A method for efficiently batch producing composite microspheres with photonic crystal structural color

Abstract

The application provides a method for efficiently and in batches preparing composite microspheres with a photonic crystal structural color, which comprises the following steps: 1) preparing monodispersed SiO2 nanoparticles; 2) preparing a dispersed phase solution and a continuous phase solution; 3) preparing microemulsion droplets; and 4) preparing SiO2-C-HEMA photonic crystal composite microspheres. The method has low preparation cost, simple process flow, fast preparation speed and controllable particle size, and the obtained SiO2-C-HEMA composite microspheres have obvious structural colors, and are easy to be industrially and in batches prepared and practically applied.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material science, and relates to photonic crystal microsphere preparation, in particular to a method for efficiently and in batches preparing SiO2-C-HEMA composite microspheres with photonic crystal structural color. BACKGROUND

[0002] At present, organic chemical pigments are mostly used for dyeing in daily life and industry, which can cause environmental pollution and easily fade over time. Unlike the coloring mode of organic pigments, structural color is an optical effect in which various colors are produced by refraction, diffuse reflection, diffraction or interference of light waves by sub-microstructures. The pure physical coloring process is environmentally friendly.

[0003] A photonic crystal microsphere is a symmetrical sphere in which single-dispersed nanoparticles are periodically arranged, and can overcome the angle specificity of traditional photonic crystals to maintain consistent structural color within a wide observation angle. The photonic crystal microsphere has applications in many fields such as manufacturing pigments, anti-counterfeiting patterns, sensors, optical codes and the like. SiO2 nanoparticles have good biocompatibility, simple preparation and stable properties, and have become a widely used raw material for photonic crystal preparation. At present, the preparation of photonic crystal microspheres has made certain breakthroughs, but there are still some challenges. Although microfluidics can continuously prepare photonic crystal microspheres, it is still difficult to prepare small-diameter photonic crystal microspheres and in batches. The SPG membrane emulsification technology can provide a large number of single-dispersed droplets, but the preparation cycle is long and the processing process is complicated. The vortex technology can overcome the above difficulties, has a short preparation and processing time, and greatly improves the production efficiency. In addition, the particle size, good biocompatibility of hydroxy acrylate monomers and optical transparency can be controlled by vortex time during the preparation process, which will bring great advantages in the application process.

[0004] Whether the vortex technology can be applied to the preparation of photonic crystal microspheres, and a new method for providing efficient and batch production of composite microspheres with photonic crystal structural color has become a technical problem to be solved. SUMMARY

[0005] The present application provides a method for efficiently and in batches preparing SiO2-C-HEMA composite microspheres with photonic crystal structural color, which has low preparation cost, simple process flow, fast preparation, controllable particle size, obvious structural color of the obtained SiO2-C-HEMA composite microspheres, and is easy to industrialize and apply.

[0006] Technical scheme: The method for efficiently and in batches preparing composite microspheres with photonic crystal structural color provided by the present application has the characteristics that it comprises the following steps:

[0007] 1) Preparation of monodisperse SiO2 nanoparticles: monodisperse SiO2 nanoparticles are prepared by seed method;

[0008] 2) Preparation of dispersed phase solution and continuous phase solution: the prepared monodisperse SiO2 nanoparticles and carbon black nanoparticles are dissolved in polymer monomer, ultrasonic dispersion is uniform, then initiator and crosslinking agent are added, and oscillation is used to make them uniformly dispersed to prepare a dispersed phase solution, and a solution that is not miscible with the dispersed phase solution is used as a continuous phase solution;

[0009] 3) Preparation of microemulsion droplets: the dispersed phase solution is added to a centrifuge tube containing the continuous phase solution, the centrifuge tube is placed in a vortex shaker, and the shearing force of the solution is adjusted to cut the dispersed phase into a large number of microemulsion droplets;

[0010] 4) Preparation of SiO2-C-HEMA photonic crystal composite microspheres: the microemulsion droplets are heated under slow stirring to polymerize and solidify, cooled, and left to stand, and the lower layer of the precipitate is washed with a cleaning solution, and after drying, stable photonic crystal composite microspheres with bright colors are obtained.

