Structural color paste and preparation method thereof, structural color composite film and preparation method thereof

Abstract

The application provides a structural color paste and a preparation method thereof. The preparation method comprises the following steps: dispersing a polymer, colloidal particles and a strong-polarity colloidal assembly energy barrier regulator in a solvent to directly prepare a structural color paste or prepare a structural color paste after volatilizing part of the solvent; wherein the colloidal particles account for 40-70 vol% of the total volume of the polymer, the colloidal particles and the strong-polarity colloidal assembly energy barrier regulator; the polymer is a solid polymer, and the number of entanglement points of the polymer chain is less than 50; the colloidal particles are silica particles or other particles coated with silica; and the strong-polarity colloidal assembly energy barrier regulator is an oligomer with a molecular number Mn less than 800 Da or a small-molecule substance with a molecular weight M less than 100 Da. The application also provides a structural color composite film and a preparation method thereof. By introducing the strong-polarity oligomer or the high-boiling-point small molecule, the application regulates the thermodynamic interaction between the polymer and the colloidal particles, and reduces the colloidal ordered assembly energy barrier.

Description

Technical Field

[0001] This invention relates to the field of structural color composite materials technology, specifically to a structural color paste and its preparation method, and a structural color composite film and its preparation method. Background Technology

[0002] While traditional pigments are widely used in various fields, their color depends on the selective absorption of light by chromophores, making them prone to fading due to photochemical reactions, affecting product lifespan and aesthetics. Furthermore, the production and use of traditional pigments cause environmental pollution, failing to meet modern environmental protection requirements. In contrast, photonic crystals, as novel optical materials, form photonic band gaps through the periodic arrangement of substances with different refractive indices, selectively reflecting visible light to produce structural colors. They exhibit high brightness, high saturation, iridescent effects, and excellent lightfastness and environmental stability, demonstrating advantages unmatched by traditional pigments. Currently, the preparation of photonic crystal structural color materials typically relies on the self-assembly of monodisperse colloidal nanospheres, but existing technologies present a contradiction between structural color quality and preparation efficiency. The interaction between polymers and colloidal particles increases the energy barrier for ordered assembly, causing colloidal particles to be frozen in a polymer matrix with low order, resulting in only short-range ordered colloidal structures. The final structural color composite film exhibits dull colors and lacks angle dependence, failing to meet practical application requirements. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing structural pigments, comprising: The structure color paste is prepared by dispersing polymers, colloidal particles, and strongly polar colloidal assembly barrier modifiers in a solvent, either directly or by evaporating part of the solvent. In this process, the colloidal particles account for 40-70 vol% of the total volume of the polymer, colloidal particles, and strongly polar colloidal assembly barrier modulator. Compared with one-dimensional photonic crystals, three-dimensional photonic crystal materials formed by solvent evaporation-induced colloidal assembly exhibit significantly reduced repulsive forces between colloidal particles when the volume fraction of colloidal particles is below 30 vol%, leading to a decrease in the orderliness of the colloidal particle arrangement and making it difficult to obtain a high-quality structural color composite film. Conversely, when the volume fraction of colloidal particles is above 70 vol%, the excessively high content of colloidal particles can cause the composite film to become brittle and prone to cracking, making it difficult to obtain a flexible and uniform structural color composite film. The polymer is a solid polymer, and the number of entanglement points of the polymer chain is <50, so as to avoid the excessive chain entanglement of the polymer chain from increasing the energy barrier of the colloidal orderly assembly, thereby reducing the structural color quality of the structural color composite film. The polymer is preferably one or more of polyvinylpyrrolidone, polyacrylic acid, polydiallyl dimethyl ammonium chloride, polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, and polyurethane. The colloidal particles are silica particles or other particles coated with silica. The colloidal particles are preferably one of silica, hollow silica, silica-coated polystyrene, silica-coated iron oxide, and other spherical particles with an outer layer coated with silica. The silica surface coating can ensure that oligomers or high-boiling-point small molecules form a solvent layer on the surface of the colloidal particles, thereby effectively reducing the energy barrier of the ordered assembly of the colloidal particles and balancing the contradiction between structural color quality and preparation efficiency. The strongly polar colloidal assembly barrier modulator has a molecular number M. n Oligomers with a molecular weight <800 Da or small molecules with a molecular weight M <100 Da, wherein the strong polarity is a dielectric constant >15, a dipole moment >1.5D, or a polar component of the solubility parameter >10 (J / cm). 3 ) 1 / 2 Or, the molecular polarity index is >15 kcal / mol. Strong polarity can promote the ionization of silanol groups, which is beneficial to further reduce the energy barrier of colloidal assembly and is the key to the orderly assembly of colloidal particles. The strong polar colloidal assembly energy barrier modifier is preferably one or more of propylene carbonate, ethylene glycol, glycerol, diethylene glycol, triethylene glycol, and polyethylene glycol 200 (Mn=200, 400, 600 Da). The solvent is used to dissolve or swell the polymer and disperse the colloidal particles. The solvent is preferably one or more of water, tetrahydrofuran, N,N-dimethylformamide, methanol, ethanol, isopropanol, dimethyl sulfoxide, N,N-dimethylacetamide, chloroform, dichloromethane, acetone and ethyl acetate. The boiling point of the solvent is preferably less than 150°C to facilitate subsequent solvent removal.

