Modified polysilazane coating, modified polysilazane coating and preparation method and repairing method of modified polysilazane coating

Abstract

The invention belongs to the technical field of antifouling coatings, and particularly relates to a modified polysilazane coating, a modified polysilazane coating, a preparation method of the modified polysilazane coating and a repairing method of the modified polysilazane coating. According to the modified polysilazane coating provided by the invention, the polysilazane compound and the low-surface-energy compound are combined to construct a firm anti-attrition coating, the polymer brush monomer is grafted with the polymer brush on the surface of the anti-attrition coating to enhance the surface hydration lubrication and antifouling performance of the anti-attrition coating, and the rigid polysilazane is grafted with the low-surface-energy fluorine to endow the surface with low viscous resistance. The preparation method comprises the following steps: firstly, constructing a tough bottom layer taking polysilazane as a main body, and introducing active sites which can be subjected to multiple times of controllable surface-initiated polymerization on the surface of the tough bottom layer; the initially grafted polymer brush layer provides a first efficient anti-fouling defense line. And when the function of the polymer brush is degraded under long-term friction and abrasion in a marine environment, active sites reserved in the substrate are activated again, so that secondary grafting and even multiple grafting of the polymer brush can be realized, and the original antifouling property of the surface of the coating can be recovered.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of antifouling coatings, and particularly relates to a modified polysilazane coating, a modified polysilazane coating layer, and a preparation method and a repairing method thereof. BACKGROUND

[0002] Surface and interface science plays an important role in many industrial technologies, and the friction and wear of surfaces and the biofouling are long-standing and costly challenges. In marine engineering, biofouling can increase the roughness of the surface of a ship, increase the sailing resistance of the ship, and cause the fuel consumption to soar. In addition, biofouling can also cause the degradation of the surface coating of the ship, accelerate the corrosion of the metal structure, and affect the service life of the marine equipment. Traditional antifouling technology mainly relies on toxic agent release type antifouling paint containing organic tin, cuprous oxide and the like. However, while these toxic agents inhibit the fouling organisms, they also continuously accumulate in the marine environment, causing harm to non-target organisms and disrupting the ecological balance. Although the subsequently developed low-surface-energy antifouling coatings (such as organosilicon and fluoropolymer) are environmentally friendly, their “anti-adhesion” mechanism relies on high speed (shear force), and the antifouling effect is poor on equipment running at static or low speed, and their wear resistance is insufficient. Therefore, it is urgent to develop a coating system that has excellent antifouling performance and excellent wear resistance.

[0003] In recent years, the surface grafting polymer brush technology, especially the polyethylene glycol (PEG) or zwitterionic polymer (such as polysulfobetaine, PSBMA) brush, has shown great potential for environmentally friendly antifouling due to its ability to effectively repel the attachment of proteins and other marine organisms by forming a dense hydration layer. However, conventional polymer brushes are usually fixed on the substrate by “grafting to” or “grafting from” methods, and their interface connection is mostly physical adsorption or irreversible chemical bond. Once the polymer brush layer is damaged under long-term use or mechanical friction, its antifouling function will be permanently lost, and it cannot realize self-repairing or functional regeneration, which limits its application in marine environments that require long-term service. SUMMARY

[0004] Therefore, the present application provides a modified polysilazane coating, a modified polysilazane coating layer, and a preparation method and a repairing method thereof. The modified polysilazane coating layer provided by the present application has excellent antifouling and wear resistance, and can be repaired and functionally regenerated after the polymer brush layer is damaged, thereby significantly prolonging the overall service life of the coating.

[0005] To solve the above technical problems, the present application provides a modified polysilazane coating, which comprises independently packaged A material and B material; The A material comprises the following components in mass fraction: 5-30 parts of a polysilazane compound; Low surface energy compound 1~5 parts; First initiator 1~5 parts; Dispersing medium 50~80 parts; The low surface energy compound is prepared by free radical polymerization reaction of silane coupling agent, fluorine-containing polymerizable monomer, silicon-containing polymerizable monomer and second initiator; The B material includes polymer brush monomer, catalytic system, reducing catalyst and water; the catalytic system includes copper chloride and pentamethyl diethylene triamine.

[0006] Preferably, the fluorine-containing polymerizable monomer includes one or more of dodecafluoroheptyl methacrylate, 1H, 1H, 2H, 2H-perfluorooctyl acrylate, hexafluoropropylene, tetrafluoroethylene, trifluorochloroethylene, vinylidene fluoride, perfluoropolyether (meth) acrylate, trifluoroethyl methacrylate and hexafluoroisopropyl methacrylate; The silicon-containing polymerizable monomer includes one or more of vinyl trialkoxysilane, vinyl trimethoxysilane, divinyl silane derivative, allyl trimethoxysilane and methacryloyloxy propyl trimethoxysilane; The silane coupling agent includes one or more of γ-aminopropyl triethoxysilane, N-β- (aminoethyl) -γ-aminopropyl trimethoxysilane, γ- (2, 3-epoxypropoxy) propyl trimethoxysilane, γ- (methacryloyloxy) propyl trimethoxysilane, 3-mercaptopropyl triethoxysilane and γ-mercaptopropyl trimethoxysilane; The second initiator includes one or more of dibenzoyl peroxide, tert-butyl benzene peroxide, dicumyl peroxide, azobis isobutyronitrile and azobis isobutyrimidine hydrochloride.

