Natural antibacterial agent arbutin energized self-polishing antifouling nano composite coating and preparation method thereof

Abstract

The invention discloses a natural antibacterial agent arbutin energized self-polishing antifouling nano composite coating and a preparation method thereof.The preparation method comprises the steps that firstly, aminopropyl terminated polydimethylsiloxane and hexamethylene diisocyanate are synthesized into a prepolymer NPDI, then the prepolymer NPDI reacts with hydroxyethyl acrylate, and an organic matrix NPDA is obtained; the preparation method comprises the following steps: adsorbing arbutin by ZIF-8 to prepare ZIF-8 / Arb powder, blending the ZIF-8 / Arb powder with SiO2, adding NPDA, adding a fluorosilicone coupling agent, carrying out a blending reaction, and carrying out spraying and room temperature drying to prepare the self-polishing antifouling nano composite coating. The base body adopted by the coating is excellent in mechanical property and outstanding in structural stability, the lap joint shear strength reaches 14.08 MPa, the coating has the hydrolysis and low surface energy characteristics, and surface self-polishing and attached organism nondestructive stripping can be achieved under water flow shearing; the nano SiO2 improves wear resistance and durability, the ZIF-8 / Arb releases arbutin and Zn < 2 + > in a targeted manner in a subacid environment, synergistically and efficiently inhibits bacteria, inhibits biofilm formation, realizes long-acting active antifouling, and is suitable for a harsh marine environment.

Description

Technical Field

[0001] This invention relates to the field of functional protective coating technology, and in particular to a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin and its preparation method. Background Technology

[0002] Ships sailing at sea for extended periods inevitably become targets for various marine organisms (such as barnacles, algae, shellfish, and tube worms) to attach to their underwater hulls—a phenomenon known as biofouling. These seemingly small organisms cause a series of serious and costly problems, including: accelerated hull corrosion and soaring maintenance costs; increased drag and fuel consumption; increased greenhouse gas emissions and unnecessary energy waste; and the potential ecological disaster of biological invasion. Therefore, biofouling is far more than just a minor issue affecting the ship's surface; it is a complex, multi-dimensional problem involving ship operational safety, economic costs, energy efficiency, environmental protection, and ecological security. Applying antifouling coatings is a simple and effective way to solve this problem.

[0003] Early, widely used organotin antifouling coatings (such as tributyltin oxide, TBT) achieved excellent antifouling effects for up to 5 years, but their persistent biotoxicity in the marine environment caused ecological disasters. While tin-free self-polishing copolymer coatings (such as acrylic copper resin) reduced ecotoxicity as alternatives, their antifouling mechanism is highly dependent on the shear forces generated by ship speed. More seriously, the current mainstream antifouling agent, cuprous oxide (Cu2O), continuously releases copper ions into the marine environment, with annual global emissions reaching tens of thousands of tons. Once accumulated in sediments, copper ions can cause increased mortality in shellfish larvae and inhibit algal photosynthesis through the food chain.

[0004] Therefore, it is essential to develop a nanocomposite coating that combines self-polishing properties, high strength, and comprehensive antifouling capabilities to meet the requirements for high-efficiency and long-term application in harsh marine environments. Summary of the Invention

[0005] This invention provides a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin and its preparation method, in order to overcome the above-mentioned problems.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin, comprising the following steps: S1: Synthesis of organic matrix materials: High-strength prepolymer NPDI was obtained by synthesizing aminopropyl-terminated polydimethylsiloxane and hexamethylene diisocyanate. S2: Add hydroxyethyl acrylate to the prepolymer NPDI to obtain the polysiloxane-polyurethane acrylate polymer organic matrix material NPDA; S3: ZIF-8 / Arb powder, an antifouling functional substance with stable loading and controllable release, is obtained by adsorbing Arb with ZIF-8. S4: The ZIF-8 / Arb powder obtained in step S3 is mixed with SiO2 to obtain a mixture of ZIF-8 / Arb / SiO2 nanoparticles. Then, ZIF-8 / Arb / SiO2 is added to the organic matrix material NPDA obtained in step S2, followed by the addition of the coupling agent triethoxy-1H,1H,2H,2H-tridecylfluoro-N-octylsilane. After the reaction is complete, a self-polishing antibacterial nanocomposite material is obtained. The obtained composite material is sprayed and dried at room temperature for 72 h to obtain a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin, which is named NPDA. X , where X is the mass ratio of ZIF-8 / Arb / SiO2 nanoparticles to the matrix material NPDA.

[0007] Further, in step S4, the mass ratio of ZIF-8 / Arb powder to SiO2 is 1:1; ZIF-8 / Arb / SiO2 is added to the organic matrix material NPDA at a ratio of 0.5-3% of the mass of the organic matrix material NPDA; preferably, ZIF-8 / Arb / SiO2 is added to the organic matrix material NPDA at ratios of 0.5%, 1%, 1.5%, 2%, and 3% of the mass of the organic matrix material NPDA, respectively.

