A photochromic film and a method for preparing the same

Abstract

The present application relates to the technical field of advanced optical functional materials, and in particular to a photochromic film and a preparation method thereof. The components include: ceramic powder and a flexible matrix, and the chemical formula of the ceramic powder is BaMgSiO4Eu x Fe y , wherein 0

Description

Technical Field

[0001] The present invention relates to the technical field of advanced optical functional materials. Specifically, it relates to a photochromic film and a preparation method thereof. Background Art

[0002] As a key member in the field of intelligent materials, photochromic materials can undergo reversible color changes when irradiated with light of a specific wavelength. This property enables them to exhibit great application potential in fields such as intelligent windows, optical anti-counterfeiting, and optical information storage. Among numerous photochromic material systems, rare-earth-doped silicate-based materials have become a research and development hotspot due to their good chemical stability, unique luminescence properties, and relatively excellent photochromic performance. However, traditional preparation methods such as the sol-gel method can achieve uniform mixing of components, but they are prone to introducing impurities, and high-temperature heat treatment may cause film cracking, affecting performance and applications. In addition, the hydrothermal method requires a high-temperature and high-pressure environment, with high equipment requirements, complex operations, and difficult control. The solid-phase reaction method results in affected product purity and performance due to uneven mixing and incomplete reactions. These methods have many deficiencies in preparing film morphology. In contrast, electrospinning technology has successfully prepared a rich variety of nanofibers, including organic, organic / inorganic composite, and inorganic electrospun fibers, due to its advantages such as simple manufacturing equipment, low spinning cost, a wide variety of spinable substances, and controllable processes.

[0003] Chinese invention patent CN118906598B discloses a multi-layer composite anti-counterfeiting film and a preparation method thereof. Using styrene, n-butyl acrylate, methacrylic acid, and allyl methacrylate as raw materials, based on colloidal microspheres prepared by semi-batch emulsion polymerization, perovskite quantum dots are embedded to form a photonic crystal film, and then a photochromic film layer containing a polypyrrole-phosphomolybdic acid composite component is formed on its surface by electrospinning. The core is to combine the color display of the photonic crystal structure with quantum dot fluorescence and photochromism to achieve anti-counterfeiting functions. It does not involve the exploration of flexibility and color change sensitivity. Summary of the Invention

[0004] In the first aspect of the present invention, a photochromic film is provided, and its components include: ceramic powder and a flexible matrix. The chemical formula of the ceramic powder is: BaMgSiO4Eu x Fe y , where 0 < x ≤ 0.01 and 0 < y ≤ 0.01; the preparation raw materials of the flexible matrix include a solvent and a polymer; the weight ratio of the ceramic powder to the flexible matrix is 1:(3 - 10).

[0005] Optionally, the weight ratio of the ceramic powder to the flexible matrix is 1:(3 - 8).

[0006] Optionally, x and y satisfy the following requirement: 0.002 <x≤0.008,0.002<y≤0.008。

[0007] The raw materials for preparing the ceramic powder include powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator.

[0008] The powder raw materials include BaCO3, SiO2, MgO, Eu2O3, and Fe2O3.

[0009] The flux includes Li2CO3 or H3BO3; the structure stabilizer includes ZrO2 or Al2O3; the sensitizer includes Dy2O3 or Tb4O7; and the charge compensator includes at least one of Na2CO3, K2CO3, and Li2CO3.

[0010] The molar ratio of the flux, structure stabilizer, sensitizer, and charge compensator is (0.5-2):(0.01-1):(0.01-0.1):(0.1-0.5).

[0011] Optionally, the molar ratio of the flux, structure stabilizer, sensitizer, and charge compensator is (0.8-1.5):(0.03-0.8):(0.05-0.08):(0.1-0.3).

[0012] The molar ratio of the powder raw material to the flux is 100:(0.5-2).

[0013] Optionally, by weight, the raw materials for preparing the flexible matrix include: 40-70 parts solvent, 10-20 parts polymer, 8-15 parts dispersant, and 1-10 parts additives.

[0014] The additives include antioxidants and light stabilizers.

[0015] Optionally, the solvent includes at least one of acetone, DMF (N,N-dimethylformamide), and NMP (N-methylpyrrolidone).

