Composite particles and film-like members

Abstract

The present invention provides composite particles capable of producing a film-like member whose mechanical properties can be altered by irradiation with ultraviolet light or the like, and a film-like member containing these composite particles. [Solution] A composite particle comprising inorganic particles, a shell layer located on the surface of the inorganic particles and comprising a first polymer chain containing a plurality of first constituent units derived from acrylic acid ester, and a second polymer chain containing a second constituent unit derived from acrylic acid ester and a third constituent unit having a structure capable of forming a cyclic polymer structure by irradiation with active energy rays, wherein the first polymer chain and the second polymer chain are positioned in that order when viewed from the inorganic particle side.

Description

[Technical Field]

[0001] This disclosure relates to composite particles and film-like members. [Background technology]

[0002] When light is incident on a colloidal crystal, in which microparticles of uniform size are arranged regularly in three dimensions, light of a specific wavelength corresponding to the spacing between the microparticle planes is reflected (Bragg reflection). If the wavelength of this reflected light falls within the visible light wavelength range, it can be observed as structural coloration. Numerous studies have been conducted on these colloidal crystals, and their application to various optical elements and optically functional materials is expected.

[0003] For example, a resin-fixed colloidal crystal sheet is known that comprises colloidal crystals in which the gaps between fine particles are filled with a resin such as acrylic resin or epoxy resin (see, for example, Patent Document 1).

[0004] Furthermore, composite particles have been proposed that can form colloidal crystalline materials that are recyclable even in the event of damage, etc., comprising inorganic particles and a shell layer located on the surface of the inorganic particles and covering the inorganic particles, which includes polymer chains containing multiple constituent units derived from acrylic monomers (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6086513 [Patent Document 2] Japanese Patent Publication No. 2024-105175 [Overview of the project] [Problems that the invention aims to solve]

[0006] Patent Document 2 proposes composite particles capable of forming a colloidal crystalline material that can be recycled even in the event of damage. By hot-pressing these composite particles and applying vibrational shear strain, a colloidal crystalline elastomer film can be fabricated. However, if the mechanical properties of this elastomer film are to be changed, it is necessary to change the composition of the polymer chains grafted onto the inorganic particle surface. Therefore, it was necessary to fabricate composite particles with different polymer chain compositions on the inorganic particle surface depending on the required mechanical properties.

[0007] This disclosure has been made in view of the above, and aims to provide composite particles capable of producing a film-like member whose mechanical properties can be changed by irradiation with ultraviolet light, etc., and a film-like member containing these composite particles.

[0008] The following are examples of specific means for solving the problem: <1> Inorganic particles and A shell layer comprising a first polymer chain located on the surface of the inorganic particles and containing a plurality of first structural units derived from acrylic acid ester, and a second polymer chain containing a second structural unit derived from acrylic acid ester and a third structural unit having a structure capable of forming a cyclic polymer structure by irradiation with active energy rays, A composite particle comprising the first polymer chain and the second polymer chain, as viewed from the inorganic particle side. <2> The third constituent unit further comprises a structure derived from an acrylic acid ester. <1> The composite particles described above. <3> The structure capable of forming a cyclic polymer structure by irradiation with the aforementioned active energy rays is Kumari. It is a cinnamic skeleton, anthracene skeleton, thymine skeleton, styrylpyrene skeleton, or cinnamic acid skeleton. <1> or <2> The composite particles described above. <4> The third constituent unit is at least one selected from the group consisting of a constituent unit derived from an acrylic acid ester represented by the following chemical formula (a) and a constituent unit derived from an acrylic acid ester represented by the following chemical formula (b). <1> ~ <3> A composite particle described in any one of the following.

[0009]

Chem.

[0010] In chemical formula (a) and chemical formula (b), R1 and R2 are divalent linking groups. <5> The content of the third structural unit is 0.010 mol% to 2.0 mol% with respect to all the structural units contained in the shell layer, and the composite particles according to any one of <1> to <4>. <6> The acrylate ester in the first structural unit and the second structural unit is the composite particle according to any one of <1> to <5>, wherein the number of carbon atoms excluding the acryloyl group is 2 to 8. <7> The inorganic particles are the composite particles according to any one of <1> to <6>, which are at least one kind of particles of silica, carbon particles, and metal oxides. <8> A film member containing the composite particles according to any one of <1> to <7>. <9> The film member according to <8>, which has a colloidal crystal structure. <10> At least a part of the third structural unit forms a cyclic multimer structure, and the film member according to <8> or <9>.

