A ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating and its preparation method

Abstract

The present invention discloses a preparation method of a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating, comprising the following steps: S1. Preparation of ZIF-8@PDA particles: Synthesize ZIF-8@PDA particles modified by polydopamine in one step in water; S2. Preparation of the ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating: Compound and superhydrophobically modify ZIF-8@PDA and carbon materials in a certain proportion, add an adhesive, spray it on the surface of a substrate, and obtain the ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating after curing. The ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating material prepared by the present invention exhibits excellent superhydrophobicity, mechanical stability and corrosion resistance. At the same time, the ZIF-8-based photothermal superhydrophobic anti-corrosion coating exhibits excellent passive delayed icing and active photothermal de-icing capabilities on the surface of aluminum alloy. It provides a brand-new strategy for winter de-icing of industrial facilities and equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of superhydrophobic coatings, and particularly relates to a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating and a preparation method thereof. Background Art

[0002] Offshore engineering facilities and equipment not only face corrosion problems brought by harsh marine environments, but also face surface icing problems in winter. The synergistic effect of corrosion and surface icing is particularly obvious for offshore engineering facilities and equipment. The water generated after ice melting will accelerate the occurrence of corrosion, and the rough corrosion products generated by corrosion provide more attachment points for the formation of ice crystals, further accelerating the icing process. This vicious cycle will significantly shorten the service life of facilities and equipment, increase maintenance costs and potential safety hazards.

[0003] In recent years, superhydrophobic coatings with special solid-liquid contact states (contact angle with water greater than 150° and rolling angle less than 10°) have attracted much attention in the scientific and industrial communities. The non-wetting and liquid-repellent properties of superhydrophobic coating surfaces exhibit great advantages in the fields of self-cleaning, anti-corrosion, anti-fouling, anti-icing, etc.

[0004] Although superhydrophobic coatings have great advantages in the fields of anti-corrosion and anti-icing on metal surfaces, superhydrophobic coatings can only delay icing and cannot actively remove ice. As the ice layer accumulates, once the superhydrophobic coating is completely covered by the ice layer, the anti-icing effect will not be achieved. This has greatly hindered the further development of superhydrophobic coatings in the anti-icing field. Existing de-icing technologies such as electrothermal de-icing, mechanical de-icing, and chemical de-icing not only have the problem of low efficiency, but also have a corrosive effect on metals, etc. Therefore, it is of great significance to develop a superhydrophobic anti-corrosion and anti-icing coating with an active de-icing function. Summary of the Invention

[0005] In view of this, the present invention provides a photothermal superhydrophobic anti-corrosion and anti-icing coating and a preparation method thereof. The main purpose is to provide a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating with passive delayed anti-icing and active photothermal de-icing functions.

[0006] The present invention provides a preparation method for a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating, including the following steps:

[0007] S1. Preparation of ZIF-8@PDA particles: Dissolve zinc salt and dopamine hydrochloride in deionized water to form solution A, dissolve 2-methylimidazole in deionized water to form solution B, mix solution A and solution B, stir at room temperature for a certain time to obtain a black turbid solution, centrifuge and wash, and freeze-dry to obtain ZIF-8 particles modified with polydopamine, ZIF-8@PDA;

[0008] S2. Preparation of ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating: A certain proportion of ZIF-8@PDA and carbon materials are dispersed in ethanol by stirring. After reacting with a modifier in an alkaline environment for a certain time, centrifugation is carried out, and then an organic solvent and a binder are added again. After stirring evenly, a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating material is obtained. The coating material is sprayed onto the surface of the substrate by spraying, and after curing, a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating is obtained.

[0009] The air layer captured by the micro-nano structure of the superhydrophobic coating can effectively reduce the solid-liquid contact area, which can not only block the direct contact between corrosive media and the material surface, but also delay the formation and attachment of ice crystals.

[0010] Further, the zinc salt in step S1 is one of zinc nitrate, zinc acetate and zinc gluconate.

[0011] Further, the mass concentration of hydrochloric acid dopamine in solution A in step S1 is 0.1 g / mL, and the mass concentration of zinc salt in solution A is 0.02 g / mL.

[0012] Further, the molar ratio of the zinc salt to 2-methylimidazole in step S1 is 1:5 - 10.

[0013] Further, the stirring time at room temperature in step S1 is 12 - 48 h, and the preferred time is 24 h.

[0014] Further, the mass ratio of ZIF-8@PDA to carbon materials in step S2 is 1:0.25 - 1.

[0015] Further, the carbon material is one or several of carbon black, carbon nanotubes and graphene.

[0016] Further, every 6 g of the mixture of ZIF-8@PDA and carbon materials is dispersed in 250 - 350 mL of ethanol.

[0017] Further, the alkaline environment in step S2 is to add ammonia solution to ethanol.

