Preparation method of fluorine-free super-hydrophobic nanometer silica cotton fabric

Abstract

This invention discloses a method for preparing a fluorine-free superhydrophobic nano-silica cotton fabric, belonging to the field of superhydrophobic textile technology. The invention utilizes trichlorooctadecylsilane (OTS), γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), and hexadecyltrimethoxysilane (HDTMS) to modify silica, obtaining a fluorine-free superhydrophobic coating. This coating, applied to the surface of the cotton fabric, results in a fabric with both low surface energy and a rough surface structure, exhibiting excellent superhydrophobic properties. Furthermore, it also imparts durability, self-cleaning, and stain-resistant capabilities to the hydrophobic coating.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic textile technology, specifically relating to a method for preparing fluorine-free superhydrophobic nano-silica cotton fabric. Background Technology

[0002] Cotton fabrics possess advantages such as warmth, breathability, and ease of dyeing and finishing, making them widely used in clothing, home furnishings, medical applications, and military applications. However, their use is limited by drawbacks such as susceptibility to staining and wetting. Superhydrophobic surfaces, due to their unique wettability, can be widely used in multifunctional finishing of cotton fabrics. Silica, with its low cost and ease of preparation, has become an important raw material for establishing micro / nano structures and reducing surface tension. However, its poor adhesion to fabrics and low durability affect the application and lifespan of superhydrophobic fabrics. Therefore, developing highly durable and highly hydrophobic coated cotton fabrics is of great value. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a simple and environmentally friendly method for preparing fluorine-free superhydrophobic nano-silica cotton fabric, so as to solve the problems of complex preparation process or fluorine content in superhydrophobic cotton fabric.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] The present invention provides a fluorine-free superhydrophobic coating, which is attached to a cotton fabric and includes a hydrophobic modified silica layer.

[0006] The hydrophobic silica in the hydrophobic silica layer is modified silica; the modifiers include trichlorooctadecylsilane (OTS), γ-glycidoxypropyltrimethoxysilane (KH-560) and hexadecyltrimethoxysilane (HDTMS).

[0007] In one embodiment of the present invention, the particle size of the hydrophobic modified silica is 15-70 nm, more preferably 15 nm-20 nm.

[0008] This invention also provides a method for preparing the fluorine-free superhydrophobic coating described above, comprising the following steps:

[0009] S1. Mix silica, the first modifier, and an alcohol solvent to modify the mixture and obtain hydrophobic silica.

[0010] S2. Disperse the second modifier in water to obtain a mixture;

[0011] S3. Mix the obtained hydrophobic silica, the mixture and the third modifier to obtain a fluorine-free superhydrophobic coating;

[0012] The first modifier, the second modifier, and the third modifier are independently selected from trichlorooctadecylsilane, KH-560, and hexadecyltrimethoxysilane, respectively, and the second modifier and the third modifier are different.

[0013] In one embodiment of the present invention, it is further preferred that the first modifier, the second modifier, and the third modifier are all different.

[0014] In one embodiment of the present invention, the following options are available: the first modifier is trichlorooctadecylsilane, the second modifier is KH-560, and the third modifier is hexadecyltrimethoxysilane.

[0015] In one embodiment of the present invention, the following options are available: the first modifier is hexadecyltrimethoxysilane, the second modifier is KH-560, and the third modifier is trichlorooctadecylsilane.

[0016] In one embodiment of the present invention, the following options are available: the first modifier is KH-560, the second modifier is trichlorooctadecylsilane, and the third modifier is hexadecyltrimethoxysilane.

[0017] In one embodiment of the present invention, the mass ratio of the first modifier, the second modifier, and the third modifier is (4-8):(3-5):1.

[0018] In one embodiment of the present invention, the particle size of the silicon dioxide in S1 is preferably 15-70 nm, and more preferably 15 nm-20 nm.

[0019] In one embodiment of the present invention, the alcohol solvent in S1 is preferably ethanol.

[0020] In one embodiment of the present invention, the mass ratio of silicon dioxide to the first modifier in S1 is 1:(10-20).

[0021] In one embodiment of the present invention, the preferred ratio of silicon dioxide to alcohol solvent in S1 is 1 g:(100-150 mL).

