Structure and method for producing structure

Abstract

A first structure according to one embodiment of the present disclosure comprises a plurality of nanoparticles, wherein the plurality of nanoparticles are linked to each other through non-covalent bonds without using an additive component other than the plurality of nanoparticles.

Description

Structure and method for manufacturing the structure

[0001] The present disclosure relates to, for example, structures using nanoparticles and methods for manufacturing such structures.

[0002] For example, Patent Document 1 discloses a structure that has high light transmittance and a high degree of freedom in shape achieved by directly covalently bonding multiple nanoparticles together without using any additional components other than the multiple nanoparticles.

[0003] International Publication No. 2023 / 089990

[0004] Meanwhile, for example, high durability is desired for structures used as substitute materials for plastics.

[0005] It is desirable to provide structures and methods for manufacturing structures that are highly durable.

[0006] A first structure according to one embodiment of the present disclosure includes a plurality of nanoparticles, which are non-covalently linked to one another without the intervention of any additional component other than the nanoparticles.

[0007] A method for manufacturing a structure according to one embodiment of the present disclosure involves modifying the surface of each of a plurality of nanoparticles with a plurality of alkoxy groups or a plurality of reactive functional groups, and then dispersing the plurality of nanoparticles in a first solvent to link the plurality of nanoparticles together by non-covalent bonds.

[0008] The second structure according to one embodiment of the present disclosure comprises a plurality of nanomaterials, which are non-covalently linked to one another without the intervention of any additional components other than the plurality of nanomaterials.

[0009] A third structure according to an embodiment of the present disclosure includes a plurality of nanomaterials, and the connectivity parameter of the plurality of nanomaterials is greater than 0 and equal to or less than 0.80.

[0010] In the first to third structures according to an embodiment of the present disclosure and the method for manufacturing a structure according to an embodiment, the nanoparticles are non-covalently linked to each other without the use of any additional component other than the nanoparticles, thereby imparting elasticity to the structure made of the nanoparticles.

[0011] FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of a structure according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating an example of the structure of the nanoparticles shown in FIG. 1. FIG. 2 is a schematic diagram illustrating another example of the structure of the nanoparticles shown in FIG. 1. FIG. 3 is a diagram illustrating the connection between the multiple nanoparticles shown in FIG. 1. FIG. 4 is a diagram illustrating the surface configuration of the multiple nanoparticles shown in FIG. 1. FIG. 5 is a diagram illustrating the internal configuration of the multiple nanoparticles shown in FIG. 1. FIG. 6 is a characteristic diagram illustrating the relationship between the compression limit and the connectivity parameter. FIG. 7A is a diagram illustrating an example of the spatial arrangement of multiple nanoparticles. FIG. 7B is a diagram illustrating another example of the spatial arrangement of multiple nanoparticles. FIG. 7C is a diagram illustrating another example of the spatial arrangement of multiple nanoparticles. FIG. 8 is an image of the structure shown in FIG. 1 photographed using a transmission electron microscope. FIG. 9 is a solid-state 29Si-NMR spectrum of the structure. FIG. 10 is a flow chart illustrating an example of a manufacturing process of the structure according to an embodiment of the present disclosure. FIG. 11 is a diagram illustrating the elasticity of the structure shown in FIG. 1.

[0012] Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings. The following description is one specific example of the present disclosure, and the present disclosure is not limited to the following aspects. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of explanation is as follows: 1. Embodiment (Example of a structure in which multiple nanoparticles are linked together by non-covalent bonds) 1-1. Structure configuration 1-2. Method for manufacturing the structure 1-3. Actions and effects 2. Modified examples 3. Example of use of the structure

[0013] 1 is a schematic diagram illustrating an example of the configuration of a structure (structure 1) according to an embodiment of the present disclosure. Structure 1 can be used, for example, as an alternative material to plastic.

[0014] The structure 1 of this embodiment includes a plurality of nanoparticles 11, which are linked together by non-covalent bonds without any additional component other than the nanoparticles 11 being involved.

[0015] The term "added component" refers to a component that is not bound to the nanoparticle 11 at a stage prior to the linking reaction (see, for example, step S104, FIG. 11 ) described below. For example, functional groups modified on the surface of the nanoparticle 11 are not considered to be added components, but resins or molecules added separately from the nanoparticle 11 are considered to be added components. Furthermore, the term "non-covalent bond" refers to a bond formed via a non-covalent bond such as an electrostatic interaction (ionic bond), a metallic bond, a hydrogen bond, or a van der Waals force.

[0016] As shown in FIG. 2A , the surface of the nanoparticle 11 is coated with amphiphilic molecules 12. Examples of the amphiphilic molecules 12 include surfactant molecules, amino acid molecules, and polymers such as phospholipids and block copolymers of polyalkylene glycols. As shown in FIG. 2B , the nanoparticle 11 reacts with organosilane molecules 13 having an organic functional group or a fluoro group to form a covalent bond, thereby passivating the surface. Alternatively, the nanoparticle 11 reacts with organosilane molecules 13 having an organic functional group or a fluoro group and further having a reactive functional group, thereby passivating the surface. The nanoparticle 11 may be passivated by surface modification with, for example, hydrogen molecules or acyclic hydrocarbon groups such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, octyl, decyl, or dodecyl groups.

[0017] FIG. 3 is an enlarged view of region A shown in FIG. 1, showing the state of connections between the plurality of nanoparticles 11. FIG. 4 is an enlarged view of region B shown in FIG. 1, showing the state of the surfaces of the plurality of nanoparticles 11. The structure 1 of this embodiment has recyclability. As described above, the surfaces of the plurality of nanoparticles 11 are coated with amphiphilic molecules 12 or are passivated with organic silane molecules 13. As an example, the surfaces of the plurality of nanoparticles 11 (for example, silica nanoparticles) may have the M shown in FIG. 4. １The nanoparticles 11 are modified with organic silane molecules such as those shown in the figure. Therefore, the nanoparticles 11 cannot be crosslinked with each other, i.e., cannot be linked to each other by covalent bonds. Instead, they are linked to each other by non-covalent bonds such as electrostatic interactions (ionic bonds), metallic bonds, hydrogen bonds, and van der Waals forces. This allows the nanoparticles 11 to be dispersed in a predetermined organic solvent, making the structure 1 recyclable.

