Durable superhydrophobic coating for sanitary ware and method of making the same

Abstract

The application discloses a kind of durable super-hydrophobic coating for sanitary ware and preparation method thereof, it is related to super-hydrophobic technical field, the durable super-hydrophobic coating for sanitary ware and preparation method thereof step successively includes substrate pretreatment, preparation and spraying of stress buffer and triboelectric bottom layer, preparation and spraying of porous liquid storage middle layer and the infusion of anchoring lubricating liquid surface layer;The application realizes the double wear-resistant mechanism of initiative and passive by multilayer synergistic design, significantly reduces the replacement frequency and maintenance cost of toilet coating;And can prevent the damage of external surfactant to super-hydrophobic interface, prolongs the actual service life of coating, provides key surface engineering support for large-scale extraction of protein drugs from urine.

Description

Technical Field

[0001] This invention relates to the field of superhydrophobic coating technology, specifically to a durable superhydrophobic coating for sanitary ware and its preparation method. Background Technology

[0002] Due to its excellent self-cleaning properties, superhydrophobic coatings have been explored for use in recent years on the inner walls of toilets, urinals, and other sanitary ware, aiming to achieve a water-saving self-cleaning effect with a simple flush. Traditional ceramic toilets rely on a smooth glaze and the mechanical force of flushing for cleaning, but they still leave residues of sticky feces, urine, and other dirt, requiring frequent scrubbing, which is both unhygienic and wasteful of water. Superhydrophobic coatings, by constructing a micro-nano rough structure and modifying it with low surface energy materials, allow water droplets to form near-spherical shapes on the surface, easily rolling off and carrying away dirt.

[0003] In related technologies, superhydrophobic coatings applied to the inner walls of sanitary ware still have the following technical defects in practical use: 1. Poor wear resistance: Existing superhydrophobic coatings mostly rely on micro-nano rough structures and low surface energy materials to achieve water repellency. However, during toilet flushing or contact with urine, the hard particles repeatedly scratch the surface, causing the fragile micro-nano structure to be quickly destroyed, losing its superhydrophobic properties, resulting in a short actual service life and failing to meet the long-term service requirements of sanitary ware. 2. Weak resistance to surfactants: Everyday cleaning agents such as toilet cleaners, shower gels, and laundry detergents all contain surfactants. Surfactants significantly reduce the surface tension of water, allowing water droplets to forcefully wet the originally superhydrophobic surface. Once the coating comes into contact with liquids containing surfactants, its superhydrophobic properties will drop sharply or even be completely lost in a short time, causing the self-cleaning function to fail. This problem limits the widespread application of superhydrophobic coatings in sanitary ware in homes, hotels, public places, and other places where chemical cleaning agents are used regularly. 3. The preparation process is complex and difficult to industrialize. The preparation of high-performance superhydrophobic coatings often involves complex processes such as photolithography, chemical bath deposition, electrospinning, and template methods. These processes require sophisticated equipment, are expensive, and are mostly used for small-scale laboratory preparations. These methods cannot achieve low-cost, large-area, and high-efficiency spraying on industrial production lines for ceramic sanitary ware such as toilets and urinals, which seriously restricts the industrialization and promotion of superhydrophobic sanitary ware.

[0004] Furthermore, in the biomedical field, urokinase and ulinastatin are two important protein drugs extracted from urine. Before extraction, a large amount of raw urine needs to be collected. Therefore, some urinals have been modified so that the lower end of the urinal is connected to an external urine collection device via a pipe, utilizing the silica gel and resin inside the collection device to adsorb the two proteins. However, the modified urinal no longer has a flushing function, failing to achieve immediate cleaning with a "one-person-one-flush" system. This results in urine residue easily remaining on the inner wall of the urinal, causing odor, bacterial growth, and affecting the purity and efficiency of raw urine collection. Currently, the collection technology from Jilin Weize Technology Co., Ltd. shows good collection results. This invention aims to spray a durable superhydrophobic coating onto the urinal to reduce urine residue inside.

[0005] Therefore, there is an urgent need to develop a durable superhydrophobic coating for the inner wall of sanitary ware that has a long lifespan, resistance to chemical pollution, multi-scale self-healing capabilities, and can be applied by spraying. This coating would also solve the problem of urine residue in urinals without flushing, and would have significant practical value and market prospects. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a durable superhydrophobic coating for sanitary ware and a method for preparing the same. The durable superhydrophobic coating for sanitary ware can effectively ensure its service life and performance, and significantly reduce the replacement frequency and maintenance cost of sanitary ware coatings.

[0007] To solve the above problems, the first aspect of the present invention adopts the following technical solution: A method for preparing a durable superhydrophobic coating for sanitary ware includes the following steps: S1. Matrix pretreatment: Take the inner wall blank of the sanitary ware, clean and dry it, use a sandblasting machine to roughen the surface of the blank to make the surface roughness Ra reach 3-5μm, and then use a plasma cleaning machine to introduce hydroxyl active groups. S2. Preparation and spraying of stress buffer and triboelectric underlayer: By mass fraction, 100 parts of hydroxyl-terminated polydimethylsiloxane, 20 parts of isocyanate-modified nano-silica, 15 parts of barium titanate nanoparticles, and 3 parts of graphene nanosheets were taken. The total solid content was adjusted to 40 wt% by adding a solvent of butyl acetate and isopropanol. The mixture was then mixed and ultrasonically dispersed in a planetary stirrer to obtain a mixture. The mixture was then uniformly sprayed onto the surface of the pre-treated blank in step S1 using an air spray gun, increasing the wet film thickness to 60 μm. After spraying, the blank was placed in an oven and cured at 80°C for 2 hours. Then, the temperature was raised to 120°C and cured for another hour to obtain a stress buffer and triboelectric underlayer with a dry film thickness of 35-45 μm. S3. Preparation and spraying of porous liquid storage intermediate layer: By weight, take 100 parts of fluorinated polyurethane solution, 40 parts of polymethyl methacrylate microspheres, 10 parts of hollow mesoporous silica nanocapsules, 5 parts of Bacillus subtilis spore microcapsules, and 0.5 parts of dibutyltin dilaurate. Add a mixed solvent of xylene and cyclohexanone at a volume ratio of 7:3 to adjust the total solid content to 35 wt%, and magnetically stir in an ice-water bath for 20 min. Apply the mixture to the stress buffer and triboelectric substrate that has been cured in step S2 using a high-pressure airless spray gun to form a wet film. The thickness was increased to 100 μm; after spraying, it was placed in an oven and dried at 60 °C; then the preform was transferred to a muffle furnace and nitrogen gas was introduced to protect the -NCO groups in the fluorinated polyurethane; the temperature was increased from 60 °C to 120 °C at a rate of 1 °C / min and held for 2 h; then the temperature was increased to 250 °C at a rate of 0.5 °C / min and held for 2 h; the power to the muffle furnace was turned off and the preform was allowed to cool naturally to room temperature under a nitrogen gas flow; a preform with a porous liquid storage middle layer was obtained, and the thickness of the resulting dry film of the middle layer was about 50-70 μm. S4. Pouring of the anchoring lubricant surface layer: Perfluoropolyether with a molecular weight of 2000 and a density of 1.82 g / cm³ was mixed with hydroxyl-terminated dimethyl silicone oil at a mass ratio of 3:1. Dibutyltin dilaurate was added to make its concentration in the mixture 0.3 wt%. The mixture was then uniformly sprayed onto the porous liquid reservoir layer surface prepared in step S3 using a low-pressure spray gun in a fine mist, until the surface was visibly wet but without liquid accumulation. The blank was then centrifuged in a benchtop centrifuge to remove excess liquid and recover it. The centrifuged blank was then transferred to an oven and heated at 80°C under nitrogen protection. The hydroxyl groups of OH-PDMS reacted with the residual isocyanate groups on the middle layer surface to form covalent bonds. After removal and standing, the final surface lubricant film thickness was approximately 300-500 nm, resulting in a durable superhydrophobic coating.

[0008] Furthermore, in step S1, the sandblasting machine uses 60-mesh white corundum and a pressure of 0.4 MPa to roughen the surface of the blank.

[0009] Furthermore, in step S2, the barium titanate nanoparticles have a particle size of 100-200 nm, the graphene nanosheets have a thickness of <5 nm and a sheet diameter of 1-5 μm, the air spray gun has a nozzle diameter of 1.0 mm, an air pressure of 0.3 MPa, and a spraying distance of 20 cm.

[0010] Further, in step S3, the solid content of the fluorinated polyurethane solution is 30%, the particle size of the polymethyl methacrylate microspheres is 5-10 μm, the nozzle diameter of the high-pressure airless spray gun is 1.2 mm, the air pressure is 0.5 MPa, and the spraying distance is 25 cm.

[0011] Furthermore, in step S4, the low-pressure spray gun has a nozzle diameter of 0.5 mm and an air pressure of 0.1 MPa. After the blank is taken out, it is left to stand for 2 hours at a room temperature of 25℃±2℃ and a relative humidity of 50%±5%.

[0012] Further, in step S2, the preparation method of the isocyanate-modified nano-silica includes the following steps: S2.1 Weigh 10.0g of hydrophilic nano-silica with an average particle size of 20nm and place it in a 200mL beaker. Dry it in a vacuum drying oven at 120℃ for 12h to remove the physically adsorbed water on the surface. S2.2 Under nitrogen protection, add 200 mL of anhydrous toluene to a 500 mL three-necked flask and start stirring; add 10.0 g of dried nano-silica and sonicate for 15 min to form a uniform suspension; S2.3. Add 15.0 g of toluene diisocyanate to a constant pressure dropping funnel. Under a nitrogen stream, slowly add toluene diisocyanate to the flask at room temperature (25°C) at a dropping rate of 1 mL / min, while maintaining stirring during the addition. The temperature of the reaction solution will naturally rise to 30-35°C due to exothermic reaction. After the addition is complete, heat the oil bath to 110°C and maintain reflux for 6 hours. During the reaction, the silanol groups on the surface of nano-silica react with the isocyanate groups of toluene diisocyanate to generate a Si–O–C(=O)–NH– structure. S2.4 After the reaction is complete, allow it to cool naturally to room temperature. Transfer the reaction solution to a centrifuge tube and centrifuge at 12,000 rpm for 30 min. Discard the supernatant and wash the precipitate twice with anhydrous toluene and once with anhydrous ethanol to remove unreacted toluene diisocyanate and byproducts. S2.5. Place the washed product in a vacuum drying oven and dry it at 60℃ and -0.09MPa for 12 hours to obtain the powder, which is the isocyanate modified nano silica.

