A method for preparing amorphous photonic crystal microspheres by using superamphiphobic surface

Abstract

The application belongs to the technical field of material synthesis, and specifically discloses a method for preparing amorphous photonic crystal microspheres by using a super-biphobic surface, which comprises the following steps: firstly, pre-crystallizing by using a centrifugal operation to preform a poly(styrene-methyl methacrylate-acrylic acid) nanomicrosphere emulsion; and secondly, performing evaporation-induced self-assembly on the super-biphobic surface to quickly form amorphous, high-spheroid, uniform microspheres with short-range order and long-range disorder. The amorphous photonic crystal microspheres prepared by using the application are of uniform structure, stable performance and simple components. Therefore, the material used in the application is simple, the cost is low, the preparation process is simple and fast, the operability is strong, the preparation method is easy to implement, and the application is easy to be used in industrialization and large-scale production.

Description

Technical Field

[0001] This invention relates to the field of materials synthesis technology, and in particular to a method for preparing amorphous photonic crystal microspheres using a superhydrophobic surface. Background Technology

[0002] Photonic crystals, due to their periodic micro / nano structures, significantly influence photon propagation, resulting in the unique phenomenon of structural color. Traditional photonic crystals exhibit a pronounced angle-dependent structural color, with the color changing with the angle of incident light. Amorphous photonic crystals, possessing short-range disorder and long-range order in their micro / nano structures, exhibit angle-independent structural color properties, making them promising for applications such as biosensoring and structural color pigments. Existing techniques commonly utilize spraying, chemical etching, and self-assembly to prepare amorphous photonic crystal microspheres, thin films, and pigment powders. Superhydrophobic surfaces possess large contact angles and low roll-off angles, enabling droplets to form highly spherical shapes while preventing pinning effects of the solid-liquid-gas three-phase lines during surface evaporation and drying. Therefore, they are widely used in evaporation-induced self-assembly techniques for preparing photonic crystal microspheres.

[0003] For example, Chinese Patent Publication No. CN108355588A discloses a method for synthesizing microspheres on a superhydrophobic surface, which includes the following steps: a. providing a substrate having at least one surface that is a superhydrophobic surface; b. providing a droplet that is solidified on the superhydrophobic surface of the substrate; c. causing the droplet to solidify on the superhydrophobic surface of the substrate to form microspheres. The method of the present invention is novel, simple, and effective, requiring no emulsifier, no complex equipment, and can be flexibly adapted to the synthesis of different types of microspheres.

[0004] For example, Chinese Patent Publication No. CN111892722A discloses a method for preparing polymer microspheres on a superhydrophobic surface, which includes the following steps: fabricating a superhydrophobic surface on a substrate; preparing a polymer spinning solution using a polymer material, and spinning a polymer fiber array on the superhydrophobic surface using a microfluidic spinning method; cutting the polymer fiber array using laser thermal cutting to obtain several segments of short polymer fibers; heating the substrate with the attached short polymer fibers until the short polymer fibers melt to form a spherical structure, and then cooling to obtain the microspheres. This method can effectively solve the problems of expensive preparation equipment and unsatisfactory morphology of the polymer microspheres obtained by existing methods, and can flexibly control the size of the target polymer microspheres.

[0005] For example, Chinese Patent Publication No. CN105177714A discloses a method for preparing photonic crystal microparticles with controllable morphology and color angle-independent properties. This method involves mixing Fe3O4 nanoparticles, carbon black nanoparticles, graphene nanoparticles, or a mixture thereof with an emulsion containing monodisperse colloidal microspheres. The mixture is then sprayed, dipped, or inkjet printed onto a superhydrophobic substrate to form emulsion droplets with a diameter of 11 μm to 1.6 mm. After drying, spherical or concave spherical photonic crystal microparticles with color angle-independent properties are obtained. Alternatively, Fe3O4 nanoparticles, carbon black nanoparticles, graphene nanoparticles, or a mixture thereof, ethanol, or a surfactant are mixed with an emulsion containing monodisperse colloidal microspheres. This mixture is then sprayed, dipped, or inkjet printed onto a superhydrophobic substrate to form emulsion droplets with a diameter of 11 μm to 1.6 mm. After drying, ellipsoidal colored photonic crystal microparticles with color angle-independent properties are obtained, and the aspect ratio of the microparticles is controllable. It is characterized by its colorfastness and environmental friendliness, and has broad application prospects in the fields of pigments, displays, and sensors.

