A photothermal response type anticorrosion self-repairing coating

Abstract

This invention discloses a photothermal responsive anti-corrosion self-healing coating, belonging to the field of metal corrosion protection technology. The coating is made from polymers, photothermal responsive slow-release (MPDA@BTA) microcapsules, layered modified SiO2 particles, solvents, and additives. This invention effectively solves the common contradiction between superhydrophobic properties and coating interfacial bonding strength by constructing a methyl hydrophobic layer and an epoxy hydrophilic layer on the surface of nano-SiO2, thus constructing an extremely stable physical barrier. Simultaneously, utilizing the photothermal conversion effect of the microcapsules, the shape memory effect of the polymer matrix can be activated under near-infrared light or sunlight, achieving physical closure of cracks and synergistically releasing corrosion inhibitors for chemical repair. This achieves a three-in-one protection of "passive barrier + active physical repair + intelligent chemical corrosion inhibition," significantly extending the service life of marine steel structures and other metal materials in harsh environments.

Description

Technical Field

[0001] This invention belongs to the field of metal corrosion protection technology, specifically relating to a photothermal responsive self-healing coating with a heterogeneous structure and multiple repair mechanisms. Background Technology

[0002] Metallic materials, due to their excellent mechanical, electrical, and thermal properties, play an irreplaceable role in national strategies such as marine resource development. However, the high-salt and high-humidity marine environment easily leads to corrosion failure of steel structures. While widely used polymer coatings provide physical barriers, they are prone to microcracks during service, resulting in high maintenance costs. Therefore, developing coatings with both high-efficiency barrier and self-healing functions is urgently needed. Existing self-healing mechanisms mostly focus on single thermal repair or microcapsule slow release. Thermal repair suffers from the problem of contact heating easily inducing coating aging and degradation. While photothermal responsive coatings can achieve precise non-contact repair, current research often overlooks the synergistic effect of multiple protective mechanisms. Furthermore, conventional superhydrophobic fillers, when improving barrier performance, often suffer from poor interfacial compatibility with the polymer matrix due to excessively low surface energy, easily inducing coating peeling. Summary of the Invention

[0003] To address the aforementioned bottlenecks, this invention provides a photothermal responsive anti-corrosion self-healing coating. By constructing a modified filler with a "hydrophobic core and hydrophilic shell" and combining a dual response mechanism of photothermal conversion and intelligent release of corrosion inhibitors, it achieves multiple synergistic protections of physical shielding, chemical slow release, and shape memory physical repair. This overcomes the shortcomings of insufficient barrier layer stability and single repair methods in existing technologies, and is of great significance for extending the service life of marine steel structure engineering.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A photothermal responsive anti-corrosion self-healing coating is made from polymers, photothermal responsive slow-release microcapsules, layered modified SiO2 particles, solvents and additives.

[0005] Further, based on a total mass percentage of 100%, the mass percentages of each raw material are as follows: polymer 60-85%, photothermal responsive sustained-release microcapsules 1-10%, layered modified SiO2 particles 2.5-12.5%, solvent 5-30%, and additives 1-10%; preferably, the mass percentages of each raw material are as follows: polymer 65-80%, photothermal responsive sustained-release microcapsules 1.5-5%, layered modified SiO2 particles 5-10%, solvent 10-25%, and additives 1.5-8%; more preferably, the mass percentages of each raw material are as follows: polymer 70%, photothermal responsive sustained-release microcapsules 3%, layered modified SiO2 particles 8%, solvent 15%, and additives 4%.

[0006] Furthermore, the polymer is selected from either thermosetting epoxy resin or polyurethane.

[0007] Furthermore, the photothermal responsive sustained-release (MPDA@BTA) microcapsules are formed by loading the metal corrosion inhibitor benzotriazole (BTA) onto polydopamine (MPDA) microcapsules with mesoporous structures. These microcapsules simultaneously possess pH-responsive release characteristics and photothermal conversion performance.

