PH-responsive Ti3C2Tx-based polyvinyl butyral self-repairing anticorrosive coating and preparation method thereof

Abstract

The invention discloses a pH response Ti < 3 > C < 2 > T < x >-based polyvinyl butyral self-repairing anti-corrosion coating and a preparation method thereof. The preparation method comprises the following steps: preparing Ti < 3 > C < 2 > T < x > (at) PDA by polymerizing dopamine on the surface of a Ti < 3 > C < 2 > T < x > (at) PDA, loading Ce-P-I < m >-MOF onto the Ti < 3 > C < 2 > T < x > (at) PDA, finally mixing into polyvinyl butyral-methanol, and coating on the surface of a copper plate to obtain the pH-responsive Ti < 3 > C < 2 > T < x >-based polyvinyl butyral self-repairing anticorrosive coating. Wherein PDA has the dual effects of improving the dispersibility and oxidation resistance of Ti3C2Tx and inhibiting corrosion promotion; imidazole in Ce-P-Im-MOF responds to the pH change of a corrosion area through redox cycle, cerium ions and phosphate radicals are dynamically released to form a passivation film, the Ti3C2Tx nanosheet labyrinth effect is overlaid, a'dynamic passivation-physical shielding-conductive regulation 'triple anti-corrosion mechanism is formed, and the corrosion resistance of a matrix is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anti-corrosion coating materials, and specifically relates to a pH-responsive Ti3C2T x Based on polyvinyl butyral self-repairing anti-corrosion coating. Background Art

[0002] Polyvinyl butyral is a thermoplastic polymer material. Due to its excellent heat resistance, film-forming properties, high stretchability and impact resistance, its application in the field of coatings has attracted more and more attention and research. At the same time, the presence of hydroxyl groups in polyvinyl butyral molecules provides active sites for chemical reactions, providing more possibilities for the preparation of composite coatings through chemical modification. However, the entanglement of polyvinyl butyral molecular chains will leave a large amount of free volume, thereby forming a large number of micropores in the coating, which are easily penetrated by corrosive media. For this reason, many researchers have embedded various anti-corrosion materials or pigments, such as mica flakes, iron oxide, zinc powder, etc., but because of their small specific surface area and large addition amount, the structural density of the composite coating is seriously damaged. In recent years, Ti3C2T x As a new type of two-dimensional material, it has great application potential in the field of corrosion protection due to its rich surface functional groups, large specific surface area and excellent mechanical properties. x The anti-corrosion protection of polymer coatings can be enhanced by improving their barrier properties. However, once the integrity of the coating is destroyed, its only barrier property fails, allowing the corrosive medium to penetrate into the metal surface and cause corrosion. x It also has excellent high conductivity. When Ti3C2T x When it comes into contact with a metal substrate, a corrosion galvanic cell will be formed under the immersion of the corrosive electrolyte, which will accelerate the corrosion of the metal.

[0003] Therefore, it is necessary not only to give the coating an active protection function to ensure that when the integrity of the coating is damaged, the response mechanism can be stimulated to release substances to inhibit the further occurrence of corrosion, but also to inhibit the Ti3C2T x It is an urgent problem to be solved by those skilled in the art to significantly improve the corrosion-promoting effect of polyvinyl butyral composite coatings. Summary of the Invention

[0004] The purpose of the present invention is to provide a pH-responsive Ti3C2T x A method for preparing a polyvinyl butyral self-repairing anti-corrosion coating based on polyvinyl butyral is described. The goal is to ensure that when the coating's integrity is damaged, it can trigger a response mechanism and release corrosion inhibitors to inhibit further corrosion, thereby giving the coating an active protective function.

[0005] To achieve the above object, the application adopts the following technical scheme: A pH-responsive Ti3C2T x The preparation method of the polyvinyl butyral self-repairing anticorrosive coating comprises the following steps: (1) Dissolve LiF in 12 mol / L HCl solution, add Ti3AlC2 powder, stir in water bath for 24 h, cool to room temperature, centrifugal wash with deionized water until the supernatant pH is 6, the obtained supernatant is placed in ice water under nitrogen protection, ultrasonic, centrifugal at 3500 rpm, finally take the supernatant freeze-drying to obtain Ti3C2T x nanosheet; (2) Add Ti3C2T x nanosheet into Tris buffer solution, ice water ultrasonic for 30 min, add dopamine, magnetic stirring for 24 h, after reaction, centrifugal, washing, freeze-drying to obtain Ti3C2T x @PDA; (3) Ultrasonic dispersion of Ti3C2T x @PDA into methanol to obtain a dispersion, dissolve cerium nitrate hexahydrate in methanol and add into the dispersion, stirring reaction for 30 min, add dimethyl imidazole methanol solution, reaction at room temperature for 24 h, after centrifugal, washing, the precipitate is freeze-dried to obtain a powder, ultrasonic dispersion of the powder into ion water, add Na3PO4, adjust pH to 9.5 with HCl, vacuum stirring reaction for 1 h, after centrifugal, washing, freeze-drying to obtain pH-responsive Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosive material; (4) Weigh the anticorrosive material obtained in step (3) and ultrasonic dispersion into methanol, then add polyvinyl butyral powder, stirring for 6 h, then coat it on a copper plate and dry at 30℃ for 48 h to obtain pH-responsive Ti3C2T x based polyvinyl butyral self-repairing anticorrosive coating.

