Composite acrylic acid low-surface-energy antifouling coating, preparation method and application

Abstract

The invention provides a composite acrylic acid low-surface-energy antifouling coating, a preparation method and application, and belongs to the technical field of marine antifouling materials, the composite acrylic acid low-surface-energy antifouling coating comprises a three-layer composite structure, the three-layer composite structure comprises a bottom layer, a middle layer and a surface layer from bottom to top, the bottom layer is capsaicin-loaded polymethyl methacrylate, and the middle layer is a polymethyl methacrylate surface layer. The bottom layer is made of capsaicin, the middle layer is made of pressure-sensitive adhesive activated by oxygen plasma, the surface layer is made of dihydroxyl-terminated polydimethylsiloxane, the mass ratio of the bottom layer to the middle layer to the surface layer is (23-25): 1: (23-25), and the mass content of capsaicin in the bottom layer accounts for 5.82-5.75% of the total mass; based on the bonding strength change of the pressure-sensitive adhesive generated by oxygen plasma jet and the capsaicin for effectively inhibiting biological growth, polyacrylic acid is used as a self-polishing reservoir to continuously release an environment-friendly antifouling agent; the pressure-sensitive adhesive adheres to the polydimethylsiloxane layer through the adhesive force change generated by oxygen plasma to achieve the low-surface-energy antifouling effect, synergistic gain is achieved, the composite material intervenes into the biological fouling process from multiple aspects, and the composite material copes with the marine biological fouling process jointly.

Description

Technical Field

[0001] This invention relates to the field of marine antifouling materials technology, specifically to a composite acrylic low surface energy antifouling coating, its preparation method, and its application. Background Technology

[0002] my country boasts a long coastline stretching for thousands of miles, abundant marine resources, and a bright future for marine development. There is great potential in the manufacture of a range of marine engineering projects, including large ships, submarines, and port terminals. However, the ever-changing marine environment places higher demands on the equipment and hulls of marine vessels. Among these challenges, biofouling poses the greatest economic and safety threat. Applying antifouling coatings is one of the most effective means of reducing biofouling and is a crucial antifouling measure for the hulls of marine vessels.

[0003] While antifouling coatings containing antifouling agents are effective, these agents are prone to runoff and have a limited lifespan in the open ocean environment. Furthermore, antifouling coatings containing metallic elements such as mercury, arsenic, tin, and copper pose potential hazards to the marine environment. Antifouling agents containing organotin have been explicitly prohibited by the International Convention on the Control of Hazardous Antifouling Systems for Ships.

[0004] The toxicity of antifouling agents has become a major factor limiting their development. To address this limitation, natural antifouling agents and low-surface-energy coatings have emerged. Natural antifouling agents are compounds extracted from natural products (plants, animals, etc.) that prevent biofouling. Low-surface-energy coatings use polymers of elements such as silicon and fluorine as the main components of the coating, maintaining their hydrophobic and smooth surface properties to make it difficult for fouling organisms to adhere. The construction of a composite system of antifouling agents and low-surface-energy coating technologies is of paramount importance. A composite antifouling system needs to meet the following two requirements: First, it must possess good mechanical properties such as adhesion to cope with the complex marine atmospheric environment faced by marine engineering equipment and have good bonding strength with the equipment substrate; second, it must be able to effectively release antifouling agents to kill bacteria or prevent fouling organisms from adhering, maintaining high hydrophobicity and bactericidal effects during long-term service. Therefore, composite antifouling coatings extend the durability and service efficiency of antifouling coatings in marine environments through their self-cleaning antifouling capabilities due to low surface energy and the antifouling effect generated by the continuous release of antifouling agents.

[0005] Capsaicin, chemically known as trans-8-methyl-N-vanillyl-6-nonenamide, is a natural compound found in chili peppers and their main active ingredient. It is generally irritating to organisms and is widely used in the biomedical field due to its biocompatibility and environmental friendliness. Capsaicin has been used as a bactericide against many microorganisms, exhibiting excellent bactericidal and degradation effects. This meets the prerequisite for use as an antifouling agent in environmentally friendly antifouling coatings. However, the use of natural antifouling agents alone in antifouling coatings suffers from uneven release and long-term failure; capsaicin alone cannot provide long-term antifouling protection for ship and marine equipment surfaces. By bonding a layer of hydroxyl-containing silicone oil to a self-polishing coating containing an antifouling agent, it gains strong hydrophobicity, anti-bioadhesion ability, and mechanical properties. Simultaneously, the hydroxyl-terminated polydimethylsiloxane layer has a smooth surface and possesses certain self-healing capabilities, anti-icing properties, and toughness. Even after being depleted in the marine environment, the underlying self-polishing coating continues to function, forming a composite antifouling system that promises long-lasting antifouling performance.