[0018] The nanoparticles 11 are composite oxides of oxidation-resistant metal atoms. Specifically, they are oxides of zirconium (Zr), titanium (Ti), tin (Sn), silicon (Si), aluminum (Al), or zinc (Zn). Among the above metal oxides, it is preferable to use Si oxide or Al oxide, which has a low refractive index and optical transparency, as the nanoparticles 11. For example, the nanoparticles 11 form a three-dimensional covalent bond network between metal atoms (M) and oxygen atoms (O) via M-O-M bonds.

[0019] FIG. 5 is an enlarged view of region C shown in FIG. 1 , showing the internal state of the plurality of nanoparticles 11. The structure 1 of this embodiment has elasticity. In this embodiment, the plurality of nanoparticles 11 have a random network structure with a low degree of condensation. Here, the internal bonding state (degree of condensation) of the plurality of nanoparticles 11 is defined by a bonding parameter. The bonding parameter (Q) is expressed by the following mathematical formula (1). When the number of bonds of all metal atoms is Z, the bonding parameter is 1. On the other hand, when the number of bonds is 0, the bonding parameter is 0.

[0020] (Z: maximum number of bonds of metal atoms, k: number of bonds of a specific metal atom, Q ｋ : the number of metal atoms with bond number k)

[0021] Below, an example will be described in which the structure 1 is composed of multiple silica nanoparticles. When silicon atoms (Si) are used as the metal atoms, Z = 4. Q1, Q2, Q3, and Q4 are determined from the peak area ratio of Si assigned by solid-state nuclear magnetic resonance (29Si-NMR) analysis. In silica nanoparticles, silicon atoms and oxygen (O) atoms form ≡Si-O-Si≡ bonds. The maximum number of bonds (Z) of silicon atoms is 4, and any silicon atom in a silicon nanoparticle can have up to four Si-O-Si bonds. In this case, silicon atoms with Z < 4 are terminated with bonds other than ≡Si-O-Si≡, for example, hydrogen atoms such as ≡Si-O-H.

[0022] In this embodiment, various nanoparticle structure models with different bonding parameters were prepared, and their compression limits were evaluated by simulation.

[0023] The structural model of the nanoparticles was created by cutting out the original bulk structure at the particle size. The original bulk structure can be a known crystalline structure identified through experiments. In the case of silica nanoparticles, for example, the crystalline structure of quartz is well known. The structure was cut so that oxygen atoms remained on the nanoparticle side after cutting. Hydrogen atoms were added in place of the cut oxygen atoms.

[0024] In addition, an amorphous structure can be used as the original bulk structure. The amorphous structure was created using classical molecular dynamics, which simulates the motion of atoms. In classical molecular dynamics, the forces acting on atoms can be evaluated by defining an empirical potential that characterizes the interactions between atoms.

[0025] This calculation used the reactive force field (ReaxFF) as an empirical potential described in Reference 1 (T.P. Senftle, ​​S. Hong, M. M. Islam, S.B. Kylasa, Y. Zheng, Y.K. Shin, C. Junkermeier, R. Engel-Herbert, M.J. Janik, H.M. Aktulga, T. Verstraelen, A. Grama, A.C.T. van Duin, npj Computational Materials. 2, 1-14 (2016)). Quartz was used as the initial structure, a known crystal structure.

[0026] Under the conditions of a three-dimensional periodic boundary and a fixed volume, classical molecular dynamics simulations were performed at 5000 K for 200 ps (time step width 0.5 fs x 400,000 steps) to create a liquid state. The material was then rapidly cooled from 5000 K to 300 K for 20 ns (time step width 0.5 fs x 40 million steps) to transform it into an amorphous structure. The structure was extracted and hydrogen-terminated in the same manner as for the crystal structure.

[0027] The relationship between the compression limit and the bonding parameter was evaluated using the following method, which uses classical molecular dynamics to simulate atomic motion. In classical molecular dynamics, the force acting on atoms can be evaluated by defining an empirical potential that characterizes interatomic interactions. In this calculation, as with the above, a reactive force field (ReaxFF) was used as the empirical potential. Compression was performed using a pseudo-wall potential. The pseudo-wall potential (E) was defined by the following equation (2). Here, ε was set to 200 kcal / mol and γc was set to 1.0 Å.

[0028]

[0029] A classical molecular dynamics simulation was performed at 300 K for 200 ps (time step width 0.5 fs x 400,000 steps) under non-periodic boundary and fixed volume conditions. The wall was placed horizontally along the z axis, and its position was z = D, sandwiching the nanoparticle structure model between z = 0 and z = D, where D is the size of the target nanoparticle structure model.

[0030] When the compression ratio was 0.5, the upper wall was changed from z = D to z = D / 2 over 200 ps. Then, the upper wall was returned from z = D / 2 to z = D over 200 ps, ​​and the structure of the nanoparticle structure model was compared before and after compression.

[0031] The presence or absence of bond recombination was determined based on the state of bonds between each atom before and after compression. The simulation results showed that if bond recombination occurred, the shape of the nanoparticle changed as a permanent distortion. On the other hand, if bond recombination did not occur, the distortion caused by compression was immediately restored. The maximum compression rate at which bond recombination did not occur during compression was defined as the compression limit P.

[0032] Figure 6 shows the relationship between the compression limit P and the connectivity parameter Q. The dotted lines are calculated by linear approximation of the data points. Approximation by mean square yielded the relationship P = -1.3Q + 1.3.

[0033] In the measurement of compression set in accordance with JIS K6262 (2013), the compression ratio of the disk-shaped test piece is fixed at 0.25 as the measurement condition, and the presence or absence of permanent set occurring after compression is evaluated.

[0034] From Figure 6, it can be seen that the range of compression limit (P) = 0.25 or more corresponds to the connectivity parameter (Q) = 0.8 or less. Therefore, it is believed that nanoparticles with Q ≦ 0.8 do not undergo bond recombination under the compression set measurement conditions. Furthermore, it is believed that structures filled with these nanoparticles also do not undergo bond recombination under similar compression conditions. Bond recombination changes the shape of the nanoparticles. On the other hand, if the bonding state does not change, the stable structure of the nanoparticles is thought to remain the same.

