Self-repairing anticorrosive coating and preparation method thereof

Abstract

The application discloses a kind of self-repairing anticorrosive paint and preparation method thereof, it is related to paint technical field;The self-repairing anticorrosive paint of the application includes 1.5~2.5 mass parts cyclodextrin-based polyurethane, 1.5~2.5 mass parts azobenzene-based composite polyurethane, 0.15~0.25 mass parts hollow mesoporous silica, 0.15~0.25 mass parts leveling agent, 7.5~12.5 mass parts solvent by weight fraction;Among them, cyclodextrin-based polyurethane is obtained by reaction of cyclodextrin and toluene diisocyanate;Azobenzene-based composite polyurethane is obtained by composite reaction of 4,4'-dihydroxyazobenzene, modified polyaniline and toluene diisocyanate;The self-repairing anticorrosive paint prepared by the application has good self-repairing effect, good anticorrosive performance, good adhesion and good mechanical properties.

Description

Technical Field

[0001] This invention relates to a self-healing anti-corrosion coating and its preparation method. Background Technology

[0002] Metal corrosion is a long-standing problem plaguing industry, causing not only huge economic losses but also potentially serious safety accidents and environmental pollution. Statistics show that global economic losses due to metal corrosion reach hundreds of billions of dollars annually, accounting for a significant proportion of GDP in many countries. Therefore, developing efficient anti-corrosion measures is of great importance for protecting metal structures, extending equipment lifespan, and ensuring production safety. Among numerous anti-corrosion measures, coating corrosion protection has become one of the most commonly used methods due to its convenient application, low cost, and wide applicability.

[0003] Although anti-corrosion coating technology is quite mature, traditional anti-corrosion coatings still have some shortcomings, especially in terms of durability and self-healing capabilities in complex environments. Once the coating is scratched or cracked, corrosive media can penetrate the substrate through these defects, accelerating the metal corrosion process and leading to anti-corrosion failure. Therefore, the research and development of anti-corrosion coatings with self-healing functions has become an important direction in recent years.

[0004] Polyaniline is an excellent green corrosion inhibitor with no environmental side effects compared to conventional corrosion inhibitors. It exhibits an "activation-passivation" behavior on metallic materials, accelerating the formation of a passivation film on the metal surface through a reversible redox reaction, thereby effectively inhibiting corrosion. Introducing polyaniline into azophenyl composite polyurethane can effectively improve its anti-corrosion performance. However, polyaniline has poor compatibility with coating matrices (such as epoxy resins and acrylic resins), leading to poor dispersion in coatings and consequently affecting the overall performance of the coating. Specifically, this manifests as decreased coating adhesion, weakened mechanical strength, and unstable anti-corrosion effects.

[0005] To overcome the above-mentioned problems, this invention proposes a self-healing anti-corrosion coating and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a self-healing anti-corrosion coating and its preparation method to solve the technical problems mentioned in the background section.

[0007] The technical solution to achieve the purpose of this invention is: a self-healing anti-corrosion coating, which, by weight, comprises 1.5 to 2.5 parts by weight of cyclodextrin-based polyurethane, 1.5 to 2.5 parts by weight of azophenyl composite polyurethane, 0.15 to 0.25 parts by weight of hollow mesoporous silica, 0.15 to 0.25 parts by weight of leveling agent, and 7.5 to 12.5 parts by weight of solvent.

[0008] Furthermore, the cyclodextrin-based polyurethane is obtained by reacting cyclodextrin with toluene diisocyanate.

[0009] Furthermore, the azophenyl composite polyurethane is obtained by a composite reaction of polytetrahydrofuran, 4,4'-dihydroxyazobenzene, modified polyaniline, and toluene diisocyanate.

[0010] Furthermore, the modified polyaniline is obtained by modifying polyaniline with cystine.

