A H4[SiW 12 O 40 ] / Preparation method of PVP color-changing material and its application in preparing electro-induced / photo-induced dual-response display device

Abstract

The present invention belongs to the technical field of the preparation of color-changing materials, and relates to a preparation method of an H4[SiW 12 O 40 / PVP color-changing material and its application in the preparation of electro-optic dual-responsive display devices. The preparation method includes the following steps: Dissolve the raw material of silicotungstic acid H4[SiW 12 O 40 in deionized water, and add lithium hydroxide powder in portions under continuous stirring to adjust the pH of the solution, and then stir for 10 min; Dissolve polyvinylpyrrolidone PVP in the obtained solution and stir for 3 h to obtain a colorless transparent solution; Freeze-dry the solution for 48 h to obtain an H4[SiW 12 O 40 / PVP electro-optic dual-responsive color-changing material. The H4[SiW 12 O 40 / PVP electro-optic dual-responsive color-changing material should be stored by low-temperature drying. The electro-optic dual-responsive color-changing material can be applied in the field of display devices.

Description

Technical Field

[0001] The present invention relates to a H4[SiW 12 O 40 ] / The invention discloses a method for preparing a PVP color-changing material and its application in preparing an electro-induced / photo-induced dual-response display device, belonging to the technical field of color-changing material preparation. Background Art

[0002] At present, the research on color-changing devices is mostly focused on single stimulus response (such as electrochromic, photochromic, and thermochromic smart windows, etc.), while the research on dual- or multi-responsive color-changing devices is still in its early stages. Dual- and multi-responsive color-changing devices refer to the ability to respond to a variety of different stimuli (such as electricity, light, heat, etc.) and change color in the same material or system. To achieve this function, the design of the material needs to be adjusted and optimized according to different color-changing mechanisms. However, the multi-stimulus responsive color-changing materials synthesized in the laboratory often face problems such as complex synthesis routes and harsh conditions, which makes these materials difficult to mass-produce and put into use.

[0003] As a new type of transition metal oxide nanocluster compound, polyoxometalates (abbreviated as polyoxometalates) have become a research hotspot due to their unique electrochemical and electronic properties. These polyoxometalates are generally 1 to 5 nanometers in size and have rich topological structures. They can exhibit different color-changing behaviors through reversible multi-electron transfer reactions without changing their basic framework. Compared with traditional transition metal oxides, polyoxometalates have excellent performance in many aspects: first, polyoxometalates clusters have good reversibility and can gradually undergo multi-electron transfer reactions; second, most polyoxometalates have high solubility in water, which is conducive to preparation and application; in addition, polyoxometalates can display a variety of colors during the electron reduction process, and can return to their original colors after undergoing redox reactions. Therefore, polyoxometalates have great potential in the fields of electrochromism and photochromism.

[0004] However, despite the good electrochemical properties of polyacids, their application in electro / photochromic devices still faces many challenges. The main problem is that polyacids usually exist in the form of crystalline solids, which makes it difficult to process them into thin films or other desired forms, limiting their practical application in color-changing devices. Therefore, how to break through this limitation and develop cost-effective dual-responsive color-changing materials suitable for large-scale production has become an important issue in promoting the practical application of color-changing devices.

[0005] In response to the above problems, exploring a new method for preparing color-changing materials can not only effectively overcome the processing difficulties of polyacids, but also achieve dual-response or even multi-response color-changing effects, which is of great significance for the widespread application of color-changing devices in the future. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a H4[SiW 12 O 40 ] / PVP color-changing material preparation method and its application in preparing electro-induced / photo-induced dual-response display device. The method is simple and easy to implement, using silicotungstic acid as a color-changing raw material, making it react with polyvinyl pyrrolidone in a solution to obtain a composite color-changing material with electro-induced / photo-induced dual-response.

[0007] The first object of the present invention is to provide a H4[SiW 12 O 40 ] / The preparation method of PVP color-changing material comprises the following steps:

[0008] S1, silicotungstic acid H4[SiW 12 O 40 ]The raw materials are dissolved in deionized water to obtain an initial solution;

[0009] S2. When the solution obtained in step S1 is fully dissolved, lithium hydroxide powder is added in portions under constant stirring, the pH of the solution is adjusted, and then stirred for 10 minutes;

[0010] S3, under constant stirring, dissolving polyvinyl pyrrolidone PVP in the solution obtained in step S2, stirring for 3 hours to obtain a colorless transparent solution;

[0011] S4, the solution of step S3 was directly freeze-dried for 48h to obtain H4[SiW 12 O 40 ] / PVP electro-induced / photo-induced dual-response color-changing material, the H4[SiW 12 O 40 ] / PVP electro- / photo-induced dual-response color-changing materials should be stored in a dry place at low temperature.

