Bionic self-adaptive compression-resistant super-hydrophobic surface and preparation method thereof

Abstract

The application provides a kind of bionic self-adaptive compression-resistant super-hydrophobic surface and a preparation method, comprising microstructure with flexible tip. Based on the technical scheme of the application, when water pressure increases, the super-hydrophobic surface with microstructure can realize self-adaptive bending deformation, form a continuous and stable air layer, increase the solid-liquid contact area, and enhance the compression-resistant performance of the super-hydrophobic surface.

Description

Technical Field

[0001] This invention relates to the field of pressure-resistant superhydrophobic surface technology, and particularly to a biomimetic adaptive pressure-resistant superhydrophobic surface and its preparation method. Background Technology

[0002] Superhydrophobic surfaces, due to their low solid-liquid adhesion and water repulsion properties, are widely used in fluid drag reduction and surface antifouling. Generally, low surface energy micro / nano structures achieve a stable Cassie-Baxter wetting state by trapping gas layers and repelling liquids, reducing solid-liquid contact and thus decreasing adhesion, allowing droplets to roll off. While reducing the solid-liquid contact area typically improves hydrophobicity, it also reduces the surface's resistance to liquid penetration. When the liquid environment around the surface becomes harsh (e.g., increased pressure, environmental disturbances, impacts), liquid "piercing" becomes more likely, causing the gas-liquid interface to become unstable and irreversibly transforming the Cassie-Baxter state into the Wenzel state, completely losing its superhydrophobic properties. Theoretically, simultaneously achieving high hydrophobicity and compressive strength is contradictory in traditional surface design; reducing the solid-liquid contact area can achieve higher hydrophobicity, but inevitably reduces compressive strength. Therefore, it is of great significance to construct an adaptive pressure-resistant superhydrophobic surface that reduces the solid-liquid contact area when liquid repellency is required and increases the contact area when pressure resistance is required.

[0003] In nature, water hyacinths can float stably on water for extended periods. Their leaves are covered with soft, downy hairs on both the surface and back, exhibiting a segmented, monoconcave structure that gradually decreases in size from bottom to top. Underwater, the leaves display a silvery, mirror-like reflection, demonstrating superhydrophobic properties. Tests have revealed that water hyacinths possess extremely high water pressure resistance, reaching 500-700 kPa. This is attributed to the fact that when subjected to significant water pressure underwater, the hairs bend and deform, overlapping each other to greatly increase the solid-liquid contact area, maintain air-layer stability, and enhance the pressure resistance of the leaf's superhydrophobic structure. This biosurface, which automatically adjusts its solid-liquid contact area to regulate hydrophobicity and pressure resistance according to changes in external pressure, provides a new approach for the design of adaptive pressure-resistant superhydrophobic surfaces. Summary of the Invention

[0004] To address the problems in the prior art, this application proposes a biomimetic adaptive pressure-resistant superhydrophobic surface, comprising a microstructure with a flexible tip. When the water pressure increases, the microstructure can adaptively bend, increasing the solid-liquid contact area of ​​the microstructure and enhancing its pressure resistance. By trapping a large amount of air to form an air film, it achieves drag reduction. The superhydrophobic surface has a low solid-liquid contact area with water, which can significantly reduce liquid adhesion.

[0005] Preferably, the diameter of the microstructure decreases gradually at the bottom, middle and top. When the water pressure increases to a certain extent, the microstructure overlaps with the adjacent structure in the pre-tilting direction to form a continuous and stable air layer.

[0006] Preferably, the height of the microstructure is 1-3000 μm, the cone tilt angle is 30-90°, and the structural spacing is 1-1000 μm.

