A functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating and its application

Abstract

The present invention discloses a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating and its application, belonging to the field of anti-corrosion technology. The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating comprises functionalized modified graphene oxide-MXene nanosheets, a self-healing polyurethane containing S-S bonds, and a solvent. The functionalized modified graphene oxide-MXene nanosheets are obtained by hydrolyzing modified graphene oxide-MXene nanosheets with a silane coupling agent containing S-S bonds. By introducing special functionalized modified graphene oxide-MXene nanosheets, the coating exhibits enhanced corrosion resistance and self-healing properties, and can be widely used for the anti-corrosion of alloy materials.

Description

Technical Field

[0001] The present invention relates to an anti-corrosion coating, in particular to a functionalized graphene oxide-MXene nanosheet-enhanced self-repairing anti-corrosion coating, belonging to the technical field of anti-corrosion coatings. Background Art

[0002] Metal corrosion causes significant economic losses annually and is associated with even more serious safety incidents. Surface coatings are the most economical and convenient anti-corrosion method, and two-dimensional fillers are often used to enhance the barrier properties of polymer coatings to improve their corrosion resistance. MXene offers advantages such as high mechanical strength and good electrical conductivity, but MXene is susceptible to oxidation and is difficult to disperse uniformly in organic polymers. Existing techniques typically address these shortcomings by modifying MXene nanomaterials. For example, Chinese patent CN114854237A discloses modifying MXene nanomaterials with silane coupling agents, or hybridizing and coating MXene nanomaterials with graphene-based nanosheets, followed by further modification with a silane coupling agent. The resulting covalent hybrids of MXene nanosheets and graphene-based nanomaterials are formed, with the graphene nanosheets acting as spacers between the MXene nanosheets to prevent aggregation within the nanocomposite polymer matrix. Covalent silane functionalization is chosen to form a protective layer on the surface of the MXene nanosheets, inhibiting oxidation and improving the dispersion of the nanosheets in the polymer coating. Although this patent utilizes silane coupling agents to improve the dispersion and stability of two-dimensional nanofillers, the introduction of two-dimensional nanofillers can introduce new technical challenges to anti-corrosion coatings. Typically, the addition of two-dimensional nanofillers reduces the self-healing efficiency of the anti-corrosion coating, thereby shortening the coating's service life. Therefore, overcoming the inherent weaknesses of two-dimensional nanofillers and developing anti-corrosion coatings that combine excellent corrosion resistance with enhanced self-healing efficiency is crucial for protecting metals from corrosion, improving work efficiency, and reducing maintenance costs. Summary of the Invention

[0003] In response to the shortcomings of the prior art, the first object of the present invention is to provide a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating. The anti-corrosion coating uses a two-dimensional nanomaterial obtained by hydrolyzing and modifying graphene oxide-MXene nanosheets with a silane coupling agent containing SS bonds. The two-dimensional nanomaterial can not only be evenly dispersed in the polyurethane matrix, but also can interact with the disulfide bonds in the self-healing polyurethane matrix containing SS bonds to carry out dynamic exchange reactions, thereby enhancing the self-healing efficiency of the anti-corrosion coating, so that the anti-corrosion coating has enhanced corrosion resistance and self-healing properties.

[0004] The second purpose of the present invention is to provide an application of a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating, which is applied to a metal surface to form an anti-corrosion coating, wherein the corrosion potential increases, the corrosion current density decreases, and the coating resistance increases. At the same time, the self-healing efficiency is significantly improved, thereby greatly extending the service life of the anti-corrosion coating.

[0005] In order to achieve the above technical objectives, the present invention provides a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating, which comprises functionalized modified graphene oxide-MXene nanosheets, self-healing polyurethane containing SS bonds and a solvent; the functionalized modified graphene oxide-MXene nanosheets are obtained by hydrolyzing modified graphene oxide-MXene nanosheets with a silane coupling agent containing SS bonds.

[0006] The key to the anti-corrosion coating of the present invention is the introduction of a functionalized graphene oxide-MXene nanosheet composite material. The surface of the graphene oxide-MXene nanosheet is functionalized and modified by the hydrolysis of a silane coupling agent containing SS bonds. On the one hand, the organic group contained in the silane is used to improve the compatibility of the graphene oxide-MXene nanosheet with the organic polymer, thereby greatly improving the dispersibility of the graphene oxide-MXene nanosheet in the polymer matrix. On the other hand, by introducing a large number of SS bonds on the surface of the graphene oxide-MXene nanosheet, it can interact with the SS bonds in the self-healing polyurethane containing SS bonds, and perform dynamic exchange reactions, thereby greatly enhancing the self-healing efficiency of the composite material. Thus, the introduction of functionalized graphene oxide-MXene nanosheets as fillers in the anti-corrosion coating can increase the corrosion potential of the anti-corrosion coating, reduce the corrosion current density, and increase the coating resistance, thereby having enhanced corrosion resistance and self-healing properties.

