A composite hydrogel marine antifouling coating and its preparation method and application

Abstract

The present invention discloses a composite hydrogel marine antifouling coating, its preparation method and application, belonging to the technical field of marine antifouling coatings. The structure of the composite hydrogel marine antifouling coating includes a hydrogel adhesion layer and a metal-polyphenol network functional layer; wherein, the hydrogel adhesion layer is a Kevlar hydrogel; the metal-polyphenol network functional layer includes a polycaffeic acid hydrogel layer chelated with copper ions. Based on the Kevlar hydrogel adhesion layer, the present invention combines the synergistic antifouling effect of polycaffeic acid and metal ion copper ions. The prepared composite hydrogel marine antifouling coating is not only environmentally friendly, but also has excellent antifouling performance against proteins, bacteria and algae.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine antifouling coatings, and particularly relates to a composite hydrogel marine antifouling coating, a preparation method thereof and an application thereof. Background Art

[0002] Marine biofouling refers to the adverse accumulation of microorganisms, algae and animals on the surface of structures immersed in seawater, which not only increases the navigation resistance of ships, accelerates metal corrosion, increases operating costs, etc., but also causes an increase in greenhouse gas emissions. Marine biofouling has become a key problem restricting the development of the marine industry.

[0003] At present, coating antifouling coatings on the surfaces of ships and marine facilities and equipment is the most effective measure to address the above problems. Traditional antifouling coatings are mainly organotin-based antifouling coatings. However, such coatings are highly toxic to organisms, violating the concept of green environmental protection. Therefore, developing highly efficient and green environmental protection antifouling materials has become a new challenge.

[0004] Inspired by the epidermal mucus of fish and amphibians such as frogs, the main component of epidermal mucus is a natural hydrogel, which has a network topology structure and associative interactions. The hydrogel is soft and hydrophilic, and a hydration layer will be formed on the surface under the induction of hydrogen bonds and electrostatic interactions. This hydration layer forms a physical barrier to marine biofouling, thereby playing an anti-adhesion function.

[0005] Benefiting from the inspiration of mussel adhesion, catechol-based coatings represented by dopamine have received extensive attention in recent years. Metal-polyphenol networks have the characteristics of rapid preparation, general applicability and biocompatibility based on the coordination between phenolic ligands and metal ions. Polyphenols usually play a synergistic antifouling role with metal ions. Therefore, there is an urgent need to find new green polyphenol compounds to fabricate marine antifouling coatings with excellent anti-biofouling performance through the strategy of constructing metal-polyphenol networks. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite hydrogel marine antifouling coating, a preparation method thereof and an application thereof. By forming a polycaffeic acid hydrogel coating on the surface of Kevlar hydrogel and further chelating copper ions, an anti-pollution coating that can hinder the attachment of microorganisms, animals and plants and alleviate the occurrence of pollution phenomena is obtained.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention: provides a composite hydrogel marine antifouling coating, the structure of which includes a hydrogel adhesion layer and a metal-polyphenol network functional layer; the hydrogel adhesion layer is Kevlar hydrogel; the metal-polyphenol network functional layer includes a polycaffeic acid hydrogel layer chelated with copper ions.

[0009] The second technical solution of the present invention: Provide a preparation method of the above-mentioned composite hydrogel marine antifouling coating, including the following steps:

[0010] Dissolve Kevlar fiber in a solvent, coat the obtained solution system on a substrate, and use water for solvent replacement to obtain a Kevlar hydrogel layer;

[0011] Immerse the Kevlar hydrogel layer in a mixed solution containing caffeic acid for oxidative polymerization to form a polycaffeic acid hydrogel layer on the surface of the Kevlar hydrogel layer;

[0012] Immerse the polycaffeic acid hydrogel layer in a solution containing copper ions to prepare the composite hydrogel marine antifouling coating.

[0013] Preferably, in the solution system in which Kevlar fiber is dissolved, the solvent is a mixed solution of aqueous KOH solution and dimethyl sulfoxide, and the concentration of Kevlar fiber is 0.02 g / mL.

