Cement-based super-hydrophobic coating with multilevel structure and high mechanical durability and preparation method of cement-based super-hydrophobic coating

Abstract

The invention discloses a high-mechanical-durability cement-based super-hydrophobic coating with a multilevel structure and a preparation method of the high-mechanical-durability cement-based super-hydrophobic coating, and belongs to the technical field of coatings and coating. The cement-based coating comprises a first coating, a second coating and a third coating, wherein the first coating comprises hydroxyl-terminated polydimethylsiloxane and a curing agent; a second coating comprising candle soot; and the third coating comprises low surface energy nano particles, and the raw materials of the low surface energy nano particles comprise ethanol, ammonia water, tetraethoxysilane and hexadecyl trimethoxy silane. Therefore, the cement-based coating disclosed by the invention has good super-hydrophobicity and mechanical durability, and can keep good working performance in a long-term wear environment. In addition, the cement-based coating is non-toxic and harmless on the whole, has the ice dredging characteristic, and can improve the resistance of the cement-based material to ice pulling damage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint and painting technology, and particularly relates to a cement-based super-hydrophobic coating with a multi-level structure and a preparation method thereof. BACKGROUND

[0002] Cement-based materials are widely used in civil buildings, bridges, and water conservancy and hydropower engineering fields due to their advantages of abundant raw materials, low cost, and high compressive strength. However, the porous and hydrophilic nature of cement-based materials allows water and harmful ions (such as Cl - , SO4 2- ) to easily penetrate into the interior, causing freeze-thaw damage and chemical corrosion, which seriously threatens the service life of the structure.

[0003] Currently, organic polymer coatings such as polyurethane, polyurea, epoxy resin, and acrylic resin are commonly used to protect cement-based materials from damage. However, when used in long-term wet environments, these coatings may develop bulging and cracking after a period of application on the surface of cement-based materials, losing their protective effect. At the same time, the mechanical durability of these coatings is generally poor, and their surfaces may develop cracks and even peel off under dynamic actions such as mechanical wear, impact load, and freeze-thaw cycles, no longer playing a protective role. These factors will limit the service life of cement-based protective materials. To address these issues, some methods use single nanoparticles (such as SiO2 and TiO2) to enhance their performance, but due to uneven particle dispersion or weak interfacial bonding, the desired effect cannot be achieved. It is very meaningful to find new methods to simultaneously improve the water resistance and mechanical durability of cement-based protective materials. SUMMARY

[0004] The present application aims to at least partially address at least one of the technical problems existing in the prior art. Therefore, the present application proposes a cement-based coating and its preparation method and application, which has good super-hydrophobicity and mechanical durability, and can maintain good working performance in long-term wear environments. By layer-by-layer brushing, a super-hydrophobic coating with a protective structure can be formed on the surface of the cement-based material, which can reduce the water absorption of the cement-based material and improve the durability of the substrate in long-term wet environments. In addition, the cement-based coating is non-toxic and harmless as a whole, has ice-phobic properties, and can improve the resistance of cement-based materials to ice pull damage.

[0005] Therefore, in a first aspect, the present application provides a cement-based coating. According to an embodiment of the present application, the cement-based coating comprises: a first coating comprising a hydroxyl-terminated polydimethylsiloxane and a curing agent; a second coating comprising candle soot; and a third coating comprising low-surface-energy nanoparticles, raw materials of the low-surface-energy nanoparticles comprising ethanol, ammonia, tetraethyl orthosilicate, and hexadecyltrimethoxysilane.

[0006] The first coating can be used to construct a protective structure of the overall coating, preventing the rough structure formed subsequently from being damaged first in the case of mechanical wear. The rough structure is damaged only after the protective layer structure is worn, and the protective structure effectively improves the service life of the overall coating. In addition, the first coating also plays a role in fixing the second layer of candle soot particles. The candle soot in the second coating forms a micrometer-level rough structure, and this rough structure is relatively dense, which preliminarily effectively reduces the water absorption of the substrate. The nanometer-level low-surface-energy particles in the third coating can play a filling role on the candle soot layer formed by the second coating, further improve the roughness of the coating surface, and introduce low-surface-energy groups, thereby improving the super-hydrophobicity of the coating surface under the dual effects. Thus, the cement-based coating of the present application has good super-hydrophobicity and mechanical durability, and can maintain good working performance in a long-term wear environment. In addition, the overall cement-based coating is non-toxic and harmless, has ice-repellent properties, and can improve the resistance of the cement-based material to ice-pull damage.

[0007] In a second aspect of the present application, a method for preparing the cement-based coating of the first aspect is provided. According to an embodiment of the present application, the method comprises: performing a first mixing treatment on a hydroxyl-terminated polydimethylsiloxane and a curing agent to obtain a first coating; performing an incomplete combustion treatment on a candle to collect candle soot and obtain a second coating; and performing a second mixing treatment on ethanol, ammonia, tetraethyl orthosilicate, and hexadecyltrimethoxysilane to obtain a third coating. Thus, the preparation process of the present application is simple and does not require complex equipment and operations. The cement-based coating prepared by the method of the present application has significant performance advantages: on the one hand, it has excellent super-hydrophobic properties and mechanical durability, and can still maintain stable performance even in a long-term wear environment; on the other hand, the overall coating is non-toxic and harmless, green and environmentally friendly, and has unique ice-repellent properties, which can effectively enhance the resistance of the cement-based material to ice-pull damage, thereby significantly improving the service life and application reliability of the material.