[0006] However, the microspheres prepared using superhydrophobic surfaces are mostly used for synthesizing polymer microspheres or curing other polymers, with less attention paid to the preparation of amorphous photonic crystals—special photonic crystals whose structural color properties are not angle-dependent. Furthermore, existing research techniques for angle-independent color photonic crystal microparticles involve complex compositions and costly raw materials. These issues limit the application of amorphous photonic crystal microspheres in biosensoring and structural color pigments. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for preparing amorphous photonic crystal microspheres using a superhydrophobic surface, resulting in uniform microspheres with structure color properties that are angle-independent.

[0008] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0009] The first technical solution proposed in this invention is a method for preparing amorphous photonic crystal microspheres using a superhydrophobic surface, comprising the following steps:

[0010] S1. Mix poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion with deionized water at a volume ratio of 1:4, remove the supernatant after centrifugation, and sonicate the lower emulsion to obtain an emulsion with structural color.

[0011] S2. Under the conditions of 21°C and 65% humidity, an emulsion with structural color is dropped onto an aluminum sheet with a transparent superhydrophobic coating, and left to stand to allow the emulsion with structural color to self-assemble into amorphous photonic crystal microspheres.

[0012] Furthermore, the preparation process of the poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion is as follows:

[0013] 1) First, remove the polymerization inhibitor by vacuum distillation of styrene: Add styrene and 5% sodium hydroxide solution to a volumetric flask and wash twice by inverting until colorless. After standing and the layers appear, separate the layers with a separatory funnel and remove the upper liquid. Then wash with ultrapure water until neutral. Add 0.5% cuprous chloride during distillation. First, heat in a water bath at 60°C to remove the foredistillate components. Then, raise the temperature to 68°C~75°C to collect the main fraction to obtain styrene with the polymerization inhibitor removed. Let it cool at room temperature and store it in a refrigerator for later use.

[0014] 2) Synthesis reaction: Take 2g of 1g / L sodium dodecylbenzenesulfonate emulsifier solution, 0.5g of ammonium bicarbonate solution and the remaining ultrapure water, totaling 80mL, and place them in a three-necked flask. Heat in a water bath at 60℃ and stir thoroughly with a magnetic stirrer at 350rpm. Then add 19g of redistilled styrene, 1g of methyl methacrylate, and 1g of acrylic acid. Maintain stirring speed of 350rpm and heat to 60℃ and hold for 1h. Then heat to 70℃ and hold for 30min. Slowly add 12mL of ammonium persulfate initiator solution at a rate of 3s / drop and stir at constant temperature for 1.5h. After heating to 80℃, slowly add 4mLAPS solution at the same rate and stir at constant temperature for 2h. Finally, slowly add 4mLAPS solution again and continue the reaction for 2h. After the reaction is completed, remove the flask, let it cool, and bottle it to obtain a monodisperse poly(styrene-methyl methacrylate-acrylic acid) nanosphere suspension.

[0015] Furthermore, in step S1, the centrifugation speed is 8000 rpm and the centrifugation time is 60 min.

