Application of photonic crystal microspheres in cosmetics

Abstract

This invention discloses a method for preparing photonic crystal microspheres in cosmetics and their application. This invention innovatively proposes the application of photonic crystal microspheres in cosmetics, resulting in cosmetics with excellent pearlescent color rendering and intensity. Specifically, it includes the following steps: First, styrene-maleic anhydride (PSMA) photonic crystals are prepared using emulsion polymerization, and their structural color characteristics can be altered by controlling their size. Second, noble metal nanoparticles Au and Ag are uniformly coated onto the surface of PSMA monodisperse polymerized microspheres using an in-situ reduction method to obtain PSMA@Au and PSMA@Ag microspheres. Finally, PSMA@Au and PSMA@Ag microspheres are polymerized into micron-sized microspheres using microfluidic technology, allowing for precise control of the particle size of the large microspheres, thereby obtaining photonic crystal liquid pigments of different colors. Furthermore, the pigments of this invention differ from conventional pigments, exhibiting excellent weather resistance and biocompatibility, highly effective broad-spectrum antibacterial properties, and UV resistance. Therefore, this raw material can be innovatively applied as a functional ingredient in cosmetics.

Description

Technical Field

[0001] This invention relates to the field of photonic crystals, and more specifically to the application of photonic crystal microspheres in cosmetics. Background Technology

[0002] A photonic crystal is an artificial periodic dielectric structure with photonic bandgap characteristics, sometimes also called a PBG photonic crystal structure. The photonic bandgap refers to the area within which waves of a certain frequency range cannot propagate; that is, the structure itself possesses a "bandgap." Simply put, a photonic crystal has wavelength selectivity, allowing light of a specific wavelength to pass through while blocking other wavelengths.

[0003] Patent application number 201510696732.3 discloses a sheet-like photonic crystal pigment, its preparation method, and its applications. This sheet-like photonic crystal pigment not only enriches the colors of existing pearlescent pigments but also changes the hue by adjusting the microsphere particle size, achieving separation of pigment hue and gloss. It can also impart richer colors to ink products while avoiding highly polluting effect pigments. Simultaneously, it can effectively achieve the iridescent color effect of structural colors and antibacterial and UV-resistant effects. Furthermore, the presence of a surface protective layer allows it to be directly added to inks. However, no research has yet disclosed the application of photonic crystal microspheres in cosmetics. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of existing technologies and provide a photonic crystal microsphere for the application of cosmetics. This photonic crystal microsphere is prepared using emulsion polymerization, in-situ reduction, and microfluidic methods to obtain a nanoscale photonic crystal microsphere liquid pigment with bright colors, good weather resistance, high skin affinity, and nanoscale dimensions.

[0005] This invention discloses the application of photonic crystal microspheres in cosmetics. The diameter of the photonic crystal microspheres is less than or equal to 1 μm. The photonic crystal microspheres are formed by densely packed monodisperse polymer particles with gaps between them, and have a regular and ordered structure. The particle size of the monodisperse polymer particles is 105 nm to 305 nm. The monodisperse polymer particles have a core-shell structure, wherein the core is selected from styrene-maleic anhydride (PSMA), and the shell is Au or Ag.

[0006] Furthermore, in the above technical solution, the particle size of styrene-maleic anhydride is 100nm to 300nm, preferably 180nm to 270nm.

[0007] Furthermore, in the above technical solution, the makeup includes liquid eyeliner, liquid eyebrow pencil, lip gloss, and liquid eyeshadow.

[0008] Furthermore, in the above technical solution, the preparation method of the photonic crystal liquid pigment includes the following steps:

[0009] (1) Pre-treat the raw material styrene to purify the raw material and remove the blocking agent;

[0010] (2) Styrene-maleic anhydride copolymer monodisperse nanospheres (PSMA) with different particle sizes were synthesized by suspension polymerization.

[0011] (3) Select PSMA with uniform copolymerization and obvious structural color, and use in-situ reduction method to grow Au or Ag on its surface to synthesize PSMA@Au core-shell structured copolymer microspheres or PSMA@Ag core-shell structured copolymer microspheres.

[0012] (4) Using microfluidics to obtain photonic crystal liquid pigments.

