Preparation method and application of simple and green super-hydrophobic nano silicon dioxide powder

Abstract

The invention discloses a preparation method and application of simple and green super-hydrophobic nano silicon dioxide powder, and belongs to the field of preparation of super-hydrophobic materials. The invention aims to solve the problems that the existing super-hydrophobic nano silicon dioxide preparation process is complicated, the pH value of a system needs to be controlled by additionally adding acid and alkali, a modifier contains fluorine and is toxic, the SiO2 structure is non-uniform, and the hydrophobic performance is unstable. The preparation method comprises the following steps: 1, uniformly stirring n-octyltriethoxysilane, tetraethyl orthosilicate, absolute ethyl alcohol and water; 2, gamma-aminopropyl triethoxy silane is added into the mixture; 3, centrifuging and washing; and 4, drying and grinding. The method is used for preparing a super-hydrophobic coating.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic material preparation. Background Technology

[0002] Due to its unique surface properties and excellent performance, superhydrophobic nano-SiO2 has shown broad application prospects in many fields such as self-cleaning, anti-icing, oil-water separation, fluid drag reduction, corrosion prevention, and medical applications.

[0003] The hydrophobicity of superhydrophobic nano-SiO2 is primarily based on two key factors: low surface energy materials and micro / nano-scale rough structures. These two factors work together to achieve a contact angle greater than 150° and a roll-off angle less than 10° between the material's surface and water, thus realizing superhydrophobic properties. Traditional manufacturing methods typically involve multi-step reaction processes, including first synthesizing nanostructured materials and then post-treating them with low surface energy agents (mostly fluorosilanes). These methods suffer from drawbacks such as complex reactions, stringent reaction conditions, high reagent toxicity, and the resulting superhydrophobic SiO2 structure being inhomogeneous, prone to aggregation, and exhibiting unstable performance. Low surface energy materials (such as fluorosilanes and aminosilanes) can significantly reduce the surface energy of the material, decreasing the interaction between water molecules and the surface. These substances typically adhere to the SiO2 surface through chemical bonding or physical adsorption, forming a hydrophobic layer. Furthermore, micro / nano-scale rough structures increase the surface roughness, further enhancing hydrophobic properties. The rough structure allows water droplets to form air pockets on the surface, reducing the actual contact area between the droplet and the surface, thereby increasing the contact angle and roll-off angle.

[0004] Generally, unmodified nano-SiO2 is hydrophilic because its surface contains hydroxyl (-OH) groups, which can form hydrogen bonds with water molecules. Existing technologies can make it hydrophobic by grafting hydrophobic groups onto its surface. There are three main methods for preparing superhydrophobic nano-SiO2: 1. The Stober method: First, tetraethyl orthosilicate (TEOS) is hydrolyzed in an alcohol / water / ammonia system (controlling the pH value) to generate monodisperse SiO2 nanospheres, then the nanospheres are further modified with long-chain alkyl or fluorosilanes (such as HDTMS, FAS). 2. The sol-gel method: TEOS is first hydrolyzed and condensed under acid or alkali catalysis to form porous SiO2 gel or aerogel, then hydrophobically modified by impregnation or vapor deposition. 3. The vapor-phase method: Gas-phase SiO2 is prepared directly or by reverse hydrolysis of SiCl4 gas, then surface modified by dry or wet methods with a silane coupling agent through high-speed stirring. However, the above three superhydrophobic nano silica preparation processes have problems such as complex processes, the need to add additional acid and alkali to control the pH value of the system, fluorine-containing toxic modifiers, uneven SiO2 structure, and unstable hydrophobic properties. Summary of the Invention

[0005] This invention aims to solve the problems of complex preparation processes for superhydrophobic nano-silica, the need to add additional acid or alkali to control the pH value of the system, the toxicity of fluorine-containing modifiers, the non-uniform structure of SiO2, and the unstable hydrophobic properties. It provides a simple and green method for preparing superhydrophobic nano-silica powder and its application.