[0022] In one embodiment of the present invention, the mixing of silicon dioxide, the first modifier and the alcohol solvent in S1 is preferably at room temperature and the mixing time is preferably 2 hours.

[0023] In one embodiment of the present invention, the concentration of the second modifier dispersed in water in S2 is 0.1-0.5 g / mL.

[0024] In one embodiment of the present invention, the dispersion temperature in S2 is preferably room temperature, and the dispersion time is preferably 0.5 h.

[0025] In one embodiment of the present invention, the mixing and modification temperature in S3 is 70-90°C and the time is 3 hours.

[0026] The present invention also provides a method for preparing a fluorine-free superhydrophobic nano-silica cotton fabric, which involves coating the cotton fabric with the modified silica sol coating, followed by drying and curing to obtain the fluorine-free superhydrophobic cotton fabric.

[0027] In one embodiment of the present invention, the curing temperature is preferably 90-150°C, more preferably 100-120°C; the curing time is preferably 1-6 min, more preferably 2-3 min.

[0028] The present invention also provides the fluorine-free superhydrophobic fabric described in the above technical solution.

[0029] The present invention also provides the application of the fluorine-free superhydrophobic coating described above in the field of self-cleaning.

[0030] This invention specifically provides a fluorine-free superhydrophobic coating, which is applied to cotton fabric. The fluorine-free superhydrophobic coating includes a hydrophobic modified silica layer attached to the cotton fabric. The surface of the fluorine-free superhydrophobic coating of this invention is loaded with a layer of modified nano-silica particles applied to the cotton fabric surface, giving the coating both low surface energy and a rough surface structure. Simultaneously, controlling the baking temperature in the preparation method to 90–150°C ensures that the hydrophobic coating has a certain degree of durability. The use of modified silica gives the coating superhydrophobicity, thereby providing self-cleaning and anti-fouling capabilities.

[0031] This invention also specifically provides a method for preparing the fluorine-free superhydrophobic cotton fabric described in the above technical solution, comprising the following steps: mixing silica, a modifier, and an alcohol solvent for modification to obtain hydrophobic silica; hydrolyzing KH-560 to obtain KH-560 sol; mixing and modifying the hydrophobic silica, KH-560 sol, and hexadecyltrimethoxysilane; coating the modified silica sol onto a substrate, and performing pre-baking and baking to obtain the fluorine-free superhydrophobic coating. The preparation method provided by this invention is simple to operate and easy to industrialize.

[0032] Furthermore, by controlling the curing temperature to 90–150°C, the adhesion between the fluorine-free superhydrophobic coating and the cotton fabric is further improved.

[0033] Beneficial effects:

[0034] The fluorine-free superhydrophobic coating obtained by this invention has a contact angle of 154.2° or higher and exhibits excellent antifouling performance against a variety of common types of liquids, as well as excellent self-cleaning performance. In addition, the fluorine-free superhydrophobic coating obtained by this invention has a certain degree of durability. After 100 cycles of linear friction and 120 minutes of washing, it still has certain hydrophobic properties, with contact angles of 131.9° or higher and 132.7° or higher, respectively.

[0035] Furthermore, the preferred embodiment of the present invention can achieve better results: the initial contact angle is above 154.2°, and after 100 linear friction cycles and 120 minutes of washing, the water contact angles are above 150.2° and 149.4° respectively, exhibiting excellent hydrophobicity and durability. Attached Figure Description

[0036] Figure 1 The following are test images of the fluorine-free superhydrophobic coating obtained in Example 1; (a) is a test image of the contact angle of the fluorine-free superhydrophobic cotton fabric, showing that the contact angle of the obtained fluorine-free superhydrophobic coating is 154.2°; (b) is the process of water jets being bounced off the treated cotton fabric; (c) is the silver mirror phenomenon observed when the treated cotton fabric is immersed in water.

[0037] Figure 2 Surface morphology of the fluorine-free superhydrophobic coating obtained in Example 1.

[0038] Figure 3 The infrared spectra of raw cotton fabric and OTS / HD-KH@SiO2 coated hydrophobic fabric obtained by Fourier transform infrared spectroscopy are shown.