[0014] Preferably, in the mixed solution containing caffeic acid, the concentration of caffeic acid is 2 - 8 mg / mL, the solvent is Tirs-HCl buffer solution, and it also contains a catalyst and a crosslinking agent.

[0015] More preferably, the catalyst is ammonium persulfate; the crosslinking agent is ethylenediamine.

[0016] More preferably, the concentration of ammonium persulfate is 1 mg / mL; the concentration of ethylenediamine is 0.075 vol.%.

[0017] Preferably, the time for oxidative polymerization is 2 - 12 h.

[0018] Preferably, in the solution containing copper ions, the concentration of copper ions is 0.5 mg / mL.

[0019] Preferably, the time for the polycaffeic acid hydrogel layer to be soaked in the solution containing copper ions is 2 h.

[0020] The third technical solution of the present invention: Provide an application of the above-mentioned composite hydrogel marine antifouling coating in a ship surface coating.

[0021] In the preparation process provided by the present invention, first, Kevlar fibers are dissolved, and Kevlar hydrogel is prepared by a phase inversion method. A hydrogel adhesion layer (Kevlar hydrogel) is coated on the surface of the substrate by a doctor blade method. Due to the hydrogen bond interaction between the molecular chains of Kevlar fibers, the Kevlar hydrogel has advantages such as being strong, acid and alkali resistant, etc. Secondly, the natural phenolic acid compound caffeic acid from plants accelerates the oxidative polymerization reaction in the presence of ammonium persulfate and ethylenediamine, and spontaneously forms a polycaffeic acid hydrogel coating (H-PCA) on the surface of the Kevlar hydrogel. On the one hand, the caffeic acid structure contains carboxyl and hydroxyl groups, which tightly bind water molecules through ionization and hydration on the coating surface, generating a physical barrier, increasing the hydrophilicity of the coating surface, and endowing the coating with the ability to resist marine biofouling. On the other hand, through the coordination of the catechol structure of caffeic acid, metal ion bactericide copper ions are chelated to construct a metal-polyphenol network, forming a copper ion chelated polycaffeic acid hydrogel coating (H-PCA / Cu 2+ ), and polycaffeic acid and metal ion copper ions play a synergistic antifouling role, improving the anti-pollution ability of the coating against proteins, bacteria and algae.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] Based on a green antifouling strategy, the present invention prepares a hydrophilic composite hydrogel antifouling coating. Due to the ionization and hydration on the coating surface, a dense hydration layer can be formed on the coating surface, which is equivalent to a physical barrier, hindering the attachment of microorganisms, animals and plants, alleviating the occurrence of pollution, and improving the anti-pollution ability of the coating; it provides a new design idea and technical basis for the development of long-lasting, durable and green broad-spectrum antifouling coatings.

[0024] The composite hydrogel antifouling coating prepared by the present invention combines the synergistic antibacterial effect exerted by the metal-polyphenol network, and the antibacterial rate can reach more than 99%. Even after being treated with acid, alkali, high salt and mechanical abrasion, the antibacterial rate of the coating remains above 99%, proving that the coating has stable antibacterial performance.

[0025] The raw materials of the composite hydrogel antifouling coating prepared by the present invention are easily available, and the preparation process is simple and efficient. The hydrogel adhesion layer is coated on the surface of the substrate by a simple doctor blade method; the metal-polyphenol network functional layer is spontaneously deposited on the coating surface by an impregnation method, and can be applied to different substrates, with universality and easy to promote. Description of the Drawings

[0026] Figure 1 SEM images of the composite hydrogel marine antifouling coating prepared in Example 1 and the coating during the preparation process. Among them, A is the SEM image of the Kevlar hydrogel adhesion layer, B is the SEM image when the polycaffeic acid hydrogel layer is polymerized, and C is the SEM image of the final composite hydrogel marine antifouling coating.

[0027] Figure 2 The water contact angles of the composite hydrogel marine antifouling coatings prepared in Examples 1-3. Among them, A is the water contact angle of the composite hydrogel marine antifouling coatings prepared in Examples 1 and 2 with different caffeic acid concentrations, and B is the water contact angle of the composite hydrogel marine antifouling coatings prepared in Examples 1 and 3 with different polymerization times.