[0013] Furthermore, in the above technical solution, the method for purifying the raw materials in step (1) is as follows: place a 10% wt to 15% wt NaOH solution, mix styrene with a 10% wt to 20% wt NaOH solution in a 1:1 ratio in a separatory funnel, shake and wash thoroughly to ensure that the blocking agent in the styrene is washed away, let stand and separate the liquid to remove the lower layer of waste liquid and retain the upper layer of styrene.

[0014] Furthermore, in the above technical solution, the monodispersity PDI of the styrene-maleic anhydride copolymer monodisperse nanospheres in step (2) is less than 0.1.

[0015] Furthermore, in the above technical solution, the styrene-maleic anhydride copolymer monodisperse nanospheres in step (2) are colored microspheres.

[0016] Furthermore, in the above technical solution, the in-situ growth of gold or silver nanoparticles in step (3) is 5 nm to 10 nm.

[0017] Furthermore, in the above technical solution, the optimal reaction conditions for the PSMA@Au in-situ reduction synthesis in step (3) are: pH 8 to 9, HAuCl4 24 mmol / L to 25.4 mmol / L, and Na4EDTA 14 g / L to 15 g / L;

[0018] The optimal reaction conditions for the PSMA@Ag in-situ reduction synthesis in step (3) are: 75℃ to 80℃, 7g / L to 7.5g / L AgNO3 aqueous solution, and 4.5g / L to 5.0g / L Na4EDTA aqueous solution.

[0019] Furthermore, in the above technical solution, the monodisperse nanoparticle microspheres (PSMA) mentioned in step (2) have a particle size of 100nm--300nm.

[0020] Furthermore, in the above technical solution, the particle size of the PSMA@Au and PSMA@Ag core-shell structure copolymer microspheres synthesized by in-situ reduction method in step (3) is 105nm to 305nm; preferably 185nm to 280nm.

[0021] Furthermore, in the above technical solution, in step (d), large-diameter photonic crystal microspheres are synthesized using a microfluidic method to obtain photonic crystal microsphere liquid pigments of different colors and bright colors.

[0022] Furthermore, in the above technical solution, in step (4), the utilization rate of raw materials is improved by microfluidic technology. Microfluidic elements can precisely control the flow rate and distribution of liquid through tiny channels and micro valves and other micro structures.

[0023] Furthermore, in the above technical solution, in step (4), the microfluidic technology can adjust the surface properties of the microspheres, such as surface charge and hydrophilicity, by adding different surface modifiers, such as sodium dodecyl sulfate, or by controlling the flow rate, thereby preventing the microspheres from agglomerating and increasing their utilization rate.

[0024] The beneficial effects of this invention are as follows: This invention innovatively proposes the application of photonic crystal microspheres in cosmetics, resulting in cosmetics with excellent pearlescent color rendering and intensity. The cosmetics produced by this invention have excellent UV protection (up to 99.50%), multifunctional antibacterial properties (99.90% anti-Escherichia coli rate, 95.90% anti-Gram bacteria rate, and 98.50% anti-Staphylococcus aureus rate), and zero sensitization (the raw material particle size is larger than the pore particle size and will not easily enter the pores). Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0026] Figure 1 This is a schematic diagram of the in-situ reduction preparation of PSMA@Au;

[0027] Figure 2 A schematic diagram of the in-situ reduction preparation of PSMA@Ag;

[0028] Figure 3 PSMA electron microscopy characterization and particle size frequency distribution; where (a) and (d) represent 207 nm particle size, (b) and (e) represent 219.50 nm particle size, and (c) and (f) represent 231.16 nm particle size.

[0029] Figure 4 This is an assembly diagram of PSMA;

[0030] Figure 5 For microfluidic preparation of large-diameter photonic crystal microspheres;

[0031] Figure 6 (a) XRD image of PSMA@Ag, consistent with the standard XRD peak of elemental silver (JCPDS card 04-0783), indicating Ag0 coating; (b) XRD of PSMA@Au, with standard gold characteristic XRD signal (Au PDF#04-0784), indicating Au0 coating.

