Corrosion inhibitor-loaded polyaniline multi-core microcapsule, preparation method thereof and self-repairing anticorrosive coating prepared from corrosion inhibitor-loaded polyaniline multi-core microcapsule

Abstract

The preparation method comprises the following steps: S1, mixing a photocuring material, a photoinitiator, an organic solvent and a corrosion inhibitor to serve as an oil phase, taking an aqueous dispersion of an emulsifier as a water phase, and mixing and emulsifying the oil phase and the water phase to obtain an oil-in-water emulsion; s2, sodium p-styrenesulfonate is added into the oil-in-water emulsion, ultraviolet curing and washing are conducted, wet sulfonated polymer multi-core microcapsules are obtained, then ultrasonic treatment is conducted in deionized water, and sulfonated polymer multi-core microcapsule aqueous dispersion is prepared; and S3, dropwise adding aniline into the aqueous dispersion of the sulfonated polymer multi-core microcapsule, stirring, and dropwise adding an initiator aqueous solution containing protonic acid to initiate aniline polymerization, thereby obtaining the polyaniline multi-core microcapsule. When the multi-core microcapsule is used for an anticorrosive coating, even if local damage exists, the remaining core material can be protected by the wall material composite condensate, a time difference of'sequential release 'is formed, and the core material is slowly released.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, and in particular to a polyaniline polynuclear microcapsule loaded with a corrosion inhibitor, its preparation method, and the self-healing anti-corrosion coating prepared therefrom. Background Technology

[0002] As core basic materials in industrial production, infrastructure construction, and high-end equipment manufacturing, the corrosion of metallic materials during service has become a key factor restricting equipment lifespan, causing safety hazards, and resulting in huge economic losses. Developing efficient, long-lasting, and environmentally friendly metal corrosion protection technologies is an important research topic in the field of materials science and engineering.

[0003] Anti-corrosion coatings have become the most commonly used technical means for metal corrosion protection due to their advantages such as convenient construction, controllable cost, and direct protective effect. Traditional anti-corrosion coatings mainly isolate corrosive media from the metal substrate through physical barriers, such as epoxy resin coatings and polyurethane coatings. However, these coatings are prone to microcracks or damage during preparation and service due to factors such as internal stress, mechanical impact, and temperature changes. Once the integrity of the coating is compromised, corrosive media can quickly penetrate to the metal surface and cause localized corrosion. Moreover, the coating itself does not have the ability to repair damage, leading to a sharp decline in protective performance. To solve this problem, researchers have developed functional anti-corrosion coatings such as sacrificial anode coatings and passivation coatings. These coatings form a protective barrier through the electrochemical reaction between the active ingredients in the coating and the metal. However, the active ingredients in these coatings are often consumed in large quantities in the early stages of service, making it difficult to achieve long-term protective effects.

[0004] Polyaniline (PANI), a conductive polymer with unique doping-dedoping properties, exhibits unique advantages in the field of metal corrosion protection. Its corrosion protection mechanism primarily stems from the quinone structure in the PANI molecular chain, which can undergo a redox reaction with the metal surface, promoting the formation of a dense oxide passivation film and inhibiting anodic dissolution. However, pure PANI coatings suffer from drawbacks such as high brittleness, poor flexibility, and insufficient adhesion to the substrate, making them prone to cracking under complex operating conditions. Furthermore, single PANI coatings lack the ability to actively respond to damage; once damaged, their anti-corrosion effect is rapidly lost, limiting their application in harsh environments.

[0005] To endow coatings with self-healing capabilities, microencapsulation technology has been widely introduced into anti-corrosion coating systems. By encapsulating functional substances such as corrosion inhibitors and repair agents in microcapsules, when microcracks appear in the coating, the mechanical force generated during crack propagation can trigger the microcapsule to rupture, releasing the internal functional substances and achieving the dual effects of crack filling and corrosion inhibition. Currently reported anti-corrosion microcapsules are mostly mononuclear structures; however, the wall thickness of mononuclear microcapsules is usually uneven, with thinner sections easily rupturing and rapidly releasing the internal core material.

[0006] Combining polyaniline with microencapsulation technology is an effective approach to improve the corrosion resistance of coatings. In existing research, some methods use polyaniline as the microcapsule wall material, or mix it with corrosion inhibitors and disperse it directly in the coating matrix, but most of these are mononuclear microcapsules, which lack long-term corrosion inhibition capabilities.

