Liquid photonic crystal color paste, preparation method and its application in rapid construction of large-area photonic crystals

Abstract

The present invention relates to a liquid photonic crystal color paste, a preparation method, and its application in the rapid construction of large-scale photonic crystals, belonging to the field of photonic crystal structure color generation technology. The present invention solves the problem of difficult controllable large-scale preparation of high-concentration photonic crystal elementary nano-microsphere dispersions. It mainly solves the problem of H generation due to the thermal decomposition of the initiator by adding a pH regulator during the emulsion polymerization process. + , which lowers the pH of the polymerization system and reduces the emulsifying ability of the emulsifier molecules, thereby causing the problem of instability in the polymerization reaction system. A high-concentration photonic crystal elementary nano-microsphere dispersion is obtained by direct synthesis, and then a liquid photonic crystal colorant for the rapid construction of large-area photonic crystals is prepared based on the high-concentration photonic crystal elementary nano-microsphere dispersion.

Description

Technical Field

[0001] The present invention relates to a liquid photonic crystal color paste, a preparation method and application thereof in the rapid construction of large-area photonic crystals, and belongs to the technical field of photonic crystal structure color generation. Background Art

[0002] Photonic crystals are composed of two or more materials with different refractive indices arranged in a periodic pattern. Due to their high brightness, high color saturation, and iridescent effect, they have great potential value in many fields such as textile ecological coloring, and bring opportunities for sustainable development. At present, the construction of photonic crystals on textile substrates through colloidal self-assembly using colloidal nanospheres as structural elements is considered to be the simplest and most effective method to achieve biomimetic structural coloration of textiles. It has low equipment requirements, a controllable assembly process, and is easy to obtain long-range ordered structures. However, conventional colloidal self-assembly requires complex processes such as crystal nucleation and crystal growth, which usually takes more than several hours, making it difficult to achieve rapid construction of photonic crystal structures.

[0003] To this end, researchers have prepared liquid photonic crystals (LPCs) with pre-crystallized forms as assembly intermediates to accelerate assembly. LPCs are pre-crystallized photonic crystals filled with a liquid (usually water). They exhibit vibrant structural colors and possess excellent dynamic resilience. Their pre-crystallized structure can disassemble under external force (with the consequent loss of structural color) and rapidly reconstruct upon removal of the force (with the subsequent reappearance of structural color). Using LPCs as assembly intermediates simplifies the complex process from monodisperse colloidal microspheres to colloidal crystals, significantly increasing the assembly speed of photonic crystals. However, the preparation of LPCs is typically time-consuming and difficult to control for large-scale production. Chinese invention patent CN113637362 A disperses SiO2 colloidal particles and a co-solvent, propylene carbonate, in the organic solvent ethanol. Rotary evaporation selectively removes the low-boiling-point organic solvent ethanol, raising the concentration of the SiO2 colloidal microspheres to a supersaturated state, causing them to spontaneously precipitate and form a reversibly resilient LPC. Although this method can cleverly obtain a liquid photonic crystal system, the preparation process is complicated, and SiO2 microspheres are difficult to prepare in large quantities. At the same time, a large amount of organic solvent ethanol is required, which causes waste after volatilization. Chinese invention patent CN 110054933 A and the paper (Y Li, Q Fan, X Wang, et al. Shear-induced assembly of liquid colloidal crystals for large-scale structural coloration of textiles [J]. Advanced Functional Materials, 2021, 31 (19): 2010746.) prepared a high volume fraction of PS liquid photonic crystals by high-speed centrifugation and static sedimentation of a low volume fraction polystyrene (PS) nanosphere dispersion. However, the centrifugal concentration process is too complicated and difficult to prepare in large quantities. The quality of the liquid photonic crystals obtained by centrifugation is difficult to control. One centrifugation is prone to produce hard crystals (local over-centrifugation). It is necessary to centrifuge and filter multiple times step by step to gradually obtain a high volume fraction of liquid photonic crystals. The preparation efficiency is low and the quality is unstable. Therefore, developing a method for rapid and controllable large-scale preparation of liquid photonic crystals is of great significance for the practical application of biomimetic photonic crystal structure chromogenic technology. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing liquid photonic crystal color paste. This method directly prepares a high-concentration photonic crystal elementary nano-microsphere dispersion by a synthetic method, and then prepares the liquid photonic crystal color paste. This method has the advantages of simple preparation method, high preparation efficiency, and large-scale preparation.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0007] S1, using emulsion synthesis method to prepare high concentration photonic crystal element nano-microsphere dispersion,

