Metal-organic framework-polymer composite corrosion-resistant coating based on soft spray and its preparation

Abstract

The present invention belongs to the field of marine anti-corrosion coating preparation, and specifically relates to a metal-organic framework-polymer composite corrosion-resistant coating based on soft spraying and its preparation. In response to the phenomenon of marine microbial corrosion on metal materials, the present invention prepares a microbial corrosion-resistant coating. The specific method is as follows: using metal, plastic, glass, etc. as a substrate, a precursor solution composed of terephthalic acid and m-phenylenediamine is applied to the substrate surface, and a metal cation solution composed of aqueous copper acetate is sprayed onto the precursor solution on the substrate surface using a soft spray method. At the same time, the metal-organic framework is assembled and the polymer is polymerized. After curing, a metal-organic framework-polymer composite coating CuBDC / PmPD is formed on the substrate surface. This composite coating can protect the substrate from microbial corrosion caused by Gram-negative bacteria in a seawater environment.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of marine anti-corrosion coatings, and in particular relates to a metal organic framework-polymer composite corrosion-resistant coating based on soft spraying and its preparation. Background Art

[0002] The marine environment, due to its unique ecological conditions, breeds a rich and diverse microbial community. While these microorganisms promote the balance of the marine ecosystem, they also pose potential threats to marine engineering facilities, especially marine microbial corrosion.

[0003] Marine microbial corrosion (MBC) refers to the attachment, growth, and formation of biofilms by marine organisms (especially microorganisms) on the surfaces of marine facilities, which in turn accelerates the corrosion of metal materials. This problem is particularly prominent in the field of marine engineering, posing a severe challenge to the safe operation of critical facilities such as ships, offshore platforms, and submarine pipelines. The mechanisms of marine MBC are complex and diverse, primarily including the formation of biofilms, the corrosive effects of microbial metabolites, and electrochemical interactions between microorganisms and metals. Biofilms are protective films formed by microorganisms on metal surfaces, altering the metal surface's microenvironment, such as oxygen concentration, pH, and ion concentration, thereby accelerating the corrosion process. Furthermore, corrosive substances such as organic acids and sulfides produced by microbial metabolism can directly act on metal materials, accelerating their corrosion.

[0004] Among the many processes for preventing and controlling microbial corrosion, a large number of studies have confirmed that metal-organic frameworks (MOFs), porous coordination polymers composed of metal ions and organic ligands through coordination bonds, play a significant role in preventing and controlling biofouling and destroying microbial membrane barriers. However, in marine environments, after microbial attachment and the formation of corrosive biofilms on the surface of metal materials, the process of microbial corrosion can cause local acidity in the microenvironment around the metal surface. This phenomenon may trigger the rapid degradation of MOFs, causing the explosive release of metal ions, resulting in high toxicity in the local marine environment and potential health risks. The above adverse effects have greatly limited the application of MOF materials in the field of preventing and controlling microbial corrosion.

[0005] Metal-organic framework-polymer composites combine the hardness and wear resistance of inorganic materials with the flexibility and processability of organic materials, and have excellent comprehensive properties. This makes it more efficient and has a longer service life in preventing and treating microbial corrosion. Compared with traditional anti-corrosion methods, this inorganic-organic composite material has less impact on the environment during preparation and use, and meets the requirements of sustainable development. At the same time, they can also reduce pollution and damage to the environment and protect the stability of the ecosystem. At present, the commonly used processes for preparing such materials, such as in-situ synthesis methods, have the problem that polymer chains may hinder the uniform distribution of metal-organic frameworks, forming local aggregation or pore blockage; solution mixing methods are prone to incomplete solvent removal and residual solvent in the material, affecting the stability of the material; mechanical mixing methods are difficult to achieve nano-scale dispersion, and metal-organic frameworks may exist in the form of micron-sized aggregates.

[0006] The microbial corrosion-resistant coatings in patents CN110819934A and CN117020223A are both produced by laser cladding or plasma spraying. These coatings have the following drawbacks: (1) they are produced at high temperatures or high voltage currents, resulting in high energy consumption; (2) they have a single function and do not contain a biocide. They only address corrosion issues from the perspective of preventing the intrusion of corrosive media, but cannot fundamentally solve the problem of microbial adhesion. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention is based on a soft spray method to prepare a flexible and surface-uniform metal-organic framework-polymer composite microbial corrosion-resistant coating on the metal surface. The soft spray described in the present invention is a new spray synthesis technology that uses the solution surface as the synthesis location. It has the advantages of uniform spraying, limited space effect, and continuous and simple operation process. It can maintain good dispersion of the metal organic framework during the preparation process. This method is not only simple and efficient, but also can be applied to the surfaces of materials with different morphologies and dimensions, and has high universality. It effectively prevents the corrosion behavior of marine microorganisms and gives the material the function of long-term use.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a metal organic framework-polymer composite microbial corrosion resistant coating based on soft spraying specifically comprises the following steps:

[0010] Step 1: Surface treatment of the substrate material: After substrate pretreatment, the surface of the substrate to be coated is subjected to plasma surface activation treatment to increase the surface energy of the substrate.

[0011] Step 2: Prepare a precursor solution and a metal cation solution: add terephthalic acid (H2BDC) and m-phenylenediamine (mPD) to a mixed organic solvent A to obtain a precursor solution; add anhydrous copper acetate (Cu(CH3COO)2) to a mixed organic solvent B to obtain a metal cation solution.