[0013] Further, in step S3, the method for preparing the hollow mesoporous silica nanocapsules includes the following steps: S3.1 Take 10 mL of polystyrene nanosphere aqueous dispersion with an average particle size of 200 nm, monodisperse and solid content of 5 wt%, add 40 mL of deionized water to dilute, ultrasonically disperse at 200 W for 10 min, then add 0.152 g of cetyltrimethylammonium bromide, stir and dissolve at 25 °C for 30 min, and use as template solution for subsequent coating. S3.2 Transfer the above template solution to a 250mL three-necked flask, place it in a 35℃ constant temperature water bath, stir magnetically, and adjust the pH to 10.0±0.2 with concentrated ammonia; dissolve 1.8mL of tetraethyl orthosilicate in 4mL of anhydrous ethanol, and add it dropwise to the three-necked flask at a rate of 0.15mL / min; at the same time, maintain the pH of the system at 9.5–10.0 by adding ammonia; after the addition is complete, continue the reaction for 4h; after the reaction is complete, collect the precipitate by centrifugation at 10000rpm for 10min, wash it 3 times with deionized water and 2 times with anhydrous ethanol; vacuum dry at 60℃ for 12h to obtain PS@mSiO2 core-shell powder; then add 1.5mL of tetraethyl orthosilicate dropwise at a rate of 0.2mL / min, while adding ammonia to maintain the pH at 9.5-10.0, and continue the reaction for 4h, during which tetraethyl orthosilicate hydrolyzes and condenses on the surface of PS spheres to form a mesoporous silica shell; S3.3 Place the dry powder in a crucible and put it in a muffle furnace. Procedurally raise the temperature in air atmosphere: from room temperature to 300℃ at 2℃ / min and hold for 1h; then raise the temperature to 500℃ at 1℃ / min and hold for 4h to completely oxidize the PS template; let the furnace cool naturally to room temperature to obtain hollow mesoporous silica nanocapsules (HmSiO2). S3.4 Take 0.5g of calcined HmSiO2 capsules and ultrasonically disperse them in 15mL of anhydrous ethanol; add 0.8g of perfluoropolyether and magnetically stir for 30min to form a suspension; transfer the suspension to a flask and evaporate it under a vacuum of -0.09MPa at 40℃ in a rotary evaporator until the solvent is nearly dry; add 5mL of anhydrous ethanol and repeat the above vacuum permeation process once to ensure that PFPE fully enters the hollow cavity and mesoporous channels; after permeation, redisperse the powder in n-hexane, centrifuge at 10000rpm for 5min to wash away excess PFPE on the surface, and repeat the n-hexane washing twice; air dry in a fume hood for 1h, and then vacuum dry at 40℃ for 4h to obtain hollow mesoporous silica nanocapsules loaded with repair solution.

[0014] Furthermore, the preparation method of hollow mesoporous silica nanocapsules also includes the following steps: S3.5 Disperse the loaded capsules in 10 mL of anhydrous n-hexane, add 0.08 mL of perfluorodecyltrimethoxysilane (PFDTMS), and mix well; under N2 protection, reflux at 60 °C for 2 h; reaction mechanism: the silanol groups generated after the methoxy groups of PFDTMS are hydrolyzed, condense with the silanol groups on the inner wall of the capsule mesoporous channels, forming a comb-like perfluoroalkyl "fence" at the pore opening; after the reaction, centrifuge at 10000 rpm for 10 min, wash twice with n-hexane, vacuum dry at 40 °C for 12 h, and store in a sealed container.

[0015] Further, in step S3, the preparation method of the Bacillus subtilis spore microcapsules includes the following steps: S3.6 Preparation of bacterial strains and culture media: Bacillus subtilis CICC10014; Nutrient broth medium (LB): peptone 10g / L, beef extract 3g / L, NaCl 5g / L, pH 7.2; Nutrient agar slant medium: the above formula with 15g / L agar added; Sporulation induction medium (DSM): nutrient broth with 0.01g / L MnSO4·H2O and 0.01g / L CaCl2 added, pH 7.0; S3.7. Lyophilized powder resuscitation: Under aseptic conditions, use a sterile pipette to add 0.5 mL of nutrient broth culture medium to the lyophilized tube, and gently shake to dissolve the bacterial powder into a suspension; transfer the suspension to a test tube containing 5 mL of nutrient broth culture medium, and incubate in a 37℃ constant temperature incubator for 24 h to obtain the resuscitation solution. S3.8 Preparation of slant culture: Dissolve the nutrient agar medium by heating, dispense into test tubes, autoclave at 121℃ for 20 min, and solidify by tilting while hot to prepare slant culture medium; take 0.1 mL of resuscitation solution and spread it evenly on the surface of the slant, incubate at 37℃ for 24 h to obtain fresh slant culture; store the slant at 4℃ for later use. S3.9 Seed culture and expansion culture: Pick a loop of bacterial growth from a fresh slant and inoculate it into 50 mL of nutrient broth medium. Incubate at 37°C and 200 rpm for 12 h to obtain the seed culture. Inoculate 5 mL of the seed culture into 500 mL of nutrient broth medium and incubate at 37°C and 200 rpm for 24 h to obtain a high-density vegetative culture medium. S3.10. Spore induction: Centrifuge the culture medium at 5000 rpm for 10 min and collect the bacterial pellet; wash once with sterile physiological saline and resuspend in 500 mL of DSM induction medium, and incubate at 37℃ and 200 rpm for 48 h; examine under a microscope every 12 h, and terminate the culture when the spore formation rate is >95%; S3.11. Spore purification: Centrifuge the culture medium at 8000 rpm and 4℃ for 15 min, and discard the supernatant; wash the precipitate three times with sterile deionized water; add 50 mL of lysozyme solution (1 mg / mL, dissolved in Tris-HCl buffer, pH 8.0), and incubate at 37℃ for 1 h to lyse the residual vegetative cells; centrifuge again at 8000 rpm and 4℃ for 15 min, and wash three times with deionized water to obtain a pure spore suspension, which is then stored at 4℃ for later use. S3.12. Preparation of wall material solutions: Sodium alginate solution: Dissolve 1.5g sodium alginate in 100mL deionized water, stir in a 60℃ water bath for 2h, sterilize at 121℃ for 20min, and cool to room temperature; Chitosan solution: Dissolve 0.5g chitosan in 100mL 1% (v / v) glacial acetic acid aqueous solution, stir overnight, filter to remove impurities, and sterilize at 121℃ for 20min. S3.13, Core-wall material mixing and preparation of spray-drying precursor: Under aseptic conditions, take 50 mL of sodium alginate solution and add 10 mL of the spore suspension obtained in step S3.11, and mix with magnetic stirring (200 rpm, 10 min); slowly add 50 mL of chitosan solution and 0.5 mL of Tween-80, and continue stirring for 30 min to obtain the spray-drying precursor mixture; this step forms an aqueous dispersion of polyelectrolyte complex—sodium alginate (anionic) and chitosan (cationic) form a microgel network through electrostatic bonding, in which spores are uniformly embedded; Tween-80, as a nonionic surfactant, further disperses the spores, reduces interfacial tension, and prevents droplet aggregation of the spray-drying precursor, which is beneficial for obtaining uniform particle size in subsequent spray drying. S3.14. Spray dry the spray-drying precursor mixture obtained in step S3.13: inlet air temperature 160℃, outlet air temperature 80-90℃, feed rate 5mL / min, atomization pressure 0.2MPa, nozzle diameter 0.7mm; collect the powder; dry the collected powder in a vacuum dryer at room temperature for 24h; the resulting light yellow powder is Bacillus subtilis spore microcapsules.

[0016] The second aspect of the present invention also discloses a durable superhydrophobic coating, which is prepared by a method for preparing a durable superhydrophobic coating for sanitary ware.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The durable superhydrophobic coating of the present invention achieves a dual anti-wear mechanism of active and passive through multi-layer synergistic design. The barium titanate (BaTiO3) piezoelectric particles added to the bottom layer generate microcurrents under the impact of water flow. These microcurrents are conducted to the middle layer through the graphene network, accelerating the germination of Bacillus subtilis spores and the secretion of surfactants, thereby shortening the biorepair response time. At the same time, the three-dimensional interconnected channels and PFPE-encapsulated nanocapsules in the middle layer serve as reservoirs for the repair fluid, which can automatically release the repair fluid when local wear is severe. Moreover, according to the simulated toilet flushing wear test, the water contact angle of the coating of the present invention is still maintained at about 161°, which is much higher than the superhydrophobic threshold of 150°. Compared with the traditional toilet coating, the durable superhydrophobic coating of the present invention significantly reduces the replacement frequency and maintenance cost.

[0018] (2) In this invention, the surface layer is a perfluoropolyether / hydroxyl silicone oil anchoring liquid film, which has extremely low surface energy and chemical inertness and extremely low adsorption capacity for surfactants. The Bacillus subtilis spore microcapsules contained in the middle layer can metabolize and secrete surfactants after being activated by water. The surfactants preferentially adsorb onto the coating surface to form an anti-fouling barrier and prevent external surfactants from damaging the superhydrophobic interface. This effect makes the toilet coating of this invention compatible with various toilet cleaners, shower gels and other daily chemicals.