[0006] Self-polishing coatings using antifouling agents lack a hydrophobic surface structure. Under prolonged seawater immersion and current impact, the antifouling agent is continuously lost, and without proper adhesion, the self-polishing coating surface will eventually peel and break. However, applying oxygen plasma to the coating surface improves its adhesion, firmly bonding hydroxyl-terminated polydimethylsiloxane to the coating surface, thus overcoming the long-term application problems of conventional self-polishing coatings.

[0007] Simultaneously, research indicates that using double-sided pressure-sensitive adhesive tape (PSA) and oxygen plasma surface treatment technology, with acrylic resin containing antifouling agents as the lower interface coating, plasma can impart extremely high adhesion to the surface, allowing polydimethylsiloxane to be bonded at the upper interface to form a composite self-polishing low surface energy antifouling coating. Furthermore, the ability of oxygen plasma to modify the surface of polymer materials was investigated. Therefore, constructing a plasma-bonded composite system is currently the primary challenge in obtaining composite self-polishing low surface energy antifouling coatings. Summary of the Invention

[0008] Purpose of the Invention: The purpose of this invention is to address the shortcomings of existing solutions that attempt to combine two types of technologies, but face key obstacles. These obstacles include weak interlayer adhesion, specifically the difficulty in firmly bonding hydrophobic materials (such as polydimethylsiloxane) to the self-polishing layer, and the tendency of conventional adhesives to delaminate under seawater immersion; and the lack of dynamic antifouling, meaning there is no replacement mechanism after coating failure, failing to achieve gradient protection of "initial physical barrier + long-term chemical antifouling." Therefore, this invention provides a composite acrylic low surface energy antifouling coating, its preparation method, and its application. This invention is based on the change in adhesion strength of pressure-sensitive adhesive under oxygen plasma jets and the effective inhibition of biological growth by capsaicin. Polyacrylic acid is used as a self-polishing reservoir to continuously release environmentally friendly antifouling agents. The low surface energy antifouling effect is achieved by bonding the polydimethylsiloxane layer through the adhesion change of the pressure-sensitive adhesive under oxygen plasma, resulting in synergistic benefits and multi-faceted intervention in the biofouling process. The composite material jointly addresses the marine biofouling process.

[0009] Technical Solution: The present invention discloses a composite acrylic low surface energy antifouling coating comprising a three-layer composite structure, wherein the three-layer composite structure comprises, from bottom to top, a bottom layer, an intermediate layer, and a top layer. The bottom layer is polymethyl methacrylate loaded with capsaicin, the intermediate layer is a pressure-sensitive adhesive activated by oxygen plasma, and the top layer is dihydroxyl-terminated polydimethylsiloxane. The mass ratio of the bottom layer, intermediate layer, and top layer is (23-25):1:(23-25), and the capsaicin content in the bottom layer accounts for 5.82-5.75% of the total mass.

[0010] In other words, the bottom layer is a self-polishing acrylic reservoir that stores antifouling agents, including capsaicin. The principle is to mix environmentally friendly capsaicin (CAP) into the polishing reservoir to prevent ecological hazards caused by metal antifouling agents such as Cu2O.

[0011] Furthermore, the bottom layer comprises the following components by weight: polyacrylic acid resin: 70-75 parts; capsaicin CAP: 5-7 parts; film-forming agent: 3-5 parts; copper pyrite: 20-22 parts; ZnO: 9-11 parts; TiO2: 6-7 parts; Fe2O3: 6-8 parts; talc: 6-8 parts; activated carbon: 1.4-2 parts.