[0012] Step 3: Infiltrating the surface of the substrate with the precursor solution: coating the surface of the substrate material treated in step 1 with the precursor solution, so that the precursor solution is evenly coated, infiltrated, and fully spread on the surface of the substrate material.

[0013] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as a spray solution. The nozzle of the spray device has an ultrasonic function. The spray solution is ultrasonically sprayed through the nozzle to form atomized droplets. The atomized droplets are further refined under the action of ultrasound. After the atomized droplets come into contact with the precursor solution on the surface of the substrate, the metal organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can be carried out simultaneously. After curing, the metal organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD is formed on the surface of the substrate.

[0014] Furthermore, the substrate in step 1 includes metal, plastic, glass, etc.

[0015] Furthermore, the pretreatment in step 1 refers to ultrasonic cleaning the substrate in a mixed solution of ethanol and acetone with a volume ratio of 1:1 for 60 minutes to 120 minutes and then drying;

[0016] When the substrate is metal, it is polished and then ultrasonically cleaned. The mesh sizes of the sandpaper used for polishing are 240 mesh, 400 mesh, 600 mesh, 800 mesh, and 1000 mesh, respectively.

[0017] Furthermore, the power of the plasma surface activation treatment in step 1 is 60W~310W, and the time is 20s~180s.

[0018] Furthermore, the molar ratio of terephthalic acid to m-phenylenediamine in step 2 is 1:3~1:15, and the mixed organic solvent A is a mixed solvent of N,N-dimethylformamide (DMF) and acetonitrile (CH3CN), both reagents are analytically pure, and the volume ratio is 8:1~5:1.

[0019] Furthermore, the precursor solution in step 2 is first magnetically stirred for 60 min to 150 min, and then ultrasonically dispersed for 20 min to 100 min to mix the solution evenly.

[0020] Furthermore, in step 2, the molar ratio of terephthalic acid to anhydrous copper acetate is 1:1~1:4, and the mixed organic solvent B is a mixed solvent of N,N-dimethylformamide and acetonitrile, with a volume ratio of 1:16~1:1.

[0021] Furthermore, the metal cation solution in step 2 is ultrasonically dispersed for 20 min to 100 min to mix the solution evenly.

[0022] Furthermore, in step 4, the amount of metal cation solution injected into the spray device each time is 1 mL, the flow rate of the metal cation solution is 125 μL / s~200 μL / s, the total duration of ultrasonic spraying is 200 s~800 s, and it is interrupted every 5 s~8 s.

[0023] Furthermore, in step 4, the ultrasonic spray power is 2W to 3W, the nozzle is shaken at an amplitude of 60° to 90°, and the atomized droplets are evenly dispersed on the surface of the substrate coated with the precursor solution. The curing is performed in an environment with a humidity of 40% to 50% for 2 hours to 5 hours.

[0024] The metal-organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD prepared by the above method consists of copper-based metal-organic framework nanosheets composed of anhydrous copper acetate and terephthalic acid, arranged in a stacked structure. The polymer is poly(m-phenylenediamine) (PmPD), formed by the polymerization of m-phenylenediamine induced by copper ions. The polymer encapsulates the copper-based metal-organic framework nanosheets and fills the interstices between the copper-based metal-organic framework sheets. The CuBDC / PmPD coating can protect substrates from microbial corrosion caused by Gram-negative bacteria in seawater environments.

[0025] Compared with the prior art, the metal organic framework-polymer composite microbial corrosion resistant coating prepared by the soft spray method of the present invention has the following beneficial effects:

[0026] Using the principle of synchronous synthesis, Cu 2＋ While assembling with terephthalic acid to form a metal-organic framework (in this case, two-dimensional copper-based metal-organic framework nanosheets, namely, CuBDC in the CuBDC / PmPD composite coating, referred to as MOFs), the coating catalyzes the oxidative polymerization of m-phenylenediamine to poly(m-phenylenediamine), imparting antibacterial properties while significantly enhancing its corrosion resistance. Furthermore, due to the presence of interchain interactions, such as hydrogen bonds, these interactions allow the poly(m-phenylenediamine) to deform somewhat under external forces, preventing it from fracturing. Consequently, poly(m-phenylenediamine) possesses good toughness, offering a certain degree of resistance to impact and fatigue damage. This significantly improves the coating's mechanical properties and its applicability to complex three-dimensional substrates.

[0027] By adjusting the number of self-assembled layers and studying the surface morphology, mechanical properties, and microbial corrosion resistance of the coating, an optimal spray duration of 800 seconds was determined. Because the precursor solution can be spread well on various pretreated substrates, this facilitates the synthetic assembly of the coating on the substrate surface, allowing the coating to be firmly applied to various substrates such as metal, plastic, and glass.

[0028] Because poly(m-phenylenediamine) wraps the two-dimensional copper-based MOFs sheets, the sudden release of MOFs is avoided, allowing the coating to kill corrosive bacteria for a longer period of time. At the same time, poly(m-phenylenediamine) fills the gaps between the MOFs sheets, effectively preventing the invasion of corrosive media. Under the synergistic effect of the two systems, the coating produces excellent resistance to microbial corrosion.