[0016] Optionally, the solvent includes acetone, N,N-dimethylformamide, and N-methylpyrrolidone.

[0017] Optionally, the polymer includes at least one of TPU (thermoplastic polyurethane), PVDF (polyvinylidene fluoride), and PVP (polyvinylpyrrolidone).

[0018] Optionally, the mass ratio of the thermoplastic polyurethane, polyvinylidene fluoride, and polyvinylpyrrolidone is (3-5):(3-4):(2-3).

[0019] Optionally, the mass ratio of the thermoplastic polyurethane, polyvinylidene fluoride, and polyvinylpyrrolidone is (3-5):(2.5-4):2.

[0020] Optionally, the dispersant includes at least one of polyoxypropylene ether, polyethylene glycol monobutyl ether, and polybutyl acrylate.

[0021] Optionally, the antioxidant includes at least one of butylated hydroxyanisole, tert-butylhydroquinone, and butylated hydroxytoluene.

[0022] Optionally, the light stabilizer includes at least one of Tinuvin 622 and Tinuvin 111.

[0023] A second aspect of the present invention provides a method for preparing a photochromic thin film, comprising the following steps:

[0024] S1: Mix the powder raw materials, add flux, structural stabilizer, sensitizer and charge compensator, and ball mill once. After drying and grinding, pre-fire in sections, ball mill a second time, and then reduce sinter and anneal to obtain ceramic powder.

[0025] S2: Add the polymer to the solvent, then add the dispersant and additives to obtain a flexible matrix;

[0026] S3: Mix the ceramic powder and flexible matrix evenly, and perform electrospinning to obtain a photochromic film.

[0027] By limiting the molar ratio of powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator to 1:(0.5-2):(0.01-1):(0.01-0.1):(0.1-0.5), and combining it with solid-state synthesis, magnesium barium silicate powder with specific crystal form and doping concentration is synthesized, thereby improving the purity and crystallinity of the powder and optimizing the crystal quality and luminescence uniformity.

[0028] The solvents, including acetone, N,N-dimethylformamide, and N-methylpyrrolidone, effectively improve the mechanical strength and flexibility of the film material. The rapid volatility of acetone and the strong solubility of N-dimethylformamide and N-methylpyrrolidone regulate the solution viscosity, creating a suitable solvent environment for spinning. Combined with specific polymers, they effectively improve the stability of the spinning jet. Further research revealed that using a composite dispersant system, combining steric hindrance and interfacial wetting, can achieve uniform dispersion of powder in the organic phase. Simultaneously, during the spinning process, uniaxial needle technology is used to prepare core-shell structured fibers, with ceramic powder as the core and PVP as the shell, further optimizing luminescence efficiency. Specific spinning parameter settings ensure fiber morphology uniformity and structural stability.

[0029] The segmented preheating includes: first holding at 600-700℃ for 2 hours, then raising the temperature at 2-5℃ / min to 950-1050℃ and holding for 2-4 hours, followed by cooling at 5-10℃ / min.

[0030] The reduction sintering includes: introducing a mixed gas at 1250℃-1350℃.

[0031] The mixed gas includes hydrogen and nitrogen, with hydrogen accounting for 2-10% of the volume.

[0032] The parameters for electrospinning include: inert gas atmosphere, collection distance 12-18cm, positive voltage 10-17kV, negative voltage 2-2.5kV, feed rate 0.1-0.2mm / min, temperature 20-30℃, and humidity 30-40%.

[0033] Optionally, the parameters of the electrospinning include: inert gas atmosphere, collection distance 14-16cm, positive voltage 12-15kV, negative voltage 2-2.5kV, feed rate 0.12-0.2mm / min, temperature 23-27℃, and humidity 30-40%.

[0034] Beneficial effects

[0035] 1. This invention utilizes electrospinning technology to prepare Fe / Eu-doped BaMgSiO4 photochromic films. By precisely controlling the doping concentration and spinning parameters, uniform, continuous films with specific microstructures can be prepared, overcoming the shortcomings of traditional methods.

[0036] 2. The thin film of the present invention has a large specific surface area and abundant pore structure, which is conducive to the rapid occurrence of photochromic reaction, thereby improving the color change speed and sensitivity.

