Transparent photochromic bicontinuous network coated article and method of making same

Abstract

The invention provides a preparation method of a transparent photochromic bicontinuous network coating product, which comprises the following steps: adding an initiator, a chain transfer agent, a first solvent and a precipitator into a single-ended active PDMS (Polydimethylsiloxane) macromonomer, a hydrophilic monomer and a silane coupling agent monomer to obtain a reactive amphiphilic grafted copolymer; mixing the reactive amphiphilic graft copolymer, inorganic nanoparticles, photochromic molecules and a second solvent, and uniformly stirring at 50-80 DEG C to prepare a coating solution; and uniformly coating the surface of a transparent base material with the coating liquid, placing the transparent base material in an air dry oven, and carrying out baking treatment to generate a cross-linking reaction so as to obtain the transparent photochromic bicontinuous network coating product. The invention provides a transparent photochromic bicontinuous network coating product. The product is easy to manufacture, high in response speed, high in color changing sensitivity, stable in structure, high in weather resistance and long in service life.

Description

Technical Field

[0001] The invention belongs to the field of photochromic materials, and in particular relates to a transparent photochromic double-continuous network coating product and a preparation method thereof. Background Art

[0002] With the rapid development of smart materials and functional coating technologies, demand for photochromic materials is growing in applications such as smart windows, dynamic visual protection, optical storage, anti-counterfeiting packaging, and military camouflage. Traditional photochromic coatings primarily utilize organic dye dispersions or inorganic semiconductor material systems, but these applications still face numerous technical bottlenecks.

[0003] Inorganic photochromic materials, such as WO3, TiO2 and other inorganic semiconductor materials, have good environmental stability, but their light response speed is slow (fading time> 5 minutes) and coloring efficiency is low (< 50cm 2 The characteristics of the material ( / J) limit its dynamic application scenarios. In addition, the color-changing properties of inorganic materials are highly dependent on the concentration of lattice defects, and traditional sintering processes make it difficult to precisely control the distribution of oxygen vacancies at grain boundaries, resulting in poor batch stability of the material.

[0004] Organic photochromic systems have shown significant advantages in many fields due to their unique dynamic response characteristics. Although organic photochromic materials represented by spiropyran and spirooxazine have the advantages of fast response speed and high color change sensitivity, they generally have problems such as poor weather resistance and short fatigue life, and the reversible change rate of their structure is greatly limited by the molecular rigidity of the microenvironment. For example, ZL201711110838.6 discloses a composite multilayer photochromic material containing polyurethane / spiropyran / zinc sulfide, the core of which is zinc sulfide mesoporous nanospheres, the middle layer is a photochromic layer composed of spiropyran compounds, and the outer shell is polyurethane. In addition, organic color-changing coatings prepared by traditional solution blending methods often experience dye aggregation, resulting in a decrease in optical transparency (haze > 30%) and uneven response.

[0005] In summary, an organic color-changing coating facility that is easy to manufacture, has a fast response speed, high color-changing sensitivity, stable structure, strong weather resistance, and long service life is in urgent need of development. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing a transparent photochromic double-continuous network coating product that is simple, easy to implement and suitable for large-scale production.

[0007] The present invention also aims to provide a transparent photochromic bicontinuous network coating product, which has the advantages of high transparency, rapid photochromic response, excellent cycle stability, etc.

[0008] To achieve the above-mentioned and other related purposes, the present invention provides a method for preparing a transparent photochromic bicontinuous network coating product, comprising the following steps:

[0009] S1, preparation of a reactive amphiphilic graft copolymer: adding an initiator, a chain transfer agent, and a first solvent to a single-end active PDMS macromonomer, a hydrophilic monomer, and a silane coupling agent monomer, and mechanically stirring the mixture at 60-80° C. for 6-12 hours under an inert gas atmosphere to obtain a mixed solution of the reactive amphiphilic graft copolymer; slowly dropwise adding the mixed solution of the reactive amphiphilic graft copolymer to a precipitant, vigorously stirring for 0.5-1.0 hour, collecting the solid by filtration, and redissolving it in the first solvent at 50-80° C., repeating the dissolution-precipitation three times to obtain a reactive amphiphilic graft copolymer;

[0010] S2, preparing a coating solution: mixing the reactive amphiphilic graft copolymer, inorganic nanoparticles, photochromic molecules and a second solvent, and stirring uniformly at 50-80° C. to prepare a coating solution;

[0011] S3, prepare a photochromic bicontinuous network coating product: adopt a pull-up dip coating process or a spin coating process to uniformly coat the coating liquid on the surface of a transparent substrate, place it in a forced air drying oven, and bake it at 60-120°C for 0.5-2.0h to cause a cross-linking reaction to form the transparent photochromic bicontinuous network coating product with a thin layer of high molecular weight polymer in a three-dimensional network structure attached to the surface of the photochromic molecules.

