N-substituted azo compound-based photoresponsive lubricity antibacterial antifouling paint as well as preparation method and application of N-substituted azo compound-based photoresponsive lubricity antibacterial antifouling paint

Abstract

The invention discloses a preparation method of a light response type lubricating antibacterial antifouling coating based on an N-substituted azo compound. The light response type lubricating antibacterial antifouling paint is mainly prepared by uniformly stirring an N-substituted azo-isocyanate prepolymer and a cyclodextrin modified polyol prepolymer, the N-substituted azo-isocyanate prepolymer is obtained by uniformly mixing dihydroxyl-terminated polydimethylsiloxane, isocyanate, an N-substituted azo compound and an organic tin catalyst in an organic solvent a and then reacting under certain conditions. The N-substituted azo compound serves as a bactericide, the bactericidal performance is remarkably enhanced through the synergistic effect of an N-substituent and an azo group of the N-substituted azo compound, meanwhile, azo serves as a photoresponse object of the coating, cis-isomerism and trans-isomerism changes can be generated under ultraviolet light emission, therefore, the subject-object connection effect with cyclodextrin is changed, movement of lubricating liquid in the coating is regulated and controlled, and the anti-corrosion performance of the coating is improved. The self-supplement of the lubricating liquid on the surface of the coating is realized, the service life of the coating is prolonged, and the antifouling property of the coating is improved.

Description

Technical Field

[0001] The present invention relates to the technology of marine antifouling coatings, and specifically relates to a preparation method and application of a light-responsive lubricating antibacterial antifouling coating based on N-substituted azo compounds. Background Art

[0002] With the rapid growth of emerging marine industries, the number of marine facilities such as ships has gradually increased. However, in the exploration of the ocean, the resistance caused by marine biofouling to the exploration, development, and utilization of marine resources cannot be ignored. It is reported that 80% of the frictional resistance of a ship during navigation comes from the hull surface. The attachment of fouling organisms will increase the surface roughness of the hull, increase the hull weight, and cause a significant increase in navigation resistance and fuel consumption. The existence of biofouling will also accelerate the corrosion of marine facilities, affect the normal operation of marine instruments and facilities, and cause huge economic losses.

[0003] Methods for solving marine biofouling include physical cleaning methods, electrochemical removal methods, and coating antifouling coatings, etc. Among them, coating antifouling coatings on the surface of marine facilities is a simple and effective method. Traditional marine antifouling coatings mostly kill attached organisms by releasing antifouling agents. Among them, organotin self-polishing coatings are representative. However, since tin-based antifouling agents can accumulate in organisms and have teratogenic effects, they pose a serious threat to marine organisms and have been prohibited from use since January 1, 2018.

[0004] In recent years, antifouling coatings that are environmentally friendly and combine multiple antifouling strategies have received extensive attention from people, and antifouling coatings with low surface energy and strong bactericidal properties are one of them. Compared with general low surface energy coatings, a lubricating layer with a dynamic response function can replenish lubricating fluid on the coating surface, improve the antifouling ability of the coating, and significantly reduce the attachment of biofouling. By synergistically combining low surface energy with multiple antifouling technologies, the antifouling goals of environmental protection, high efficiency, and energy saving can be better achieved.

[0005] Chinese Patent Application CN109021747A imitates the function of mucus secretion on the surface of shark skin, uses twice-modified talcum powder to modify methyl silicone oil as a suitable substance to simulate the mucus on the surface of shark skin, then selects urea-formaldehyde resin as the wall material for microencapsulation, and uses the slow-release effect of microcapsules to release the simulated mucus to achieve the prevention and control of marine organisms. In this technology, the modification of nano-silver on the surface of talcum powder endows the coating with excellent bactericidal properties and good antifouling effects. However, the microencapsulation technology used in this technology has a high preparation cost, and the slow-release effect relied on has a poor release effect in static seawater, and the antifouling strength and antifouling efficiency cannot be regulated.

[0006] Chinese Invention Patent CN115851097B synthesized a porous liquid with the property of photo-responsive release of environmentally friendly antifouling agents based on ZIF-8, and injected it as a lubricating liquid into an antifouling coating prepared from organosilicon polyurethane. It has the advantage of being responsive to external ultraviolet stimuli, being able to intelligently switch the antifouling mode as needed in both strong light and dark environments, improving the antifouling efficiency, reducing the waste of antifouling agents, and overcoming the problem that the antifouling performance of traditional lubricating liquid-injected antifouling coatings decreases after the surface lubricating layer is damaged by water flow. However, the synthesis of the ZIF-8-based porous liquid in this technology requires techniques such as freeze-drying, with complex steps and high costs, and the antifouling agent is only released under ultraviolet light irradiation, resulting in insufficient antifouling effect at night.

[0007] Chinese Invention Patent CN115851110B utilizes the photo-responsive reversible dimerization behavior of coumarin compounds to regulate the mobility of a coumarin-terminated polydimethylsiloxane lubricating liquid on the surface of a coumarin-modified organosilicon polyurethane matrix, and then adjusts the lubricating performance of the surface, enabling the coating to adjust the antifouling intensity as needed, reducing the loss of the lubricating liquid, and effectively improving the antifouling efficiency. However, the antibacterial and antifouling performance of the antifouling coating prepared by this technology comes from the coumarin-modified lubricating liquid, and the antifouling performance depends on the fouling desorption effect generated by the lubricating liquid, while the bactericidal ability is limited.

[0008] Chinese Invention Patent CN113150594B discloses an ultraviolet-responsive coumarin-controlled release and self-healing antifouling coating, which has the advantages of controllable release of coumarin-based antifouling agents in response to external ultraviolet stimuli and self-healing of the coating, overcoming the problems of difficult release control of traditional antifouling agents in the antifouling coating and difficulty in repairing low-surface-energy antifouling coatings after damage. However, the coumarin antifouling agent released by this technology has high bioaccumulation and is not easily degraded, and long-term accumulation will damage the living environment of aquatic organisms. Summary of the Invention

[0009] Aiming at the problems of the prior art, the purpose of the present invention is to provide a preparation method of a photo-responsive lubricating antibacterial antifouling coating based on N-substituted azo compounds, which has significant bactericidal performance, has a response to ultraviolet light, can avoid the limited antibacterial and antifouling effect at night of the lubricating liquid-injected antifouling coating, cannot be adjusted according to environmental changes, and will not form microplastic pollution. The coating prepared from the obtained antifouling coating can adjust the surface lubricity as needed according to changes in the external environment, does not require additional bactericides to enhance the antifouling effect, and has strong antibacterial effects under both light and dark conditions.