[0037] 3. The synergistic doping of Fe and Eu in this invention can effectively control the photochromic properties of the thin film, enabling the thin film to exhibit multi-stage dynamic color-changing effects under a single light source excitation.

[0038] 4. This invention utilizes electrospinning technology to composite powder with a polymer matrix to form a film, overcoming the difficulty of uniformly dispersing high-performance inorganic powder in a flexible matrix using traditional methods, and achieving uniform distribution and good bonding of powder in the polymer matrix.

[0039] 5. By precisely controlling parameters such as the formulation of the spinning solution, spinning voltage, injection pump speed, ambient humidity, and temperature, uniform regulation of nanofiber morphology and size was achieved, significantly improving the color change speed and sensitivity. Attached Figure Description

[0040] Figure 1 The XRD patterns of the thin films prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown.

[0041] Figure 2 The image shows the SEM pattern of the thin film prepared in Example 2.

[0042] Figure 3 The SEM energy dispersive spectroscopy (EDS) analysis of the thin film prepared in Example 2 shows that the elements in the top row from left to right are: O, Si, Mg, and the elements in the bottom row from left to right are: Ba, Eu, Fe.

[0043] Figure 4 The SEM image of the thin film prepared in Comparative Example 1;

[0044] Figure 5 For the SEM energy dispersive spectroscopy (EDS) analysis of the thin film prepared in Comparative Example 1, the elements in the top row from left to right are: Si, Mg, Ba, and the elements in the bottom row from left to right are: O, C, Eu.

[0045] Figure 6 The SEM images of the thin films prepared in Comparative Example 2 are shown.

[0046] Figure 7 The image shows the reflectance spectra of the thin film prepared in Example 1 before and after solar irradiation. The blue curve corresponds to before irradiation, and the brown curve corresponds to after irradiation.

[0047] Figure 8 The image shows the reflectance spectra of the thin film prepared in Example 1 before and after irradiation at 365 nm. The blue curve corresponds to before irradiation, and the brown curve corresponds to after irradiation.

[0048] Figure 9 The reflection spectra of the thin film prepared in Comparative Example 1 before and after solar irradiation are shown. The blue curve corresponds to before irradiation, and the brown curve corresponds to after irradiation.

[0049] Figure 10 Example 1 shows the changes in the thin film before and after solar irradiation, with the left image showing before irradiation and the right image showing after irradiation.

[0050] Figure 11 The images show the changes in the thin film prepared in Example 1 before and after irradiation with a 365nm light source. The left image shows the film before irradiation, and the right image shows the film after irradiation.

[0051] Figure 12 Tensile properties of the thin film prepared in Example 1 were tested. Detailed Implementation

[0052] Example 1

[0053] A photochromic thin film is composed of ceramic powder and a flexible matrix, wherein the chemical formula of the ceramic powder is BaMgSiO4Eu. 0.005 Fe 0.005 The weight ratio of the ceramic powder to the flexible matrix is ​​1:5.

[0054] The raw materials for preparing the ceramic powder are powder raw materials (BaCO3, SiO2, MgO, Eu2O3, Fe2O3), flux (Li2CO3), structural stabilizer (ZrO2), sensitizer (Dy2O3), and charge compensator (Na2CO3); the molar ratio of the powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator is 254:1:0.5:0.05:0.2.

[0055] The raw materials for preparing the flexible matrix, by weight, include: 35 parts solvent (acetone, N,N-dimethylformamide and N-methylpyrrolidone compounded in a ceramic powder mass ratio of 4:2:1), 10 parts polymer (TPU, PVDF and PVP compounded in a mass ratio of 5:3:2) (TPU Bayer, Germany; PVDF Arkema, France; PVP BASF, Germany), 1 part dispersant (polyoxypropylene ether, polyethylene glycol monobutyl ether and polybutyl acrylate compounded in a mass ratio of 1:1:1), 0.05 parts antioxidant (BHT) and 0.03 parts light stabilizer (Tinuvin 770).

[0056] A method for preparing a photochromic thin film includes the following steps:

[0057] S1: Mix the powder raw materials according to the chemical formula of ceramic powder, add flux, structure stabilizer, sensitizer and charge compensator, and ball mill once. After drying and grinding, perform segmented pre-firing, ball mill a second time, and then reduce sintering and annealing to obtain ceramic powder.