[0011] This invention also provides a method for preparing a self-healing anti-corrosion coating, comprising the following preparation steps:

[0012] 1.5–2.5 parts by weight of cyclodextrin-based polyurethane and 1.5–2.5 parts by weight of azophenyl composite polyurethane were dissolved in 7.5–12.5 parts by weight of dimethyl sulfoxide solvent. Then, 0.15–0.25 parts by weight of hollow mesoporous silica were added and dispersed at 2000–4000 rpm for 25–35 min. Next, 0.15–0.25 parts by weight of leveling agent were added and dispersion was continued for 4–6 min. The mixture was then treated with 365 nm UV for 10–20 min and dried in an oven at 58–62 °C for 28–32 min to obtain a self-healing anti-corrosion coating.

[0013] Further, the preparation steps of the cyclodextrin-based polyurethane are as follows: 1.5-2.5 parts by weight of polytetrahydrofuran and 0.8-1.2 parts by weight of toluene diisocyanate are dissolved in 9-11 parts by weight of dimethyl sulfoxide, followed by the addition of 2-2.4 parts by weight of a 0.09-0.11 g / mL dimethyl sulfoxide solution of cyclodextrin. After mixing evenly, the mixture is reacted in a water bath at 48-52°C for 50-70 min, and then cured in an oven at 58-62°C for 28-32 min to obtain the cyclodextrin-based polyurethane.

[0014] Further, the preparation steps of the azophenyl composite polyurethane are as follows: 19-21 parts by weight of polytetrahydrofuran, 0.09-0.11 parts by weight of 4,4'-dihydroxyazobenzene, 0.18-0.22 parts by weight of modified polyaniline, and 9-11 parts by weight of dimethyl sulfoxide are stirred and mixed to obtain mixture A; 0.9-1.1 parts by weight of toluene diisocyanate and 0.018-0.022 parts by weight of dibutyltin dilaurate are poured into solution A, reacted in a water bath at 49-51°C for 55-65 min, and cured in an oven at 60°C for 28-32 min to synthesize azophenyl polyurethane.

[0015] Further, the preparation steps of the modified polyaniline are as follows: 3 parts by mass of polyaniline are dispersed in 500 parts by mass of deionized water, and then 27-33 parts by mass of cysteine ​​are added and mixed. After ultrasonic-assisted dispersion for 25-35 minutes, the mixture is magnetically stirred for 23-25 ​​hours, filtered, and washed repeatedly with deionized water and ethanol 2-4 times. Finally, it is dried at room temperature for 12 hours to obtain the modified polyaniline.

[0016] Furthermore, the self-healing method of the self-healing anti-corrosion coating is as follows: at 100mW / cm 2 Irradiate with a 405nm laser for 20–30 seconds.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects:

[0018] The self-healing anti-corrosion coating of the present invention comprises cyclodextrin-based polyurethane, azophenyl composite polyurethane, hollow mesoporous silica, and leveling agent; wherein, the cyclodextrin-based polyurethane is obtained by reacting cyclodextrin with toluene diisocyanate; the azophenyl composite polyurethane is obtained by reacting polytetrahydrofuran, 4'-dihydroxyazobenzene, modified polyaniline, and toluene diisocyanate.

[0019] Polyaniline is an excellent green corrosion inhibitor with no environmental side effects compared to conventional corrosion inhibitors. It exhibits an "activation-passivation" behavior on metallic materials, that is, it accelerates the formation of a passivation film on the metal surface through a reversible redox reaction, thereby effectively inhibiting the occurrence of corrosion reactions. Introducing polyaniline into azophenyl composite polyurethane can effectively improve the anti-corrosion performance of azophenyl composite polyurethane. However, polyaniline is prone to agglomeration in the resin matrix, which is not conducive to its uniform dispersion and will reduce the adhesion of the coating. Modifying polyaniline with cystine can effectively improve the compatibility of polyaniline in azophenyl composite polyurethane.