[0007] Based on the shortcomings of the existing technologies, there is an urgent need to develop an anti-corrosion coating system that combines active self-healing capability, long-lasting anti-corrosion performance, and excellent mechanical properties. Summary of the Invention

[0008] To address the aforementioned problems in existing technologies, this invention provides a polyaniline polynuclear microcapsule loaded with a corrosion inhibitor, its preparation method, and the self-healing anti-corrosion coating prepared therefrom. This invention combines emulsion template method, photopolymerization technology, and in-situ polymerization technology to develop a simple method for preparing polyaniline polynuclear microcapsules loaded with a corrosion inhibitor. When the polynuclear microcapsules are used in anti-corrosion coatings, even with localized damage, the remaining core material is protected by the wall material composite aggregate, creating a "sequential release" time difference, allowing the core material to be released slowly.

[0009] The technical solution of the present invention is as follows: The first objective of this invention is to provide a method for preparing polyaniline polynuclear microcapsules loaded with corrosion inhibitors, comprising the following steps: S1, weigh out the photocurable material, photoinitiator, organic solvent and corrosion inhibitor and mix them evenly as the oil phase, take the aqueous dispersion of the emulsifier as the aqueous phase, mix the oil phase and the aqueous phase and emulsify once to obtain an oil-in-water (O / W) emulsion. S2, add sodium p-styrene sulfonate to the oil-in-water emulsion, and after it is completely dissolved, cure it with ultraviolet light. Then wash it with anhydrous ethanol and deionized water alternately 3-4 times to remove excess sodium p-styrene sulfonate and obtain wet sulfonated polymer polynuclear microcapsules. Then transfer them to deionized water and sonicate them to disperse the microcapsules evenly to obtain an aqueous dispersion of sulfonated polymer polynuclear microcapsules. S3, aniline is added dropwise to an aqueous dispersion of sulfonated polymer polynuclear microcapsules, stirred, and then an aqueous initiator containing protic acid is added dropwise under ice bath conditions to initiate aniline polymerization. After reacting under ice bath conditions for 12-36 h, the polyaniline polynuclear microcapsules are obtained by sedimentation and washing.

[0010] In one embodiment of the present invention, in step S1, the photocurable material is one or more of pentaerythritol triacrylate, dipentaerythritol pentaacrylate, N,N'-methylenebisacrylamide, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. Photocurable materials are multifunctional compounds (functionality greater than or equal to 2), and their Hansen solubility δ pThe polar component is 6-18, and the cross-linked network formed after curing is insoluble or sparingly soluble in the organic solvent, with a solubility range of <1g / 100mL.

[0011] The organic solvent is one or more of cyclohexane, n-hexane, petroleum ether, and n-heptane; the δ value of the Hansen solubility of the organic solvent is... p (Polar component) is 0.

[0012] In one embodiment of the present invention, in step S1, the photoinitiator is one or more of 2-hydroxy-2-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, bis(1-(2,4-difluorophenyl)-3-pyrrolithium)dicenoctane, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone; The corrosion inhibitor is one or more of the following: methylbenzotriazole, 2-mercaptobenzothiazole, 2-mercaptobenzoimidazol, 2-mercaptobenzoxazole, benzotriazole, oleic acid imidazoline, butylbenzotriazole, and thiadiazole.

[0013] In one embodiment of the present invention, in step S1, the oil phase composition by weight is: 80-100 parts of photocurable material, 1-4 parts of photoinitiator, 20-50 parts of organic solvent, and 10-30 parts of corrosion inhibitor.

[0014] In one embodiment of the present invention, in step S1, the aqueous phase is an aqueous dispersion of emulsifier with a mass concentration of 0.5-5%. The emulsifier in the aqueous phase is one or more of the following: polyvinyl alcohol, polyethylene glycol, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polystyrene-maleic anhydride copolymer, Tween-60, Tween-80, Span-60, Span-80, hexadecyltrimethylammonium bromide, gelatin, and gum arabic.

[0015] In one embodiment of the present invention, in step S1, the mass ratio of the oil phase to the water phase is 4:1-1:4; the emulsification conditions are an emulsifier rotation speed of 5000-20000 rpm and an emulsification time of 0.5-3 min.

[0016] In one embodiment of the present invention, in step S2, 15-25 parts by weight of sodium styrene sulfonate are used.

[0017] In one embodiment of the present invention, in step S2, the conditions for ultraviolet curing are: wavelength 230-420 nm and curing time 1-10 min.

[0018] In one embodiment of the present invention, in step S2, the washing process involves alternating washing with deionized water and anhydrous ethanol to remove excess sodium p-styrene sulfonate, resulting in wet sulfonated polymer polynuclear microcapsules. The filter cake is then transferred to deionized water and ultrasonically dispersed to obtain an aqueous dispersion of sulfonated polymer polynuclear microcapsules.

