Preparation method and application of super-hydrophobic silicon oxide nanofilament and preparation method of super-hydrophobic coating
By preparing superhydrophobic silica nanowires in organic solvents, the problems of complex preparation and environmental friendliness of existing superhydrophobic materials have been solved, enabling the construction and application of low-cost and environmentally friendly superhydrophobic coatings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2024-05-09
- Publication Date
- 2026-06-23
AI Technical Summary
The existing superhydrophobic materials have complex preparation processes that require damage to the substrate material or the use of fluorine-containing compounds, which limits their practical application and environmental friendliness.
Superhydrophobic silica nanowires were prepared by controlling the hydrolysis and condensation reactions of alkylchlorosilanes and alkylsiloxanes in organic solvents to form a random aspect ratio nanowire structure. The low surface energy of the alkyl chain simplifies the preparation process and achieves superhydrophobic properties.
It enables low-cost, large-scale, and rapid construction of superhydrophobic coatings with excellent superhydrophobic properties, suitable for self-cleaning and oil-water separation applications, and is environmentally friendly and non-toxic.
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Figure CN118419943B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of superhydrophobic material preparation technology, specifically relating to a method for preparing and applying superhydrophobic silica nanowires and a method for preparing superhydrophobic coatings. Background Technology
[0002] Nature-inspired superhydrophobic surfaces have seen rapid development over the past 20 years. Through the synergistic effect of multi-level physical structures at the nanoscale and / or microscale with low surface energy materials, an air barrier is formed between a water droplet placed on a superhydrophobic surface and the solid structure, allowing the droplet to exhibit Cassie-Baxter contact and maintain its spherical shape. Due to the small contact area and low adhesion between the droplet and the solid surface, superhydrophobic surfaces have broad application prospects in areas such as corrosion protection, self-cleaning, antifouling, and oil-water separation.
[0003] Based on the fundamental idea of combining rough structures with low surface energy materials, researchers have developed various methods to construct superhydrophobic materials, such as reactive ion etching, template methods, chemical vapor deposition, layer-by-layer assembly, and colloidal assembly. These methods either damage the substrate material to achieve the rough structure or require complex fabrication processes to obtain the synergy between the physical structure and the low surface energy material, significantly limiting the practical application of superhydrophobic surfaces. Furthermore, most superhydrophobic materials achieve their properties by introducing perfluorosilanes, and the use of fluorine-containing materials increases ecological risks. Considering the characteristics of superhydrophobic materials and the practical application requirements, developing superhydrophobic silica nanowires—a key material with a simple fabrication process—is crucial for achieving low-cost, large-scale, and rapid construction and application development of superhydrophobic coatings. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing superhydrophobic silica nanowires and their applications, as well as a method for preparing superhydrophobic coatings.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A method for preparing superhydrophobic silica nanowires involves using alkylchlorosilanes and / or alkylsiloxanes as structural reagents and organic reagents with different water contents as solvents. The two are mixed and the silanes in the structural reagents are hydrolyzed and condensed by water in the solvent to prepare silica nanowires. The structural reagents and solvents are mixed in a volume ratio of 1:100 to 1:2000, preferably 1:200 to 1:1000.
[0007] The concentration of water in the solvent is 80-500 ppm, preferably 120-166 ppm; the organic reagent is one or more of toluene, chlorobenzene, p-xylene, n-butylbenzene, chloroform, acetone, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-hexadecane, 1,2-dichloroethane, and 1,1,2,2-tetrachloroethane; preferably one or more of toluene, p-xylene, chloroform, n-hexane, n-heptane, and n-hexadecane.
[0008] The alkyl chains in the alkylchlorosilanes and / or alkylsiloxanes have 1-18 carbon atoms. The alkyl chains include methyl, ethyl, propyl, hexyl, octyl, nonyl, decyl, dodecyl, hexadecyl, and octadecyl.
[0009] The structural reagent is one or more of the following: trichlorosilane, trimethoxysilane, triethoxysilane, triisopropoxysilane, tri-n-propoxysilane, tri-n-butoxysilane, and triacetoxysilane, which have 1-18 carbon atoms.
[0010] Furthermore, the structural reagent and solvent are mixed in proportion, and the mixture is stirred and reacted at 15-30℃ for 1h-12h. Through the controlled hydrolysis and condensation of the structural reagent, silica nanowires are formed. The product is obtained after separation and drying. The preferred reaction temperature is 20-25℃ and the reaction time is 3h-6h.
[0011] The separated liquid phase is used to obtain the solvent for the reaction through distillation or molecular sieve adsorption, and it can be recycled.