[0035] For this reason, in this embodiment, the connectivity parameter (Q) of the plurality of nanoparticles 11 is preferably greater than 0 and less than 0.80. For example, when considering vibrations due to environmental factors such as cold regions (e.g., in the range of P>0.30 or more), the connectivity parameter (Q) of the plurality of nanoparticles 11 is preferably greater than 0 and less than 0.77. For example, when using the structure 1 for bending parts such as joints of a robot (e.g., in the range of P>0.35 or more), the connectivity parameter (Q) of the plurality of nanoparticles 11 is preferably greater than 0 and less than 0.74. As a result, as will be described in detail later, the nanoparticles 11 themselves have elastic properties (flexibility), and the structure can be restored after deformation, thereby obtaining a structure 1 that avoids factors that cause compression set.

[0036] Note that the points in Figure 6 correspond to nanoparticle structure models of different sizes, crystalline, or amorphous. Smaller nanoparticles have a smaller connectivity parameter (Q) due to the presence of more atoms near the surface.

[0037] In silica nanoparticles whose surfaces have been inactivated by organic silane molecules 13 such as a silane coupling agent, Si atoms are included at the terminal ends, and the connectivity parameter (Q) calculated by the above formula (1) increases. However, because the Si-O-Si network itself inside the silica nanoparticles remains unchanged, the Si-O-Si bonds containing the silane coupling agent are excluded from the counting of the connectivity parameter (Q). The following describes the connectivity parameter when organic silane molecules are used to modify the surface of silica nanoparticles.

[0038] When organosilane molecules are used as surface modification groups for silica nanoparticles, the bonding parameter is corrected to eliminate the influence of Si atoms contained in the organosilane molecules. This is because the organosilane molecules used in this embodiment are trifunctional molecules, such as those represented by formula (1) or (2) described below, that can be covalently bonded to silica nanoparticles at only one point, and the Si contained in the organosilane molecules does not contribute to the elasticity of structure 1. Note that the phrase "only at one point" above means that the organosilane molecules used in this embodiment are not covalently bonded to multiple silica nanoparticles. When the peak area ratio of Si derived from the organosilane compound particles assigned by 29Si-NMR analysis is Mm, m is the peak number, and Y is the total number of peaks, the bonding parameter (Q) is expressed by the following formula (3):

[0039] The structure 1 is a non-porous body in which a plurality of nanoparticles 11 are densely packed so that they are adjacent to each other, as shown in Fig. 1. Here, the "non-porous body" means that the nanoparticles 11 constituting the structure 1 move freely to fill gaps, and the structure of the nanoparticles 11 (for example, a hollow structure, a porous structure, or a non-porous structure) does not matter.

[0040] As described above, the surfaces of the plurality of nanoparticles 11 are coated with the amphiphilic molecules 12 or are inactivated with the organic silane molecules 13, and are in a state where they cannot be linked to each other by covalent bonds.

[0041] 7A to 7C show examples of the spatial arrangement of a plurality of nanoparticles 11. The plurality of nanoparticles 11 may have a face-centered cubic lattice structure, for example, as shown in FIG. 7A. In this case, the packing density of the structure 1 is 74% by volume. The plurality of nanoparticles 11 may have a body-centered cubic lattice structure, for example, as shown in FIG. 7B. In this case, the packing density of the structure 1 is 68% by volume. The plurality of nanoparticles 11 may have a hexagonal close-packed structure, for example, as shown in FIG. 7C. In this case, the packing density of the structure 1 is 74% by volume.

[0042] The spatial arrangement of the nanoparticles 11 in the structure 1 is not limited to the above-described packed structure, and they may be randomly packed, in which case the packing density is preferably 50% by volume or more. The structure 1 may also contain secondary particles formed by aggregation of the nanoparticles 11.

[0043] The plurality of nanoparticles 11 have a primary particle diameter of, for example, 1 nm or more and 10 nm or less. Alternatively, when the plurality of nanoparticles 11 have a hollow structure or a porous structure, they have a primary particle diameter of, for example, 1 nm or more and 100 nm or less. Although the above range is large for nanoparticles, flexibility can be expected if the binding parameter is reduced by adopting a hollow or porous structure.

[0044] The primary particle diameter of the nanoparticles 11 is determined as follows.

[0045] First, the structure 1 to be measured is processed into a thin section by FIB or the like. When the FIB method is used, a carbon film and a tungsten thin film are formed as protective films as a pretreatment for observing a cross-sectional TEM image, which will be described later. The carbon film is formed on the surface of the structure 1 by vapor deposition. The tungsten thin film is formed on the surface of the structure 1 by vapor deposition or sputtering. In this way, a cross section of the structure 1 is formed by thinning.

[0046] The cross section of the obtained thin film sample is observed using a transmission electron microscope (Tecnai G2 manufactured by FEI) at an acceleration voltage of 200 kV in a field of view of 50 nm × 50 nm so that multiple nanoparticles 11 can be observed, and a TEM photograph is taken. Note that the photographing position is selected randomly from the thin film sample.

[0047] Next, 50 nanoparticles 11 whose diameters are clearly visible in the direction of the observation surface are selected from the TEM photograph. If there are fewer than 50 nanoparticles 11 whose diameters are clearly visible in one photographed field of view, 50 nanoparticles 11 whose diameters are clearly visible in the direction of the observation surface are selected from multiple fields of view. Figure 8 is an image of a TEM photograph of the structure 1 taken using a transmission electron microscope. For example, in Figure 8, nanoparticles a and b whose diameters are clearly visible are selected. On the other hand, for example, nanoparticles c and d, the nanoparticles 11 overlap in the depth direction of the observation, making it impossible to confirm their shapes, and therefore are not suitable for measurement. The maximum diameter of each of the selected 50 nanoparticles 11 is measured.

[0048] Here, the maximum diameter is the maximum distance between two parallel lines drawn from any angle so as to be tangent to the contour of the nanoparticle 11 (so-called maximum Feret diameter). When measuring the maximum diameter (maximum Feret diameter), the diameter of the particle portion excluding the alkoxy groups and reactive functional groups modified on the surface of the nanoparticle 11 is measured. The primary particle diameter (average particle diameter) of the nanoparticle 11 is obtained by calculating the median value of the 50 maximum diameters (maximum Feret diameters) thus determined.

