Self-adaptive photochromic coating as well as preparation method and application thereof

Abstract

The invention belongs to the field of photochromic coatings, and particularly relates to a self-adaptive photochromic coating and a preparation method and application thereof.The self-adaptive photochromic coating is prepared from, by weight, 0.5-1.5 parts of polycaprolactone, 4-6 parts of dichloromethane, 2-6 parts of tetrahydrofuran and 0.1-0.3 part of a composition A. The composition A is formed by compounding DASAs-1, DASAs-2 and organic dye; the self-adaptive photochromic coating prepared by taking the donor-acceptor Stetenporus adduct as a non-fixed hue and the organic dye as a fixed hue is different from a traditional photochromic material which needs to drive the material to perform color conversion in an ultraviolet light wave band. The prepared photochromic material can automatically adjust the color according to the change of ambient light under the driving of visible light, and self-adaptive camouflage is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of photochromic coatings, and particularly relates to a self-adaptive photochromic coating and a preparation method and application thereof. BACKGROUND

[0002] In the field of security and protection, camouflage technology is often used as a key means to hide targets and improve their survivability. The complex and changeable factors such as terrain, season, weather and time further increase the demand for dynamic environmental adaptability of camouflage technology. Although traditional visible light camouflage technology is suitable for specific types of background environment and can solve the problem of target camouflage to a certain extent, it is difficult to meet the demand for visible light camouflage of targets in cross-regional, multi-seasonal and full-time periods. Self-adaptive visible light camouflage technology is a new type of visible light camouflage technology that can actively change its detectable features to maintain good camouflage effect according to the changes in the background. This technology can effectively improve the survivability of targets in the battlefield.

[0003] The purpose of the self-adaptive visible light camouflage technology is to reduce the difference in brightness and chroma between the target and the background, thereby achieving the effect of self-adaptive camouflage. Photochromic coating changes its molecular structure under the action of light, resulting in a change in the absorption peak of light, i.e. color, and this change is generally reversible. Therefore, photochromic camouflage materials have the advantage of convenient triggering and have good development prospects in the field of self-adaptive visible light camouflage.

[0004] There are many types of photochromic coatings at present, which can be mainly divided into inorganic compounds and organic compounds. Compared with inorganic compounds, organic photochromic coatings have good performance and a wide range of applications. Organic compounds mainly include spiropyrans, spirooxazines, diarylethene, fulgides, azo compounds, etc. However, the light excitation wavelength band of these compounds is mainly concentrated in the ultraviolet light band, which cannot achieve self-adaptive adjustment according to changes in the environment light source.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a self-adaptive photochromic coating and a preparation method and application thereof, so as to solve the problem that the existing photochromic coating cannot achieve self-adaptive adjustment according to changes in the environment light source.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: The present application provides a self-adaptive photochromic coating, which comprises the following components by weight: polycaprolactone 0.5-1.5 parts, dichloromethane 4-6 parts, tetrahydrofuran 2-6 parts, and composition A 0.1-0.3 parts, wherein the composition A is compounded by DASAs (donor-acceptor Stenhouse compound)-1, DASAs-2 and an organic dye.

[0008] Further, the composition A is compounded by DASAs-1, DASAs-2 and organic dyes according to the mass ratio of (1.5~2.5):(1.5~2.5):(0.5~1.5).

[0009] Further, the organic dyes include one of pigment yellow 180, pigment orange 73 and pigment brown 25.

[0010] Further, the preparation method of the DASAs-1 comprises the following steps: S101, dissolving the electron acceptor-1 in deionized water to obtain a concentration of 0.13~0.3mol / L electron acceptor solution-1; S102, slowly adding furfural to the electron acceptor solution-1, and stirring at 60~80℃ for 2~6h to obtain a first suspension, filtering the first suspension, collecting the filtrate to obtain a DASAs-1 precursor; the molar ratio of the added furfural to the electron acceptor-1 in S101 is 1:1; S103, dissolving the DASAs-1 precursor in dichloromethane to obtain a DASAs-1 precursor solution with a concentration of 30uM~60uM, then adding an electron donor to the DASAs-1 precursor solution, and reacting at 30~40℃ in the dark for 2~6h, after the reaction is completed, purifying by silica gel column chromatography to obtain DASAs-1; the molar ratio of the added electron donor to the electron acceptor-1 in S101 is (8~10):(8~12). In this step, the reaction is controlled by temperature and environment, without using a catalyst, avoiding the interference of catalyst residues on the photochromic performance of the product (such as the catalyst may absorb specific waveband light, affecting the light response accuracy of DASAs), saving the separation step, reducing the process complexity and production cost, and at the same time, because DASAs is sensitive to visible light (linear→cyclic isomerization), the dark environment can avoid the premature excitation of DASAs during the reaction process, ensuring that the product exists in the "linear colored state" stably, laying a foundation for subsequent compounding with organic dyes. The synthesis route of DASAs-1 is: .