[0012] A method for preparing the composite acrylic low surface energy antifouling coating as described above includes the following steps:

[0013] Step 1: Preparation of polyacrylic acid reservoir

[0014] 1.1. AIBA and AIBN are mixed with water to obtain a mixed initiator. NaOH and AA monomers are mixed with water in a molar ratio of 1:1 to prepare solution 1. In addition, monomers BA, MA and AM are mixed in a certain proportion to prepare solution 2.

[0015] 1.2. Mix solution 1, solution 2, ethanol, and water at 70°C and 300 rpm with a magnetic stirrer for 15 min until the mixture turns blue. Then add solution 1 and solution 2 every 10 min, repeating 5 times. Continue stirring continuously for 1 h. Add solution 1 and stir for 30 min to obtain the polyacrylic acid reservoir.

[0016] Step 2: Prepare the base layer

[0017] 2.1 At room temperature, add polyacrylic acid reservoir, natural capsaicin, film-forming agent, copper pyrite, ZnO, TiO2, Fe2O3, talc and activated carbon into a grinding cup and grind them to a fineness ≤100μm.

[0018] 2.2. At a speed of 2000 rpm, the mixture was dispersed in a coating rapid dispersion tester for 35 min to obtain the bottom layer, namely the self-polishing acrylic reservoir (PMMA@CAP) storing capsaicin.

[0019] Step 3: Lamination and Plasma Treatment

[0020] 3.1 Spin-coating the self-polishing acrylic reservoir coating for storing capsaicin onto a glass substrate. First, gently clean the polyacrylic acid reservoir with isopropanol solvent and a wiping cloth. Then, laminate the PSA onto the polyacrylic acid reservoir. Apply PSA tape on top and press for 2 minutes to form a PMMA-PSA structure. Compress the PMMA-PSA structure with a trigger clamp for 2 minutes to promote bonding.

[0021] 3.2. Oxygen plasma treatment was performed on the surfaces of the PSA and MSDS layers: oxygen flow rate 25 mL / min, power 15 W, chamber pressure 700 mTorr, treatment time 1 minute; to increase their surface energy and promote the bonding of the two materials. After centrifugation, washing and drying, a PMMA-PSA-MSDS composite coating was obtained; the composite coating consisted of polyacrylic acid (PMMA), double-sided pressure-sensitive tape PSA, and dihydroxyl-terminated polydimethylsiloxane in a ratio of 23-25:1:23-25.

[0022] 3.3 The treated MSDS layer is bonded to the PMMA-PSA structure to obtain a composite acrylic low surface energy antifouling coating.

[0023] Furthermore, in step 1.1, the mixed initiator is a mixture of AIBA and AIBN in a 1:1 molar ratio, and the amount of ethanol added is 1.5-2 times the volume of the NaAA aqueous solution; the amount of water added is 6-7 times the volume of the NaAA aqueous solution.

[0024] Furthermore, in step 1, the mass ratio of monomers BA, MA, AM, AA, and capsaicin is 65:20:7.5:7.5:10.

[0025] Application of a composite acrylic low surface energy antifouling coating as described above in biomimetic fouling of marine engineering equipment.

[0026] Furthermore, marine engineering equipment includes ships, submarines, port facilities, or offshore platforms.

[0027] In this invention, the PMMA acrylic resin reservoir can effectively encapsulate the antifouling agent capsaicin (CAP), while continuously releasing environmentally friendly antifouling agents into the marine environment, achieving effective antifouling agent loading for the self-polishing coating. Furthermore, the acrylic resin reservoir itself continuously hydrolyzes and self-polishes to release capsaicin, and the hydroxyl-terminated polydimethylsiloxane on the surface provides hydrophobicity, making it difficult for fouling organisms to adhere. These factors complement each other, providing a more long-lasting antifouling effect. Simultaneously, through oxygen plasma treatment technology and pressure-sensitive adhesive as a binder, while achieving antifouling performance, it provides good substrate adhesion and abrasion resistance, and is not prone to cracking, for the composite antifouling coating. The hydroxyl-terminated polydimethylsiloxane MSDS layer on the surface plays a crucial role in the early stages of biofouling, preventing rapid initial biofilm formation. Over time, long-term seawater impact and immersion cause partial detachment and failure of the polydimethylsiloxane film layer. The inner acrylic resin continuously releases antifouling agents, compensating for the insufficient durability and impact resistance of the hydrophobic layer, and improving the protection against biofouling on the surface of marine equipment. In addition, the antifouling agent capsaicin (CAP) can effectively interfere with the calcium content of fungal and algal cells. 2+ The hydrophobic coating achieves a balance, thereby inhibiting biofilm growth and enhancing its antifouling properties. This results in a composite hydrophobic and antibacterial coating to prevent further biofouling, thus reducing energy consumption during ship navigation. The self-cleaning, low-surface-energy coating effectively mitigates the adhesion of fouling organisms. The inner antifouling coating acts as a second layer of antifouling, combining chemical and physical antifouling functions to synergistically address the problem of non-destructive marine organisms adhering to and fouling marine equipment, further improving the surface antifouling capability of marine equipment. Oxygen plasma technology modifies the interlayer adhesion interface, effectively combining the chemical antifouling layer and the physical hydrophobic layer, and providing excellent mechanical properties for the composite coating.

