Graphene modified marine anticorrosive paint based on dynamic covalent bonds

Abstract

The invention discloses a graphene modified marine anticorrosive paint based on dynamic covalent bonds, which takes a reversible cross-linked network as a core, and is prepared by the following steps: firstly, synthesizing two dynamic reaction precursors of furan functionalized methyl vinyl MQ type silicon resin and maleimide functionalized graphene oxide; then the furan group and the maleimide group are uniformly dispersed in a solvent and coated on the surface of a base material, a Diels-Alder cycloaddition reaction between the furan group and the maleimide group is triggered through heating, and a three-dimensional dynamic covalent cross-linked network is constructed in situ in the coating. According to the dynamic cross-linked structure, the interface bonding force of graphene and silicon resin is remarkably enhanced in a chemical bonding mode, filler agglomeration is avoided, the physical shielding and mechanical enhancement effects of graphene are fully exerted, the overall coating is endowed with excellent toughness, impact resistance and permeability resistance, and the service life of the coating is prolonged. And cavitation erosion in the marine environment can be effectively resisted, and the synergistic effect of scouring and corrosive media can be effectively resisted, so that long-acting and reliable anti-corrosion protection is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of marine coating and underwater coating protection, and relates to a graphene modified marine anticorrosive coating based on dynamic covalent bonds. BACKGROUND

[0002] In the marine environment, steel structure facilities are long-term exposed to multiple factors such as salt spray, tides, ultraviolet radiation and microbial attachment, among which electrochemical corrosion is the primary factor leading to material failure and shortening of service life. In response to this severe challenge, organic coating protection has become the most widely used technical means due to its convenient construction, controllable cost and significant protection effect. Traditional marine anticorrosive coating systems, such as epoxy resin coatings and polyurethane coatings, mainly rely on the dense physical barrier formed after film formation to isolate corrosive media, or provide sacrificial anode protection by adding zinc powder and other active pigments. However, these traditional resin matrices (epoxy, polyurethane) have high surface energy and certain hydrophilicity, and in the long-term immersion or alternating wet and hot marine environment, water and corrosive ions (such as Cl - ) will gradually penetrate the coating and eventually reach the metal substrate interface to induce corrosion. In addition, the cross-linked network of such coatings is mainly connected by permanent chemical bonds (static network), which has the disadvantages of high internal stress and insufficient flexibility. When subjected to wave impact, sand erosion or temperature changes, the substrate deforms, and microcracks are easily generated. Once the coating is damaged, its protective performance will decrease dramatically, and the cracks are difficult to repair, often requiring large-scale recoating, resulting in high maintenance costs.

[0003] In recent years, graphene has been widely regarded as an ideal choice for the next generation of anticorrosive fillers due to its unique two-dimensional sheet structure, excellent mechanical strength and outstanding gas and liquid barrier properties. The introduction of graphene into the coating system aims to greatly extend the diffusion path of corrosive media by utilizing its "labyrinth effect", thereby significantly improving the shielding performance of the coating. Currently, most graphene modified anticorrosive coatings on the market still use simple physical blending processes, i.e. directly dispersing graphene or graphene oxide powder in the resin base. Although this method is simple, it has significant bottlenecks: first, there is strong van der Waals force between graphene layers, which easily leads to agglomeration, making it difficult to achieve uniform dispersion at the nanoscale in the polymer matrix. Agglomerates can even become defect points, accelerating the penetration of the medium; second, physical blending leads to weak van der Waals force or hydrogen bonding between graphene and the resin matrix, resulting in low interfacial adhesion strength. Under external force or environmental stress, the interface is prone to debonding, and the reinforcing and barrier effects of graphene cannot be fully utilized, and even may accelerate the damage of the coating due to interface failure.

[0004] Meanwhile, polysiloxane (especially MQ type silicone resin) as a film-forming material, due to its main chain of flexible Si-O bond and side chain of hydrophobic methyl, exhibits excellent weather resistance, high and low temperature resistance, hydrophobicity and inherent low surface energy characteristics, and has great application potential in harsh marine environment. However, the mechanical strength, adhesion and permeability resistance of pure silicone resin coating are sometimes difficult to meet the requirements of heavy-duty corrosion. The combination of graphene and silicone resin can theoretically complement each other's advantages, but how to realize the stable and uniform dispersion of graphene in silicone resin and establish a strong and tough interface bonding is a key scientific problem that must be solved to obtain a high-performance composite coating.