[0011] In step 1), the particle size of the monodisperse SiO2 nanoparticles is 190-310 nm.

[0012] In step 2), the mass of the carbon black nanoparticles is 0.05-0.40% of the mass of the monodisperse SiO2 nanoparticles; the polymer monomer is a monomer containing hydroxy acrylate; the continuous phase solution is a mixture solution of n-hexadecane and different emulsifiers or surfactants; and the emulsifier is one of Span 80, Span 85, or Span 65.

[0013] The polymer monomer contains one or more of hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0014] In step 2), the mass concentration of the monodisperse SiO2 nanoparticles dissolved in the polymer monomer is 0.1-0.3 g / mL, the mass ratio of the carbon black nanoparticles to the monodisperse SiO2 nanoparticles is 0.0005-0.004:1, the amount of the initiator added is 0.1-1% of the volume of the polymer monomer, and the amount of the crosslinking agent added is 0.5-1.5% of the volume of the polymer monomer.

[0015] In step 2), the crosslinking agent is one or more of adipic acid diacrylate, succinic acid diacrylate, and ethylene glycol dimethacrylate; and the initiator is one or more of azobisisobutyronitrile, potassium persulfate, and benzoyl peroxide.

[0016] In step 3), the vortex shearing time is 1-5 min.

[0017] The curing temperature of the microemulsion in step 4) is 55-100 DEG C, the curing time is 2-10 hours, and the stirring speed is 200-700 rpm.

[0018] The cleaning liquid in step 4) is one or more mixed solutions of n-hexane, n-pentane, n-heptane, n-octane, petroleum ether, and isopropyl alcohol.

[0019] The diameter of the SiO2-C-HEMA photonic crystal composite microspheres in step 4) is 1-10 microns.

[0020] Compared with the prior art, the present application has the following advantages: the present application provides a method for efficiently and batch-preparing SiO2-C-HEMA composite microspheres with photonic crystal structural color, and the obtained photonic crystal microspheres are organic-inorganic composite microspheres. The microspheres are entirely wrapped by polyhydroxy acrylate, and the photonic crystal spheres are formed by self-assembly of SiO2 nanoparticles and carbon black.

[0021] The preparation process of the present application is simple and efficient, and is more suitable for rapid batch production. A large number of droplets can be formed by vortexing for a short time, and the corresponding photonic crystal composite microspheres can be obtained by polymerization after heating. During the heating process, the polymerization process of hydroxy acrylate is synchronized with the self-assembly process of SiO2 and carbon black, and the self-assembled spheres are fixed in the polymer network, which has certain guarantee for the structural stability.

[0022] The present application can easily obtain small-particle photonic crystal microspheres. Through vortexing, photonic crystal composite microspheres as small as 1 micron can be obtained, which greatly widens the application range and increases the research and application in the fields of electrochemistry, electrochemiluminescence, photocatalysis, photoelectrochemistry, and pigment dyes.

[0023] The present application can easily obtain photonic crystal composite microspheres with obvious structural color, and different structural colors of photonic crystal composite microspheres can be prepared by adjusting the particle size of SiO2 nanoparticles and the proportion of carbon black.

[0024] The photonic crystal composite microspheres of the present application have strong structural stability. The traditional photonic crystal microspheres are only combined to form spheres by the weak balance of van der Waals force and electrostatic repulsion, and are prone to be contaminated. The composite microspheres in the present application are individual entities wrapped by polymers, which can to some extent buffer, prevent pollution, etc. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The present application is a flow chart for preparing SiO2-C-HEMA photonic crystal composite microspheres by vortex cutting method;

[0026] Figure 2 The Fourier transform infrared spectrum of the SiO2-C-HEMA photonic crystal composite microspheres of the present invention is shown below.

[0027] Figure 3 This is a photograph of the SiO2-C-HEMA photonic crystal composite microspheres prepared in Example 1 of the present invention.

[0028] Figure 4 This is a scanning electron microscope image of the SiO2-C-HEMA photonic crystal composite microspheres of the present invention;

[0029] Figure 5 This is a photograph of the SiO2-C-HEMA photonic crystal composite microspheres prepared in Example 3 of the present invention.