[0018] Further, the modifier in step S2 is tetraethyl orthosilicate and cetyltrimethoxysilane.

[0019] Further, the volume ratio of ethanol:ammonia solution:tetraethyl orthosilicate:cetyltrimethoxysilane in step S2 is 50:0.6:0.6:0.6.

[0020] Further, the organic solvent in step S2 is one of butyl acetate, ethanol and ethyl acetate.

[0021] Further, the binder described in step S2 is one or more of triphenyl phosphate, polysilazane, epoxy resin, polydimethylsiloxane, and thermoplastic polyurethane.

[0022] Further, the carbon material in step S1 is preferably carbon black, the organic solvent in step S2 is preferably butyl acetate, and the binder is preferably polysilazane and triphenyl phosphate. Carbon black is cheaper and more widely sourced than other carbon materials. As an emerging binder, polysilazane can cure itself without a curing agent and harsh curing conditions compared to traditional binders such as epoxy resin and polydimethylsiloxane. Triphenyl phosphate and polysilazane act synergistically to extend the diffusion of the corrosive medium and significantly improve the antioxidant performance of the carbon material, enhancing the anti-corrosion performance of the coating.

[0023] The present invention uses micron-scale ZIF-8@PDA and nano-scale carbon materials as photothermal superhydrophobic particles and a binder to prepare a ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating. First, the low surface energy substances and the air layer captured by the surface micro-nano structure of the coating can physically block the corrosive medium, enabling the coating to have certain anti-corrosion performance and also achieving the purpose of delaying icing. At the same time, the surface micro-nano structure of the coating causes sunlight to be reflected and absorbed multiple times on the coating surface, similar to a "trap" for capturing sunlight, increasing the sunlight absorption rate of the coating, and thus endowing the coating with certain photothermal performance to achieve the purpose of active photothermal de-icing. The ZIF-8-based photothermal superhydrophobic anti-corrosion and anti-icing coating can meet the requirements of metal anti-corrosion and anti-icing fields such as marine ships, coastal infrastructure, petroleum, chemical industry, electric power, and automobiles. Description of the Drawings

[0024] Figure 1 Shows the effects of droplets with different properties on the surface of Example 1;

[0025] Figure 2 Is the infrared thermal imaging of the temperature rise of aluminum alloy, Comparative Example 1, and Example 1 within 10 minutes under one sunlight intensity;

[0026] Figure 3 Is the process of aluminum alloy, Comparative Example 1, and Example 1 delaying icing at -15°C;

[0027] Figure 4 Is the photothermal ice melting process of aluminum alloy, Comparative Example 1, and Example 1 under one sunlight intensity. Detailed Embodiments

[0028] The preparation, performance, etc. of the ZIF-8-based photothermal superhydrophobic anti-corrosion coating of the present invention are further described below through specific examples.

[0029] Example 1

[0030] S1. Preparation of ZIF-8@PDA particles: Dissolve 12.25 g of zinc gluconate and 0.10 g of dopamine hydrochloride in 300 mL of deionized water to form solution A. Dissolve 16.00 g of 2-methylimidazole in 200 mL of deionized water to form solution B. Mix solution A and solution B and stir at room temperature for 24 h to obtain a black turbid solution. Centrifuge and wash, and then freeze-dry to obtain ZIF-8@PDA particles.

[0031] S2. Preparation of ZIF-8-based photothermal superhydrophobic anti-corrosion coating: Disperse 0.30 g of ZIF-8@PDA and 0.30 g of carbon black in 25 mL of ethanol. Sequentially add 0.3 mL of ammonia water, 0.3 mL of tetraethyl orthosilicate, and 0.3 mL of cetyltrimethoxysilane. After reacting for 4 h, centrifuge, and then re-add 10 mL of butyl acetate, 1.20 g of polysilazane, and 0.1 g of triisopropylphenyl phosphate. Stir evenly to obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating material. Spray the coating material onto the surface of aluminum alloy by spraying method, and after curing, obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating.

[0032] Example 2

[0033] Preparation of ZIF-8@PDA particles: Dissolve 12.25 g of zinc gluconate and 0.10 g of dopamine hydrochloride in 300 mL of deionized water to form solution A. Dissolve 8.00 g of 2-methylimidazole in 200 mL of deionized water to form solution B. Mix solution A and solution B and stir at room temperature for 36 h to obtain a black turbid solution. Centrifuge and wash, and then freeze-dry to obtain ZIF-8@PDA particles.