[0007] As a preferred solution, the functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating includes the following mass components: 1 part of functionalized modified graphene oxide-MXene nanosheets; 100 to 1000 parts of self-healing polyurethane containing SS bonds; 1000 to 30,000 parts of solvent; As a more preferred solution, the functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating consists of the following mass components: 1 part of functionalized modified graphene oxide-MXene nanosheets; 500 to 1000 parts of self-healing polyurethane containing SS bonds; 2500 to 25,000 parts of solvent.

[0008] As a preferred solution, the functionalized modified graphene oxide-MXene nanosheets are prepared by the following method: ultrasonically dispersing the graphene oxide-MXene nanosheets in an alcohol-water mixed solvent, adjusting the pH to an acidic condition, and then adding a silane coupling agent containing an SS bond to carry out a hydrolysis reaction. The obtained reaction product is sequentially washed, centrifuged, and dried to obtain the functionalized modified graphene oxide-MXene nanosheets.

[0009] As a preferred solution, the self-healing polyurethane containing SS bonds is prepared by the following method: prepolymerizing dihydroxy-terminated PDMS with isophorone diisocyanate to obtain a diisocyanate-terminated prepolymer, and copolymerizing the diisocyanate-terminated prepolymer with 4,4'-dithiodiphenylamine and isophorone diamine to obtain.

[0010] As a preferred solution, the mass ratio of graphene oxide-MXene nanosheets to silane coupling agent containing SS bonds is 1:1.5-2.5. The amount of silane coupling agent containing SS bonds modified on the graphene oxide-MXene nanosheets cannot be too low, otherwise the modification effect cannot be achieved.

[0011] As a preferred solution, the pH is adjusted to 3-4 using an organic carboxylic acid, such as acetic acid.

[0012] As a preferred solution, the silane coupling agent containing SS bonds includes Si69.

[0013] As a preferred solution, the conditions for the hydrolysis reaction are: temperature of 25±2° C., and time of 12 to 24 hours.

[0014] As a preferred solution, the solvent includes at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and tetrahydrofuran.

[0015] The present invention also provides an application of a functionalized graphene oxide-MXene nanosheet-enhanced self-repairing anti-corrosion coating, which is used for corrosion protection of metal surfaces.

[0016] As a preferred solution, the metal includes a magnesium alloy.

[0017] The method for preparing functionalized graphene oxide-MXene nanosheets of the present invention comprises the following steps:

[0018] SS1: Disperse 1 part of graphene oxide-MXene nanosheets in Solution I, a mixture of anhydrous ethanol and water with a volume ratio of 8-10:1. Ultrasonic treatment is performed at a temperature of 22-30°C for 10-15 minutes. A more preferred ultrasonic treatment is at 25°C for 10 minutes.

[0019] SS2: Adjust the pH of the solution in SS1 to an acidic condition; the pH value of the solution is adjusted to 3-4. The pH value can be adjusted using glacial acetic acid.

[0020] SS3: Add 2 parts of silane coupling agent containing SS bond to the SS2 solution and stir in a water bath until the reaction is complete; the reaction conditions are: temperature 25±2°C, stirring time 12 to 24 hours.

[0021] SS4: The solution obtained in SS3 is washed and centrifugally vacuum dried to obtain coupling agent-functionalized graphene oxide-MXene nanosheets; wherein the obtained solution is washed with ethanol 2 to 4 times and with deionized water 1 to 3 times, and the vacuum drying temperature is 40 to 50° C. and the drying time is 10 to 12 hours.

[0022] The preparation method of the functionalized graphene oxide-MXene nanosheet enhanced self-repairing anti-corrosion coating of the present invention comprises the following steps:

[0023] SSS1: Disperse 1 part of functionalized graphene oxide-MXene nanosheets in 1000-30000 solvent II and perform ultrasonic treatment; the solvent II is N,N-dimethylacetamide, the ultrasonic temperature is 22-30°C, and the ultrasonic time is 10-15 minutes. The further preferred ultrasonic conditions are: temperature 25°C, and time 10 minutes.

[0024] SSS2: Add 100-1000 parts of the self-healing polyurethane containing SS bonds to the solution obtained in SSS1 and stir until fully dissolved to obtain an anti-corrosion coating. The stirring temperature is 20-35°C and the stirring speed is 600-800 rpm. More preferably, the stirring conditions are: 32°C and 600 minutes.