[0049] The connectivity parameters of the plurality of nanoparticles 11 can be adjusted as follows.

[0050] The binding parameter is determined by the particle size of the nanoparticles, the manufacturing conditions, and the post-treatment conditions. For example, the smaller the particle size, the smaller the binding parameter can be.

[0051] Furthermore, by considering the manufacturing method and post-treatment conditions, it is possible to synthesize multiple nanoparticles 11 with desired bonding parameters. For example, by reacting nanoparticles with water molecules in the presence of a catalyst or by heating, the ≡Si-O-Si≡ bonds that constitute the silica skeleton of the nanoparticles are hydrolyzed into two ≡Si-OH groups, thereby denaturing them into nanoparticles with a smaller bonding parameter even if they have the same particle size. Silica nanoparticles are dispersed in any solvent, and a predetermined amount and type of acid or base is added. Water is added as needed, and the mixture is heated and stirred as necessary. A similar reaction also occurs when the mixture is stirred in a high-humidity environment instead of adding water.

[0052] Furthermore, even when the particle diameter is large, the nanoparticles 11 may be made hollow or porous, as described above, to increase the surface area and control the bonding parameters. The hollow structure of silica nanoparticles can be produced with reference to Reference 2 (MFCTakai, New Glass 31 (1), 24-27, 2016-03 New Glass Forum). According to Reference 2, the organic particle template method, inorganic particle template method, and vesicle template method are listed as possible methods for producing hollow structures, but the present invention is not limited thereto. According to Reference 2, the organic liquid crystal template method is listed as a possible method for producing porous structures, but the present invention is not limited thereto.

[0053] As mentioned above, the ≡Si-O-Si≡ bonds that make up the silica skeleton react with water molecules in the presence of a catalyst or upon heating and hydrolyze into two ≡Si-OH groups. This allows nanoparticles with the same particle size and hollow shell thickness to be modified into nanoparticles with a smaller bonding parameter. Hollow silica nanoparticles are dispersed in a solvent, and a predetermined amount and type of acid or base is added. Water is added as needed, and the mixture is heated and stirred as needed. A similar reaction also occurs when the mixture is stirred in a high-humidity environment instead of adding water.

[0054] 9 is a diagram of the solid-state 29Si-NMR spectrum of the structure. The number of metal atoms with a bonding number k (for example, Q1, Q2, Q3, and Q4 of silica nanoparticles) can be measured as follows.

[0055] (Q1, Q2, Q3, Q4 in the solid state 29Si-NMR spectrum of the structure) The solid state 29Si-NMR spectrum of the obtained structure is measured under the following conditions.

[0056] <Sample Preparation Conditions> The obtained structure is washed and dried, then pulverized by the following method, and the powder is filled into a test tube.

[0057] <Measurement conditions> Device name: Bruker Advance 300 wbs spectrometer (manufactured by BRUKER) Measurement method: DD (Dipolar Decoupling) method Temperature: Room temperature Sample tube: 7 mm Sample rotation speed: 5000 rpm Resonance frequency: 59.62 MHz Pulse width: 4.5 msec. Waiting time: 60 sec Number of accumulations: 1000 times Standard sample: hexamethylcyclotrisiloxane (-9.55 ppm)

[0058] <Peak separation method> (Baseline creation method) Procedure (1): Calculate average value 1 of the intensity in the range of -60 to -69 ppm and average value 2 of the intensity in the range of -131 to -140 ppm. Procedure (2): Define the line passing through two points (-60 ppm, average value 1) (-140 ppm, average value 2) as the baseline for Q1, Q2, Q3, and Q4. Procedure (3): Delete the baseline values ​​from the spectra assigned to Q1, Q2, Q3, and Q4. Procedure (4): Calculate average value 1 of the intensity in the range of -11 to 0 ppm and average value 2 of the intensity in the range of 21 to 30 ppm. Procedure (2): Define the line passing through two points (-11 ppm, average value 1) (21 ppm, average value 2) as the baseline for M1 assignment. Procedure (3): Delete the baseline values ​​from the spectra assigned to M1.

[0059] (Peak Separation Method) Separation method: Solver function of Microsoft Office Excel (registered trademark) Function used: Gaussian function (wherein A is the peak height, B is the peak position, and C is the half-width.) Peak assignment: Q1: -80±2 ppm, one ≡Si-O-Si≡ bond and three ≡Si-OH bonds Q2: -91±2 ppm, two ≡Si-O-Si≡ bonds and two ≡Si-OH bonds Q3: -100±2 ppm, three ≡Si-O-Si≡ bonds and one ≡Si-OH bond Q4: -110±2 ppm, four ≡Si-O-Si bonds M1: 12±2 ppm, one ≡Si-O-Si≡ bond and three ≡Si-O-C bonds

[0060] In the data of the sample of this embodiment, when focusing on the chemical shift ranges of 29Si from -140 to -60 ppm and 0 to 20 ppm, it is represented by the superposition of the peaks Q1, Q2, Q3, Q4, and M1 and 0 to 3 other peaks located at -110 to -79.0 ppm and 0 to 20 ppm. The peak shape function used was a Gaussian function, and the coefficient of determination R2 in the fitting was calculated. That is, (HO) ３ A peak at -80±2 ppm originating from the -Si(OSi) structure, (HO) ２ The peak at -91±2 ppm is due to -Si(OSi)2, and HO-Si(OSi) ３ The peak at -100±2 ppm originates from Si(OSi) ４ The peak at -110±2 ppm is due to (HO)3-Si(OSi), and the peak at 12±2 ppm is due to (HO)3-Si(OSi). Zero to three other peaks were used at arbitrary positions to make the coefficient of determination R2 approach 1.