[0011] The two-step reaction design of "electron acceptor→precursor→DASAs" can reduce the generation of by-products, and in the preparation process, the obtained suspension is easy to separate by filtration, and the subsequent reaction with the electron donor is easier to control, so that the purity of the final product is higher.

[0012] Further, the electron acceptor-1 is one of 1,3-dimethylbarbituric acid or 2,2-dimethyl-1,3-dioxane-4,6-dione.

[0013] Further, the preparation method of the DASAs-2 comprises the following steps: S201, dissolving the electron acceptor-2 in deionized water to obtain an electron acceptor-2 solution with a concentration of 0.13-0.3 mol / L; the electron acceptor solution-2; S202, slowly adding furfural to the electron acceptor solution-2, and stirring at 60-80 DEG C for 2-6 h to obtain a second suspension, filtering the second suspension, collecting the filtrate, and obtaining a DASAs-2 precursor; in this step, the molar ratio of the added furfural to the electron acceptor-2 in S201 is 1:1; S203, dissolving the DASAs-2 precursor in dichloromethane to obtain a DASAs-2 precursor solution with a concentration of 30 uM-60 uM, then adding an electron donor to the DASAs-2 precursor solution, and reacting at 30-40 DEG C in the dark for 2-6 h, after the reaction is completed, purifying by silica gel column chromatography to obtain DASAs-2; in this step, the molar ratio of the added electron donor to the electron acceptor-2 in S201 is (8-10):(8-12). The synthesis route of DASAs-2 is as follows: .

[0014] Further, the electron acceptor-2 is one of 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one or 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione.

[0015] Further, the electron donor is indoline or N-propyl aniline.

[0016] The application further provides a preparation method of the adaptive photochromic coating. uniformly mixing polycaprolactone, dichloromethane and tetrahydrofuran to obtain a mixed solvent; uniformly mixing DASAs-1, DASAs-2 and an organic dye to obtain a composition A; adding the composition A into the mixed solvent, uniformly stirring, and obtaining the adaptive photochromic coating.

[0017] The application further provides an application of the adaptive photochromic coating in the field of camouflage.

[0018] Compared with the prior art, the application has the following beneficial effects: (1) The adaptive photochromic coating prepared by the donor-acceptor Stenhouse adduct as a non-fixed hue and the organic dye as a fixed hue is different from the traditional photochromic material which needs to drive the material to change color in the ultraviolet light band.

[0019] (2) The preparation method of the DASAs in the application is simple, low in cost and high in product purity, and through control of the reaction conditions, the product is ensured to exist in a "linear colored state", laying a foundation for the compounding of the product with the organic dye.

[0020] (3) The adaptive photochromic camouflage film formed by the coating obtained by adding the polycaprolactone can realize adaptive camouflage in desert / forest scenes and improve the applicability of the coating in various environments based on the color mixing principle, according to the change of the ambient light (such as green light and yellow light) to adjust the proportion of the non-fixed hue and the fixed hue under the synergistic action of the donor-acceptor Stenhouse adduct, the organic dye and the polycaprolactone. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The UV-visible light absorption spectrum curve and the color change schematic diagram of the DASAs-1 obtained in Example 1 before and after visible light irradiation; Figure 2 The UV-visible light absorption spectrum curve and the color change schematic diagram of the DASAs-2 obtained in Example 1 before and after visible light irradiation; Figure 3 The color of the coating obtained in Example 1, Comparative Example 1 and Comparative Example 4 under natural light; Figure 4 The color of the coating obtained in Example 1, Comparative Example 1 and Comparative Example 4 under green light irradiation; Figure 5 The color of the coating obtained in Example 1, Comparative Example 1 and Comparative Example 4 under yellow light irradiation; Figure 6 The color of the coating obtained in Example 2, Comparative Example 2 and Comparative Example 5 under natural light; Figure 7 The color of the coating obtained in Example 2, Comparative Example 2 and Comparative Example 5 under green light irradiation; Figure 8 The color of the coating obtained in Example 2, Comparative Example 2 and Comparative Example 5 under yellow light irradiation; Figure 9 The color of the coating obtained in Example 3, Comparative Example 3 and Comparative Example 6 under natural light; Figure 10Color of the coating obtained in Example 3, Comparative Example 3, Comparative Example 6 under yellow light irradiation. Figure 11 Color of the coating obtained in Example 3, Comparative Example 3, Comparative Example 6 under yellow light irradiation. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0023] Example 1 The adaptive photochromic coating comprises the following raw materials by weight: polycaprolactone 0.5 parts, dichloromethane 6 parts, tetrahydrofuran 3 parts, and composition A 0.1 parts, wherein the composition A is compounded by DASAs-1, DASAs-2 and an organic dye according to a mass ratio of 1.5:2:1.5.