[0008] The preparation of the MPDA@BTA microcapsules includes the following steps: a) Dissolve triblock copolymer F127 in a mixed solution of deionized water and ethanol, and stir magnetically until completely dissolved. Then, add polydimethylsiloxane (PDMS) dropwise to obtain a nanoemulsion system. Add dopamine hydrochloride (DA) and dissolve it completely. Then, add tris(hydroxymethyl)aminomethane (Tris) buffer. Using a nanoemulsion assembly strategy, react at 30℃ and 500 r / min for 12-24 h. Then, centrifuge the reaction solution at 11000 r / min. The resulting black precipitate is washed 2-3 times with anhydrous ethanol and deionized water, and then dried at 60℃ for 12 h to obtain MPDA microcapsule particles. b) By using the vacuum-assisted loading method, MDPA microcapsule particles are mixed with the metal corrosion inhibitor benzotriazole (BTA) at a mass ratio of 1:4, and the vacuum loading is repeated 2-3 times at 25 °C and 10-15 Pa for 2 hours each time. After centrifugation, washing and drying, MPDA@BTA microcapsule powder can be obtained.

[0009] Furthermore, by weight, the amounts of each material used in step a) include: 16 parts of triblock copolymer F127, 20.6 parts of polydimethylsiloxane, 8 parts of dopamine hydrochloride, and 3 parts of tris(hydroxymethyl)aminomethane buffer.

[0010] Furthermore, in step a), the volume ratio of deionized water to ethanol in the mixed solution of deionized water and ethanol is 1:1.

[0011] Furthermore, the layered modified SiO2 particles are prepared by condensing the hydroxyl groups on the surface of nano-SiO2 with silanols generated from the hydrolysis of methyltrimethoxysilane (MTMS) to form a hydrophobic layer on the surface of nano-SiO2, and then grafting a silane coupling agent KH-560 onto the interface of the hydrophobic layer to form a hydrophilic layer. The hydrophilic layer can be covalently linked to the polymer through exposed epoxy groups.

[0012] The specific preparation steps of the layered modified SiO2 particles are as follows: MTMS, anhydrous ethanol and deionized water are mixed at a volume ratio of 1:10:1, and ammonia is added to adjust the pH to 8-9. The mixture is magnetically stirred for 30 min to obtain hydrolysate A; KH-560, anhydrous ethanol and deionized water are mixed at a volume ratio of 1:15:0.5 and stirred for 30 min to obtain hydrolysate B; dried SiO2 is dispersed in anhydrous ethanol at a material-to-liquid mass ratio of 1:80, ultrasonically treated for 30 min, and then hydrolysate A is slowly added dropwise. The mixture is stirred at 60℃ for 4 h to complete the hydrophobic layer coating. Then, the system temperature is maintained at 60℃, and hydrolysate B is added to the reaction solution. The reaction is carried out for 2 h. After centrifugation, washing and drying, the layered modified SiO2 particles are obtained. Furthermore, the particle size of the SiO2 is 300±5 nm.

[0013] Furthermore, the mass ratio of SiO2 to MTMS used is 1:1.8, and the mass ratio of MTMS to KH-560 used is 9:1.

[0014] Furthermore, the solvent is selected from one or more of polypropylene glycol diglycidyl ether, deionized water, anhydrous ethanol, and acetone.

[0015] Furthermore, the additive is selected from one or more of dispersants, curing agents, and silane coupling agents.

[0016] Furthermore, the dispersant is selected from one or more of ionic dispersants and polymeric dispersants.

[0017] Furthermore, the curing agent is D230 type polyetheramine.

[0018] Furthermore, the silane coupling agent is selected from one or more of γ-glycidoxypropyltrimethoxysilane (KH-560) and methyltrimethoxysilane (MTMS).

[0019] Furthermore, the preparation of the photothermal responsive anti-corrosion self-healing coating includes the following steps: 1) The polymer, solvent, and additives are mixed evenly by mechanical stirring to obtain a polymer solution; 2) Photothermal responsive sustained-release microcapsules and layered modified SiO2 particles are added to a polymer solution, and mechanically mixed, ultrasonically treated and vacuum degassed to promote the dispersion of the photothermal responsive sustained-release microcapsules and eliminate air bubbles in the uncured composite material to obtain an anti-corrosion self-healing coating. 3) Apply the obtained anti-corrosion self-healing coating to the surface of the metal substrate and cure it to obtain a photothermal responsive anti-corrosion self-healing coating.