[0006] A simple, green, superhydrophobic nano-silica powder preparation method is carried out according to the following steps:

[0007] 1. At room temperature, n-octyltriethoxysilane, tetraethyl orthosilicate, anhydrous ethanol and water are stirred until homogeneous to obtain mixed solution A;

[0008] 2. Mix γ-aminopropyltriethoxysilane with mixed solution A and stir to react, to obtain system B;

[0009] 3. System B was centrifuged and washed multiple times to obtain superhydrophobic nano-SiO2 solid;

[0010] Fourth, the superhydrophobic nano-SiO2 solid is dried and ground to obtain superhydrophobic nano-silica powder.

[0011] An application of a superhydrophobic nano silica powder for the preparation of superhydrophobic coatings.

[0012] The beneficial effects of this invention are:

[0013] This invention utilizes a partial hydrolysis-condensation reaction of tetraethyl orthosilicate, n-octyltriethoxysilane, and γ-aminopropyltriethoxysilane in an air atmosphere to form aggregates of nanoparticles. Some hydrophobic groups remain on the SiO2 surface, thus completing the synthesis and modification in a single step. The resulting SiO2 particles possess micro / nano structures and low surface energy groups, achieving ultra-high hydrophobic properties. Furthermore, the entire reaction process does not require the addition of additional acids or bases to control the pH of the system.

[0014] This invention provides a one-step method for preparing superhydrophobic SiO2. The product obtained by this method is amorphous SiO2 with relatively uniform particle size. The product consists of nanoscale particles (20nm~50nm) aggregated together, and due to the varying degrees of aggregation, it possesses a roughness. Therefore, compared with previous preparation methods, this method avoids the drawbacks of secondary modification on the hydrophilic nano-SiO2 surface, as well as the instability of hydrophobicity, complex processes, stringent experimental conditions, and environmental unfriendliness.

[0015] The superhydrophobic nano-SiO2 obtained by this invention has a contact angle with water >150°, and the superhydrophobicity of the product hardly changes when it is sealed and stored at room temperature for 6 months.

[0016] The preparation method of this invention is simple, low-cost, and environmentally friendly. The product can be sealed and stored for a long time at room temperature, making it suitable for large-scale industrial production. Attached Figure Description

[0017] Figure 1 The image shows the XRD pattern of the superhydrophobic nano-silica powder prepared in Example 1.

[0018] Figure 2 This is a TEM image of the superhydrophobic nano-silica powder prepared in Example 1;

[0019] Figure 3 SEM images of the superhydrophobic nano silica powder prepared in Example 1, (a) scale bar is 1 μm, (b) scale bar is 10 μm;

[0020] Figure 4 This is a particle size distribution diagram of the superhydrophobic nano-silica powder prepared in Example 1;

[0021] Figure 5 The graph shows the hydrophobic properties of the superhydrophobic nano-silica powder prepared in Example 1.

[0022] Figure 6 The image shows the hydrophobic properties of the superhydrophobic nano-silica powder prepared in Example 1 after 6 months of storage.

[0023] Figure 7 The superhydrophobic properties of the superhydrophobic nano-silica powder prepared in Example 1 under different chemical environments;

[0024] Figure 8 The image shows the contact angle test results of the superhydrophobic coating prepared in Example 2 with water.

[0025] Figure 9 The image shows the roll-off angle test result of the superhydrophobic coating prepared in Example 2 with water.

[0026] Figure 10 The image shows the wetting pattern of a 6 μL water droplet adhering to the surface of the superhydrophobic coating prepared in Example 2: (a) the droplet descending stage, (b) the droplet contacting the coating stage, (c) the droplet continuing to be pressed down and deformed stage, (d) the droplet rising stage, and (e) the droplet continuing to rise and completely leaving the coating stage.

[0027] Figure 11 This is a diagram showing the surface depression formed when the superhydrophobic coating prepared in Example 2 is immersed in water;

[0028] Figure 12 The contact angle test results of the superhydrophobic coating prepared in Example 2 after 30 wear cycles (1200 cm) are shown.

[0029] Figure 13The contact angle test diagram of the superhydrophobic coating prepared in Example 2 after immersion in hydrochloric acid solution with pH 3 for 12 hours is shown.