[0004] Furthermore, the colloidal particles have a size range of 80~500nm. Colloidal particles in this size range can modulate visible light with wavelengths of 360~700nm, thereby producing structural colors within the visible light range.

[0005] Furthermore, the boiling point of the solvent is lower than that of the strongly polar colloidal assembly barrier modifier. This prevents the strongly polar colloidal assembly barrier modifier from evaporating preferentially over the solvent during solvent evaporation, which could lead to a decrease in the orderliness of colloidal particles in the resulting structural color paste.

[0006] Furthermore, the absolute value of the refractive index difference between the colloidal particles and the polymer, or between the colloidal particles and the strongly polar colloidal assembly barrier modulator, is ≥0.01. This is because an effective refractive index difference facilitates the generation of optical band gaps, thereby enabling the manipulation of light.

[0007] Furthermore, the solid content in the liquid structural color paste ranges from 5 to 95 wt%. This wide range of solid content (5-95 wt%) not only enriches the rheological properties of the paste, which is beneficial for the processing and molding of structural color materials, but also significantly improves the preparation efficiency of structural color materials.

[0008] Furthermore, the solvent disperses the polymer chains uniformly by dissolving or swelling the polymer, while the colloidal particles are also dispersed in the solvent. The strongly polar colloidal assembly barrier modulator is adsorbed on the surface of the colloidal particles through polarity, forming a composite unit of colloidal particles and strongly polar colloidal assembly barrier modulator.

[0009] A structural color paste prepared according to a method for preparing structural color pastes.

[0010] A method for preparing a structural color composite film involves completely evaporating the solvent in a structural color paste prepared by a structural color paste preparation method to obtain the structural color composite film. The evaporation temperature is preferably 0~150℃, and the evaporation rate is preferably 0.001~1 g / (h·cm). 2 Excessively high evaporation temperatures can cause the strong polar colloidal assembly barrier modifier to volatilize or decompose, making it difficult to obtain high-quality structural color composite films.

[0011] Furthermore, during solvent evaporation, the concentration of the structural pigment increases, and the colloidal particles, polymer chains, and strongly polar colloidal assembly barrier modulators approach each other. The strongly polar colloidal assembly barrier modulators reduce the repulsive force between colloidal particles through strong polarity, while weakening the binding of polymer chains on colloidal particles. This allows the colloidal particles to overcome the assembly barrier and arrange themselves in a long-range ordered manner along the thermodynamically stable direction, forming a three-dimensional periodic structure. The polymer chains bind to the colloidal particles through weak bond interactions and fill the gaps between the colloidal particles, fixing the three-dimensional periodic structure of the colloidal particles.

[0012] A structural color composite film prepared according to a method for preparing structural color composite films.