[0006] Further, the mass ratio of LiF and Ti3AlC2 powder in step (1) is 1:1, and the solid-liquid ratio of LiF and HCl solution is 1g:20mL.

[0007] Further, the temperature of the water bath in step (1) is 35℃.

[0008] Further, the power of the ultrasonic in step (1) is 350W, and the time is 1h.

[0009] Further, the mass ratio of Ti3C2T x nanosheet and dopamine in step (2) is 1:1, and the mass ratio of Ti3C2T xThe solid-liquid ratio of nanosheets and Tris buffer was 1 g:2000 mL.

[0010] Furthermore, the Ti3C2T x The mass ratio of PDA, cerium nitrate hexahydrate and dimethylimidazole is 1:10:20.

[0011] Furthermore, the mass ratio of the powder and Na3PO4 in step (3) is 1:10.

[0012] Furthermore, the amount of the anti-corrosion material added in step (4) accounts for 0.2-1.0 wt % of the polyvinyl butyral powder.

[0013] pH-responsive Ti3C2T prepared by the above preparation method x Polyvinyl butyral self-repairing anti-corrosion coating, Ti3C2T in anti-corrosion coating x @PDA-Ce-P-Im-MOF releases Ce under acidic conditions 3+ and PO3- 4, releasing PO3- 4 under alkaline conditions; the acidic conditions are pH=2~4, and the alkaline conditions are pH=10~12.

[0014] The principle of the present invention is: Ti3AlC2 can be exfoliated into Ti3C2T by etching and then ultrasonic treatment. x Nanosheets, the Ti3C2T x Nanosheets are a new type of two-dimensional layered material. Compared with other two-dimensional layered materials, they have a large specific surface area, excellent mechanical properties and rich functional groups on the surface. They can be used as an excellent anti-corrosion reinforcement material in polyvinyl butyral coatings. The surface is then coated with insulating material dopamine. The introduction of polydopamine layer (PDA) can effectively improve the properties of Ti3C2T through its rich hydrophilic groups (such as hydroxyl and amino groups). x The dispersion of nanosheets in the solution avoids agglomeration caused by van der Waals forces. At the same time, PDA acts as a dense physical barrier to isolate oxygen and moisture from Ti3C2T x The direct contact of PDA significantly delays its oxidative degradation process. In addition, the insulating properties of PDA can hinder the x The electron transfer between the highly conductive surface and the corrosive medium inhibits its tendency to act as a conductive pathway to accelerate the electrochemical corrosion of the metal substrate. In addition, the cerium-based phosphate-imidazole metal organic framework (Ce-P-Im-MOF) was loaded onto the Ti3C2T x Preparation of pH-responsive Ti3C2T@PDA xThe anti-corrosion material @PDA-Ce-P-Im-MOF was mixed into a polyvinyl butyral-methanol solution and coated on the surface of a copper plate to form a pH-responsive Ti3C2T x Polyvinyl butyral self-repairing anti-corrosion coating based on Ce-P-Im-MOF: The imidazole (Im) of Ce-P-Im-MOF responds to the pH change of the corrosion micro-area through redox cycle, dynamically releases cerium ions and phosphates to form a dense passivation film, inhibiting the dissolution of the anode metal. x The nanosheets form a tortuous, maze-like physical barrier (a labyrinth effect) within the coating, hindering the diffusion path of corrosive media or molecules, significantly improving the material's resistance to penetration and protective properties. Ultimately, this creates a triple anti-corrosion mechanism of "dynamic passivation - physical shielding - and conductive regulation," significantly enhancing the long-term corrosion resistance of the metal substrate.

