A structural color polymer composite material based on photonic crystals and its preparation and application

Abstract

This invention relates to a structural color polymer composite material based on photonic crystals, its preparation, and its application, belonging to the interdisciplinary field of polymer material processing and photonic crystals. A premix of monodisperse photonic crystal microspheres and thermoplastic polymer resin is fed into a twin-screw extruder for melt blending and extrusion to obtain a photonic crystal polymer composite precursor. Then, an external rheological field is applied, causing the monodisperse photonic crystal microspheres to self-assemble in the thermoplastic polymer resin, forming a periodic lattice and a short-range ordered glassy structure, resulting in a polymer composite material with stable structural color. This invention utilizes the strong shearing and kneading effects of the twin-screw extruder to achieve uniform dispersion of photonic crystal microspheres in the polymer matrix, while preserving the periodic ordered structure of the microspheres, thus preparing a photonic crystal polymer composite material with both excellent optical and mechanical properties. This invention solves the technical problems of microsphere agglomeration, poor mechanical properties, and difficulty in large-area preparation in traditional photonic crystal preparation.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing and photonic crystal interdisciplinary technology, and more specifically, to a structural color polymer composite material based on photonic crystals and its preparation and application. Background Technology

[0002] Photonic crystals, as functional materials with periodic refractive index structures, possess unique advantages in terms of the structural colors generated through Bragg scattering. These advantages include being clean and environmentally friendly, having vibrant colors, being resistant to fading, and responding to external stimuli (temperature, pressure, light, etc.). They hold irreplaceable application value in fields such as color display, sensing and detection, information encryption, and biometrics. However, traditional photonic crystal fabrication techniques suffer from numerous bottlenecks, severely limiting their industrial application. First, poor mechanical properties are the core problem. Traditional photonic crystals are mainly prepared through the self-assembly of colloidal microspheres (such as gravity sedimentation and vertical sedimentation methods). The microspheres only have point contact and lack effective connections, resulting in materials that are prone to breakage and have insufficient stability. Although researchers have tried to improve this through chemical cross-linking and polymer filling, these methods are complicated, have poor universality, and easily destroy the ordered structure of the microspheres.

[0003] Secondly, it is difficult to guarantee the uniformity of microsphere dispersion. The optical performance of photonic crystals depends on the periodic and ordered arrangement of microspheres, but traditional blending processes (such as melt stirring) are difficult to achieve uniform dispersion of nanoscale microspheres in polymer matrices, which easily leads to agglomeration, destroying the periodic structure and causing distortion or disappearance of structural color.

[0004] Furthermore, large-scale fabrication is difficult. Existing precision machining equipment is expensive and has low production efficiency, while spin coating and spray coating methods are limited by substrate size and have uneven thickness, which cannot meet the industrial production requirements for low cost and large volume.

[0005] Furthermore, traditional photonic crystal fabrication processes often involve complex chemical treatments or solvent use, posing environmental pollution risks and contradicting the trend of green manufacturing. Although twin-screw blending extrusion technology has been widely used in the preparation of polymer composites, offering advantages such as uniform mixing, high efficiency, and scalability, its application in photonic crystal composites presents a significant technical challenge: how to preserve the periodic structure of microspheres and prevent agglomeration under strong shear conditions.

[0006] Therefore, developing a blending extrusion process that can achieve uniform dispersion of photonic crystal microspheres, retain ordered structure, improve mechanical properties, and is environmentally friendly, efficient, and scalable is of great significance for promoting the industrial application of photonic crystals. Summary of the Invention

[0007] This invention aims to overcome the aforementioned deficiencies of existing technologies and provide a structural color polymer composite material based on photonic crystals, along with its preparation process and applications. The invention involves feeding a premix of monodisperse photonic crystal microspheres and thermoplastic polymer resin into a twin-screw extruder for melt blending and extrusion, yielding a photonic crystal polymer composite precursor. An external rheological field is applied to the composite precursor. Under the synergistic effect of the relaxation of thermoplastic polymer resin chains and the Brownian motion of the monodisperse photonic crystal microspheres, the microspheres self-assemble within the resin to form a periodic lattice and a short-range ordered glassy structure, resulting in a polymer composite material with stable structural color. This invention utilizes the strong shearing and kneading effects of the twin-screw extruder to achieve uniform dispersion of the photonic crystal microspheres in the polymer matrix, while preserving the periodic ordered structure of the microspheres, thus preparing a photonic crystal polymer composite material with both excellent optical and mechanical properties. This invention solves the technical problems of microsphere agglomeration, poor mechanical properties, and difficulty in large-area preparation in traditional photonic crystal manufacturing processes.