[0020] Furthermore, the mixing method used in the operation preferably includes high-speed stirring, ultrasonic dispersion, and more preferably high-energy ball milling; the stirring speed is 600~1000 r / min, preferably 700~900 r / min, and more preferably 800 r / min; the stirring time is 250~350 min, preferably 280~320 min, and more preferably 300 min.

[0021] Furthermore, the ultrasonic treatment time in step 2) is 10 minutes.

[0022] Furthermore, step 2) involves vacuum degassing, which is performed in a vacuum drying oven for 10 minutes.

[0023] Furthermore, the curing process described in step 3) employs a three-stage heating process: a 50°C holding period of 2 hours (to promote particle orientation during the low viscosity stage); followed by a heating to 80°C and a holding period of 4 hours (to fix the dispersion structure through resin crosslinking); and then a heating to 120°C and a holding period of 1 hour (to completely eliminate internal stress).

[0024] Furthermore, the thickness of the formed heat-responsive anti-corrosion self-healing coating is 80~140 μm, preferably 90~130 μm, and more preferably 120 μm.

[0025] The significant advantages of this invention are: (1) The MDPA microcapsules in this invention are synthesized using a nanoemulsion assembly strategy. Their surface has a uniform mesoporous structure, which can effectively load functional molecules such as corrosion inhibitors. They also have pH response characteristics and excellent photothermal conversion performance, making them an ideal nanocontainer for corrosion protection. In this invention, BTA is loaded onto the microcapsules using a vacuum-assisted loading method and uniformly embedded in the polymer coating. When corrosion begins on the metal surface, the MPDA@BTA microcapsules will release corrosion inhibitors in response. The corrosion inhibitors are adsorbed at the metal corrosion sites and can inhibit the continued progress of the corrosion electrochemical reaction through physical or chemical action. Furthermore, under solar radiation, the shape memory effect of the thermosetting polymer coating can be activated to achieve self-closure of surface defects, further improving the self-repair effect of the coating. This reduces the corrosion protection cost of building steel structures and provides necessary technical guarantees for the long-term safety performance of offshore steel structure working platforms, etc.

[0026] (2) In this invention, the layered modified SiO2 particles are generated by hydrolyzing methyltrimethoxysilane (MTMS) under the catalysis of ammonia water. The silanol (Si-OH) generated preferentially condenses with the hydroxyl groups on the surface of nano SiO2 to form Si-O-Si bonds, and its methyl (-CH3) forms a hydrophobic layer outward. Then, the siloxane group of KH-560 is used to graft the residual hydroxyl groups on the surface of nano SiO2, and the exposed epoxy group (-CH(O)CH2) is oriented outward, thereby forming a "hydrophobic core-hydrophilic shell" structure. The core can reduce the surface energy and maintain high hydrophobicity (contact angle > 120°). The epoxy group in the shell forms a covalent bond (-COC-) with the resin, which significantly enhances the interfacial compatibility. The two work together, and the micro-nano roughness (300±5 nm SiO2) and the chemical heterostructure together satisfy the Cassie-Baxter model, which can realize a mechanically stable superhydrophobic / strong adhesion synergistic state.

[0027] (3) Addressing the shortcomings of existing superhydrophobic fillers, such as weak interfacial bonding due to low surface energy and a single repair mechanism that cannot simultaneously address physical and chemical repair, this invention constructs a layered modified nano-SiO2 filler with a "hydrophobic core-hydrophilic shell" structure. This utilizes the highly hydrophobic methyl layer formed on the surface of SiO2 particles and the epoxy hydrophilic layer formed on the outside that can covalently condense with the polymer matrix, thus fundamentally resolving the contradiction between barrier properties and compatibility. Simultaneously, by embedding MPDA@BTA microcapsules with photothermal conversion function into the matrix, a three-in-one protection mechanism of "passive superhydrophobic barrier, active photothermal physical repair, and intelligent chemical corrosion inhibition" is achieved. Under near-infrared light or solar radiation, the coating can utilize the photothermal conversion effect of microcapsules to induce the shape memory effect of the polymer matrix, thereby achieving self-closing physical repair of defects on the coating surface. When corrosion occurs on the metal surface, the microcapsules release corrosion inhibitors in response to pH values, thereby inhibiting electrochemical reactions through physical or chemical adsorption and achieving chemical repair. This provides efficient and long-lasting corrosion protection for offshore steel structures, significantly improving the safety and service life of metal components.