[0008] In a third aspect of the present application, the cement-based coating of the first aspect or the cement-based coating prepared by the method of the second aspect is applied to at least one of improving the hydrophobic properties and the durability of the cement-based material.

[0009] In a fourth aspect, the present application provides a multi-level structure cement-based material. According to an embodiment of the present application, the multi-level structure cement-based material comprises: a cement-based material and a cement-based coating applied on the surface of the cement-based material; the cement-based coating is the cement-based coating of the first aspect or the cement-based coating prepared by the method of the second aspect. As described above, the cement-based coating of the present application has good super-hydrophobicity and mechanical durability, thus, the multi-level structure cement-based material coated with the cement-based coating not only has good water-proofing performance by effectively repelling water and preventing water penetration, but also has excellent durability to resist external physical abrasion and prolong the service life.

[0010] In a fifth aspect, the present application provides a method for preparing the multi-level structure cement-based material of the fourth aspect. According to an embodiment of the present application, the method comprises: applying the cement-based coating of the first aspect or the cement-based coating prepared by the method of the second aspect on the surface of the cement-based material. Thus, the multi-level structure cement-based material obtained by the method of the present application has excellent water-proofing performance and durability, can maintain stable performance in harsh environments with long-term abrasion, and has ice-phobicity to effectively enhance the resistance of the cement-based material to ice pull damage.

[0011] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0012] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0013] Figure 1 is a distribution diagram of the cement-based coating on the surface of the cement-based material according to an embodiment of the present application;

[0014] Figure 2 is a photograph of the surface wettability of the cement-based super-hydrophobic coating according to Example 3 of the present application; wherein,

[0015] (a) is the contact angle of a liquid droplet on the surface of the coating; (b) is the rolling angle of the liquid droplet on the surface of the coating;

[0016] Figure 3 is a micro-morphology diagram of the surface of the super-hydrophobic coating according to Example 3 of the present application, with a magnification of 5000 times;

[0017] Figure 4 is a comparison diagram of water absorption rates of Example 3 and Comparative Example 1 according to the present application;

[0018] Figure 5is a plot of surface wettability change after 50 tape peel cycles according to Example 3 of the present application;

[0019] Figure 6 is a plot of surface wettability change after 1000 kg sand impact according to Example 3 of the present application. DETAILED DESCRIPTION

[0020] The embodiments of the present application will be described in detail below. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot be used to limit the protection scope of the present application.

[0021] In this document, reference to“an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment. It is explicitly contemplated that one or more features, structures, or characteristics described in connection with an embodiment can be combined with features, structures, or characteristics of another embodiment.

[0022] For the sake of brevity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not expressly recited; and any lower limit can be combined with any other lower limit to form a range not expressly recited, and likewise any upper limit can be combined with any other upper limit to form a range not expressly recited. Further, each individual disclosed point or single numerical value can be combined with any other point or single numerical value to form a range not expressly recited, either as a lower or upper limit, or in combination with other lower or upper limits.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the use of the terms“including,”“comprising,”“having” and the like are meant to be inclusive and are to be construed as specifying the presence of stated features, regions, integers, steps or components as well as their equivalents thereof.

[0024] In this document, it is to be understood that the terms“center,”“longitudinal,”“lateral,”“length,”“width,”“thickness,”“upper,”“lower,”“front,”“back,”“left,”“right,”“vertical,”“horizontal,”“top,”“bottom,”“inner,”“outer,”“clockwise,”“counterclockwise,”“axial,”“radial,”“circumferential,” and similar terms are used to indicate orientation or positional relationships based on the orientation or positional relationships shown in the drawings, and are not intended to require that the device or element be constructed and operated in a particular orientation or manner, and are thus not to be construed as limiting the application.

[0025] It should be noted that the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0026] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0027] At present, the method for modifying the hydrophobicity of cement-based materials is divided into overall super-hydrophobic modification method and surface super-hydrophobic modification method. Among them, the surface super-hydrophobic modification method is widely used because of its simple operation and remarkable effect. However, the cement-based material modified by the traditional surface super-hydrophobic modification method has obvious deficiency in wear resistance. In the long-term use process, affected by environmental factors, the paint is easy to fall off in large quantities, resulting in that the cement-based material loses the hydrophobic property, and further affecting the service life and protection effect thereof. In addition, in the existing related research, the method for preparing the super-hydrophobic coating with high durability is often relatively complex, and has the problem of environmental pollution, which limits its large-scale application.

[0028] Therefore, aiming at the protection demand of the cement-based material in the long-term humid and wear environment, it is of great significance to develop a cement-based paint with high mechanical durability and super-hydrophobic property. By improving the mechanical durability of the paint itself, not only the water erosion can be effectively resisted, the service life of the paint is prolonged, but also the overall durability of the cement-based material is significantly improved, so as to reduce the maintenance cost and realize the long-term and efficient protection of the cement-based material in the complex environment.

[0029] Therefore, the present application provides a cement-based paint, which has good super-hydrophobicity and mechanical durability, and can maintain good working performance in a long-term wear environment. By layer-by-layer brushing, a super-hydrophobic coating with a protective structure can be formed on the surface of the cement-based material, and after brushing, the water absorption rate of the cement-based material can be reduced, and the durability of the base body in a long-term humid environment can be improved. In addition, the cement-based paint as a whole is non-toxic and harmless, has ice-repellent property, and can improve the resistance of the cement-based material to ice pull damage. The cement-based paint, the preparation method thereof, the application thereof, the multi-level structure cement-based material and the preparation method thereof will be described in detail below.