[0007] Preferably, the molar ratio of the silane coupling agent, fluorine-containing polymerizable monomer and silicon-containing polymerizable monomer is 1:3~6:3~6; the content of the second initiator in the free radical polymerization reaction system is 1~5 mol%; The temperature of the free radical polymerization reaction is 65~75℃, and the time is 4~6h.

[0008] Preferably, the polysilazane compound includes one or more of methyl polysilazane, vinyl polysilazane, phenyl polysilazane, perhydrogen polysilazane, polysilaborazane, polyfluorosilazane and polyureasilazane; The first initiator is an initiator of atom transfer radical polymerization, and the first initiator includes 3-aminopropyl triethoxysilane-Br; The dispersing medium includes tetrahydrofuran or n-butyl ether.

[0009] Preferably, the polymer brush monomer includes zwitterionic monomer, positive ion monomer or anionic monomer. the zwitterionic monomer comprises one or more of 3-sulfopropyl methacrylate potassium salt, sulfobetaine methacrylate, methacryloyl ethyl sulfobetaine and dimethylaminoethyl methacrylate; the positive ion monomer comprises one or more of methacryloyloxyethyl trimethylammonium chloride, acryloyloxyethyl trimethylammonium chloride and dimethyl diallyl ammonium chloride; the anionic monomer comprises acrylic acid; the reducing catalyst comprises ascorbic acid; the mass ratio of the copper chloride and the volume of the pentamethyldiethylenetriamine is 7-9 mg:10 μL; the mass ratio of the polymer brush monomer and the water is 1.5-2.5:5; the volume ratio of the water and the pentamethyldiethylenetriamine is 5 mL:9-11 μL; the molar ratio of the reducing catalyst and the copper chloride is 9-11:1.

[0010] The application further provides a modified polysilazane coating, comprising a substrate and a polysilazane layer, and a polymer brush layer grafted to the surface of the polysilazane layer. The polysilazane layer is formed by the A material, and the polymer brush layer is formed by the B material.

[0011] Preferably, the substrate comprises glass, metal or polymer. The thickness of the polysilazane layer is 30-90 µm, and the thickness of the polymer brush layer is 30-90 µm.

[0012] Preferably, the method comprises the following steps: After coating the A material on the surface of the substrate, curing is performed to obtain a substrate containing a polysilazane layer; The substrate containing the polysilazane layer is immersed in the B material to perform an atom transfer radical polymerization reaction, thereby obtaining the modified polysilazane coating.

[0013] Preferably, before the coating, the method further comprises: performing plasma sputtering treatment on the substrate in an oxygen atmosphere. The curing temperature is 55-65 °C, and the curing time is 46-50 h. The atom transfer radical polymerization reaction time is 2-6 h.

[0014] The application further provides a method for repairing a modified polysilazane coating, comprising the following steps: The damaged modified polysilazane coating is re-immersed in the B material to perform an atom transfer radical polymerization reaction, thereby obtaining a repaired modified polysilazane coating.

[0015] The application provides a modified polysilazane coating, comprising independently packaged A material and B material; the A material comprises the following components in mass fraction: 5-30 parts of polysilazane compound, 1-5 parts of low surface energy compound, 1-5 parts of first initiator, 50-80 parts of dispersion medium; the low surface energy compound is prepared by free radical polymerization reaction of silane coupling agent, fluorine-containing polymerizable monomer, silicon-containing polymerizable monomer and second initiator; the B material comprises polymer brush monomer, catalytic system, reducing catalyst and water; the catalytic system comprises copper chloride and pentamethyldiethylenetriamine. The modified polysilazane coating provided by the application combines polysilazane compound and low surface energy compound to construct a strong friction-reducing coating, polymer brush monomer is grafted with polymer brush on the surface of the friction-reducing coating to enhance the surface hydration lubrication and antifouling performance, and rigid polysilazane grafted with low surface energy fluorine endows the surface with low viscous resistance; meanwhile, the hydrophilic modified polymer brush has stable hydration lubrication capacity and exhibits stable lubrication performance in a water environment.

[0016] The application further provides a modified polysilazane coating, comprising a substrate and a polysilazane layer which are stacked, and a polymer brush layer grafted on the surface of the polysilazane layer; the polysilazane layer is formed by the A material, and the polymer brush layer is formed by the B material. The application firstly constructs a strong and tough substrate mainly composed of polysilazane, and introduces active sites which can be used for multiple and controllable surface-initiated polymerization on the surface of the substrate; the initially grafted polymer brush layer provides the first efficient antifouling line. When the polymer brush functionally deteriorates under long-term friction and abrasion in a marine environment, the reserved active sites in the substrate are activated again, so that the polymer brush can be "secondarily grafted" or even "grafted multiple times", so that the surface of the coating restores its original antifouling performance. The design of "repeated grafting" solves the life bottleneck of "one-time use" of the traditional polymer brush, and combines the dynamic and repairable antifouling function with the static and solid mechanical protection substrate, which is beneficial to the development of long-life, low-maintenance and environment-friendly marine protection coating. DETAILED DESCRIPTION

[0017] The application provides a modified polysilazane coating, comprising independently packaged A material and B material.