[0012] Preferably, the weight ratio of the single-end active PDMS macromonomer, hydrophilic monomer, silane coupling agent monomer, initiator, chain transfer agent and first solvent in step S1 is 100:50-100:1.0-5.0:0.5-2.5:0.5-2.5:600-1000.

[0013] Preferably, in step S1, the weight ratio of the mixed solution of the amphiphilic graft copolymer, the precipitant, and the solvent 1 is 100:200-400:40-100.

[0014] Preferably, the single-end active PDMS macromonomer in step S1 is a monoacryloxy-terminated PDMS or a monomethacryloxy-terminated PDMS; the hydrophilic monomer is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyoxyethylene methacrylate and polyoxyethylene acrylate; the silane coupling agent monomer is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane and allyltrimethoxysilane.

[0015] Preferably, the initiator in step S1 is one of azobisisobutyronitrile, azobisisoheptanenitrile and dibenzoyl peroxide; the chain transfer agent is one of γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane and mercaptopropylmethyldimethoxysilane.

[0016] Preferably, the first solvent is one or more of ethyl acetate, butyl acetate, 2-butanone and tetrahydrofuran; the inert gas is high-purity nitrogen or high-purity argon; and the precipitant is one or more of n-hexane, n-heptane, acetone, methanol, ethanol and butanol.

[0017] Preferably, the weight ratio of the reactive amphiphilic graft copolymer, the inorganic nanoparticles, the photochromic molecules and the second solvent in step S2 is 100:0.5-2.0:1.5-3.5:400-500.

[0018] Preferably, the inorganic nanoparticles are nano-silicon dioxide, nano-titanium dioxide, nano-zinc oxide or nano-ferroferric oxide; the photochromic molecules are one or more of spiropyran, spirooxazine and naphthopyran photochromic substances, such as N-hydroxyethyl-3,3-dimethyl-6-nitroindolinyl spiropyran, N-ethyl-3,3-dimethyl-6'-morpholinyl spirooxazine-2,3'-[3H]naphtho[2,1-b][1,4]oxazine, 5-chloro-1,3,3-trimethyl-1,3-dihydrospiro[indole-2,3'-naphtho[2,1-b][ [1,4]oxazine], 1,3-dihydro-1,3,3-trimethyl-6'-(4-morpholinyl)-spiro[2H-indole-2,3'-[3H]naphtho[2,1-b][1,4]oxazine], 3,3-diphenyl-3H-naphtho[2,1-b]pyran, 3,3-dimethoxyphenyl-3H-naphtho[2,1-b]pyran; the second solvent is one or more of ethyl acetate, butyl acetate, 2-butanone, isopropanol, ethanol and 2,2-dimethyl-1-butanol; the viscosity of the coating liquid is 400-800cp at 25°C.

[0019] Preferably, the transparent substrate is a sun lens, a myopia lens, a protective mask, a PC film or a PET film.

[0020] A transparent photochromic double-continuous network coating product is prepared according to the above method.

[0021] The transparent photochromic double-continuous network coating product provided in this case has the following beneficial effects:

[0022] 1) Based on the unique micro-nano phase separation structure of the bicontinuous network and the high flexibility of the PDMS segments, the present invention prepares a photochromic coating based on the bicontinuous network. Its color change sensitivity and transparency are much higher than those of traditional color-changing coatings. The preparation process is simple and practical, and it is easy to industrialize.