[0028] (4) This invention resolves the interfacial contradiction between superhydrophobic properties and coating adhesion by constructing a modified layer of "hydrophobic core-hydrophilic shell" on the surface of nanofillers. Furthermore, it utilizes the coupling technology of photothermal conversion effect and intelligent corrosion inhibitor release to achieve deep synergy between active physical barrier repair and passive chemical inhibition protection. This coating is particularly suitable for the protection of marine engineering steel structures under high salt, high humidity, and complex lighting conditions, such as offshore drilling platforms, oil storage platforms, and offshore buildings, and can significantly improve the durability and safety performance of metal components under harsh service environments. Attached Figure Description

[0029] Figure 1The contact angle test results are for the anti-corrosion self-healing coatings prepared in Comparative Examples 1-3 (a-c) and Example (d).

[0030] Figure 2 The adhesion test results are for the anti-corrosion self-healing coatings prepared in Comparative Examples 1-3 (a-c) and Example (d).

[0031] Figure 3 Impedance spectra of the anti-corrosion self-healing coatings prepared in Comparative Examples 1-3 (a-c) and Example (d) after 28 days of salt spray testing.

[0032] Figure 4 The image shows a sample of the anti-corrosion self-healing coating prepared in Comparative Example 4(a) and Example (b). Detailed Implementation

[0033] A photothermal responsive anti-corrosion self-healing coating is prepared by the following steps: 1) The polymer, solvent, and additives are mixed evenly by mechanical stirring to obtain a polymer solution; 2) Photothermal responsive sustained-release microcapsules and layered modified SiO2 particles were added to a polymer solution, mechanically mixed, ultrasonically treated for 10 min, and vacuum degassed for 10 min to obtain an anti-corrosion self-healing coating. 3) Apply the obtained anti-corrosion self-healing coating to the surface of the metal substrate, first heat treatment at 50℃ for 2 hours, then heat to 80℃ for 4 hours, then heat to 120℃ for 1 hour to obtain a photothermal responsive anti-corrosion self-healing coating.

[0034] Based on a total mass percentage of 100%, the mass percentages of each raw material are as follows: polymer 60-85%, photothermal responsive sustained-release microcapsules 1-10%, layered modified SiO2 particles 2.5-12.5%, solvent 5-30%, and additives 1-10%.

[0035] The polymer is selected from either thermosetting epoxy resin or polyurethane.

[0036] The preparation of the photothermal responsive sustained-release (MPDA@BTA) microcapsules includes the following steps: a) Dissolve 16 parts by weight of triblock copolymer F127 in a mixed solution of 200 parts of deionized water and ethanol (1:1, v / v), and stir magnetically until completely dissolved. Then add 20.6 parts of polydimethylsiloxane (PDMS) dropwise to obtain a nanoemulsion system. Add 8 parts of dopamine hydrochloride (DA) and dissolve it completely. Then add 3 parts of tris(hydroxymethyl)aminomethane (Tris) buffer and react at 30°C and 500 r / min for 12-24 h. After that, centrifuge the reaction solution at 11000 r / min. The resulting black precipitate is washed 2-3 times with anhydrous ethanol and deionized water, and then dried at 60°C for 12 h to obtain polydopamine (MPDA) microcapsule particles. b) The obtained MDPA microcapsule particles were mixed with benzotriazole (BTA) at a mass ratio of 1:4, and then subjected to vacuum loading 2-3 times at 25 °C and 10-15 Pa for 2 hours each time. After centrifugation, washing and drying, MPDA@BTA microcapsule powder was obtained.

