Substrate pre-implanted bimolecule co-anchored composite super-hydrophobic coating and preparation method thereof

Abstract

The invention provides a substrate pre-implanted bimolecule co-anchored composite super-hydrophobic coating and a preparation method thereof, and the preparation method comprises the following steps: (1) cleaning and drying the surface of an aluminum alloy substrate, and then oxidizing to obtain an AAO substrate; (2) taking the AAO substrate as a cathode, taking a Pt electrode as an anode, and placing the AAO substrate and the Pt electrode in electrolyte for electro-deposition to obtain a sample; and (3) spin-coating a modification solution on the surface of the sample, and then heating and drying to obtain the composite super-hydrophobic coating, the electrolyte in the step (2) contains an alloy solution and a bimolecular solution. According to the substrate pre-implanted bimolecule co-anchored composite super-hydrophobic coating, a pre-implanted bimolecule co-anchoring strategy is adopted, and the physical and mechanical properties and chemical durability of the coating are remarkably improved through strong chemical bonding of molecules and the substrate and strong chemical bonding of the molecules and the modifier.

Description

Technical Field

[0001] The present invention belongs to the field of materials, and particularly relates to a composite superhydrophobic coating with dual-molecule co-anchoring pre-implanted on a substrate and a preparation method thereof. Background Art

[0002] At present, existing coating technologies include chemical etching method, chemical vapor deposition method, traditional electrochemical deposition method, sol-gel method, etc. Among them, the chemical etching method immerses the material in an etching solution, and through a series of chemical reactions, an etched structure and surface roughness are obtained to achieve superhydrophobic performance. However, the stability and uniformity of the structure and performance obtained by the etching method are poor; chemical vapor deposition deposits a superhydrophobic thin film on the material surface through a series of chemical reactions, which is relatively precise, but the equipment is complex and the cost is high; traditional electrochemical deposition forms a superhydrophobic coating by directly depositing substances on the substrate surface through an electrochemical reaction. Although the coating prepared by this method has good mechanical properties, the roughness and adhesion of the coating need to be improved; the sol-gel method forms a gel on the substrate surface through a sol, and after drying and curing, a superhydrophobic coating is formed. The coating prepared by this method is relatively uniform, but the mechanical properties are poor. At the same time, the coatings prepared by the above methods are prone to failure in a chemical corrosion environment, and there are problems such as insufficient chemical durability and corrosion resistance. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and proposes a composite superhydrophobic coating with dual-molecule co-anchoring pre-implanted on a substrate and a preparation method thereof.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] The present invention provides a preparation method of a composite superhydrophobic coating with dual-molecule co-anchoring pre-implanted on a substrate, comprising the following steps:

[0006] (1) Clean and dry the surface of an aluminum alloy substrate, and then perform oxidation to obtain an AAO substrate;

[0007] (2) Use the AAO substrate as the cathode and a Pt electrode as the anode, and place them in an electrolyte for electrodeposition to obtain a sample;

[0008] (3) Spin-coat a modification solution on the surface of the sample, and then obtain the composite superhydrophobic coating after heating and drying;

[0009] The electrolyte in the step (2) contains an alloy solution and a dual-molecule solution with a molar ratio of 1:2-3.

[0010] Further, the alloy solution is a solution containing a nickel compound and a zinc compound with a molar ratio of 1:0.1-0.5.

[0011] Preferably, the alloy solution contains nickel chloride hexahydrate and zinc chloride in a molar ratio of 1:0.15.

[0012] On an anodic aluminum oxide (AAO) substrate, an alloy layer with excellent mechanical properties is prepared by electrodeposition. The alloy layer is a nickel (Ni)-zinc (Zn) alloy. The alloy layer achieves uniform deposition through the optimization of electrodeposition process parameters. The alloy layer significantly improves the physical and mechanical properties of the coating, including wear resistance and adhesion to the substrate. At the same time, the high hardness of the nickel-zinc alloy enhances the impact resistance and scratch resistance, enabling it to meet more functional requirements. In addition, the alloy layer also has good corrosion resistance and thermal stability, making its application prospects broad in fields such as aerospace and ship transportation. Glycine and ethylenediamine dihydrochloride are added to the electrolyte and thus implanted onto the AAO substrate. The alloy layer has good corrosion resistance and wear resistance and can significantly improve the physical and mechanical properties of the coating.