[0008] According to a first aspect of the present invention, a method for preparing a structural color polymer composite material based on a photonic crystal is provided, comprising the following steps: S1: Mix monodisperse photonic crystal microspheres and thermoplastic polymer resin to obtain a premix; S2: The premix obtained in step S1 is fed into a twin-screw extruder for melt blending and extrusion to obtain a photonic crystal polymer composite precursor. S3: An external rheological field is applied to the composite precursor obtained in step S2. Under the synergistic effect of the relaxation of thermoplastic polymer resin chain segments and the Brownian motion of monodisperse photonic crystal microspheres, the monodisperse photonic crystal microspheres self-assemble in the thermoplastic polymer resin to form a periodic lattice and a short-range ordered glassy structure, thereby obtaining a polymer composite material with a stable structural color.

[0009] Preferably, in step S3, the external rheological field is a self-confining pressure field, an oscillating shear field, or a uniaxial tensile field; the confining pressure field is achieved by hot pressing on a flat plate; the oscillating shear field is achieved by bending-induced oscillating shearing through a multi-roll calendering system.

[0010] Preferably, the monodisperse photonic crystal microspheres are at least one of copolymer microspheres formed by copolymerization of ethyl acrylate and styrene, polystyrene microspheres, and polymethyl methacrylate microspheres.

[0011] Preferably, the thermoplastic polymer resin is at least one selected from polypropylene, polyethylene terephthalate, polylactic acid, polyethylene, nylon, and thermoplastic polyurethane.

[0012] Preferably, in the premix, the mass of the monodisperse photonic crystal microspheres is 40%-60% of the mass of the thermoplastic polymer resin.

[0013] Preferably, the extrusion temperature of the twin-screw extruder is 10°C-50°C higher than the melting point of the thermoplastic polymer resin, and the screw speed of the twin-screw extruder is 30 rpm-60 rpm.

[0014] According to another aspect of the present invention, a structural color polymer composite material based on photonic crystals is provided.

[0015] According to another aspect of the present invention, a structural color fabric based on structural color polymer is provided, wherein the surface of the structural color fabric is covered by a structural color film composed of the aforementioned photonic crystal-based structural color polymer composite material through a hot pressing process.

[0016] According to another aspect of the present invention, the application of the aforementioned photonic crystal-based structural color polymer composite material as a consumable for structural color 3D printing is provided.

[0017] According to another aspect of the present invention, the application of the aforementioned photonic crystal-based structural color polymer composite material in mechanochromic motion monitoring wearable devices, anti-counterfeiting packaging, security tags, or infrared reflective films is provided.

[0018] In summary, the significant advantages of the above-mentioned technical solutions conceived in this invention compared with the prior art are reflected in the following aspects: (1) This invention provides a structural color polymer composite material based on photonic crystals and its preparation process. It utilizes twin-screw extrusion rheological processing technology, employing the distributed mixing function of a twin-screw extruder to prepare a polymer masterbatch intermediate containing monodisperse microspheres. Subsequently, an external rheological field is used to drive the microspheres to undergo secondary assembly in a viscoelastic matrix, forming a periodic lattice that generates structural color. By controlling the rheological field to induce anisotropic or quasi-crystalline arrangement of monodisperse microspheres in a thermoplastic resin matrix, a functional composite material with both high mechanical strength and optical responsiveness is prepared. This functional composite material, capable of large-scale production and possessing tunable structural color properties, significantly expands the application scenarios of photonic crystal materials.

[0019] (2) The present invention has the beneficial effects of excellent microsphere dispersion uniformity and periodic structure retention. The photonic crystal microspheres are dispersed uniformly in the polymer matrix to the nanoscale, with an aggregate content of ≤5% (the proportion of aggregates with a particle size ≥1 μm), and the microspheres maintain a face-centered cubic or body-centered cubic periodic arrangement, with a structural color wavelength deviation of ≤±10nm and a reflectivity of ≥50%.

