Anhydrous xanthine film with wide band high reflectivity and preparation method and application thereof

Abstract

The present application relates to a kind of wide-band high reflectivity anhydrous xanthine film and its preparation method and application, belong to the field of pearlescent pigment, high reflection crystal material and new functional material, high polymer regulation xanthine-based pearlescent pigment synthesis method.Utilize ammonia volatilization method in aqueous solution to prepare xanthine-based pearlescent pigment, obtain the dispersion of xanthine nanosheet, and then obtain xanthine nanosheet, make xanthine nanosheet into xanthine film material, and then obtain wide-band high reflectivity anhydrous xanthine film.

Description

Technical Field

[0001] This invention relates to a broadband high-reflectivity anhydrous xanthine thin film, its preparation method, and its applications, belonging to the fields of pearlescent pigments, high-reflectivity crystal materials, and novel functional materials, and a method for synthesizing xanthine crystals using polymer regulation. The high reflectivity refers to a reflectivity of the thin film of not less than 90%, and the broadband refers to 400nm-1200nm. Background Technology

[0002] Many organisms contain small organic molecule crystals. Some of these crystals can act as multilayer reflectors or light scatterers to produce structural colors, while others can play a role in vision or other physiological activities. These small organic molecule crystals include guanine (Avital L. Lior, Eyal Shimoni, Osip Schwartz, Efrat G. Regev, Dan Oron, Geoff Oxford, Steve Weiner, Lia Addadi, Adv. Funct. Mater., 2010, 20:320-329.), isoflavone (Benjamin A. Palmera, Anna Hirschb, Vlad Brumfeldc, Eliahu D. Aflalod, Iddo Pinkasc, Amir Sagid, Shaked Rosenne, Dan Orong, Leslie Leiserowitzb, Leeor Kronikb, Steve Weinera, Lia Addadia. PNAS, 2018, 115:2299-2304.), and 7,8-dihydroxanthraquinone (Gan Zhang, Anna Hirsch, Guy Shmul, Liat Avram, Nadav Elad, Vlad...). Brumfeld, IddoPinkas, Yishay Feldman, Raz Ben Asher, Benjamin A. Palmer, Leeor Kronik, Leslie Leiserowitz, Steve Weiner, Lia Addadi. J. Am. Chem. Soc., 2019, 141: 19736-19745.), xanthine (Alexander (Günther Pass, J.Exp.Biol., 2016, 219:3039-3048.) and uric acid (Caveney, S.Proc.R.Soc.Lond., Ser.B:Biol.Sci., 1971, 178:205-225.). Guanine crystals are among the most widely distributed and used organic crystals in living organisms. They possess an extremely high refractive index (1.83), exhibiting strong reflectivity and forming different reflectors in various biological optical systems. It has been reported that the Archaeognatha bio-eye contains rhombic xanthine nanosheet crystals, but no relevant literature reports the crystal structure of the bio-xanthine crystals. However, some literature speculates that these bio-xanthine crystals may have a similar crystal structure to bio-guanine crystals (Ofir Friedman, Alexander Bohm, Katya Rechav, Iddo Pinkas, Vlad Brumfeld, Günther Pass, Steve Weiner, Lia Addadi, J. Struct. Biol., 2022, 214:107834). Xanthine crystals can also be used as optical materials.

[0003] Xanthine crystals possess a bright pearlescent luster, and natural pearl extract has excellent pearly luster, low toxicity, low density, and natural properties, still finding application in some high-end cosmetics (Xu Yangqun, Manufacturing, Processing and Application of Pearlescent Pigments, Beijing: Chemical Industry Press, 2005). Xanthine crystals have a similar luster to natural pearl extract; therefore, artificially synthesized xanthine crystal flakes have high commercial value as a substitute for natural pearl extract. However, there are currently no reports in the literature regarding the artificial synthesis of xanthine crystals. Preparing artificially synthesized xanthine crystals into a broadband high-reflectivity optical film material can improve anti-counterfeiting properties, while the high reflectivity reduces light and heat absorption, thus achieving sun protection and cooling effects. Artificially synthesized xanthine with high reflectivity can be used in sunscreen cosmetics, rubber, coatings, plastics, inks, papermaking, and other fields. It can also be used to coat the surface of materials such as military products, automobiles, and reflective glass of buildings with artificially synthesized xanthine film materials, thereby improving the anti-counterfeiting properties of military products, the sun protection and cooling properties of automobiles, and the cooling properties of reflective glass of buildings, etc., and has extremely high application value.