[0019] In one embodiment of the present invention, in step S3, the protic acid is one or more of hydrochloric acid, sulfuric acid, phytic acid, and phosphoric acid.

[0020] In one embodiment of the present invention, in step S3, the initiator is one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, and potassium permanganate; the molar ratio of the initiator to aniline is 1:2-4:1; the mass ratio of aniline to sulfonated polymer polynuclear microcapsules is 1:20-1:2; and the mass ratio of protic acid to aniline is 10:1-1:1.

[0021] In one embodiment of the present invention, in step S3, the temperature of the ice bath is 2-3 ℃.

[0022] A second objective of this invention is to provide a polyaniline polynuclear microcapsule loaded with a corrosion inhibitor prepared by the above-described method.

[0023] In one embodiment of the present invention, the shell material of the polyaniline polynuclear microcapsules loaded with corrosion inhibitor includes polyaniline and a photocurable material. The polyaniline polynuclear microcapsules have a particle size of 5-30 μm, a wall thickness of 1.3-2.5 μm, a micronucleus unit particle size of 0.5-3 μm, and a corrosion inhibitor loading rate of 30%-60%. The mass ratio of polyaniline to photocurable material is 1:20-1:2.

[0024] The third objective of this invention is to provide a self-healing anti-corrosion coating containing polyaniline polynuclear microcapsules loaded with the above-mentioned corrosion inhibitor, wherein the polyaniline polynuclear microcapsules loaded with the corrosion inhibitor account for 5-15 wt% of the total mass of the coating. In one embodiment of the present invention, the self-healing anti-corrosion coating further includes a film-forming resin.

[0025] The fourth objective of this invention is to provide a coating obtained by adding polyaniline polynuclear microcapsules loaded with corrosion inhibitors to a film-forming resin and curing it.

[0026] In one embodiment of the present invention, the film-forming resin is a photocurable resin system, a solvent-based resin system, or a water-based resin system.

[0027] In one embodiment of the present invention, the coating is cured by photocuring.

[0028] In one embodiment of the present invention, the self-repairing anti-corrosion coating comprises, by weight, 5-15 parts of polyaniline polynuclear microcapsules loaded with corrosion inhibitor, 50-70 parts of photocurable resin, 15-30 parts of reactive diluent, 2-4 parts of photoinitiator, and 1-10 parts of additives; the photocuring irradiation conditions are: UV wavelength of 230-420 nm and curing time of 0.5-2 min.

[0029] In one embodiment of the present invention, the photocurable resin is one or more of epoxy acrylate, polyurethane acrylate, and polyester acrylate.

[0030] In one embodiment of the present invention, the reactive diluent is one or more of tetrahydrofurfuryl acrylate, isobornyl acrylate, tetrahydrofuran acrylate, and polyethylene glycol diacrylate.

[0031] In one embodiment of the present invention, the additive is one or more of an adhesion promoter and a leveling agent.

[0032] In one embodiment of the present invention, the adhesion promoter is one or more of phosphate methacrylate (PM-2) and 2-methyl-2-acrylate-2-hydroxyethyl phosphate (PM-1).

[0033] In one embodiment of the present invention, the leveling agent is a polyether-modified polydimethylsiloxane copolymer (BYK333).

[0034] In one embodiment of the present invention, the coating is cured by thermal curing.

[0035] In one embodiment of the present invention, the self-repairing anti-corrosion coating is composed of the following components by weight: 5-15 parts of polyaniline polynuclear microcapsules loaded with corrosion inhibitor, 78-84 parts of water-based resin, and 16-22 parts of curing agent; the heat curing conditions are: curing temperature of 50-80 ℃ and curing time of 2-6 h.

[0036] In one embodiment of the present invention, the aqueous resin is one or more of epoxy resin, acrylic resin, and silicone resin; In one embodiment of the present invention, the curing agent is one or more of amine curing agents, epoxy curing agents, Mannich base curing agents, and polyamide curing agents.

[0037] In one embodiment of the present invention, the self-repairing anti-corrosion coating comprises, by weight, 5-15 parts of polyaniline polynuclear microcapsules loaded with corrosion inhibitor, 78-84 parts of solvent-based resin, and 16-22 parts of curing agent; the heat curing conditions are: curing temperature of 50-80 ℃ and curing time of 2-6 h.

[0038] In one embodiment of the present invention, the solvent-based resin is one or more selected from epoxy resin, acrylic resin, polyurethane resin, phenolic resin, and alkyd resin. In one embodiment of the present invention, the curing agent is one or more of amine curing agents and isocyanate crosslinking agents.

