Preparation method of super-infiltration nano coating

Abstract

The invention discloses a preparation method of an ultra-infiltration nano coating, and relates to the field of ultra-infiltration nano coatings, and the preparation method comprises the following steps: S1, base material pretreatment, S2, nano material dispersion liquid preparation, S3, coating: adopting an impregnation method, a spraying method or a spin-coating method to attach the nano material dispersion liquid prepared in the step S2 to the surface of the base material pretreated in the step S1, and S4, low-temperature curing to obtain the ultra-infiltration nano coating. And S5, surface modification: carrying out hydrophobic modification or hydrophilic modification on the base material subjected to low-temperature curing in the step S4 according to the type of the base material. The effect of enhancing the adhesive force of the base material and the coating is achieved through the means of pretreating the base material, it is ensured that nano particles of the dispersion liquid are always uniformly dispersed through preparation of the nano material dispersion liquid and the coating, coating is conducted through proper methods such as dipping, spraying and spin coating, and then low-temperature curing is conducted; the effect of constructing a stable porous nano-structure coating with excellent performance is achieved, and meanwhile, different requirements are met through multiple coating modes.

Description

Technical Field

[0001] The invention relates to the field of super-wetting nano coatings, and in particular to a preparation method of super-wetting nano coatings. Background Art

[0002] As various industries continue to increase their requirements for material performance, traditional materials can no longer meet the complex and diverse usage scenarios. In the construction field, the exterior walls of buildings have long faced problems such as rain erosion and dirt adhesion, and there is an urgent need for an efficient protective coating to extend the service life of the building and keep the appearance clean. In the medical industry, if the surface of medical devices can have antibacterial and easy-to-clean properties, the risk of cross-infection can be effectively reduced. Electronic equipment hopes to achieve waterproof and anti-fog through super-wetting coatings to improve equipment stability and reliability. Super-wetting nano-coating technology came into being. It can effectively solve the above-mentioned industry pain points by finely regulating nanomaterials and giving the coating special surface properties, so it has received widespread attention and research.

[0003] Although the existing super-wetting nano-coating technology has emerged due to the industry's urgent demand for high-performance materials, it has many shortcomings in practical applications. In the substrate pretreatment stage, there is a lack of universal and efficient treatment methods, and it is difficult to thoroughly clean the surface and increase active sites, which makes the coating easy to fall off, affecting the service life and function; when the nanomaterials are dispersed, the particles are easy to agglomerate, and a slight deviation in the ultrasonic treatment and the use of dispersants will cause uneven coating performance; in the low-temperature curing stage, the porosity and pore size distribution are difficult to accurately control, which reduces the application effect of the coating in oil-water separation, self-cleaning and other scenarios; surface modification is affected by many factors, the performance indicators are unstable, the photosensitizer effect is poor, and the self-cleaning ability is insufficient; at the same time, there is a lack of a complete quality inspection system, and the product quality fluctuates greatly. In addition, the coating has a single function and it is difficult to meet the needs of multi-functional integration. The waste of raw materials is serious and the cost is high, which hinders large-scale application. It is necessary to design a preparation method for super-wetting nano-coating to solve the above-mentioned problems. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method for preparing a super-wetting nano-coating to solve the problems in the above technical solution that the coating has a single function, is difficult to meet the requirements of multi-functional integration, has serious waste of raw materials and is costly.

