Use of a liquid responsive photonic crystal

Abstract

The application discloses an application of a liquid responsive photonic crystal. The application utilizes the fact that a liquid responsive silicon dioxide photonic crystal changes from white to a single color when it meets water or alcohol, and the photonic crystal returns to the initial white color when the liquid evaporates and dries. The reversible and recyclable liquid responsive color changing characteristic expands the application of the photonic crystal in many fields such as anti-fake packaging, color sensing and optical devices.

Description

Technical Field

[0001] This invention belongs to the field of photonic crystal material preparation and anti-counterfeiting, and relates to the application of a liquid-responsive photonic crystal. Background Technology

[0002] Photonic crystal materials, due to their photonic bandgap characteristics, can achieve structural color generation, and structural color can be modulated by controlling their photonic bandgap. Therefore, photonic crystal materials have wide applications in optical devices, information displays, color sensing, and anti-counterfeiting packaging. Among them, silica is a simple-to-prepare, high-performance, and inexpensive photonic crystal material. Its nanospheres can self-assemble into photonic crystals, thus exhibiting vibrant colors. In recent years, silica photonic crystals have been widely studied and applied. Existing research shows that most silica photonic crystals suffer from complex preparation processes and insignificant color changes in liquid responses, which greatly limits their application in color sensing, packaging anti-counterfeiting, and other fields. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a liquid-responsive photonic crystal, its preparation method and application, so as to solve the problem that the application of silicon dioxide photonic crystals is limited by the indistinct color change due to liquid response in the prior art.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] An application of a liquid-responsive photonic crystal, wherein the liquid-responsive photonic crystal is a silica microsphere, and the silica microsphere changes from white to a certain monochromatic color after contact with a liquid; when the liquid evaporates, the silica microsphere returns to white; the monochromatic color is a color other than white.

[0006] A further improvement of the present invention is that:

[0007] Preferably, the liquid is water, ethanol, acrylic acid, ethylene glycol, or n-hexane.

[0008] Preferably, the silica microspheres exhibit a hexagonal closed-loop stacked structure.

[0009] Preferably, the silica microspheres are ordered in both long and short ranges.

[0010] Preferably, the method for preparing silica microspheres includes the following steps:

[0011] Step 1: Mix anhydrous ethanol and tetraethyl orthosilicate, and stir to obtain seed solution A;

[0012] Step 2: Mix anhydrous ethanol and ammonia, stir, and obtain reaction solution B;

[0013] Step 3: Add mixed solution C dropwise to reaction solution B, and solution D is formed after the reaction; the mixed solution C is a mixture of TEOS solution and anhydrous ethanol.

[0014] Step 4: Let solution D stand at room temperature until the milky white particles settle at the bottom of the container. Remove the supernatant, leaving the settled milky white particles. Wash and centrifuge the milky white particles to obtain silica microspheres.

[0015] Step 5: Dry the silica microspheres and grind them to obtain a liquid-responsive photonic crystal.

[0016] Preferably, in step 1, the volume ratio of anhydrous ethanol to tetraethyl orthosilicate is (3-6):(4-8).

[0017] Preferably, in step 2, the volume ratio of anhydrous ethanol to ammonia is (190-200):(15-20).

[0018] Preferably, in step 3, the volume ratio of reaction solution B to mixed solution C is (7-14):(5-15).

[0019] Preferably, in step 3, the reaction temperature is 28-38℃ and the reaction time is 4-5h.

[0020] Preferably, in step 5, the drying temperature is 40-45℃ and the drying time is 6-10h.

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

[0022] This invention discloses an application of a liquid-responsive photonic crystal, wherein the liquid-responsive photonic crystal is a silica microsphere. The silica microsphere has good dispersibility. When the silica photonic crystal comes into contact with easily evaporating liquids such as water or ethanol, it can change from white to a certain monochromatic color. When the liquid evaporates and dries, the photonic crystal returns to its initial white color. This liquid-responsive color-changing characteristic makes it have broad application prospects in many fields such as anti-counterfeiting packaging, color response, and optical devices.

