A method for preparing a superhydrophobic coating

Abstract

The application discloses a preparation method of a super-hydrophobic coating. First, a three-electrode electrochemical working system is used to prepare an inner layer solidified polyaniline coating by using 0.5 mol / L aniline, 0.1 mol / L phytic acid, 0.2 mol / L sulfuric acid and nickel acetate; then, an outer layer solidified polyaniline coating is prepared by using anhydrous ethanol, distilled water, dodecyl trimethoxysilane, hexadecyl trimethoxysilane, 3-aminopropyl triethoxysilane, epoxy resin E51 and hydrophobic silicon dioxide; finally, a novel polyaniline super-hydrophobic coating with excellent corrosion resistance, mechanical properties and heat resistance can be obtained by normal temperature solidification. By adjusting the adding proportion of the epoxy resin and the hydrophobic silicon dioxide, the surface roughness of the super-hydrophobic coating can be more accurately controlled, the precise control of the surface roughness of the super-hydrophobic coating is realized in the molecular scale, the super-hydrophobic coating has good corrosion resistance and adhesion, raw materials are easy to obtain and do not contain environment-unfriendly reagents, and the solidification condition is simple and no other reagents need to be added.

Description

Technical Field

[0001] This invention belongs to the field of conductive coating technology, and specifically relates to a method for preparing a superhydrophobic coating. Background Technology

[0002] Inspired by the superhydrophobic phenomenon exemplified by the "lotus effect," the technology for preparing superhydrophobic materials has developed rapidly over the past few decades. Due to the unique wettability of superhydrophobic surfaces, water droplets struggle to adhere to them. Therefore, superhydrophobic surfaces hold immense application potential in waterproofing, anti-fogging, anti-freezing, self-cleaning, anti-biocontamination, drug delivery, reducing fluid transport resistance, corrosion resistance, batteries, and oil-water separation. However, current research on superhydrophobic surface materials still has some shortcomings, such as complex preparation methods, high process requirements, difficulties in mass production, and low stability in use, attracting widespread attention from the scientific and industrial communities. Researchers have utilized various methods to develop superhydrophobic coatings, including chemical etching, laser etching, template etching, anodizing, self-assembly, phase separation, and sol-gel methods. Significant improvements have been made in preparation schemes and hydrophobic effects to obtain low-cost, simple-to-prepare, and large-scale durable superhydrophobic coatings.

[0003] Current technologies cannot achieve precise control of superhydrophobic surface roughness at the molecular scale, which hinders the further improvement of superhydrophobic theoretical models. Summary of the Invention

[0004] The purpose of this invention is to prepare a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical, and heat resistance properties. By adjusting the addition ratio of epoxy resin / hydrophobic silica, the surface roughness of the superhydrophobic coating can be more accurately controlled, thereby achieving precise control of the superhydrophobic surface roughness at the molecular scale.

[0005] A method for preparing a superhydrophobic coating includes the following steps: (1) Prepare phytic acid-doped aniline tempered film substrate and perform inner layer curing. An electrolyte containing 0.5 mol / L aniline, 0.1 mol / L phytic acid, and 0.2 mol / L sulfuric acid was prepared in a 25 mL beaker using a three-electrode electrochemical workstation system. Nickel acetate was added to the electrolyte. Cyclic voltammetry (CV) was used with a potential range of -0.2 V to 1.1 V, scanning at a rate of 20 mV / s for 20 to 30 cycles. After polymerization, the oligomers on the surface of the polyaniline were rinsed off with anhydrous ethanol, and then dried in a forced-air oven at 60 to 65 °C for 10 to 12 h to obtain an inner-layer cured polyaniline coating. (2) Prepare epoxy resin / hydrophobic silica film for outer layer curing Anhydrous ethanol, distilled water, dodecyltrimethoxysilane, hexadecyltrimethoxysilane and 3-aminopropyltriethoxysilane were added to a 100ml three-necked flask and heated and stirred at 60-70℃ to dissolve them completely. The reaction was carried out in an oil bath for 4-6 hours at a temperature of 60-70℃. After the reaction was completed, epoxy resin E51 was added and hydrophobic silica was added after 1-2 hours of reaction. The solution was then sprayed onto the inner layer cured polyaniline coating prepared in (1) to obtain the outer layer cured polyaniline coating. (3) Preparation of a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical and thermal properties The outer layer of polyaniline coating prepared in (2) is cured at room temperature for 12 hours to obtain a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical and thermal properties.

[0006] The specific formula and process of the method are as follows: Anhydrous ethanol Analytical Pure 69.2～76.7 distilled water Chemically pure 3.8～4.2 hexadecyltrimethoxysilane Analytical Pure 6.1～6.5 3-Aminopropyltriethoxysilane Analytical Pure 1.2～2.3 dodecyltrimethoxysilane Analytical Pure 2.0～3.3 Nickel acetate Analytical Pure 2.7～3.0 Epoxy Resin E51 Analytical Pure 1.7～2.3 Hydrophobic silica Chemically pure 4.8～9.6 The three-electrode electrochemical workstation system uses a platinum wire as the counter electrode, a calomel electrode as the reference electrode, and a pre-treated metal sheet as the working electrode. The working electrode is an SS304 stainless steel sheet that has been sanded.