[0024] The preparation method of the adaptive photochromic coating in the present embodiment is performed according to the following steps: Step 1, preparation of an electron acceptor solution: 2,2-dimethyl-1,3-dioxane-4,6-dione is placed in a round-bottom flask, deionized water is added, and ultrasonic treatment is performed until 2,2-dimethyl-1,3-dioxane-4,6-dione is completely dissolved, thereby preparing a 2,2-dimethyl-1,3-dioxane-4,6-dione solution with a concentration of 0.13 mol / L.

[0025] 1-phenyl-3-(trifluoromethyl)-1H-pyrazole-5(4H)-one is placed in a round-bottom flask, deionized water is added, and ultrasonic treatment is performed until 1-phenyl-3-(trifluoromethyl)-1H-pyrazole-5(4H)-one is completely dissolved, thereby preparing a 1-phenyl-3-(trifluoromethyl)-1H-pyrazole-5(4H)-one solution with a concentration of 0.13 mol / L.

[0026] Step 2, preparation of a DASAs precursor: Furfural is slowly added dropwise to the 2,2-dimethyl-1,3-dioxane-4,6-dione solution obtained in step 1, and heating and stirring are performed at 60°C for 6 h. After that, a yellow precipitate appears in the 2,2-dimethyl-1,3-dioxane-4,6-dione solution, and the yellow precipitate collected after filtration is the DASAs-1 precursor. The molar ratio of the furfural added in this step to the 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 is 1:1.

[0027] To the solution of 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one, furaldehyde was added slowly dropwise. After stirring at 60℃ for 6h, a deep red precipitate appeared in the solution of 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one. After filtration, the deep red precipitate was collected as the precursor of DASAs-2. The molar ratio of furaldehyde to 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 1:1.

[0028] Step 3, preparation of DASAs: The precursor of DASAs-1 was added into dichloromethane to prepare a solution of the precursor of DASAs-1 with a concentration of 30uM. The solution was ultrasonically treated for 4min to fully dissolve the precursor of DASAs-1. Then indoline was added into the solution. The reaction was carried out at 30℃ in the dark for 6h. After the reaction was completed, the final product DASAs-1 was obtained by silica gel column chromatography. The molar ratio of indoline to 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 1:1.

[0029] The precursor of DASAs-2 was added into dichloromethane to prepare a solution of the precursor of DASAs-2 with a concentration of 30uM. The solution was ultrasonically treated for 4min to fully dissolve the precursor of DASAs-2. Then N-propyl aniline was added into the solution. The reaction was carried out at 30℃ in the dark for 6h. After the reaction was completed, the final product DASAs-2 was obtained by silica gel column chromatography. The molar ratio of N-propyl aniline to 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 1:1.

[0030] Step 4, preparation of adaptive photochromic coating: 0.5 parts of polycaprolactone, 6 parts of dichloromethane and 3 parts of tetrahydrofuran were mixed to obtain a mixed solvent by stirring for 2h; DASAs-1, DASAs-2 and pigment yellow 180 were uniformly mixed according to a mass ratio of 1.5:2:1.5 to obtain a composition A. 0.1 parts of the composition A were added into the mixed solvent to obtain an adaptive photochromic coating-1 after uniform stirring.

[0031] Example 2 The adaptive photochromic coating of the present example is composed of the following raw materials by weight: polycaprolactone 0.7 parts, dichloromethane 5 parts, tetrahydrofuran 4 parts, and composition A 0.15 parts. The composition A is composed of DASAs-1, DASAs-2 and organic dye according to a mass ratio of 1.8:1.5:1.

[0032] The preparation method of the adaptive photochromic coating in this embodiment is performed according to the following steps: Step 1, preparation of an electron acceptor solution: 1,3-dimethylbarbituric acid was placed in a round-bottom flask, deionized water was added, and ultrasonic treatment was performed until the 1,3-dimethylbarbituric acid was completely dissolved, thereby preparing a 1,3-dimethylbarbituric acid solution with a concentration of 0.2 mol / L.

