Light-absorbing hydrophobic material with micro-nano structure, preparation method and hydrophobic coating containing the material

Abstract

The application discloses high-light-absorption super-hydrophobic material with micro-nano structure, and discloses a preparation method of the high-light-absorption super-hydrophobic material and a hydrophobic coating containing the material. The micro-morphology of the high-light-absorption super-hydrophobic material is that a plurality of nanoscale needle-shaped structures are arranged in order to form a micrometer flower-shaped structure; the nanoscale needle-shaped structure takes cobalt tetroxide as a matrix, and the matrix is doped with manganese and nickel. The high-light-absorption super-hydrophobic material has high-light-absorption heat collection performance and good hydrophobic performance, so that the coating obtained subsequently can achieve the purposes of heat collection and hydrophobicity and dirt prevention.

Description

Technical Field

[0001] This invention relates to a high light-absorbing superhydrophobic material with a micro / nano structure, and also to a method for preparing the above-mentioned high light-absorbing superhydrophobic material and a hydrophobic coating containing the above-mentioned material. Background Technology

[0002] Solar energy is a pollution-free and reusable energy source, and its most basic utilization method is through photothermal conversion. Photothermal conversion materials can effectively convert light energy into heat energy. Among these, the application of photothermal conversion materials in insulation blankets can help ensure life and property protection in situations such as wilderness survival and emergency rescue, showing great promise. However, over time, these materials will accumulate a large amount of mold and scale on their surface, thus affecting their further use.

[0003] Existing superhydrophobic coatings for heat collection, such as those developed by Sun Peng et al., use carbon black as the photothermal conversion material and PDMS as the flexible substrate. They successfully prepared a PDMS / carbon black photothermal superhydrophobic film with good flexibility using a combination of photolithography and stencil method. The film has a water contact angle of 151.1° and superhydrophobic properties, but its absorbance is only 88.2%, which is not ideal. Li Huigui et al. prepared a carbon black / PDMS photothermal superhydrophobic coating by spraying epoxy resin as an adhesive onto a substrate surface, followed by spraying a blend of carbon black nanoparticles, polydimethylsiloxane (PDMS), and heptadecafluorodecyltriethoxysilane (PFDTES). The water droplet contact angle on the coating surface reached as high as 161°, but the equilibrium temperature on a stainless steel substrate under one solar intensity was only 72.3°, indicating room for improvement. Wu et al. prepared a PSCS photothermal superhydrophobic surface using candle ash, silica shell, and PDMS, achieving a PSCS surface contact angle of 163±1°. However, under one solar intensity, the coating temperature rose by 53°, indicating that the heat collection performance was not particularly excellent. From the above, it can be seen that currently prepared heat-collecting superhydrophobic coatings mainly rely on polymers such as PDMS to achieve hydrophobic properties and on materials such as carbon black to achieve heat collection performance. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a metal-based material that has both high light absorption and heat collection performance and good hydrophobic properties. Another purpose of this invention is to provide a method for preparing the above-mentioned high light absorption superhydrophobic material with micro-nano structure and a hydrophobic coating containing the above-mentioned metal-based powder. The coating obtained based on this coating can achieve the purpose of hydrophobicity and antifouling while collecting heat.

[0005] Technical solution: The high light absorption superhydrophobic material with micro-nano structure of the present invention has the following microstructure: multiple nano-scale needle-like structures are arranged in an orderly manner to form a micron-scale flower-like structure; the nano-scale needle-like structure is based on cobalt tetroxide, and the matrix is ​​doped with manganese and nickel.

[0006] Among them, the nanoscale needle-like structure (nanospin) has a particle size of 15–30 nm, and the micron-scale flower-like structure has a particle size of 2–5 μm.

[0007] The preparation method of the above-mentioned high light-absorbing superhydrophobic material with micro / nano structure includes the following steps:

[0008] (1) Three different metal salts, structure directing agent and pH adjuster are stirred and dissolved in a solution to obtain a precursor solution; the three metal salts are nickel salt, manganese salt and cobalt salt; wherein, by molar mass, the stoichiometric ratio of nickel salt, manganese salt and cobalt salt is 3:2:5;

[0009] (2) The precursor solution is placed in a high-pressure reactor and reacted at high temperature. After washing with water and drying, the precursor is obtained.