[0005] To achieve the above object, the present invention is implemented by the following technical scheme: A method for preparing a super-wetting nano coating comprises the following steps: S1. Substrate pretreatment: For different types of substrates such as metal, glass and polymer, ultrasonic cleaning is first performed, and the substrates are cleaned in acetone, ethanol and deionized water for 10-30 minutes respectively, with the ultrasonic frequency set to 40kHz, to remove oil stains and impurities on the surface of the substrate; for metal substrates, 1-3M NaOH solution is used for etching for 5-15 minutes; for glass substrates, plasma treatment is used for 2-5 minutes at a power of 5-100W; for polymer substrates, swelling treatment is performed in a specific organic solvent for 15-30 minutes; S2. Preparation of nanomaterial dispersion: SiO 2 Nanoparticles and TiO with a particle size of 20-100nm 2 The nanoparticles were mixed in a mass ratio of 1:1-3:1, with SiO 2 As the core, TiO 2 The core-shell structure of the shell is composited; then a bio-based dispersant is added, and the concentration of the composite structure in the dispersion is controlled at 0.5-2wt%; secondly, ultrasonic treatment is performed, and the ultrasonic treatment power is set to 200-500W, and the time is 30-60min; at the same time, a small amount of 0.1-0.3wt% sodium polyacrylate anti-settling agent can be added during the dispersion process; S3, coating: using dipping method, spraying method or spin coating method, the nano material dispersion prepared in step S2 is attached to the surface of the substrate pretreated in step S1; (1) Dipping method: The dipping speed is controlled at 1-5 mm / s, so that the substrate is slowly immersed in the dispersion and fully wetted. The pulling speed is set to 0.5-2 mm / s to ensure the uniformity of the coating thickness. During the dipping process, multiple dipping and pulling methods can be used. After each dipping, dry it at room temperature for 5-10 minutes before the next dipping. Generally, it is carried out 2-3 times to increase the thickness and density of the coating. (2) Spraying method: The spray gun pressure is set at 0.2-0.5MPa, and the spraying distance is maintained at 10-20cm. The thickness of the coating is controlled by adjusting the flow rate and spraying time of the spray gun. To obtain a more uniform coating, the substrate can be rotated during the spraying process at a speed of 510 rpm to make the coating evenly distributed on the surface of the substrate. At the same time, a temperature and humidity control system can be set in the spraying environment, with the temperature maintained at 20-25℃ and the humidity controlled at 40%-60% to reduce the impact of environmental factors on the coating quality; (3) Spin coating: The rotation speed is set at 1000-3000 rpm and the time is 30-60 seconds. The dispersion is evenly distributed on the surface of the substrate through high-speed rotation. Before spin coating, an appropriate amount of dispersion can be dripped on the surface of the substrate, and then the spin coating equipment is quickly started to ensure the initial uniformity of the coating. In order to prevent the dispersion from splashing during the spin coating process, a protective baffle can be set around the spin coating equipment, and an adsorption device can be set on the inside of the baffle to collect the splashed dispersion and reduce waste; S4, low temperature curing: the substrate coated with the nanomaterial dispersion in step S3 is cured in an inert gas environment at 50-80°C for 0.5-2 hours, the inert gas is nitrogen or argon, and the gas flow rate is controlled at 5-10L / min; during the curing process, a programmed temperature rise method can be adopted, firstly raising the temperature to 50°C at a rate of 5-10°C / min, maintaining for 15-30 minutes, and then raising the temperature to the final curing temperature at the same rate; S5, surface modification: the substrate that has been low-temperature cured in step S4 is subjected to hydrophobic modification or hydrophilic modification according to the type of the substrate; (1) Hydrophobic modification: 0.1-1wt% perfluorooctyltriethoxysilane ethanol solution is used for modification. During the modification process, the coating is immersed in the solution for 15-30 minutes, then taken out and dried at room temperature for 2-3 hours; (2) Hydrophilic modification: Use 0.5-2wt% aminosilane aqueous solution for modification, soak the coating in the solution for 20-40 minutes, then take it out and rinse it with deionized water, and dry it in an oven at 60-80℃ for 1-2 hours.

[0006] Furthermore, in the step S2, SiO 2 With TiO 2 The core-shell structure formation of the nanoparticles ensures the integrity and uniformity of the core-shell structure. At the same time, a dynamic light scattering instrument is used to detect the particle size distribution of the nanoparticles in the dispersion to ensure that the particle size of the nanoparticles is within the specified range and is evenly distributed.

[0007] Furthermore, in the S3 step, a non-contact thickness measuring instrument is used to monitor the thickness change of the coating in real time to ensure that the coating thickness is within the range of 100-500nm and the thickness uniformity deviation is ≤±10%; for the dipping method and the spraying method, the residual amount of organic solvent in the coating can be detected by thermogravimetric analysis after coating to ensure that the residual amount is less than 0.5wt% to ensure the quality and performance of the coating.