[0020] (3) This invention is adaptable to multiple scenarios. The structural color polymer based on photonic crystal manufactured by this invention can be processed by two post-processing methods. The functional fabric obtained by hot pressing fabric post-processing has excellent sun resistance and water washing fastness, and there is no pollution from traditional printing and dyeing wastewater; 3D printing post-processing can prepare complex structure functional devices, support personalized customization and material recycling, and is suitable for multiple fields such as textiles, electronics, and sensing, solving the problem of single application scenarios of traditional processes.

[0021] (4) This invention is environmentally friendly, efficient and can be mass-produced. The entire process does not use solvents and only involves the mixing and melting of solid raw materials. The wastewater and waste gas emissions are zero, which meets the national green manufacturing standards. The twin-screw extrusion technology has high production efficiency and high precision for film products, which is significantly better than the production efficiency and dimensional control precision of traditional processes.

[0022] (5) The processing technology described in this invention is applicable to a variety of thermoplastic polymers (PP, PET, PE, etc.) and photonic crystal microspheres (P(EA-co-St), PS, PS@SiO2, PMMA, etc.). By simply adjusting the extrusion and hot pressing parameters according to the melting characteristics of the resin, rich and stable colors can be obtained by selecting different combinations of resins and pigments. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the present invention.

[0024] Figure 2 This is a 500x magnified SEM image of the structural color polymer composite material of this invention.

[0025] Figure 3 This is a photograph of the present invention after hot pressing and dyeing.

[0026] Figure 4 These are photographs of the 3D-printed model of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Figure 1 This is a flowchart of the preparation process of the present invention. The present invention provides a method for preparing a structural color polymer composite material based on photonic crystals, comprising the following steps: 1. Raw material preparation and pretreatment: (1) Monodisperse photonic crystal microspheres (particle size 100nm-500nm, PDI≤0.05) are selected as optical functional components. This particle size range can generate visible light band structural colors of 400nm-700nm through Bragg scattering, covering basic colors such as red, green, and blue. Thermoplastic polymer resin is selected as matrix support material, which needs to meet the requirements of good melt flow and good compatibility with microspheres.

[0029] (2) Vacuum freeze-dry the photonic crystal microspheres (temperature -50℃ to -30℃, vacuum degree ≤10Pa, drying time 12h-24h) to remove adsorbed moisture; the thermoplastic polymer resin needs to be dried by blowing (temperature 70℃-110℃, drying time 6h-12h) to remove moisture and avoid the generation of bubbles during extrusion that affect the material density.

[0030] (3) Mix the pretreated microspheres and resin evenly according to the predetermined mass ratio so that the microspheres are evenly attached to the surface of the resin particles to form a uniformly dispersed premix, thus avoiding local agglomeration of microspheres during subsequent extrusion.

[0031] 2. Twin-screw co-extrusion: A co-rotating twin-screw extruder is selected, with a segmented screw configuration consisting of a conveying section, a weak shear section, a strong shear section, and a homogenization section. The strong shear section contains 3-5 sets of staggered kneading blocks. A gradient temperature increase mode is used for extrusion. The feeding zone temperature is 10°C higher than the resin melting point, the melting zone temperature gradually rises to more than 30°C above the resin melting point, the mixing zone temperature is maintained at the resin melting point of 40°C, and the die head temperature is consistent with the mixing zone temperature. The screw speed is adjusted according to the microsphere particle size: 45-60 rpm for particles of 100nm-200nm, and 30-45 rpm for particles of 300nm-500nm. This allows the mixed resin to be co-extruded with the photonic crystal microspheres, yielding a filamentous one-dimensional photonic crystal copolymer.

[0032] 3. Apply an external rheological field: (1) Post-treatment of hot-pressed fabric: ① Select natural fiber fabrics (cotton, linen) or synthetic fiber fabrics (polyester, nylon, polypropylene) that can withstand heat and pressure temperatures, cut them to the target size, remove surface impurities and moisture (dry at 60℃ for 30 minutes), and ensure that the fabric is flat and wrinkle-free.