[0010] Another object of the present invention is to provide the application of the photo-responsive lubricating antibacterial antifouling coating based on N-substituted azo compounds in the preparation of surface coatings for ocean engineering equipment.

[0011] In order to achieve the object of the present invention, the present invention provides the following technical solutions:

[0012] A light-responsive lubricating, antibacterial and antifouling coating based on N-substituted azo compounds, which is mainly obtained by uniformly stirring an N-substituted azo-isocyanate prepolymer and a cyclodextrin-modified polyol prepolymer; the N-substituted azo-isocyanate prepolymer is obtained by mixing a dihydroxy-terminated polydimethylsiloxane, an isocyanate, an N-substituted azo compound and an organotin catalyst in an organic solvent a, and reacting under an inert atmosphere at 60-80 °C; the N-substituted azo compound is obtained by reacting an alkyl aniline solution and a diazonium salt solution with a molar ratio of 0.8-1.2:1 at 0-5 °C and then purifying.

[0013] The cyclodextrin-modified polyol prepolymer is obtained by uniformly mixing a dihydroxy-terminated polydimethylsiloxane, an isocyanate and acetylated cyclodextrin in an organic solvent a, and reacting under an inert atmosphere at 60-70 °C.

[0014] To further achieve the object of the present invention, preferably, the light-responsive lubricating, antibacterial and antifouling coating further comprises a lubricating fluid, wherein the N-substituted azo-isocyanate prepolymer, the cyclodextrin-modified polyol prepolymer and the lubricating fluid are 10-50 parts, 10-50 parts and 0.1-20 parts respectively.

[0015] Preferably, the lubricating fluid is one or more of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, and methyl phenyl silicone oil; the viscosity of the lubricating fluid is ~10 mPa·s.

[0016] Preferably, by weight, the dihydroxy-terminated polydimethylsiloxane, the isocyanate, the N-substituted azo compound, the organotin catalyst and the organic solvent a are 5-25 parts, 1-5 parts, 1-3 parts, 0.05-0.1 part and 10-100 parts respectively; the mass ratio of the N,N-dihydroxyalkyl aniline to the organic solvent b is (2-10):(10-100).

[0017] The alkyl aniline solution is obtained by dissolving N,N-dihydroxyalkyl aniline in an organic solvent b, adjusting the pH to 5-7, and then cooling.

[0018] The diazonium salt solution is obtained by reacting aniline and sodium nitrite with a molar ratio of (0.7-1.2):1 dissolved in 0.5-2 mol / L hydrochloric acid at 0-5 °C for 0.5-1 h.

[0019] By weight, the amounts of the dihydroxy-terminated polydimethylsiloxane, the isocyanate, the acetylated cyclodextrin and the organic solvent a are 5-25 parts, 1-5 parts, 4-8 parts and 10-100 parts respectively.

[0020] Preferably, the N,N-dihydroxyalkyl aniline is one or more of N,N-dihydroxyethyl aniline, N,N-bis(2-hydroxyethyl)-3-chloroaniline, N,N-bis(2-hydroxypropyl) aniline, and N-ethyl-N-hydroxyethyl aniline; the weight-average molecular weight of the dihydroxy-terminated polydimethylsiloxane is 1000 to 10000;

[0021] The isocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and triphenylmethane triisocyanate.

[0022] Preferably, the organotin catalyst is one or more of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dipentanoate, and dibutyltin acetoacetate;

[0023] The acetylated cyclodextrin is one or more of acetylated α-cyclodextrin, acetylated β-cyclodextrin, and acetylated γ-cyclodextrin;

[0024] The organic solvent a is one or more of tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and xylene;

[0025] The organic solvent b is one or more of ethanol, ether, ethyl acetate, acetone, dichloroethane, and trichloroethane.

[0026] Preferably, the inert gas is an atmosphere formed by one of nitrogen or an inert gas;

[0027] The reaction time under the condition of 60 to 80 °C is 2 to 4 h; the reaction time at 0 to 5 °C is 1 to 2 h; the actual reaction time under the condition of 60 to 70 °C is 2 to 4 h;

[0028] The purification is to wash the product with deionized water while it is cold after the reaction at 0 to 5 °C, and then filter and dry it by suction;

[0029] The preparation method of the N-substituted azo compound-based photo-responsive lubricating antibacterial and antifouling coating includes the following steps:

[0030] 1) Dissolve N,N-dihydroxyalkyl aniline in organic solvent b, adjust the pH to 5 to 7, and then cool to obtain an alkyl aniline solution; react the alkyl aniline solution with a diazonium salt solution at a molar ratio of (0.8 to 1.2):1 at 0 to 5 °C, and then purify to obtain an N-substituted azo compound;

[0031] 2) Mix the dihydroxy-terminated polydimethylsiloxane, isocyanate, N-substituted azo compound, and organotin catalyst in organic solvent a, and react under an inert atmosphere at 60 to 80 °C to obtain an N-substituted azo-isocyanate prepolymer;

[0032] 3) After uniformly mixing the dihydroxy-terminated polydimethylsiloxane, isocyanate, and acetylated cyclodextrin in organic solvent a, react to obtain a cyclodextrin-modified polyol prepolymer under an inert atmosphere at 60-70 °C.

[0033] 4) After uniformly stirring the N-substituted azo-isocyanate prepolymer and the cyclodextrin-modified polyol prepolymer, a light-responsive lubricating antibacterial and antifouling coating is obtained.

[0034] Application of the light-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds in preparing the surface coating of ocean engineering equipment.

[0035] Preferably, the wet film coating thickness of the coating is 100-1000 μm; the coating is air-dried at room temperature.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] 1) The N-substituted azo compound designed and synthesized in the present invention is used as a bactericide. By the synergistic effect of the N-substituent and the azo group, the reduction ability of the compound is enhanced, endowing the coating with excellent bactericidal performance, so that the coating does not require additional bactericides to enhance the antifouling effect, and has a strong antibacterial effect under both light or dark conditions, and is not affected by the environment.