[0016] Furthermore, in step S2, the preparation process of the transparent superhydrophobic coating is as follows:

[0017] 1) Preparation of nanosphere mixed silica sol: Solution A was prepared by mixing anhydrous ethanol with a monodisperse polystyrene nanosphere emulsion with a diameter of 50 nm and a mass concentration of 5% at a mass ratio of 5:1; Solution B was prepared by mixing tetraethyl silicate (TEOS), 0.1 mol / L hydrochloric acid, and anhydrous ethanol at a mass ratio of 1:1:1.5; 6 g of Solution A and 0.2 g of Solution B were mixed by shaking and stirred thoroughly with a magnetic stirrer for 40 min, and then the partially hydrolyzed prepolymer solution was ultrasonically dispersed for 15 min to obtain nanosphere mixed silica sol;

[0018] 2) Aluminum sheet pretreatment: Clean the aluminum sheet thoroughly, then immerse it in anhydrous ethanol solution and sonicate for 30 minutes. Next, immerse the aluminum sheet in deionized water and sonicate for 10 minutes. After removal, dry it with nitrogen or compressed air. Immerse the treated aluminum sheet in 1 mol / L hydrochloric acid for 1 minute, then rinse it with ultrapure water. After drying it again with nitrogen or compressed air, treat it with plasma for 5 minutes, then remove it and store it in a dust-free environment.

[0019] 3) Spraying: Place the pretreated aluminum sheet on an 85℃ hot plate and heat for 5 minutes or until the surface temperature stabilizes. Then, using a spray gun with a pressure of 0.40MPa and a distance of 15cm from the aluminum sheet surface, spray the prepared nanospheres mixed with silica sol onto the aluminum sheet surface and cure it into a film.

[0020] 4) Calcination: Transfer the aluminum sheet with the surface solidified into a film to a muffle furnace, heat it to 500°C at a heating rate of 2°C / min and hold it for 2 hours, then let it cool naturally to obtain an aluminum sheet with a transparent coating.

[0021] 5) Low surface energy modification: The aluminum sheet with transparent coating prepared above is plasma treated and then placed in a sealed vacuum dryer. A fluorinated atmosphere is formed in a vacuum environment by volatile 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The surface is then left to stand for 6 hours for fluorosilane modification. After modification, the sample surface is rinsed with anhydrous ethanol and dried with nitrogen or compressed air to obtain a transparent superhydrophobic coating.

[0022] Furthermore, in step S2, the settling time is 30-60 minutes.

[0023] The second technical solution proposed in this invention is an amorphous photonic crystal microsphere prepared using the above method.

[0024] The third technical solution proposed in this invention is the application of the amorphous photonic crystal microspheres in biological detection and the preparation of structural color pigments.

[0025] Compared with existing technologies, this invention first utilizes centrifugation to pre-crystallize a poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion, and then induces self-assembly through evaporation on a superaphthoic surface. This allows for the rapid formation of amorphous, highly spherical, and uniform microspheres exhibiting short-range order and long-range disorder. This invention enables the mass production of amorphous photonic crystal microspheres with uniform structure, stable performance, and simple composition. Therefore, the materials used in this invention are simple and inexpensive, the preparation process is simple and rapid, highly operable, and the preparation method is easy to implement and readily applicable for industrial-scale application. Attached Figure Description

[0026] Figure 1An optical microscope image of the amorphous photonic crystal microspheres prepared in Example 1.

[0027] Figure 2 This is a SEM image of the internal structure of the amorphous photonic crystal microspheres prepared in Example 1.

[0028] Figure 3 The images show the reflection spectra of the amorphous photonic crystal microspheres prepared in Example 1 at different angles. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0030] Unless otherwise specified, all raw materials and reagents used in the following examples were commercially available.

[0031] In this embodiment, a transparent superhydrophobic coating is first prepared, and the specific preparation process is as follows:

[0032] 1) Preparation of nanosphere mixed silica sol: Solution A was prepared by mixing anhydrous ethanol with a monodisperse polystyrene nanosphere emulsion with a diameter of 50 nm and a mass concentration of 5% at a mass ratio of 5:1; Solution B was prepared by mixing tetraethyl silicate (TEOS), 0.1 mol / L hydrochloric acid, and anhydrous ethanol at a mass ratio of 1:1:1.5; 6 g of Solution A and 0.2 g of Solution B were mixed by shaking and stirred thoroughly with a magnetic stirrer for 40 min, and then the partially hydrolyzed prepolymer solution was ultrasonically dispersed for 15 min to obtain nanosphere mixed silica sol;