[0033] ② Evenly spread the cooled and shaped composite intermediate (shredded strip, particles, or filaments) onto the fabric surface, with a coverage of 50g / m²-300g / m². Place a high-temperature resistant release film (such as polyimide PI film) between the intermediate and the pressure plate of the hot pressing equipment to prevent the molten polymer from sticking to the pressure plate. At the same time, place a flat stainless steel template to ensure uniform pressure transmission. Set the hot pressing temperature to -10℃ to +30℃ of the resin melting point (to ensure that the resin softens or melts, so that the photonic crystal microspheres are fixed to the fabric fibers), the pressure range is 3MPa-10MPa, and the holding time is 10min-15min. The thermal expansion effect promotes the tight bonding between the microspheres and the fabric fibers, so that the photonic crystal microspheres are coated with polymer and fixed to the fiber surface or inside.

[0034] ③ Cooling and finishing: After hot pressing, the fabric is allowed to cool naturally to room temperature. After depressurization, the release film and template are removed. The fabric is then routinely finished to obtain a photonic crystal functional fabric with uniform color and stable structural color.

[0035] (2) Post-processing of 3D printing: ① Pre-treat the composite filament (dry at 60℃-80℃ for 2-4 hours to remove adsorbed moisture); design the target device model using CAD software, import it into slicing software (such as Modellight v3), and set the printing parameters: nozzle temperature 175℃-220℃ (adjust according to resin type, PP corresponds to 190℃-210℃, PLA corresponds to 175℃-195℃), heated bed temperature 40℃-70℃, layer thickness 0.2mm-0.5mm, fill rate 25%-100%, and printing speed 10mm / s-40mm / s.

[0036] ② Feed the composite filament into the FDM 3D printer's feed inlet, run the program according to the .gcode format slicing file, and melt the filament through the nozzle heating (preserving the short-range ordered structure of the microspheres), building up layer by layer; multi-color devices can be achieved by pausing the printing process and changing different colored composite filaments. After printing, maintain the heated bed temperature for 5-10 minutes, then allow it to cool naturally to room temperature to avoid interlayer cracking and residual internal stress caused by rapid cooling.

[0037] ③ Perform surface finishing on the finished product: remove the surface support structure and burrs from the printed part, and lightly polish it if necessary to ensure a smooth surface without damaging the periodic structure of the microspheres.

[0038] Specifically, the key parameter design and principle of the process described in this invention include the following three aspects: (1) Raw material proportioning design: The mass of photonic crystal microspheres should account for 40%-60% of the polymer resin mass. When the proportion is less than 40%, the microspheres are sparsely distributed in the matrix and cannot form a continuous periodic structure, resulting in insufficient structural color intensity (reflectivity ≤30%). When the proportion is greater than 60%, the distance between microspheres is too small, the van der Waals attraction is significantly enhanced, and agglomeration is likely to occur. This will also lead to a decrease in the melt flowability of the composite material (melt index ≤5g / 10min), making it difficult to extrude and mold, and at the same time, it will lead to a decrease in the mechanical properties of the material. A proportion of 40%-60% can enable the microspheres to form a uniform periodic arrangement, while ensuring that the melt flowability meets the extrusion requirements.

[0039] (2) Design principle of twin-screw extrusion parameters: ①Temperature parameters: The extrusion temperature should be 10℃-40℃ higher than the resin melting point and 30℃ lower than the resin thermal decomposition temperature. This range can ensure that the resin melts completely to form a continuous phase and avoid the degradation of microspheres caused by high temperature (e.g., the thermal decomposition temperature of PS microspheres is about 250℃, so the extrusion temperature should not exceed 220℃).

[0040] ② Screw speed: A speed range of 30rpm-60rpm can control the shear rate of the melt in the barrel to 100s. - ¹-500s - ¹, this shear strength can both break up microsphere aggregates without destroying the periodic structure of the microspheres themselves.

[0041] Extruded materials can be filaments, strips, films, or granules. Granules are easy to store and transport, and can be directly spread or remelted into the desired shape when used.