[0025] The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating of the present invention is used for corrosion protection on the surface of metal materials: the anti-corrosion coating is applied to the surface of the substrate and the coating is dried; the coating drying conditions are 70-90°C and the drying time is 12-48 hours, and further preferred drying conditions are: temperature 70°C and time 48 hours.

[0026] Compared with the existing technology, the technical solution of the present invention has the following beneficial effects:

[0027] 1) The self-healing anti-corrosion coating provided by the present invention obtains a two-dimensional nanomaterial by hydrolyzing and modifying graphene oxide-MXene nanosheets with a silane coupling agent containing SS bonds. This can greatly improve the dispersibility of graphene oxide-MXene nanosheets in an organic polymer matrix, better exert the electrical conductivity, thermal conductivity and other functions of graphene oxide-MXene nanosheets, and at the same time utilize the silane coupling agent to strengthen the interfacial connection performance between the rigid graphene oxide-MXene nanosheets and the soft polyurethane matrix, utilize the rigid graphene oxide-MXene nanosheets to improve the mechanical strength of the soft matrix, improve the shielding performance of the anti-corrosion coating, and improve the long-term corrosion resistance service performance. In particular, the SS bonds introduced by the silane coupling agent can enhance the self-healing efficiency of the self-healing polyurethane containing SS bonds, thereby greatly improving the service life of the anti-corrosion coating.

[0028] 2) The functionalized graphene oxide-MXene nanosheets used in the self-healing anti-corrosion coating provided by the present invention are obtained by modifying the graphene oxide-MXene nanosheets using a silane coupling agent containing an SS bond. Compared with other silane coupling agents, the silane coupling agent containing an SS bond can produce a corrosion inhibition effect and enhance the corrosion resistance of the coating.

[0029] 3) The functionalized graphene oxide-MXene nanosheets used in the self-healing anti-corrosion coating provided by the present invention have introduced SS bonds that can interact with the SS bonds in the self-healing polyurethane containing SS bonds, and mainly enhance the self-healing process through the transfer and cross-reaction of free radicals (for example, light-induced uniform cleavage of disulfide bonds, and the generated thiol radicals can trigger the cleavage of multiple disulfide bonds and exchange with another disulfide bond unit or directly and simply undergo cross-recombination), thereby compensating for the damage to the self-healing properties of the matrix caused by the simple addition of rigid two-dimensional nanomaterials.

[0030] 4) The self-repairing anti-corrosion coating provided by the present invention forms an anti-corrosion coating on the surface of the metal material, which has high corrosion potential, low corrosion current density, large coating resistance, and self-healing function. It can effectively avoid metal corrosion and oxidation and extend the service life of the metal material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the microstructure of graphene oxide-MXene nanosheets functionalized with silane coupling agent Si69.

[0032] Figure 2 These are the electrochemical impedance spectroscopy graphs of the coating in Example 1 repaired 1 hour and 1 day after being scratched.

[0033] Figure 3 These are the electrochemical impedance spectroscopy graphs of the coating in Example 2 repaired 1 hour and 1 day after being scratched.

[0034] Figure 4This is the electrochemical impedance spectroscopy graph of the self-healing test of the coating prepared in Comparative Example 1.

[0035] Figure 5 This is the electrochemical impedance spectroscopy graph of the self-healing test of the coating prepared in Comparative Example 2. DETAILED DESCRIPTION

[0036] The following examples are intended to further illustrate the present invention in detail and are not intended to further limit the scope of protection of the claims of the present invention.

[0037] In the following specific embodiments,

[0038] Graphene oxide was purchased from: Source Leaf Biotechnology (monolayer, 98%).

[0039] MXene preparation method: 1g Ti3AlC2 powder (Rohn, titanium aluminum carbide powder, 98%, 200 mesh) was gradually added to a PTFE beaker containing LiF (1.6g) and 12M HCl (20mL) under stirring and ice bath conditions. The temperature was then heated to 40°C and stirred for 24 hours. The resulting black solution was centrifuged at 5000rpm for 10 minutes, the bottom precipitate was collected, and washed with 1M dilute hydrochloric acid solution and deionized water until the pH value was about 6. Subsequently, the collected precipitate was added to deionized water, ice bathed, and ultrasonically treated for 2 hours under nitrogen protection. The upper liquid was then collected and freeze-dried to obtain a few-layer MXene powder.