[0033] 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione was placed in a round-bottom flask, deionized water was added, and ultrasonic treatment was performed until the 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione was completely dissolved, thereby preparing a 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione solution with a concentration of 0.2 mol / L.

[0034] Step 2, preparation of a DASAs precursor: Furfural was slowly added to the 1,3-dimethylbarbituric acid solution obtained in step 1, and after heating and stirring at 70°C for 4 h, yellow precipitates appeared in the 1,3-dimethylbarbituric acid solution. After filtration, the yellow precipitates collected were the DASAs-1 precursor. The molar ratio of furfural added in this step to 1,3-dimethylbarbituric acid in step 1 was 1:1.

[0035] Furfural was slowly added to the 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione solution, and after heating and stirring at 70°C for 4 h, deep red precipitates appeared in the 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione solution. After filtration, the deep red precipitates collected were the DASAs-2 precursor. The molar ratio of furfural added in this step to 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 1:1.

[0036] Step 3, preparation of DASAs: The DASAs-1 precursor was added to dichloromethane to prepare a DASAs-1 precursor solution with a concentration of 40 uM, and ultrasonic treatment was performed for 6 min to fully dissolve the DASAs-1 precursor. Subsequently, N-propyl aniline was added to the solution, and the reaction was performed at 35°C in the dark for 4 h. After the reaction was completed, the final product DASAs-1 was obtained by purification using a silica gel column chromatography method. The molar ratio of N-propyl aniline added in this step to 1,3-dimethylbarbituric acid in step 1 was 4:5.

[0037] The DASAs-2 precursor was added to dichloromethane to prepare a DASAs-2 precursor solution with a concentration of 40 uM. The DASAs-2 precursor was fully dissolved by ultrasonic treatment for 6 min. Then indoline was added to the solution, and the reaction was carried out at 35°C in the dark for 4 h. After the reaction was completed, the final product DASAs-2 was purified by silica gel column chromatography. In this step, the molar ratio of indoline to 5- (furan-2-ylmethyl) -2, 2-dimethyl-1, 3-dioxane-4, 6-dione in step 1 was 4:5.

[0038] Step 4, preparation of an adaptive photochromic coating: 0.7 parts of polycaprolactone, 5 parts of dichloromethane, and 4 parts of tetrahydrofuran were mixed to obtain a mixed solvent by stirring for 3 h. DASAs-1, DASAs-2, and pigment orange 73 were uniformly mixed in a mass ratio of 1.8:1.5:1 to obtain composition A. 0.15 parts of composition A were added to the mixed solvent and stirred uniformly to obtain an adaptive photochromic coating-2.

[0039] Example 3 This example proposes an adaptive photochromic coating composed of the following parts by weight: polycaprolactone 1 part, dichloromethane 4 parts, tetrahydrofuran 2 parts, and composition A 0.2 parts. The composition A is composed of DASAs-1, DASAs-2, and organic dye in a mass ratio of 2.5:2.5:0.5.

[0040] The preparation method of the adaptive photochromic coating in this example was performed according to the following steps: Step 1, preparation of an electron acceptor solution: 2, 2-dimethyl-1, 3-dioxane-4, 6-dione was placed in a round-bottom flask, deionized water was added, and ultrasonic treatment was performed until 2, 2-dimethyl-1, 3-dioxane-4, 6-dione was completely dissolved to prepare a 2, 2-dimethyl-1, 3-dioxane-4, 6-dione solution with a concentration of 0.25 mol / L.

[0041] 1-phenyl-3- (trifluoromethyl) -1H-pyrazole-5 (4H) -one was placed in a round-bottom flask, deionized water was added, and ultrasonic treatment was performed until 1-phenyl-3- (trifluoromethyl) -1H-pyrazole-5 (4H) -one was completely dissolved to prepare a 1-phenyl-3- (trifluoromethyl) -1H-pyrazole-5 (4H) -one solution with a concentration of 0.25 mol / L.

[0042] Step 2, preparation of a DASAs precursor: To the solution of 2,2-dimethyl-1,3-dioxane-4,6-dione obtained in step 1, furaldehyde was added slowly dropwise. After stirring at 80℃ for 2h, yellow precipitate appeared in the solution of 2,2-dimethyl-1,3-dioxane-4,6-dione. After filtration, the yellow precipitate collected was the precursor of DASAs-1. The molar ratio of furaldehyde to 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 1:1.

