Preparation method of pH response type intelligent marine anti-corrosion and anti-fouling paint based on polyhedral oligomeric silsesquioxane

Abstract

The invention discloses a preparation method of a pH response type intelligent marine anti-corrosion and anti-fouling coating based on polyhedral oligomeric silsesquioxane. The method comprises the following steps: reacting NH2-POSS with an acrylic monomer to obtain a POSS-PAA slow-release material; then, the POSS-PAA sustained-release material and DCOIT are subjected to a reaction, and a POSS-PAA sustained-release material loaded with the antifouling agent is obtained; polymerizing epoxy resin E-51 and an acrylic monomer to obtain an epoxy acrylic copolymer; finally, fully mixing the POSS-PAA sustained-release material loaded with the antifouling agent, an epoxy acrylic copolymer, a flatting agent, a defoaming agent and a solvent to obtain a target product. The anti-fouling agent has the outstanding advantages of long anti-fouling time, controllable release, intelligent response and the like, and the use efficiency of the anti-fouling agent is improved.

Description

Technical Field

[0001] This invention relates to a method for preparing a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane. Background Technology

[0002] Various marine engineering equipment and vessels inevitably encounter the problem of marine biofouling in the marine environment. The attachment of marine organisms not only increases the roughness of the hull surface but also reduces vessel speed and maneuverability, and increases fuel consumption. Marine fouling organisms on the hull often accelerate the electrochemical corrosion of metals, reduce the strength and safety of the hull steel structure, shorten dry-docking intervals, increase the return-to-dock rate, and thus affect the service life of the vessel, significantly increasing maintenance costs. Applying marine anti-corrosion and antifouling coatings is the most economical and effective way to solve these problems.

[0003] Traditional antifouling coatings maintain the same antifouling agent release rate throughout the peak and off-peak seasons for marine organisms. This results in insufficient release during peak growth periods to prevent fouling organism adhesion, or waste of antifouling agents during off-peak seasons. In recent years, smart-responsive antifouling coatings have become a research hotspot. These coatings can intelligently regulate antifouling agent release behavior based on changes in environmental stimuli. Among them, pH-responsive coatings utilize acidic substances produced by marine microbial metabolism as trigger signals to achieve on-demand release of antifouling agents. CN114958131A discloses an antifouling coating that is responsive to both seawater temperature and pH. This coating can intelligently control the release of antifouling agents based on changes in seawater temperature and pH, reducing the amount of antifouling agent used. The coating slows resin hydrolysis and antifouling agent leaching at temperatures <12℃ and pH <6, and accelerates antifouling agent release at temperatures >32℃ and pH >8, which is the opposite of the pH decrease characteristic when fouling organisms such as bacteria attach. During the peak growth period of fouling organisms, the pH of the adhesion area is generally weakly acidic. The properties of this coating actually inhibit the leaching of the antifouling agent, failing to achieve the effect of preventing fouling organism adhesion. Wei Enyang of Hainan University prepared a smart (pH-responsive) microcapsule and marine antifouling coating. The capsules used chitosan quaternary ammonium salt and sodium alginate as wall materials, encapsulating the environmentally friendly antifouling agent DCOIT, with zinc acrylate resin as the matrix. In a 100-day real-sea antifouling test, it exhibited excellent antifouling properties. However, with the increase of the smart microcapsule content, the adhesion of this smart-responsive coating gradually decreased.

[0004] POSS, with its nanoscale rigid inorganic core and functionalizable organic peripheral groups, can significantly improve the mechanical properties, thermal stability, and chemical stability of polymer materials. Introducing POSS into antifouling coatings can simultaneously enhance both the mechanical and functional properties of the coating; however, research on POSS-based pH-responsive antifouling coatings has not yet been reported.

[0005] Therefore, developing a pH-responsive smart marine antifouling and anticorrosive coating based on POSS can achieve intelligent and controllable release of antifouling agents, while also possessing excellent mechanical properties and durability, which has significant scientific and practical application value. Summary of the Invention

[0006] The present invention aims to propose a method for preparing a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxanes to solve the problems of low adhesion and chaotic pH response range of current smart responsive antifouling coatings.