[0008] Furthermore, in the step S4, a scanning electron microscope is used to observe the porous nanostructure of the cured coating, and the porosity and pore size distribution are analyzed. The curing process parameters are adjusted to optimize the porosity and pore size distribution of the coating. At the same time, the porosity of the coating is accurately measured by mercury intrusion porosimetry to verify whether it is within the range of 40% to 60%.

[0009] Furthermore, in the S5 step, the water contact angle and rolling angle of the modified coating are accurately measured by a contact angle meter to ensure that the water contact angle of the hydrophobic modified coating is ≥150°, the rolling angle is ≤5°, and the water contact angle of the hydrophilic modified coating is ≤10°; for the hydrophilic modified coating with ultraviolet photocatalytic self-cleaning function, an ultraviolet light irradiation experiment is used to observe the decomposition and removal of pollutants on the coating surface under ultraviolet light irradiation, and evaluate its self-cleaning performance.

[0010] Furthermore, the nanoparticle dispersion is doped with 1-5wt% of Ag nanoparticles with a particle size of 5-20nm, and X-ray photoelectron spectroscopy (XPS) is used to analyze the existence form and chemical state of the Ag nanoparticles in the dispersion to ensure that they are evenly dispersed and have good antibacterial activity. The antibacterial rate of the coating against Escherichia coli is tested through an inhibition zone experiment to ensure that the antibacterial rate is ≥99%.

[0011] Furthermore, the surface roughness Ra of the porous nanostructured coating was measured using an atomic force microscope to ensure that it was in the range of 0.5-2μm. By establishing a mathematical model of surface roughness and contact angle, it was verified that the roughness and contact angle were positively correlated (R²>0.95).

[0012] Furthermore, after the nanomaterial dispersion is used, the bio-based dispersant is separated by ultrafiltration and centrifugation, and then after a simple purification treatment, it can be used again in the preparation of the nanomaterial dispersion. At the same time, the dispersion that does not adhere to the surface of the substrate during the spraying process can be collected and reused by setting up a recovery device to reduce the waste of raw materials.

[0013] Furthermore, functional additives are introduced during the coating preparation process, and 0.01-0.05wt% of organic fluorescent dye is added to the coating to make the coating emit fluorescence under the excitation of light of a specific wavelength; magnetic particles are added to the coating, and the particle size of Fe 3 O 4 Magnetic nanoparticles, doped in an amount of 2-5wt%, make the coating magnetic.

[0014] In summary, the present invention provides a method for preparing a super-wettable nano-coating, which has the following beneficial effects: 1. Through the pretreatment of the substrate, the adhesion between the substrate and the coating is enhanced. Through the nanomaterial dispersion and coating preparation, SiO2 With TiO 2 Nanoparticles are mixed in proportion to form a core-shell structure, bio-based dispersants are added and ultrasonically treated, and coated by appropriate methods such as dipping, spraying, and spin coating, and then cured at low temperature, thereby achieving the effect of constructing a stable and high-performance porous nanostructured coating. At the same time, a variety of coating methods are adapted to different needs, and low-temperature curing avoids high-temperature damage.

[0015] 2. Perfluorooctyl triethoxysilane ethanol solution is used for hydrophobic modification, aminosilane aqueous solution is used for hydrophilic modification, and photosensitizer can be added to enhance the self-cleaning effect, thereby achieving the effect of giving the coating diversified super-wetting properties. The hydrophobic modification greatly increases the water contact angle of the coating, making it easy for water droplets to roll off, and effectively preventing water and dirt; the hydrophilic modification reduces the water contact angle, and combined with the ultraviolet light catalytic self-cleaning function, keeps the surface clean.

[0016] 3. By using a transmission electron microscope and a dynamic light scattering instrument to monitor the core-shell structure and particle size distribution during the preparation of the nanomaterial dispersion, a laser thickness gauge to monitor the thickness in real time during coating, thermogravimetric analysis to detect organic solvent residues, scanning electron microscopy and mercury intrusion analysis to analyze the pore structure after low-temperature curing, and contact angle measurement and ultraviolet light irradiation experiments to evaluate performance after surface modification, a series of testing methods have been used to fully ensure the quality and performance stability of the coating. Accurate data feedback can timely adjust the preparation process to ensure that the performance indicators of each batch of coatings meet the standards and improve the product qualification rate.