[0018] In the application, the A material comprises 5-30 parts of polysilazane compound in mass fraction, which can be specifically 8 parts, 10 parts, 13 parts, 15 parts, 20 parts, 25 parts or 28 parts. As a specific embodiment of the application, the polysilazane compound can comprise one or more of methyl polysilazane, vinyl polysilazane, phenyl polysilazane, perhydro polycyclosilazane, polysilaborazane, polyfluorosilazane and polyureasilazane, and can be specifically methyl polysilazane, vinyl polysilazane, phenyl polysilazane, perhydro polycyclosilazane, polysilaborazane, polyfluorosilazane or polyureasilazane.

[0019] In the present application, the A material includes 1-5 parts of low surface energy compound, which can be specifically 2 parts, 3 parts or 4 parts, based on the mass fraction of polysilazane compound. In the present application, the low surface energy compound is prepared by free radical polymerization of silane coupling agent, fluorine-containing polymerizable monomer, silicon-containing polymerizable monomer and second initiator. As a specific embodiment of the present application, the silane coupling agent can include one or more of γ-aminopropyl triethoxysilane (KH550), N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane (KH-602), γ-(2,3-epoxypropoxy) propyl trimethoxysilane (KH-560), γ-(methacryloyloxy) propyl trimethoxysilane (KH-570), 3-mercaptopropyl triethoxysilane (KH580) and γ-mercaptopropyl trimethoxysilane (KH-590), which can be specifically γ-aminopropyl triethoxysilane, N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane, γ-(2,3-epoxypropoxy) propyl trimethoxysilane, γ-(methacryloyloxy) propyl trimethoxysilane, 3-mercaptopropyl triethoxysilane or γ-mercaptopropyl trimethoxysilane. The present application grafts the low surface energy compound to the polysilazane compound through the hydrolysis condensation reaction of the silane coupling agent, which can form a covalent bond with the hydroxyl group or other active functional groups on the surface of the substrate, thereby enhancing the bonding force between the polysilazane layer and the substrate.

[0020] As a specific embodiment of the present application, the fluorine-containing polymerizable monomer can include one or more of dodecafluoroheptyl methacrylate, 1H, 1H, 2H, 2H-perfluorooctyl acrylate, hexafluoropropene, tetrafluoroethylene, trifluorochloroethylene, vinylidene fluoride, perfluoropolyether (meth) acrylate, trifluoroethyl methacrylate and hexafluoroisopropyl methacrylate, and can specifically be dodecafluoroheptyl methacrylate, 1H, 1H, 2H, 2H-perfluorooctyl acrylate, hexafluoropropene, tetrafluoroethylene, trifluorochloroethylene, vinylidene fluoride, perfluoropolyether (meth) acrylate, trifluoroethyl methacrylate or hexafluoroisopropyl methacrylate. As a specific embodiment of the present application, the silicon-containing polymerizable monomer can include one or more of vinyl trialkoxysilane, vinyl trimethoxysilane, divinyl silane derivative, allyl trimethoxysilane and methacryloyloxypropyl trimethoxysilane, and can specifically be vinyl trialkoxysilane, vinyl trimethoxysilane, divinyl silane derivative, allyl trimethoxysilane or methacryloyloxypropyl trimethoxysilane; the divinyl silane derivative can be tetra-vinyl silane. As a specific embodiment of the present application, the second initiator can include one or more of dibenzoyl peroxide, tert-butyl benzene peroxide, dicumyl peroxide, azobisisobutyronitrile (AIBN) and azobis isobutylamidine hydrochloride, and can specifically be dibenzoyl peroxide, tert-butyl benzene peroxide, dicumyl peroxide, azobisisobutyronitrile or azobis isobutylamidine hydrochloride.

[0021] As a specific embodiment of the present application, the molar ratio of the silane coupling agent, the fluorine-containing polymerizable monomer and the silicon-containing polymerizable monomer can be 1:3-6:3-6, and can specifically be 1:3:3 or 1:5.6:5.6; the content of the second initiator in the free radical polymerization system can be 1-5 wt%, and can specifically be 2 wt%, 3 wt% or 4 wt%.

[0022] As a specific embodiment of the present application, the raw material for preparing the low surface energy compound further includes an organic solvent, and the organic solvent can be tetrahydrofuran or n-butyl ether. The present application does not have special limitations on the amount of the organic solvent, as long as the material can be fully dissolved.

[0023] As a specific embodiment of the present application, the temperature of the free radical polymerization reaction can be 65-75°C, and can specifically be 68°C, 70°C or 73°C; the time of the free radical polymerization reaction can be 4-6 h, and can specifically be 5 h.

[0024] As a specific embodiment of the present application, the radical polymerization reaction can further include mixing the radical polymerization reaction system with hexane for precipitation, and drying the obtained solid after solid-liquid separation to obtain the low surface energy compound. The present application does not have special requirements for the solid-liquid separation method as long as it can achieve solid-liquid separation. The present application does not have special requirements for the amount of hexane as long as it can achieve complete precipitation. As a specific embodiment of the present application, the drying can be vacuum drying, the temperature of the vacuum drying can be 20-30℃, which can be specifically 25℃; the time of the vacuum drying can be 22-26h, which can be specifically 23h, 24h or 25h; the present application does not have special requirements for the vacuum degree of the vacuum drying as long as it is a vacuum condition.