[0038] 2) For the antifouling coating prepared in the present invention, the initial coating has a stable trans-azobenzene structure, which turns into cis when exposed to ultraviolet light, realizing the supramolecular self-assembly to disassembly process of the azobenzene guest and the cyclodextrin host, and this process is reversible. Thereby, the mobility of the coating polymer chains is adjusted, and then the movement of the lubricating fluid is adjusted to form a dynamic lubricating layer on the coating surface, enabling the coating to adjust the antifouling intensity according to environmental changes and effectively improving the antifouling efficiency.

[0039] 3) The antifouling coating prepared in the present invention does not need to release antifouling agents into the environment to achieve the antifouling effect, prolongs the service life of the coating, and also avoids the microplastic pollution that traditional antifouling coatings may cause to the marine environment. Description of the Drawings

[0040] Figure 1 1H NMR spectrum of N,N-di(hydroxyethyl)azobenzene prepared in Example 1.

[0041] Figure 2 Infrared spectra of the N-substituted azo compound (N-Azo), N-substituted azo-isocyanate prepolymer (N-AzoPU), cyclodextrin-modified polyol prepolymer (Ac-α-CDPU), acetylated cyclodextrin (Ac-α-CD), and the prepared coating (Azo&CDPU) prepared in Example 1.

[0042] Figure 3 The following are the water contact angle diagrams of the coatings obtained in Examples 1-5 of the present invention after being irradiated with visible light (VL) and ultraviolet light (UV). Among them, VL-a, VL-b, VL-c, VL-d, and VL-e correspond to the test results of Examples 1-5 under visible light, and UV-a, UV-b, UV-c, UV-d, and UV-e correspond to the test results of Examples 1-5 under ultraviolet light.

[0043] Figure 4 The following is the result diagram of the anti-Escherichia coli of the coatings obtained in Examples 1-5 and Comparative Examples 1-2 of the present invention.

[0044] Figure 5 The following is the result diagram of the anti-Staphylococcus aureus of the coatings obtained in Examples 1-5 and Comparative Examples 1-2 of the present invention. Detailed implementation manners

[0045] To better understand the present invention, the following further illustrates the present invention in conjunction with the accompanying drawings and embodiments. However, the scope claimed by the present invention is not limited to the scope expressed in the embodiments.

[0046] The object of the present invention is to provide a coating with significant bactericidal performance, which has a response to ultraviolet light, can avoid the problem that the antibacterial and antifouling effect of the lubricating fluid injection type antifouling coating at night is limited and cannot be adjusted according to environmental changes, and will not form microplastic pollution. Based on this object, a photo-responsive lubricating antibacterial antifouling coating based on N-substituted azo compounds provided by the present invention is mainly obtained by uniformly stirring an N-substituted azo-isocyanate prepolymer and a cyclodextrin-modified polyol prepolymer; the N-substituted azo-isocyanate prepolymer is obtained by mixing a dihydroxy-terminated polydimethylsiloxane, an isocyanate, an N-substituted azo compound, and an organotin catalyst in an organic solvent a and reacting under an inert atmosphere at 60-80 °C; the N-substituted azo compound is obtained by reacting an alkyl aniline solution and a diazonium salt solution with a molar ratio of 0.8-1.2:1 at 0-5 °C and then purifying; the cyclodextrin-modified polyol prepolymer is obtained by uniformly mixing a dihydroxy-terminated polydimethylsiloxane, an isocyanate, and acetylated cyclodextrin in an organic solvent a and reacting under an inert atmosphere at 60-70 °C.

[0047] In the above technical solution, the light-responsive lubricating antibacterial and antifouling coating of the present invention uses azo derivatives as bactericides and has remarkable antibacterial properties. Its bactericidal effect mainly stems from the reduction reaction of the azo bond, which can generate toxic aromatic amines to effectively kill bacteria. In addition, by introducing tertiary amine as a substituent in the N-substituted azo compound, the tertiary amine can further form an amino cation, endowing the coating with cationic bactericidal properties. The synergistic effect of this N-substituent and the azo group can interfere with the metabolic process of microbial cells, destroy the structure and permeability of the cell membrane, and induce an oxidative stress response inside the cell, resulting in damage to biological macromolecules (such as proteins, DNA, etc.) inside the cell, thereby enabling the coating to exhibit excellent antibacterial properties.

[0048] Meanwhile, the present invention utilizes the light-responsive characteristics of azobenzene compounds to achieve intelligent regulation of the coating. At room temperature, the azo group exists in a more thermally stable trans configuration. When irradiated with ultraviolet light, the azo group absorbs the ultraviolet light and the molecule jumps from the ground state of the trans form to the excited state, overcoming the energy barrier of the isomerization reaction to achieve the isomerization transformation from trans to cis. Under visible light irradiation, the cis-configured azobenzene compounds can be re-converted to the trans configuration, thus realizing the reversible cycle of azobenzene isomerization. This light-responsive characteristic provides a basis for the dynamic performance regulation of the coating.

[0049] On the other hand, the present invention utilizes the special structure of cyclodextrin and its host-guest interaction. Cyclodextrin is a cyclic polysaccharide molecule composed of 6-8 D-glucose units. Its unique hydrophobic cavity provides sites for binding with many model substrates, enabling it to recognize a variety of guest molecules and form host-guest complexes through non-covalent interactions. Based on this kinetic and reversible binding property, the cyclodextrin unit can selectively recognize and bind specific molecules according to the size matching principle, thereby further enhancing the functionality of the coating.

[0050] Based on the above three aspects of characteristics, the present invention uses the designed and synthesized N-substituted azo compound as the light-responsive guest and cyclodextrin as the supramolecular interaction host, respectively synthesizes N-substituted azo-isocyanate prepolymer and cyclodextrin-modified polyol prepolymer. By changing the intensity of external ultraviolet / visible light, the cis-trans structure change of azo is realized, and the relative movement of the cyclodextrin host and the azobenzene guest is changed to achieve the movement of polymer segments, thereby adjusting the exudation of the lubricating fluid in the coating and achieving the effect of responsive dynamic antifouling.

[0051] As a preferred technical solution, the N-substituted azo-isocyanate prepolymer and the cyclodextrin-modified polyol prepolymer of the present invention further include a lubricating fluid, and the lubricating fluid is selected from one or more of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, and methyl phenyl silicone oil; preferably, the viscosity of the lubricating fluid is ~10 mPa·s. In the trans state, the benzene ring of azobenzene is inserted into the cavity of cyclodextrin to form a supramolecular complex. In the cis state, due to the steric hindrance of the azo structure, it cannot bind to cyclodextrin. Thus, the movement of polymer segments is achieved through the relative movement of the cyclodextrin host and the azobenzene guest, and further, the exudation of the lubricating fluid in the coating is adjusted to achieve the effect of responsive dynamic antifouling. The coating added with the lubricant can not only prevent fouling by adjusting the movement of the lubricating fluid according to the ultraviolet response conditions, but also has a strong bactericidal effect itself.

