Underwater super-hydrophobic surface micro-nano composite structure with resistance to condensation failure and preparation method thereof

Abstract

A micro-nano composite structure and preparation method for an underwater super-hydrophobic surface that resists condensation failure, a preparation method for an underwater super-hydrophobic surface that enables condensed water to be actively and promptly discharged through the synergistic effect between micro-nano structures, and the super-hydrophobic surface can be used for a long time underwater in the presence of a temperature difference. The preparation method comprises the following steps: (1) preparation of a micron structure; (2) preparation of a nanostructure; (3) coordinated preparation of a micro-nano composite structure; (4) preparation of a micro-nano composite super-hydrophobic structure; and (5) preparation of a hydrophobic micro-nano composite structure surface. The present invention reduces the adhesion of condensed droplets within the micro-structure by composite conical or fractal nanostructures within a micro-cavity; utilizes a biomimetic continuous hydrophobic micro-structure to provide a stable gas-liquid interface and sufficient cavitation to prevent the overall failure of the surface super-hydrophobicity caused by the failure of a single cavity; and utilizes the synergistic effect with the micro-cavity structure to quickly discharge the accumulated condensed water.

Description

Technical Field

[0001] The present invention relates to the technical field of super-hydrophobic materials, and in particular to an underwater super-hydrophobic surface micro-nano composite structure that resists condensation failure and a preparation method thereof. Background Art

[0002] Superhydrophobic surfaces are gaining increasing attention due to their excellent performance in anti-fouling, anti-metal corrosion and marine bioadhesion, fluid pipeline drag reduction, chemical heat and mass transfer, and biomedicine. The key to constructing superhydrophobic surfaces lies in the design of micro-nano structures and the use of low surface energy materials. The micro-nano structure provides a confined space for the superhydrophobic surface to lock air, while the low surface energy material prevents the liquid from infiltrating into the interior of the structure. Due to the presence of the micro-nano structure, the superhydrophobic surface can maintain a large proportion of the gas-liquid interface, so that the fluid has excellent fluidity on the surface. However, due to the presence of many external factors such as pressure, this gas layer within the structure is often unstable, which in turn limits the application of superhydrophobic surfaces in actual working conditions. As for the thermodynamic stability of the gas layer (the gas layer is replaced by water), current research is still insufficient. Superhydrophobic surfaces have promising applications in heat and mass transfer in air. However, in many applications, particularly underwater systems, the thermodynamic instability of the air layer severely limits their useful lifespan. Steam condensation, a typical phase change process, is a common phenomenon in nature and industrial production. When superhydrophobic surfaces are used underwater, condensation is unavoidable within the high humidity structures.

[0003] In recent years, efforts have focused on improving the stability of the gas-liquid interface by constructing multi-level structures or by controlling the gas saturation of the aqueous phase to limit gas diffusion within the gas layer. However, these approaches only work for maintaining stability from the outside in at the gas-liquid interface and are unable to combat the instability of the gas layer from the inside out, caused by condensation within underwater superhydrophobic surface structures.

[0004] The above shows that underwater super-hydrophobic surfaces often lose their super-hydrophobic properties due to the condensation of water vapor in their micro-nanostructures, triggering the escape of the air layer. In this way, the surface loses its super-hydrophobic properties due to infiltration. In underwater environments, a new design is needed to actively transport the condensed droplets out, thereby ensuring the long-term usability of the super-hydrophobic surface. Summary of the Invention

[0005] In response to the problems in the above-mentioned prior art, the present application proposes an underwater super-hydrophobic surface micro-nano composite structure that is resistant to condensation failure, which includes a microstructure and a nanostructure on a substrate, wherein the inclination angle of the microstructure is 30 to 70°; the width of the microstructure is 30 to 250 μm; the nanostructure is located on the surface of the microstructure, and the particle size of the nanostructure is 10 to 80 nm; the spacing is 30 to 60 nm; the depth is 90 to 180 nm; the microstructure and the nanostructure form a micro-nano composite structure, and the thickness of the nanostructure is 5 to 20 μm.

[0006] Preferably, the microstructure includes at least one of an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, and a strip structure having a certain inclination angle, depth, and width.

[0007] Preferably, the substrate comprises at least one of metal, alloy, silicon wafer, or glass.

[0008] Preferably, when the cross-section of the inverted quadrangular pyramid structure is a trapezoid, the length of the lower base of the trapezoid is half the length of the upper base.

[0009] Preferably, the top of the single concave structure of the microstructure has a protrusion for limiting the position of the nanostructure.