[0043] To the solution of 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one obtained in step 1, furaldehyde was added slowly dropwise. After stirring at 80℃ for 2h, deep red precipitate appeared in the solution of 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one. After filtration, the deep red precipitate collected was the precursor of DASAs-2. The molar ratio of furaldehyde to 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 1:1.

[0044] Step 3, preparation of DASAs: The precursor of DASAs-1 was added into dichloromethane to prepare a solution of the precursor of DASAs-1 with a concentration of 60uM. The solution was ultrasonically treated for 2min to fully dissolve the precursor of DASAs-1. Then indoline was added into the solution. The reaction was carried out at 40℃ in the dark for 2h. After the reaction was completed, the final product DASAs-1 was obtained by silica gel column chromatography. The molar ratio of indoline to 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 2:3.

[0045] The precursor of DASAs-2 was added into dichloromethane to prepare a solution of the precursor of DASAs-2 with a concentration of 60uM. The solution was ultrasonically treated for 2min to fully dissolve the precursor of DASAs-2. Then N-propylaniline was added into the solution. The reaction was carried out at 40℃ in the dark for 2h. After the reaction was completed, the final product DASAs-2 was obtained by silica gel column chromatography. The molar ratio of N-propylaniline to 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 2:3.

[0046] Step 4, preparation of adaptive photochromic coating: 1 part of polycaprolactone, 4 parts of dichloromethane and 2 parts of tetrahydrofuran were mixed to obtain a mixed solvent by stirring for 4h; DASAs-1, DASAs-2 and pigment brown 25 were uniformly mixed according to a mass ratio of 2.5:2.5:0.5 to obtain composition A. 0.2 parts of composition A were added into the mixed solvent to obtain adaptive photochromic coating-3 after uniform stirring.

[0047] Example 4 The adaptive photochromic coating is prepared by the following steps:

[0048] The adaptive photochromic coating is prepared by the following steps: Step 1, preparation of an electron acceptor solution: The 1,3-dimethylbarbituric acid solution with a concentration of 0.3 mol / L is prepared by placing 1,3-dimethylbarbituric acid in a round-bottom flask, adding deionized water, and ultrasonically treating until the 1,3-dimethylbarbituric acid is completely dissolved.

[0049] The 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione solution with a concentration of 0.3 mol / L is prepared by placing 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione in a round-bottom flask, adding deionized water, and ultrasonically treating until the 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione is completely dissolved.

[0050] Step 2, preparation of a DASAs precursor: The yellow precipitate collected after filtration is the DASAs-1 precursor. The molar ratio of the furfural added in this step to the 1,3-dimethylbarbituric acid in Step 1 is 1:1.

[0051] The deep red precipitate collected after filtration is the DASAs-2 precursor. The molar ratio of the furfural added in this step to the 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione in Step 1 is 1:1.

[0052] Step 3, preparation of DASAs: The DASAs-1 precursor is added to dichloromethane to prepare a DASAs-1 precursor solution with a concentration of 50 uM, and the DASAs-1 precursor is fully dissolved by ultrasonic treatment for 4 min. Then, N-propyl aniline is added to the solution, and the reaction is carried out at 32°C in the dark for 5 h. After the reaction is completed, the final product DASAs-1 is obtained by silica gel column chromatography. In this step, the molar ratio of N-propyl aniline to 1,3-dimethylbarbituric acid in step 1 is 9:10.

[0053] The DASAs-2 precursor is added to dichloromethane to prepare a DASAs-2 precursor solution with a concentration of 50 uM, and the DASAs-2 precursor is fully dissolved by ultrasonic treatment for 4 min. Then, indoline is added to the solution, and the reaction is carried out at 32°C in the dark for 5 h. After the reaction is completed, the final product DASAs-2 is obtained by silica gel column chromatography. In this step, the molar ratio of indoline to 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 is 9:10.

[0054] Step 4, preparation of an adaptive photochromic coating: 1.2 parts of polycaprolactone, 5 parts of dichloromethane, and 5 parts of tetrahydrofuran are mixed to obtain a mixed solvent by stirring for 4 h; DASAs-1, DASAs-2, and pigment orange 73 are uniformly mixed in a mass ratio of 2.3:1.7:1.3 to obtain composition A. 0.25 parts of composition A are added to the mixed solvent and uniformly stirred to obtain an adaptive photochromic coating-4.