[0005] On the other hand, from the network structure design of the coating, it has become a research direction to endow the material with certain dynamic characteristics. Dynamic covalent bonds, such as reversible Diels-Alder (DA) bonds, can reversibly break and recombine under certain conditions (such as heating). The introduction of such dynamic bonds into the cross-linked network of the coating can theoretically endow the material with self-repairing potential and recyclability. However, existing researches are mostly focused on the introduction of dynamic bonds into homogeneous polymer networks, and how to combine dynamic covalent chemistry with the functionalization and compounding process of nanofillers (such as graphene) to construct a composite material system that realizes the strong combination of graphene and resin matrix and has long-term corrosion resistance and dynamic characteristics with dynamic bonds as "bridge" is still rarely reported.

[0006] Therefore, the development of a new type of marine corrosion-resistant coating, which can not only solve the dispersion and interface bonding problem of graphene in resin, fully exert its barrier and reinforcing effect, but also combine the durability advantage of organic silicone resin and introduce intelligent dynamic characteristics, has important theoretical value and practical significance for improving the long-term protection level of marine major equipment, reducing the life cycle maintenance cost and developing green and sustainable protection technology. SUMMARY

[0007] Invention purpose: Marine engineering equipment is long-term exposed to harsh service environment and faces multiple damage modes such as electrochemical corrosion, cavitation erosion and biofouling. Existing traditional graphene modified corrosion-resistant coatings (such as epoxy and polyurethane-based systems) mostly rely on physical blending to introduce graphene, which has problems such as easy agglomeration of nanosheets and weak interface bonding with resin matrix, making it difficult to fully exert the reinforcing and barrier potential of graphene. At the same time, the static cross-linked network often produces micro-cracks and accelerates failure due to insufficient toughness and stress concentration when facing dynamic mechanical impact such as high flow rate and containing silt. Based on this, the purpose of the present application is to provide a graphene modified marine corrosion-resistant coating based on dynamic covalent bonds.

[0008] Principle: through the step-by-step synthesis of furan functional methyl vinyl MQ type silicone resin and maleimide functional graphene oxide hybrid crosslinking agent, and utilize the efficient Diels-Alder cycloaddition reaction between the two, in situ build strong, uniform three-dimensional chemical crosslinking network inside the coating. The core synthesis mechanism is: first, through free radical graft copolymerization, the reactive monomer containing furan ring is covalently grafted onto the methyl vinyl MQ silicone resin skeleton, which endows the matrix with excellent flexibility, hydrophobicity and weather resistance, and introduces furan functional groups which can be used as diene; second, through the reaction of isocyanate bridging agent with the hydroxyl / carboxyl on the surface of graphene oxide, and then with maleimide monomer for secondary grafting, a multi-site maleimide functional group (dienophile) is constructed on the surface of graphene sheet, forming a nano hybrid crosslinking agent which can be uniformly dispersed and has strong interfacial reactivity; finally, in the heating and curing process after coating, the furan groups in the resin and the maleimide groups on the graphene occur directional Diels-Alder reaction, forming a stable covalent bond connection network between them. The dynamic crosslinking structure not only significantly enhances the interfacial bonding force between graphene and silicone resin through chemical bonding, avoids filler agglomeration, fully plays the physical shielding and mechanical enhancement effect of graphene, but also endows the coating with excellent toughness, impact resistance and permeability resistance, which can effectively resist the synergistic effect of cavitation, erosion and corrosion medium in marine environment, thereby realizing long-term and reliable corrosion protection.

[0009] Technical scheme: the graphene modified marine anti-corrosion coating based on dynamic covalent bond of the present application comprises, by weight fraction: furan functional methyl vinyl MQ type silicone resin 30-60 parts; maleimide functional graphene oxide hybrid crosslinking agent 2-15 parts; reaction solvent 20-50 parts; catalyst 0.1-2 parts; Among them, The furan functional methyl vinyl MQ type silicone resin is prepared by grafting the reactive monomer containing furan ring onto the methyl vinyl MQ type silicone resin skeleton through free radical copolymerization; The maleimide functional graphene oxide hybrid crosslinking agent is prepared by reacting the isocyanate bridging agent with the oxygen-containing functional groups on the surface of graphene oxide, and then reacting with maleimide monomer; The coating forms a three-dimensional dynamic covalent crosslinking network through the Diels-Alder reaction between the furan groups in the furan functional methyl vinyl MQ type silicone resin and the maleimide groups in the maleimide functional graphene oxide hybrid crosslinking agent.