[0007] The present invention provides a method for preparing a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxanes, comprising the following steps: (1) Under the catalysis of N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP), octaaminopropyl cage-type half-siloxane (NH2-POSS) and acrylic acid monomer (AA) are fully reacted under liquid phase conditions; after the reaction is completed, the reaction liquid is poured into diethyl ether for full precipitation, the precipitate is separated and washed, and the washed precipitate is dried to obtain the product, namely POSS-PAA sustained-release material; (2) Disperse the POSS-PAA sustained-release material in a dispersion solvent, then add an environmentally friendly antifouling agent, stir the reaction thoroughly, and then remove the dispersion solvent to obtain the product, namely the POSS-PAA sustained-release material loaded with antifouling agent; the amount of dispersion solvent is generally 45-55 times the mass of the POSS-PAA sustained-release material. (3) The epoxy resin E-51 and the acrylic monomer are polymerized to obtain the product, namely epoxy acrylic copolymer. (4) After fully mixing the POSS-PAA slow-release material loaded with antifouling agent, epoxy acrylic copolymer, leveling agent, defoamer and solvent, a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-type silsesquioxane is obtained; the full mixing is carried out by high-speed dispersion at a speed of 300~1200 rpm.

[0008] The specific synthesis steps of the POSS-PAA sustained-release material are as follows: NH2-POSS was dissolved in N,N-dimethylformamide (DMF), and N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) were added. The mixture was then stirred and activated. After activation, acrylic acid monomer was added dropwise under nitrogen protection to react with NH2-POSS. After the addition was complete, the reaction continued under nitrogen protection. After the reaction was completed, the reaction solution was poured into diethyl ether for thorough precipitation. After precipitation, the precipitate was separated and washed. The washed precipitate was dried to obtain the POSS-PAA sustained-release material. Washing was generally performed three times with ethanol, and drying was carried out under vacuum at a temperature of 35-45℃ and a vacuum degree of 10-15 kPa for 3-6 hours. The mass ratio of NH2-POSS, N,N-dimethylformamide, N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) is 3-8:36-60:0.5-3:0.01-0.5; the mass ratio of NH2-POSS, acrylic acid monomer and diethyl ether is 3-8:15-35:85-145.

[0009] The stirring activation temperature is 25℃ and the time is 1-3 hours; the temperature for adding acrylic monomer is 20-60℃ and the time is 3-6 hours; after the acrylic monomer is added, the reaction with NH2-POSS continues at a temperature of 20-60℃ for 18-36 hours.

[0010] In step (2), the dispersing solvent is methanol, ethanol, or butanol; the environmentally friendly antifouling agent is 4,5-dichloro-N-octyl-4-isothiazolin-3-one (DCOIT); the amount of DCOIT added is 3-8 times the mass of the POSS-PAA sustained-release material. The reaction temperature is 20-35℃ and the time is 8-16 hours with thorough stirring.

[0011] The specific synthesis steps of the epoxy acrylate copolymer are as follows: Epoxy resin E-51 is mixed with acrylic monomer (AA), and triphenylphosphine catalyst is added to react epoxy resin E-51 and acrylic monomer at a temperature of 75-85℃ for 2-5 hours. After the reaction is completed, epoxy acrylic copolymer is obtained.

[0012] The mass ratio of epoxy resin E-51, acrylic monomer and triphenylphosphine is 2-6:0.5-2:0.01-0.2.

[0013] In step (4), the mass ratio of the product-loaded antifouling agent POSS-PAA slow-release material, epoxy acrylic copolymer, leveling agent, defoamer and solvent is: 10-40: 30-40: 0.01-0.8: 0.01-0.8: 10-30.

[0014] The leveling agent is BYK333 leveling agent, the defoamer is BYK1790 defoamer, and the solvent is ethyl acetate.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The antifouling agent is released on demand via a pH-responsive mechanism. At the normal seawater pH of 8.1, the carboxyl groups in the PAA segments of the POSS-PAA slow-release material are in a deprotonated state, resulting in extended molecular chains and strong hydrophilicity, effectively encapsulating the antifouling agent and leading to a slow release rate. When microorganisms attach and produce acidic metabolites, the local pH decreases, causing the carboxyl groups to protonate, the molecular chains to contract, and the hydrophobicity to increase. This accelerates the release of the antifouling agent, preventing early over-release and late-stage failure, thus improving the efficiency of the antifouling agent.