[0028] In theory, the antifouling coating, whether it is an acrylic structure, an antifouling agent, or a polydimethylsiloxane structure, can effectively prevent fouling and isolate the marine environment. It uses different physicochemical mechanisms to prevent biofouling, thereby increasing the smoothness of the surface of ships and marine equipment, effectively saving fuel and energy, and protecting marine equipment.

[0029] Specifically, the prepared composite coating, while achieving chemical antifouling, works in conjunction with low surface energy coatings to resist the erosion of biofouling environments from different channels, greatly improving the antifouling protection time and effect.

[0030] In marine engineering, this invention not only solves the problems that arise in the practical application of low surface energy coatings, but also overcomes to some extent the problems of high toxicity of antifouling agents and insufficient durability of natural antifouling agents in self-polishing coating systems, providing a promising solution for constructing long-lasting antifouling coatings.

[0031] Furthermore, the composite antifouling coating utilizes the self-polishing properties of polyacrylic acid hydrolysis, enabling it to release natural antifouling agents into the marine biofouling environment. The bonding polydimethylsiloxane layer reduces surface energy, allowing the composite coating to produce a non-fouling antifouling effect. This, combined with the reservoir's self-polishing and antifouling functions, results in a longer-lasting antifouling effect. This overcomes the limitations of various metal oxides as antifouling agents due to their high toxicity and strong pollution, making capsaicin antifouling agents applicable. Ultimately, this achieves a composite synergistic effect, environmental friendliness, and long-lasting antifouling.

[0032] Meanwhile, after obtaining PMMA-PSA-MSDS, the bonding of the PSA intermediate layer of the pressure-sensitive adhesive compensates for the poor adhesion of the MSDS. The free radicals released by oxygen plasma interact with the surface of the pressure-sensitive adhesive layer and the MSDS layer, changing the phases of the two materials from hydrophobic to hydrophilic. The MSDS surface that has not been treated with oxygen plasma maintains a low surface energy, thereby further enhancing the surface properties of the antifouling polyacrylic coating.

[0033] The prepared composite antifouling coating PMMA-PSA-MSDS integrates a series of effective antifouling mechanisms. In marine fouling environments, the combination of PMMA, CAP, and MSDS releases antifouling agents from the reservoir while maintaining low surface energy hydrophobicity, providing promising application prospects in marine fouling environments and achieving a multi-faceted synergistic self-cleaning and antifouling effect.

[0034] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0035] 1. Environmentally friendly. The composite antifouling coating of this invention, whether it is the base material, the surface material, or the antifouling agent it contains, is all natural and environmentally friendly, and will not cause pollution or damage to the marine environment, thus meeting the requirements of being bio-friendly, green, and non-toxic.

[0036] 2. Multi-layer assembly. The composite antifouling coating of this invention can be rapidly prepared and assembled in multiple layers. This is beneficial for multi-layer protection against mechanical damage and marine environmental erosion and corrosion. The multi-layer action first damages the outer coating and then consumes the inner coating, thereby extending the service life of the antifouling coating and improving its antifouling efficiency and durability.

