Graphene-modified water-based anti-corrosion coating for marine steel structures and preparation method thereof

Abstract

The present invention belongs to the technical field of preparation of anti-corrosion coatings, and provides a graphene-modified water-based anti-corrosion coating for marine steel structures and a preparation method thereof. Polyaniline nanofibers are prepared by reacting aniline with ammonium persulfate and p-toluenesulfonic acid, and then modified with ammonium orthomolybdate; SiO2 nanopowder is silanized and modified with GPTMS, and then composited with modified polyaniline nanofibers to obtain a PANI-SiO2 composite material; nitrogen and sulfur co-doped graphene is prepared by heat treatment with thiourea and urea, and intercalation and silanization modification of graphene are achieved using an intercalation agent and KH560; a fluorine-containing segment prepolymer and a multifunctional copolymer segment are prepared, and a tetramercapto crosslinking agent is used to prepare a functionalized emulsion; the silane-modified graphene, the PANI-SiO2 composite material and the functionalized emulsion are sequentially added to a water-based epoxy resin system, and a leveling agent, a defoaming agent and a thickener are used to obtain a water-based anti-corrosion coating suitable for marine steel structures.

Description

Technical Field

[0001] The present invention belongs to the technical field of anti-corrosion coating preparation, and relates to a graphene-modified water-based anti-corrosion coating for marine steel structures and a preparation method thereof. Background Art

[0002] With the increasing frequency of marine development activities and the widespread use of steel structures in offshore engineering, corrosion issues have become increasingly prominent. Seawater contains high concentrations of chloride ions, dissolved oxygen, salt, and other corrosive substances. These factors combine to accelerate the corrosion of marine metal structures. Seawater is a highly conductive electrolyte, making metal structures susceptible to electrochemical corrosion in seawater, making the corrosion problem of marine steel structures particularly prominent. Seawater scouring corrosion is a combination of mechanical scouring and chemical corrosion, typically occurring in areas of marine structures exposed to high-speed currents, waves, or tides. High-velocity seawater exerts shear stress on metal surfaces, destroying the passive film or protective coating, exposing unprotected metal surfaces. Scouring exposes fresh metal to the corrosive environment and removes corrosion products (such as rust), perpetuating the corrosion process. Seawater scouring mechanically destroys the passive film or corrosion product layer on the metal surface, exposing the metal to the corrosive environment and significantly increasing the electrochemical corrosion rate. Furthermore, scouring removes corrosion products (such as rust or oxides), preventing their redeposition. This removal further accelerates the corrosion process.

[0003] At present, the main anti-corrosion measures for marine steel structures include coating protection, sacrificial anode protection, and impressed current protection. Coating protection is a commonly used method that isolates the metal from seawater by applying a layer of anti-corrosion coating on the metal surface, thereby achieving an anti-corrosion effect. However, traditional solvent-based anti-corrosion coatings have certain limitations in terms of water resistance and adhesion. Long-term use in marine environments can easily lead to bubbling and shedding, resulting in a decrease in anti-corrosion effectiveness. Sacrificial anode protection involves connecting a metal that is more active than the protected metal, such as magnesium, zinc, or aluminum alloy, to seawater, causing the active metal to corrode as the anode while the protected metal is protected as the cathode. However, the consumption rate of the sacrificial anode material is difficult to control and requires regular inspection and replacement. Water-based coatings have the advantages of being simple and easy to apply, fast drying, and good leveling during construction. They can improve construction efficiency and reduce construction costs, making water-based coatings have good application prospects in the field of marine steel structure anti-corrosion. As a new type of two-dimensional carbon nanomaterial, graphene has shown great application potential in the field of anti-corrosion coatings in recent years. Graphene has an ultra-high specific surface area and excellent barrier properties. Its lamellar structure can form a continuous, dense protective film in the coating, effectively preventing the penetration of corrosive media such as oxygen, water molecules, and chloride ions. At the same time, the interaction between graphene and the polymer matrix is ​​good, forming a strong interfacial bond with the matrix material in the water-based anti-corrosion coating, thereby enhancing the adhesion of the coating. Therefore, the development of a graphene-modified water-based anti-corrosion coating for marine steel structures is of great significance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a graphene-modified marine steel structure water-based anti-corrosion coating and its preparation method. First, polyaniline nanofibers are prepared by aniline oxidative polymerization and modified with ammonium orthomolybdate. SiO2 nanopowder is surface-modified using a silane coupling agent and composited with modified polyaniline to form a PANI-SiO2 composite material. Secondly, nitrogen and sulfur co-doped graphene is prepared by heat treatment with thiourea and urea. The graphene is further intercalated and silanized using an intercalating agent and KH560 to improve its dispersibility and interfacial bonding properties. Then, a fluorine-containing prepolymer segment and a multifunctional copolymer segment are prepared to prepare a functionalized emulsion, which gives the coating excellent hydrophobic and corrosion resistance. Finally, the silane-modified graphene, PANI-SiO2 composite material and functionalized emulsion are added to a water-based epoxy resin system to prepare a water-based anti-corrosion coating with superior performance, thereby meeting the needs of actual production.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures, the preparation method comprising:

[0007] S1, in an ice-water bath, aniline, p-toluenesulfonic acid, and ammonium persulfate solution are dispersed in deionized water while stirring, washed and filtered to obtain polyaniline nanofibers, and then the polyaniline nanofibers are immersed in ammonium orthomolybdate solution, stirred thoroughly, centrifuged, washed, and dried to obtain modified polyaniline nanofibers. SiO2 nanopowder and GPTMS are dispersed in anhydrous ethanol, adjusted to a first temperature, stirred and refluxed, filtered, washed, and vacuum-dried to obtain modified SiO2, and the modified polyaniline nanofibers and modified SiO2 are dispersed in deionized water, adjusted to a second temperature and adjusted to pH 7, stirred for reaction, centrifuged, washed, and freeze-dried to obtain PANI-SiO2;