[0007] A method for preparing a biomimetic adaptive pressure-resistant superhydrophobic surface involves using a high-precision printing system to print a biomimetic structure array. The printed array is then activated in a plasma cleaner to generate hydroxyl groups on its surface. Next, it is placed in a vacuum oven containing perfluorooctyltrichlorosilane and evacuated to achieve fluorination. PDMS prepolymer and crosslinking agent are weighed, mixed, and stirred until homogeneous. The mixture is then evacuated to remove air bubbles. The fluorinated biomimetic structure array is then taped to the center of a substrate. The de-bubbled PDMS solution is poured onto the biomimetic structure array template. After standing, the mixture is evacuated again to further remove air bubbles. After curing in an oven, the negative template is peeled off. The negative template undergoes the same fluorination treatment. PDMS polymer and crosslinking agent are weighed, mixed, and stirred until homogeneous. After removing air bubbles under vacuum, the mixture is poured onto the negative template, allowed to stand, and then evacuated a second time. After curing in an oven, the negative template is peeled off to obtain the biomimetic adaptive pressure-resistant superhydrophobic surface.

[0008] Preferably, fluorination and alkylation are used to reduce the surface energy of the structural array, thereby preparing a biomimetic adaptive pressure-resistant superhydrophobic surface with enhanced pressure resistance.

[0009] Preferably, after the biomimetic structure array is fluorinated and a negative template is prepared, a rigid superhydrophobic surface is prepared using epoxy resin. First, the epoxy resin adhesive of component A is weighed, then the epoxy resin adhesive of component B is weighed and stirred evenly. After being placed in a vacuum chamber to remove air bubbles, it is poured onto the negative template. After standing and being vacuumed a second time, it is placed in an oven to cure and then peeled off from the negative template to obtain the surface of the rigid superhydrophobic structure array.

[0010] Preferably, silica is prepared into an ethanol solution, and then perfluorodecyltrichlorosilane is added for modification. The mixture is stirred at room temperature to form a mixture. The treated mixture is then sprayed onto the surface of the prepared rigid superhydrophobic structure array. After fluorination, a rigid superhydrophobic structure array surface with enhanced compressive strength is prepared.

[0011] The above-mentioned technical features can be combined in various suitable ways or replaced by equivalent technical features, as long as the purpose of the present invention can be achieved.

[0012] The biomimetic adaptive pressure-resistant superhydrophobic surface and its preparation method provided by this invention have at least the following advantages compared with the prior art:

[0013] When a superhydrophobic surface is subjected to water pressure, the structure bends and deforms, the solid-liquid contact area increases, and the stability of the solid-liquid interface increases, thereby increasing the pressure resistance of the pressure-adaptive superhydrophobic surface. Attached Figure Description

[0014] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0015] Figure 1 This is a SEM image of the microstructure of the biomimetic adaptive pressure-resistant superhydrophobic surface of the present invention.

[0016] Figure 2 This refers to the water contact angle of the biomimetic adaptive pressure-resistant superhydrophobic surface of the present invention.

[0017] Figure 3 This refers to the water contact angle of the rigid conical superhydrophobic surface of the present invention.

[0018] Figure 4 This is a design diagram of the biomimetic adaptive pressure-resistant superhydrophobic structure of the present invention;

[0019] Figure 5 This is a SEM image of the biomimetic adaptive compressive superhydrophobic structure of the present invention;