[0010] (3) The precursor was placed in a muffle furnace for high-temperature annealing and calcination to obtain a material with a micro-nano hierarchical structure.

[0011] In step (1), the structure directing agent is hexadecyltrimethylammonium bromide or hexamethylenetetramine, and the amount of structure directing agent added is 4-6% of the total mass of solid materials; the pH adjuster is urea, and the amount of pH adjuster added is 3-6% of the total mass of solid materials; the solution is composed of deionized water and ethylene glycol in a volume ratio of 2:1.

[0012] In step (2), the reaction temperature is 120-160℃ and the reaction time is 10-14h.

[0013] In step (3), the calcination temperature is 300-500℃ and the calcination time is 2-4h.

[0014] The hydrophobic coating containing the above-mentioned metal-based material is composed of the following components in parts by weight: 1 part metal-based material, 2 parts resin, 0.125 parts curing agent, 0.2 parts additives, and 9.35 to 9.45 parts organic solvent.

[0015] Wherein, the resin is a modified organosilicon resin or a fluorocarbon resin; the curing agent is a phenolic amine curing agent; the auxiliary agent is a silane coupling agent; and the organic solvent is a combination of anhydrous ethanol and butyl acetate in a volume ratio of 3:8.

[0016] The method for forming a coating based on the above-mentioned hydrophobic coating is as follows: the metal base material, resin, curing agent and additives in the formula amount are added to an organic solvent and stirred to dissolve to obtain a coating; the coating is sprayed onto the treated substrate to form a coating by spraying; the coating is dried at room temperature and then placed in an oven to cure, thus obtaining a coating.

[0017] The curing temperature is 50–80℃, and the curing time is 4–8 hours.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The metal-based powder material prepared by the present invention has a micro-nano structure that resembles lotus leaves. The micron-level flower-like structure of the material is formed by a loosely ordered array of nanoneedles. The loosely ordered distribution of the nanoneedle array gives the material a higher specific surface area and more light contact sites. At the same time, light is reflected and absorbed multiple times between the nanoneedles, achieving a high absorption rate, thereby greatly improving the photothermal conversion efficiency of the material; (2) At the same time, the metal-based powder material prepared by the present invention has a micro-nano structure that resembles lotus leaves, that is, the powder material contains both nano-level needle-like structures and micron-level flower-like structures. The needle-like structure and the micron-sized flower-like structure are similar to the nanofibers and micron-sized papillae of lotus leaves, respectively. The combination of these micro and nano structures gives the material good superhydrophobic properties. (3) The present invention combines modified organosilicon resin or fluorocarbon resin with high absorbance lotus leaf-like micro-nano structure powder material to obtain a coating with both high absorbance and superhydrophobic properties (because the coating surface retains the micron-sized papillae of the powder material, it achieves both high absorbance and superhydrophobic properties). The coating obtained by the present invention has an absorbance of 97.24% and a water contact angle of 155°. It can be coated on various substrates such as metal, fabric, plastic, and wood. Attached Figure Description

[0019] Figure 1 SEM images of the metal-based powder material with micro-nano hierarchical structure prepared in Example 1 at different magnifications;

[0020] Figure 2 SEM images of the high-light-absorbing superhydrophobic coating with lotus leaf-like micro / nano structure prepared in Example 2 at different magnifications;

[0021] Figure 3 The reflectance curve and absorptivity values ​​of the high light-absorbing superhydrophobic coating with a lotus leaf-like micro / nano structure prepared in Example 2 are shown.

[0022] Figure 4 The temperature change curve of the high light absorption superhydrophobic coating with lotus leaf-like micro-nano structure prepared in Example 2 under one solar radiation intensity;

[0023] Figure 5 The water contact angle (155°) and physical image of the high light-absorbing superhydrophobic coating with lotus leaf-like micro-nano structure prepared in Example 2 are shown.

[0024] Figure 6 SEM images of the metal-based powder material in Comparative Example 1 at different magnifications;

[0025] Figure 7 SEM images of the metal-based powder material in Comparative Example 2 at different magnifications;

[0026] Figure 8 SEM images of the metal-based powder material in Comparative Example 3 at different magnifications;

[0027] Figure 9 The reflectance curve and absorptivity values ​​of the coating obtained in Comparative Example 4 are shown.