[0039] The beneficial technical effects of this invention are as follows: (1) This invention combines emulsion template method, photopolymerization technology and in-situ polymerization technology to provide a method for preparing polyaniline polynuclear microcapsules loaded with corrosion inhibitors. The preparation method adopts in-situ loading corrosion inhibitor technology, which does not require additional post-loading treatment. In addition, photopolymerization technology solidifies the shell of droplets without long-term heating, and the synthesis is efficient and stable, with the potential for mass production.

[0040] (2) This invention utilizes the difference in polarity between the polymer crosslinking network formed by the photopolymer during ultraviolet photopolymerization to address the phase separation phenomenon between the solvent phase and the polymer phase. The Hansen solubility δ of the selected organic solvent is considered. p When the polar component is 0, the organic solvent has poor affinity for the polymer network, resulting in complete incompatibility between the solvent phase and the polymer phase. As a result, phase separation occurs at the beginning of polymerization. The nucleation process in the droplet and the migration of the in-situ polymer to the droplet surface occur simultaneously, eventually forming multinucleated microcapsules.

[0041] (3) In this invention, polyaniline can impart good anti-corrosion effect to the coating. As an environmentally friendly and green anti-corrosion filler, polyaniline does not contain heavy metal ions and is easy to synthesize. When it is applied in coatings, it can provide anodic protection for the substrate. Its own redox cycle can generate a passivation film to isolate the corrosion medium from erosion. The corrosion inhibitor can impart good self-healing performance to the coating. When the coating is damaged by external forces such as scratching and collision, the metal substrate is exposed to the corrosive environment. The microenvironment of the damaged area (such as changes in pH value and increases in ion concentration) will trigger the responsive release mechanism of the microsphere structure. The corrosion inhibitor will quickly migrate to the damaged metal surface through diffusion, form a stable chelate film with metal ions, fill the coating defects and block the continuous corrosion reaction.

[0042] (4) This invention constructs polyaniline multinuclear microcapsules loaded with corrosion inhibitors, achieving a synergistic effect of the passivation and corrosion protection of polyaniline and the active repair effect of the corrosion inhibitors: the multinuclear structure not only increases the loading of the corrosion inhibitors but also avoids concentrated release of the corrosion inhibitors. The outer total wall material and the partition wall material between the core material form a multi-level diffusion barrier, requiring the core material to be released through multiple permeation paths, thus prolonging the diffusion time and ultimately achieving long-term release of the corrosion inhibitors; polyaniline serves as a component of the capsule wall, providing basic corrosion protection, and can also complement the corrosion inhibitors inside the capsule, extending the protective life of the coating. Therefore, developing such multinuclear microcapsules and their self-healing anti-corrosion coating preparation methods has significant practical significance and application value in solving the problems of short protective life and weak repair ability of traditional coatings. Attached Figure Description

[0043] Figure 1 The infrared spectrum of the polyaniline polynuclear microcapsules loaded with corrosion inhibitor prepared in Example 1 of this invention; Figure 2 This is a scanning electron microscope (SEM) image of the polyaniline polynuclear microcapsules prepared in Example 1 of this invention. Figure 3 This is a scanning electron microscope (SEM) image of the polyaniline mononuclear microcapsules prepared in Comparative Example 2 of this invention. Figure 4 The release curves of the corrosion inhibitor in NaCl salt solution are shown for the polyaniline polynuclear microcapsules prepared in Example 1 and the polyaniline mononuclear microcapsules prepared in Comparative Example 2. Figure 5 The neutral scratch salt spray resistance test of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention; Figure 6 The test results are for the resistance to neutral intact salt spray of Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] Example 1 The preparation method of polyaniline polynuclear microcapsules loaded with corrosion inhibitors includes the following steps: a. Add 100 parts pentaerythritol triacrylate, 30 parts cyclohexane, 30 parts benzotriazole, and 4 parts 2-hydroxy-2-methyl-1-phenyl-1-propanone to a centrifuge tube and vortex to mix evenly to obtain the oil phase; add 41 parts deionized water and 2.05 parts Tween-60 to a centrifuge tube and vortex to mix evenly to obtain the aqueous phase; mix the oil phase and the aqueous phase evenly to obtain an emulsion; b. Slowly add 15 parts of sodium p-styrene sulfonate to the emulsion and stir. Then, place the emulsion under a UV-LED ultraviolet light source to cure for 5 min. Use deionized water and anhydrous ethanol alternately to wash away unreacted sodium p-styrene sulfonate to prepare sulfonated polymer polynuclear microcapsules. Then, transfer them to deionized water and sonicate to disperse the microcapsules evenly to obtain an aqueous dispersion of sulfonated polymer polynuclear microcapsules. c. Add 10 parts of aniline dropwise to 1500 parts of an aqueous dispersion containing 100 parts of sulfonated polymer polynuclear microcapsules, and stir continuously to allow aniline to be completely adsorbed onto the surface of the polynuclear microcapsules. Then, under ice bath (2-3 ℃) conditions, add 200 parts of an aqueous solution containing 12.25 parts of ammonium persulfate and 100 parts of phosphoric acid dropwise to initiate the polymerization of aniline. After reacting under ice bath conditions for 24 h, the polyaniline polynuclear microcapsules loaded with benzotriazole are obtained after sedimentation and washing.