[0039] Figure 4 Photos showing various common liquids (deionized water, water-soluble dye, cola, milk, coffee, and cooking oil) dropped onto the surfaces of raw cotton fabric and fluorine-free superhydrophobic coatings.

[0040] Figure 5 The diagram shows the self-cleaning performance of the fluorine-free superhydrophobic coating obtained in Example 1; where (a) is the self-cleaning process of reactive dye stains and (b) is the self-cleaning process of dust stains.

[0041] Figure 6 The images show the abrasion resistance test results (a) and soap wash fastness test results (b) of the fabric with the fluorine-free superhydrophobic coating obtained in Example 1. Detailed Implementation

[0042] This invention provides a fluorine-free superhydrophobic coating, which is applied to a cotton fabric and includes a hydrophobic modified silica layer attached to the cotton fabric.

[0043] The hydrophobic modified silica has a particle size of 15-70 nm, more preferably 15-20 nm.

[0044] The fluorine-free superhydrophobic coating provided by this invention comprises a hydrophobic silica layer attached to cotton fabric. In this invention, the hydrophobic silica in the hydrophobic silica coating is preferably modified silica; the modified agent is preferably trichlorooctadecylsilane, KH-560, and hexadecyltrimethoxysilane.

[0045] This invention also provides a method for preparing the fluorine-free superhydrophobic coating described above, comprising the following steps:

[0046] Silicon dioxide, the modifier trichlorooctadecylsilane, and an alcohol solvent were mixed and modified to obtain modified silicon dioxide.

[0047] KH-560 was hydrolyzed to obtain KH-560 sol;

[0048] KH-560 sol, modified silica and hexadecyltrimethoxysilane were mixed and modified at a temperature of 70-90℃ for 3 hours to obtain hydrophobic silica.

[0049] The modified silica sol is impregnated onto cotton fabric, and then pre-dried and baked to obtain the fluorine-free superhydrophobic cotton fabric.

[0050] In this invention, the particle size of the silica is preferably 15–70 nm, more preferably 15 nm–20 nm. The modifier is preferably trichlorooctadecylsilane, KH-560, or hexadecyltrimethoxysilane. In this invention, the alcohol solvent is preferably ethanol.

[0051] In this invention, the preferred ratio of silica to modifier is 1 g:(2-5) mL. In this invention, the preferred ratio of silica to alcohol solvent is 1 g:(100-150 mL).

[0052] In this invention, the mixing of silica, modifier OTS, and alcohol solvent preferably includes the following steps: mixing silica and alcohol solvent to perform a first dispersion to obtain a silica dispersion; and mixing the silica dispersion with the modifier OTS. In this invention, the first dispersion is preferably performed at room temperature for 2 hours, and the amount of OTS added is 2-5 mL.

[0053] In this invention, KH-560 is hydrolyzed to obtain KH-560 sol; the reagent for KH-560 hydrolysis is deionized water; the ratio of the amount of KH-560 to the reagent for KH-560 hydrolysis is 1g:(10-15mL); in this invention, the hydrolysis temperature is preferably room temperature, and the hydrolysis time is preferably 0.5h.

[0054] After modification, KH-560 sol, modified silica and hexadecyltrimethoxysilane are mixed, and the modification temperature is 70-90℃ for 3 hours; the heating equipment is preferably an oil bath.

[0055] After obtaining the hydrophobic modified silica, the present invention coats the modified silica sol onto cotton fabric and dries and cures it to obtain fluorine-free superhydrophobic cotton fabric.

[0056] In this invention, the coating method preferably includes dip coating and spray coating. In this invention, the dip coating temperature of the hydrophobic sol is preferably room temperature, and the time is 2–10 minutes.

[0057] In this invention, the curing temperature is preferably 90–150°C, more preferably 100–120°C; the curing time is preferably 1–6 min, more preferably 2–3 min. The resulting fluorine-free superhydrophobic cotton fabric is thus obtained.

[0058] This invention also provides the fluorine-free superhydrophobic cotton fabric described in the above technical solution, the preparation method described in the above technical solution, and the application of the fluorine-free superhydrophobic coating in the field of self-cleaning.