[0010] Further, the preparation method of the furan functional methyl vinyl MQ type silicone resin comprises the following steps: (1) Under the protection of an inert gas, methyl vinyl MQ type silicone resin, a reactive monomer containing a furan ring, a free radical initiator and a first organic solvent are added to a reaction vessel and stirred until they are mixed evenly; (2) Heat the reaction system to 60-85°C and carry out free radical graft copolymerization for 4-12 hours; (3) After the reaction is complete, the product solution is added dropwise to a precipitant for precipitation, and the solid product is collected by filtration. (4) The solid product was washed several times with a precipitant and then dried under vacuum to obtain the furan-functionalized methyl vinyl MQ type silicone resin.

[0011] Furthermore, the methyl vinyl MQ type silicone resin is selected from methyl vinyl MQ type siloxane resin, with an M:Q value ≥ 1.3:1, or the methyl vinyl MQ type silicone resin is liquid at 25°C.

[0012] Furthermore, the furan ring-containing reactive monomer is selected from one of 2-furan methacrylate, 2-furan acrylate, furfuryl methacrylate, furfuryl acrylate, and 5-methyl-2-furan methacrylate.

[0013] Specifically, the initiator is a raw material that can initiate free radical copolymerization at 60–85°C, without any particular limitations. Preferably, azobisisobutyronitrile (AIBN) is used.

[0014] Specifically, the first organic solvent is selected from at least one of toluene, xylene, N,N-dimethylformamide, and acetone.

[0015] Furthermore, the weight ratio of the methyl vinyl MQ type silicone resin, the furan ring-containing reactive monomer, the free radical initiator, and the first organic solvent is 100:(5-25):(0.5-3):(150-300).

[0016] Specifically, the precipitant is a commonly used polar precipitant that can rapidly reduce the solubility of organic products in the reaction mixture, enabling their efficient precipitation, without any particular limitations. Preferably, it is selected from n-hexane and petroleum ether.

[0017] Furthermore, the preparation method of the maleimide-functionalized graphene oxide hybrid crosslinking agent includes the following steps: (1) Graphene oxide is dispersed in a second organic solvent, and a monomer containing isocyanate functional group is added. The reaction is carried out at 60-80°C for 8-15 hours under inert gas protection. After the reaction is completed, the graphene oxide is separated by centrifugation, washed and dried to obtain isocyanate functionalized graphene oxide intermediate. (2) The isocyanate-functionalized graphene oxide intermediate obtained in step (1) is redispersed in a third organic solvent, and a monomer containing maleimide functional group is added. The reaction is continued at 60-80°C for 8-15 hours under inert gas protection. (3) After the reaction is complete, the product is centrifuged and washed repeatedly with a cleaning solvent to remove unreacted monomers and byproducts. Then it is dried under vacuum to obtain the maleimide-functionalized graphene oxide hybrid crosslinking agent.

[0018] Furthermore, the graphene oxide is selected from at least one of single-layer graphene oxide, few-layer graphene oxide, and multi-layer graphene oxide, and its carbon-oxygen atom ratio is between 1.5:1 and 3:1.

[0019] Specifically, the second organic solvent is selected from one of N,N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, and dimethyl sulfoxide.

[0020] Furthermore, the isocyanate-containing functional group monomer is selected from one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate.

[0021] Specifically, the third organic solvent is selected from one of N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

[0022] Furthermore, the maleimide-containing monomer is selected from one of N-(2-hydroxyethyl)maleimide, N-(3-hydroxypropyl)maleimide, and N-(6-hydroxyhexyl)maleimide.

[0023] Further, the weight fraction ratio of the graphene oxide, the second organic solvent, the isocyanate-functionalized monomer, the third organic solvent, and the maleimide-functionalized monomer is (30-60): (50-150): (50-100): (20-80).

[0024] Specifically, the cleaning solvent is selected from ethyl acetate, methanol, and ethanol.

[0025] Specifically, the reaction solvent is selected from one of tetrahydrofuran, ethyl acetate, propylene glycol methyl ether acetate, and xylene.

[0026] Specifically, the catalyst is selected from one of anhydrous zinc chloride, anhydrous aluminum chloride, and p-toluenesulfonic acid.