[0037] 3. Convenient oxygen plasma treatment. The composite antifouling coating of this invention can be quickly assembled and bonded. This is attributed to the use of oxygen plasma treatment technology, which changes the activity and physicochemical properties of the material surface, quickly transforming the material from a hydrophobic and smooth surface to a hydrophilic and easily adhesive surface. This allows the composite coating to acquire a variety of excellent mechanical properties and triple antifouling capabilities, simplifying the operation, reducing time consumption, and addressing the slow application process, thus improving application efficiency.

[0038] 4. Enhanced Antifouling Performance. The composite antifouling coating of this invention releases the antifouling agent, while the acrylic resin continuously hydrolyzes under the influence of seawater, generating a self-cleaning effect. The surface hydrophobic layer also participates in multiple stages of preventing marine fouling by being washed away by ocean currents. This, combined with the stored and released antifouling agent (CAP), jointly resists marine fouling. This not only improves the antifouling durability and practical performance of the coating but also overcomes the ecological disaster of marine bioaccumulation caused by the use of biotoxic antifouling agents.

[0039] 5. Gradient Antifouling. The multi-layered assembly of the composite antifouling coating of this invention allows for the treatment and resolution of marine biofouling phenomena at different gradients and degrees. Therefore, the antifouling capability is continuously strengthened according to the degree of damage to the surface coating caused by the severity of fouling. Simultaneously, under the adhesive effect of oxygen plasma and the hydrolytic effect of acrylic resin, as the surface hydrophobicity gradually weakens, the dissociation of the acrylic resin is continuously regulated, thereby achieving intelligent control of the release of antifouling substances.

[0040] 6. Multi-functional. In the composite coating of this invention, the stored capsaicin (CAP) is an environmentally friendly antifouling agent that works by interfering with the calcium content of fungal and algal cells. 2+ This balance inhibits biofilm growth. The acrylic resin in the reservoir undergoes continuous hydrolysis under the action of water flow, resulting in a self-cleaning effect. The hydrolysis and shedding of the biofouling layer on the acrylic surface cleans away fouling organisms, thus providing antifouling protection. The hydroxyl-terminated polydimethylsiloxane resin on the surface has low surface energy and exerts its antifouling effect through its hydrophobic and slip-prone properties. These three antifouling mechanisms primarily address the adhesion of fouling organisms, preventing biofouling through multiple mechanisms such as reducing bioactivity, killing biofilms, and hydrophobicity and slip-prone properties, thereby providing a method for constructing a long-lasting composite antifouling coating.

[0041] 7. Synergistic Effect. According to literature reports, capsaicin (CAP) and acrylic resin in the composite coating of this invention have good compatibility and can jointly cope with various harsh biofouling environments. By combining oxygen plasma treatment technology with a polydimethylsiloxane surface, it responds to large fouling organisms (mussels, oysters), and the combined action of these three substances forms a multi-layered, self-polishing, low-surface-energy acrylic composite antifouling coating.

[0042] 8. Plasma Surface Adhesion Modification Technology. The significant difference between the composite coating of this invention and existing acrylic self-polishing coatings is the use of plasma surface treatment technology to alter the coating's surface energy, thereby achieving a multi-faceted synergistic effect. Based on the existing acrylic self-polishing coating's embedded antifouling agent technology, this is further combined with an oxygen plasma treatment process to achieve strong adhesion of hydroxyl-terminated polydimethylsiloxane to the upper layer of the acrylic coating, greatly improving the coating's hydrophobicity and mechanical properties, achieving a highly efficient and durable antifouling effect. Attached Figure Description

[0043] Figure 1 The synthesis route and application principle of the PMMA-PSA-MSDS composite coating provided in the embodiments of the present invention.

[0044] Figure 2 Fourier transform infrared spectrum of the composite coating provided in an embodiment of the present invention.

[0045] Figure 3 Water contact angle diagram of the composite coating provided in the embodiments of the present invention. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are all conventional reagents, methods and equipment in this technical field. Unless otherwise specified, the reagents and materials used in the following embodiments are all commercially available.