[0037] The method for preparing the layered modified SiO2 particles is as follows: First, SiO2 powder of 300±5 nm is vacuum dried at 120℃ for 2 hours to remove physically adsorbed water and set aside. Then, methyltrimethoxysilane (MTMS), anhydrous ethanol, and deionized water are mixed at a volume ratio of 1:10:1, and ammonia is added to adjust the pH to 8-9. The mixture is magnetically stirred for 30 minutes to obtain hydrolysate A. Silane coupling agent KH-560, anhydrous ethanol, and deionized water are mixed at a volume ratio of 1:15:0.5 and stirred for 30 minutes to obtain hydrolysate B. The dried SiO2 is dispersed in anhydrous ethanol at a mass ratio of 1:80 and ultrasonically treated for 30 minutes. Then, hydrolysate A is slowly added dropwise at a mass ratio of SiO2 to MTMS of 1:1.8. The mixture is stirred at 60℃ for 4 hours. Afterward, the system temperature is maintained at 60℃, and hydrolysate B is added to the reaction solution at a mass ratio of MTMS to KH-560 of 9:1. The reaction is continued for 2 hours. h, after centrifugation, washing and drying, layered modified SiO2 particles can be obtained; The solvent is selected from one or more of polypropylene glycol diglycidyl ether, deionized water, anhydrous ethanol, and acetone.

[0038] The additives are selected from one or more of dispersants, curing agents, and silane coupling agents.

[0039] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0040] The thermosetting epoxy resin used in the following examples is bisphenol A type epoxy resin (E44) produced by Dongguan Hongcheng Polymer Materials Co., Ltd.; the polyurethane used is acrylic polyurethane produced by Nantong Xingchen Synthetic Materials Co., Ltd.; the polypropylene glycol diglycidyl ether used is purchased from Shanghai Maclean Biotechnology Co., Ltd.; the anhydrous ethanol used is purchased from Xilong Scientific Co., Ltd.; the dispersant used is AMORSO-526B type polymeric dispersant produced by Kunshan Jiyan Chemical Materials Co., Ltd.; the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (F127), polydimethylsiloxane (PDMS), dopamine hydrochloride (DA), tris(hydroxymethyl)aminomethane (Tris), nano silica (300±5 nm), benzotriazole (BTA) and other materials used are all purchased from Shanghai Maclean Biotechnology Co., Ltd. Example

[0041] Step 1: Preparation of MPDA@BTA microcapsules. 1.6 g of triblock copolymer F127 was dissolved in 200 mL of a mixture of deionized water and ethanol (1:1, v / v), and magnetically stirred until completely dissolved. Then, 2 mL of PDMS was added dropwise, and the mixture was magnetically stirred at 500 r / min for 10 min at room temperature to form a homogeneous nanoemulsion system. Next, 0.8 g of DA and 0.3 g of Tris were added sequentially, and the mixture was stirred continuously at 30 ℃ and 500 r / min for 24 h. The reaction solution was then centrifuged at 11000 r / min, and the resulting black precipitate was washed three times each with deionized water and anhydrous ethanol. Finally, it was dried in an oven at 60 ℃ for 12 h to obtain MPDA microcapsule powder. Then, the obtained MPDA microcapsule powder and BTA were dissolved in 100 mL of anhydrous ethanol at a mass ratio of 1:4, and treated with ultrasound for 30 min to ensure uniform dispersion of the microcapsules and corrosion inhibitor. The mixed solution was then placed in a vacuum drying oven at 25 ℃ for 2... Vacuum-assisted loading was performed, and this process was repeated three times to ensure sufficient BTA loading. The resulting precipitate was then filtered and washed three times with anhydrous ethanol and deionized water to remove unloaded excess material. Finally, it was dried in an electrically heated drying oven for 24 hours to obtain blackish-gray MPDA@BTA microcapsules.