[0008] Further, in step S4, the molar ratio of the mixture ZIF-8 / Arb / SiO2 to triethoxy-1H,1H,2H,2H-tetrafluoro-N-octylsilane is 1:1~1.5; The blending reaction is carried out under stirring conditions for 2-3 hours, followed by subsequent spraying and drying steps.

[0009] Further, in step S1, the specific method for obtaining the prepolymer NPDI is as follows: aminopropyl-terminated polydimethylsiloxane is mixed with hexamethylene diisocyanate, tetrahydrofuran is added as a solvent, and the mixture is magnetically stirred for 2-3 hours under nitrogen protection at a reaction temperature of 50-60°C to obtain the prepolymer NPDI. The molar ratio of the aminopropyl-terminated polydimethylsiloxane to the hexamethylene diisocyanate is 1:1 to 1.2.

[0010] Further, in step S2, the molar ratio of the prepolymer NPDI to the hydroxyethyl acrylate is 1.2:1.

[0011] Further, the specific steps of step S2 are as follows: the organic matrix material NPDA is prepared by adding hydroxyethyl acrylate to the prepolymer, reacting it in tetrahydrofuran solvent under nitrogen protection at a temperature of 50-60°C with magnetic stirring for 2-3 hours.

[0012] Further, in step S3, the antifouling functional material ZIF-8 / Arb powder is prepared by the following method: 2-Methylimidazole and zinc nitrate hexahydrate were dissolved separately in a solvent and magnetically stirred until completely dissolved. The two solutions were then mixed and stirred at room temperature until the solution turned milky white. The milky white solution was then transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 60-80°C for 10-12 hours. After the reaction, the solid product was separated, washed, dried, and ground to obtain ZIF-8 powder. The washing method was as follows: the white precipitate was repeatedly washed with methanol or ethanol, followed by centrifugation. The washing and centrifugation steps were repeated three times. The drying conditions were: vacuum drying at 60-80°C for 10-12 hours. The prepared ZIF-8 powder was placed in a PBS solution with an Arb concentration of 100 mg / mL and magnetically stirred for 30 min to complete adsorption. The resulting suspension was then centrifuged, the precipitate was washed with PBS solution, and dried under vacuum at 60–80 °C for 6–8 h to obtain the antifouling functional material ZIF-8 / Arb powder. Further, in step S3, the mass ratio of 2-methylimidazole to zinc nitrate hexahydrate is 1:2–2.5.

[0013] Furthermore, in step S3, the solvent is selected from either methanol or ethanol.

[0014] In another aspect, the present invention provides a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin, which is prepared by the aforementioned preparation method.

[0015] The beneficial effects of this invention are: I. The organic matrix material synthesized in this invention possesses excellent mechanical properties, with an overlap shear strength reaching 14.08 MPa, exhibiting outstanding structural stability. Even in harsh marine environments, this material can effectively resist mechanical damage and maintain structural integrity, thereby ensuring long-term stable antibacterial function.

[0016] II. This invention utilizes ZIF-8-loaded arbutin (Arb) as a functional component, achieving efficient storage and controlled release of arbutin. This transforms the antifouling coating from a traditional passive physical barrier into an advanced material with active antibacterial function, intelligent response, and long-lasting maintenance of an antibacterial microenvironment. The coating matrix achieves dynamic surface control through the combined effect of its low surface energy characteristics and hydrolyzable components. The introduction of hydroxyethyl acrylate endows the matrix material with intrinsic hydrolytic properties, enabling self-polishing of the material surface during ship navigation using the shear force of water flow, thereby removing attached organisms without damage. Simultaneously, the addition of nano-silica further enhances the material's wear resistance, ensuring the coating's durability under long-term frictional environments.

[0017] Third, in this invention, ZIF-8 / Arb can achieve targeted release of arbutin in a slightly acidic environment formed by microbial enrichment, and release Zn along with the disintegration of the ZIF-8 skeleton. 2+ Zn 2+ It can enhance the interaction with electronegative bacteria, disrupting their cell barriers and internal structures, thereby effectively inhibiting biofilm formation; at the same time, the hydroxyl functional groups abundant in the natural antibacterial agent arbutin can significantly interfere with bacterial life activities and interact with Zn. 2+ The ion bactericidal effect works synergistically to enhance the antibacterial performance of the entire system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the preparation process of the ZIF-8 / Arb / SiO2-NPDA coating of the present invention. Figure 2 The surface morphology diagram and elemental distribution diagram of the coating prepared in this invention are shown below. Figure 2 a is a SEM image of ZIF-8 nanoparticles. Figure 2 b is a SEM image of the ZIF-8 / Arb nanoparticles. Figure 2 c is the SEM image of SiO2 nanoparticles. Figure 2 d is the SEM image of the NPDA coating. Figure 2 e is NPDA 0.5 SEM image of the coating, Figure 2 f is a SEM image of the NPDA1 coating. Figure 2 g is a SEM image of the NPDA2 coating. Figure 2 h is the SEM image of the NPDA3 coating. Figure 2 i represents the elemental distribution diagram of the ZIF-8 / Arb / SiO2-NPDA coating surface; Figure 3 The figure shows the hydrolysis performance results of the coating prepared according to the present invention, wherein, Figure 3 a represents the hydrolysis weight loss results of NPDA and coatings with different nanoparticle contents. Figure 3 b represents the water absorption rate of NPDA and coatings with different nanoparticle contents; Figure 4 The image shows the surface wettability of the coating prepared according to the present invention. Figure 4 a is the contact angle before coating hydrolysis. Figure 4 b is the surface energy of the coating before hydrolysis. Figure 4 c is the contact angle after coating hydrolysis. Figure 4 d represents the surface energy of the coating after hydrolysis; Figure 5 The mechanical strength test results of the coating prepared according to the present invention are shown below. Figure 5 a is a schematic diagram of the coating adhesion tape peel test; Figure 5 b shows the results of the lap shear strength test; Figure 5 c represents the sandpaper abrasion test; Figure 5 d represents the sand abrasion cycle test.