[0015] The significant advantages of the present invention are: 1. Using Ti3AlC2 as raw material, it is peeled off into Ti3C2T by simple HCl+LiF etching and ultrasonic treatment. x Nanosheets, obtained Ti3C2T x The nanosheets are two-dimensional layered materials with complete structure, which can provide excellent barrier effect for composite coatings. x Nanosheets are a new type of two-dimensional layered material with a large specific surface area (30m 2 / g), excellent mechanical properties (tensile strength 20~50·GPa) and rich functional groups (-O, -OH, -F) on the surface, making it an excellent anti-corrosion reinforcement material in polyvinyl butyral coatings.

[0016] 2. The present invention uses insulating material dopamine to coat Ti3C2T x The introduction of polydopamine (PDA) nanosheets can effectively improve the properties of Ti3C2T by its abundant hydrophilic groups (such as hydroxyl and amino groups). x The dispersion of nanosheets in the solution avoids agglomeration caused by van der Waals forces. At the same time, PDA acts as a dense physical barrier to isolate oxygen and moisture from Ti3C2T x The direct contact of PDA significantly delays its oxidative degradation process. In addition, the insulating properties of PDA can hinder the x The electron transfer between the highly conductive surface and the corrosive medium inhibits its tendency to act as a conductive pathway to accelerate the electrochemical corrosion of the metal substrate.

[0017] 3. pH-responsive Ti3C2T prepared by the present invention xThe PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. 3+ The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained.

[0018] 4、The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained. x The PDA-Ce-P-Im-MOF anticorrosion material is obtained by loading Ce-P-Im-MOF on the surface of Ti3C2Tx nanosheets through electrostatic adsorption, hydrogen bonding and mild chemical bonding, and the process does not damage the structure of Ti3C2Tx nanosheets, and the excellent barrier property of Ti3C2Tx nanosheets is completely retained.x SEM images of PDA-Ce-P-Im-MOF and Ce-P-Im-MOF.

[0020] Figure 2 Ti3C2T x nanosheets, Ti3C2T x PDA, Ti3C2T x FT-IR images of PDA-Ce-P-Im-MOF and Ce-P-Im-MOF.

[0021] Figure 3 Ti3C2T x nanosheets, Ti3C2T x PDA, Ti3C2T x XRD images of PDA-Ce-P-Im-MOF and Ce-P-Im-MOF.

[0022] Figure 4 EIS spectra of the composite coatings (with artificial scratches) prepared in Examples 1-3 and Comparative Examples 1-3.

[0023] Figure 5 EIS spectra of the composite coatings prepared in Examples 1-3 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0024] In order to make the content described in the present application more convenient to understand, the technical solutions described in the present application will be further described below in combination with specific embodiments, but the present application is not limited thereto.

[0025] Example 1 (0.2wt% pH-responsive Ti3C2T x based polyvinyl butyral self-repairing anticorrosive coating) (1) Preparation of Ti3C2T x nanosheets: In a polytetrafluoroethylene beaker, 1 g of LiF and 20 mL of HCl solution (12 mol / L) were added and stirred for 30 min until it was completely dissolved, then 1 g of Ti3AlC2 powder was added, and stirred in a 35℃ water bath for 24 h. After natural cooling to room temperature, the supernatant was washed by centrifugation with deionized water until the pH value of the supernatant reached 6. Then the last obtained supernatant was ultrasonicated in ice water under nitrogen protection at a power of 350 W for 1 h, and then the supernatant was centrifuged at a speed of 3500 rpm for 10 min. Finally, the supernatant was freeze-dried to obtain Ti3C2T x nanosheets.

[0026] (2) Preparation of Ti3C2T x @PDA 0.1 g of Ti3C2T xThe nanosheets were added into 200 mL Tris buffer solution (pH = 8.5), and after ice water ultrasonic treatment for 30 min, 0.1 g dopamine was added, and magnetic stirring was performed for 24 h. After the reaction was completed, centrifugal washing was performed three times with deionized water, and finally freeze-drying was performed, to obtain Ti3C2T x @PDA.

[0027] (3) pH-responsive Ti3C2T x @Preparation of PDA-Ce-P-Im-MOF Take 0.1 g Ti3C2T x @PDA was added into 50 mL methanol, and after ultrasonic treatment for 30 min, Ti3C2T x @PDA methanol dispersion solution, then 1 g of cerium nitrate hexahydrate was added into 20 mL of methanol, and after stirring until completely dissolved, Ti3C2T x @PDA methanol dispersion solution, and after stirring for 30 min, 30 mL of methanol containing 2 g of dimethyl imidazole was added. After reaction at room temperature for 24 h, centrifugal washing was performed three times with methanol at a rotation speed of 4000 rpm, and the obtained precipitate was freeze-dried to obtain a powder. Then, 0.1 g of the above powder was added into 100 mL of deionized water and ultrasonic dispersed for 30 min, 1 g of Na3PO4 was added, and the pH was adjusted to 9.5 with HCl. After vacuum stirring for 1 h, centrifugal washing was performed three times with deionized water at a rotation speed of 4000 rpm, and finally the precipitate was freeze-dried to obtain pH-responsive Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosion material.

