Method for preparing super-hydrophobic membrane, super-hydrophobic membrane and application of super-hydrophobic membrane

Abstract

The invention provides a method for preparing a super-hydrophobic membrane, the super-hydrophobic membrane and application of the super-hydrophobic membrane. The method comprises the following steps: 1) providing a parafilm; (2) placing the film on a metal substrate, and enabling the film to be in direct contact with the metal substrate; and 3) performing first laser processing on the metal substrate to obtain the parafilm with micro-nano particles on the surface. The advanced method which is simple and easy to implement, low in cost, environmentally friendly and suitable for automatic industrial manufacturing of the super-hydrophobic membrane is realized by using the easily available metal plate and the commercially available parafilm and combining nanosecond laser ablation and femtosecond laser drilling technologies and a roll-to-roll manufacturing mode. The invention also provides the super-hydrophobic membrane prepared by the method. The super-hydrophobic membrane has excellent super-hydrophobicity, air permeability, water-containing corrosive liquid resistance, photothermal effect, thermoplasticity and tensile property.

Description

Technical Field

[0001] The present invention belongs to the field of advanced material manufacturing, and in particular relates to a method for preparing a super-hydrophobic film, a super-hydrophobic film and applications thereof. Background Art

[0002] Wetting is a common phenomenon in the ambient atmosphere, caused by the tendency of liquid droplets to spread on most solid surfaces. This phenomenon has plagued humanity for many years. Designing and manufacturing anti-wetting materials to address this hot issue has led to a surge in research into superhydrophobic materials, with their overwhelming advantages and high demand. Scientists worldwide have been diligently developing high-performance superhydrophobic surface coatings based on low surface energy principles and the Cassie-Baxter theory to address this issue. Figure 1 The paper summarizes the main methods used in the existing technology, such as synthesizing small molecules and polymers containing low surface tension fragments (such as fluorine-containing and silicon-containing chemical groups), or designing specific umbrella-shaped and dendritic protective molecular structures to modify the surface to achieve superhydrophobicity. These chemical synthesis methods focus on following the principle of low surface energy and designing protective molecular structures, so that the product exhibits effective anti-wetting properties after exposure to water, moisture, pollutants, etc. These works point out effective ways and directions for designing superhydrophobic research ideas.

[0003] However, the application of these superhydrophobic materials presents several challenges: chemical coatings modified with fluorine-containing molecular chains can lead to the accumulation of difficult-to-treat fluorides that are difficult to degrade. When ingested by organisms, these compounds pose serious risks to the environment and humans. Furthermore, the chemical synthesis of these materials involves complex synthesis steps, product purification, and characterization, which is time-consuming and labor-intensive. The proper handling of chemical reagents used in the chemical synthesis process is also a vexing issue.

[0004] On the other hand, in recent years, some research works have produced superhydrophobicity by constructing surface morphologies with structures such as protrusions, micropores and micro-air pockets. This traditional physical method can effectively avoid the problems existing in the above-mentioned chemical synthesis. However, in the absence of feasible calculations and precise modulation, the surface physical morphology constructed by traditional physical methods such as solvent evaporation and nanoparticle doping will face new challenges. The size and distribution of its surface roughness are random, which will lead to a lack of good control over the surface hydrophobicity. In addition, physically constructed superhydrophobic surfaces or materials will also have defects such as poor durability and poor wear resistance due to the lack of strong chemical bonding. Summary of the Invention

[0005] To address the problems existing in the above-mentioned prior art, the present invention uses readily available metal sheets and commercially available parafilm films, combined with laser processing technology, to develop a method for manufacturing superhydrophobic films. This method greatly simplifies the chemical synthesis methods and physical means conventionally used in the prior art and has great potential for industrial large-scale production and practical application.

[0006] The present invention provides a continuous roll-to-roll method for manufacturing a super-hydrophobic film, and a super-hydrophobic film manufactured by the method. Specifically, the present invention provides:

[0007] (1) A method for preparing a super-hydrophobic film, comprising the following steps:

[0008] 1) Providing a parafilm membrane;

[0009] 2) placing the film on a metal substrate so that it is in direct contact with the metal substrate; and

[0010] 3) performing a first laser processing on the metal substrate to obtain a parafilm having micro-nano particles on the surface.

[0011] (2) The method according to (1), wherein the room temperature thermal conductivity of the metal substrate is 15 W / (m·K) to 200 W / (m·K), and the thermal expansion coefficient is 15×10 -6 / ℃ to 30×10 -6 / ℃, Brinell hardness is 20HBW to 300HBW.

[0012] (3) The method according to (1), wherein the metal substrate is selected from a stainless steel plate, a zinc plate, and an aluminum plate.

[0013] (4) The method according to (1), wherein the thickness of the metal substrate is 1 mm to 5 mm; preferably, the thickness of the metal substrate is 3 mm.

[0014] (5) The method according to (1), wherein the first laser processing includes nanosecond laser ablation; preferably, the nanosecond laser ablation is performed on the metal substrate from above the parafilm film through the parafilm film.

[0015] (6) The method according to (5), wherein the conditions of the nanosecond laser ablation are: laser frequency of 20 kHz, pulse width of 110 ns, laser energy and light intensity of each pulse of 70.28 J / cm 2 and 6.39×10 8 J / cm 2 / s.

[0016] (7) The method according to (1), wherein the method further comprises performing a second laser processing on the parafilm film to obtain a parafilm film having a micropore array on the surface.

[0017] (8) The method according to (7), wherein the second laser processing includes femtosecond laser drilling; preferably, the parafilm film is subjected to femtosecond laser drilling from above the parafilm film; preferably, the second laser processing is performed on the parafilm film having micro-nanoparticles on the surface obtained in step 3).

[0018] (9) The method according to (8), wherein the conditions of the femtosecond laser drilling are: laser frequency of 5 MHz, pulse width of 300 fs, laser energy and light intensity of each pulse of 0.12 J / cm 2 and 4×10 10 J / cm 2 / s.

[0019] (10) The method according to (1), wherein the parafilm and the metal substrate are placed on a roll-to-roll device, and the first laser processing is performed on the metal substrate.

[0020] (11) The method according to (7), wherein the parafilm film is placed on a roll-to-roll device and the second laser processing is performed on the parafilm film.

[0021] (12) The method according to (1), wherein the micro-nano particles include micro-nanoscale protrusions, depressions, air pockets, and a combination of one or more thereof.

[0022] (13) The method according to (12), wherein the average particle size of the micro-nanoscale protrusions, depressions and air pockets is 1 μm to 50 μm.

[0023] (14) The method according to (7), wherein the micropore array comprises pores with a diameter of 100 μm to 400 μm; preferably, the average pore diameter of the micropore array is 300 μm.

[0024] (15) A superhydrophobic film prepared by the method according to any one of (1) to (14).