[0013] The beneficial effects of this invention are as follows: By introducing highly polar oligomers or high-boiling-point small molecules, this invention regulates the thermodynamic interaction between polymers and colloidal particles, significantly reducing the energy barrier for ordered assembly of colloidal particles. This mechanism enables colloidal particles to arrange themselves efficiently and orderly within the polymer matrix, achieving long-range ordered assembly even under conditions of rapid solvent evaporation and high-solids-content structural color pastes. Therefore, this invention can rapidly prepare high-quality structural color composite films with vibrant colors, high saturation, and angle dependence in one step, while maintaining the material's flexibility and good processing performance. Furthermore, the method of this invention is simple to operate and can achieve rapid preparation of large-area structural color composite films, possessing significant potential for large-scale production. By optimizing the formulation and process parameters, the color and properties of the structural color composite film can be flexibly controlled, further expanding its application prospects in fields such as visualization sensing, anti-counterfeiting, and colored coatings. In summary, this invention not only resolves the contradiction between structural color quality and preparation efficiency in existing technologies but also provides a novel technical path for developing high-performance, environmentally friendly structural color materials, possessing significant practical application value and broad development prospects. Specifically: 1. Efficient and Orderly Assembly with Simplified Equipment: This invention effectively regulates the thermodynamic interactions of ordered assembly of colloidal particles by introducing highly polar oligomers or high-boiling-point small molecules, significantly reducing the energy barrier for ordered assembly. Compared with traditional solvent evaporation-induced ordered assembly methods, this invention not only broadens the range of conditions for ordered assembly but also overcomes the limitations of co-assembly kinetics on the construction of ordered structures, thereby significantly improving the production efficiency of high-quality structural color composite films. Furthermore, based on the solution co-assembly strategy, this invention eliminates the need for complex shearing equipment or processes, significantly simplifying the production process and reducing equipment costs and operational complexity.

[0014] 2. Repairability and Green Recycling: In this invention, the weak interaction between colloidal particles and the polymer endows the structural color composite film with unique repairability. When the structural color composite film is damaged during use, this weak interaction allows the material to restore its structure and properties under appropriate conditions (such as heating or applying external force), thereby extending the material's service life. Furthermore, this weak interaction also allows the structural color composite film to be recycled through simple physical or chemical methods after disposal, achieving green recycling and reducing environmental impact.

[0015] 3. Expanded Application Areas: This invention prepares brightly colored structural color pastes through a controlled co-assembly thermodynamic method. These pastes can not only be used to produce brightly colored structural color film materials via coating techniques (such as blade coating and screen printing), but also to prepare structural color materials with specific shapes using extrusion printing, electrospinning, and other equipment. This diversified preparation method greatly expands the application areas of structural color materials. Specifically, structural color film materials can be widely used in optical coatings, display technology, sensors, and other fields; while bulk structural color materials can be used in decorative materials, smart packaging, biomedicine, and other scenarios. By adjusting the types of colloidal particles and polymers and their interactions, the material properties can be further optimized to meet the specific needs of different application scenarios. Attached Figure Description

[0016] Figure 1 These are scanning electron microscope images of the silica particles used in Examples 1-7.

[0017] Figure 2 The reflectance spectra are those of the structural color composite films prepared in Examples 1-7.

[0018] Figure 3 These are optical photographs of the structural color composite films prepared in Examples 1-4.

[0019] Figure 4 The reflectance spectra are those of the structural color composite films in Comparative Examples 1-4.

[0020] Figure 5 Optical photographs of the structural color composite films in Comparative Examples 1-4.

[0021] Figure 6 The image shows a scanning electron microscope image of the structural color composite film in Comparative Example 2.

[0022] Figure 7 This is a schematic diagram of the invention. Detailed Implementation

[0023] Unless otherwise specified, all raw materials used below are commercially available products, and all methods used below are conventional methods in this field.