[0029] The present invention uses a soft spray method to prepare a microbial corrosion-resistant coating. The process achieves uniform spraying and minimal thickness variation across the coating. The process also minimizes spatial effects and environmental pollution, while also providing continuous and convenient operation, paving the way for large-scale coating production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a transmission electron microscope (TEM) image of the CuBDC / PmPD composite coating in Example 1;

[0031] Figure 2 is an X-ray photoelectron spectroscopy (XPS) graph of the CuBDC / PmPD composite coating in Example 2;

[0032] Figure 3 is an X-ray diffraction (XRD) pattern of the sample; wherein, CuBDC / PmPD is the composite coating of Example 2, and CuBDC is the coating of Comparative Example 3;

[0033] Figure 4 1 are scanning electron microscope (SEM) images of the samples; wherein (a) is the CuBDC / PmPD composite coating of Example 2, and (b) is the CuBDC coating of Comparative Example 3;

[0034] Figure 5 are atomic force microscope (AFM) images of the samples; wherein (a) is the CuBDC coating of Comparative Example 4, and (b) is the CuBDC / PmPD composite coating of Example 4;

[0035] Figure 6 3 are photos of the samples in Example 3; (a) is a hemispherical polytetrafluoroethylene substrate, and (b) is a sample after a CuBDC / PmPD composite coating is prepared on the surface of the hemispherical polytetrafluoroethylene substrate;

[0036] Figure 7: is a statistical diagram of pitting corrosion of samples after microbial corrosion; wherein, CuBDC / PmPD is the composite coating of Example 2, 316 stainless steel is the sample treated in Example 2, and CuBDC is the coating of Example 3;

[0037] Figure 8 : are electrochemical impedance spectroscopy data of samples after seven days of microbial corrosion; wherein (a) is an electrochemical Bode plot, and (b) is an electrochemical energy quist plot. In (a) and (b), CuBDC / PmPD is the composite coating of Example 2, 316 stainless steel is the sample treated in Comparative Example 2, and CuBDC is the coating of Comparative Example 3;

[0038] Figure 9 The figures are physical pictures of the sample substrates after microbial corrosion, the corrosion products on the sample surface and the coating are removed; (a) is comparative example 1, (b) is comparative example 4, and (c) is example 4;

[0039] Figure 10 These are colony images obtained from a plate coating test of the sample against Pseudomonas aeruginosa; wherein (a) is Example 2, (b) is Comparative Example 3, and (c) is Comparative Example 2;

[0040] Figure 11 The live-dead staining test images of the samples under a confocal laser scanning microscope (CLSM) are shown; wherein (a) is Example 2, (b) is Comparative Example 3, and (c) is Comparative Example 2;

[0041] Figure 12 These are bacterial morphology images under a scanning electron microscope (SEM) after the sample was co-cultured with Pseudomonas aeruginosa; wherein, (a) is Example 2, (b) is Comparative Example 3, and (c) is Comparative Example 2. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and the effects of the present invention in achieving its intended purpose, the present invention is further described in detail below in conjunction with embodiments to better illustrate the specific implementation methods, structural features and technical effects of the present invention.

[0043] Wherein, the experimental conditions that are not specifically marked are usually performed according to conventional conditions, such as the conditions described in textbooks or experimental guides, or according to the conditions recommended by the manufacturer, and these conditions are conventional and easy to obtain for those of ordinary skill in the art. The above embodiment is described only as a preferred embodiment of the present invention, but does not limit the scope of the present invention. For those skilled in the art, the present invention can be reasonably adjusted, equivalently substituted or optimized and improved on the basis of the principles of the present invention and design ideas mastered by it, and all these changes should be within the scope of protection of the present invention.

[0044] The embodiment of the present invention provides a metal organic framework-polymer composite microbial corrosion resistant coating prepared based on the soft spray method and its preparation method. The soft spray method completes the preparation of the coating through a mild interface engineering effect, which can effectively retain the active ingredients of micro-nano materials and achieve uniform film formation, and is suitable for precision fields such as flexible devices. The copper-based metal organic framework nanosheet stacked growth arrangement has good orientation, which increases the contact area with bacteria or corrosive media, releases copper ions to efficiently destroy microbial films and inhibit corrosion reactions; its dense layered arrangement can form a physical barrier, synergistic with the long-term sustained release ability of copper ions, and significantly improves the antibacterial durability and anti-corrosion and anti-permeation properties. The polymer is formed by oxidative polymerization of meta-phenylenediamine in an interfacial reaction. After being compounded with a metal organic framework, it can effectively prevent particle agglomeration and enhance environmental stability and coating universality.

[0045] In the following examples, the metal cations used are Cu 2+ The ultrasonic nozzle is a Z956 focused ultrasonic nozzle, purchased from Beijing Dongfang Jinrongchao Electrical Appliance Co., Ltd. There are no special requirements for the mixed organic solvents A and B. In the present invention, the mixed organic solvent A dissolves 3g of terephthalic acid and m-phenylenediamine in different proportions per 100mL of the mixed organic solvent; and the mixed organic solvent B dissolves 0.5g of anhydrous copper acetate per 100mL. Unless otherwise specified, all other raw materials and equipment used are commercially available. The present invention is further described below with reference to specific examples and accompanying drawings.

[0046] Example 1

[0047] Step 1: Surface treatment of the 316 stainless steel substrate material: The metal sample was polished with 240 mesh, 400 mesh, 600 mesh, 800 mesh, and 1000 mesh sandpaper in sequence. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 60 minutes. The surface of the substrate to be loaded with the coating was subjected to plasma surface activation treatment with a plasma treatment power of 60 W and a time of 20 seconds to increase the surface energy of the substrate.