[0034] S2. Preparation of ZIF-8-based photothermal superhydrophobic anti-corrosion coating: Disperse 0.48 g of ZIF-8@PDA and 0.12 g of carbon nanotubes in 25 mL of ethanol. Sequentially add 0.3 mL of ammonia water, 0.3 mL of tetraethyl orthosilicate, and 0.3 mL of cetyltrimethoxysilane. After reacting for 6 h, centrifuge, and then re-add 10 mL of ethanol and 0.60 g of epoxy resin (E-44 type epoxy resin and polyamide 650 curing agent, the mass ratio of epoxy resin to curing agent is 1:1). Stir evenly to obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating material. Spray the coating material onto the surface of glass by spraying method, and after curing, obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating.

[0035] Example 3

[0036] Preparation of ZIF-8@PDA particles: Dissolve 7.80 g of zinc nitrate and 0.10 g of dopamine hydrochloride in 300 mL of deionized water to form solution A. Dissolve 16.00 g of 2-methylimidazole in 200 mL of deionized water to form solution B. Mix solution A and solution B and stir at room temperature for 48 h to obtain a black turbid solution. Centrifuge and wash, and then freeze-dry to obtain ZIF-8@PDA particles.

[0037] Preparation of S2, ZIF-8-based photothermal superhydrophobic anti-corrosion coating: Disperse 0.40 g of ZIF-8@PDA and 0.20 g of graphene in 25 mL of ethanol. Sequentially add 0.3 mL of ammonia water, 0.3 mL of tetraethyl orthosilicate, and 0.3 mL of cetyltrimethoxysilane. After reacting for 2 h, centrifuge, and then re-add 15 mL of ethyl acetate and 1.10 g of polydimethylsiloxane (Sylgard 184 type A polydimethylsiloxane and Sylgard 184 type B curing agent, the mass ratio of polydimethylsiloxane to the curing agent is 10:1). Stir evenly to obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating. Spray the coating onto the surface of a wooden board by spraying method, and after curing, obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating.

[0038] Example 4

[0039] Preparation of ZIF-8@PDA particles: Dissolve 5.91 g of zinc acetate and 0.10 g of dopamine hydrochloride in 300 mL of deionized water to form solution A. Dissolve 16.00 g of 2-methylimidazole in 200 mL of deionized water to form solution B. Mix solution A and solution B and stir at room temperature for 12 h to obtain a black turbid solution. Centrifuge and wash, and then freeze-dry to obtain ZIF-8@PDA particles.

[0040] Preparation of S2, ZIF-8-based photothermal superhydrophobic anti-corrosion coating: Disperse 0.36 g of ZIF-8@PDA and 0.24 g of carbon black in 25 mL of ethanol. Sequentially add 0.3 mL of ammonia water, 0.3 mL of tetraethyl orthosilicate, and 0.3 mL of cetyltrimethoxysilane. After reacting for 4 h, centrifuge, and then re-add 50 mL of ethyl acetate and 0.5 g of thermoplastic polyurethane. Stir evenly to obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating. Spray the coating onto the surface of a metal mesh by spraying method, and after curing, obtain a ZIF-8-based photothermal superhydrophobic anti-corrosion coating.

[0041] Comparative Example 1

[0042] The difference from Example 1 is that carbon black was not added.

[0043] Comparative Example 2

[0044] The difference from Example 1 is that cetyltrimethoxysilane was not added in step S2.

[0045] Comparative Example 3

[0046] The difference from Example 1 is that triisopropylphenyl phosphate was not added in step S2.

[0047] Comparative Example 4

[0048] The difference from Example 1 is that polysilazane was not added in step S2.

[0049] Performance test:

[0050] (1) Salt spray corrosion test

[0051] The results of the salt spray corrosion test carried out based on the GB / T 10125 standard are shown in Table 1.

[0052] Table 1 Salt spray test results

[0053]

[0054] Example 1 exhibits the most excellent protective performance. Its salt spray resistance time reaches 30 days, which is 20% higher than that of Comparative Example 1 (25 days), and is significantly better than other comparative examples (5 - 21 days). The addition of CB not only fills the internal pores of the coating but also forms a three-dimensional barrier network, resulting in the excellent salt spray resistance performance of the example.

[0055] (2) Stability of the coating

[0056] In this invention, a double test method of sandpaper abrasion and tape peeling is adopted to evaluate the stability of the coatings of Examples 1 - 4 and Comparative Examples 1 - 4. Sandpaper abrasion test: Fix a 1000-mesh sandpaper on a horizontal test bench, place the side of the sample with the coating facing down, and place a 100 g weight on the side without the coating. Make the specimen move linearly back and forth horizontally by traction, and count one wear cycle for every 20 cm travel. Tape peeling test: Use 3M tape. First, flatten and attach the tape to the surface of the coating, use a 100 g weight to press the tape and the coating along the length direction of the sample, and finally peel the tape completely; this process is regarded as one tape peeling cycle. After the sandpaper abrasion and tape peeling cycles, record the changes in the contact angle and rolling angle on the coating surface. When the contact angle is lower than 150° or the rolling angle is lower than 10°, the test ends. The test results are shown in Table 2.