[0013] Furthermore, the bimolecular solution is glycine and ethylenediamine dihydrochloride in a molar ratio of 1-3:1-3.

[0014] Preferably, the bimolecular solution is glycine and ethylenediamine dihydrochloride in a molar ratio of 0.7:2.

[0015] One end of the amino group of glycine can form hydrogen bonds or covalent bonds (such as Al-N bonds) with the hydroxyl groups (-OH) on the surface of the aluminum alloy substrate or the oxygen atoms on the surface of the metal oxide, thereby enhancing the adhesion between the coating and the substrate and optimizing the surface structure of anodic aluminum oxide. The introduction of the N atom can attack and open the Al-O bond to form an Al-N bond, removing the dendritic structure on the surface layer of the AAO and making it exhibit an excellent porous structure, which is easy to graft silane. The other end of the carboxyl group of glycine can undergo dehydration condensation with the silanol generated after the hydrolysis of silane to form a Si-O-C bond, thereby achieving connection.

[0016] Ethylenediamine dihydrochloride has two amino groups. One end of the amino group can play the same role as the amino group in glycine, and the other amino group can form a hydrogen bond with the silanol and further dehydrate to form a covalent bond (Si-N), optimizing the interfacial bonding strength of the coating.

[0017] Pre-implanting glycine and ethylenediamine dihydrochloride enhances the chemical bonding between the coating and the AAO substrate through the amino group of glycine and the amino group of ethylenediamine dihydrochloride, and also optimizes the surface structure of the AAO substrate. Through the carboxyl group of glycine and the amino group of ethylenediamine dihydrochloride, it is more conducive to the subsequent grafting of surface modifiers (such as silane), significantly improving the adhesion, chemical durability, and hydrophobic properties of the coating, providing a basis for the preparation of high-performance superhydrophobic coatings.

[0018] Further, the oxidation step in the step (1) is specifically as follows: Place the cleaned aluminum alloy substrate in an oxalic acid solution and perform anodic oxidation at a current density of 100 mA·cm -2 for 15 minutes; the concentration of the oxalic acid solution is 0.1 - 0.5 mol / L.

[0019] Further, the current density of the electrodeposition step in the step (2) is 20 - 60 mA·cm -2 , the time is 5 - 60 minutes, and the temperature is 50 - 80 °C.

[0020] Further, the modification solution in the step (3) is methoxysilane; preferably, the modification solution in the step (3) is any one of cetyltrimethoxysilane, octadecyltrimethoxysilane, and perfluorodecyltrimethoxysilane.

[0021] Spin-coat the modification solution on the surface of the alloy layer and perform high-temperature drying and dehydration to form a stable superhydrophobic coating. The silane provides hydrophobic groups with low surface energy, and at the same time forms stable chemical bonds with the carboxyl group in glycine and the amino group in ethylenediamine dihydrochloride, further enhancing the chemical stability and durability of the coating. By regulating the spin-coating speed and drying temperature of the silane, the optimal parameters are found.

[0022] Further, the rotation speed of the spin-coating step in the step (3) is 2000 - 3000 rpm, and the time is 30 - 60 s; the temperature of the heating step in the step (3) is 100 - 150 °C, and the time is 30 - 60 minutes.