[0025] (16) The superhydrophobic film according to (15), wherein the surface of the superhydrophobic film has micro-nano particles, and the micro-nano particles include micro-nanoscale protrusions, depressions, air pockets and a combination of one or more thereof; preferably, the surface of the superhydrophobic film also has a micropore array.

[0026] (17) The superhydrophobic film according to (15), wherein the average particle size of the micro-nanoscale protrusions, depressions and air pockets is 1 μm to 50 μm; preferably, the micropore array includes pores with a diameter of 100 μm to 400 μm; preferably, the average pore size of the micropore array is 300 μm.

[0027] (18) Application of the superhydrophobic film according to any one of (15) to (17) for waterproofing, anti-fogging, anti-icing, anti-corrosion and / or anti-microbial use.

[0028] (19) The use according to (18), wherein the superhydrophobic film is used to prepare a protective film for sealing, a protective layer for clothes or shoes, or a precursor material for a Janus film.

[0029] Compared with the prior art, the present invention has the following advantages and positive effects:

[0030] (1) The present invention simply places a commercial parafilm on a metal substrate and laser processes the substrate to impart micro-nanostructures (micro-nanoparticles) to the parafilm surface, thereby producing a superhydrophobic membrane. The present invention further produces a breathable superhydrophobic membrane with a micropore array. The method of the present invention is simple, cost-effective, highly efficient, reproducible, environmentally friendly, and capable of precisely controlling the size and distribution of the surface micro-nanostructures and micropore array.

[0031] (2) The laser processing technology used in the present invention has super high efficiency in manufacturing ideal surface morphology. Among them, nanosecond laser ablation technology can customize points and lines of different depths and spacings by adjusting and optimizing parameters such as laser ablation marking speed, working power, and laser filling spacing, thereby manufacturing the required surface micro-nanostructure; femtosecond laser drilling technology can customize micropore arrays with required hole size and hole spacing. The laser processing process takes a short time, only a few minutes, seconds or even a few nanoseconds. It is simple, easy, very low cost and environmentally friendly, and is suitable for the automated industrial manufacturing of breathable superhydrophobic membranes.

[0032] (3) The superhydrophobic film prepared according to the method of the present invention exhibits unique surface micro-nanoparticles, thereby exhibiting excellent superhydrophobicity. The average static contact angle of a deionized water droplet of approximately 4 μL exceeds 150°. When the surface is slightly tilted at an average tilt angle of no more than 10°, the water droplet can easily roll off the film without any residue.

[0033] (4) The superhydrophobic membrane with a micropore array prepared according to the method of the present invention has a surface microstructure and a uniform micropore array, exhibiting excellent superhydrophobicity. The average static contact angle is 159.67°±5.75°, and the rolling contact angle is 5.81°±2.46°. In a simulated perspiration test, by precisely controlling the flow rate of a 1 wt% NaCl solution, the air permeability of the superhydrophobic membrane of the present invention is comparable to that of commercially available rayon (also known as artificial silk) at a relative humidity of 90.83%±3.25%.

[0034] (5) The present invention can also utilize a continuous roll-to-roll manufacturing method, which is conducive to automated production and significantly improves productivity. Compared with complex laboratory chemical synthesis methods or traditional physical means, the method of the present invention has great potential for industrial large-scale production and practical application.

[0035] (6) The commercial sealing film (parafilm) and metal substrate (such as stainless steel substrate) used in the present invention are easy to obtain and low in cost.

[0036] (7) The superhydrophobic membrane of the present invention can be applied to protective clothing that is waterproof and anti-pollutant. Furthermore, the superhydrophobic membrane of the present invention exhibits excellent air permeability, resistance to aqueous corrosive liquids, photothermal effects, thermoplasticity, and stretchability, making it suitable as a multifunctional material for various applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The main methods used in the prior art to manufacture super-hydrophobic surfaces are shown.

[0038] Figure 2 The structure and performance schematic diagram of the super-hydrophobic membrane with a micropore array according to the present invention is shown. The super-hydrophobic membrane has beneficial super-hydrophobicity and air permeability.

[0039] Figure 3 A microscope photograph of a super-hydrophobic film according to the present invention is shown, wherein Figure 3 (a) and (b) are electron microscope images of superhydrophobic membranes with micropore arrays, where all scale bars =

[0040] 2mm; Figure 3 (c) is a scanning electron microscope image of the superhydrophobic film (without femtosecond laser drilling), where the scale bars in the upper left, upper right, and lower left images = 100 μm, and the scale bar in the lower right image =

[0041] 10 μm; Figure 3 (d) is a scanning electron micrograph of a superhydrophobic membrane having a micropore array, with scale bars = 100 μm in the upper left, upper right, and lower left images, and scale bar = 10 μm in the lower right image.

[0042] Figure 4 The results of characterization of the properties of the super-hydrophobic film according to the present invention are shown, wherein Figure 4 (a) shows the statistical results of the static contact angle test, where the numbers on the bar graph represent the mean values ​​and the error bars represent the standard deviations; the samples from left to right are: lotus leaf (control), original parafilm, super-hydrophobic film prepared in Example 1, super-hydrophobic film of Example 1 stretched twice, breathable super-hydrophobic film prepared in Example 2, and breathable super-hydrophobic film prepared in Example 2 stretched twice; Figure 4 (b) shows a representative photo of the static contact angle test. The samples from left to right are: lotus leaf (control), super-hydrophobic film prepared in Example 1, super-hydrophobic film of Example 1 stretched twice, and breathable super-hydrophobic film prepared in Example 2. Figure 4 (c) shows the silver mirror effect of the superhydrophobic film under water; Figure 4 (d) shows the waterproof test results of the breathable superhydrophobic membrane; Figure 4 (e) shows the rolling contact angle test results of the superhydrophobic film prepared in Example 1; Figure 4 (f) shows the rolling contact angle test results of the breathable superhydrophobic film prepared in Example 2; Figure 4 (g) shows the average rolling contact angle of the samples.

[0043] Figure 5 The air permeability test and results of the super hydrophobic membrane according to the present invention are shown, wherein Figure 5 (a) shows a human sweating scene simulation test apparatus, and the left and right insets show the water vapor permeation tests of the original parafilm film and the breathable superhydrophobic film prepared in Example 2, respectively; Figure 5 (b) and (c) show the Arduino-based humidity sensor; Figure 5 (d), (e), (f), and (g) show the results of quantitative evaluation of the air permeability of different materials.