[0012] The prepared superhydrophobic silica nanowires have a diameter of 40nm-88nm and a length of over 500nm.
[0013] An application of the superhydrophobic silica nanowires prepared by the method described above, specifically their application in the preparation of superhydrophobic coatings.
[0014] A method for preparing a superhydrophobic coating involves preparing a dispersion of the prepared superhydrophobic silica nanowires using a solvent, and then spraying the dispersion onto different substrate surfaces to form a superhydrophobic coating.
[0015] The solvent in the dispersion is one or more organic reagents with different water contents used in the preparation of the superhydrophobic silica nanowires obtained above.
[0016] The solvent in the dispersion may be the same or different and may be selected from one or more organic reagents with different water contents used in the preparation of the superhydrophobic silica nanowires obtained above.
[0017] The superhydrophobic silica nanowires, when sprayed onto the material surface, appear white, and the nanowires accumulate to form a rough, porous structure; the coating has superhydrophobic properties, with a contact angle of 162° or higher for a 5μL water droplet.
[0018] The preparation method of this invention promotes the advancement of superhydrophobic surfaces and plays a positive role in realizing the low-cost, large-scale, and rapid construction of superhydrophobic coatings and expanding their practical applications.
[0019] This invention simplifies the preparation of silica nanowires and enables large-scale production by utilizing the controlled hydrolysis and condensation reactions of alkylchlorosilanes and alkylsiloxanes in organic solvents with a certain water content. The resulting silica nanowires exhibit excellent superhydrophobic properties and show promising applications in self-cleaning, oil-water separation, and anti-icing fields.
[0020] This invention has the following advantages and positive effects:
[0021] 1. This invention prepares superhydrophobic silica nanowires by controlled hydrolysis and condensation of alkylchlorosilanes and / or alkylsiloxanes in an organic solvent containing a small amount of water. No additional surfactants, emulsifiers or other structural template components are required. The reaction system is simple and has few solvent impurities after the reaction. It can be recycled by simple water removal, thus meeting economic and environmental requirements.
[0022] 2. The preparation conditions of this invention are mild. Silica nanowires can be prepared by simple stirring and oscillation at a mild temperature, without relying on complex production equipment. The prepared silica nanowires can be analyzed from the system by centrifugation, filtration, etc., without the need for additional post-processing.
[0023] 3. The silica nanowires prepared by this invention have a large aspect ratio and random morphology, which makes it easy to form a rough multi-level structure in the coating. At the same time, the alkyl chain in the structural reagent endows the nanowires with low surface energy, so that the coating based on silica nanowires has ideal superhydrophobic properties.
[0024] 4. The preparation process is simple to operate, easy to master, has mild reaction conditions, and is easy to scale up for production. Attached Figure Description
[0025] Figure 1 This is a SEM image of the silica nanowires prepared in Example 1 of the present invention.
[0026] Figure 2 The diagram illustrates superhydrophobic coatings constructed on different substrate materials according to embodiments of the present invention; wherein, a is a glass substrate, b is a PET substrate, c is an aluminum substrate, d is a fabric substrate, and e is a gold-ITO electrode.
[0027] Figure 3Contact angle photographs of superhydrophobic coatings formed on different substrate materials are provided for embodiments of the present invention; wherein, Figure 3 A is a glass substrate. Figure 3 B represents the aluminum substrate. Figure 3 C represents the fabric substrate.
[0028] Figure 4 This is a SEM image of the silica nanowires prepared in Example 2 of the present invention.
[0029] Figure 5 This is a SEM image of the silica nanowires prepared in Example 3 of the present invention.
[0030] Figure 6 This is a SEM image of the SiO2 nanoparticle coating provided in Comparative Example 1 of the present invention.
[0031] Figure 7 This is a diagram illustrating the SiO2 nanoparticle coating provided in Comparative Example 1 of the present invention, with a contact angle of 45°.
[0032] Figure 8 The image shows a SEM image of the SiO2 nanoparticles and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite coating provided in Comparative Example 2 of this invention.
[0033] Figure 9 This is a diagram illustrating the superhydrophobic coating of SiO2 nanoparticles and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) provided in Comparative Example 2 of the present invention, with a contact angle of 148°. Detailed Implementation
[0034] The present invention will be further explained below with reference to specific embodiments and accompanying drawings.
