A microstructured self-healing superhydrophobic coating, preparation method and application

Abstract

The present invention belongs to the field of superhydrophobic coatings, and particularly relates to a microstructured self-healing superhydrophobic coating, a preparation method and an application thereof. First, diatomaceous earth is calcined and added to an NaOH solution to obtain diatomaceous earth A. Then, diatomaceous earth A is mixed with octadecylamine liquid and subjected to vacuum impregnation to obtain diatomaceous earth DO impregnated with octadecylamine. Then, DO is added to a solvent, the pH is adjusted, and dopamine is added to obtain DOA. DOA is added to a solvent, and a bis-amino-terminated polydimethoxysilane is added to obtain N-DOA. N-DOA, NH2-PDMS-NH2 and an acrylic resin are added to a butyl acetate solution, and phthalaldehyde is added to obtain a mixed solution. Then, a microstructured self-healing superhydrophobic coating is prepared on a substrate through a spray gun. The coating has a high microstructural recovery rate and low preparation cost, and the preparation method realizes fluorine-free modification.

Description

Technical Field

[0001] The present invention belongs to the field of superhydrophobic coatings, and particularly relates to a microstructured self-healing superhydrophobic coating, a preparation method and an application thereof. Background Art

[0002] The hydrophobicity of a superhydrophobic coating depends on a low surface energy and surface micro-nano structures. However, during the actual application process, due to chemical and physical effects, the low surface energy and micro-nano structures are damaged, resulting in the Cassie-Wenzel transition of droplets. Therefore, the durability problem of superhydrophobic coatings limits their practical applications.

[0003] Regarding the durability problem of superhydrophobic coatings, current research mainly focuses on enhancing the mechanical strength of the coating itself and damage self-repair. Among them, self-healing coatings have been widely studied because they can self-repair damage, including self-healing coatings such as storing low surface energy substances in porous capsules, phase change movement of substances with low melting points, and promoting the thermal movement of chain segments by intermolecular kinetic bonds. For chemical damage, self-repair can be achieved by releasing low surface energy substances or the thermal movement of molecular chain segments to replace the generated polar groups, but there is little research on the self-repair of microstructures.

[0004] Liu et al. prepared a microstructured self-healing superhydrophobic coating through the thermal expansion of graphene and the elastic deformation characteristics of fluororubber resin (FKM). Zhang et al. used carnauba wax (CW) as a temperature-responsive phase change substance for the superhydrophobic coating, combined with modified fluororubber (MFR) and carbon nanofibers (CNF) with a large aspect ratio, and obtained a superhydrophobic FSR / CNF / CW / MFR composite coating with excellent structure repair performance, effectively improving the hydrophobic stability and service life of the superhydrophobic coating. Therefore, the present invention encapsulates octadecane phase change material in porous diatomite through the self-oxidative polymerization of dopamine, and after being modified with double amino-terminated PDMS, it is dispersed in a mixed solution of acrylic resin and PDMS, and a superhydrophobic coating with microstructured self-repair is prepared by a simple spraying method.

[0005] Currently, a microstructured self-healing superhydrophobic coating has been prepared by using the thermal expansion of graphene (EAG) and the elastic deformation characteristics of fluororubber resin (FKM). The main steps are to first synthesize fluorine-modified graphene nanoparticles, uniformly disperse 0.25 g of EAG and 2 mL of TEOS in 20 mL of ethanol, mechanically stir for 10 min, and dropwise add a mixed solution of 2 m of NH 3 ·H 2 O and 20 mL of ethanol to the above solution, and stir at a speed of 300 r / min for 12 h. Subsequently, 100 μL of 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (PFTS) is added to the EAG@SiO 2 gel, hydrolyzed for 12 h, and then dried at 80 °C to obtain EAG@SiO2 - PFTS particles can construct rich micro - nano structures during the calcination of the coating to achieve super - hydrophobic performance.