[0020] Figure 6 This is a schematic diagram illustrating the compressive strength of the biomimetic adaptive compressive superhydrophobic surface of the present invention. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] This invention provides a method for preparing a pressure-adaptive superhydrophobic surface: as follows Figure 1-3As shown, a biomimetic structural array template with a height of 400 μm, an inclination angle of 75°, and a structural spacing of 100 μm was designed. The diameters of the base, middle, and top surfaces of the inclined cones are 100 μm, 50 μm, and 10 μm, respectively. The designed biomimetic structural array was printed using a high-precision nanoArch S130 printing system. The printing material was a light yellow HTL resin with a curing wavelength of 405 nm, and the printing area was 8 mm × 7 mm. The printed biomimetic structural array was placed in a plasma cleaner (Plasma, 30W) for 10 min to activate it with oxygen plasma, generating hydroxyl groups on the surface. Then, it was placed in a vacuum oven containing 200 μL of perfluorooctyltrichlorosilane (in a 20 mL open glass bottle) and sealed under vacuum at 60°C for 2 h to achieve fluorination treatment. 10 g of PDMS prepolymer and 1 g of crosslinking agent were weighed, mixed thoroughly, and placed in a vacuum chamber for 10 min to remove air bubbles. The fluorinated biomimetic structure array was attached to the center of a 4cm×4cm aluminum substrate using 3M tape, and a 4mm thick rubber gasket was placed on the aluminum substrate. A degassed PDMS mixture was poured onto the biomimetic structure array template with the silicone gasket. After standing at room temperature for 10 minutes, a vacuum was applied for 10 minutes to further remove air bubbles from the PDMS mixture. The mixture was then cured in an 80℃ oven for 2 hours and peeled off from the positive template to obtain the negative template of the biomimetic structure array. The negative template underwent the same fluorination treatment as described above. 5g of PDMS polymer and 1g of crosslinking agent were weighed, mixed thoroughly, and vacuum-removed of air bubbles. This mixture was then poured onto the negative template, allowed to stand, and vacuumed again. The mixture was then cured in an 80℃ oven for 2 hours and peeled off from the negative template to obtain the adaptive pressure-resistant superhydrophobic surface.

[0023] To increase the hydrophobicity of the structural array, fluorination and alkylation were used to reduce the surface energy of the structural array, thus preparing a biomimetic adaptive pressure-resistant superhydrophobic surface with enhanced compressive strength.

[0024] In one embodiment, after the biomimetic structure array undergoes the same fluorination treatment and negative template preparation as described above, a rigid superhydrophobic surface is prepared using epoxy resin. First, 3g of component A epoxy resin adhesive is weighed, and then 1g of component B epoxy resin adhesive is weighed and stirred evenly. After being placed in a vacuum chamber to remove air bubbles, it is poured onto the negative template, left to stand, and then vacuumed again. After being placed in an 80°C oven to cure for 2 hours, it is peeled off from the negative template to obtain the surface of the rigid superhydrophobic structure array.

[0025] To further enhance the hydrophobic properties of the aforementioned structural array surface, a 20 nm diameter silica solution was prepared in ethanol at a concentration of 20 mg / mL. Then, 400 μL of perfluorodecyltrichlorosilane was added for modification, and the solution was mechanically stirred at 500 rpm / min for 2 hours at room temperature. The treated solution was then sprayed onto the prepared rigid superhydrophobic structural array surface. The specific spraying parameters and procedures were as follows: the air compressor pressure was adjusted to 0.4 MPa, the spray gun flow rate was 2 mL / min, the spraying distance was 10 cm, and the surface was sprayed vertically and uniformly for a certain period of time. After standing for approximately 3 minutes, the surface was placed in a 60°C oven for curing for 2 hours. The resulting rigid superhydrophobic structural array surface with enhanced compressive strength was then prepared using the aforementioned fluorination method.

[0026] In one embodiment, a 10mm×10mm biomimetic structure array was 3D printed. A 10mm×10mm biomimetic structure array patch was prepared using the same preparation method as in Case 1. A silica coating was deposited on the surface of the biomimetic structure array and then fluorinated using the modification method described in Case 2 to enhance surface hydrophobicity. The modified adaptive pressure-resistant superhydrophobic patch had a water contact angle of 160° and a roll-off angle of 1.5°. Multiple modified superhydrophobic patches were adhered to the bottom of a remote-controlled amphibious aircraft model using epoxy resin adhesive. The amphibious aircraft's water gliding speed was calculated by measuring the total distance and time of movement. Tests showed that the amphibious aircraft with the adaptive pressure-resistant superhydrophobic structure on its bottom had an average gliding speed of 38cm / s, while the untreated amphibious aircraft had an average gliding speed of 17cm / s. This comparison showed that applying the adaptive pressure-resistant superhydrophobic surface to the aircraft bottom increased the gliding speed by approximately 25%, achieving drag reduction during water gliding. Furthermore, the total time taken for the test aircraft to break free from the water surface from a standstill was 20% shorter compared to an amphibious aircraft with an untreated bottom. This is because the air layer captured by the adaptive pressure-resistant superhydrophobic surface reduces drag when the amphibious aircraft is gliding on the water; the low solid-liquid adhesion of the superhydrophobic surface reduces the water's binding force on the aircraft during takeoff; and as the pressure decreases, the solid-liquid contact area of ​​the adaptive pressure-resistant superhydrophobic surface is further reduced, further decreasing the adhesion between the aircraft's bottom and the water surface, which is more conducive to the amphibious aircraft taking off from the water.