[0052] The light-responsive lubricating antibacterial antifouling coating of the present invention mainly lies in the synthesis of the N-substituted azo-isocyanate prepolymer and the cyclodextrin-modified polyol prepolymer, and a coating is formed by mixing and reacting. As for the dosages of the N-substituted azo-isocyanate prepolymer, the cyclodextrin-modified polyol prepolymer and / or the lubricating fluid; the dosages of the dihydroxy-terminated polydimethylsiloxane, isocyanate, N-substituted azo compound, organotin catalyst and organic solvent a in the synthesis of the N-substituted azo-isocyanate prepolymer, and the dosages of the dihydroxy-terminated polydimethylsiloxane, isocyanate and acetylated cyclodextrin in the synthesis of the cyclodextrin-modified polyol prepolymer in the organic solvent a can be obtained through tests according to the purpose of the present invention.

[0053] The alkyl aniline solution in the present invention is also involved in the prior art. The present invention preferably obtains it by dissolving N,N-dihydroxyalkyl aniline in an organic solvent b, adjusting the pH to 5-7, and then cooling.

[0054] The diazonium salt solution already exists in the prior art. The present invention preferably obtains it by reacting aniline and sodium nitrite with a molar ratio of (0.7-1.2):1 dissolved in 0.5-2 mol / L hydrochloric acid at 0-5 °C for 0.5-1 h.

[0055] Among the raw materials, N,N-dihydroxyalkyl aniline, isocyanate, organotin catalyst, and acetylated cyclodextrin are all conventional selections in the art. In the present invention, N,N-dihydroxyalkyl aniline is preferably one or more of N,N-dihydroxyethyl aniline, N,N-bis(2-hydroxyethyl)-3-chloroaniline, N,N-bis(2-hydroxypropyl) aniline, and N-ethyl-N-hydroxyethyl aniline; the weight-average molecular weight of the dihydroxy-terminated polydimethylsiloxane is preferably 1000-10000; the isocyanate is preferably one or more of hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and triphenylmethane triisocyanate. The organotin catalyst is preferably one or more of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dipentanoate, and dibutyltin acetoacetate; the acetylated cyclodextrin is preferably one or more of acetylated α-cyclodextrin, acetylated β-cyclodextrin, and acetylated γ-cyclodextrin;

[0056] In the present invention, organic solvents a and b are mainly selected based on the solubility of the solvents. According to the dissolution object, the present invention preferably selects organic solvent a as one or more of tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and xylene; organic solvent b is one or more of ethanol, ether, ethyl acetate, acetone, dichloroethane, and trichloroethane.

[0057] According to the purpose of the present invention, the light-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds of the present invention is mainly used for preparing the surface coating of ocean engineering equipment. The wet film coating thickness of the preferred coating is 100-1000 μm; the coating is air-dried at room temperature.

[0058] It should be noted that although an organotin catalyst is used in the preparation process of the coating of the present invention, it is only used as a catalyst. Compared with the traditional prohibited tin-based antifouling agent coating, the dosage is extremely small, and it is not easily released in the coating, and the influence generated can be ignored.

[0059] Example 1

[0060] Dissolve 0.94 g of aniline in 30 mL of 1 mol / L hydrochloric acid solution, cool it at 0-5 °C, and then slowly dropwise add 10 mL of 1.1 mol / L sodium nitrite solution thereto, and react for 0.5 h at 0-5 °C to obtain a diazonium salt solution; take 2.72 g of N,N-dihydroxyethyl aniline and dissolve it in an appropriate amount of ethanol, and adjust the pH to 6 with acetic acid buffer solution to obtain an alkyl aniline solution; slowly dropwise add the alkyl aniline solution to the diazonium solution, react at 0-5 °C for 1 h, wash the product with deionized water while it is cold, and after suction filtration and drying, obtain N-substituted azo compound N,N-dihydroxyethyl azobenzene, and its nuclear magnetic hydrogen spectrum is as follows Figure 1As shown. It can be seen from the figure that the signal peaks of the compound at δ = 7.89, 7.43, and 6.78 ppm are the signal peaks of Ar-H, and the signal peaks at δ = 3.83 and 3.54 ppm are the signal peaks of -N-CH2- and -CH2-, indicating the successful preparation of N,N-dihydroxyethyl azobenzene.

[0061] Add 20 mL of N,N-dimethylformamide and 2.5 g of triethylamine to a three-necked flask, stir evenly at 0 °C, add 1.47 g of acetyl chloride, and finally add 2.55 g of α-cyclodextrin and react at 0 °C for 1 h, then react at room temperature for 24 h. After the reaction is completed, add a large amount of acetone to precipitate the product, filter by suction, and dry to obtain acetylated α-cyclodextrin.

[0062] Add 9 g of tetrahydrofuran, 1.92 g of isophorone diisocyanate (IPDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) to a three-necked flask, introduce nitrogen, heat to 75 °C, and react under nitrogen protection for 4 h to obtain IPDI-PDMS; add 9 g of tetrahydrofuran, 1.02 g of hexamethylene diisocyanate (HDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) to a three-necked flask, introduce nitrogen, heat to 65 °C, and react under nitrogen protection for 4 h to obtain HDI-PDMS.

[0063] Add 3 g of tetrahydrofuran and 1.25 g of IPDI-PDMS to a three-necked flask and stir evenly, then add 0.02 g of dibutyltin dilaurate and 0.143 g of N,N-dihydroxyethyl azobenzene, introduce nitrogen, and react at 60 °C for 2 h to obtain N-substituted azo-isocyanate prepolymer (A-1). Add 3 mL of N,N-dimethylformamide and 1 g of HDI-PDMS to a three-necked flask and stir evenly, then add 0.45 g of acetylated α-cyclodextrin, introduce nitrogen, and react at 70 °C for 2 h to obtain cyclodextrin-modified polyol prepolymer (B-1).