[0032] Figure 7 (a) is a SEM image of PSMA@Au, with assembly conditions of HAuCl4 concentration of 25.4 mmol / L, AgNO3 concentration of 7.5 g / L, and pH value of 9; (b) is a SEM image of PSMA@Ag, with assembly conditions of Na4EDTA concentration of 5.0 g / L, AgNO3 concentration of 7.5 g / L, and temperature of 80℃.

[0033] Figure 8 (a) Reflection spectrum of PSMA@Ag; (b) Reflection light of PSMA@Au;

[0034] Figure 9 (a) is a digital photograph of PSMA@Ag, and (b) is a digital photograph of PSMA@Au. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0036] (1) Preparation and assembly performance study of monodisperse PSMA@Au and PSMA@Ag microspheres

[0037] PSMA (polystyrene-co-maleic anhydride) colloidal microspheres were prepared using a traditional emulsion polymerization method. The effects of synthesis temperature and emulsifier dosage on the monodispersity, particle size, and surface charge density of the microspheres were investigated, and a scale-up synthesis experiment was conducted. After the core layer PSMA microspheres were aminated with polyethyleneimine (PEI), organic-inorganic core-shell microspheres (PSMA@Au) with high surface charge density were prepared by in-situ reduction method. The effects of Au or Ag source concentration, reducing agent dosage, reaction system pH, and reaction temperature on the size, coating density, and surface charge density of the shell Au nanoparticles and core-shell microspheres were investigated. The regulation of the particle size of core-shell PSMA@Au and PSMA@Ag microspheres by changes in PSMA microsphere size was explored.

[0038] Large-diameter photonic crystal microspheres were prepared using monodisperse PSMA@Au and PSMA@Ag colloidal microspheres as building blocks via microfluidic methods to obtain photonic crystal microspheres with nanoscale particle size and vibrant colors. The effects of microsphere content, curing temperature, and the gas-liquid-solid three-phase contact line during curing on the long-range ordered structure of the photonic crystal were investigated.

[0039] Example 1

[0040] (I) A method for preparing monodisperse PSMA microspheres of 210 nm to 250 nm, comprising the following steps:

[0041] ① Take a certain amount of SDS (i.e., the amount of sodium dodecyl sulfate added affects the particle size of the synthesized monodisperse PSMA microspheres: 0.045g, 0.054g, and 0.066g of added SDS, and obtain monodisperse PSMA microspheres with sizes of 231.16nm, 219.50nm, and 207.85nm respectively) and put it into a 100mL three-necked flask. Add 45mL of deionized water, stir mechanically at a constant speed of 300r / min, and heat to 80℃ under N2 protection.

[0042] ② Add 5.0g of styrene, maintain the temperature at 80℃, and react for 10min.

[0043] ③ Add 0.05g of potassium persulfate (preparing it as a solution will enhance the effect) to initiate the polymerization reaction, and react for 1 hour.

[0044] ④ Add 0.8g MA (preparing it as a solution will enhance the effect) and continue the reaction for 5 hours.

[0045] ⑤ The obtained product was washed twice with deionized water and then dispersed in deionized water.

[0046] PSMA electron microscopy characterization and particle size frequency distribution are as follows: Figure 3 As shown, the assembly diagram of PSMA is as follows. Figure 4 As shown.

[0047] Example 2

[0048] (II) Preparation methods of PSMA@Ag core-shell structured microspheres, such as... Figure 1 As shown, it includes the following steps:

[0049] Taking the fabrication of 220nm PSMA@Ag core-shell structured microspheres as an example:

[0050] ① Prepare an emulsion of 1.5 mL containing 10% by mass of PSMA microspheres with a particle size of 207.85 nm. The 207.85 nm PSMA microspheres were prepared in Example 1 and diluted to 10 mL with deionized water.

[0051] ② Add 5 mL of 0.1 g / mL PEI solution and stir at room temperature for 3 hours (stirring speed: 450-550 r / min, until a vortex appears on the liquid surface).

[0052] ③ Centrifuge (6000r, 10min), wash twice with deionized water (to remove free PEI in the solution), and disperse in 10mL of deionized water.

[0053] ④ Add 5 mL of AgNO3 solution of a certain concentration (optimal concentration: 7.5 g / L) and stir at room temperature for 3 hours.