[0059] The following detailed description of the preparation method of the fluorine-free superhydrophobic cotton fabric provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] Accurately weigh 0.3 g of nano-SiO2 particles and place them in a beaker containing 30 mL of anhydrous ethanol. Disperse the mixture using an ultrasonic stirrer for 30 minutes. Add 5 mL (4.92 g) of OTS and react for 2 hours to obtain solution A.

[0062] Add 3g of silane coupling agent KH-560 to another beaker containing 30mL of deionized water, and use an ultrasonic stirrer to ultrasonically stir the mixture for 30 minutes to promote the complete hydrolysis of silane coupling agent KH-560 in water to obtain solution B.

[0063] Solution A, solution B, and 1 mL (0.89 g) of HDTMS were sequentially added to a 150 mL three-necked flask. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution to between 4 and 5. The three-necked flask was placed in a magnetically stirred, temperature-controlled oil bath at 70 °C, and the stirrer speed was adjusted to 1000 rpm. The mixture was stirred and reacted for 4 hours to finally obtain the hydrophobic OTS / HD-KH@SiO2 sol.

[0064] The cotton fabric was immersed in the prepared OTS / HD-KH@SiO2 sol, pre-dried for 10 minutes and then baked (120℃, 2 minutes) to obtain a fluorine-free superhydrophobic cotton fabric.

[0065] The resulting transparent superhydrophobic coating has a contact angle of 154.2° and exhibits good self-cleaning properties.

[0066] Figure 1 The following are test diagrams of the water contact angle of the fluorine-free superhydrophobic coating obtained in Example 1. (a) is a test diagram of the contact angle of the fluorine-free superhydrophobic cotton fabric. (a) shows that the contact angle of the obtained fluorine-free superhydrophobic coating is 154.2°. (b) shows the process of the water column being bounced off the treated cotton fabric. (c) shows the silver mirror phenomenon of the treated cotton fabric immersed in water.

[0067] Infrared spectra of raw cotton fabric and OTS / HD-KH@SiO2 coated hydrophobic fabric obtained by Fourier transform infrared spectroscopy are shown below. Figure 2 As shown. The hydrophobic cotton fabric and the original cotton fabric are at 3332cm. -1 The presence of a -OH stretching vibration peak at 2918 cm⁻¹, with the peak width and height of the original cotton fabric being wider than that of the treated cotton, indirectly proves that some hydroxyl groups on the surface of the cotton fabric have been replaced by hydrophobic materials, undergoing dehydration condensation to form covalent bonds, thus crosslinking onto the fabric. The treated cotton fabric exhibits a peak at 2918 cm⁻¹. -1 and 2851cm -1 The peaks at 1456 cm⁻¹ represent the stretching vibrations of the methyl and methylene groups of the long-chain alkyl group of OTS. -1 The peak at 814 cm⁻¹ represents the stretching vibration of the methylene group. -1 The presence of Si-O stretching vibration peaks at the surface indicates that the modified silica nanoparticles were successfully applied to the fabric surface. This demonstrates the successful preparation of the OTS / HD-KH@SiO2 coated hydrophobic fabric.

[0068] Figure 3 To obtain photographs of various common liquids (deionized water, water-soluble dye, cola, milk, coffee, and cooking oil) dropped onto the surfaces of raw cotton fabric and a fluorine-free superhydrophobic coating, from... Figure 3 It can be seen that the obtained fluorine-free superhydrophobic cotton fabric exhibits excellent anti-fouling performance against a variety of common types of liquids.

[0069] Reactive dyes and dust were used to simulate solid contaminants. Solid contaminant powder was sprinkled onto the fluorine-free superhydrophobic coating obtained in Example 1. Water was then dripped onto one end of the transparent superhydrophobic coating. (See photograph.) Figure 4 As shown, (a) represents the self-cleaning process for reactive dye stains, and (b) represents the self-cleaning process for dust stains. From Figure 4 It can be seen that the prepared fluorine-free superhydrophobic cotton fabric has excellent self-cleaning properties.