[0023] 2) Based on the rigidity of inorganic nanoparticles, chemical crosslinking between organic and inorganic materials is established to prepare organic-inorganic hybrid bicontinuous network coatings, which synergistically achieve the high flexibility of the photochromic molecular microenvironment and the high hardness of the macroscopic coating, thereby optimizing the performance of the photochromic coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the H NMR spectrum of the single-end active PDMS macromonomer used in Example 1 of the present invention;

[0025] Figure 2 This is the H NMR spectrum of the reactive amphiphilic graft copolymer prepared in Example 1 of the present invention;

[0026] Figure 3 The absorbance of the photochromic coating prepared in Example 1 of the present invention in the ultraviolet-visible band;

[0027] Figure 4 The absorbance of the photochromic coating prepared in Example 1 of the present invention in the ultraviolet-visible band after color development;

[0028] Figure 5 The change of light transmittance during the color development process of the photochromic coating prepared in Example 1 of the present invention with illumination time;

[0029] Figure 6 The change of light transmittance over time during the fading process of the photochromic coating prepared in Example 1 of the present invention;

[0030] Figure 7 These are the effects of the photochromic coating prepared in Example 1 of the present invention before and after color change after being irradiated with sunlight for 10 minutes. DETAILED DESCRIPTION

[0031] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0032] The anti-pollution composite membrane obtained in the example was tested and evaluated for the following technical indicators.

[0033] (1) Color change sensitivity test: The prepared sample was placed in a dark box and allowed to stand for 24 h to completely fade. As the initial state of the test, the UV light source (365 nm) was turned on and the timer was started at the same time. The illumination distance was kept at 10 cm. Spectral data was collected every 30 seconds using a spectrophotometer until the color change tended to be stable. The UV light source was then turned off and the color parameters were continued to be measured every 30 seconds until they recovered to within 10% of the initial value. The fading time was recorded.

[0034] (2) Coating hardness determination: The pencil hardness method is used to determine the coating hardness. First, place the coating sample to be tested on a hard, flat surface. Start with a soft pencil and gradually increase the hardness. Push the pencil forward at a 45° angle for about 6-10 mm until you find the highest pencil level that does not scratch the coating. This is the coating hardness level.

[0035] (3) Transparency test: The coating is evenly applied on a transparent substrate (such as glass, PET film), and a spectrophotometer is used to scan the visible light range (380-780 nm). The transmittance curve is recorded, and the average transmittance at a specific wavelength (such as 550 nm) or the entire wavelength band is calculated. The transparency of the coating is evaluated by the transmittance.

[0036] Unless otherwise specified, all reagents used in the following examples of the present invention were of analytical grade and purchased from China National Pharmaceutical Group Shanghai Chemical Reagent Company.

[0037] Example 1:

[0038] A method for preparing a transparent photochromic bicontinuous network coating product comprises the following steps:

[0039] 1. Preparation of reactive amphiphilic graft copolymers: Reactive amphiphilic graft copolymers are prepared by free radical polymerization.

[0040] (1) Monomethacryloyloxy terminated PDMS (molecular weight 4600 g / mol, such as Figure 1 As shown), hydroxyethyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, in the presence of an initiator azobisisobutyronitrile and a chain transfer agent γ-mercaptopropyltrimethoxysilane, reacting in ethyl acetate under a high-purity nitrogen atmosphere at 80°C with mechanical stirring for 10 hours to obtain a mixed solution of a reactive amphiphilic graft copolymer; wherein the weight ratio of the monomethacryloyloxy-terminated PDMS, hydroxyethyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, azobisisobutyronitrile, γ-mercaptopropyltrimethoxysilane and ethyl acetate is 100:90:3.0:1.5:1.5:800;

[0041] (2) The mixed solution of the reactive amphiphilic graft copolymer described in (1) was slowly added dropwise to n-hexane, and after vigorous stirring for 0.5 h, the solid was collected by filtration and redissolved in ethyl acetate at 60° C. The above dissolution-precipitation steps were repeated 3 times to obtain a reactive amphiphilic graft copolymer (such as Figure 2 As shown), wherein the weight ratio of the mixed solution of the amphiphilic graft copolymer, n-hexane and ethyl acetate is 100:300:80.

[0042] 2. Preparation of a coating liquid: The reactive amphiphilic graft copolymer, nano-silica, N-ethyl-3,3-dimethyl-6'-morpholinospiroindoline-2,3'-[3H]naphtho[2,1-b][1,4]oxazine and butyl acetate are mixed and stirred uniformly at 60°C to prepare a coating liquid; the weight ratio of the reactive amphiphilic graft copolymer, nano-silica, N-ethyl-3,3-dimethyl-6'-morpholinospiroindoline-2,3'-[3H]naphtho[2,1-b][1,4]oxazine and butyl acetate is 100:1.5:2.5:500.