[0064] Figure 2 Infrared spectra of the N-substituted azo compound (N-Azo), N-substituted azo-isocyanate prepolymer (N-AzoPU), acetylated cyclodextrin (Ac-α-CD), cyclodextrin-modified polyol prepolymer (Ac-α-CDPU), and the prepared coating (Azo&CDPU) prepared in Example 1.

[0065] Take 1 mL of A-1 and B-1 respectively and add them to a screw-cap vial, stir for 20 min to obtain a photo-responsive lubricating antibacterial and antifouling coating. Scrape the coating onto a glass plate with a thickness of 150 μm and dry at room temperature to obtain an antifouling coating (C-1).

[0066] The infrared spectra of the N-substituted azo compound (N-Azo), N-substituted azo-isocyanate prepolymer (N-AzoPU), acetylated cyclodextrin (Ac-α-CD), cyclodextrin-modified polyol prepolymer (Ac-α-CDPU), and the prepared coating (Azo&CDPU) prepared above are as Figure 2 shown. The stretching vibration absorption peaks at 1142 cm-1 (-OH), 1513 cm-1 (-N=N-), 1594 cm-1 (Ar), and 2989 cm-1 to 2945 cm-1 (-CH2-) in Figure 2 also indicate the successful preparation of the N-substituted azo compound. And as can be seen from the figure, the appearance or enhancement of the signal peaks belonging to C-O, C-H, and C=O in the acetyl group functional group at 1247, 1398, and 1748 cm-1 respectively indicates the successful preparation of acetylated α-cyclodextrin. For the N-substituted azo-isocyanate prepolymer and the cyclodextrin-modified polyol prepolymer, the disappearance of the -NCO signal peak at 2250 cm -1 and the signal peaks at 1695 cm-1 (-NH-C=O), 1260 cm-1 (CH3-Si-CH3), and 1000 to 1100 cm-1 (-Si-O-Si-) indicate the successful polymerization of both.

[0067] Example 2

[0068] Dissolve 0.94 g of aniline in 30 mL of 1 mol / L hydrochloric acid solution, cool it at 0 - 5 °C, and then slowly dropwise add 10 mL of 1.1 mol / L sodium nitrite solution, and react for 1 h under the condition of 0 - 5 °C to obtain a diazonium salt solution; take 3.14 g of N,N-bis(2-hydroxypropyl)aniline and dissolve it in an appropriate amount of ether, and adjust the pH to 6.5 with acetate buffer solution to obtain an alkyl aniline solution; slowly dropwise add the alkyl aniline solution to the diazo solution, react for 2 h at 0 - 5 °C, wash the product with deionized water while it is cold, filter by suction, and dry to obtain the N-substituted azo compound N,N-bis(2-hydroxypropyl)azobenzene.

[0069] Add 20 mL of N,N-dimethylformamide and 2.5 g of triethylamine to a three-necked flask, stir evenly at 0 °C, add 1.72 g of acetyl chloride, and finally add 3 g of β-cyclodextrin and react at -5 °C for 1 h, then react at room temperature for 30 h. After the reaction is completed, add a large amount of dichloroethane to precipitate the product, filter by suction, and dry to obtain acetylated β-cyclodextrin.

[0070] 9 g of tetrahydrofuran, 1.92 g of isophorone diisocyanate (IPDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Argon was introduced, and the temperature was raised to 80 °C. After that, the reaction was carried out for 3 h under nitrogen protection to obtain IPDI-PDMS; 9 g of tetrahydrofuran, 1.05 g of hexamethylene diisocyanate (HDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Nitrogen was introduced, and the temperature was raised to 65 °C. After that, the reaction was carried out for 4 h under argon protection to obtain HDI-PDMS.

[0071] 3 g of tetrahydrofuran and 1.25 g of IPDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.02 dibutyltin diacetate and 0.15 g of N-substituted azo compound N,N-bis(2-hydroxypropyl)azobenzene were added. Helium was introduced, and the reaction was carried out at 60 °C for 2 h to obtain N-substituted azo-isocyanate prepolymer (A-2). 3 mL of N,N-dimethylformamide and 1 g of HDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.47 g of acetylated β-cyclodextrin was added. Helium was introduced, and the reaction was carried out at 70 °C for 2 h to obtain cyclodextrin-modified polyol prepolymer (B-2).

[0072] 1 mL of A-3 and B-3 were respectively taken and added to a screw-cap vial. Then, 200 μL of methyl silicone oil with a viscosity of about 10 mPa·s was added and stirred for 20 min to obtain a light-responsive lubricating antibacterial and antifouling coating. The coating was scrape-coated onto a glass plate with a thickness of 150 μm and dried at room temperature to obtain an antifouling coating (C-2).

[0073] Example 3

[0074] 0.94 g of aniline was dissolved in 30 mL of 1 mol / L hydrochloric acid solution and cooled at 0 - 5 °C. Then, 10 mL of 1.1 mol / L sodium nitrite solution was slowly added dropwise thereto, and the reaction was carried out at 0 - 5 °C for 1 h to obtain a diazonium salt solution; 3.24 g of N,N-bis(2-hydroxyethyl)-3-chloroaniline was dissolved in an appropriate amount of ethanol, and the pH was adjusted to 6 with an acetate buffer solution to obtain an alkyl aniline solution; the alkyl aniline solution was slowly added dropwise to the diazonium solution, and the reaction was carried out at 0 - 5 °C for 1 h. The product was washed with deionized water while it was cold, filtered by suction, and dried to obtain the N-substituted azo compound N,N-bis(2-hydroxyethyl)-3-chloroazobenzene.

[0075] 20 mL of N,N-dimethylformamide and 2.5 g of triethylamine were added to a three-necked flask and stirred evenly at 0 °C. 1.96 g of acetyl chloride was added, and finally 3.42 g of γ-cyclodextrin was added. The reaction was carried out at 4 °C for 1 h, and then at room temperature for 36 h. After the reaction was completed, a large amount of trichloroethane was added to precipitate the product. The product was filtered by suction and dried to obtain acetylated γ-cyclodextrin.

[0076] 9 g of N-methylpyrrolidone, 1.92 g of isophorone diisocyanate (IPDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Argon was introduced, and the temperature was raised to 75 °C. After that, the reaction was carried out for 4 h under argon protection to obtain IPDI-PDMS; 9 g of N-methylpyrrolidone, 1.5 g of diphenylmethane diisocyanate (MDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Argon was introduced, and the temperature was raised to 70 °C. After that, the reaction was carried out for 4 h under argon protection to obtain MDI-PDMS.