[0019] (3) This invention integrates three self-healing mechanisms of different scales to form a complete repair system. The surface lubricating film spreads automatically through capillary action to repair local film loss; when the wear reaches the middle layer, the nanocapsules rupture to release PFPE repair fluid, and at the same time, spores germinate and secrete surfactants to chemically repair the contaminated or damaged surface. This makes the entire repair process automatic during normal flushing and use without the need to disassemble the toilet or perform professional construction. This self-healing ability greatly extends the actual service life of the coating.

[0020] (4) The durable superhydrophobic coating of the present invention enables the waterless urine collection fixture to achieve extremely low urine residue on the inner wall, automatic rolling collection, and inhibition of odor growth without flushing, significantly improving the collection efficiency and purity of raw urine, reducing manual maintenance costs, and providing key surface engineering support for the large-scale extraction of protein drugs from urine. Attached Figure Description

[0021] Figure 1 These are scanning electron microscope (SEM) images of the durable superhydrophobic coating used in sanitary ware according to the present invention; Figure 2 This is a test diagram of the contact angle of the durable superhydrophobic coating used in sanitary ware according to the present invention; Figure 3 This is a graph showing the number of rinsing cycles of the durable superhydrophobic coating used in sanitary ware according to the present invention; Figure 4 This is a graph showing the surfactant contamination test data of this invention; Figure 5 This is the contact angle of control group 1 after 2000 water flushes in this invention; Figure 6 This is the contact angle of control group 2 after 2000 water rinses in this invention; Figure 7 This is the contact angle of control group 3 after 2000 water flushes in this invention; Figure 8 This is the contact angle of control group 1 after surfactant contamination in this invention; Figure 9 This is the contact angle of control group 2 after surfactant contamination in this invention; Figure 10 This is the contact angle of control group 3 after surfactant contamination in this invention. Detailed Implementation

[0022] The technical solutions of the invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without creative effort are within the scope of the invention.

[0023] In the description of this invention, it should be noted that the terms "above" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience and simplification of the description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Example 1: This embodiment 1 discloses a method for preparing a durable superhydrophobic coating for sanitary ware, comprising the following steps: S1. Matrix pretreatment: Take the inner wall blank of the sanitary ware, and ultrasonically clean it sequentially with deionized water and anhydrous ethanol for 15 minutes to remove surface contaminants and attachments. Then, dry it in an oven at 80℃. Roughen the surface of the blank using a sandblasting machine: with a spray gun distance of 20cm and a moving speed of 200mm / s, blow off the residual sand particles with high-pressure air after sandblasting to achieve a surface roughness Ra of 3-5μm. Then, introduce hydroxyl active groups using a plasma cleaning machine. The specific parameters are: working gas is oxygen (purity ≥99.99%), vacuum degree 20Pa, oxygen flow rate 80sccm, radio frequency power 200W (frequency 13.56MHz), and processing time 5 minutes. During operation, the roughened billet is placed in the plasma chamber, and the vacuum is evacuated to a background vacuum of <5Pa. Oxygen is introduced to the set flow rate and the vacuum valve is adjusted to stabilize the pressure inside the chamber at 20Pa. The radio frequency power supply is turned on to generate oxygen plasma. After processing for 5 minutes, the power supply is turned off and the gas supply is stopped. The vacuum pump is kept running for 1 minute to remove the reaction byproducts. Finally, dry air is introduced to restore the atmospheric pressure, and the billet is taken out to obtain the pretreated billet. S2. Preparation and spraying of stress buffer and triboelectric underlayer: By mass fraction, 100 parts of hydroxyl-terminated polydimethylsiloxane, 20 parts of isocyanate-modified nano-silica, 15 parts of barium titanate nanoparticles, and 3 parts of graphene nanosheets were taken. The total solid content was adjusted to 40 wt% by adding a solvent of butyl acetate and isopropanol. The mixture was stirred in a planetary stirrer at 2000 rpm for 30 min and ultrasonically dispersed for 15 min to obtain a mixture. The mixture was then uniformly sprayed onto the surface of the pretreated blank in step S1 using an air spray gun, increasing the wet film thickness to 60 μm. After spraying, the mixture was placed in an oven and cured on the surface of the blank at 80°C for 2 h. Then, the temperature was raised to 120°C and cured for another 1 h to obtain a stress buffer and triboelectric underlayer. The dry film thickness of the obtained underlayer was 35-45 μm. S3. Preparation and spraying of porous liquid storage intermediate layer: By weight, 100 parts of fluorinated polyurethane solution, 40 parts of polymethyl methacrylate microspheres, 10 parts of hollow mesoporous silica nanocapsules, 5 parts of Bacillus subtilis spore microcapsules, and 0.5 parts of dibutyltin dilaurate were added to a mixed solvent of xylene and cyclohexanone at a volume ratio of 7:3 to adjust the total solid content to 35 wt%. The mixture was then magnetically stirred in an ice-water bath (500 rpm, 20 min). A high-pressure airless spray gun (1.2 mm nozzle, 0.5 MPa air pressure, 25 cm spraying distance) was then used to spray the mixture onto the stress buffer and triboelectric substrate that had been cured in step S2, increasing the wet film thickness to 100 μm. After spraying, the mixture was placed in an oven and dried at 60°C for 30 min to allow the fluorinated polyurethane to initially set and the solvent to evaporate. The preform was then transferred to a muffle furnace, and nitrogen gas (flow rate 0.5 L / min) was introduced to protect the -NCO groups in the fluorinated polyurethane. The temperature was increased from 60℃ to 120℃ at a rate of 1℃ / min and held for 2 hours to further crosslink and cure the fluorinated polyurethane, while the PMMA microspheres had not yet decomposed. Subsequently, the temperature was increased to 250℃ at a rate of 0.5℃ / min and held for 2 hours. Under these conditions, the PMMA microspheres thermally decomposed to form three-dimensional interconnected channels; simultaneously, the fluorinated polyurethane completed further crosslinking, but because the temperature was controlled at 250℃ (below the significant decomposition temperature of -NCO, 300℃), approximately 0.05-0.10 mmol / g of active isocyanate groups remained on the surface. Nitrogen protection was maintained throughout the process to prevent the reaction of -NCO with moisture. The muffle furnace power was turned off, and the material was allowed to cool naturally to room temperature under a nitrogen flow to obtain a preform with a porous liquid storage middle layer. The resulting dry film thickness of the middle layer was approximately 50-70 μm. S4. The surface layer of the anchoring lubricant will be infused with a molecular weight of 2000 and a density of 1.82 g / cm³. 3Perfluoropolyether (PFPE) and hydroxyl-terminated dimethyl silicone oil (OH-PDMS) were mixed uniformly at a mass ratio of 3:1. Dibutyltin dilaurate (DBTDL) was added to achieve a concentration of 0.3 wt% in the mixture. The mixture was then uniformly sprayed onto the preform with a porous liquid reservoir layer prepared in step S3 using a low-pressure spray gun (0.5 mm nozzle, 0.1 MPa) in a fine mist until the surface was visibly wetted but without liquid accumulation. The preform was then immediately placed in a benchtop centrifuge and centrifuged at 500 rpm for 5 min to remove excess liquid. The centrifuged preform was then transferred to an oven and heated at 80 °C for 3 h under nitrogen protection. Under these conditions, the hydroxyl groups of OH-PDMS reacted with the residual isocyanate groups (-NCO) on the surface of the mid-layer to form covalent bonds. The reaction formula is as follows: R-NCO+HO-R′→R-NH-COO-R′, where R represents the middle layer fluorinated polyurethane skeleton and R' represents the alkyl chain of OH-PDMS; the final surface lubricant film thickness is about 300-500nm, and a durable superhydrophobic coating is obtained.

[0027] In step S1, the sandblasting machine uses 60-mesh white corundum and a pressure of 0.4 MPa, which can create uniform and dense micron-level pits and scratches on the ceramic surface. The pits and scratches are neither too coarse to cause stress concentration, nor too fine to provide sufficient mechanical locking force. The pressure of 0.4 MPa is considered medium-low pressure sandblasting, which can effectively remove the loose layer on the surface, while avoiding microcracks or matrix damage caused by excessive high pressure stress. It can effectively roughen the surface of the blank.

[0028] In step S2, the barium titanate nanoparticles have a particle size of 100-200 nm; the graphene nanosheets have a thickness of <5 nm and a sheet diameter of 1-5 μm, working synergistically with the barium titanate piezoelectric particles: when water flows and impacts the coating surface, the barium titanate generates a microcurrent due to the piezoelectric effect. This microcurrent is conducted to the middle layer through the graphene network, accelerating the germination of Bacillus subtilis spores and their metabolic secretion of surfactants, thereby shortening the bioremediation response time; the air spray gun has a nozzle diameter of 1.0 mm, an air pressure of 0.3 MPa, and a spraying distance of 20 cm to achieve bottom coating, suitable for industrial production.

[0029] In step S3, the solid content of the fluorinated polyurethane solution is 30%. The fluorinated polyurethane solution can fully fill but not completely encapsulate the gaps between the polymethyl methacrylate microspheres. The pores formed after thermal decomposition are interconnected, which is conducive to the capillary adsorption of the subsequent perfluoropolyether repair solution. The particle size of the polymethyl methacrylate microspheres is 5-10μm, which can achieve a balance between the storage capacity and the release rate. It can both accommodate a sufficient amount of perfluoropolyether repair solution and release it quickly during wear. It can automatically adsorb the repair solution by capillary action to achieve efficient replenishment. The high-pressure airless spray gun has a nozzle diameter of 1.2mm, an air pressure of 0.5MPa, and a spraying distance of 25cm. Compared with ordinary air spray guns, high-pressure airless spraying has less shear force on the coating, which can effectively avoid premature rupture of hollow mesoporous silica nanocapsules and inactivation of Bacillus subtilis spore microcapsules, ensuring the slow release and biorepair function of the middle layer during service.