[0046] The preparation method of a self-healing anti-corrosion coating of polyaniline polynuclear microcapsules loaded with corrosion inhibitors includes the following steps: 7.8 parts of the above-mentioned benzotriazole-loaded polyaniline polynuclear microcapsules were added to an aqueous coating composed of 78 parts of waterborne epoxy resin (LLA-10, Jiangsu Lanling Chemical Group Co., Ltd.) and 20 parts of amine curing agent (LLA-119, Jiangsu Lanling Chemical Group Co., Ltd.), and cured at 80 °C for 3 hours to obtain a benzotriazole-loaded polyaniline polynuclear microcapsule-based self-healing anti-corrosion coating.

[0047] Example 2 The preparation method of polyaniline polynuclear microcapsules loaded with corrosion inhibitors includes the following steps: a. Add 80 parts of dipentaerythritol pentaacrylate, 50 parts of n-hexane, 10 parts of methylbenzotriazole, and 0.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone to a 250 mL beaker and vortex to mix thoroughly to obtain the oil phase. Add 562 parts of deionized water and 2.81 parts of Tween-80 to a centrifuge tube and vortex to mix thoroughly to obtain the aqueous phase. Mix the oil phase and the aqueous phase thoroughly to obtain an emulsion. b. Slowly add 25 parts of sodium p-styrene sulfonate to the emulsion and stir. Then, place the emulsion under a UV-LED ultraviolet light source to cure for 5 min. Use deionized water and anhydrous ethanol alternately to wash away unreacted sodium p-styrene sulfonate to prepare sulfonated polymer polynuclear microcapsules. Then, transfer them to deionized water and sonicate to disperse the microcapsules evenly to obtain an aqueous dispersion of sulfonated polymer polynuclear microcapsules. c. Add 5 parts of aniline dropwise to 1500 parts of an aqueous dispersion containing 100 parts of sulfonated polymer polynuclear microcapsules, and stir continuously to allow aniline to be completely adsorbed onto the surface of the polynuclear microcapsules. Then, under ice bath (2-3 ℃) conditions, add 2000 parts of an aqueous solution containing 49 parts of ammonium persulfate and 5 parts of phytic acid dropwise to initiate the polymerization of aniline. After reacting under ice bath conditions for 12 h, after sedimentation and washing, polyaniline polynuclear microcapsules loaded with methylbenzotriazole are obtained.

[0048] The preparation method of a self-healing anti-corrosion coating of polyaniline polynuclear microcapsules loaded with corrosion inhibitors includes the following steps: 4.2 parts of the above-mentioned polyaniline polynuclear microcapsules loaded with methylbenzotriazole were added to a solvent-based coating composed of 84 parts of solvent-based epoxy resin (E51, Jiangsu Sanmu Chemical Co., Ltd.) and 16 parts of amine curing agent (polyetheramine D-230, Adamas Reagent Co., Ltd.), and cured at 50 °C for 6 hours to obtain a self-healing anti-corrosion coating based on polyaniline polynuclear microcapsules loaded with methylbenzotriazole.