[0042] Step 2: Preparation of layered modified SiO2. Pre-dried SiO2 (300±5 nm) was dispersed in anhydrous ethanol at a mass ratio of 1:80 and sonicated for 30 min to form a uniform suspension. Then, MTMS, anhydrous ethanol, and deionized water were mixed at a volume ratio of 1:10:1, and ammonia was added to adjust the pH to ~9. The mixture was magnetically stirred for 30 min to ensure complete hydrolysis, yielding hydrolysate A. KH-560, anhydrous ethanol, and deionized water were mixed at a volume ratio of 1:15:0.5 and stirred for 30 min to obtain hydrolysate B. Subsequently, hydrolysate A was slowly added dropwise to the SiO2 suspension at a SiO2 to MTMS mass ratio of 1:1.8. The mixture was continuously stirred under sealed conditions at 60℃ to promote partial condensation and grafting of the functional groups of MTMS with the hydroxyl groups on the SiO2 surface. After stirring for 4 h, hydrolysate B was added to the reaction solution at a MTMS to KH-560 mass ratio of 9:1, and stirring was continued for 2 h. After the reaction was completed, the mixture was centrifuged at 8000 r / min for 10 min to obtain the reaction precipitate. The precipitate was washed three times with anhydrous ethanol and deionized water to remove unreacted residues. Finally, it was vacuum dried at 80℃ for 12 h to obtain layered modified nano-SiO2 particles.

[0043] Step 3: Preparation of anti-corrosion self-healing coating. First, according to the weight parts, 6.14 parts of thermosetting epoxy resin, 1.54 parts of polypropylene glycol diglycidyl ether, and 2.30 parts of D230 are subjected to high-speed mechanical stirring to obtain a mixed solution. Then, 3.4 parts of MPDA@BTA, 10.2 parts of layered modified SiO2, and 0.5 parts of dispersant are added to the mixed solution in sequence. The mixture is then ball-milled at 800 r / min for 300 min, ultrasonically treated for 10 min, and then placed in a vacuum drying oven for degassing for 10 min to obtain the anti-corrosion self-healing coating.

[0044] Step 4: Preparation of the anti-corrosion self-healing coating. Using a coating applicator, the above-mentioned anti-corrosion self-healing coating is applied to the surface of a metal substrate. The coating is prepared with a thickness of 120 μm according to the following curing procedure: initial curing: 50℃ / 2h; intermediate curing: 80℃ / 4h; final curing: 120℃ / 1h.

[0045] Comparative Example 1 Following the steps described in the examples, an anti-corrosion self-healing coating without layered modified SiO2 was prepared.

[0046] Comparative Example 2 The steps are the same as in the implementation example.

[0047] Step 2: Preparation of hydrophilic modified SiO2. Pre-dried SiO2 (300±5 nm) was dispersed in anhydrous ethanol at a mass ratio of 1:80 and sonicated for 30 min to form a uniform suspension. KH-560, anhydrous ethanol, and deionized water were mixed at a volume ratio of 1:15:0.5 and stirred for 30 min to obtain a hydrolysate. Subsequently, the hydrolysate was slowly added dropwise to the SiO2 suspension at a SiO2 to KH-560 mass ratio of 1:0.2, and stirred continuously for 6 h under sealed conditions at 60℃. After the reaction was completed, the mixture was centrifuged at 8000 r / min for 10 min to obtain the reaction precipitate, which was washed three times with anhydrous ethanol and deionized water to remove unreacted residues. Finally, it was vacuum dried at 80℃ for 12 h to obtain hydrophilic modified nano-SiO2 particles.

[0048] Steps three and four are the same as in the embodiment, and a corrosion-resistant self-healing coating containing hydrophilic modified SiO2 is obtained.

[0049] Comparative Example 3 The steps are the same as in the implementation example.

[0050] Step 2: Preparation of hydrophobically modified SiO2. Pre-dried SiO2 (300±5 nm) was dispersed in anhydrous ethanol at a mass ratio of 1:80 and sonicated for 30 min to form a uniform suspension. MTMS, anhydrous ethanol, and deionized water were mixed at a volume ratio of 1:10:1, and ammonia was added to adjust the pH to ~9. The mixture was magnetically stirred for 30 min to ensure complete hydrolysis, yielding a hydrolysate. Subsequently, hydrolysate A was slowly added dropwise to the SiO2 suspension at a SiO2 to MTMS mass ratio of 1:1.8, and the mixture was continuously stirred at 60℃ under sealed conditions for 6 h. After the reaction, the mixture was centrifuged at 8000 r / min for 10 min to obtain the reaction precipitate. This precipitate was washed three times with anhydrous ethanol and deionized water to remove unreacted residues. Finally, it was vacuum dried at 80℃ for 12 h to obtain hydrophobically modified nano-SiO2 particles.