[0030] Cement-based paint and preparation method thereof

[0031] In a first aspect, the present application provides a cement-based coating. According to an embodiment of the present application, the cement-based coating comprises: a first coating comprising a hydroxyl-terminated polydimethylsiloxane and a curing agent; a second coating comprising candle soot; and a third coating comprising low surface energy nanoparticles, raw materials of the low surface energy nanoparticles comprising ethanol, ammonia, tetraethyl orthosilicate and hexadecyltrimethoxysilane.

[0032] The first coating can be used to construct a protective structure of the overall coating, preventing the rough structure formed subsequently from being damaged first in the case of mechanical wear. The rough structure is damaged only after the protective layer structure is worn, and the protective structure effectively improves the service life of the overall coating. In addition, the first coating also plays a role in fixing the second layer of candle soot particles. The candle soot in the second coating forms a micron-level rough structure, and this rough structure is relatively dense, which preliminarily effectively reduces the water absorption of the substrate. The nanometer-level low surface energy particles in the third coating can play a filling role on the candle soot layer formed by the second coating, further improve the roughness of the coating surface, and introduce low surface energy groups, thereby improving the super-hydrophobicity of the coating surface under the dual effects. Thus, the cement-based coating of the present application has good super-hydrophobicity and mechanical durability, and can maintain good working performance in a long-term wear environment. In addition, the overall cement-based coating is non-toxic and harmless, has ice-repellent properties, and can improve the resistance of cement-based materials to ice damage.

[0033] In some embodiments of the present application, the mass ratio of the hydroxyl-terminated polydimethylsiloxane (PDMS-OH) and the curing agent is (8-12):1. For example, it can be 8:1, 9:1, 10:1, 11:1, 12:1, etc., or it can be a range composed of any of the above values. Thus, by making the mass ratio of the hydroxyl-terminated polydimethylsiloxane and the curing agent in the above range, it can be ensured that the cross-linking reaction between the hydroxyl-terminated polydimethylsiloxane and the curing agent proceeds sufficiently, so that the coating has good mechanical properties, flexibility, hydrophobicity and adhesion to the substrate.

[0034] In some embodiments of the present application, the curing agent comprises at least one of tetraethyl orthosilicate and dibutyltin dilaurate. Thus, the above-mentioned types of curing agents can undergo cross-linking reactions with the hydroxyl-terminated polydimethylsiloxane to form a stable three-dimensional network structure, thereby imparting mechanical strength and durability to the protective structure of the coating as a whole.

[0035] In some embodiments of the present application, the curing agent comprises tetraethyl orthosilicate and dibutyltin dilaurate, and the mass ratio of the tetraethyl orthosilicate and the dibutyltin dilaurate is 10:1. In this way, the cross-linking reaction with the hydroxyl-terminated polydimethylsiloxane can be sufficiently carried out to form a stable three-dimensional network structure, thereby forming a protective structure to impart the coating as a whole with mechanical strength and durability and to fix the subsequent coating structure.

[0036] In some embodiments of the present application, the volume ratio of the ethanol, the ammonia water, the tetraethyl orthosilicate and the hexadecyltrimethoxysilane is (45-55):(2-5):(2-5):(2.5-3.5). For example, it can be 48:2.5:2.5:2.5, 50:4:4:2.5, 50:3:3:3.2, 55:5:5:3.5, 52:4:4:3, etc., or can be a range composed of any of the above values. In this way, by controlling the volume ratio of the four substances within the above range, the size, uniformity, surface hydrophobicity and reaction rate of the nanoparticles can be effectively controlled. Specifically, the ethanol as a solvent affects the uniformity of the reaction system and the reaction rate; the ammonia water as a catalyst adjusts the size and generation rate of the nanoparticles; the tetraethyl orthosilicate as a precursor provides a basis for subsequent roughness construction after hydrolysis to generate silica particles at the nanoscale; and the hexadecyltrimethoxysilane as a low surface energy agent imparts the nanoparticles with low surface energy and good hydrophobicity. Optimizing the volume ratio can ensure that the nanoparticles have an ideal size distribution, excellent hydrophobic properties and good dispersion stability, thereby meeting the needs of different application scenarios.

[0037] It should be noted that the ammonia water used in the present application is obtained by commercial purchase, and its mass fraction is 25%-28%. In the process of preparing the third coating, the purchased ammonia water is directly used without any additional treatment or adjustment.

[0038] In some embodiments of the present application, the particle size of the candle soot is 1.5-3.5 μm. For example, it can be 1.5 μm, 1.7 μm, 2 μm, 2.2 μm, 2.5 μm, etc., or a range formed by any of the above values. In some embodiments of the present application, the particle size of the low-surface-energy nanoparticles is 50-100 nm. For example, it can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc., or a range formed by any of the above values. In this way, the candle soot and the low-surface-energy nanoparticles can form a micro-nano multi-level rough structure inside the coating, thereby greatly improving the waterproof performance of the cement-based material. When water acts on the surface of the coating, the water gradually penetrates into the super-hydrophobic structure by capillary force. At this time, the micro-nano multi-level rough structure can effectively delay the escape of air in the super-hydrophobic structure, and inhibit the irreversible conversion process of the super-hydrophobic surface from the Cassie-Baxter state to the Wenzel state. At the same time, the low-surface-energy group carried by the low-surface-energy nanoparticle structure layer can form a synergistic effect with the multi-scale rough morphology, thereby reducing the water absorption of the cement-based material after brushing and improving the durability of the substrate in a long-term humid environment.