[0048] Step 2: Prepare the precursor solution and metal cation solution: Weigh terephthalic acid and m-phenylenediamine in a molar ratio of 1:3 and add them to a mixed solvent A of N,N-dimethylformamide and acetonitrile in a volume ratio of 8:1. After magnetic stirring for 60 minutes, ultrasonicate for 20 minutes to form a uniform precursor solution.

[0049] Weigh anhydrous copper acetate at a molar ratio of 1:1 to terephthalic acid. Dissolve the solution in a mixed organic solvent (B) of N,N-dimethylformamide and acetonitrile at a volume ratio of 1:16. Ultrasonicate for 20 minutes to form a uniform metal cation solution.

[0050] Step 3: Infiltrate the substrate surface with the precursor solution: Place the substrate material treated in step 1 in a glass culture dish of appropriate size, use a dropper to absorb the precursor solution, and evenly apply it to the surface of the substrate material to ensure that the solution is fully spread on the surface of the material.

[0051] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as the spray solution. The spray solution is atomized into fine droplets under ultrasonic dispersion. Ultrasonic spraying is performed at a power load of 2W, and the atomized droplets are ejected from the ultrasonic nozzle. The amount of metal cation solution injected into the spray device each time is 1mL, the metal cation solution flow rate is 125μL / s (with interruptions every 8 seconds), and the total spraying time is 200 seconds. After the atomized droplets contact the precursor solution on the substrate surface, the metal-organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can proceed simultaneously.

[0052] The excess solution in the glass culture dish was sucked dry with a medical 1 mL syringe and allowed to stand for 2 h in an ambient relative humidity of 40%. After the coating was naturally cured, a metal organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD was formed on the surface of the substrate.

[0053] from Figure 1 It can be seen that the sheet structure of MOFs is clearly visible, and different composite elements are randomly dispersed in the MOFs sheets, with neither obvious element separation nor phase separation.

[0054] Example 2

[0055] Step 1: Surface treatment of the 316 stainless steel carbon steel substrate material: The metal sample was polished with 240 mesh, 400 mesh, 600 mesh, 800 mesh, and 1000 mesh sandpaper in sequence. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 90 minutes. The surface of the substrate to be loaded with the coating was subjected to plasma surface activation treatment with a plasma treatment power of 220 W and a time of 130 seconds to increase the surface energy of the substrate.

[0056] Step 2: Prepare the precursor solution and metal cation solution: Weigh terephthalic acid and m-phenylenediamine in a molar ratio of 1:12 and add them to a mixed solvent A of N,N-dimethylformamide and acetonitrile in a volume ratio of 6:1. After magnetic stirring for 120 minutes, a uniform precursor solution is formed over 80 minutes.

[0057] Weigh anhydrous copper acetate at a molar ratio of 2:1 to terephthalic acid. Dissolve in a mixed organic solvent (B) of N,N-dimethylformamide and acetonitrile at a volume ratio of 1:6. Ultrasonicate for 80 minutes to form a uniform metal cation solution.

[0058] Step 3: Infiltrate the substrate surface with the precursor solution: Place the substrate material treated in step 1 in a glass culture dish of appropriate size, use a dropper to absorb the precursor solution, and evenly apply it to the surface of the substrate material to ensure that the solution is fully spread on the surface of the material.

[0059] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as the spray solution. The spray solution is atomized into fine droplets under ultrasonic dispersion. Ultrasonic spraying is performed at a power load of 2.6W, and the atomized droplets are ejected from the ultrasonic nozzle. The amount of metal cation solution injected into the spray device each time is 1mL, the metal cation solution flow rate is 145μL / s (with interruptions every 6.9 seconds), and the total spraying time is 600 seconds. After the atomized droplets contact the precursor solution on the substrate surface, the metal-organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can proceed simultaneously.

[0060] The excess solution in the glass culture dish was sucked dry with a medical 1 mL syringe and allowed to stand for 4 h under an ambient relative humidity of 45%. After the coating was naturally cured, a metal organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD was formed on the surface of the substrate.

[0061] from Figure 2 It can be analyzed that the elemental composition of the prepared composite coating is C, N, O and Cu elements. Figure 3 Three peaks were observed at 10°, 17°, and 20° in the CuBDC / PmPD composite coating, corresponding to the standard PDF card of CuBDC, proving the presence of CuBDC in the composite coating. Figure 4 (a) The obvious stacking structure of two-dimensional MOFs sheets can be seen, and the structure of MOFs is sheet-like and Figure 1 The TEM results correspond to those of Figure 4 (a) and Figure 4 (b) By comparison, it can be seen that after the formation of poly(m-phenylenediamine) in Example 2, the microscopic surface of the coating becomes smooth and uniform, which indicates that the poly(m-phenylenediamine) fully fills the gaps between the MOFs nanosheets and the coating surface becomes denser.

[0062] Example 3

[0063] Step 1: Surface treatment of the plastic substrate material: prepare a commercially available hemispherical polytetrafluoroethylene mold substrate, and subject the substrate surface to be loaded with the coating to plasma surface activation treatment at a power of 160 W for 70 seconds to enhance the substrate surface energy.