[0023] Furthermore, the silica particles in this invention are very uniform in size. For 220nm silica, the particle size difference is about 35nm. The arrangement of the assembled photonic crystals is not only ordered in the short range but also in the long range. When it comes into contact with liquids such as water or ethanol, the gaps change from air to liquid filling, the effective refractive index of the structure changes, and the Bragg reflection at the interface between the two is also enhanced, thus exhibiting color.

[0024] Furthermore, the preparation method of these silica microspheres is simple, uses readily available and inexpensive raw materials, and is easy to mass-produce. Using tetraethyl orthosilicate as the silicon source, anhydrous ethanol as the solvent, and ammonia as the catalyst, silica microspheres with good monodispersity are generated. After drying, liquid-responsive photonic crystals are obtained. The entire preparation method involves mild and easily controllable reaction conditions, employing a multi-step dropping method to achieve controllable preparation of silica microspheres with uniform particle size.

[0025] Furthermore, during the preparation process, the ethanol solution of nano-silica was allowed to stand, and after separating the supernatant, the resulting silica microspheres had a narrower particle size distribution and were more uniform in size, whereas the previous silica particle size distribution range was wider.

[0026] This invention also discloses a liquid-responsive photonic crystal, which is prepared by the above-described method. The method utilizes readily available raw materials, is simple in process, inexpensive, and easily mass-produced. Monodisperse silica microspheres are prepared using tetraethyl orthosilicate as the silicon source, anhydrous ethanol as the solvent, and ammonia as the catalyst. After drying, the liquid-responsive photonic crystal is obtained. The silica liquid-responsive photonic crystal obtained by the above preparation method changes from white to a certain monochromatic color upon contact with liquids such as water or ethanol. After the liquid evaporates and dries, the silica photonic crystal returns to its original white state. This characteristic allows for better application in fields such as anti-counterfeiting packaging based on liquid-responsive color change, color response, and optical devices. Attached Figure Description

[0027] Figure 1 This is a SEM image of the plane of the liquid-responsive SiO2 photonic crystal prepared in Example 1 of this invention.

[0028] Figure 2 This is a SEM image of the cross-section of the liquid-responsive SiO2 photonic crystal prepared in Example 3 of this invention.

[0029] Figure 3 This is a 3D image of the surface of the liquid-responsive SiO2 photonic crystal prepared in Example 4 of this invention, taken using a super depth-of-field microscope.

[0030] Figure 4 This is a 2D image of the surface of the liquid-responsive SiO2 photonic crystal prepared in Example 5 of this invention before and after contact with water, obtained using a super depth-of-field microscope.

[0031] Figure 5 This is a diagram showing the color-changing effect of the liquid-responsive SiO2 photonic crystals (strip and powder forms) prepared in Example 6 of this invention when exposed to water.

[0032] Figure 6 This is a particle size distribution diagram of the liquid-responsive SiO2 microspheres prepared in Example 8 of the present invention.

[0033] Figure 7 These are images showing the color change and reversible change effects of the liquid-responsive SiO2 photonic crystals prepared in Examples 8-10 of this invention under dry, liquid-wetted, and re-drying conditions.

[0034] Figure 8 These are the reflection spectra of the liquid-responsive SiO2 photonic crystals prepared in Examples 11-13 of this invention before and after contact with water.

[0035] Figure 9 This is a cyclic diagram of the reflection curves of the liquid-responsive SiO2 photonic crystal prepared in Example 16 of this invention under wet and dry conditions. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0037] This invention discloses a liquid-responsive photonic crystal and its preparation method, which specifically includes the following steps:

[0038] (1) Add 3-6 mL of anhydrous ethanol and 4-8 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0039] (2) Add 190-200 mL of anhydrous ethanol and 15-20 mL of ammonia to a three-necked flask, stir at low speed, and add 7-14 mL of the seed solution A obtained in (1) to form reaction solution B.