[0040] Preparation of graphene oxide-MXene nanosheets: 100 mg of graphene oxide powder and 20 mg of MXene powder were placed in a beaker containing a certain amount of deionized water and ultrasonicated for 15 minutes to obtain a uniform mixed suspension. The mixed solution was then stirred continuously for 10 hours to ensure sufficient reaction. Finally, the suspension was freeze-dried in a vacuum freeze dryer and stored for later use.

[0041] Preparation of a self-healing polyurethane containing SS bonds: Dihydroxy-terminated PDMS (commercial product, 4.0 g) was placed in a two-necked flask, stirred at 110°C for 1 hour, and then cooled to 70°C. Isophorone diisocyanate (0.934 g, 4.2 mmol) and dibutyltin dilaurate (0.04 g) were dissolved in N,N-dimethylacetamide. The mixed solution was added dropwise to the two-necked flask. Stirring was continued for 3 hours to obtain a diisocyanate-terminated prepolymer. Then, 4,4'-dithiodiphenylamine (0.248 g, 1 mmol) and isophorone diamine (0.17 g, 1 mmol) were dissolved in DMAc and added to the blood vessel. This step was carried out under magnetic stirring for 3 hours. The product was cured in a Teflon mold and dried in a vacuum at 90°C for 720 minutes.

[0042] Example 1

[0043] Preparation of coupling agent functionalized graphene oxide-MXene nanosheets:

[0044] Disperse 1 part of graphene oxide-MXene nanosheets in a mixed solution of 20 parts of anhydrous ethanol and water, with a volume ratio of distilled water of 9:1, and ultrasonicate in a water bath at 25°C for 10 minutes. Use glacial acetic acid to adjust the pH of the solution to 3-4; add 2 parts of Si69 silane coupling agent to the acidic solution, stir in a water bath at 25°C for 24 hours until the reaction is complete; wash the reaction solution 3 times with anhydrous ethanol solution, then wash it 2 times with deionized water, centrifuge it at 5000rpm for 20 minutes, collect the bottom precipitate, and dry it at 40°C under vacuum for 10 hours to finally obtain coupling agent functionalized graphene oxide-MXene nanosheets; Figure 2 This is a scanning electron micrograph of graphene oxide-MXene nanosheets functionalized with Si69 silane coupling agent.

[0045] Preparation of anti-corrosion coating:

[0046] One part of functionalized graphene oxide-MXene nanosheets was dispersed in 12,500 parts of N,N-dimethylacetamide solvent and ultrasonicated in a water bath at 25°C for 10 minutes; 500 parts of self-healing polyurethane containing SS bonds were added to the ultrasonically dispersed solution and stirred at 25°C and 600 rpm to fully dissolve it to obtain an anti-corrosion coating.

[0047] Use of anti-corrosion coatings:

[0048] The surface of the magnesium alloy (Mg-1.5Zn-0.5Ca, mass percentage) substrate was ground with 600-1400 mesh sandpaper, cleaned with ethanol or acetone, and then dried for later use;

[0049] With the help of a transfer tool such as a dropper, spread the anti-corrosion coating on a clean magnesium alloy substrate. Use a spin coater to evenly apply the coating to the surface of the magnesium alloy and spin off excess liquid. Repeat the spin coating 6 times.

[0050] The magnesium alloy sample with the coating was placed at 70° C. and dried for 48 hours to obtain the coupling agent-functionalized graphene oxide-MXene anti-corrosion coating.

[0051] Example 2:

[0052] Preparation of coupling agent functionalized graphene oxide-MXene nanosheets:

[0053] Disperse 1 part of graphene oxide-MXene nanosheets in a mixed solution of 20 parts of anhydrous ethanol and water, with a volume ratio of distilled water of 9:1, and ultrasonicate in a water bath at 25°C for 10 minutes. Use glacial acetic acid to adjust the pH of the solution to 3-4; add 2 parts of Si69 silane coupling agent to the acidic solution and stir in a 25°C water bath for 24 hours until the reaction is complete; wash the reaction solution three times with anhydrous ethanol solution and then twice with deionized water, centrifuge at 5000 rpm for 20 minutes, collect the bottom precipitate, and dry it at 40°C under vacuum for 10 hours to finally obtain coupling agent-functionalized graphene oxide-MXene nanosheets;

[0054] Preparation of anti-corrosion coatings

[0055] 1 part of functionalized graphene oxide-MXene nanosheets was dispersed in 20,000 parts of N,N-dimethylacetamide solvent and ultrasonicated in a water bath at 25°C for 10 minutes; 1,000 parts of self-healing polyurethane elastomer containing SS bonds was added to the ultrasonically dispersed solution and stirred at 25°C and 600 rpm to fully dissolve it to obtain an anti-corrosion coating.