[0064] Step 2: Prepare the precursor solution and metal cation solution: Weigh terephthalic acid and m-phenylenediamine in a molar ratio of 1:8 and add them to a mixed solvent A of N,N-dimethylformamide and acetonitrile in a volume ratio of 7:1. After magnetic stirring for 90 minutes, ultrasonication is carried out for 50 minutes to form a uniform precursor solution.

[0065] Weigh anhydrous copper acetate at a molar ratio of 3:1 to terephthalic acid. Dissolve the solution in a mixed organic solvent (B) of N,N-dimethylformamide and acetonitrile at a volume ratio of 1:11. Ultrasonicate for 50 minutes to form a uniform metal cation solution.

[0066] Step 3: Infiltrate the substrate surface with the precursor solution: Place the substrate material treated in step 1 in a glass culture dish of appropriate size, use a dropper to absorb the precursor solution, and evenly apply it to the surface of the substrate material to ensure that the solution is fully spread on the surface of the material.

[0067] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as the spray solution. The spray solution is atomized into fine droplets under ultrasonic dispersion. Ultrasonic spraying is performed at a power load of 2.3W, and the atomized droplets are ejected from the ultrasonic nozzle. The amount of metal cation solution injected into the spray device each time is 1mL, the metal cation solution flow rate is 170μL / s (with interruptions every 5.9 seconds), and the total spraying time is 400 seconds. After the atomized droplets contact the precursor solution on the substrate surface, the metal-organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can proceed simultaneously.

[0068] The excess solution in the glass culture dish was sucked dry with a medical 1 mL syringe and allowed to stand for 3 hours under an ambient relative humidity of 50%. After the coating was naturally cured, a metal organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD was formed on the surface of the substrate.

[0069] Figure 6 (a) and Figure 6 (b) As can be seen, the CuBDC / PmPD composite coating completely covers the hemispherical PTFE substrate without any peeling or cracking. This is due to the interaction between the poly(m-phenylenediamine) molecular chains, which enhances the coating's resistance to external deformation and significantly increases its toughness. This demonstrates the potential of the coating prepared in this invention for coating substrates with complex three-dimensional shapes.

[0070] Example 4

[0071] Step 1: Surface treatment of the X80 carbon steel substrate material: The metal sample was surface-polished with 240-mesh, 400-mesh, 600-mesh, 800-mesh, and 1000-mesh sandpaper. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 120 min. The surface of the substrate to be coated was subjected to plasma surface activation treatment with a plasma treatment power of 310 W and a time of 180 s to increase the surface energy of the substrate.

[0072] Step 2: Prepare the precursor solution and metal cation solution: weigh terephthalic acid and m-phenylenediamine at a molar ratio of 1:15 and add them to a mixed solvent A of N,N-dimethylformamide and acetonitrile with a volume ratio of 8:1. After magnetic stirring for 150 minutes, ultrasonication for 100 minutes is performed to form a uniform precursor solution.

[0073] Weigh anhydrous copper acetate at a molar ratio of 1:1 to terephthalic acid. Dissolve the solution in a 1:1 volume ratio of N,N-dimethylformamide to acetonitrile (solvent B). Ultrasonicate for 100 minutes to form a uniform metal cation solution.

[0074] Step 3: Infiltrate the substrate surface with the precursor solution: Place the substrate material treated in step 1 in a glass culture dish of appropriate size, use a dropper to absorb the precursor solution, and evenly apply it to the surface of the substrate material to ensure that the solution is fully spread on the surface of the material.

[0075] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as the spray solution. The spray solution is atomized into fine droplets under ultrasonic dispersion. Ultrasonic spraying is performed at a power load of 3W, and the atomized droplets are ejected from the ultrasonic nozzle. The amount of metal cation solution injected into the spray device each time is 1mL, the metal cation solution flow rate is 200μL / s (with interruptions every 5 seconds), and the total spraying time is 800 seconds. After the atomized droplets contact the precursor solution on the substrate surface, the metal-organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can be carried out simultaneously.

[0076] The excess solution in the glass culture dish was absorbed with a medical 1 mL syringe and allowed to stand for 4 h under ambient conditions of 50% relative humidity and 30°C. After the coating was naturally cured, a metal organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD was formed on the surface of the substrate.

[0077] compared to Figure 5 (a) The CuBDC coating surface of Comparative Example 4 has a micron-scale undulating structure. Figure 5The surface undulations of the CuBDC / PmPD composite coating in (b) remain at the nanometer level, and the surface of the composite coating prepared in Example 4 is flatter and more uniform. This is because the filling of poly(m-phenylenediamine) has a wrapping effect on the MOFs. The poly(m-phenylenediamine) covers the stacked MOFs layers, reducing the RMS roughness of the coating.

[0078] Comparative Example 1

[0079] This comparative example does not include steps 2 to 4.

[0080] Step 1: Surface treatment of the X80 carbon steel substrate material: The metal sample was surface-polished with 240-mesh, 400-mesh, 600-mesh, 800-mesh, and 1000-mesh sandpaper. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 10 minutes. The surface of the substrate to be loaded with the coating was subjected to plasma surface activation treatment with a plasma treatment power of 50 W and a time of 20 seconds to increase the surface energy of the substrate.

[0081] Comparative Example 2

[0082] This comparative example does not include steps 2 to 4.

[0083] Step 1: Surface treatment of the 316 stainless steel substrate material: The metal sample was surface-polished with 240-mesh, 400-mesh, 600-mesh, 800-mesh, and 1000-mesh sandpaper. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 10 minutes. The surface of the substrate to be loaded with the coating was subjected to plasma surface activation treatment with a plasma treatment power of 50 W for 20 seconds to increase the surface energy of the substrate.