[0028] Figure 10 The water contact angle of the coating obtained in Comparative Example 4 is 116°.

[0029] Figure 11 The reflectance curve and absorptivity values ​​of the coating obtained in Comparative Example 5 are shown.

[0030] Figure 12 The water contact angle of the coating obtained in Comparative Example 5 is 136°. Detailed Implementation

[0031] Example 1

[0032] The present invention discloses a method for preparing a high-light-absorbing superhydrophobic material with a micro / nano structure, comprising the following steps:

[0033] (1) Dissolve 1.96g C4H6MnO4·4H2O in a mixed solvent consisting of 20mL ethylene glycol and 40mL deionized water; then add 5.82g Co(NO3)2·6H2O, 3.48g Ni(NO3)2·6H2O, 0.6g urea and 0.6g CTAB (hexadecyltrimethylammonium bromide) to the above solution and stir for 30min to obtain the precursor solution;

[0034] (2) The precursor solution was placed in a high-pressure reactor made of polytetrafluoroethylene and sealed. It was reacted at 120°C for 12 hours. After the reaction, the solution was washed with deionized water by centrifugation until the washing liquid was neutral. The product after the reaction was placed in an oven and dried at 60°C to obtain the precursor.

[0035] (3) The precursor was placed in a muffle furnace and annealed and calcined at 450°C for 2 hours to obtain a metal-based powder material with a lotus leaf-like micro-nano structure.

[0036] pass Figure 1 It can be seen that the microstructure of the metal-based powder material prepared in Example 1 is as follows: multiple nanoscale needle-like structures are arranged in an orderly manner to form a micron-sized flower-like structure; the particle size of the nanoscale needle-like structure (nano needle) is 15-30 nm, and the particle size of the micron-sized flower-like structure is 2-5 μm.

[0037] The metal-based powder material of the present invention further enhances its intrinsic light absorption and heat collection performance through its special micro-nano hierarchical structure. At the same time, the special micro-nano hierarchical structure can also help enhance the hydrophobic properties of the coating formed subsequently.

[0038] Example 2

[0039] The present invention discloses a method for preparing a high-light-absorbing superhydrophobic coating with a lotus leaf-inspired micro / nano structure, comprising the following steps:

[0040] (1) Add 1g of metal-based powder material to 3mL of anhydrous ethanol and mix. Stir ultrasonically for 5min. After the mixture is finished, add 2g of fluorocarbon resin (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) and 0.2g of KH550 silane coupling agent to obtain a mixed solution. Mix the mixed solution with 8mL of butyl acetate and stir ultrasonically for 5min. Then add 0.125g of phenolic amine curing agent (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) and continue to stir ultrasonically for 10min to obtain the coating.

[0041] (2) The coating is applied to the treated substrate by manual spraying. The coating on the substrate is dried at room temperature and then cured in a 60°C oven for 6 hours to obtain the coating.

[0042] pass Figure 2 It can be concluded that the flower-like microstructure constructed by the powder in the coating is preserved, and the added fluorocarbon resin will coat the micro-flower-like structure of the powder. Overall, the coating is still dominated by micron-sized flower-like papillae and nano-sized spheres.

[0043] Comparative Example 1

[0044] The preparation method of Comparative Example 1 is exactly the same as that of Example 1, except that in step (1), nickel salt, manganese salt, and cobalt salt are mixed in a stoichiometric ratio of 2:3:5 to obtain a metal-based powder material. The SEM image of the metal-based powder material obtained in Comparative Example 1 is shown below. Figure 6 As shown, through Figure 6 It can be seen that although the metal salt ratio can still form a spherical micron-scale structure after the ratio is changed, the surface nanoscale structure is disordered and cannot form a regular array of nanoneedles.

[0045] Comparative Example 2

[0046] The preparation method of Comparative Example 2 is exactly the same as that of Example 1, except that in step (3), the calcination temperature is 750℃, resulting in a metal-based powder material. The SEM image of the metal-based powder material obtained in Comparative Example 2 is shown below. Figure 7 As shown, through Figure 7 It can be seen that the change in calcination temperature affected the formation of the flower-like structure, and the entire structure was irregularly and randomly distributed.

