Preparation Method and Application of a Self-Healing Anticorrosion Coating with Photothermal-Responsive Nanocontainers

Abstract

The present invention provides a preparation method of a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer, which dissolves the ionic liquid [Hmim][C 12 H 25 SO4] in a polyvinyl alcohol solution, then mixes it with a dichloromethane solution of polycaprolactone, stirs and reacts, separates the solid and liquid, and obtains PCL@IL microspheres; immerses the PCL@IL microspheres in a Tris-HCl solution of dopamine, and stirs and reacts at 30-40 °C for 10-14 h to obtain PDA / PCL@IL microspheres; uniformly disperses the PDA / PCL@IL microspheres in acetone, then adds bisphenol A diglycidyl ether and neopentyl glycol diglycidyl ether, mixes evenly, removes acetone by rotary evaporation, adds a curing agent, disperses evenly, coats it on the surface of a magnesium alloy, and cures it to obtain the coating. This coating not only greatly improves the corrosion resistance of the magnesium alloy, but also endows the coating with a self-healing function at the same time. Once the coating is eroded, the photothermal effect of the polydopamine deposited on the surface of the polycaprolactone microspheres can be excited by light, converting the light into heat to realize the self-healing function of the coating.

Description

Technical Field

[0001] The present invention belongs to the technical fields of chemical engineering materials and metal corrosion prevention, and particularly relates to a preparation method and application of a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer. Background Art

[0002] Magnesium alloys are currently the lightest engineering materials and are widely used in the automotive, electronic communication, and aerospace industries due to their high specific strength and stiffness, excellent damping, and electromagnetic shielding properties. Unfortunately, the low standard electrode potential and porous oxide film of magnesium alloys usually result in poor corrosion resistance and cannot meet the requirements of different application scenarios. Compared with traditional anti-corrosion coating technologies such as chemical conversion coatings, micro-arc oxidation coatings, electrochemical polymerization, and alloys, organic coatings have excellent anti-corrosion performance and good interfacial adhesion. However, an inevitable drawback is that the evaporation of solvents during the curing process can generate a large number of micropores in pure organic coatings, such as the widely used epoxy resin (EP) coatings, allowing corrosive ions and water to penetrate the interface between the metal and the coating. Therefore, suitable fillers must be added to the EP coating to extend or prevent the electrolytic diffusion path.

[0003] Coating protection, as a physical shield, can effectively inhibit the occurrence of corrosion phenomena on the surface of the metal matrix, and it is one of the most effective means of metal corrosion prevention. However, the coating will inevitably be damaged and cracked during the anti-corrosion process, resulting in a decline in anti-corrosion performance. Therefore, it is necessary to develop intelligent coatings with the function of self-repairing damage. Self-healing coatings can be stimulated by external stimuli such as light, electricity, heat, and magnetism to promote the melting of the coating in the damaged area to heal the damaged interface. This method can repair surface damage of a relatively large size and is beneficial to restoring the physical and chemical properties and shielding effect of the coating itself. In recent years, new self-healing coatings that generate heat through light irradiation have received extensive attention from scholars. Photothermal-triggered self-healing has the following remarkable advantages: (1) It can be remotely activated and heal the damaged area without damage; (2) It is highly controllable and can be turned on / off immediately; (3) Light can be focused on the selected area without obvious interference to the intact coating; (4) Compared with traditional heating and chemical stimuli that require a long time, the healing process triggered by photothermal is extremely fast (usually within a few minutes). Therefore, the method of generating heat through light irradiation has great research value and economic benefits in the research and development of coatings. Polydopamine (PDA) has excellent light-heat generation performance, and polydopamine also has advantages such as a high melting point, good chemical stability, and corrosion resistance. Therefore, the development of photothermal self-healing coatings based on polydopamine has broad application prospects.