[0008] S2, dispersing graphene, thiourea and urea in deionized water, transferring the mixture to a reactor after ultrasonic dispersion and adjusting the temperature to a third temperature for reaction, washing the product with a 1 wt.% KOH solution after completion of the reaction and drying to obtain N, S co-doped graphene powder, dispersing the N, S co-doped graphene powder and an intercalation agent in N-methylpyrrolidone, adjusting the temperature to a fourth temperature and stirring, filtering, washing and drying to obtain a partially intercalated graphene material, dispersing the partially intercalated graphene material and KH560 in an ethanol aqueous solution, adjusting the pH to 5 and the temperature to the second temperature, reflux reaction, centrifugation, washing and drying to obtain a silane-modified graphene powder;

[0009] S3, dispersing trifluoroethyl methacrylate and azobisisobutyronitrile in dimethyl sulfoxide, adjusting the temperature to the second temperature under a nitrogen atmosphere for reaction, adding ethanol for separation after the reaction to obtain a fluorine-containing segment prepolymer, dispersing N-vinyl pyrrolidone, 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride and azobisisobutyronitrile in dimethyl sulfoxide, adjusting the temperature to the second temperature under a nitrogen atmosphere for reaction with stirring, adding ethanol for separation after the reaction to obtain a multifunctional copolymer segment, dispersing the fluorine-containing segment prepolymer, the multifunctional copolymer segment and pentaerythritol tetrakis(3-mercaptopropionic acid) in dimethyl sulfoxide, adjusting the temperature to the fourth temperature for reaction with stirring to obtain a macromolecular solution, and then dispersing the macromolecular solution and Tween 80 in deionized water with stirring, adjusting the pH to 8 and the temperature to 70° C. for insulation to obtain a functionalized emulsion;

[0010] S4, add the leveling agent, defoaming agent and thickener to the water-based epoxy resin in sequence and mix them evenly, then add the silane-modified graphene powder, functionalized emulsion and PANI-SiO2 to the water-based epoxy resin in sequence, mix them evenly and add the curing agent when using to obtain a water-based anti-corrosion coating for marine steel structures based on graphene modification.

[0011] Polyaniline (PAI) is prepared using aniline monomer as the starting material and ammonium persulfate as the oxidant, achieving a chemical oxidative polymerization reaction. Ammonium persulfate decomposes in aqueous solution to generate reactive oxidative species such as sulfate radicals. These radicals oxidize the aniline monomer via an electron transfer mechanism to form aniline radical cations. Following the formation of radical cations, intermolecular coupling reactions drive the formation of linear PAI chains. By maintaining a low temperature in an ice-water bath, the rate of the radical reaction is effectively reduced, inhibiting unwanted side reactions such as excessive cross-linking or branching. Low temperature control also limits the rapid growth of PAI chains, allowing them to self-assemble into fibrous nanostructures. Their regularity and uniformity provide a crucial structural foundation for subsequent surface modification and the dispersibility of composite materials. During the PAI oxidative polymerization reaction, p-toluenesulfonic acid (p-toluenesulfonic acid) is introduced as a dopant. Its primary function is to convert PAI into a conductive state through a protonation mechanism. P-toluenesulfonic acid is a strongly acidic compound. Its sulfonic acid groups electrostatically bind to the amine and imine groups on the PAI molecular chains, protonating these groups and forming ion pairs. Protonated polyaniline exhibits high conductivity, allowing electrons to move freely along the molecular chain. Furthermore, the solubility and dispersibility of the doped polyaniline are significantly improved, making it easier to mix evenly with other components during the subsequent preparation process.

[0012] Further functionalization of the polyaniline nanofibers was achieved using an ammonium orthomolybdate solution, aiming to impart enhanced chemical stability and electrochemical activity to the polyaniline while also improving its dispersibility in composite materials. Under alkaline conditions, the molybdate ions in the ammonium orthomolybdate solution electrostatically bind to the protonated amine and imine groups on the polyaniline chains, forming stable ion pairs. This ion pair formation further enhances the polyaniline's conductivity and surface activity. Furthermore, the molybdate ions may interact with nitrogen atoms on the polyaniline molecular chains through hydrogen bonds, further enhancing the chemical stability of the polyaniline surface. This surface modification forms a functional molybdenum-centered protective layer on the polyaniline fibers. This layer not only enhances the material's antioxidant capacity but also reduces its degradation rate in corrosive environments, thereby improving the durability and environmental adaptability of the polyaniline. The introduction of molybdate ions alters the charge distribution on the polyaniline fiber surface, increasing the electrostatic repulsion between fibers and effectively preventing nanofiber aggregation. In addition, the combination of molybdate and polyaniline molecules provides more active sites on the fiber surface, which can interact with water molecules or other polar solvent molecules, thereby improving the dispersion stability of polyaniline in the aqueous phase system.

[0013] The silica nanopowder was modified using γ-glycidoxypropyltrimethoxysilane (GPTMS). GPTMS is a functionalized silane whose trimethoxysilane groups undergo hydrolysis and condensation with hydroxyl groups on the silica surface, forming silane-oxygen bonds while retaining its epoxy groups on the surface as active sites. Heating and refluxing the mixture in anhydrous ethanol allowed the GPTMS to fully react with the silica surface, thus achieving surface functionalization. The modified silica not only better bonded with polyaniline but also exhibited increased hydrophilicity and dispersibility, enabling uniform distribution within the composite and enhancing the mechanical properties. The modified polyaniline nanofibers were mixed with the modified silica powder in deionized water. This process resulted in the composite of polyaniline and silica through electrostatic and intermolecular interactions. The conductive properties of the modified polyaniline synergistically interacted with the mechanical properties of silica, resulting in excellent corrosion resistance in the PANI-SiO2 composite. Polyaniline, through its redox activity, provides cathodic protection on metal surfaces, while silica, as an inorganic filler, provides a physical barrier within the coating, preventing the penetration of corrosive media. This multi-layered protection mechanism delays the onset of corrosion and enhances the coating's long-term protective capabilities.