[0006] Then, the preparation of the super - hydrophobic coating is carried out: First, 1.0 g of polyphenylene sulfide (PPS) resin powder is dispersed in 10 mL of ethanol, and then the suspension is sprayed onto the polished aluminum substrate with an air spray gun at a pressure of 6 bar, and the spraying distance is maintained at 15 - 20 cm. After calcination at 300 °C, a pure PPS coating on the bottom layer is obtained to enhance the adhesion of the subsequent super - hydrophobic coating. Subsequently, 0.04 g of EAG@SiO - PFTS, 0.08 g of FKM, 1.0 g of PPS, and 0.1 g of FEP are dispersed in 10 mL of ethanol and magnetically stirred for 1 h to prepare a super - hydrophobic polymer suspension. Finally, the prepared suspension is sprayed onto the surface of the pre - coated PPS coating. During the heat treatment at 300 °C, a super - hydrophobic PPS / FKM / EG@SiO 2 coating can be obtained, and the coating consists of EAG@SiO 2 rapidly expands to EG@SiO 2 . However, using graphene to make a super - hydrophobic coating has problems such as high cost and fluorosis caused by introducing fluorosilane for hydrophobic modification, which is not friendly to the environment.

[0007] Preparation of CW and MFR composite particles: A mixed solution of 4 g of carnauba wax (CW) and 40 mL of ethyl acetate is placed in a reagent bottle and vigorously stirred in a water bath at 85 °C for 5 minutes. Subsequently, 20 mL of ethanol is added dropwise to the CW / ethyl acetate mixed solution at room temperature and stirred. After cooling, vacuum filtration, and drying, CW particles are obtained. 0.16 g of fluororubber (FR) particles are added to a mixed solution of 40 μL of POTS and 1 mL of ethyl acetate. While the FR particles undergo impregnation modification, they slightly expand, and finally, they are dried at 80 °C to obtain fluorosilane - modified fluororubber particles, named MFR.

[0008] Preparation of superhydrophobic coating: CNF (0.12 g) and MFR (0.12 g) particles were dispersed in ethyl acetate (15 mL) under strong ultrasonic vibration for 10 min. Subsequently, FSR resin (1 g), N3390 curing agent (1 g), and CW powder (0.05 g) were added to the solution, and strong ultrasonic vibration dispersion was carried out using an ultrasonic generator for 5 min. Finally, the solution was sprayed onto the treated aluminum plate under a pressure of 5 - 6 bar on a heating platform at 40 °C. After curing at 180 °C for 1 h in a forced-air drying oven, a superhydrophobic FSR / CNF / CW / MFR coating was successfully obtained. However, the cost of constructing a network structure using carbon nanofibers is high, which is not conducive to the widespread application of superhydrophobic coatings. The use of fluorosilane for hydrophobic modification is environmentally unfriendly. The phase change material carnauba wax used shows leakage after the temperature exceeds its melting point, reducing the cyclic service life of the coating. Therefore, there is an urgent need for a microstructured self-healing superhydrophobic coating, its preparation method, and application. Summary of the Invention

[0009] In view of the problems and disadvantages existing in the prior art, the present invention provides a preparation method for a microstructured self-healing superhydrophobic coating, comprising the following steps:

[0010] S1: Calcine diatomite, add it to a NaOH solution, stir, filter, and dry to obtain diatomite A;

[0011] S2: Mix diatomite A and octadecylamine liquid in a mass ratio of 2:1, and carry out vacuum impregnation to obtain diatomite DO impregnated with octadecylamine;

[0012] S3: Add the diatomite DO obtained in step 2 to a solvent, adjust the pH, stir, add dopamine and continue to stir, and then dry to obtain dopamine-encapsulated DOA;

[0013] S4: Add the DOA in step 3 to a solvent, add a bis-amino-terminated polydimethoxysilane, stir and wash, and vacuum dry to obtain polydimethoxysilane-modified N-DOA;

[0014] S5: Add the N-DOA obtained in step 4, polydimethoxysilane, and acrylic resin to a butyl acetate solution, stir, add phthalaldehyde and continue to stir to obtain a mixed liquid. Spray the mixed liquid onto the base material under pressure using a spray gun, and cure to obtain a microstructured self-healing superhydrophobic coating.

[0015] Further, the calcination time in S1 is 2 h, and the calcination temperature is 600 °C.