[0004] Ionic liquids (ILs) are liquids composed entirely of ions, which are organic salts in liquid state at room temperature consisting of organic cations and inorganic or organic anions, and are usually referred to as room temperature ionic liquids. As a new type of polar solvent, ionic liquids have almost no vapor pressure, are non-flammable, non-volatile, have good chemical stability and thermal stability, can be recycled and are environmentally friendly, so they are called "green" chemical solvents and can be used to replace traditional volatile and toxic solvents, and have been widely used in the corrosion protection of metals.

[0005] Polycaprolactone (PCL) is one of the most commonly used thermoplastic reagents at present and has a reversible plasticization mechanism. Some studies use PCL fibers or microspheres as therapeutic agents because of their overall effectiveness, availability and low cost. In addition, PCL microspheres may be used as carriers and were first demonstrated in the pharmaceutical field, mainly applied to drug delivery systems, and recently in the field of self-healing coatings, as carriers of corrosion inhibitors, providing them with additional self-healing capabilities.

[0006] At present, the developed protective coatings generally only have anti-corrosion functions, and only a very small number of coatings have other functions such as self-healing. Generally speaking, self-healing anti-corrosion coatings with excellent performance and diverse functions are extremely scarce. Therefore, adding special materials (such as PDA / PCL@IL microspheres) to epoxy coatings to improve the overall performance of magnesium alloys and endow magnesium alloys with other new functions is bound to be one of the important directions for the development of self-healing anti-corrosion coatings in the future. Summary of the Invention

[0007] Based on this, in view of the technical problem of how to improve the corrosion protection function of magnesium alloys, the present invention provides a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer (also called EP / PDA / PCL@IL self-healing anti-corrosion coating), which can not only greatly improve the corrosion resistance of magnesium alloys, but also has a new function of photothermal self-healing.

[0008] Another object of the present invention is to provide a preparation method of the above self-healing anti-corrosion coating with a photothermal-responsive nanocontainer and its application in photothermal self-healing of metal corrosion.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A preparation method of a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer, which comprises the following steps:

[0011] 1) Preparation of PCL@IL microspheres

[0012] PCL@IL microspheres were prepared by the double emulsion (W1 / O / W2) solvent evaporation method. Specifically: the ionic liquid [Hmim][C 12 H25 [Hmim][C H 25 SO4] was dissolved in a polyvinyl alcohol (PVA) solution, and then mixed with a dichloromethane solution of polycaprolactone (PCL). The mixture was stirred and reacted for 10 - 14 h, and then solid - liquid separation was carried out to obtain PCL@IL microspheres;

[0013] 2) Preparation of PDA / PCL@IL microspheres

[0014] The PCL@IL microspheres were immersed in a Tris - HCl solution of dopamine (PDA) and stirred and reacted at 30 - 40 °C for 10 - 14 h. Solid - liquid separation was carried out to obtain PDA / PCL@IL microspheres;

[0015] 3) Preparation of EP / PDA / PCL@IL composite coating

[0016] The PDA / PCL@IL microspheres were uniformly dispersed in acetone by ultrasonic treatment, and then bisphenol A diglycidyl ether (DGEBA) and neopentyl glycol diglycidyl ether (NGDE) were added. After mixing evenly, acetone was removed by rotary evaporation. A curing agent was added and dispersed evenly, and then coated on the surface of the magnesium alloy and cured to obtain a self - healing anti - corrosion coating with a photothermal - responsive nanocontainer.

[0017] Specifically, in step 1), the mass ratio of the polycaprolactone to the ionic liquid [Hmim][C 12 H 25 SO4] can be (0.4 - 0.6) : (0.04 - 0.06), and is further preferably (9 - 12):1.

[0018] Specifically, in step 2), the mass ratio of the dopamine to the PCL@IL microspheres is (0.1 - 0.3) : (0.05 - 0.15).

[0019] Furthermore, in step 2), the concentration of the Tris - HCl solution of dopamine is (1.5 - 2.5) g / L.

[0020] Specifically, in step 3), the mass ratio of the bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, and the curing agent is (1.5 - 2) : (0.9 - 1.1) : (1.1 - 1.2).