[0047] Example 1: Preparation of PMMA@CAP

[0048] Step 1: Preparation of a self-polishing polyacrylic acid antifouling layer

[0049] Preparation of polyacrylic acid reservoir: AIBA and AIBN were mixed with water to obtain a mixed initiator. NaOH and AA monomers were mixed with water to prepare solution 1. Monomers BA, MA, and AM were mixed in proportion to prepare solution 2. Solution 1, solution 2, ethanol, and water were magnetically stirred at 70℃ and 300rpm for 15min until the mixed solution turned blue. Then, solution 1 and solution 2 were added in 5 portions every 10min. Stirring was continued for 1h. Solution 1 was added for 30min to obtain the polyacrylic acid reservoir.

[0050] Step 2: Preparation of a polyacrylic acid coating loaded with the natural antifouling agent capsaicin (CAP).

[0051] A one-pot method was used, with 70.0 g of polyacrylic acid reservoir, 5.0 g of natural capsaicin, 3.0 g of film-forming agent, 20 g of copper pyrite, 9.0 g of ZnO, 6.0 g of TiO2, 6.0 g of Fe2O3, 6.0 g of talc, and 1.4 g of activated carbon added to a grinding cup at room temperature. The mixture was ground at 2000 rpm and dispersed in a rapid dispersion tester for 35 min to obtain the water-based acrylic self-polishing antifouling coating PMMA@CAP. The sample fineness was measured using a scraper fineness meter; a fineness less than 100 μm was used.

[0052] Example 2: Preparation of PMMA-PSA-MSDS

[0053] Based on the PMMA@CAP prepared in Example 1, after coating it onto a glass substrate, pressure-sensitive adhesive was applied and hydroxyl-terminated polydimethylsiloxane was coated onto its surface. The specific process is as follows:

[0054] The prepared polyacrylic acid coating was spin-coated onto a glass substrate. First, the polyacrylic acid reservoir was gently cleaned with isopropanol solvent and a wiping cloth. Then, a PSA was laminated onto the polyacrylic acid reservoir. The PMMA-PSA structure was compressed with a trigger clamp for 2 minutes to promote bonding. The surfaces of the PSA (already laminated onto PMMA) and MSDS were then subjected to oxygen plasma treatment for 1 minute under operating conditions of 15W, 25mL / min oxygen flow rate, and 700m Torr chamber pressure to increase their surface energy and promote bonding between the two materials, thus obtaining the PMMA-PSA-MSDS composite coating.

[0055] The loading method of the antifouling agent CAP is as described in step 2 of Example 1. Fourier transform infrared spectra of the antifouling coating surfaces CAP(a), PMMA@CAP(b), and PMMA-PSA-MSDS(c) obtained from the natural antifouling agent, Example 1, and Example 2 are shown below. Figure 2 As shown.

[0056] Test Example 1: Water contact angle of PMMA, PMMA@CAP, and PMMA-PSA-MSDS coatings

[0057] The blank 304 stainless steel samples, PMMA, PMMA@CAP, and PMMA-PSA-MSDS prepared in Examples 1 and 2 were immersed in natural seawater for 7 days, and the water contact angle was analyzed. The hydrophobicity of the coating was tested by the water contact angle. The test and analysis method is referenced in: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of China. GB / T 30693-2014. Measurement of water contact angle of plastic film [S]. Beijing: China Standards Press, 2014.

[0058] Water was used as the test liquid. The surface of the coated sample was ensured to be clean. The sample was fixed on the test stage, and its position was adjusted to be centered on the camera. For the static contact angle test, the droplet volume was 5.0 μL. The contact angle was measured three times at different positions on the sample, and the average value was taken. For the roll-off angle test, the water volume was 15.0 μL. The roll-off angle was measured three times at different positions on the sample, and the average value was taken. The results are as follows... Figure 3 Table 1 shows the water contact angles of blank 304 stainless steel samples, PMMA, PMMA@CAP, and PMMA-PSA-MSDS after immersion in seawater for 7 days. As shown in Table 1, the water contact angles of the coatings on the blank 304 stainless steel samples, PMMA, and PMMA@CAP are very low, wetting the surface and preventing sliding on the coating. PMMA-PSA-MSDS, with its hydrophobic MSDS layer, shows a significant change in both water contact angle and roll-off angle. Water and hexadecane can slide off the coating surface without leaving marks, further demonstrating that the adhesion of MSDS provides the antifouling properties of the coating.