[0012] Further, in step S2, the pH of the solution is adjusted to 4-6.5. When the pH is lower than 4, silicotungstic acid exhibits strong acidity, which promotes its dissociation to form a relatively high ion concentration, and excessive dissociation of silicotungstic acid occurs, resulting in aggregation or precipitation to form insoluble substances, affecting the efficiency of its subsequent reaction with lithium hydroxide. If the pH value is higher than 6.5, lithium hydroxide may cause excessive alkaline conditions, resulting in excessive dissociation of silicotungstic acid or side reactions, affecting the stability of the synthesis process and the smooth progress of subsequent operations. When the pH is 4-6.5, PVP can be well dissolved and interact with other components (such as silicotungstic acid and lithium ions), and finally form a uniform solution, which is conducive to the subsequent freeze-drying process.

[0013] The influence of pH not only determines the smooth progress of the reaction, but also directly affects the structure and performance of the final material. When the pH value is between 4 and 6.5, the silicotungstic acid and PVP can maintain good stability and suitable dispersibility in the electro- / photo-induced dual-response color-changing material, and the material is transparent. Too high or too low pH values ​​will cause the material to become less transparent, have low viscosity and turn yellow.

[0014] Furthermore, the mass of the PVP is silicotungstic acid H4[SiW 12 O 40 ] (5-15)% by mass One of the functions of PVP is to stabilize the dispersion of each component in the solution. PVP provides the necessary support for the composite material by forming a thin film or matrix in it. If the amount of PVP is insufficient, it cannot effectively coat and disperse silicotungstic acid, resulting in poor dispersion of the material and the formation of an uneven structure, which affects the electrochromic / photoresponsive performance of the material. If the amount of PVP is insufficient, the photochromic response speed of the material may slow down, the response amplitude may decrease, or even the responsiveness may be lost. Excessive PVP may result in thicker films or larger polymer chain structures. Although this helps to increase the mechanical strength and stability of the material, if it is excessive, it may make the material too strong and affect its response behavior, for example, the electrochromic or photoresponsive time becomes longer and the color change amplitude decreases. When the mass of the PVP is silicotungstic acid H4[SiW 12 O 40 ] is (5-15)% by mass, a uniform, transparent and moderate composite material can be obtained.

[0015] Furthermore, the reaction in step S3 should be carried out in the dark. The light-shielding method is to use tin foil, aluminum foil or opaque black cloth to block the reaction. The reaction must be carried out in the dark because some monomers or intermediates in PVP are sensitive to light and may cause side reactions or degradation.

[0016] In step S1, silicotungstic acid is a typical polyoxometalate. When it is dissolved in deionized water, water molecules will help the ionization of silicotungstic acid, so that it exists in the solution in the form of a negatively charged structure. In water, tungsten atoms and oxygen atoms interact through hydrogen bonds or coordination bonds to form a stable solution.

[0017] In step S2, lithium hydroxide (LiOH) powder is dissolved in water to provide hydroxide ions (OH - ), through the H4[SiW 12 O 40 ] / Hydrogen ions in PVP (H + ) reaction, adjusting the pH value of the solution. When the pH is adjusted to 4-5, some hydrogen ions in the tungstic acid clusters are neutralized by hydroxide ions, which promotes the deprotonation of the structure of silicotungstic acid, helps to promote the interaction between PVP and silicotungstic acid, and enables PVP to effectively coat or combine with polyoxometallic acid clusters.

[0018] In step S3, polyvinyl pyrrolidone (PVP) is a hydrophilic polymer with good solubility and dispersibility. PVP molecules interact with the metal oxoacid clusters in silicotungstic acid through their polar groups (such as amino groups, hydroxyl groups, etc.). PVP molecules bind to tungsten atoms or silicon atoms in silicotungstic acid clusters through hydrogen bonds, electrostatic interactions or coordination effects. This process helps to form a uniformly dispersed H4[SiW 12 O 40 ] / PVP complex.

[0019] In step S4, the purpose of freeze drying is to remove the water in the obtained solution and maintain the structural stability of the composite material. The freeze drying process helps to prevent the aggregation of PVP and silicotungstic acid clusters or change their structure. During the freeze drying process, the water in the solution is first frozen, and then the water is removed by low-temperature vacuum sublimation to form H4[SiW 12 O 40 ] / PVP composite material.