[0049] Example 3 The preparation method of polyaniline polynuclear microcapsules loaded with corrosion inhibitors includes the following steps: a. Add 90 parts of N,N'-methylenebisacrylamide, 20 parts of petroleum ether, 20 parts of thiadiazole, and 2 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone to a 250 mL beaker and vortex to mix thoroughly to obtain the oil phase. Add 264 parts of deionized water and 6.6 parts of Span-60 to a centrifuge tube and vortex to mix thoroughly to obtain the aqueous phase. Mix the oil phase and the aqueous phase thoroughly to obtain an emulsion. b. Slowly add 20 parts of sodium p-styrene sulfonate to the emulsion and stir. Then, place the emulsion under a UV-LED light source to cure for 5 min. Use deionized water and anhydrous ethanol alternately to wash away unreacted sodium p-styrene sulfonate to prepare sulfonated polymer multinuclear microcapsules. Then, transfer them to deionized water and sonicate to disperse the microcapsules evenly to obtain an aqueous dispersion of sulfonated polymer multinuclear microcapsules. c. Add 25 parts of aniline dropwise to 1500 parts of an aqueous dispersion containing 50 parts of sulfonated polymer polynuclear microcapsules, and stir continuously to allow aniline to be completely adsorbed onto the surface of the polynuclear microcapsules. Then, under ice bath (2-3 ℃) conditions, add 2800 parts of an aqueous solution containing 150 parts of ammonium persulfate and 125 parts of sulfuric acid dropwise to initiate the polymerization of aniline. After reacting under ice bath conditions for 36 h, the polyaniline polynuclear microcapsules loaded with thiadiazole are obtained after sedimentation and washing. The preparation method of a self-healing anti-corrosion coating of polyaniline polynuclear microcapsules loaded with corrosion inhibitors includes the following steps: 12.75 parts of the above-mentioned thiadiazole-loaded polyaniline polynuclear microcapsules were added to a UV-curable coating composed of 70 parts of modified epoxy acrylate (6215-100, Changxing Special Materials (Suzhou) Co., Ltd.), 15 parts of isobornyl acrylate (IBOA, Changxing Special Materials (Suzhou) Co., Ltd.), 2.5 parts of 2-hydroxy-2-methylphenylpropane-1-one, and 1 part of PM-2. The resulting coating was then subjected to ultraviolet irradiation with a total irradiation energy of 1000 mJ / cm². 2 A self-healing anti-corrosion coating based on polyaniline polynuclear microcapsules loaded with thiadiazole was obtained.

[0050] Comparative Example 1 The preparation method of water-based anti-corrosion coating includes the following steps: 78 parts of waterborne epoxy resin (LLA-10, Jiangsu Lanling Chemical Group Co., Ltd.) and 20 parts of curing agent (LLA-119, Jiangsu Lanling Chemical Group Co., Ltd.) were mixed and cured at 80 °C for 3 hours to obtain a waterborne anti-corrosion coating.

[0051] Comparative Example 2 The preparation method of polyaniline mononuclear microcapsules includes the following steps: a. Add 100 parts pentaerythritol triacrylate, 30 parts dichloromethane, 30 parts benzotriazole, and 4 parts 2-hydroxy-2-methyl-1-phenyl-1-propanone to a 250 mL beaker and vortex to mix thoroughly to obtain the oil phase. Add 32.5 parts deionized water and 20 parts Tween-60 to a centrifuge tube and vortex to mix thoroughly to obtain the aqueous phase. Mix the oil phase and the aqueous phase thoroughly to obtain an emulsion. b. Slowly add 15 parts of sodium p-styrene sulfonate to the aqueous phase of the emulsion and stir. Then place the emulsion under a UV-LED ultraviolet light source to cure for 5 min. Use deionized water and anhydrous ethanol alternately to wash away unreacted sodium p-styrene sulfonate to prepare sulfonated mononuclear microcapsules. c. Add 10 parts of aniline dropwise to 1500 parts of an aqueous dispersion containing 100 parts of sulfonated mononuclear microcapsules, and stir continuously to allow aniline to be completely adsorbed onto the surface of the mononuclear microcapsules. Then, under ice bath (2-3 ℃) conditions, add dropwise an aqueous solution containing 200 parts of an initiator containing 12.25 parts of ammonium persulfate and 100 parts of phosphoric acid to initiate the polymerization of aniline. After reacting under ice bath conditions for 24 h, the polyaniline mononuclear microcapsules are obtained after sedimentation and washing. The preparation method of the self-healing anti-corrosion coating includes the following steps: 7.8 parts of the above-mentioned polyaniline mononuclear microcapsules were added to an aqueous coating composed of 78 parts of waterborne epoxy resin (LLA-10, Jiangsu Lanling Chemical Group Co., Ltd.) and 20 parts of amine curing agent (LLA-119, Jiangsu Lanling Chemical Group Co., Ltd.), and cured at 70 °C for 4 hours to obtain a polyaniline mononuclear microcapsule-based self-healing anti-corrosion coating.

