Functionalized graphene oxide-MXene nanosheet enhanced self-repairing anticorrosive paint and application thereof

Abstract

The invention discloses a functionalized graphene oxide-MXene nanosheet enhanced self-repairing anticorrosive coating and application thereof, and belongs to the technical field of corrosion prevention. The functionalized graphene oxide-MXene nanosheet enhanced type self-repairing anticorrosive paint is prepared from functionalized modified graphene oxide-MXene nanosheets, self-repairing polyurethane containing S-S bonds and a solvent, wherein the functional modified graphene oxide-MXene nanosheet is obtained by hydrolyzing the modified graphene oxide-MXene nanosheet by a silane coupling agent containing an S-S bond, and the special functional modified graphene oxide-MXene nanosheet is introduced into the coating, so that the coating shows enhanced corrosion resistance and self-repairing characteristic, and can be widely applied to corrosion prevention 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] The corrosion problem of metals causes great economic losses every year and is accompanied by more serious safety accidents. Surface coating is the most economical and convenient anti-corrosion method. Two-dimensional fillers are often used to enhance the barrier properties of polymer coatings to improve the corrosion resistance of coatings. Among them, MXene has the advantages of high mechanical strength and good conductivity, but MXene is easy to oxidize and difficult to disperse evenly in organic polymer materials. In the prior art, these shortcomings are usually overcome by modifying MXene nanomaterials. For example, Chinese patent CN114854237A discloses that MXene nanomaterials are modified by silane coupling agents, or MXene nanomaterials are hybridized and coated with graphene-based nanosheets, and then modified by silane coupling agents after coating. MXene nanosheets and graphene-based nanomaterials are covalent hybrids, and graphene nanosheets act as spacers between MXene nanosheets to prevent them from aggregating in nanocomposite polymer matrices. The purpose of selecting covalent silane functionalization is to form a protective layer on the surface of MXene nanosheets, inhibit the oxidation of MXene, and improve the dispersion quality of nanosheets in polymer coatings. Although the patent can use silane coupling agents to improve the dispersibility and stability of two-dimensional nanofillers, the introduction of two-dimensional nanofillers will bring new technical problems to the anti-corrosion coating. A typical example is that the addition of two-dimensional nanofillers will lead to a decrease in the self-healing efficiency of the anti-corrosion coating, thereby reducing the service life of the anti-corrosion coating. Therefore, overcoming the inherent weaknesses of two-dimensional nanofillers and developing anti-corrosion coatings that have both excellent corrosion resistance and promote self-healing efficiency are of great significance for metal corrosion protection, improving work efficiency, and reducing maintenance costs. Summary of the invention

[0003] In view of 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, in which a two-dimensional nanomaterial is obtained by hydrolyzing graphene oxide-MXene nanosheets modified by a silane coupling agent containing SS bonds. The two-dimensional nanomaterial can not only be evenly dispersed in a polyurethane matrix, but can also interact with the disulfide bonds in a 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, the corrosion potential of which increases, the corrosion current density decreases, the coating resistance increases, and 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 anticorrosive coating of the present invention is the introduction of a functionalized graphene oxide-MXene nanosheet composite material, and the surface of the graphene oxide-MXene nanosheet is functionally 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 a dynamic exchange reaction, thereby greatly enhancing the self-healing efficiency of the composite material. Thus, the introduction of functionalized graphene oxide-MXene nanosheets as fillers in the anticorrosive coating can increase the corrosion potential of the anticorrosive coating, reduce the corrosion current density, and increase the coating resistance, and has enhanced corrosion resistance and self-healing properties.

[0007] As a preferred scheme, 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 scheme, 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 scheme, 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, and 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: dihydroxy-terminated PDMS is prepolymerized with isophorone diisocyanate to obtain a diisocyanate-terminated prepolymer, and the diisocyanate-terminated prepolymer is copolymerized 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 agents containing SS bonds is 1:1.5 to 2.5. The modification amount of silane coupling agents containing SS bonds on 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; the pH is adjusted using 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 of 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 applied to metal surface corrosion protection.

[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 and perform ultrasonic treatment; the solution I is a mixed solution of anhydrous ethanol and water, and the volume ratio of anhydrous ethanol to distilled water is 8 to 10:1. The ultrasonic treatment conditions are: temperature of 22 to 30°C, time of 10 to 15 minutes; further preferred ultrasonic conditions are: temperature of 25°C, time of 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 to 4. The pH value can be adjusted using glacial acetic acid.

[0020] SS3: Add 2 parts of silane coupling agent containing SS bond into 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 deionized water 1 to 3 times, the vacuum drying temperature is 40 to 50° C., and the drying time is 10 to 12 hours.

[0022] The method for preparing 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, the ultrasonic time is 10-15 minutes, and further preferred ultrasonic conditions are: temperature is 25°C, and time is 10 minutes.