[0039] By layer-by-layer coating of the first coating, the second coating and the third coating, as shown in Figure 1 The candle soot in the second coating and the low-surface-energy nanoparticles (hydrophobically modified SiO2) in the third coating will be embedded in the hydroxyl-terminated polydimethylsiloxane layer (PDMS-OH) formed by the first coating, thereby forming a super-hydrophobic coating with a protective structure on the surface of the cement-based material. When encountering external wear and tear, the hydroxyl-terminated polydimethylsiloxane layer formed by the first coating can protect the internal rough structure, and the rough structure can still ensure its integrity in the early stage of damage, thereby long-term super-hydrophobic effect. In the middle and late stages of damage, the low-surface-energy nanoparticle structure layer formed by the third coating on the top may be damaged, thereby exposing the candle soot layer formed by the second coating, which has excellent adhesion to the substrate and can continue to resist external damage, thereby embodying the high mechanical durability of this composite coating and improving the water resistance of the cement-based material. At the same time, the nanoparticle structure layer has low surface energy, which further reduces the water absorption of the cement-based material after brushing and improves the durability of the substrate in a long-term humid environment.

[0040] In a second aspect, the present application provides a method for preparing the cement-based coating of the first aspect. According to an embodiment of the present application, the method comprises: performing a first mixing process on hydroxyl-terminated polydimethylsiloxane and a curing agent to obtain a first coating; performing an incomplete combustion process on a candle to collect candle soot to obtain a second coating; performing a second mixing process on ethanol, ammonia, tetraethyl orthosilicate and hexadecyl trimethoxysilane to obtain a third coating. Thus, the cement-based coating prepared by the method of the present application has significant performance advantages: on the one hand, it has excellent super-hydrophobic properties and mechanical durability, and can maintain stable performance even in harsh environments with long-term wear and tear; on the other hand, the coating is non-toxic and harmless, green and environmentally friendly, and has unique ice-repellent properties, which can effectively enhance the resistance of cement-based materials to ice damage and significantly improve the service life and application reliability of the materials.

[0041] In some embodiments of the present application, the first mixing process is performed using a first stirring method, and the first stirring speed is 300 rpm-450 rpm. For example, it can be 300 rpm, 350 rpm, 400 rpm, 450 rpm, etc., or a range composed of any of the above values. In some embodiments of the present application, the first stirring time is 25 min-35 min. For example, it can be 25 min, 27 min, 30 min, 32 min, 35 min, etc., or a range composed of any of the above values. In some embodiments of the present application, the first stirring temperature is 25℃-35℃. For example, it can be 25℃, 27℃, 30℃, 32℃, 35℃, etc., or a range composed of any of the above values.

[0042] In some embodiments of the present application, the second mixing process further comprises: performing a third mixing process on the ammonia and the ethanol to obtain a third mixing process product; performing a fourth mixing process on the third mixing process product and the tetraethyl orthosilicate to obtain a fourth mixing process product; and performing a fifth mixing process on the fourth mixing process product and the hexadecyl trimethoxysilane to obtain the third coating.

[0043] In some embodiments of the present application, the third mixing process is performed by using a second stirring mode, and the rotation speed of the second stirring is 400 rpm-550 rpm. For example, it can be 400 rpm, 450 rpm, 500 rpm, 550 rpm, etc., or a range consisting of any of the above values. In some embodiments of the present application, the time of the second stirring is 25 min-35 min. For example, it can be 25 min, 27 min, 30 min, 32 min, 35 min, etc., or a range consisting of any of the above values. In some embodiments of the present application, the temperature of the second stirring is 40℃-60℃. For example, it can be 40℃, 45℃, 50℃, 55℃, 60℃, etc., or a range consisting of any of the above values.

[0044] In some embodiments of the present application, the fourth mixing process is performed by using a third stirring mode, and the rotation speed of the third stirring is 400 rpm-550 rpm. For example, it can be 400 rpm, 450 rpm, 500 rpm, 550 rpm, etc., or a range consisting of any of the above values. In some embodiments of the present application, the time of the third stirring is 2 h-3 h. For example, it can be 2 h, 2.2 h, 2.5 h, 2.7 h, 3 h, etc., or a range consisting of any of the above values. In some embodiments of the present application, the temperature of the third stirring is 40℃-60℃. For example, it can be 40℃, 45℃, 50℃, 55℃, 60℃, etc., or a range consisting of any of the above values.

[0045] In some embodiments of the present application, the fifth mixing process is performed by using a fourth stirring mode, and the rotation speed of the fourth stirring is 650 rpm-800 rpm. For example, it can be 650 rpm, 700 rpm, 750 rpm, 800 rpm, etc., or a range consisting of any of the above values. In some embodiments of the present application, the time of the fourth stirring is 2.5 h-4 h. For example, it can be 2.5 h, 3 h, 3.5 h, 4 h, etc., or a range consisting of any of the above values. In some embodiments of the present application, the temperature of the fourth stirring is 40℃-60℃. For example, it can be 40℃, 45℃, 50℃, 55℃, 60℃, etc., or a range consisting of any of the above values.