[0061] The number of other peaks was set to 0 to 3 based on a coefficient of determination R2 value of 0.99; when this value was exceeded, the number of Gaussian peaks was not increased any further. Therefore, peaks located between -110 and -79.0 ppm could be fitted with up to seven Gaussian functions, but fitting was performed with fewer peaks depending on the results. For each structure, the obtained spectrum was defined as raw data, and spectral separation was performed as described above. In the solid-state 29Si-NMR spectrum, the peak area derived from Si(OSi)4 was designated Q4, the peak area derived from HO-Si(OSi)3 was designated Q3, the peak area derived from (HO)2-Si(OSi)2 was designated Q2, the peak area derived from (HO)3-Si(OSi) was designated Q1, and the peak area derived from (CO)3-Si(OSi) was designated M1.

[0062] (1-2. Manufacturing Method of Structure) FIG. 10 is a flow chart showing an example of a manufacturing process of the structure 1. As shown in FIG.

[0063] (Synthesis of Nanoparticles) First, nanoparticles (silica nanoparticles) are synthesized as the multiple nanoparticles 11 that constitute the structure 1 (step S101). Generally, methods for producing silica nanoparticles are broadly divided into two categories: gas-phase and liquid-phase methods. However, as described above, minute nanoparticles 11 with a diameter of 11 nm or less can be isolated without aggregation by using the liquid-phase method. For the precursor used in the liquid-phase method, it is preferable to select a molecule capable of forming a three-dimensional polysiloxane skeleton (Si—O—Si) through a hydrolysis reaction and a condensation polymerization reaction. Examples of such precursors include water glass (sodium silicate) and alkoxysilane molecules. Examples of alkoxysilane molecules include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetraisopropoxysilane, and one or more of these can be selected.

[0064] The precursor is dissolved in water or an organic solvent, and then the acidity or basicity is adjusted. This results in the formation of silica particles through a polymerization reaction. Note that the above manufacturing method is not limited to this, as long as the final nanoparticles 11 satisfy the desired binding parameters. References are listed below. For example, Reference 3 (T. Yokoi et al. Chem. Mater. 2009, 21, 3719-3729) reports the formation of nanoparticles with a diameter of 8 nm in an aqueous solution in the presence of amino acids. By coating the nanoparticle surface with amino acid molecules, the nanoparticles can be isolated without aggregation. Reference 4 (S. Sakamoto et al. Langmuir 2018, 34, 1711-1717) reports the formation of nanoparticles with a diameter of 3 nm using a reverse micelle liquid crystal phase as a template. By coating the nanoparticle surface with surfactant molecules, the nanoparticles can be isolated without aggregation.

[0065] (Surface Modification and Linking of Nanoparticles) Next, the nanoparticles 11 are dispersed in a solvent to perform surface modification and linking (step S102). Amphiphilic molecules 12, such as surfactant molecules, amino acid molecules, or polymers such as phospholipids or block copolymers of polyalkylene glycol, are added to the dispersion liquid in which the nanoparticles 11 are dispersed. The added amphiphilic molecules 12 adsorb to the surface of the nanoparticles 11 and serve to prevent aggregation of the nanoparticles. As described in the above-mentioned documents 3 and 4, depending on the manufacturing method, nanoparticles 11 whose surfaces are coated with amphiphilic molecules can be obtained. In such cases, the addition of amphiphilic molecules 12 is omitted.

[0066] In addition, instead of surfactant molecules, amino acid molecules, or polymers, organic silane molecules 13 (silane coupling agents) are added to the dispersion. The organic silane molecules 13 are selected from those having non-covalent functional groups so that the multiple nanoparticles 11 cannot be covalently bonded to each other, in other words, so that they are connected by non-covalent bonds. Examples of non-covalent functional groups include alkyl groups, amino groups, and carboxyl groups. Furthermore, since the structure 1 is endowed with elasticity derived from the multiple nanoparticles 11 as described above, the organic silane molecules 13 are selected to be trifunctional molecules that can covalently bond to silica nanoparticles at only one point. Examples of such organic silane molecules 13 include organic silane molecules represented by the following general formula (1) or general formula (2):

[0067] (Chemical formula 1) R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４ is a methyl group, an ethyl group, a propyl group, or an isopropyl group.

[0068] In this process, multiple nanoparticles 11 whose surfaces are coated with amphiphilic molecules 12 or multiple nanoparticles 11 whose surfaces are modified with organic silane molecules 13 are filled, filling the gaps between the nanoparticles, and adjacent nanoparticles 11 are connected to each other by non-covalent bonds.

[0069] (Formation of Structure) Next, the desired structure is obtained by removing the solvent from the dispersion of the surface-modified nanoparticles 11 and drying them. First, the surface-modified nanoparticles 11 are dissolved in an organic solvent (step S103). The organic solvent is appropriately selected according to the functional groups modified on the surface. Next, the solution in which the surface-modified nanoparticles 11 are dissolved is applied to a substrate, and the organic solvent components are then volatilized to obtain the structure 1 (step S104). Examples of methods for volatilizing the solvent include volatilization by heating at normal pressure or drying under reduced pressure. As a result of the above, a structure 1 is obtained in which multiple nanoparticles 10 are linked by non-covalent bonds.

[0070] The coating onto a substrate can be performed by spin coating, dip coating, or casting on a desired substrate such as a silicon substrate, glass substrate, or plastic substrate. Alternatively, a bulk can be formed by pouring a solution containing the surface-modified nanoparticles 11 into a mold and air-drying it.

[0071] If the structure 1 becomes cloudy or cracks due to interfacial tension during drying, supercritical drying or freeze-drying may be used, but if the structure can withstand this, drying by raising the temperature at normal pressure may be performed. Furthermore, the macromorphology can be controlled depending on the method for removing the organic solvent. Furthermore, a fibrous structure 1 can be produced by air-drying a concentrated, viscous solution containing surface-modified nanoparticles 11 while pulling up the thread.

[0072] (1-3. Actions and Effects) In the structure 1 of this embodiment, the plurality of nanoparticles 11 are linked to each other by non-covalent bonds without the intervention of any additional component other than the plurality of nanoparticles 11. This provides elasticity to the structure 1 made up of the plurality of nanoparticles 11. This will be described below.

[0073] Anti-reflective coatings, heat insulating materials, and semiconductor materials require properties such as abrasion resistance, low refractive index, low dielectric constant, and insulating properties. Because general carbon compound plastic materials cannot meet these requirements, inorganic material structures are used as alternatives.