Advantages of the Invention

[0011] According to one embodiment of the present invention, there are provided composite particles capable of producing a film member whose mechanical properties can be changed by irradiation with ultraviolet rays or the like, and a film member containing the composite particles.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a graph showing the chemical formula of silica fine particles 2 modified with a first polymer chain and a second polymer chain, and the results of a 1H-NMR spectrum for Example 2. [Figure 2] FIG. 2 is a graph showing the measurement results of the reflection spectrum before and after shearing for the elastomer films of Examples 1 to 4. [Figure 3]Figure 3 is a graph showing the measurement results of the reflectance spectra before and after shearing for the elastomer films of Examples 5 to 8. [Figure 4] Figure 4 shows the stress-strain curves during the stretching process for the elastomer films after shearing in Examples 1-3. [Figure 5] Figure 5 shows the stress-strain curves during the stretching process of the elastomer films after UV irradiation in Examples 1 to 3. [Figure 6] Figure 6 shows the stress-strain curves during the stretching process for the elastomer films after shearing in Examples 4-6. [Figure 7] Figure 7 shows the stress-strain curves during the stretching process of the elastomer films after UV irradiation in Examples 4-6. [Figure 8] Figure 8 shows the stress-strain curves during the stretching process for the elastomer films after shearing in Examples 2, 7, and 8. [Figure 9] Figure 9 shows the stress-strain curves during the stretching process for the elastomer films after UV irradiation in Examples 2, 7, and 8. [Figure 10] Figure 10 is a graph showing the measurement results of the reflectance spectra during the stretching process for the elastomer films of Examples 2, 7, and 8 after UV irradiation. [Figure 11] Figure 11 is a graph showing the relationship between pressure and reflected wavelength, derived from the stress-strain curves during the stretching process, for elastomer films after UV irradiation in Examples 2, 7, and 8. [Figure 12] Figure 12 shows the stress-strain curves during the stretching process for the elastomer film after shearing in Example 2, or for the elastomer film after UV irradiation with UV irradiation time adjusted from 3 minutes to 60 minutes. [Figure 13] Figure 13 shows the stress-strain curves during the stretching process of the elastomer film after UV irradiation, with the UV irradiation time adjusted to 120 minutes or 240 minutes in Example 2. [Figure 14] Figure 14 is a graph showing the measurement results of the reflectance spectra during the stretching process for the elastomer film after UV irradiation, with the UV irradiation time adjusted to 15 minutes, 30 minutes, or 60 minutes in Example 2. [Figure 15]Figure 15 is a graph showing the relationship between pressure and reflected wavelength derived from the stress-strain curve during the stretching process for elastomer films after UV irradiation, where the UV irradiation time was adjusted to 15 minutes, 30 minutes, or 60 minutes in Example 2. [Figure 16] Figure 16 shows the stress-strain curves during the stretching process (under a strain condition of 30% of the fracture strain) for the elastomer film after shearing in Example 2, or for the elastomer film after UV irradiation with UV irradiation time adjusted from 3 minutes to 60 minutes. [Figure 17] Figure 17 shows the stress-strain curves during the stretching process (under a strain condition of 30% of the fracture strain) of the elastomer film after UV irradiation, with the UV irradiation time adjusted to 120 minutes or 240 minutes in Example 2. [Figure 18] Figure 18 is a graph showing the change in the ultraviolet-visible absorption spectrum with respect to the ultraviolet irradiation time when the elastomer film of Example 2 was irradiated with ultraviolet light. [Figure 19] Figure 19 shows the stress-strain curves during the stretching process (under a strain condition of 30% of the fracture strain) of the elastomer films after UV irradiation in Examples 2, 7, and 8. [Figure 20] Figure 20 shows the stress-strain curves during the stretching process for the elastomer film after shearing in Example 7, or for the elastomer film after UV irradiation with UV irradiation time adjusted to 15 to 60 minutes. [Figure 21] Figure 21 shows the stress-strain curves during the stretching process for the elastomer film after shearing in Example 8, or for the elastomer film after UV irradiation with UV irradiation time adjusted to 15 to 60 minutes. [Figure 22] Figure 22 shows the stress-strain curves during the compression process for the elastomer films after shearing in Examples 1-3. [Figure 23] Figure 23 shows the stress-strain curves during the compression process in the elastomer films of Examples 1-3 after UV irradiation. [Figure 24] Figure 24 shows the stress-strain curves during the compression process for the elastomer films after shearing in Examples 4-6. [Figure 25] Figure 25 shows the stress-strain curves during the compression process in the elastomer films of Examples 4-6 after UV irradiation. [Figure 26] Figure 26 shows the stress-strain curves during the compression process for the elastomer films after shearing in Examples 2, 7, and 8. [Figure 27] Figure 27 shows the stress-strain curves during the compression process in the elastomer films after UV irradiation in Examples 2, 7, and 8. [Figure 28] Figure 28 is a graph showing the relationship between pressure and reflected wavelength, derived from the stress-strain curve during the compression process, for elastomer films after UV irradiation in Examples 2, 7, and 8. [Figure 29] Figure 29 is a graph showing the relationship between the time from the release of the compressive force and the reflected wavelength for the elastomer films after UV irradiation in Examples 2, 7, and 8. [Figure 30] Figure 30 shows the stress-strain curves during the compression process for the elastomer film after shearing in Example 2, or for the elastomer film after UV irradiation with UV irradiation time adjusted from 3 minutes to 60 minutes. [Figure 31] Figure 31 is a graph showing the relationship between pressure and reflected wavelength, derived from the stress-strain curve during the compression process, for elastomer films after UV irradiation, where the UV irradiation time was adjusted from 3 minutes to 60 minutes in Example 2. [Figure 32] Figure 32 is a graph showing the relationship between the time from release of compressive force and the reflected wavelength for the elastomer film after UV irradiation, where the UV irradiation time was adjusted from 3 minutes to 60 minutes in Example 2. [Figure 33] Figure 33 is a graph showing the measurement results of the reflectance spectrum after stretching for the elastomer film of Example 2. [Figure 34] Figure 34 is a graph showing the chemical formulas and 1H-NMR spectra of silica nanoparticles 9 modified with the first and second polymer chains for Example 9. [Figure 35] Figure 35 is a graph showing the measurement results of the reflectance spectra before and after shearing for the elastomer films of Examples 9 and 10. [Figure 36] Figure 36 is a graph showing the change in the ultraviolet-visible absorption spectrum when the elastomer film of Example 9 is irradiated with ultraviolet light. [Figure 37] Figure 37 is a graph showing the change in the fluorescence spectrum when the elastomer film of Example 9 is irradiated with ultraviolet light. [Figure 38] Figure 38 is a graph showing the results of frequency dispersion measurement when the elastomer film of Example 9 was irradiated with ultraviolet light. [Figure 39] Figure 39 shows the stress-strain curves during the stretching process for the elastomer film after shearing, or for the elastomer film after UV irradiation with UV irradiation time adjusted to 1 to 15 minutes, in Example 9. [Figure 40] Figure 40 shows the stress-strain curve during the stretching process (strain condition of 30% of fracture strain) for the elastomer film after shearing in Example 9 or for the elastomer film after UV irradiation with UV irradiation time adjusted to 1 to 15 minutes. [Figure 41] Figure 41 is a graph showing the change in the ultraviolet-visible absorption spectrum when the elastomer film of Example 9 is heated. [Figure 42] Figure 42 is a graph showing the change in the fluorescence spectrum when the elastomer film of Example 9 is heated. [Figure 43] Figure 43 is a graph showing the results of frequency dispersion measurements of the elastomer film of Example 9 or the heated elastomer film. [Figure 44] Figure 44 shows the stress-strain curves during the stretching process of the elastomer film after irradiation with ultraviolet light or after heating in Example 9. [Figure 45] Figure 45 shows the stress-strain curve during the stretching process (under a strain condition of 30% of the fracture strain) of the elastomer film after irradiation with ultraviolet light or after heating in Example 9. [Figure 46] Figure 46 is a graph showing the change in the ultraviolet-visible absorption spectrum when the elastomer film of Example 9 was irradiated with ultraviolet light before UV re-irradiation. [Figure 47] Figure 47 is a graph showing the change in the fluorescence spectrum when the elastomer film of Example 9 was irradiated with ultraviolet light before re-irradiation with UV light. [Figure 48]Figure 48 is a graph showing the results of frequency dispersion measurements of the elastomer film before UV re-irradiation or after UV re-irradiation in Example 9. [Figure 49] Figure 49 shows the stress-strain curves during the stretching process in the elastomer film before UV re-irradiation or after UV re-irradiation in Example 9. [Figure 50] Figure 50 shows the stress-strain curves during the stretching process (under a strain condition of 30% of the fracture strain) for the elastomer film before UV re-irradiation or after UV re-irradiation in Example 9. [Figure 51] Figure 51 shows the stress-strain curves during the stretching process for the elastomer film after shearing in Example 10, or for the elastomer film after UV irradiation with UV irradiation time adjusted to 0.25 to 15 minutes. [Figure 52] Figure 52 shows the stress-strain curve during the stretching process (strain condition of 30% of fracture strain) for the elastomer film after shearing in Example 10 or for the elastomer film after UV irradiation with UV irradiation time adjusted to 0.25 to 15 minutes. [Figure 53] Figure 53 shows the stress-strain curves during the stretching process (under a strain condition of 30% of the fracture strain) for the elastomer film after heat treatment (1st to 3rd time) or after UV irradiation (1st to 3rd time) of Example 10. [Figure 54] Figure 54 is a graph showing the measurement results of the reflectance spectra before and after shearing for the elastomer films of Examples 11 and 12. [Figure 55] Figure 55 shows the stress-strain curves during the stretching process for the elastomer film after shearing, or for the elastomer film after UV irradiation with an adjusted UV irradiation time of 60 minutes, in Examples 9, 11, and 12. [Figure 56] Figure 56 shows the stress-strain curves during the stretching process (strain condition of 30% of fracture strain) for the elastomer films after shearing in Examples 9, 11, and 12, or for the elastomer films after UV irradiation with an adjusted UV irradiation time of 60 minutes. [Figure 57]Figure 57 is a graph showing the change in the ultraviolet-visible absorption spectrum when the elastomer films of Examples 11 and 12 are irradiated with ultraviolet light. [Figure 58] Figure 58 is a graph showing the changes in the fluorescence spectra when the elastomer films of Examples 11 and 12 were irradiated with ultraviolet light. [Figure 59] Figure 59 is a graph showing the changes in the fluorescence spectra when the elastomer films of Examples 11 and 12 were heated. [Modes for carrying out the invention]

[0013] In this disclosure, the "~" symbol indicating a numerical range is used to mean that the numbers before and after it are included as the lower and upper limits, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. In this disclosure, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, it means the total amount of all multiple components present in the composition unless otherwise specified. Compounds that are not specified as substituted or unsubstituted in this disclosure may have any substituents, as long as they do not impair the effects described in this disclosure. In this disclosure, a preferred combination of embodiments is a more preferred embodiment. In this disclosure, two or more preferred embodiments may be combined in any combination.

[0014] <Composite particles> The composite particles of this disclosure comprise an inorganic particle and a shell layer comprising a first polymer chain located on the surface of the inorganic particle and containing a plurality of first constituent units derived from an acrylic acid ester, and a second polymer chain containing a second constituent unit derived from an acrylic acid ester and a third constituent unit having a structure capable of forming a cyclic polymer structure by irradiation with active energy rays, wherein the first polymer chain and the second polymer chain are arranged in that order when viewed from the inorganic particle side.

[0015] The composite particles of this disclosure have a shell layer on the surface of an inorganic particle, the shell layer containing a first nopolymer chain and a second polymer chain. In a film-like member formed from composite particles comprising inorganic particles covered with a shell layer containing these polymer chains, a three-dimensional structure (e.g., a colloidal crystal structure) is maintained by the entanglement of the polymer chains.

[0016] Furthermore, the shell layer in the composite particles of this disclosure includes a second polymer chain containing a third constituent unit having a structure capable of forming a cyclic polymer structure by irradiation with active energy rays. As a result, a cyclic polymer structure is formed when an active energy ray, such as ultraviolet light, is irradiated onto a film-like member formed from the composite particles. This changes the mechanical properties of the film-like member before and after irradiation with active energy rays. Furthermore, the proportion of the formed cyclic polymer structure can be adjusted by changing conditions such as the irradiation intensity and duration of the active energy rays. Therefore, the mechanical properties of the film-like member can be changed depending on the irradiation conditions of the active energy rays.

[0017] (Inorganic particles) The composite particles of this disclosure comprise inorganic particles. The inorganic particles are not particularly limited as long as the shell layer can be a core particle located on the surface.

[0018] The inorganic particles are preferably at least one of silica, carbon particles, and metal oxide particles. The carbon particles are not particularly limited as long as they contain carbon, and examples include graphite and carbon black. The metal oxides are not particularly limited, and examples include alumina, titanium oxide, zinc oxide, tantalum pentoxide, niobium pentoxide, indium tin oxide, cerium oxide, yttrium oxide, chromium oxide, zirconium oxide, magnesium oxide, and nickel oxide. From the viewpoint of increasing the reflectivity of light and improving the visibility of reflected light, it is preferable that the inorganic particles have a high refractive index, and titanium dioxide is preferred as an example.

[0019] The average particle size of the inorganic particles may be 1 nm to 10 μm, 10 nm to 10 μm, 50 nm to 10 μm, or 100 nm to 10 μm. The average particle size of the inorganic particles may be 10 nm to 1 μm, 30 nm to 500 nm, or 50 nm to 200 nm. In this disclosure, the average particle size refers to the volume-average particle diameter, which can be measured, for example, using a dynamic light scattering (DLS) particle size distribution analyzer (product number; UPA-UT151, manufactured by Nikkiso Co., Ltd.) under conditions where the temperature of the particle diameter is adjusted to 25°C.

[0020] (Shell layer) The composite particles of this disclosure are located on the surface of inorganic particles and comprise a shell layer covering the inorganic particles. The shell layer comprises a first polymer chain and a second polymer chain. The first polymer chain comprises a plurality of first structural units derived from acrylic acid esters. The second polymer chain comprises a second structural unit derived from acrylic acid esters and a third structural unit having a structure capable of forming a cyclic polymer structure by irradiation with active energy rays.