[0030] Figure 14 The contact angle test diagram of the superhydrophobic coating prepared in Example 2 after immersion in a sodium hydroxide solution with pH 13 for 12 hours is shown.

[0031] Figure 15 The image shows the contact angle of the superhydrophobic coating prepared in Example 2 after immersion in an aqueous solution at 70°C for 12 hours. Detailed Implementation

[0032] Specific Implementation Method 1: This implementation method provides a simple, green, superhydrophobic nano-silica powder preparation method, which is prepared according to the following steps:

[0033] 1. At room temperature, n-octyltriethoxysilane, tetraethyl orthosilicate, anhydrous ethanol and water are stirred until homogeneous to obtain mixed solution A;

[0034] 2. Mix γ-aminopropyltriethoxysilane with mixed solution A and stir to react, to obtain system B;

[0035] 3. System B was centrifuged and washed multiple times to obtain superhydrophobic nano-SiO2 solid;

[0036] Fourth, the superhydrophobic nano-SiO2 solid is dried and ground to obtain superhydrophobic nano-silica powder.

[0037] Principle: The propylamine group on γ-aminopropyltriethoxysilane (APTES) catalyzes the intermolecular condensation reaction of ethoxy groups on tetraethyl orthosilicate (TEOS) and n-octyltriethoxysilane. By controlling the proportions of APTES, water, and ethanol, the amount of hydrolysis and condensation can be controlled, allowing the ethoxy groups of TEOS, n-octyltriethoxysilane, and APTES molecules to form a three-dimensional network through incomplete covalent condensation. The condensed portion forms a Si-O-Si inorganic framework structure, while the uncondensed portion has Si atoms bonded to organic groups (n-octyl and residual ethoxy groups), reducing surface energy and forming low surface energy regions. The propylamine group of APTES regulates particle packing through steric hindrance, forming a micro / nano composite structure. Therefore, this method successfully prepares superhydrophobic nano-silica powder in one step. The hydrophobic functional groups are inherent in the reactant structure, exhibiting strong chemical bonds, uniform dispersion, and stable hydrophobic properties. The superhydrophobic SiO2 generated during the incomplete covalent condensation process is a micro-nano phase structure (nanoparticle aggregate) composed of aggregates with a particle size of 20nm~50nm. Combined with low surface energy groups, it ultimately achieves superhydrophobic properties with a contact angle >150°.

[0038] The beneficial effects of this embodiment are:

[0039] In this embodiment, under an air atmosphere, an incomplete hydrolysis-condensation reaction is carried out using tetraethyl orthosilicate, n-octyltriethoxysilane, and γ-aminopropyltriethoxysilane to form aggregates of nanoparticles. Some hydrophobic groups remain on the SiO2 surface, thus completing the synthesis and modification in one step. The resulting SiO2 particles possess micro / nano structures and low surface energy groups, achieving ultra-high hydrophobic properties. Furthermore, the entire reaction process does not require the addition of additional acids or bases to control the pH of the system.

[0040] This embodiment describes a one-step method for preparing superhydrophobic SiO2. The product obtained by this method is amorphous SiO2 with relatively uniform particle size. The product consists of nanoscale particles (20nm~50nm) aggregated together, and due to the varying degrees of aggregation, it possesses a roughness. Therefore, compared with previous preparation methods, this method avoids the drawbacks of secondary modification on the hydrophilic nano-SiO2 surface, as well as the instability of hydrophobicity, complex processes, stringent experimental conditions, and environmental unfriendliness.

[0041] The superhydrophobic nano-SiO2 obtained using this embodiment has a contact angle with water >150°, and the superhydrophobicity of the product hardly changes when it is sealed and stored at room temperature for 6 months.

[0042] The preparation method described in this embodiment is simple, low-cost, and environmentally friendly. The product can be sealed and stored for a long time at room temperature, making it suitable for large-scale industrial production.

[0043] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the volume ratio of n-octyltriethoxysilane to tetraethyl orthosilicate in step one is 1:(4~10). Everything else is the same as in Specific Implementation Method One.

[0044] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the volume ratio of n-octyltriethoxysilane to anhydrous ethanol in step one is 1:(0.2~2). Everything else is the same as in Specific Implementation Method One or Two.