[0020] Figure 6 The figure shows the results of the anti-bioadhesion and antifouling performance of the coating prepared in this invention. Figure 6 a represents the result of the anti-protein adhesion test. Figure 6 b is a visual comparison of the algae inhibition experiments of the coatings after 0 days, 5 days, and 15 days; Figure 6 c. The 15-day absorbance spectra of the control group and the five coatings; Figure 6 d represents the inhibition rate of the five coatings on Chlorella after 15 days; Figure 7 The results show the antibacterial properties of different coatings prepared according to the present invention, wherein... Figure 7 Figure a shows the results of plate coating experiments on the inhibition of Escherichia coli and Staphylococcus aureus by different coatings before hydrolysis and the control group; Figure 7 Figure b shows the results of plate coating experiments on Escherichia coli and Staphylococcus aureus with different coatings after 30 days of hydrolysis. Figure 7 c represents the inhibition rate of different coatings against Escherichia coli and Staphylococcus aureus before hydrolysis. Figure 7 d represents the inhibition rate of different coatings against Escherichia coli and Staphylococcus aureus after 30 days of hydrolysis; Figure 8 The results of the marine field antifouling test comparing the performance of the ZIF-8 / Arb / SiO2-NPDA coating prepared in this invention are presented. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention utilizes arbutin (Arb), a plant-derived glycoside compound, which is readily biodegradable in the natural environment, avoiding persistent residues in ecosystems. Its antibacterial action does not involve heavy metal ions or recalcitrant organohalides, thus avoiding significant toxic stress or ecological damage to aquatic organisms and soil microbial communities. Compared to traditional antibacterial agents, arbutin combines highly effective antibacterial properties with excellent biocompatibility, conforming to green chemistry principles and making it a promising environmentally friendly antifouling agent. Furthermore, nanocomposite materials, with their unique functional groups combined with antibacterial agents, exhibit unique self-polishing and long-lasting antibacterial advantages in the field of antifouling.

[0023] Example: like Figure 1 The above describes a method for preparing a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin, as provided in this embodiment, including the following steps: S1: A high-strength prepolymer (NPDI) was synthesized using aminopropyl-terminated polydimethylsiloxane and hexamethylene diisocyanate. Under nitrogen protection, 10 g of aminopropyl-terminated polydimethylsiloxane (PDMS) and 1.68 g of hexamethylene diisocyanate (HDI) (molar ratio 1:1) were added to a three-necked flask containing tetrahydrofuran (THF). The system was magnetically stirred at 600 rpm for 2 h at 60 °C to allow the two to fully react and prepolymerize, thus obtaining the high-strength prepolymer NPDI. S2: Preparation of NPDA matrix Subsequently, 0.96 g of hydroxyethyl acrylate (HEA) was added to the high-strength prepolymer NPDI, i.e., the feeding ratio was controlled at NCO:OH = 1.2:1, and the reaction was carried out at 60℃ and 600 rpm for 2 h to finally obtain NPDA (polysiloxane-polyurethane acrylate) solution. Aminopropyl-terminated polydimethylsiloxane (HEA), as a low surface energy component, is introduced into the coating system, significantly reducing the surface energy of the coating and thus imparting initial hydrophobic properties. The amino functional groups at the ends of the polymer chains exhibit high reactivity, reacting chemically with the isocyanate groups (-NCO) at the hexamethylene diisocyanate (HDI) ends in the system to form urea bonds (–NH–CO–NH–). Simultaneously, the addition of HEA reacts with HDI to generate urethane bonds (–NHCOO–). This reaction not only effectively increases the crosslinking density of the polymer network within the coating, significantly improving the mechanical strength of the material, but also this strengthened crosslinked network structure is more conducive to the stable construction and performance maintenance of subsequent structures.