[0021] Examples of acrylic acid esters constituting the first or second constituent unit include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, tert-octyl acrylate, isobornyl acrylate, lauryl acrylate, myristyl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-n-butoxyethyl acrylate, methoxytriethylene glycol acrylate, oligoethylene glycol acrylate (e.g., n=8-9), methoxypolyethylene glycol acrylate, methoxytripropylene glycol acrylate, methoxypolypropylene glycol acrylate, fluoroalkyl acrylate, and others.

[0022] The first polymer chain may contain multiple first structural units derived from acrylic acid esters, and the first structural unit may be one type or two or more types. If the first polymer chain contains two or more types of structural units, the first polymer chain may be a random copolymer or a block copolymer.

[0023] The acrylic acid ester in the first structural unit may have 2 to 8 carbon atoms excluding the acryloyl group, 2 to 6 carbon atoms excluding the acryloyl group, or 4 to 6 carbon atoms excluding the acryloyl group.

[0024] The first polymer chain may contain structural units other than the first structural unit, i.e., structural units derived from sources other than acrylic acid esters. Examples of structural units derived from sources other than acrylic acid esters include: acrylic acid; isocyanate group-containing acrylates such as 2-isocyanate ethyl acrylate; nitrogen-containing acrylates such as N,N-dimethylaminoethyl acrylate and Nt-butylaminoethyl acrylate; amide group-containing monomers such as acrylamide and N-isopropylacrylamide; styrene monomers such as styrene, p-methylstyrene, α-methylstyrene, 2-vinylnaphthalene, and p-methoxystyrene; unsaturated carboxylic acid monomers such as crotonic acid; maleic acid, fumaric acid. Examples include unsaturated dicarboxylic acid monomers such as itaconic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; fumarate ester monomers such as dimethyl fumarate and dicyclohexyl fumarate; isocyanate group-containing monomers such as m-isopropenyl-α,α-dimethylbenzyl isocyanate; aromatic nitrogen-containing monomers such as 2-vinylpyridine and 4-vinylpyridine; conjugated diene monomers such as butadiene, isoprene, and chloroprene; vinyl ester monomers such as vinyl acetate; and vinylpyrrolidone, vinylcarbazole, and acrylonitrile.

[0025] The content of the first constituent unit may be 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol% relative to the total constituent units contained in the first polymer chain. The upper limit of the content of the first constituent unit is not particularly limited and may be 100 mol% or less, or 95 mol% or less, relative to the total constituent units contained in the first polymer chain.

[0026] The second polymer chain includes a second structural unit derived from an acrylic acid ester and a third structural unit having a structure capable of forming a cyclic polymer structure upon irradiation with active energy rays.

[0027] The second polymer chain may independently contain multiple second or third structural units. The second or third structural units may independently consist of one type or two or more types. The second polymer chain may be a random copolymer or a block copolymer.

[0028] The acrylic acid ester in the second structural unit may have 2 to 8 carbon atoms excluding the acryloyl group, 2 to 6 carbon atoms excluding the acryloyl group, or 4 to 6 carbon atoms excluding the acryloyl group.

[0029] The content of the second constituent unit may be 50 mol% or more, 70 mol% or more, 90 mol% or more, or 98 mol% or more, relative to the total constituent units contained in the second polymer chain. There is no particular upper limit to the content of the second constituent unit; it may be less than 100 mol% or 99.9 mol% or less relative to the total constituent units contained in the second polymer chain.

[0030] The third constituent unit has a structure capable of forming a cyclic polymer structure upon irradiation with active energy rays. Furthermore, the third constituent unit may also include a structure derived from an acrylic acid ester.

[0031] Examples of active energy rays include alpha rays, gamma rays, electron beams, X-rays, ultraviolet rays, visible light, and infrared light. Among these, ultraviolet rays are preferred as the active energy ray.

[0032] Examples of structures capable of forming cyclic polymer structures by irradiation with active energy rays include coumarin skeletons, anthracene skeletons, thymine skeletons, styrylpyrene skeletons, and cinnamic acid skeletons.

[0033] The third constituent unit may be a constituent unit derived from an acrylic acid ester having a coumarin skeleton, anthracene skeleton, thymine skeleton, styrylpyrene skeleton, or cinnamic acid skeleton, or it may be a constituent unit derived from an acrylic acid ester having a coumarin skeleton or anthracene skeleton. The third constituent unit may be a constituent unit derived from an acrylic acid ester represented by the following chemical formula (a), or it may be a constituent unit derived from an acrylic acid ester represented by the following chemical formula (b).

[0034] [ka]

[0035] In chemical formulas (a) and (b), R1 and R2 are divalent linking groups. Examples of R1 and R2 include alkylene groups, alkoxy groups, polyalkoxy groups, etc. R1 may, for example, be bonded to a carbon atom at position 4, 6, or 7 in the coumarin skeleton. R2 may, for example, be bonded to the carbon atom at position 9 in the anthracene skeleton.

[0036] For R2, it may be a group represented by the following general formula (X).

[0037] [ka]

[0038] In general formula (X), R3 is an alkylene group, Y is a single bond or an oxygen atom, and R4 is a single bond or an alkylene group. The alkylene group in R3 may have 1 to 10 carbon atoms or 2 to 6 carbon atoms. The alkylene group in R4 may have 1 to 5 carbon atoms or 1 to 3 carbon atoms.

[0039] For example, with coumarin compounds, a dimerization reaction proceeds when irradiated with ultraviolet light of 300 nm or higher, as shown below, and a cleavage reaction proceeds when irradiated with deep ultraviolet light of less than 300 nm. Note that the position of R is just an example and is not limited to this.

[0040] [ka]

[0041] As shown below, anthracene compounds undergo a dimerization reaction when irradiated with ultraviolet light of 300 nm or higher, and a cleavage reaction when irradiated with deep ultraviolet light of less than 300 nm or when heated. Note that the position of R is just an example and is not limited to this.

[0042] [ka]

[0043] When the second polymer chain in the composite particles of this disclosure contains a constituent unit derived from an acrylic acid ester represented by chemical formula (a) or a constituent unit derived from an acrylic acid ester represented by chemical formula (b), the above-described dimerization reaction proceeds when irradiated with active energy such as ultraviolet light. At this time, a ring structure is formed between the two second polymer chains, and as a result, the mechanical properties of the film-like member (e.g., Young's modulus, maximum point stress, etc.) change. Furthermore, since the rate of progress of the dimerization reaction can be adjusted by adjusting the irradiation conditions of the active energy ray, such as wavelength, irradiation intensity, and irradiation time, it is also possible to adjust the mechanical properties of the film-like member.

[0044] Furthermore, coumarin compounds undergo a cleavage reaction when irradiated with deep ultraviolet light below 300 nm. Therefore, for structures capable of forming a cyclic polymer structure by irradiation with active energy rays, the cyclic polymer structure can be cleaved by irradiation with active energy rays of a lower wavelength than those mentioned above. This allows the reaction for forming the cyclic polymer structure and the cleavage reaction to proceed reversibly, making it possible to return the film-like member after irradiation to its state before irradiation, and also making it possible to change the mechanical properties of the film-like member after irradiation. As a result, the composite particles of this disclosure and the film-like members formed using them can be reused.

[0045] On the other hand, for anthracene compounds, a cleavage reaction proceeds by irradiation with deep ultraviolet light less than 300 nm or by heating. When the second polymer chain in the composite particles of this disclosure contains a constituent unit derived from an acrylic acid ester represented by chemical formula (b), the above-described dimerization reaction proceeds by irradiation with active energy such as ultraviolet light. Furthermore, the cyclic polymer structure formed by heating the composite particles after the dimerization reaction has proceeded is easily cleaved. As a result, the reaction that forms the cyclic polymer structure by irradiation with active energy rays and the cleavage reaction by heating proceed reversibly. For film-like members whose mechanical properties have changed due to the formation of a cyclic polymer structure by irradiation with active energy rays, it is possible to return them to the state before irradiation with active energy rays, and it may also be possible to change the mechanical properties. Furthermore, even if the reaction that forms the cyclic polymer structure by irradiation with active energy rays and the reaction that cleaves the cyclic polymer structure by heating are repeated, the mechanical properties of the film-like member are easily maintained, making it easy to reuse.

[0046] The content of the third constituent unit may be 0.010 mol% to 2.0 mol%, 0.012 mol% to 2.0 mol%, 0.15 mol% to 1.5 mol%, or 0.20 mol% to 1.0 mol% relative to the total constituent units contained in the shell layer. The content of the third constituent unit is, for example, 1This can be determined by measuring the 1H-NMR spectrum and calculating the ratio between the peak of protons contained only in the third constituent unit and the peak of protons contained in constituent units other than the third constituent unit but not in the third constituent unit.

[0047] The second polymer chain may contain structural units other than the second or third structural units. These structural units may include: acrylic acid; isocyanate group-containing acrylates such as 2-isocyanate ethyl acrylate; nitrogen-containing acrylates such as N,N-dimethylaminoethyl acrylate and Nt-butylaminoethyl acrylate; amide group-containing monomers such as acrylamide and N-isopropylacrylamide; styrene monomers such as styrene, p-methylstyrene, α-methylstyrene, 2-vinylnaphthalene, and p-methoxystyrene; unsaturated carboxylic acid monomers such as crotonic acid; maleic acid, fumaryl methyl acrylate. Examples include unsaturated dicarboxylic acid monomers such as acids and itaconic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; fumarate ester monomers such as dimethyl fumarate and dicyclohexyl fumarate; isocyanate group-containing monomers such as m-isopropenyl-α,α-dimethylbenzyl isocyanate; aromatic nitrogen-containing monomers such as 2-vinylpyridine and 4-vinylpyridine; conjugated diene monomers such as butadiene, isoprene, and chloroprene; vinyl ester monomers such as vinyl acetate; and vinylpyrrolidone, vinylcarbazole, and acrylonitrile.