[0046] Applications

[0047] In a third aspect, the present application provides use of the cement-based coating of the first aspect or the cement-based coating prepared by the method of the second aspect in improving at least one of the hydrophobic property and the durability of the cement-based material. As described above, the cement-based coating of the present application has good super-hydrophobic property and mechanical durability, and can maintain good working performance in long-term wear environment, and has ice-phobic effect. Thus, the cement-based coating of the present application can improve the hydrophobic property and the durability of the cement-based material.

[0048] Multilevel structure cement-based material and preparation method thereof

[0049] In a fourth aspect, the present application provides a multilevel structure cement-based material. According to an embodiment of the present application, the multilevel structure cement-based material comprises: a cement-based material and a cement-based coating coated on the surface of the cement-based material; the cement-based coating is the cement-based coating of the first aspect or the cement-based coating prepared by the method of the second aspect. As described above, the cement-based coating of the present application has good super-hydrophobic property and mechanical durability, and thus the multilevel structure cement-based material coated with the cement-based coating not only has good water-proof property by effectively repelling water and preventing water penetration, but also has excellent durability to resist external physical wear and prolong service life.

[0050] In a fifth aspect, the present application provides a method for preparing the multilevel structure cement-based material of the fourth aspect. According to an embodiment of the present application, the method comprises: coating the cement-based coating of the first aspect or the cement-based coating prepared by the method of the second aspect on the surface of the cement-based material. Thus, the multilevel structure cement-based material obtained by the method of the present application has excellent water-proof property and durability, can maintain stable performance in long-term wear harsh environment, and has ice-phobic effect to effectively enhance the resistance of the cement-based material to ice pull damage.

[0051] In some embodiments of the present application, the coating comprises: coating a first coating of the cement-based coating on the surface of the cement-based material; coating a second coating of the cement-based coating on the surface of the first coating before the first coating is cured; coating a third coating of the cement-based coating on the surface of the second coating; and curing the coatings to obtain the multilevel structure cement-based material.

[0052] In some embodiments of the present application, the second coating is applied before the first coating is cured, which enables the candle soot particles in the second coating to fully contact the liquid end-hydroxyl polydimethylsiloxane film of the first coating, thereby improving the adhesion between the two coatings. The subsequent candle soot deposition operation can cause the end-hydroxyl polydimethylsiloxane layer to rapidly solidify and form a more compact packing of the existing candle soot layer, thereby ensuring that the coating surface has good roughness. Then, the third coating is applied to fill the candle soot layer embedded in the end-hydroxyl polydimethylsiloxane film, which can further improve the roughness of the coating surface and introduce low-surface-energy groups, thereby improving the super-hydrophobic properties of the coating surface under the dual effects.

[0053] Embodiments of the present application will be described in detail below. The embodiments described below are exemplary and are intended only to explain the present application, and should not be construed as limiting the present application. If a specific technique or condition is not specified in the embodiments, it is performed according to the technique or condition described in the literature in the art or according to the product manual. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be obtained from the market.

[0054] The candle soot in the embodiments is obtained by incomplete combustion of a candle, and its specific preparation method can refer to Zimmerle, B., Wu, M., Liu, J., & Chen, X. (2023). The microwave absorption performance of candle soots. Carbon, 212, 118124.

[0055] Example 1

[0056] The cement-based super-hydrophobic coating with a multi-level structure is made by the following method:

[0057] (1) Mix tetraethyl orthosilicate and dibutyltin dilaurate in a mass ratio of 10:1 as a curing agent. Then mix the end-hydroxyl polydimethylsiloxane with the curing agent in a mass ratio of 8:1, stir at 300 rpm in a constant temperature water bath at 30°C for 30 min, and brush the obtained product on the surface of the cement-based material to form a bottom protective structure layer;

[0058] (2) uniformly coat the candle soot on the bottom protective structure layer of the cement-based material at a dosage of 5 g / m 2 After the candle soot layer is completely covered, use a burning candle to perform a 15-second soot deposition treatment on the surface. Due to the incomplete combustion of the candle, soot particles will be deposited to further densify the roughness of the candle soot layer, thereby forming an intermediate candle soot structure layer;

[0059] (3) Under the constant temperature condition of 40°C, mix anhydrous ethanol, 25-28% ammonia water, tetraethyl orthosilicate, and hexadecyl trimethoxysilane in a volume ratio of 48:2.5:2.5:2.5. First, slowly drop a certain amount of ammonia water into anhydrous ethanol, and stir at a speed of 400 rpm for 30 min; then add tetraethyl orthosilicate, and continue to maintain the stirring condition of 40°C and 400 rpm for 3 h; finally, add hexadecyl trimethoxysilane, and adjust the stirring speed to 650 rpm, and maintain the stirring condition of 40°C for 2.5 h to obtain low-surface-energy nanoparticles. Brush the low-surface-energy nanoparticles on the cement-based material with the bottom protective structure layer and the intermediate candle soot structure layer to form a top low-surface-energy nanoparticle structure layer.

[0060] After the brushed cement-based material is placed in a normal temperature environment for drying for 24 h, a cement-based super-hydrophobic material with a multi-level structure is formed.