[0021] Furthermore, in step 3), the addition amount of the PDA / PCL@IL microspheres is 5% - 15% of the total mass of the bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, and the curing agent. In step 3), the curing agent is polyetheramine curing agent D230, and it is cured at a temperature of 45 - 55 °C for 12 - 24 h. When preparing the epoxy resin, bisphenol A diglycidyl ether DGEBA, neopentyl glycol diglycidyl ether NGDE, etc. are selected.

[0022] The present invention provides a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer prepared by the above preparation method.

[0023] The present invention also provides an application of the above self-healing anti-corrosion coating with a photothermal-responsive nanocontainer in the photothermal self-healing of metal corrosion, especially in the photothermal self-healing of magnesium alloy corrosion.

[0024] When applied to a magnesium alloy, the magnesium alloy needs to be pretreated, including but not limited to grinding, cleaning, drying, etc.

[0025] For the above application, specifically, a near-infrared laser with a power of 1-2 W / cm 2 can be used to irradiate the damaged area of the coating, and the coating gradually melts and heals the damaged interface within 4-6 minutes.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides a preparation method of polycaprolactone encapsulated ionic liquid (PCL@IL), and also provides a preparation method of polydopamine deposited on the surface of polycaprolactone encapsulated ionic liquid microspheres (PDA / PCL@IL). The obtained PDA / PCL@IL is added to the coating as a filler to obtain a self-healing coating with photothermal response. The self-healing anti-corrosion coating prepared by the method provided by the present invention not only greatly improves the corrosion resistance of magnesium alloy, but also endows the coating with a self-healing function. Once the coating is eroded, the photothermal effect of polydopamine deposited on the surface of polycaprolactone microspheres can be excited by light, converting light into heat, accelerating the release of ionic liquid and the melting of polycaprolactone microspheres to quickly repair the damaged area of the coating, realizing the self-healing function of the coating. The preparation method provided by the present invention is simple, and the prepared self-healing anti-corrosion coating not only has a self-healing function with photothermal response, but also has excellent anti-corrosion performance.

[0028] The treatment method of the self-healing anti-corrosion coating with a photothermal-responsive nanocontainer prepared by the present invention is simple and easy to operate. The surface of the prepared coating is uniform and flat, with good photothermal self-repair performance, and has a low corrosion current density (the corrosion current density of the composite coating of the present invention is 6.14×10 –10 A / cm 2 , compared with the corrosion current density of AZ31B magnesium alloy of 1.102×10 –5 A / cm 2 , it is reduced by 5 orders of magnitude), which can greatly improve the long-term corrosion resistance of magnesium alloy. After irradiating the scratch with near-infrared light for 5 minutes, the coating at the scratch has self-healed. After salt spray for 30 days in a 5.0 wt.% NaCl solution, the surface of the coating remains intact and there is no corrosion on the surface of the coating, indicating that the coating has excellent corrosion protection. Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the PDA / PCL@IL microspheres of the present invention;

[0030] Figure 2 It is the SEM surface morphology diagrams of PCL (a), PCL@IL microspheres (c), and PDA / PCL@IL microspheres (e) in Example 1, and the EDS spectra diagrams of PCL (b), PCL@IL microspheres (d), and PDA / PCL@IL microspheres (f);

[0031] Figure 3 It is the SEM diagrams of different coatings prepared on the surface of AZ31B magnesium alloy: (a) is the EP coating, (b) is the C, N, O element diagram and the EDS spectrum diagram of the EP coating, (c) is the EP / PDA / PCL@IL composite coating, and (d) is the C, N, O element diagram and the EDS spectrum diagram of the EP / PDA / PCL@IL composite coating;

[0032] Figure 4 It is the potentiodynamic polarization curve diagrams of different coatings (EP coating, EP / PDA / PCL composite coating, EP / PDA / PCL@IL coating prepared in Example 1) prepared on the surface of AZ31B magnesium alloy;