[0077] 3 g of tetrahydrofuran and 1.25 g of IPDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.025 g of dibutyltin dilaurate and 0.161 g of N-substituted azo compound N,N-bis(2-hydroxyethyl)-3-chloroazobenzene were added. Argon was introduced, and the reaction was carried out at 60 °C for 3 h to obtain an N-substituted azo-isocyanate prepolymer (A-3). 3 mL of N,N-dimethylformamide and 1.05 g of MDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.54 g of acetylated γ-cyclodextrin was added. Argon was introduced, and the reaction was carried out at 70 °C for 3 h to obtain a cyclodextrin-modified polyol prepolymer (B-3).

[0078] 1 mL of A-3 and 1 mL of B-3 were respectively taken and added to a screw-cap vial. Then, 300 μL of ethyl silicone oil with a viscosity of about 10 mPa·s was added and stirred for 20 min to obtain a photo-responsive lubricating antibacterial and antifouling coating. The coating was scrape-coated on a glass plate with a thickness of 150 μm and dried at room temperature to obtain an antifouling coating (C-3).

[0079] Example 4

[0080] 0.94 g of aniline was dissolved in 20 mL of 1.5 mol / L hydrochloric acid solution and cooled at 0 - 5 °C. Then, 10 mL of 1.1 mol / L sodium nitrite solution was slowly added dropwise thereto, and the reaction was carried out at 0 - 5 °C for 1 h to obtain a diazonium salt solution; 2.72 g of N,N-bis(2-hydroxyethyl)aniline was dissolved in an appropriate amount of ethanol, and the pH was adjusted to 6 with an acetate buffer solution to obtain an alkyl aniline solution; the alkyl aniline solution was slowly added dropwise to the diazonium solution, and the reaction was carried out at 0 - 5 °C for 2 h. The product was washed with deionized water while it was cold, filtered by suction, and dried to obtain an N-substituted azo compound N,N-bis(2-hydroxyethyl)azobenzene.

[0081] Acetylated β-cyclodextrin was prepared by the same method steps as in Example 2.

[0082] 9 g of tetrahydrofuran, 1.92 g of isophorone diisocyanate (IPDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Nitrogen was introduced, and the temperature was raised to 75 °C. After that, the reaction was carried out for 4 h under nitrogen protection to obtain IPDI-PDMS; 9 g of tetrahydrofuran, 1.5 g of diphenylmethane diisocyanate (MDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Nitrogen was introduced, and the temperature was raised to 70 °C. After that, the reaction was carried out for 4 h under nitrogen protection to obtain MDI-PDMS.

[0083] 3 g of tetrahydrofuran and 1.25 g of IPDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.02 g of dibutyltin diacetate and 0.143 g of N-substituted azo compound N,N-dihydroxyethyl azobenzene were added. Nitrogen was introduced, and the reaction was carried out at 60 °C for 3 h to obtain N-substituted azo-isocyanate prepolymer (A-4). 3 mL of N,N-dimethylformamide and 1.05 g of MDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.47 g of acetylated β-cyclodextrin was added. Nitrogen was introduced, and the reaction was carried out at 70 °C for 3 h to obtain cyclodextrin-modified polyol prepolymer (B-4).

[0084] 1 mL of A-4 and 1 mL of B-4 were respectively taken and added to a screw-cap vial. Then, 400 μL of phenyl silicone oil with a viscosity of about 15 mPa·s was added and stirred for 20 min to obtain a light-responsive lubricating antibacterial and antifouling coating. The coating was scrape-coated onto a glass plate with a thickness of 150 μm and dried at room temperature to obtain an antifouling coating (C-4).

[0085] Example 5

[0086] 0.94 g of aniline was dissolved in 15 mL of 2 mol / L hydrochloric acid solution and cooled at 0 - 5 °C. Then, 15 mL of 1.1 mol / L sodium nitrite solution was slowly added dropwise thereto, and the reaction was carried out at 0 - 5 °C for 1 h to obtain a diazonium salt solution; 2.72 g of N,N-dihydroxyethylaniline was dissolved in an appropriate amount of ethanol, and the pH was adjusted to 6.5 with an acetate buffer solution to obtain an alkyl aniline solution; the alkyl aniline solution was slowly added dropwise to the diazonium solution, and the reaction was carried out at 0 - 5 °C for 2 h. The product was washed with deionized water while it was cold, filtered by suction, and dried to obtain the N-substituted azo compound N,N-dihydroxyethyl azobenzene.

[0087] Acetylated α-cyclodextrin was obtained by the same method steps as in Example 1.

[0088] 9 g of tetrahydrofuran, 1.92 g of isophorone diisocyanate (IPDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Nitrogen was introduced, and the temperature was raised to 70 °C. After reacting for 4 h under nitrogen protection, IPDI-PDMS was obtained. 9 g of tetrahydrofuran, 1.02 g of hexamethylene diisocyanate (HDI), and 6 g of hydroxyl-terminated polydimethylsiloxane (HPT-PDMS) were added to a three-necked flask. Nitrogen was introduced, and the temperature was raised to 70 °C. After reacting for 3 h under nitrogen protection, HDI-PDMS was obtained.

[0089] 3 g of tetrahydrofuran and 5 g of IPDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.02 g of dibutyltin dilaurate and 0.143 g of N-substituted azo compound N,N-dihydroxyethyl azobenzene were added. Helium was introduced, and the reaction was carried out at 60 °C for 4 h to obtain an N-substituted azo-isocyanate prepolymer (A-5). 3 mL of N,N-dimethylacetamide and 2.5 g of HDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.45 g of acetylated α-cyclodextrin was added. Helium was introduced, and the reaction was carried out at 70 °C for 4 h to obtain a cyclodextrin-modified polyol prepolymer (B-5).

[0090] 1 mL of A-5 and B-5 were respectively taken and added to a screw-cap vial. Then, 300 μL of methylphenyl silicone oil with a viscosity of 10 mPa·s was added and stirred for 20 min to obtain a light-responsive lubricating antibacterial and antifouling coating. The coating was scrape-coated onto a glass plate with a thickness of 150 μm and dried at room temperature to obtain an antifouling coating (C-5).

[0091] Comparative Example 1: Without N-substituted azo compound

[0092] Acetylated α-cyclodextrin, IPDI-PDMS, and HDI-PDMS were obtained by the same method steps as in Example 1.