[0024] Example 1 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =58kDa, polymer chain entanglement number is 15), silica gel particles and polyethylene glycol 200 (number of molecules) M n =200Da, structural formula is The dielectric constant (at 25℃) is 16.3, the dipole moment (at 25℃) is 2.3D, and the polar component of the solubility parameter is 8.6 (J / cm²). 3 ) 1 / 2 (The molecular polarity index is 18 kcal / mol) is dispersed in water at a volume ratio of 1:9:10 to form a liquid structure color paste with a solid content of 90 wt%. (2) The above liquid structural color paste is uniformly coated onto the substrate surface by scraping, and then applied at 60°C. o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.056 g / (h·cm). 2 This process rapidly removes moisture, ultimately yielding a structural color composite film with a reflectance peak intensity as high as 30%. Reflectance peak intensity is defined as the difference between the peak and valley intensities of the reflectance spectrum.

[0025] Scanning electron microscope images of silica particles, as shown below. Figure 1 As shown, the diameter is 80~500nm. The reflection peak intensity of the structural color composite film obtained in Example 1 is shown in [reference needed]. Figure 2 (a) Optical photographs are shown Figure 3 (a).

[0026] Example 2 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =58kDa, polymer chain entanglement points are 15), silica gel particles and glycerol (structural formula is The dielectric constant (at 25℃) is 42.5, the dipole moment (at 25℃) is 2.6D, and the polar component of the solubility parameter is 12.1 (J / cm²). 3 ) 1 / 2 (The molecular polarity index is 30 kcal / mol) is dispersed in water at a volume ratio of 1:9:10 to form a liquid structure color paste with a solid content higher than 90 wt%. (2) Then, the above-mentioned liquid structural color paste is uniformly coated onto the surface of the substrate by scraping, and then at 60°C. o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.056 g / (h·cm). 2 To quickly remove the moisture, a structural color composite film with a reflection peak intensity of up to 30% is finally obtained.

[0027] The reflection peak intensity of the structural color composite film obtained in Example 2 is shown in [reference needed]. Figure 2 (b), Optical photographs are shown in 3(b).

[0028] Example 3 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =58kDa, polymer chain entanglement points are 15), silica gel particles and diethylene glycol (structural formula is The dielectric constant (at 25℃) is 31.9, the dipole moment (at 25℃) is 2.5D, and the polar component of the solubility parameter is 10.2 (J / cm²). 3 ) 1 / 2 (The molecular polarity index is 25 kcal / mol) is dispersed in water at a volume ratio of 1:9:10 to form a liquid structure pigment with a solid content of more than 90 wt%.

[0029] (2) Then, the above-mentioned liquid structural color paste is uniformly coated onto the surface of the substrate by scraping, and then at 60°C. o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.056 g / (h·cm). 2 To quickly remove the moisture, a structural color composite film with a reflection peak intensity of up to 30% is finally obtained.

[0030] The reflectance spectrum of the structural color composite film obtained in Example 3 is shown in [reference needed]. Figure 2 (c), Optical photographs are shown in 3(c).

[0031] Example 4 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =58kDa, polymer chain entanglement points are 15), silica gel particles and triethylene glycol (structural formula is The dielectric constant (at 25℃) is 23.7, the dipole moment (at 25℃) is 2.4D, and the polar component of the solubility parameter is 9.8 (J / cm). 3 ) 1 / 2 (With a molecular polarity index of 22 kcal / mol) dispersed in water at a volume ratio of 1:9:10 to form a liquid structure color paste with a solid content higher than 90 wt%. (2) Then, the above-mentioned liquid structural color paste is uniformly coated onto the surface of the substrate by scraping, and then at 60°C. o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.056 g / (h·cm). 2To quickly remove the moisture, a structural color composite film with a reflection peak intensity of up to 30% is finally obtained.

[0032] The reflectance spectrum of this structural color composite film is shown below. Figure 2 As shown in (d), the optical photograph is shown in 3(d).

[0033] Example 4 was prepared using the same method as Example 1. Examples 2 to 4 mainly adjusted the types of oligomers or high-boiling-point small molecules. Specifically, the polyethylene glycol 200 used in Example 1 (molecule count...) M n =200Da) was replaced with glycerol, diethylene glycol, and triethylene glycol, respectively. Under conditions of rapid solvent evaporation, these modified materials were still able to successfully prepare structural color composite films with a reflection peak intensity as high as 30%, further demonstrating the broad applicability of this method in terms of material selection.