[0033] Figure 5 It is the scratch photo-thermal self-healing experiment of different coatings prepared on the surface of AZ31B magnesium alloy: (a) EP coating, (b) 5% EP / PDA / PCL@IL coating, (c) 10% EP / PDA / PCL@IL coating, and (d) 15% EP / PDA / PCL@IL coating;

[0034] Figure 6 It is the salt spray experiment test diagrams of different coatings (EP coating, EP / PDA / PCL composite coating, EP / PDA / PCL@IL coating prepared in Example 1) prepared on the surface of AZ31B magnesium alloy. Detailed Description of the Invention

[0035] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0036] In the following embodiments, unless otherwise specified, the raw materials used are all ordinary commercially available products, and room temperature refers to (25±5)°C.

[0037] The ionic liquid [Hmim][C 12 H 25 SO4] can be prepared with reference to the literature (Effect of alkyl chain lengthof imidazolium cations onfoam properties of anionic surface active ionicliquids: Experimental and DFT studies. Kehui Hu, etal.Journal of Molecularliquids: 340(2021)117197.).

[0038] In the following examples, the magnesium alloy used was pretreated as follows:

[0039] (1) The AZ31B magnesium alloy was machined into samples with a size of 1.5 cm × 1.5 cm × 0.6 cm, and the substrate was coated with epoxy resin, leaving only a 1.5 cm × 1.5 cm working surface;

[0040] (2) Subsequently, the AZ31B magnesium alloy samples were polished successively with 180, 600, 1500, and 3000 - mesh sandpapers, and then polished with W3.5 diamond polishing paste (Veiyee, model PG);

[0041] (3) Finally, ultrasonic cleaning was performed with distilled water and absolute ethanol for 10 min each, and then air - dried naturally, and that's it.

[0042] Example 1

[0043] 1. Preparation of PDA / PCL@IL microspheres

[0044] (1) Dissolve 0.5 g of polycaprolactone PCL in 15 mL of dichloromethane, and dissolve 0.05 g of ionic liquid [Hmim][C 12 H 25 SO4] (IL) in 100 mL of a 0.5% (w / v) polyvinyl alcohol PVA solution. After mixing the two, stir vigorously at room temperature for 30 min, then stir magnetically at 1000 r / min for 12 h, and centrifuge to obtain PCL@IL microspheres.

[0045] (2) Dissolve 0.2 g of dopamine in 100 mL of Tris-HCl buffer solution with a pH of 8.5 to obtain a Tris-HCl solution of dopamine. Then soak 0.1 g of PCL@IL microspheres in the Tris-HCl solution of dopamine and stir overnight (12 h) at 37 °C to obtain PDA / PCL@IL microspheres (for the structural schematic diagram, see Figure 1 ).

[0046] 2. Preparation of EP / PDA / PCL@IL composite coating

[0047] Disperse 0.4 g of PDA / PCL@IL microspheres evenly in 15 mL of acetone by ultrasonic treatment for 30 min. Then add 1.7 g of bisphenol A diglycidyl ether (DGEBA) and 1.08 g of neopentyl glycol diglycidyl ether (NGDE), mix well to form a homogeneous liquid, and use a rotary evaporator to evaporate the acetone. PDA / PCL@IL is evenly dispersed in the epoxy resin. Then add 1.15 g of polyetheramine curing agent D230, stir evenly by ultrasonic treatment for 15 min to obtain a PDA / PCL@IL / epoxy resin composite solution. Place the pretreated magnesium alloy sample on a spin coater, and evenly coat the PDA / PCL@IL / epoxy resin composite solution on the surface of the magnesium alloy by spin coating. Cure at a temperature of 50 °C for 18 h to finally obtain a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer (with a thickness of about 50 μm, see Figure 3 c), denoted as 10% EP / PDA / PCL@IL coating.