[0043] 3. Producing a photochromic bicontinuous network coating product: Using a pull-up dip coating process, the coating liquid is evenly coated on the surface of a transparent sun lens substrate, and the substrate is placed in a forced air drying oven and baked at 120° C. for 2.0 h to cause a cross-linking reaction to form a transparent photochromic bicontinuous network coating sun lens product with a thin layer of a high molecular weight polymer in a three-dimensional network structure attached to the surface of the photochromic molecules.

[0044] After testing, the sun lens based on the transparent color-changing coating of the bicontinuous network prepared in this embodiment has almost no absorption in the visible light band before color development (such as Figure 3 As shown), the light transmittance is as high as 95.3% (as shown Figure 5 As shown), it has obvious absorption of visible light after being irradiated by ultraviolet light (as shown Figure 4 It takes about 11 minutes to fade to 10% of the initial value (as shown in Figure 6 (as shown), with a coating hardness of 5H. Compared to a photochromic polyurethane coating without a bicontinuous network (transmittance 91.2%, coating hardness 4H, fading time 19 minutes), the fading rate and coating hardness are significantly improved. This bicontinuous network structure maintains continuity and interpenetration in three dimensions, exhibiting macroscopically uniform transparency and microscopic phase separation. Its unique micro-nano two-phase condensed structure ensures the coating's high transparency and excellent color development / fading responsiveness.

[0045] Example 2:

[0046] A method for preparing a transparent photochromic bicontinuous network coating product comprises the following steps:

[0047] 1. Preparation of reactive amphiphilic graft copolymers: Reactive amphiphilic graft copolymers are prepared by free radical polymerization.

[0048] (1) Monomethacryloyloxy-terminated PDMS (molecular weight 4600 g / mol), polyoxyethylene methacrylate, and γ-methacryloyloxypropyltrimethoxysilane are reacted in butyl acetate under the protection of a high-purity nitrogen atmosphere with mechanical stirring at 80° C. for 12 hours in the presence of an initiator, azobisisobutyronitrile, and a chain transfer agent, to obtain a mixed solution of a reactive amphiphilic graft copolymer; wherein the weight ratio of the monomethacryloyloxy-terminated PDMS, polyoxyethylene methacrylate, γ-methacryloyloxypropyltrimethoxysilane, azobisisobutyronitrile, γ-mercaptopropyltrimethoxysilane, and butyl acetate is 100:90:2.0:2.0:1.0:900;

[0049] (2) slowly adding the mixed solution of the reactive amphiphilic graft copolymer to methanol, stirring vigorously for 0.5 h, collecting the solid by filtration, and redissolving it in butyl acetate at 60° C., repeating the dissolution-precipitation process three times to obtain the reactive amphiphilic graft copolymer; wherein the weight ratio of the mixed solution of the amphiphilic graft copolymer, methanol, and butyl acetate is 100:350:80.

[0050] 2. Preparation of coating solution: the steps are the same as step 2 of Example 1.

[0051] 3. Preparation of a photochromic bicontinuous network coating product: the steps are the same as step 3 of Example 1.

[0052] Testing showed that the transparent, color-changing coating based on the bicontinuous network produced in this example had a transmittance of 95.1%, a coating hardness of 5H, and a fading time of approximately 10.5 minutes to 10% of its initial value. This significantly improved fading rate and coating hardness compared to a photochromic polyurethane coating without a bicontinuous network (transmittance of 91.2%, coating hardness of 4H, and fading time of 19 minutes).

[0053] Example 3:

[0054] A method for preparing a transparent photochromic bicontinuous network coating product comprises the following steps:

[0055] 1. Preparation of reactive amphiphilic graft copolymers: Reactive amphiphilic graft copolymers are prepared by free radical polymerization.

[0056] (1) Monoacryloxy-terminated PDMS (molecular weight 4600 g / mol), hydroxyethyl acrylate, and γ-acryloxypropyltrimethoxysilane are reacted in ethyl acetate under the protection of a high-purity nitrogen atmosphere with mechanical stirring at 80° C. for 10 hours in the presence of an initiator, azobisisobutyronitrile, and a chain transfer agent, to obtain a mixed solution of a reactive amphiphilic graft copolymer; wherein the weight ratio of the monoacryloxy-terminated PDMS, hydroxyethyl acrylate, γ-acryloxypropyltrimethoxysilane, azobisisobutyronitrile, γ-mercaptopropyltrimethoxysilane, and ethyl acetate is 100:90:3.0:2.0:1.5:900;

[0057] (2) slowly adding the mixed solution of the reactive amphiphilic graft copolymer to methanol, stirring vigorously for 0.5 h, collecting the solid by filtration, and redissolving it in ethyl acetate at 60° C., repeating the dissolution-precipitation process three times to obtain the reactive amphiphilic graft copolymer, wherein the weight ratio of the mixed solution of the amphiphilic graft copolymer, methanol, and ethyl acetate is 100:300:80.