[0030] In step S4, the low-pressure spray gun has a nozzle diameter of 0.5 mm and an air pressure of 0.1 MPa, which can achieve precise coating from monolayer to submicron level. Combined with the subsequent centrifugal removal process, the final liquid film thickness is controlled at 300-500 nm. This thickness can ensure superhydrophobic performance without being too thick, which would cause capillary adsorption failure or surface stickiness.

[0031] The durable superhydrophobic coating of this invention achieves a dual anti-wear mechanism—active and passive—through a multi-layer synergistic design. The barium titanate (BaTiO3) piezoelectric particles added to the bottom layer generate microcurrents under water flow impact. These microcurrents are conducted to the middle layer through a graphene network, accelerating the germination of Bacillus subtilis spores and their metabolic secretion of surfactants, thereby shortening the biorepair response time. Simultaneously, the three-dimensional interconnected channels and PFPE-encapsulated nanocapsules in the middle layer serve as reservoirs for the repair fluid, automatically releasing it when localized wear is severe. Furthermore, simulated toilet flushing abrasion tests show that the coating's water contact angle remains at approximately 161°, far exceeding the superhydrophobic threshold of 150°. Compared to traditional toilet coatings, this durable superhydrophobic coating significantly reduces replacement frequency and maintenance costs.

[0032] In this invention, the surface layer is a perfluoropolyether / hydroxyl silicone oil anchoring liquid film, which has extremely low surface energy and chemical inertness, and has a very low adsorption capacity for surfactants. The Bacillus subtilis spore microcapsules contained in the middle layer can metabolize and secrete surfactants after being activated by water. The surfactants preferentially adsorb onto the coating surface, forming an anti-fouling barrier and preventing external surfactants from damaging the superhydrophobic interface. This effect makes the toilet coating of this invention compatible with various toilet cleaners, shower gels and other everyday chemicals.

[0033] This invention integrates three self-healing mechanisms at different scales to form a complete repair system. The surface lubricating film automatically spreads through capillary action, repairing localized film loss. When wear reaches the middle layer, nanocapsules rupture to release PFPE repair fluid, while spores germinate and secrete surfactants to chemically repair contaminated or damaged surfaces. This allows the entire repair process to be completed automatically during normal flushing and use without the need to disassemble the toilet or undergo professional installation. This self-healing capability significantly extends the actual service life of the coating.

[0034] The durable superhydrophobic coating of this invention enables waterless urine collection styes to achieve extremely low urine residue on the inner wall, automatic rolling collection, and inhibition of odor growth without the need for flushing. This significantly improves the collection efficiency and purity of raw urine, reduces manual maintenance costs, and provides key surface engineering support for the large-scale extraction of protein drugs from urine.

[0035] Furthermore, the preparation method of isocyanate-modified nano-silica in step S2 includes the following steps: S2.1 Weigh 10.0g of hydrophilic nano-silica with an average particle size of 20nm and place it in a 200mL beaker. Dry it in a vacuum drying oven at 120℃ for 12h to remove the physically adsorbed water on the surface. S2.2 Under nitrogen protection, add 200 mL of anhydrous toluene to a 500 mL three-necked flask and start stirring; add 10.0 g of dried nano-silica and sonicate for 15 min to form a uniform suspension; S2.3. Add 15.0 g of toluene diisocyanate to a constant pressure dropping funnel. Under a nitrogen stream, slowly add toluene diisocyanate to the flask at room temperature (25°C) at a dropping rate of 1 mL / min, while maintaining stirring during the addition. The temperature of the reaction solution will naturally rise to 30-35°C due to exothermic reaction. After the addition is complete, heat the oil bath to 110°C and maintain reflux for 6 hours. During the reaction, the silanol groups on the surface of nano-silica react with the isocyanate groups of toluene diisocyanate to generate a Si–O–C(=O)–NH– structure. S2.4 After the reaction is complete, allow it to cool naturally to room temperature. Transfer the reaction solution to a centrifuge tube and centrifuge at 12,000 rpm for 30 min. Discard the supernatant and wash the precipitate twice with anhydrous toluene and once with anhydrous ethanol to remove unreacted toluene diisocyanate and byproducts. S2.5. Place the washed product in a vacuum drying oven and dry it at 60℃ and -0.09MPa for 12 hours to obtain the powder, which is the isocyanate modified nano silica.

[0036] Specifically, 20nm nano-silica has an extremely high specific surface area, providing abundant surface silanol (Si-OH) reaction sites, which is conducive to full reaction with toluene diisocyanate, increasing grafting density. Moreover, the hydrophilic surface can directly participate in the reaction without additional activation, simplifying the process.

[0037] Using 200 mL of anhydrous toluene as a solvent, both isocyanate and nano-silica exhibit good dispersibility without participating in the reaction. Simultaneously, nitrogen protection is used to eliminate water vapor interference and prevent the hydrolysis and deactivation of -NCO groups. Furthermore, ultrasonic dispersion effectively depolymerizes the nanoparticles, ensuring that each nanoparticle is fully exposed to the reaction medium and guaranteeing grafting uniformity.

[0038] Toluene has a boiling point of 110℃. Reflux ensures a constant temperature in the reaction system while removing trace amounts of moisture. The 6-hour reaction time is sufficient for the hydroxyl groups and -NCO groups on the surface of the nano-silica to fully react, achieving a high grafting rate. The Si–O–C(=O)–NH– structure indicates that one -NCO group of toluene diisocyanate reacts with the hydroxyl groups on the surface of the nano-silica to form a urethane bond, while the other -NCO group remains active and can be used for further reaction with the polymer matrix. This structure endows the nano-silica with hydrophobicity while retaining reactive sites, making it a reactive filler capable of forming chemical crosslinks with the coating matrix and significantly enhancing interfacial adhesion.

[0039] Next, centrifugal washing can effectively precipitate nano-silica, remove unreacted monomers and byproducts, and then low-temperature vacuum drying avoids high temperature damage to the grafted organic segments, while quickly removing residual solvent. At the same time, a high vacuum of -0.09MPa ensures that the solvent is completely removed, preventing hydrolysis or aggregation during storage.

[0040] The method for preparing isocyanate-modified nano-silica successfully produced nano-silica with surface-grafted active isocyanate groups by strictly controlling the drop rate and reaction temperature under anhydrous and oxygen-free conditions and optimizing the post-treatment purification process. This modified product not only retains the dispersibility of nanoparticles but also forms chemical bonds with the coating matrix, significantly enhancing the mechanical properties and durability of the coating.

[0041] Furthermore, the method for preparing hollow mesoporous silica nanocapsules in step S3 includes the following steps: S3.1 Take 10 mL of a polystyrene (PS) nanosphere aqueous dispersion with an average particle size of 200 nm, monodisperse, and a solid content of 5 wt%, add 40 mL of deionized water to dilute, ultrasonically disperse at 200 W for 10 min, then add 0.15 g of cetyltrimethylammonium bromide (CTAB), stir and dissolve at 25 °C for 30 min, and use it as the template solution for subsequent coating. S3.2. Transfer the above template solution to a 250mL three-necked flask and place it in a 35℃ constant temperature water bath with magnetic stirring. Adjust the pH to 10.0±0.2 with 28wt% concentrated ammonia. Dissolve 1.8mL of tetraethyl orthosilicate (TEOS) in 4mL of anhydrous ethanol and add it dropwise to the three-necked flask at a rate of 0.15mL / min. Simultaneously, maintain the pH of the system at 9.5–10.0 by adding ammonia. Continue the reaction for 4 hours after the addition is complete. After the reaction is complete, collect the precipitate by centrifugation at 10000rpm for 10min, wash it 3 times with deionized water and 2 times with anhydrous ethanol. Vacuum dry at 60℃ for 12h to obtain PS@mSiO2 core-shell powder; then add 1.5mL of tetraethyl orthosilicate dropwise at a rate of 0.2mL / min, while simultaneously adding ammonia to maintain the pH at 9.5–10.0. Continue the reaction for 4 hours, during which tetraethyl orthosilicate hydrolyzes and condenses on the surface of the PS spheres to form a mesoporous silica shell. S3.3 Place the dry powder in a crucible and put it in a muffle furnace. Procedurally raise the temperature in air atmosphere: from room temperature to 300℃ at 2℃ / min and hold for 1h; then raise the temperature to 500℃ at 1℃ / min and hold for 4h to completely oxidize the PS template; let the furnace cool naturally to room temperature to obtain hollow mesoporous silica nanocapsules (HmSiO2). S3.4. Take 0.5g of calcined HmSiO2 capsules and ultrasonically disperse them in 15mL of anhydrous ethanol. Add 0.8g of perfluoropolyether (PFPE) and magnetically stir for 30min to form a suspension. Transfer the suspension to a round-bottom flask and evaporate it under a rotary evaporator at 40℃ water bath and -0.09MPa vacuum until the solvent is nearly dry. Add 5mL of anhydrous ethanol and repeat the above vacuum permeation process once to ensure that PFPE fully enters the hollow cavity and mesoporous channels. After permeation, redisperse the powder in n-hexane and centrifuge at 10000rpm for 5min to wash away excess PFPE on the surface. Repeat the n-hexane washing twice. Air dry in a fume hood for 1h, then vacuum dry at 40℃ for 4h to obtain hollow mesoporous silica nanocapsules loaded with the repair solution.

[0042] Specifically, monodisperse polystyrene (PS) nanospheres with uniform particle size (200 nm) were selected as sacrificial templates, fundamentally ensuring the high uniformity of the final hollow silica capsule size. This is the basis for the consistency of the loading-release behavior of the subsequent repair solution. A solid content of 5 wt% and a dosage of 10 mL provide a sufficient number of templates for subsequent encapsulation, while dispersing them to a total volume of 50 mL, avoiding excessive crowding of microspheres that could lead to adhesion during encapsulation. Adding 0.15 g of cetyltrimethylammonium bromide (CTAB) and stirring to dissolve it, the CTAB concentration being higher than its critical micelle concentration, will spontaneously self-assemble on the surface of the PS spheres and in the bulk solution to form worm-like micelles. These micelles act as mesoscopic structure templates; during the subsequent hydrolysis and polycondensation of tetraethyl orthosilicate, silicon species are deposited around the micelles, and after calcination and removal, ordered mesoporous channels remain.

