ZIF-8-based photo-thermal super-hydrophobic anti-corrosion and anti-icing coating and preparation method thereof

Abstract

The invention discloses a preparation method of a ZIF-8-based photo-thermal super-hydrophobic anti-corrosion and anti-icing coating, which comprises the following steps: S1, preparing ZIF-8 (at) PDA particles: synthesizing polydopamine modified ZIF-8 (at) PDA particles in water in one step; S2, preparing the ZIF-8-based photo-thermal super-hydrophobic anti-corrosion and anti-icing coating: carrying out composite super-hydrophobic modification on ZIF-8 (at) PDA and a carbon material according to a certain proportion, adding an adhesive, stirring, and carrying out vacuum drying to obtain the ZIF-8-based photo-thermal super-hydrophobic anti-corrosion and anti-icing coating. And spraying the mixture on the surface of a base material, and curing to obtain the ZIF-8-based photo-thermal super-hydrophobic anti-corrosion and anti-icing coating. The ZIF-8-based photo-thermal super-hydrophobic anti-corrosion and anti-icing coating material prepared by the preparation method disclosed by the invention shows excellent super-hydrophobicity, mechanical stability and corrosion resistance. Meanwhile, the ZIF-8-based photo-thermal super-hydrophobic anticorrosive coating shows excellent passive icing delay and active photo-thermal deicing capabilities on the surface of the aluminum alloy. And a brand-new strategy is provided for deicing of industrial facilities and equipment in winter.

Description

Technical Field

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

[0002] Marine engineering facilities and equipment not only face corrosion problems caused by the harsh marine environment, but also face the problem of surface icing in winter. The synergistic effect of corrosion and surface icing is particularly harmful to marine engineering facilities and equipment. The moisture produced by ice melting will accelerate the occurrence of corrosion, and the rough surface corrosion products produced 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 safety hazards.

[0003] In recent years, super-hydrophobic coatings with special solid-liquid contact state (contact angle with water greater than 150°, rolling angle less than 10°) have attracted much attention in the scientific and industrial communities. The non-wetting and liquid repellency of super-hydrophobic coatings have shown great advantages in the fields of self-cleaning, anti-corrosion, anti-fouling, and anti-icing.

[0004] Although super-hydrophobic coatings have great advantages in the fields of corrosion protection and anti-icing on metal surfaces, super-hydrophobic coatings can only delay ice formation and cannot be removed actively. With the accumulation of ice, once the super-hydrophobic coating is completely covered by the ice, the anti-icing effect will not be achieved. This greatly hinders the further development of super-hydrophobic coatings in the field of anti-icing. Deicing technologies such as electric deicing, mechanical deicing, and chemical deicing in the prior art not only have low efficiency, but also corrode metals. Therefore, it is of great significance to develop a super-hydrophobic anti-corrosion and anti-icing with active deicing function. Summary of the invention

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

[0006] The present invention provides a method for preparing a ZIF-8-based photothermal super-hydrophobic anti-corrosion and anti-icing coating, comprising the following steps: S1. Preparation of ZIF-8@PDA particles: zinc salt and dopamine hydrochloride were dissolved in ionized water to form solution A, 2-methylimidazole was dissolved in deionized water to form solution B, solution A and solution B were mixed and stirred at room temperature for a certain period of time to obtain a black turbid solution, which was centrifuged and washed, and freeze-dried to obtain ZIF-8 particles modified with polydopamine, ZIF-8@PDA; S2. Preparation of ZIF-8-based photothermal super hydrophobic anti-corrosion and anti-icing coating: disperse a certain proportion of ZIF-8@PDA and carbon material in ethanol in a stirring manner, react with the modifier in an alkaline environment for a certain period of time, centrifuge, re-add the organic solvent and binder, and stir evenly to obtain the ZIF-8-based photothermal super hydrophobic anti-corrosion and anti-icing coating. Spray the coating onto the surface of the substrate, and obtain the ZIF-8-based photothermal super hydrophobic anti-corrosion and anti-icing coating after curing.

[0007] The air layer captured by the super-hydrophobic coating can effectively reduce the solid-liquid contact area, which can not only block the direct contact between the corrosive medium and the material surface, but also delay the formation and adhesion of ice crystals.

[0008] Furthermore, the zinc salt in step S1 is one of zinc nitrate, zinc acetate and zinc gluconate.

[0009] Furthermore, in step S1, the mass concentration of dopamine hydrochloride in solution A is 0.1 g / mL, and the mass concentration of zinc salt in solution A is 0.02 g / mL.

