A novel super oleophobic surface and its preparation method based on laminar microstructure deposition

Abstract

The present invention provides a novel structural super oleophobic surface and a preparation method thereof based on the deposition of laminated microstructures, which belongs to the technical field of functional surface preparation, including armor microstructures and laminated microstructures; there are micro grooves between adjacent armor microstructures, and laminated microstructures are arranged in the micro grooves, and there is a certain gap between the laminated microstructures and the armor microstructures; and the laminated microstructures are not higher than the armor microstructures; the lower ends of the armor microstructures and the micro grooves are both provided with substrates. In the present invention, there is a certain gap between the armor microstructure and the laminated microstructure in the super oleophobic surface, and the laminated microstructure can not only prevent itself from being wetted by oil, but also reduce the wetting of the oil to its adjacent armor microstructures. The preparation method based on the deposition of laminated microstructures is to transfer the laminated microstructure unit to the groove of the armor microstructure by liquid film assistance, and to increase the bonding strength between the laminated microstructure unit and the substrate by heating or brazing.

Description

Technical Field

[0001] The present invention relates to the technical field of functional surface preparation, and in particular to a novel structural super oleophobic surface and a preparation method thereof based on laminar microstructure deposition. Background Art

[0002] A superoleophobic surface refers to a functional surface that achieves a liquid-gas-liquid-solid composite contact interface between the oil and the surface by constructing a microstructure on the surface, thereby achieving an oil contact angle greater than 140°. Such a surface has potential application value in self-cleaning, anti-fouling and anti-adhesion. In recent years, it has received widespread attention in surface engineering, environment, biomedicine and other fields.

[0003] In general, a superoleophobic surface is achieved by constructing a secondary groove structure on the surface (Tuteja A, Choi W, Ma M, Mabry JM, Mazzella SA, Rutledge GC, McKinley GH, Cohen R E. Designing Superoleophobic Surfaces. Science 2007, 318: 1618-1622.) or a more complex double secondary groove structure (201010132465.4, Liu T, Kim CJ. Turning a surface superrepellent even to completely wetting liquids. Science 2014, 346: 1096-1100.). The construction process of these complex structure surfaces is complicated, and the mechanical properties of the constructed structures are poor. In order to improve the mechanical properties of functional surfaces, a durable superhydrophobic surface combining armor and functional structural units has been proposed in recent years (Wang D, Sun Q, Hokkanen MJ, et al. Design of robust superhydrophobic surfaces. Nature 2020, 582: 55-60.), but this surface only has a hydrophobic effect on water droplets with large surface tension, and does not work on oil with small surface tension. Drawing on the idea of ​​combining this armor and functional structural unit, it is expected to construct a surface with good mechanical properties and super oleophobic properties. The key lies in the construction of the oleophobic functional structural unit inside the armor structure.

[0004] The article "Construction of superoleophobic surface based on in-situ reactive liquid marble microstructure transfer" mentioned that the laminated structure can prevent itself from being wetted by oil. However, according to the model of this work, the laminated microstructure needs to fill the gaps between the microstructures, which limits the superoleophobic properties of the surface. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a novel super oleophobic surface and a preparation method thereof based on the deposition of a laminated microstructure. In the super oleophobic surface of the present invention, there is a certain gap between the armor microstructure and the laminated microstructure, and the laminated microstructure can not only prevent itself from being wetted by oil, but also reduce the wetting of the adjacent armor microstructure by the oil.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A super oleophobic surface with an armor-laminated microstructure comprises an armor microstructure and a laminated microstructure; micro grooves are provided between adjacent armor microstructures, a laminated microstructure is provided in the micro grooves, a certain gap is provided between the laminated microstructure and the armor microstructure; and the laminated microstructure is not higher than the armor microstructure; a base is provided at the lower ends of the armor microstructure and the micro grooves.

[0008] In the above scheme, the laminated microstructure is composed of multiple layers of lamellar units stacked together, and there are certain gaps between the lamellar units.

[0009] In the above solution, the armor microstructure is a micro-protrusion or a micro-ridge.

[0010] In the above scheme, the armor microstructure is used to withstand force and wear, and the laminated microstructure is used to achieve a superoleophobic function. Specifically, the oil is placed above the armor microstructure and the laminated microstructure, and the edge of the top layer of the laminated microstructure limits the oil from spreading downward along the laminated microstructure, so that the oil can only spread a limited distance on the armor microstructure, thereby preventing the oil from contacting partial areas of the microgrooves.

[0011] In the above scheme, the method for preparing a laminated microstructure includes the following steps: preparing a lamellar structure, interstitial materials and a binder, dispersing the prepared lamellar structure, interstitial materials and a binder into a solution, and dripping the solution onto a microporous template to obtain a laminated microstructure; or obtaining a laminated microstructure by in-situ growth through a chemical reaction.