[0061] Example 2

[0062] The cement-based super-hydrophobic coating with a multi-level structure is made by the following method:

[0063] (1) Mix tetraethyl orthosilicate and dibutyltin dilaurate in a mass ratio of 10:1 as a curing agent. Then mix hydroxyl-terminated polydimethylsiloxane with the curing agent in a mass ratio of 9:1, stir at a speed of 320 rpm for 30 min under the condition of a constant temperature water bath of 30°C, and brush the obtained product on the surface of the cement-based material to form a bottom protective structure layer;

[0064] (2) Uniformly coat candle soot on the bottom protective structure layer of the cement-based material at a dosage of 5.5 g / m 2 After the candle soot layer is completely covered, use a burning candle to perform soot deposition processing on the surface for 20 s. Due to the incomplete combustion of the candle, soot particles will be deposited to further densify the roughness of the candle soot layer, thereby forming an intermediate candle soot structure layer;

[0065] (3) Under the constant temperature condition of 55°C, mix anhydrous ethanol, 25-28% ammonia water, tetraethyl orthosilicate, and hexadecyl trimethoxysilane in the volume ratio of 50:4:4:2.5. First, slowly drop a certain amount of ammonia water into anhydrous ethanol, and stir at the speed of 450 rpm for 30 min; then add tetraethyl orthosilicate, and continue to maintain the stirring condition of 55°C and 700 rpm for 2 h; finally, add hexadecyl trimethoxysilane, and adjust the stirring speed to 750 rpm, maintain the stirring condition of 55°C for 3.5 h, to obtain low-surface-energy nanoparticles. Brush the low-surface-energy nanoparticles on the cement-based material with the bottom protective structure layer and the intermediate candle soot structure layer, to form a top low-surface-energy nanoparticle structure layer.

[0066] After the brushed cement-based material is placed in a normal temperature environment for drying for 24 h, a cement-based super-hydrophobic material with a multi-level structure is formed.

[0067] Example 3

[0068] The cement-based super-hydrophobic coating with a multi-level structure is made by the following method:

[0069] (1) Mix tetraethyl orthosilicate and dibutyltin dilaurate in the mass ratio of 10:1 as a curing agent. Then mix hydroxyl-terminated polydimethylsiloxane with the curing agent in the mass ratio of 10:1, stir at the speed of 350 rpm for 30 min under the constant temperature water bath condition of 30°C, and brush the obtained product on the surface of the cement-based material to form a bottom protective structure layer;

[0070] (2) Uniformly coat candle soot on the bottom protective structure layer of the cement-based material in the amount of 6.25 g / m 2 After the candle soot layer is completely covered, use a burning candle to perform soot deposition treatment on the surface for 20 s. Due to the incomplete combustion of the candle, soot particles will be deposited to further densify the roughness of the candle soot layer, thereby forming an intermediate candle soot structure layer;

[0071] (3) Under the constant temperature condition of 50°C, mix anhydrous ethanol, 25-28% ammonia water, tetraethyl orthosilicate, and hexadecyl trimethoxysilane in a volume ratio of 50:3:3:3.2. First, slowly drop a certain amount of ammonia water into anhydrous ethanol, and stir at a speed of 500 rpm for 30 min; then add tetraethyl orthosilicate, and continue to maintain the stirring condition of 50°C and 500 rpm for 2.5 h; finally, add hexadecyl trimethoxysilane, and adjust the stirring speed to 750 rpm, maintain 50°C stirring for 3 h, to obtain low-surface-energy nanoparticles. Brush the low-surface-energy nanoparticles on the cement-based material with the bottom protective structure layer and the intermediate candle soot structure layer to form a top low-surface-energy nanoparticle structure layer.

[0072] After the brushed cement-based material is placed in a normal temperature environment for drying for 24 h, a cement-based super-hydrophobic material with a multi-level structure is formed.

[0073] Example 4

[0074] The cement-based super-hydrophobic coating with a multi-level structure is made by the following method:

[0075] (1) Mix tetraethyl orthosilicate and dibutyltin dilaurate in a mass ratio of 10:1 as a curing agent. Then mix hydroxyl-terminated polydimethylsiloxane with the curing agent in a mass ratio of 11:1, stir at a speed of 450 rpm for 30 min under the condition of a constant temperature water bath of 30°C, and brush the obtained product on the surface of the cement-based material to form a bottom protective structure layer;

[0076] (2) Uniformly coat candle soot on the bottom protective structure layer of the cement-based material at a dosage of 6.5 g / m 2 After the candle soot layer is completely covered, use a burning candle to perform soot deposition processing on the surface for 30 seconds. Due to the incomplete combustion of the candle, soot particles will be deposited to further densify the roughness of the candle soot layer, thereby forming an intermediate candle soot structure layer;

[0077] (3) Under the constant temperature condition of 60°C, mix anhydrous ethanol, 25-28% ammonia water, tetraethyl orthosilicate, and hexadecyl trimethoxysilane in the volume ratio of 55:5:5:3.5. First, slowly drop a certain amount of ammonia water into anhydrous ethanol, and stir at the speed of 550 rpm for 30 min; then add tetraethyl orthosilicate, and continue to maintain the stirring condition of 60°C and 550 rpm for 3 h; finally, add hexadecyl trimethoxysilane, and adjust the stirring speed to 800 rpm, maintain the stirring condition of 60°C for 4 h, to obtain low-surface-energy nanoparticles. Brush the low-surface-energy nanoparticles on the cement-based material with the bottom protective structure layer and the intermediate candle soot structure layer, to form a top low-surface-energy nanoparticle structure layer.

[0078] After the brushed cement-based material is placed in a normal temperature environment for drying for 24 h, a cement-based super-hydrophobic material with a multi-level structure is formed.