[0010] Preferably, the width of the ridge is the same as the thickness of the nanostructures on the sides of the microstructures.

[0011] The present application also relates to a method for preparing an underwater super-hydrophobic surface micro-nano composite structure that resists condensation failure, comprising the following steps:

[0012] S1. Using soft material replication or etching technology, an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, or a strip structure with a certain tilt angle, depth, and width is prepared on a substrate to form a microstructure;

[0013] S2. Using selected polymers or inorganic particles of different shapes as building blocks of nanostructures, conical, sheet-shaped, or fractal nanostructures of a certain height, particle size, and spacing are prepared on the surface of the microstructure by spraying, chemical vapor deposition, evaporation, chemical oxidation, or ion beam etching; the nanostructures and microstructures form a micro-nano composite surface;

[0014] S3, immersing the micro-nano composite surface in an ethanol solution of perfluorododecyl mercaptan for a period of time, taking it out and rinsing it with deionized water, and drying it with nitrogen gas;

[0015] S4. Use a blade to scrape the micro-nano composite surface back and forth, and then rub it back and forth with a large molecular weight hydrophilic polyethylene glycol solid to obtain a surface with an affinity-repellency micro-nano composite structure.

[0016] Preferably, the ion beam etching step includes: ultrasonically cleaning the finely polished metal sample in acetone, then placing it on an electric transfer stage, and performing surface etching using a picosecond laser system; ultrasonically cleaning the finely polished metal sample in acetone, then placing it on an electric transfer stage, and performing surface etching using a picosecond laser system; the central wavelength of the laser pulse is 1064nm, the repetition frequency is 597.44kHz, and the maximum power is 65.4W; the laser beam scanning trajectory is controlled by programming, and the scanning is repeated at a speed of 3m / s; the laser beam is focused using a 100mm field lens, and the laser spot diameter is approximately 30μm.

[0017] Preferably, the step of chemical oxidation includes: placing the sample in a tubular furnace to grow nanowires on the surface of the prepared microstructure; the tubular furnace is programmed to heat at a heating rate of 3°C / min and then stabilized at 480±5°C for 2 hours; the quartz tube of the tubular furnace is open to the laboratory atmosphere to allow the sample to oxidize in fixed air; after the heat treatment is completed, the furnace temperature is turned off and the sample is taken out when the furnace temperature drops below 30°C.

[0018] Preferably, the chemical vapor deposition step includes: using candle ash nanoparticles to prepare conical or fractal nanostructures of a certain height, particle size, and spacing on the surface of the microstructure by a chemical vapor deposition method; wherein the particle size of the nanostructure is 10 to 80 nm; the spacing is 30 to 60 nm; the depth is 90 to 180 nm; and the coordination of the micro-nano composite structure lies in the thickness of the nanostructure being 5 to 20 μm.

[0019] The above 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.

[0020] The underwater super-hydrophobic surface micro-nano composite structure and preparation method thereof provided by the present invention have at least the following beneficial effects compared with the prior art:

[0021] 1. The main function of the micron structure is to provide a stable gas-liquid interface and gas layer. At the same time, the appropriately sized micron structure is conducive to the timely contact of the merged condensed droplets with the gas-liquid interface and rapid discharge.

[0022] 2. The main function of the nanostructure is to control the nucleation and growth process of the condensation droplets, and to make the condensation droplets stay only on the top of the structure after growing, so that they maintain a stable Cassie state and low adhesion properties.

[0023] 3. By compounding conical, sheet-shaped or fractal nanostructures within the microcavity, the adhesion of condensation droplets within the microstructure is reduced; a biomimetic continuous hydrophobic microstructure is used to provide a stable gas-liquid interface and sufficient air pockets to prevent the overall failure of the surface superhydrophobicity caused by the failure of a single cavity; and the synergistic effect with the microcavity structure is used to quickly discharge the accumulated condensed water. A method for preparing a micro-nano composite structure surface that resists the instability of the air layer from the inside out caused by condensation within the underwater superhydrophobic surface structure is proposed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0025] Figure 1 Schematic diagram of the side structure of the micro-nano composite super-hydrophobic surface;

[0026] Figure 2 This is the SEM image of the micro-nano composite super-hydrophobic surface;

[0027] Figure 3 Schematic diagram of the changes in the gas-liquid interface, gas layer detachment, and droplet discharge caused by condensation within microstructures and micro-nano composite superhydrophobic surface structures;

[0028] Figure 4 This is a metallographic microscope image of a silicon-based inverted square pyramid with microstructure;

[0029] Figure 5 Schematic diagram of the contact angle of microstructured hydrophobic surface and micro-nano composite structure superhydrophobic surface;