[0027] The preparation method of graphene-modified marine anticorrosive coating based on dynamic covalent bonds described in this invention can be carried out according to conventional coating preparation processes without special requirements.

[0028] Specifically, this invention provides a method for preparing a graphene-modified marine anticorrosive coating based on dynamic covalent bonds, comprising the following steps: In a dispersion and stirring device, furan-functionalized methyl vinyl MQ type silicone resin, maleimide-functionalized graphene oxide hybrid crosslinking agent, and reaction solvent are stirred at 100 rpm until homogeneous. Then, the catalyst is added and stirring continues until homogeneous. Coating can then be performed.

[0029] Specifically, there are no particular restrictions on the mixing equipment involved in the preparation steps; any conventional equipment used in coating dispersion manufacturing is acceptable.

[0030] The present invention discloses a graphene-modified marine anti-corrosion coating based on dynamic covalent bonds, which is applied by conventional coating methods such as spraying, brushing, and rolling, and has a film thickness of 300~500μm after drying and curing on the substrate surface.

[0031] Beneficial Effects: 1. This invention designs and synthesizes a hybrid crosslinking agent of furan-functionalized methyl vinyl MQ type silicone resin and maleimide-functionalized graphene oxide in steps, and utilizes the efficient Diels-Alder cycloaddition reaction between the two to construct a three-dimensional crosslinked network with strong chemical bonds in situ within the coating. This design fundamentally solves the bottleneck problems commonly encountered in the preparation of graphene coatings by traditional physical blending methods, such as easy agglomeration of nanosheets and weak interfacial bonding with the resin matrix. The chemically bonded interface ensures the effective transfer of stress from the flexible silicone resin matrix to the high-strength graphene sheets, thereby synergistically improving the mechanical strength, toughness, and impermeability of the coating, and significantly enhancing its durability under dynamic marine environments (such as cavitation and erosion).

[0032] 2. This invention "bridges" the excellent weather resistance, hydrophobicity, and flexibility of methyl vinyl MQ type silicone resin with the superior barrier properties and mechanical reinforcement of graphene oxide through dynamic covalent bonds, achieving an organic fusion and synergistic effect of performance. The silicone resin matrix ensures the long-term stability of the coating in harsh marine environments such as wide temperature range and strong ultraviolet radiation, while the uniformly dispersed and chemically bonded graphene network provides long-lasting and dense physical barrier, together constructing an integrated protection system against multiple failure modes such as electrochemical corrosion and media penetration.

[0033] 3. The preparation process of this invention is well-defined and controllable. Two functionally defined precursors can be reproducibly prepared through mature chemical reactions such as free radical grafting and isocyanate coupling. The final coating formation relies on a simple and efficient Diels-Alder reaction with mild reaction conditions, requiring no special equipment, and is easy to implement for industrial production and application. This provides a reliable technical path for developing a new generation of high-performance, multifunctional marine anti-corrosion coatings. Detailed Implementation

[0034] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0035] The raw materials used in the examples are shown in Table 1. In actual implementation, the raw materials are not limited to those listed in Table 1; appropriate products can be selected based on the foregoing. Other raw materials used in the examples are commercially available chemical reagents.

[0036] Table 1

[0037] Preparation of furan-functionalized methyl vinyl MQ type silicone resin 1: The weight ratio of methyl vinyl MQ type silicone resin 1-1, furan ring-containing reactive monomer 2-1, free radical initiator, and first organic solvent 3-2 is 100:13:0.5:200. The specific preparation process is as follows: (1) Under the protection of an inert gas, methyl vinyl MQ type silicone resin, a reactive monomer containing a furan ring, a free radical initiator and a first organic solvent are added to a reaction vessel and stirred until they are mixed evenly; (2) Heat the reaction system to 65°C and carry out free radical graft copolymerization reaction for 9 hours; (3) After the reaction is complete, the product solution is added dropwise to a precipitant for precipitation, and the solid product is collected by filtration. (4) The solid product was washed several times with a precipitant and then dried under vacuum to obtain furan-functionalized methyl vinyl MQ type silicone resin 1.