[0017] 4. By doping Ag nanoparticles into the nanoparticle dispersion, and verifying its antibacterial activity using X-ray photoelectron spectroscopy and inhibition zone experiments, fluorescent agents and magnetic particle functional additives are introduced to expand the coating function; the bio-based dispersant is recycled and a device is set up to recycle the spray dispersion. This not only achieves the purpose of giving the coating antibacterial, fluorescent, magnetic and other functions, but also reduces the preparation cost, improves the utilization rate of raw materials, and reduces waste emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the process architecture of a method for preparing a super-wettable nano-coating according to the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example: See also Figure 1 As shown, the present invention provides a technical solution: a method for preparing a super-wetting nano coating, comprising the following steps: S1. Substrate pretreatment: For different types of metal, glass and polymer substrates, ultrasonic cleaning is first performed, and the cleaning is carried out in acetone, ethanol and deionized water for 10-30 minutes respectively, and the ultrasonic frequency is set to 40kHz to remove oil and impurities on the surface of the substrate; for metal substrates, 1-3M NaOH solution is used for etching for 5-15 minutes, and the surface is roughened by chemical etching to increase the surface active sites and promote the adhesion of subsequent coatings; for glass substrates, plasma treatment is used for 2-5 minutes at a power of 5-100W, and the interaction between plasma and glass surface is used to change the surface chemical properties and increase the surface energy; for polymer substrates, swelling treatment is carried out in a specific organic solvent for 15-30 minutes to change the microstructure of the substrate surface and enhance the bonding strength with the coating. Through substrate pretreatment, the surfaces of different substrates can be deeply cleaned, providing a good foundation for coating adhesion, greatly improving adhesion and extending service life; S2. Preparation of nanomaterial dispersion: SiO 2 Nanoparticles and TiO with a particle size of 20-100nm 2 The nanoparticles were mixed in a mass ratio of 1:1-3:1, with SiO 2 As the core, TiO 2 The core-shell structure of the shell is composited, which helps to synergistically exert the characteristics of the two materials; then a bio-based dispersant is added, and the bio-based dispersant can be chitosan or hydroxyethyl cellulose, and the concentration of the composite structure in the dispersion is controlled at 0.5-2wt%; secondly, ultrasonic treatment is performed, and the ultrasonic treatment power is set to 200-500W, and the time is 30-60min. Through high-intensity ultrasonic vibration, the agglomeration of nanoparticles is broken to form a uniform dispersion; at the same time, a small amount of 0.1-0.3wt% sodium polyacrylate anti-settling agent can be added during the dispersion process to prevent the nanoparticles from agglomerating again through electrostatic repulsion and steric hindrance. The unique core-shell structure makes SiO 2 The stability of TiO 2 The functional advantages of TiO 2 The shell absorbs light energy to decompose pollutants, SiO 2 The inner core maintains a stable structure and improves the durability of the coating. The use of anti-settling agents ensures that the nanoparticles are always evenly dispersed during the storage and transportation of the dispersion, and the product quality consistency between batches is high, which reduces the quality control cost in the production process, ensures the stability of the coating performance during large-scale production, and is conducive to product standardization; S3, coating: using dipping method, spraying method or spin coating method, the nano material dispersion prepared in step S2 is attached to the surface of the substrate pretreated in step S1; (1) Dipping method: The dipping speed is controlled at 1-5 mm / s, so that the substrate is slowly immersed in the dispersion and fully wetted. The pulling speed is set to 0.5-2 mm / s to ensure the uniformity of the coating thickness. During the dipping process, multiple dipping and pulling methods can be used. After each dipping, dry it at room temperature for 5-10 minutes before the next dipping. Generally, it is carried out 2-3 times to increase the thickness and density of the coating. The slow and controllable dipping and pulling speed ensures that the dispersion can fully fill the microscopic pores on the surface of the substrate to form a tightly fitting coating and reduce the internal