[0014] In the nitrogen-sulfur co-doping process, graphene sheets are dispersed in an aqueous solution and mixed with thiourea and urea for a hydrothermal reaction. Graphene has a highly π-conjugated two-dimensional structure, and its chemical activity is primarily concentrated at the edges and defect regions of the sheets, which typically bear polar functional groups such as hydroxyl, carboxyl, or epoxy groups. However, strong van der Waals forces between graphene sheets cause them to easily aggregate in solution. Therefore, physical exfoliation induced by ultrasonic treatment can be used to disperse the sheets into single or few-layer structures. Under the hydrothermal reaction conditions, thiourea and urea decompose to produce various reactive intermediates. These intermediates can react chemically with active sites on the graphene surface or edges to form nitrogen- and sulfur-doped structures. Nitrogen doping improves graphene's conductivity by introducing different types of nitrogen groups into the graphene carbon skeleton, while also enhancing its resistance to oxidants in corrosive media. Sulfur doping, on the other hand, introduces thiol, thioether, or sulfide structures onto the graphene surface, making it more hydrophilic and chemically active. The presence of sulfur can also enhance the polarity and surface energy of graphene, promote its dispersion in aqueous systems, and further improve its chemical bonding ability with metal surfaces. Nitrogen and sulfur co-doping has a synergistic effect in terms of corrosion resistance. Nitrogen doping increases the electron cloud density of graphene, enabling it to act as an electron donor during the corrosion process, providing cathodic protection for the metal surface. Sulfur doping, through chemical reactions with oxygen molecules or ions in the corrosive medium, forms a passivation film on the graphene surface, thereby preventing further penetration of the corrosive medium. This synergistic protection mechanism not only delays the corrosion behavior of the metal matrix but also provides a better interfacial chemical foundation for subsequent modification.

[0015] In phosphonate intercalation modification, nitrogen- and sulfur-codoped graphene reacts with an intercalant in an organic solvent. The intercalant is an amphiphilic molecule whose structural characteristics enable it to selectively bind to the graphene surface. Phosphonate groups can strongly interact with carboxyl or hydroxyl groups on the graphene surface through chemical adsorption or bonding, thereby achieving intercalation modification. Silane groups, through further hydrolysis and condensation reactions, introduce additional chemical bridges between graphene sheets. This intercalation not only increases the spacing between graphene sheets but also reduces the van der Waals forces between them, significantly improving the dispersibility of graphene in solution. The contribution of intercalation modification to anti-corrosion performance and interfacial bonding performance is mainly reflected in two aspects: first, intercalation modification significantly reduces the penetration rate of corrosive media in the coating by constructing physical and chemical barriers between graphene sheets. This barrier effect is one of the key mechanisms for graphene materials to play a role in anti-corrosion coatings; second, phosphonate groups can form a strong chemical bond with the metal surface, thereby improving the adhesion of the coating to the metal substrate. This enhanced adhesion not only improves the mechanical properties of the coating, but also significantly extends the service life of the coating.

[0016] The intercalated graphene is refluxed with the silane coupling agent KH560 in a water-ethanol mixture to complete the silane modification. KH560's molecular structure contains both trimethoxysilane and epoxy groups. The trimethoxysilane groups can hydrolyze to generate silanols, which then undergo condensation reactions with hydroxyl or carboxyl groups on the graphene surface to form stable silicon-oxygen bonds. The KH560 molecules are firmly fixed to the graphene surface, while their unreacted epoxy groups are exposed. The epoxy groups serve as active sites, allowing them to undergo cross-linking reactions with the resin matrix during the subsequent coating preparation process, thereby enhancing the interfacial bonding between the graphene and the coating matrix. Silane modification forms a protective functional coating on the surface of graphene through chemical bonding, which enhances the chemical corrosion resistance of graphene and further improves its stability in complex environments; secondly, silane modification provides graphene with additional chemically active sites, enabling it to achieve better compatibility and bonding with other coating components; silane modification also significantly improves the dispersibility of graphene, enabling it to be evenly distributed in the coating system to form a dense barrier structure, while reducing the agglomeration of flakes.

[0017] A fluorinated segment prepolymer was prepared using trifluoroethyl methacrylate as a monomer via free radical polymerization initiated by azobisisobutyronitrile (AIBN). Trifluoroethyl methacrylate is a fluorinated monomer with highly polar fluorine atoms bonded within its molecular structure, which imparts high hydrophobicity and low surface energy. During polymerization, AIBN decomposes to generate free radicals, which, through chain initiation, chain propagation, and chain termination, convert trifluoroethyl methacrylate into a linear polymer with a specific molecular weight. Fluorine atoms, due to their high electronegativity and large size, significantly reduce the surface free energy of the material, resulting in the fluorinated segment prepolymer exhibiting excellent hydrophobicity and anti-fouling properties. This hydrophobicity effectively prevents the penetration of water and corrosive ions, forming a primary barrier in the coating. A multifunctional copolymer segment was prepared via AIBN-initiated free radical polymerization using N-vinyl pyrrolidone (NVP), 3-(methacryloyloxy)propyltrimethoxysilane (MPTS), and maleic anhydride as comonomers. NVP is a hydrophilic monomer containing a pyrrolidone ring in its molecular structure. This polar structure can significantly enhance the hydrophilicity and wettability of the copolymer. The introduction of NVP can improve the material's dispersibility in aqueous systems, making it more compatible and stable in water-based coatings. MPTS is a bifunctional silane monomer containing both a methacryloxy group, which can participate in free radical polymerization, and a trimethoxysilane group. The trimethoxysilane group can undergo hydrolysis and condensation during the subsequent coating curing process, forming a silicon-oxygen bond with the hydroxyl group or other active groups on the substrate surface. This chemical bond significantly enhances the adhesion between the coating and the substrate, thereby improving the mechanical properties and durability of the coating. The introduction of maleic anhydride further increases the functional group density of the copolymer. Its anhydride groups can chemically react with metal surfaces or other coating components to form stable chemical bonds, enhancing the interfacial bonding ability of the copolymer. At the same time, its polar anhydride structure also improves the corrosion resistance of the coating.