[0045] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the volume ratio of n-octyltriethoxysilane to water in step one is 1:(0.2~1). Everything else is the same as in Specific Implementation Methods One to Three.

[0046] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: in step one, octyltriethoxysilane, tetraethyl orthosilicate, anhydrous ethanol, and water are stirred evenly at room temperature and a stirring speed of 400 r / min to 1000 r / min. Everything else is the same as in Specific Implementation Methods One to Four.

[0047] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the volume ratio of n-octyltriethoxysilane to γ-aminopropyltriethoxysilane in the mixed solution A described in step two is 1:(0.5~4). Everything else is the same as in Specific Implementation Methods One to Five.

[0048] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that: in step two, the reaction is carried out under the conditions of a temperature of 25℃~50℃ and a rotation speed of 400r / min~1000r / min for 8h~48h. Everything else is the same as in Specific Implementation Method Six.

[0049] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step three, centrifugation is performed at a speed of 4000 r / min to 8000 r / min for 5 min to 20 min, followed by washing with anhydrous ethanol, and the centrifugation and washing are repeated 1 to 3 times; the drying in step four is specifically performed at a temperature of 60℃ to 100℃ for 8 h to 2 h. Everything else is the same as in Specific Implementation Methods One to Seven.

[0050] Specific Implementation Method Nine: This implementation method describes the application of a simple, green superhydrophobic nano-silica powder for the preparation of a superhydrophobic coating.

[0051] In this specific embodiment, the prepared superhydrophobic nano silica powder is added to epoxy resin (EP) to obtain a fluorine-free superhydrophobic coating, forming a SiO2-EP superhydrophobic composite coating on the substrate. The coating preparation process is green and environmentally friendly and simple, and has good wear resistance and durability.

[0052] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the superhydrophobic coating is specifically prepared according to the following steps:

[0053] 1. Mix epoxy resin and superhydrophobic nano silica powder, then add ethanol, and ultrasonically disperse for 15 min to 20 min under a power of 400W~500W to obtain dispersion A.

[0054] The mass ratio of the epoxy resin to the superhydrophobic nano silica powder is 1:(0.8~2); the mass ratio of the epoxy resin to ethanol is 1:(10~40);

[0055] 2. Add the polyamide curing agent to ethanol and ultrasonically disperse it for 15 min to 20 min under a power of 400W~500W to obtain dispersion B;

[0056] The mass ratio of the polyamide curing agent to ethanol is 1:(5~20);

[0057] 3. Using zirconium oxide as grinding beads, grind dispersion A for 10 min to 30 min at a speed of 600 r / min to 1500 r / min, then add dispersion B, and continue stirring for 2 min to 5 min at a speed of 600 min to 1000 r / min. Finally, filter with a filter screen to remove the grinding beads and obtain a mixture, which is the superhydrophobic composite coating.

[0058] The mass ratio of dispersion A to dispersion B is 1:(0.2~1.5);

[0059] 4. Apply the superhydrophobic composite coating to the substrate to obtain a wet film with a thickness of 250μm~550μm. Let the wet film stand at room temperature for 20min~60min, then dry it at 40℃~80℃ for 2h~4h to obtain the superhydrophobic coating. Other steps are the same as in Specific Implementation Method Nine.

[0060] The beneficial effects of the present invention are verified using the following embodiments:

[0061] Example 1:

[0062] A simple, green, superhydrophobic nano-silica powder preparation method is carried out according to the following steps:

[0063] 1. Under the conditions of room temperature and stirring speed of 400 r / min, n-octyltriethoxysilane, tetraethyl orthosilicate, anhydrous ethanol and water are stirred evenly to obtain mixed solution A;

[0064] The volume ratio of n-octyltriethoxysilane to tetraethyl orthosilicate is 1:10;

[0065] The volume ratio of n-octyltriethoxysilane to anhydrous ethanol is 1:0.3;

[0066] The volume ratio of the n-octyltriethoxysilane to water is 1:0.2;

[0067] 2. Mix γ-aminopropyltriethoxysilane with mixed solution A, and stir the mixture for 8 hours at a temperature of 50℃ and a rotation speed of 400 r / min to obtain system B;

[0068] The volume ratio of n-octyltriethoxysilane to γ-aminopropyltriethoxysilane in the mixed solution A is 1:1;

[0069] 3. System B was centrifuged and washed multiple times to obtain superhydrophobic nano-SiO2 solid;

[0070] IV. Dry the superhydrophobic nano-SiO2 solid at 60℃ for 6 hours, and then grind it to obtain superhydrophobic nano-silica powder.