[0044] Figure 6 The results of the corrosion resistance test and the photothermal test of the super hydrophobic film according to the present invention are shown; Figure 6 (a) shows a corrosion resistance test, wherein the red droplet is a droplet of a 1 M HCl aqueous solution (pH 0) placed on a super-hydrophobic film, the blue droplet is a droplet of a 1 M KOH aqueous solution (pH 14) placed on a super-hydrophobic film, and the colorless droplet is a droplet of deionized water (DI water) (pH 7) placed on a super-hydrophobic film. All scale bars in the figure = 10 mm; Figure 6 (b) shows the photothermal test results of the superhydrophobic film, the original parafilm film, and air. The temperature changes with time during 550 seconds of irradiation under one sun were detected by a thermocouple device. Figure 6(c) and (d) show the corresponding Figure 6 (b) Thermal imaging of the sample, scale bar = 10 mm.

[0045] Figure 7 A schematic diagram of manufacturing a breathable super-hydrophobic membrane by a roll-to-roll method according to the present invention is shown.

[0046] Figure 8 The diagram shows an enlarged schematic diagram of the surface morphology of a super-hydrophobic membrane with a micropore array according to the present invention. The membrane surface has a rough surface morphology and a uniformly distributed micropore array, and water droplets roll on the membrane surface to collect surface pollutants.

[0047] Figure 9 The long-term corrosion resistance test results of the super-hydrophobic film according to the present invention are shown. Figure 9 (a) shows the initial state of the superhydrophobic membrane. The left beaker contains 50 mL of 1 M KOH aqueous solution, which is stained with 50 μL of blue dye. The right beaker contains 50 mL of 1 M HCl aqueous solution, which is stained with 50 μL of red dye. Figure 9 (b) to (d) show the changes in solution color and membrane wettability during immersion of two superhydrophobic membranes in 1 M KOH (left) and 1 M HCl (right) solutions, respectively; Figure 9 (b) t = 0 hours; Figure 9 (c) t = 6 hours; Figure 9 (d) t = 16 hours. Figure 9 (e) shows the final state of two super-hydrophobic films after long-term immersion; the left side is the super-hydrophobic film after being soaked in 1M KOH solution for 20 hours; the right side is the super-hydrophobic film after being soaked in 1M HCl solution for 20 hours.

[0048] Figure 10 Shown are the water resistance and corrosion resistance test results of a superhydrophobic film stretched to 5 times its original length. Figure 10 (a) shows an elongated superhydrophobic film immersed in deionized water; Figure 10 (b) shows photos of droplets placed on an elongated superhydrophobic film taken at different angles, where the red droplets are droplets of 1M HCl aqueous solution (pH 0), the blue droplets are droplets of 1M KOH aqueous solution (pH 14), and the colorless droplets are droplets of deionized water (DI water) (pH 7). DETAILED DESCRIPTION

[0049] The present invention is further illustrated below by describing specific implementation methods, but this is not intended to limit the present invention. Those skilled in the art can make various modifications or improvements based on the basic ideas of the present invention, but as long as they do not deviate from the basic ideas of the present invention, they are all within the scope of the present invention.

[0050] When a water droplet reaches equilibrium on a solid surface, the wettability of the solid surface is influenced by two primary factors, according to Young's equation and the modified Cassie-Baxter equation. Both chemical composition and surface morphology influence wettability and serve as principles and strategies for the fabrication of superhydrophobic surfaces. Chemists tend to synthesize molecules or prepare compounds by adjusting molecular functional groups and chemical structures to develop a range of chemical formulations for superhydrophobic coatings. Typically, these chemical syntheses utilize fluorine- and silicon-containing molecules with ultra-low surface tension. When coated onto a solid surface, the fluorine- and silicon-containing chemical groups, due to their low surface energy and high polarity, aggregate at the outer solid-air interface, forming a barrier between the water and the solid surface, thereby protecting the solid surface from wetting by the water droplet. Uniquely designed umbrella- and dendritic-shaped molecular structures, due to the dense clustering of protective molecular groups on their outer layers, also contribute to this protective effect. Scientists have also studied how surface morphology determines the wettability of solid surfaces. Typically, specific micro- and nanostructures are required to impart anti-wetting properties to solid surfaces. Prior art methods primarily utilize solvent evaporation or the addition of micro- and nano-sized silicon particles to impart a hierarchical structure of micropores or protrusions to the surface, which can also trap micro-air pockets. Solid surfaces with appropriately sized and distributed micropores, protrusions, and micro-air pockets can effectively resist water penetration. Designing and manufacturing super-hydrophobic surfaces based on both chemical composition and surface morphology has become a trend in the field. However, both approaches have drawbacks during manufacturing and application.

[0051] As mentioned above, chemical synthesis methods introduce chemical coatings containing long-chain fluorinated molecules into practical applications. These can cause difficult-to-remove accumulation and are difficult to degrade, posing serious environmental and human hazards when ingested. Furthermore, the complex synthesis, purification, and characterization of these chemical molecules is time-consuming and labor-intensive. Fluorinated chemicals are often expensive. The proper handling of chemical reagents used in the preparation process is also a vexing issue.

[0052] On the other hand, traditional physical methods can more effectively generate hierarchical and heterogeneous micro-nano surface morphologies, which contribute to superhydrophobicity. However, due to the lack of stable chemical bonding, superhydrophobic structures constructed by physical doping are generally not wear-resistant and have poor durability. In recent years, improved physical methods that generate superhydrophobicity by constructing surface morphologies composed of protrusions, micropores and micro-air pockets can effectively overcome the above problems. These methods include solvent evaporation, freeze drying, phase separation, self-assembly, etc. However, in the absence of feasible calculations and precise modulation, these methods will face new challenges in the random size and distribution of surface roughness, which may require time-consuming and labor-intensive experiments and explorations.

[0053] The present invention provides a method for preparing a super-hydrophobic film, comprising the following steps:

[0054] 1) Providing a parafilm membrane;

[0055] 2) placing the film on a metal substrate so that it is in direct contact with the metal substrate; and

[0056] 3) performing a first laser processing on the metal substrate to obtain a parafilm having micro-nano particles on the surface.

[0057] The term "superhydrophobic" as used herein has a meaning known in the art. Typically, a superhydrophobic material has a surface stable static contact angle greater than 150° and a rolling contact angle less than 10°.

[0058] The method of the present invention can use a metal substrate with suitable hardness, good heat transfer effect, and not easy to deform by heat, so as to facilitate the laser processing process and the successful preparation of the superhydrophobic film. In some embodiments, the thermal conductivity of the metal substrate is 15W / (m·K) to 200W / (m·K), and the thermal expansion coefficient is 15×10 -6 / ℃ to 30×10 -6 / °C, and a Brinell hardness of 20 HBW to 300 HBW. When the above parameters of the metal substrate used deviate significantly from the above range, the heat transfer effect of the metal substrate will be affected, and the laser processing will cause significant thermal deformation of the metal substrate, thereby affecting the preparation of the superhydrophobic film.