[0030] Figure 6 The reflection spectrum of the SiO2-C-HEMA photonic crystal composite microspheres prepared in Example 3 of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1:

[0033] (1) First, add 40 mL of anhydrous ethanol, 0.72 mL of ammonia, and 8.28 mL of deionized water to a 150 mL three-necked flask. Then, in a water bath, maintain magnetic stirring at 200 rpm and heat to 60 °C, add 2.2 mL of TEOS, and continue the reaction at the same temperature and stirring speed for 24 h. Finally, a translucent, light sky-blue seed solution will be obtained. Next, under magnetic stirring at 200 rpm, add 15 mL of ammonia and 160 mL of anhydrous ethanol to a 250 mL three-necked flask, and add 2 mL of seed solution at room temperature (25 °C) and constant stirring speed. After 15 min, add a mixture of ethanol and TEOS (ethanol / TEOS volume ratio of 2:1) dropwise to one side of the three-necked flask at a rate of 0.1 mL / min; and add a mixture of ammonia, ethanol, and H2O (ammonia / ethanol / H2O volume ratio of 3:7:2) dropwise to the other side at a rate of 0.005 mL / min. During the reaction, small amounts of solution were added to a glass slide at various times to form a film, and the color was observed. The reaction was stopped when a blue film was obtained. After the reaction, the suspension was washed twice by centrifugation with deionized water and anhydrous ethanol at 9000 rpm for 3 minutes. After thorough washing, it was then dried in a vacuum drying oven at 55°C for 12 hours to obtain SiO2 nanoparticles with a particle size of approximately 190 nm.

[0034] (2) Preparation of dispersed phase solution and continuous phase solution: Weigh 1.0g of SiO2 nanoparticles and 0.0012g of carbon black and dissolve them in 4mL of hydroxyethyl methacrylate (HEMA) monomer. Disperse them evenly by ultrasonication. Add 40μL of initiator azobisisobutyronitrile and 0.028g of crosslinking agent ethylene glycol dimethacrylate and mix evenly to prepare the dispersed phase solution. Take 80mL of n-hexadecane and add 8mL of Span 80 and mix evenly to prepare the continuous phase solution.

[0035] (3) Preparation of microemulsion droplets: Take 1 mL of the above dispersed phase solution and 20 mL of the continuous phase solution and add them to a 50 mL centrifuge tube. Place the tube in a vortex shaker, turn on the switch, and vortex for 3 min to obtain the microemulsion droplet solution.

[0036] (4) Preparation of SiO2-C-HEMA photonic crystal composite microspheres: The centrifuge tube containing the microemulsion droplet solution was placed in an oil bath at 80℃ and 300 rpm for 8 hours. As the polymerization process progressed, the droplets gradually decreased in size, eventually yielding photonic crystal composite microspheres with structural color. The mixture was then allowed to stand for 60 minutes, and the lower precipitate was removed and washed with n-hexane. This process was repeated 2-5 times until the continuous phase was completely cleaned. Finally, SiO2-C-HEMA photonic crystal composite microspheres with a particle size of approximately 6 μm and structural color were obtained.

[0037] Appendix Figure 2 The Fourier transform infrared spectrum of the prepared SiO2-C-HEMA photonic crystal composite microspheres shows that SiO2, C, and HEMA are present in the composite microspheres without any deficiencies. The SiO2-C-HEMA photonic crystal composite microspheres prepared in Example 1 are as follows... Figure 3 As shown, (a) shows the stacked state of the photonic crystal composite microspheres against a white background, and (b) shows the state of the photonic crystal composite microspheres against a black background.

[0038] Example 2:

[0039] (1) First, the seed solution was prepared under the same conditions as in Example 1. Then, with magnetic stirring at 200 rpm, 15 mL of ammonia and 160 mL of anhydrous ethanol were added to a 250 mL three-necked flask. At room temperature (25°C) and constant stirring speed, 2 mL of the seed solution was added. After 15 min, a mixture of ethanol and TEOS (ethanol / TEOS volume ratio 2:1) was added dropwise to one side of the flask at a rate of 0.1 mL / min; while on the other side, a mixture of ammonia, ethanol, and H2O (ammonia / ethanol / H2O volume ratio 3:7:2) was added dropwise at a rate of 0.005 mL / min. During the reaction, small amounts of solution were added to a glass slide at various times to form a film, and the color was observed. The reaction was stopped when a green film was obtained. After the reaction, the suspension was washed twice by centrifugation with deionized water and anhydrous ethanol at 9000 rpm for 3 min. After thorough washing, the suspension was dried in a vacuum drying oven at 55°C for 12 h to obtain SiO2 nanoparticles with a particle size of approximately 240 nm.