[0007] The mass ratio of epoxy resin E51 to hydrophobic silica is 3:1 to 4:1. By adjusting the addition ratio of epoxy resin / hydrophobic silica, the surface roughness of the superhydrophobic coating can be more accurately controlled, thereby achieving precise control of the superhydrophobic surface roughness at the molecular scale.

[0008] Beneficial effects (1) In the method provided by the present invention, polyaniline can form a metal passivation layer, trigger the interlayer electric field interaction between metal and polyaniline, and construct a hydrophobic adsorption layer. The synthesized reactants have low toxicity, scratch resistance, and pitting corrosion resistance, and can also induce passivation behavior between the coating and the metal oxide layer, which can protect the metal from further corrosion. In addition, a novel polyaniline superhydrophobic coating is prepared by electrochemical CV method. By adjusting the ratio of epoxy resin / hydrophobic silica and modifying the silica nanoparticles hydrophobically, the interfacial interaction between the silica nanoparticles and epoxy resin is improved, and the surface roughness of the superhydrophobic coating can be controlled more accurately.

[0009] (2) In the method provided by the present invention, based on the chelating property of phytic acid with metal particles, phytic acid can chelate with divalent and higher valence metal ions (such as Cu2+, Zn2+, Fe2+, Fe3+, Al3+, Ca2+, Mg2+, etc.) to form stable complexes within a wide pH range. It can also form a dense chemical conversion film on the surface of metals such as steel, aluminum alloy, magnesium alloy, and copper by chelating with the surface atoms of the metal. This film can then slow down the diffusion rate of corrosive media such as oxygen, Cl-, and H+ to the surface of the metal substrate, thereby inhibiting metal corrosion. Moreover, since the phytic acid chemical conversion film contains abundant hydroxyl and phosphate groups, it can effectively chemically crosslink with the organic coating of the metal coating, improving the adhesion between the metal surface and the outer coating, thus forming a dense chemical conversion film. This allows the novel polyaniline superhydrophobic coating to have both good anti-corrosion performance and adhesion.

[0010] (3) In the method provided by the present invention, the raw materials are readily available and there are no environmentally unfriendly reagents. The curing conditions are simple and no other reagents need to be added. Detailed Implementation

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0012] (1) Prepare phytic acid-doped aniline tempered film substrate and perform inner layer curing. A three-electrode electrochemical workstation was used, with a platinum wire as the counter electrode, a calomel electrode as the reference electrode, and a sandpaper-polished SS304 stainless steel sheet as the working electrode. In a 25 mL beaker, the electrolyte consisted of 0.5 mol / L aniline, 0.1 mol / L phytic acid, and 0.2 mol / L sulfuric acid. 0.85 g of nickel acetate was added to the 25 mL electrolyte beaker. Cyclic voltammetry (CV) was performed within the range of -0.2 V to 1.1 V at a rate of 20 mV / s for 20 cycles. After polymerization, the oligomers on the polyaniline surface were rinsed off with anhydrous ethanol, and the polyaniline was dried in a forced-air oven at 60 °C for 12 hours to obtain the inner cured polyaniline coating.

[0013] (2) Prepare epoxy resin / hydrophobic silica film for outer layer curing 25 ml of ethanol, 1 ml of distilled water, 0.65 g of dodecyltrimethoxysilane, 1.95 g of hexadecyltrimethoxysilane, and 0.45 g of 3-aminopropyltriethoxysilane were added to a 100 ml three-necked flask. The mixture was heated and stirred at 60 °C until fully dissolved. The reaction was then carried out in an oil bath for 4 h at 60 °C. After the reaction was completed, 0.65 g of epoxy resin E51 was added. After 1 h, 1.40 g of hydrophobic silica was added. The silica was then sprayed onto the inner layer of cured polyaniline coating prepared in (1) to obtain the outer layer of cured polyaniline coating.

[0014] (3) Preparation of a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical and thermal properties The outer layer of polyaniline coating prepared in (2) is cured at room temperature for 12 hours to obtain a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical and thermal properties.