[0028] Figure 3 The antifouling performance of Example 1 at different stages of preparing the composite hydrogel marine antifouling coating.

[0029] Figure 4 The antibacterial culture pictures of Example 1 at different stages of preparing the composite hydrogel marine antifouling coating, as well as the antibacterial culture pictures of the final coating after being treated with acid, alkali, high-salt solution or mechanical abrasion.

[0030] Figure 5 The antibacterial properties of Example 1 against Escherichia coli and Staphylococcus aureus at different stages of preparing the composite hydrogel marine antifouling coating.

[0031] Figure 6 The anti-algal test results of Example 1 at different stages of preparing the composite hydrogel marine antifouling coating. Among them, A is the absorbance test result, and B is the calculated result of chlorophyll concentration. Detailed implementation manners

[0032] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention. It should be understood that the terms described in the present invention are only used to describe specific implementation manners and are not used to limit the present invention.

[0033] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention.

[0035] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, that is, they are meant to include but not limited to.

[0036] Example 1

[0037] Preparation of composite hydrogel marine antifouling coating:

[0038] (1) Preparation of Kevlar hydrogel adhesion layer: Take 1.2 g of Kevlar fiber and add it to a mixture of 60 mL of DMSO, 1.2 mL of water and 1.2 g of KOH. Stir at room temperature for 48 h. Let the obtained dark red solution stand overnight, and then pour the above solution onto the surface of 304 stainless steel. Use a spatula to scrape it to a thickness of about 100 μm, and immerse it in deionized water to form a hydrogel adhesion layer through phase inversion;

[0039] (2) Preparation of caffeic acid mixed solution: Dissolve 0.8 g of caffeic acid (4 mg / mL), 0.2 g of ammonium persulfate and 150 μL of ethylenediamine completely in 200 mL of Tirs-HCl buffer solution (50 mM, pH = 8.5) at 65 °C, and stir under air conditions to obtain a dark brown solution;

[0040] (3) Preparation of polycaffeic acid hydrogel layer: Immerse the Kevlar hydrogel adhesion layer prepared in step (1) into the caffeic acid mixed solution in step (2), react at room temperature for 8 h, and then take out the sample and rinse the residual solution on the surface with deionized water for standby;

[0041] (4) Preparation of copper ion chelated polycaffeic acid composite hydrogel layer: Transfer the polycaffeic acid hydrogel layer prepared in step (3) to an aqueous solution of copper sulfate pentahydrate at 2 mg / mL (Cu 2+ concentration is about 0.5 mg / mL), the reaction time is 2 h, and then take out the sample and wash it thoroughly with deionized water, and dry it at 45 °C to obtain the composite hydrogel marine antifouling coating.

[0042] The SEM images of the composite hydrogel marine antifouling coating prepared in Example 1 and the coating during the preparation process are shown in Figure 1 , where A is the SEM image of the Kevlar hydrogel adhesion layer, B is the SEM image when the polycaffeic acid hydrogel layer is polymerized, and C is the SEM image of the final composite hydrogel marine antifouling coating.

[0043] Example 2

[0044] Preparation of composite hydrogel marine antifouling coating:

[0045] Compared with Example 1, the difference is only that the caffeic acid concentrations in step (2) are configured to be 2 mg / mL, 6 mg / mL and 8 mg / mL respectively, and other conditions are the same as those in Example 1.

[0046] Example 3

[0047] Preparation of composite hydrogel marine antifouling coating:

[0048] Compared with Example 1, the only difference is that the reaction time in step (3) is adjusted to 2 h, 4 h, 6 h, 10 h, and 12 h respectively, and other conditions are the same as those in Example 1.