[0055] Example 5 This example proposes an adaptive photochromic coating, which is composed of the following raw materials by weight: polycaprolactone 1.5 parts, dichloromethane 4 parts, tetrahydrofuran 6 parts, and composition A 0.3 parts. The composition A is compounded by DASAs-1, DASAs-2, and organic dye in a mass ratio of 2:2.3:0.8.

[0056] The preparation method of the adaptive photochromic coating in this example is performed according to the following steps: Step 1, preparation of an electron acceptor solution: 2,2-dimethyl-1,3-dioxane-4,6-dione is placed in a round-bottom flask, deionized water is added, and ultrasonic treatment is performed until 2,2-dimethyl-1,3-dioxane-4,6-dione is completely dissolved to prepare a 2,2-dimethyl-1,3-dioxane-4,6-dione solution with a concentration of 0.18 mol / L.

[0057] A round bottom flask was charged with 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one, deionized water was added, and the mixture was sonicated until the 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one was completely dissolved to prepare a 0.18 mol / L 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one solution.

[0058] Step 2, preparation of a precursor of the DASAs: To the 2,2-dimethyl-1,3-dioxane-4,6-dione solution obtained in step 1, furaldehyde was slowly added dropwise, and after heating and stirring at 75°C for 3 h, a yellow precipitate appeared in the 2,2-dimethyl-1,3-dioxane-4,6-dione solution. After filtration, the yellow precipitate collected was the DASAs-1 precursor. The molar ratio of the furaldehyde added in this step to the 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 1:1.

[0059] To the 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one solution, furaldehyde was slowly added dropwise, and after heating and stirring at 75°C for 3 h, a deep red precipitate appeared in the 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one solution. After filtration, the deep red precipitate collected was the DASAs-2 precursor. The molar ratio of the furaldehyde added in this step to the 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 1:1.

[0060] Step 3, preparation of the DASAs: The DASAs-1 precursor was added to dichloromethane to prepare a 45 uM DASAs-1 precursor solution, and the DASAs-1 precursor was fully dissolved by ultrasonic treatment for 6 min. Subsequently, indoline was added to the solution, and the reaction was carried out at 37°C in the dark for 3 h. After the reaction was completed, the final product DASAs-1 was obtained by purification using silica gel column chromatography. The molar ratio of the indoline added in this step to the 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 5:6.

[0061] The DASAs-2 precursor was added to dichloromethane to prepare a 45 uM DASAs-2 precursor solution, and the DASAs-2 precursor was fully dissolved by ultrasonic treatment for 6 min. Subsequently, N-propylaniline was added to the solution, and the reaction was carried out at 37°C in the dark for 3 h. After the reaction was completed, the final product DASAs-2 was obtained by purification using silica gel column chromatography. The molar ratio of the N-propylaniline added in this step to the 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 5:6.

[0062] Step 4, preparation of adaptive photochromic coating: 1.5 parts of polycaprolactone, 4 parts of dichloromethane, 6 parts of tetrahydrofuran were mixed and stirred for 2 h to obtain a mixed solvent; DASAs-1, DASAs-2 and pigment yellow 180 were mixed uniformly according to a mass ratio of 2:2.3:0.8 to obtain composition A; 0.3 parts of composition A were added to the mixed solvent and stirred uniformly to obtain adaptive photochromic coating-5.

[0063] Comparative Example 1 The difference between this comparative example and Example 1 is that the raw material components of the adaptive photochromic coating do not contain polycaprolactone in this comparative example, and the others are the same as Example 1.

[0064] Comparative Example 2 The difference between this comparative example and Example 2 is that the raw material components of the adaptive photochromic coating do not contain polycaprolactone in this comparative example, and the others are the same as Example 2.

[0065] Comparative Example 3 The difference between this comparative example and Example 3 is that the raw material components of the adaptive photochromic coating do not contain polycaprolactone in this comparative example, and the others are the same as Example 3.

[0066] Comparative Example 4 The difference between this comparative example and Example 1 is that the preparation process of DASAs in Step 3 is as follows: The DASAs-1 precursor was added to dichloromethane to prepare a DASAs-1 precursor solution with a concentration of 30 uM, and the DASAs-1 precursor was fully dissolved by ultrasonic for 4 min. Then indoline was added to the solution, and the reaction was carried out at 30°C under natural light for 6 h. After the reaction was completed, the final product DASAs-1 was obtained by silica gel column chromatography. The molar ratio of indoline added in this step to 2,2-dimethyl-1,3-dioxane-4,6-dione in Step 1 was 1:1.