[0033] 2) Aluminum sheet pretreatment: Clean the aluminum sheet thoroughly, then immerse it in anhydrous ethanol solution and sonicate for 30 minutes. Next, immerse the aluminum sheet in deionized water and sonicate for 10 minutes. After removal, dry it with nitrogen or compressed air. Immerse the treated aluminum sheet in 1 mol / L hydrochloric acid for 1 minute, then rinse it with ultrapure water. After drying it again with nitrogen or compressed air, treat it with plasma for 5 minutes, then remove it and store it in a dust-free environment.

[0034] 3) Spraying: Place the pretreated aluminum sheet on an 85℃ hot plate and heat for 5 minutes or until the surface temperature stabilizes. Then, using a spray gun with a pressure of 0.40MPa and a distance of 15cm from the aluminum sheet surface, spray the prepared nanospheres mixed with silica sol onto the aluminum sheet surface and cure it into a film.

[0035] 4) Calcination: Transfer the aluminum sheet with the surface solidified into a film to a muffle furnace, heat it to 500°C at a heating rate of 2°C / min and hold it for 2 hours, then let it cool naturally to obtain an aluminum sheet with a transparent coating.

[0036] 5) Low surface energy modification: The aluminum sheet with transparent coating prepared above is plasma treated and then placed in a sealed vacuum dryer. A fluorinated atmosphere is formed in a vacuum environment by volatile 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The surface is then left to stand for 6 hours for fluorosilane modification. After modification, the sample surface is rinsed with anhydrous ethanol and dried with nitrogen or compressed air to obtain a transparent superhydrophobic coating for later use.

[0037] Then, a monodisperse poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion was prepared, and the specific preparation process is as follows:

[0038] 1) First, remove the polymerization inhibitor by vacuum distillation of styrene: Add styrene and 5% sodium hydroxide solution to a volumetric flask and wash twice by inverting until colorless. After standing and the layers appear, separate the layers with a separatory funnel and remove the upper liquid. Then wash with ultrapure water until neutral. Add 0.5% cuprous chloride during distillation. First, heat in a water bath at 60°C to remove the foredistillate components. Then, raise the temperature to 68°C~75°C to collect the main fraction to obtain styrene with the polymerization inhibitor removed. Let it cool at room temperature and store it in a refrigerator for later use.

[0039] 2) Synthesis reaction: Take 2g of 1g / L sodium dodecylbenzenesulfonate emulsifier solution, 0.5g of ammonium bicarbonate solution and the remaining ultrapure water, totaling 80mL, and place them in a three-necked flask. Heat in a water bath at 60℃ and stir thoroughly with a magnetic stirrer at 350rpm. Then add 19g of redistilled styrene, 1g of methyl methacrylate, and 1g of acrylic acid. Maintain stirring at 350rpm and heat to 60℃ for 1h, then heat to 70℃ and hold for 30min. Slowly add 12mL of ammonium persulfate initiator solution at a rate of 3s / drop and stir at constant temperature for 1.5h. After heating to 80℃, slowly add 4mLAPS solution at the same rate and stir at constant temperature for 2h. Finally, slowly add another 4mLAPS solution and continue the reaction for 2h. After the reaction is complete, remove the flask, let it cool, and bottle it to obtain a monodisperse poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion for later use.

[0040] Example 1

[0041] 1) Add 1 mL of monodisperse poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion and 4 mL of deionized water to a 7 mL centrifuge tube. Centrifuge at 8000 rpm for 60 min, remove the supernatant, and sonicate to homogenize thoroughly to obtain an emulsion with structural color.

