An antifogging optical coating material and a preparation method thereof

Abstract

This invention belongs to the field of optical coating materials and nanostructure preparation technology, specifically relating to an anti-fogging optical coating material and its preparation method. Addressing the problem that current superhydrophilic coatings easily dissolve and lose their hydrophilic components upon contact with water, leading to a gradual decline in anti-fogging performance, this invention cleans and pre-treats a fluorine-doped tin oxide conductive glass substrate with ultraviolet ozone. Then, a dense zinc oxide seed layer is prepared on its surface using an dip-coating method. Next, the substrate with the seed layer is immersed in a growth solution containing zinc nitrate and hexamethylenetetramine, and an electrochemically assisted in-situ growth method is used to grow an array of zinc oxide nanopillars with a regular structure on the substrate. Finally, the resulting film is subjected to high-temperature annealing to control defects and improve crystallinity, and combined with ultraviolet irradiation treatment to activate surface hydroxyl groups.

Description

Technical Field

[0001] This invention belongs to the field of optical coating materials and nanostructure preparation technology, specifically relating to an anti-fog optical coating material and its preparation method. Background Technology

[0002] Under conditions of sudden temperature changes or extremely high relative humidity, water vapor condensation easily occurs on the surface of transparent optical substrates. Tiny water droplets on the solid surface form hemispherical shapes due to surface tension. These densely packed droplets cause severe Mie scattering of light, resulting in a macroscopic "fogging" phenomenon. Fogging significantly reduces the transmittance and imaging clarity of optical devices, posing a considerable negative impact on transportation, medical surgical protection, and the stable operation of precision optical sensors.

[0003] To eliminate surface fogging, the most widely adopted strategy in the current technological field is to prepare superhydrophilic anti-fogging coatings. The core mechanism of superhydrophilic coatings lies in reducing the surface water contact angle, allowing condensed water droplets to spontaneously spread upon contact with the surface, forming a continuous, uniform, and transparent water film with a refractive index close to that of water, thereby effectively preventing light scattering. To achieve surface superhydrophilization, technicians typically dope or graft a large number of surfactants, amphiphilic polymers, or water-soluble organic molecules containing polar hydrophilic groups into the coating (CN116589981A).

[0004] However, the aforementioned technical solutions based on organic macromolecules or hydrophilic small molecules generally face a challenge: the hydrophilic components in the coating, due to their large number of polar groups, are thermodynamically highly soluble in water. When the anti-fog coating is subjected to rain, long-term adhesion of condensate, or manual washing in practical applications, the hydrophilic components in the coating will dissolve, migrate, and eventually be lost into the aqueous phase. This interphase mass transfer process leads to a sharp decrease in the density of polar groups on the coating surface, and the surface's superhydrophilic properties irreversibly degrade to a hydrophobic state, resulting in a significant time-limited effect on the anti-fog performance.

[0005] In summary, there is an urgent need for an anti-fog optical coating material to solve the technical problem that the hydrophilic components of superhydrophilic coatings easily dissolve and are lost after contact with water, leading to a gradual decline in anti-fog performance. Summary of the Invention

[0006] This invention provides an anti-fog optical coating material and its preparation method. By adopting a pure inorganic electrochemical-assisted in-situ growth strategy, a zinc oxide nanopillar array is constructed, which solves the problem of anti-fog component loss.

[0007] The specific technical solution is as follows: This invention provides an anti-fog optical coating material and its preparation method, as detailed below: S1: Substrate pretreatment: Fluorine-doped tin oxide conductive glass is ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water in sequence, dried, and treated with ultraviolet ozone to obtain a pretreated substrate.

[0008] S2: Deposition of zinc oxide seed crystal layer.

[0009] S21: Add zinc acetate dihydrate to anhydrous ethanol, stir, then add ethanolamine, heat and stir, let stand, and obtain the precursor sol.