[0040] (3) Slowly add a mixture of TEOS solution and anhydrous ethanol solution C (the volume ratio of each component in solution C is TEOS: anhydrous ethanol = 3:2) to the reaction solution B formed in (2). The amount of TEOS and anhydrous ethanol solution C added is 5-15 mL. The synthesis rate of silica is controlled by the rate of adding the mixed reagent, so that the prepared silica microspheres have a large particle size range. The added mixed reagent is a mixture of TEOS and anhydrous ethanol solution C. Solution B and the added mixed reagent react at 28-38℃ for 4-5 h to form solution D.

[0041] (4) After the reaction in (3) is complete, the resulting solution D is left to stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round-bottom flask, the supernatant is removed, leaving the settled milky white particles. Then, an appropriate amount of anhydrous ethanol and deionized water are added and centrifuged and washed twice. After the last centrifugation, the supernatant is completely discarded to obtain SiO2 microsphere blocks. In this process, centrifugation and washing to remove the supernatant can effectively remove microspheres with smaller particle sizes, resulting in silica microspheres with more uniform size. The microspheres exist in the form of microsphere blocks, which are many silica microspheres that have agglomerated together after centrifugation and are macroscopically blocky.

[0042] (5) After drying the SiO2 microspheres at 40-45℃ for 6-10 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal. In this embodiment, well-dispersed silica microspheres are prepared in one step. During this process, grinding the microspheres can reduce the agglomeration of silica, so that the microspheres are composed of a single or a combination of a few microspheres, which helps to make the subsequent assembly of the photonic crystal more orderly and is beneficial to the presentation of structural colors.

[0043] The prepared silica microspheres can change from white to a certain monochromatic color when exposed to easily evaporating liquids such as water, ethanol, acrylic acid, ethylene glycol, or n-hexane. liquid After evaporation and drying, the photonic crystal returns to its initial white color. Monochromatic colors are other non-white colors.

[0044] Example 1

[0045] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0046] (2) Add 196 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0047] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0048] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0049] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0050] Figure 1 This is a SEM image of the surface of the liquid-responsive SiO2 photonic crystal prepared in this embodiment. As can be seen from the image, the photonic crystal structure is orderly arranged, and the SiO2 microspheres are uniformly distributed throughout the entire plane, exhibiting a tight hexagonal closed packing, proving that the photonic crystal as a whole exhibits a long-range ordered and short-range ordered arrangement.

[0051] Example 2

[0052] (1) Add 3 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0053] (2) Add 195 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0054] (3) Slowly add 5 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 3 ml of TEOS solution and 2 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0055] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0056] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0057] Example 3

[0058] (1) Add 6 mL of anhydrous ethanol and 7 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0059] (2) Add 196 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0060] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0061] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0062] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0063] Figure 2 This is a SEM image of the cross-section of the liquid-responsive SiO2 photonic crystal prepared in this embodiment. As can be seen from the image, the photonic crystal structure is orderly arranged with obvious layering. The SiO2 microspheres are arranged in a tetragonal packing, and the overall structure shows a long-range ordered and short-range ordered arrangement.

[0064] Example 4

[0065] (1) Add 5 mL of anhydrous ethanol and 4 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0066] (2) Add 194 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0067] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0068] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0069] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0070] Figure 3 This is a 3D image of the surface of the liquid-responsive SiO2 photonic crystal prepared in this embodiment using a super depth-of-field microscope. As can be seen from the image, the surface of the photonic crystal has good flatness and no obvious protrusions or depressions.

[0071] Example 5

[0072] (1) Add 6 mL of anhydrous ethanol and 8 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0073] (2) Add 196 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0074] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 35°C for 5 h to form solution D.

[0075] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0076] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0077] Figure 4 This is a 2D image of the surface of the liquid-responsive SiO2 photonic crystal prepared in this embodiment before and after it comes into contact with water, using a super depth-of-field microscope. As can be seen from the image, after the photonic crystal is wetted by water, the color of the surface changes from a whitish grayish-green to a bright and vivid green.