[0054] ⑤ Heat to 80℃ and react for 3 hours (long silver nucleus).

[0055] ⑥ Add 5 mL of Na4EDTA solution of a certain concentration and continue the reaction for 1 h (nuclear growth).

[0056] ⑦ The obtained product was washed twice with deionized water.

[0057] The preparation conditions for PSMA@Ag core-shell structured microspheres of other particle sizes are similar.

[0058] XRD images of PSMA@Ag are as follows Figure 6 As shown in (a), the peaks are consistent with the standard XRD peaks of elemental silver (JCPDS card 04-0783), indicating that Ag0 is coated. Figure 8 (a) Reflection spectrum of PSMA@Ag (b) Reflection light of PSMA@Au. Figure 9 (a) is a digital photograph of PSMA@Ag.

[0059] Example 3

[0060] (III) Preparation method of PSMA@Au core-shell structured microspheres with a particle size of 220 nm, such as Figure 2 As shown, it includes the following steps:

[0061] ① Take 10 mL of 1.5% PSMA solution with a mass fraction of 207.85 nm. The 207.85 nm PSMA microspheres were prepared in Example 1. Add 5 mL of 0.2 g / mL polyethyleneimine (PEI) solution and stir at room temperature for 3 h.

[0062] ② Wash the stirred solution twice with deionized water and disperse it in 10 mL of water;

[0063] ③ Add 2.272 mL of HAuCl4 solution with a concentration of 25.4 mmol / L, adjust the pH value to 9 with NaOH solution, and stir at room temperature for 3 h;

[0064] ④ Heat to 100℃ and react for 2 hours;

[0065] ⑤ Dissolve 0.0752 g of Na4EDTA in 20 mL of deionized water and add it dropwise in three portions (3 mL for the first time and the remaining portion in two separate drops) with a 10 min interval between each addition. Continue the reaction for 1.5 h. Finally, wash the reaction product twice with deionized water.

[0066] XRD image of PSMA@Au as follows Figure 6 As shown in (b), the standard gold characteristic XRD signal (Au PDF#04-0784) indicates that Au0 is coated. Figure 8 (b) is the reflection spectrum of PSMA@Au. Figure 9 (b) is a digital photograph of PSMA@Au.

[0067] Example 4

[0068] (iv) Microfluidic preparation of large-diameter photonic crystal microspheres, such as Figure 5 As shown, it includes the following steps

[0069] ① Precursors for preparing photonic crystal microspheres: The 10% (by mass) aqueous solution of PSMA@Au monodisperse nanoparticles with a particle size of 220 nm prepared in Examples 2 and 3 and the 10% (by mass) aqueous solution of PSMA@Ag monodisperse nanoparticles with a particle size of 220 nm prepared in Examples 3 served as precursors for photonic crystal microspheres.

[0070] ② Fabrication of microfluidic chips: Chips are fabricated using microfluidic technology. Each chip contains a microchannel and a micropore. The diameter of the micropore should be comparable to the diameter of the template microsphere.

[0071] ③ Microfluidic control for photonic crystal microspheres: The precursor of photonic crystal microspheres is injected into a microchannel, and the flow of fluid is controlled by a microcontroller to form photonic crystal microspheres at the micropores.

[0072] A monodisperse of silica nanoparticles (20 wt%) and silicone oil (50 cSt) were used as the internal (dispersed phase) and external (continuous phase) fluids, respectively. These were injected into a microfluidic device using a syringe pump to generate water-in-oil microdroplets. The flow rates of the internal and external phases were 0.5 mL / h and 5 mL / h, respectively. The resulting microdroplets were collected in silicone oil (500 cSt) and incubated at 75°C overnight to allow water evaporation.

[0073] ④ Particle size control: The particle size of PSMA@Au and PSMA@Ag photonic crystal microspheres can be controlled by adjusting parameters such as flow rate and channel size in microfluidic control. (Photonic crystal microspheres ranging from 500 nm to 1 μm can be obtained when the internal and external phase flow rates are 0.5 mL / h and 5 mL / h, respectively.)