[0010] Furthermore, in step S1, the molar ratio of the zinc salt to 2-methylimidazole is 1:5-10.

[0011] Furthermore, the stirring time at room temperature in step S1 is 12 to 48 h, preferably 24 h.

[0012] Furthermore, in step S2, the ratio of ZIF-8@PDA to carbon material is 1:0.25~1.

[0013] Furthermore, the carbon material is one or more of carbon black, carbon nanotubes and graphene.

[0014] Furthermore, every 6 g of the mixture of ZIF-8@PDA and carbon materials was dispersed in 250–350 mL of ethanol.

[0015] Furthermore, the alkaline environment in step S2 is obtained by adding an ammonia solution into ethanol.

[0016] Furthermore, the modifiers in step S2 are tetraethyl silicate and hexadecyltrimethoxysilane.

[0017] Furthermore, in step S2, the ratio of ethanol: ammonia solution: tetraethyl silicate: hexadecyltrimethoxysilane is 50:6:1:1-2.

[0018] Furthermore, the organic solvent in step S2 is one of butyl acetate, ethanol and ethyl acetate.

[0019] Furthermore, the binder in step S2 is one or more of triisopropylphenyl phosphate, polysilazane, epoxy resin, polydimethylsiloxane and thermoplastic polyurethane.

[0020] Furthermore, 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 triisopropylphenyl phosphate. Carbon black is cheap and widely available compared to other carbon materials. Polysilazane, as an emerging adhesive, does not require a curing agent and harsh curing conditions compared to traditional binders such as epoxy resin and polydimethylsiloxane, and can cure itself. Triisopropylphenyl phosphate and polysilazane work synergistically to prolong the diffusion time of the corrosive medium, significantly improve the antioxidant properties of the carbon material, and improve the anti-corrosion performance of the coating.

[0021] The present invention uses micron-sized ZIF-8@PDA and nano-sized carbon materials as photothermal super-hydrophobic particles and binders to form ZIF-8-based photothermal super-hydrophobic anti-corrosion and anti-icing coatings. First, the low surface energy material possessed by the coating and the air layer captured by the surface micro-nano structure can achieve physical barriers to corrosive media, so that the coating has certain anti-corrosion properties, and can also serve the purpose of delaying icing. At the same time, the micro-nano structure on the surface of the coating causes sunlight to be reflected and absorbed multiple times on the surface of the coating, similar to a "trap" that captures sunlight, which increases the absorption rate of the coating to sunlight, so that the coating has certain photothermal properties, thereby achieving the purpose of active photothermal deicing. ZIF-8-based photothermal super-hydrophobic anti-corrosion and anti-icing coatings can meet the needs of marine ships, coastal infrastructure, petroleum, chemical industry, electric power, automobiles, etc. involving the field of metal corrosion and anti-icing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The effects of droplets of different properties on the surface of Example 1; Figure 2 Infrared thermal imaging of aluminum alloy, comparative example 1, and embodiment 1 at a sunlight intensity of 10 min; Figure 3 The process of delayed freezing at -15°C for aluminum alloy, comparative example 1, and example 1; Figure 4 Photothermal ice melting process of aluminum alloy, comparative example 1 and embodiment 1 under one sunlight intensity. DETAILED DESCRIPTION

[0023] The preparation and performance of the ZIF-8-based photothermal superhydrophobic anticorrosion coating of the present invention are further described below through specific examples.

[0024] Example 1 S1. Preparation of ZIF-8@PDA particles: 12.25 g zinc gluconate and 0.10 g dopamine hydrochloride were dissolved in 300 mL ionized water to form solution A, and 16.00 g 2-methylimidazole was dissolved in 200 mL deionized water to form solution B. Solution A and solution B were mixed and stirred at room temperature for 24 h to obtain a black turbid solution, which was washed by centrifugation and freeze-dried to obtain ZIF-8@PDA particles.

[0025] S2. Preparation of ZIF-8-based photothermal super-hydrophobic anti-corrosion coating: 0.30 g ZIF-8@PDA and 0.30 g carbon black were dispersed in 25 mL ethanol, and 0.3 mL ammonia water, 0.3 mL tetraethyl silicate, and 0.3 mL hexadecyltrimethoxysilane were added in sequence. After reacting for 4 h, the mixture was centrifuged, and 10 mL butyl acetate, 1.20 g polysilazane, and 0.1 g triisopropylphenyl phosphate were added again. After stirring evenly, a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating was obtained. The coating was sprayed onto the surface of the aluminum alloy, and a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating was obtained after curing.