[0035] This invention utilizes the controlled hydrolysis of trifunctional silanes with alkyl chains in organic reagents with a certain water content range to generate nanowire structures. More specifically, it employs the spatial asymmetry of specific silane molecules to avoid forming spherical structures and controls the water content in the solvent to control filament formation. Simultaneously, it can form tiny water droplets. Silane molecules hydrolyze and condense into asymmetric structures within these droplets. Because silane molecules contain hydrophobic groups, and the overall result of hydrolysis and condensation leads to a reduction in water content, the small water droplets distribute near the uncondensed silanol groups in the asymmetric structure, thereby promoting the hydrolysis and condensation of new silane molecules. This further increases the asymmetric structure, forming a filament structure. Furthermore, the superhydrophobic properties of the formed material are due to the random nature of the silicon nanowires, which can stack to form a rough structure. Additionally, the carbon chains in the silane on the nanostructure surface possess low surface energy properties. The combination of these two factors achieves the superhydrophobic performance.
[0036] Example 1
[0037] (1) Add 16.6 mg of water to 100 mL of dry toluene and use ultrasound to dissolve the water into the toluene to obtain a toluene aqueous solution with a water content of 166 ppm.
[0038] (2) Measure 0.5 mL of methyltrichlorosilane and add it to a toluene aqueous solution while stirring at 200 rpm. Continue stirring at room temperature (22°C) for 3 h. The volume ratio of methyltrimethoxysilane to toluene aqueous solution is 1:200.
[0039] (3) The silica nanowires generated by the reaction were separated by centrifugation at 3000 rpm for 10 min and dried at 60 °C to obtain the product (see [reference]). Figure 1 ).
[0040] (4) 1.5g of the prepared silica nanowires were redispersed in 5mL of toluene aqueous solution and coated onto the surfaces of glass, PET, aluminum, polyester fiber, and gold-ITO electrodes by spraying to form a coating.
[0041] Depend on Figure 1 SEM images of the silica nanowires show that they have diameters of 40-80 nm and lengths exceeding 500 nm. The nanowires exhibit a curved shape and their surfaces possess nanoscale protrusions. Figure 2 The prepared silica nanowires can be uniformly coated with a white coating on different substrates by spraying.
[0042] The surface wettability of the silica nanowire coatings obtained in step (4) of the above embodiments on different substrate materials was determined: Figure 3 Photographs of the contact angles of the silica nanowire coating. The silica nanowire coating has excellent superhydrophobic properties. The contact angles of a 5 μL water droplet on the surfaces of glass, aluminum, and fiber fabric coated with silica nanowires are 172°, 170°, and 162°, respectively.
[0043] Example 2
[0044] The difference from Example 1 is that, following the preparation method of Example 1, the mass of water in step 1) is replaced with 30 mg, and the water content in the toluene is adjusted to 300 ppm (see Example 1). Figure 4 ).
[0045] Depend on Figure 4 It is evident that the formed silica nanowires still maintain a random high aspect ratio structure.
[0046] Example 3
[0047] The difference from Example 1 is that, according to the preparation method of Example 1, toluene in step 1) is replaced with chloroform (see Example 1). Figure 5 ).
[0048] Depend on Figure 5 It is evident that the formed silica nanowires still have a rough structure, maintaining a large aspect ratio and irregularity.
[0049] Example 4
[0050] The difference from Example 1 is that, according to the preparation method of Example 1, methyltrichlorosilane in step 2) is replaced with methyltrimethoxysilane.
[0051] Example 5
[0052] The difference from Example 1 is that, according to the preparation method of Example 1, the amount of methyltrichlorosilane in step 2) is adjusted to 0.1 ml, and the volume ratio of methyltrichlorosilane to toluene is adjusted to 1:1000.
[0053] Example 6
[0054] The difference from Example 1 is that, according to the preparation method of Example 1, the reaction temperature in step 2) is adjusted to 25°C and the reaction time is adjusted to 1.5h.
[0055] Example 7
[0056] The difference from Example 1 is that, according to the preparation method of Example 1, the stirring in steps 1) and 2) is replaced with oscillation at a speed of 200 rpm.
[0057] The silica nanowires obtained in Examples 2-7 above can all achieve a large aspect ratio and exhibit a random morphology, thereby forming superhydrophobic properties on the substrate.
[0058] Comparative Example 1
[0059] Preparation of SiO2 nanoparticle coating:
[0060] Preparation of SiO2 nanoparticles: 100 ml of anhydrous ethanol and 6 ml of ammonia (28%) were added to a 250 ml round-bottom flask, and the mixture was magnetically stirred at 500 rpm for half an hour. 2 ml of tetraethyl orthosilicate (TEOS) was added to the mixture, and the reaction was carried out at 500 rpm for 15 hours. The product was centrifuged at 9000 rpm for 15 minutes. The precipitate was thoroughly dispersed in anhydrous ethanol, and then washed by centrifugation. This process was repeated three times until the final product was dispersed in anhydrous ethanol.