[0058] S2: Add the polymer to the solvent, then add the dispersant and additives to obtain a flexible matrix;

[0059] S3: Mix the ceramic powder and flexible matrix evenly, and perform electrospinning to obtain a photochromic film.

[0060] The ball milling parameters are: powder raw material: zirconium balls: ethanol = 1:1:2, high-energy ball milling speed 450 rpm, 15 h; the segmented pre-calcination includes: first holding at 650℃ for 2 h, then increasing the temperature to 1000℃ at a rate of 3℃ / min, holding for 3 h, and then cooling to ambient temperature at a rate of 5-10℃ / min; the reduction sintering includes: introducing a mixed gas (hydrogen and nitrogen, with hydrogen accounting for 5% by volume) at 1300℃; the annealing parameters are: air annealing at 550℃ for 2 h.

[0061] The parameters for electrospinning include: nitrogen atmosphere, collection distance 15cm, positive voltage 13.5kV, negative voltage 2.2kV, feed rate 0.18mm / min, temperature 25℃, and humidity 35%.

[0062] Example 2

[0063] A photochromic thin film is composed of ceramic powder and a flexible matrix, wherein the chemical formula of the ceramic powder is BaMgSiO4Eu. 0.005 Fe 0.005 The weight ratio of the ceramic powder to the flexible matrix is ​​1:5.

[0064] The raw materials for preparing the ceramic powder are powder raw materials (BaCO3, SiO2, MgO, Eu2O3, Fe2O3), flux (Li2CO3), structural stabilizer (ZrO2), sensitizer (Dy2O3), and charge compensator (Na2CO3); the molar ratio of the powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator is 254:1.5:0.8:0.08:0.2.

[0065] The raw materials for preparing the flexible matrix, by weight, include: 35 parts solvent (acetone, N,N-dimethylformamide and N-methylpyrrolidone in a mass ratio of 4:2:1), 8 parts polymer (TPU, PVDF and PVP in a mass ratio of 3:3:2), dispersant (polyoxypropylene ether, polyethylene glycol monobutyl ether and polybutyl acrylate in a mass ratio of 1:1:1), 0.05 parts antioxidant (BHT) and 0.03 parts light stabilizer (Tinuvin 770).

[0066] A method for preparing a photochromic thin film includes the following steps:

[0067] S1: Mix the powder raw materials according to the chemical formula of ceramic powder, add flux, structure stabilizer, sensitizer and charge compensator, and ball mill once. After drying and grinding, perform segmented pre-firing, ball mill a second time, and then reduce sintering and annealing to obtain ceramic powder.

[0068] S2: Add the polymer to the solvent, then add the dispersant and additives to obtain a flexible matrix;

[0069] S3: Mix the ceramic powder and flexible matrix evenly, and perform electrospinning to obtain a photochromic film.

[0070] The ball milling parameters are: powder raw material: zirconium balls: ethanol = 1:1:2, high-energy ball milling speed 450 rpm, 15 h; the segmented pre-calcination includes: first holding at 700℃ for 2 h, then increasing the temperature to 1020℃ at a rate of 4℃ / min, holding at that temperature for 3 h, and then cooling down to ambient temperature at a rate of 6℃ / min; the reduction sintering includes: introducing a mixed gas (hydrogen and nitrogen, with hydrogen accounting for 5% by volume) at 1320℃; the annealing parameters are: air annealing at 600℃ for 1.5 h.

[0071] The parameters for electrospinning include: nitrogen atmosphere, collection distance 15cm, positive voltage 14kV, negative voltage 2.3kV, feed rate 0.16mm / min, temperature 26℃, and humidity 40%.

[0072] Example 3

[0073] A photochromic thin film is composed of ceramic powder and a flexible matrix, wherein the chemical formula of the ceramic powder is BaMgSiO4Eu. 0.005 Fe 0.005 The weight ratio of the ceramic powder to the flexible matrix is ​​1:5.

[0074] The raw materials for preparing the ceramic powder are powder raw materials (BaCO3, SiO2, MgO, Eu2O3, Fe2O3), flux (Li2CO3), structural stabilizer (ZrO2), sensitizer (Dy2O3), and charge compensator (Na2CO3); the molar ratio of the powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator is 254:0.8:0.03:0.08:0.2.