[0078] Example 6

[0079] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0080] (2) Add 190 mL of anhydrous ethanol and 17 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0081] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0082] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0083] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0084] Figure 5 The image shows the color-changing effect of the liquid-responsive SiO2 photonic crystal (strip and powder) prepared in this embodiment when exposed to water. As can be seen from the image, the liquid-responsive photonic crystal is white in a dry state, but turns bright green when exposed to water.

[0085] Example 7

[0086] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0087] (2) Add 197 mL of anhydrous ethanol and 18 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0088] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0089] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0090] (5) After drying the SiO2 microspheres at 45°C for 7 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0091] Example 8

[0092] (1) Add 4 mL of anhydrous ethanol and 7 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0093] (2) Add 190 mL of anhydrous ethanol and 15 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0094] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 36°C for 5 h to form solution D.

[0095] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0096] (5) After drying the SiO2 microspheres at 40°C for 7 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0097] Figure 6 This is a particle size distribution diagram of the liquid-responsive SiO2 microspheres prepared in this embodiment. As can be seen from the figure, the SiO2 microspheres prepared by this method have very uniform particle size, with a size range of about 35 nm, and most microspheres have a size difference within the range of 20 nm.

[0098] Example 9

[0099] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0100] (2) Add 200 mL of anhydrous ethanol and 20 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0101] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0102] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0103] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0104] Example 10

[0105] (1) Add 5 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0106] (2) Add 200 mL of anhydrous ethanol and 19 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0107] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0108] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0109] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0110] Figure 7 The images show the color change and reversible change effects of the liquid-responsive SiO2 photonic crystals prepared in Examples 8-10 under dry, liquid-wetted, and re-drying conditions. As can be seen from the images, the photonic crystal is white in the dry state, and turns a single color when it comes into contact with water or ethanol. After the solution evaporates and dries, it returns to white.

[0111] Example 11

[0112] (1) Add 4 mL of anhydrous ethanol and 7 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0113] (2) Add 191 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 10 mL of seed solution A obtained in (1) to form reaction solution B.

[0114] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 30°C for 5 h to form solution D.

[0115] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0116] (5) After drying the SiO2 microspheres at 42℃ for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0117] Example 12

[0118] (1) Add 3 mL of anhydrous ethanol and 4 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0119] (2) Add 196 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 7 mL of seed solution A obtained in (1) to form reaction solution B.

[0120] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 28°C for 5 h to form solution D.

[0121] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0122] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0123] Example 13

[0124] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0125] (2) Add 196 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 14 mL of seed solution A obtained in (1) to form reaction solution B.

[0126] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 38°C for 4 hours to form solution D.

[0127] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0128] (5) After drying the SiO2 microspheres at 45°C for 10 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0129] Figure 8 The figures show the reflection spectra of the liquid-responsive SiO2 photonic crystals prepared in Examples 11-13 before and after contact with water. As can be seen from the figures, the peak of the reflection curve of the photonic crystal is not obvious before contact with water and the color saturation is poor. After contact with water, the peak of the reflection curve of the photonic crystal is obvious and the color saturation is improved.

[0130] Example 14

[0131] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0132] (2) Add 195 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 12 mL of seed solution A obtained in (1) to form reaction solution B.

[0133] (3) Slowly add 15 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 9 ml of TEOS solution and 6 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 4 h to form solution D.

[0134] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0135] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0136] Example 15

[0137] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0138] (2) Add 196 mL of anhydrous ethanol and 18 mL of ammonia to a three-necked flask, stir at low speed, and add 12 mL of seed solution A obtained in (1) to form reaction solution B.

[0139] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 35°C for 4 h to form solution D.

[0140] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0141] (5) After drying the SiO2 microspheres at 40℃ for 10h, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0142] Example 16

[0143] (1) Add 4 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0144] (2) Add 198 mL of anhydrous ethanol and 16 mL of ammonia to a three-necked flask, stir at low speed, and add 9 mL of seed solution A obtained in (1) to form reaction solution B.

[0145] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 33°C for 5 h to form solution D.