[0051] Step 3: Preparation of the anti-corrosion self-healing coating. First, according to the weight parts, 6.14 parts of thermosetting epoxy resin, 1.54 parts of polypropylene glycol diglycidyl ether, and 2.30 parts of D230 are subjected to high-speed mechanical stirring to obtain a mixed solution. Then, 3.4 parts of MPDA@BTA, 9.5 parts of hydrophobically modified SiO2, 0.7 parts of KH-560, and 0.5 parts of dispersant are added to the mixed solution in sequence. The mixture is then ball-milled at 800 r / min for 300 min, ultrasonically treated for 10 min, and then placed in a vacuum drying oven for degassing for 10 min to obtain the anti-corrosion self-healing coating.

[0052] Step four is the same as in the embodiment, to obtain a corrosion-resistant self-healing coating containing hydrophobically modified SiO2.

[0053] The anti-corrosion self-healing coatings prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to contact angle tests, and the results are shown in the figure. Figure 1 .Depend on Figure 1 It is clearly evident that the contact angle of the anti-corrosion self-healing coating without layered modified SiO2 is only 28.714°, indicating that liquids spread very easily on the coating surface, exhibiting typical hydrophilic properties. In contrast, the contact angles of the anti-corrosion self-healing coatings containing hydrophilic modified SiO2 and hydrophobic modified SiO2 are 60.912° and 97.613°, respectively. Furthermore, the self-healing anti-corrosion coating containing layered modified SiO2 prepared in the examples achieves a contact angle of 124.1°, indicating a lower surface energy and a significant repulsive effect on droplets, demonstrating superior hydrophobic properties.

[0054] The adhesion of the anti-corrosion self-healing coatings prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in the figure. Figure 2 .like Figure 2 As shown, the adhesion of the anti-corrosion self-healing coating without layered modified SiO2 is only 7 MPa, while the adhesion of the anti-corrosion self-healing coating containing hydrophilic modified SiO2 is increased to 10 MPa. This is mainly attributed to the epoxy groups endowed on the SiO2 particles, which can strengthen the interfacial bonding with the epoxy substrate, thereby improving adhesion. In contrast, the adhesion of the anti-corrosion self-healing coating containing hydrophobic modified SiO2 is 7.4 MPa, while the adhesion of the self-healing anti-corrosion coating containing layered modified SiO2 is as high as 10.8 MPa, indicating that layered modified SiO2 particles can not only endow the coating with excellent hydrophobic properties, but also effectively improve the interfacial bonding strength of the coating.

[0055] The anti-corrosion self-healing coatings prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to electrochemical impedance spectroscopy (EIS) testing in 3.5% NaCl solution for 28 days. A three-electrode system was used: a steel sheet with the anti-corrosion self-healing coating was used as the working electrode (effective exposed area 1 cm²), a saturated calomel electrode (SCE) as the reference electrode, and a platinum sheet as the counter electrode. Impedance spectroscopy measurements were performed in the frequency range of 0.01 Hz to 100 kHz at a temperature of 30 ± 2 °C. All coating samples were subjected to 180 s near-infrared spectroscopy (NIR, 0.5 W / cm²). 2 Irradiation was applied to stimulate the shape memory healing properties of the epoxy coating. Test results are shown in Table 1 and... Figure 3 As shown.

[0056] Table 1

[0057] From Table 1 and Figure 3As can be seen, the impedance modulus of the anti-corrosion self-healing coating without layered modified SiO2 continuously decreased throughout the immersion period, indicating that the coating's anti-corrosion ability was weak and the metal matrix had already undergone severe corrosion (a). Although the anti-corrosion self-healing coatings containing hydrophilic modified SiO2 or hydrophobic modified SiO2 showed some improvement in anti-corrosion self-healing performance, their low-frequency impedance modulus was only around 10. 5 Orders of magnitude (b, c). In contrast, the anti-corrosion self-healing coating containing layered modified SiO2 prepared in the examples showed a continuous increase in impedance modulus during the initial immersion period, reaching its maximum value on day 7, at which point the low-frequency impedance modulus |Z| 0.01Hz It is 1.13 × 10 8 Ω·cm 2 The low-frequency impedance modulus of the anti-corrosion self-healing coating without layered modified SiO2 is 3.1 × 10⁻⁶. 4 Ω·cm 2 The self-healing ability of the coating was improved by four orders of magnitude, which also highlights that the addition of layered modified SiO2 particles significantly improved the performance of the self-healing anti-corrosion coating.