[0074] When using plastic materials in objects with curved shapes or moving parts, they are preferably flexible and elastic. However, inorganic structures, which are alternative materials, generally have inelastic mechanical properties, so structural innovation is required to use inorganic structures as elastic bodies. Examples include nanoparticle-based porous membranes (silica gel) and polymers with surface-modified linear chain structures (silicone rubber).

[0075] However, inorganic material structures such as silica gel and silicone rubber, which have elasticity due to structural modifications, have structural issues related to durability. For example, the flexibility of silica gel, an inorganic nanoporous material, comes from its voids. If the voids are irreversibly crushed, it will cause changes in the elastic modulus and permanent deformation. The flexibility of silicone rubber is controlled by the crosslinking structure between surface modification groups. If the bonding state of the crosslinks changes due to friction, etc., it will cause changes in the elastic modulus and permanent deformation.

[0076] In contrast to this, in the present embodiment, as described above, the plurality of nanoparticles 11 are linked to one another by non-covalent bonds without the intervention of any additional component other than the plurality of nanoparticles 11. This provides elasticity to the structure 1. This elasticity of the structure 1 is derived from the temporary release of the linkages between the nanoparticles 11 in response to mechanical stress, and can prevent permanent deterioration.

[0077] As described above, the structure 1 of this embodiment can provide a highly durable alternative to plastic.

[0078] Furthermore, in this embodiment, the nanoparticles 11 used have a low connectivity parameter (for example, a connectivity parameter (Q) of 0.80 or less). This makes the nanoparticles 11 themselves flexible, imparting further elasticity to the structure 1 and enabling further improvement in durability. The elasticity of this structure 1 is derived from the bonding state between the atoms of the nanoparticles 11 themselves, as shown in FIG. 11, for example, and is not affected by the above-mentioned voids or crosslinks between surface substituents. Therefore, excellent creep resistance and excellent properties are obtained, in principle, in which permanent deformation due to compression does not occur.

[0079] Furthermore, in this embodiment, the nanoparticles 11 are connected to each other by non-covalent bonds such as electrostatic interactions (ionic bonds), metallic bonds, hydrogen bonds, and van der Waals forces, which allows the nanoparticles 11 in the structure 1 to be dispersed in a predetermined organic solvent, making the structure 1 recyclable.

[0080] <2. Modifications> In the above embodiment, an example has been shown in which the structure 1 is configured using a plurality of nanoparticles 11, but the present invention is not limited to this. The structure 1 can also be configured using nanomaterials other than nanoparticles, not limited to the nanoparticles 11. Examples of nanomaterials other than nanoparticles include nanofibers and nanosheets that have similar properties to the nanoparticles 11 described above.

[0081] For example, nanofibers have flexibility due to their radial elasticity, and nanosheets have flexibility due to their thickness elasticity. By subjecting nanomaterials such as nanofibers and nanosheets to the same treatment as that for the nanoparticles 11 described above, a structure 1 having the same effect as that of the above embodiment can be obtained.

[0082] Furthermore, by mixing the above-mentioned nanoparticles 11, nanofibers, nanosheets, or other flexible nanomaterials with a resin, a resin material in which the nanomaterials are dispersed can be produced.

[0083] Examples of resins that can disperse nanomaterials include epoxy resins, phenolic resins, maleimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, melamine resins, compositions containing an olefin-aromatic vinyl compound-aromatic polyene copolymer such as an ethylene-styrene-divinylbenzene copolymer, compositions containing a maleimide compound, hydrocarbon elastomers, polyphenylene ether, biphenylaralkyl novolac epoxy resins, cresol novolac resins, compositions containing a silicone-modified maleimide compound, long-chain alkyl bismaleimide resins, compositions containing a polyimide compound, cyanate ester compounds, bismaleimide compounds, bisallylnadiimide resins, benzoxazine compounds, and polymers of bismaleimide compounds and diamine compounds.

[0084] Resin materials having nanomaterials dispersed therein can be used, for example, as insulating materials for high-frequency devices, substrate materials for printed wiring boards, substrate materials for copper-clad laminates, constituent materials for semiconductor packages, protective materials for semiconductor chips, coverlays, solder resists, build-up materials, interlayer insulating materials, adhesive sheets, interlayer adhesive materials, bump sheets for flip-chip bonders, or sealing materials for power semiconductor elements.

[0085] When a resin material with dispersed nanomaterials is used as an insulating material for a high-frequency device, it can improve, for example, the low dielectric constant and low dielectric loss characteristics required for high-frequency applications. Furthermore, when a resin material with dispersed nanomaterials is used as an insulating material for a high-frequency device, it can ensure, for example, a low dielectric loss tangent while maintaining a relative dielectric constant. When a resin material with dispersed nanomaterials is used as a substrate material for a printed wiring board or a copper-clad laminate, for example, the use of a flexible nanomaterial can achieve both moldability (resin fluidity) and mechanical strength (high modulus of elasticity and flexibility) of the resin material. This improves the stability of processed dimensions and reduces the amount of warpage after mounting. Furthermore, devices using the resin material with dispersed nanomaterials can improve flame retardancy, high heat resistance, and adhesion. Furthermore, devices using the resin material with dispersed nanomaterials can also control the thermal expansion coefficient and thermal conductivity.

[0086] 3. Use Examples of the Structure The structure 1 according to the above embodiment is suitable for applications where damage due to external forces is likely to accumulate, such as moving parts or long-term use. The structure 1 has a high mass density, so it is suitable for applications where there are few weight restrictions.

[0087] For example, the structure 1 can be used for anti-reflection coatings, electronic equipment components, power generation equipment, or exteriors of mobile objects, taking advantage of its properties of abrasion resistance, low refractive index, low dielectric constant, and insulating properties.

[0088] For electronic device applications, the structure 1 can be used, for example, as a constituent material for stretchable wiring and wiring boards, optical fibers, flat cables, wiring structures, cables such as cable guides, touch panels, force sensors, MEMS, seat sensors, etc., which are used in wearable devices that can be worn on the human body, etc. Additionally, it can be used as a constituent material for parts that support electronic device parts with movable parts, such as bendable displays.