[0030] Figure 6 It is the accumulation and discharge phenomenon of condensed water in the superhydrophobic surface structure and the gas-liquid interface. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] The present invention provides an underwater super-hydrophobic surface micro-nano composite structure that is resistant to condensation failure. The substrate comprises a microstructure and a nanostructure, wherein the inclination angle of the microstructure is 30 to 70°; the width of the microstructure is 30 to 250 μm; the nanostructure is located on the surface of the microstructure, and the particle size of the nanostructure is 10 to 80 nm; the spacing is 30 to 60 nm; the depth is 90 to 180 nm; the microstructure and the nanostructure form a micro-nano composite structure, and the thickness of the nanostructure is 5 to 20 μm.

[0033] The present application also provides a method for preparing an underwater super-hydrophobic surface micro-nano composite structure that resists condensation failure, comprising the following steps:

[0034] S1. Using soft material replication or etching technology, an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, or a strip structure with a certain tilt angle, depth, and width is prepared on a substrate to form a microstructure;

[0035] S2. Using selected polymers or inorganic particles of different shapes as building blocks of nanostructures, conical, sheet-shaped, or fractal nanostructures of a certain height, particle size, and spacing are prepared on the surface of the microstructure by spraying, chemical vapor deposition, evaporation, chemical oxidation, or ion beam etching; the nanostructures and microstructures form a micro-nano composite surface;

[0036] S3, immersing the micro-nano composite surface in an ethanol solution of perfluorododecyl mercaptan for a period of time, taking it out and rinsing it with deionized water, and drying it with nitrogen gas;

[0037] S4. Use a blade to scrape the micro-nano composite surface back and forth, and then rub it back and forth with a large molecular weight hydrophilic polyethylene glycol solid to obtain a surface with an affinity-repellency micro-nano composite structure.

[0038] In one embodiment, a metal sheet is laser etched to obtain a microstructure having a certain tilt angle, depth, and width. The microstructure includes an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, and / or a stripe structure.

[0039] In one embodiment, conical nanostructures of certain height, size, and spacing are prepared on different surfaces of the microstructure by ion beam etching;

[0040] The particle size of the nanostructure is 10 to 80 nm; the spacing is 30 to 60 nm; the depth is 90 to 180 nm; and the coordination of the micro-nano composite structure lies in the thickness of the nanostructure being 5 to 20 μm.

[0041] In one embodiment, the obtained micro-nano composite surface is immersed in an ethanol solution of perfluorododecyl mercaptan for a period of time, taken out and rinsed with deionized water, and dried with nitrogen gas;

[0042] Specifically, the prepared surface is placed in a plasma cleaner for cleaning for 10 to 15 minutes; the concentration of the perfluorododecanethiol ethanol solution is 10 mol / L, and the immersion time is 3 days.

[0043] In one embodiment, the obtained surface is scraped back and forth 5 to 8 times using a blade, and then rubbed back and forth 5 to 8 times with a large molecular weight hydrophilic polyethylene glycol solid to obtain a surface with an affinity-repellency micro-nano composite structure.

[0044] In one embodiment, a metal sheet is laser-etched to obtain an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, or a strip structure having a certain tilt angle, depth, and width.

[0045] The inclination angle of the microstructure is 30 to 70 degrees; the depth is half of the depth of the overall structure after the angle of the microstructure is determined; and the width of the microstructure is 30 to 250 μm.

[0046] In one embodiment, candle ash nanoparticles are used to prepare conical or fractal nanostructures of a certain height, particle size, and spacing on the surface of the microstructure by chemical vapor deposition;

[0047] The particle size of the nanostructure is 10 to 80 nm; the spacing is 30 to 60 nm; the depth is 90 to 180 nm; and the coordination of the micro-nano composite structure lies in the thickness of the nanostructure being 5 to 20 μm.

[0048] In one embodiment, a soft material complex is used to prepare a microstructure with a certain tilt angle, depth, and width on a polymer SU-8 photoresist substrate, wherein the microstructure includes an inverted square pyramid structure, a regular square pyramid structure, a columnar structure, and a stripe structure;

[0049] The inclination angle of the microstructure is 30 to 70 degrees; the depth is half of the depth of the overall structure after the angle of the microstructure is determined; and the width of the microstructure is 30 to 250 μm.

[0050] In one embodiment, silica nanoparticles of different sizes are used to prepare fractal nanostructures of certain height, particle size, and spacing on the surface of the microstructure by spraying;

[0051] The particle size of the nanostructure is 10 to 80 nm; the spacing is 30 to 60 nm; the depth is 90 to 180 nm; and the coordination of the micro-nano composite structure lies in the thickness of the nanostructure being 5 to 20 μm.