[0020] The present invention also provides the H4[SiW 12 O 40 ] / Application of PVP color-changing materials in the preparation of electro- / photo-induced dual-response display devices.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention combines silicotungstic acid and polyvinyl pyrrolidone to improve the stability, dispersibility and processability of silicotungstic acid, and at the same time give the composite material electro- and photo-induced dual-response color-changing properties. The specific reasons are as follows:

[0023] ① Improve dispersibility and stability

[0024] Water solubility of silicotungstic acid: Silicotungstic acid is a polyoxometalate, which usually has good solubility in water, but its solution may easily aggregate to form large particles or precipitation. PVP, as a polymer compound, can effectively interact with the metal oxometalate clusters in silicotungstic acid to improve its dispersibility in solution.

[0025] Improve stability: PVP is a hydrophilic polymer that can stabilize polyoxometalate clusters at the molecular level by forming hydrogen bonds and electrostatic interactions with tungsten atoms or silicon atoms in silicotungstic acid to prevent aggregation or degradation, thereby improving the chemical and physical stability of the composite material.

[0026] ② Enhance the processability of the solution

[0027] PVP itself has good solubility and high viscosity, which can form a uniform solution or gel after the silicotungstic acid and PVP are compounded, which is convenient for subsequent preparation processes, such as freeze drying. This makes the processing of the final material more convenient and improves the processability of the material.

[0028] ③Empower electro- / photo-induced dual-response color-changing properties

[0029] Electrochromic / photochromic properties of polyoxometalates: Silicotungstic acid itself has good electrochromic and photochromic response properties, which means that it can change its electronic structure under the action of electric field or light, resulting in a change in color. After PVP is introduced into the composite material, PVP can serve as a supporting material to help maintain the stable structure of silicotungstic acid and ensure that it can still show good color-changing properties under different conditions.

[0030] Synergistic effect: PVP can not only stabilize silicotungstic acid, but also optimize its electrochromic and photochromic response speed and effect through interaction with silicotungstic acid. For example, PVP may further enhance the color change response by changing the surface state of the material or affecting the electron transport properties.

[0031] ④ Enhance the mechanical strength of materials

[0032] PVP is a polymer material that can give composite materials a certain mechanical strength and flexibility, making the final material more durable in practical applications, especially for applications that require a certain shape or flexibility (such as flexible displays, sensors, etc.).

[0033] (2) The present invention provides a method for preparing a dual-response color-changing material. The method mainly adopts a solution method to prepare a silicotungstic acid and PVP composite material. The operation is simple and the required equipment is not complicated. The target material can be easily obtained by conventional steps such as dissolving, stirring and freeze-drying the raw materials, which is suitable for large-scale preparation. The entire preparation process does not require high temperature or complex heat treatment, which reduces energy consumption and operation difficulty. The high temperature induced crystal structure changes or damage that may be caused by the high temperature sintering process is avoided.

[0034] The preparation method combines silicotungstic acid and PVP, and through appropriate dissolution, pH adjustment, PVP addition and freeze-drying steps, a material with electro- / photo-induced dual-response color-changing properties is prepared. This material may have application potential in the fields of sensors, displays or smart dimming materials.

[0035] (3) The present invention uses strongly crystalline Keggin-type silicotungstic acid as the color-changing raw material. It has good redox reversibility. Under the action of external stimulation, electrons jump from a low-energy electronic state to a high-energy electronic state, and the electronic configuration changes. That is, it can accept electrons to become a mixed-valence complex with the structure remaining basically unchanged, which provides the possibility for the electrochromic performance of the composite material.

[0036] In addition, the composite material selected in the present invention is polyvinyl pyrrolidone, which has a certain reducibility and is an electron donor. By compounding it with silicotungstic acid, electrons can be transferred from polyvinyl pyrrolidone to silicotungstic acid under light stimulation, thereby realizing the photochromic properties of the composite material. In addition, the method is simple and easy to operate, does not require complex high-temperature and high-pressure equipment, saves costs, and can meet the application requirements of electro-induced / photo-induced dual-response color-changing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 H4[SiW prepared in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2 12 O 40 ] / Physical picture of PVP color-changing material;

[0038] Figure 2 H4[SiW prepared in Example 1 and Comparative Examples 3 and 4 of the present invention 12 O 40 ] / Physical picture of PVP color-changing material;