[0058] 2. Preparation of coating solution: same as step 2 of Example 1.

[0059] 3. Preparation of photochromic bicontinuous network coating product: Same as step 3 of Example 1.

[0060] Testing showed that the transparent, color-changing coating based on the bicontinuous network produced in this example had a transmittance of 95.2%, a coating hardness of 5H, and a fading time of approximately 10.7 minutes to 10% of its initial value. This significantly improved fading rate and coating hardness compared to a photochromic polyurethane coating without a bicontinuous network (transmittance of 91.2%, coating hardness of 4H, and fading time of 19 minutes).

[0061] Example 4:

[0062] A method for preparing a transparent photochromic bicontinuous network coating product comprises the following steps:

[0063] 1. Preparation of reactive amphiphilic graft copolymer: same as step 1 of Example 1.

[0064] 2. Preparation of coating liquid: The reactive amphiphilic graft copolymer, nano-titanium dioxide, 1,3-dihydro-1,3,3-trimethyl-6'-(4-morpholinyl)-spiro[2H-indole-2,3'-[3H]naphtho[2,1-b][1,4]oxazine] and butyl acetate are mixed and stirred evenly at 60°C to prepare a coating liquid; the weight ratio of the reactive amphiphilic graft copolymer, nano-titanium dioxide, 1,3-dihydro-1,3,3-trimethyl-6'-(4-morpholinyl)-spiro[2H-indole-2,3'-[3H]naphtho[2,1-b][1,4]oxazine] and butyl acetate is 100:1.5:2.5:500.

[0065] 3. Preparation of photochromic bicontinuous network coating product: Same as step 3 of Example 1.

[0066] Testing showed that the transparent, color-changing coating based on the bicontinuous network produced in this example had a transmittance of 95.0%, a coating hardness of 5H, and a fading time of approximately 11.2 minutes to 10% of its initial value. This significantly improved fading rate and coating hardness compared to a photochromic polyurethane coating without a bicontinuous network (transmittance of 91.5%, coating hardness of 4H, and fading time of 19.5 minutes).

[0067] Example 5:

[0068] A method for preparing a transparent photochromic bicontinuous network coating product comprises the following steps:

[0069] 1. Preparation of reactive amphiphilic graft copolymer: same as step 1 of Example 1.

[0070] 2. Preparation of coating liquid: The reactive amphiphilic graft copolymer, nano-titanium dioxide, 5-chloro-1,3,3-trimethyl-1,3-dihydrospiro[indole-2,3'-naphtho[2,1-b][1,4]oxazine] and butyl acetate are mixed and stirred evenly at 60°C to prepare a coating liquid; the weight ratio of the reactive amphiphilic graft copolymer, nano-titanium dioxide, 5-chloro-1,3,3-trimethyl-1,3-dihydrospiro[indole-2,3'-naphtho[2,1-b][1,4]oxazine] and butyl acetate is 100:1.5:2.5:500.

[0071] 3. Preparation of photochromic bicontinuous network coating product: same as step 1 of Example 1.

[0072] Testing showed that the transparent, color-changing coating based on the bicontinuous network produced in this example had a transmittance of 95.4%, a coating hardness of 5H, and a fading time of approximately 11.1 minutes to 10% of its initial value. This significantly improved fading rate and coating hardness compared to a photochromic polyurethane coating without a bicontinuous network (91.6% transmittance, 4H coating hardness, and 19.8 minutes).

[0073] Example 6:

[0074] A method for preparing a transparent photochromic bicontinuous network coating product comprises the following steps:

[0075] 1. Preparation of reactive amphiphilic graft copolymer: same as step 1 of Example 1.

[0076] 2. Preparation of the coating liquid: The reactive amphiphilic graft copolymer, nano-titanium dioxide, 3,3-dimethoxyphenyl-3H-naphtho[2,1-b]pyran and butyl acetate are mixed and stirred evenly at 60°C to prepare a coating liquid; the weight ratio of the reactive amphiphilic graft copolymer, nano-titanium dioxide, 3,3-dimethoxyphenyl-3H-naphtho[2,1-b]pyran and butyl acetate is 100:1.5:2.5:500.