[0028] (4) pH-responsive Ti3C2T x @Preparation of pH-responsive Ti3C2T Take 5 mg Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosion material was added into 25 mL of methanol, and after ultrasonic treatment for 30 min, 2.5 g of polyvinyl butyral powder was added, and then continuous stirring was performed for 6 h. Then, it was coated on a copper plate by means of an 80 μm coating rod, and then placed in a 30 °C oven for drying for 48 h, to obtain pH-responsive Ti3C2T x @Preparation of pH-responsive Ti3C2T

[0029] The preparation method of Ce-P-Im-MOF is as follows: Ce-P-Im-MOF was prepared by the following method: 1 g of cerium nitrate hexahydrate was added to 20 mL of methanol, stirred for 30 min, then 30 mL of methanol containing 2 g of dimethylimidazole was added, and the reaction was carried out at room temperature for 24 h, then the obtained precipitate was washed with methanol at a rotation speed of 4000 rpm for three times, and the obtained powder was freeze-dried. Then, 0.1 g of the above powder was added to 100 mL of deionized water and ultrasonically dispersed for 30 min, 1 g of Na3PO4 was added, and the pH was adjusted to 9.5 with HCl, and the reaction was carried out under vacuum stirring for 1 h, then the obtained precipitate was washed with deionized water at a rotation speed of 4000 rpm for three times, and finally freeze-dried to obtain Ce-P-Im-MOF.

[0030] Example 2 (0.5wt% pH-responsive Ti3C2T x Polyvinyl butyral self-healing anticorrosion coating) (1) Preparation of Ti3C2T x nanosheets: In a polytetrafluoroethylene beaker, 1 g of LiF and 20 mL of HCl solution (12 mol / L) were added, stirred for 30 min until it was completely dissolved, then 1 g of Ti3AlC2 powder was added, and stirred in a 35°C water bath for 24 h, then the obtained precipitate was cooled to room temperature, and washed with deionized water until the pH of the supernatant reached 6, then the obtained supernatant was ultrasonically treated in ice water under nitrogen protection at a power of 350 W for 1 h, then the supernatant was centrifuged at a rotation speed of 3500 rpm for 10 min, and finally the supernatant was freeze-dried to obtain Ti3C2T x nanosheets.

[0031] (2) Preparation of Ti3C2T x @PDA 0.1 g of Ti3C2T x nanosheets was added to 200 mL of Tris buffer (pH = 8.5), ultrasonically treated in ice water for 30 min, then 0.1 g of dopamine was added, and magnetically stirred for 24 h, then the obtained precipitate was washed with deionized water for three times, and finally freeze-dried to obtain Ti3C2T x @PDA.

[0032] (3) Preparation of pH-responsive Ti3C2T x @PDA-Ce-P-Im-MOF 0.1 g of Ti3C2T x @PDA was added to 50 mL of methanol, and ultrasonically treated for 30 min to obtain a methanol dispersion of Ti3C2T x @PDA, then 1 g of cerium nitrate hexahydrate was added to 20 mL of methanol, stirred until it was completely dissolved, and then Ti3C2T xAfter stirring for 30 min, 30 mL of methanol containing 2 g of dimethylimidazole was added, and the reaction was allowed to proceed at room temperature for 24 h. The resulting precipitate was washed three times with methanol at 4000 rpm, and then the powder was obtained by freeze-drying. Next, 0.1 g of the powder was added to 100 mL of deionized water and ultrasonically dispersed for 30 min. After 1 g of Na3PO4 was added, the pH was adjusted to 9.5 with HCl, and the reaction was allowed to proceed under vacuum for 1 h. The resulting precipitate was washed three times with deionized water at 4000 rpm, and then freeze-drying was performed to obtain a pH-responsive Ti3C2T x PDA-Ce-P-Im-MOF anticorrosive material

[0033] (4) Preparation of a pH-responsive Ti3C2T x polyvinyl butyral self-healing anticorrosive coating 12.5 mg of Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosive material was added to 25 mL of methanol, ultrasonically treated for 30 min, and then 2.5 g of polyvinyl butyral powder was added. Subsequently, stirring was continued for 6 h, and then the mixture was coated on a copper plate using an 80-μm film coating rod. The coated plate was then placed in an oven at 30°C and dried for 48 h to obtain a pH-responsive Ti3C2T x polyvinyl butyral self-healing anticorrosive coating.