[0039] Figure 3 H4[SiW prepared in Example 1 of the present invention 12 O 40 ] / Infrared spectrum of PVP color-changing material;

[0040] Figure 4 H4[SiW prepared in Example 1 of the present invention 12 O 40 ] / XRD spectrum of PVP color-changing material;

[0041] Figure 5 H4[SiW prepared in Example 1 of the present invention 12 O 40 ] / Thermogravimetric diagram of PVP color-changing material;

[0042] Figure 6 It is a response time curve graph of the display device;

[0043] Figure 7 It is a curve diagram showing the transmittance variation of the device as the voltage changes;

[0044] Figure 8 A photograph showing the electrochromic color change of the device;

[0045] Fig. 9 Optical photos of the dual-response display device after UV irradiation for different time periods;

[0046] Fig.10 Restore the transmittance curve of the coloring process for the dual-response display device;

[0047] Fig.11 This is the transmittance curve of the dual-response display device during oxidation fading;

[0048] Fig.12 Schematic diagram of the pattern display of the smart window system made for the dual-response display device. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the embodiments.

[0050] Example 1

[0051] Weigh 3 g of silicotungstic acid raw material and dissolve it in 25 mL of deionized water at room temperature 25°C to obtain an initial solution. Then place the solution in a magnetic stirrer, add lithium hydroxide powder in small amounts repeatedly while stirring continuously, use a pH meter to adjust the solution pH to 5, and continue stirring for 10 min. Then weigh 0.3 g of polyvinyl pyrrolidone and add it to the above solution in small amounts repeatedly while stirring continuously to fully dissolve it. The reaction is carried out under light-proof conditions and stirred continuously for 3 h to obtain a colorless and transparent sol. Finally, freeze-dry it for 48 h to obtain H4[SiW 12 O 40 ] / PVP composite material.

[0052] Example 2

[0053] The difference between Example 2 and Example 1 is that the pH of the solution is adjusted to 6.5, and the other conditions are exactly the same.

[0054] Example 3

[0055] The difference between Example 3 and Example 1 is that the pH of the solution is adjusted to 4, and the other conditions are exactly the same.

[0056] Comparative Example 1

[0057] The difference between Comparative Example 1 and Example 1 is that the pH of the solution is adjusted to 3, and the other conditions are exactly the same.

[0058] Comparative Example 2

[0059] The difference between Comparative Example 2 and Example 1 is that the pH of the solution is adjusted to 7.5, and the other conditions are exactly the same.

[0060] Examples 1-3 and Comparative Examples 1-2 investigate the effect of pH on the prepared H4[SiW12 O 40 ] / PVP composite material. In this process, we fixed the amount of PVP added to 10% of the mass of silicotungstic acid. The experimental samples obtained in Example 1-2 and Comparative Example 1-2 are as follows Figure 1 As shown in the figure and the experimental process, we can see that when the pH value is 3, after adding PVP, during the continuous stirring process, PVP will not dissolve and will form insoluble flocculent precipitates; as the pH value continues to increase, it can be found that after adding PVP, under the condition of continuous stirring, PVP will completely dissolve to form a stable and transparent sol precursor solution, and the same results will be obtained in the pH range of 4~6.5; and when the pH value gradually increases to 7.5, PVP will not dissolve again. Therefore, we determined that the appropriate pH range is 4~6.5.

[0061] Example 4

[0062] The difference between Example 4 and Example 1 is that the added amount of polyvinyl pyrrolidone is 5% of the mass of silicotungstic acid, i.e., 0.15 g, and the other conditions are exactly the same.

[0063] Example 5

[0064] The difference between Example 5 and Example 1 is that the amount of polyvinyl pyrrolidone added is 15% of the mass of silicotungstic acid, i.e., 0.45 g, and the other conditions are exactly the same.

[0065] Comparative Example 3

[0066] The difference between Comparative Example 3 and Example 1 is that the added amount of polyvinyl pyrrolidone is 3% of the mass of silicotungstic acid, i.e., 0.09 g, and the other conditions are exactly the same.

[0067] Comparative Example 4

[0068] The difference between Comparative Example 4 and Example 1 is that the amount of polyvinyl pyrrolidone added is 20% of the mass of silicotungstic acid, i.e., 0.6 g, and the other conditions are exactly the same.