[0015] The test performance is as follows: 1 Adhesion / Grade GB / T 1720-1979 Level 1 2 Salt spray resistance / h GB / T 1771-2007 1200h 3 Heat resistance GB / T 1735-2009 300℃ / 48h 4 flexibility GB / T 1731-1993 1mm 5 Contact angle θ (CA) GB / T 26490-2011 157.4° 6 Roll angle θ (SA) GB / T 26490-2011 8.2° Example 2

[0016] (1) Prepare phytic acid-doped aniline tempered film substrate and perform inner layer curing. A three-electrode electrochemical workstation was used, with a platinum wire as the counter electrode, a calomel electrode as the reference electrode, and a sandpaper-polished SS304 stainless steel sheet as the working electrode. In a 25 mL beaker, the electrolyte consisted of 0.5 mol / L aniline, 0.1 mol / L phytic acid, and 0.2 mol / L sulfuric acid. 0.98 g of nickel acetate was added to the 25 mL electrolyte beaker. Cyclic voltammetry (CV) was performed within the range of -0.2 V to 1.1 V at a rate of 20 mV / s for 20 cycles. After polymerization, the oligomers on the polyaniline surface were rinsed off with anhydrous ethanol, and the polyaniline was dried in a forced-air oven at 60 °C for 12 hours to obtain the inner cured polyaniline coating.

[0017] (2) Prepare epoxy resin / hydrophobic silica film for outer layer curing In a 100ml three-necked flask, 25ml of ethanol, 1ml of distilled water, 0.88g of dodecyltrimethoxysilane, 2.15g of hexadecyltrimethoxysilane, and 0.55g of 3-aminopropyltriethoxysilane were added respectively. The mixture was heated and stirred at 60℃ until fully dissolved. The reaction was then carried out in an oil bath for 4 hours at 60℃. After the reaction was completed, 0.85g of epoxy resin E51 was added. After 1 hour, 2.25g of hydrophobic silica was added. The silica was then sprayed onto the inner layer cured polyaniline coating prepared in (1) to obtain the outer layer cured polyaniline coating.

[0018] (3) Preparation of a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical and thermal properties The outer layer of polyaniline coating prepared in (2) is cured at room temperature for 12 hours to obtain a novel polyaniline superhydrophobic coating with excellent anti-corrosion, mechanical and thermal properties.

[0019] The test performance is as follows: 1 Adhesion / Grade GB / T 1771-2007 Level 1 2 Salt spray resistance / h GB / T 1735-2009 1200h 3 Heat resistance GB / T 1731-1993 300℃ / 48h 4 flexibility GB / T 26490-2011 1mm 5 Contact angle θ (CA) GB / T 26490-2011 162.3° 6 Roll angle θ (SA) GB / T 1720-1979 6.7° This disclosure has been described with reference to the foregoing embodiments; however, these embodiments are merely examples for implementing this disclosure. It must be noted that the disclosed embodiments do not limit the scope of this disclosure. On the contrary, any changes and modifications made without departing from the spirit and scope of this disclosure are within the scope of patent protection of this disclosure.

Claims

1. A method for preparing a superhydrophobic coating, characterized in that: Includes the following steps: (1) Preparation of inner layer cured polyaniline coating: A 25 mL electrolyte was prepared using a three-electrode electrochemical workstation system. The electrolyte contained 0.5 mol / L aniline, 0.1 mol / L phytic acid, and 0.2 mol / L sulfuric acid, with 0.8 g to 1.0 g of nickel acetate added. Cyclic voltammetry was used with a potential range of -0.2 V to 1.1 V, scanning at a rate of 20 mV / s for 20 to 30 cycles. After polymerization, the oligomers on the surface of the polyaniline were rinsed off with anhydrous ethanol, and then dried in a forced-air oven at 60 to 65 °C for 10 to 12 hours to obtain an inner-layer cured polyaniline coating. (2) Preparation of outer layer cured polyaniline coating Anhydrous ethanol, distilled water, dodecyltrimethoxysilane, hexadecyltrimethoxysilane and 3-aminopropyltriethoxysilane were added to a 100ml three-necked flask. The mixture was heated and stirred at 60-70℃ to dissolve it completely. The mixture was then heated in an oil bath for 4-6 hours at a temperature of 60-70℃. After the reaction was completed, epoxy resin E51 was added. After reacting for 1-2 hours, hydrophobic silica was added. The mixture was then sprayed onto the inner layer cured polyaniline coating prepared in (1) to obtain the outer layer cured polyaniline coating. (3) Preparation of polyaniline superhydrophobic coating After curing the outer layer of polyaniline coating prepared in (2), a superhydrophobic coating is obtained.

2. The method for preparing the superhydrophobic coating according to claim 1, characterized in that: The working system of the three-electrode electrochemical workstation uses a platinum wire as the counter electrode, a calomel electrode as the reference electrode, and a pretreated metal sheet as the working electrode.

3. The method for preparing the superhydrophobic coating according to claim 2, characterized in that: The working electrode is an SS304 stainless steel sheet that has been sanded.

4. The method for preparing the superhydrophobic coating according to claim 1, characterized in that: The distilled water, hexadecyltrimethoxysilane, 3-aminopropyltriethoxysilane, dodecyltrimethoxysilane, nickel acetate, and epoxy resin E51 are chemically pure; the anhydrous ethanol and hydrophobic silica are analytically pure.

5. The method for preparing the superhydrophobic coating according to claim 1, characterized in that: The curing conditions for step (3) are room temperature curing for 12 hours.