[0008] The nano-microsphere dispersion is made of monomers, water, and appropriate amounts of emulsifiers, initiators, and pH regulators. The total weight of the monomers and water is 100%, and the monomers account for 35-50 wt% of the total weight of the monomers and water. The pH regulator is used in an amount of 0.2-0.4 wt% of the monomers.

[0009] The monomer is selected from one or more of styrene (St), methyl methacrylate (MMA), methacrylic acid (MAA), hydroxyethyl acrylate (HEA) or butyl acrylate (BA);

[0010] S2. placing the high-concentration photonic crystal elementary nanosphere dispersion obtained in S1 into a dialysis bag for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0011] S3. Add an appropriate amount of melanin to the liquid photonic crystal system obtained in S2, mix uniformly with ultrasound, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0012] Preferably, in S1, the emulsifier accounts for 0.05-0.1 wt% of the monomer, and the initiator accounts for 0.2-0.4 wt% of the monomer.

[0013] Preferably, the high concentration photonic crystal elementary nanosphere dispersion in S1 is synthesized by the following method:

[0014] Mix the formulated amount of emulsifier, pH adjuster and water, and heat to 75°C to 90°C;

[0015] The monomers are added to the aqueous solution at one time, an inert gas is introduced to protect the reaction monomers, an initiator is added after stirring to initiate a polymerization reaction, and the reaction is carried out at a temperature of 75°C to 90°C until the monomers are completely polymerized. After the reaction is completed, the material is cooled to room temperature and discharged to obtain a high-concentration photonic crystal element nanosphere dispersion.

[0016] By adjusting the amount of emulsifier or initiator, nano-microsphere dispersions with different particle sizes can be prepared.

[0017] Preferably, the pH regulator is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate.

[0018] Preferably, the emulsifier is one or more of sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), sodium dodecylsulfonate (AS), and sodium dodecylpolyoxyethylene ether sulfate (AES); and the initiator is one or more of potassium persulfate (KPS), sodium persulfate (NaPS), and ammonium persulfate (APS).

[0019] Preferably, the inert gas is nitrogen or argon, the polymerization reaction time is 2 hours to 4 hours, the stirring time after adding the monomer is 20 to 40 minutes, and the stirring speed during the entire polymerization reaction process is 300 to 400 rpm.

[0020] Preferably, the nanospheres have a diameter of 160 to 340 nm, good sphericity, and a monodispersity index of less than 0.08.

[0021] Preferably, the melanin is one or a mixture of carbon black, water-soluble melanin, and the amount of melanin used is 0.1-1.0 wt % of the liquid photonic crystal.

[0022] Preferably, the molecular weight of the dialysis bag is 1000 to 3000.

[0023] A liquid photonic crystal color paste obtained by the preparation method of the present invention.

[0024] An application of the liquid photonic crystal color paste of the present invention in the rapid construction of large-area photonic crystals.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention solves the problem of difficult controllable large-scale preparation of high-concentration photonic crystal elementary nanosphere dispersions. Specifically, by adding a pH regulator during the emulsion polymerization process, the problem of H generated by thermal decomposition of the initiator is effectively solved. + , which causes the pH of the polymerization system to decrease, the emulsification ability of the emulsifier molecules to decrease, and leads to the problem of phase inversion of the system, thereby achieving a high concentration of photonic crystal elementary nano-microsphere dispersion by direct synthesis;

[0027] 2. The present invention dialyzes a high-concentration dispersion of photonic crystal-based nanospheres to remove oligomers and small molecule salts from the resulting high-concentration dispersion, thereby reducing the ionic strength of the system and increasing the dielectric constant. This increases the electrostatic repulsion potential between the nanospheres, allowing the nanospheres to spontaneously assemble under the balance of van der Waals forces and electrostatic repulsion to form a pre-crystallized liquid photonic crystal. This results in a brightly colored liquid photonic crystal paste. The prepared liquid photonic crystal paste exhibits a certain degree of fluidity and excellent dynamic reversibility, making it suitable for the rapid construction of large-scale photonic crystals. By regulating the particle size and mass fraction of the microspheres, the structural color of the liquid photonic crystal can be controlled.