defects of the coating. Multiple dipping and pulling increases the coating thickness and improves the coating's protective ability to the substrate. (2) Spraying method: The spray gun pressure is set at 0.2-0.5MPa, and the spraying distance is maintained at 10-20cm. The thickness of the coating is controlled by adjusting the flow rate and spraying time of the spray gun. In order to obtain a more uniform coating, the substrate can be rotated during the spraying process at a speed of 510 rpm to make the coating evenly distributed on the surface of the substrate. At the same time, a temperature and humidity control system can be set in the spraying environment. The temperature is maintained at 20-25℃ and the humidity is controlled at 40%-60% to reduce the impact of environmental factors on the coating quality. Accurate spray parameter control combined with substrate rotation can quickly form a uniform coating on a large area of ​​the substrate, improve production efficiency, and reduce coating defects caused by environmental changes. A stable production environment ensures stable coating quality, reduces scrap rate, and saves production costs. (3) Spin coating: The rotation speed is set at 1000-3000 rpm for 30-60 seconds. The dispersion is evenly distributed on the surface of the substrate through high-speed rotation. Before spin coating, an appropriate amount of dispersion can be dripped on the surface of the substrate, and then the spin coating equipment is quickly started to ensure the initial uniformity of the coating. In order to prevent the dispersion from splashing during the spin coating process, a protective baffle can be set around the spin coating equipment, and an adsorption device can be set on the inside of the baffle to collect the splashed dispersion to reduce waste. High-speed spin coating can evenly spread the dispersion on the surface of the substrate in a very short time, and prepare an ultra-thin coating with precise thickness and high uniformity. The setting of the protective baffle and the adsorption device not only reduces the loss of raw materials and saves costs, but also keeps the production environment clean, reduces the safety hazards that may be caused by the splash of the dispersion, and improves the safety and environmental protection of the production process; S4, low temperature curing: the substrate coated with the nanomaterial dispersion in step S3 is cured in an inert gas environment at 50-80°C for 0.5-2 hours, and the inert gas is nitrogen or argon, and the gas flow rate is controlled at 5-10L / min; during the curing process, a programmed temperature rise method can be adopted, firstly the temperature is raised to 50°C at a rate of 5-10°C / min, maintained for 15-30 minutes, and then the temperature is raised to the final curing temperature at the same rate, which helps to form a more stable porous nanostructured coating. By adjusting parameters such as curing temperature, time and gas flow rate, the porosity and pore size of the coating can be accurately controlled to meet different application requirements. Low temperature curing avoids high temperature damage to the performance of heat-sensitive substrates and coating materials, and broadens the application range of the coating. Inert gas protection prevents oxidation of the coating and ensures the chemical stability of the coating. Programmed temperature rise promotes the orderly arrangement of molecules to form a regular porous structure. The precisely controlled porosity and pore size give the coating special physical properties. S5, surface modification: the substrate that has been low-temperature cured in step S4 is subjected to hydrophobic modification or hydrophilic modification according to the type of the substrate; (1) Hydrophobic modification: 0.1-1wt% perfluorooctyl triethoxysilane ethanol solution is used for modification. During the modification process, the coating is immersed in the solution for 15-30 minutes, then taken out and dried at room temperature for 2-3 hours. After hydrophobic modification, the coating exhibits super-hydrophobic properties, and water droplets are difficult to adhere to, which can effectively prevent water from corroding the substrate and avoid safety accidents such as short circuits and leakage caused by water; (2) Hydrophilic modification: Use 0.5-2wt% aminosilane aqueous solution for modification, soak the coating in the solution for 20-40 minutes, then take it out and rinse it with deionized water, and dry it in an oven at 60-80℃ for 1-2 hours. The hydrophilic modification makes the coating surface easily wetted by water, thereby improving the self-cleaning function and service life of the coating.