[0059] Table 1. Water contact angles of PMMA, PMMA@CAP, and PMMA-PSA-MSDS

[0060]

[0061] Experimental Example 2: Algal Resistance to PMMA, PMMA@CAP, and PMMA-PSA-MSDS

[0062] Algal formation is also a major process in the second stage of marine biofouling. The anti-algal performance of a composite self-polishing low surface energy polyacrylic acid antifouling coating was tested using *Chlorella vulgaris*. Before the experiment, all experimental supplies, including culture media and pipettes, were sterilized with ultraviolet light for 30 minutes. *Chlorella vulgaris* strains were used as the experimental microalgae species. The microalgae were cultured in F / 2 medium at 20°C under visible light (LED) illumination (3000 lux) for 8 days. The algal solution in the logarithmic growth phase was diluted with culture medium to obtain an appropriate concentration (10⁻⁶) for subsequent experiments. 5 The 304 stainless steel samples with PMMA, PMMA@CAP, PMMA-PSA-MSDS coatings, and blank group (cells / mL) in Example 1 were immersed in diluted algal suspension for 7 days under alternating sunlight and darkness. Then, they were thoroughly rinsed with sterile PBS solution (pH=7.3) to remove loosely attached algae. The anti-algae ability of the composite self-polishing low surface energy polyacrylic acid antifouling coating was studied by measuring the absorbance at 440 nm. The absorbance represents the algal biomass.

[0063] As shown in Table 2, it can be seen that during the growth process, based on the characteristic absorption signal, there are significant differences in algal deposition between the test surfaces. The algal coverage rate of the composite self-polishing low surface energy polyacrylic acid antifouling coating is relatively low. The anti-algae mechanism of the composite self-polishing low surface energy polyacrylic acid antifouling coating is related to the continuously released antifouling agent capsaicin and the physical barrier of the MSDS layer. The composite self-polishing low surface energy polyacrylic acid antifouling coating of this invention has an algal resistance of 75.22%. The resistance calculation formula is as follows:

[0064] Algal resistance = (absorbance) 空白组 -Absorbance 实验组 ) / Absorbance 实验组 ×100%.

[0065] Table 2 Absorbance of PMMA, PMMA@CAP, and PMMA-PSA-MSDS

[0066]

[0067]

[0068] Experimental Example 3: Tensile Strength Test under Different Bonding Parameters

[0069] The bonding process was modified by setting the oxygen flow rate to 20, 25, and 30 mL / min, the power to 15 W, and the chamber pressure to 700 mTorrr. The processing time was set to 30 s, 1 min, and 2 min, respectively. The tensile strength of the PMMA@CAP@MSDS coatings with different bonding methods was measured at a displacement rate of 3 mm / min.

[0070]

[0071]

[0072] Experimental results show that when the oxygen treatment flow rate is set to 25 mL / min, power to 15 W, chamber pressure to 700 mTorrr, and treatment time to 1 min during the bonding process, the PMMA-CAP@MSDS exhibits the highest tensile strength. When the treatment time is 30 s and the oxygen flow rate is insufficient, the composite coating shows adhesive failure, indicating inadequate modification of the adhesive layer. When the oxygen flow rate is too high and the treatment time is too long, the lower PMMA-CAP layer exhibits superhydrophilic behavior, making stable bonding difficult, and the tensile strength decreases significantly compared to sample 5.

[0073] Experimental Example 4: Comparison of PMMA-CAP, PMMA-CAP@MSDS, and MSDS coating effects

[0074]

[0075] The preparation process of the single dihydroxyl-terminated polydimethylsiloxane coating MSDS is as follows: mix MSDS with xylene solvent in a certain proportion (e.g., 10-30% solid content), stir until uniform, dilute the mixed solution and then spray it uniformly through a spray gun at an air pressure of 0.2-0.5MPa. Evaporate the solvent at room temperature for 10-30 minutes, or bake at 60-80℃ for 5-10 minutes to remove bubbles.

[0076] The results above show that PMMA-PSA-MSDS has the best overall effect.