[0016] 2. The slow-release function of the NH2-POSS nanocarrier and the protective effect of the resin matrix significantly extend the antifouling time. At the same time, the rigid inorganic skeleton of POSS significantly improves the hardness, wear resistance and adhesion of the coating.

[0017] 3. The barrier effect of NH2-POSS nanoparticles effectively inhibits the penetration of corrosive media. At the same time, the PAA segments grafted to the ends of NH2-POSS can form a protective film by combining with the surface of the metal substrate, reducing the contact between the metal and dissolved oxygen and other corrosive substances in the water, and synergistically improving the corrosion resistance and durability of the coating.

[0018] 4. NH2-POSS grafted PAA segments, as synergists for bactericides and antifouling agents, can significantly enhance the antifouling effect of DCOIT and improve the antifouling effect of the antifouling coating. Attached Figure Description

[0019] Figure 1 This is a diagram of the antibacterial experiment in Example 1; Figure 2 This is a diagram of the antibacterial experiment in Example 2; Figure 3 This is a diagram of the antibacterial experiment in Example 3; Figure 4 This is a diagram of the antibacterial experiment in Example 4; Figure 5 This is a diagram of the antibacterial experiment in Example 5; Figure 6 This is a diagram of the antibacterial test for the control sample. Detailed Implementation

[0020] The feasibility of the technical solution of the present invention is illustrated by the following examples, but the scope of protection of the present invention should not be limited to the specific examples below. Example 1

[0021] (1) Add 3g of NH2-POSS to a 100 mL four-necked flask, then add 36g of DMF to dissolve NH2-POSS, and add 0.5g of DCC and 0.01g of DMAP. Activate the solution by magnetic stirring at 25°C for 2 hours. Under nitrogen protection and at 25°C, add 15g of AA dropwise to the activated NH2-POSS solution for 3 hours. After the addition is complete, continue to react under nitrogen protection and at 25°C for 24 hours. After the reaction is complete, pour the reaction solution into 85g of diethyl ether for precipitation. After precipitation, centrifuge to collect the product. Wash the product three times with ethanol. After washing, vacuum dry at 40°C and 15kPa for 5 hours to obtain POSS-PAA sustained-release material. (2) Place 2g of POSS-PAA sustained-release material into a 200 mL four-necked flask, add 90g of anhydrous ethanol for dispersion, then add 6g of DCOIT, stir at 25℃ for 12 hours to obtain POSS-PAA sustained-release material loaded with antifouling agent DCOIT. (3) 2g of epoxy resin E-51 and 0.5g of AA were placed in a four-necked flask and mixed by mechanical stirring. 0.01g of triphenylphosphine catalyst was added and reacted at 80°C for 3 hours to obtain epoxy acrylic copolymer.

[0022] (4) 10g of POSS-PAA slow-release material loaded with antifouling agent DCOIT, 40g of epoxy acrylic copolymer, 0.25g of defoamer BYK1790, 0.25g of leveling agent BYK333 and 10g of ethyl acetate were mixed evenly at a speed of 800rpm. After mixing for 40 minutes, a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-type silsesquioxane was obtained. Example 2

[0023] The operation steps are the same as in Example 1, except that: the amount of NH2-POSS added is 4.3g, the amount of AA added is 20g, the amount of POSS-PAA slow-release material added is 2.4g, the amount of POSS-PAA slow-release material loaded with antifouling agent DCOIT added is 18g, and the amount of epoxy acrylic copolymer added is 38g. Example 3

[0024] The operation steps are the same as in Example 1, except that: the amount of NH2-POSS added is 5.6g, the amount of AA added is 25g, the amount of POSS-PAA slow-release material added is 3.6g, the amount of POSS-PAA slow-release material loaded with antifouling agent DCOIT added is 26g, and the amount of epoxy acrylic copolymer added is 36g. Example 4

[0025] The operation steps are the same as in Example 1, except that: the amount of NH2-POSS added is 6.8g, the amount of AA added is 30g, the amount of POSS-PAA slow-release material added is 4.8g, the amount of POSS-PAA slow-release material loaded with antifouling agent DCOIT added is 34g, and the amount of epoxy acrylic copolymer added is 34g. Example 5

[0026] The operation steps are the same as in Example 1, except that: the amount of NH2-POSS added is 8.0g, the amount of AA added is 35g, the amount of POSS-PAA slow-release material added is 6g, the amount of POSS-PAA slow-release material loaded with antifouling agent DCOIT added is 40g, and the amount of epoxy acrylic copolymer added is 32g.