[0034] Example 5 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =58kDa, polymer chain entanglement number is 15), silica gel particles and polyethylene glycol 200 (number of molecules) M n =200Da) was dispersed in water at a volume ratio of 1:9:10 to form a liquid structure pigment with a solid content higher than 90wt%; (2) Then, the above-mentioned liquid structural color paste is uniformly coated onto the surface of the substrate by scraping, and then at 90°C... o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.245 g / (h·cm). 2 This process rapidly removes moisture, ultimately yielding a structural color composite film with a reflectance peak intensity as high as 30%, such as... Figure 2 As shown in (e).

[0035] Example 6 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =58kDa, polymer chain entanglement number is 15), silica gel particles and polyethylene glycol 200 (number of molecules) M n =200Da) was dispersed in water at a volume ratio of 1:9:10 to form a liquid structure pigment with a solid content higher than 90wt%; (2) Then, the above-mentioned liquid structural color paste is uniformly coated onto the surface of the substrate by scraping, and then at 30°C... o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.004 g / (h·cm). 2 To quickly remove the moisture, a structural color composite film with a reflection peak intensity of up to 30% is finally obtained.

[0036] Compared to Example 1, Examples 5 and 6 are identical in material selection, but the solvent evaporation rate is adjusted. Specifically, the solvent evaporation rate of Example 5 is 0.245 g / (h·cm). 2 The rate is 0.056 g / (h·cm) higher than the original rate. 2 The solvent evaporation rate in Example 6 was 0.004 g / (h·cm). 2 The rate was 0.056 g / (h·cm) lower than the original rate. 2 Experimental results show that even at the adjusted evaporation rate, structural color composite films with a reflection peak intensity as high as 30% can still be successfully prepared, such as... Figure 2 As shown in (f). However, in existing technologies, to obtain a film with a reflection peak intensity of 30%, the corresponding evaporation rate must be less than 0.00275 g / (h·cm). 2 This indicates that by optimizing the composition of the structural color paste and regulating the co-assembly thermodynamics, the present invention effectively reduces the dependence of the colloidal structure on assembly kinetics, breaks through the strict limitations on kinetic conditions in traditional co-assembly methods, and thus achieves the efficient construction of high-quality structural color composite films.

[0037] Example 7 A method for preparing a structural color composite film includes the following steps: (1) Polyvinylpyrrolidone (molecular weight) M w =24kDa, polymer chain entanglement points are 6), silica gel particles and polyethylene glycol 200 (number of molecules) M n =200Da) was dispersed in water at a volume ratio of 1:9:10 to form a liquid structure pigment with a solid content higher than 90wt%; (2) Then, the above-mentioned liquid structural color paste is uniformly coated onto the surface of the substrate by scraping, and then at 60°C. o The coated structural pigment was dried under condition C, at which point the evaporation rate was 0.056 g / (h·cm). 2 To quickly remove the moisture, a structural color composite film with a reflection peak intensity of up to 30% is finally obtained.

[0038] The implementation conditions were the same as in Example 1, with the only difference in Example 7 being the molecular weight of polyvinylpyrrolidone (PVP). M w The value was adjusted to 24 kDa, corresponding to a polymer chain entanglement number of 6. Experimental results show that even with polyvinylpyrrolidone (PVP) having a low chain entanglement number (6), structural color composite films with a reflection peak intensity as high as 30% can still be successfully prepared, such as... Figure 2 As shown in (g). This demonstrates that polyvinylpyrrolidone with a low number of chain entanglements can also achieve the construction of high-quality structural color composite films in this invention.

[0039] Comparative Example 1 This comparative experiment used the same preparation method and conditions as Example 1, the only difference being the polyvinylpyrrolidone (molecular weight) used. M w =1300kDa) corresponds to 330 polymer chain entanglement points, which is much higher than 50. Experimental results show that the intensity of the reflection peak of the obtained structural color composite film is about 10% lower ( Figure 4 (a)), Optical photographs are shown Figure 5 (a) The reason is that high molecular weight polyvinylpyrrolidone has more chain entanglements, which increases the energy barrier for ordered assembly of the colloidal molecules, reduces the structural color quality of the composite film, and results in a white appearance of the obtained composite film. This comparative experiment highlights the key role of polymer molecular weight in the co-assembly process.