[0024] S3: Preparation of the antifouling functional material ZIF-8 / Arb, including two steps: preparation of ZIF-8 powder and preparation of ZIF-8 / Arb powder, as detailed below: S31: ZIF-8 powder was synthesized using a solvothermal method. First, 6g of zinc nitrate hexahydrate was dissolved in 100mL of methanol to form a first solution. Then, 13.92g of 2-methylimidazole was dissolved in 100mL of methanol to form a second solution. The first and second solutions were mixed and magnetically stirred for 3 hours. The mixture was then transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE) and reacted at 70℃ for 12 hours. After the reaction, the system was allowed to cool to room temperature. The solid product was separated by centrifugation at 4000 r / min and washed with methanol. This centrifugation and washing step was repeated three times. The resulting solid was vacuum dried at 70℃ for 10 hours and then ground to obtain ZIF-8 powder. S32: Preparation of ZIF-8 / Arb powder: All the ZIF-8 powder prepared above was placed in a PBS solution with an Arb concentration of 100 mg / mL and magnetically stirred for 30 min to complete the adsorption process. Then, it was centrifuged, washed, and dried to obtain ZIF-8 / Arb powder.

[0025] S4: ZIF-8 / Arb / SiO2 was blended with NPDA to prepare a ZIF-8 / Arb / SiO2-NPDA coating, namely a self-polishing and anti-fouling nanocomposite coating. ZIF-8 / Arb powder and SiO2 were mixed at a mass ratio of 1:1 to prepare ZIF-8 / Arb / SiO2 composite powder. Then, 0.06 g, 0.12 g, 0.24 g, and 0.36 g of this composite powder (corresponding to 0.5%, 1%, 2%, and 3% of the NPDA matrix mass), respectively, were weighed and added to the NPDA matrix prepared in step S2. Subsequently, equal masses (0.06 g, 0.12 g, 0.24 g, and 0.36 g) of the coupling agent triethoxy-1H,1H,2H,2H-tridecylfluoro-N-octylsilane (FOTS) were simultaneously added for surface coupling treatment. The resulting polished and anti-fouling nanocomposite materials were sequentially labeled as NPDA. 0.5 NPDA1, NPDA2, and NPDA3 were mixed. The mixtures were stirred using a heated magnetic stirrer at 60°C until homogeneous. The resulting slurry was then coated onto the surface of the substrate and dried at room temperature for 72 hours to form a ZIF-8 / Arb / SiO2-NPDA coating. Based on the amount of ZIF-8 / Arb / SiO2 added, the coating samples were designated as NPDA (without addition), NPDA2, and NPDA3, respectively. 0.5 NPDA1, NPDA2, and NPDA3. The introduction of ZIF-8 into the coating provides the coating system with dual functions: firstly, its nanoscale polyhedral structure constructs a micro-nano composite rough topology on the coating surface, significantly increasing the air trapping ratio at the solid-liquid interface and effectively reducing the actual solid-liquid contact area; secondly, when bacterial attachment induces local microenvironment acidification, the ZIF-8 framework undergoes controlled dissociation, releasing Zn. 2+ Arb disrupts bacterial cell membrane integrity, interferes with the bacterial tricarboxylic acid cycle (TCA cycle), and causes respiratory chain complex enzyme dysfunction and abnormal membrane potential, thus achieving highly efficient antibacterial activity. Simultaneously, the addition of FOTS plays a synergistic role; its ethoxysilane end groups form coupling bridges with NPDA, significantly enhancing the dispersion stability of ZIF-8 / Arb nanoparticles in the matrix. The terminal perfluoroalkyl long chains are oriented through surface enrichment effects, further reducing the overall surface energy of the coating by utilizing the extremely low surface energy of fluorine atoms.

[0026] The loading of silica, in synergy with ZIF-8, constructs a two-scale rough structure. This loading is achieved not only through strong hydrogen bonds formed between the urethane bonds (-NHCOO-) of NPDA and the silanol groups (Si-OH, hydrogen bond donors) on the SiO2 surface, as well as the oxygen atoms (Si-O-Si, hydrogen bond acceptors) in the silicon-oxygen bonds, but also through weak hydrogen bonds formed between the nitrogen sites (-N=, hydrogen bond acceptors) on the ZIF-8 framework and the silanol groups (Si-OH, hydrogen bond donors). This further stabilizes the loading, resulting in a layer-by-layer accumulation of hydrogen bonds that gives the coating superior stability and wear resistance.

[0027] Experimental Results and Analysis: (1) SEM image analysis of ZIF-8, ZIF-8 / Arb, SiO2 nanoparticles and ZIF-8 / Arb / SiO2-NPDA coating The microstructure of ZIF-8, ZIF-8 / Arb, SiO2 nanoparticles, and the ZIF-8 / Arb / SiO2-NPDA coating was characterized using scanning electron microscopy (SEM). First, the ZIF-8, ZIF-8 / Arb, SiO2 nanoparticles, and ZIF-8 / Arb / SiO2-NPDA coating samples were subjected to gold sputtering in an ion sputtering apparatus. Then, the surface morphology and structure of the gold-sputtered ZIF-8 and ZIF-8 / Arb nanoparticles at 1 μm, SiO2 at 5 μm, and the ZIF-8 / Arb / SiO2-NPDA coating at 200 μm were observed using SEM. The results are as follows: Figure 2 As shown.