[0079] Example 5

[0080] A cement-based super-hydrophobic coating with a multi-level structure is made by the following method:

[0081] (1) Mix tetraethyl orthosilicate and dibutyltin dilaurate in the mass ratio of 10:1 as a curing agent. Then mix hydroxyl-terminated polydimethylsiloxane with the curing agent in the mass ratio of 12:1, stir at the speed of 450 rpm for 30 min under the constant temperature water bath condition of 30°C, and brush the obtained product on the surface of the cement-based material to form a bottom protective structure layer;

[0082] (2) Uniformly coat candle soot on the bottom protective structure layer of the cement-based material in the amount of 6 g / m 2 After the candle soot layer is completely covered, use a burning candle to perform soot deposition processing on the surface for 25 s. Due to the incomplete combustion of the candle, soot particles will be deposited to further densify the roughness of the candle soot layer, thereby forming an intermediate candle soot structure layer;

[0083] (3) Under constant temperature condition at 55°C, mix anhydrous ethanol, 25-28% ammonia water, tetraethyl orthosilicate, and hexadecyltrimethoxysilane in a volume ratio of 52:4:4:3. First, slowly drop a certain amount of ammonia water into anhydrous ethanol, and stir at a speed of 500 rpm for 30 min; then add tetraethyl orthosilicate, and continue to maintain the stirring condition at 55°C and 500 rpm for 2.5 h; finally, add hexadecyltrimethoxysilane, and adjust the stirring speed to 780 rpm, maintain the stirring condition at 55°C for 3.5 h, to obtain low-surface-energy nanoparticles. Brush the low-surface-energy nanoparticles on the cement-based material with the bottom protective structure layer and the intermediate candle soot structure layer to form a top low-surface-energy nanoparticle structure layer.

[0084] After the brushed cement-based material is placed in a normal temperature environment for drying for 24 h, a cement-based super-hydrophobic material with a multi-level structure is formed.

[0085] Comparative Example 1

[0086] Comparative Example 1 is a blank group cement-based material without brushing any coating.

[0087] Comparative Example 2

[0088] Comparative Example 2 only coats the bottom protective structure layer, and the specific process is referred to step (1) in Example 3.

[0089] Comparative Example 3

[0090] Comparative Example 3 coats the bottom protective structure layer and the candle soot structure layer, and the specific process is referred to steps (1) and (2) in Example 3.

[0091] Comparative Example 4

[0092] When the inventors studied the difference between the step-by-step coating of each layer and the one-time coating after mixing the three layers of raw materials, the raw materials of each layer were mixed according to the ratio of Example 3, and stirred at a speed of 500 rpm for 5 hours under constant temperature water bath condition at 30°C. However, after the stirring was completed, it was found that there were a large amount of flocculent precipitates in the product, and obvious solid-liquid separation occurred after standing, and a uniform coating that could be brushed was not formed. This shows that the ideal coating effect cannot be obtained by only mixing the raw materials of each layer, and the step-by-step coating method of each layer has a significant advantage, which can effectively avoid such problems, so as to achieve a better coating effect.

[0093] Performance Test

[0094] The performance tests were carried out on some representative examples and comparative examples, and the test items and methods are as follows:

[0095] Wettability test: The contact angle of the examples and the comparative examples was determined by using an optical contact angle tester (DSA 100, Germany Krüss). Five random points were selected on the test surface of each sample, and the average value of the obtained contact angle was calculated as the test result. The roll-off angle of the examples and the comparative examples was determined by using an optical contact angle meter (OCA 20, Germany Dataphysics). The wettability test was carried out at room temperature with 4 μL of deionized water.

[0096] Water absorption test: The test was carried out according to the requirements of GBT50082-2009 "Standard for Testing Methods of Long-term Performance and Durability of Ordinary Concrete".

[0097] Deicing thrust test: A 20 mm side length cube without bottom mold was filled with water and placed on the surface of the sample. After being placed in a refrigerator at -17°C for 4 hours, the ice was pushed down from the sample surface by a digital thrust meter to test the deicing thrust.

[0098] Adhesive tape peeling test: 3M 610 transparent test tape with a width of 25 mm was used to peel off the microstructure on the super-hydrophobic surface. The mechanical durability of the coating was evaluated by measuring the wetting performance of the coating surface after peeling.

[0099] Sand impact test: The sand impact test simulated the long-term performance change of the coating in the outdoor sand environment. The sand with a particle size of 200-600 μm was released from a height of 30 cm at a speed of 200 g / min through a funnel, and impacted the surface of the coating sample. The mechanical durability of the coating was evaluated by measuring the change in wetting performance of the coating surface after impact.

[0100] The test results are shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104] Note: " / " in the table represents no actual measurable points.

[0105] As shown in Table 1, the contact angle of the super-hydrophobic coating described in Examples 1-3 is above 150°, and the roll-off angle is below 10°, which meets the super-hydrophobic requirement. Among them, the super-hydrophobic performance of Example 3 is the best, as shown in Figure 2 , the droplet is spherical, and the super-hydrophobic performance is excellent. The coating surface is constructed with a nano-micron level rough structure, as shown in Figure 3 , which can reduce the adhesion of liquid and part of solid pollutants to the coating surface, improve the waterproof performance of the coating, and also has a self-cleaning effect, reducing the maintenance cost of the building.