[0040] (2) Preparation of dispersed phase solution and continuous phase solution: Weigh 0.5g of SiO2 nanoparticles and 0.0018g of carbon black and dissolve them in 2mL of hydroxyethyl methacrylate (HEMA) monomer. Disperse them evenly by ultrasonication. Add 30μL of initiator azobisisobutyronitrile and 0.020g of crosslinking agent ethylene glycol dimethacrylate and mix evenly to prepare the dispersed phase solution. Take 40mL of n-hexadecane and add 4mL of Span 80 and mix evenly to prepare the continuous phase solution.

[0041] (3) Preparation of microemulsion droplets: Take 1 mL of the above dispersed phase solution and 20 mL of the continuous phase solution and add them to a 50 mL centrifuge tube. Place the tube in a vortex shaker, turn on the switch, and vortex for 1 min to obtain the microemulsion droplet solution.

[0042] (4) Preparation of SiO2-C-HEMA photonic crystal composite microspheres: The centrifuge tube containing the microemulsion droplet solution was placed in an oil bath at 55℃ and 200 rpm for 10 h. As the polymerization process progressed, the droplets gradually decreased in size, eventually yielding photonic crystal composite microspheres with structural color. The mixture was then allowed to stand for 60 min, and the lower precipitate was removed and washed with n-hexane. This process was repeated 2-5 times until the continuous phase was completely cleaned. Finally, SiO2-C-HEMA photonic crystal composite microspheres with a particle size of approximately 10 μm and structural color were obtained.

[0043] The SiO2-C-HEMA photonic crystal composite microspheres were characterized by Nova field emission scanning electron microscopy, and the SEM images are shown below. Figure 4 As shown in the figure, the composite microspheres range in size from 1 to 10 μm, and the spheres tend to have a perfect shape in nature.

[0044] Example 3:

[0045] (1) First, the seed solution was prepared under the same conditions as in Example 1. Then, with magnetic stirring at 200 rpm, 15 mL of ammonia and 160 mL of anhydrous ethanol were added to a 250 mL three-necked flask. At room temperature (25°C) and constant stirring speed, 2 mL of the seed solution was added. After 15 min, a mixture of ethanol and TEOS (ethanol / TEOS volume ratio 2:1) was added dropwise to one side of the flask at a rate of 0.1 mL / min; while on the other side, a mixture of ammonia, ethanol, and H2O (ammonia / ethanol / H2O volume ratio 3:7:2) was added dropwise at a rate of 0.005 mL / min. During the reaction, small amounts of solution were added to a glass slide at various times to form a film, and the color was observed. The reaction was stopped when a red film was obtained. After the reaction, the suspension was washed twice by centrifugation with deionized water and anhydrous ethanol at 9000 rpm for 3 min. After thorough washing, the suspension was dried in a vacuum drying oven at 55°C for 12 h to obtain SiO2 nanoparticles with a particle size of approximately 300 nm.

[0046] (2) Preparation of dispersed phase solution and continuous phase solution: Weigh 0.25g of SiO2 nanoparticles and 0.0006g of carbon black and dissolve them in 1mL of hydroxyethyl methacrylate (HEMA) monomer. Disperse them evenly by ultrasonication. Add 15μL of initiator azobisisobutyronitrile and 0.007g of crosslinking agent ethylene glycol dimethacrylate and mix evenly to prepare the dispersed phase solution. Take 20mL of n-hexadecane and add 3mL of Span 80 and mix evenly to prepare the continuous phase solution.

[0047] (3) Preparation of microemulsion droplets: Take 1 mL of the above dispersed phase solution and 20 mL of the continuous phase solution and add them to a 50 mL centrifuge tube. Place the tube in a vortex shaker, turn on the switch, and vortex for 5 min to obtain the microemulsion droplet solution.