[0070] The fabric abrasion resistance test was conducted according to the modified method of AA TCC 8-2001. The treated fabric was subjected to abrasion treatment using a color fastness tester. The treated fabric was placed on a stainless steel ring, with the original cotton fabric used as a backing. One cycle constituted one abrasion test. Figure 6 (a) It can be seen that the contact angle of the treated cotton fabric decreases continuously with the increase of the number of friction cycles. The main reason is that with the increase of the number of friction cycles, the micro / nano rough structure of the cotton fabric surface is destroyed, and some low surface energy substances are worn away, resulting in a continuous decrease in the water contact angle of the cotton fabric. After 100 friction cycles, the contact angle of the treated cotton fabric is 131.9°, and it can still maintain a certain degree of hydrophobicity.

[0071] The soap wash fastness test was conducted according to Method 1 of AATCC Standard 61-2003. 0.37 wt% soap flakes and 10 steel balls were added to the soap wash fastness tester, and the fabric was soaped at 40°C for 45 minutes as one wash cycle (equivalent to 5 ordinary washes). After soap washing, the fabric was rinsed thoroughly with plenty of water to remove the soap solution, and then dried at 80°C. The results are as follows: Figure 6 As shown in (b), after washing for 120 minutes, the contact angle of the OTS / HD-KH@SiO2 cotton fabric decreased from 154.4° to 132.7°, but it still retained its hydrophobic properties. This is mainly because the surface material of the cotton fabric in the composite system is relatively stable. After 120 minutes of washing, the dense film tightly coats the nanoparticles, preventing them from falling off the fabric, and the degree of cross-linking is good.

[0072] Example 2

[0073] Accurately weigh 0.3 g of nano-SiO2 particles and place them in a beaker containing 30 mL of anhydrous ethanol. Disperse the mixture using an ultrasonic stirrer for 30 minutes, then add 4.92 g of HDTMS and react for 2 hours to obtain solution A.

[0074] Add 3g of silane coupling agent KH-560 to another beaker containing 30mL of deionized water, and use an ultrasonic stirrer to ultrasonically stir the mixture for 30 minutes to promote the complete hydrolysis of silane coupling agent KH-560 in water to obtain solution B.

[0075] Solution A, solution B, and 0.89 g of OTS were sequentially added to a 150 mL three-necked flask. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution to between 4 and 5. The three-necked flask was placed in a magnetically stirred, temperature-controlled oil bath at 70 °C, and the stirrer speed was adjusted to 1000 rpm. The mixture was stirred and reacted for 4 hours to finally obtain hydrophobic OTS / HD-KH@SiO2 sol.

[0076] The prepared OTS / HD-KH@SiO2 sol was sprayed onto the surface of cotton fabric, pre-dried for 10 min and then baked (120℃, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0077] The resulting transparent superhydrophobic coating has a contact angle of 157.2°.

[0078] Following the same testing procedure as in Example 1, the fluorine-free superhydrophobic cotton fabric obtained in this example exhibited excellent stain-resistant properties against various common types of liquids (deionized water, water-soluble dyes, cola, milk, coffee, and edible oil). Furthermore, the prepared fluorine-free superhydrophobic cotton fabric possesses excellent self-cleaning properties.

[0079] Following the same fabric abrasion resistance and soap washing fastness tests as in Example 1, the fluorine-free superhydrophobic coating obtained in this example has a certain durability effect. After 100 linear abrasions and 120 minutes of washing, the water contact angles were 143.5° and 142.6°, respectively, and it still has good hydrophobic properties.

[0080] Example 3

[0081] Accurately weigh 0.3g of nano-SiO2 particles and place them in a beaker containing 30mL of anhydrous ethanol. Disperse the mixture using an ultrasonic stirrer for 30 minutes, then add 4.92g of silane coupling agent KH-560 and react for 2 hours to obtain solution A.

[0082] Add 3g of OTS to another beaker containing 30mL of deionized water, and use an ultrasonic stirrer to ultrasonically stir the mixture for 30 minutes to promote the complete hydrolysis of OTS in water to obtain solution B.

[0083] Solution A, solution B, and 0.89 g of HDTMS were sequentially added to a 150 mL three-necked flask. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution to between 4 and 5. The three-necked flask was placed in a magnetically stirred, temperature-controlled oil bath at 70 °C, and the stirrer speed was adjusted to 1000 rpm. The mixture was stirred and reacted for 4 hours to finally obtain the hydrophobic OTS / HD-KH@SiO2 sol.