[0074] ⑤ Collection of photonic crystal microspheres: The silica gel crystal microspheres were removed and repeatedly washed with n-hexane until all remaining silicone oil was completely removed. Subsequently, the colloidal crystal microspheres were calcined at 800℃ for 4 hours to enhance the adhesion between nanoparticles and improve the mechanical strength of the colloidal crystal microspheres.

[0075] The resulting PSMA@Au and PSMA@Ag photonic crystal microspheres exhibit large particle size and a periodic porous structure. Furthermore, microfluidic technology enables high-throughput, high-precision, and reproducible fabrication.

[0076] The photonic crystal microspheres obtained above have a bright metallic luster. Furthermore, with changes in materials and binders, the resulting microspheres will exhibit different colors and can be applied to the preparation of cosmetics.

[0077] Comparative Example 1

[0078] Polystyrene microspheres (PS) were prepared by emulsion polymerization.

[0079] By adjusting the amount of emulsifier, the particle size of polystyrene microspheres can be controlled. Since larger pores in inverted opal facilitate liquid penetration, microspheres with a particle size range of 300nm-600nm can be prepared. The specific method is as follows: Preparation of polystyrene microsphere emulsions with a particle size below 300nm.

[0080] The PS microspheres were prepared using a traditional emulsion polymerization method, with the particle size controlled by varying the amount of emulsifier. First, a certain mass of sodium dodecyl sulfate (SDS) was dissolved in 135 mL of deionized water. The solution was stirred and heated at 300 rpm until it reached 50°C. Then, 15.0 g of styrene monomer was added. The temperature was then further increased to 85°C, and the solution was stirred for 30 min. Finally, 0.15 g of potassium persulfate (KPS) initiator was added, and the reaction was allowed to proceed for 5 h to obtain an impure PS microsphere emulsion. This PS microsphere emulsion was then centrifuged at 9000 rpm for 45 min, and the supernatant was discarded. Deionized water was then added, and the mixture was sonicated while simultaneously breaking up the solids until they were completely dissolved. This process was repeated for another 45 min at 9000 rpm, and the supernatant was discarded to obtain a pure PS microsphere emulsion.

[0081] Compared to PSMA@Ag microspheres and PSMA@Au microspheres, polystyrene microspheres (PS) do not have antibacterial, UV-resistant, or zero-allergenic properties, and their particle size control is complicated.

[0082] Comparative Example 2

[0083] Preparation of SiO2 microspheres

[0084] To meet the above requirements, inorganic SiO2 microspheres were synthesized using the Stober method. Tetraethoxysilane underwent slow hydrolysis in a mixed solution of water and ethanol, catalyzed by ammonia, gradually nucleating and growing the microspheres. This ensured excellent monodispersity, abundant surface charge, and excellent particle size controllability. Under weakly alkaline conditions, the deprotonation of hydroxyl groups on the SiO2 microsphere surface resulted in abundant negative charges. Considering that the small particle size of colloidal microspheres makes it easier for them to form a non-close-packed array in the polymer system through electrostatic repulsion, calculations showed that SiO2 microspheres with a particle size of 120nm-160nm needed to be prepared. The particle size of the SiO2 microspheres was controlled by adjusting the amount of tetraethoxysilane and the concentration of ammonia.

[0085] Compared to PSMA@Ag and PSMA@Au microspheres, SiO2 microspheres (PS) lack the unique metallic luster and reflective effect, and therefore cannot make makeup more radiant. They also lack antibacterial, UV-protective, and hypoallergenic properties.

[0086] Monodisperse PSMA@Au core-shell microspheres were prepared by uniformly distributing Au nanoparticles on the surface of colloidal microspheres, ensuring uniform and stable dispersion of Au nanoparticles within the photonic crystal structure. Simultaneously, Au's absorption of visible light eliminates incoherent scattering from the photonic crystal, enabling the achievement of highly saturated structural colors without the addition of any light-absorbing substances. Compared to cosmetics on the market that add various substances to achieve high-saturation colors, our structural color cosmetics are greener, safer, and more environmentally friendly. Furthermore, monodisperse PSMA@Au colloidal microspheres with high surface charge were designed and synthesized, giving them both self-assembly properties and the excellent antibacterial properties of noble metals. The preparation methods for SiO2, PSMA@Ag, and PSMA@Au photonic crystal microspheres are simple and inexpensive, and they are easily modified and functionalized. Future industrial production could reduce production costs while achieving green development goals. This approach changes the traditional use of metal oxide pigments or macromolecular dyes with conjugated structures in cosmetics. Utilizing the characteristics of structural colors such as high brightness, high saturation, non-fading, iridescence, and polarization effects, various photonic crystal microspheres (micrometer-scale) were prepared using microfluidic technology. These micrometer-scale photonic crystal microspheres were then used as colorants to formulate inks, and various structural color cosmetics were prepared based on this.