[0048] (4) Preparation of SiO2-C-HEMA photonic crystal composite microspheres: The centrifuge tube containing the microemulsion droplet solution was placed in an oil bath at 95℃ and 600 rpm for 3 hours. As the polymerization process progressed, the droplets gradually decreased in size, eventually yielding photonic crystal composite microspheres with structural color. The mixture was then allowed to stand for 60 minutes, and the lower precipitate was removed and washed with n-hexane. This process was repeated 2-5 times until the continuous phase was completely cleaned. Finally, SiO2-C-HEMA photonic crystal composite microspheres with a particle size of approximately 3 μm and structural color were obtained.

[0049] The SiO2-C-HEMA photonic crystal composite microspheres prepared in Example 3 are as follows: Figure 5 As shown, (a) shows the stacked state of the photonic crystal composite microspheres against a white background, and (b) shows the state of the photonic crystal composite microspheres against a black background. Their reflection spectra are as follows: Figure 6 As shown, the reflection is particularly strong in the red wavelength range.

[0050] This invention disperses SiO2 nanoparticles and carbon black together in a hydroxy acrylate monomer to form a dispersed phase. This dispersed phase is then subjected to vortex shearing in a continuous phase composed of n-hexadecane and a surfactant, forming numerous small droplets. Subsequently, under the confinement effect of these droplets, heating initiates polymerization to form photonic crystal composite microspheres. These composite microspheres exhibit stable structure, vibrant structural colors, and the intensity of color can be altered by changing the carbon content. This method is low-cost, simple to operate, and rapid in preparation, making it easier to scale up for mass production.

Claims

1. A method for efficient batch preparation of composite microspheres with photonic crystal structure colors, characterized in that: Includes the following steps: 1) Preparation of monodisperse SiO2 nanoparticles: Monodisperse SiO2 nanoparticles were prepared by seed method; the particle size of the monodisperse SiO2 nanoparticles was 190nm-310nm. 2) Preparation of Dispersed Phase Solution and Continuous Phase Solution: The prepared monodisperse SiO2 nanoparticles and carbon black nanoparticles were dissolved in polymer monomers, ultrasonically dispersed, and then an initiator and crosslinking agent were added. The mixture was shaken to ensure uniform dispersion and prepare a dispersed phase solution. A solution immiscible with the dispersed phase solution was selected as the continuous phase solution. The mass of the carbon black nanoparticles was 0.05%-0.40% of the mass of the monodisperse SiO2 nanoparticles. The polymer monomer was a monomer containing hydroxy acrylate. The continuous phase solution was a mixture of n-hexadecane with different emulsifiers or surfactants. The emulsifier was one of Span 80, Span 85, or Span 65. The polymer monomer was hydroxyethyl methacrylate. The mass concentration of the monodisperse SiO2 nanoparticles dissolved in the polymer monomer was 0.1 g / mL-0.3 g / mL. The amount of initiator added was 0.1%-1% of the volume of the polymer monomer, and the amount of crosslinking agent added was 0.5%-1.5% of the volume of the polymer monomer. 3) Preparation of microemulsion droplets: The dispersed phase solution is added to a centrifuge tube containing a continuous phase solution. The centrifuge tube is placed in a vortex mixer, and the vortex shearing time is controlled to cut the dispersed phase into microemulsion droplets by the shear force of the solution. The vortex shearing time is 1 min to 5 min. 4) Preparation of SiO2-C-HEMA photonic crystal composite microspheres: Microemulsion droplets were stirred and heated to polymerize and solidify, cooled and allowed to stand, the lower precipitate was washed with a cleaning solution, and dried to obtain composite microspheres with photonic crystal structure color; the curing temperature of the microemulsion was 55℃-100℃, the curing time was 2h-10h, and the stirring speed was 200rpm-700rpm; the cleaning solution was one or a mixture of n-hexane, n-pentane, n-heptane, n-octane, petroleum ether, and isopropanol; the diameter of the SiO2-C-HEMA photonic crystal composite microspheres was 1μm-10μm.

Images