[0059] Examples of the metal substrate include, but are not limited to, stainless steel plates, zinc plates, and aluminum plates. In a preferred embodiment, the metal substrate is a 304 stainless steel plate.

[0060] In some embodiments, the metal substrate has a thickness of 1 mm to 5 mm; preferably, the thickness of the metal substrate is 3 mm. If the metal substrate is too thin, it is susceptible to thermal deformation during repeated processing. If the metal substrate is too thick, it accumulates a high amount of heat, which can cause the parafilm to soften and become sticky, hindering film processing, transport on continuous roll-to-roll equipment, and debonding of the finished product.

[0061] Parafilm is a commercially available composite film material well-known to those skilled in the art. Its sealing properties make it suitable for use as a sealing film in research laboratories, hospitals, homes, gardening, and industrial packaging. Parafilm is composed of waxy materials such as polyolefins, which have low surface tension. It is also known as paraffin sealing film or sealing film.

[0062] In the method of the present invention, the parafilm is simply placed on the metal substrate so that it is in direct contact with the metal substrate, ensuring that there is no gap between the parafilm and the metal substrate. The parafilm is not stretched by external forces to cause observable deformation (such as changes in length, thickness, or surface morphology), even on continuous roll-to-roll equipment.

[0063] The present invention comprehensively considers the surface tension, transmittance, thickness, and other properties of parafilm. Through the method of the present invention, laser processing of a substrate imparts a micro-nano granular surface structure to the parafilm, thereby producing a super-hydrophobic film. This super-hydrophobic film exhibits excellent water resistance and photothermal effects, as well as excellent air permeability, making it widely applicable in various scenarios. Because the parafilm itself is thermoplastic and stretchable, the resulting super-hydrophobic film also exhibits thermoplasticity and stretchability.

[0064] The laser processing technology of the present invention includes nanosecond laser ablation technology, whose most attractive advantage is that it can etch the substrate surface with ultra-high efficiency and easily produce the desired surface morphology by adjusting and optimizing the laser ablation operating parameters such as marking speed, working power, filling spacing, etc.

[0065] In some embodiments, since the parafilm is translucent and is conducive to the penetration of the laser beam, the first laser processing can be performed on the metal substrate from above the parafilm through the parafilm. Figure 7 As shown, when nanosecond laser ablation is performed on a metal substrate through a parafilm film, the high temperature and heat excite particles on the metal substrate's surface from a ground state to a higher state within nanoseconds, imparting ultrahigh energy and high-speed motion to these metal particles. Upon impact with the parafilm surface above, the parafilm's surface decomposes, producing carbon, which is then fused to the thermoplastic parafilm surface. Under a set of laser operating parameters, unique micro-nanostructures are formed at regular intervals. By adjusting and optimizing parameters such as nanosecond laser ablation marking speed, operating power, and laser fill spacing, customized ablation points and lines of varying depths and spacing can be created on the parafilm surface to create a variety of micro-nanostructures.

[0066] In a preferred embodiment, the conditions for nanosecond laser ablation are: laser frequency of 20 kHz, pulse width of 110 ns, laser energy and light intensity of each pulse of 70.28 J / cm 2 and 6.39×10 8 J / cm 2 / s.

[0067] In some specific preferred embodiments, the conditions for nanosecond laser ablation are: scanning speed of 250 mm / s, operating power of 15 W, laser frequency of 20 kHz, pulse width of 110 ns, filling interval of 25 μm, laser energy and light intensity of each pulse of 70.28 J / cm 2 and 6.39×10 8 J / cm 2 / s.

[0068] During the first laser processing of the method of the present invention, the parafilm does not deform as a whole, or does not deform significantly.

[0069] The superhydrophobic parafilm prepared by the method of the present invention exhibits exceptional superhydrophobicity, with an average static contact angle of greater than 150° for a deionized (DI) water droplet of approximately 4 μL. When the surface is slightly tilted at an average tilt angle of no more than 10°, the water droplet easily rolls off the film without leaving any residue, a remarkable phenomenon.

[0070] In other embodiments, the methods of the present invention further comprise subjecting the parafilm to a second laser process to produce a parafilm having a micropore array on its surface. This second laser process involves femtosecond laser drilling, which efficiently customizes and drills micropores to produce a uniformly distributed micropore array. This technology offers significant advantages over traditional physical methods for producing desired membrane pores, including extremely short production times and low costs, and holds great potential for industrial applications and large-scale production for everyday use.

[0071] The parafilm film can be subjected to femtosecond laser drilling from above the parafilm film.

[0072] Preferably, the second laser processing is performed on the parafilm film with micro-nano particles on the surface obtained in step 3). That is, the laser processing of the metal substrate is performed before the laser processing of the parafilm film.

[0073] In a preferred embodiment, the conditions for femtosecond laser drilling are: laser frequency of 5 MHz, pulse width of 300 fs, laser energy and light intensity of each pulse of 0.12 J / cm 2 and 4×10 10 J / cm 2 / s.

[0074] In some specific preferred embodiments, the conditions for femtosecond laser drilling are: drilling speed of 1 mm / s, operating power of 600 W, laser frequency of 5 MHz, step value of 3000, pulse width of 300 fs, laser energy and light intensity of each pulse of 0.12 J / cm 2 and 4×10 10 J / cm 2 / s.

[0075] The present invention uses femtosecond laser drilling technology to drill a uniform micropore array with suitable pore size and distribution on the prepared super-hydrophobic parafilm membrane, thereby obtaining a breathable super-hydrophobic membrane, which is breathable in a simulation experiment of the human body perspiration process at an average relative humidity of about 90%.

[0076] In some embodiments, the surface micro-nanoparticles of the super-hydrophobic film prepared by the method of the present invention include micro-nanoscale protrusions, depressions, air pockets, and one or more combinations thereof, thereby forming a surface roughness structure. Preferably, the average particle size of the micro-nanoscale protrusions, depressions, and air pockets is 1 μm to 50 μm. For example, the micro-nanoscale protrusions, depressions, and air pockets can have various shapes, and their equivalent circular diameters or average particle sizes can be about 1 μm, about 2 μm, about 5 μm, about 10 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, or about 50 μm.

[0077] In other embodiments, the microwell array comprises pores having a diameter of 100 μm to 400 μm. Preferably, the average pore size of the microwell array is 300 μm.

[0078] The overall appearance and surface morphology of the superhydrophobic film are as follows Figure 3 As shown, Figure 3 (a) and (b) show electron micrographs of a super-hydrophobic membrane with a micropore array according to the present invention, which has a uniform micropore array with an average micropore diameter of 300 μm and a spacing of 1.41 mm. The diameters of the individual micropores may vary slightly because the parafilm membrane inevitably undergoes slight deformation due to heat during the laser processing process, and some parts of the parafilm membrane cannot be closely attached to the metal substrate. As a result, during the femtosecond laser drilling process, this part of the parafilm membrane is subjected to defocused (underfocused) laser action. Under fixed laser parameters, holes of different pore sizes may be drilled. The number of such slightly deformed holes is small and does not affect the overall performance of the resulting breathable super-hydrophobic membrane.