[0042] (3) Design principle of applying external rheological field parameters: ① Hot-pressing parameter design: The temperature range of -10℃ to +30℃ is within the resin's elastic to molten state. At this temperature, the resin has good fluidity, and under pressure, it can promote the rearrangement of microspheres to form a more regular periodic structure, while avoiding excessive temperature that could lead to microsphere deformation or resin degradation. A pressure of 3MPa-10MPa ensures close contact between the microspheres and the resin matrix, reduces interfacial voids, and improves mechanical strength. However, insufficient pressure (<5MPa) will result in irregular microsphere arrangement, while excessive pressure (>15MPa) may cause microsphere breakage.

[0043] ② 3D printing parameters: The nozzle temperature needs to match the resin melting characteristics. Too low a temperature will result in insufficient filament flow and poor interlayer bonding, while too high a temperature will easily damage the microsphere structure. Layer thickness and infill rate directly affect the mechanical properties of the device. The smaller the layer thickness and the higher the infill rate, the stronger the tensile strength. Printing speed is negatively correlated with interlayer bonding. The slower the speed, the more sufficient the heat transfer between layers, and the stronger the bonding.

[0044] In some embodiments, the monodisperse photonic crystal microspheres are selected from at least one of P(EA-co-St) microspheres (polymer microspheres formed by copolymerization of ethyl acrylate (EA) and styrene (St), polystyrene (PS) microspheres, and polymethyl methacrylate (PMMA) microspheres, with a microsphere particle size of 100 nm-500 nm and a polydispersity index (PDI) ≤0.05.

[0045] In some embodiments, the plastic polymer resin is selected from at least one of polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), polyethylene (PE), nylon (PA), and thermoplastic polyurethane (TPU).

[0046] In some embodiments, the monodisperse photonic crystal microspheres account for 40%-60% of the mass of the resin polymer material in the premix; a dispersing agent is added during the formation of the premix, specifically at least one of silane coupling agent, calcium stearate or polyethylene wax, with a mass percentage of 0.1%-2%.

[0047] In some embodiments, the temperature setting range of the twin-screw extrusion is 10°C to 50°C higher than the melting point of the selected thermoplastic polymer resin, and the screw speed is 30 rpm to 60 rpm.

[0048] In some embodiments, the confined pressure field is achieved by hot pressing of a flat plate. The process conditions are: the temperature is in the viscous flow range of the resin, that is, the melting point temperature minus 10°C to plus 30°C, the pressure is 3 MPa-10 MPa, and the holding time is 5 min-15 min, so that the microspheres form a layered orderly arrangement in the direction perpendicular to the pressure during melt flow.

[0049] In some embodiments, the oscillating shear field is achieved by bending-induced oscillating shear (BIOS) of the composite precursor film in a multi-roll calendering system, using shear force to eliminate lattice defects.

[0050] The structural color polymer composite material prepared by this invention contains a periodically arranged array of microspheres inside the material; when irradiated by incident light, the surface of the material exhibits a structural color that conforms to the Bragg diffraction law.

[0051] The structural color polymer composite material prepared by this invention can be used in fields such as color display, sensing and detection, information encryption, and biometrics, and has broad application prospects.

[0052] A structural color fabric based on structural color polymers, wherein a structural color film composed of the composite material is coated on the surface of the fabric by a hot pressing process, wherein the microspheres in the film are cross-linked polystyrene microspheres and the matrix is ​​polyethylene terephthalate; the coverage of the film on the fabric surface is 50 g / m² to 300 g / m², and the content of organic pigments or dyes is zero.

[0053] The fabric thermopressing and dyeing process based on twin-screw extrusion provided by this invention, with its core advantages such as environmental friendliness, high color fastness, and stable coloring, is particularly suitable for the following textile fields with high requirements for performance, environmental protection, or durability: (1) Intelligent force-induced color-changing motion monitoring wearable device: Utilizing the flexible structural color film or fiber prepared in this invention (such as using TPU or SEBS as the matrix), intelligent sports protective gear (such as knee pads, resistance bands) can be developed. When the material is subjected to tensile or compressive deformation, the lattice spacing of the internal photonic crystal microspheres will physically change. According to Bragg's equation, the reflected wavelength... An offset will occur.

[0054] (2) Anti-counterfeiting packaging and security labels: Utilizing the unreplicable micro-flow field of the twin-screw extrusion process, or introducing specific micro-defect patterns through subsequent hot pressing / imprinting processes, anti-counterfeiting labels can be used for pharmaceuticals, luxury goods, or certificates. The generation of structural colors depends on the precise arrangement of nanoscale microspheres, making it difficult for counterfeiters to imitate using simple printing techniques.