[0042] 2) Amorphous poly(styrene-methyl methacrylate-acrylic acid) photonic crystal microspheres were prepared by evaporation-induced self-assembly. Specifically, at 21°C and 65% humidity, 10 μL of emulsion with structural color was pipetted and dropped onto an aluminum sheet with a transparent superhydrophobic coating. After standing for 60 min, self-assembled amorphous photonic crystal microspheres were obtained.

[0043] Example 2

[0044] 1) Add 1 mL of poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion and 4 mL of deionized water to a 7 mL centrifuge tube. Centrifuge at 8000 rpm for 60 min, remove the supernatant, and sonicate to homogenize thoroughly to obtain an emulsion with structural color.

[0045] 2) Amorphous poly(styrene-methyl methacrylate-acrylic acid) photonic crystal microspheres were prepared by evaporation-induced self-assembly. Specifically, at 21°C and 65% humidity, 10 μL of emulsion with structural color was pipetted and dropped onto an aluminum sheet with a transparent superhydrophobic coating. After standing for 30 min, self-assembled amorphous photonic crystal microspheres were obtained.

[0046] Example 3

[0047] 1) Add 1 mL of poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion and 4 mL of deionized water to a 7 mL centrifuge tube. Centrifuge at 8000 rpm for 60 min, remove the supernatant, and sonicate to homogenize thoroughly to obtain an emulsion with structural color.

[0048] 2) Amorphous poly(styrene-methyl methacrylate-acrylic acid) photonic crystal microspheres were prepared by evaporation-induced self-assembly. Specifically, at 21°C and 65% humidity, 10 μL of emulsion with structural color was pipetted and dropped onto an aluminum sheet with a transparent superhydrophobic coating. After standing for 45 min, self-assembled amorphous photonic crystal microspheres were obtained.

[0049] Taking the amorphous photonic crystal microspheres prepared in Example 1 as an example, the optical microscope image of the amorphous photonic crystal microspheres is as follows. Figure 1 As shown, the SEM image of the internal structure of the amorphous photonic crystal microsphere is as follows. Figure 2 As shown. By Figure 1 and Figure 2 It can be seen that the amorphous photonic crystal microspheres are uniform in size and have a fully symmetrical structure that is infinitely close to a sphere. The surface is smooth, intact, and crack-free. The surface is composed of periodically arranged colloidal particles, while the internal structure is an amorphous arrangement with short-range order and long-range disorder.

[0050] The reflection spectra of the amorphous photonic crystal microsphere at different angles are shown below. Figure 3 As shown, by Figure 3 It can be seen that the reflection spectrum curves of light incident from multiple angles are very similar. At the same time, due to its structural characteristics, the light propagation characteristics are optimized, and its reflectivity peak can exceed 70%.

[0051] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing amorphous photonic crystal microspheres using a superhydrophobic surface, characterized in that, Includes the following steps: S1. A poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion with a volume ratio of 1:4 was mixed with deionized water. After centrifugation, the supernatant was removed. The centrifugation speed was 8000 rpm and the centrifugation time was 60 min. The lower emulsion was ultrasonically vibrated to homogenize it, resulting in an emulsion with structural color. The preparation process of the poly(styrene-methyl methacrylate-acrylic acid) nanosphere emulsion is as follows: 1) First, remove the polymerization inhibitor by vacuum distillation of styrene: Add styrene and 5% sodium hydroxide solution to a volumetric flask and wash twice by inverting until colorless. After standing and the layers appear, separate the upper liquid with a separatory funnel and remove the upper liquid. Then wash with ultrapure water until neutral. Add 0.5% cuprous chloride during distillation. First, heat in a water bath at 60°C to remove the foredistillate components, and then raise the temperature to 68°C~75°C to collect the main fraction to obtain styrene with the polymerization inhibitor removed. Let it cool at room temperature and store it in a refrigerator for later use. 2) Synthesis reaction: 2 g of 1 g / L sodium dodecylbenzenesulfonate emulsifier solution, 0.5 g of ammonium bicarbonate solution, and the remaining ultrapure water (80 mL total) were placed in a three-necked flask and heated in a 60 °C water bath with a magnetic stirrer at 350 rpm for thorough stirring. Then, 19 g of redistilled styrene, 1 g of methyl methacrylate, and 1 g of acrylic acid were added. The mixture was stirred at 350 rpm and heated to 60 °C for 1 h, then heated to 70 °C and held for 30 min. 12 mL of ammonium persulfate initiator solution was slowly added at a rate of 3 s / drop, and the mixture was stirred at a constant temperature for 1.5 h. After heating to 80 °C, 4 mL of APS solution was slowly added at the same rate, and the mixture was stirred at a constant temperature for 2 h. Finally, 4 mL of APS solution was slowly added again, and the reaction was continued for 2 h. After the reaction was completed, the mixture was removed, cooled, and bottled to obtain a monodisperse poly(styrene-methyl methacrylate-acrylic acid) nanosphere suspension. S2. Under the conditions of temperature 21 ℃ and humidity 65%, an emulsion with structural color is dropped onto an aluminum sheet with a transparent superhydrophobic coating, and left to stand to allow the emulsion with structural color to self-assemble into amorphous photonic crystal microspheres.