[0028] from Figure 2 As can be clearly seen in a, the ZIF-8 nanoparticles exhibit a relatively uniform dodecahedral structure, with a particle size distribution ranging from hundreds of nanometers to 1 micrometer; Arb adsorption on the ZIF-8 surface can be observed in the ZIF-8 / Arb mixture, confirming the effective loading of Arb by ZIF-8. Figure 2 b; Figure 2 The SiO2 in c exhibits a typical spherical morphology. Figure 2 (d) – Figure 2 SEM images of the coatings (h) from NPDA to NPDA3 show that the coating surface gradually becomes rougher as the ZIF-8 / Arb / SiO2 nanoparticle content increases. This roughness is jointly provided by the ZIF-8 / Arb / SiO2 nanoparticles, where ZIF-8 / Arb plays an antibacterial role and SiO2 plays a hydrophobic reinforcing role. Further analysis using EDS elemental distribution maps... Figure 2 i) The successful preparation of the ZIF-8 / Arb / SiO2-NPDA coating was verified from the perspective of elemental composition.

[0029] (2) Test results of coating self-polishing and water absorption properties This invention tests and evaluates the self-polishing and water absorption properties of the prepared ZIF-8 / Arb / SiO2-NPDA coating.

[0030] Self-polishing performance test: The coated glass slides were immersed in water and sampled every 5 days. After sampling, the sample surface was rinsed with deionized water and then dried in a 60°C constant temperature drying oven for 30 minutes until constant weight, and weighed using an analytical balance with an accuracy of 0.1 mg.

[0031] Water absorption test: The coating was evenly applied to an area measuring 2.5 cm × 7 cm with a mass of W. g On a glass slide, after curing for 72 hours, the mass W0 of the coated slide was recorded. The slide was then completely immersed in water for 7 days, and after removal, surface moisture was quickly removed and the slide was weighed to obtain W. t Calculate its water absorption rate W. A .

[0032]

[0033] The hydrolysis performance test results of each layer are as follows: Figure 3 As shown. The results of the long-term hydrolysis test are as follows. Figure 3 As shown in Figure a, the hydrolysis rate of the coating gradually increased with the addition of ZIF-8 / Arb / SiO2 nanoparticles from 0% to 3%. The NPDA coating without added nanoparticles had the lowest hydrolysis rate, demonstrating the good water resistance of its cross-linked network. When the addition of ZIF-8 / Arb / SiO2 nanoparticles was 2% (NPDA2), the cumulative hydrolysis amount of the coating over 60 days was 0.6 mg / cm³. 2 The appropriate hydrolysis behavior of NPDA2 is beneficial for achieving a layer-by-layer polishing antifouling mechanism. Excessive addition (such as NPDA3) leads to excessively rapid hydrolysis, causing premature coating degradation; insufficient addition (0.5%–1%) of ZIF-8 / Arb / SiO2 nanoparticles results in insufficient polishing rate, affecting the durability of antifouling. NPDA2 achieves an optimized balance between nanoparticle content and hydrolysis rate, thus maintaining structural stability while achieving long-lasting antifouling performance.

[0034] Water absorption test results ( Figure 3 b) shows that the NPDA coating has a water absorption rate of only 3.43%. 0.5 The water absorption rates of NPDA1 and NPDA2 coatings were 6%, 22.2%, and 26.92%, respectively, while NPDA3 reached 49.3%. This difference stems from the different material composition: the NPDA coating is mainly composed of high-bond-energy Si-O bonds, forming an effective energy and physical barrier that blocks water molecule penetration, thereby controlling the water absorption rate and degree of hydrolysis at a low level.

[0035] (3) Contact angle and surface energy test before and after coating hydrolysis This invention analyzes the surface wetting properties of a natural extract antifouling coating, and the results are as follows: Figure 4 As shown. The changes in the wetting behavior of the coating during static seawater immersion at room temperature were evaluated by contact angle testing, as shown. Figure 4 a and Figure 4 As shown in c, after 10 days of immersion, the diiodomethane contact angle of the NPDA coating decreased by 12°. 0.5The water contact angles of the NPDA1 and NPDA3 coatings decreased by 5°, 4°, and 6°, respectively, while the contact angles of the NPDA2 coating with water and diiodomethane decreased only slightly, indicating that it has good stability in the seawater environment.

[0036] The surface energy of the coating before and after immersion was further calculated using the Owens-Wendt-Rabel-Kaelble method, and analyzed using Bayer curves. The results are as follows: Figure 4 b and Figure 4 As shown in d, NPDA 0.5 The coatings, NPDA1 coating, and NPDA2 coating maintained low surface energy (20–30 mJ / m²) throughout the experiment. 2 This indicates that the coating surface has stable chemical properties and is not easily altered by seawater immersion, thus helping to inhibit biofilm adhesion and marine biofouling. These results, from an interfacial energy perspective, confirm that NPDA2, as a naturally derived antifouling coating, possesses consistently low surface energy characteristics and reliable anti-biofouling capabilities.