[0025] In the present application, the A material includes 1-5 parts of the first initiator based on the mass fraction of the polysilazane compound, which can be specifically 2 parts, 3 parts or 4 parts. In the present application, the first initiator is used for subsequent grafting of the polymer brush.

[0026] As a specific embodiment of the present application, the first initiator can be an initiator for atom transfer radical polymerization, and the first initiator can include 3-aminopropyl triethoxysilane-Br (APTES-Br); the structural formula of the 3-aminopropyl triethoxysilane-Br is shown as formula 1: Formula 1.

[0027] As a specific embodiment of the present application, the preparation method of the 3-aminopropyltriethoxysilane-Br can comprise the following steps: first mixing 3-aminopropyltriethoxysilane, triethylamine and dry organic solvent, and then adding 2-bromoisobutyryl bromide dropwise to carry out amidation reaction to obtain the 3-aminopropyltriethoxysilane-Br. As a specific embodiment of the present application, the dry organic solvent can be anhydrous dichloromethane. As a specific embodiment of the present application, the molar ratio of the 3-aminopropyltriethoxysilane (APTES) and triethylamine can be 3:3.5-4.5, and can be specifically 3:4; the volume ratio of the molar amount of the 3-aminopropyltriethoxysilane to the dry organic solvent can be 45 mmol:95-105 mL, and can be specifically 45 mmol:100 mL; the molar ratio of the 3-aminopropyltriethoxysilane and 2-bromoisobutyryl bromide (BiBB) can be 3:3.5-4.5, and can be specifically 3:4. As a specific embodiment of the present application, the first mixing can be carried out under stirring in an ice water bath, and the stirring time can be 18-22 min, and can be specifically 20 min. As a specific embodiment of the present application, the dropwise adding can be carried out in an ice water bath, and the temperature of the system during the dropwise adding can be 0°C; after the dropwise adding is completed, the stirring is continued for 25-30 min. As a specific embodiment of the present application, the temperature of the amidation reaction can be room temperature, and the temperature of the room temperature can be 20-30°C, and can be specifically 25°C; the time of the amidation reaction can be 22-26 h, and can be specifically 24 h.

[0028] As a specific embodiment of the present application, after the amidation reaction, the reaction system can be further filtered, the filtrate obtained by the filtering can be washed with hydrochloric acid solution, sodium carbonate solution and water in sequence, the organic phase after the washing and anhydrous magnesium sulfate can be mixed and dried, and then rotary evaporation is carried out to obtain the 3-aminopropyltriethoxysilane-Br. As a specific embodiment of the present application, the molar concentration of the hydrochloric acid solution can be 0.8-1.2 mol / L, and can be specifically 1 mol / L; the sodium carbonate solution can be a saturated sodium carbonate solution; the water can be deionized water; and the drying time can be 22-26 h, and can be specifically 24 h. The rotary evaporation in the present application is not particularly limited, as long as the solvent can be removed.

[0029] In the present application, the 3-aminopropyltriethoxysilane-Br can be grafted into the network of the polysilazane layer through hydrolysis, so that new first initiators can be exposed after the polymer brush layer is worn out, and the polymer brush layer can be repeatedly grafted.

[0030] In the present application, the A material includes 50-80 parts of a dispersion medium, which can be specifically 55 parts, 60 parts, 65 parts, 70 parts or 75 parts, based on the mass fraction of the polysilazane compound. As a specific embodiment of the present application, the dispersion medium can include tetrahydrofuran or n-butyl ether.

[0031] As a specific embodiment of the present application, the preparation method of the A material can include the following steps: stirring the polysilazane compound, the low surface energy compound, the first initiator and the dispersion medium at room temperature to obtain the A material; the temperature of the room temperature can be 20-35℃, and can also be 25-30℃; the stirring time can be 10-14h, which can be specifically 12h. In the present application, the A material is a transparent solution.

[0032] In the present application, the B material includes a polymer brush monomer, a catalytic system, a reducing catalyst and water; the catalytic system includes copper chloride and pentamethyldiethylenetriamine; the copper chloride can be copper chloride dihydrate. As a specific embodiment of the present application, the polymer brush monomer can include a zwitterionic monomer, a cationic monomer or an anionic monomer; the zwitterionic monomer can include one or more of potassium 3-sulfopropyl methacrylate (SPMA), sulfobetaine methacrylate, methacryloyl ethyl sulfobetaine (SBMA) and dimethylaminoethyl methacrylate (DMAEMA), which can be specifically potassium 3-sulfopropyl methacrylate, sulfobetaine methacrylate (SBMA), methacryloyl ethyl sulfobetaine or dimethylaminoethyl methacrylate; the cationic monomer can include one or more of methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride and dimethyl diallyl ammonium chloride, which can be specifically methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride or dimethyl diallyl ammonium chloride; the anionic monomer can include acrylic acid (AA).

[0033] As a specific embodiment of the present application, the reducing catalyst can include ascorbic acid; the water can be deionized water. As a specific embodiment of the present application, the mass ratio of the copper chloride to the pentamethyldiethylenetriamine can be 7-9mg:10μL, which can be specifically 8mg:10μL; the mass ratio of the polymer brush monomer to water can be 1.5-2.5:5, which can be specifically 2:5; the volume ratio of the water to the pentamethyldiethylenetriamine can be 5mL:9-11μL, which can be specifically 5mL:10μL; the molar ratio of the reducing catalyst to the copper chloride can be 9-11:1, which can be specifically 10:1.