[0010] S22: The pretreated substrate prepared in S1 is vertically immersed in the precursor sol prepared in S21, left to stand for 20 seconds, vertically pulled out, dried, heat-treated, and coated 2 to 4 times to obtain a substrate with a seed crystal layer.

[0011] S3: Electrochemical-assisted growth of zinc oxide nanopillar arrays.

[0012] S31: Add zinc nitrate hexahydrate to deionized water, stir, then add hexamethylenetetramine, and continue stirring to obtain the growth solution.

[0013] S32: The growth solution prepared in S31 is heated to 90°C, and the substrate with seed crystal layer prepared in S22 is immersed in the growth solution. Three-electrode electrochemical deposition is performed, followed by washing and drying to obtain a substrate with ZnO deposited on the surface.

[0014] S4: Annealing and activation. The substrate with surface-deposited ZnO prepared in S32 is annealed at high temperature, cooled to room temperature, and then treated with ultraviolet light to obtain an optical coating material.

[0015] Furthermore, the ultrasonic cleaning described in S1 has the following parameter settings: power 100-300W, frequency 40-80kHz, and duration 15-30min.

[0016] The ultraviolet ozone treatment described in S1 has the following parameter settings: wavelengths of 185nm and 254nm, and duration of 20min.

[0017] Furthermore, the ethanolamine described in S21 has a molar ratio of 0.8:1 to 1.2:1 with zinc acetate dihydrate.

[0018] The heating and stirring described in S21 has the following parameters: rotation speed 300-500 rpm, temperature 50-70℃, and duration 1-2 hours.

[0019] The vertical lifting described in S22 has the following parameter settings: lifting speed 2-4 mm / s.

[0020] The drying process described in S22 has the following parameters: temperature 100-120℃, duration 5-10 min.

[0021] The heat treatment described in S22 has the following parameters: temperature 350-400℃, duration 10-30min.

[0022] Furthermore, in the growth solution described in S31, the concentration of zinc nitrate hexahydrate is 0.025 mol / L, and the concentration of hexamethylenetetramine is 0.025 mol / L.

[0023] In the three-electrode electrochemical deposition described in S32, the working electrode is a substrate with a seed crystal layer, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl reference electrode connected to the growth solution through a salt bridge. The electrode body of the Ag / AgCl reference electrode is not directly placed in the 90°C growth solution. A constant potential mode is adopted, the working potential is -1V relative to the reference electrode, and the deposition time is 60min.

[0024] Furthermore, the high-temperature annealing described in S4 has the following parameter settings: temperature 400-450℃, heating rate 2-5℃ / min, and holding time 1-2h.

[0025] The ultraviolet light irradiation treatment described in S4 has the following parameter settings: wavelength 254nm, distance 3cm, power density 15~20mW / cm². 2 The duration is 30 to 60 minutes.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes ultraviolet light to induce the chemical adsorption of hydroxyl groups on the ZnO lattice surface, which then firmly bind to the crystal framework, preventing the loss of hydrophilic components.

[0027] 2. This invention reduces light scattering loss inside the coating and ensures high transmittance by using electrochemically assisted growth of ZnO. Attached Figure Description

[0028] Figure 1 This is the XRD pattern of the optical coating material prepared in Example 1.

[0029] Figure 2 These are XPS images of the optical coating materials prepared in Example 1 and Comparative Example 4, wherein... Figure 2 a is the optical coating material prepared in Example 1. Figure 2 b is the material after the optical coating material prepared in Example 1 has been immersed in water for 72 hours. Figure 2 c is the optical coating material prepared in Comparative Example 4. Detailed Implementation

[0030] The following describes in further detail an anti-fog optical coating material and its preparation method according to this application. This does not limit the scope of protection of this application; rather, the scope of protection is defined by the claims. Certain specific details disclosed provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented using other materials, etc., without employing one or more of these specific details.