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

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

[0026] Compared with the prior art, 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 can greatly improve the dispersibility of graphene oxide-MXene nanosheets in an organic polymer matrix by hydrolyzing and modifying graphene oxide-MXene nanosheets with a silane coupling agent containing SS bonds to obtain a two-dimensional nanomaterial, so as to better exert the electrical conductivity, thermal conductivity and other functions of graphene oxide-MXene nanosheets. At the same time, the silane coupling agent is used to strengthen the interface connection performance between the rigid graphene oxide-MXene nanosheets and the soft polyurethane matrix, and the rigid graphene oxide-MXene nanosheets are used to improve the mechanical strength of the soft matrix, thereby improving the shielding performance of the anti-corrosion coating and the long-term corrosion resistance service performance. In particular, the SS bond 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 SS bonds in the self-healing polyurethane containing SS bonds, and the self-healing process is enhanced mainly 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 cross-recombine), 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 Microstructure of graphene oxide-MXene nanosheets functionalized with silane coupling agent Si69.

[0032] Figure 2 The electrochemical impedance spectra of the coating in Example 1 were obtained 1 hour and 1 day after being repaired after being scratched.

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

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

[0035] Figure 5 This is the electrochemical impedance spectrum 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 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 (Ron, titanium 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 method of graphene oxide-MXene nanosheets: 100 mg of graphene oxide powder and 20 mg of MXene powder are placed in a beaker containing a certain amount of deionized water and ultrasonicated for 15 minutes to obtain a uniform mixed suspension. Then the mixed solution is continuously stirred for 10 hours to ensure sufficient reaction. Finally, the suspension is freeze-dried and collected using a vacuum freeze dryer for later use.

[0041] Preparation of self-healing polyurethane containing SS bonds: Dihydroxy-terminated PDMS (commercial product, 4.0 g) was charged into 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 dripped into a two-necked flask. Stirring was continued for 3 hours to obtain a terminal diisocyanate 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 vacuum dried 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 for 24 hours in a 25°C water bath until the reaction is complete; wash the reaction solution 3 times with anhydrous ethanol solution, then wash it twice 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] 1 part of functionalized graphene oxide-MXene nanosheets was dispersed in 12500 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 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 is ground with 600-1400 mesh sandpaper, then cleaned with ethanol or acetone, and then blown dry 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] Embodiment 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 perform water bath ultrasound 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 for 24 hours in a 25°C water bath until the reaction is complete; wash the reaction solution 3 times with anhydrous ethanol solution, then wash it twice 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;

[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 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 is ground with 600-1400 mesh sandpaper, then cleaned with ethanol or acetone, and then blown dry 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) without disulfide bonds is used.

[0064] test:

[0065] The above examples and comparative examples were subjected to electrochemical impedance tests, and the test solution was 3.5wt% NaCl. The test results are shown in Figures 2 to 5 .

[0066] From the electrochemical impedance spectra of the examples and the comparative examples ( Figures 2 to 5 ) It was found in the observation that compared with the characteristic of the damaged coating in the comparative example that the repaired coating has no corrosion resistance, the corrosion resistance of the Si69 functionalized coating after the coating was damaged and repaired for 1 day is greater than that of the coating repaired for 1 hour. In addition, the initial corrosion resistance and the corrosion resistance after self-repair of the coating in Example 2 are greatly 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 silane coupling agent functionalized graphene oxide-MXene nanosheets improves the dispersibility of graphene oxide-MXene nanosheets on the one hand, and the silane coupling agent containing disulfide bonds can continuously provide corrosion inhibition and self-healing effects, because it forms a new film layer on the surface of the magnesium alloy and promotes the closure of scratches on the damaged part of the coating to resist further penetration of corrosive solutions, thereby improving the life of the coating.

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

Claims

1. A functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating, Features: The invention comprises functionalized modified graphene oxide-MXene nanosheets, self-healing polyurethane containing SS bonds and 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.

2. A functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating according to claim 1, Features: 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 to 30000 parts of solvent.

3. A functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating according to claim 1 or 2, Features: 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 to 25000 parts of solvent.

4. A functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating according to claim 3, Features: 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 the obtained product.

5. The functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating according to claim 3, Features: 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 with an SS bond to carry out a hydrolysis reaction, and sequentially washing, centrifuging, and drying the obtained reaction products to obtain the functionalized modified graphene oxide-MXene nanosheets.

6. The functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating according to claim 5, Features: The mass ratio of the graphene oxide-MXene nanosheets to the silane coupling agent of the SS bond is 1:1.5 to 2.5; The pH is adjusted to 3-4; The pH is adjusted using an organic carboxylic acid.

7. The functionalized graphene oxide-MXene nanosheet enhanced self-healing anti-corrosion coating according to claim 5, Features: The silane coupling agent containing SS bonds includes Si69.

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

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

10. Application of a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating according to any one of claims 1 to 9, Features: Used for corrosion protection of metal surfaces.

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