[0021] In step S2, SiO 2 With TiO 2 The core-shell structure formation of nanoparticles ensures the integrity and uniformity of the core-shell structure. At the same time, the dynamic light scattering instrument is used to detect the particle size distribution of nanoparticles in the dispersion to ensure that the particle size of the nanoparticles is within the specified range and is evenly distributed. The use of TEM and DLS can achieve accurate monitoring of the microstructure and particle size distribution of the nanomaterial dispersion, and timely detect core-shell structure anomalies or particle size deviations. The preparation process can be quickly adjusted to ensure consistent coating performance for each batch, reduce product quality fluctuations, improve production efficiency, and reduce rework costs caused by quality problems.

[0022] In step S3, a non-contact thickness gauge is used to monitor the thickness change of the coating in real time to ensure that the coating thickness is within the range of 100-500nm and the thickness uniformity deviation is ≤±10%. For the dipping method and spraying method, thermogravimetric analysis can be used to detect the residual amount of organic solvent in the coating after coating to ensure that the residual amount is less than 0.5wt% to ensure the quality and performance of the coating. Real-time thickness monitoring ensures that the coating thickness is accurately controllable and meets the design requirements to avoid abnormal thickness affecting the coating function. TGA detects organic solvent residues to prevent residual solvents from affecting the curing effect and chemical stability of the coating and ensure that the coating is firmly bonded to the substrate.

[0023] In step S4, a scanning electron microscope is used to observe the porous nanostructure of the cured coating, and the porosity and pore size distribution are analyzed. The curing process parameters are adjusted to optimize the porosity and pore size distribution of the coating. The porosity of the coating is accurately measured by mercury intrusion porosimetry to verify whether it is within the range of 40% to 60%. SEM intuitively presents the microscopic porous structure of the coating, and the mercury intrusion porosimetry is used to accurately measure the porosity, providing reliable data for optimizing the curing process. According to the requirements of different applications for pore structure, the process parameters can be accurately adjusted to customize high-performance coatings.

[0024] In step S5, the water contact angle and rolling angle of the modified coating are accurately measured by a contact angle meter to ensure that the water contact angle of the hydrophobic modified coating is ≥150°, the rolling angle is ≤5°, and the water contact angle of the hydrophilic modified coating is ≤10°; for the hydrophilic modified coating with ultraviolet photocatalytic self-cleaning function, an ultraviolet light irradiation experiment is used to observe the decomposition and removal of pollutants on the surface of the coating under ultraviolet light, evaluate its self-cleaning performance, accurately measure the contact angle and rolling angle, accurately judge whether the coating wetting performance meets the standard, ensure that the hydrophobic or hydrophilic effect meets expectations, ensure that the product functions normally, and conduct ultraviolet light irradiation experiments on self-cleaning coatings to quantify the self-cleaning ability and screen out the best modification process.

[0025] 1-5wt% Ag nanoparticles with a particle size of 5-20nm are doped into the nanoparticle dispersion, and X-ray photoelectron spectroscopy (XPS) is used to analyze the existence form and chemical state of Ag nanoparticles in the dispersion to ensure that they are evenly dispersed and have good antibacterial activity. The antibacterial rate of the coating against Escherichia coli is tested through the inhibition zone experiment to ensure that the inhibition rate is ≥99%. Doped Ag nanoparticles give the coating strong antibacterial properties, effectively inhibit bacterial growth, reduce the risk of cross infection, and protect personnel health. XPS analysis and inhibition zone experiments verify the dispersion state and antibacterial effect of Ag nanoparticles from the microscopic and macroscopic levels, providing direction for optimizing the doping process and stabilizing and efficiently achieving antibacterial properties.

[0026] Atomic force microscopy was used to measure the surface roughness Ra of the porous nanostructured coating to ensure that it was within the range of 0.5-2μm. By establishing a mathematical model of surface roughness and contact angle, it was verified that the roughness was positively correlated with the contact angle (R²>0.95). AFM accurately measured the surface roughness and deeply explored its influence on the superwetting performance. The established mathematical model provided theoretical guidance for the optimization of coating design. In actual preparation, the surface roughness was precisely adjusted according to the required wetting performance to achieve precise control of the superwetting performance.

[0027] After the nanomaterial dispersion is used, the bio-based dispersant is separated by ultrafiltration and centrifugation, and then after simple purification, it can be used again for the preparation of nanomaterial dispersion. At the same time, the dispersion that is not attached to the surface of the substrate during the spraying process can be collected and reused by setting up a recovery device to reduce the waste of raw materials. The recycling of bio-based dispersants can greatly reduce the cost of raw material procurement, and the recycling of sprayed dispersions can further reduce waste and improve the utilization rate of raw materials. This not only reduces the production cost of enterprises, but also increases profit margins.