[0058] Comparative Example 4 Steps one through three are the same as in the example.

[0059] Step 4: Preparation of the anti-corrosion self-healing coating. The above-mentioned anti-corrosion self-healing coating is applied to the surface of the metal substrate using a coating applicator and cured at 120℃ for 12 hours to prepare a 120 μm thick anti-corrosion self-healing coating.

[0060] Figure 4 The figures show sample images of the anti-corrosion self-healing coatings prepared in Examples 1 and 2 (Comparative Example 4). As can be seen from the figures, the coating surface prepared by direct high-temperature curing exhibits a "skin-like" phenomenon, causing defects in the coating's appearance. In contrast, the coating surface prepared by three-stage heating and curing is smoother.

[0061] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A photothermal responsive anti-corrosion self-healing coating, characterized in that: Based on a total mass percentage of 100%, the raw materials used and their respective mass percentages are as follows: polymer 60-85%, photothermal responsive sustained-release microcapsules 1-10%, layered modified SiO2 particles 2.5-12.5%, solvent 5-30%, and additives 1-10%.

2. The photothermal responsive anti-corrosion self-healing coating according to claim 1, characterized in that: The polymer is selected from either thermosetting epoxy resin or polyurethane.

3. The photothermal responsive anti-corrosion self-healing coating according to claim 1, characterized in that: The photothermal responsive sustained-release microcapsules are formed by loading the metal corrosion inhibitor benzotriazole onto polydopamine microcapsules with a mesoporous structure.

4. The photothermal responsive anti-corrosion self-healing coating according to claim 3, characterized in that: The mass ratio of polydopamine microcapsules with mesoporous structure to benzotriazole is 1:

4.

5. The photothermal responsive anti-corrosion self-healing coating according to claim 1, characterized in that: The layered modified SiO2 particles are prepared by condensing the hydroxyl groups on the surface of nano-SiO2 with silanol generated by the hydrolysis of methyltrimethoxysilane to form a hydrophobic layer on the surface of nano-SiO2, and then grafting silane coupling agent KH-560 onto the interface of the hydrophobic layer to form a hydrophilic layer.

6. The photothermal responsive anti-corrosion self-healing coating according to claim 1, characterized in that: The solvent is selected from one or more of polypropylene glycol diglycidyl ether, deionized water, anhydrous ethanol, and acetone.

7. The photothermal responsive anti-corrosion self-healing coating according to claim 1, characterized in that: The additives are selected from one or more of dispersants, curing agents, and silane coupling agents.

8. The photothermal responsive anti-corrosion self-healing coating according to any one of claims 1-7, characterized in that: Its preparation method includes the following steps: 1) The polymer, solvent, and additives are mixed evenly by mechanical stirring to obtain a polymer solution; 2) Photothermal responsive slow-release microcapsules and layered modified SiO2 particles are added to a polymer solution, and after mechanical mixing, ultrasonic treatment and vacuum degassing, an anti-corrosion self-healing coating is obtained. 3) Apply the obtained anti-corrosion self-healing coating to the surface of the metal substrate and cure it to obtain a photothermal responsive anti-corrosion self-healing coating.

9. The thermally responsive anti-corrosion self-healing coating according to claim 8, characterized in that: Step 3) The curing process adopts a three-stage heating process: heat treatment at 50°C for 2 hours, then heat treatment at 80°C for 4 hours, and then heat treatment at 120°C for 1 hour.

10. The thermally responsive anti-corrosion self-healing coating according to claim 8, characterized in that: The thickness of the resulting heat-responsive anti-corrosion self-healing coating is 80~140 μm.

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