[0028] 3. The method of the present invention is green and environmentally friendly. The obtained liquid photonic crystal color paste is environmentally friendly and brightly colored, which can effectively reduce the use and discharge of chemical colorants (dyes, pigments) and reduce environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a particle size distribution diagram of the photonic crystal element nanospheres prepared in Example 1;

[0030] Figure 2 This is an SEM image of the photonic crystal element nanospheres prepared in Example 2;

[0031] Figure 3 This is a digital photo of the liquid photonic crystal prepared in Example 3;

[0032] Figure 4 is an optical microscope photograph of the liquid photonic crystal prepared in Example 4;

[0033] Figure 5 is the reflectivity curve of the liquid photonic crystal prepared in Example 5;

[0034] Figure 6 This is the self-assembly process of the liquid photonic crystal prepared in Example 6 after being disturbed by external force;

[0035] Figure 7 This is a digital photo of the liquid photonic crystal paste prepared in Example 7;

[0036] Figure 8 These are digital photos of the photonic crystal structure color-producing fabrics prepared in Examples 7 and 8, wherein the upper photo is prepared in Example 7 and the lower photo is prepared in Example 8. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described in detail below through specific examples. It should be understood that the implementation of the present invention is not limited to the following examples, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0038] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0039] Example 1

[0040] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0041] (1) A 40 wt% concentration dispersion of photonic crystal primitive PSt nanoparticles was directly prepared by an emulsion synthesis method, specifically: 0.5 g of emulsifier SDS and 1.8 g of pH regulator Na2CO3 were added to 900 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 85°C; 600 g of monomer St was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 30 min at a speed of 350 rpm, and then 1.7 g of initiator KPS was added to initiate system polymerization. The mixture was reacted at 85°C for 3 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 40 wt% concentration dispersion of monodispersed PSt nanoparticles with a particle size of 216 nm.

[0042] (2) placing the PSt nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 2000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0043] (3) Add 0.5% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0044] Example 2

[0045] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0046] (1) A 35 wt% concentration of photonic crystal element PMMA nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.45 g of emulsifier SDBS and 2.0 g of pH regulator NaHCO3 were added to 975 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 80°C; 525 g of monomer MMA was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 40 min at a speed of 350 rpm, and then 1.8 g of initiator APS was added to initiate system polymerization. The mixture was reacted at 80°C for 2.5 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 35 wt% monodispersed PMMA nanosphere dispersion with a particle size of 273 nm.

[0047] (2) placing the PMMA nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 3000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0048] (3) Add 0.3% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and after standing, obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0049] Example 3

[0050] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0051] (1) A 40 wt% concentration of photonic crystal element PSt nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.52 g of emulsifier SDS and 2.0 g of pH regulator K2CO3 were added to 900 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 90°C; 600 g of monomer St was added to the above aqueous solution at one time, and argon was introduced to protect the reaction monomers. The mixture was mechanically stirred for 20 min at a speed of 400 rpm, and then 1.8 g of initiator KPS was added to initiate system polymerization. The reaction was carried out at 90°C for 3 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 40 wt% monodispersed PSt nanosphere dispersion with a particle size of 248 nm.

[0052] (2) placing the PSt nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 3000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0053] (3) Add 0.4% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0054] Example 4

[0055] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0056] (1) A 45 wt% concentration of photonic crystal element PHEA nano-microsphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.4 g of emulsifier SDS and 2.5 g of pH regulator Na2CO3 were added to 825 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 75°C; 675 g of monomer HEA was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 30 min at a speed of 400 rpm, and then 2.4 g of initiator KPS was added to initiate system polymerization. The mixture was reacted at 75°C for 2.5 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 45 wt% monodispersed PHEA nano-microsphere dispersion with a particle size of 257 nm.