[0048] Composite particles, which are core-shell particles, can be manufactured by, for example, graft polymerization from core particles having atom transfer radical polymerization (ATRP) initiators (Method 1), reacting functional groups at the ends of polymer chains with the surface of core particles (Method 2), or particle synthesis using macromonomers as comonomers (Method 3). Method 1 is preferred because it allows for the formation of high-density graft chains, the use of various monomers in the graft chains, and the free design of the molecular weight of the graft chains.

[0049] When producing core particles having an ATRP initiator, known methods can be employed and are not particularly limited. For example, one method involves reacting a compound having an ATRP initiator (such as a silane coupling agent having an ATRP initiator) with the functional groups on the surface of the core particles.

[0050] In the composite particles of this disclosure, a structure represented by the following general formula (1) may be bonded to the surface of an inorganic particle, and the inorganic particle and the polymer chain may be bonded via the structure represented by general formula (1). The structure represented by general formula (1) can be formed by the reaction of a living radical polymerization initiator with an acrylic monomer.

[0051] [ka]

[0052] In general formula (1), n ​​is an integer between 3 and 10, and R1 is a methyl group or an ethyl group, * *1 is an independent bonding position with the inorganic particle or a bonding position with an alkoxy group having 1 to 3 carbon atoms, and *2 is a bonding position with the polymer chain.

[0053] <Membrane material> The film-like member of this disclosure includes the composite particles of this disclosure as described above. For example, the film-like member may be a molded product formed by molding the composite particles of this disclosure using a hot press or the like.

[0054] The film-like member of this disclosure preferably has a colloidal crystal structure. Having a colloidal crystal structure exhibits structural color due to Bragg reflection of light by a three-dimensional periodic structure. For example, when a shear force is applied to a film-like member formed from composite particles, the composite particles having polymer chains may be oriented to form a colloidal crystal structure. The structural color due to Bragg reflection of light can be adjusted by changing, for example, the material of the inorganic particles, the particle size of the inorganic particles, the molecular weight of the polymer chains, and the proportion of each constituent unit of the polymer chains. The mechanical properties of the film-like member can be adjusted by changing the molecular weight of the first polymer chain, the molecular weight of the second polymer chain, and the content of the third constituent unit.

[0055] In the film-like member of this disclosure, at least a portion of the third constituent unit contained in the shell layer may form a cyclic polymer structure. The formation of a cyclic polymer structure tends to improve the mechanical properties of the film-like member.

[0056] Examples of cyclic polymer structures include the following structural formula (c) or structural formula (d).

[0057] [ka]

[0058] [ka]

[0059] In structural formula (c), * indicates a bond position. In structural formula (d), *1 to *4 represent candidate bond locations, where only one of *1 or *2 is an actual bond location, and only one of *3 or *4 is an actual bond location.

[0060] The proportion of the cyclic polymer structure can be adjusted by controlling the irradiation conditions of the active energy ray, such as wavelength, irradiation intensity, and irradiation time. A film-like member in which at least a portion of the third constituent units contained in the shell layer form a cyclic polymer structure can be formed, for example, by irradiating the film-like member with active energy rays.

[0061] Examples of active energy rays irradiated onto a film-like material include alpha rays, gamma rays, electron beams, X-rays, ultraviolet rays, visible light, and infrared light. Among these, ultraviolet rays are preferred as the active energy ray. If the active energy ray is ultraviolet light, the wavelength of the ultraviolet light may be, for example, 300 nm to 400 nm, or 320 nm to 380 nm.

[0062] The film-like member of this disclosure changes its structural color due to Bragg reflection of light by stretching, compression, etc., and the change in structural color can be adjusted by changing the conditions of the inorganic particles, polymer chains, etc. that constitute the film-like member, or by changing the irradiation conditions of active energy rays. For this reason, the film-like member of this disclosure can be applied to strain visualization sheets that can withstand various pressures, pressure sensors, etc. Furthermore, since the cyclic polymer structure of the film-like member of this disclosure undergoes cleavage upon heating, the film-like member can also be applied as a heating sensor. [Examples]

[0063] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the spirit of the invention.

[0064] [Example 1] Silica microparticles with an average particle size of 120 nm were prepared. An aqueous dispersion of the silica microparticles was centrifuged, and the silica microparticles were redispersed in ethanol. This procedure was repeated three times to prepare 25.0 g of ethanol suspension containing 10% by mass of silica microparticles. A solution of 15.4 mL of 28% aqueous ammonia and 175 mL of ethanol was added dropwise to a round-bottom flask containing 25.0 g of the silica microparticle ethanol suspension, and the mixture was stirred in an oil bath at 40°C for 2 hours. Subsequently, a solution of 10.0 mL of ethanol and 2.00 g of a silane coupling agent having an atomic transfer radical polymerization (ATRP) initiator (6-(trimethoxysilyl)hexyl 2-bromo-2-methylpropanoate) was added dropwise to this round-bottom flask, and the mixture was stirred at 40°C for 18 hours. This mixture was then centrifuged, and the precipitate was redispersed in ethanol. This procedure was repeated three times to prepare 25.0 g of ethanol suspension containing 10% by mass of silica microparticles. This resulted in the fabrication of silica nanoparticles (SiP-Br) having an ATRP initiation group represented by the following formula (1a) on their surface. In formula (1a), *1 independently represents the bonding site to the silica nanoparticle or the bonding site to the methoxy group.

[0065] [ka]

[0066] (Preparation of silica nanoparticles 1A modified with the first polymer chain) Next, 0.3 g of ethanol suspension of silica nanoparticles having an ATRP initiator (calculated as silica nanoparticles), 15.0 g of n-butyl acrylate (BA), 2.63 mg of polymerization initiator ethyl 2-bromoisobutyrate (EBIB), 16.6 mg of tris[2-(dimethylamino)ethyl]amine (Me6TREN), and 4.2 mg of copper(II) bromide were added to the flask, and nitrogen bubbling was carried out for 30 minutes. Then, 7.3 mg of copper(I) bromide was added, followed by nitrogen bubbling for 10 minutes, and the mixture was heated and stirred in an aluminum bead bath at 70°C for 5.7 hours. After bubbling the reaction solution with air at room temperature, it was purified by centrifugation or the like to obtain silica nanoparticles 1A (SiP-PBA1) modified with a first polymer chain consisting of constituent units derived from BA.

[0067] (Preparation of silica nanoparticles 1 modified with the first polymer chain and the second polymer chain) As described above, SiP-PBA1 was polymerized with n-butyl acrylate (BA) and an acrylic acid ester (6AOCM) having a coumarin skeleton represented by the following chemical formula to produce silica nanoparticles modified with a first polymer chain consisting of structural units derived from BA and a second polymer chain consisting of structural units derived from BA and structural units derived from 6AOCM. First, 0.627 g of SiP-PBA1, 5.57 g of BA, 182 mg of 6AOCM, 1.77 mg of EBIB, 10.9 mg of Me6TREN, and 3.3 mg of copper(II) bromide were added to a flask, and nitrogen bubbling was carried out for 30 minutes. Then, 6.3 mg of copper(I) bromide was added, followed by nitrogen bubbling for 10 minutes, and the polymerization reaction was carried out at 70°C for 2 hours. After that, tributyltin hydride was added to the reaction solution and the reaction was carried out at 70°C for 1 hour. After bubbling the reaction solution with air at room temperature, the mixture was centrifuged to produce silica nanoparticles (SiP-PBA1-b-(PBA1-r-P6AOCM)) modified with a b-(PBA1-r-P6AOCM) chain (second polymer chain) relative to SiP-PBA1.

[0068] [ka]

[0069] [Examples 2-8] (Preparation of silica nanoparticles 2A-5A modified with the first polymer chain) In Example 1 (Preparation of silica nanoparticles 1A modified with the first polymer chain), silica nanoparticles 2A to 5A (SiP-PBA2 to SiP-PBA5) modified with the first polymer chain were obtained in the same manner as in Example 1, except that the amounts of each reagent used and the polymerization conditions were changed as shown in Table 1.

[0070] [Table 1]

[0071] (Preparation of silica nanoparticles 2-8 modified with the first and second polymer chains) In Example 1 (Preparation of silica nanoparticles 1 modified with the first and second polymer chains), silica nanoparticles 2 to 8, which are Examples 2 to 8, were obtained in the same manner as in Example 1, except that the amounts of each reagent used and the polymerization conditions were changed as shown in Table 2.

[0072] [Table 2]

[0073] (Molecular weight of polymer chains) In Examples 1-8, the number-average molecular weight (Mn) of the polymer chain was determined by SEC (Size Exclusion Chromatography). Polystyrene was used as the standard substance for molecular weight conversion, and a 10 mM lithium bromide (LiBr) N,N-dimethylformamide solution was used as the eluent. A first or second polymer chain was synthesized using ethyl 2-bromoisobutyrate (EBIB) as the initiator under the same synthesis conditions as in Examples 1-8, except that silica nanoparticles were not used. The number-average molecular weight (Mn) of the first polymer chain was then determined. n,1 ) or the number-average molecular weight (M) of the second polymer chain n,2 Measurements were taken. The results are shown in Table 3.