[0028] Functional additives are introduced during the coating preparation process. 0.01-0.05wt% of organic fluorescent dye is added to the coating to make the coating emit fluorescence under the excitation of light of a specific wavelength. Magnetic particles with a particle size of 10-50nm Fe 3 O 4 Magnetic nanoparticles, with a doping amount of 2-5wt%, make the coating magnetic. The introduction of functional additives greatly expands the application range of the coating. The fluorescent coating can achieve high-sensitivity detection of specific substances or environmental changes in optical sensing; the magnetic coating can efficiently separate mixed substances in magnetic control separation.

[0029] The above are only preferred embodiments of the present invention and are not intended to limit the present invention in other forms. Any technician familiar with the profession may use the technical contents disclosed above to change or modify them into equivalent embodiments with equivalent changes and apply them to other fields. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a super-wetting nano coating, characterized in that: The following steps are involved: S1. Substrate pretreatment: For different types of substrates such as metal, glass and polymer, ultrasonic cleaning is first performed, and the cleaning is carried out in acetone, ethanol and deionized water for 10-30 minutes respectively. The ultrasonic frequency is set to 40kHz to remove oil stains and impurities on the surface of the substrate; For metal substrates, 1-3M NaOH solution is used for etching for 5-15 minutes; for glass substrates, plasma treatment is used for 2-5 minutes at a power of 5-100W; for polymer substrates, swelling treatment is carried out in a specific organic solvent for 15-30 minutes; S2. Preparation of nanomaterial dispersion: SiO2 nanoparticles with a particle size of 10-50nm and TiO2 nanoparticles with a particle size of 20-100nm are mixed in a mass ratio of 1:1-3:1 to form a core-shell structure with SiO2 as the core and TiO2 as the shell; then a bio-based dispersant is added, and the concentration of the composite structure in the dispersion is controlled at 0.5-2wt%; secondly, ultrasonic treatment is performed, and the ultrasonic treatment power is set to 200-500W for 30-60min; at the same time, a small amount of 0.1-0.3wt% sodium polyacrylate anti-settling agent can be added during the dispersion process; S3, coating: using dipping method, spraying method or spin coating method, the nano material dispersion prepared in step S2 is attached to the surface of the substrate pretreated in step S1; (1) Dipping method: The dipping speed is controlled at 1-5 mm / s, so that the substrate is slowly immersed in the dispersion and fully wetted. The pulling speed is set to 0.5-2 mm / s to ensure the uniformity of the coating thickness. During the dipping process, multiple dipping and pulling methods can be used. After each dipping, dry it at room temperature for 5-10 minutes before the next dipping. Generally, it is carried out 2-3 times to increase the thickness and density of the coating. (2) Spraying method: The spray gun pressure is set at 0.2-0.5MPa, and the spraying distance is maintained at 10-20cm. The thickness of the coating is controlled by adjusting the flow rate and spraying time of the spray gun. To obtain a more uniform coating, the substrate can be rotated during the spraying process at a speed of 510 rpm to make the coating evenly distributed on the surface of the substrate. At the same time, a temperature and humidity control system can be set in the spraying environment, with the temperature maintained at 20-25℃ and the humidity controlled at 40%-60% to reduce the impact of environmental factors on the coating quality; (3) Spin coating: The rotation speed is set at 1000-3000 rpm and the time is 30-60 seconds. The dispersion is evenly distributed on the surface of the substrate through high-speed rotation. Before spin coating, an appropriate amount of dispersion can be dripped on the surface of the substrate, and then the spin coating equipment is quickly started to ensure the initial uniformity of the coating. In order to prevent the dispersion from splashing during the spin coating process, a protective baffle can be set around the spin coating equipment, and an adsorption device can be set on the inside of the baffle to collect the splashed dispersion and reduce waste; S4, low temperature curing: the substrate coated with the nanomaterial dispersion in step S3 is cured in an inert gas environment at 50-80°C for 0.5-2 hours, the inert gas is nitrogen or argon, and the gas flow rate is controlled at 5-10L / min; during the curing process, a programmed temperature rise method can be adopted, firstly raising the temperature to 50°C at a rate of 5-10°C / min, maintaining for 15-30 minutes, and then raising the temperature to the final curing temperature at the same rate; S5, surface modification: the substrate that has been low-temperature cured in step S4 is subjected to hydrophobic modification or hydrophilic modification according to the type of the substrate; (1) Hydrophobic modification: 0.1-1wt% perfluorooctyltriethoxysilane ethanol solution is used for modification. During the modification process, the coating is immersed in the solution for 15-30 minutes, then taken out and dried at room temperature for 2-3 hours; (2) Hydrophilic modification: Use 0.5-2wt% aminosilane aqueous solution for modification, soak the coating in the solution for 20-40 minutes, then take it out and rinse it with deionized water, and dry it in an oven at 60-80℃ for 1-2 hours.