[0037] (4) Coating mechanical strength test and results This invention systematically tested and evaluated the mechanical properties of the marine antifouling coating, and the results are as follows: Figure 5 As shown. The adhesion between the NPDA2 coating and the substrate was determined using the tape peel method, and the results are as follows. Figure 5 As shown in Figure a, after 200 repeated peeling cycles, the NPDA2 coating remained intact without any peeling. According to the ASTM D3359 standard, "Standard Test Method for Determining Adhesion by Tape Test," the adhesion grade was rated as 5B, indicating that the NPDA coating has excellent interfacial bonding between itself and the substrate, as well as between its components.

[0038] The results of the overlap shearing experiment are as follows Figure 5 As shown in b, the coating shear strength is 14.08 MPa, demonstrating good load-bearing capacity. Regarding abrasion resistance, after 20 cycles of wear with 60-grit sandpaper (…), Figure 5 c), the coating thickness was reduced by only 14 μm, demonstrating the high wear resistance imparted by the combination of SiO2 nanoparticle reinforcement and polymer toughness network.

[0039] Further evaluation of the surface property changes of the NPDA2 coating was conducted through a sand abrasion test. Figure 5 d) After 20 impacts from a height of 30 cm, the contact angle of the NPDA2 coating surface only decreased by about 5°, indicating that its surface chemical composition and structure remained stable under mechanical wear. Among them, SiO2 nanoparticles made a significant contribution to improving the coating's hardness and resistance to deformation.

[0040] In summary, the excellent mechanical properties of this coating stem from its sophisticated microstructure design and the synergistic enhancement effect of its multiple components.

[0041] (5) Anti-protein adhesion and Chlorella inhibition test The present invention tested the coating's resistance to protein adhesion and algae growth, and the results are as follows: Figure 6 As shown.

[0042] Anti-protein adhesion test: The coated samples were pre-soaked in phosphate-buffered saline (PBS, pH=7.2) for 2 hours, followed by immersion in 0.5 mg / mL bovine serum albumin (BSA) solution for 24 hours. After removal, the samples were rinsed with PBS, Coomassie Brilliant Blue working solution was added, and the absorbance was measured using a UV-2600 spectrophotometer. The results are as follows: Figure 6 As shown in Figure a: the absorbance of the blank glass group at 595 nm is approximately 0.48, indicating that proteins readily adsorb onto the coating surface; the absorbance of the pure NPDA coating decreases to 0.38, demonstrating the hydrophobic and anti-adhesion properties of polydimethylsiloxane. With the increase of ZIF-8 / Arb / SiO2 nanoparticle content from 0.5% to 3%, the anti-protein adhesion performance of the coating continuously improves, and the NPDA... 0.5 The absorbances of NPDA1, NPDA2 and NPDA3 were 0.37±0.03, 0.35±0.01, 0.34±0.01 and 0.33±0.01, respectively, showing a significant dose-dependent increase.

[0043] Anti-algae adhesion experiment: Chlorella vulgaris was used as a representative algae, and cultured for 15 days under a 12:12 light-dark cycle, with regular shaking to ensure normal growth and adhesion. The absorbance (OD) at 680 nm was measured. 680 The concentration of algae was reflected, and the inhibition rate was calculated using a pure glass plate as a control. Figure 6 b represents 0 days, 5 days, and 15 days of Control and NPDA. 0.5 A visual comparison of the algae inhibition effects of NPDA1, NPDA2, and NPDA3 coatings (from left to right). From left to right, the colors change from dark to light; the lighter the color, the lower the algae biomass and the better the inhibition effect.

[0044] Figure 6 In c, as the content of ZIF-8 / Arb / SiO2 nanoparticles in the coating increases, OD... 680 The values ​​gradually decreased, indicating that algal growth was significantly inhibited. NPDA, NPDA 0.5 The inhibition rates of NPDA1, NPDA2, and NPDA3 against Chlorella were 11.91%, 23.89%, 27.65%, 32.61%, and 33.4%, respectively. Figure 6(d) shows that the content of ZIF-8 / Arb / SiO2 nanoparticles is positively correlated with the algae-inhibiting effect. This performance is mainly due to the Arb active ingredient continuously released by the ZIF-8 / Arb nanoparticles in the coating, which can effectively interfere with the physiological activities of algal cells, thereby improving the overall antifouling performance.

[0045] (6) Antibacterial test of coating The antibacterial properties of the coating were systematically tested in this invention.

[0046] Based on the standards "Determination of antimicrobial properties of plastics and other nonporous surfaces" (ISO 22196) and "Standard test method for determining the antimicrobial activity of antimicrobial agents under dynamic contact conditions" (ASTM E2149), *Escherichia coli* (ATCC 25922) and *Staphylococcus aureus* (ATCC 6538) were selected as test strains. All strains were purchased from Beijing Baocang Biotechnology Co., Ltd. The antimicrobial rate of different coatings was determined using the plate count method. All experimental materials were autoclaved and the operations were performed in a clean bench. First, the bacteria were activated and inoculated into LB liquid medium to prepare a concentration of approximately 10%. 8 CFU / mL bacterial suspension. Place the glass plate coated with the sample into the bacterial suspension and incubate at 37°C for 24 hours. After removal, rinse with LB medium, dilute the eluent to 0.1% of its original concentration, and spread 100 μL onto LB solid medium. Incubate at 37°C for 24 hours, count the colonies, and calculate the antibacterial rate E. b .