[0031] This invention proposes an anti-fog optical coating material and its preparation method, the detailed technical solution of which is as follows: 1. Substrate pretreatment Fluorine-doped tin oxide (FTO) conductive glass was ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water, dried, and then treated with ultraviolet ozone to obtain a pretreated substrate.

[0032] Gradient ultrasonic cleaning with acetone, ethanol, and deionized water sequentially removes non-polar organic contaminants, polar organic residues, ionic contaminants, and particulate matter. 185nm ultraviolet light decomposes oxygen in the air into ozone, simultaneously attacking the covalent bonds of organic molecules, causing them to break and activate. 254nm ultraviolet light further decomposes ozone, generating highly reactive oxygen atoms with strong oxidizing capabilities. Simultaneously, it works synergistically with ozone to completely oxidize the activated organic matter into volatile products such as carbon dioxide, water, and small amounts of nitrogen oxides, which escape from the surface. After ultraviolet ozone treatment, the FTO surface generally forms a polar surface rich in hydroxyl groups and negatively charged oxygen, increasing the surface energy and hydrophilicity, which is beneficial for the uniform anchoring and directional adhesion of the subsequent zinc oxide seed layer to the substrate surface as "nucleation sites."

[0033] 2. Deposition of zinc oxide seed layer Zinc acetate dihydrate was added to anhydrous ethanol and stirred. Then ethanolamine (MEA) was added, heated and stirred, and allowed to stand to obtain a precursor sol. The pretreated substrate was vertically immersed in the precursor sol in an environment with a relative humidity of less than 50%, allowed to stand for 20 seconds, vertically lifted, dried, and heat-treated. The coating was repeated 2 to 4 times to obtain a substrate with a zinc oxide seed layer.

[0034] Ethanolamine contains an amino group at one end and a hydroxyl group at the other. In the sol, MEA interacts with Zn in the solution via the lone pair of electrons on its amino group. 2+ A coordination reaction occurs, forming a stable, soluble tetracoordinated zinc-amine complex, which prevents Zn from reacting. 2+Ions undergo premature hydrolysis to form insoluble Zn(OH)₂ precipitate. Due to the near-anhydrous system and low ambient humidity, hydrolysis is minimized, and the sol remains transparent. When the substrate is vertically pulled from the sol, a uniform solution layer of a certain thickness adheres to the substrate surface due to the viscosity and surface tension of the liquid. Anhydrous ethanol gradually evaporates during the pulling process and subsequent drying, causing the solution to become supersaturated, and the zinc-amine complex deposits on the substrate surface to form a gel film. During heat treatment, the zinc-amine complex undergoes thermal decomposition: firstly, MEA dissociates from the complex and evaporates; subsequently, the acetate ions in the remaining zinc precursor decompose and leave in the form of CO₂ and CH₃COOH gases; finally, Zn-O bonds gradually form at around 300–350℃, and Zn… 2+ With O 2- The resulting ZnO crystal nuclei combine and form. As the temperature increases further, the nuclei continue to grow and fuse together, forming a dense nanocrystalline thin film with a wurtzite structure on the substrate surface.

[0035] 3. Electrochemical-assisted growth of zinc oxide nanopillar arrays Zinc nitrate hexahydrate was added to deionized water and stirred. Then hexamethylenetetramine (HMTA) was added and stirred again to obtain a growth solution. The growth solution was heated, and then the substrate with the seed crystal layer was immersed in the growth solution. Three-electrode electrochemical deposition was performed, followed by washing and drying to obtain a substrate with ZnO deposited on the surface.

[0036] HMTA slowly hydrolyzes to produce ammonia and formaldehyde, thus creating a weakly alkaline environment that continuously and slowly generates OH- at the cathode interface. - Synergistic NO3 - The electrochemical reduction reaction ensures sufficient OH- - It provides the necessary nutrients without causing excessively rapid precipitation, thus inhibiting homogeneous nucleation in the solution. Simultaneously, HMTA can selectively adsorb onto nonpolar surfaces, suppressing the lateral growth rate of these surfaces and limiting the lateral expansion of the grains. This promotes directional growth of crystals along the polar c-axis, ultimately forming an array of nanopillars or nanorods perpendicular to the substrate.