[0034] As a specific embodiment of the present application, the preparation method of the B material can comprise the following steps: after mixing the polymer brush monomer, the catalyst system and water, a reducing catalyst is added for catalyst activation to obtain the B material; the second mixing can be stirred under a protective atmosphere, which can be nitrogen, and the present application has no special requirements for the stirring as long as it can be uniformly mixed; the catalyst activation can be carried out under stirring, and the stirring time can be 1.5-2.5 min, which can be specifically 2 min.

[0035] The present application also provides a modified polysilazane coating, comprising a substrate and a polysilazane layer, a polymer brush layer grafted to the surface of the polysilazane layer. The polysilazane layer is formed by the A material, and the polymer brush layer is formed by the B material. As a specific embodiment of the present application, the substrate can comprise glass, metal or polymer; the metal can comprise iron sheet or aluminum sheet; the polymer can comprise rubber, polyurethane, polypropylene, polyethylene, polystyrene, polydimethylsiloxane (PMDS) or fiber; the thickness of the substrate is not specially limited in the present application, which can be limited as required. In the present application, the thickness of the polysilazane layer can be 30-90 µm, which can be specifically 40 µm, 50 µm, 60 µm, 70 µm or 80 µm; the thickness of the polymer brush layer can be 30-90 µm, which can be specifically 40 µm, 50 µm, 60 µm, 70 µm or 80 µm.

[0036] The bottom layer (polysilazane layer) in the modified polysilazane coating provided by the present application forms a firm chemical bond with the substrate through controllable hydrolysis, ensuring the adhesion strength and durability of the coating, and the polymer brush layer endows the modified polysilazane coating with excellent anti-adhesion performance, and the surface of the polysilazane coating has excellent lubrication, anti-biofouling and repeatable grafting performance.

[0037] The present application also provides a preparation method of the modified polysilazane coating in the above technical solution, comprising the following steps: After coating the A material on the surface of the substrate and solidifying, a substrate containing a polysilazane layer is obtained; The substrate containing the polysilazane layer is immersed in the B material for atom transfer radical polymerization to obtain the modified polysilazane coating.

[0038] The present application coats the substrate with A material and then solidifies to obtain a substrate containing a polysilazane layer. As a specific embodiment of the present application, the coating can further include: subjecting the substrate to plasma sputtering treatment in an oxygen atmosphere; the plasma sputtering treatment can be performed for 1-3 min, and can be specifically 2 min. The present application hydroxylates the surface of the substrate after plasma sputtering treatment, thereby improving the surface activity of the substrate. As a specific embodiment of the present application, the substrate can include glass, metal or polymer, the metal can include iron sheet or aluminum sheet; and the polymer can include rubber, polyurethane, polypropylene, polyethylene, polystyrene, polydimethylsiloxane (PMDS) or fiber.

[0039] The present application does not have special requirements for the coating method, and a conventional method in the art can be used. As a specific embodiment of the present application, the solidification temperature can be 55-65℃, and can be specifically 60℃; and the solidification time can be 46-50 h, and can be specifically 48 h.

[0040] After obtaining the substrate containing a polysilazane layer, the present application immerses the substrate containing a polysilazane layer in B material to perform atom transfer radical polymerization, thereby obtaining the modified polysilazane coating. The present application does not have special requirements for the amount of B material, as long as the substrate containing a polysilazane layer can be immersed. As a specific embodiment of the present application, the atom transfer radical polymerization (ATRP) can be performed for 2-6 h, and can be specifically 3 h, 4 h or 5 h; the atom transfer radical polymerization can be performed at a temperature of 20-30℃, and can be specifically 20℃, 25℃ or 30℃; and the atom transfer radical polymerization can be performed in a sealed environment to avoid the influence of air.

[0041] As a specific embodiment of the present application, the atom transfer radical polymerization can further include: washing the sample after the atom transfer radical polymerization with water and then drying, thereby obtaining the modified polysilazane coating. As a specific embodiment of the present application, the water used for washing can be deionized water; the washing can be performed for 2-4 times, and can be specifically 3 times; and the drying can be performed by blowing nitrogen.

[0042] The present application also provides a method for repairing a modified polysilazane coating, which comprises the following steps: immersing the damaged modified polysilazane coating in B material to perform atom transfer radical polymerization, thereby obtaining a repaired modified polysilazane coating.

[0043] As a specific embodiment of the present application, the damaged modified polymeric silane coating can be a sample in which the polymer brush layer is damaged by abrasion to make the modified polymeric silane coating lose functionality; the conditions for performing the atom transfer radical polymerization reaction can refer to the process for preparing the modified polysilazane coating, which is not repeated here.

[0044] The number of times of repairing the damaged modified polymeric silane coating in the present application can be 5 or more, specifically 5, 6 or 10.

[0045] In the present application, the first initiator (ATRP initiator) is introduced into the network structure of the coating by hydrolysis, for example, the triethoxysilane contained in the APTES-Br initiator can be introduced into the polysilazane crosslinking network by hydrolysis to form Si-OH; therefore, the polymer brush can be re- immersed in the B material after abrasion to realize repeated grafting multiple times. The present application provides a method of wear-resistant coating with repeated grafting.