[0020] Secondly, an anti-corrosion coating was prepared by mixing cyclodextrin-based polyurethane, azophenyl composite polyurethane, hollow mesoporous silica, and a leveling agent. The polymer chains of the cyclodextrin-based polyurethane and azophenyl composite polyurethane penetrate into the pores of the hollow mesoporous silica, using the silica as physical cross-linking points. This increases the cross-linking density of the self-healing anti-corrosion coating, thereby enhancing its mechanical properties, wear resistance, and anti-corrosion performance. Simultaneously, the hollow mesoporous silica provides an additional physical barrier; when the coating is damaged externally, it effectively prevents the further expansion of the damaged surface and prevents corrosive media from penetrating the substrate through cracks or scratches. This extends the service life of the coating and improves its anti-corrosion effect. When exposed to light and heat, cis-azobenzene is converted into trans-azobenzene and combines with cyclodextrin, which leads to the shrinkage of the polymer chains in the coating. This causes the cyclodextrin-based polyurethane and azophenyl composite polyurethane interspersed in the hollow mesoporous silica to shrink. Using the hollow mesoporous silica as a physical fixation point, it accurately applies an inward pulling force to the polymer layers on both sides of the damaged area, causing the damaged surfaces to approach each other until they come into contact. Once in contact, the trans-azobenzene on the damaged surface will continue to react with the cyclodextrin. At the same time, azobenzene and polyaniline will convert the absorbed light energy into heat energy, activating the recombination of disulfide bonds at the damaged site, thereby completing the self-repair process. Detailed Implementation

[0021] To better understand the above technical solution, the following will provide a detailed explanation of the technical solution in conjunction with specific implementation methods.

[0022] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0023] The raw materials used in some embodiments and comparative examples of this invention are as follows:

[0024] The solvent used is dimethyl sulfoxide;

[0025] The cyclodextrin used is α-cyclodextrin;

[0026] The leveling agent used is BYK-333 from BYK Chemicals.

[0027] Polytetrahydrofuran (average relative molecular mass approximately 1000);

[0028] Polyaniline: average relative molecular mass approximately 15,000.

[0029] The preparation steps of hollow mesoporous silica are as follows: Add 0.2 parts by mass of hexadecyltrimethylammonium bromide to 200 parts by mass of a mixed solution with an alcohol-to-water ratio of 4–9:1, and dropwise add 2 mol / L NaOH solution until the pH reaches 9. Then add 2 parts by mass of paraffin wax, and emulsify at a high speed of 5000 r / min for 5 min using a homogenizer. Next, add 2 parts by mass of tetraethyl orthosilicate. React at 80℃ and 400 r / min for 2 h with stirring. After the reaction, filter the product, wash 2–4 times with deionized water and anhydrous ethanol, dry, and calcine at 600℃ for 3 h to remove the liquid paraffin template agent and surfactant, obtaining hollow mesoporous silica with a specific surface area of ​​802.7263 m². 2 / g, pore volume is 0.89cm³ 3 / g, with an average pore size of 4.19nm.

[0030] (Example 1)

[0031] A method for preparing a self-healing anti-corrosion coating includes the following preparation steps:

[0032] 1.5 parts by weight of cyclodextrin-based polyurethane and 1.5 parts by weight of azophenyl composite polyurethane were dissolved in 7.5 parts by weight of dimethyl sulfoxide solvent. Then, 0.15 parts by weight of hollow mesoporous silica were added and dispersed at 2000 rpm for 25 min. Next, 0.15 parts by weight of leveling agent were added and dispersion was continued for 4 min. The mixture was then treated with 365 nm UV for 10 min and dried in an oven at 58 °C for 28 min to obtain a self-healing anti-corrosion coating.

[0033] The preparation steps of the cyclodextrin-based polyurethane are as follows: 1.5 parts by mass of polytetrahydrofuran and 0.8 parts by mass of toluene diisocyanate are dissolved in 9 parts by mass of dimethyl sulfoxide, and then 2 parts by mass of a 0.09 g / mL cyclodextrin dimethyl sulfoxide solution are added. After mixing evenly, the mixture is reacted in a water bath at 48°C for 50 min, and then cured in an oven at 58°C for 28 min to obtain the cyclodextrin-based polyurethane.