[0093] 3 g of tetrahydrofuran and 1.25 g of IPDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.02 g of dibutyltin dilaurate and 1 g of hydroxyl-terminated polydimethylsiloxane were added. Nitrogen was introduced, and the reaction was carried out at 60 °C for 2 h to obtain an organosilicon polyurethane main body (A-6). 3 mL of N,N-dimethylformamide and 1 g of HDI-PDMS were added to a three-necked flask and stirred evenly. Then, 0.45 g of acetylated α-cyclodextrin was added. Nitrogen was introduced, and the reaction was carried out at 70 °C for 2 h to obtain a cyclodextrin-modified polyol prepolymer (B-6).

[0094] 1 mL of A-6 and B-6 were respectively taken and added to a screw-cap vial and stirred for 20 min to obtain a lubricating antifouling coating. The coating was scrape-coated onto a glass plate with a thickness of 150 μm and dried at room temperature to obtain an antifouling coating (C-6).

[0095] Comparative Example 2: Conventional antifouling coating

[0096] Add 9 mL of ethyl acetate, 10 mL of PDMS (Sylgard 184, purchased from Dow Corning Corporation), and 1 mL of curing agent (curing agent compatible with PDMS) into a beaker, and ultrasonicate for 20 min to stir evenly, and cool to room temperature to obtain a PDMS solution. Immerse a glass plate in the PDMS solution for 1 min and then take it out. After draining the excess solution, dry it in an oven at 120 °C for 10 min to obtain an antifouling coating (C-7).

[0097] The antifouling coatings obtained in Examples 1 to 5 above were respectively irradiated with 365 nm ultraviolet light for 4 h, and the water contact angles of the coatings under ultraviolet light (UV) and visible light (VL) were measured using a contact angle measuring instrument (JC2000C1, Shanghai); in addition, referring to the droplet sliding speed test method described in Chinese invention patent CN115851110B, by shooting a video of a droplet sliding from the top to the bottom of an inclined coating surface under an inclination angle of 30°, the sliding time of the droplet from the starting point to the bottom of the slope was measured using a timer and video editing software, and the sliding speed of the droplet was calculated according to the known slope path length, and the average value was taken as the droplet sliding speed to measure the droplet sliding speed on the coating surface before and after ultraviolet light irradiation. The results are shown in Table 1. Figure 3 The water contact angle diagrams of the coatings obtained in Examples 1 to 5 of the present invention after irradiation with visible light (VL) and ultraviolet light (UV) are shown, where VL-a, VL-b, VL-c, VL-d, VL-e correspond to the test results of Examples 1 to 5 under visible light, and UV-a, UV-b, UV-c, UV-d, UV-e correspond to the test results of Examples 1 to 5 under ultraviolet light.

[0098] Table 1 Antifouling performance of the coatings

[0099]

[0100] By comparing the contact angles of Examples 1 to 4 containing azo derivatives, it can be found that the water contact angle of the coating without silicone oil lubricant under visible light is 100°. As the content of silicone oil increases, the water contact angle of the coating gradually decreases. When the silicone oil increases to 15% by volume in Example 3, further increasing the silicone oil content in Example 4 hardly changes the water contact angle. In Examples 2 and 5, different ratios of the content of isocyanate groups (-NCO) and hydroxyl groups (-OH) on the polymer chain were selected in the coating. The results show that when the same content of silicone oil is added, the coatings obtained with different ratios of the content of isocyanate groups (-NCO) and hydroxyl groups (-OH) all have good lubricity on the coating surface.

[0101] Since there are no azo derivatives in Comparative Examples 1 and 2, there is no antifouling performance change due to the release of lubricating fluid caused by ultraviolet response. For Comparative Examples 1 to 5, the water contact angles under ultraviolet and visible light were measured. It was found that after ultraviolet light irradiation, the water contact angles of the coatings all decreased. This is because under ultraviolet light, azobenzene converts from the trans structure to the cis structure, and the azo group detaches, causing the movement of the polymer molecular chain. In the coating with added silicone oil, the movement of the polymer molecular chain makes the silicone oil move to the coating surface, reducing the water contact angle of the coating and improving the lubricity. The test results of the droplet sliding speed of the coating show that as the silicone oil content in the coating increases, the sliding speed of the droplets on the coating surface gradually increases, that is, the surface lubricity gradually increases. As the surface silicone oil content gradually saturates, the lubrication performance basically no longer increases. And after ultraviolet light treatment, the droplet sliding speed on the coating surface is greater than that under visible light, indicating that the coating of the present invention can adjust the surface lubricity as needed according to the UV response characteristics, enhance the antifouling efficiency in sufficient light conditions to cope with a higher degree of fouling under sunlight, and the antifouling performance weakens under the dark condition without light, achieving the effect of responsive antifouling according to environmental changes. Moreover, the coating of the present invention adheres well to the tested glass plates and tinplates and is not easy to fall off. After being soaked in salt water and solutions with different pH values for more than 48 hours, there is basically no corrosion, the lubricity of the coating is not affected, and the surface coating has good stability.

[0102] Antibacterial test: After sterilizing the antifouling coatings obtained in Examples 1 to 5 and Comparative Examples 1 to 2, 0.01 g of the sample was weighed and placed in a 24-well plate, and added to Escherichia coli and Staphylococcus aureus bacterial solutions with a concentration of 10 6 cfu / mL and cultured by shaking for 24 h. After diluting the bacterial solution to an appropriate multiple, it was spread on a plate and photographed and counted after culturing at 37 °C for 24 h. There were 2 parallel samples in each group. The results are as Figure 4 、 Figure 5 shown. Figure 4 In [Figure], a corresponds to the survival situation of Escherichia coli in the blank group without adding samples, and b, c, d, e, f correspond to the survival situations of Escherichia coli added with samples of Examples 1 to 5, respectively. g, h correspond to the survival situations of Escherichia coli added with samples of Comparative Examples 1 and 2, respectively. Figure 5 In [Figure], a corresponds to the survival situation of Staphylococcus aureus in the blank group without adding samples, and b, c, d, e, f correspond to the survival situations of Staphylococcus aureus added with samples of Examples 1 to 5, respectively. g, h correspond to the survival situations of Staphylococcus aureus added with samples of Comparative Examples 1 and 2, respectively.