[0046] In order to further illustrate the present application, the technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0047] Example 1 (1) Substrate pretreatment process: the surface of a glass substrate with a thickness of 1 mm was hydroxylated by plasma sputtering treatment for 3 min to obtain a pretreated substrate; (2) Synthesis of low surface energy compound: 5.6 g (0.014 mol) of dodecafluoroheptyl methacrylate (fluorine-containing polymerizable monomer, Mw=400.16), 2.08 g (0.014 mol) of vinyltrimethoxysilane (Mw=148.23), 0.598 g (0.00251 mol) of KH580 silane coupling agent (Mw=238.42), and 0.28 g of azobisisobutyronitrile (second initiator) were dissolved in 15 mL of tetrahydrofuran, and a free radical polymerization reaction was carried out at 70°C under nitrogen atmosphere for 6 h, then 50 mL of hexane was added for precipitation, and the obtained solid was dried at 25°C under vacuum to obtain a low surface energy compound; (3) Preparation of APTES-Br initiator: Under a nitrogen atmosphere, a 250 mL three-necked flask containing anhydrous dichloromethane (100 mL) was added 3-aminopropyltriethoxysilane (APTES, 45 mmol) and triethylamine (60 mmol); the mixed system was placed in an ice water bath and stirred for 20 min to reduce the temperature to 0°C, and 2-bromoisobutyryl bromide (60 mmol) was slowly added dropwise; after the dropwise addition was completed, stirring was continued at 0°C for 30 min, and then the temperature was restored to room temperature (25°C) for amide reaction for 24 h; after the reaction was completed, the white precipitate was removed by filtration, and the obtained filtrate was washed with 1 mol / L HC1 solution, saturated Na2CO3 solution and deionized water three times in turn, and the organic phase was taken; the organic phase and anhydrous MgSO4 were mixed and dried for 24 h, and then the solvent was removed by rotary evaporation to obtain the APTES-Br initiator; (4) Preparation of polysilazane layer: 20 parts of methyl polysilazane (9150), 2 parts of low surface energy compound, 2 parts of APTES-Br initiator and 76 parts of tetrahydrofuran were stirred and mixed at 25°C for 12 h to obtain a transparent solution (A material); the obtained transparent solution was drop-coated on the surface of the pretreated substrate and cured at 60°C for 48 h to obtain a polysilazane layer with a thickness of 45 µm; (5) Preparation of polymer brush layer: 2 g of 3-sulfopropyl methacrylate potassium salt (SPMA), 5 mL of deionized water, 8 mg of copper chloride dihydrate (CuCl2·2H2O) and 10 µL of pentamethyldiethylenetriamine (PMEDTA) were sequentially added to a test tube, nitrogen was introduced for protection, and stirring was performed until the monomer and catalyst were completely dissolved; then 88 mg of ascorbic acid (AA) was added and stirred for 2 min to activate the catalyst to obtain B material; the glass substrate on which the polysilazane layer was formed was immersed in B material, and the bottle cap was tightly closed to prevent air from entering; after 6 h of atom transfer radical polymerization, the sample was taken out, washed with deionized water for 3 times, and dried with nitrogen to form a polymer brush layer with a thickness of 50 µm, thereby obtaining a modified polysilazane coating.

[0048] Example 2 (1) Substrate pretreatment process: The surface of a PDMS substrate with a thickness of 1 mm was subjected to hydroxylation treatment by plasma sputtering for 3 min to obtain a pretreated substrate; (2) Synthesis of low surface energy compound: 5.85 g (0.014 mol) of 1H, 1H, 2H, 2H- perfluorooctyl acrylate (fluorine-containing polymerizable monomer Mw = 418.15), 2.08 g (0.014 mol) of vinyltrimethoxysilane (Mw = 148.23), 0.598 g (0.00251 mol) of KH580 silane coupling agent, and 0.28 g of azobisisobutyronitrile (second initiator) were dissolved in 15 mL of tetrahydrofuran, and a free radical polymerization reaction was carried out at 70°C under a nitrogen atmosphere for 6 h. After the reaction, 50 mL of hexane was added for precipitation, and the obtained solid was dried at 25°C under vacuum to obtain a low surface energy compound; (3) Preparation of APTES-Br initiator according to the method of Example 1; (4) Preparation of polysilazane layer: 20 parts of methyl polysilazane (9150), 1 part of low surface energy compound, 2 parts of APTES-Br initiator, and 77 parts of tetrahydrofuran were stirred and mixed at 25°C for 12 h to obtain a transparent solution (material A). The obtained transparent solution was drop-coated on the surface of the pretreated substrate and cured at 60°C for 48 h to obtain a polysilazane layer with a thickness of 50 µm; (5) Preparation of polymer brush layer: 2 g of sulfobetaine methacrylate (SBMA), 5 mL of deionized water, 8 mg of copper chloride dihydrate (CuCl2·2H2O), and 10 µL of pentamethyldiethylenetriamine (PMEDTA) were sequentially added to a test tube, nitrogen was introduced, and stirring was carried out until the monomer and catalyst were completely dissolved. Then, 88 mg of ascorbic acid (AA) was added and stirred for 2 min to activate the catalyst, and material B was obtained. The PDMS substrate forming the polysilazane layer was immersed in material B, and the bottle cap was tightly sealed to prevent air from entering. After 6 h of atom transfer radical polymerization, the sample was taken out, washed with deionized water for 3 times, and dried with nitrogen to form a polymer brush layer with a thickness of 50 µm, and a modified polysilazane coating was obtained.