[0018] A fluorinated prepolymer, a multifunctional copolymer, and pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) were mixed to form a macromolecular structure via a thiol-ene click chemistry reaction. Under high temperature, the thiol groups undergo homolytic cleavage to generate thiol radicals, which react with double bonds on the olefinic bond to form a stable C-S bond. PETMP is a multifunctional thiol compound containing four thiol groups in its molecular structure, enabling cross-linking with double bonds in the fluorinated and multifunctional copolymer segments to form a highly cross-linked macromolecular structure. This cross-linking not only increases the molecular weight and mechanical strength of the material but also imparts enhanced chemical stability and weather resistance. The introduction of the fluorinated prepolymer imparts hydrophobicity and low surface energy at one end of the macromolecular chain, while the multifunctional copolymer segment, through its combination of hydrophilic and reactive functional groups, enhances the material's interfacial bonding and dispersibility. This two-segment macromolecular structure achieves a balance of hydrophobicity and hydrophilicity, enabling the material to exhibit excellent hydrophobic and anti-corrosion properties in coating systems while maintaining compatibility with other coating components. The functionalized emulsion was prepared by mixing the macromolecular solution with the emulsifier Tween 80 and dispersing it in deionized water. The fluorinated segments in the functionalized emulsion provide low surface energy and hydrophobicity, reducing the adhesion and penetration of corrosive media. The multifunctional copolymer segments enhance the interfacial bonding between the coating and the substrate through a chemical reaction between maleic anhydride and silane groups. The thiol-ene crosslinking structure enhances the mechanical properties and durability of the coating by increasing the intermolecular crosslinking density.

[0019] The primary function of the PANI-SiO2 composite is to provide both a redox barrier and a physical barrier. Modified polyaniline (PANI) creates a cathodic protection effect on metal surfaces through its electrical conductivity and redox activity. When corrosive media penetrate the coating, PANI forms a protective oxide film on the metal surface through redox cycles, reducing the occurrence of metal oxidation reactions. The introduction of ammonium orthomolybdate further enhances this effect. Molybdate ions bind to the metal surface to form a passivation film, reducing the corrosion rate. SiO2 nanoparticles act as an inorganic barrier to block the diffusion path of the corrosive media. Their high dispersibility and surface activity allow them to be evenly distributed in the coating matrix, thereby improving the coating's density and permeability resistance. The composite structure between PANI and SiO2 also increases the coating's mechanical strength and durability. The two-dimensional lamellar structure of silane-modified graphene powder possesses an extremely high specific surface area and excellent barrier properties, forming a dense physical barrier within the coating. Nitrogen and sulfur co-doping further enhances the conductivity and chemical activity of graphene, enabling it to assist the redox barrier effect of PANI-SiO2 and enhance cathodic protection of metal surfaces. Furthermore, silane modification introduces silicon-containing and epoxy groups, enabling chemical crosslinking of graphene with the epoxy resin matrix, thereby enhancing the coating's adhesion and interfacial stability. Modification with the silane coupling agent also improves the dispersibility of graphene in aqueous systems, ensuring its uniform distribution within the coating.

[0020] Functionalized emulsions provide hydrophobicity, corrosion protection, and enhanced interfacial adhesion through molecular design. The fluorinated segments within the emulsion impart low surface energy and excellent hydrophobicity to the coating, effectively preventing the adsorption and penetration of water and corrosive ions. The multifunctional copolymer segments enhance the emulsion's dispersibility in aqueous systems through the hydrophilicity of N-vinylpyrrolidone (NVP). Furthermore, chemical crosslinking with the coating matrix through silane groups and maleic anhydride structures strengthens interfacial adhesion and enhances the coating's mechanical properties. The emulsion's wettability control capabilities enhance the coating's spreadability on the substrate surface, ensuring a uniform coating and reducing coating defects. The three materials enhance coating performance through multiple synergistic interactions. The two-dimensional barrier of silane-modified graphene and the inorganic barrier of PANI-SiO2 complement each other, forming a multi-layered anti-corrosion barrier structure. The conductive polyaniline in PANI-SiO2 combines with the conductivity of silane-modified graphene to further enhance the coating's cathodic protection. The fluorinated hydrophobic segments of the functionalized emulsion work synergistically with the barrier effect of silane-modified graphene to form a dual protective structure with a hydrophobic surface and internal barrier, effectively reducing the adsorption of corrosive media. The silane groups in the emulsion also chemically cross-link with the SiO2 particles in PANI-SiO2 and the surface active groups of silane-modified graphene, enhancing the overall structural stability and interfacial bonding of the coating.

[0021] As a preferred technical solution of the present invention, in S1, the mass ratio of aniline, p-toluenesulfonic acid and ammonium persulfate solution is 20:5:125.

[0022] In some optional embodiments, the mass fraction of the ammonium persulfate solution is 20 wt.%.

[0023] In some optional embodiments, the stirring time is 10-12h, for example, it can be 10h, 10.2h, 10.4h, 10.6h, 10.8h, 11h, 11.2h, 11.4h, 11.6h, 11.8h or 12h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In some optional embodiments, the mass fraction of the ammonium orthomolybdate solution is 5 wt.%, and the solution pH is 8.

[0025] In some optional embodiments, the mass volume ratio of the SiO2 nanopowder, GPTMS and anhydrous ethanol is 10g:5mL:50mL.

[0026] In some optional embodiments, the first temperature is 80-90°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] In some optional embodiments, the stirring reflux time is 2-3h, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] In some optional embodiments, the mass ratio of the modified polyaniline nanofibers to the modified SiO2 is 2:1.

[0029] In some optional embodiments, the second temperature is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] In some optional embodiments, the stirring reaction time is 5-6h, for example, it can be 5h, 5.1h, 5.2h, 5.3h, 5.4h, 5.5h, 5.6h, 5.7h, 5.8h, 5.9h or 6h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] As a preferred technical solution of the present invention, in S2, the mass ratio of graphene, thiourea and urea is 10:10:8.

[0032] In some optional embodiments, the third temperature is 180-190°C, for example, it can be 180°C, 181°C, 182°C, 183°C, 184°C, 185°C, 186°C, 187°C, 188°C, 189°C or 190°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In some optional embodiments, the third temperature reaction time is 12-13h, for example, it can be 12h, 12.1h, 12.2h, 12.3h, 12.4h, 12.5h, 12.6h, 12.7h, 12.8h, 12.9h or 13h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional embodiments, the mass volume ratio of the N, S co-doped graphene powder, the intercalation agent and N-methylpyrrolidone is 8 g:5 g:100 mL.

[0035] In some optional embodiments, the intercalant is Dynasylan® 1189.