[0047]

[0048] in, and The figures represent the average number of bacteria on the blank control sample and the paint-coated sample, respectively. For antibacterial rate.

[0049] Figure 7 a, Figure 7 Images b show the antibacterial plates before and after 30 days of hydrolysis. The results showed that the glass plate control group had no antibacterial activity, while the pure NPDA coating, due to the hydrophobic properties of the polydimethylsiloxane matrix, exhibited an inhibition rate of approximately 50-60% against both bacteria. Figure 7 c). With the increase of nanoparticle (ZIF-8 / Arb and SiO2) content, the antibacterial performance is significantly improved: NPDA 0.5The inhibition rates against *Escherichia coli* and *Staphylococcus aureus* reached 67% and 80%, respectively. NPDA1 increased these rates to 95% and 96%, while NPDA2 exhibited the best antibacterial effect (99% against *Escherichia coli* and 99% against *Staphylococcus aureus*), indicating that a 2% nanoparticle addition level was close to the saturation threshold of antibacterial performance. This effect is mainly attributed to the breakdown and release of Zn by ZIF-8 in a slightly acidic environment. 2+ Together with arbutin (Arb), they work synergistically against bacteria, Zn 2+ Arb can disrupt the cell barrier, and its hydroxyl functional group can interfere with bacterial life activities, thereby achieving targeted inactivation of bacteria.

[0050] To examine the performance stability of the coating during long-term use, the antibacterial test was performed again on the sample after 30 days of hydrolysis. Figure 7 b、 Figure 7 d). Compared with the fresh coating, the antibacterial rate of the hydrolyzed coating decreased slightly, but still remained at a high level. Among them, the antibacterial rates of the three coatings, NPDA1, NPDA2, and NPDA3, remained above 90% after long-term hydrolysis, confirming the targeted and controlled release of Arb by ZIF-8 and the persistence and reliability of its antibacterial function in practical application environments.

[0051] (7) Antifouling experiments in actual marine environments This invention utilizes field experiments conducted in a real marine environment. The seaplate dimensions were 15 cm × 20 cm, and the average coating thickness was 208 μm. This experiment systematically evaluated the antifouling performance of different modified coatings. The experiment was conducted during the peak season for biological reproduction and attachment in the coastal waters of the Yellow Sea. Figure 8 The study compared the biofouling status of the blank control group (uncoated) and five NPDA series coated test plates at different time points throughout the experimental period.

[0052] After 35 days of static immersion, the blank control group test panels showed severe biofouling, covered with a large number of large algae and shellfish larvae, forming a structurally stable fouling community. In contrast, the NPDA series coated test panels all showed varying degrees of fouling inhibition, and the antifouling performance decreased with changes in composition: the severity of fouling was in the order of NPDA > NPDA. 0.5 >NPDA1>NPDA3>NPDA2.

[0053] Among them, a certain area of ​​biofilm and medium-sized fouling biofilm were still visible in the NPDA coating; however, as the degree of modification increased, NPDA... 0.5 The fouling area of ​​the NPDA1 and NPDA3 coatings gradually decreased. In particular, the NPDA2 coating exhibited excellent overall antifouling performance. At the end of the entire experimental period, only sporadic biofilms and diatoms were observed on its surface, with no large-scale macroscopic biological colonization. Figure 8 The results showed that the fouling coverage area of ​​the NPDA2 surface was significantly lower than that of other experimental groups, demonstrating good resistance to bioadhesion and inhibition of community settlement.

[0054] Furthermore, the NPDA2 coating contains arbutin (Arb), a natural antibacterial agent with outstanding environmental friendliness. As a plant-derived glycoside compound, arbutin is easily biodegradable in the natural environment and does not persist in the ecosystem. Its antibacterial effect does not rely on heavy metal ions or recalcitrant organic halides or other environmentally harmful substances, therefore it poses no significant toxic stress to aquatic organisms or soil microbial communities, conforming to the principles of green chemistry. It is an environmentally friendly antifouling agent that combines highly effective antibacterial properties with excellent biocompatibility.