[0084] Comparative Example 3

[0085] Step 1: Surface treatment of the 316 stainless steel substrate material: The metal sample was surface-polished with 240-mesh, 400-mesh, 600-mesh, 800-mesh, and 1000-mesh sandpaper. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 10 minutes. The surface of the substrate to be loaded with the coating was subjected to plasma surface activation treatment with a plasma treatment power of 50 W for 20 seconds to increase the surface energy of the substrate.

[0086] Step 2: Prepare the precursor solution and metal cation solution: Weigh terephthalic acid and add it to a mixed solvent A of N,N-dimethylformamide and acetonitrile in a volume ratio of 6:1. Both are analytically pure. After magnetic stirring for 10 minutes, ultrasonication is performed for 10 minutes to form a uniform precursor solution.

[0087] Anhydrous copper acetate was weighed at a molar ratio of 2:1 to terephthalic acid. The solution was dissolved in a mixed organic solvent B of N,N-dimethylformamide and acetonitrile at a volume ratio of 1:8. The mixture was sonicated for 10 minutes to form a uniform metal cation solution.

[0088] Step 3: Infiltrate the substrate surface with the precursor solution: Place the substrate material treated in step 1 in a glass culture dish of appropriate size, use a dropper to absorb the precursor solution, and evenly apply it to the surface of the substrate material to ensure that the solution is fully spread on the surface of the material.

[0089] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as the spray solution. The spray solution is atomized into fine droplets under ultrasonic dispersion. Ultrasonic spraying is performed at a power load of 0.6W, and the atomized droplets are ejected from the ultrasonic nozzle. The amount of metal cation solution injected into the spray device each time is 0.8mL, the metal cation solution flow rate is 40μL / s (with interruptions every 20 seconds), and the total spraying time is 400 seconds. After the atomized droplets contact the precursor solution on the substrate surface, the metal-organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can proceed simultaneously.

[0090] The excess solution in the glass culture dish was sucked dry with a 1 mL medical syringe, and the solution was left to stand for 4 hours under an ambient relative humidity of 40%. After the coating was naturally cured, a CuBDC coating was formed on the substrate surface. The X-ray diffraction (XRD) results are shown in Figure 2. Figure 3 As shown in the scanning electron microscope (SEM) photos Figure 4 (b)

[0091] Comparative Example 4

[0092] Step 1: Surface treatment of the X80 carbon steel substrate material: The metal sample was surface-polished with 240-mesh, 400-mesh, 600-mesh, 800-mesh, and 1000-mesh sandpaper. The polished metal sample was ultrasonically cleaned in a mixed solution of ethanol and acetone for 10 minutes. The surface of the substrate to be loaded with the coating was subjected to plasma surface activation treatment with a plasma treatment power of 50 W and a time of 20 seconds to increase the surface energy of the substrate.

[0093] Step 2: Prepare the precursor solution and metal cation solution: Weigh terephthalic acid and add it to a mixed solvent A of N,N-dimethylformamide and acetonitrile in a volume ratio of 6:1. Both are analytically pure. After magnetic stirring for 10 minutes, perform ultrasonication for 10 minutes to form a uniform precursor solution.

[0094] Anhydrous copper acetate was weighed at a molar ratio of 4:1 to terephthalic acid. The solution was dissolved in a mixed organic solvent B of N,N-dimethylformamide and acetonitrile at a volume ratio of 1:8. The mixture was sonicated for 10 minutes to form a uniform metal cation solution.

[0095] Step 3: Infiltrate the substrate surface with the precursor solution: Place the substrate material treated in step 1 in a glass culture dish of appropriate size, use a dropper to absorb the precursor solution, and evenly apply it to the surface of the substrate material to ensure that the solution is fully spread on the surface of the material.

[0096] Step 4: Soft spray treatment: The metal cation solution is injected into a spray device as the spray solution. The spray solution is atomized into fine droplets under ultrasonic dispersion. Ultrasonic spraying is performed at a power load of 0.6W, and the atomized droplets are ejected from the ultrasonic nozzle. The amount of metal cation solution injected into the spray device each time is 0.8mL, the metal cation solution flow rate is 40μL / s (with interruptions every 20 seconds), and the total spraying time is 400 seconds. After the atomized droplets contact the precursor solution on the substrate surface, the metal-organic framework assembly and the oxidative polymerization of the polymer (polymer monomer) can proceed simultaneously.

[0097] The excess solution in the glass culture dish was sucked out with a medical 1mL syringe, and the solution was left to stand for 4 hours under the condition of 50% relative humidity. After the coating was naturally cured, a CuBDC coating was formed on the substrate surface. Figure 5 (a) shown.

[0098] The samples in the examples and comparative examples were subjected to the following tests: (1) pitting test, (2) electrochemical impedance spectroscopy test, (3) material surface corrosion test, and (4) antibacterial ability test to verify the microbial corrosion protection effect of the composite coating on the metal substrate material.

[0099] The composition and content of the simulated seawater used in the test are as follows: 23.476 g / L NaCl, 0.664 g / L KCl, 3.917 g / L Na2SO4, 0.096 g / L KBr, 0.026 g / L H3BO3, 0.192 g / L NaHCO3, 0.04 g / L SrCl2·6H2O, 1.848 g / L CaCl2, and 4.975 g / L MgCl2.