[0036] In some optional embodiments, the fourth temperature is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In some optional embodiments, the stirring time at the fourth temperature is 8-9h, for example, it can be 8h, 8.1h, 8.2h, 8.3h, 8.4h, 8.5h, 8.6h, 8.7h, 8.8h, 8.9h or 9h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In some optional embodiments, the mass volume ratio of the partially intercalated graphene material to KH560 is 8 g:3 mL.

[0039] In some optional embodiments, the reflux reaction time is 2-3h, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] As a preferred technical solution of the present invention, in S3, the mass ratio of trifluoroethyl methacrylate to azobisisobutyronitrile is 15:0.5.

[0041] In some optional embodiments, the second temperature reaction time is 4-5h, for example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] In some optional embodiments, the mass ratio of N-vinyl pyrrolidone, 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, and azobisisobutyronitrile is 10g:10g:10g:1g.

[0043] In some optional embodiments, the second temperature stirring reaction time is 4-5h, for example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In some optional embodiments, the mass ratio of the fluorine-containing segment prepolymer, the multifunctional copolymer segment and pentaerythritol tetrakis(3-mercaptopropionate) is 2:2:1.

[0045] In some optional embodiments, the fourth temperature stirring reaction time is 10-12h, for example, it can be 10h, 10.2h, 10.4h, 10.6h, 10.8h, 11h, 11.2h, 11.4h, 11.6h, 11.8h or 12h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some optional embodiments, the mass volume ratio of the macromolecular solution to Tween 80 is 70 mL:1 g.

[0047] In some optional embodiments, the insulation time is 1-2h, for example, it can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] As a preferred technical solution of the present invention, in S4, the mass ratio of the leveling agent, defoaming agent, thickener, water-based epoxy resin, silane-modified graphene powder, functionalized emulsion and PANI-SiO2 is 0.5:0.5:2:200:3:15:5.

[0049] In a second aspect, the present invention provides a graphene-modified water-based anti-corrosion coating for marine steel structures prepared by the preparation method described in the first aspect.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) the conductive properties of modified polyaniline and the mechanical properties of silicon dioxide form a synergistic effect in the composite material, so that the PANI-SiO2 composite material exhibits excellent corrosion resistance. Polyaniline can form a cathodic protection effect on the metal surface through its redox activity. At the same time, silicon dioxide as an inorganic filler can provide a physical barrier effect in the coating to prevent the penetration of corrosive media; (2) The two-dimensional sheet structure of graphene has an extremely high specific surface area and excellent barrier properties. The graphene sheet can extend the diffusion path of the corrosive medium and reduce the possibility of moisture, oxygen and corrosive ions penetrating into the metal interface. Nitrogen doping increases the electron cloud density of graphene, providing cathodic protection for the metal surface. Sulfur doping can effectively prevent the penetration of corrosive media. Doping forms a passivation film on the graphene surface by chemically reacting with oxygen molecules or ions in the corrosive medium. Silane modification introduces silicon-oxygen bonds and epoxy groups on the graphene surface, enabling it to undergo chemical cross-linking reactions with the coating matrix. The chemical combination of silicon-oxygen bonds enhances the interfacial stability of the coating, while the epoxy groups can further react with the epoxy resin matrix to improve the adhesion of the coating. (3) The introduction of fluorine-containing prepolymers in the functionalized emulsion reduces the free energy of the coating surface, making the coating exhibit excellent hydrophobicity and anti-fouling properties. The multifunctional copolymer segments undergo chemical cross-linking with the substrate through silane groups and maleic anhydride structures, enhancing the adhesion of the coating. The thiol-ene cross-linking structure improves the mechanical properties and durability of the coating by increasing the cross-linking density between molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Flowchart of the method for preparing the graphene-modified water-based anti-corrosion coating for marine steel structures provided in Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0052] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0053] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products and have not been subjected to any further purification treatment.

[0054] Example 1

[0055] like Figure 1 As shown, this embodiment provides a method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification, and the preparation method specifically comprises the following steps:

[0056] S1, ice water bath, disperse 20g aniline, 5g p-toluenesulfonic acid and 125g, 20wt.% ammonium persulfate solution in 200mL deionized water and keep stirring for 10.6h, wash and filter to obtain polyaniline nanofibers, then immerse the polyaniline nanofibers in 5wt.% ammonium orthomolybdate solution, stir thoroughly, centrifuge, wash and dry to obtain modified polyaniline nanofibers. Disperse 10g SiO2 nanopowder and 5mL GPTMS in 50mL anhydrous ethanol, adjust to 88℃, stir and reflux for 2.0h, filter, wash and vacuum dry to obtain modified SiO2, disperse 20g modified polyaniline nanofibers and 10g modified SiO2 in 100mL deionized water, adjust the temperature to 54℃ and adjust the pH to 7, stir and react for 5.3h, centrifuge and wash, freeze-dry to obtain PANI-SiO2;

[0057] S2, 10g of graphene, 10g of thiourea and 8g of urea were dispersed in 100mL of deionized water, transferred to a reactor after ultrasonic dispersion and adjusted to 188°C for reaction for 12.4h. After the reaction, the product was washed with 1wt.% KOH solution and dried to obtain N,S co-doped graphene powder, 8g of N,S co-doped graphene powder and 5g of intercalation agent were dispersed in 100mL of N-methylpyrrolidone, the temperature was adjusted to 74°C and stirred for 8.2h, filtered, washed and dried to obtain partially intercalated graphene material, 8g of partially intercalated graphene material and 3mL of KH560 were dispersed in 50mL of ethanol aqueous solution, the pH was adjusted to 5 and the temperature was adjusted to 55°C, refluxed for 2.2h, centrifuged, washed and dried to obtain silane-modified graphene powder;

