfate). This induces colloidal crystallization at the air interface (gas-liquid interface) of the dispersion liquid in a short time (several minutes), and a high-quality (highly uniform) colloidal crystal structure can be formed.

[0037] In this embodiment, the photo-crosslinking site in the polymer chain PMM introduced onto the surface of the PSt-PDA particle is derived from MAT, and thus colloidal crystallization is induced by irradiating with white light. However, depending on the type of photo-crosslinking site in the polymer chain introduced into the colloidal particle, colloidal crystallization may be induced by irradiating with light having an optimal wavelength in a narrow wavelength range, such as ultraviolet light or blue light, rather than light having a wide wavelength range such as white light.

[0038] In addition, in this embodiment, since the polymer chain PMM introduced onto the surface of the PSt-PDA particle is a copolymer polymer chain having a hydrophilic portion and a photo-crosslinking portion, water is used as the dispersion medium of the colloidal particle dispersion, but the dispersion medium is not limited thereto and may be an aqueous solvent such as a water-containing alcohol.

[0039] Furthermore, in this embodiment, a colloidal crystal structure obtained by irradiating light onto a dispersion liquid, which is a composition for producing the above-mentioned colloidal crystal structure, is transferred onto a substrate, thereby producing a transfer product in which a colloidal crystal structure is formed as a film on a substrate. EXAMPLES

[0040] Here, a dispersion liquid of colloidal particles according to the above embodiment was actually prepared, and it was confirmed whether a colloidal crystal structure could be formed.

[0041] The colloid particles (PSt-PDA-PMM particles) described in the above embodiment were dispersed in water to prepare a dispersion liquid, and the dispersion liquid and a small amount of catalyst were added to a petri dish with a diameter of 2.5 cm, and white light (peak wavelength 450 nm) was irradiated from above. The result is shown in Figure 2. The particle diameter of the core particles (PSt-PDA particles) that make up the colloid particles in this example is about 200 to 300 nm.

[0042] As shown in Figure 2(a), it was confirmed that a colloidal crystal structure was formed on the surface (air interface) of the dispersion in the petri dish within a short period of time, about 5 minutes, from the start of white light irradiation, and that a structural color was expressed.

[0043] In addition, as shown in Fig. 2(b), the colloidal crystal structure formed on the surface of the dispersion in the petri dish was confirmed to have an angle-dependent structural color that appears to change color depending on the viewing angle, and it is therefore presumed that a high-quality (highly uniform) colloidal crystal structure has been formed. Note that the colloidal crystal structure of this example appears orange at the angle of the photograph in Fig. 2(a), red at the angle of the photograph on the left in Fig. 2(b), yellow at the angle of the photograph in the center, and green at the angle of the photograph on the right, and appears to change color depending on the viewing angle.

[0044] In addition, the colloidal crystal structure formed on the surface of the dispersion liquid was formed as a thin film at the air interface, and it was confirmed that this colloidal crystal film could be transferred onto a hydrophilic glass substrate and exhibited structural color (see Figure 3).

[0045] Furthermore, as shown in Figure 4, by coating a hydrophilic glass substrate with a thin film of the dispersion and irradiating it with white light, a colloidal crystal structure (colloidal crystal film) was formed on the glass substrate in a short period of time, and it was confirmed that this colloidal crystal film exhibited structural color.

[0046] It is presumed that a high-quality colloidal crystal structure has been formed, since the angle dependence of structural color was also confirmed for the colloidal crystal structure (colloidal crystal film) formed on the glass substrate, as shown in Figure 5. When the colloidal crystal structure actually formed on the glass substrate was observed under magnification with an electron microscope, as shown in the enlarged portion of Figure 4, it was confirmed that a close-packed structure of colloidal particles had been formed.

[0047] They also confirmed that a similarly high-quality colloidal crystal structure was formed when the dispersion was irradiated with blue light (peak wavelength 450 nm) instead of white light.

[0048] As described above, these embodiments and examples make it possible to provide a novel method for producing a colloidal crystal structure, which can easily produce a high-quality, large-area colloidal crystal structure in a short time by simply irradiating light without using any special equipment, a method for transferring a colloidal crystal structure, a transferred product, colloid particles, a colloidal crystal structure, a colloidal crystal film, and a composition for producing a colloidal crystal structure. [Industrial Applicability]

[0049] The present invention is a novel method for producing a colloidal crystal structure, which induces colloidal crystallization by irradiating light to a composition in which colloidal particles, in which a polymer chain having a photocrosslinking site is introduced on the surface of a core particle, are dispersed in a dispersion medium, and a high-quality, large-area colloidal crystal structure can be easily produced in a short time without using a special device, and has industrial applicability as a method for transferring a colloidal crystal structure, a transfer product, colloidal particles, a colloidal crystal structure, a colloidal crystal film, and a composition for producing a colloidal crystal structure. The present invention has a wide range of applications, such as simple sensors, optical devices, structural color / reflective films, decorative materials, architectural / industrial paints, cosmetics, and reflective displays, depending on the characteristics of the colloidal particles. In addition, the present invention is highly safe for the human body because these products can be produced without using organic solvents.

Claims

1. A method for producing a colloidal crystal structure, comprising irradiating light to a composition in which colloidal particles, each of which has a polymer chain having a photocrosslinking site introduced on the surface of its core particle, are dispersed in a dispersion medium.

2. 2. The method for producing a colloidal crystal structure according to claim 1, wherein the polymer chain is a copolymer polymer chain having a hydrophilic portion and the photocrosslinkable portion.

3. 2. The method for producing a colloidal crystal structure according to claim 1, wherein the core particle is a polymer fine particle.

4. a step of irradiating light to a composition in which colloidal particles, each of which has a polymer chain having a photocrosslinking site introduced on the surface of a core particle, are dispersed in a dispersion medium, to obtain a colloidal crystal structure; transferring the resulting colloidal crystal structure onto a substrate; A method for transferring a colloidal crystal structure having the following structure:

5. A transfer product obtained by transferring the colloidal crystal structure according to claim 4 onto a substrate.

6. A colloidal particle comprising a core particle and a polymer chain having a photocrosslinking site.

7. 7. The colloidal particle according to claim 6, wherein the polymer chain is a copolymer polymer chain having a hydrophilic portion and the photocrosslinking portion.

8. 7. The colloidal particle according to claim 6, wherein the core particle is a polymer fine particle.

9. A colloidal crystal structure having a close-packed structure of the colloidal particles according to any one of claims 6 to 8.

10. A colloidal crystal film having the colloidal crystal structure according to claim 9.

11. A colloidal particle according to any one of claims 6 to 8, A dispersion medium for dispersing the colloidal particles; 1. A composition for producing a colloidal crystal structure comprising:

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