[0079] Figure 3 (c) shows a scanning electron micrograph of the superhydrophobic film, showing a unique micro-nanostructure on its surface. Figure 3(d) shows a scanning electron microscope photograph of the superhydrophobic membrane with a micropore array of the present invention. It can be observed that its surface has a unique micro-nano structure and a uniform micropore array. The average diameter of the micropores is 300 μm and the spacing is 1.41 mm.

[0080] The super-hydrophobic film of the present invention is fused with a large amount of carbon produced by the decomposition of the parafilm surface layer, resulting in a uniform black color. This imparts excellent photothermal properties to the film. After 550 seconds of irradiation at one sun intensity using a solar simulator, the average temperature reached approximately 75°C. This property helps protect protective clothing and shoes from rainy weather, keeping them dry and warm.

[0081] In a preferred embodiment, the parafilm and metal substrate are placed on a roll-to-roll machine, and the metal substrate (or subsequently the parafilm) is laser processed. The continuous roll-to-roll manufacturing mode facilitates an automated process, which will significantly increase productivity and enable large-scale production, which is very promising in industry.

[0082] In a preferred embodiment, a 304 stainless steel plate and a parafilm composed of low surface energy paraffin wax and polyolefin are used to fabricate a superhydrophobic membrane having excellent waterproofness and breathability through laser processing.

[0083] In another aspect, the present invention provides a super-hydrophobic film prepared by the method of the present invention, wherein the surface of the super-hydrophobic film has micro-nano particles.

[0084] In some embodiments, the surface micro-nano particles of the super-hydrophobic film of the present invention include micro-nanoscale protrusions, depressions, air pockets, and one or more combinations thereof, thereby forming a surface roughness structure. Preferably, the micro-nanoscale protrusions, depressions, and air pockets are sized from 1 μm to 50 μm. For example, the micro-nanoscale protrusions, depressions, and air pockets may have various shapes, and their average particle size or equivalent circular diameter may be about 1 μm, about 2 μm, about 5 μm, about 10 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, or about 50 μm.

[0085] In other embodiments, the surface of the superhydrophobic membrane further comprises a micropore array. Preferably, the micropore array comprises pores with a diameter of 100 μm to 400 μm; preferably, the average pore diameter of the micropore array is 300 μm.

[0086] According to the method of the present invention, a superhydrophobic film prepared by laser processing based on a high-performance commercially available parafilm film and a metal substrate has excellent superhydrophobicity, air permeability, photothermal effect, anti-corrosive liquid properties, thermoplasticity and stretchability, and is expected to be used as a protective film for laboratory sealing; a protective layer for clothes and shoes used on rainy days to help wearers stay dry and warm; and a precursor material for preparing Janus membranes in scientific research.

[0087] Likewise, aqueous sol microspheres of bacteria / viruses cannot adhere to the super-hydrophobic surface. Therefore, the super-hydrophobic film of the present invention is of great help in daily sterilization and disinfection.

[0088] In addition, the essence of antifouling is to prevent the adsorption of microscopic particles (such as pollutants, water vapor, etc.). Therefore, the super hydrophobic film of the present invention also has potential advantages in anti-fog and even anti-icing, which will effectively improve surface properties and protect equipment used in adverse weather conditions. Figure 8 As shown, the membrane surface has a rough surface morphology and a uniformly distributed micropore array, and water droplets roll on the membrane surface to collect surface pollutants.

[0089] Therefore, another aspect of the present invention provides use of the superhydrophobic film of the present invention for waterproofing, anti-fog, anti-icing, anti-corrosion and / or anti-microbial applications.

[0090] More importantly, the method of the present invention is applicable to a continuous roll-to-roll manufacturing mode, which facilitates the automation process and will significantly improve productivity, which is very promising in industrial large-scale production.

[0091] The present invention is further explained or illustrated below by way of examples, but these examples should not be construed as limiting the scope of protection of the present invention.

[0092] Example

[0093] Unless otherwise specified, the experimental methods used in the following examples were performed using conventional experimental procedures, operations, materials and conditions in the art.

[0094] The materials, reagents and instruments used in the examples are from the following sources:

[0095] Parafilm: Bemis PM-999, manufactured by Bemis, USA, purchased from the Chemical Supply Platform of the Hong Kong University of Science and Technology;

[0096] 304 stainless steel plate: purchased from Guangdong Hongwang New Material Technology Co., Ltd., with a length of 120 mm, a width of 100 mm, and a thickness of 3 mm;

[0097] 1064 nm pulsed laser machine for laser ablation: purchased from Guangdong Han's Yueming Laser Group Co., Ltd.

[0098] 1030 nm femtosecond laser machine for laser drilling: purchased from Wuhan Anyang Laser Technology Co., Ltd.

[0099] Contact angle measuring instrument: purchased from Biolin, model Biolin Theta;

[0100] Industrial electron microscope (EM): purchased from Shenzhen Haiyue Electronics Co., Ltd.

[0101] Scanning electron microscope (SEM): purchased from JEOL Ltd., model JEOL-7100F;

[0102] Waterproof test color-changing test paper: purchased from Shenzhen Chuangbaoda Technology Co., Ltd., the product name is water-changing test paper;

[0103] Beaker: purchased from Breeze Glass Merchants;

[0104] The cast aluminum rollers and accessories were produced by Dongguan Huaying Machinery Equipment Co., Ltd.; the polylactic acid (PLA) and thermoplastic polyurethane (TPU) filaments used for 3D printing of accessories were purchased from Shenzhen Tuozhu Technology Co., Ltd.

[0105] Optical power meter for calculating laser energy and light intensity: purchased from FieldBest;

[0106] High-precision electric linear displacement stage: purchased from Beijing Paidiwei Instrument Co., Ltd., model PDV PP110-30-5040;

[0107] Mobile controller: purchased from Beijing Paidiwei Instrument Co., Ltd., model KZ-100.

[0108] Example 1: Preparation of super-hydrophobic film

[0109] The parafilm film was placed on a 304 stainless steel plate, ensuring direct contact between the parafilm and the plate (i.e., close contact, not adhered). A 1064 nm pulsed laser was used to perform nanosecond laser ablation on the 304 stainless steel substrate from above the parafilm film, through the parafilm itself, to produce a superhydrophobic parafilm film.

[0110] Nanosecond laser ablation operating parameters: scanning speed 250 mm / s, operating power 15 W, laser frequency 20 kHz, pulse width 110 ns, filling interval 25 μm. The laser energy and light intensity per pulse were calculated to be 70.28 J / cm 2 and 6.39×10 8 J / cm2 / s.