[0047] Comparative Example 3

[0048] The preparation method of Comparative Example 3 was exactly the same as that of Example 1, except that in step (1), the amount of urea added was 1.2 g, resulting in a metal-based powder material. The SEM image of the metal-based powder material obtained in Comparative Example 3 is shown below. Figure 8 As shown, through Figure 8 It can be seen that changes in urea content do not affect the formation of nanoneedle structures, but prevent them from arranging into flower-like structures.

[0049] To verify the heat collection and superhydrophobic properties of the high light absorption superhydrophobic coating prepared in Example 2, the following tests were conducted:

[0050] (1) Heat collection performance test:

[0051] Reflectance was measured using a UV-Vis-NIR spectrometer, with the test wavelength ranging from 0.2 to 2.5 μm. The absorptivity of the coating was calculated by combining the reflectance curve with solar energy spectroscopy. The test results are as follows. Figure 3 As shown, through Figure 3 It can be seen that the reflectance of this solar energy absorbing powder is low in the ultraviolet-visible-near infrared region, and the overall absorbance calculated is 97.24%.

[0052] The coating was continuously irradiated under a xenon lamp with strong sunlight, and the surface temperature changes were recorded using an infrared thermal imager. The test results are as follows: Figure 4 As shown, through Figure 4 It can be seen that the coating can be heated from room temperature (30℃) to 90℃ within 6 minutes.

[0053] (2) Superhydrophobicity test:

[0054] The water contact angle of the coating was tested using a CA measurement system (JC2000D2), and the test results are as follows: Figure 5 As shown, through Figure 5 It can be seen that the coating achieves superhydrophobic properties, with a water contact angle of 155°.

[0055] Comparative Example 4

[0056] The preparation method of Comparative Example 4 was exactly the same as that of Example 2, except that in step (1), the added fluorocarbon resin was replaced with polyurethane to obtain the coating. The heat collection and hydrophobic properties of the coating obtained in Comparative Example 4 were tested, and the results are as follows: Figure 9 , 10 As shown, through Figure 9 , 10 It can be seen that after the resin was replaced, the light absorption of the coating decreased, the water contact angle decreased significantly to only 116°, and the hydrophobic properties were greatly reduced.

[0057] Comparative Example 5

[0058] The preparation method of Comparative Example 5 was exactly the same as that of Example 2, except that in step (1), 0.5 g of fluorocarbon resin was added to obtain the coating. The heat collection and hydrophobic properties of the coating obtained in Comparative Example 5 were tested, and the results are as follows: Figure 11 , 12 As shown, through Figure 11 , 12 It can be seen that after the fluorocarbon content is reduced, the light absorption rate of the coating remains almost unchanged, but the water contact angle decreases significantly to only 136°, and the hydrophobicity is reduced.

Claims

1. A method for preparing a high-light-absorbing superhydrophobic coating with a lotus leaf-inspired micro / nano structure, characterized in that, Includes the following steps: (1) Add 1g of metal-based powder material to 3mL of anhydrous ethanol and mix. After ultrasonic stirring for 5min, add 2g of fluorocarbon resin and 0.2g of KH550 silane coupling agent to obtain a mixed solution. Mix the mixed solution with 8mL of butyl acetate and ultrasonically stir for 5min. Then add 0.125g of phenolic amine curing agent and continue ultrasonic stirring for 10min to obtain a coating. (2) The coating is applied to the treated substrate by manual spraying. The coating on the substrate is dried at room temperature and then cured in a 60°C oven for 6 hours to obtain the coating. In step (1), the metal-based powder material is prepared by the following method, the specific steps of which are as follows: (1.1) Dissolve 1.96g C4H6MnO4·4H2O in a mixed solvent consisting of 20mL ethylene glycol and 40mL deionized water; then add 5.82g Co(NO3)2·6H2O, 3.48g Ni(NO3)2·6H2O, 0.6g urea and 0.6g CTAB to the above solution, stir for 30min to obtain the precursor solution; (1.2) The precursor solution was placed in a high-pressure reactor made of polytetrafluoroethylene and sealed. It was reacted at 120°C for 12 hours. After the reaction, the solution was washed with deionized water by centrifugation until the washing liquid was neutral. The product after the reaction was placed in an oven and dried at 60°C to obtain the precursor. (1.3) The precursor was placed in a muffle furnace and annealed and calcined at 450°C for 2 hours to obtain a metal-based powder material with a lotus leaf-like micro-nano structure.

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