[0071] In step three, centrifuge at 4000 r / min for 20 min, then wash with anhydrous ethanol, and repeat centrifugation and washing three times.

[0072] The superhydrophobic nano-silica powder prepared in Example 1 was placed in a container and sealed for storage at room temperature.

[0073] Figure 1 The image shows the XRD pattern of the superhydrophobic nano-silica powder prepared in Example 1; as can be seen from the image, the product is amorphous SiO2.

[0074] Figure 2 The image shows a TEM image of the superhydrophobic nano silica powder prepared in Example 1. As can be seen from the image, the product has a relatively uniform particle size and is composed of nano-sized particles (20nm~50nm). Due to the different degrees of aggregation, the product has roughness.

[0075] Figure 3 The images show SEM images of the superhydrophobic nano silica powder prepared in Example 1. (a) Scale bar is 1 μm, and (b) Scale bar is 10 μm. As can be seen from the images, the product has a uniform particle size, no agglomeration, and good dispersibility.

[0076] Figure 4 This is a particle size distribution diagram of the superhydrophobic nano-silica powder prepared in Example 1; the particles were dispersed in an ethanol solution, and the dispersion size was measured using a laser particle size analyzer. Figure 4 It can be seen that the material is mainly composed of fine nanoparticles with an average particle size of about 16 nm. The vast majority of the particles are between 10 nm and 50 nm in size, indicating that the prepared superhydrophobic nano-silica has good dispersibility in ethanol solution.

[0077] The superhydrophobic properties were determined by measuring the contact angle with water after compaction of the powder. 1g of the superhydrophobic nano-silica powder prepared in Example 1 was taken, placed on a glass slide, and compacted to maintain a smooth surface. The contact angle was then measured using a contact angle meter, with a water droplet size of 5μL used for the measurement. Figure 5 The figure shows the hydrophobic properties of the superhydrophobic nano silica powder prepared in Example 1; as can be seen from the figure, the contact angle between the solid powder and water can reach 168.6°.

[0078] The superhydrophobic nano silica powder prepared in Example 1 was placed in a container and sealed for storage at room temperature for 6 months. Then, it was placed on the surface of a glass slide and the powder was compacted to keep the surface as flat as possible. The contact angle was tested using a contact angle meter. The water droplet used in the contact angle measurement was 5 μL. Figure 6 The figure shows the hydrophobic properties of the superhydrophobic nano silica powder prepared in Example 1 after 6 months of storage. As can be seen from the figure, the hydrophobic angle of the solid powder is 168.1 after 6 months, which proves that its hydrophobicity hardly changes and its stability is excellent.

[0079] Take 1g of the superhydrophobic nano-silica powder prepared in Example 1, place it on the surface of a glass slide and compact the powder to keep the surface as flat as possible. Then, add 20μL of water droplets and 20μL of different solutions (pH=1 hydrochloric acid, pH=14 NaOH solution, 3.5wt.% NaCl solution, cola and tea) to the powder surface and observe the wetting state of the superhydrophobic SiO2 powder under different chemical environments to analyze the superhydrophobicity of the particles. Figure 7 The figure shows the superhydrophobic properties of the superhydrophobic nano-silica powder prepared in Example 1 under different chemical environments. As can be seen from the figure, the superhydrophobic silica particles remain spherical and do not wet in different solutions, indicating that the superhydrophobic silica has excellent acid and alkali resistance.

[0080] Example 2:

[0081] Application of the superhydrophobic nano-silica powder prepared in Example 1: It is used to prepare superhydrophobic coatings;

[0082] The superhydrophobic coating is prepared according to the following steps:

[0083] 1. Mix epoxy resin and superhydrophobic nano silica powder, then add ethanol, and ultrasonically disperse for 20 minutes at a power of 400W to obtain dispersion A.