[0037] Compared to a simple two-electrode system, the introduction of a three-electrode system enables highly stable and precise control of deposition potential or current density. During the high-temperature, long-duration deposition process of this invention, changes in the solution composition near the electrode surface cause resistance drift. A two-electrode system cannot eliminate the potential drift caused by IR drop, easily leading to deposition cessation or the deposition of samples with inhomogeneous phases and inconsistent morphologies. The three-electrode system, through a reference electrode, monitors the real potential of the working electrode in real time, locking the deposition process within the target potential region and ensuring the orientational stability of the single crystal along the c-axis. Simultaneously, a dense nano-ZnO seed layer is pre-deposited before the electrodeposited ZnO layer, reducing the nucleation barrier for electrochemical deposition and promoting the preferential orientation of ZnO grains perpendicular to the substrate direction (c-axis). To avoid the influence of the high-temperature growth solution on the stability of the Ag / AgCl reference electrode, in this embodiment, the reference electrode body is not directly exposed to the 90°C growth solution, but is connected to the growth solution via a salt bridge, and potential verification is performed before and after deposition. Therefore, the working electrode potential during the deposition process can be maintained within a repeatable controllable range, avoiding uncontrollable ZnO nucleation and orientation growth due to reference electrode drift.

[0038] 4. Annealing and Activation The substrate with ZnO deposited on its surface is annealed at high temperature, cooled to room temperature, and then treated with ultraviolet light to obtain an optical coating material.

[0039] During electrochemically assisted in-situ growth, oxygen vacancies exist in zinc oxide crystals due to limitations in growth kinetics and thermodynamics. During annealing in an air atmosphere at 400–450°C, oxygen molecules in the air adsorb onto the zinc oxide surface at high temperatures and dissociate. The dissociated active oxygen atoms migrate into the zinc oxide lattice through thermal diffusion, filling the oxygen vacancies. When the zinc oxide surface is irradiated with ultraviolet light of energy greater than its band gap, valence band electrons are excited and jump to the conduction band, generating electron-hole pairs. Photogenerated holes have strong oxidizing capabilities and can react with adsorbed water molecules or hydroxyl groups to generate hydroxyl radicals. These hydroxyl radicals can oxidize and decompose trace amounts of organic matter adsorbed on the surface. Simultaneously, photogenerated electrons can react with adsorbed oxygen molecules to generate superoxide anion radicals, which also participate in the surface cleaning process. The generated hydroxyl radicals react with surface zinc atoms, and photogenerated holes can directly promote the dissociation of adsorbed water molecules, ultimately forming a dense and stable surface hydroxyl monolayer. The solution does not introduce water-soluble organic hydrophilic agents. The hydrophilicity mainly comes from the spreading / capillary effect induced by the inorganic ZnO surface hydroxyl groups and nanostructure, thus reducing the risk of migration and dissolution of added hydrophilic agents. In this invention, annealing and ultraviolet irradiation are two sequential but complementary steps, neither of which can be omitted. If only annealing is performed without ultraviolet irradiation, although crystal defects are reduced, the surface hydroxyl density is limited, resulting in insufficient anti-fogging performance. If only ultraviolet irradiation is performed without annealing, the surface hydroxyl bonds are unstable and easily detach after long-term immersion in water or repeated condensation-evaporation cycles, leading to a rapid decline in anti-fogging performance.

[0040] Example 1 A method for preparing an anti-fog optical coating material is as follows: Table 1 Main Raw Materials S1: Substrate pretreatment. Fluorine-doped tin oxide conductive glass was ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water, dried, and then treated with ultraviolet ozone to obtain the pretreated substrate. The ultrasonic cleaning parameters were set as follows: power 200W, frequency 60kHz, duration 23min; the ultraviolet ozone treatment parameters were set as follows: wavelengths 185nm and 254nm, duration 20min.