[0052] Test example: (1) Total internal reflection Fourier transform infrared test The sample was dried and ground before testing, and the total internal reflection wavelength scanning range was 4000-550 cm⁻¹. -1 The image resolution is 4 cm. -1 The number of scans was 32. The polyaniline polynuclear microcapsules prepared in Example 1 ( p The infrared spectrum of -HDDA / PANI@BTA is as follows: Figure 1 As shown. By Figure 1 It can be seen that the infrared spectrum of pure polyaniline (PANI) is 1579 cm⁻¹ -1 and 1492 cm -1 The absorption peaks at 1300 cm⁻¹ correspond to the C=N and C=C stretching vibration absorption peaks, respectively. -1 The absorption peak at 1153 cm⁻¹ is related to the CN stretching of secondary aromatic amines, and also to the absorption peak at 1153 cm⁻¹. -1 The absorption peak at 1206 cm⁻¹ is related to the bending vibration of the CH plane. -1 and 740 cm -1 The absorption peaks at these locations correspond to the stretching vibration of N=N and the vibration of the benzene ring in the BTA molecule, respectively. For p -HDDA / PANI@BTA multinuclear microcapsules, the characteristic absorption peak of BTA can be observed in their FT-IR spectrum, proving that p - Successful preparation of HDDA / PANI@BTA multinuclear microcapsules and effective loading of BTA.

[0053] (2) Scanning electron microscopy test The microcapsules prepared in Comparative Example 2 and Example 1 were characterized by SEM. The polyaniline polynuclear microcapsules prepared in Example 1 are as follows: Figure 2 As shown. Figure 2 It can be seen that the microcapsules have a regular spherical structure and a polymer layer grown on their surface. Furthermore, observing the interior of the damaged microcapsules reveals a distinct multinucleated structure. The polyaniline mononuclear microcapsules prepared in Comparative Example 2 are as follows... Figure 3 As shown. Figure 3 It can be seen that the microcapsules have a regular spherical structure and a polymer layer grown on the surface. In addition, when observing the inside of the damaged microcapsules, a distinct mononuclear structure can be observed inside the microcapsules.

[0054] (3) Test of sustained-release performance of polyaniline polynuclear microcapsules The release behavior of the microcapsules prepared in Comparative Example 2 and Example 1 was investigated using ultraviolet spectroscopy. 100 mg of microcapsules were placed in dialysis bags and then in 150 mL of NaCl aqueous solution (3.5 wt%). The intensity of the ultraviolet absorption peak of BTA in the aqueous solution was monitored at regular intervals. The release of BTA was determined using a concentration-absorbance standard curve of BTA in NaCl solution. The test results are as follows: Figure 4 As shown. By Figure 4 It is evident that the polyaniline polynuclear microcapsules prepared in Example 1 possess a longer-lasting sustained-release capability. Since mononuclear microcapsules consist of a single core encapsulated within a single-layer wall material, the core material only needs to pass through this single-layer wall material to diffuse to the outside, resulting in a short mass transfer path and a tendency for initial burst release. In contrast, in polynuclear microcapsules, the release of the core material requires a two-stage diffusion process: "inside the small core → local wall material → overall wall material matrix → microcapsule surface," significantly extending the diffusion path.

[0055] (4) Corrosion resistance test of self-healing anti-corrosion coating The corrosion resistance of the self-healing anti-corrosion coatings prepared in Comparative Examples 1, 2, and 1 was tested using a neutral salt spray test. The back and edges of the coated low-carbon steel plates were sealed with waterproof tape, and the gaps were then sealed with a mixture of paraffin and rosin. Q... Labs' Q FOG SSP Type 600 circulating corrosion salt spray chamber, conforming to standard GB / T1771 The 2007 standard, "Determination of Neutral Salt Spray Resistance of Paints and Varnishes," included a salt spray test. The NaCl solution concentration used in the salt spray test was 5 wt%, the test temperature was 35℃, and the pressure inside the salt spray chamber was 10 kPa. The test results are as follows: Figure 5 , 6 As shown. By Figure 5 , 6It is evident that the polyaniline polynuclear microcapsule coating prepared in Example 1 exhibits superior anti-corrosion performance. This is because the coating loaded with BTA from polyaniline polynuclear microcapsules demonstrates better anti-corrosion performance. The core reason lies in the synergistic effect formed by the polynuclear structure, the electrochemical properties of polyaniline, and the protective performance of the coating. The polynuclear structure enables BTA to achieve batch-based long-term release through multi-level diffusion, avoiding the initial burst release problem of mononuclear structures and continuously replenishing the corrosion inhibitor as corrosion progresses. Furthermore, polyaniline can further regulate the BTA release rate through its electrochemical response to the corrosive microenvironment, precisely inhibiting the corrosion reaction. Simultaneously, the small core dispersion characteristics of the polynuclear microcapsules allow for a more uniform distribution of the polyaniline wall material in the coating, improving coating density, reducing corrosive media penetration, and ensuring that the electrochemical anti-corrosion sites of polyaniline are distributed throughout the coating, forming a synergistic effect of "electrochemical protection + chemical corrosion inhibition" with BTA.