[0016] Further, the stirring time in S1 is 2 h, the stirring temperature is 75 °C, the drying temperature is 80 °C, and the drying time is 2 h.

[0017] Further, the impregnation temperature in S2 is 70°C and the impregnation time is 1 h.

[0018] Further, in S3, the pH is adjusted to 8.5, the stirring time is 1 - 2 h, the drying time is 2 h, and the drying temperature is 60°C.

[0019] Further, the stirring time in S4 is 12 h.

[0020] Further, the stirring time in S5 is 10 min, the curing temperature is 80°C, the curing time is 1 h, and the pressure is 0.5 Mpa.

[0021] A microstructured self - healing superhydrophobic coating, the coating is a lotus - leaf - like coating structure with micro - nano - scale papillae structure.

[0022] An application of a microstructured self - healing superhydrophobic coating, the coating is applied in the preparation of self - cleaning, anti - icing and anti - fouling coatings.

[0023] Technical effects

[0024] (1) A microstructured self - healing superhydrophobic coating provided by the present invention uses diatomite and octadecylamine with favorable prices to reduce the coating preparation cost, and the microstructural recovery rate of the coating is high. After being rubbed with 600 - mesh sandpaper for 2000 cm, under the action of the phase change of octadecylamine and the movement of molecular segments, the damaged structure recovers, and the superhydrophobic recovery rate is as high as 98.6%; and the coating is more environmentally friendly.

[0025] (2) A preparation method of a microstructured self - healing superhydrophobic coating provided by the present invention can be prepared on a large scale. Among them, the simple spraying method realizes the large - scale preparation of the coating. This preparation method uses NH 2 -PDMS-NH 2 to carry out hydrophobic modification of the coating, which not only enhances the dispersion of DOA in the matrix material, but also realizes fluorine - free modification.

[0026] (3) An application of a microstructured self - healing superhydrophobic coating provided by the present invention has a wide range of applications. Using AR / NH 2 -PDMS-NH 2 as the matrix material enhances the adhesion strength between the coating and many substrate materials and broadens its applications. Description of the drawings

[0027] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can be obtained based on these drawings. In the drawings:

[0028] Figure 1 It is a diagram showing the change in contact angle before and after the coating of Example 1 of the present invention is worn by 600-mesh sandpaper and after light-induced healing.

[0029] Figure 2 It is a diagram showing the change in surface morphology before and after the coating of Example 1 of the present invention is worn by 600-mesh sandpaper and after light-induced healing.

[0030] Figure 3 It is a process diagram of the preparation of the phase change capsule (a) and the photothermal self-healing superhydrophobic coating (b) of Example 1 of the present invention. Detailed implementation manners

[0031] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with Example 1 of the present invention and the attached Figures 1 to 3 , and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention.

[0032] A preparation method of a microstructured self-healing superhydrophobic coating provided by the present invention includes the steps of first calcining Changbai Mountain diatomite in a muffle furnace, then adding it to a NaOH solution, stirring and filtering, and then drying it in a vacuum drying oven to obtain diatomite A; then mixing diatomite A with octadecylamine (PCM) liquid in a mass ratio of 2:1, and then impregnating it in a vacuum drying oven to obtain diatomite DO impregnated with octadecylamine; then adding DO to deionized water solution, adjusting the pH of the solution, then stirring at room temperature, adding dopamine and continuing to stir, and drying in a vacuum drying oven to obtain dopamine-encapsulated DO (DOA). In S3, dopamine-encapsulated octadecylamine is selected, which not only endows the coating with photothermal properties and promotes the phase change of octadecylamine to repair damaged microstructures;

[0033] Adding DOA to an ethanol solution, and then adding an equal mass of diamine-terminated polydimethoxysilane (NH 2 -PDMS-NH 2 ), after stirring at room temperature, washing three times with an ethanol solution, and then vacuum drying to obtain NH 2 -PDMS-NH 2Modified DOA (N-DOA); the formed polydopamine undergoes a Schiff base reaction with diamino-terminated polydimethoxysilane in step S4 to graft the diamino-terminated polydimethoxysilane onto the surface of DOA, which not only plays a hydrophobic role but also promotes the movement of DOA along with the molecular segments through the dynamic imine bonds formed under the action of BTC, further promoting the microstructure repair;

[0034] Add N-DOA and NH 2 -PDMS-NH 2 and AR into the butyl acetate solution, stir, then add benzotrichloride (BTC) and continue stirring. Then, use a spray gun to spray the obtained mixed solution onto the substrate material under a pressure of 0.5 MPa, and cure to obtain a microstructural self-healing superhydrophobic coating.