[0023] The present invention also provides a substrate pre-implanted with a composite superhydrophobic coating with bimolecular co-anchoring prepared by using the above preparation method.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to the present invention adopts a pre-implanted bimolecular co-anchoring strategy. Through strong chemical bonding between molecules and the substrate, and strong chemical bonding between molecules and the modifier, the physical and mechanical properties and chemical durability of the coating are significantly improved; at the same time, the AAO substrate formed by anodic oxidation and the electrodeposited Ni-Zn alloy layer provide an excellent micro-nano structure basis for the superhydrophobic coating, further enhancing the hydrophobic performance of the coating; the surface modifier endows the coating with hydrophobic characteristics of low surface energy, making it have excellent stability and durability in complex environments. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate described in the embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the molecular anchoring path according to the embodiment of the present invention. Detailed implementation manners

[0028] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0029] The present invention will be described in detail below with reference to the embodiments.

[0030] Embodiment 1

[0031] A preparation method of a composite superhydrophobic coating with dual-molecule co-anchoring pre-implanted on a substrate, comprising the following steps:

[0032] (1) The aluminum alloy substrate is ultrasonically cleaned with detergent, deionized water and ethanol for 15 minutes. After removing the surface oil stains and impurities, it is dried with an air pressure gun. The cleaned aluminum alloy substrate is used as the anode and placed in a 0.3 mol / L oxalic acid solution. Anodic oxidation is carried out at a current density of 100 mA·cm -2 for 15 minutes to form a dendritic anodic aluminum oxide (AAO) layer, and then it is rinsed with deionized water and dried for standby;

[0033] (2) The anodized AAO substrate is used as the cathode and placed in an electrolyte containing 1 mol / L nickel chloride hexahydrate, 0.15 mol / L zinc chloride and 0.1 mol / L sodium dodecyl sulfate. Electrochemical deposition is carried out at a current density of 40 mA·cm-2. At the same time, 0.7 mol / L glycine and 2 mol / L ethylenediamine hydrochloride are added to the electrolyte to adjust the solution acidity and optimize the co-deposition kinetics. The deposition time is 5 - 10 minutes, and the electro-deposition temperature is 70 °C. At this time, the structure is a uniform porous structure and the alloy adheres to the pore walls and pores. After the deposition is completed, the sample is rinsed with deionized water and dried;

[0034] (3) The electro-deposited sample is spin-coated with cetyltrimethoxysilane using a 50% ethanol solution by mass fraction at a rotation speed of 2000 rpm for 35 seconds, and then dried on a hot plate at 120 °C for 50 minutes to form a composite superhydrophobic coating, and the structure is as Figure 1 shown.

[0035] Comparative Example 1

[0036] The difference from Embodiment 1 is only that: the dual-molecule solution is glycine.

[0037] Comparative Example 2

[0038] The difference from Example 1 is only that: the bimolecular solution is ethylenediamine hydrochloride.

[0039] Comparative Example 3

[0040] The difference from Example 1 is only that: the bimolecular solution is lysine and ethylenediamine hydrochloride with a ratio of 0.7:2.

[0041] Comparative Example 4

[0042] The difference from Example 1 is only that: the alloy solution contains cobalt chloride hexahydrate and zinc chloride with a molar ratio of 1:0.15.

[0043] Comparative Example 5

[0044] The difference from Example 1 is only that: the alloy solution contains nickel chloride hexahydrate and iron chloride with a molar ratio of 1:0.15.

[0045] Comparative Example 6

[0046] The difference from Example 1 is only that: the modification solution is octyltrimethoxysilane.

[0047] Contact angle and sandpaper friction tests were carried out on the coatings obtained in Example 1 and each Comparative Example 1. The results are shown in Table 1-2.

[0048] Table 1 Contact angle test results

[0049] Project Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Contact Angle (°) 165.379 156.660 153.097 155.553 159.744 146.919 129.914

[0050] Table 2 Abrasion resistance test results

[0051]