[0027] The above embodiments are merely illustrative examples of the feasibility of implementing the invention, using specific values ​​selected from the ranges of mass parameters, temperature parameters, etc., in the claims. They are not intended to limit the scope of protection of the invention. Any value selected from the ranges of mass parameters, temperature parameters, etc., in the claims can be used to implement the invention and achieve its objectives. Therefore, numerous embodiments will not be elaborated upon here.

[0028] The smart responsive antifouling coatings prepared in Examples 1 to 5 and the commercially available zinc acrylate self-polishing antifouling coating (control sample) were subjected to adhesion tests according to the international standard ISO 4624-2023 for pull-out method and the French standard GB / T9286-2021 for cross-cut adhesion test. The test results are shown in Table 1.

[0029]

[0030] The test results show that as the content of epoxy-modified acrylic resin matrix increases, the adhesion gradually increases, and the adhesion is significantly better than that of commercially available zinc acrylate self-polishing antifouling coatings.

[0031] The smart responsive antifouling coatings prepared in Examples 1 to 5 and a commercially available zinc acrylate self-polishing antifouling coating (control sample) were subjected to antibacterial experiments according to the following antibacterial steps. The specific antibacterial test steps are as follows: 1) Weigh the appropriate amount of culture medium powder and add it to a 250 mL Erlenmeyer flask. Add 100 mL of distilled water, seal the Erlenmeyer flask with a rubber band and a sealing film with a vent, and label it with the serial number and preparation date.

[0032] 2) Transfer the conical flasks containing TSA and the toothpicks (pipe tips, etc.) to a high-temperature sterilizer and sterilize at 121°C for 20 minutes (or 115°C for 30 minutes). After high-temperature sterilization, transfer the toothpicks (pipe tips, etc.) to an oven to dry at 60°C.

[0033] 3) Heat the mouth of the conical flask with an alcohol lamp, then pour the solid LB nutrient agar medium from the conical flask into the petri dish, filling it to about 1 / 2 full. Place the petri dish in a clean bench and cool for 10 minutes until it solidifies and there is no water vapor on the lid.

[0034] 4) Using a pipette, draw 3 mL of LB culture medium into a shaker tube. Then, change the pipette tip and draw 100 μL of glycerol bacteria, immersing it in the shaker tube containing LB broth. Mix thoroughly by repeatedly pipetting and blowing, then cap the tube and record the number and date. Simultaneously, set up a blank control group. Then transfer the tube to a shaker and incubate for 24 hours.

[0035] 5) The smart responsive antifouling coatings prepared in steps 1 to 5 and the commercially available zinc acrylate self-polishing antifouling coating were sterilized and disinfected by using anhydrous ethanol and ultraviolet light. The samples were then transferred to conical flasks containing 100 mL LB broth. The same number of treated steel plates were used for the blank control group.

[0036] Dilute the freshly cultured bacterial solution 100 times with sterile water in a gradient. Add 100 μL of the diluted bacterial solution to an Erlenmeyer flask, mix by pipetting, and then place the flask in a shaking incubator at 37°C and a shaking frequency of 150 r / min for 18-24 hours.

[0037] After the culture is complete, remove the sample from the incubator and place it in a laminar flow hood. Aseptically pipette 3 mL of antibacterial solution into a polystyrene round-bottom tube. Dilute to 10⁻⁴ and 10⁻⁵ using a sterile water gradient dilution method. Pipette 100 μL of each diluted antibacterial solution onto an LB nutrient agar plate and spread it evenly with a spreader. Cover the agar plate, seal the edges with sealing film, and incubate at 37°C for 24 hours.

[0038] Colony units (CFU) on the plates were studied, counted, and recorded. The number of *E. coli* colonies grown on solid medium was recorded as U1. The same procedure was performed on the original sample as a blank sample, and the number of *E. coli* colonies was recorded as U2. The antibacterial rate A of the samples is as follows: The test results are shown in Table 2 and the instruction manual appendix. Figure 1-6 .