[0043] The reaction system maintains a weakly alkaline environment of pH 9.5–10.0, precisely controlled by ammonia. Within this pH range, the hydrolysis and polycondensation rates of tetraethyl orthosilicate (TEOS) reach a good equilibrium, which is conducive to heterogeneous nucleation on the template surface and the growth of a continuous shell, while effectively inhibiting the formation of solid silica spheres through homogeneous nucleation in the solution.

[0044] The calcination of the dried PS@mSiO2 core-shell powder in a muffle furnace is a crucial turning point in this process. A stepped heating regime was adopted: first, the temperature was increased to 300℃ at a rate of 2℃ / min and held for 1 hour to allow the CTAB micelles to initially decompose, while simultaneously allowing the fragile carbon chain framework to slowly break down and escape, avoiding concentrated vaporization that could impact the shell wall; then, the temperature was increased even more slowly to 500℃ at a rate of 1℃ / min and held for 4 hours. During this stage, the PS core was completely thermally oxidized and decomposed into CO2 and water vapor, which were slowly released from the body through mesoporous channels. Under the oxidizing atmosphere at 500℃, PS was completely removed without significant carbon residue, and CTAB was also completely removed, releasing interconnected mesoporous channels. The spaces previously occupied by PS were transformed into regular hollow cavities, thus obtaining hollow mesoporous silica nanocapsules (HmSiO2) with intact structure and no cracks in the shell. The slow, programmed heating is the core guarantee for maintaining the integrity of the shell.

[0045] After calcination, the interior of HmSiO2 is now in a hollow state. The capsules are uniformly dispersed in anhydrous ethanol. Utilizing the excellent wettability of ethanol on mesoporous silica, the perfluoropolyether (PFPE) is carried by ethanol molecules and rapidly penetrates the hydrophilic mesoporous channels. During rotary evaporation under a vacuum of -0.09 MPa, the gas in the channels and hollow cavities is extracted, creating a negative pressure. Ethanol is replenished, and the vacuum operation is repeated. Utilizing the cyclic effect of "solvent expansion of channels – negative pressure suction – solvent evaporation and concentration," PFPE molecules are driven to efficiently enter the capsule cavity and fill most of the pore space. The amount of PFPE used is 1.6 times the mass of the capsule (0.8 g to 0.5 g capsules). This excess feed combined with surface washing ensures saturated loading while avoiding excessive surface residue. Finally, vacuum drying at 40°C gently removes the ethanol without damaging the properties of the perfluoropolyether.

[0046] The preparation method of this hollow mesoporous silica nanocapsule uses monodisperse PS microspheres as sacrificial templates and CTAB as a mesoporous template agent. Through pH-stable sol-gel coating, vacuum negative pressure permeation encapsulation, and slow heating calcination, nanocapsules with uniform particle size, intact shells, hollow cavities, and mesoporous channels were successfully prepared. These capsules can efficiently load perfluoropolyether repair fluid and can controllably release it when the coating is worn, providing a key storage and transport carrier for the long-term self-repair of the coating.

[0047] To further prevent leakage of perfluoropolyether, the preparation method of hollow mesoporous silica nanocapsules also includes the following steps: S3.5. Disperse the loaded capsules in 10 mL of anhydrous n-hexane, add 0.08 mL of perfluorodecyltrimethoxysilane (PFDTMS), and mix thoroughly. Refrigerate at 60 °C for 2 h under N2 protection. Reaction mechanism: The silanol groups generated from the hydrolysis of the methoxy groups in PFDTMS condense with the silanol groups on the inner wall of the capsule's mesoporous channels, forming a comb-like perfluoroalkyl "fence" at the pore opening. After the reaction, centrifuge at 10000 rpm for 10 min, wash twice with n-hexane, dry under vacuum at 40 °C for 12 h, and store in a sealed container.

[0048] Specifically, perfluorodecyltrimethoxysilane is used for hydrophobic sealing in hexane. After hydrolysis, the silanol groups of perfluorodecyltrimethoxysilane undergo a condensation reaction with the silanol groups on the inner wall of the capsule mesoporous channel to form a "molecular lock" that is tightly grafted at the pore entrance. This effectively prevents the perfluoropolyether in the inner cavity from spontaneously flowing out during coating preparation or long-term storage, ensuring a high retention rate of the repair solution. Moreover, this sealing is not permanently welded. When the coating wears and generates shear force or heat, the physically bonded sealing layer can be destroyed, releasing the perfluoropolyether again. This achieves the ideal switching effect of no leakage under normal conditions and fast response when needed.

[0049] Furthermore, the preparation method of Bacillus subtilis spore microcapsules in step S3 includes the following steps: S3.6 Preparation of bacterial strain and culture medium: Bacillus subtilis CICC10014. Nutrient broth (LB): 10 g / L peptone, 3 g / L beef extract, 5 g / L NaCl, pH 7.2. Nutrient agar slant: The above formula with 15 g / L agar added. Sporulation induction medium (DSM): Nutrient broth with 0.01 g / L MnSO4·H2O and 0.01 g / L CaCl2 added, pH 7.0.

[0050] S3.7. Resuscitation of lyophilized powder: Under aseptic conditions, use a sterile pipette to add 0.5 mL of nutrient broth culture medium to the lyophilization tube, and gently shake to dissolve the bacterial powder into a suspension. Transfer the suspension to a test tube containing 5 mL of nutrient broth culture medium and incubate at 37°C for 24 hours as the resuscitation solution.

[0051] S3.8 Preparation of slant culture: Dissolve the nutrient agar medium by heating, dispense into test tubes, autoclave at 121℃ for 20 min, and solidify by tilting while hot to prepare slant culture medium. Take 0.1 mL of resuscitation solution and spread it evenly on the surface of the slant, incubate at 37℃ for 24 h to obtain fresh slant culture. Store the slant at 4℃ for later use.

[0052] S3.9 Seed culture and expansion culture: Pick a loopful of bacterial growth from a fresh slant and inoculate it into 50 mL of nutrient broth. Incubate at 37°C and 200 rpm for 12 h to obtain the seed culture. Inoculate 5 mL of the seed culture into 500 mL of nutrient broth and incubate at 37°C and 200 rpm for 24 h to obtain a high-density vegetative culture medium.

[0053] S3.10. Spore induction: Centrifuge the culture medium at 5000 rpm for 10 min and collect the bacterial pellet. Wash once with sterile physiological saline and resuspend in 500 mL of DSM induction medium. Incubate at 37°C and 200 rpm for 48 h. Examine under a microscope every 12 h. Terminate the culture when the spore formation rate is >95%.

[0054] S3.11. Spore purification: Centrifuge the culture medium at 8000 rpm and 4℃ for 15 min, and discard the supernatant. Wash the precipitate three times with sterile deionized water. Add 50 mL of lysozyme solution (1 mg / mL, dissolved in Tris-HCl buffer, pH 8.0), and incubate at 37℃ for 1 h to lyse any remaining vegetative cells. Centrifuge again at 8000 rpm and 4℃ for 15 min, and wash three times with deionized water to obtain a pure spore suspension, which is then stored at 4℃ for later use.

[0055] S3.12. Preparation of wall material solutions: Sodium alginate solution: Dissolve 1.5g sodium alginate in 100mL deionized water, stir in a 60℃ water bath for 2h, sterilize at 121℃ for 20min, and cool to room temperature. Chitosan solution: Dissolve 0.5g chitosan in 100mL 1% (v / v) glacial acetic acid aqueous solution, stir overnight, filter to remove impurities, and sterilize at 121℃ for 20min.

[0056] S3.13. Core-wall material mixing and preparation of spray-drying precursor: Under aseptic conditions, take 50 mL of sodium alginate solution and add 10 mL of the spore suspension obtained in step S3.11, and mix with magnetic stirring (200 rpm, 10 min). Slowly add 50 mL of chitosan solution and 0.5 mL of Tween-80, and continue stirring for 30 min to obtain the spray-drying precursor mixture. This step forms an aqueous dispersion of a polyelectrolyte complex—sodium alginate (anionic) and chitosan (cationic) form a microgel network through electrostatic bonding, with spores uniformly embedded within it; Tween-80, as a nonionic surfactant, further disperses the spores, reduces interfacial tension, and prevents droplet aggregation of the spray-drying precursor, which is beneficial for obtaining uniform particle size in subsequent spray drying.

[0057] S3.14. Spray dry the spray-drying precursor mixture obtained in step S3.13: inlet air temperature 160℃, outlet air temperature 80-90℃, feed rate 5mL / min, atomization pressure 0.2MPa, nozzle diameter 0.7mm. Collect the powder. Dry the collected powder in a vacuum dryer at room temperature for 24h. The resulting pale yellow powder is Bacillus subtilis spore microcapsules.

[0058] Specifically, through vegetative growth, the bacterial population is rapidly increased using seed culture, and high-density vegetative cells are obtained through nutrient broth culture to induce spore formation. Lysozyme can specifically hydrolyze peptidoglycan in the bacterial cell wall, but has no effect on the spore shell. It can completely lyse vegetative cells that have not formed spores, increasing the spore purity to >95%. The spore suspension is then obtained by centrifugation at 8000 rpm and 4℃ for 15 min. The low temperature avoids heat damage to the spores during centrifugation and precipitates the spores. At the same time, cell debris generated by lysis is removed.