[0052] In Comparative Example 1, when the bimolecular solution is only glycine, due to its weak complexing ability with Ni 2+ / Zn 2+ , the nickel-zinc alloy with a large difference in electrode potential cannot achieve co-deposition. This non-synergistic deposition process makes the alloy layer structure poor, resulting in insufficient hydrophobicity and poor abrasion resistance. In Comparative Example 2, when the electrolyte only contains ethylenediamine hydrochloride, the lack of glycine as a pH regulator causes a significant increase in the solution pH, resulting in ineffective deposition of Ni 2+ . The coating lacks nickel strengthening phase, has insufficient surface roughness and weak bonding force, so its hydrophobicity and abrasion resistance are poor. In Comparative Example 3, if glycine is replaced by lysine, since lysine is a basic amino acid, too high pH may cause local metal hydroxide precipitation, destroying the pore continuity. At the same time, the phenomenon of ineffective deposition of Ni 2+ will also occur as described above. In Comparative Example 4, if nickel chloride hexahydrate is replaced by cobalt chloride hexahydrate, Co 2+Excessive complexation with glycine results in too slow release of metal ions during the deposition process and too little alloy distribution, leading to poorer hydrophobicity and wear resistance of the superhydrophobic coating compared to Example 1. In Comparative Example 5, if zinc chloride is changed to iron chloride, the hydrogen evolution overpotential of iron deposition is lower, exacerbating the hydrogen evolution phenomenon, resulting in hydrogen embrittlement in the alloy layer or an increase in bubbles during the deposition process, uneven deposition, a decrease in the hydrophobic angle, and poorer wear resistance. In Comparative Example 6, insufficient chain length: If hexadecyltrimethoxysilane is replaced with octyltrimethoxysilane, since the carbon chain of octyl (C8) is shorter, it cannot effectively reduce the surface energy, resulting in weakened hydrophobicity. At the same time, a dense silane network cannot be formed, resulting in the inability to resist high-intensity wear and poorer wear resistance.

[0053] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a composite superhydrophobic coating with pre-implanted and co-anchored bimolecules on a substrate, characterized in that: It includes the following steps: (1) Clean and dry the surface of the aluminum alloy substrate, and then perform oxidation to obtain an AAO substrate; (2) Use the obtained AAO substrate as the cathode and the Pt electrode as the anode, and place them in an electrolyte for electrodeposition to obtain a sample; (3) Spin-coat a modification solution on the surface of the sample, and then obtain the composite superhydrophobic coating after heating and drying; The electrolyte in step (2) contains an alloy solution and a bimolecular solution with a molar ratio of 1:2 - 3.

2. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 1, wherein: The alloy solution is a solution containing a nickel compound and a zinc compound with a molar ratio of 1:0.1 - 0.

5.

3. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 2, characterized in that: The alloy solution contains nickel chloride hexahydrate and zinc chloride with a molar ratio of 1:0.

15.

4. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 1, characterized in that: The bimolecular solution is glycine and ethylenediamine hydrochloride with a molar ratio of 1 - 3:1 - 3.

5. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 4, wherein: The bimolecular solution is glycine and ethylenediamine hydrochloride with a molar ratio of 0.7:

2.

6. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 1, characterized in that: The oxidation step in the said step (1) is specifically as follows: placing the cleaned aluminum alloy substrate in an oxalic acid solution, and performing anodic oxidation for 15 minutes at a current density of 100 mA·cm -2 ; the concentration of the said oxalic acid solution is 0.1 - 0.5 mol / L.

7. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 1, characterized in that: The current density in the electro-deposition step of step (2) is 20-60 mA·cm -2 , the time is 5-60 minutes, and the temperature is 50-80 °C.

8. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 1, characterized in that: The modification solution in step (3) is methoxysilane; preferably, the modification solution in step (3) is any one of cetyltrimethoxysilane, octadecyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, or perfluorodecyltrimethoxysilane.

9. The preparation method of the composite superhydrophobic coating with bimolecular co-anchoring pre-implanted on the substrate according to claim 1, characterized in that: The rotation speed of the spin-coating step in step (3) is 2000 - 3000 rpm, and the time is 30 - 60 s; the temperature of the heating step in step (3) is 100 - 150 °C, and the time is 30 - 60 minutes.

10. A substrate pre-implanted with a composite superhydrophobic coating with bimolecular co-anchoring prepared by the preparation method described in any one of claims 1 - 9.

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