[0026] Example 2 Preparation of ZIF-8@PDA particles: 12.25 g zinc gluconate and 0.10 g dopamine hydrochloride were dissolved in 300 mL ionized water to form solution A, and 8.00 g 2-methylimidazole was dissolved in 200 mL deionized water to form solution B. Solution A and solution B were mixed and stirred at room temperature for 36 h to obtain a black turbid solution, which was centrifuged and washed, and freeze-dried to obtain ZIF-8@PDA particles.

[0027] S2. Preparation of ZIF-8-based photothermal super-hydrophobic anti-corrosion coating: 0.48 g ZIF-8@PDA and 0.12 g carbon nanotubes were dispersed in 25 mL ethanol, and 0.3 mL ammonia water, 0.3 mL tetraethyl silicate, and 0.3 mL hexadecyltrimethoxysilane were added in sequence. After reacting for 6 h, centrifugation was performed, and 10 mL ethanol and 0.60 g epoxy resin (E-44 epoxy resin and polyamide 650 curing agent, the mass ratio of epoxy resin to curing agent was 1:1) were added again. After stirring evenly, a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating was obtained. The coating was sprayed onto the glass surface, and the ZIF-8-based photothermal super-hydrophobic anti-corrosion coating was obtained after curing.

[0028] Example 3 Preparation of ZIF-8@PDA particles: 7.80 g zinc nitrate and 0.10 g dopamine hydrochloride were dissolved in 300 mL ionized water to form solution A, and 16.00 g 2-methylimidazole was dissolved in 200 mL deionized water to form solution B. Solution A and solution B were mixed and stirred at room temperature for 48 h to obtain a black turbid solution, which was centrifuged and washed, and then freeze-dried to obtain ZIF-8@PDA particles.

[0029] S2. Preparation of ZIF-8-based photothermal super-hydrophobic anti-corrosion coating: 0.40 g ZIF-8@PDA and 0.20 g graphene were dispersed in 25 mL ethanol, and 0.3 mL ammonia water, 0.3 mL tetraethyl silicate, and 0.3 mL hexadecyltrimethoxysilane were added in sequence. After reacting for 2 h, the mixture was centrifuged and 15 mL ethyl acetate and 1.10 g polydimethylsiloxane (Sylgard 184 A type polydimethylsiloxane and Sylgard 184 B type curing agent, the mass ratio of polydimethylsiloxane to curing agent was 10:1) were added again. After stirring evenly, a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating was obtained. The coating was sprayed onto the surface of the wooden board, and after curing, a ZIF-8-based photothermal super-hydrophobic anti-corrosion coating was obtained.

[0030] Example 4 Preparation of ZIF-8@PDA particles: 5.91 g zinc acetate and 0.10 g dopamine hydrochloride were dissolved in 300 mL ionized water to form solution A, and 16.00 g 2-methylimidazole was dissolved in 200 mL deionized water to form solution B. Solution A and solution B were mixed and stirred at room temperature for 12 h to obtain a black turbid solution, which was centrifuged and washed, and then freeze-dried to obtain ZIF-8@PDA particles.

[0031] S2. Preparation of ZIF-8-based photothermal super-hydrophobic anti-corrosion coating: Disperse 0.36 g ZIF-8@PDA and 0.24 g carbon black in 25 mL ethanol, add 0.3 mL ammonia water, 0.3 mL tetraethyl silicate, and 0.3 mL hexadecyltrimethoxysilane in sequence, react for 4 h and centrifuge, add 50 mL ethyl acetate and 0.5 g thermoplastic polyurethane again, stir evenly to obtain ZIF-8-based photothermal super-hydrophobic anti-corrosion coating, spray the coating onto the surface of the metal mesh, and obtain ZIF-8-based photothermal super-hydrophobic anti-corrosion coating after curing.

[0032] Comparative Example 1 The difference from Example 1 is that no carbon black is added.

[0033] Comparative Example 2 The difference from Example 1 is that hexadecyltrimethoxysilane is not added in step S2.

[0034] Comparative Example 3 The difference from Example 1 is that triisopropylphenyl phosphate is not added in step S2.

[0035] Comparative Example 4 The difference from Example 1 is that no polysilazane is added in step S2.

[0036] Performance Test: (1) Salt spray corrosion test The results of the salt spray corrosion test based on GB / T 10125 standard are shown in (Table 1).

[0037] Table 1 Salt spray test results

[0038]

[0039] Example 1 exhibits the best protection performance, with a salt spray resistance time of 30 days, which is 20% higher than that of Comparative Example 1 (25 days), and 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 of the example.