[0004] Therefore, adding various polymers to the synthesized dispersion can produce rhombic xanthine single-crystal nanosheets with relatively uniform morphology, and the prepared xanthine single-crystal nanosheets all have a bright pearlescent color. Assembling artificially synthesized xanthine single-crystal nanosheets with specific exposed surfaces into broadband high-reflectivity optical film materials can be applied to anti-counterfeiting, sun protection, and cooling applications. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and to propose a high-reflectivity anhydrous xanthine film, its preparation method, and its application.

[0006] The technical solution of this invention is:

[0007] A highly reflective anhydrous xanthine film, wherein the anhydrous xanthine film is a multilayer film, the basic unit of the multilayer film is anhydrous xanthine single crystal nanosheet, and is a xanthine single crystal nanosheet with exposed (200) surface.

[0008] The anhydrous xanthine nanosheets are prepared using anhydrous xanthine as a raw material according to the following method:

[0009] The first step is to prepare an alkaline solution of xanthine: the specific method is to prepare a solution by mixing xanthine powder and ammonia.

[0010] The second step is to prepare the dispersion. The specific method is as follows: use water and polymer additives as raw materials, mix and dissolve the raw materials to obtain the dispersion. The temperature for preparing the dispersion is room temperature to 60°C.

[0011] The third step is to add the alkaline xanthine solution prepared in the first step to the dispersion prepared in the second step and mix them to obtain a mixture.

[0012] The fourth step is to stir the mixture obtained in the third step. The stirring process is a crystallization process, resulting in a dispersion of xanthine single crystal nanosheets.

[0013] The fifth step involves subjecting the xanthine single-crystal nanosheet dispersion obtained in the fourth step to multiple centrifugation and washing processes to obtain anhydrous xanthine single-crystal nanosheets.

[0014] In the first step, ammonia water mainly provides an alkaline environment that can dissolve xanthine. The molar mass ratio of xanthine to ammonia water is 1:(20-30). For example, if 0.02-0.06 mol of xanthine is dissolved in 1L of ammonia water, the concentration of xanthine in the resulting solution is 0.02-0.06M (M represents mol / L).

[0015] In the second step, the polymer additives are polyacrylamide, dimethyl diallyl ammonium chloride / acrylamide copolymer, poly(1-vinylpyrrolidone-co-2-methacrylate dimethylaminoethyl ester), polyvinylpyrrolidone, polyaspartic acid, L-glutamic acid polymer, polyvinyl maleic anhydride, polyvinyl caprolactam, polyquaternium salt, polyacrylic acid, and polystyrene sulfonic acid.

[0016] In the third step, when the alkaline solution and the dispersion are mixed, the volume ratio of water to xanthine ammonia solution is 10:(1-6); the mass ratio of polymer additive to xanthine is (0.1-100):(0.01-10). For example, 10-15 mL of water, 0.1-100 mg of polymer, temperature RT-60℃, and 1-5 mL of xanthine ammonia solution.

[0017] In the fourth step, the reaction temperature is RT to 60℃, and the reaction time is 5 to 24 hours.

[0018] A method for preparing a high-reflectivity anhydrous xanthine film, comprising: mixing anhydrous xanthine single-crystal nanosheets with water to obtain a suspension; allowing the suspension to stand, during which water evaporates, thereby obtaining a high-reflectivity anhydrous xanthine film.

[0019] An application of anhydrous xanthine single-crystal nanosheets: The obtained anhydrous xanthine single-crystal nanosheets are used as pearlescent pigments in skin care products, sunscreen cosmetics, paper, coatings, rubber, paints and other fields.

[0020] An application of a high-reflectivity anhydrous xanthine film involves applying the high-reflectivity anhydrous xanthine film to military products, automobiles, glass surfaces, etc. In application, the high-reflectivity anhydrous xanthine film is coated on the surface of aircraft and military clothing, automobiles, and reflective glass surfaces of buildings to achieve effects such as anti-counterfeiting, sun protection, and cooling.

[0021] Compared with existing technologies, the present invention has the following main advantages:

[0022] (1) In this invention, the xanthine single crystal nanosheets with specific exposed surfaces are artificially synthesized and are pure xanthine crystals. Therefore, they have better stability and solubility and can be dispersed in water for several months without significant changes.