[0035] Example 1

[0036] S1: Calcinate 5 g of Changbai Mountain diatomite in a muffle furnace at 600 °C for 2 h, then add it to a 1 mol / L NaOH solution, stir at 75 °C for 2 h, filter, and dry in a vacuum drying oven at 80 °C for 2 h to obtain diatomite A;

[0037] S2: Mix the diatomite A obtained in S1 with octadecylamine (PCM) liquid in a mass ratio of 2:1, impregnate in a vacuum drying oven at 70 °C and 0.8 MPa for 1 h to obtain diatomite DO impregnated with octadecylamine;

[0038] S3: Add the DO obtained in S2 to 20 ml of deionized water solution, adjust the solution pH = 8.5, stir at room temperature for 1 h, then add 50 wt% dopamine and continue stirring for 2 h, and dry in a vacuum drying oven at 60 °C for 2 h to obtain dopamine-encapsulated DO (DOA);

[0039] S4: Add the DOA obtained in S3 to an ethanol solution, then add an equal mass of diamino-terminated polydimethoxysilane (NH 2 -PDMS-NH 2 ), stir at room temperature for 12 h, wash three times with ethanol solution, and then dry in vacuum to obtain NH 2 -PDMS-NH 2 modified DOA (N-DOA);;

[0040] S5: Add the N-DOA obtained in S4 and NH 2 -PDMS-NH 2AR and AR were added to the butyl acetate solution and stirred for 10 min, then benzoyl trichloride (BTC) was added and stirring continued for 10 min. Using a spray gun with a diameter of 0.5 mm, the obtained mixed solution was sprayed onto the substrate material under a pressure of 0.5 MPa and cured at 80 °C for 1 h to obtain a microstructured self-healing superhydrophobic coating.

[0041] From Figure 1 It can be seen that under a load of 200 g, after friction for 2000 cm, the contact angle decreased from 159.7° to 149.2°, indicating that the microstructure was damaged during the friction process, resulting in an increase in the solid-liquid contact area and a decrease in the contact angle. After 20 min of light irradiation, the contact angle recovered to 158.9°. Due to the photothermal effect of the coating, the movement of the NH 2 -PDMS-NH 2 segment was promoted. At the same time, the damaged diatomite released octadecylamine, and octadecylamine underwent a phase change, further promoting the repair of the microstructure, so the contact angle increased.

[0042] From Figure 2 it can be seen that after the coating was worn, the surface microstructure was partially worn. After light irradiation, new microstructures appeared on the worn surface under the action of the movement of the NH 2 -PDMS-NH 2 segment and the phase change of octadecylamine, enabling the damaged surface microstructure to be repaired.

[0043] From Figure 3 it is known that in order to prevent the leakage problem of the phase change material, octadecylamine was encapsulated in the voids of high-strength diatomite through dopamine. As shown in Figure (a), the pore size of diatomite was increased by calcination and alkali treatment, and then octadecylamine was encapsulated in the pores of diatomite by vacuum impregnation. After dopamine coating, not only the photothermal performance was imparted to the phase change capsule, but also it was beneficial for the 2 -PDMS-NH 2 hydrophobic modification. The preparation process of the coating is shown in Figure (b). AR, PDMS, BTC and N-DOA were added to the butyl acetate solution and stirred, and then evenly sprayed onto the substrate surface using a spray gun, and a self-healing superhydrophobic coating was obtained after drying.

[0044] The present invention provides a microstructured self-healing superhydrophobic coating based on diatomite and octadecylamine, which greatly reduces the preparation cost. This coating has excellent self-healing characteristics. After being rubbed with 600-mesh sandpaper for 2000 cm, it can still restore its microstructure under the action of the phase change of octadecylamine and the movement of molecular segments, and the recovery rate is as high as 98.6%, showing excellent durability and anti-damage ability. In addition, the present invention pays attention to environmental protection, and the coating uses more green and sustainable materials, further reducing the impact on the environment and making it more advantageous in practical applications.