[0058] S3, 15g of trifluoroethyl methacrylate and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 50℃ under nitrogen atmosphere and the reaction was carried out for 4.0h. After the reaction, ethanol was added for separation to obtain a fluorinated segment prepolymer. 5g of N-vinyl pyrrolidone, 5g of 3-methacryloyloxypropyltrimethoxysilane, 5g of maleic anhydride and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 55℃ under nitrogen atmosphere and the reaction was stirred for 4.2h. After the reaction was completed, ethanol was added for separation to obtain a multifunctional copolymer segment. 10g of the fluorinated segment prepolymer, 10g of the multifunctional copolymer segment and 5g of pentaerythritol tetrakis(3-mercaptopropionic acid) were dispersed in 30mL of dimethyl sulfoxide, the temperature was adjusted to 77℃ and the reaction was stirred for 11.8h to obtain a macromolecular solution. 70mL of the macromolecular solution was then mixed with 1g of Tween 80 was dispersed into 200 mL of deionized water and stirred, the pH was adjusted to 8 and the temperature was adjusted to 70 °C for 1.6 h to obtain a functionalized emulsion;

[0059] S4, add 0.5g of leveling agent, 0.5g of defoaming agent, and 2g of thickener to 200g of water-based epoxy resin in sequence and mix evenly, then add 3g of silane-modified graphene powder, 15g of functionalized emulsion and 5g of PANI-SiO2 to the water-based epoxy resin in sequence, mix evenly, and add curing agent when used to obtain a graphene-modified marine steel structure water-based anti-corrosion coating.

[0060] Example 2

[0061] This embodiment provides a method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification, and the preparation method specifically comprises the following steps:

[0062] S1, ice water bath, disperse 20g aniline, 5g p-toluenesulfonic acid and 125g, 20wt.% ammonium persulfate solution in 200mL deionized water and keep stirring for 10.0h, wash and filter to obtain polyaniline nanofibers, then immerse the polyaniline nanofibers in 5wt.% ammonium orthomolybdate solution, stir thoroughly, centrifuge, wash and dry to obtain modified polyaniline nanofibers. Disperse 10g SiO2 nanopowder and 5mL GPTMS in 50mL anhydrous ethanol, adjust to 80℃, stir and reflux for 2.6h, filter, wash and vacuum dry to obtain modified SiO2, disperse 20g modified polyaniline nanofibers and 10g modified SiO2 in 100mL deionized water, adjust the temperature to 50℃ and adjust the pH to 7, stir and react for 5.0h, centrifuge and wash, freeze-dry to obtain PANI-SiO2;

[0063] S2, 10g of graphene, 10g of thiourea and 8g of urea were dispersed in 100mL of deionized water, transferred to a reactor after ultrasonic dispersion and adjusted to 180°C for reaction for 12.0h, and after the reaction, the product was washed with 1wt.% KOH solution and dried to obtain N,S co-doped graphene powder, 8g of N,S co-doped graphene powder and 5g of intercalation agent were dispersed in 100mL of N-methylpyrrolidone, the temperature was adjusted to 70°C and stirred for 8.4h, filtered, washed and dried to obtain partially intercalated graphene material, 8g of partially intercalated graphene material and 3mL of KH560 were dispersed in 50mL of ethanol aqueous solution, the pH was adjusted to 5 and the temperature was adjusted to 51°C, refluxed for 2.8h, centrifuged, washed and dried to obtain silane-modified graphene powder;

[0064] S3, 15g of trifluoroethyl methacrylate and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 57°C in a nitrogen atmosphere and the reaction was carried out for 4.8h. After the reaction, ethanol was added for separation to obtain a fluorinated segment prepolymer. 5g of N-vinyl pyrrolidone, 5g of 3-methacryloyloxypropyltrimethoxysilane, 5g of maleic anhydride and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 50°C in a nitrogen atmosphere and the reaction was stirred for 4.0h. After the reaction was completed, ethanol was added for separation to obtain a multifunctional copolymer segment. 10g of the fluorinated segment prepolymer, 10g of the multifunctional copolymer segment and 5g of pentaerythritol tetrakis(3-mercaptopropionic acid) were dispersed in 30mL of dimethyl sulfoxide, the temperature was adjusted to 70°C and the reaction was stirred for 10.0h to obtain a macromolecular solution. 70mL of the macromolecular solution was then mixed with 1g of Tween 80 was dispersed into 200 mL of deionized water and stirred, the pH was adjusted to 8 and the temperature was adjusted to 70 °C for 1.0 h to obtain a functionalized emulsion;

[0065] S4, add 0.5g of leveling agent, 0.5g of defoaming agent, and 2g of thickener to 200g of water-based epoxy resin in sequence and mix evenly, then add 3g of silane-modified graphene powder, 15g of functionalized emulsion and 5g of PANI-SiO2 to the water-based epoxy resin in sequence, mix evenly, and add curing agent when used to obtain a graphene-modified marine steel structure water-based anti-corrosion coating.

[0066] Example 3

[0067] This embodiment provides a method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification, and the preparation method specifically comprises the following steps:

[0068] S1, ice water bath, disperse 20g aniline, 5g p-toluenesulfonic acid and 125g, 20wt.% ammonium persulfate solution in 200mL deionized water and keep stirring for 11.4h, wash and filter to obtain polyaniline nanofibers, then immerse the polyaniline nanofibers in 5wt.% ammonium orthomolybdate solution, stir thoroughly, centrifuge, wash and dry to obtain modified polyaniline nanofibers. Disperse 10g SiO2 nanopowder and 5mL GPTMS in 50mL anhydrous ethanol, adjust to 84℃, stir and reflux for 3.0h, filter, wash and vacuum dry to obtain modified SiO2, disperse 20g modified polyaniline nanofibers and 10g modified SiO2 in 100mL deionized water, adjust the temperature to 60℃ and adjust the pH to 7, stir and react for 5.7h, centrifuge and wash, freeze-dry to obtain PANI-SiO2;

[0069] S2, 10g of graphene, 10g of thiourea and 8g of urea were dispersed in 100mL of deionized water, ultrasonically dispersed, transferred to a reactor and the temperature was adjusted to 190°C for reaction for 12.7h. After the reaction, the product was washed with 1wt.% KOH solution and dried to obtain N,S co-doped graphene powder, 8g of N,S co-doped graphene powder and 5g of intercalation agent were dispersed in 100mL of N-methylpyrrolidone, the temperature was adjusted to 71°C and stirred for 9.0h, filtered, washed and dried to obtain partially intercalated graphene material, 8g of partially intercalated graphene material and 3mL of KH560 were dispersed in 50mL of ethanol aqueous solution, the pH was adjusted to 5 and the temperature was adjusted to 50°C, refluxed for 2.0h, centrifuged, washed and dried to obtain silane-modified graphene powder;