[0034] Example 3 (1.0 wt% pH-responsive Ti3C2T x polyvinyl butyral self-healing anticorrosive coating) (1) Preparation of Ti3C2T x nanoplatelets: In a polytetrafluoroethylene beaker, 1 g of LiF and 20 mL of an HCl solution (12 mol / L) were added, and stirring was performed for 30 min until the LiF was completely dissolved. Subsequently, 1 g of Ti3AlC2 powder was added, and stirring was performed in a 35°C water bath for 24 h. After the mixture was allowed to cool to room temperature, the supernatant was washed with deionized water until the pH of the supernatant reached 6. Subsequently, the supernatant obtained after the last washing was ultrasonically treated in ice water under nitrogen protection at a power of 350 W for 1 h. The supernatant was then centrifuged at 3500 rpm for 10 min, and finally freeze-drying was performed to obtain Ti3C2T x nanoplatelets.

[0035] (2) Preparation of Ti3C2T x @PDA 0.1 g of Ti3C2T xThe nanosheets were added into 200 mL Tris buffer solution (pH = 8.5), and after ice water ultrasonic treatment for 30 min, 0.1 g dopamine was added, and magnetic stirring was performed for 24 h. After the reaction was completed, centrifugal washing was performed three times with deionized water, and finally freeze-drying was performed to obtain Ti3C2T x @PDA.

[0036] (3) pH-responsive Ti3C2T x @Preparation of PDA-Ce-P-Im-MOF Take 0.1 g Ti3C2T x @PDA was added into 50 mL methanol, and after ultrasonic treatment for 30 min, Ti3C2T x @PDA methanol dispersion solution, then 1 g of cerium nitrate hexahydrate was added into 20 mL of methanol, and after stirring until completely dissolved, Ti3C2T x @PDA methanol dispersion solution, after stirring for 30 min, 30 mL of methanol containing 2 g of dimethyl imidazole was added, and after reaction at room temperature for 24 h, centrifugal washing was performed three times with methanol at a rotation speed of 4000 rpm, and then the obtained precipitate was freeze-dried to obtain a powder. Then, 0.1 g of the above powder was added into 100 mL of deionized water and ultrasonic dispersed for 30 min, 1 g of Na3PO4 was added, and then the pH was adjusted to 9.5 with HCl, vacuum stirring was performed for 1 h, and then centrifugal washing was performed three times with deionized water at a rotation speed of 4000 rpm, and finally the precipitate was freeze-dried to obtain pH-responsive Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosion material.

[0037] (4) pH-responsive Ti3C2T x Preparation of pH-responsive Ti3C2T Take 25 mg Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosion material was added into 25 mL of methanol, and after ultrasonic treatment for 30 min, 2.5 g of polyvinyl butyral powder was added, and then continuous stirring was performed for 6 h, and then it was coated on a copper plate through an 80 μm film coating rod, and then it was placed in a 30°C oven for drying for 48 h to obtain pH-responsive Ti3C2T x @pH-responsive Ti3C2T

[0038] Comparative Example 1 (pure polyvinyl butyral composite coating) (1) Preparation of pure polyvinyl butyral composite coating Take 2.5 g of polyvinyl butyral powder and add it into 25 mL of methanol, and then continuous stirring was performed for 6 h, and then it was coated on a copper plate through an 80 μm film coating rod, and then it was placed in a 30°C oven for drying for 48 h to obtain a pure polyvinyl butyral composite coating.

[0039] Comparative Example 2 (0.5wt% Ti3C2T x Polyvinyl butyral anti-corrosion coating) (1) Ti3C2T x Preparation of nanosheets: 1 g of LiF and 20 mL of HCl solution (12 mol / L) were added to a polytetrafluoroethylene beaker and stirred for 30 min until they were completely dissolved. Then, 1 g of Ti3AlC2 powder was added and stirred in a water bath at 35 ° C for 24 h. After it was naturally cooled to room temperature, it was centrifuged and washed with deionized water until the pH value of the supernatant reached 6. The supernatant obtained for the last time was ultrasonicated in ice water under nitrogen protection at 350 W power for 1 h, and then the supernatant was centrifuged at 3500 rpm for 10 min. Finally, the supernatant was freeze-dried to obtain Ti3C2T x Nanosheets.