[0074] (polymer chains) 1 (H-NMR spectrum) In Examples 1 to 8, 1 The content of constituent units derived from 6AOCM (corresponding to the third constituent unit) relative to the total constituent units of the first and second polymer chains contained in the shell layer of silica nanoparticles was determined from the results of the H-NMR spectrum (solvent: deuterated chloroform). Specifically, the content of constituent units derived from 6AOCM (φ cou (%) was determined based on the following formula (1). For Example 2, the chemical formulas of silica nanoparticles 2 modified with the first polymer chain and the second polymer chain, and 1 The results of the 1H-NMR spectrum are shown in Figure 1. In equation (1), S1 is the integral value of peak a in Figure 1, and S2 is the sum of the integral values ​​of peaks b to f in Figure 1. For Examples 1 and 3 to 7, the polymer chain was analyzed in the same manner as in Example 2. 1 The 1H-NMR spectrum was measured. The results are shown in Table 3.

[0075]

number

[0076] [Table 3]

[0077] (Measurement of reflectance spectrum) Silica microparticles 1-8, modified with the first and second polymer chains of Examples 1-8, were hot-pressed at 150°C to form discs with a diameter of approximately 25 mm and a thickness of approximately 500 μm. This produced disc-shaped elastomer films. Vibrational shear strain was applied to a disc-shaped elastomer film using a rheometer's parallel plate jig under the following conditions. This resulted in the fabrication of the elastomer film after shearing. -Conditions for applying vibrational shear strain- Fixture diameter: 25 mm Model: MCR102 type (Anton Paar) Temperature: 150 °C Frequency: 0.1 Hz Load: 8 N Strain: 100% Impression time: 10 min

[0078] The reflection spectra before and after shearing were measured using the elastomer film before shearing and the elastomer film after shearing. The results are shown in FIGS. 2 and 3. (1) to (8) in FIGS. 2 and 3 respectively correspond to the reflection spectra of the elastomer films of Examples 1 to 8 in order,

[0079] As shown in FIGS. 2 and 3, the elastomer films of Examples 1 to 8 exhibited a reflected color due to shearing. The reason for the exhibited reflected color is presumably because silica fine particles having polymer chains were oriented in the elastomer film to form a colloidal crystal structure by applying vibration shear strain.

[0080] (UV irradiation 1) The elastomer films after shearing of Examples 1 to 8 were irradiated with ultraviolet light having a wavelength of 365 nm at an intensity of 120 mW / cm 2 under the conditions of 60 minutes. Thereby, an elastomer film after ultraviolet irradiation was obtained.

[0081] (Stress measurement by stretching 1) In order to confirm the influence of the molecular weight of the first polymer chain on the elastomer film, stress measurements by stretching were performed on the elastomer films after shearing and the elastomer films after ultraviolet irradiation in Examples 1 to 3. The results are shown in FIGS. 4, FIGS. 5 and Table 4.

[0082]

Table 4

[0083] For the elastomer films after shearing and the elastomer films after ultraviolet irradiation, the number average molecular weight (M n,1The fracture strain increased as the number average molecular weight (M) of the first polymer chain increased. Furthermore, for the elastomer film after UV irradiation, the number average molecular weight (M) of the first polymer chain was also increased. n,1 As the ratio increased, the Young's modulus decreased. This is presumed to be because the proportion of the flexible first polymer chain increased relative to the sum of the first and second polymer chains. From the above results, the number-average molecular weight (M) of the first polymer chain n,1 By adjusting the following, the fracture strain of the elastomer film before and after UV irradiation, and the Young's modulus of the elastomer film after UV irradiation could be adjusted.

[0084] (Stress measurement by stretching 2) To confirm the effect of the molecular weight of the second polymer chain on the elastomer film, stress measurements were performed by stretching on the elastomer films after shearing and after UV irradiation in Examples 4 to 6. The results are shown in Figures 6 and 7 and Table 5.

[0085] [Table 5]

[0086] Regarding the elastomer film after shearing, the number-average molecular weight (M) of the second polymer chain n,2 The stress at the maximum point increased as the coefficient of ) increased. This is presumed to be because the constituent units derived from 6AOCM function as rigid parts. Regarding the elastomer film after UV irradiation, the number-average molecular weight (M) of the second polymer chain n,2 The maximum point stress increased as the number-average molecular weight of the second polymer chain increased. This is presumed to be because the larger the number-average molecular weight of the second polymer chain, the greater the proportion of coumarin moieties dimerized by UV irradiation, and thus the greater the number of crosslinking points.

[0087] (Stress measurement by stretching 3) To confirm the effect of the proportion of constituent units derived from 6AOCM in the second polymer chain on the elastomer film, stress measurements were performed by stretching on the elastomer films after shearing and after UV irradiation in Examples 2, 7, and 8. The results are shown in Figures 8, 9, and Table 6.

[0088] [Table 6]

[0089] Regarding the elastomer film after shearing, the content of constituent units derived from 6AOCM (φ cou No particular correlation was found between the percentage (%) and the stress at the maximum point. Regarding the elastomer film after UV irradiation, the content of constituent units derived from 6AOCM (φ cou A tendency was observed where the maximum point stress increased as (%) increased. The reason for this is φ cou It is presumed that a higher percentage (%) indicates a greater proportion of coumarin moieties dimerized by UV irradiation, resulting in an increase in crosslinking points.

[0090] (Measurement of reflectance spectrum during stretching process 1) The reflectance spectra of the elastomer films in Examples 2, 7, and 8 were measured while stretching after irradiation with ultraviolet light for 60 minutes. The results are shown in Figure 10. In Figure 10, (1) was performed. In Example 2, (2) is Example 7 and (3) is Example 8. As shown in Figure 10, stretching caused the reflection peak to continuously shift towards shorter wavelengths, changing the reflection color from yellow-green to blue. For the elastomer films after UV irradiation in Examples 2, 7, and 8, the strain was converted to pressure from the stress-strain curve during the stretching process, and the reflected wavelength was plotted against the pressure. The results are shown in Figure 11. It was confirmed that the pressure required to change the reflection wavelength to a similar level varies depending on the composition of the second polymer chain.

[0091] (UV irradiation 2) The effect of changing the UV irradiation time on the elastomer film was investigated. Specifically, the elastomer film after shearing in Example 2 was exposed to UV light with a wavelength of 365 nm at an intensity of 120 mW / cm². 2 The samples were irradiated under conditions ranging from 3 minutes to 240 minutes. This resulted in obtaining an elastomer film after UV irradiation.

[0092] (Stress measurement by stretching 4) In Example 2, stress measurements were performed on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation times adjusted from 3 minutes to 240 minutes. The results are shown in Figures 12 and 13 and Table 7.

[0093] [Table 7]

[0094] As shown in Table 7, the maximum point stress increased with increasing UV irradiation time. This is presumed to be because UV irradiation promoted the dimerization reaction of the coumarin moiety, increasing the number of crosslinking points.

[0095] (Measurement of reflectance spectrum during stretching process 2) The reflectance spectrum of the elastomer film after UV irradiation in Example 2 was measured while stretching. The results are shown in Figure 14. In Figure 14, (1) is after 15 minutes of UV irradiation, (2) is after 30 minutes of UV irradiation, and (3) is after 60 minutes of UV irradiation. As shown in Figure 14, stretching caused the reflection peak to continuously shift towards shorter wavelengths, changing the reflection color from yellow-green to blue. For the elastomer film after UV irradiation in Example 2, the strain was converted to pressure from the stress-strain curve during the stretching process, and the reflected wavelength was plotted against the pressure. The results are shown in Figure 15. It was confirmed that the pressure required to change the reflected wavelength to a similar level varies depending on the ultraviolet irradiation time.

[0096] (Stress measurement during the stretching-releasing process 1) In Example 2, stress measurements were performed during the stretch-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation times adjusted from 3 minutes to 240 minutes. These stress measurements were performed at a strain of 30% of the fracture strain. The results are shown in Figures 16 and 17 and Table 8.

[0097] [Table 8]

[0098] As shown in Table 8, the maximum point stress tended to increase and the hysteresis loss rate to decrease as the UV irradiation time increased. This is presumed to be because UV irradiation promoted the dimerization reaction of the coumarin moiety, increasing the number of crosslinking points. Furthermore, the change in the ultraviolet-visible absorption spectrum with respect to the ultraviolet irradiation time when the elastomer film of Example 2 was irradiated with ultraviolet light was measured. The results are shown in Figure 18. It was confirmed that the peaks originating from the coumarin skeleton decreased upon ultraviolet irradiation. Based on these results, it was found that the mechanical properties of the elastomer film could be adjusted by controlling the UV irradiation time.

[0099] (Stress measurement during the stretching-releasing process 2) In Examples 2, 7, and 8, stress measurements were performed on elastomer films after UV irradiation with an adjusted UV irradiation time of 60 minutes, during the stretch-release process. These stress measurements were performed at a strain of 30% of the fracture strain. The results are shown in Figure 19 and Table 9.

[0100] [Table 9]

[0101] As shown in Table 9, the content of the constituent units derived from 6AOCM in the elastomer film after UV irradiation (φ cou As (%) increased, the maximum point stress increased and the hysteresis loss rate decreased. The reason for this is φ couIt is presumed that a higher percentage (%) indicates a greater proportion of coumarin moieties dimerized by UV irradiation, resulting in an increase in crosslinking points.