[0056] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing polyaniline polynuclear microcapsules loaded with a corrosion inhibitor, characterized in that, Includes the following steps: S1, weigh out the photocurable material, photoinitiator, organic solvent and corrosion inhibitor and mix them evenly as the oil phase, take the aqueous dispersion of the emulsifier as the aqueous phase, mix the oil phase and the aqueous phase and emulsify them once to obtain an oil-in-water emulsion. S2, Sodium p-styrene sulfonate was added to the oil-in-water emulsion. After complete dissolution, it was cured by ultraviolet light. Then, it was washed alternately with anhydrous ethanol and deionized water to obtain wet sulfonated polymer polynuclear microcapsules. Subsequently, it was transferred to deionized water and sonicated to uniformly disperse the microcapsules to obtain an aqueous dispersion of sulfonated polymer polynuclear microcapsules. S3, aniline is added dropwise to an aqueous dispersion of sulfonated polymer polynuclear microcapsules, stirred, and then an aqueous initiator containing protic acid is added dropwise under ice bath conditions to initiate aniline polymerization. After reacting under ice bath conditions for 12-36 h, the polyaniline polynuclear microcapsules are obtained by sedimentation and washing.

2. The preparation method according to claim 1, characterized in that, In step S1, the photocurable material is one or more of pentaerythritol triacrylate, dipentaerythritol pentaacrylate, N,N'-methylenebisacrylamide, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate; its Hansen solubility δ p It is 6-18; The organic solvent is one or more of cyclohexane, n-hexane, petroleum ether, and n-heptane; its Hansen solubility δ p It is 0.

3. The preparation method according to claim 1, characterized in that, In step S1, the photoinitiator is one or more of 2-hydroxy-2-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, bis(1-(2,4-difluorophenyl)-3-pyrrolithium)dicenoctane, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone; The corrosion inhibitor is one or more of the following: methylbenzotriazole, 2-mercaptobenzothiazole, 2-mercaptobenzoimidazol, 2-mercaptobenzoxazole, benzotriazole, oleic acid imidazoline, butylbenzotriazole, and thiadiazole.

4. The preparation method according to claim 1, characterized in that, In step S1, the oil phase composition by weight is: 80-100 parts of photocurable material, 1-4 parts of photoinitiator, 20-50 parts of organic solvent, and 10-30 parts of corrosion inhibitor. The aqueous phase is an aqueous dispersion of emulsifier with a mass concentration of 0.5-5%; the emulsifier in the aqueous phase is one or more of the following: polyvinyl alcohol, polyethylene glycol, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polystyrene-maleic anhydride copolymer, Tween-60, Tween-80, Span-60, Span-80, hexadecyltrimethylammonium bromide, gelatin, and gum arabic. The mass ratio of the oil phase to the water phase is 4:1 to 1:

4.

5. The preparation method according to claim 1, characterized in that, In step S2, 15-25 parts by weight of sodium styrene sulfonate are used; the UV curing conditions are: wavelength 230-420 nm, curing time 1-10 min.

6. The preparation method according to claim 1, characterized in that, In step S3, the protic acid is one or more of hydrochloric acid, sulfuric acid, phytic acid, and phosphoric acid; the initiator is one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, and potassium permanganate; the molar ratio of the initiator to aniline is 1:2-4:1; the mass ratio of aniline to sulfonated polymer polynuclear microcapsules is 1:20-1:2; and the mass ratio of the protic acid to aniline is 10:1-1:

1.

7. A polyaniline polynuclear microcapsule loaded with a corrosion inhibitor prepared by the preparation method according to any one of claims 1-6.

8. The polyaniline polynuclear microcapsules loaded with corrosion inhibitor according to claim 7, characterized in that, The shell material includes polyaniline and photocurable material. The polyaniline multinuclear microcapsules have a particle size of 5-30 μm, a wall thickness of 1.3-2.5 μm, a micronuclear unit particle size of 0.5-3 μm, and a corrosion inhibitor loading rate of 30%-60%.

9. A self-healing anti-corrosion coating comprising polyaniline polynuclear microcapsules loaded with the corrosion inhibitor as described in claim 8, characterized in that, The coating consists of polyaniline polynuclear microcapsules loaded with corrosion inhibitors and film-forming resins, with the polyaniline polynuclear microcapsules loaded with corrosion inhibitors accounting for 5-15 wt% of the total coating mass.

10. A coating obtained from the self-healing anti-corrosion coating of claim 9, characterized in that, It is obtained by adding polyaniline polynuclear microcapsules loaded with corrosion inhibitors into a film-forming resin and then curing it.

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