[0087] The cosmetic product of Example 2 prepared by the present invention has good UV protection (up to 99.50%) as detected by spectroscopic method, and has multifunctional antibacterial properties as detected by cytotoxicity test method (anti-Escherichia coli rate up to 99.90%, anti-Gram bacteria rate up to 95.90%, and anti-Staphylococcus aureus rate up to 98.50%).

[0088] The cosmetic product of Example 3 prepared by the present invention has good UV protection (up to 99.60%) as detected by spectroscopic method, and has multifunctional antibacterial properties as detected by cytotoxicity test method (anti-Escherichia coli rate up to 99.80%, anti-Gram bacteria rate up to 95.80%, and anti-Staphylococcus aureus rate up to 97.50%).

[0089] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. The application of photonic crystal microspheres in color cosmetics, characterized by: The diameter of the photonic crystal microspheres is less than or equal to 1 μm; the photonic crystal microspheres are a regular and ordered structure formed by densely packed monodisperse polymer particles with gaps between them; the particle size of the monodisperse polymer particles is 105 nm to 305 nm; the monodisperse polymer particles have a core-shell structure, wherein the core is selected from styrene-maleic anhydride (PSMA) and the shell is Au or Ag. Preparation method of photonic crystal liquid pigment, Includes the following steps: (1) Pre-treat the raw material styrene to purify the raw material and remove the blocking agent; (2) Styrene-maleic anhydride copolymer monodisperse nanospheres (PSMA) with different particle sizes were synthesized by suspension polymerization. (3) Select PSMA with uniform copolymerization and obvious structural color, and use in-situ reduction method to grow Au or Ag on its surface to synthesize PSMA@Au core-shell structured copolymer microspheres or PSMA@Ag core-shell structured copolymer microspheres. (4) Obtaining photonic crystal liquid pigments using microfluidics; The monodispersity index (PDI) of the styrene-maleic anhydride copolymer monodisperse nanospheres described in step (2) is less than 0.1; The optimal reaction conditions for the PSMA@Au in-situ reduction synthesis in step (3) are: pH 8 to 9, HAuCl4 24 mmol / L to 25.4 mmol / L, and Na4EDTA 14 g / L to 15 g / L; The optimal reaction conditions for the PSMA@Ag in-situ reduction synthesis in step (3) are: 75℃ to 80℃, 7g / L to 7.5g / L AgNO3 aqueous solution, and 4.5g / L to 5.0g / L Na4EDTA aqueous solution.

2. The application according to claim 1, characterized in that: The particle size of styrene-maleic anhydride ranges from 100 nm to 300 nm.

3. The application according to claim 1, characterized in that: The makeup products include liquid eyeliner, liquid eyebrow pencil, lip gloss, and liquid eyeshadow.

4. The application according to claim 1, characterized in that, The method for purifying the raw materials in step (1) is as follows: prepare a 10% wt to 15% wt NaOH solution, mix styrene with the 10% wt to 20% wt NaOH solution in a 1:1 ratio in a separatory funnel, shake and wash thoroughly to ensure that the blocking agent in the styrene is washed away, let stand and separate the liquid to remove the lower layer of waste liquid and retain the upper layer of styrene.

5. The application according to claim 1, characterized in that, The styrene-maleic anhydride copolymer monodisperse nanospheres mentioned in step (2) are colored nanospheres.

6. The application according to claim 1, characterized in that, In step (3), the in-situ growth of gold or silver nanoparticles ranges from 5 nm to 10 nm.

7. The application according to claim 1, characterized in that, Add a surface modifier in step (4).

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