[0055] (3) Structural color 3D printing consumables: During the FDM printing process, the shear force of the molten filament passing through the nozzle will induce the microspheres to orient along the printing path again, thereby preparing a standard diameter (1.75 mm) 3D printing filament, which can be used for printing personalized products. During the fused deposition modeling (FDM) process, it can maintain the ordered structure of the microspheres and give the printed parts an anisotropic gloss. Preferably, the 3D printing filament is composed of 40 wt% core-shell structured photonic crystal microspheres and 60 wt% polypropylene (PP) matrix.

[0056] (4) Building energy-saving and light management film (infrared reflective film): By adjusting the microsphere particle size, its photonic bandgap is made to specifically reflect infrared light (thermal radiation) while allowing visible light to pass through. Without affecting the light transmission (transparency), it blocks heat from entering the room and reduces air conditioning energy consumption. It can be used as building window film or agricultural greenhouse film, etc.

[0057] In the above applications, specific examples will be used to further illustrate the application scenarios of the present invention.

[0058] (1) When applying, the appropriate resin (such as PET or PVC for agricultural greenhouses to improve heat resistance), microspheres (to meet specific reflection wavelengths) and substrate should be selected according to the requirements of the target product.

[0059] (2) In the field of additive manufacturing, the masterbatch of the present invention can be directly extruded into FDM 3D printing filament, giving the printed product a structural color that never fades and anisotropic gloss.

[0060] The detailed descriptions of the specific embodiments and application scenarios above fully demonstrate the operability, excellent performance, and broad market application prospects of the process of the present invention.

[0061] The following are specific examples.

[0062] Example 1: Preparation method of structural color polymer composite material (1) Raw material preparation and pretreatment: The thermoplastic resin used is spinning grade polyethylene terephthalate (PET) homopolymer granules, with a mass ratio of PET:PS = 1:0.6. The average particle size of the polystyrene microspheres is 180 nm (target structural color is blue).

[0063] The PET granules were dried in an 80°C forced-air drying oven for 8 hours to remove moisture. Premixing: The dried PET granules and polystyrene microspheres were stirred for 10 minutes to mix them evenly and form a premix.

[0064] (2) Twin-screw blending extrusion: This invention uses a co-rotating twin-screw extruder with a screw configuration designed for high-shear mixing (comprising multiple kneading blocks). Temperature settings: Feeding zone 220°C, Melting zone 2 240°C, Melting zone 3 250°C, Mixing zone 4 260°C, Mixing zone 5 270°C, Mixing zone 6 260°C, Melt pump zone 250°C, Die head zone 250°C. Screw speed adjusted to 40 rpm.

[0065] The premixed material is added through the feed port, and under the conveying, melting, shearing, and mixing action of the screw, the photonic crystals are highly dispersed in the PET melt. After the molten blend is pressurized by the melt pump, it is extruded through a circular single-hole die. The extruded polymer filaments have a smooth surface, uniform color, and no visible color spots.

[0066] Figure 2 This is a 500x magnified SEM image of the structural color polymer composite material of this invention.

[0067] Example 2: Hot pressing preparation of blue structural fabric based on PET The structural color polymer composite material prepared in Example 1 was subjected to hot-press printing: A pre-cut polyester fabric sample was laid flat in the center of the lower heating plate. The prepared blue PET colored filaments were cut into granules (this step is omitted if the granulation process has been completed), and evenly spread on the fabric surface. A layer of high-temperature resistant polyimide (PI) release film was then placed on the spread masterbatch to prevent molten PET from adhering to the pressure plate. A flat stainless steel template was placed above the release film to ensure uniform pressure transmission.

[0068] Set the hot-pressing parameters: temperature 250°C, pressure 10 MPa. Holding time 10 minutes. After the entire process is complete, carefully remove the release film and stainless steel template. At this point, a thin, continuous blue PET film is evenly covered on the cotton fabric surface, firmly bonded to the fabric. Under 250°C and high pressure, the PET matrix completely melts and undergoes lateral flow. This restricted shear flow forces the rigid PS microspheres to self-assemble in the flowing PET medium, forming a layered lattice structure parallel to the fabric surface. After cooling and demolding, a continuous, flexible film with a bright metallic blue luster is formed on the fabric surface.