[0070] S3, 15g of trifluoroethyl methacrylate and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 53°C in a nitrogen atmosphere and the reaction was carried out for 5.0h. After the reaction, ethanol was added for separation to obtain a fluorinated segment prepolymer. 5g of N-vinyl pyrrolidone, 5g of 3-methacryloyloxypropyltrimethoxysilane, 5g of maleic anhydride and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 60°C in a nitrogen atmosphere and the reaction was stirred for 4.7h. After the reaction was completed, ethanol was added for separation to obtain a multifunctional copolymer segment. 10g of the fluorinated segment prepolymer, 10g of the multifunctional copolymer segment and 5g of pentaerythritol tetrakis(3-mercaptopropionic acid) were dispersed in 30mL of dimethyl sulfoxide, the temperature was adjusted to 74°C and the reaction was stirred for 12.0h to obtain a macromolecular solution. 70mL of the macromolecular solution was then mixed with 1g of Tween 80 was dispersed into 200 mL of deionized water and stirred, the pH was adjusted to 8 and the temperature was adjusted to 70 °C for 1.4 h to obtain a functionalized emulsion;

[0071] S4, add 0.5g of leveling agent, 0.5g of defoaming agent, and 2g of thickener to 200g of water-based epoxy resin in sequence and mix evenly, then add 3g of silane-modified graphene powder, 15g of functionalized emulsion and 5g of PANI-SiO2 to the water-based epoxy resin in sequence, mix evenly, and add curing agent when used to obtain a graphene-modified marine steel structure water-based anti-corrosion coating.

[0072] Example 4

[0073] This embodiment provides a method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification, and the preparation method specifically comprises the following steps:

[0074] S1, ice water bath, disperse 20g aniline, 5g p-toluenesulfonic acid and 125g, 20wt.% ammonium persulfate solution in 200mL deionized water and keep stirring for 12.0h, wash and filter to obtain polyaniline nanofibers, then immerse the polyaniline nanofibers in 5wt.% ammonium orthomolybdate solution, stir thoroughly, centrifuge, wash and dry to obtain modified polyaniline nanofibers. Disperse 10g SiO2 nanopowder and 5mL GPTMS in 50mL anhydrous ethanol, adjust to 90℃, stir and reflux for 2.4h, filter, wash and vacuum dry to obtain modified SiO2, disperse 20g modified polyaniline nanofibers and 10g modified SiO2 in 100mL deionized water, adjust the temperature to 57℃ and adjust the pH to 7, stir and react for 6.0h, centrifuge and wash, freeze-dry to obtain PANI-SiO2;

[0075] S2, 10g of graphene, 10g of thiourea and 8g of urea were dispersed in 100mL of deionized water, transferred to a reactor after ultrasonic dispersion and adjusted to 186°C for reaction for 13.0h, and after the reaction, the product was washed with 1wt.% KOH solution and dried to obtain N,S co-doped graphene powder, 8g of N,S co-doped graphene powder and 5g of intercalation agent were dispersed in 100mL of N-methylpyrrolidone, the temperature was adjusted to 80°C and stirred for 8.0h, filtered, washed and dried to obtain partially intercalated graphene material, 8g of partially intercalated graphene material and 3mL of KH560 were dispersed in 50mL of ethanol aqueous solution, the pH was adjusted to 5 and the temperature was adjusted to 60°C, refluxed for 3.0h, centrifuged, washed and dried to obtain silane-modified graphene powder;

[0076] S3, 15g of trifluoroethyl methacrylate and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 60℃ under nitrogen atmosphere and the reaction was carried out for 4.6h. After the reaction, ethanol was added for separation to obtain a fluorine-containing segment prepolymer. 5g of N-vinyl pyrrolidone, 5g of 3-methacryloyloxypropyltrimethoxysilane, 5g of maleic anhydride and 0.5g of azobisisobutyronitrile were dispersed in 50mL of dimethyl sulfoxide, the temperature was adjusted to 58℃ under nitrogen atmosphere and the reaction was stirred for 5.0h. After the reaction was completed, ethanol was added for separation to obtain a multifunctional copolymer segment. 10g of the fluorine-containing segment prepolymer, 10g of the multifunctional copolymer segment and 5g of pentaerythritol tetrakis(3-mercaptopropionic acid) were dispersed in 30mL of dimethyl sulfoxide, the temperature was adjusted to 80℃ and the reaction was stirred for 10.6h to obtain a macromolecular solution. 70mL of the macromolecular solution was then mixed with 1g of Tween 80 was dispersed into 200 mL of deionized water and stirred, the pH was adjusted to 8 and the temperature was adjusted to 70 °C for 2.0 h to obtain a functionalized emulsion;

[0077] S4, add 0.5g of leveling agent, 0.5g of defoaming agent, and 2g of thickener to 200g of water-based epoxy resin in sequence and mix evenly, then add 3g of silane-modified graphene powder, 15g of functionalized emulsion and 5g of PANI-SiO2 to the water-based epoxy resin in sequence, mix evenly, and add curing agent when used to obtain a graphene-modified marine steel structure water-based anti-corrosion coating.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification. The difference between it and Example 1 is that the mass of thiourea in S2 is 20g, which is 10g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0080] Comparative Example 2

[0081] This comparative example provides a method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification. The difference between it and Example 1 is that the mass of thiourea in S2 is 1g, which is 9g less than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0082] Comparative Example 3

[0083] This comparative example provides a preparation method of a water-based anti-corrosion coating for marine steel structures based on graphene modification. The difference between it and Example 1 is that the mass of pentaerythritol tetrakis(3-mercaptopropionic acid) in S3 is 10g, which is 5g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0084] Comparative Example 4

[0085] This comparative example provides a preparation method of a graphene-modified water-based anti-corrosion coating for marine steel structures. The difference between it and Example 1 is that the mass of pentaerythritol tetrakis(3-mercaptopropionic acid) in S3 is 1g, which is 4g less than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0086] Adhesion testing was conducted according to GB / T 9286-2021, salt spray resistance testing according to GB / T 31588.1-2015, and impact resistance testing according to GB / T 1732-2020. The test results are shown in Table 1.