[0049] Example 3 (1) Substrate pretreatment process: The surface of a metal iron substrate with a thickness of 1 mm was hydroxylated by plasma sputtering treatment for 1 min to obtain a pretreated substrate; (2) Synthesis of low surface energy compound: 5.85 g (0.014 mol) of 1H, 1H, 2H, 2H- perfluorooctyl acrylate (fluorine-containing polymerizable monomer) (Mw = 418.15), 2.27 g (0.014 mol) of allyltrimethoxysilane (Mw = 162.26), 0.598 g (0.00251 mol) of KH580 silane coupling agent, and 0.28 g of azobisisobutyronitrile (second initiator) were dissolved in 15 mL of tetrahydrofuran, and a free radical polymerization reaction was carried out at 70°C under a nitrogen atmosphere for 6 h. After the reaction, 50 mL of hexane was added for precipitation, and the obtained solid was dried at 25°C under vacuum to obtain a low surface energy compound. (3) Preparation of APTES-Br initiator according to the method of Example 1; (4) Preparation of polysilazane layer: 30 parts of methyl polysilazane (9150), 1 part of low surface energy compound, 2 parts of ATRP reaction initiator, and 77 parts of tetrahydrofuran were mixed at 25°C for 12 h. A transparent solution (material A) was obtained. The obtained transparent solution was drop-coated on the surface of a pretreated substrate and cured at 60°C for 48 h to obtain a polysilazane layer with a thickness of 50 µm. (5) Preparation of polymer brush layer: 2 g of sulfobetaine methacrylate (SBMA), 5 mL of deionized water, 8 mg of copper chloride dihydrate (CuCl2·2H2O), and 10 µL of pentamethyldiethylenetriamine (PMEDTA) were sequentially added to a test tube, nitrogen was introduced, and stirring was carried out until the monomer and catalyst were completely dissolved. Then, 88 mg of ascorbic acid (AA) was added and stirred for 2 min to activate the catalyst, and material B was obtained. The PDMS substrate on which the polysilazane layer was formed was immersed in material B, and the bottle cap was tightly closed to prevent air from entering. After 6 h of atom transfer radical polymerization, the sample was taken out, washed with deionized water 3 times, and dried with nitrogen to form a polymer brush layer with a thickness of 45 µm, thereby obtaining a modified polysilazane coating.

[0050] Test Example 1 The modified polysilazane coating prepared in Examples 1 to 3 was tested for performance according to the following method, and the test results are shown in Table 1.

[0051] Tribological performance test: The test conditions were a load of 1 N, a PDMS complex mode of 6 mm, a frequency of 1 Hz, and a test time of 10 min.

[0052] Surface modulus test: The surface modulus was tested using a nanoindentation (Bioindenter UNHT3 Bio, Anton Paar).

[0053] Antifouling performance test: First, a purchased Chlorella vulgaris suspension was diluted with deionized water to a concentration of 1.0 x 106 cells / mL, and the diluted suspension was used for the test. The test was carried out in a 12-well plate, and the test conditions were as follows: 1 mL of the diluted suspension was added to each well, and the plate was incubated in the dark for 24 h. Then, 1 mL of the modified polysilazane coating prepared in Examples 1 to 3 was added to each well, and the plate was incubated in the light for 24 h. After the test, the number of cells was counted using a hemocytometer, and the antifouling performance was evaluated. -2) under alternating conditions for 20 days in a constant temperature incubator (25°C, BPC-500F, bluepard.com) to ensure the algae concentration reached a suitable concentration (1.5 x 10 6 L -1 left and right). Chlorophyll in seaweed cells emits fluorescence under excitation light at a specific wavelength, so the adhesion behavior of seaweed can be observed by means of a fluorescence microscope (Olympus BX51). During the test, the sample was cut into 1 x 1 cm 2 squares and placed in a sterilized glass bottle. Then, 5 mL of algae suspension was poured into the glass bottle and the sample surface was immersed to a depth of about 1 cm. After incubation in a constant temperature incubator for 24 h, the sample was taken out, washed three times with artificial seawater to remove the seaweed that did not adhere to the surface of the sample, and the fluorescence photos of the sample surface with adhered seaweed were taken by a fluorescence microscope. The same shooting conditions were maintained when taking photos, such as exposure, light intensity, exposure time, etc., with a magnification of 20 times and a field size of 0.14 mm 2 . Fifteen photos were randomly taken for each sample, and finally the density of algae adhered to the surface of the sample was counted according to the method in the literature using ImageJ.

[0054] Table 1 Test results of the friction and antifouling properties of the modified polysilazane coating prepared in Examples 1-3

[0055] As can be seen from Table 1, the modified polysilazane coating provides a hard lubricating layer and has excellent lubricating properties and antifouling properties.

[0056] Test Example 2 The modified polysilazane coating prepared in Example 3 was tested for repeatable grafting properties according to the following method, and the test results are shown in Table 2.