[0045] Through a preparation method of a microstructured self-healing superhydrophobic coating provided by the present invention, the preparation method is not only simple and economical, but also particularly suitable for large-scale production. Through a simple spraying process, a self-healing superhydrophobic coating can be efficiently and uniformly generated on a large-area substrate. This method uses NH 2 -PDMS-NH 2 as a hydrophobic modifier for the coating, which not only enhances the dispersion of octadecylamine (DOA) in the matrix material, but also realizes fluorine-free modification, making the entire preparation process more environmentally friendly and meeting the requirements of modern industry for environmentally friendly materials.

[0046] Through the application of a preparation method of a microstructured self-healing superhydrophobic coating provided by the present invention, the microstructured self-healing superhydrophobic coating of the present invention has a wide range of applications. Using AP / NH 2 -PDMS-NH 2 as the matrix material greatly improves the adhesion strength between the coating and various substrate materials, making it applicable to a variety of industrial fields, including aerospace, automotive manufacturing, electronic devices, etc. At the same time, the coating material of the present invention has excellent wear resistance and anti-fouling properties, showing extremely high reliability and long-term effectiveness in practical applications. This wide range of applicability gives it broad prospects in industry and daily life.

Claims

1. A method for preparing a microstructured self-healing super-hydrophobic coating, characterized in that: The following steps are involved: S1: calcining diatomaceous earth, adding it to a NaOH solution, stirring, filtering and drying to obtain diatomaceous earth A; S2: mixing diatomite A and octadecylamine liquid in a mass ratio of 2:1, and performing vacuum impregnation to obtain diatomite DO impregnated with octadecylamine; S3: adding the diatomaceous earth DO obtained in step 2 to the solvent, adjusting the pH, stirring, adding dopamine, continuing to stir, and drying to obtain dopamine-encapsulated DOA; S4: adding the DOA obtained in step 3 to a solvent, adding diamino-terminated polydimethoxysilane, stirring and washing, and vacuum drying to obtain polydimethoxysilane-modified N-DOA; S5: Add the N-DOA obtained in step 4, polydimethoxysilane and acrylic resin to the butyl acetate solution and stir, add benzaldehyde and continue stirring to obtain a mixed liquid, use a spray gun to spray the mixed liquid on the base material under pressure, and cure it to obtain a microstructure self-healing super hydrophobic coating.

2. A method for preparing a microstructured self-healing super-hydrophobic coating according to claim 1, characterized in that, The calcination time described in S1 is 1 to 3 hours, and the calcination temperature is 600°C.

3. A method for preparing a microstructured self-healing super-hydrophobic coating according to claim 1, characterized in that, The stirring time described in S1 is 2 hours, the stirring temperature is 75° C., the drying temperature is 80° C., and the drying time is 2 hours.

4. A method for preparing a microstructured self-healing super-hydrophobic coating according to claim 1, characterized in that, In S2, the immersion temperature is 70° C. and the immersion time is 1 hour.

5. A method for preparing a microstructured self-healing super-hydrophobic coating according to claim 1, characterized in that: In S3, the pH is adjusted to 8.5, the stirring time is 1 to 2 hours, the drying time is 2 hours, and the drying temperature is 60°C.

6. A method for preparing a microstructured self-healing super-hydrophobic coating according to claim 1, characterized in that: The stirring time in S4 is 12 h.

7. The method for preparing a microstructured self-healing super-hydrophobic coating according to claim 1, characterized in that: In S5, the stirring time is 10 min, the curing temperature is 80° C., the curing time is 1 h, and the pressure is 0.5 MPa.

8. A microstructured self-healing super-hydrophobic coating obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The coating is a lotus leaf-like coating structure with a micro-nano-scale papillary structure.

9. The use of a microstructure self-healing super-hydrophobic coating according to claim 8, characterized in that: The coating is used in preparing self-cleaning, anti-icing and anti-fouling coatings.

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