[0034] The preparation steps of the azophenyl composite polyurethane are as follows: 19 parts by mass of polytetrahydrofuran, 0.09 parts by mass of 4,4'-dihydroxyazobenzene, 0.18 parts by mass of modified polyaniline, and 9 parts by mass of dimethyl sulfoxide are stirred and mixed to obtain mixture A; 0.9 parts by mass of toluene diisocyanate and 0.018 parts by mass of dibutyltin dilaurate are poured into solution A, reacted in a water bath at 49°C for 55 min, and cured in an oven at 60°C for 28 min to synthesize azophenyl polyurethane.

[0035] The preparation steps of the modified polyaniline are as follows: 3 parts by mass of polyaniline are dispersed in 500 parts by mass of deionized water, and then 27 parts by mass of cysteine ​​are added and mixed. After ultrasonic-assisted dispersion for 25 minutes, the mixture is magnetically stirred for 23 hours, filtered, and washed twice with deionized water and ethanol. Finally, it is dried at room temperature for 12 hours to obtain the modified polyaniline.

[0036] (Example 2)

[0037] A method for preparing a self-healing anti-corrosion coating includes the following preparation steps:

[0038] Two parts by mass of cyclodextrin-based polyurethane and two parts by mass of azophenyl composite polyurethane were dissolved in 10 parts by mass of dimethyl sulfoxide. Then, 0.2 parts by mass of hollow mesoporous silica were added and dispersed at 3000 rpm for 30 min. Next, 0.2 parts by mass of leveling agent were added and dispersion was continued for 5 min. The mixture was then treated with 365 nm UV for 15 min and dried in an oven at 60 °C for 30 min to obtain a self-healing anti-corrosion coating.

[0039] The preparation steps of the cyclodextrin-based polyurethane are as follows: 2 parts by mass of polytetrahydrofuran and 1 part by mass of toluene diisocyanate are dissolved in 10 parts by mass of dimethyl sulfoxide, and then 2.2 parts by mass of a 0.1 g / mL cyclodextrin dimethyl sulfoxide solution are added. After mixing evenly, the mixture is reacted in a water bath at 50°C for 60 min, and then cured in an oven at 60°C for 30 min to obtain the cyclodextrin-based polyurethane.

[0040] The preparation steps of the azophenyl composite polyurethane are as follows: 20 parts by mass of polytetrahydrofuran, 0.1 parts by mass of 4,4'-dihydroxyazobenzene, 0.2 parts by mass of modified polyaniline, and 10 parts by mass of dimethyl sulfoxide are stirred and mixed to obtain mixture A; 1 part by mass of toluene diisocyanate and 0.02 parts by mass of dibutyltin dilaurate are poured into solution A, reacted in a 50°C water bath for 60 min, and cured in a 60°C oven for 30 min to synthesize azophenyl polyurethane.

[0041] The preparation steps of the modified polyaniline are as follows: 3 parts by mass of polyaniline are dispersed in 500 parts by mass of deionized water, and then 30 parts by mass of cysteine ​​are added and mixed. After ultrasonic-assisted dispersion for 30 minutes, the mixture is magnetically stirred for 24 hours, filtered, and washed repeatedly with deionized water and ethanol 3 times. Finally, it is dried at room temperature for 12 hours to obtain the modified polyaniline.

[0042] (Example 3)

[0043] A method for preparing a self-healing anti-corrosion coating includes the following preparation steps:

[0044] 2.5 parts by weight of cyclodextrin-based polyurethane and 2.5 parts by weight of azophenyl composite polyurethane were dissolved in 12.5 parts by weight of dimethyl sulfoxide solvent. Then, 0.25 parts by weight of hollow mesoporous silica were added and dispersed at 4000 rpm for 35 min. Next, 0.25 parts by weight of leveling agent were added and dispersion was continued for 6 min. The mixture was then treated with 365 nm UV for 20 min and dried in an oven at 62 °C for 32 min to obtain a self-healing anti-corrosion coating.