[0049] Application Example 1

[0050] Wettability test of the coating:

[0051] The water contact angles of the composite hydrogel marine antifouling coatings prepared in Examples 1-3 were measured by a goniometer (HARKE-SPCAX1S, China). Five points were randomly selected on the surface of each coating for testing, and the average value of the five measurements was taken as the contact angle value of the coating. The measurement results are as Figure 2 shown, where A is the water contact angle of the composite hydrogel marine antifouling coatings prepared in Examples 1 and 2 with different caffeic acid concentrations, and B is the water contact angle of the composite hydrogel marine antifouling coatings prepared in Examples 1 and 3 with different polymerization times. It can be seen from Figure 2 that a composite hydrogel coating with optimal hydrophilicity can be obtained by changing the amount of caffeic acid and the reaction time.

[0052] Application Example 2

[0053] Anti-protein adsorption performance test of the coating:

[0054] The antifouling performance of Example 1 at different stages of preparing the composite hydrogel marine antifouling coating was evaluated by bovine serum albumin (BSA) adsorption test. The size of the sample coating was 2 cm × 2 cm. The sample was immersed in BSA solution (4 mg·mL -1 ) for 24 hours, and then the sample was taken out and gently washed with PBS solution to remove the BSA with weak adhesion. Then the sample was vigorously rinsed with sterile water (4 mL) to elute the BSA firmly attached to the surface. The absorbance of BSA in the collected washing solution was measured at a wavelength of λ = 295 nm to represent the amount of BSA attached to the sample surface.

[0055] The measurement results are shown in Figure 3 , Figure 3 showing that the residual BSA on the surface of the substrate 304 stainless steel (304ss) was as high as 0.6387 ± 0.0411 mg·cm -2 , the residual BSA on the surface of the substrate coated with Kevlar hydrogel adhesion layer (Kevlarhydrogel) decreased slightly, to 0.4586 ± 0.0389 mg·cm -2 , and finally, the residual BSA on the surface of the composite hydrogel marine antifouling coating (H-PCA / Cu 2+ ) was only 0.0793 ± 0.0077 mg·cm -2, which is due to the strong interfacial hydration and surface charge effect (negatively charged surface) of the coating, strongly repelling BSA.

[0056] Application Example 3

[0057] Antibacterial performance test of the coating:

[0058] The dilution coating plate method was used to test the antibacterial performance of Example 1 against Escherichia coli and Staphylococcus aureus at different stages of preparing the composite hydrogel marine antifouling coating. The size of the sample coating was 3 cm × 3 cm. The sample and the diluted bacterial solution were co-cultured at 37 °C (Escherichia coli, Staphylococcus aureus) for 2 h. The surface of the sample was rinsed with 5 mL of physiological saline to obtain a bacterial suspension. A certain amount of the bacterial suspension was spread on a solid medium (each sample was spread in parallel 3 times), and cultured at 37 °C for 12 h. The colony counting method was used to calculate the number of colonies on the sample. The calculation formula is as follows:

[0059]

[0060] Where Rs is the antibacterial rate, N p and N E represent the average values of the number of colonies in the blank group and the sample group, respectively.

[0061] The antibacterial culture pictures of Example 1 at different stages of preparing the composite hydrogel marine antifouling coating, and the antibacterial culture pictures of the final coating after being treated with acid (pH = 2), alkali (pH = 12), high-salt solution (7 wt% NaCl) for 12 h, and mechanical abrasion are shown in Figure 4 , Figure 4 showing that the composite hydrogel marine antifouling coating (H-PCA / Cu 2+ ) exhibits excellent antibacterial performance against both Escherichia coli and Staphylococcus aureus, with an antibacterial rate reaching 99.9%; then after the coating is treated with acid (pH = 2), alkali (pH = 12), high-salt solution (7 wt% NaCl) for 12 h or through mechanical abrasion, the composite hydrogel marine antifouling coating still maintains an antibacterial rate of 99.9%, indicating that the composite hydrogel antifouling coating prepared by the present invention has stable antibacterial performance. Figure 5 is the antibacterial performance of Example 1 against Escherichia coli and Staphylococcus aureus at different stages of preparing the composite hydrogel marine antifouling coating.