[0077] This invention presents a composite self-polishing low surface energy polyacrylic acid antifouling coating. Utilizing environmentally friendly capsaicin as an antifouling agent, and through the self-polishing ability of polyacrylic acid and the hydrophobic modification of MSDS, the antifouling performance is synergistically enhanced, achieving a multi-faceted integration of environmental friendliness, long-lasting antifouling, and hydrophobic modification for marine engineering materials. Furthermore, the surface of the material can be modified using simple oxygen plasma, allowing the PMMA-PSA-MSDS coating to improve its mechanical properties from multiple angles, including pressure-sensitive adhesive bonding and oxygen plasma phase boundary modification. This combines the advantages of two mainstream polymer antifouling coatings, making their long-term application in marine engineering possible.

[0078] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A composite acrylic low surface energy antifouling coating, characterized in that: The product comprises a three-layer composite structure, consisting of a bottom layer, a middle layer, and a top layer from bottom to top. The bottom layer is polymethyl methacrylate loaded with capsaicin, the middle layer is a pressure-sensitive adhesive activated by oxygen plasma, and the top layer is dihydroxyl-terminated polydimethylsiloxane. The mass ratio of the bottom layer, middle layer, and top layer is (23-25):1:(20-25), and the capsaicin content in the bottom layer accounts for 5.82-5.75% of the total mass.

2. The composite acrylic low surface energy antifouling coating according to claim 1, characterized in that: the bottom layer comprises the following components, by weight: polyacrylic acid resin: 70-75 parts; capsaicin CAP: 5-7 parts; film-forming agent: 3-5 parts; copper pyrite: 20-22 parts; ZnO: 9-11 parts; TiO2: 6-7 parts; Fe2O3: 6-8 parts; talc: 6-8 parts; activated carbon: 1.4-2 parts.

3. A method for preparing a composite acrylic low surface energy antifouling coating as described in claim 1 or 2, characterized by comprising the following steps: Step 1: Preparation of polyacrylic acid reservoir 1.

1. AIBA and AIBN are mixed with water to obtain a mixed initiator. NaOH and AA monomers are mixed with water at a molar ratio of 1:1 to prepare a 1 mol / L NaAA solution 1. In addition, monomers BA, MA and AM are mixed in a certain proportion to prepare a solution 2. 1.

2. Mix solution 1, solution 2, ethanol, and water at 70℃ and 300rpm for 15min until the mixed solution turns blue. Then add solution 1 and solution 2 every 10min, repeat 5 times, and continue stirring for 1h. Add solution 1 and stir for 30min to obtain the polyacrylic acid reservoir. Step 2: Prepare the base layer 2.1 At room temperature, add polyacrylic acid reservoir, natural capsaicin, film-forming agent, copper pyrite, ZnO, TiO2, Fe2O3, talc and activated carbon into a grinding cup and grind them to a fineness ≤100μm. 2.2 At a speed of 2000 rpm, the mixture was dispersed in a coating rapid dispersion tester for 35 min to obtain the bottom layer, namely the self-polishing acrylic reservoir for storing capsaicin; Step 3: Lamination and Plasma Treatment 3.1 Spin-coating the self-polishing acrylic reservoir coating for storing capsaicin onto the substrate, laminating PSA tape, and applying pressure for 2 minutes to form a PMMA-PSA structure; 3.

2. Oxygen plasma treatment of the PSA layer and MSDS layer surface: oxygen flow rate 25 mL / min, power 15 W, chamber pressure 700 mTorr, treatment time 1 minute; 3.3 The treated MSDS layer is bonded to the PMMA-PSA structure to obtain a composite acrylic low surface energy antifouling coating.

4. The method for preparing the composite acrylic low surface energy antifouling coating according to claim 3, characterized in that: In step 1.1, the initiator is a mixture of AIBA and AIBN in a 1:1 molar ratio. The amount of ethanol added is 1.5-2 times the volume of the NaAA aqueous solution, and the amount of water added is 6-7 times the volume of solution 1.

5. The method for preparing the composite acrylic low surface energy antifouling coating according to claim 3, characterized in that: In step 1, the mass ratio of monomers BA, MA, AM, AA, and capsaicin is 65:20:7.5:7.5:

10.

6. The application of a composite acrylic low surface energy antifouling coating as described in any one of claims 1-2 in biomimetic fouling of marine engineering equipment.

7. The application according to claim 6, characterized in that: The marine engineering equipment includes ships, submarines, port facilities, or offshore platforms.

Images