[0069] In the present invention, the content of PVP has an important influence on whether the material can achieve the performance of electro-induced / photo-induced dual response. Therefore, Examples 1, 4-5 and Comparative Examples 3-4 explored the influence of different PVP contents in the synthesis conditions, such as Figure 2As shown. The pH value of the fixed solution in this process is 5. From the above figure and the experimental process, it can be seen that when the content of PVP is 3% of the mass of silicotungstic acid, a good sol solution cannot be formed, so that PVP cannot well coat silicotungstic acid, which will not only affect the subsequent synthesis reaction, but also affect the color change performance of the final material. Because insufficient PVP cannot provide enough electrons in the color change process, it may reduce its color change performance. With the continuous increase of PVP content, a stable and transparent sol precursor solution is gradually formed; and when the content of PVP increases to 20% of the mass of silicotungstic acid, due to the viscosity of PVP polymer, the viscosity of the solution is too large, and it is difficult to continue stirring, so that silicotungstic acid and PVP cannot be fully and evenly mixed, which is not conducive to the synthesis reaction of silicotungstic acid and PVP. Therefore, we determined that the appropriate PVP content is 5~15%.

[0070] Characterization of materials:

[0071] Example 1 H4[SiW 12 O 40 The ] / PVP composite material has the most suitable viscosity and transparency. The composite material prepared in Example 1 was characterized by infrared, XRD and thermogravimetric analysis.

[0072] In order to compare the changes in the corresponding absorption peak positions, we also give the pure phase PVP and H4[SiW 12 O 40 ] infrared spectrum, the infrared spectrum obtained is as follows Figure 3 As shown in the figure, it can be seen that the OH in water molecules (wave number 3500 cm) appears in the infrared spectra of the three substances. -1 This is basically consistent with the reports in the literature. 12 O 40 ] / PVP composite material infrared spectrum shows both PVP and H4[SiW 12 O 40 ] is a characteristic peak located at 1015 cm -1 、970 cm -1 、920 cm -1 and 799 cm -1 The absorption peaks at v (W=O d ), v (Si-O a ), v (WO b -W) and v (WO c -W) characteristic absorption peak (O a: oxygen coordinated with the central atom Si; O b :Connecting two trimetallic oxide clusters W3O 13 The bridging oxygen; O c : corner oxygen of a single trimetallic cluster; O d : terminal oxygen coordinated to only one W). 12 O 40 Compared with the infrared spectrum of the composite material, the 12 O 40 ] has not changed in number and position, indicating that H4[SiW 12 O 40 ] itself has no obvious change, which also shows that the PVP and H4[SiW 12 O 40 The existence of non-chemical bond interactions between the two is possible. -1 Department v The stretching vibration peak of (CH) is 1656 cm -1 Department v The stretching vibration peak of (C=O) is 1373~1496 cm -1 Department v The stretching vibration peaks of (C-H2) and 1170~1319 cm -1 Where v The stretching vibration peaks of (CN) are all characteristic absorption peaks of PVP. 12 O 40 The vibration absorption peak of C=O in the ] / PVP composite material shifts to a lower wave number, while the peak positions of other groups do not shift significantly, indicating that the PVP molecule may interact with silicotungstic acid through its carbonyl group and still maintains the basic structure of the polymer in the composite material.

[0073] For comparison, pure H4[SiW 12 O 40 ], PVP and the obtained composite material XRD results are shown in Figure 4 As shown in the figure, although the raw material used is Keggin-type silicotungstic acid with strong crystallinity, the composite material formed after reacting with PVP has no obvious diffraction peak and shows an amorphous structure. This is mainly related to the freeze-drying method used in the preparation of the composite material. During the freezing process, the sol quickly turns into a solid, and the silicotungstic acid does not have time to nucleate and grow from the liquid, thus turning into an amorphous solid.

[0074] The thermogravimetric analysis results obtained are as follows Figure 5 As shown in the figure, it can be seen that H4[SiW 12O 40 ] / PVP composites have three obvious weight loss processes. The weight loss process before 500 °C should be attributed to the thermal decomposition of PVP. When the temperature continues to rise, the weight loss in the second stage (500-800 °C) is attributed to the decomposition of H4[SiW 12 O 40 ], the weight loss of the third stage is H4[SiW 12 O 40 ] is caused by the thermal decomposition of its own Keggin structure, so we infer that the H4[SiW 12 O 40 ] accounts for about 60% and has a high solid content.