[0057] (2) placing the PHEA nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 1000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized morphology exhibiting structural color;

[0058] (3) Add 0.35% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0059] Example 5

[0060] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0061] (1) A 40 wt% concentration of photonic crystal element PBA nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.45 g of emulsifier SDBS and 2.5 g of pH regulator KHCO3 were added to 900 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 85°C; 600 g of monomer BA was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 30 min at a speed of 350 rpm, and then 2.2 g of initiator APS was added to initiate system polymerization. The mixture was reacted at 85°C for 3.5 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 40 wt% monodispersed PBA nanosphere dispersion with a particle size of 216 nm.

[0062] (2) placing the PBA nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 3000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0063] (3) Add 0.3% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and after standing, obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0064] Example 6

[0065] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0066] (1) A 40 wt% concentration of photonic crystal element PSt nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.5 g of emulsifier AS and 2.0 g of pH regulator KHCO3 were added to 900 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 85°C; 600 g of monomer St was added to the above aqueous solution at one time, and argon was introduced to protect the reaction monomers. The mixture was mechanically stirred for 25 min at a speed of 300 rpm, and then 1.8 g of initiator KPS was added to initiate system polymerization. The reaction was carried out at 85°C for 3 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 40 wt% monodispersed PSt nanosphere dispersion with a particle size of 216 nm.

[0067] (2) placing the PSt nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 2000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0068] (3) Add 0.2% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0069] Example 7

[0070] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0071] (1) A 35 wt% concentration of photonic crystal element PMMA nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.5 g of emulsifier AES and 2.5 g of pH regulator K2CO3 were added to 975 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 80°C; 525 g of monomer MMA was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 30 min at a speed of 350 rpm, and then 2.2 g of initiator KPS was added to initiate system polymerization. The mixture was reacted at 80°C for 4 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 35 wt% monodispersed PMMA nanosphere dispersion with a particle size of 195 nm.

[0072] (2) placing the PMMA nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 3000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0073] (3) Add 0.25% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0074] (4) Liquid photonic crystal color paste is applied to the fabric surface by external shear induced coating, and after heating treatment, a blue photonic crystal structure color-producing fabric with bright color and iridescent effect is obtained. Figure 8 superior.

[0075] Example 8

[0076] A method for preparing a liquid photonic crystal color paste, the method comprising the following steps:

[0077] (1) A 40 wt% concentration of photonic crystal element PSt nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.54 g of emulsifier AS and 2.5 g of pH regulator Na2CO3 were added to 750 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 85°C; 750 g of monomer St was added to the above aqueous solution at one time, and argon was introduced to protect the reaction monomers. The mixture was mechanically stirred for 30 min at a speed of 350 rpm, and then 1.8 g of initiator KPS was added to initiate system polymerization. The mixture was reacted at 85°C for 4 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 40 wt% monodispersed PSt nanosphere dispersion with a particle size of 256 nm.

[0078] (2) placing the PSt nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 2000 for dialysis to remove oligomers and small molecule salts in the system, thereby obtaining a liquid photonic crystal with a pre-crystallized form exhibiting structural color;

[0079] (3) Add 0.1% melanin (based on the weight of the liquid photonic crystal as 100%) to the liquid photonic crystal obtained in (2), mix evenly by ultrasonication, and let it stand to obtain a liquid photonic crystal color paste with bright and vivid structural color effect and dynamic recovery.

[0080] (4) Liquid photonic crystal color paste is applied to the fabric surface by external shear induced coating, and after heating treatment, a yellow photonic crystal structure color-producing fabric with bright color and iridescent effect is obtained. Figure 8 Down.

[0081] Comparative Example 1

[0082] (1) 0.5 g of emulsifier SDS and 1.8 g of pH regulator Na2CO3 were added to 900 mL of deionized water and stirred evenly to obtain an aqueous solution containing the emulsifier and pH regulator, which was then heated to 60°C; 600 g of monomer St was added to the aqueous solution at once, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 30 min at a speed of 350 rpm, and then 1.7 g of initiator KPS was added to initiate system polymerization. The mixture was reacted at 60°C for 3 h, cooled to room temperature, and discharged to obtain a PSt nanosphere dispersion.