[0012] In the above scheme, the laminated microstructure is first spread on a supporting plate, and then water or oil is spread on the liquid film supporting plate to form a liquid film, so that the liquid film on the liquid film supporting plate is in contact with the laminated microstructure laid on the supporting plate, thereby forming a liquid film surface with the laminated microstructure attached; or a solution that can react with a specific gas to generate a solid substance is first prepared, and the solution is spread on the liquid film supporting plate, and a reaction gas is introduced to react on the liquid film surface to generate a laminated microstructure, thereby forming a liquid film surface with the laminated microstructure attached; then, the armor microstructure surface is placed horizontally, the liquid film of the liquid film supporting plate is facing downward and the surface is kept horizontal, and the liquid film supporting plate is moved so that the laminated microstructure attached to the liquid film is in contact with the armor microstructure surface; the laminated microstructure on the liquid film is transferred to the microgrooves between the armor microstructures by vibration.

[0013] In the above scheme, the bonding performance between the laminated microstructure and the substrate is improved by increasing the temperature.

[0014] In the above scheme, the temperature is raised to 200-500°C and maintained for 10 minutes to 2 hours.

[0015] In the above scheme, before the laminated microstructure contacts the liquid film, a small amount of solder can be applied to one end of the laminated microstructure or solder can be placed on the base below the microgroove. After the laminated microstructure is transferred, the laminated microstructure and the base below the microgroove are brazed by heating.

[0016] In the above scheme, vibration is generated by vertical reciprocating movement, and the reciprocating movement frequency is greater than 3 Hz.

[0017] The present invention has the following technical advantages:

[0018] A new type of superoleophobic surface is realized in the form of armor structure + laminated microstructure. The laminated microstructure not only prevents the oil from wetting itself, but also reduces the oil from wetting the armor structure, expanding the structural types of superoleophobic surfaces and enriching the structural design options for superoleophobic surfaces.

[0019] The selective transfer of the laminated microstructure is achieved by utilizing the unstable transfer of liquid marbles formed by wrapping the laminated microstructure at the micro-groove area.

[0020] Through the form of armor structure + laminated microstructure, layer-by-layer wear can be achieved while the armor structure is worn, and the super-oleophobic function is achieved by the unworn laminated microstructure, ensuring that the wear process only has a limited impact on the super-oleophobic function of the surface.

[0021] Compared with the standard secondary groove structure and the complex double secondary groove structure super oleophobic surface preparation process (reactive ion etching process), the preparation of the armor structure + laminated microstructure super oleophobic surface can be achieved in the atmospheric atmosphere, with fewer requirements on the preparation conditions and a simpler and more practical preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the superoleophobic surface structure of the armor-laminated microstructure composite;

[0023] Figure 2 Schematic diagram of the superoleophobic surface structure of armor-laminated flower-like microstructure composite;

[0024] Figure 3 Schematic diagram of the contact state between the armor-laminate microstructure and the oil before and after wear;

[0025] Figure 4 Schematic diagram of the contact state between the armor-laminated flower-like microstructure and the oil before and after wear;

[0026] Figure 5 Schematic diagram of the template method preparation process of laminated microstructures;

[0027] Figure 6 Schematic diagram of the template-granulation method preparation process of the laminated microstructure;

[0028] Figure 7 Schematic diagram of the transfer of layered flower-like microstructures based on liquid film transfer;

[0029] Figure 8 Schematic diagram of the connection between the laminated flower-like microstructure and the substrate based on the laminated flower-like microstructure with its own solder;

[0030] Fig. 9 Schematic diagram of the connection between the laminated flower-like microstructure and the substrate based on confined solder;

[0031] Fig.10 The comparison of scanning electron microscope images of the armor microstructure surface and the armor microstructure surface modified with the laminated flower-like microstructure;

[0032] Fig.11 Images of droplets on the armor microstructure surface and the armor microstructure surface modified with the laminated flower-like oleophobic structure.

[0033] The reference numerals are as follows:

[0034] 1-substrate, 2-armor microstructure, 3-laminated microstructure, 4-oil, 5-gas, 6-laminated flower-like microstructure, 7-armor microstructure after wear, 8-laminated microstructure after wear, 9-laminated microstructure laminated flower-like microstructure after wear, 10-container, 11-microporous template, 12-laminated unit, 13-interstitial material and binder, 14-solution, 15-laminated structure wire, 16-liquid film supporting plate, 17-liquid film, 18-self-contained solder, 19-confined solder, 20-image of droplets on the surface of armor microstructure after silanization, 21-image of droplets on the surface of armor microstructure modified with laminated flower-like microstructure. DETAILED DESCRIPTION

[0035] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] Combine the following Figure 1-Figure 11 The implementation details and working conditions of the novel structural super oleophobic surface proposed in the present invention and the specific process based on the deposition of the laminated microstructure are described.