[0057] The repeatable grafting properties of the polymer brush were determined by using a wear tester (Model 339). The experiment used polyester cloth as the upper friction pair and was carried out in a water environment. The coating was subjected to 5000 cycles of reciprocating wear under a load of 5 N, and after the friction test, the contact angle and friction coefficient of the surface were measured. Then, the worn sample was immersed again in the B material of Example 3 to graft a polymer brush (for 6 h of atom transfer radical polymerization), and the friction coefficient and contact angle were tested again. The modified polysilazane coating after the second repair was subjected to 5000 cycles of reciprocating wear test again, with grafting-wearing as one cycle of repair, and the cycle repair was repeated for 5 times.

[0058] Table 2 Test results of the modified polysilazane coating after 5 cycles of repair

[0059] As shown in Table 2, the modified polysilazane coating provided by the present application has stable and repeatable grafting performance, and after abrasion, the grafting can still maintain low friction and good hydration lubrication performance.

[0060] Although the above embodiments have made a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, which all belong to the protection scope of the present application.

Claims

1. A modified polysilazane coating, characterized in that, Includes individually packaged materials A and B; Material A comprises the following components in parts by weight: 5-30 parts of polysilazane compounds; 1-5 parts of low surface energy compound; 1-5 parts of the first initiator; 50-80 parts of dispersion medium; The low surface energy compound is prepared by free radical polymerization of a silane coupling agent, a fluorinated polypolymerizable monomer, a silicon-containing polypolymerizable monomer, and a second initiator. Material B comprises polymer brush monomer, catalytic system, reducing catalyst and water; the catalytic system comprises copper chloride and pentamethyldiethylenetriamine.

2. The modified polysilazane coating according to claim 1, characterized in that, The fluorinated polypolymerizable monomers include one or more of the following: dodecafluoroheptyl methacrylate, 1H,1H,2H,2H-perfluorooctyl acrylate, hexafluoropropylene, tetrafluoroethylene, trifluorochloroethylene, vinylidene fluoride, perfluoropolyether (meth) acrylate, trifluoroethyl methacrylate, and hexafluoroisopropyl methacrylate. The silicon-containing polymerizable monomers include one or more of vinyltrialkoxysilane, vinyltrimethoxysilane, divinylsilane derivatives, allyltrimethoxysilane, and methacryloxypropyltrimethoxysilane; The silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and γ-mercaptopropyltrimethoxysilane; The second initiator includes one or more of benzoyl peroxide, tert-butyl benzoate peroxide, dicumyl peroxide, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride.

3. The modified polysilazane coating according to claim 1 or 2, characterized in that, The molar ratio of the silane coupling agent, the fluorinated polymerizable monomer, and the silicon-containing polymerizable monomer is 1:3~6:3~6; the content of the second initiator in the free radical polymerization reaction system is 1~5 mol% The free radical polymerization reaction is carried out at a temperature of 65-75°C for 4-6 hours.

4. The modified polysilazane coating according to claim 1, characterized in that, The polysilazane compounds include one or more of methyl polysilazane, vinyl polysilazane, phenyl polysilazane, perhydropolycyclosilazane, polysiloborazane, polyfluorosilazane, and polyurea silazane; The first initiator is an initiator for atom transfer radical polymerization reaction, and the first initiator includes 3-aminopropyltriethoxysilane-Br; The dispersion medium includes tetrahydrofuran or n-butyl ether.

5. The modified polysilazane coating according to claim 1, characterized in that, The polymer brush monomer includes amphoteric monomers, cationic monomers, or anionic monomers. The zwitterionic monomers include one or more of potassium propyl 3-sulfonate methacrylate, sulfonate betaine methacrylate, and dimethylaminoethyl methacrylate. The positive ion monomer includes one or more of methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, and dimethyl diallylammonium chloride; The anionic monomer includes acrylic acid; The reducing catalyst includes ascorbic acid; The mass ratio of copper chloride to pentamethyldiethylenetriamine is 7-9 mg:10 μL; the mass ratio of polymer brush monomer to water is 1.5-2.5:5; the volume ratio of water to pentamethyldiethylenetriamine is 5 mL:9-11 μL; and the molar ratio of reducing catalyst to copper chloride is 9-11:

1.

6. A modified polysilazane coating, characterized in that, It includes a laminated matrix and a polysilazane layer, and a polymer brush layer grafted onto the surface of the polysilazane layer; The polysilazane layer is formed from material A, and the polymer brush layer is formed from material B.

7. The modified polysilazane coating according to claim 6, characterized in that, The matrix includes glass, metal, or polymer; The thickness of the polysilazane layer is 30~90µm, and the thickness of the polymer brush layer is 30~90µm.

8. The method for preparing the modified polysilazane coating according to claim 6 or 7, characterized in that, Includes the following steps: After coating the substrate surface with material A and curing it, a substrate containing a polysilazane layer is obtained; The substrate containing the polysilazane layer is immersed in material B and subjected to an atom transfer radical polymerization reaction to obtain the modified polysilazane coating.

9. The preparation method according to claim 8, characterized in that, The process prior to coating also includes: subjecting the substrate to plasma sputtering treatment in an oxygen atmosphere; The curing temperature is 55~65℃, and the curing time is 46~50h; The time for the atom transfer radical polymerization reaction is 2-6 hours.

10. A method for repairing modified polysilazane coatings, characterized in that, Includes the following steps: The damaged modified polysilane coating was re-impregnated with material B to carry out an atom transfer radical polymerization reaction, resulting in a repaired modified polysilazane coating.

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