[0083] (2) placing the PSt nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 3000 for dialysis to remove oligomers and small molecular salts in the system;

[0084] (3) 0.5% melanin (based on the weight of the PSt nanosphere dispersion as 100%) was added to the PSt nanosphere dispersion obtained in (2), and ultrasonically mixed. After standing, no structural color of the liquid photonic crystal was exhibited.

[0085] Comparative Example 2

[0086] 0.45 g of emulsifier SDBS was added to 975 mL of deionized water, stirred evenly to obtain an emulsifier-containing aqueous solution, and the temperature was raised to 80°C; 525 g of monomer MMA was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. Mechanical stirring was carried out for 40 minutes at a speed of 350 rpm, and then 1.8 g of initiator APS was added to initiate the polymerization of the system. The reaction was carried out at 80°C for about 2 hours. The system instantly thickened and became yogurt-like, and the polymerization reaction could not continue normally.

[0087] Comparative Example 3

[0088] (1) 0.45 g of emulsifier SDBS and 5.0 g of pH regulator NaHCO3 were added to 975 mL of deionized water and stirred evenly to obtain an aqueous solution containing the emulsifier and pH regulator, which was then heated to 80°C; 525 g of monomer MMA was added to the aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers. The mixture was mechanically stirred for 40 min at a speed of 350 rpm, and then 1.8 g of initiator APS was added to initiate system polymerization. The mixture was reacted at 80°C for 2.5 h, cooled to room temperature, and discharged to obtain a PMMA nanosphere dispersion.

[0089] (2) placing the PMMA nanosphere dispersion obtained in (1) into a dialysis bag with a molecular weight of 3000 for dialysis to remove oligomers and small molecule salts in the system;

[0090] (3) 0.3% melanin (based on the weight of the PMMA nanosphere dispersion as 100%) was added to the PMMA nanosphere emulsion obtained in (2), and ultrasonically mixed until uniform. After standing, no structural color of the liquid photonic crystal was observed.

[0091] Comparative Example 4

[0092] (1) A 40 wt% concentration of photonic crystal element PSt nanosphere dispersion was directly prepared by an emulsion synthesis method, specifically: 0.52 g of emulsifier SDS and 2.0 g of pH regulator K2CO3 were added to 900 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 90°C; 600 g of monomer St was added to the above aqueous solution at one time, and argon was introduced to protect the reaction monomers. The mixture was mechanically stirred for 20 min at a speed of 400 rpm, and then 1.8 g of initiator KPS was added to initiate system polymerization. The reaction was carried out at 90°C for 3 h until the monomers were completely polymerized. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a 40 wt% PSt nanosphere dispersion with a particle size of 248 nm.

[0093] (2) 0.4% melanin (based on the weight of the PSt nanosphere dispersion as 100%) was directly added to the PSt nanosphere dispersion obtained in (1), and ultrasonically mixed uniformly. After standing, no structural color of the liquid photonic crystal was exhibited.

[0094] Comparative Example 5

[0095] (1) A 25 wt% concentration of photonic crystal element PHEA nanoparticle dispersion was directly prepared by an emulsion synthesis method, specifically: 0.37 g of emulsifier SDS and 2.5 g of pH regulator K2CO3 were added to 1125 mL of deionized water, stirred evenly to obtain an aqueous solution containing the emulsifier and the pH regulator, and heated to 75°C; 375 g of monomer HEA was added to the above aqueous solution at one time, and nitrogen was introduced to protect the reaction monomers, mechanically stirred for 30 min at a speed of 400 rpm, and then 2.4 g of initiator KPS was added to initiate system polymerization, and the reaction was carried out at 75°C for 2.5 h until the monomers were completely polymerized. After the reaction was completed, the material was cooled to room temperature and discharged to obtain a 25 wt% PHEA nanoparticle dispersion; (2) The PHEA nanoparticle dispersion obtained in (1) was placed in a dialysis bag with a molecular weight of 1000 for dialysis to remove oligomers and small molecular salts in the system;

[0096] (3) 0.35% melanin (based on the weight of the PHEA nanosphere dispersion as 100%) was added to the PHEA nanosphere dispersion obtained in (2), and ultrasonically mixed. After standing, no structural color of the liquid photonic crystal was exhibited.