[0040] (2) Ti3C2T x Preparation of polyvinyl butyral anticorrosion coating Weigh 12.5 mg Ti3C2T x The mixture was added to 25 mL of methanol and ultrasonically treated for 30 min before adding 2.5 g of polyvinyl butyral powder. The mixture was then stirred for 6 h and coated on a copper plate using an 80 μm coating rod. The mixture was then dried in an oven at 30 °C for 48 h to obtain Ti3C2T x Based on polyvinyl butyral anti-corrosion coating.

[0041] Comparative Example 3 (0.5wt% Ti3C2T x @PDA polyvinyl butyral anti-corrosion coating) (1) Ti3C2T x Preparation of nanosheets: 1 g of LiF and 20 mL of HCl solution (12 mol / L) were added to a polytetrafluoroethylene beaker and stirred for 30 min until they were completely dissolved. Then, 1 g of Ti3AlC2 powder was added and stirred in a water bath at 35 ° C for 24 h. After it was naturally cooled to room temperature, it was centrifuged and washed with deionized water until the pH value of the supernatant reached 6. The supernatant obtained for the last time was ultrasonicated in ice water under nitrogen protection at 350 W power for 1 h, and then the supernatant was centrifuged at 3500 rpm for 10 min. Finally, the supernatant was freeze-dried to obtain Ti3C2T x Nanosheets.

[0042] (2) Ti3C2T x Preparation of @PDA Take 0.1g Ti3C2T xThe nanosheets were added into 200 mL Tris buffer (pH = 8.5), and after ice water ultrasonic treatment for 30 min, 0.1 g dopamine was added, and magnetic stirring was performed for 24 h. After the reaction was completed, centrifugal washing was performed three times with deionized water, and finally freeze-drying was performed, to obtain Ti3C2T x @PDA.

[0043] (3) Ti3C2T x @PDA polyvinyl butyral anticorrosive coating 12.5 mg Ti3C2T x @PDA was added into 25 mL methanol, and after ultrasonic treatment for 30 min, 2.5 g polyvinyl butyral powder was added, followed by continuous stirring for 6 h. Then, it was coated on a copper plate through an 80 μm coating rod, and then placed in a 30 °C oven for drying for 48 h, to obtain Ti3C2T x @PDA polyvinyl butyral anticorrosive coating.

[0044] Figure 1 Ti3C2T x nanosheets, Ti3C2T x @PDA, Ti3C2T x @PDA-Ce-P-Im-MOF SEM diagram: it can be seen that Ti3C2T x nanosheets have a thin lamellar shape and have a wrinkled plane, Ti3C2T x @PDA layer thickness is thickened, and for Ti3C2T x @PDA-Ce-P-Im-MOF surface morphology, it can be found that the lamellar thickness is increased and the particles are attached, Ti3C2T x @PDA-Ce-P-Im-MOF surface attached particles have different sizes and irregularly distributed three-dimensional polyhedral shapes, and the Ce-P-Im-MOF surface is characterized by irregularly aggregated particles, has high roughness, multi-scale pores and complex three-dimensional morphology.

[0045] Figure 2 Ti3C2T x nanosheets, Ti3C2T x @PDA, Ti3C2T x @PDA-Ce-P-Im-MOF FT-IR diagram. Ti3C2T x was mainly identified through the characteristic peak of Ti-O at 537 cm -1 ; after the surface modification of Ti3C2T x with PDA, obvious PDA organic chain bonding peaks can be seen at 760~1200 cm -1 ; Ti3C2T xThe hydroxyl group in PDA appears as a broad peak at 3325 cm in the lower wavenumber range. -1 Left and right; Ti3C2T x The FTIR spectrum of @PDA-Ce-P-Im-MOF describes the phosphate bond (1024 cm -1 ) in dimethylimidazole, the intensity of the peaks corresponding to the carbon and nitrogen bonds in dimethylimidazole decreased, indicating that imidazole was replaced by phosphoric acid to a certain extent, forming a partial cerium phosphate structure; similarly, the FTIR spectrum of Ce-P-Im-MOF described the phosphate bond (1024 cm -1 ) exists.

[0046] Figure 3 Ti3C2T x Nanosheets, Ti3C2T x @PDA、Ti3C2T x XRD pattern of @PDA-Ce-P-Im-MOF: Ti3C2T x , the peaks at 6.8° and 28° belong to Ti3C2T x (002) and (004) crystal planes; dopamine on Ti3C2T x Ti3C2T after surface polymerization x The interlayer spacing is slightly widened and the (002) crystal plane is moved to a lower diffraction degree, indicating that PDA x Interlayer coating; Ti3C2T x In the @PDA-Ce-P-Im-MOF sample, the characteristic peaks at 28.7°, 47.3°, and 56.4° can be attributed to the (111), (220), and (311) crystal planes, respectively, but the broader peak shape indicates that the crystallinity of the cerium-based MOF (Ce-P-Im-MOF) is relatively low.