[0048] Figure 2 The SEM surface morphology diagrams of PCL (a), PCL@IL microspheres (c), and PDA / PCL@IL microspheres (e) and the EDS energy spectrum diagrams of PCL (b), PCL@IL microspheres (d), and PDA / PCL@IL microspheres (f) in Example 1 above are given. The surface morphologies of PCL, PCL@IL, and PDA / PCL@IL were analyzed by SEM. As Figure 1 shown in (a) and (c), the morphologies of PCL and PCL@IL are both spherical with an average diameter of about 7 μm, indicating that the addition of the ionic liquid inhibitor has no significant effect on the size and morphology of the PCL microspheres. Figure 2 (e) shows the morphology of the PDA / PCL@IL microspheres, and it can be seen that dopamine has been successfully deposited on the surface of the PCL@IL microspheres. To further confirm the successful synthesis of the microspheres, the synthesized microspheres were analyzed by energy-dispersive X-ray spectroscopy (EDS). Figure 2 (b) is the EDS spectrum of the PCL microspheres, which contains only two elements, C and O. Figure 2(d) is the EDS spectrum of PCL@IL microspheres. There are still only two elements, C and O, indicating that the ionic liquid inhibitor is encapsulated within the microspheres. Figure 2 (f) is the EDS spectrum of PDA / PCL@IL microspheres. The presence of N element also confirms the deposition of PDA. The scanning electron microscopy and EDS analysis results clearly demonstrate the successful preparation of PCL, PCL@IL, and PDA / PCL@IL microspheres.

[0049] Example 2

[0050] The difference from Example 1 is that when preparing the EP / PDA / PCL@IL composite coating, 0.4 g of PDA / PCL@IL microspheres are replaced with 0.2 g, denoted as the 5% EP / PDA / PCL@IL coating.

[0051] Example 3

[0052] The difference from Example 1 is that when preparing the EP / PDA / PCL@IL composite coating, 0.4 g of PDA / PCL@IL microspheres are replaced with 0.59 g, denoted as the 15% EP / PDA / PCL@IL coating.

[0053] Comparative Example 1

[0054] 1. Preparation of EP composite coating

[0055] Weigh 1.7 g of bisphenol A diglycidyl ether (DGEBA) and 1.08 g of neopentyl glycol diglycidyl ether (NGDE), mix them to form a homogeneous liquid, then add 1.15 g of polyetheramine curing agent D230, and disperse it evenly by ultrasonic stirring for 15 min to obtain an epoxy resin composite solution. Place the pretreated magnesium alloy sample on a spin coater, and uniformly coat the epoxy resin composite solution on the surface of the magnesium alloy by spin coating. Cure it at 50 °C for 18 h to finally obtain an EP composite coating (with a thickness of about 50 μm, see Figure 3 a) in

[0056] Comparative Example 2

[0057] 1. Preparation of PDA / PCL microspheres

[0058] (1) Dissolve 0.5 g of polycaprolactone PCL in 15 mL of dichloromethane, mix it with 100 mL of a 0.5% (w / v) polyvinyl alcohol PVA solution, stir vigorously at room temperature for 30 min, then stir magnetically at 1000 r / min for 12 h, and centrifuge to obtain PCL microspheres;

[0059] (2) Dissolve 0.2 g of dopamine in 100 mL of Tris-HCl buffer solution with a pH of 8.5 to obtain a Tris-HCl solution of dopamine. Then soak 0.1 g of PCL microspheres in the Tris-HCl solution of dopamine and stir overnight (12 h) at 37 °C to obtain PDA / PCL microspheres.