[0084] The prepared OTS / HD-KH@SiO2 sol was sprayed onto the surface of cotton fabric, pre-dried for 10 min and then baked (120℃, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0085] The resulting transparent superhydrophobic coating has a contact angle of 154.8°.

[0086] Following the same testing procedure as in Example 1, the fluorine-free superhydrophobic cotton fabric obtained in this example exhibited excellent stain-resistant properties against various common types of liquids (deionized water, water-soluble dyes, cola, milk, coffee, and edible oil). Furthermore, the prepared fluorine-free superhydrophobic cotton fabric possesses excellent self-cleaning properties.

[0087] According to the same fabric abrasion resistance and soap washing fastness tests as in Example 1, the fluorine-free superhydrophobic coating obtained in this example has a certain durability effect. After 100 linear abrasions and 120 minutes of washing, the water contact angles are 150.2° and 149.4°, respectively, and it still has excellent hydrophobic properties.

[0088] Comparative Example 1

[0089] Accurately weigh 0.3 g of nano-SiO2 particles and place them in a beaker containing 30 mL of anhydrous ethanol. Disperse the mixture using an ultrasonic stirrer for 30 minutes, add 2 mL (1.97 g) of OTS, and react for 2 hours to obtain solution A.

[0090] Add 3g of silane coupling agent KH-560 to another beaker containing 30mL of deionized water, and use an ultrasonic stirrer to ultrasonically stir the mixture for 30 minutes to promote the complete hydrolysis of silane coupling agent KH-560 in water to obtain solution B.

[0091] Solution A, solution B, and 1 mL (0.89 g) of HDTMS were sequentially added to a 150 mL three-necked flask. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution to between 4 and 5. The three-necked flask was placed in a magnetically stirred, temperature-controlled oil bath at 70 °C, and the stirrer speed was adjusted to 1000 rpm. The mixture was stirred and reacted for 4 hours to finally obtain the hydrophobic OTS / HD-KH@SiO2 sol.

[0092] The prepared OTS / HD-KH@SiO2 sol was sprayed onto the surface of cotton fabric, pre-dried for 10 min and then baked (120℃, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0093] The resulting transparent superhydrophobic coating has a contact angle of 148.1°.

[0094] The above are preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

[0095] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A fluorine-free superhydrophobic coating, characterized in that, The fluorine-free superhydrophobic coating is attached to cotton fabric, and the fluorine-free superhydrophobic coating includes a hydrophobic modified silica layer; the hydrophobic silica layer is prepared by modifying silica with a modifier; the modifier includes trichlorooctadecylsilane, KH-560 and hexadecyltrimethoxysilane; The method for preparing the fluorine-free superhydrophobic coating includes the following steps: S1. Mix silica, a first modifier, and an alcohol solvent to modify the mixture and obtain hydrophobic silica; the mass ratio of silica to the first modifier is 1:(10-20); the volume ratio of silica to alcohol solvent is 1 g:(100~150mL). S2. Disperse the second modifier in water to obtain a mixture; the concentration of the second modifier dispersed in water is 0.1-0.5 g / mL; S3. Mix the obtained hydrophobic silica, the mixture and the third modifier to obtain a fluorine-free superhydrophobic coating; The first modifier is KH-560, the second modifier is trichlorooctadecylsilane, and the third modifier is hexadecyltrimethoxysilane; The mass ratio of the first modifier, the second modifier, and the third modifier is (4-8):(3-5):

1.

2. A method for preparing a fluorine-free superhydrophobic nano-silica cotton fabric, characterized in that, The fluorine-free superhydrophobic coating of claim 1 is coated onto a cotton fabric, and then dried and cured to obtain a fluorine-free superhydrophobic cotton fabric.

3. The fluorine-free superhydrophobic cotton fabric prepared by the method of claim 2.

4. The application of the fluorine-free superhydrophobic coating of claim 1 or the fluorine-free superhydrophobic cotton fabric of claim 3 in the field of self-cleaning.

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