[0111] Example 2: Preparation of breathable superhydrophobic membrane

[0112] The super-hydrophobic parafilm prepared in Example 1 was perforated using a 1030 nm femtosecond laser to obtain a breathable super-hydrophobic film.

[0113] Femtosecond laser drilling operating parameters: drilling speed 1mm / s, operating power 600W, laser frequency 5MHz, step value 3000, pulse width 300fs. The laser energy and light intensity of each pulse were calculated to be 0.12J / cm 2 and 4×10 10 J / cm 2 / s.

[0114] The laser processing parameters of the present invention are debugged and optimized to well coordinate the air permeability and super-hydrophobicity of the membrane product.

[0115] Example 3: Study on the properties of superhydrophobic membranes

[0116] During the super-hydrophobic film preparation process, the parafilm is placed on a metal substrate without being attached, leaving the two in close contact. After laser processing, the super-hydrophobic film is peeled off the metal substrate, and the desired material is cut out for property analysis.

[0117] Surface morphology characterization:

[0118] The morphology and structure of the super-hydrophobic films prepared in Example 1 and Example 2 were characterized using an electron microscope (EM) and a JEOL-7100F scanning electron microscope (SEM).

[0119] The results are as follows Figure 3 As shown in the figure, the surface of the super-hydrophobic film prepared by the present invention has a rough, granular surface morphology, including micro-nanoscale protrusions, depressions, and air pockets. These irregular shapes have equivalent circular diameters ranging from 1 μm to 50 μm, with an average diameter of approximately 10 μm. After femtosecond laser drilling, the surface also has a uniform array of micropores with an average pore diameter of approximately 300 μm and a spacing of approximately 1.41 mm.

[0120] Contact angle test:

[0121] Using a contact angle meter, 4 μL of deionized water (DI) droplets were applied at room temperature, and the static and dynamic contact angles were carefully measured to examine the superhydrophobicity of the superhydrophobic films prepared according to the methods of Examples 1 and 2. Figure 4 (a) shows the statistical results of static contact angles of multiple groups of parallel sample tests (average value, n=5), Figure 4(b) shows representative photos of each group of samples to intuitively demonstrate the superhydrophobic performance.

[0122] Taking the lotus leaf (static contact angle 159.29°±3.93°) as a control, the static contact angle of the original parafilm membrane without laser processing was 107.87°±2.12°; the static contact angle of the superhydrophobic membrane prepared in Example 1 was 161.66°±2.02°; and the static contact angle of the breathable superhydrophobic membrane prepared in Example 2 was 159.67°±5.75°.

[0123] The superhydrophobic membranes according to the present invention are also stretchable and maintain good superhydrophobicity after stretching. When the superhydrophobic membranes of Examples 1 and 2 were stretched to twice their original length, the static contact angle of the stretched superhydrophobic membrane of Example 1 was 152.55°±6.59°, while the static contact angle of the stretched breathable superhydrophobic membrane of Example 2 was 147.39°±11.35°.

[0124] Rolling contact angle test:

[0125] At room temperature, the tilt angle required for a 4 μL DI water droplet to roll on the super-hydrophobic film according to the present invention was tested, and the results were as follows: Figure 4 As shown in (e) and (f), a 4 μL DI water droplet slid off the superhydrophobic membrane prepared in Example 1 at a rolling contact angle of 5.29° in 6.48 s; while a 4 μL DI water droplet slid off the breathable superhydrophobic membrane prepared in Example 2 at a rolling contact angle of 3.64° in 3.96 s.

[0126] Meanwhile, the rolling contact angle test on the original parafilm film under the same conditions showed that a 4 μL DI water droplet was firmly fixed on the original parafilm film even when the original parafilm film surface was flipped 180°.

[0127] Figure 4 (g) Statistical results of the average rolling contact angles of the samples are listed (n=5): the average rolling contact angle of the superhydrophobic film prepared in Example 1 is 4.33°±2.39°, and the average rolling contact angle of the breathable superhydrophobic film prepared in Example 2 is 5.81°±2.46°. When the superhydrophobic films of Examples 1 and 2 are stretched to twice their original lengths, the average rolling contact angle of the stretched superhydrophobic film of Example 1 is 8.14°±5.84°, and the rolling contact angle of the stretched breathable superhydrophobic film of Example 2 is 16.12°±4.41°.

[0128] Silver mirror test:

[0129] Excellent superhydrophobicity is usually accompanied by a magical silver mirror effect. Figure 4As shown in (c), when the breathable superhydrophobic membrane prepared in Example 2 is immersed in water, a thin air layer can be clearly observed, thereby confirming the Cassie-Baxter roughness of the membrane surface, achieving superhydrophobicity, and visualizing the micropore array.

[0130] Waterproof test:

[0131] The breathable super-hydrophobic membrane prepared in Example 2 was subjected to a waterproof test. Figure 4 As shown in (d), a color-changing test paper was placed beneath a breathable superhydrophobic membrane within the dotted box. Several water droplets ranging from 10 μL to 100 μL were then placed on the membrane for 30 minutes. The test paper beneath the membrane did not change color upon contact with water, demonstrating that the micro-nanostructure on the membrane effectively prevented water from penetrating and discoloring the test paper.

[0132] Air permeability test:

[0133] The breathable superhydrophobic membrane prepared in Example 2 was subjected to a permeability test using a PDV PP110-30-5040 high-precision electric linear displacement stage and a KZ-100 motion controller.

[0134] In order to test the air permeability of the membrane, a beaker filled with water was placed on a 100°C heating plate, and the unprocessed original parafilm membrane and the breathable superhydrophobic membrane prepared in Example 2 were placed on the beaker respectively, and another beaker was placed on the membrane. The membrane was left to stand for 30 minutes and the water vapor condensation phenomenon was observed. Figure 5 As shown in the two insets in (a), a layer of water droplets forms on the bottom surface of the original parafilm, but there is no water vapor in the beaker above (left inset); in contrast, the entire inner wall of the beaker above the breathable superhydrophobic membrane is covered with water vapor (right inset). This demonstrates that the breathable superhydrophobic membrane of the present invention has excellent water vapor permeability.

[0135] Figure 5 (a) shows a carefully designed human sweating scenario simulation test device to quantitatively study the air permeability of superhydrophobic membranes. The design of the device is based on the human body surface area (BSA) of 1.6m 2 , the surface area of ​​the foot (FSA) is BSA × 3.5%, and the sweat rate of a healthy individual is 0.2 μL / cm 2 / min to 1 μL / cm 2 / min. Figure 5 (b) and (c) show the humidity sensor based on Arduino AHT20, which is used to monitor and record the relative humidity and temperature changes during the whole experiment. Figure 5As shown in (a), the human sweating simulation test setup includes a motorized positioning system, a microfluidics system, a beaker with a breathable superhydrophobic membrane or other material wrapped around the beaker mouth, and an integrated temperature and humidity sensor. A syringe (extrusion device) is mounted on a motorized platform, and the fluid extrusion rate is precisely controlled by adjusting the motor's motion.