2. The method for preparing amorphous photonic crystal microspheres using a superhydrophobic surface according to claim 1, characterized in that, In step S2, the preparation process of the transparent superhydrophobic coating is as follows: 1) Preparation of nanosphere mixed silica sol: Solution A was prepared by mixing anhydrous ethanol with a monodisperse polystyrene nanosphere emulsion with a diameter of 50 nm and a mass concentration of 5% at a mass ratio of 5:1; Solution B was prepared by mixing tetraethyl silicate (TEOS), 0.1 mol / L hydrochloric acid, and anhydrous ethanol at a mass ratio of 1:1:1.5; 6 g of Solution A and 0.2 g of Solution B were mixed by shaking and stirred thoroughly with a magnetic stirrer for 40 min, and then the partially hydrolyzed prepolymer solution was ultrasonically dispersed for 15 min to obtain nanosphere mixed silica sol; 2) Aluminum sheet pretreatment: Clean the aluminum sheet, then immerse it in anhydrous ethanol solution and sonicate for 30 min. Then immerse the aluminum sheet in deionized water and sonicate for 10 min. After taking it out, dry it with nitrogen or compressed air. Immerse the treated aluminum sheet in 1 mol / L hydrochloric acid for 1 min. After taking it out, clean it with ultrapure water. After drying it again with nitrogen or compressed air, treat it with plasma for 5 min. Take it out and keep it away from dust for later use. 3) Spraying: Place the pretreated aluminum sheet on an 85 ℃ hot plate and heat for 5 min or until the surface temperature stabilizes. Then, use a spray gun with a pressure of 0.40 MPa and a distance of 15 cm from the aluminum sheet surface to spray the prepared nanospheres mixed with silica sol onto the aluminum sheet surface and cure it into a film. 4) Calcination: The aluminum sheet with the surface solidified into a film is transferred to a muffle furnace and heated to 500°C at a heating rate of 2°C / min and held for 2 hours. Then it is naturally cooled to obtain an aluminum sheet with a transparent coating. 5) Low surface energy modification: The aluminum sheet with transparent coating prepared above is subjected to plasma treatment and then placed in a sealed vacuum dryer. A fluorinated atmosphere is formed in a vacuum environment by volatile 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The surface is then left to stand for 6 h for fluorosilane modification. After modification, the sample surface is rinsed with anhydrous ethanol and dried with nitrogen or compressed air to obtain a transparent superhydrophobic coating.

3. The method for preparing amorphous photonic crystal microspheres using a superhydrophobic surface according to claim 1, characterized in that, In step S2, the settling time is 30-60 minutes.

4. An amorphous photonic crystal microsphere prepared by the method according to any one of claims 1-3.

5. The application of the amorphous photonic crystal microspheres as described in claim 4 in biodetection and preparation of structural color pigments.

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