[0067] The DASAs-2 precursor was added to dichloromethane to prepare a DASAs-2 precursor solution with a concentration of 30 uM, and the DASAs-2 precursor was fully dissolved by ultrasonic for 4 min. Then N-propyl aniline was added to the solution, and the reaction was carried out at 30°C under natural light for 6 h. After the reaction was completed, the final product DASAs-2 was obtained by silica gel column chromatography. The molar ratio of N-propyl aniline added in this step to 1-phenyl-3-(trifluoromethyl)-1H-pyrazole-5(4H)-one in Step 1 was 1:1.

[0068] The others are the same as Example 1.

[0069] Comparative Example 5 The difference between this comparative example and Example 1 is that in this comparative example, the preparation process of step 3 DASAs is as follows: The DASAs-1 precursor was added to dichloromethane to prepare a DASAs-1 precursor solution with a concentration of 40 uM. The DASAs-1 precursor was fully dissolved by ultrasonic treatment for 6 min. Then, N-propyl aniline was added to the solution, and the reaction was carried out at 35°C under natural light for 4 h. After the reaction was completed, the final product DASAs-1 was obtained by silica gel column chromatography. In this step, the molar ratio of N-propyl aniline added to 1,3-dimethylbarbituric acid in step 1 was 4:5.

[0070] The DASAs-2 precursor was added to dichloromethane to prepare a DASAs-2 precursor solution with a concentration of 40 uM. The DASAs-2 precursor was fully dissolved by ultrasonic treatment for 6 min. Then, indoline was added to the solution, and the reaction was carried out at 35°C under natural light for 4 h. After the reaction was completed, the final product DASAs-2 was obtained by silica gel column chromatography. In this step, the molar ratio of indoline added to 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 4:5.

[0071] The same as Example 2 Comparative Example 6 The difference between this comparative example and Example 1 is that in this comparative example, the preparation process of step 3 DASAs is as follows: The DASAs-1 precursor was added to dichloromethane to prepare a DASAs-1 precursor solution with a concentration of 60 uM. The DASAs-1 precursor was fully dissolved by ultrasonic treatment for 2 min. Then, indoline was added to the solution, and the reaction was carried out at 40°C under natural light for 2 h. After the reaction was completed, the final product DASAs-1 was obtained by silica gel column chromatography. In this step, the molar ratio of indoline added to 2,2-dimethyl-1,3-dioxane-4,6-dione in step 1 was 2:3.

[0072] The DASAs-2 precursor was added to dichloromethane to prepare a DASAs-2 precursor solution with a concentration of 60 uM. The DASAs-2 precursor was fully dissolved by ultrasonic treatment for 2 min. Then, N-propyl aniline was added to the solution, and the reaction was carried out at 40°C under natural light for 2 h. After the reaction was completed, the final product DASAs-2 was obtained by silica gel column chromatography. In this step, the molar ratio of N-propyl aniline added to 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one in step 1 was 2:3.

[0073] The same as Example 3.

[0074] In order to better illustrate the beneficial effects of the present application, UV-visible spectrum test was conducted on DASAs-1 and DASAs-1 obtained in Example 1 of the present application, and color comparison was made on the coatings obtained in Examples 1-3 and Comparative Examples 1-6 under natural light, yellow light and green light.

[0075] From Figure 1 It can be seen that the DASAs-1 prepared in the present application changes from purple to colorless under ultraviolet light, and the photochromic excitation wavelength is 560 nm, and the colored state can be excited by green light to realize the transition to colorless state. From Figure 2 It can be seen that the DASAs-2 prepared in the present application changes from blue to colorless under ultraviolet light, and the photochromic excitation wavelength is 645 nm, and the colored state can be excited by red light to realize the transition to colorless state; the photochromic coating prepared by taking DASAs-1 and DASAs-2 as photochromic phase and organic pigment as stationary phase can realize self-adaptive photochromism under specific light source according to the subtractive three primary color principle.