[0038] Preparation of furan-functionalized methyl vinyl MQ type silicone resin 2:

[0039] The weight ratio of methyl vinyl MQ type silicone resin 1-1, furan ring-containing reactive monomer 2-2, free radical initiator, and first organic solvent 3-2 is 100:5:1:150. The specific preparation process is as follows: (1) Under the protection of an inert gas, methyl vinyl MQ type silicone resin, a reactive monomer containing a furan ring, a free radical initiator and a first organic solvent are added to a reaction vessel and stirred until they are mixed evenly; (2) Heat the reaction system to 60°C and carry out free radical graft copolymerization for 12 hours; (3) After the reaction is complete, the product solution is added dropwise to a precipitant for precipitation, and the solid product is collected by filtration. (4) The solid product was washed several times with a precipitant and then dried under vacuum to obtain furan-functionalized methyl vinyl MQ type silicone resin 2.

[0040] Preparation of furan-functionalized methyl vinyl MQ type silicone resin 3:

[0041] The weight ratio of methyl vinyl MQ type silicone resin 1-2, furan ring-containing reactive monomer 2-3, free radical initiator, and first organic solvent 3-1 is 100:25:3:300. The specific preparation process is as follows: (1) Under the protection of an inert gas, methyl vinyl MQ type silicone resin, a reactive monomer containing a furan ring, a free radical initiator and a first organic solvent are added to a reaction vessel and stirred until they are mixed evenly; (2) Heat the reaction system to 85°C and carry out free radical graft copolymerization for 4 hours; (3) After the reaction is complete, the product solution is added dropwise to a precipitant for precipitation, and the solid product is collected by filtration. (4) The solid product was washed several times with a precipitant and then dried under vacuum to obtain furan-functionalized methyl vinyl MQ type silicone resin 3.

[0042] Preparation of maleimide-functionalized graphene oxide hybrid crosslinking agent 1:

[0043] The weight ratio of graphene oxide 4-1, second organic solvent 5-1, isocyanate-functionalized monomer 6-3, third organic solvent 7-1, and maleimide-functionalized monomer 8-1 is 50:120:70:50. The specific preparation process is shown below: (1) Graphene oxide was dispersed in a second organic solvent, and a monomer containing isocyanate functional group was added. The reaction was carried out at 60°C for 15 hours under inert gas protection. After the reaction was completed, the mixture was centrifuged, washed and dried to obtain isocyanate-functionalized graphene oxide intermediate. (2) The isocyanate-functionalized graphene oxide intermediate obtained in step (1) is redispersed in a third organic solvent, and a monomer containing maleimide functional group is added. The reaction is continued at 75°C for 13 hours under inert gas protection. (3) After the reaction is complete, the product is centrifuged and washed repeatedly with a cleaning solvent to remove unreacted monomers and byproducts. Then it is dried under vacuum to obtain maleimide-functionalized graphene oxide hybrid crosslinking agent 1.

[0044] Preparation of maleimide-functionalized graphene oxide hybrid crosslinking agent 2:

[0045] The weight ratio of graphene oxide 4-2, second organic solvent 5-2, isocyanate-functionalized monomer 6-1, third organic solvent 7-1, and maleimide-functionalized monomer 8-1 is 30:150:100:20. The specific preparation process is shown below: (1) Graphene oxide was dispersed in a second organic solvent, and a monomer containing isocyanate functional group was added. The reaction was carried out at 80°C for 8 hours under inert gas protection. After the reaction was completed, the mixture was centrifuged, washed and dried to obtain isocyanate-functionalized graphene oxide intermediate. (2) The isocyanate-functionalized graphene oxide intermediate obtained in step (1) is redispersed in a third organic solvent, and a monomer containing maleimide functional group is added. The reaction is continued at 80°C for 8 hours under inert gas protection. (3) After the reaction is complete, the product is centrifuged and washed repeatedly with a cleaning solvent to remove unreacted monomers and byproducts. Then it is dried under vacuum to obtain maleimide-functionalized graphene oxide hybrid crosslinking agent 2.

[0046] Preparation of maleimide-functionalized graphene oxide hybrid crosslinking agent 3:

[0047] The weight ratio of graphene oxide 4-1, second organic solvent 5-1, isocyanate-functionalized monomer 6-2, third organic solvent 7-2, and maleimide-functionalized monomer 8-2 is 60:50:50:80. The specific preparation process is shown below: (1) Graphene oxide was dispersed in a second organic solvent, and a monomer containing isocyanate functional group was added. The reaction was carried out at 70°C for 12 hours under inert gas protection. After the reaction was completed, the mixture was centrifuged, washed and dried to obtain isocyanate-functionalized graphene oxide intermediate. (2) The isocyanate-functionalized graphene oxide intermediate obtained in step (1) is redispersed in a third organic solvent, and a monomer containing maleimide functional group is added. The reaction is continued at 60°C for 15 hours under inert gas protection. (3) After the reaction is complete, the product is centrifuged and washed repeatedly with a cleaning solvent to remove unreacted monomers and byproducts. Then it is dried under vacuum to obtain maleimide-functionalized graphene oxide hybrid crosslinking agent 3.