[0075] The raw materials for preparing the flexible matrix, by weight, include: 33 parts solvent (acetone, N,N-dimethylformamide and N-methylpyrrolidone in a mass ratio of 18:10:5), 12 parts polymer (TPU, PVDF and PVP in a mass ratio of 5:4:3), dispersant (polyoxypropylene ether, polyethylene glycol monobutyl ether and polybutyl acrylate in a mass ratio of 1:1:1), 0.05 parts antioxidant (BHT) and 0.03 parts light stabilizer (Tinuvin 770).

[0076] A method for preparing a photochromic thin film includes the following steps:

[0077] S1: Mix the powder raw materials according to the chemical formula of ceramic powder, add flux, structure stabilizer, sensitizer and charge compensator, and ball mill once. After drying and grinding, perform segmented pre-firing, ball mill a second time, and then reduce sintering and annealing to obtain ceramic powder.

[0078] S2: Add the polymer to the solvent, then add the dispersant and additives to obtain a flexible matrix;

[0079] S3: Mix the ceramic powder and flexible matrix evenly, and perform electrospinning to obtain a photochromic film.

[0080] The ball milling parameters are: powder raw material: zirconium balls: ethanol = 1:1:2, high-energy ball milling speed 450 rpm, 15 h; the segmented pre-calcination includes: first holding at 700℃ for 2 h, then increasing the temperature to 1020℃ at a rate of 4℃ / min, holding at that temperature for 3 h, and then cooling down to ambient temperature at a rate of 6℃ / min; the reduction sintering includes: introducing a mixed gas (hydrogen and nitrogen, with hydrogen accounting for 5% by volume) at 1280℃; the annealing parameters are: air annealing at 500℃ for 2.5 h.

[0081] The parameters for electrospinning include: nitrogen atmosphere, collection distance 15cm, positive voltage 12.5kV, negative voltage 2.1kV, feed rate 0.19mm / min, temperature 24℃, and humidity 30%.

[0082] Comparative Example 1

[0083] A photochromic thin film is composed of ceramic powder and a flexible matrix, wherein the chemical formula of the ceramic powder is BaMgSiO4Eu. 0.005 Fe 0.005 The weight ratio of the ceramic powder to the flexible matrix is ​​1:5.

[0084] The raw materials for preparing the ceramic powder are powder raw materials (BaCO3, SiO2, MgO, Eu2O3, Fe2O3), flux (Li2CO3), structural stabilizer (ZrO2), sensitizer (Dy2O3), and charge compensator (Na2CO3); the molar ratio of the powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator is 100:1:0.5:0.05:0.2.

[0085] The raw materials for preparing the flexible matrix, by weight, include: 35 parts solvent (acetone, N,N-dimethylformamide and N-methylpyrrolidone in a mass ratio of 4:2:1), 10 parts polymer (PVA) (Kuraray Corporation, Japan), dispersant (polyoxypropylene ether, polyethylene glycol monobutyl ether and polybutyl acrylate in a mass ratio of 1:1:1), 0.05 parts antioxidant (BHT) and 0.03 parts light stabilizer (Tinuvin 770).

[0086] A method for preparing a photochromic thin film includes the following steps:

[0087] S1: Mix the powder raw materials according to the chemical formula of ceramic powder, add flux, structure stabilizer, sensitizer and charge compensator, and ball mill once. After drying and grinding, perform segmented pre-firing, ball mill a second time, and then reduce sintering and annealing to obtain ceramic powder.

[0088] S2: Add the polymer to the solvent, then add the dispersant and additives to obtain a flexible matrix;

[0089] S3: Mix the ceramic powder and flexible matrix evenly, and perform electrospinning to obtain a photochromic film.

[0090] The ball milling parameters are: powder raw material: zirconium balls: ethanol = 1:1:2, high-energy ball milling speed 450 rpm, 15 h; the segmented pre-calcination includes: first holding at 650℃ for 2 h, then increasing the temperature to 1000℃ at a rate of 3℃ / min, holding for 3 h, and then cooling to ambient temperature at a rate of 5-10℃ / min; the reduction sintering includes: introducing a mixed gas (hydrogen and nitrogen, with hydrogen accounting for 5% by volume) at 1300℃; the annealing parameters are: air annealing at 550℃ for 2 h.