[0059] Sodium alginate (polyanionic) and chitosan (polycationic) electrostatically combine in aqueous solution to form a dense polyelectrolyte complex network. The spore suspension is pre-dispersed in a sodium alginate solution, followed by the slow droplet addition of a chitosan solution, resulting in the formation of a microgel layer on the spore surface. Tween-80, as a nonionic surfactant, reduces the water-air interfacial tension, aiding in the uniform dispersion of spores in the viscous wall material solution and preventing uneven particle size and nozzle clogging caused by droplet aggregation before spraying.

[0060] By immediately spray-drying the above mixture, the internal temperature of the microcapsules is much lower than the inlet air temperature due to the heat absorption of water evaporation, and the spores can maintain a high survival rate. The powder in the cyclone separator is then collected to obtain Bacillus subtilis spore microcapsules.

[0061] The method for preparing Bacillus subtilis spore microcapsules involves two steps: high-purity spores are obtained through culture, encapsulation with sodium alginate / chitosan composite wall material, and rapid microencapsulation via spray drying. This method successfully produces spore microcapsules that are resistant to organic solvents, high temperatures, and water-activated sequential release. During the coating's service life, the spores germinate and continuously secrete surfactants, forming a renewable chemical anti-fouling barrier that complements the physical repair of perfluoropolyether, significantly extending the actual service life of the coating.

[0062] Characterization and performance testing of durable superhydrophobic coatings for sanitary ware interiors: (1) such as Figure 1 As shown, the coating sample was characterized by scanning electron microscopy (SEM). After being attached to conductive carbon tape and sputtered with gold, the coating morphology was observed under the SEM. The morphology was rough, and a large number of particles were visible.

[0063] (2) such as Figure 2 As shown, the contact angle test was conducted using the seated drop method. The droplet was placed stably on the coating surface, and after the droplet stabilized for 10 seconds, the contact angle was calculated by fitting the Young-Laplace equation using the instrument's built-in software. The contact angle of the durable superhydrophobic coating can reach 168.732°.

[0064] The standard Young-Laplace equation takes the form of: For a stationary droplet placed on a solid surface (commonly referred to as the seated drop method), its profile is described by the following equation: ; Where ΔP: pressure difference across the curved liquid surface (internal pressure of the droplet minus external pressure); γ: surface tension of the liquid (known parameter); R1, R2: two principal radii of curvature of the droplet surface at a certain point.

[0065] (3) Flushing abrasion test, used to simulate the long-term scouring and abrasion of the coating by water flow and hard particles in water during actual use of the toilet. The test device is a self-made circulating flushing abrasion test machine, mainly including: a water tank (50L), a variable frequency water pump (adjustable flow rate), a nozzle (simulating the flushing hole of a toilet, 10mm in diameter), a sample holder, a circulation pipeline and a filter screen. The flushing flow rate is 10L / min (simulating the flushing intensity of the toilet). The abrasive medium is 200-mesh quartz sand (particle size about 75μm), added to the water at a concentration of 0.5g / L. The sample is continuously flushed, each flush lasting 10s, with an interval of 30s (simulating the actual flushing interval). A total of 2000 flushes are accumulated. After every 200 flushes, the test is stopped, the sample is taken out, the surface is gently rinsed with deionized water to remove residual sand particles, and then air-dried at room temperature. The contact angle of the sample surface is tested. The results are as follows. Figure 3 As shown, after 2000 cycles of abrasion with sand and water, the contact angle of Example 1 remained at 164°, far exceeding the superhydrophobic threshold of 150°. This indicates that the PFPE repair fluid in the middle layer of the coating can continuously replenish the surface liquid film through capillary action, effectively resisting the erosion of hard particles.

[0066] like Figure 5 As shown, control group 1 (no self-healing): only the base layer and top layer were sprayed according to steps two and four of Example 1, without applying the middle layer.

[0067] After 2000 water rinses, the contact angle of control group 1 dropped sharply to approximately 98°, indicating complete failure. Control group 1 consisted only of a bottom layer and a surface layer, lacking a porous liquid reservoir structure in the middle layer. Under the scouring of sand-containing water, the surface lubricant film was rapidly worn away and could not be replenished. Therefore, the superhydrophobic properties of control group 1 decreased sharply in the initial stage of water rinsing, with the contact angle only reaching 98° after 2000 rinses, completely losing its self-cleaning ability. This proves that traditional superhydrophobic coatings without a repair fluid reserve and replenishment mechanism cannot resist long-term mechanical wear.

[0068] like Figure 6 As shown, control group 2 (without triboelectric particles): BaTiO3 nanoparticles and graphene nanosheets were not added to the bottom layer formulation, and the rest was the same as in Example 1.

[0069] Although control group 2 contained the repair solution, it lacked an electric field to stimulate the metabolic activity of Bacillus subtilis, resulting in a contact angle of 154°. This indicates that the repair speed relying solely on passive capillary fluid supply is slow, and the liquid film replenishment in some areas is not timely. Control group 2 contained a complete middle porous structure and PFPE repair solution, but lacked BaTiO3 piezoelectric particles and a graphene conductive network in the bottom layer. Therefore, it could not generate a microcurrent during rinsing, thus losing the promoting effect of the electric field on Bacillus subtilis spore germination. Although PFPE in the middle pores could still slowly seep out through capillary action, the lack of electric field stimulation resulted in a longer spore germination time and lower surfactant secretion, leading to insufficient repair efficiency for surfactant contamination and micro-wear. Therefore, after 2000 rinsing cycles, the contact angle of control group 2 decreased to 155°, while the roll-off angle increased, indicating that passive capillary fluid supply alone is insufficient to maintain long-term stable superhydrophobic properties.

[0070] like Figure 7 As shown, control group 3 (without bio-microcapsules): Bacillus subtilis spore microcapsules were not added to the middle layer formulation, and the rest was the same as in Example 1.

[0071] Control group 3 performed slightly better than control group 2, with a contact angle of 161°, but still worse than Example 1, indicating that the surfactants secreted by the bio-microcapsules have an auxiliary effect in maintaining long-term superhydrophobicity. Control group 3 contained a complete BaTiO3 piezoelectric layer and a PFPE reservoir layer, but did not contain Bacillus subtilis spore microcapsules. Therefore, although the piezoelectric microcurrent was present, it could not accelerate spore germination to produce surfactants. When the coating was contaminated by surfactants (such as toilet cleaner residue) or when long-term wear caused partial loss of PFPE, the chemical repair effect of bio-surfactants was lacking. Although the PFPE liquid film could still provide some superhydrophobicity, it could not repair areas wetted by surfactants. After 2000 flushes, the contact angle was 161°, slightly lower than 164° in Example 1, and the roll-off angle was also larger. This proves that the synergistic secretion of bio-surfactants is an important supplement to maintaining the coating's long-term anti-fouling and self-repairing capabilities.

[0072] (4) Surfactant contamination test, used to evaluate the coating's tolerance to surfactants in everyday cleaning agents. The test reagent is sodium dodecyl sulfate (SDS), prepared as a 0.1 wt% aqueous solution with deionized water. The coating sample is completely immersed in the 0.1 wt% SDS aqueous solution and left to stand at room temperature (25±2℃) for 1 hour. The sample is then removed and gently rinsed three times (100 mL each time) with deionized water to remove any residual SDS solution from the surface. The surface moisture is dried with nitrogen gas, and the contact angle is tested after being left at room temperature for 30 minutes. Figure 4As shown, after soaking in 0.1% SDS solution for 1 hour, the contact angle of Example 1 still reached 153°, maintaining a superhydrophobic state. This is because the surface anchoring liquid film itself has extremely low surface energy, and the surfactants secreted by spore germination can repel external surfactants, forming an anti-fouling barrier.

[0073] like Figure 4 as well as Figure 8-10 As shown, control group 1 had a contact angle of 82°, indicating complete hydrophilicity. Control group 1 consisted only of a bottom layer and a surface layer, lacking a middle liquid reservoir structure and bio-microcapsules. Although the surface anchoring liquid film had extremely low surface energy, after immersion in a 0.1% SDS solution for 1 hour, SDS molecules gradually adsorbed and partially replaced the fluorocarbon chains on the liquid film surface through hydrophobic interactions, leading to the destruction of the liquid film structure, an increase in surface energy, a drop in the water contact angle to 82°, and a complete loss of superhydrophobic properties. Due to the lack of any repair mechanism, this damage was irreversible. This indicates that traditional superhydrophobic coatings without self-healing capabilities are extremely sensitive to surfactant contamination, and once contact occurs, they permanently fail.

[0074] The contact angle of control group 2 was 142°, close to but slightly below the 150° threshold, indicating that the resistance of the liquid film to surfactants is limited without bioremediation. Control group 2 contained a complete mesoporous structure and PFPE remediation solution, but lacked BaTiO3 piezoelectric particles and a graphene conductive network. Therefore, no microcurrent could be generated during immersion, and spore germination and surfactant secretion could not be accelerated by the electric field. Although the PFPE liquid film in the mesoporous channels could still partially replenish the surface layer through capillary action, the lack of chemical remediation by biosurfactants made it difficult for the SDS-contaminated liquid film area to recover to a low surface energy state. Furthermore, spore germination was slow without an electric field. Therefore, the contact angle of control group 2 only recovered to 142°, close to but slightly below the 150° superhydrophobic threshold, indicating that the resistance to surfactants by relying solely on the physical PFPE liquid film is limited, and bioremediation is required to achieve a stable superhydrophobic state.

[0075] The contact angle of control group 3 was only 98°, indicating a lack of synergistic effect from biosurfactants, and the coating could not recover after surfactant contamination. Control group 3 contained a complete piezoelectric layer (BaTiO3 + graphene) and a PFPE reservoir layer, but lacked Bacillus subtilis spore microcapsules. Therefore, although piezoelectric microcurrents were present, they could not generate surfactants. When SDS molecules adsorbed and contaminated the surface liquid film, the physical displacement effect of PFPE alone was insufficient to completely remove SDS molecules, and PFPE itself did not have the ability to actively repel or neutralize surfactants. The surface energy of the contaminated liquid film area increased, and water droplets were easily pinned. The contact angle of only 98° indicated a lack of chemical repair effect from biosurfactants, and the coating could not effectively recover after surfactant contamination.