[0047] Application Examples The pH-responsive Ti3C2T prepared in Examples 1 to 3 x The pH response test of the @PDA-Ce-P-Im-MOF anticorrosive material was carried out; and the anticorrosive performance test of the anticorrosive coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was carried out, respectively. The specific methods and results are as follows: Ti3C2T x pH response test of @PDA-Ce-P-Im-MOF anticorrosion material The pH-responsive Ti3C2T prepared in Examples 1 to 3 was studied using an ICP-OES tester. x pH response capability of PDA-Ce-P-Im-MOF anticorrosive material. 100 mg of pH-responsive Ti3C2T prepared in Examples 1 to 3 was added. xThe PDA-Ce-P-Im-MOF anticorrosive materials were respectively placed in 100 mL of 3.5wt% NaCl solution, and soaked for 24 h under different pH conditions (2-4, 7, 10-12), and then centrifuged to take the supernatant for ICP-OES test.

[0048] Table 1 pH response test As shown in Table 1, the pH response of the Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosive materials was tested. The results show that the Ti3C2T x @PDA-Ce-P-Im-MOF prepared in Examples 1-3 can release Ce 3+ and PO3-4under acidic conditions, can only release PO3-4under alkaline conditions, and almost no Ce 3+ and PO3-4under neutral conditions. The difference in pH response is due to the environmental response characteristics of the coordination chemistry of Ce-P-Im-MOF: in an acidic medium, protons (H⁺) prefer to protonate the pyrrole nitrogen of the imidazole ring, weakening the coordination stability of Ce 3+ , while H⁺ combines with PO3-4to form soluble H2PO-4, realizing the coordinated release of Ce 3+ and PO3-4; under alkaline conditions, the unprotonated imidazole maintains the framework-fixed Ce 3+ , but the high concentration of OH⁻causes the hydrolysis and dissociation of the phosphate ligand, resulting in the release of PO3-4; in a neutral environment, neither sufficient H⁺to trigger the protonation effect nor excess OH⁻to drive the ligand hydrolysis, the MOF maintains structural integrity, so the ion release is significantly inhibited.

[0049] The anticorrosive materials obtained in Comparative Examples 1-3 have no pH response effect because they do not contain Ce-P-Im-MOF.

[0050] Anticorrosion performance test The electrochemical workstation was used to study the anticorrosion performance of the coating by electrochemical impedance spectroscopy (EIS). The EIS test frequency range was 10 -2 ~10 5 Hz, and the sine wave signal amplitude was 20 mV. The electrolytic cell used a three-electrode system, and the copper plate coated with the organic coating (with a circular test area of 1 cm 2 ) was used as the working electrode, and the saturated calomel electrode and platinum wire were used as the reference electrode and the counter electrode, respectively. The sample was immersed in 3.5wt% NaCl solution for EIS electrochemical performance test.

[0051] The dynamic passivation function of the composite coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 3 (with artificial scratches) was studied by EIS in 3.5 wt % NaCl solution for 90 h. The results are shown in FIG. Figure 4 As shown in Figure 2, during the immersion period of the coating, the response peaks in the Bode phase diagrams of Example 1, Example 3, and Comparative Examples 1-2 all shifted to the low-frequency region. However, the response peak of the Bode phase diagram of Example 2 shifted to the high-frequency region with increasing immersion time, which was attributed to the 0.5wt% Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosion material (Example 2) pH response mechanism: During the immersion process, when a small amount of electrolyte penetrates into the interface of the anticorrosion material, the pH response mechanism of Ce-P-Im-MOF is activated, dynamically releasing Ce 3+ and PO3- 4, Ce 3+ The PO₃₄ and PO₃₄ ...