[0077] 3. Preparation of photochromic bicontinuous network coating product: same as step 3 of Example 1.

[0078] Testing showed that the transparent, color-changing coating based on the bicontinuous network produced in this example had a transmittance of 95.3%, a coating hardness of 5 hours, and a fading time of approximately 11.4 minutes to 10% of its initial value. This significantly improved fading rate and coating hardness compared to a photochromic polyurethane coating without a bicontinuous network (transmittance of 91.8%, coating hardness of 4 hours, and fading time of 19.4 minutes).

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a transparent photochromic bicontinuous network coating product, characterized in that: The preparation steps include, S1, preparation of a reactive amphiphilic graft copolymer: adding an initiator, a chain transfer agent, and a first solvent to a single-end active PDMS macromonomer, a hydrophilic monomer, and a silane coupling agent monomer, and mechanically stirring the mixture at 60-80° C. for 6-12 hours under an inert gas atmosphere to obtain a mixed solution of the reactive amphiphilic graft copolymer; slowly dropwise adding the mixed solution of the reactive amphiphilic graft copolymer to a precipitant, vigorously stirring for 0.5-1.0 hour, collecting the solid by filtration, and redissolving it in the first solvent at 50-80° C., repeating the dissolution-precipitation three times to obtain a reactive amphiphilic graft copolymer; S2, preparing a coating solution: mixing the reactive amphiphilic graft copolymer, inorganic nanoparticles, photochromic molecules and a second solvent, and stirring uniformly at 50-80° C. to prepare a coating solution; S3, prepare a photochromic bicontinuous network coating product: adopt a pull-up dip coating process or a spin coating process to uniformly coat the coating liquid on the surface of a transparent substrate, place it in a forced air drying oven, and bake it at 60-120°C for 0.5-2.0h to cause a cross-linking reaction to form the transparent photochromic bicontinuous network coating product with a thin layer of high molecular weight polymer in a three-dimensional network structure attached to the surface of the photochromic molecules.

2. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 1, characterized in that: The weight ratio of the single-end active PDMS macromonomer, hydrophilic monomer, silane coupling agent monomer, initiator, chain transfer agent and first solvent in step S1 is 100:50-100:1.0-5.0:0.5-2.5:0.5-2.5:600-1000.

3. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 2, characterized in that: In step S1, the weight ratio of the mixed solution of the amphiphilic graft copolymer, the precipitant, and the solvent 1 is 100:200-400:40-100.

4. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 1, 2 or 3, characterized in that: The single-end active PDMS macromonomer in step S1 is a monoacryloxy-terminated PDMS or a monomethacryloxy-terminated PDMS; the hydrophilic monomer is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyoxyethylene methacrylate and polyoxyethylene acrylate; the silane coupling agent monomer is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane and allyltrimethoxysilane.

5. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 4, characterized in that: The initiator in step S1 is one of azobisisobutyronitrile, azobisisoheptanenitrile and dibenzoyl peroxide; the chain transfer agent is one of γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane and mercaptopropylmethyldimethoxysilane.

6. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 5, characterized in that: The first solvent is one or more of ethyl acetate, butyl acetate, 2-butanone and tetrahydrofuran; the inert gas is high-purity nitrogen or high-purity argon; and the precipitant is one or more of n-hexane, n-heptane, acetone, methanol, ethanol and butanol.

7. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 6, characterized in that: The weight ratio of the reactive amphiphilic graft copolymer, the inorganic nanoparticles, the photochromic molecules and the second solvent in step S2 is 100:0.5-2.0:1.5-3.5:400-500.

8. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 7, characterized in that: The inorganic nanoparticles are nano-silicon dioxide, nano-titanium dioxide, nano-zinc oxide or nano-ferroferric oxide; the photochromic molecules are one or more of spiropyran, spirooxazine and naphthopyran photochromic substances; the second solvent is one or more of ethyl acetate, butyl acetate, 2-butanone, isopropanol, ethanol and 2,2-dimethyl-1-butanol; The coating liquid has a viscosity of 400 to 800 cp at 25°C.

9. The method for preparing a transparent photochromic bicontinuous network coating product according to claim 8, characterized in that: The transparent substrate is a sun lens, a myopia lens, a protective mask, a PC film or a PET film.

10. A transparent photochromic bicontinuous network coating product, characterized in that: A transparent photochromic double-continuous network coating product prepared by the method according to claim 9.

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