[0045] The preparation steps of the cyclodextrin-based polyurethane are as follows: 2.5 parts by mass of polytetrahydrofuran and 1.2 parts by mass of toluene diisocyanate are dissolved in 11 parts by mass of dimethyl sulfoxide, and then 2.4 parts by mass of a 0.11 g / mL cyclodextrin dimethyl sulfoxide solution is added. After mixing evenly, the mixture is reacted in a water bath at 52°C for 70 min, and then cured in an oven at 62°C for 32 min to obtain the cyclodextrin-based polyurethane.

[0046] The preparation steps of the azophenyl composite polyurethane are as follows: 21 parts by mass of polytetrahydrofuran, 0.11 parts by mass of 4,4'-dihydroxyazobenzene, 0.22 parts by mass of modified polyaniline, and 11 parts by mass of dimethyl sulfoxide are stirred and mixed to obtain mixture A; 1.1 parts by mass of toluene diisocyanate and 0.022 parts by mass of dibutyltin dilaurate are poured into solution A, reacted in a water bath at 51°C for 65 min, and cured in an oven at 60°C for 32 min to synthesize azophenyl polyurethane.

[0047] The preparation steps of the modified polyaniline are as follows: 3 parts by mass of polyaniline are dispersed in 500 parts by mass of deionized water, and then 33 parts by mass of cysteine ​​are added and mixed. After ultrasonic-assisted dispersion for 35 minutes, the mixture is magnetically stirred for 25 hours, filtered and washed repeatedly with deionized water and ethanol 4 times, and finally dried at room temperature for 12 hours to obtain modified polyaniline.

[0048] Comparative Example 1

[0049] The difference between Comparative Example 1 and Example 2 is that the raw material components of the self-healing anti-corrosion coating in Comparative Example 1 include: cyclodextrin-based polyurethane, azophenyl composite polyurethane, and leveling agent; the remaining steps and components are the same as in Example 2.

[0050] Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 2 is that the raw material components of the self-healing anti-corrosion coating in Comparative Example 1 include: azophenyl composite polyurethane, hollow mesoporous silica, and leveling agent; the remaining steps and components are the same as in Example 2.

[0052] Comparative Example 3

[0053] The difference between Comparative Example 3 and Example 2 is that the azophenyl composite polyurethane in Comparative Example 1 was obtained by the composite reaction of polytetrahydrofuran, modified polyaniline, and toluene diisocyanate; the remaining steps and components were the same as in Example 2.

[0054] Comparative Example 4

[0055] The difference between Comparative Example 4 and Example 2 is that the azophenyl composite polyurethane in Comparative Example 1 is obtained by the composite reaction of polytetrahydrofuran, 4,4'-dihydroxyazobenzene, polyaniline, and toluene diisocyanate; the remaining steps and components are the same as in Example 2.

[0056] Comparative Example 5

[0057] The difference between Comparative Example 5 and Example 2 is that the raw material components of the self-healing anti-corrosion coating in Comparative Example 1 include: cyclodextrin-based polyurethane, azophenyl composite polyurethane, hollow mesoporous silica, leveling agent, and modified polyaniline; wherein, the azophenyl composite polyurethane is obtained by the composite reaction of 4,4'-dihydroxyazobenzene, polytetrahydrofuran, and toluene diisocyanate; the remaining steps and components are the same as in Example 2.

[0058] Comparative Example 6

[0059] The difference between Comparative Example 6 and Example 2 is that the raw material components of the self-healing anti-corrosion coating in Comparative Example 1 include: cyclodextrin-based polyurethane, azophenyl composite polyurethane, hollow mesoporous silica, leveling agent, and polyaniline; wherein, it is obtained by the composite reaction of 4,4'-dihydroxyazobenzene, polytetrahydrofuran, and toluene diisocyanate; the remaining steps and components are the same as in Example 2.

[0060] Example of results:

[0061] Tensile properties: The tensile properties of the self-healing anti-corrosion coatings prepared according to the examples and comparative examples were tested using Shimadzu's AGS-X10KN electronic universal tensile testing machine in accordance with GB / T7762.

[0062] Corrosion resistance: The self-healing anti-corrosion coatings prepared in the examples and comparative examples were uniformly coated on the surface of low carbon steel plates using a frame-type coating applicator with a gap width of 120 μm. The coatings were cured in an oven at 60 °C for 8 h to obtain a self-healing anti-corrosion coating. The salt spray resistance of the self-healing anti-corrosion coatings was tested according to GB / T1771.