[0055] Based on the above experimental results, it is demonstrated that this invention has successfully prepared a polymer-based integrated nanoparticle antifouling coating. This coating achieves the integration and optimization of multiple properties through the synergistic effect of ZIF-8 / Arb and SiO2 nanoparticles: 1. Controllable microstructure: This invention provides a self-polishing and anti-fouling nanocomposite coating surface empowered by the natural antibacterial agent arbutin, which exhibits controllable roughness as the content of nanoparticles increases. ZIF-8 / Arb is responsible for antibacterial activity, while SiO2 enhances hydrophobicity and mechanical properties. 2. Balance between self-polishing and hydrolytic stability: When the nanoparticle content is 2%, the cumulative hydrolysis amount of the coating is 0.6 mg / cm² within 60 days, demonstrating a suitable hydrolysis rate and long-lasting self-polishing and anti-fouling ability. 3. Stable surface properties: After being soaked in seawater, it still maintains low surface energy (20–30 mJ / m²) and high contact angle, and its surface chemical properties are stable, which is beneficial for inhibiting bioattachment; 4. Excellent mechanical properties: Adhesion reaches grade 5B, shear strength is 14.08 MPa, good wear resistance and impact resistance, and SiO2 nanoparticles significantly improve coating hardness and durability; 5. Highly effective against bioattachment: It significantly inhibits protein adsorption, with an inhibition rate of up to 33.4% against Chlorella, and exhibits dose-dependent antibacterial properties, with an inhibition rate of up to 99% against Escherichia coli and Staphylococcus aureus. 6. Environmental adaptability and long-lasting effect: It exhibits excellent antifouling performance in actual marine environments. After 35 days of sea trials, only sporadic biological attachment was observed in the NPDA2 coating, and its active ingredient arbutin has environmentally friendly and biodegradable characteristics.

[0056] In summary, the coating prepared by this patent has multiple functions such as self-polishing, high mechanical strength, environmental stability and efficient antibacterial properties. It is suitable for surface protection of facilities such as ships and offshore platforms, and has significant application potential and engineering value in harsh marine environments. It provides an effective material solution for achieving long-lasting and environmentally friendly marine antifouling.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin, characterized in that, Includes the following steps: S1: Synthesis of organic matrix material: Prepolymer NPDI was synthesized by using aminopropyl-terminated polydimethylsiloxane and hexamethylene diisocyanate. S2: Add hydroxyethyl acrylate to the prepolymer NPDI to obtain the polysiloxane-polyurethane acrylate polymer organic matrix material NPDA; S3: ZIF-8 / Arb powder was obtained by adsorbing arbutin Arb using ZIF-8; S4: The ZIF-8 / Arb powder obtained in step S3 is mixed with SiO2 to obtain a mixture ZIF-8 / Arb / SiO2. Then, ZIF-8 / Arb / SiO2 is added to the organic matrix material NPDA obtained in step S2 and mixed. Then, the coupling agent triethoxy-1H,1H,2H,2H-tridecylfluoro-N-octylsilane is added and the mixture is blended. After the reaction is completed, the resulting material is sprayed and dried at room temperature to obtain the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin.

2. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 1, characterized in that, In step S4, the mass ratio of ZIF-8 / Arb powder to SiO2 is 1:1; ZIF-8 / Arb / SiO2 is added to the organic matrix material NPDA at a ratio of 0.5-3% of the mass of the organic matrix material NPDA.

3. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 1, characterized in that, In step S4, the molar ratio of the mixture ZIF-8 / Arb / SiO2 to triethoxy-1H,1H,2H,2H-tetrafluoro-N-octylsilane is 1:1~1.5; The blending reaction was carried out under stirring conditions for 2-3 hours.

4. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 1, characterized in that, In step S1, the specific method for obtaining the prepolymer NPDI is as follows: aminopropyl-terminated polydimethylsiloxane is mixed with hexamethylene diisocyanate, tetrahydrofuran is added as a solvent, and the mixture is stirred and reacted for 2-3 hours at a reaction temperature of 50-60°C under nitrogen protection to obtain the prepolymer NPDI. The molar ratio of the aminopropyl-terminated polydimethylsiloxane to the hexamethylene diisocyanate is 1:1 to 1.

2.

5. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 1, characterized in that, In step S2, the molar ratio of the prepolymer NPDI to the hydroxyethyl acrylate is 1.2:

1.

6. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 1, characterized in that, The specific steps of step S2 are as follows: The organic matrix material NPDA is prepared by adding hydroxyethyl acrylate to the prepolymer, and stirring the reaction in tetrahydrofuran solvent under nitrogen protection at a temperature of 50-60°C for 2-3 hours.

7. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 1, characterized in that, In step S3, the antifouling functional material ZIF-8 / Arb powder is prepared by the following method: 2-Methylimidazole and zinc nitrate hexahydrate were dissolved separately in a solvent and magnetically stirred until completely dissolved. The two solutions were then mixed and stirred at room temperature for 6 hours until the solution turned milky white. The milky white solution was then transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 60-80°C for 10-12 hours. After the reaction was completed, the solid product was separated, washed, dried, and ground to obtain ZIF-8 powder. ZIF-8 powder was placed in a PBS solution with an Arb concentration of 100 mg / mL and magnetically stirred for 30 min to complete adsorption. The resulting suspension was then centrifuged, washed, and dried to obtain ZIF-8 / Arb powder, a substance with antifouling function.

8. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 7, characterized in that, In step S3, the mass ratio of 2-methylimidazole to zinc nitrate hexahydrate is 1:2~2.

5.

9. The method for preparing the self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin according to claim 7, characterized in that, In step S3, the solvent is selected from either methanol or ethanol.

10. A self-polishing and anti-fouling nanocomposite coating empowered by the natural antibacterial agent arbutin, characterized in that, It is prepared by the preparation method described in claim 1.

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