[0040] Comparative Example 2 This comparative experiment used the same preparation method and conditions as Example 1, the only difference being that polyethylene glycol 200 was not introduced into the structural color paste. The experimental results showed that the structural color composite film without polyethylene glycol 200-induced structured color exhibited a significantly reduced degree of ordered arrangement of colloidal particles within the polymer matrix, as illustrated in the scanning electron microscope images. Figure 6 As shown, this leads to a decrease in the intensity of the composite film's reflection peak, resulting in a white appearance. See the optical photograph. Figure 5 (b) Reflectance is shown in [reference]. Figure 4 (b) This phenomenon fully demonstrates that the introduction of polar oligomers or high-boiling-point small molecules is crucial for regulating the thermodynamics of co-assembly and achieving the preparation of high-quality and efficient structural color composite films, which is also the core innovation of the structural color paste of this invention.

[0041] Comparative Example 3 This comparative experiment used the same preparation method and conditions as Example 1, the only difference being that the volume ratio of polyvinylpyrrolidone, polyethylene glycol 200, and silica particles in the structural color paste was 7:63:30, meaning that silica accounted for 30% of the volume in the composite film. Experimental results showed that the reflection peak intensity of the obtained structural color composite film was less than 15%. Figure 4(c) The reflection peak is relatively broad, the structural color saturation is low, and the colors are not vivid. See the optical photograph. Figure 5 (c). This indicates that the volume fraction of silica is one of the key factors in obtaining high-quality structural color composite films.

[0042] Furthermore, the absolute value of the refractive index difference between the colloidal particles and the polymer, or between the colloidal particles and the strongly polar colloidal assembly barrier modulator, is ≥0.01. This is because an effective refractive index difference is beneficial for the generation of optical band gaps, thereby achieving light modulation. The refractive indices of the colloidal particles, polymer, and strongly polar colloidal assembly barrier modulator involved in the above embodiments are shown in the table below. like Figure 7 The diagram shown is a schematic of the present invention. The biggest obstacle to the spontaneous ordered arrangement of colloidal particles in a polymer matrix is ​​the assembly energy barrier (including the repulsive force between colloidal particles and the binding force of polymer chains on colloidal particles). The present invention overcomes this barrier by using a strongly polar colloidal assembly energy barrier regulator: First, the strongly polar colloidal assembly energy barrier regulator (such as glycerol, polyethylene glycol 200) has strong polar characteristics such as high dielectric constant (>15) and high dipole moment (>1.5D), which can promote the ionization of silanol groups on the surface of colloidal particles (such as silica), reduce the electrostatic repulsion between particles, and at the same time form a solvation layer on the surface of colloidal particles through polar adsorption, reducing the van der Waals repulsion between particles and making it easier for particles to approach each other; Second, the selected polymer (such as polyvinylpyrrolidone) has less than 50 polymer chain entanglement points, with a low degree of chain entanglement, and the strongly polar regulator competes with the polymer chain for adsorption on the surface of colloidal particles through polar interaction, reducing the physical encapsulation and binding of polymer chains on colloidal particles, and providing space for particle movement. The formation of three-dimensional periodic structures depends on the synergistic effect of concentration gradient driving and thermodynamic stability tendency. When the solvent in the structural pigment evaporates, the concentration of the pigment gradually increases, and the spatial distance between colloidal particles, polymer chains, and strong polar regulators continuously decreases. The interaction between particles (attraction / repulsion) gradually becomes dominant, forcing the system to seek the stable state with the lowest energy. The geometric characteristics of colloidal particles make them tend to form close-packed structures, such as face-centered cubic and body-centered cubic packing. This arrangement can minimize the free energy of the system and is the most thermodynamically stable state. The presence of strong polar regulators gives the particles sufficient fluidity to overcome the assembly energy barrier, rather than being frozen in a disordered state by the polymer matrix, thus completing a long-range (micrometer-level and above) ordered arrangement along the thermodynamically stable direction.