[0076] From Figures 3 to 11 It can be seen that the coating prepared in the present application has excellent self-adaptive change effect under green light and yellow light, and the pattern formed by the coating prepared in the present application has strong universality and can realize self-adaptive camouflage in desert / forest and other scenes; from Figures 3 to 11 It can be seen that the coating obtained in Comparative Example 1-3 hardly changes color under green light and yellow light, which is because the energy barrier to be broken in the process of changing the linear structure of DASAs to the ring structure is high, which will lead to the failure of molecular isomerization and thus the realization of electrochromism. The ester functional group of polycaprolactone can significantly affect the structure of intramolecular hydrogen bond, thereby promoting proton transfer. The presence of ester group can change the strength and length of hydrogen bond, improve the activity of proton, and make the proton transfer easier, thereby promoting the photoisomerization process of DASAs from linear structure to ring structure. From Figures 3 to 11 It can also be seen that the coatings obtained in Comparative Examples 4-6 do not completely realize color transition under yellow light and green light, and the color difference between the obtained system and the theoretical color obtained by the color mixing principle is large. This is because the stability of DASAs is directly related to its molecular structure: linear conjugated structure is stable, and ring non-conjugated structure is unstable. Dark environment can block visible light to trigger isomerization, ensure that DASAs always exist in stable linear structure during synthesis, thereby avoiding side reactions and improving product uniformity, and finally showing higher stability; non-dark conditions trigger isomerization in advance, which destroys the stable structure of the molecule, resulting in a decrease in the stability of the product. Therefore, the self-adaptive photochromic material synthesized in dark conditions has smaller color difference with the surrounding background.

[0077] The detailed description set forth above discloses merely the preferred embodiments of the present application and is not intended to limit the scope of the application. Various modifications and variations will be apparent to those skilled in the art from this detailed description, which is given by way of example only. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation.

[0078] It is to be understood that the application is not limited to the details of the foregoing description, and that various modifications and changes can be made without departing from the scope of the application. The scope of the application is limited only by the claims that follow.

Claims

1. An adaptive photochromic coating, characterized in that, The composition comprises the following components by weight: polycaprolactone 0.5-1.5 parts, dichloromethane 4-6 parts, tetrahydrofuran 2-6 parts, and composition A 0.1-0.3 parts, wherein the composition A is compounded by DASAs-1, DASAs-2 and an organic dye.

2. The adaptive photochromic coating of claim 1, wherein, The composition A is compounded by DASAs-1, DASAs-2 and an organic dye in a mass ratio of (1.5-2.5):(1.5-2.5):(0.5-1.5).

3. The adaptive photochromic coating of claim 1, wherein, The organic dye comprises one of Pigment Yellow 180, Pigment Orange 73 and Pigment Brown 25.

4. The self-adapting photochromic coating according to claim 1, wherein, The preparation method of the DASAs-1 comprises the following steps: S101, dissolving an electron acceptor-1 in deionized water to obtain an electron acceptor solution-1; S102, slowly adding furfural to the electron acceptor solution-1, and then heating and stirring to obtain a first suspension, filtering the first suspension, collecting the filtrate, and obtaining a DASAs-1 precursor; S103, dissolving the DASAs-1 precursor in dichloromethane to obtain a DASAs-1 precursor solution, then adding an electron donor to the DASAs-1 precursor solution for reaction, and purifying the reaction product by silica gel column chromatography to obtain the DASAs-1.

5. The adaptive photochromic coating of claim 4, wherein, The electron acceptor-1 is one of 1,3-dimethylbarbituric acid or 2,2-dimethyl-1,3-dioxane-4,6-dione.

6. The self-adapting photochromic coating according to claim 1, wherein, The preparation method of the DASAs-2 comprises the following steps: S201, dissolving an electron acceptor-2 in deionized water to obtain an electron acceptor solution-2; S202, slowly adding furfural to the electron acceptor solution-2, and then heating and stirring to obtain a second suspension, filtering the second suspension, collecting the filtrate, and obtaining a DASAs-2 precursor; S203, dissolving the DASAs-2 precursor in dichloromethane to obtain a DASAs-2 precursor solution, then adding an electron donor to the DASAs-2 precursor solution for reaction, and purifying the reaction product by silica gel column chromatography to obtain the DASAs-2.

7. The adaptive photochromic coating of claim 6, wherein, The electron acceptor-2 is one of 1-phenyl-3-(trifluoromethyl)-1H-pyrazol-5(4H)-one or 5-(furan-2-ylmethyl)-2,2-dimethyl-1,3-dioxane-4,6-dione.

8. The adaptive photochromic coating of claim 4 or 6, wherein, The electron donor is indoline or N-propyl aniline.

9. A method for preparing the self-adapting photochromic coating according to claim 1, characterized in that, The method comprises the following steps: mixing polycaprolactone, dichloromethane and tetrahydrofuran uniformly to obtain a mixed solvent; mixing DASAs-1, DASAs-2 and an organic dye uniformly to obtain a composition A; adding the composition A into the mixed solvent, and stirring uniformly to obtain the self-adapting photochromic coating.

10. Application of the self-adapting photochromic coating of any one of claims 1-7 in the field of camouflage.

Images