[0102] (UV irradiation 3) The effect of changing the UV irradiation time on the elastomer film was investigated. Specifically, the elastomer film after shearing in Example 7 or Example 8 was exposed to UV light with a wavelength of 365 nm at an intensity of 120 mW / cm². 2 The irradiation was performed under conditions ranging from 15 to 60 minutes. This resulted in obtaining an elastomer film after UV irradiation.

[0103] (Stress measurement by stretching 5) In Example 7 or Example 8, stress measurements were performed on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation time adjusted to 15 to 60 minutes. The results are shown in Figures 20 and 21 and Table 10.

[0104] [Table 10]

[0105] As shown in Table 10, the maximum point stress tended to increase with increasing UV irradiation time. This is presumed to be because UV irradiation promoted the dimerization reaction of the coumarin moiety, increasing the number of crosslinking points.

[0106] (Measurement of swelling rate) The swelling rate of the elastomer film was determined when the UV irradiation time was changed. Specifically, the elastomer film after shearing in Example 2 (before in Table 11) or the elastomer film after UV irradiation was immersed in the solvent N,N-dimethylformamide for 6 hours, 1 day, 3 days, 5 days, 7 days, or 15 days, and the swelling rate (%) was calculated based on the following formula. The results are shown in Table 11. Swelling rate (%) = (Mass of elastomer film after immersion / Mass of elastomer film before immersion) × 100

[0107] [Table 11]

[0108] As shown in Table 11, the average swelling rate tended to decrease as the UV irradiation time increased. This is presumed to be because UV irradiation promoted the dimerization reaction of the coumarin moiety, increasing the number of crosslinking sites.

[0109] (Stress measurement during compression-release process 1) In Examples 1 to 3, stress measurements were performed during the compression-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with an adjusted UV irradiation time of 60 minutes. The results are shown in Figures 22 and 23 and Table 12.

[0110] [Table 12]

[0111] As shown in Table 12, for the elastomer film after UV irradiation, the number average molecular weight (M) of the first polymer chain is n,1 As the coefficient of force () increases, the stress at the maximum point decreases, yielding results similar to those obtained during the stretching process.

[0112] (Stress measurement during compression-release process 2) In Examples 4-6, stress measurements were performed during the compression-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with an adjusted UV irradiation time of 60 minutes. The results are shown in Figures 24 and 25 and Table 13.

[0113] [Table 13]

[0114] As shown in Table 13, the number average molecular weight (M) of the second polymer chain was determined for the elastomer film after shearing and the elastomer film after UV irradiation. n,2 As the coefficient of force () increased, the stress at the maximum point increased, yielding results similar to those obtained during the stretching process.

[0115] (Stress measurement during compression-release process 3) In Examples 2, 7, and 8, stress measurements were performed during the compression-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with an adjusted UV irradiation time of 60 minutes. The results are shown in Figures 26, 27, and Table 14.

[0116] [Table 14]

[0117] As shown in Table 14, the content of constituent units derived from 6AOCM (φ) of the elastomer film after shearing and the elastomer film after UV irradiation. cou As the (%) increases, the stress at the maximum point increases, yielding results similar to those obtained during the stretching process.

[0118] The reflectance spectra of the elastomer films in Examples 2, 7, and 8, after irradiation with ultraviolet light for 60 minutes, were measured while the films were compressed. Next, for the elastomer films after UV irradiation in Examples 2, 7, and 8, the strain was converted to pressure from the stress-strain curve during the compression process, and the reflected wavelength was plotted against the pressure. The results are shown in Figure 28. It was confirmed that the pressure required to change the reflection wavelength to a similar level varies depending on the composition of the second polymer chain.

[0119] The reflectance spectra of the elastomer films in Examples 2, 7, and 8, after 60 minutes of UV irradiation, were measured while releasing the compressive force. The reflected wavelength was plotted against the time from the release of the compressive force. The results are shown in Figure 29. The change in reflected wavelength after the release of the compressive force is due to the content of the constituent units (φ) derived from 6AOCM. cou It changed due to (%). cou It is presumed that as the percentage increases, the proportion of dimerized coumarin moieties increases, leading to an increase in crosslinking points and thus increased elasticity.

[0120] (Stress measurement during compression-release process 4) In Example 2, stress measurements were performed during the compression-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation times adjusted from 3 minutes to 60 minutes. The results are shown in Figure 30 and Table 15.

[0121] [Table 15]

[0122] As shown in Table 15, the maximum point stress increased with increasing UV irradiation time, yielding results similar to those obtained during the stretching process.

[0123] The reflectance spectrum of the elastomer film after UV irradiation in Example 2 was measured while it was compressed. For the elastomer film after UV irradiation in Example 2, the strain was converted to pressure from the stress-strain curve during the compression process, and the reflected wavelength was plotted against the pressure. The results are shown in Figure 31. It was confirmed that the pressure required to change the reflected wavelength to a similar level varies depending on the ultraviolet irradiation time.

[0124] The reflectance spectrum of the elastomer film after UV irradiation in Example 2 was measured while releasing the compressive force. The reflected wavelength was plotted against the time from the release of the compressive force. The results are shown in Figure 32. The change in reflected wavelength after the release of the compressive force varied with the UV irradiation time. This is presumed to be because as the UV irradiation time increased, the proportion of dimerized coumarin moieties increased, leading to an increase in crosslinking points and increased elasticity.

[0125] (Measurement of reflectance spectrum) The silica nanoparticles 2 from Example 2 were hot-pressed at 150°C to form a thickness of approximately 500 μm. After applying vibrational shear strain, they were formed into a long, elongated shape with a length of approximately 1.5 mm and a width of approximately 4.5 mm. This produced a long elastomer film. A long elastomer film was exposed to ultraviolet light with a wavelength of 365 nm at an intensity of 120 mW / cm². 2The film was irradiated for 3 minutes. Next, the elastomer film was divided into five sections along its length, designated as regions (1) to (5) from one end to the other. With aluminum foil, which functions as a photomask, placed on regions (2) and (4), the elastomer film was irradiated with ultraviolet light at a wavelength of 365 nm and an intensity of 120 mW / cm². 2 The irradiation was performed under the condition of 57 minutes.

[0126] The elastomer film was stretched to 50% strain after UV irradiation, and its reflectance spectrum was measured. The results are shown in Figure 33. Figures 33(1) to (5) correspond to the reflectance spectra in regions (1) to (5), respectively. As shown in Figure 33, regions (1), (3), and (5), which were irradiated with ultraviolet light for a total of 60 minutes, showed a reflective color upon stretching. However, in regions (2) and (4), where ultraviolet irradiation was interrupted midway, no reflective color was observed even after stretching. From the above results, it was possible to visualize patterns that were not visible before stretching by stretching an elastomer film that had been patterned with ultraviolet irradiation. Such a technique is a false It is expected to have applications in preventing erosion and other related fields.

[0127] [Examples 9 and 10] (Preparation of silica nanoparticles 9A and 10A modified with the first polymer chain) Silica nanoparticles with an average particle size of 120 nm were prepared, and silica nanoparticles (SiP-Br) having an ATRP initiator group represented by formula (1a) on their surface were fabricated using the same procedure as in Example 1. In Example 1 (Preparation of silica nanoparticles 1A modified with the first polymer chain), silica nanoparticles 9A and 10A (SiP-PBA9, SiP-PBA10) modified with the first polymer chain were obtained in the same manner as in Example 1, except that the amounts of each reagent used and the polymerization conditions were changed as shown in Table 16.

[0128] [Table 16]

[0129] (Preparation of silica nanoparticles 9 and 10 modified with the first and second polymer chains) In Example 1 (Preparation of silica nanoparticles 1 modified with the first and second polymer chains), the acrylic acid ester having a coumarin skeleton (6AOCM) was changed to an acrylic acid ester having an anthracene skeleton represented by the following chemical formula (2AOAN), the polymerization temperature before adding tributyltin hydride was changed from 70°C to 90°C (the reaction temperature after adding tributyltin hydride remained unchanged at 70°C), and the amounts of each reagent used and the polymerization conditions were changed as shown in Table 17. In addition, silica nanoparticles 9 and 10, which are Examples 9 and 10 and are modified with the first and second polymer chains, were obtained in the same manner as in Example 1.

[0130] [ka]

[0131] [Table 17]

[0132] (Molecular weight of polymer chains) In Examples 9 and 10, the number-average molecular weight (Mn) of the polymer chain was determined by SEC measurement in the same manner as in Example 1. Furthermore, a first or second polymer chain was synthesized using ethyl 2-bromoisobutyrate (EBIB) as the starting group under the same synthesis conditions as in Examples 9 and 10, except that silica nanoparticles were not used. The number-average molecular weight (Mn) of the first polymer chain was then determined. n,1 ) or the number-average molecular weight (M) of the second polymer chain n,2 Measurements were taken. The results are shown in Table 18.