[0041] S2: Deposition of zinc oxide seed crystal layer.

[0042] S21: Add zinc acetate dihydrate to 500 mL of anhydrous ethanol, stir, then add ethanolamine, heat and stir, and let stand to obtain the precursor sol. The molar ratio of ethanolamine to zinc acetate dihydrate is 1:1; the heating and stirring parameters are set as follows: 400 rpm, 60℃, and 1.5 h.

[0043] S22: The pretreated substrate prepared in S1 is vertically immersed in the precursor sol prepared in S21, left to stand for 20 seconds, vertically pulled at a speed of 3 mm / s, dried at 110℃ for 8 minutes, and heat-treated at 375℃ for 20 minutes. The coating is repeated 3 times to obtain a substrate with a seed crystal layer.

[0044] S3: Electrochemical-assisted growth of zinc oxide nanopillar arrays.

[0045] S31: Add zinc nitrate hexahydrate to deionized water and stir. Then add hexamethylenetetramine and continue stirring to obtain the growth solution. The concentration of zinc nitrate hexahydrate and hexamethylenetetramine is 0.025 mol / L.

[0046] S32: The growth solution prepared in S31 was heated to 90℃. The substrate with the seed crystal layer prepared in S22 was immersed in the growth solution. Three-electrode electrochemical deposition was performed (the working electrode was the substrate with the seed crystal layer, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl reference electrode connected to the growth solution through a salt bridge. The reference electrode body was kept at room temperature or cooled and protected, and was not directly placed in the 90℃ growth solution. The potential of the reference electrode was checked before and after deposition to confirm that the potential drift was within the allowable range of experimental error. A constant potential mode was used, with the working potential relative to the reference electrode being -1V, and the deposition time being 60min). After washing and drying, a substrate with ZnO deposited on the surface was obtained.

[0047] S4: Annealing and Activation. The ZnO-deposited substrate prepared in S32 was subjected to high-temperature annealing, cooled to room temperature, and then treated with ultraviolet light to obtain the optical coating material. The high-temperature annealing parameters were set as follows: temperature 425℃, heating rate 3.5℃ / min, and holding time 1.5h; the ultraviolet light irradiation parameters were set as follows: wavelength 254nm, distance 3cm, and power density 18mW / cm³. 2 The duration is 45 minutes.

[0048] Example 2 The composition and preparation process are the same as in Example 1, except that: The ultrasonic cleaning parameters in step S1 of the preparation process are set as follows: power 100W, frequency 40kHz, duration 15min, and other steps are the same.

[0049] In the preparation process S21, the molar ratio of ethanolamine to zinc acetate dihydrate is 0.8:1, and the other components are the same.

[0050] The heating and stirring parameters in step S21 of the preparation process are set as follows: rotation speed 300 rpm, temperature 50℃, duration 1 h, and other steps are the same.

[0051] Example 3 The composition and preparation process are the same as in Example 1, except that: The ultrasonic cleaning parameters in step S1 of the preparation process are set as follows: power 300W, frequency 80kHz, duration 30min, and other steps are the same.

[0052] In the preparation process S21, the molar ratio of ethanolamine to zinc acetate dihydrate is 1.2:1, and the other components are the same.

[0053] The heating and stirring parameters in step S21 of the preparation process are set as follows: rotation speed 500 rpm, temperature 70℃, duration 2h, and other steps are the same.

[0054] Example 4 The composition and preparation process are the same as in Example 1, except that: In the preparation process S21, the molar ratio of ethanolamine to zinc acetate dihydrate is 0.9:1, and the other components are the same.