[0063] Self-healing performance: The mechanical self-healing properties of the self-healing anti-corrosion coatings prepared according to the GB / T7762 test examples and comparative examples were assessed using a Shimadzu AGS-X10KN electronic universal tensile testing machine at a tensile rate of 200 mm / min. The samples were cut into dumbbell shapes with a width of 4 mm, a length of 50 mm, and a thickness of 2 mm, with a 20 mm gap between the two ends. The self-healing efficiency of the coating was evaluated by measuring the mechanical properties of the uncut coating and the cut repair coating. The self-healing efficiency (η) of the coating was calculated according to formula (1). The cut repair coating refers to the self-healing anti-corrosion coating after cutting at 100 mW / cm 2 Irradiation with a 405nm laser for 20 seconds;

[0064] η = ε healing / ε initial × 100% Equation (1)

[0065] Where: ε initial —Elongation at break of the uncut coating; ε healing —Elongation at break of the repaired coating.

[0066] Adhesion: The self-healing anti-corrosion coatings prepared in the examples and comparative examples were uniformly coated onto the surface of low carbon steel plates using a frame-type film scraper with a gap width of 120 μm. The coatings were cured in an oven at 60 °C for 8 h to obtain the self-healing anti-corrosion coating. The adhesion of the self-healing anti-corrosion coatings was tested according to GB / T9286.

[0067] Table 1 below shows the performance test results of the self-healing anti-corrosion coatings prepared in the examples and comparative examples:

[0068] Table 1

[0069]

[0070] As shown in Table 1 above, the self-healing anti-corrosion coatings prepared in Examples 1 to 3 have good tensile properties, anti-corrosion properties, self-healing properties, and adhesion.

[0071] Compared with Example 2, the self-healing anti-corrosion coating of Comparative Example 1 did not contain hollow mesoporous silica in its raw material components, and therefore could not provide physical cross-linking points for physical cross-linking. When subjected to photothermal stimulation, cis-azobenzene would be converted into trans-azobenzene and combine with cyclodextrin, which would cause the polymer chain of the coating to shrink. Without hollow mesoporous silica as a physical fixing point, it could not accurately apply inward tensile force to the polymer layers on both sides of the damaged area, causing the damaged surfaces to approach each other until they made contact. The tensile properties and self-healing properties of the coating obtained in Comparative Example 2 were better.

[0072] Compared with Example 2, Comparative Example 2's self-healing anti-corrosion coating did not contain cyclodextrin-based polyurethane in its raw material components. When exposed to photothermal stimulation, cis-azobenzene would be converted to trans-azobenzene, and the polymer chains of the coating could not shrink, resulting in poor self-healing performance.

[0073] Compared with Example 2, Comparative Example 3, which did not contain 4,4'-dihydroxyazobenzene, had poor tensile and self-healing properties because the polymer chains could not shrink when exposed to photothermal stimulation.

[0074] Compared with Example 2, Comparative Example 4 did not modify polyaniline. Polyaniline tends to agglomerate in the resin matrix, resulting in reduced adhesion, poor tensile properties, poor corrosion resistance, and poor self-healing effect. This is because the polyaniline is unevenly distributed, leading to inconsistent self-healing effects in different parts of the coating.

[0075] Compared with Example 2, Comparative Example 5 did not prepare azophenyl composite polyurethane from modified polyaniline. Instead, it was directly mixed with cyclodextrin-based polyurethane, azophenyl composite polyurethane, hollow mesoporous silica, and leveling agent to prepare the self-healing anti-corrosion coating. The coating exhibited weaker tensile properties, anti-corrosion properties, self-healing properties, and adhesion. This may be because the self-healing anti-corrosion coating prepared directly from modified polyaniline has better compatibility than the one prepared first with azophenyl composite polyurethane.