[0048] Examples 1-5 The formulations for Examples 1-5 are shown in Table 2.

[0049] Table 2

[0050] A method for preparing a graphene-modified marine anticorrosive coating based on dynamic covalent bonds, as described in Examples 1-5, includes the following steps: In a dispersion and stirring device, furan-functionalized methyl vinyl MQ type silicone resin, maleimide-functionalized graphene oxide hybrid crosslinking agent, and reaction solvent are stirred at 100 rpm until homogeneous. Then, a catalyst is added and stirring continues until homogeneous. Subsequently, a coating with a thickness of 300~500 μm is formed on the substrate surface by spraying and drying and curing.

[0051] Comparative Example 1 (Marine anti-corrosion coating without furan functionalization) Compared with Example 1, Comparative Example 1 used methyl vinyl MQ type silicone resin as the polymer resin, without furan functionalization, and the remaining components and weight parts were the same. Its preparation process was also the same as that of Example 1. During coating, the coating was baked at 80°C to ensure curing.

[0052] Comparative Example 2 (Marine Anti-corrosion Coating with Graphene Oxide) Compared with Example 1, Comparative Example 2 uses graphene oxide that has not been chemically modified and is dispersed in the coating by physical mixing alone. The other components and weight parts are the same, and its preparation process is also the same as that of Example 1.

[0053] <Specific Test Experiments and Conditions> Test 1: Corrosion Resistance The coating was applied to the polished steel plate surface, ensuring the entire surface was coated. A 3.5 wt% sodium chloride aqueous solution (prepared using deionized water) was prepared, and the sample was completely immersed in the solution for 70 days. The immersion temperature was controlled at 25 ± 2 ℃. During immersion, the container was covered to reduce evaporation and contamination; if necessary, the solution was replenished or replaced every 7–14 days to maintain salinity stability. Electrochemical impedance spectroscopy (EIS) was performed using an electrochemical workstation with a three-electrode system: the coated sample as the working electrode, a platinum or graphite electrode as the counter electrode, and a silver / silver chloride electrode or a saturated calomel electrode as the reference electrode. Before testing, the sample after 70 days of immersion was removed, gently rinsed with deionized water to remove surface salt, and dried with nitrogen or dry air. It was then immediately placed in the electrochemical test cell; the electrolyte in the test cell was also a 3.5 wt% sodium chloride solution. A sinusoidal AC disturbance signal with an amplitude of 5–10 mV is applied at an open-circuit potential; the scanning frequency range is 10. 5 ~10 -2 Hz. After obtaining the impedance spectrum, the impedance modulus at low frequencies is extracted as a characterization index for corrosion resistance, and |Z| is taken as the value. 0.01 The comparison is performed at Hz; the higher the low-frequency impedance modulus value, the better the shielding / protection performance of the coating.

[0054] Test 2: Surface Free Energy The contact angles of the cured coating surface with deionized water and diiodomethane were determined using an XG-CAMC3 fully automatic contact angle measuring instrument manufactured by Shanghai Xuanzhun Instrument Co., Ltd. Before measurement, the coating surface was cleaned with anhydrous ethanol and dried. The surface free energy of the coating was then calculated using the Owens two-liquid method.

[0055] The specific test results of Examples 1-5 and Comparative Examples 1-2 are shown in Tables 3 and 4.

[0056] Table 3

[0057] Table 4

[0058] The test results above confirm that the low-frequency impedance modulus of Examples 1-5 reaches 3.89 × 10⁻⁶. 9 ~4.39×10 9 Ω·cm 2 The surface energy is much higher than that of the comparative example and is in the low surface energy range, which proves that the coating of the embodiment has better shielding / protection performance and excellent anti-corrosion and hydrophobic properties, making it suitable for marine environments.