[0052] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. An underwater super-hydrophobic surface micro-nano composite structure that resists condensation failure, characterized in that: The substrate includes microstructures and nanostructures, where the inclination angle of the microstructure is 30~70°; the width of the microstructure is 30~250 μm; the nanostructure is located on the surface of the microstructure, and the particle size of the nanostructure is 10~80 nm; the spacing is 30~60 nm; the depth is 90~180 nm; the microstructure and nanostructure form a micro-nano composite structure, and the thickness of the nanostructure is 5~20 μm; the top of the single concave structure of the microstructure has a flange to limit the nanostructure.

2. The underwater super-hydrophobic surface micro-nano composite structure with resistance to condensation failure according to claim 1, characterized in that: The microstructure includes at least one of an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, and a strip structure with a certain inclination angle, depth, and width.

3. The underwater super-hydrophobic surface micro-nano composite structure with resistance to condensation failure according to claim 1, characterized in that: The substrate includes at least one of metal, alloy, silicon wafer, or glass.

4. The underwater super-hydrophobic surface micro-nano composite structure resistant to condensation failure according to claim 2, characterized in that: When the cross section of the inverted quadrangular pyramid structure is a trapezoid, the length of the lower base of the trapezoid is half the length of the upper base.

5. The underwater super-hydrophobic surface micro-nano composite structure with resistance to condensation failure according to claim 1, characterized in that: The width of the ridge is the same as the thickness of the nanostructures on the sides of the microstructures.

6. The method for preparing an underwater super-hydrophobic surface micro-nano composite structure resistant to condensation failure according to claim 1, characterized in that: The following steps are involved: S1. Using soft material replication or etching technology, an inverted quadrangular pyramid structure, a regular quadrangular pyramid structure, a columnar structure, or a strip structure with a certain tilt angle, depth, and width is prepared on a substrate to form a microstructure; S2. Using selected polymers or inorganic particles of different shapes as building blocks of the nanostructure, conical, sheet-shaped, or fractal nanostructures of a certain height, particle size, and spacing are prepared on the surface of the microstructure by spraying, chemical vapor deposition, evaporation, chemical oxidation, or ion beam etching. The nanostructures and microstructures form a micro-nano composite surface, and the synergistic effect between the micro-nano structures enables the active and timely discharge of condensed water. S3, immersing the micro-nano composite surface in an ethanol solution of perfluorododecyl mercaptan for a period of time, taking it out and rinsing it with deionized water, and drying it with nitrogen gas; S4. Use a blade to scrape the micro-nano composite surface back and forth, and then rub it back and forth with a large molecular weight hydrophilic polyethylene glycol solid to obtain a surface with an affinity-repellency micro-nano composite structure.

7. The method for preparing an underwater super-hydrophobic surface micro-nano composite structure resistant to condensation failure according to claim 6, characterized in that: The ion beam etching steps include: ultrasonically cleaning the finely polished metal sample in acetone, then placing it on an electric transfer stage, and performing surface etching using a picosecond laser system; ultrasonically cleaning the finely polished metal sample in acetone, then placing it on an electric transfer stage, and performing surface etching using a picosecond laser system; the central wavelength of the laser pulse is 1064 nm, the repetition rate is 597.44 kHz, and the maximum power is 65.4 W; the laser beam scanning trajectory is controlled by programming, and the scanning is repeated at a speed of 3 m / s; the laser beam is focused using a 100 mm field lens, and the laser spot diameter is approximately 30 μm.

8. The method for preparing an underwater super-hydrophobic surface micro-nano composite structure resistant to condensation failure according to claim 6, characterized in that: The chemical oxidation steps include: placing the sample in a tubular furnace to grow nanowires on the surface of the prepared microstructure; the tubular furnace is programmed to increase the temperature at a heating rate of 3°C / min and then stabilize at 480±5°C for 2 hours; the quartz tube of the tubular furnace is open to the laboratory atmosphere to allow the sample to oxidize in a fixed air; after the heat treatment is completed, the furnace temperature is turned off and the sample is removed when the furnace temperature drops below 30°C.

9. The method for preparing an underwater super-hydrophobic surface micro-nano composite structure resistant to condensation failure according to claim 6, characterized in that: The chemical vapor deposition step includes: using candle ash nanoparticles to prepare conical or fractal nanostructures with a certain height, particle size and spacing on the microstructure surface through a chemical vapor deposition method.

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