[0056] Use of anti-corrosion coatings

[0057] The surface of the magnesium alloy (Mg-1.5Zn-0.5Ca, mass percentage) substrate was ground with 600-1400 mesh sandpaper, cleaned with ethanol or acetone, and then dried for later use;

[0058] With the help of a transfer tool such as a dropper, spread the anti-corrosion coating on a clean magnesium alloy substrate. Use a spin coater to evenly apply the coating to the surface of the magnesium alloy and spin off excess liquid. Repeat the spin coating for 6 layers.

[0059] The magnesium alloy sample with the coating was placed at 70° C. and dried for 48 hours to obtain the coupling agent-functionalized graphene oxide-MXene anti-corrosion coating.

[0060] Comparative Example 1

[0061] Compared with Example 1, the only difference is that unfunctionalized graphene oxide-MXene powder is used.

[0062] Comparative Example 2

[0063] Compared with Example 1, the only difference is that graphene oxide-MXene powder functionalized with a silane coupling agent (KH590) that does not contain a disulfide bond is used.

[0064] test:

[0065] The above examples and comparative examples were subjected to electrochemical impedance spectroscopy, with the test solution containing 3.5 wt% NaCl. Figures 2 to 5 .

[0066] From the electrochemical impedance spectra of the examples and the comparative examples ( Figures 2 to 5 ) observations revealed that, compared to the comparative example in which the damaged coating had no corrosion resistance, the Si69-functionalized coating exhibited improved corrosion resistance one day after repair compared to one hour after repair. Furthermore, the initial corrosion resistance and post-repair corrosion resistance of the coating in Example 2 were significantly improved.

[0067] Therefore, the present invention provides a method for preparing coupling agent-functionalized graphene oxide (MXene) nanosheets with enhanced corrosion resistance and self-healing properties, and its application in anti-corrosion coatings. The use of a silane coupling agent to functionalize the graphene oxide (MXene) nanosheets not only improves the dispersibility of the graphene oxide (MXene) nanosheets, but also enables the disulfide-containing silane coupling agent to provide sustained corrosion inhibition and self-healing properties. This silane coupling agent forms a new film on the magnesium alloy surface and promotes the closure of scratches in damaged areas of the coating, resisting further penetration of corrosive solutions, thereby extending the coating's lifespan.

[0068] The above content only describes one embodiment of the present invention and does not limit the scope of the present invention. Any technically equivalent structural or process changes, or direct or indirect applications in other related technical fields, are included in the scope of protection of the present invention.

Claims

1. A functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating, characterized by: The following mass groups are included: 1 part of functionalized modified graphene oxide-MXene nanosheets; 100-1000 parts of self-repairing polyurethane containing SS bonds; 1000~30000 parts of solvent; The functionalized modified graphene oxide-MXene nanosheets are obtained by hydrolyzing modified graphene oxide-MXene nanosheets with a silane coupling agent containing SS bonds; The self-repairing polyurethane containing SS bonds is prepared by the following method: prepolymerizing dihydroxy-terminated PDMS with isophorone diisocyanate to obtain a diisocyanate-terminated prepolymer, and copolymerizing the diisocyanate-terminated prepolymer with 4, 4'-dithiodiphenylamine and isophorone diamine to obtain; The functionalized modified graphene oxide-MXene nanosheets are prepared by the following method: ultrasonically dispersing the graphene oxide-MXene nanosheets in an alcohol-water mixed solvent, adjusting the pH to an acidic condition, adding a silane coupling agent for an SS bond to carry out a hydrolysis reaction, and sequentially washing, centrifuging, and drying the obtained reaction product to obtain the functionalized modified graphene oxide-MXene nanosheets.

2. The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to claim 1, characterized in that: It is composed of the following mass groups: 1 part of functionalized modified graphene oxide-MXene nanosheets; 500-1000 parts of self-repairing polyurethane containing SS bonds; 2500~25000 parts of solvent.

3. The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to claim 1, characterized in that: The mass ratio of the graphene oxide-MXene nanosheets to the silane coupling agent of the SS bond is 1:1.5~2.5; The pH is adjusted to 3-4; The pH is adjusted using an organic carboxylic acid.

4. The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to claim 3, characterized in that: The silane coupling agent containing SS bond includes Si69.

5. The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to claim 1, characterized in that: The conditions of the hydrolysis reaction are: temperature of 25±2° C. and time of 12 to 24 hours.

6. The functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to claim 1, characterized in that: The solvent includes at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and tetrahydrofuran.

7. The use of a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to any one of claims 1 to 6, characterized in that: Used for corrosion protection of metal surfaces.

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