[0069] Figure 3 This is a photograph of the present invention after hot pressing and dyeing.

[0070] Example 3: 3D Printing of a Structural Color Model Based on Photonic Crystals (PP) In this embodiment, the first two steps are the same as those in embodiments (1) and (2), only the processing parameters during extrusion need to be modified. The extrusion temperature is set as follows: feeding zone 160°C, melting zone 2 170°C, melting zone 3 180°C, mixing zone 4 180°C, mixing zone 5 190°C, mixing zone 6 190°C, melt pump zone 185°C, and die head zone 185°C.

[0071] The composite filament was pretreated (dried at 80℃ for 3 hours to remove adsorbed moisture); the target device model was designed using CAD software, and the printing parameters were set using slicing software: nozzle temperature 200℃, heated bed temperature 60℃, layer thickness 0.3 mm, fill rate 75%, and printing speed 40 mm / s.

[0072] The composite filament is then fed into the FDM 3D printer's feed inlet, and the program is run using the .gcode format slice file. The printing process is then complete. After printing, the heated bed temperature is maintained for 5 minutes, and then allowed to cool naturally to room temperature to avoid interlayer cracking and residual internal stress caused by rapid cooling.

[0073] Figure 4 These are photographs of the 3D-printed model of this invention.

[0074] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a structural color polymer composite material based on photonic crystals, characterized in that, Includes the following steps: S1: Mix monodisperse photonic crystal microspheres and thermoplastic polymer resin to obtain a premix; S2: The premix obtained in step S1 is fed into a twin-screw extruder for melt blending and extrusion to obtain a photonic crystal polymer composite precursor. S3: An external rheological field is applied to the composite precursor obtained in step S2. Under the synergistic effect of the relaxation of thermoplastic polymer resin chain segments and the Brownian motion of monodisperse photonic crystal microspheres, the monodisperse photonic crystal microspheres self-assemble in the thermoplastic polymer resin to form a short-range ordered glassy structure, thereby obtaining a polymer composite material with a stable structural color.

2. The method for preparing structural color polymer composite materials based on photonic crystals as described in claim 1, characterized in that, In step S3, the external rheological field is a self-confining pressure field, an oscillating shear field, or a uniaxial tensile field; the confining pressure field is achieved by hot pressing of a flat plate; the oscillating shear field is achieved by bending-induced oscillating shearing through a multi-roll calendering system.

3. The method for preparing structural color polymer composite materials based on photonic crystals as described in claim 1 or 2, characterized in that, The monodisperse photonic crystal microspheres are at least one of the following: copolymer microspheres formed by copolymerization of ethyl acrylate and styrene, polystyrene microspheres, and polymethyl methacrylate microspheres.

4. The method for preparing a structural color polymer composite material based on a photonic crystal as described in claim 1 or 2, characterized in that, The thermoplastic polymer resin is at least one of polypropylene, polyethylene terephthalate, polylactic acid, polyethylene, nylon, and thermoplastic polyurethane.

5. The method for preparing structural color polymer composite materials based on photonic crystals as described in claim 1, characterized in that, In the premix, the mass of the monodisperse photonic crystal microspheres is 40%-60% of the mass of the thermoplastic polymer resin.

6. The method for preparing the structured color polymer composite material based on photonic crystals as described in claim 1, characterized in that, The extrusion temperature of the twin-screw extruder is 10°C-50°C higher than the melting point of the thermoplastic polymer resin, and the screw speed of the twin-screw extruder is 30 rpm-60 rpm.

7. The structural color polymer composite material based on photonic crystals prepared by the method according to any one of claims 1-6.

8. A structural color fabric based on structural color polymers, characterized in that, The surface of the structural color fabric is covered with a structural color film made of the structural color polymer composite material based on photonic crystals as described in claim 7 by a hot pressing process.

9. The application of the structural color polymer composite material based on photonic crystal as described in claim 7 as a consumable for structural color 3D printing.

10. The application of the structured color polymer composite material based on photonic crystal as described in claim 7 in mechanochromic motion monitoring wearable devices, anti-counterfeiting packaging, security tags, or infrared reflective films.

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