[0055] In the S22 preparation process, the vertical lifting speed is 2 mm / s, the drying parameters are set as follows: temperature 100℃, time 5 min, the heat treatment parameters are set as follows: temperature 350℃, time 10 min, the coating is repeated twice, and other steps are the same.

[0056] The high-temperature annealing parameters for process S4 are set as follows: temperature 400℃, heating rate 2℃ / min, holding time 1h; the ultraviolet irradiation treatment parameters are set as follows: power density 15mW / cm³. 2 The duration is 30 minutes, and the other steps are the same.

[0057] Example 5 The composition and preparation process are the same as in Example 1, except that: In the preparation process S21, the molar ratio of ethanolamine to zinc acetate dihydrate is 1.1:1, and the other components are the same.

[0058] In the S22 preparation process, the vertical lifting speed is 4 mm / s, the drying parameters are set as follows: temperature 120℃, time 10 min, the heat treatment parameters are set as follows: temperature 400℃, time 30 min, the coating is repeated 4 times, and other steps are the same.

[0059] The high-temperature annealing parameters for process S4 are set as follows: temperature 450℃, heating rate 5℃ / min, holding time 2h; the ultraviolet irradiation treatment parameters are set as follows: power density 20mW / cm³. 2 The duration is 60 minutes, and the other steps are the same.

[0060] Comparative Example 1 The composition and preparation process are the same as in Example 1, except that: In step S2 of the fabrication process, the deposition of the zinc oxide seed layer is removed, and the pretreated substrate is directly electrochemically deposited. The other steps are the same.

[0061] Comparative Example 2 The composition and preparation process are the same as in Example 1, except that: Electrochemical deposition in step S3 of the preparation process was removed, and ZnO was prepared by the traditional sol-gel dip-coating method (the concentration of the seed crystal liquid precursor in step S2 was increased by 5 times, and the dip-coating was repeated 15 times on the FTO substrate using the dip-coating method), with the other steps being the same.

[0062] Comparative Example 3 The composition and preparation process are the same as in Example 1, except that: In step S4 of the preparation process, high-temperature annealing is removed, and ultraviolet light treatment is used directly. The other steps are the same.

[0063] Comparative Example 4 The composition and preparation process are the same as in Example 1, except that: In step S4 of the preparation process, ultraviolet light treatment is removed, and only high-temperature annealing is performed; the other steps remain the same.

[0064] Samples of the optical coating material prepared in Example 1 were taken and cut into 10mm × 10mm sheet samples for XRD testing (scanning range 20°–70°, scan step 0.01°, blank substrate control sample was the pretreated substrate in S1). Figure 1 As shown, the (100) peak near 2θ≈31.7° and the (101) peak near 2θ≈36.2° are extremely weak. Near 2θ≈34.4°, the diffraction peaks are attributed to the (002) crystal plane of ZnO. At the same time, no obvious characteristic peaks of Zn(OH)2, residual zinc salt, organic precursor crystals or other impurity phases appear in the spectrum, indicating that the ZnO nanopillar array has a significant c-axis preferred orientation and its

[0001] crystal direction is perpendicular to the FTO substrate surface.

[0065] Samples were taken from the optical coating materials prepared in Example 1 and Comparative Example 4. The samples from Example 1 were divided into an initial group ( Figure 2 a) and the immersion group (72h immersion treatment, Figure 2 b) Normal sampling of the optical coating material prepared in Comparative Example 4 ( Figure 2 c) Perform XPS testing (full-spectrum scan range 0–1200 eV, step size 0.5 eV; high-resolution scan range 528–535 eV, step size 0.05 eV), such as Figure 2 As shown, in Figure 2In sample a, the hydroxyl component accounts for approximately 58.2%, indicating that after the synergistic effect of annealing and ultraviolet irradiation, the ZnO surface no longer contains only a small amount of physically adsorbed water or occasional hydroxyl groups, but rather a large number of chemically bonded hydroxyl groups related to zinc sites on the ZnO surface. This high-density hydroxyl layer can significantly improve the surface polarity and surface energy of the material, causing water vapor to tend to spread rapidly into a continuous water film after condensation, rather than forming discrete droplets. Therefore, it is beneficial to improve anti-fogging performance. Figure 2 In b, the proportion of hydroxyl components changed to 57.6%, indicating that water immersion treatment did not significantly weaken the high-binding-energy hydroxyl components. Figure 2 In c, the proportion of high-energy hydroxyl peaks is about 17.8%, indicating that although high-temperature annealing is beneficial to improving the quality of ZnO crystals and reducing some defects, annealing alone cannot construct high-density surface chemically bonded hydroxyl groups.