[0023] (2) In this invention, a variety of polymers are used as morphology modifiers to artificially synthesize xanthine single crystal nanosheets with specific exposed surfaces. These nanosheets are all rhombic and preferentially expose the (100) crystal plane with the best refractive index. The presence of polymers makes the morphology of the crystal consistent with the morphology of xanthine crystals in the body, thus obtaining anhydrous xanthine single crystal nanosheets.

[0024] (3) In this invention, the length of the synthesized xanthine single crystal nanosheets with specific exposed surfaces is 2-4 μm, and they show a bright structural color under an optical microscope and a bright pearlescent color in the dispersion.

[0025] (4) In this invention, the membrane material made from the anhydrous xanthine single crystal nanosheets with specific exposed surfaces synthesized in this invention is bright white and has a high reflectivity, which is higher than that of industrial xanthine.

[0026] (5) In this invention, an anhydrous xanthine film synthesized artificially is applied to the surfaces of military products, automobiles, building glass, etc., to further improve the reflectivity of these objects and achieve high reflectivity, thereby achieving anti-counterfeiting, sun protection, cooling and other effects.

[0027] (6) The present invention relates to a high-reflectivity anhydrous xanthine film, its preparation method, and its application. The method includes: preparing a xanthine ammonia solution using xanthine powder and ammonia water; preparing a dispersion of water and various polymers; adding the xanthine ammonia solution to the dispersion; mixing and stirring for a certain time to obtain a dispersion of xanthine single-crystal nanosheets; thereby obtaining xanthine single-crystal nanosheets; and fabricating xanthine single-crystal nanosheets into a xanthine film material to obtain a high-reflectivity anhydrous xanthine film. The anhydrous xanthine single-crystal nanosheets with specific exposed surfaces synthesized in this invention are pure xanthine crystals, exhibiting better stability and solubility. Various polymers can be used as morphology modifiers to synthesize rhombic xanthine with specific exposed surfaces. The synthesized xanthine single-crystal nanosheets with specific exposed surfaces have a length of 2-4 μm, displaying a bright structural color under an optical microscope and a bright pearlescent color in the dispersion. The film material made from the xanthine single-crystal nanosheets with specific exposed surfaces is bright white and has high reflectivity, exceeding that of industrial xanthine. Applying the xanthine film to the surface of military products further enhances the reflectivity of the surface, achieving high reflectivity and thus anti-counterfeiting effects. Attached Figure Description

[0028] Figure 1 Optical photograph of polymer-regulated anhydrous xanthine single-crystal nanosheets.

[0029] Figure 2 SEM image of polymer-regulated anhydrous xanthine single-crystal nanosheets.

[0030] Figure 3 The image shows the XRD pattern of polymer-regulated anhydrous xanthine single-crystal nanosheets.

[0031] Figure 4 This is a diffuse reflectance diagram of anhydrous xanthine films. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Example

[0034] A highly reflective anhydrous xanthine film, wherein the anhydrous xanthine film is a multilayer film, the basic unit of the multilayer film is anhydrous xanthine single crystal nanosheet, and is a xanthine single crystal nanosheet with exposed (200) surface.

[0035] The anhydrous xanthine nanosheets are prepared using anhydrous xanthine as a raw material according to the following method:

[0036] The first step is to prepare an alkaline solution of xanthine: The specific method is to prepare a 1L xanthine ammonia solution by mixing 9g of xanthine powder with 1L of ammonia water.

[0037] The second step is to prepare the dispersion. The specific method is as follows: use 10mL of water and 10mg of polymer additive as raw materials, mix and dissolve the raw materials to obtain the dispersion, and prepare the dispersion at a temperature of 40℃.

[0038] The third step is to add the alkaline xanthine solution prepared in the first step to the dispersion prepared in the second step and mix them to obtain a mixture.

[0039] The fourth step is to stir the mixture obtained in the third step for 5-24 hours. The stirring process is a crystallization process, and a dispersion of xanthine single crystal nanosheets is obtained.

[0040] The fifth step involves subjecting the xanthine single-crystal nanosheet dispersion obtained in the fourth step to multiple centrifugation and washing processes to obtain anhydrous xanthine single-crystal nanosheets.