[0091] The parameters for electrospinning include: nitrogen atmosphere, collection distance 15cm, positive voltage 13.5kV, negative voltage 2.2kV, feed rate 0.18mm / min, temperature 25℃, and humidity 35%.

[0092] Comparative Example 2

[0093] A photochromic thin film is composed of ceramic powder and a flexible matrix, wherein the chemical formula of the ceramic powder is BaMgSiO4Eu. 0.005 Fe 0.005 The weight ratio of the ceramic powder to the flexible matrix is ​​1:15.

[0094] The raw materials for preparing the ceramic powder are powder raw materials (BaCO3, SiO2, MgO, Eu2O). 3、 The powder raw materials consist of Fe2O3, flux (Li2CO3), structural stabilizer (ZrO2), sensitizer (Dy2O3), and charge compensator (Na2CO3). The molar ratio of the powder raw materials, flux, structural stabilizer, sensitizer, and charge compensator is 100:1:0.5:0.05:0.2.

[0095] The raw materials for preparing the flexible matrix, by weight, include: 35 parts solvent (acetone, N,N-dimethylformamide and N-methylpyrrolidone in a mass ratio of 4:2:1), 10 parts polymer (TPU, PVDF and PVP in a mass ratio of 5:3:2) (TPU Bayer, Germany; PVDF Arkema, France; PVP BASF, Germany), dispersant (polyoxypropylene ether, polyethylene glycol monobutyl ether and polybutyl acrylate in a mass ratio of 1:1:1), 0.05 parts antioxidant (BHT) and 0.03 parts light stabilizer (Tinuvin 770).

[0096] A method for preparing a photochromic thin film includes the following steps:

[0097] S1: Mix the powder raw materials according to the chemical formula of ceramic powder, add flux, structure stabilizer, sensitizer and charge compensator, and ball mill once. After drying and grinding, perform segmented pre-firing, ball mill a second time, and then reduce sintering and annealing to obtain ceramic powder.

[0098] S2: Add the polymer to the solvent, then add the dispersant and additives to obtain a flexible matrix;

[0099] S3: Mix the ceramic powder and flexible matrix evenly, and perform electrospinning to obtain a photochromic film.

[0100] The ball milling parameters are: powder raw material: zirconium balls: ethanol = 1:1:2, high-energy ball milling speed 450 rpm, 15 h; the segmented pre-calcination includes: first holding at 650℃ for 2 h, then increasing the temperature to 1000℃ at a rate of 3℃ / min, holding for 3 h, and then cooling to ambient temperature at a rate of 5-10℃ / min; the reduction sintering includes: introducing a mixed gas (hydrogen and nitrogen, with hydrogen accounting for 5% by volume) at 1300℃; the annealing parameters are: air annealing at 550℃ for 2 h.

[0101] The parameters for electrospinning include: nitrogen atmosphere, collection distance 15cm, positive voltage 13.5kV, negative voltage 2.2kV, feed rate 0.18mm / min, temperature 25℃, and humidity 35%.

[0102] Performance testing methods and data

[0103] 1. X-ray diffraction tests were performed on the thin films prepared in Example 1 and Comparative Examples 1 and 2. The results are as follows: Figure 1 As shown. From Figure 1 The XRD peak positions and peak shapes of the thin film can be clearly observed to be in perfect agreement with the PDF standard card (#81-2317). No impurity phase was detected, confirming that the sample is pure phase barium magnesium silicate.

[0104] 2. The films prepared in Examples 2-3 and the comparative examples were observed using scanning electron microscopy (SEM). Uniform fiber arrangement was observed only in the flexible matrix. However, when doped with Eu / Fe (… Figure 2 When preparing BaMgSiO4 ceramic powder, SEM scanning results showed that, compared with pure fibers, the prepared fibers exhibited a phenomenon where white particles were uniformly encapsulated within the fibers. Furthermore, SEM energy dispersive spectroscopy (EDS) analysis revealed this phenomenon. Figure 3 , Figure 5The distribution of each element in the fiber is clearly shown. This indicates that electrospinning technology has successfully combined the fiber with solid-phase particles to form a composite material, thereby significantly improving the material's fast-response light and photochromic properties. Comparative Example 1, due to incompatible polymers and solvents, failed to form the desired fiber microstructure. Figure 4 Comparative Example 2, due to the significant difference in the ratio of powder to flexible matrix, lacks the morphological and color variations of particles encapsulated by filaments. Figure 6 .