[0103] From Figure 4 、 Figure 5It can be seen that the samples obtained in Examples 1 to 5 have significant antibacterial effects, indicating that even when there is no lubricity change with ultraviolet response in Example 1, there is still a strong antibacterial effect. In addition to preventing fouling by adjusting the movement of the lubricating fluid according to the ultraviolet response conditions, the coating with the added lubricant itself also has a strong bactericidal effect. Comparative Example 1 without N-substituted azo compounds and Comparative Example 2 of a common PDMS antifouling film basically have no antibacterial effect, proving that N-substituted azo compounds in the coating act as bactericides, endowing the coating with excellent bactericidal performance, regardless of whether it is daytime or nighttime. The antibacterial effect of the current lubricity antibacterial antifouling coating depends on the surface lubricating fluid, with weak lubricity and poor antibacterial effect under dark conditions. However, this coating does not require an additional bactericide to enhance the antifouling effect, is not affected by the environment, and has a strong antibacterial effect under both light and dark conditions. Moreover, this coating is different from the hydrolytic self-polishing marine antifouling coating and is not easily decomposed to cause microplastic pollution.

Claims

1. A light-responsive lubricating, antibacterial and antifouling coating based on N-substituted azo compounds, characterized in that, It is mainly obtained by uniformly stirring an N-substituted azo-isocyanate prepolymer and a cyclodextrin-modified polyol prepolymer; the N-substituted azo-isocyanate prepolymer is obtained by uniformly mixing a dihydroxy-terminated polydimethylsiloxane, an isocyanate, an N-substituted azo compound, and an organotin catalyst in an organic solvent a, and then reacting under an inert atmosphere at 60-80 °C; the N-substituted azo compound is obtained by reacting an alkyl aniline solution and a diazonium salt solution with a molar ratio of 0.8-1.2:1 at 0-5 °C and then purifying. The cyclodextrin-modified polyol prepolymer is obtained by uniformly mixing a dihydroxy-terminated polydimethylsiloxane, an isocyanate, and acetylated cyclodextrin in an organic solvent a, and then reacting under an inert atmosphere at 60-70 °C.

2. The photo-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 1, wherein: The photo-responsive lubricating antibacterial and antifouling coating further comprises a lubricating fluid. Among them, the N-substituted azo-isocyanate prepolymer, the cyclodextrin-modified polyol prepolymer, and the lubricating fluid are 10-50 parts, 10-50 parts, and 0.1-20 parts respectively.

3. The photo-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 2, characterized in that: The lubricating fluid is one or more of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, and methyl phenyl silicone oil; the viscosity of the lubricating fluid is ~10 mPa·s.

4. The photo-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 1, characterized in that: By weight, the dihydroxy-terminated polydimethylsiloxane, isocyanate, N-substituted azo compound, organotin catalyst, and organic solvent a are 5-25 parts, 1-5 parts, 1-3 parts, 0.05-0.1 parts, and 10-100 parts respectively; the mass ratio of N,N-dihydroxyalkyl aniline to organic solvent b is (2-10):(10-100). The alkyl aniline solution is obtained by dissolving N,N-dihydroxyalkyl aniline in an organic solvent b, adjusting the pH to 5-7, and then cooling. The diazonium salt solution is obtained by reacting aniline and sodium nitrite with a molar ratio of (0.7-1.2):1 dissolved in 0.5-2 mol / L hydrochloric acid at 0-5 °C for 0.5-1 h. By weight, the amounts of the dihydroxy-terminated polydimethylsiloxane, isocyanate, acetylated cyclodextrin, and organic solvent a are 5-25 parts, 1-5 parts, 4-8 parts, and 10-100 parts respectively.

5. The photocatalytic lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 1, characterized in that: The N,N-dihydroxyalkyl aniline is one or more of N,N-dihydroxyethyl aniline, N,N-bis(2-hydroxyethyl)-3-chloroaniline, N,N-bis(2-hydroxypropyl) aniline, and N-ethyl-N-hydroxyethyl aniline; the weight-average molecular weight of the dihydroxy-terminated polydimethylsiloxane is 1000-10000. The isocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and triphenylmethane triisocyanate.

6. The photo-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 1, wherein: The organotin catalyst is one or more of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dipentanoate, and dibutyltin acetoacetate. The acetylated cyclodextrin is one or more of acetylated α-cyclodextrin, acetylated β-cyclodextrin, and acetylated γ-cyclodextrin. The organic solvent a is one or more of tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and xylene; The organic solvent b is one or more of ethanol, ether, ethyl acetate, acetone, dichloroethane, and trichloroethane.

7. The light-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 1, characterized in that: The inert gas is an atmosphere formed by nitrogen or one of the inert gases; The reaction time under the condition of 60-80 °C is 2-4 h; the reaction time under 0-5 °C is 1-2 h; the actual reaction time under the condition of 60-70 °C is 2-4 h; The purification is to wash the product with deionized water while it is still cold after the reaction at 0-5 °C, filter by suction, and dry.

8. The preparation method of the N-substituted azo compound-based photo-responsive lubricating antibacterial and antifouling coating according to claim 1, characterized in that It includes the following steps: 1) Dissolve N,N-dihydroxyalkyl aniline in organic solvent b, adjust the pH to 5-7, and then cool to obtain an alkyl aniline solution; react the alkyl aniline solution and the diazonium salt solution with a molar ratio of (0.8-1.2):1 at 0-5 °C, and then purify to obtain the N-substituted azo compound; 2) Mix bis-hydroxy-terminated polydimethylsiloxane, isocyanate, N-substituted azo compound, and organotin catalyst in organic solvent a, and react under an inert atmosphere at 60-80 °C to obtain an N-substituted azo-isocyanate prepolymer; 3) Mix bis-hydroxy-terminated polydimethylsiloxane, isocyanate, and acetylated cyclodextrin in organic solvent a uniformly, and react under an inert atmosphere at 60-70 °C to obtain a cyclodextrin-modified polyol prepolymer; 4) Stir the N-substituted azo-isocyanate prepolymer and the cyclodextrin-modified polyol prepolymer evenly to obtain a light-responsive lubricating antibacterial and antifouling coating.

9. Application of the light-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to any one of claims 1-8 in preparing a surface coating for marine engineering equipment.

10. Use of the light-responsive lubricating antibacterial and antifouling coating based on N-substituted azo compounds according to claim 9 in the preparation of a surface coating for ocean engineering equipment, characterized in that, The wet film coating thickness of the coating is 100-1000 μm; the coating is air-dried at room temperature.

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