[0039]

[0040] The test results show that when 10g of POSS-PAA slow-release material loaded with antifouling agent DCOIT is added (accounting for 16.5wt% of the total coating weight), the antibacterial rate of the coating against E. coli can reach 83%, which is much higher than the antibacterial rate of commercially available zinc acrylate self-polishing antifouling coatings. Moreover, the antibacterial rate increases with the increase of the amount of POSS-PAA slow-release material loaded with antifouling agent DCOIT. When the amount added is 40g (accounting for 48.5% of the total coating weight), the antibacterial rate against E. coli can reach 100%.

Claims

1. A method for preparing a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane, characterized in that... Includes the following steps: (1) Under the catalysis of N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, NH2-POSS and acrylic acid monomers were fully reacted in the liquid phase. After the reaction was completed, the reaction liquid was poured into diethyl ether for full precipitation. The precipitate was separated and washed. The washed precipitate was dried to obtain the product, namely POSS-PAA sustained-release material. (2) Disperse the POSS-PAA sustained-release material in a dispersion solvent, then add an environmentally friendly antifouling agent, stir the reaction thoroughly, and then remove the dispersion solvent to obtain the product, namely the POSS-PAA sustained-release material loaded with antifouling agent. (3) The epoxy resin E-51 and the acrylic monomer are polymerized to obtain the product, namely epoxy acrylic copolymer. (4) After fully mixing the POSS-PAA slow-release material loaded with antifouling agent, epoxy acrylic copolymer, leveling agent, defoamer and solvent, a pH-responsive smart marine anti-corrosion and antifouling coating based on cage-type silsesquioxane is obtained.

2. The preparation method of pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 1, characterized in that: The specific synthesis steps of the POSS-PAA sustained-release material are as follows: NH2-POSS was dissolved in N,N-dimethylformamide, and N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine were added. The mixture was then stirred and activated. After activation, acrylic acid monomer was added dropwise under nitrogen protection to react with NH2-POSS. After the addition was complete, the reaction continued under nitrogen protection. After the reaction was completed, the reaction solution was poured into diethyl ether for precipitation. After precipitation, the precipitate was separated and washed. The washed precipitate was dried to obtain the POSS-PAA sustained-release material.

3. The preparation method of the pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 2, characterized in that: The mass ratio of NH2-POSS, N,N-dimethylformamide, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine is 3-8:36-60:0.5-3:0.01-0.5; the mass ratio of NH2-POSS, acrylic acid monomer and diethyl ether is 3-8:15-35:85-145.

4. The pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 2, and its preparation method, is characterized in that: The stirring activation temperature is 25℃ and the time is 1-3 hours; the temperature for adding acrylic monomer is 20-60℃ and the time is 3-6 hours; after the acrylic monomer is added, the reaction with NH2-POSS continues at a temperature of 20-60℃ for 18-36 hours.

5. The preparation method of the pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 1, characterized in that: In step (2), the dispersing solvent is methanol, ethanol or butanol; the environmentally friendly antifouling agent is 4,5-dichloro-N-octyl-4-isothiazolin-3-one, and the amount of 4,5-dichloro-N-octyl-4-isothiazolin-3-one is 3-8 times the mass of POSS-PAA sustained-release material; the temperature for fully stirring the reaction is 20-35℃ and the time is 8-16 hours.

6. The preparation method of the pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 1, characterized in that: The specific synthesis steps of the epoxy acrylate copolymer are as follows: Epoxy resin E-51 is mixed with acrylic monomer, and triphenylphosphine catalyst is added to allow epoxy resin E-51 and acrylic monomer to react at a temperature of 75-85℃ for 2-5 hours. After the reaction is completed, epoxy acrylic copolymer is obtained.

7. The preparation method of the pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 6, characterized in that: The mass ratio of epoxy resin E-51, acrylic monomer and triphenylphosphine is 2-6:0.5-2:0.01-0.

2.

8. The preparation method of the pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 1, characterized in that: In step (4), the mass ratio of the POSS-PAA slow-release material loaded with antifouling agent, epoxy acrylic copolymer, leveling agent, defoamer and solvent is: 10-40: 30-40: 0.01-0.8: 0.01-0.8: 10-30.

9. The preparation method of pH-responsive smart marine anti-corrosion and antifouling coating based on cage-like silsesquioxane as described in claim 1 or 8, characterized in that: The leveling agent is BYK333 leveling agent, the defoamer is BYK1790 defoamer, and the solvent is ethyl acetate.

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