[0097] The particle size distribution of the photonic crystal element nanospheres prepared in Example 1 is shown in FIG. Figure 1 The prepared nanoparticles are of uniform size. It has been verified that the particle size distribution of the nanoparticles prepared in Examples 1-8 is narrow.

[0098] The SEM image of the photonic crystal element nanospheres prepared in Example 2 is shown in FIG. Figure 2 The prepared nano-microspheres have good sphericity. It has been verified that the nano-microspheres prepared in Examples 1-8 all have good sphericity.

[0099] The digital photo of the liquid photonic crystal prepared in Example 3 is shown in Figure 3 The prepared liquid photonic crystals have obvious iridescent effects. It has been verified that the digital photos of the liquid photonic crystals prepared in Examples 1-8 all have obvious iridescent effects.

[0100] The optical photograph of the liquid photonic crystal prepared in Example 4 is shown in Figure 4 The prepared liquid photonic crystals have beautiful structural color effects. It has been verified that the optical photographs of the liquid photonic crystals prepared in Examples 1-8 all have beautiful structural color effects.

[0101] The reflectivity curve of the liquid photonic crystal prepared in Example 5 is shown in FIG. Figure 5 As shown in the figure, the reflection peak is high and narrow, which proves that the brightness and saturation of the structural color are high. It has been verified that the reflection peaks of the liquid photonic crystal color pastes prepared in Examples 1-8 are all high and narrow.

[0102] The self-assembly process of the liquid photonic crystal prepared in Example 6 after external force disturbance is shown in FIG. Figure 6 As shown in the figure, the prepared liquid photonic crystals have good dynamic recovery properties. It has been verified that the liquid photonic crystals prepared in Examples 1-8 all have good dynamic recovery properties.

[0103] The digital photo of the liquid photonic crystal color paste prepared in Example 7 is shown in Figure 7 The prepared liquid photonic crystal color paste has high saturation. It has been verified that the liquid photonic crystal digital photos prepared in Examples 1-8 all have high saturation.

[0104] Figure 8 These are digital photos of the photonic crystal structure chromogenic fabrics prepared in Examples 7 and 8. The prepared photonic crystal structure chromogenic films are bright and uniform in color. It has been verified that the photonic crystal structure chromogenic films prepared in Examples 1-8 are all bright and uniform in color.

[0105] Examples 1-8 all produced liquid photonic crystal color pastes with vibrant structural colors and dynamic recovery. The higher the concentration of the liquid photonic crystals, the more easily the nanospheres are aligned under the balance of van der Waals forces and electrostatic repulsion, resulting in brighter and more vivid structural colors. Therefore, the liquid photonic crystal color paste prepared in Example 4 exhibited the brightest and most vivid structural colors.

[0106] Compared with Example 1, the reaction temperature of Comparative Example 1 is too low, the initiator initiation rate is low, the number of micelles is reduced, the monomer conversion rate is low, and after the polymerization reaction is completed, the reaction is still incomplete, showing oil floating phenomenon and the smell of monomer can be smelled.

[0107] Compared with Example 2, in Comparative Example 2, no pH regulator was added, and the initiator was decomposed by heat to produce H + , which causes the pH of the polymerization system to drop, reducing the emulsifying ability of the emulsifier molecules, leading to phase inversion and a yogurt-like phenomenon. The polymerization reaction cannot proceed normally, and the system has a monomer odor. In Comparative Example 3, excessive addition of pH adjuster increased the ionic strength of the system too much, causing the emulsion to lose stability and cause flocculation.

[0108] Compared with Example 3, in Comparative Example 4, the nanosphere dispersion was not dialyzed, and substances such as oligomers and small molecule salts existed in the system. The electrostatic repulsion potential energy between the nanospheres was insufficient, and liquid photonic crystals could not be formed.

[0109] Compared with Example 4, the amount of monomer added in Comparative Example 5 is small, the number of nanospheres in the system after the polymerization reaction is completed is small, the distance between the microspheres is too large, the random free motion caused by Brownian motion is dominant, and the nanospheres are disordered, so liquid photonic crystals cannot be formed.

[0110] The abnormal phenomena that occurred during the polymerization reaction of Comparative Examples 1-5 and the characteristics of the final systems are summarized in Table 1.