[0040] (2) Stability of coating The present invention uses a dual test method of sandpaper wear and tape stripping to evaluate the stability of the coatings of Examples 1-4 and Comparative Examples 1-4. Sandpaper wear test: Fix 1000 mesh sandpaper on a horizontal test bench, place the coated side of the sample downward, and place a 100 g weight on the uncoated side. The sample is pulled to perform reciprocating linear motion in the horizontal direction, and each 20 cm stroke is counted as a wear cycle. Tape stripping test: 3M tape is used. First, the tape is flatly attached to the coating surface, and a 100 g weight is used to compact the tape and the coating along the length of the sample, and finally the tape is completely stripped off; this process is a tape stripping cycle. After the sandpaper wear and tape stripping cycles, the changes in the contact angle and the rolling angle of the coating surface are recorded. The test ends when the contact angle is less than 150° or the rolling angle is less than 10°. The test results are shown in Table 2.

[0041] Table 2 Stability of coating

[0042]

[0043] (3) Coating photothermal ice melting test 40 microliters of water droplets were dropped on the surfaces of aluminum alloy, Example 1 and Comparative Example 1, respectively, and the time for the water droplets to completely freeze was recorded in a -15°C lightless environment. The test results are: in a lightless environment, the time for the water droplets to freeze on the surface of Example 1 is 821 seconds; 783 seconds longer than the time for the water droplets to freeze on the surface of the aluminum alloy, and 49 seconds longer than the time for the water droplets to freeze on the surface of Comparative Example 1. After the water droplets are completely frozen, the xenon lamp is turned on to test the photothermal deicing ability of the coating. The water droplets will not melt on the surface of the aluminum alloy within 900 seconds, the water droplets on the surface of Example 1 begin to melt in 16 seconds and completely melt in 182 seconds; the water droplets on the surface of Comparative Example 1 begin to melt in 23 seconds and completely melt in 227 seconds. In comparison, the coating of Example 1 has excellent anti-icing properties.

[0044] The above contents are only part of the embodiments of the present invention, which are only the best embodiments of the present invention and do not limit the present invention in any form. For those skilled in the art, other variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a ZIF-8-based photothermal super-hydrophobic anticorrosion coating, characterized in that: The following steps are involved: S1. Preparation of ZIF-8@PDA particles: zinc salt and dopamine hydrochloride are dissolved in ionized water to form solution A, 2-methylimidazole is dissolved in deionized water to form solution B, solution A and solution B are mixed and stirred at room temperature to obtain a black turbid solution, which is centrifuged and washed, and freeze-dried to obtain ZIF-8 particles modified with polydopamine, ZIF-8@PDA; S2. Preparation of ZIF-8-based photothermal super-hydrophobic anti-corrosion coating: disperse a certain proportion of ZIF-8@PDA and carbon material in ethanol in a stirring manner, react with the modifier in an alkaline environment, centrifuge, re-add the organic solvent and binder, and stir evenly to obtain the ZIF-8-based photothermal super-hydrophobic anti-corrosion coating. Spray the coating onto the surface of the substrate, and obtain the ZIF-8-based photothermal super-hydrophobic anti-corrosion coating after curing.

2. The method for preparing a ZIF-8 based photothermal super hydrophobic anticorrosive coating according to claim 1, wherein 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 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; the stirring time at room temperature is 12-48 h, preferably 24 h.

3. A method for preparing a ZIF-8 based photothermal super hydrophobic anticorrosive coating according to claim 1, characterized in that, In step S2, the 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.

4. A method for preparing a ZIF-8 based photothermal super hydrophobic anticorrosive coating according to claim 1, 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.

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

6. according to claim 5 a kind of preparation method of ZIF-8 base photothermal super hydrophobic anticorrosive coating, it is characterised in that, The modifier in step S2 is tetraethyl silicate and hexadecyltrimethoxysilane, wherein the ratio of ethanol: ammonia solution: tetraethyl silicate: hexadecyltrimethoxysilane is 50:6:1:1-2.

7. A method for preparing a ZIF-8 based photothermal super hydrophobic anticorrosive coating according to claim 1, characterized in that, The binder in step S2 is one of polysilazane, triisopropylphenyl phosphate, epoxy resin, polydimethylsiloxane or thermoplastic polyurethane.

8. according to the preparation method of a kind of ZIF-8 based photothermal super hydrophobic anticorrosive coating described in any one of claims 1-7, 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.

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