[0043] After colloidal particles form a three-dimensional ordered structure, polymer chains bind to the surface of the colloidal particles through weak bond interactions (such as hydrogen bonds and van der Waals forces) and fill the gaps between the particles, forming a framework-filler structure. The filling of polymer chains prevents the ordered structure from colloidal particles from colloidally colloidally colloidally collapsing due to thermal motion or external forces in subsequent processes; the weak bond interactions ensure structural stability while retaining a certain degree of flexibility, as the weak bonds can reform under certain conditions, thus providing a degree of repairability.

[0044] In summary, this invention, by introducing highly polar oligomers or high-boiling-point small molecules, regulates the thermodynamic interactions of the ordered assembly of colloidal particles, achieving efficient and orderly arrangement of colloidal particles in a polymer matrix, thereby preparing a brightly colored and responsive structural color composite film. This method requires no complex shearing equipment or processes, offering advantages such as simple equipment, easy scale-up, and low energy consumption. Furthermore, this invention endows the structural color composite film with repairable and recyclable properties, further expanding its application areas and demonstrating significant economic and environmental benefits.

[0045] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing a structural color paste, characterized in that, include: The structure color paste is prepared by dispersing polymers, colloidal particles, and strongly polar colloidal assembly barrier modifiers in a solvent, either directly or by evaporating part of the solvent. The colloidal particles comprise 40-70% vol% of the total volume of the polymer, colloidal particles, and the strongly polar colloidal assembly barrier modulator. The polymer is a solid polymer, and the number of entanglement points of the polymer chain is <50. The colloidal particles are silica particles or other particles coated with silica. The strongly polar colloidal assembly barrier modulator has a molecular number M. n Oligomers with a molecular weight <800 Da or small molecules with a molecular weight M <100 Da, wherein the strong polarity is a dielectric constant >15, a dipole moment >1.5D, or a polar component of the solubility parameter >10 (J / cm). 3 ) 1 / 2 Or the molecular polarity index is >15 kcal / mol; The solvent is used to dissolve or swell the polymer and disperse the colloidal particles.

2. The method for preparing structural pigments according to claim 1, characterized in that: The colloidal particle size ranges from 80 to 500 nm.

3. The method for preparing structural pigments according to claim 1, characterized in that: The boiling point of the solvent is lower than that of the strongly polar colloidal assembly barrier modulator.

4. The method for preparing structural pigments according to claim 1, characterized in that: The absolute value of the difference in refractive index between the colloidal particles and the polymer, or between the colloidal particles and the strongly polar colloidal assembly barrier modulator, is ≥0.

01.

5. The method for preparing structural pigments according to claim 1, characterized in that: The solid content in the structural pigment ranges from 5 to 95 wt%.

6. The method for preparing structural pigments according to claim 1, characterized in that: The solvent disperses the polymer chains uniformly by dissolving or swelling the polymer, while the colloidal particles are also dispersed in the solvent. The strongly polar colloidal assembly barrier modulator is adsorbed on the surface of the colloidal particles through polarity, forming a composite unit of colloidal particles and strongly polar colloidal assembly barrier modulator.

7. The structural color paste prepared by any one of the structural color paste preparation methods according to claims 1 to 6.

8. A method for preparing a structural color composite film, characterized in that, By completely evaporating the solvent in the structural color paste described in claim 7, a structural color composite film is obtained.

9. The method for preparing the structural color composite film according to claim 8, characterized in that: During solvent evaporation, the concentration of the structural pigment increases, and colloidal particles, polymer chains, and strongly polar colloidal assembly barrier modulators approach each other. The strongly polar colloidal assembly barrier modulators reduce the repulsive force between colloidal particles through strong polarity, while weakening the binding of polymer chains on colloidal particles. This allows colloidal particles to overcome the assembly barrier and arrange themselves in a long-range ordered manner along the thermodynamically stable direction, forming a three-dimensional periodic structure. The polymer chains bind to the colloidal particles through weak bond interactions and fill the gaps between the colloidal particles, fixing the three-dimensional periodic structure of the colloidal particles.

10. The structural color composite film prepared by the method of preparing the structural color composite film according to claim 8 or 9.

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