[0027] In one embodiment, the diameter of the superhydrophobic structure decreases progressively from the bottom to the middle and top, with the bottom column diameter being significantly larger than the top diameter, to prevent bending deformation of the bottom structure and allow for bending deformation of the top structure. Figure 4-5 Furthermore, under underwater pressurization, the structure overlaps with adjacent structures in the pre-tilting direction, forming a continuous and stable air layer, such as... Figure 6As shown. The main purpose of the superhydrophobic structure in this application is to enhance the water pressure resistance of the superhydrophobic surface. When the pressure increases, the structure achieves adaptive bending deformation, thereby increasing the solid-liquid contact area and enhancing the water pressure resistance of the structure.

[0028] In one embodiment, the specific parameters of the superhydrophobic structure are: the height of the microstructure is 1-3000 μm, the cone tilt angle is 30-90°, and the structural spacing is 1-1000 μm.

[0029] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A biomimetic self-adaptive pressure-resistant superhydrophobic surface, characterized in that, The microstructure with a flexible tip has a height of 1-3000 mu m, a taper inclination angle of 30-90 degrees, and a structure spacing of 1-1000 mu m, and when the water pressure increases, the microstructure can realize self-adaptive bending, so that the solid-liquid contact area of the microstructure is increased, and the pressure resistance of the microstructure is enhanced, and when the water pressure increases to a certain extent, the microstructure bends to a pre-inclined direction, forming a continuous and stable air layer; the solid-liquid contact area of the super-hydrophobic surface with water is low, and the liquid adhesion can be greatly reduced.

2. The method of producing a biomimetic self-adapting pressure-resistant superhydrophobic surface according to claim 1, characterized in that, A 3D printing system is used to print a biomimetic structure array as a positive template, and a negative template of the biomimetic structure array is obtained after the positive template is removed by using an organic silicone resin or a photosensitive resin material for replication, and the negative template is subjected to secondary replication by using the organic silicone resin or the photosensitive resin material, and the negative template is removed to obtain the biomimetic self-adaptive pressure-resistant structure array.

3. The production method according to claim 2, characterized by, The surface energy of the structure array is reduced by fluorination and alkylation treatment, and a biomimetic self-adaptive pressure-resistant super-hydrophobic surface with enhanced pressure resistance is prepared.

4. The production method according to claim 2, characterized by, After the biomimetic structure array is subjected to fluorination, alkylation treatment and negative template preparation, a rigid super-hydrophobic surface is prepared by using an epoxy resin, A component epoxy resin glue is weighed, B component epoxy resin glue is weighed, stirred and mixed uniformly, and then poured on the negative template after removing air bubbles by vacuumizing in a vacuum device, and then placed and vacuumized again, and then placed in an oven for curing, and then torn off from the negative template to obtain the rigid super-hydrophobic structure array surface.

5. The production method according to claim 4, characterized by, Hydrophobic silicon dioxide, titanium dioxide and aluminum oxide nanoparticles are configured into a solution, and the treated mixed solution is sprayed or dip-coated on the prepared super-hydrophobic structure array surface to prepare a super-hydrophobic structure array surface with enhanced pressure resistance.

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