[0057] Table 2 Stability of the coating

[0058]

[0059] (3) Photothermal ice melting test of the coating

[0060] Forty microliters of water droplets were respectively dropped onto the surfaces of aluminum alloy, Example 1 and Comparative Example 1. In an environment of -15 °C without light, the time for the water droplets to completely freeze was recorded. The test results were as follows: In an environment without light, the freezing time of the water droplets on the surface of Example 1 was 821 s; it was 783 s longer than the freezing time of the water droplets on the aluminum alloy surface and 49 s longer than the freezing time of the water droplets on the surface of Comparative Example 1. After the water droplets were completely frozen, the xenon lamp was turned on to test the photo-thermal de-icing ability of the coating. The water droplets did not melt within 900 s on the aluminum alloy surface. The water droplets on the surface of Example 1 started to melt at 16 s and completely melted at 182 s; the water droplets on the surface of Comparative Example 1 started to melt at 23 s and completely melted at 227 s. In comparison, the coating of Example 1 has excellent anti-icing characteristics.

[0061] The above content is part of the embodiments of the present invention. It is only the best embodiment of the present invention and does not impose any formal restrictions on the present invention. For those skilled in the art, without departing from the concept of the present invention, other deformations and improvements can be made, which all fall within the protection scope of the present invention.

Claims

1. A method for preparing a ZIF-8 based photothermal super hydrophobic anticorrosive coating, characterized in that, The following steps are involved: S1. Preparation of ZIF-8@PDA particles: Dissolve zinc salt and dopamine hydrochloride in deionized water to form solution A, and dissolve 2-methylimidazole in deionized water to form solution B. Mix solution A and solution B and stir at room temperature to obtain a black turbid solution. Wash the solution by centrifugation and freeze-dry to obtain polydopamine-modified ZIF-8 particles (ZIF-8@PDA). S2. Preparation of ZIF-8-based photothermal super-hydrophobic anti-corrosion coating: a certain proportion of ZIF-8@PDA and carbon material are dispersed in ethanol in a stirring manner, reacted with a modifier under an alkaline environment, centrifuged, and an organic solvent and a binder are added again. After stirring evenly, a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating is obtained, and the coating is sprayed onto the surface of the substrate by a spraying method. After curing, a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating is obtained; The modifiers in step S2 are tetraethyl silicate and hexadecyltrimethoxysilane.

2. the preparation method of a kind of ZIF-8 base photothermal super hydrophobic anticorrosive coating according to claim 1, is characterized in that, The zinc salt in step S1 is one of zinc nitrate, zinc acetate, and zinc gluconate; the mass concentration of dopamine hydrochloride in solution A is 0.1 g / mL, the mass concentration of the zinc salt in solution A is 0.02 g / mL, and the molar ratio of the zinc salt to 2-methylimidazole is 1:5-10; and the stirring time at room temperature is 12-48 h.

3. the preparation method of a kind of ZIF-8 base photothermal super hydrophobic anticorrosive coating according to claim 2, is characterized in that, The stirring time at room temperature in step S1 is 24 h.

4. the preparation method of a kind of ZIF-8 base photothermal super hydrophobic anticorrosive coating according to claim 1, is characterized in that, In step S2, the mass ratio of ZIF-8@PDA to carbon material is 1:0.25~1; the carbon material is one or more of carbon black, carbon nanotubes, and graphene.

5. the preparation method of a kind of ZIF-8 base photothermal super hydrophobic anticorrosive coating according to claim 1, is characterized in that, Every 6 g of the mixture of ZIF-8@PDA and carbon materials in step S2 was dispersed in 250 mL of ethanol.

6. a preparation method of a ZIF-8 based photothermal super hydrophobic anticorrosive coating according to claim 1, is characterized in that, The alkaline environment in step S2 is prepared by adding an ammonia solution to ethanol.

7. a preparation method of a ZIF-8 based photothermal super hydrophobic anticorrosive coating according to claim 6, is characterized in that, In step S2, the volume ratio of ethanol: ammonia solution: tetraethyl silicate: hexadecyltrimethoxysilane is 50:0.6:0.6:0.

6.

8. a kind of preparation method of ZIF-8 base photothermal super hydrophobic anticorrosive coating according to claim 1, is characterized in that, The adhesive in step S2 is one of polysilazane, triisopropylphenyl phosphate, epoxy resin, polydimethylsiloxane or thermoplastic polyurethane.

9. according to the preparation method of a kind of ZIF-8 base photothermal super hydrophobic anticorrosive coating described in any one of claim 1-8, it is characterised in that, In step S1, the carbon material is carbon black; in step S2, the organic solvent is butyl acetate, and the binder is polysilazane and triisopropylphenyl phosphate.

Images