[0062] Specific operation process of the mechanical friction experiment: Press a 50 g weight on the sample, place its coated surface face down on a standard sandpaper (CW 2000), and drag the sample in a straight line at a speed of 2 cm / s for 10 cm. This process is defined as one mechanical abrasion, and H-PCA / Cu 2+ is subjected to 100 times of mechanical abrasion.

[0063] Application Example 4

[0064] Anti-algal test of the coating:

[0065] Chlorella vulgaris and Phaeodactylum tricornutum were selected as experimental algae. The size of the sample coating was 3 cm × 3 cm. Using F / 2 medium and F / 2 + Si medium, under visible light LED irradiation (3000 Lux) at 21 °C, the algae were cultured for 7 days with a light / dark cycle of 14:10 hours. Each coating was immersed in 30 mL of diluted algae (about 105 cells / mL) and cultured for 7 days. On the one hand, the growth status of the algae was determined by measuring the absorbance at λ = 445 nm according to the standard curve; on the other hand, the sample coating was immersed in the diluted algal solution for 7 days, and the weakly adhered algae on the surface were gently washed with PBS solution, then the surface was thoroughly rinsed with 4 mL of sterile water to remove the algae attached to the surface. The rinsing solution was collected and mixed with an equal volume of acetone, and ultrasonicated for 15 min to extract chlorophyll. The absorbance was measured at λ = 647 nm according to the standard curve of the chlorophyll solution, and the chlorophyll concentration was calculated.

[0066] The anti-algal test results of Example 1 at different stages of preparing the composite hydrogel marine antifouling coating are shown in Figure 6 , where A is the absorbance test result and B is the chlorophyll concentration calculation result. As Figure 6 shown, there are significant differences in the growth and attachment of algae on different samples. The growth of algae can be inhibited by the action of Cu 2+ , and the hydration on the coating surface can avoid the attachment of algae. H-PCA / Cu 2+ exhibits excellent antifouling ability against algae.

[0067] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A composite hydrogel marine antifouling coating, characterized in that: The structure comprises a hydrogel adhesion layer and a metal-polyphenol network functional layer; the hydrogel adhesion layer is Kevlar hydrogel; and the metal-polyphenol network functional layer comprises a polycaffeic acid hydrogel layer chelated with copper ions.

2. A method for preparing the composite hydrogel marine antifouling coating according to claim 1, characterized in that: The following steps are involved: Dissolving Kevlar fiber in a solvent, coating the obtained solution system on a substrate, and replacing the solvent with water to obtain a Kevlar hydrogel layer; Immersing the Kevlar hydrogel layer in a mixed solution containing caffeic acid for oxidative polymerization to generate a polycaffeic acid hydrogel layer on the surface of the Kevlar hydrogel layer; The polycaffeic acid hydrogel layer is immersed in a solution containing copper ions to prepare the composite hydrogel marine antifouling coating.

3. The preparation method according to claim 2, characterized in that: In the solution system containing Kevlar fibers, the solvent is a mixed solution of KOH aqueous solution and dimethyl sulfoxide, and the concentration of Kevlar fibers is 0.02 g / mL.

4. The preparation method according to claim 2, characterized in that: In the mixed solution containing caffeic acid, the concentration of caffeic acid is 2-8 mg / mL, the solvent is Tirs-HCl buffer, and the mixed solution also contains a catalyst and a cross-linking agent.

5. The preparation method according to claim 4, characterized in that: The catalyst is ammonium persulfate; the cross-linking agent is ethylenediamine.

6. The preparation method according to claim 5, characterized in that: The concentration of the ammonium persulfate is 1 mg / mL; the concentration of the ethylenediamine is 0.075 vol.%.

7. The preparation method according to claim 2, characterized in that: The time of the oxidative polymerization is 2 to 12 hours.

8. The preparation method according to claim 2, characterized in that: In the copper ion-containing solution, the copper ion concentration is 0.5 mg / mL.

9. The preparation method according to claim 2, characterized in that: The polycaffeic acid hydrogel layer is immersed in the copper ion-containing solution for 2 hours.

10. Use of the composite hydrogel marine antifouling coating according to claim 1 in ship surface coating.

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