[0066] Based on Examples 1-5 and Comparative Examples 1-4, samples of the finally prepared optical coating materials were taken for water contact angle testing: the optical coating materials were divided into an initial group and an immersion group (immersed in deionized water for 72 hours and naturally dried for 10 minutes), and placed in an environment of 23°C and 50% relative humidity for 30 minutes. The optical contact angle was measured using an optical contact angle measuring instrument, and 5 points were selected in different areas for testing and the average value was taken.

[0067] Based on Examples 1-5 and Comparative Examples 1-4, samples of the finally prepared optical coating materials were taken for haze and transmittance tests: the coated surface of the sample was facing the incident light window, and a dual-beam integrating sphere haze meter was used for testing (the reference sample was air, the scanning wavelength range was 300-900 nm, and the calculation wavelength range was 400-800 nm). Three sets of tests were conducted, and the average value was taken.

[0068] The specific test results are shown in Table 2. Figure 1 , Figure 2 As shown: Table 2 Comparison of core performance of Examples 1-5 and Comparative Examples 1-4 The comparison results show that Example 1 has the best performance. The optimized seed layer and the best synergistic post-processing process formed a dense, strong ZnO crystal structure rich in stable hydroxyl groups, which effectively suppressed the dissolution of hydrophilic components. This indicates that Example 1 successfully solved the problem that the hydrophilic components in the superhydrophilic coating are easily dissolved and lost after contact with water, leading to a gradual decline in anti-fogging performance. The overall performance of Examples 2 to 5 is slightly lower than that of Example 1, but still maintains a high level. This shows that the performance degradation problem was alleviated even under a large range of parameter variations. Comparative Example 1, because the deposition of the zinc oxide seed layer was removed, directly performed electrochemical deposition on the pretreated substrate, resulting in disordered ZnO growth and poor adhesion to the substrate. Comparative Example 2 used the traditional sol-gel dip coating method, resulting in a loose and porous coating with poor physical stability and severely insufficient water resistance. Comparative Example 3 did not undergo high-temperature annealing, and the UV treatment alone could not fully crystallize ZnO. The hydroxyl groups were mainly physically adsorbed rather than chemically bonded, and dissolved in large quantities after contact with water. Comparative Example 4 did not undergo UV treatment, resulting in high haze and insufficient practicality.

[0069] In summary, it is clear from the above embodiments and comparative examples that the anti-fogging optical coating material provided by the present invention is significantly superior to traditional solutions in solving the problem of gradual decay of anti-fogging performance. This is attributed to the optimization of the seed crystal layer, electrochemical assisted growth, appropriate annealing, and synergistic photoactivation, thereby solving the problem that the hydrophilic components in the superhydrophilic coating of the anti-fogging optical coating material are easily dissolved and lost after contact with water, leading to a gradual decay of anti-fogging performance.

Claims

1. An anti-fog optical coating material, comprising a transparent conductive substrate, a ZnO seed layer, and a ZnO nanopillar array layer sequentially disposed therefrom, characterized in that: The transparent conductive substrate is fluorine-doped tin oxide conductive glass; the ZnO nanopillar array layer is composed of hexagonal columnar ZnO nanopillars preferentially oriented along the c-axis, and grown perpendicularly to the [0001] crystal direction.