[0084] The mass ratio of epoxy resin to superhydrophobic nano silica powder is 1:1; the mass ratio of epoxy resin to ethanol is 1:10; the epoxy resin was purchased from Nantong Xing Synthetic Materials Co., Ltd., and the model is E44.

[0085] 2. Add the polyamide curing agent to ethanol and ultrasonically disperse it for 20 minutes at a power of 400W to obtain dispersion B;

[0086] The mass ratio of the polyamide curing agent to ethanol is 1:10; the polyamide curing agent was purchased from Nantong Xing Synthetic Materials Co., Ltd., and the model is 650.

[0087] 3. Using zirconium oxide as grinding beads, grind dispersion A for 20 minutes at a speed of 800 r / min, then add dispersion B and continue stirring for 2 minutes at a speed of 800 r / min. Finally, filter with a filter screen to remove the grinding beads and obtain a mixture, which is the superhydrophobic composite coating.

[0088] The mass ratio of dispersion A to dispersion B is 1:1;

[0089] 4. The superhydrophobic composite coating is coated on the substrate to obtain a wet film with a thickness of 350 μm. The wet film with a thickness of 350 μm is left to stand for 20 min at room temperature, and then dried at 80℃ for 2 h to obtain the superhydrophobic coating.

[0090] The substrate is a pretreated glass slide.

[0091] Figure 8 The image shows the contact angle test results of the superhydrophobic coating prepared in Example 2 with water. Figure 9 The figure shows the roll-off angle test results of the superhydrophobic coating prepared in Example 2 with water. As can be seen from the figure, the contact angle of the superhydrophobic coating prepared in Example 2 with water is 167.6° and the roll-off angle is 3.1°.

[0092] Figure 10 The image shows the wetting of a 6 μL water droplet attached to the surface of the superhydrophobic coating prepared in Example 2. (a) Droplet descent stage, (b) Droplet contact stage with coating, (c) Droplet continues to be pressed down and deformed stage, (d) Droplet rise stage, and (e) Droplet continues to rise and completely leaves the coating stage. As can be seen from the figure, even when the liquid comes into contact with the coating and the water droplet deforms, wetting of the coating does not occur, indicating that the coating has excellent superhydrophobicity.

[0093] Figure 11 The figure shows the liquid surface depression formed when the superhydrophobic coating prepared in Example 2 is immersed in water. As can be seen from the figure, the coating structure exhibits a good air trapping effect. When the coating is immersed in water, there is an obvious depression on the coating surface. A reflective layer is also observed under the liquid surface. This is because air is trapped by the coating surface, forming an extremely thin air cushion between the water and the coating. When the coating is immersed in water, the interface between the air layer and the water will refract light due to the difference in refractive index.

[0094] The abrasion resistance of the superhydrophobic coating prepared in Example 2 was tested using 1000# sandpaper and a 100g weight via the sandpaper abrasion test. The coating was moved horizontally for 20cm, then vertically for 20cm, constituting one cycle (total process 40cm). Figure 12 The image shows the contact angle test results of the superhydrophobic coating prepared in Example 2 after 30 wear cycles (1200 cm). As can be seen from the image, the contact angle of the coating was still 153.7° after 30 wear cycles.

[0095] To evaluate the chemical durability and water resistance of the coating, the superhydrophobic coating was exposed to corrosive solutions (acids, alkalis) and hot water (70°C) for 12 hours, and the hydrophobicity of the coating was tested.

[0096] Figure 13The image shows the contact angle of the superhydrophobic coating prepared in Example 2 after immersion in a hydrochloric acid solution with pH 3 for 12 hours. As can be seen from the image, after immersion in a hydrochloric acid solution with pH 3 for 12 hours, the contact angle of the coating is 150.1°, indicating that the coating can still maintain its superhydrophobicity and has good resistance to strong acids.