[0061] Preparation of SiO2 nanoparticle coating: The SiO2 dispersion was thoroughly treated under ultrasonic conditions to avoid the formation of agglomerates, and then a uniform coating was formed on the glass surface by spraying. SEM images of the coating are shown below. Figure 6 The particles form a dense structure (particle assembly causes some line defects). The contact angle of a 5ul water droplet on this surface is approximately 45°. Figure 7 ).
[0062] Comparative Example 2
[0063] Preparation of SiO2 nanoparticles and poly(vinylidene fluoride-co-hexafluoropropylene) composite superhydrophobic coating:
[0064] First, poly(vinylidene fluoride-co-hexafluoropropylene) with a molecular weight of approximately 470,000 was dissolved in DMF and then diluted 10 times with tetrahydrofuran.
[0065] A coating is formed by alternately spraying SiO2 particle dispersion and PVDF-HFP solution onto a glass substrate. Figure 8 The mass ratio of SiO2 particles to polymer in the coating is maintained at 5:1. The prepared coating is heated at 60°C for 1 hour to completely evaporate and remove the solvent, thus obtaining the superhydrophobic composite coating. The contact angle of a 5 μL water droplet on this surface is approximately 148°. Figure 9 ).
[0066] In summary, compared with the comparative example, the material preparation process of this invention is simpler, while exhibiting superior superhydrophobic properties and being easily applicable to various scenarios. This invention utilizes the controlled hydrolysis of trifunctional silanes with alkyl chains in organic reagents within a certain water content range to generate nanowire structures with a large aspect ratio and random morphology. The alkyl chains endow the material with low surface energy, while the nanowire structure provides the necessary physical structure, resulting in silicon oxide nanowires with outstanding superhydrophobic effects. Furthermore, the purified and recyclable organic reagents avoid environmental impact.
[0067] The above description is only a preferred embodiment of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing superhydrophobic silica nanowires, characterized in that: Silica nanowires were prepared by mixing alkylchlorosilanes and / or alkylsiloxanes as structural reagents and organic reagents with different water contents as solvents, and initiating the hydrolysis and condensation of silanes in the structural reagents through water in the solvent; wherein the structural reagents and solvents were mixed in a volume ratio of 1:100-1:2000. The structural reagent is one or more of the following: trichlorosilane, trimethoxysilane, triethoxysilane, triisopropoxysilane, tri-n-propoxysilane, tri-n-butoxysilane, and triacetoxysilane, which have 1-18 carbon atoms. The concentration of water in the solvent is 80-500 ppm.
2. The method for preparing superhydrophobic silica nanowires according to claim 1, characterized in that: The organic reagent is one or more of toluene, chlorobenzene, p-xylene, n-butylbenzene, chloroform, acetone, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-hexadecane, 1,2-dichloroethane, and 1,1,2,2-tetrachloroethane.
3. The method for preparing superhydrophobic silica nanowires according to any one of claims 1-2, characterized in that: The structural reagent and solvent are mixed in proportion and then reacted at 15-30℃ for 1-12 hours by stirring. Through the controlled hydrolysis and condensation of the structural reagent, silica nanowires are formed. The product is obtained after separation and drying.
4. The method for preparing superhydrophobic silica nanowires according to claim 3, characterized in that: The separated liquid phase is used to obtain the solvent for the reaction through distillation or molecular sieve adsorption, and it can be recycled.
5. An application of the superhydrophobic silica nanowires prepared by the method of claim 1, characterized in that: Application of the superhydrophobic silica nanowires in the preparation of superhydrophobic coatings.
6. A method for preparing a superhydrophobic coating, characterized in that: The superhydrophobic silica nanowires prepared according to claim 1 were prepared into a dispersion by solvent, and then sprayed onto different substrate surfaces to form a superhydrophobic coating.
7. The method for preparing the superhydrophobic coating according to claim 6, characterized in that: The solvent in the dispersion is one or more organic reagents with different water contents used in preparing the superhydrophobic silica nanowires prepared according to claim 1.
8. The method for preparing the superhydrophobic coating according to claim 7, characterized in that: The solvent in the dispersion may be the same or different and may be selected from one or more organic reagents with different water contents used in preparing the superhydrophobic silica nanowires prepared according to claim 1.