[0038] Armor-laminated microstructure super oleophobic surface microstructure as attached Figure 1 and 2 As shown, the armor microstructure 2 and the laminated microstructure 3 or laminated flower-shaped microstructure 6 on the substrate 1 are constituted together, and the laminated microstructure 3 or laminated flower-shaped microstructure 6 is embedded in the depression of the armor microstructure 2. A gap can be set between the laminated microstructure 3 or laminated flower-shaped microstructure 6 and the armor microstructure 2. The convex position of the armor microstructure 2 bears force and wear resistance, and the laminated microstructure 3 or laminated flower-shaped microstructure 6 realizes the super-oleophobic function, reducing the wetting of the armor microstructure 2 by the oil. When in contact with the oil 4, the edge of the laminated microstructure 3 or the laminated flower-shaped microstructure 6 drags the liquid surface so that the liquid cannot completely enter the depression of the armor microstructure 2, and the depression of the armor microstructure 2 has residual gas 5, thereby constructing the liquid-solid-liquid-gas composite interface required for the super-oleophobic surface. The laminated microstructure 2 or the laminated flower-shaped microstructure 6 is formed by stacking multiple layers of lamellar units, with certain gaps between the lamellar structures. The turning points and gaps of the lamellar structures jointly prevent the contact liquid surface from spreading between the lamellar layers and on the surface of the armor microstructure 2.

[0039] The contact state of the armor-laminated microstructure super-oleophobic surface with oil before and after wear is shown in the attached figure. Figure 3 and 4As shown, the height of the protruding part of the armor microstructure 2 is reduced after wear, and becomes the worn armor microstructure 7. At the same time, part of the laminar layers of the laminated microstructure 2 or the laminated flower-shaped microstructure 6 is worn, and becomes the worn laminated microstructure 8 or the worn laminated flower-shaped microstructure 9. The worn laminated microstructure 8 or the worn laminated flower-shaped microstructure 9 still has the laminated structural characteristics of the laminated microstructure 2 or the laminated flower-shaped microstructure 6, so that when the oil contacts the surface, a liquid-solid-liquid-gas composite interface is still formed, that is, a certain superoleophobic property is still maintained.

[0040] The preparation method of the laminated microstructure deposition for preparing the armor-laminated microstructure superoleophobic surface is: first prepare the armor microstructure surface; then prepare the laminated microstructure; cover the laminated microstructure on the liquid film surface on the liquid film supporting plate; contact the laminated microstructure attached to the liquid film with the armor microstructure surface; transfer the laminated microstructure attached to the liquid film to the depression on the armor microstructure surface by vibration; and improve the bonding performance between the laminated microstructure and the depression on the armor microstructure surface by post-processing.

[0041] First, the armor microstructure surface is prepared. It can be prepared on the surface of a substrate with good mechanical properties and wear resistance by traditional micromachining methods such as laser direct writing, photolithography, and embossing. The microstructure can be in the form of micro-protrusions, micro-ridges, or mesh microstructures. Then, the laminated microstructure can be prepared by layer unit deposition, or by chemical reaction in situ growth to achieve a laminated flower-like microstructure to replace the laminated microstructure. The method of preparing by layer unit deposition is shown in the attached Figure 5 and attached Figure 6 , first prepare a container 10 and a microporous template 11, and prepare a layer unit 12, mix the layer unit 12 and the interstitial material and the binder 13 to form a certain solution 14, pour the solution into the container 10 with the microporous template 11, and after standing for a period of time, part of the layer unit 12, the interstitial material and the binder 13 are deposited in the micropores of the microporous template 11 to form a laminated microstructure 3, and after taking out the template, clean the template surface and demould to obtain the laminated microstructure 3. As an improved method, a microporous template 11 with a longer micropore length can also be used, and after the layer unit 12, the interstitial material and the binder 13 are deposited, a laminated structure wire 15 is obtained, and then the laminated structure wire 15 is processed by cutting and granulating to obtain the laminated microstructure 3. The laminated flower-like microstructure is realized by in-situ growth of chemical reaction: a certain solution is prepared, the solution can react with a specific gas to generate a solid substance, and the solution is placed in a reaction gas atmosphere to promote a chemical reaction on the liquid surface to generate a laminated flower-like microstructure.