[0089] For use in mechanical drive and power generation equipment, the structure 1 can be used as a piezoelectric material that receives mechanical energy by being mechanically driven, or by being deformed by natural wave or wind forces, or as a constituent material of the elastic body that supports it.

[0090] For exterior applications of moving objects, the structure 1 can be used as a support material for deflecting wind force as an exterior part of an automobile, train, airplane, etc. The structure 1 can also be used as a constituent material for a damper in the event of a collision.

[0091] The structure 1 as an anti-reflection film can be used for the glass of automobiles and trains that are at risk of being hit by pebbles or the like, or as a constituent material for the glass of high-rise buildings that are difficult to maintain.

[0092] For example, by using biocompatible functional groups, Structure 1 can be used as a constituent material of a supplement that supports the synthesis of collagen and glycosaminoglycans necessary for the formation of hair fibers, nails, and bones.

[0093] Additionally, the structure 1 can be used as a constituent material of a sealant for sealing movable parts that have gaps.

[0094] This technology may be relevant to Goal 13 "CLIMATE ACTION" and Goal 14 "LIFE BELOW WATER" of the Sustainable Development Goals (SDGs) adopted at the 2015 United Nations Summit. Conventionally, plastic materials produced using petroleum as a raw material have been used for the above-mentioned applications. However, discarded plastics flow into the ocean and become floating plastic waste that is harmful to living organisms, causing marine pollution. Furthermore, greenhouse gases emitted during the incineration of discarded plastics contribute to global warming, which are known global problems. By using the configuration of this technology, plastic alternative materials whose primary raw material is inorganic oxides derived from rocks can be used. These plastic alternative materials have a lower plastic content than conventional nanocomposite materials and plastic materials, and because the primary raw materials are biocompatible and hydrolyzable, they reduce the risk of becoming floating waste harmful to living organisms even if they flow into the ocean. Furthermore, since the main raw material is water vapor, which is the main component generated when incinerated, it is expected that the greenhouse gas emissions will be smaller than those of plastic materials, which could contribute to preventing marine pollution and curbing global warming.

[0095] The present disclosure has been described above by giving embodiments and use examples, but the present disclosure is not limited to the above-described embodiments, etc., and various modifications are possible.

[0096] The effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0097] The present technology can also be configured as follows. According to the present technology configured as follows, it is possible to provide a plastic substitute material having high durability. [1] A structure including a plurality of nanoparticles, wherein the plurality of nanoparticles are connected to each other by non-covalent bonds without the intervention of any additional component other than the plurality of nanoparticles. [2] The structure according to [1], wherein the non-covalent bonds are hydrogen bonds or van der Waals forces. [3] The structure according to [1] or [2], wherein the connectivity parameter of the plurality of nanoparticles is greater than 0 and less than or equal to 0.80. [4] The structure according to [1] or [2], wherein the connectivity parameter of the plurality of nanoparticles is greater than 0 and less than or equal to 0.77. [5] The structure according to [1] or [2], wherein the connectivity parameter of the plurality of nanoparticles is greater than 0 and less than or equal to 0.74. [6] The structure according to any one of [1] to [5], wherein the primary particle diameter of the plurality of nanoparticles is 1 nm or greater and 100 nm or less. [7] The structure according to any one of [1] to [5], wherein the primary particle diameter of the plurality of nanoparticles is 1 nm or more and 10 nm or less. [8] The structure according to any one of [1] to [7], wherein the plurality of nanoparticles have a hollow structure or a porous structure. [9] The structure according to any one of [1] to [8], wherein the surfaces of the plurality of nanoparticles are coated with amphiphilic molecules.

[10] The structure according to [9], wherein the amphiphilic molecules are at least one of surfactant molecules, amino acid molecules, phospholipids, and block copolymers of polyalkylene glycol.

[11] The structure according to any one of [1] to

[10] , wherein organosilane molecules are covalently bonded to the surfaces of the plurality of nanoparticles.

[12] The structure according to

[11] , wherein the organosilane molecules are trifunctional molecules.

[13] The structure according to

[11] or

[12] , wherein the organosilane molecules are compounds represented by the following general formula (1) or (2): [Chemical Formula 1] R １ R ２ R ３ Si(OR ４ )...(1) R１ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４ is a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[14] The structure according to any one of [1] to

[13] , wherein each of the plurality of nanoparticles is a metal oxide.

[15] The structure according to any one of [1] to

[14] , wherein each of the plurality of nanoparticles is an oxide of zirconium, titanium, tin, silicon, aluminum, or zinc.

[16] The structure according to any one of [1] to

[15] , wherein each of the plurality of nanoparticles is an oxide of silicon or aluminum.

[17] A method for producing a structure, wherein the surface of each of the plurality of nanoparticles is modified with a plurality of alkoxy groups or a plurality of reactive functional groups, and then the plurality of nanoparticles are dispersed in a first solvent to link the plurality of nanoparticles together by non-covalent bonds.

[18] A method for producing a structure according to

[17] , wherein the surface of each of the plurality of nanoparticles is modified with the plurality of reactive functional groups by adding organosilane molecules represented by the following general formula (1) or the following general formula (2). [Chemical Formula 2] R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４is a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[19] A method for producing a structure according to

[17] or

[18] above, wherein the structure is obtained via removal of the first solvent and drying.

[20] A method for producing a structure according to any one of

[17] to

[19] above, wherein a molecule capable of forming a three-dimensional polysiloxane skeleton is used as a precursor, the precursor is dispersed in a second solvent, and the dispersion in which the precursor is dispersed is adjusted to be acidic or basic to obtain the plurality of nanoparticles.

[21] A structure comprising a plurality of nanoparticles whose surfaces are coated with amphiphilic molecules, and the plurality of nanoparticles are linked to each other without the intervention of any additional component other than the plurality of nanoparticles.

[22] The structure according to

[21] above, wherein the amphiphilic molecules are at least one of surfactant molecules, amino acid molecules, phospholipids, and block copolymers of polyalkylene glycol.

[23] A structure comprising a plurality of nanoparticles having organic silane molecules represented by the following general formula (1) or (2) covalently bonded to the surface thereof, wherein the plurality of nanoparticles are connected to each other without the intervention of any additional component other than the plurality of nanoparticles. [Chemical Formula 3] R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４is a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[24] A structure comprising a plurality of nanomaterials, wherein the plurality of nanomaterials are non-covalently linked to one another without the intervention of any additional component other than the plurality of nanomaterials.