[0136] The air permeability of different materials (e.g., black rayon cloth, white rayon cloth, untreated pristine parafilm, and the breathable superhydrophobic membrane prepared in Example 2) was quantitatively evaluated and compared. In experiments with the breathable superhydrophobic membrane prepared in Example 2, the experimental system reached equilibrium between humidity and heat transfer within the first five minutes. As the experiment progressed, liquid began to flow into the beaker. As the evaporation rate increased, the water vapor concentration increased significantly and sought an outlet to dissipate. The only available channel was the upper opening of the beaker, which was completely covered by the breathable superhydrophobic membrane prepared in Example 2. Fluctuating humidity levels were carefully recorded using an Arduino-based humidity sensor. The coordinated interplay between the introduction of fluid and the obstruction of vapor escape through the breathable membrane enabled us to study relative humidity levels to ensure the accuracy and stability of our findings. Experiments with other materials used the same procedures and parameters as above, except that other materials were used to cover the beaker opening.

[0137] like Figure 5 As shown in (d), the test was carried out in ambient air with a humidity of 57.73% and a temperature of 22.96°C. During the initial 5 minutes (stage I), the test system reached a balance between humidity and heat transfer. Subsequently, during the 15-minute test period when the entire device was heated to 37°C (stage II), the relative humidity in the beaker covered with the breathable superhydrophobic film rose to 90.83% ± 3.25%, the relative humidity in the beaker covered with the black rayon cloth was 85.27%, the relative humidity in the beaker covered with the white rayon cloth was 93.62%, and the relative humidity in the beaker covered with the original parafilm was 100%, as shown in Figure 5. Figure 5 As shown in (d) and (e).

[0138] like Figure 5 As shown in (f) and (g), at room temperature, the relative humidity in the beaker covered with the breathable superhydrophobic film was 88.35% ± 3.01%, the relative humidity in the beaker covered with the black rayon cloth was 84.89%, the relative humidity in the beaker covered with the white rayon cloth was 82.85%, and the relative humidity in the beaker covered with the original parafilm was 100%.

[0139] The above results show that the breathable superhydrophobic membrane according to the present invention has acceptable breathability when used as protective clothing.

[0140] Corrosion resistance test:

[0141] The super hydrophobic film of the present invention is not limited to the application of pure water environment, but also has excellent corrosion resistance. Figure 6 As shown in (a), droplets of 1M HCl aqueous solution (pH 0), droplets of 1M KOH aqueous solution (pH 14), and droplets of deionized water (DI water) (pH 7) were respectively placed on the super-hydrophobic film prepared in Example 1. During the 10-minute corrosion resistance test, the appearance and performance of the super-hydrophobic film did not change, indicating that the super-hydrophobic film of the present invention has satisfactory resistance to aqueous corrosive liquids against strong acids of pH 0 and strong bases of pH 14.

[0142] In addition, the corrosion resistance was more comprehensively investigated under long-term exposure and tensile conditions.

[0143] The superhydrophobic film prepared in Example 1 was immersed in 1 M KOH and 1 M HCl aqueous solutions for 20 hours, respectively.

[0144] Figure 9 The results of a long-term corrosion resistance test are shown. Figure 9 (a) shows the initial state of the superhydrophobic film. The left beaker contains 50 mL of a 1 M KOH solution stained with 50 μL of blue dye (purchased from Henan Tanjiao Technology Co., Ltd.); the right beaker contains 50 mL of a 1 M HCl solution stained with 50 μL of red dye (purchased from Henan Tanjiao Technology Co., Ltd.). Before immersion, when water droplets, 1 M KOH droplets, and 1 M HCl droplets were dropped on the superhydrophobic film, the film exhibited excellent superlyophobic properties.

[0145] Figure 9 (b) to (d) show the changes in solution color and membrane wettability during immersion of two superhydrophobic membranes in 1 M KOH (left) and 1 M HCl (right) solutions, respectively. Figure 9 (b) t = 0 hours; Figure 9 (c) t = 6 hours; Figure 9 (d) t = 16 hours. Figure 9(e) shows the final state of two super-hydrophobic films after long-term immersion; the left side is a super-hydrophobic film soaked in 1M KOH solution for 20 hours; the right side is a super-hydrophobic film soaked in 1M HCl solution for 20 hours. After immersing for 20 hours in 1M KOH solution, the super-hydrophobicity of the super-hydrophobic film did not change much, and the static contact angle was about 150 °. The non-immersed area (control) on the super-hydrophobic film maintained its superior super-hydrophobicity. This shows that the super-hydrophobic film of the present invention has corrosion resistance to 1M KOH solution. However, after soaking in 1M HCl solution for 20 hours, the droplets spread on the super-hydrophobic film, indicating that its super-hydrophobicity is greatly reduced. This can be attributed to the strong acid liquid gradually corroding the substrate parafilm film and destroying the film performance. The super-hydrophobicity of the non-immersed area (control) on the super-hydrophobic film is also affected by the high volatility of the HCl solution, which makes the rolling property of the droplets on the film surface worse. HCl vapor permeates the micro-nanostructure, altering the membrane surface's superhydrophobic structure, similar to the Cassie-Baxter model (a model and theoretical basis proposed by scientists Cassie and Baxter). This suggests that while the superhydrophobic membrane of the present invention exhibits good corrosion resistance to a 1M HCl solution for a short period of time, it struggles to maintain this resistance over extended periods.

[0146] In addition, the super-hydrophobicity of the super-hydrophobic film of the present invention in a stretched state was also studied. The super-hydrophobic film prepared in Example 1 was stretched to 5 times its original length and then tested. Figure 10 Shown are the corrosion resistance results of the superhydrophobic film when stretched to 5 times its original length. Figure 10 (a) shows an elongated superhydrophobic film immersed in deionized water for 10 min; Figure 10 (b) shows photos of droplets placed on an elongated superhydrophobic film taken at different angles (the droplet residence time is about 10 minutes), where the red droplets are droplets of 1M HCl aqueous solution (pH 0), the blue droplets are droplets of 1M KOH aqueous solution (pH 14), and the colorless droplets are droplets of deionized water (DI water) (pH 7).

[0147] like Figure 10 As shown in Figure 2, the superhydrophobic film stretched to 5 times its original length is resistant to corrosion by 1M KOH solution. Figure 9 Similarly, when the immersion time was extended to 20 h, the 1 M HCl solution gradually corroded the elongated superhydrophobic film and damaged its performance, causing it to lose its superhydrophobicity during long-term immersion in the HCl solution.