[0060] 2. Preparation of EP / PDA / PCL composite coating

[0061] Disperse 0.4 g of PDA / PCL microspheres evenly in 15 mL of acetone by ultrasonic treatment for 30 min. Then add 1.7 g of bisphenol A diglycidyl ether (DGEBA) and 1.08 g of neopentyl glycol diglycidyl ether (NGDE), mix well to form a homogeneous liquid, and use a rotary evaporator to remove the acetone. The PDA / PCL microspheres are evenly dispersed in the epoxy resin. Then add 1.15 g of polyetheramine curing agent D230 and stir ultrasonically for 15 min to disperse evenly to obtain a PDA / PCL epoxy resin composite solution. Place the pretreated magnesium alloy sample on a spin coater and evenly coat the PDA / PCL epoxy resin composite solution on the surface of the magnesium alloy by spin coating, and cure at a temperature of 50 °C for 18 h to finally obtain an EP / PDA / PCL composite coating (with a thickness of about 50 μm).

[0062] Figure 3 The SEM images of different composite coatings prepared on the surface of magnesium alloy are given: (a) is the EP coating; (c) is the EP / PDA / PCL@IL composite coating. As Figure 3 shown, SEM characterization shows that the surface of the EP coating prepared in Comparative Example 1 is very smooth, flat and dense ( Figure 3 in a). After doping PDA / PCL@IL microspheres in the EP coating ( Figure 3 in c), its surface is still smooth and flat, and almost no difference can be seen, indicating that the PDA / PCL@IL microspheres are evenly dispersed in the EP coating without obvious agglomeration phenomenon.

[0063] The corrosion resistance of various coating samples (EP coating, EP / PDA / PCL composite coating, EP / PDA / PCL@IL coating prepared in Example 1) prepared in Example 1 and Comparative Example was tested by electrochemical method in 3.5 wt.% NaCl solution, and their potentiodynamic polarization curves are as Figure 4 shown. The corrosion current density of the EP / PDA / PCL@IL composite coating prepared in Example 1 of this example is 6.14×10 –10 A / cm 2 , compared with the corrosion current density of AZ31B magnesium alloy (1.102×10 –5 A / cm2 ), it is reduced by 5 orders of magnitude. Compared with the corrosion current density of the EP coating (1.277×10 –8 A / cm 2 ), it is reduced by 2 orders of magnitude. Compared with the corrosion current density of the EP / PDA / PCL composite coating (7.667×10 –9 A / cm 2 ), it is reduced by 1 order of magnitude, indicating that the EP / PDA / PCL@IL composite coating of the present invention greatly improves the corrosion resistance of magnesium alloys.

[0064] To demonstrate the self-healing performance of different coating samples, the coatings in this application were scratched with a blade and irradiated with an 808 nm laser at a power density of 2.0 W / cm 2 for 5 min. The surface morphology of the scratches before and after NIR irradiation was recorded with an optical microscope. In addition, the heat generation behavior of different coatings was monitored using infrared thermal images. The results are shown in Figure 5 . It can be seen from Figure 5 that for the pure epoxy resin coating (EP coating), since its surface temperature (about 35 °C) is too low to trigger the shape memory effect, self-healing cannot be performed. For the EP / PDA / PCL@IL coating of the present invention, regardless of whether the addition amount of PDA / PCL@IL microspheres is 5%, 10%, or 15%, the scratches have healed after 5 min of irradiation, and the coating temperature is higher than 55 °C, indicating that it can stimulate the photothermal effect of polydopamine deposited on the surface of polycaprolactone microspheres through light irradiation, convert light into heat, accelerate the release of ionic liquid and the melting of polycaprolactone microspheres, and quickly repair the damaged area of the coating, thereby achieving the effect of coating self-healing.

[0065] The neutral salt spray experiment further tested the long-term corrosion resistance of magnesium alloy samples with different coatings in a more severe environment, and they were salt spray immersed in a 5.0 wt.% NaCl solution. Figure 6 The salt spray experiment test diagrams of different coatings (EP coating, EP / PDA / PCL composite coating, EP / PDA / PCL@IL coating prepared in Example 1) prepared on the magnesium alloy surface are given, and they were salt spray immersed in a 5.0 wt.% NaCl solution. The results are as Figure 6 shown. As can be seen from Figure 6It can be seen that the bare AZ31B magnesium alloy shows corrosion phenomenon earliest, and large corrosion areas appear only after 24 h. Compared with the bare AZ31B magnesium alloy, the corrosion conditions of the EP coating, EP / PDA / PCL coating and EP / PDA / PCL@IL coating samples are slightly better. Corrosion of the EP coating starts only after 432 h of immersion, while the EP / PDA / PCL composite coating starts to corrode after 504 h. Different from the above samples, the surface of the EP / PDA / PCL@IL coating sample of the present invention remains intact after 720 h (30 d) of immersion, and there is no corrosion on the coating surface, indicating that the coating has excellent corrosion protection.