[25] The structure according to

[24] , wherein the plurality of nanomaterials include at least one of nanoparticles, nanofibers, and nanosheets.

[26] The structure according to

[24] or

[25] , wherein the plurality of nanomaterials have a bonding parameter greater than 0 and equal to or less than 0.80.

[27] The structure according to any one of

[24] to

[26] , wherein the surfaces of the plurality of nanomaterials are covered with amphiphilic molecules.

[28] The structure according to

[27] , wherein the amphiphilic molecules are at least one of surfactant molecules, amino acid molecules, phospholipids, and block copolymers of polyalkylene glycol.

[29] The structure according to any one of

[24] to

[28] , wherein organic silane molecules are covalently bonded to the surfaces of the plurality of nanomaterials, and the organic silane molecules are trifunctional molecules.

[30] The structure according to

[29] , wherein the organic silane molecules are compounds represented by the following general formula (1) or (2): [Chemical Formula 4] R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４is a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[31] The structure according to any one of

[24] to

[30] , wherein each of the plurality of nanomaterials is an oxide of zirconium, titanium, tin, silicon, aluminum, or zinc.

[32] A structure comprising a plurality of nanomaterials, wherein the connectivity parameter of the plurality of nanomaterials is greater than 0 and equal to or less than 0.80.

[33] The structure according to

[32] , wherein the plurality of nanomaterials include at least one of nanoparticles, nanofibers, and nanosheets.

[34] The structure according to

[32] or

[33] , wherein the surfaces of the plurality of nanomaterials are covered with amphiphilic molecules.

[35] The structure according to

[34] , wherein the amphiphilic molecules are at least one of surfactant molecules, amino acid molecules, phospholipids, and block copolymers of polyalkylene glycol.

[36] The structure according to any one of

[32] to

[35] , wherein organic silane molecules are covalently bonded to the surfaces of the plurality of nanomaterials, and the organic silane molecules are trifunctional molecules.

[37] The structure according to

[36] , wherein the organic silane molecules are compounds represented by the following general formula (1) or (2): [Chemical Formula 4] R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４ is a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[38] The structure according to any one of

[32] to

[37] , wherein each of the plurality of nanomaterials is an oxide of zirconium, titanium, tin, silicon, aluminum, or zinc.

[0098] This application claims priority based on Japanese Patent Application No. 2023-212701, filed on December 18, 2023, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0099] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A structure comprising a plurality of nanoparticles, the plurality of nanoparticles being non-covalently linked to one another without the intervention of any additional component other than the plurality of nanoparticles.

2. The structure of claim 1, wherein the non-covalent bond is a hydrogen bond or a van der Waals force.

3. The structure of claim 1, wherein the connectivity parameter of the plurality of nanoparticles is greater than 0 and less than or equal to 0.

80.

4. The structure of claim 1, wherein the connectivity parameter of the plurality of nanoparticles is greater than 0 and less than or equal to 0.

77.

5. The structure of claim 1, wherein the connectivity parameter of the plurality of nanoparticles is greater than 0 and less than or equal to 0.

74.

6. The structure according to claim 1, wherein the primary particle diameter of the plurality of nanoparticles is 1 nm or more and 100 nm or less.

7. The structure according to claim 1, wherein the primary particle diameter of said plurality of nanoparticles is 1 nm or more and 10 nm or less.

8. The structure according to claim 1, wherein the plurality of nanoparticles have a hollow structure or a porous structure.

9. The structure of claim 1, wherein the surfaces of said plurality of nanoparticles are coated with amphiphilic molecules.

10. The structure of claim 9, wherein the amphiphilic molecule is at least one of a surfactant molecule, an amino acid molecule, a phospholipid, and a block copolymer of a polyalkylene glycol.

11. The structure of claim 1, wherein the plurality of nanoparticles have organosilane molecules covalently bonded to a surface thereof.

12. The structure of claim 11, wherein the organosilane molecule is a trifunctional molecule.

13. The structure according to claim 11, wherein the organosilane molecule is a compound represented by the following general formula (1) or the following general formula (2): [Chemical Formula 1] R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４ is a methyl group, an ethyl group, a propyl group, or an isopropyl group.

14. The structure of claim 1, wherein each of said plurality of nanoparticles is a metal oxide.

15. The structure of claim 1, wherein each of said plurality of nanoparticles is an oxide of zirconium, titanium, tin, silicon, aluminum, or zinc.

16. The structure of claim 1, wherein each of said plurality of nanoparticles is an oxide of silicon or aluminum.

17. A method for producing a structure, comprising modifying the surface of each of a plurality of nanoparticles with a plurality of alkoxy groups or a plurality of reactive functional groups, and then dispersing the plurality of nanoparticles in a first solvent to non-covalently link the plurality of nanoparticles to each other.

18. A method for producing the structure according to claim 17, comprising modifying the surfaces of each of the nanoparticles with the reactive functional groups by adding an organosilane molecule represented by the following general formula (1) or the following general formula (2): [Chemical formula 2] R １ R ２ R ３ Si(OR ４ )...(1) R １ R ２ R ３ SiCl...(2) (R １ , R ２ , R ３ are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, an octadecyl group, or a carboxypropyl group. ４ is a methyl group, an ethyl group, a propyl group, or an isopropyl group.

19. The method for producing the structure according to claim 17, further comprising removing the first solvent and drying the structure to obtain the structure.

20. A method for producing the structure described in claim 17, which comprises using a molecule capable of forming a three-dimensional polysiloxane skeleton as a precursor, dispersing the precursor in a second solvent, and then preparing the dispersion in which the precursor is dispersed to be acidic or basic, thereby obtaining the plurality of nanoparticles.

21. A structure comprising a plurality of nanomaterials, the plurality of nanomaterials being non-covalently linked to each other without the intervention of any additional components other than the plurality of nanomaterials.

22. A structure comprising a plurality of nanomaterials, the plurality of nanomaterials having a connectivity parameter greater than 0 and less than or equal to 0.80.

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