[0146] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0147] (5) After drying the SiO2 microspheres at 45°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0148] Figure 9 This is a cyclic graph of the reflection curves of the liquid-responsive SiO2 photonic crystal prepared in this embodiment under wet and dry conditions. As can be seen from the graph, the change in reflectivity is minimal under repeated wet and dry conditions, indicating that the color change process of the photonic crystal in response to the solution is reversible and cyclic.

[0149] Example 17

[0150] (1) Add 4 mL of anhydrous ethanol and 7 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0151] (2) Add 196 mL of anhydrous ethanol and 15 mL of ammonia to a three-necked flask, stir at low speed, and add 11 mL of seed solution A obtained in (1) to form reaction solution B.

[0152] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 34℃ for 5 h to form solution D.

[0153] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0154] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0155] Example 18

[0156] (1) Add 3 mL of anhydrous ethanol and 6 mL of tetraethyl orthosilicate to a beaker and stir magnetically for 30 min. The tetraethyl orthosilicate is evenly dispersed in the anhydrous ethanol to form seed solution A.

[0157] (2) Add 193 mL of anhydrous ethanol and 17 mL of ammonia to a three-necked flask, stir at low speed, and add 14 mL of seed solution A obtained in (1) to form reaction solution B.

[0158] (3) Slowly add 10 ml of a mixture of TEOS solution and anhydrous ethanol solution C to the reaction solution B formed in (2) (the amount of each component added to solution C is 6 ml of TEOS solution and 4 ml of anhydrous ethanol), control the synthesis rate of silicon dioxide, and react at 28°C for 5 h to form solution D.

[0159] (4) Let the solution D obtained in (3) stand at room temperature for 3 days. After all the milky white particles have settled at the bottom of the round bottom flask, remove the supernatant and leave the settled milky white particles. Add an appropriate amount of anhydrous ethanol and deionized water and centrifuge and wash twice. After the last centrifugation, pour off all the supernatant to obtain SiO2 microspheres.

[0160] (5) After drying the SiO2 microspheres at 40°C for 6 hours, grind them thoroughly to obtain a liquid-responsive SiO2 photonic crystal.

[0161] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An application of a liquid-responsive photonic crystal, characterized in that, The liquid-responsive photonic crystal is a silica microsphere. When the silica microsphere photonic crystal comes into contact with a liquid, it changes from white to a certain monochromatic color; when the liquid evaporates, the silica microsphere photonic crystal returns to white; the monochromatic color is any color other than white; the liquid is water, ethanol, acrylic acid, ethylene glycol, or n-hexane; The silica microsphere photonic crystal exhibits a hexagonal closed-stack structure. The silica microsphere photonic crystal exhibits both long-range and short-range order. The preparation method of silica microspheres includes the following steps: Step 1: Mix anhydrous ethanol and tetraethyl orthosilicate, and stir to obtain seed solution A; Step 2: Mix anhydrous ethanol and ammonia, stir, add seed solution A, stir again to obtain reaction solution B; Step 3: Add mixed solution C dropwise to reaction solution B, and solution D is formed after the reaction; the mixed solution C is a mixture of TEOS solution and anhydrous ethanol; the reaction temperature is 28-38℃, and the reaction time is 4-5h; Step 4: Let solution D stand at room temperature until the milky white particles settle at the bottom of the container. Remove the supernatant, leaving the settled milky white particles. Wash and centrifuge the milky white particles to obtain silica microspheres. Step 5: Dry the silica microspheres and then grind them to obtain a liquid-responsive photonic crystal; the drying temperature is 40-45℃ and the drying time is 6-10h.

2. The application of a liquid-responsive photonic crystal according to claim 1, characterized in that, In step 1, the volume ratio of anhydrous ethanol to tetraethyl orthosilicate is (3-6):(4-8).

3. The application of a liquid-responsive photonic crystal according to claim 1, characterized in that, In step 2, the volume ratio of anhydrous ethanol to ammonia is (190-200):(15-20).

4. The application of a liquid-responsive photonic crystal according to claim 1, characterized in that, In step 3, the volume ratio of reaction solution B to mixed solution C is (7-14):(5-15).

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