[0066] In summary, the present invention prepared a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer. The preparation method is simple, and the obtained self-healing anti-corrosion coating has a uniform and dense surface. It can not only greatly improve the corrosion resistance of magnesium alloy, but also has a photothermal self-repair function, which can provide long-term corrosion protection for magnesium alloy.

[0067] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, several improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of a self-healing anti-corrosion coating with a photothermal-responsive nanocontainer, characterized in that It includes the following steps: 1) Prepare PCL@IL microspheres Dissolve the ionic liquid [Hmim][C 12 H 25 SO4] in a polyvinyl alcohol solution, then mix it with a dichloromethane solution of polycaprolactone, stir and react for 10 - 14 h, and perform solid-liquid separation to obtain PCL@IL microspheres; 2) Prepare PDA / PCL@IL microspheres Immerse the PCL@IL microspheres in a Tris-HCl solution of dopamine and stir and react at 30-40 °C for 10-14 h, then perform solid-liquid separation to obtain PDA / PCL@IL microspheres; 3) Prepare an EP / PDA / PCL@IL composite coating Disperse the PDA / PCL@IL microspheres evenly in acetone, then add bisphenol A diglycidyl ether and neopentyl glycol diglycidyl ether, mix well, remove acetone by rotary evaporation, add a curing agent, disperse evenly, coat on the surface of the magnesium alloy, and cure to obtain.

2. The preparation method of the self-healing anti-corrosion coating with a photothermal-responsive nanocontainer as claimed in claim 1, wherein, In step 1), the mass ratio of the polycaprolactone to the ionic liquid [Hmim][C 12 H 25 SO4] is (9 - 12):

1.

3. The preparation method of the self-healing anti-corrosion coating with the photothermal-responsive nanocontainer as described in claim 1, characterized in that, In step 2), the mass ratio of the dopamine to the PCL@IL microspheres is (0.1-0.3):(0.05-0.15).

4. The preparation method of the self-healing anti-corrosion coating with the photothermal-responsive nanocontainer as described in claim 3, characterized in that, In step 2), the concentration of the Tris-HCl solution of dopamine is 1.5-2.5 g / L.

5. The preparation method of the self-healing anti-corrosion coating with the photothermal-responsive nanocontainer as described in claim 3, wherein, In step 3), the mass ratio of the bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, and the curing agent is (1.5-2):(0.9-1.1):(1.1-1.2).

6. The preparation method of the self-healing anti-corrosion coating with the photothermal-responsive nanocontainer as claimed in claim 3, characterized in that, In step 3), the addition amount of the PDA / PCL@IL microspheres is 5%-15% of the total mass of the bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, and the curing agent.

7. The preparation method of the self-healing anti-corrosion coating with a photothermal-responsive nanocontainer as described in claim 3, characterized in that, In step 3), the curing agent is a polyetheramine curing agent D230, and it is cured at a temperature of 45-55 °C for 12-24 h.

8. A self-healing anti-corrosion coating with a photothermal-responsive nanocontainer prepared by the preparation method according to any one of claims 1 to 7.

9. Application of the self-healing anti-corrosion coating with a photothermal-responsive nanocontainer according to claim 8 in photothermal self-healing of metal corrosion.

10. The application according to claim 9, wherein Irradiate the damaged area of the coating with a near-infrared laser of 1~2 W / cm 2 , and the coating gradually melts within 4~6 min to heal the damaged interface.

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