[0148] Photothermal test:

[0149] Since the super-hydrophobic film according to the present invention has a uniform black color, the photothermal effect was also studied. The super-hydrophobic film prepared in Example 1 and the original parafilm film were placed in a solar simulator (purchased from Oriel Sol3A, Newport, 1 kW / m 2 ) for 550 seconds, and the real-time data was measured by thermocouples and presented as a continuous temperature-time curve ( Figure 6 (b)). Figure 6 As shown in (b), during the process, the maximum temperature of the superhydrophobic film was 76.63±1.66℃, and the average temperature was about 75℃; under the same experimental conditions, the maximum temperature of the original parafilm was 39.53±2.14℃, and that of air was 30.23±1.45℃.

[0150] Figure 6 (c) and (d) show the corresponding Figure 6 (b) Thermal imaging of the sample. Figure 6 As shown in (c), the super-hydrophobic film of the present invention showed a maximum temperature of 77.34°C and an average temperature of 74.45°C after the above-mentioned illumination test; in comparison, Figure 6 (d) shows that the average temperature of the original parafilm is 38.51°C (wherein the maximum temperature of 52.61°C is the highest temperature measured within the large rectangular range and does not represent the maximum temperature of the original parafilm).

[0151] Example 4: Roll-to-roll manufacturing of superhydrophobic films

[0152] The super-hydrophobic film according to the present invention is automatically produced using a self-developed roll-to-roll manufacturing machine equipped with two different power systems for nanosecond laser ablation and femtosecond laser drilling.

[0153] In the continuous roll-to-roll preparation process, the rollers of the roll-to-roll devices at the left and right ends of the laser processing area are lower than the processing platform where the parafilm and metal substrate are located. The parafilm film before and after processing is respectively transferred over the top of the two rollers to achieve transmission, while ensuring that the parafilm film is in close contact with the metal substrate.

[0154] like Figure 7 As shown in the figure, in the coordinated working mode of the laser machine and the roll-to-roll machine, continuous material transportation, direct laser processing and automated film manufacturing can be achieved. Through the two-phase stepper motor electrically connected to the reserved rotary axis port and operated by the laser control software, the roll-to-roll machine works in conjunction with the ablation nanosecond laser machine with rotary segmentation marking function (such as Figure 7 system shown on the left) to prepare superhydrophobic membranes.

[0155] Furthermore, the super-hydrophobic film prepared above can be transported to a roll-to-roll femtosecond laser drilling process (e.g. Figure 7 In the system shown on the right, micropore array drilling is performed continuously, thereby enabling continuous production and simultaneous collection of breathable superhydrophobic membranes. Figure 7 The entire manufacturing process is shown.

[0156] The roll-to-roll manufacturing process and equipment shown in this embodiment are an illustrative example, intended to illustrate that the preparation method of the superhydrophobic membrane and breathable superhydrophobic membrane of the present invention is suitable for roll-to-roll continuous manufacturing on suitable roll-to-roll manufacturing equipment.

Claims

1. A method for preparing a super-hydrophobic film, comprising the following steps: 1) Providing a parafilm membrane; 2) placing the film on a metal substrate so as to be in direct contact with the metal substrate; and 3) performing a first laser processing on the metal substrate to obtain a parafilm having micro-nano particles on the surface.

2. The method according to claim 1, wherein the room temperature thermal conductivity of the metal substrate is 15W / (m·K) to 200W / (m·K), and the thermal expansion coefficient is 15×10 -6 / ℃ to 30×10 -6 / ℃, Brinell hardness is 20HBW to 300HBW.

3. The method according to claim 1, wherein the metal substrate is selected from the group consisting of a stainless steel plate, a zinc plate, and an aluminum plate. 4 . The method according to claim 1 , wherein the thickness of the metal substrate is 1 mm to 5 mm; preferably, the thickness of the metal substrate is 3 mm. 5 . The method according to claim 1 , wherein the first laser processing comprises nanosecond laser ablation; preferably, the nanosecond laser ablation is performed on the metal substrate from above the parafilm through the parafilm.

6. The method according to claim 5, wherein the conditions of the nanosecond laser ablation are: laser frequency of 20 kHz, pulse width of 110 ns, laser energy and light intensity of each pulse of 70.28 J / cm 2 and 6.39×10 8 J / cm 2 / s.

7. The method according to claim 1, further comprising performing a second laser processing on the parafilm to obtain a parafilm having a micropore array on its surface.

8. The method according to claim 7, wherein the second laser processing comprises femtosecond laser drilling; preferably, the femtosecond laser drilling is performed on the parafilm film from above; preferably, the second laser processing is performed on the parafilm film having micro-nanoparticles on the surface obtained in step 3).

9. The method according to claim 8, wherein the conditions of the femtosecond laser drilling are: laser frequency of 5 MHz, pulse width of 300 fs, laser energy and light intensity of each pulse of 0.12 J / cm 2 and 4×10 10 J / cm 2 / s. 10 . The method according to claim 1 , wherein the parafilm and the metal substrate are placed on a roll-to-roll device, and the first laser processing is performed on the metal substrate.

11. The method of claim 7, wherein the parafilm is placed on a roll-to-roll device and the second laser processing is performed on the parafilm. 12 . The method according to claim 1 , wherein the micro-nano particles comprise micro-nano-scale protrusions, depressions, air pockets, and a combination of one or more thereof. 13 . The method according to claim 12 , wherein the average particle size of the micro-nano-scale protrusions, depressions and air pockets is 1 μm to 50 μm.

14. The method according to claim 7, wherein the micropore array comprises pores with a diameter of 100 μm to 400 μm; preferably, the average pore diameter of the micropore array is 300 μm.

15. A super-hydrophobic film prepared according to the method described in any one of claims 1 to 14.

16. The super-hydrophobic film according to claim 15, wherein the surface of the super-hydrophobic film has micro-nano particles, and the micro-nano particles include micro-nano-scale protrusions, depressions, air pockets, and one or more combinations thereof; preferably, the surface of the super-hydrophobic film also has a micropore array.

17. The superhydrophobic film according to claim 15, wherein the average particle size of the micro-nanoscale protrusions, depressions and air pockets is 1 μm to 50 μm; preferably, the micropore array comprises pores with a diameter of 100 μm to 400 μm; preferably, the average pore size of the micropore array is 300 μm.

18. Application of the superhydrophobic film according to any one of claims 15 to 17 for waterproofing, anti-fogging, anti-icing, anti-corrosion and / or anti-microbial use.

19. The use according to claim 18, wherein the superhydrophobic film is used to prepare a sealing protective film, a protective layer for clothes or shoes, or a precursor material for a Janus film.

Images