[0133] (polymer chains) 1 (H-NMR spectrum) In Examples 9 and 10, 1From the results of the H-NMR spectrum (solvent: deuterated chloroform), the content of constituent units derived from acrylic acid esters having an anthracene skeleton (2AOAN in Examples 9 and 10) (corresponding to the third constituent unit) relative to the total constituent units of the first and second polymer chains contained in the shell layer of silica nanoparticles was determined. Specifically, the content of constituent units derived from acrylic acid esters having an anthracene skeleton (φ Ant (%) was determined based on the following formula (2). For Example 9, the chemical formula of silica nanoparticles 9 modified with the first polymer chain and the second polymer chain, and 1 The results of the 1H-NMR spectrum are shown in Figure 34. In equation (2), S1 is the integral value of peak a in Figure 34, and S2 is the sum of the integral values ​​of peaks b to e in Figure 34. For Example 10, the polymer chain was analyzed in the same manner as in Example 9. 1 1H-NMR spectra were measured. The results are shown in Table 18.

[0134]

number

[0135] [Table 18]

[0136] (Measurement of reflectance spectrum) Silica microparticles 9 and 10, modified with the first and second polymer chains of Examples 9 and 10, were hot-pressed at 150°C to form discs with a diameter of approximately 25 mm and a thickness of approximately 500 μm. This produced disc-shaped elastomer films. Vibrational shear strain was applied to a disc-shaped elastomer film using a rheometer's parallel plate jig under the following conditions. This resulted in the fabrication of the elastomer film after shearing. -Conditions for applying vibrational shear strain- Jig diameter: 25mm Model: MCR102 (Anton Paar) Temperature: 150℃ Frequency: 0.1Hz Load: 8N Strain: 100% Application time: 10 min

[0137] The reflectance spectra were measured before and after shearing using the elastomer film before and after shearing. The results are shown in Figure 35. Figures 35(1) and (2) correspond to the reflectance spectra of the elastomer films of Examples 9 and 10, respectively.

[0138] As shown in Figure 35, the elastomer films of Examples 9 and 10 exhibited a reflective color upon shearing. The reason for this reflective color is presumed to be that the application of vibrational shear strain caused silica nanoparticles containing polymer chains within the elastomer film to orient themselves and form a colloidal crystal structure.

[0139] (UV irradiation 4) The elastomer films of Examples 9 and 10 were exposed to ultraviolet light with a wavelength of 365 nm at an intensity of 120 mW / cm². 2 The irradiation was performed under conditions of an irradiation time of 60 minutes or less. This resulted in obtaining an elastomer film after UV irradiation. In the examples of this disclosure, the elastomer film before shearing (thickness 60 μm) was used for the change in ultraviolet-visible absorption spectrum described later, and the elastomer film after shearing described above was used for the change in fluorescence spectrum.

[0140] (Evaluation of UV-Vis absorption spectrum changes and fluorescence spectrum changes 1) The changes in the ultraviolet-visible absorption spectrum and fluorescence spectrum of the elastomer film of Example 9 were measured when ultraviolet light was irradiated. The results are shown in Figures 36 and 37. It was confirmed that the peaks originating from the anthracene skeleton decreased upon ultraviolet irradiation.

[0141] (Frequency dispersion measurement 1) Next, frequency dispersion measurements were performed on the elastomer film of Example 9 when it was irradiated with ultraviolet light. The results are shown in Figure 38. It was observed that the storage modulus at 1 Hz tended to increase with increasing ultraviolet irradiation time. This is presumed to be because the dimerization reaction of the anthracene moiety progressed due to ultraviolet irradiation, increasing the number of crosslinking sites.

[0142] (Measurement of swelling rate) The swelling rate of the elastomer film was determined when the UV irradiation time was changed. Specifically, the elastomer film after shearing or the elastomer film after UV irradiation from Example 9 was immersed in N,N-dimethylformamide, a solvent, for 6 hours, 1 day, 3 days, 5 days, or 7 days, and the swelling rate (%) was calculated based on the following formula. The results are shown in Table 19. Swelling rate (%) = (Mass of elastomer film after immersion / Mass of elastomer film before immersion) × 100

[0143] [Table 19]

[0144] As shown in Table 19, the average swelling rate tended to decrease as the UV irradiation time increased. This is presumed to be because UV irradiation promoted the dimerization reaction of the anthracene moiety, increasing the number of crosslinking sites.

[0145] (Stress measurement by stretching 6) To confirm the effect of UV irradiation time on elastomer films, in Example 9, stress measurements were performed by stretching on elastomer films after shearing and after UV irradiation with UV irradiation times adjusted from 1 to 15 minutes. The results are shown in Figure 39 and Table 20.

[0146] [Table 20]

[0147] As shown in Table 20, the maximum point stress increased with increasing UV irradiation time. This is presumed to be because UV irradiation promoted the dimerization reaction of the anthracene moiety, increasing the number of crosslinking points.

[0148] (Stress measurement during the stretching-releasing process 3) In Example 9, stress measurements were performed during the stretch-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation times adjusted from 1 to 15 minutes. These stress measurements were performed at a strain of 30% of the fracture strain. The results are shown in Figure 40 and Table 21.

[0149] [Table 21]

[0150] As shown in Table 21, the maximum point stress tended to increase and the hysteresis loss rate to decrease as the UV irradiation time increased. This is presumed to be because UV irradiation promoted the dimerization reaction of the anthracene moiety, increasing the number of crosslinking points.

[0151] (Evaluation of UV-Vis absorption spectrum changes and fluorescence spectrum changes 2) The elastomer film of Example 9, after being irradiated with ultraviolet light for 15 minutes, was heated at 150°C, and the changes in the ultraviolet-visible absorption spectrum and fluorescence spectrum over time were measured. The results are shown in Figures 41 and 42. Heating at 150°C resulted in an increase in absorbance and the intensity of the fluorescence peak derived from the anthracene skeleton, suggesting that the thermal cleavage reaction of the dimerized region proceeded and the anthracene region was reformed.

[0152] (Frequency dispersion measurement 2) Next, frequency dispersion measurements were performed on the elastomer film of Example 9 after irradiating with ultraviolet rays for 15 minutes and the elastomer film heated under the conditions of 150°C for 1 hour. The results are shown in Fig. 43. It was confirmed that the storage modulus at 1 Hz decreased due to the heat treatment. This is presumably because the crosslinking points decreased due to the progress of the thermal cleavage reaction of the dimerized sites.

[0153] (Stress measurement by stretching 6) To confirm the change in mechanical properties of the elastomer film due to heating, stress measurements by stretching were performed on the elastomer film of Example 9 after irradiating with ultraviolet rays for 15 minutes and the elastomer film heated under the conditions of 150°C for 1 hour. The results are shown in Fig. 44. The maximum point stress before heating was 525 kPa, and the maximum point stress after heating was 285 kPa.

[0154] (Stress measurement in stretching - release process 4) Stress measurements in the stretching - release process were performed on the elastomer of Example 9 after irradiating with ultraviolet rays for 15 minutes and the elastomer film heated under the conditions of 150°C for 1 hour. This stress measurement was performed at a strain of 30% of the breaking strain. The results are shown in Fig. 45. The maximum point stress and the hysteresis loss rate before heating were 215 kPa and 14.7% respectively, and the maximum point stress and the hysteresis loss rate after heating were 167 kPa and 17.4% respectively.

[0155] By heating, the maximum point stress during stretching and in the stretching - release process decreased, and the hysteresis loss rate increased. This is presumably because the crosslinking points decreased due to the progress of the thermal cleavage reaction of the dimerized sites. From the above results, it was confirmed that it is possible to change the mechanical properties of the elastomer film after ultraviolet irradiation by heating.

[0156] (Evaluation of ultraviolet - visible absorption spectrum change and fluorescence spectrum change 3) The elastomer film of Example 9 (hereinafter also referred to as "elastomer film before UV re-irradiation"), which was irradiated with ultraviolet light for 15 minutes and then heated at 150°C for 1 hour, was subjected to further ultraviolet irradiation. Changes in the ultraviolet-visible absorption spectrum and fluorescence spectrum with respect to the ultraviolet irradiation time were measured. The results are shown in Figures 46 and 47. It was confirmed that the absorbance and peaks originating from the anthracene skeleton decreased upon ultraviolet irradiation.

[0157] (Frequency dispersion measurement 3) Next, frequency dispersion measurements were performed on the elastomer film before UV re-irradiation and on the same elastomer film after irradiating with ultraviolet light again for 15 minutes (hereinafter also referred to as "elastomer film after UV re-irradiation"). The results are shown in Figure 48. It was confirmed that the storage modulus at 1 Hz increased after UV re-irradiation. This is presumed to be because the dimerization reaction of the anthracene moiety proceeded again due to UV irradiation.

[0158] (Stress measurement by stretching 7) To confirm the changes in mechanical properties of elastomer films due to re-irradiation with ultraviolet light, stress measurements were performed on the elastomer films before and after UV re-irradiation. The results are shown in Figure 49. The maximum point stress before UV re-irradiation was 285 kPa, and the maximum point stress after UV re-irradiation was 398 kPa.

[0159] (Stress measurement during the stretching-releasing process 5) Stress measurements were performed on the elastomer film before and after UV re-irradiation during the stretch-release process. These stress measurements were performed at a strain of 30% of the fracture strain. The results are shown in Figure 50. The maximum point stress and hysteresis loss rate before UV re-irradiation were 167 kPa and 17.4%, respectively, while the maximum point stress and hysteresis loss rate after UV re-irradiation were 213 kPa and 13.2%, respectively.

[0160] Re-irradiation with ultraviolet light increased the maximum point stress during stretching and the stretch-release process, while decreasing the steresis loss rate. This is presumed to be because the dimerization reaction of the anthracene moiety proceeded again due to ultraviolet irradiation.