[0097] Figure 14 The image shows the contact angle of the superhydrophobic coating prepared in Example 2 after immersion in a sodium hydroxide solution at pH 13 for 12 hours. As can be seen from the image, the contact angle of the coating is 153.9° after immersion in the sodium hydroxide solution at pH 13 for 12 hours, indicating that the coating has good resistance to strong alkali.

[0098] Figure 15 The image shows the contact angle of the superhydrophobic coating prepared in Example 2 after immersion in a 70°C aqueous solution for 12 hours. As can be seen from the image, the contact angle of the coating after immersion in the 70°C aqueous solution for 12 hours is 154.7°, indicating that the coating has good hydrophobicity in high-temperature water. The above results show that the coating has good chemical durability and water resistance.

Claims

1. A simple, green, superhydrophobic nano-silica powder preparation method, characterized in that... It is done in the following steps:

1. At room temperature, n-octyltriethoxysilane, tetraethyl orthosilicate, anhydrous ethanol and water are stirred until homogeneous to obtain mixed solution A; 2. Mix γ-aminopropyltriethoxysilane with mixed solution A and stir to react, to obtain system B; 3. System B was centrifuged and washed multiple times to obtain superhydrophobic nano-SiO2 solid; Fourth, the superhydrophobic nano-SiO2 solid is dried and ground to obtain superhydrophobic nano-silica powder.

2. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... The volume ratio of n-octyltriethoxysilane to tetraethyl orthosilicate in step one is 1:(4~10).

3. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... The volume ratio of n-octyltriethoxysilane to anhydrous ethanol in step one is 1:(0.2~2).

4. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... The volume ratio of n-octyltriethoxysilane to water in step one is 1:(0.2~1).

5. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... In step one, under the conditions of room temperature and a stirring speed of 400 r / min to 1000 r / min, n-octyltriethoxysilane, tetraethyl orthosilicate, anhydrous ethanol and water are stirred evenly.

6. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... In step two, the volume ratio of n-octyltriethoxysilane to γ-aminopropyltriethoxysilane in the mixed solution A is 1:(0.5~4).

7. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... In step two, the reaction is carried out at a temperature of 25℃~50℃ and a rotation speed of 400r / min~1000r / min for 8h~48h.

8. The method for preparing a simple, green, superhydrophobic nano-silica powder according to claim 1, characterized in that... In step three, centrifuge at a speed of 4000 r / min to 8000 r / min for 5 min to 20 min, then wash with anhydrous ethanol, and repeat centrifugation and washing 1 to 3 times; the drying in step four is specifically carried out at a temperature of 60℃ to 100℃ for 8 h to 2 h.

9. The application of the superhydrophobic nano-silica powder prepared according to claim 1, characterized in that... It is used to prepare superhydrophobic coatings.

10. The application of the superhydrophobic nano-silica powder according to claim 9, characterized in that... The superhydrophobic coating is prepared according to the following steps:

1. Mix epoxy resin and superhydrophobic nano silica powder, then add ethanol, and ultrasonically disperse for 15 min to 20 min under a power of 400W~500W to obtain dispersion A. The mass ratio of the epoxy resin to the superhydrophobic nano silica powder is 1:(0.8~2); the mass ratio of the epoxy resin to ethanol is 1:(10~40); 2. Add the polyamide curing agent to ethanol and ultrasonically disperse it for 15 min to 20 min under a power of 400W~500W to obtain dispersion B; The mass ratio of the polyamide curing agent to ethanol is 1:(5~20); 3. Using zirconium oxide as grinding beads, grind dispersion A for 10 min to 30 min at a speed of 600 r / min to 1500 r / min, then add dispersion B, and continue stirring for 2 min to 5 min at a speed of 600 min to 1000 r / min. Finally, filter with a filter screen to remove the grinding beads and obtain a mixture, which is the superhydrophobic composite coating. The mass ratio of dispersion A to dispersion B is 1:(0.2~1.5); 4. Apply the superhydrophobic composite coating to the substrate to obtain a wet film with a thickness of 250μm~550μm. Let the wet film with a thickness of 250μm~550μm stand for 20min~60min at room temperature, and then dry it at a temperature of 40℃~80℃ for 2h~4h to obtain the superhydrophobic coating.

Images