[0105] 3. The reflectance spectrum of the material before and after solar irradiation was measured using an ultraviolet-visible-near-infrared spectrophotometer, such as... Figure 7 As shown, the reflectivity of the thin film in Example 1 decreased significantly after irradiation (37.78%), and the material's appearance changed from white to pink. Figure 10 );like Figure 8 As shown, the reflectivity of the thin film decreased significantly (18.95%) after being irradiated by a 365nm light source, and the material emitted a blue light. Figure 11 ), while the reflectivity of the thin film in Comparative Example 1 was significantly poor after irradiation ( Figure 9 This indicates that the thin film of Embodiment 1 of the present invention not only has flexibility but also outstanding light-emitting performance.

[0106] Images of BaMgSiO4:Eu / Fe electrospun thin films before and after irradiation using a 365nm light source are shown below. Figure 11 This indicates that the sample not only possesses flexibility but also exhibits outstanding luminescent properties.

[0107] 4. The tensile properties of the film from Example 1 were tested using a ZQ-990LA universal tensile testing machine. Figure 12 As shown, its strain capacity reaches 200%, exhibiting excellent tensile properties, making it suitable for applications such as wearable devices.

Claims

1. A photochromic film, characterized by, The composition comprises: ceramic powder and flexible matrix, the chemical formula of the ceramic powder is: BaMgSiO4Eu x Fe y , wherein 0 < x ≤ 0.01, 0 < y ≤ 0.01; the raw material of the flexible matrix comprises solvent and polymer; the weight ratio of the ceramic powder and the flexible matrix is 1: (3-8); The preparation raw materials of the ceramic powder include powder raw materials, fluxing agent, structure stabilizer, sensitizer and charge compensator, and the molar ratio of the fluxing agent, structure stabilizer, sensitizer and charge compensator is (0.5-2):(0.01-1):(0.01-0.1):(0.1-0.5); The preparation raw materials of the flexible matrix include 40-70 parts of solvent, 10-20 parts of polymer, 8-15 parts of dispersant and 1-10 parts of auxiliary agent; The solvent includes acetone, N,N-dimethylformamide and N-methyl pyrrolidone; The polymer includes thermoplastic polyurethane, polyvinylidene fluoride and polyvinylpyrrolidone, and the mass ratio of the thermoplastic polyurethane, polyvinylidene fluoride and polyvinylpyrrolidone is (3-5):(3-4):(2-3); The preparation method of the photochromic film includes the following steps: mixing powder raw materials, adding fluxing agent, structure stabilizer, sensitizer and charge compensator, performing primary ball milling, drying and grinding, performing segmented pre-sintering, performing secondary ball milling, performing reduction sintering and annealing treatment to obtain ceramic powder; adding polymer into solvent, and then adding dispersant and auxiliary agent to obtain flexible matrix; uniformly mixing the ceramic powder and the flexible matrix, and performing electrospinning to obtain photochromic film.

2. The photochromic film of claim 1, wherein The segmented pre-sintering includes: first, keeping at 600-700 DEG C for 2h, then increasing the temperature to 950-1050 DEG C at a rate of 2-5 DEG C / min, keeping for 2-4h, and then decreasing the temperature at a rate of 5-10 DEG C / min.

3. The photochromic film of claim 1, wherein The reduction sintering includes: passing mixed gas at 1250 DEG C-1350 DEG C, the mixed gas including hydrogen and nitrogen, and the volume ratio of hydrogen being 2-10%.

4. The photochromic film of claim 1, wherein The parameters of the electrospinning include: inert gas atmosphere, collection distance of 12-18cm, positive voltage of 10-17kV, negative voltage of 2-2.5kV, advancing speed of 0.1-0.2mm / min, temperature of 20-30 DEG C and humidity of 30-40%.

Images