[0161] Based on the above, it was confirmed that the properties of an elastomer film can be reversibly changed by combining irradiation with ultraviolet light and heating.

[0162] (Stress measurement by stretching 8) To confirm the effect of UV irradiation time on elastomer films, in Example 10, stress measurements were performed on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation times adjusted from 0.25 minutes to 15 minutes. The results are shown in Figure 51 and Table 22.

[0163] [Table 22]

[0164] As shown in Table 22, the maximum point stress increased with increasing UV irradiation time. This is presumed to be because, similar to Example 9, UV irradiation promoted the dimerization reaction of the anthracene moiety, increasing the number of crosslinking points.

[0165] (Stress measurement during the stretching-releasing process 6) In Example 10, stress measurements were performed during the stretch-release process on the elastomer film after shearing and on the elastomer film after UV irradiation with UV irradiation time adjusted from 0.25 minutes to 15 minutes. This stress measurement was performed at a strain of 30% of the fracture strain. The results are shown in Figure 52 and Table 23.

[0166] [Table 23]

[0167] As shown in Table 23, as the ultraviolet irradiation time increased, the maximum point stress tended to increase and the hysteresis loss rate tended to decrease. This is presumably because, similar to Example 9, the dimerization reaction at the anthracene site proceeded due to ultraviolet irradiation, increasing the number of crosslinking points.

[0168] (Stress measurement during the stretching - release process 7) Regarding the elastomer of Example 10, UV irradiation with ultraviolet light for 15 minutes and heating under the conditions of 150°C for 1 hour were repeated three times in sequence (in the order of FIGS. 53(1) to (6)), and stress measurement during the stretching - release process was performed after the completion of each UV irradiation or heating. This stress measurement was carried out at a strain of 30% of the breaking strain. The results are shown in FIGS. 53 and Table 24.

[0169]

Table 24

[0170] As shown in Table 24, it was confirmed that each UV irradiation treatment increased the maximum point efficacy and decreased the hysteresis loss rate, and each heat treatment decreased the maximum point stress and increased the hysteresis loss rate. Furthermore, it was also confirmed that there were no significant changes in the mechanical properties even when the UV irradiation treatment was repeated or the heat treatment was repeated. From the above points, it was confirmed that by combining ultraviolet irradiation and heating on the elastomer film, it is possible to reversibly change the properties of the elastomer film. Furthermore, considering the results of Tables 22 and 23, it is speculated that the mechanical properties of the elastomer film can be adjusted by adjusting the conditions of ultraviolet irradiation, and the mechanical properties of the elastomer film can also be reversibly adjusted by appropriately adjusting the conditions of heat treatment and ultraviolet treatment.

[0171] [Examples 11, 12] Silica nanoparticles 9A (SiP-PBA9) modified with the first polymer chain were obtained in the same manner as in Example 9. Silica nanoparticles 11 and 12, modified with the first and second polymer chains, were obtained in the same manner as in Example 9, except that the acrylic acid ester having an anthracene skeleton (2AOAN) in Example 9 was changed to an acrylic acid ester having an anthracene skeleton represented by the following chemical formula with a different substituent at the 9-position (0MAOAN or 6AOAN), and the amount of each reagent used was changed as shown in Table 25. For comparison, the data from Example 9 is also included below.

[0172] [ka]

[0173] [Table 25]

[0174] (Molecular weight of polymer chains) In Examples 11 and 12, the number-average molecular weight (Mn) of the polymer chain was determined by SEC measurement in the same manner as in Example 9. Furthermore, a first or second polymer chain was synthesized using ethyl 2-bromoisobutyrate (EBIB) as the starting group under the same synthesis conditions as in Examples 11 and 12, except that silica nanoparticles were not used. The number-average molecular weight (Mn) of the first polymer chain was then determined. n,1 ) or the number-average molecular weight (M) of the second polymer chain n,2 Measurements were taken. The results are shown in Table 26.

[0175] (polymer chains) 1 (H-NMR spectrum) In Examples 11 and 12, 1 The content of constituent units derived from acrylic acid esters having an anthracene skeleton (0MAOAN or 6AOAN in Examples 11 and 12) was determined from the 1H-NMR spectrum (solvent: deuterated chloroform) in the same manner as in Example 9. Ant The percentage (%) was calculated based on formula (2) described above. The results are shown in Table 26.

[0176] [Table 26]

[0177] (Measurement of reflectance spectrum) In the same manner as in Example 9, silica nanoparticles 11 and 12 modified with the first and second polymer chains were formed into disc shapes, and then a sheared elastomer film was fabricated by applying vibrational shear strain to the disc-shaped elastomer film.

[0178] The reflectance spectra were measured before and after shearing using the elastomer film before and after shearing. The results are shown in Figure 54. Figures 54(1) and (2) correspond to the reflectance spectra of the elastomer films of Examples 11 and 12, respectively. As shown in Figure 54, the elastomer films of Examples 11 and 12 showed a reflective color upon shearing, similar to the elastomer film of Example 9.

[0179] (Stress measurement by stretching 9) To confirm the effect of UV irradiation time on elastomer films, stress measurements were performed by stretching on elastomer films after shearing and after UV irradiation with an adjusted UV irradiation time of 60 minutes in Examples 9, 11, and 12. The results are shown in Figure 55 and Table 27.

[0180] [Table 27]

[0181] As shown in Table 27, the maximum point stress increased upon irradiation with ultraviolet light. This is presumed to be because the dimerization reaction of the anthracene moiety progressed due to ultraviolet irradiation, increasing the number of crosslinking points.

[0182] (Stress measurement during the stretching-releasing process 8) In Examples 9, 11, and 12, stress measurements were performed during the stretch-release process on elastomer films after shearing and on elastomer films after UV irradiation with an adjusted UV irradiation time of 60 minutes. These stress measurements were performed at a strain of 30% of the fracture strain. The results are shown in Figure 56 and Table 28.

[0183] [Table 28]

[0184] As shown in Table 28, irradiation with ultraviolet light tended to increase the maximum point stress and decrease the hysteresis loss rate. This is presumed to be because ultraviolet light irradiation promoted the dimerization reaction of the anthracene moiety, increasing the number of crosslinking points.

[0185] (Evaluation of UV-Vis absorption spectrum changes and fluorescence spectrum changes 4) In the same manner as in Example 9, the changes in the ultraviolet-visible absorption spectrum and fluorescence spectrum of the elastomer films of Examples 11 and 12 were measured when irradiated with ultraviolet light. The results are shown in Figures 57 and 58 (in Figures 57 and 58, (1) is Example 11 and (2) is Example 12). It was confirmed that the peaks originating from the anthracene skeleton decreased upon ultraviolet irradiation.

[0186] (Evaluation of UV-Vis absorption spectrum changes and fluorescence spectrum changes 5) The elastomer films of Examples 11 and 12, after being irradiated with ultraviolet light for 15 minutes, were heated at 150°C, and the changes in the fluorescence spectrum over time were measured. The results are shown in Figure 59 (in the figure, (1) is Example 11 and (2) is Example 12). An increase in absorbance and the intensity of the fluorescence peak derived from the anthracene skeleton was observed upon heating at 150°C, suggesting that the thermal cleavage reaction of the dimerized sites proceeded and the anthracene sites were reformed.

[0187] From these results, it was confirmed that the mechanical properties of the elastomer film can be adjusted by ultraviolet irradiation, even when the acrylic acid ester containing an anthracene skeleton is changed. Furthermore, it was confirmed that heating the elastomer film causes a thermal cleavage reaction in the dimerized areas, leading to the reformation of the anthracene moiety.

Claims

1. Inorganic particles and A shell layer comprising a first polymer chain located on the surface of the inorganic particles and containing a plurality of first structural units derived from acrylic acid ester, and a second polymer chain containing a second structural unit derived from acrylic acid ester and a third structural unit having a structure capable of forming a cyclic polymer structure by irradiation with active energy rays, A composite particle comprising the first polymer chain and the second polymer chain, as viewed from the inorganic particle side.

2. The composite particle according to claim 1, wherein the third constituent unit further comprises a structure derived from an acrylic acid ester.

3. The composite particle according to claim 1, wherein the structure capable of forming a cyclic polymer structure by irradiation with the active energy ray is a coumarin skeleton, an anthracene skeleton, a thymine skeleton, a styrylpyrene skeleton, or a cinnamic acid skeleton.

4. The composite particle according to claim 1, wherein the third constituent unit is at least one selected from the group consisting of a constituent unit derived from an acrylic acid ester represented by the following chemical formula (a) and a constituent unit derived from an acrylic acid ester represented by the following chemical formula (b). 【Chemistry 1】 In chemical formulas (a) and (b), R １ and R ２ It is a divalent linking group.

5. The composite particle according to claim 1, wherein the content of the third constituent unit is 0.010 mol% to 2.0 mol% of the total constituent units contained in the shell layer.

6. The composite particle according to claim 1, wherein the acrylic acid ester in the first and second constituent units has 2 to 8 carbon atoms excluding the acryloyl group.

7. The composite particle according to claim 1, wherein the inorganic particle is at least one of silica, carbon particles, and metal oxide particles.

8. A film-like member comprising composite particles according to any one of claims 1 to 7.

9. The film-like member according to claim 8, having a colloidal crystalline structure.

10. The film-like member according to claim 8, wherein at least a portion of the third constituent unit forms a cyclic polymer structure.

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