[0052] The EIS of the composite coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 3 after being immersed in 3.5 wt% NaCl solution for 100 days is as follows: Figure 5 After 100 days of immersion, the Z values ​​of the coatings in Examples 1 to 3 were f＝0.01Hz Values ​​higher than 10 8 Ω·cm 2 , indicating that the anti-corrosion coatings prepared in Examples 1 to 3 have excellent corrosion resistance. Figure 5 It can be found that during the soaking period, Z f＝0.01Hz The value can always be kept above 10 9 Ω·cm 2 , the surface coating has excellent anti-corrosion performance. For the pure polyvinyl butyral self-repairing anti-corrosion coating of comparative example 1, as the immersion time increases, the corrosive medium penetrates along the coating defects to the surface of the copper plate, causing corrosion. f＝0.01Hz Value reduced to 10 4 Ω·cm 2 For Comparative Example 2, during the soaking period, Z f＝0.01Hz The value is initially 10 8 Ω·cm 2 Gradually reduce to 10 4 Ω·cm 2 , derived from the unmodified Ti3C2T in Comparative Example 2 xBecause the flakes agglomerate to form a discontinuous barrier, the electrolyte quickly penetrates and weakens the physical barrier effect. At the same time, its high conductivity forms a micro-galvanic pair with the metal matrix, accelerating the dissolution of the anode and making the low-frequency impedance from 10 8 Down to 10 4 Ω·cm 2 In Comparative Example 3, the PDA layer was used to improve the x However, as the immersion time extended to 100 days, the hydrolysis of the PDA layer led to the degradation of the interface insulation, resulting in the protective performance of the coating declining to 10 after long-term immersion. 8 Ω·cm 2 The root cause is that Ce-P-Im-MOF has not been introduced, and the system cannot respond to pH changes in the corrosion micro-area to release corrosion-inhibiting ions to form a passivation layer.

[0053] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A pH-responsive Ti3C2T x A method for preparing a self-repairing anti-corrosion coating based on polyvinyl butyral, characterized by: The following steps are involved: (1) LiF was dissolved in 12 mol / L HCl solution, Ti3AlC2 powder was added, stirred in a water bath for 24 h, cooled to room temperature, and centrifuged with deionized water until the pH of the supernatant was 6. The supernatant was ultrasonicated in ice water under nitrogen protection, centrifuged at 3500 rpm, and finally the supernatant was freeze-dried to obtain Ti3C2T x nanosheets; (2) Ti3C2T x The nanosheets were added to Tris buffer, ultrasonicated in ice water for 30 min, and then dopamine was added. After stirring for 24 h, the Ti3C2T x @PDA; (3) Ti3C2T x PDA was ultrasonically dispersed in methanol to obtain a dispersion, cerium nitrate hexahydrate was dissolved in methanol and added to the dispersion, stirred for 30 minutes, and a methanol solution of dimethylimidazole was added. The mixture was reacted at room temperature for 24 hours, centrifuged, washed, and precipitated to obtain a powder by freeze-drying. The powder was ultrasonically dispersed in deionized water, Na3PO4 was added, and the pH was adjusted to 9.5 with HCl. The mixture was stirred in vacuum for 1 hour, and then centrifuged, washed, and freeze-dried to obtain pH-responsive Ti3C2T x @PDA-Ce-P-Im-MOF anticorrosion materials; (4) The anticorrosive material obtained in step (3) was weighed and ultrasonically dispersed in methanol, and then polyvinyl butyral powder was added. After stirring for 6 hours, it was coated on a copper plate and dried at 30°C for 48 hours to obtain pH-responsive Ti3C2T x Based on polyvinyl butyral self-repairing anti-corrosion coating.

2. The preparation method according to claim 1, wherein: The mass ratio of LiF and Ti3AlC2 powder in step (1) is 1:1, and the solid-liquid ratio of LiF and HCl solution is 1 g:20 mL.

3. The preparation method according to claim 1, wherein: The temperature of the water bath in step (1) is 35°C.

4. The preparation method according to claim 1, wherein: The power of the ultrasound in step (1) is 350W and the time is 1 hour.

5. The preparation method according to claim 1, wherein: As described in step (2), Ti3C2T x The mass ratio of nanosheets to dopamine is 1:1, and Ti3C2T x The solid-liquid ratio of nanosheets and Tris buffer was 1 g:2000 mL.

6. The preparation method according to claim 1, wherein: Ti3C2T described in step (3) x The mass ratio of PDA, cerium nitrate hexahydrate and dimethylimidazole is 1:10:

20.

7. The preparation method according to claim 1, wherein: The mass ratio of the powder and Na3PO4 in step (3) is 1:

10.

8. The preparation method according to claim 1, wherein: The amount of the anti-corrosion material added in step (4) is 0.2-1.0 wt % of the polyvinyl butyral powder.

9. A pH-responsive Ti3C2T prepared by the method according to any one of claims 1 to 8 x Based on polyvinyl butyral self-repairing anti-corrosion coating.

10. The pH-responsive Ti3C2T3 according to claim 9 x The polyvinyl butyral self-repairing anti-corrosion coating is characterized by: Ti3C2T in anti-corrosion coatings x @PDA-Ce-P-Im-MOF releases Ce under acidic conditions 3+ and PO3- 4, releasing PO3- 4 under alkaline conditions; the acidic conditions are pH=2~4, and the alkaline conditions are pH=10~12.

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