2. The anti-fog optical coating material according to claim 1, characterized in that: The surface water contact angle of the ZnO nanopillar array layer is less than 5°.

3. The anti-fog optical coating material according to claim 1, characterized in that: The anti-fog optical coating material, after being immersed in water for 72 hours, has a surface water contact angle of no more than 10° and an average transmittance of no less than 90%.

4. A method for preparing an anti-fog optical coating material according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Substrate pretreatment: Fluorine-doped tin oxide conductive glass is ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence, dried and treated with ultraviolet ozone to obtain pretreated substrate. S2: Deposition of zinc oxide seed crystal layer; S21: Add zinc acetate dihydrate to anhydrous ethanol, stir, then add ethanolamine, heat and stir, let stand, and obtain the precursor sol. S22: The pretreated substrate prepared in S1 is vertically immersed in the precursor sol prepared in S21, left to stand for 20 seconds, vertically pulled out, dried, heat-treated, and coated 2 to 4 times to obtain a substrate with a seed crystal layer. S3: Electrochemical-assisted growth of zinc oxide nanopillar arrays; S31: Add zinc nitrate hexahydrate to deionized water, stir, then add hexamethylenetetramine, and continue stirring to obtain the growth solution; S32: The growth solution prepared in S31 is heated to 90°C, and the substrate with seed crystal layer prepared in S22 is immersed in the growth solution. Three-electrode electrochemical deposition is performed, followed by washing and drying to obtain a substrate with ZnO deposited on the surface. S4: Annealing and activation. The substrate with surface-deposited ZnO prepared in S32 is annealed at high temperature, cooled to room temperature, and then treated with ultraviolet light to obtain an optical coating material.

5. The method for preparing an anti-fog optical coating material according to claim 4, characterized in that: The ultrasonic cleaning described in S1 has the following parameters: power 100-300W, frequency 40-80kHz, and duration 15-30min. The ultraviolet ozone treatment described in S1 has the following parameter settings: wavelengths of 185nm and 254nm, and duration of 20min.

6. The method for preparing an anti-fog optical coating material according to claim 4, characterized in that: The ethanolamine described in S21 has a molar ratio of 0.8:1 to 1.2:1 with zinc acetate dihydrate. The heating and stirring described in S21 has the following parameters: rotation speed 300-500 rpm, temperature 50-70℃, and duration 1-2 hours.

7. The method for preparing an anti-fog optical coating material according to claim 4, characterized in that: The vertical lifting described in S22 has the following parameter settings: lifting speed 2-4 mm / s; The drying described in S22 has the following parameters: temperature 100-120℃, duration 5-10min; The heat treatment described in S22 has the following parameters: temperature 350-400℃, duration 10-30min.

8. The method for preparing an anti-fog optical coating material according to claim 4, characterized in that: The growth solution described in S31 contains zinc nitrate hexahydrate at a concentration of 0.025 mol / L and hexamethylenetetramine at a concentration of 0.025 mol / L.

9. The method for preparing an anti-fog optical coating material according to claim 4, characterized in that: In the three-electrode electrochemical deposition described in S32, the working electrode is a substrate with a seed crystal layer, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl reference electrode connected to the growth solution through a salt bridge. The electrode body of the Ag / AgCl reference electrode is not directly placed in the 90°C growth solution. A constant potential mode is adopted, the working potential is -1V relative to the reference electrode, and the deposition time is 60min.

10. The method for preparing an anti-fog optical coating material according to claim 4, characterized in that: The high-temperature annealing described in S4 has the following parameter settings: temperature 400~450℃, heating rate 2~5℃ / min, and holding time 1~2h. The ultraviolet light irradiation treatment described in S4 has the following parameter settings: wavelength 254nm, distance 3cm, power density 15~20mW / cm². 2 The duration is 30 to 60 minutes.

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