[0111] Table 1

[0112]

[0113]

[0114] The key to the present invention is to effectively solve the problem of H generated by thermal decomposition of the initiator by adding a pH regulator during the emulsion polymerization process. + , which causes the pH of the polymerization system to decrease, the emulsification ability of the emulsifier molecules to decrease, and the system to invert phase. On the basis of solving the above problems, a high-concentration dispersion of photonic crystal primitive nano-microspheres is prepared by a direct synthesis method. The high-concentration dispersion of photonic crystal primitive nano-microspheres is then dialyzed to remove substances such as oligomers and small molecule salts in the system, reduce the ionic strength in the system, and increase the dielectric constant of the medium, thereby increasing the electrostatic repulsion potential energy between the nano-microspheres. The nano-microspheres spontaneously arrange and assemble under the balance of van der Waals force and electrostatic repulsion to form a liquid photonic crystal with a pre-crystallized morphology, thereby producing a liquid photonic crystal color paste with bright and colorful colors.

[0115] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0116] The above is a detailed introduction to the liquid photonic crystal colorant, preparation method, and application in the rapid construction of large-area photonic crystals provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the method and core concept of the present invention. It should be pointed out that, for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a liquid photonic crystal color paste, characterized in that The method comprises the following steps: S1, using emulsion synthesis method to prepare high concentration photonic crystal element nano-microsphere dispersion, The nanosphere dispersion is prepared from monomers, water, and appropriate amounts of emulsifiers, initiators, and pH regulators. The total weight of the monomers and water is 100%, and the monomers account for 35-50 wt% of the total weight of the monomers and water. The pH regulator is used in an amount of 0.2-0.4 wt% of the monomers, the emulsifier is used in an amount of 0.05-0.1 wt% of the monomers, and the initiator is used in an amount of 0.2-0.4 wt% of the monomers. The monomer is selected from one or more of styrene, methyl methacrylate, hydroxyethyl acrylate or butyl acrylate; The high-concentration photonic crystal elementary nano-microsphere dispersion is synthesized by the following method: An emulsifier and a pH adjuster in a formulated amount are mixed with water to obtain an aqueous solution, and the temperature is raised to 75°C to 90°C; the monomers are added to the aqueous solution at once, an inert gas is introduced to protect the reaction monomers, an initiator is added after stirring to initiate a polymerization reaction, and the reaction is carried out at a temperature of 75°C to 90°C until the monomers are completely polymerized. After the reaction is completed, the material is cooled to room temperature and discharged to obtain a high-concentration photonic crystal element nanosphere dispersion; S2, placing the high-concentration photonic crystal elementary nano-microsphere dispersion obtained in S1 into a dialysis bag for dialysis to obtain a liquid photonic crystal with a pre-crystallized form exhibiting structural color; S3, adding an appropriate amount of melanin to the liquid photonic crystal system obtained in S2, mixing uniformly with ultrasound, and allowing to stand to obtain a liquid photonic crystal color paste having a bright and vivid structural color effect and dynamic recovery; The pH regulator is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, and the emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium dodecylsulfonate and sodium dodecyl polyoxyethylene ether sulfate.

2. The method for preparing the liquid photonic crystal paste according to claim 1, wherein: The initiator is one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

3. The method for preparing the liquid photonic crystal paste according to claim 1, wherein: The inert gas is nitrogen or argon, the polymerization reaction time is 2 h to 4 h, the stirring time after adding the monomer is 20 to 40 min, and the stirring speed during the entire polymerization reaction process is 300 to 400 rpm.

4. The method for preparing the liquid photonic crystal paste according to claim 1, wherein: The nanospheres have a diameter of 160 to 340 nm, good sphericity, and a monodispersity index of less than 0.08; The melanin is one or a mixture of carbon black, water-soluble melanin, and the amount of melanin used is 0.1-1.0 wt% of the liquid photonic crystal.

5. The method for preparing liquid photonic crystal color paste according to claim 1, characterized in that: The molecular weight of the dialysis bag is 1000 to 3000.

6. A liquid photonic crystal color paste obtained by the preparation method according to claim 1.

7. Use of the liquid photonic crystal paste according to claim 6 in the rapid construction of large-area photonic crystals.

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