[0106] Compared with the comparative example, the water absorption of Examples 1-3 decreased significantly. Figure 4 As shown in the figure, compared with the comparative example 1, the water absorption rate of the embodiment 3 is greatly reduced, reaching a minimum of 1.49%, which will reduce the erosion of water and harmful ions on the interior of the cement-based material. The deicing force of the embodiments 1-3 is less than that of the comparative example, which shows that the coating has good ice-repellent performance. Figure 5 and Figure 6 As shown, the coating in Example 3 can still maintain good hydrophobic properties after undergoing 50 tape stripping cycles and 1000 kg of sand dynamic abrasion, which will provide good protection for the long-term working performance of cement-based materials.

[0107] The reason for these test results is that this composite coating has a multi-level structure. The middle candle ash layer and the top low-surface-energy nanoparticle layer provide a superior multi-level roughness structure. The low-surface-energy groups carried by the nanoparticles work together with some of the low-surface-energy groups carried by the bottom protective layer to significantly reduce the wettability of the material surface, thereby improving the cement-based material's resistance to aquatic erosion. Furthermore, when subjected to mechanical wear and dynamic loads, the bottom protective layer comes into play, protecting the internal roughness structure and low-surface-energy groups and extending the coating's service life. Even if further wear and tear occurs, the multi-level structure gradually resists damage, ensuring the long-term persistence of hydrophobicity.

[0108] The super-hydrophobicity and high mechanical durability demonstrated in the above examples in the tests provide advantages for cement-based materials to maintain good working performance for a long time in long-term humid environments. This proves that the cement-based super-hydrophobic coating provided by the present invention can protect cement-based materials from damage in mechanical wear or dynamic load (falling sand) environments, which will reduce the occurrence of some safety accidents and also reduce the cost of building repair and maintenance.

[0109] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0110] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that variations, modifications, substitutions and changes can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A cement-based coating, characterized in that: include: a first coating comprising hydroxyl-terminated polydimethylsiloxane and a curing agent; a second coating comprising candle soot; as well as The third coating comprises low-surface-energy nanoparticles, and the raw materials of the low-surface-energy nanoparticles comprise ethanol, ammonia water, ethyl orthosilicate and hexadecyltrimethoxysilane.

2. The cement-based coating according to claim 1, characterized in that The mass ratio of the terminal hydroxyl polydimethylsiloxane to the curing agent is (8-12):1; Optionally, the curing agent includes at least one of ethyl orthosilicate and dibutyltin dilaurate; Optionally, the volume ratio of the ethanol, the ammonia water, the tetraethyl orthosilicate and the above is (45-55):(2-5):(2-5):(2.5-3.5); Optionally, the mass fraction of the ammonia water is 25%-28%.

3. The cement-based coating according to claim 1, characterized in that The particle size of the candle ash is 1.5 μm-3.5 μm; Optionally, the particle size of the low surface energy nanoparticles is 50 nm to 100 nm.

4. A method for preparing the cement-based coating according to any one of claims 1 to 3, characterized in that: include: Performing a first mixing process on the hydroxy-terminated polydimethylsiloxane and the curing agent to obtain a first coating; Performing an incomplete combustion treatment on the candle, collecting the candle ash, and obtaining a second coating; The ethanol, ammonia water, ethyl orthosilicate and hexadecyltrimethoxysilane are subjected to a second mixing process to obtain a third coating.

5. The method according to claim 4, characterized in that The second mixing process further comprises: performing a third mixing process on the aqueous ammonia and the ethanol to obtain a third mixed treatment product; performing a fourth mixing treatment on the third mixed product and the ethyl orthosilicate to obtain a fourth mixed product; The fourth mixing product is subjected to a fifth mixing process with the hexadecyltrimethoxysilane to obtain the third coating.

6. The method according to claim 5, characterized in that The first mixing process is performed by a first stirring mode, wherein the first stirring speed is 300 rpm-450 rpm; optionally, the first stirring time is 25 min-35 min; optionally, the first stirring temperature is 25° C.-35° C.; Optionally, the third mixing treatment is performed using a second stirring mode, the second stirring speed is 400 rpm-550 rpm; optionally, the second stirring time is 25 min-35 min; optionally, the second stirring temperature is 40° C.-60° C.; Optionally, the fourth mixing treatment is performed using the third stirring mode, the third stirring speed is 400 rpm-550 rpm; optionally, the third stirring time is 2 h-3 h; optionally, the third stirring temperature is 40° C.-60° C.; Optionally, the fifth mixing treatment is performed using a fourth stirring method, the fourth stirring speed is 650 rpm-800 rpm; optionally, the fourth stirring time is 2.5 h-4 h; optionally, the fourth stirring temperature is 40° C.-60° C.

7. Use of the cement-based coating according to any one of claims 1 to 3 or the cement-based coating prepared by the method according to any one of claims 4 to 6 in improving at least one of the hydrophobicity and durability of cement-based materials.

8. A multi-level structural cement-based material, characterized in that: include: A cement-based material and a cement-based coating applied on the surface of the cement-based material; the cement-based coating is the cement-based coating according to any one of claims 1 to 3 or a cement-based coating prepared by the method according to any one of claims 4 to 6.

9. A method for preparing the multi-level structural cement-based material according to claim 8, characterized in that: include: The cement-based coating according to any one of claims 1 to 3 or the cement-based coating prepared by the method according to any one of claims 4 to 6 is applied on the surface of a cement-based material.

10. The method according to claim 9, characterized in that The coating comprises: Applying the first coating of the cement-based coating on the surface of the cement-based material; Before the first coating is cured, applying a second coating of the cement-based coating on the surface of the first coating; Applying a third coating of the cement-based coating on the surface of the second coating; After the coating is solidified, the multi-level structure cement-based material is obtained.

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