[0100] The composition and content of 2216E liquid medium used in the test are as follows: 19.45 g / L NaCl, 5.98 g / L MgCl2, 3.24 g / L Na2SO4, 1.8 g / L CaCl2, 0.55 g / L KCl, 0.16 g / L Na2CO3, 0.08 g / L KBr, 0.034 g / L SrCl2, 0.08 g / L SrBr2, 0.022 g / L H3BO3, 0.004 g / L NaSiO3, 0.0024 g / L NaF, 0.0016 g / L NH4NO3, 0.008 g / L NaH2PO4, 5.0 g / L peptone, 1.0 g / L yeast extract, and 0.1 g / L ferric citrate.

[0101] The CuBDC / PmPD composite coating prepared by the present invention can protect the substrate against microbial corrosion caused by Gram-negative bacteria represented by Pseudomonas aeruginosa. The antibacterial performance test is conducted using Pseudomonas aeruginosa as an example. Pseudomonas aeruginosa, P. aeruginosa ), accession number MCCC1A00099, purchased from the China Marine Microbial Culture Collection. Single colonies were isolated by streak plate method and cultured in 2216E liquid medium at 37°C and 180 rpm for 12–16 hours until the logarithmic growth phase was reached. Culture fluid from the logarithmic growth phase was used for subsequent experiments.

[0102] (1) Pitting test is as follows:

[0103] The sample prepared with CuBDC / PmPD composite coating in Example 2, the 316 stainless steel sample treated in Comparative Example 2, and the sample prepared with CuBDC coating in Comparative Example 3 were immersed in the water for OD 600 = 0.1 in simulated seawater containing Pseudomonas aeruginosa, and after immersing in a 37°C constant temperature incubator for 14 days, the pitting data on the surface of each sample were statistically analyzed. Figure 7 The figure shows pitting data from different sampling points and the statistically derived confidence intervals for the corrosion trend. Both the pitting data and the confidence intervals indicate that the depth and width of the pitting pits of the metal samples protected by the coating in Example 2 and Comparative Example 3 are reduced compared to Comparative Example 2, significantly weakening the corrosion trend. The CuBDC / PmPD composite coating exhibits the best resistance to microbial corrosion, indicating that the formation of poly(m-phenylenediamine) effectively resists the invasion of corrosive media.

[0104] (2) Electrochemical impedance spectroscopy is as follows:

[0105] The sample with CuBDC / PmPD composite coating prepared in Example 2, the 316 stainless steel sample treated in Comparative Example 2, and the sample with CuBDC coating prepared in Comparative Example 3 were cold mounted as electrodes. The electrodes were immersed in a solution with a bacterial activity of OD 600 = 0.1 in a simulated seawater environment of Pseudomonas aeruginosa, and then immersed in the water at room temperature for seven days for electrochemical testing. The electrochemical impedance spectrum obtained is as follows Figure 8 As shown, Figure 8 (a) is the electrochemical Bode diagram. The results show that the impedance value of the CuBDC / PmPD composite coating is increased by one order of magnitude compared with the bare 316 stainless steel sample; Figure 8 (b) is the electrochemical energy Quest diagram, the results show that the impedance value of bare 316 stainless steel is only 1×10 4 Ω, the impedance value of the composite coating in Example 2 is 9×10 4 Ω, the impedance value has been significantly improved, which shows that the CuBDC / PmPD composite coating greatly improves the microbial corrosion resistance of the substrate.

[0106] (3) The surface corrosion of the material is tested as follows:

[0107] The sample with CuBDC / PmPD composite coating prepared in Example 4, the X80 carbon steel sample treated in Comparative Example 1, and the sample with CuBDC coating prepared in Comparative Example 4 were placed in a 600 = 0.1 in a simulated seawater environment with Pseudomonas aeruginosa, the corrosion products and coatings on the sample surfaces were removed in batches on the 1st and 7th days, and the surface morphology of each sample substrate was observed. Figure 9 (a) Figure 9 (b) and Figure 9 (c) It can be seen that the substrate surface of Example 4 has no corrosion phenomenon and the surface still has a metallic luster, indicating that the CuBDC / PmPD composite coating has the best protective effect on the metal sample.

[0108] (4) Antibacterial ability test is as follows:

[0109] All samples used in the antimicrobial assay were sterilized by UV irradiation for 30 min before use.

[0110] The sample with CuBDC / PmPD composite coating prepared in Example 2, the 316 stainless steel sample treated in Comparative Example 2, and the sample with CuBDC coating prepared in Comparative Example 3 were immersed in 2216E liquid culture medium containing an initial bacterial activity of OD 600 =0.05 Pseudomonas aeruginosa. Co-culture at 37°C for 1 day. After incubation, gently wash the surface of each sample with sterile water to remove weakly adhering planktonic bacteria. The treated samples were subjected to the following tests:

[0111] (4-1) Plate coating test: The samples were vortexed in a centrifuge tube containing 2216E liquid culture medium to collect bacteria tightly attached to the surface of each sample. The antibacterial properties of the samples were evaluated by dilution plate coating method. Figure 10 As shown: Example 2 Figure 10 (a), Comparative Example 2 Figure 10 (c) shows that Comparative Example 3 is as follows Figure 10 (b)