[0076] Example 2: Actual spraying process for large areas of unglazed ceramic blanks: The unglazed ceramic blank is fixed on a rotating worktable, and a six-axis spraying robot is used to apply the coating according to the following procedure: (1) Pre-processing station: The material enters the automatic sandblasting chamber via a conveyor belt. The sandblasting medium is 60-mesh white corundum. The spray gun moves at a speed of 200 mm / s. The process involves high-pressure air purging followed by plasma jet treatment (power 1 kW, processing speed 50 mm / s).

[0077] (2) Base coat spraying station: Prepare the base coat according to the proportions in step two of Example 1, and use an air spray gun array (6 guns, 15cm spacing). The spraying parameters are the same as in Example 1, with a wet film thickness of 60-80μm. Then, enter the infrared drying tunnel (80℃ / 20min + 120℃ / 20min).

[0078] (3) Intermediate layer spraying station: Prepare the intermediate coating according to the proportions in step three of Example 1, and use an airless spray gun (1.5 mm diameter, 0.6 MPa pressure) to spray a wet film thickness of 100-120 μm → infrared drying tunnel (60℃ / 10 min surface drying) → enter the hot air circulation oven (280℃, heat preservation for 1 h, nitrogen protection).

[0079] (4) Surface grouting station: Prepare the lubricant according to the proportions in step four of Example 1, and spray it using an ultrasonic atomization spraying system (frequency 40kHz, atomized particle size 10μm) → centrifugal drying station (ceramic blank inverted, 500rpm, 8min) → allow it to stand at room temperature for 2h to cure.

[0080] The production equipment and parameters in this embodiment differ from those in Embodiment 1, but the core chemical formula and key process principles remain unchanged. This ensures that this embodiment can achieve the same excellent performance as Embodiment 1.

[0081] This embodiment is a streamlined, automated, and dynamic preparation method for industrial production, which achieves continuous operation through conveyor belts, spray gun arrays, and infrared / hot air continuous furnaces; and all key chemical formulations and film-forming mechanisms are completely consistent with those in Example 1. Therefore, the coating prepared in Example 2 can reproduce the excellent performance reported in Example 1.

[0082] The second aspect of this invention also discloses a durable superhydrophobic coating, which is prepared by the method of preparing a durable superhydrophobic coating for sanitary ware as described in Example 1 or Example 2. This coating can be effectively applied to fields such as waterless / water-saving urinals, water-saving toilets, shower room glass, bathtubs, and ceramic sanitary ware. At the same time, with its comprehensive properties of long life, wear resistance, self-healing, and resistance to chemical pollution, it can also be widely extended to industrial fields with stringent durability requirements, such as marine corrosion and fouling prevention, pipeline drag reduction, anti-icing and de-icing, self-cleaning buildings, and oil-water separation.

[0083] The core of this invention lies in the synergistic effect of a multi-layered structure, achieving both superhydrophobicity and active intelligent response. The scientific principles are explained below in stages: (1) Superhydrophobic and Superlubricating Principle (Surface Layer): The surface layer is composed of a PFPE / OH-PDMS mixed liquid film, which has extremely low surface energy and excellent chemical inertness. When water or dirt comes into contact with the surface, a liquid-liquid interface is formed due to the presence of the liquid film, rather than a traditional solid-liquid interface. According to Young's equation and the sliding angle theory, the adhesion work of the liquid-liquid interface is extremely low, so the water droplet contact angle is >165°. At the same time, the hydroxyl groups of OH-PDMS are covalently bonded to the active groups of the middle fluorinated polyurethane, so that the lubricating liquid film will not be washed away by the water flow.

[0084] (2) Wear Self-Repair Principle (Middle Layer): The middle layer contains three-dimensional interconnected channels (formed by the thermal decomposition of PMMA microspheres) and hollow SiO2 nanocapsules encapsulating PFPE. When the surface liquid film is locally damaged by hard particles, the PFPE stored freely in the channels automatically seeps to the surface through capillary action, reforming the lubricating liquid film. When the wear depth reaches the interior of the middle layer, the nanocapsules rupture, releasing PFPE from the hollow SiO2 nanocapsules. Due to the high compatibility between PFPE and the fluorinated polyurethane of the channel walls, the repair liquid spreads rapidly and replenishes the reservoir. This process requires no external energy and can be repeated dozens of times until the capsules are depleted.

[0085] (3) Synergistic Repair Principle of Bioactive Factors (Spore Microcapsules Added to the Middle Layer): When the wear depth exceeds half the thickness of the middle layer (e.g., a sharp object scratches into the middle layer), Bacillus subtilis spore microcapsules are exposed. The spores can withstand heat treatment at 280℃ and long-term storage in a dry dormant state. Once exposed to flushing water, water molecules slowly penetrate through the calcium alginate wall material. After sensing moisture and a suitable temperature (20-40℃), the spores germinate into vegetative cells within 2-4 hours. The vegetative cells utilize the residual organic carbon source (trace degradation products of fluorinated polyurethane or organic matter in the air) within the pores for metabolism, secreting surfactants. Surfactants are cyclic lipopeptides with a critical micelle concentration (CMC) of approximately 10 μm, capable of drastically reducing the surface tension of water from 72 mN / m to below 27 mN / m. These surfactant molecules diffuse to the coating surface, adsorb onto the worn area, forming a new low-energy interface, repairing the decrease in hydrophobicity caused by surfactant contamination or mechanical damage. Meanwhile, a weak electric current (from the piezoelectric effect of BaTiO3) can stimulate the metabolic activity of Bacillus subtilis. Several hours later, as water evaporates or nutrients are depleted, the vegetative cells reform spores and enter the next dormant state, achieving a reversible cycle.

[0086] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a durable superhydrophobic coating for sanitary ware, characterized in that, Includes the following steps: S1. Matrix pretreatment: Take the inner wall blank of the sanitary ware, clean and dry it, use a sandblasting machine to roughen the surface of the blank to make the surface roughness Ra reach 3-5μm, and then use a plasma cleaning machine to introduce hydroxyl active groups. S2. Preparation and spraying of stress buffer and triboelectric underlayer: By mass fraction, 100 parts of hydroxyl-terminated polydimethylsiloxane, 20 parts of isocyanate-modified nano-silica, 15 parts of barium titanate nanoparticles, and 3 parts of graphene nanosheets were taken. The total solid content was adjusted to 40 wt% by adding a solvent of butyl acetate and isopropanol. The mixture was then mixed and ultrasonically dispersed in a planetary stirrer to obtain a mixture. The mixture was then uniformly sprayed onto the surface of the pre-treated blank in step S1 using an air spray gun, increasing the wet film thickness to 60 μm. After spraying, the blank was placed in an oven and cured at 80°C for 2 hours. Then, the temperature was raised to 120°C and cured for another hour to obtain a stress buffer and triboelectric underlayer with a dry film thickness of 35-45 μm. S3. Preparation and spraying of porous liquid storage intermediate layer: By weight, take 100 parts of fluorinated polyurethane solution, 40 parts of polymethyl methacrylate microspheres, 10 parts of hollow mesoporous silica nanocapsules, 5 parts of Bacillus subtilis spore microcapsules, and 0.5 parts of dibutyltin dilaurate. Add a mixed solvent of xylene and cyclohexanone at a volume ratio of 7:3 to adjust the total solid content to 35 wt%, and magnetically stir in an ice-water bath for 20 min. Apply the mixture to the stress buffer and triboelectric substrate that has been cured in step S2 using a high-pressure airless spray gun to form a wet film. The thickness was increased to 100 μm; after spraying, it was placed in an oven and dried at 60 °C; then the preform was transferred to a muffle furnace and nitrogen gas was introduced to protect the -NCO groups in the fluorinated polyurethane; the temperature was increased from 60 °C to 120 °C at a rate of 1 °C / min and held for 2 h; then the temperature was increased to 250 °C at a rate of 0.5 °C / min and held for 2 h; the power to the muffle furnace was turned off and the preform was allowed to cool naturally to room temperature under a nitrogen gas flow; a preform with a porous liquid storage middle layer was obtained, and the thickness of the resulting dry film of the middle layer was about 50-70 μm. S4. Pouring of the anchoring lubricant surface layer: Perfluoropolyether with a molecular weight of 2000 and a density of 1.82 g / cm³ was mixed with hydroxyl-terminated dimethyl silicone oil at a mass ratio of 3:

1. Dibutyltin dilaurate was added to make its concentration in the mixture 0.3 wt%. The mixture was then uniformly sprayed onto the porous liquid reservoir layer surface prepared in step S3 using a low-pressure spray gun in a fine mist, until the surface was visibly wet but without liquid accumulation. The blank was then centrifuged in a benchtop centrifuge to remove excess liquid and recover it. The centrifuged blank was then transferred to an oven and heated at 80°C under nitrogen protection. The hydroxyl groups of OH-PDMS reacted with the residual isocyanate groups on the middle layer surface to form covalent bonds. After removal and standing, the final surface lubricant film thickness was approximately 300-500 nm, resulting in a durable superhydrophobic coating.

2. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 1, characterized in that, In step S1, the sandblasting machine uses 60-mesh white corundum and a pressure of 0.4 MPa to roughen the surface of the blank.

3. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 2, characterized in that, In step S2, the barium titanate nanoparticles have a particle size of 100-200 nm, the graphene nanosheets have a thickness of <5 nm and a sheet diameter of 1-5 μm, the air spray gun has a nozzle diameter of 1.0 mm, an air pressure of 0.3 MPa, and a spraying distance of 20 cm.

4. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 3, characterized in that, In step S3, the solid content of the fluorinated polyurethane solution is 30%, the particle size of the polymethyl methacrylate microspheres is 5-10 μm, the nozzle diameter of the high-pressure airless spray gun is 1.2 mm, the air pressure is 0.5 MPa, and the spraying distance is 25 cm.

5. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 4, characterized in that, In step S4, the low-pressure spray gun has a nozzle diameter of 0.5 mm and an air pressure of 0.1 MPa. After the blank is taken out, it is left to stand for 2 hours at a room temperature of 25℃±2℃ and a relative humidity of 50%±5%.

6. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 1, characterized in that, In step S2, the method for preparing the isocyanate-modified nano-silica includes the following steps: S2.1 Weigh 10.0g of hydrophilic nano-silica with an average particle size of 20nm and place it in a 200mL beaker. Dry it in a vacuum drying oven at 120℃ for 12h to remove the physically adsorbed water on the surface. S2.2 Under nitrogen protection, add 200 mL of anhydrous toluene to a 500 mL three-necked flask and start stirring; add 10.0 g of dried nano-silica and sonicate for 15 min to form a uniform suspension; S2.

3. Add 15.0 g of toluene diisocyanate to a constant pressure dropping funnel. Under a nitrogen stream, slowly add toluene diisocyanate to the flask at room temperature (25°C) at a dropping rate of 1 mL / min, while maintaining stirring during the addition. The temperature of the reaction solution will naturally rise to 30-35°C due to exothermic reaction. After the addition is complete, heat the oil bath to 110°C and maintain reflux for 6 hours. During the reaction, the silanol groups on the surface of nano-silica react with the isocyanate groups of toluene diisocyanate to generate a Si–O–C(=O)–NH– structure. S2.4 After the reaction is complete, allow it to cool naturally to room temperature. Transfer the reaction solution to a centrifuge tube and centrifuge at 12,000 rpm for 30 min. Discard the supernatant and wash the precipitate twice with anhydrous toluene and once with anhydrous ethanol to remove unreacted toluene diisocyanate and byproducts. S2.

5. Place the washed product in a vacuum drying oven and dry it at 60℃ and -0.09MPa for 12 hours to obtain the powder, which is the isocyanate modified nano silica.

7. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 1, characterized in that, In step S3, the method for preparing the hollow mesoporous silica nanocapsules includes the following steps: S3.1 Take 10 mL of polystyrene nanosphere aqueous dispersion with an average particle size of 200 nm, monodisperse and solid content of 5 wt%, add 40 mL of deionized water to dilute, ultrasonically disperse at 200 W for 10 min, then add 0.152 g of cetyltrimethylammonium bromide, stir and dissolve at 25 °C for 30 min, and use as template solution for subsequent coating. S3.2 Transfer the above template solution to a 250mL three-necked flask, place it in a 35℃ constant temperature water bath, stir magnetically, and adjust the pH to 10.0±0.2 with concentrated ammonia; dissolve 1.8mL of tetraethyl orthosilicate in 4mL of anhydrous ethanol, and add it dropwise to the three-necked flask at a rate of 0.15mL / min; at the same time, maintain the pH of the system at 9.5–10.0 by adding ammonia; after the addition is complete, continue the reaction for 4h; after the reaction is complete, collect the precipitate by centrifugation at 10000rpm for 10min, wash it 3 times with deionized water and 2 times with anhydrous ethanol; vacuum dry at 60℃ for 12h to obtain PS@mSiO2 core-shell powder; then add 1.5mL of tetraethyl orthosilicate dropwise at a rate of 0.2mL / min, while adding ammonia to maintain the pH at 9.5-10.0, and continue the reaction for 4h, during which tetraethyl orthosilicate hydrolyzes and condenses on the surface of PS spheres to form a mesoporous silica shell; S3.3 Place the dry powder in a crucible and put it in a muffle furnace. Procedurally raise the temperature in air atmosphere: from room temperature to 300℃ at 2℃ / min and hold for 1h; then raise the temperature to 500℃ at 1℃ / min and hold for 4h to completely oxidize the PS template; let the furnace cool naturally to room temperature to obtain hollow mesoporous silica nanocapsules (HmSiO2). S3.4 Take 0.5g of calcined HmSiO2 capsules and ultrasonically disperse them in 15mL of anhydrous ethanol; add 0.8g of perfluoropolyether and magnetically stir for 30min to form a suspension; transfer the suspension to a flask and evaporate it under a vacuum of -0.09MPa at 40℃ in a rotary evaporator until the solvent is nearly dry; add 5mL of anhydrous ethanol and repeat the above vacuum permeation process once to ensure that PFPE fully enters the hollow cavity and mesoporous channels; after permeation, redisperse the powder in n-hexane, centrifuge at 10000rpm for 5min to wash away excess PFPE on the surface, and repeat the n-hexane washing twice; air dry in a fume hood for 1h, and then vacuum dry at 40℃ for 4h to obtain hollow mesoporous silica nanocapsules loaded with repair solution.

8. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 7, characterized in that, The method for preparing the hollow mesoporous silica nanocapsules further includes the following steps: S3.5 Disperse the loaded capsules in 10 mL of anhydrous n-hexane, add 0.08 mL of perfluorodecyltrimethoxysilane, and mix well; under N2 protection, reflux at 60 °C for 2 h; reaction mechanism: the silanol groups generated after the methoxy group of perfluorodecyltrimethoxysilane is hydrolyzed, condense with the silanol groups on the inner wall of the capsule mesoporous channels, forming a comb-like perfluoroalkyl "fence" at the pore opening; after the reaction, centrifuge at 10000 rpm for 10 min, wash twice with n-hexane, vacuum dry at 40 °C for 12 h, and store in a sealed container.

9. The method for preparing a durable superhydrophobic coating for sanitary ware according to claim 8, characterized in that, In step S3, the preparation method of the Bacillus subtilis spore microcapsules includes the following steps: S3.6 Preparation of bacterial strain and culture medium: Bacillus subtilis CICC10014; Nutrient broth medium: 10 g / L peptone, 3 g / L beef extract, 5 g / L NaCl, pH 7.2; Nutrient agar slant medium: the above formula with 15 g / L agar added; Sporulation induction medium: nutrient broth with 0.01 g / L MnSO4·H2O and 0.01 g / L CaCl2 added, pH 7.0; S3.

7. Lyophilized powder resuscitation: Under aseptic conditions, use a sterile pipette to add 0.5 mL of nutrient broth culture medium to the lyophilized tube, and gently shake to dissolve the bacterial powder into a suspension; transfer the suspension to a test tube containing 5 mL of nutrient broth culture medium, and incubate in a 37℃ constant temperature incubator for 24 h to obtain the resuscitation solution. S3.8 Preparation of slant culture: Dissolve the nutrient agar medium by heating, dispense into test tubes, autoclave at 121℃ for 20 min, and solidify by tilting while hot to prepare slant culture medium; take 0.1 mL of resuscitation solution and spread it evenly on the surface of the slant, incubate at 37℃ for 24 h to obtain fresh slant culture; store the slant at 4℃ for later use. S3.9 Seed culture and expansion culture: Pick a loop of bacterial growth from a fresh slant and inoculate it into 50 mL of nutrient broth medium. Incubate at 37°C and 200 rpm for 12 h to obtain the seed culture. Inoculate 5 mL of the seed culture into 500 mL of nutrient broth medium and incubate at 37°C and 200 rpm for 24 h to obtain a high-density vegetative culture medium. S3.

10. Spore induction: Centrifuge the culture medium at 5000 rpm for 10 min and collect the bacterial pellet; wash once with sterile physiological saline and resuspend in 500 mL of DSM induction medium, and incubate at 37℃ and 200 rpm for 48 h; examine under a microscope every 12 h, and terminate the culture when the spore formation rate is >95%; S3.

11. Spore purification: Centrifuge the culture medium at 8000 rpm and 4℃ for 15 min, and discard the supernatant; wash the precipitate three times with sterile deionized water; add 50 mL of lysozyme solution, and incubate at 37℃ for 1 h to lyse the residual vegetative cells; centrifuge again at 8000 rpm and 4℃ for 15 min, and wash three times with deionized water to obtain a pure spore suspension, which is temporarily stored at 4℃ for later use. S3.

12. Preparation of wall material solutions: Sodium alginate solution: Dissolve 1.5g sodium alginate in 100mL deionized water, stir in a 60℃ water bath for 2h, sterilize at 121℃ for 20min, and cool to room temperature; Chitosan solution: Dissolve 0.5g chitosan in 100mL 1% (v / v) glacial acetic acid aqueous solution, stir overnight, filter to remove impurities, and sterilize at 121℃ for 20min. S3.13, Preparation of core-wall material mixing and spray-drying precursor: Under aseptic conditions, take 50 mL of sodium alginate solution, add 10 mL of spore suspension obtained in step S3.11, and mix with magnetic stirring; slowly add 50 mL of chitosan solution and 0.5 mL of Tween-80, and continue stirring for 30 min to obtain the spray-drying precursor mixture; this step forms an aqueous dispersion of polyelectrolyte complex—sodium alginate and chitosan form a microgel network through electrostatic bonding, in which spores are uniformly embedded; Tween-80, as a nonionic surfactant, further disperses spores, reduces interfacial tension, and prevents droplet aggregation of the spray-drying precursor, which is beneficial for obtaining uniform particle size in subsequent spray drying. S3.

14. Spray dry the spray-drying precursor mixture obtained in step S3.13: inlet air temperature 160℃, outlet air temperature 80-90℃, feed rate 5mL / min, atomization pressure 0.2MPa, nozzle diameter 0.7mm; collect the powder; dry the collected powder in a vacuum dryer at room temperature for 24h; the resulting light yellow powder is Bacillus subtilis spore microcapsules.

10. A durable superhydrophobic coating, characterized in that, It is prepared by the method for preparing a durable superhydrophobic coating for sanitary ware according to any one of claims 1 to 9.

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