[0059] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A graphene-modified marine anticorrosive coating based on dynamic covalent bonds, characterized by, By weight parts, including: Furan-functionalized methyl vinyl MQ type silicone resin 30-60 parts; Maleimide-functionalized graphene oxide hybrid crosslinking agent 2-15 parts; Reaction solvent 20-50 parts; Catalyst 0.1-2 parts; Among them, The furan-functionalized methyl vinyl MQ type silicone resin is prepared by free radical copolymerization of a furan ring-containing reactive monomer grafted onto a methyl vinyl MQ type silicone resin skeleton; The maleimide-functionalized graphene oxide hybrid crosslinking agent is prepared by reacting an isocyanate functional group-containing monomer with the oxygen-containing functional groups on the surface of graphene oxide, and then reacting with a maleimide functional group-containing monomer; The coating is prepared by the Diels-Alder reaction between the furan groups in the furan-functionalized methyl vinyl MQ type silicone resin and the maleimide groups in the maleimide-functionalized graphene oxide hybrid crosslinking agent, forming a three-dimensional dynamic covalent crosslinking network.

2. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to claim 1, characterized in that, The preparation method of the furan-functionalized methyl vinyl MQ type silicone resin comprises the following steps: (1) Under the protection of inert gas, methyl vinyl MQ type silicone resin, furan ring-containing reactive monomer, free radical initiator and first organic solvent are added to the reaction container and stirred until mixed uniformly; (2) The reaction system is heated to 60-85℃, and free radical graft copolymerization is carried out for 4-12 hours; (3) After the reaction is completed, the product solution is dropped into the precipitator for precipitation, and the solid product is collected by filtration; (4) The solid product is washed several times with the precipitator, and then dried under vacuum to obtain the furan-functionalized methyl vinyl MQ type silicone resin.

3. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to any one of claims 1 or 2, characterized in that, The methyl vinyl MQ type silicone resin is selected from methyl vinyl MQ type siloxane resin with M:Q value ≥1.3:1, or methyl vinyl MQ type silicone resin is liquid at 25℃.

4. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to any one of claims 1 or 2, characterized in that, The furan ring-containing reactive monomer is selected from one of 2-furfuryl methacrylate, 2-furfuryl acrylate, furfuryl methacrylate, furfuryl acrylate, 5-methyl-2-furfuryl methacrylate.

5. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to claim 2, characterized in that, The weight parts ratio of the methyl vinyl MQ type silicone resin, furan ring-containing reactive monomer, free radical initiator, first organic solvent is 100:(5-25):(0.5-3):(150-300).

6. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to claim 1, characterized in that, The preparation method of the maleimide-functionalized graphene oxide hybrid crosslinking agent comprises the following steps: (1) Disperse graphene oxide in a second organic solvent, add an isocyanate functional group-containing monomer, and react at 60-80℃ for 8-15 hours under the protection of inert gas. After the reaction is completed, centrifugal separation, washing and drying are carried out to obtain an isocyanate-functionalized graphene oxide intermediate; (2) Redisperse the isocyanate-functionalized graphene oxide intermediate obtained in step (1) in a third organic solvent, add a maleimide functional group-containing monomer, and continue to react at 60-80℃ for 8-15 hours under the protection of inert gas; (3) After the reaction is completed, centrifugal separation is carried out, and the product is repeatedly washed with a washing solvent to remove unreacted monomers and byproducts, and then dried under vacuum to obtain the maleimide-functionalized graphene oxide hybrid crosslinking agent.

7. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to any one of claims 1 or 6, characterized in that, The graphene oxide is selected from at least one of single-layer graphene oxide, few-layer graphene oxide, and multi-layer graphene oxide, and has a carbon-oxygen atomic ratio of 1.5:1 to 3:

1.

8. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to any one of claims 1 or 6, characterized in that, The isocyanate-functional monomer is selected from one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate, and dicyclohexyl methane diisocyanate.

9. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to any one of claims 1 or 6, characterized in that, The maleimide-functional monomer is selected from one of N-(2-hydroxyethyl)maleimide, N-(3-hydroxypropyl)maleimide, and N-(6-hydroxyhexyl)maleimide.

10. The graphene-modified marine anticorrosive coating based on dynamic covalent bonds according to claim 6, characterized in that, The weight fraction ratio of the graphene oxide, the second organic solvent, the isocyanate-functional monomer, the third organic solvent, and the maleimide-functional monomer is (30-60):(50-150):(50-100):(20-80).

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