2. The method for preparing a super-wetting nano coating according to claim 1, characterized in that: In the step S2, the core-shell structure formation of SiO2 and TiO2 nanoparticles is observed by transmission electron microscopy to ensure the integrity and uniformity of the core-shell structure. At the same time, a dynamic light scattering instrument is used to detect the particle size distribution of the nanoparticles in the dispersion to ensure that the particle size of the nanoparticles is within a specified range and is evenly distributed.

3. The method for preparing a super-wetting nano coating according to claim 1, characterized in that: In the S3 step, a non-contact thickness measuring instrument is used to monitor the thickness change of the coating in real time to ensure that the coating thickness is within the range of 100-500nm and the thickness uniformity deviation is ≤±10%; for the dipping method and the spraying method, the residual amount of organic solvent in the coating can be detected by thermogravimetric analysis after coating to ensure that the residual amount is less than 0.5wt% to ensure the quality and performance of the coating.

4. The method for preparing a super-wettable nano-coating according to claim 1, characterized in that: In the step S4, a scanning electron microscope is used to observe the porous nanostructure of the cured coating, and the porosity and pore size distribution are analyzed. The curing process parameters are adjusted to optimize the porosity and pore size distribution of the coating. At the same time, the porosity of the coating is accurately measured by mercury intrusion porosimetry to verify whether it is within the range of 40% to 60%.

5. The method for preparing a super-wetting nano coating according to claim 1, characterized in that: In the S5 step, the water contact angle and rolling angle of the modified coating are accurately measured by a contact angle meter to ensure that the water contact angle of the hydrophobic modified coating is ≥150°, the rolling angle is ≤5°, and the water contact angle of the hydrophilic modified coating is ≤10°; for the hydrophilic modified coating with ultraviolet photocatalytic self-cleaning function, an ultraviolet light irradiation experiment is used to observe the decomposition and removal of pollutants on the coating surface under ultraviolet light irradiation, and evaluate its self-cleaning performance.

6. The method for preparing a super-wettable nano-coating according to claim 1, characterized in that: The nanoparticle dispersion is doped with 1-5wt% of Ag nanoparticles with a particle size of 5-20nm, and X-ray photoelectron spectroscopy (XPS) is used to analyze the existence form and chemical state of the Ag nanoparticles in the dispersion to ensure that they are evenly dispersed and have good antibacterial activity. The antibacterial rate of the coating against Escherichia coli is tested through an inhibition zone experiment to ensure that the antibacterial rate is ≥99%.

7. The method for preparing a super-wettable nano-coating according to claim 1, characterized in that: The surface roughness Ra of the porous nanostructured coating was measured using an atomic force microscope to ensure that it was within the range of 0.5-2μm. By establishing a mathematical model of surface roughness and contact angle, it was verified that the roughness and contact angle were positively correlated (R²>0.95).

8. The method for preparing a super-wetting nano-coating according to claim 1, characterized in that: After the nanomaterial dispersion is used, the bio-based dispersant is separated by ultrafiltration and centrifugation, and then after a simple purification treatment, it can be used again in the preparation of nanomaterial dispersion. At the same time, the dispersion that does not adhere to the surface of the substrate during the spraying process can be collected and reused by setting up a recovery device to reduce the waste of raw materials.

9. The method for preparing a super-wetting nano-coating according to claim 1, characterized in that: Functional additives are introduced during the coating preparation process. 0.01-0.05wt% of organic fluorescent dyes are added to the coating to make the coating fluoresce when excited by light of a specific wavelength. Magnetic particles are added to the coating, Fe3O4 magnetic nanoparticles with a particle size of 10-50nm and a doping amount of 2-5wt%, so that the coating has magnetic properties.

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