[0087] Table 1 Test results of graphene-modified water-based anti-corrosion coatings for marine steel structures in Examples 1-4 and Comparative Examples 1-4

[0088]

[0089] As shown in Table 1, compared to Example 1, the adhesion, salt spray resistance, and impact resistance of Comparative Example 1 were all reduced; the adhesion, salt spray resistance, and impact resistance of Comparative Example 2 were all reduced. This is because the excessive amount of thiourea in Comparative Example 1 may lead to excessive doping of sulfur and nitrogen in the graphene sheets, resulting in excessive structural defects, reducing the integrity and mechanical strength of the graphene sheets, weakening the physical barrier function of the coating, and reducing the interfacial bonding ability between the graphene and the substrate material (such as water-based epoxy resin and PANI-SiO2). Excessive defects increase the penetration path of corrosive media through the coating, reducing salt spray resistance. In Comparative Example 2, the insufficient amount of thiourea, resulting in insufficient sulfur and nitrogen doping in the graphene, fails to significantly improve the chemical activity and wettability of the graphene surface, resulting in difficulty in forming a strong interfacial bond between the graphene and the coating substrate. Insufficient doping may also reduce the electrochemical activity of the graphene, weakening its synergistic cathodic protection effect with the PANI-SiO2, and affecting salt spray resistance.

[0090] As shown in Table 1, compared with Example 1, the adhesion, salt spray resistance, and impact resistance of Comparative Example 3 are all reduced; the adhesion, salt spray resistance, and impact resistance of Comparative Example 4 are all reduced. This is because in Comparative Example 3, the excessive amount of tetrakis(3-mercaptopropionic acid) pentaerythritol ester will cause the crosslinking density of the functionalized emulsion to be too high, the flexibility of the coating will decrease, and thus its impact resistance will be reduced. Excessive crosslinking may cause the internal stress of the coating to increase, and the interface between the coating and the substrate may peel or crack, resulting in reduced adhesion. The high crosslinking density may cause microcracks to form on the coating surface, reducing salt spray resistance. In Comparative Example 4, the amount of tetrakis(3-mercaptopropionic acid) pentaerythritol ester is insufficient, and the crosslinking network in the functionalized emulsion cannot be fully formed. The chemical bonding force and impact resistance between the coating and the substrate will both decrease. The hydrophobicity and density of the coating mainly depend on the integrity of the crosslinking network. Insufficient crosslinking will cause the barrier performance of the coating to decrease, making it easier for corrosive media to penetrate the metal substrate surface.

[0091] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures, characterized in that: The preparation method comprises: S1, stirring aniline, p-toluenesulfonic acid and ammonium persulfate solution to obtain polyaniline nanofibers, then immersing the polyaniline nanofibers in ammonium orthomolybdate solution to obtain modified polyaniline nanofibers, reacting SiO2 nanopowder with GPTMS to obtain modified SiO2, and reacting the modified polyaniline nanofibers with modified SiO2 to obtain PANI-SiO2; S2, reacting graphene, thiourea and urea to obtain N,S co-doped graphene powder, reacting the N,S co-doped graphene powder with an intercalation agent to obtain a partially intercalated graphene material, and reacting the partially intercalated graphene material with KH560 to obtain a silane-modified graphene powder; S3, reacting trifluoroethyl methacrylate with azobisisobutyronitrile to obtain a fluorine-containing segment prepolymer, reacting N-vinyl pyrrolidone, 3-(methacryloyloxy)propyltrimethoxysilane, and maleic anhydride with azobisisobutyronitrile to obtain a multifunctional copolymer segment, reacting the fluorine-containing segment prepolymer and the multifunctional copolymer segment with pentaerythritol tetrakis(3-mercaptopropionate) to obtain a macromolecular solution, and then mixing the macromolecular solution with Tween 80 to obtain a functionalized emulsion; S4, adding a leveling agent, a defoaming agent, and a thickener to a water-based epoxy resin, and then adding silane-modified graphene powder, a functionalized emulsion, and PANI-SiO2 to the water-based epoxy resin to obtain a graphene-modified water-based anti-corrosion coating for marine steel structures; The mass ratio of graphene, thiourea and urea is 10:10:8; The mass ratio of the fluorine-containing segment prepolymer, the multifunctional copolymer segment and pentaerythritol tetrakis(3-mercaptopropionate) is 2:2:

1.

2. The method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification according to claim 1, wherein: In S1: The mass ratio of the aniline, p-toluenesulfonic acid and ammonium persulfate solution is 20:5:125; The mass volume ratio of the SiO2 nanopowder to GPTMS is 10g:5mL.

3. The method for preparing a water-based anti-corrosion coating for marine steel structures based on graphene modification according to claim 1, wherein: In S1: The mass ratio of the modified polyaniline nanofiber to the modified SiO2 is 2:

1.

4. The method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures according to claim 1, wherein: In S2: The mass ratio of the N, S co-doped graphene powder to the intercalation agent is 8:

5.

5. The method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures according to claim 1, wherein: In S2: The mass volume ratio of the partially intercalated graphene material to KH560 is 8 g:3 mL.

6. The method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures according to claim 1, wherein: In S3: The mass ratio of trifluoroethyl methacrylate to azobisisobutyronitrile is 15:0.

5.

7. The method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures according to claim 1, wherein: In S3: The mass ratio of the N-vinyl pyrrolidone, 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, and azobisisobutyronitrile is 10g:10g:10g:1g.

8. The method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures according to claim 1, wherein: In S3: The volume-to-mass ratio of the macromolecular solution to Tween 80 is 70 mL:1 g.

9. The method for preparing a graphene-modified water-based anti-corrosion coating for marine steel structures according to claim 1, wherein: In S4: The mass ratio of the leveling agent, defoaming agent, thickener, water-based epoxy resin, silane-modified graphene powder, functionalized emulsion and PANI-SiO2 is 0.5:0.5:2:200:3:15:

5.

10. A water-based anti-corrosion coating for marine steel structures based on graphene modification, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 9.

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