[0075] Electrochromic performance of dual-response display devices

[0076] Ketjen black was selected as the counter electrode material, and H4[SiW 12 O 40 ] / PVP composite color-changing material is used to prepare a dual-response display device. The display device is made of a transparent conductive ITO glass and a common glass with a Ketjen black counter electrode as a frame, and the prepared composite material is used as a color-changing material. The electrochromic performance of the prepared display device is tested. First, the response time of the display device at 728nm (the time required to reach 90% of the maximum light contrast) is studied. Figure 6 As shown, the calculated response time is: coloring time 9.9s, fading time 135.0s. Figure 7 The transmittance change curve of the display device under different voltages is shown. As the negative voltage continues to increase, the transmittance gradually decreases, indicating that the transmittance of the smart window can be controlled by adjusting the voltage. Figure 8 A photograph of the electrochromic color change of the display device is shown, and it can be seen that a reversible redox reaction can occur under the action of an electric field.

[0077] Photochromic performance of dual-response display devices

[0078] The photochromic properties of the dual-response display device were studied by coloring it with a 5W handheld UV lamp. Fig. 9 The following are optical photos of the dual-response device after UV irradiation for different times. As the UV irradiation time increases, the color of the device gradually turns blue and the blue color continues to deepen. When the irradiation time reaches 5 minutes, the color of the device reaches the darkest, and the color will not deepen as the irradiation time is extended. The transmittance curve of the dual-response display device during the reduction coloring process and the transmittance curve of the oxidation fading process are shown in Figure 2. Fig.10 and Fig.11As shown in the figure, the results show that as the color of the dual-response display device gradually turns blue, its transmittance in the entire visible light wavelength range gradually decreases. When the irradiation time reaches 300 s, the transmittance reaches a minimum value, and the value does not change after continued irradiation. We can determine that photochromism reaches the best value when the ultraviolet irradiation is 300s, at which time the maximum light contrast at 700nm reaches more than 80%.

[0079] In addition, the dual-response display device prepared in this embodiment can also realize the display of patterns by photochromic method. Fig.12 A smart window system made using the dual-response display device was demonstrated, which can write and erase patterns through the interaction of ultraviolet (UV) light and oxygen (O2). The following is a detailed analysis of the process:

[0080] (1) UV writing:

[0081] First, the smart window is illuminated through a mask using UV light, a process called "UV writing."

[0082] The UV light triggers a chemical reaction in the window material, causing the material to change color or transparency, creating a pattern on the window.

[0083] (2) O2 erase:

[0084] Next, the pattern written by UV light can be erased by allowing oxygen to react with the material treated with UV light. The oxygen participates in the redox reaction of the material, restoring the material to its original state, causing the pattern to disappear.

[0085] (3) Cycle process:

[0086] The image shows a cyclic process where UV writing and O2 erasing can be performed alternately, allowing different patterns to be written and erased repeatedly on the smart window. This reversibility makes the smart window highly flexible and can be used to dynamically display information or as an interface for variable privacy control.

[0087] By simply controlling the interaction of UV light and oxygen, precise control of window transparency and color and complex pattern changes can be achieved. Therefore, the prepared display devices can be applied to a variety of scenarios, such as building exterior walls, car windows, electronic device displays, etc.

Claims

1. A H4[SiW 12 O 40 ] / The preparation method of PVP color-changing material is characterized by: The steps include: S1, silicotungstic acid H4[SiW 12 O 40 ]The raw materials are dissolved in deionized water to obtain an initial solution; S2. When the solution obtained in step S1 is fully dissolved, lithium hydroxide powder is added in portions under constant stirring, the pH of the solution is adjusted, and then stirred for 10 minutes; S3, dissolving polyvinyl pyrrolidone PVP in the solution obtained in step S2 under constant stirring, stirring for 3 h to obtain a colorless transparent solution; S4, directly freeze-dry the solution in step S3 for 48 h to obtain H4[SiW 12 O 40 ] / PVP electro-induced / photo-induced dual-response color-changing material, the H4[SiW 12 O 40 ] / PVP electrochromic / photochromic dual-response materials should be stored in a dry place at low temperature; In step S2, the pH of the solution is adjusted to 4-6.5; The H4[SiW 12 O 40 ] / Application of PVP color-changing materials in the preparation of electro- / photo-induced dual-response display devices.

2. H4[SiW according to claim 1 12 O 40 ] / The preparation method of PVP color-changing material is characterized by: The mass of the PVP is (5-15)% of the mass of silicotungstic acid.

3. H4[SiW according to claim 1 12 O 40 ] / The preparation method of PVP color-changing material is characterized by: The reaction in step S3 is carried out under light-proof conditions, and the light-proof method is to use any one of tin foil, aluminum foil or opaque black cloth to block the reaction.

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