[0112] (4-2) Live / dead staining test: The activity of bacteria was assessed using the LIVE / DEAD BacLight bacterial viability kit. The bacteria on the sample surface were stained with SYTO9 and PI dyes for 20 minutes in the dark and then stained with E x / E m =488 / 559nm CLSM was used for visualization. Figure 11 As shown: Example 2 Figure 11 (a), Comparative Example 2 Figure 11 (c) shows that Comparative Example 3 is as follows Figure 11 (b)

[0113] (4-3) Visualization test of bacteria on the surface of the material: The bacteria on the surface of the material were fixed with glutaraldehyde and then freeze-dried in a freeze dryer for 24 hours for dehydration. The results were observed under a scanning electron microscope (SEM). Figure 12 As shown: Example 2 Figure 12 (a), Comparative Example 2 Figure 12 (c) shows that Comparative Example 3 is as follows Figure 12 (b)

[0114] From the above tests, it can be seen that the CuBDC / PmPD composite coating exhibits extremely high antibacterial ability, indicating that the CuBDC two-dimensional MOFs sheets in the composite coating release 2+ It has a good killing effect on bacteria and plays a positive role in resisting microbial corrosion.

[0115] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying, characterized in that: Includes the following: Step 1: Surface treatment of the substrate material: After substrate pretreatment, the surface of the substrate to be coated is subjected to plasma surface activation treatment to increase the surface energy of the substrate; Step 2: preparing a precursor solution and a metal cation solution: preparing a precursor solution with terephthalic acid and m-phenylenediamine, wherein the molar ratio of terephthalic acid to m-phenylenediamine is 1:3 to 1:15; preparing a metal cation solution with anhydrous copper acetate, wherein the molar ratio of terephthalic acid to anhydrous copper acetate is 1:1 to 1:4; Step 3: Infiltrating the substrate surface with the precursor solution: coating the precursor solution on the surface of the substrate material treated in step 1; Step 4: soft spray treatment: injecting a metal cation solution as a spray solution into a spray device, wherein the nozzle of the spray device has an ultrasonic function, and the spray solution is ultrasonically sprayed through the nozzle to form atomized droplets; 1 mL of the metal cation solution is injected into the spray device each time, the flow rate of the metal cation solution is 125 μL / s~200 μL / s, and the total ultrasonic spray time is 200s~800s; after the atomized droplets contact the precursor solution on the surface of the substrate, the metal organic framework is assembled and the polymer is polymerized simultaneously; the metal organic framework is allowed to stand for 2h~5h in an environment with a humidity of 40%~50%, and after curing, a metal organic framework-polymer composite microbial corrosion-resistant coating CuBDC / PmPD is formed on the surface of the substrate; The polymer encapsulates the copper-based metal organic framework and fully fills the gaps of the copper-based metal organic framework to obtain a smooth and dense CuBDC / PmPD coating, which prevents the corrosive medium from invading the substrate and enables the substrate to resist seawater corrosion and microbial corrosion in the seawater environment.

2. The method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying according to claim 1, characterized in that: In step 1: the pretreatment refers to ultrasonic cleaning of the substrate in a mixed solution of ethanol and acetone for 60 minutes to 120 minutes; the power of the plasma surface activation treatment is 60W to 310W, and the time is 20 seconds to 180 seconds.

3. The method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying according to claim 1, characterized in that: The substrate in step 1 includes metal, plastic, and glass.

4. The method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying according to claim 3, characterized in that: In step 1, when the substrate is metal, it is first polished with sandpaper with mesh sizes of 240 mesh, 400 mesh, 600 mesh, 800 mesh, and 1000 mesh, and then ultrasonically cleaned in a mixed solution of ethanol and acetone for 60 min to 120 min.

5. The method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying according to claim 1, characterized in that: In step 2: Terephthalic acid, m-phenylenediamine, N,N-dimethylformamide and acetonitrile are prepared into a precursor solution, wherein the volume ratio of N,N-dimethylformamide to acetonitrile is 8:1 to 5:1; Anhydrous copper acetate, N,N-dimethylformamide and acetonitrile are prepared into a metal cation solution, wherein the volume ratio of N,N-dimethylformamide to acetonitrile is 1:16 to 1:

1.

6. The method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying according to claim 1, characterized in that: In step 2: the precursor solution is first magnetically stirred for 60 min to 150 min, and then ultrasonically dispersed for 20 min to 100 min to mix the solution evenly; The metal cation solution is ultrasonically dispersed for 20 minutes to 100 minutes to ensure uniform mixing of the solution.

7. The method for preparing a metal organic framework-polymer composite corrosion resistant coating based on soft spraying according to claim 1, characterized in that: In step 4: the ultrasonic spray power is 2W~3W, and the nozzle shaking amplitude is 60°~90°.

8. The metal organic framework-polymer composite corrosion resistant coating obtained by the method according to any one of claims 1 to 7, characterized in that: The metal organic framework is a copper-based metal organic framework composed of anhydrous copper acetate and terephthalic acid, and is arranged in a stacked growth manner; the polymer is poly-m-phenylenediamine formed by the polymerization of m-phenylenediamine induced by copper ions; the polymer coats the copper-based metal organic framework and fills the gaps in the copper-based metal organic framework.

9. The use of the corrosion-resistant coating according to claim 8, characterized in that: The corrosion-resistant coating can enable the substrate to resist microbial corrosion caused by Gram-negative bacteria in a seawater environment.

Images