[0041] A method for preparing a high-reflectivity anhydrous xanthine film, comprising: mixing 1g of anhydrous xanthine single-crystal nanosheets with 1mL of water to obtain a suspension; allowing the suspension to stand, during which water evaporates; and allowing it to stand for 5h to obtain a high-reflectivity anhydrous xanthine film.

[0042] Figure 1 This is an optical photograph of the anhydrous xanthine crystal nanosheets in this embodiment, showing strong structural color. Figure 2 This is a SEM image of anhydrous xanthine crystal nanosheets in this embodiment; Figure 3 The XRD pattern of the anhydrous xanthine crystal nanosheets in this embodiment shows a strong preferred orientation. Figure 4 This is a diffuse reflectance diagram of the anhydrous xanthine film in this embodiment. Figure 4 It is known that the diffuse reflectance of anhydrous xanthine films is as high as 90-100% in the wavelength range of 400-1200nm.

[0043] This embodiment successfully prepared anhydrous xanthine crystal nanosheets, thereby obtaining anhydrous xanthine thin films with high reflectivity over a wide wavelength range, which have extremely high application value.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention. The scope of protection of the present invention should be determined by the claims.

Claims

1. A high-reflectivity anhydrous xanthine film, characterized in that: The anhydrous xanthine film is a multilayer film, and the basic unit of the multilayer film is anhydrous xanthine single crystal nanosheets with exposed (200) surfaces; The anhydrous xanthine single-crystal nanosheets are prepared using anhydrous xanthine as a raw material according to the following method: The first step is to prepare an ammonia solution of xanthine; The second step is to prepare an aqueous solution of the polymer; The third step is to add the xanthine ammonia solution prepared in the first step to the polymer aqueous solution prepared in the second step, and mix and stir. The fourth step is to stir the mixture obtained in the third step to obtain a dispersion of xanthine single crystal nanosheets. The fifth step involves centrifuging and washing the dispersion of xanthine single-crystal nanosheets obtained in the fourth step to obtain xanthine single-crystal nanosheets. In the second step, the polymer is at least one of the following: polyacrylamide, dimethyl diallyl ammonium chloride / acrylamide copolymer, poly(1-vinylpyrrolidone-co-2-methacrylate dimethylaminoethyl ester), polyvinylpyrrolidone, polyaspartic acid, L-glutamic acid polymer, polyvinyl maleic anhydride, polyvinyl caprolactam, polyquaternium salt, polyacrylic acid, and polystyrene sulfonic acid.

2. The high-reflectivity anhydrous xanthine film according to claim 1, characterized in that: In the first step, the method for preparing the ammonia solution of xanthine is as follows: prepare a solution by mixing xanthine powder and ammonia.

3. The high-reflectivity anhydrous xanthine film according to claim 2, characterized in that: The concentration of xanthine in ammonia water is 0.02-0.06 mol / L.

4. The high-reflectivity anhydrous xanthine film according to claim 1, characterized in that: In the third step, the dispersion is prepared at RT~60℃, where RT represents room temperature. The proportions of the substances in the dispersion are as follows: the volume ratio of water to xanthine ammonia solution is 10:(1~6); the mass ratio of polymer additive to xanthine is (0.1~100):(0.01~10).

5. The high-reflectivity anhydrous xanthine film according to claim 1, characterized in that: In the fourth step, the reaction temperature is RT~60℃ and the reaction time is 5-24h.

6. A method for preparing a high-reflectivity anhydrous xanthine film according to claim 1, characterized in that... The steps of this method are as follows: Anhydrous xanthine single-crystal nanosheets were mixed with water to obtain a suspension. The suspension was then allowed to stand to obtain a highly reflective anhydrous xanthine film.

7. An application of the anhydrous xanthine single-crystal nanosheets of claim 1, characterized in that: The obtained xanthine single-crystal nanosheets are used as pearlescent pigments in skin care products, sunscreen cosmetics, paper, coatings, rubber, and paints.

8. The application of the high-reflectivity anhydrous xanthine film according to claim 1, characterized in that: High-reflectivity anhydrous xanthine films are applied to the surfaces of aircraft, tanks, automobiles, and reflective glass. In this application, the high-reflectivity anhydrous xanthine film is coated onto the surfaces of aircraft, tanks, automobiles, and reflective glass.

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