[0076] The difference between Comparative Example 6 and Comparative Example 5 is that Comparative Example 6 did not modify the polyaniline. Polyaniline is prone to agglomeration in the resin matrix, resulting in reduced adhesion, poor tensile properties, poor corrosion resistance, and poor self-healing effect. This is because the polyaniline is unevenly distributed, leading to inconsistent self-healing effects in different parts of the coating.

[0077] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-healing anti-corrosion coating, characterized in that, By weight, the raw material components include 1.5 to 2.5 parts by weight of cyclodextrin-based polyurethane, 1.5 to 2.5 parts by weight of azophenyl composite polyurethane, 0.15 to 0.25 parts by weight of hollow mesoporous silica, 0.15 to 0.25 parts by weight of leveling agent, and 7.5 to 12.5 parts by weight of solvent. The cyclodextrin-based polyurethane is obtained by reacting cyclodextrin with toluene diisocyanate; The azophenyl composite polyurethane is obtained by the composite reaction of polytetrahydrofuran, 4,4'-dihydroxyazobenzene, modified polyaniline, and toluene diisocyanate. The modified polyaniline is obtained by modifying polyaniline with cystine.

2. The method for preparing the self-healing anti-corrosion coating according to claim 1, characterized in that, The preparation steps include the following: Dissolve 1.5-2.5 parts by weight of cyclodextrin-based polyurethane and 1.5-2.5 parts by weight of azophenyl composite polyurethane in 7.5-12.5 parts by weight of dimethyl sulfoxide solvent, then add 0.15-0.25 parts by weight of hollow mesoporous silica, disperse at 2000-4000 rpm for 25-35 min, then add 0.15-0.25 parts by weight of leveling agent, continue dispersion for 4-6 min, treat with 365nm UV for 10-20 min, and then dry in an oven at 58-62℃ for 28-32 min to obtain a self-healing anti-corrosion coating.

3. The method for preparing the self-healing anti-corrosion coating according to claim 2, characterized in that, The preparation steps of the cyclodextrin-based polyurethane are as follows: 1.5-2.5 parts by weight of polytetrahydrofuran and 0.8-1.2 parts by weight of toluene diisocyanate are dissolved in 9-11 parts by weight of dimethyl sulfoxide, followed by the addition of 2-2.4 parts by weight of a 0.09-0.11 g / mL cyclodextrin dimethyl sulfoxide solution. After mixing evenly, the mixture is reacted in a water bath at 48-52°C for 50-70 min, and then cured in an oven at 58-62°C for 28-32 min to obtain the cyclodextrin-based polyurethane.

4. The method for preparing the self-healing anti-corrosion coating according to claim 2, characterized in that, The preparation steps of the azophenyl composite polyurethane are as follows: 19-21 parts by weight of polytetrahydrofuran, 0.09-0.11 parts by weight of 4,4'-dihydroxyazobenzene, 0.18-0.22 parts by weight of modified polyaniline, and 9-11 parts by weight of dimethyl sulfoxide are stirred and mixed to obtain mixture A; 0.9-1.1 parts by weight of toluene diisocyanate and 0.018-0.022 parts by weight of dibutyltin dilaurate are poured into solution A, reacted in a water bath at 49-51°C for 55-65 min, and cured in an oven at 60°C for 28-32 min to synthesize azophenyl polyurethane.

5. The method for preparing the self-healing anti-corrosion coating according to claim 4, characterized in that, The preparation steps of the modified polyaniline are as follows: 3 parts by mass of polyaniline are dispersed in 500 parts by mass of deionized water, and then 27-33 parts by mass of cysteine ​​are added and mixed. After ultrasonic-assisted dispersion for 25-35 minutes, the mixture is magnetically stirred for 23-25 ​​hours, filtered and washed repeatedly with deionized water and ethanol 2-4 times, and finally dried at room temperature for 12 hours to obtain the modified polyaniline.

6. The method for preparing the self-healing anti-corrosion coating according to any one of claims 2 to 5, characterized in that, The self-healing method of the self-healing anti-corrosion coating is as follows: at 100mW / cm 2 Irradiate with a 405nm laser for 20-30 seconds.

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