[0042] After obtaining the laminated microstructure, the laminated microstructure is covered on the liquid film surface on the liquid film supporting plate. The process is: the prepared laminated microstructure 3 or laminated flower-shaped microstructure 6 is spread on a laminated microstructure supporting plate, and then a liquid such as water or oil is spread on the liquid film supporting plate 16 to form a liquid film 17, and the liquid film 17 on the liquid film supporting plate 16 is contacted with the laminated microstructure 3 or laminated flower-shaped microstructure 6 laid on the laminated microstructure supporting plate, thereby forming a liquid film 17 surface attached with the laminated microstructure 3 or laminated flower-shaped microstructure 6; for the laminated flower-shaped microstructure 6 generated by in-situ reaction, the preparation of the laminated flower-shaped microstructure 6 can also be combined with the formation of the liquid film 17 attached with the laminated microstructure, first prepare a solution that can react with a specific gas to generate a solid substance, spread the solution on a liquid film supporting plate 16, introduce a reaction gas to react on the surface of the liquid film 17 to generate a laminated flower-shaped microstructure 6, thereby forming a liquid film 17 surface attached with the laminated flower-shaped microstructure 6.

[0043] After the liquid film with attached laminated microstructure is prepared, the laminated microstructure with attached liquid film is brought into contact with the surface of armor microstructure and the laminated microstructure 3 or laminated flower-shaped microstructure 6 on the liquid film is transferred to the concave part of the surface of armor microstructure by means of vibration. The process of bringing the laminated microstructure with attached liquid film into contact with the surface of armor microstructure is as follows: the armor microstructure surface 1 is placed horizontally, the liquid film 17 of the liquid film supporting plate 16 is facing downward and the surface is kept horizontal, the liquid film supporting plate is moved so that the laminated microstructure 3 or laminated flower-shaped microstructure 6 with attached liquid film is brought into contact with the surface of armor microstructure 2, and a gap block is placed between the liquid film supporting plate 16 and the surface of armor microstructure 2 to maintain the gap between the two surfaces. The principle of transferring the laminated microstructure 3 or laminated flower-shaped microstructure 6 to the concave part of the surface of armor microstructure 2 is as shown in the attached figure. Figure 7 As shown, the process is as follows: the target surface is placed horizontally, and vibration is generated by rapid vertical reciprocating movement, and the reciprocating movement frequency is greater than 3Hz, so that the laminated microstructure 3 or the laminated flower-shaped microstructure 6 on the surface of the liquid film 17 is separated from the surface of the liquid film 17 under the acceleration of the vibration, and is transferred to the micro-groove composed of the armor microstructure 2. In order to improve the bonding performance of the laminated microstructure and the substrate 1 below the micro-groove composed of the armor microstructure, the surface can be heated. Generally, the surface temperature is raised to 200-500°C and kept warm for 10 minutes to 2 hours.

[0044] In order to improve the adhesion of the laminated microstructure 3 or the laminated flower-shaped microstructure 6 to the concave part of the armor microstructure surface, a small amount of self-contained solder 18 can be applied to one end of the laminated microstructure before the laminated microstructure is transferred. Figure 8 or selectively placing a small amount of localized solder 19 in the recessed area of ​​the armor microstructure surface, as shown in the attached Fig. 9After the transfer of the laminated microstructure, the laminated microstructure and the concave part of the armor microstructure surface are brazed by heating treatment, and the heating treatment temperature is determined according to the thermodynamic characteristics of the brazing material.

[0045] In the embodiment, a LiOH solution is reacted with carbon dioxide to generate a laminated flower-like microstructure, and a liquid film with the laminated flower-like microstructure attached is simultaneously formed when the liquid film surface reacts, and the armor microstructure surface is a silicon wafer microstructure surface processed by laser.

[0046] The armor microstructure 2 is prepared on the surface of the substrate 1 (silicon wafer surface) by laser direct writing method. The protrusion spacing of the armor microstructure 2 is about 50 microns. The surface is silanized to improve the surface adhesion to the deposited laminated flower-like microstructure 6. The prepared laser-processed armor microstructure 2 surface is placed horizontally, and a small amount of broken silicon wafers are laid on the surface of the laser-processed armor microstructure 2 as gap blocks. A small amount of LiOH solution is poured onto a smooth silicon wafer, and the LiOH solution is spread into a thin liquid film by blowing air. Carbon dioxide gas is blown to the liquid film to react on the surface of the liquid film to generate a laminated flower-like microstructure 6. After the surface of the liquid film turns white, the liquid film is reversed downward so that it contacts the surface of the laser-processed armor microstructure 2, and the smooth silicon wafer contacts and fixes the gap blocks of broken silicon wafers pre-placed on the surface of the laser-processed armor microstructure 2. Manually shaking the surface of the laser processed armor microstructure 2 causes the laminated flower-like microstructure 6 and the liquid film 17 in contact therewith to vibrate, and the laminated flower-like microstructure 6 is transferred to the concave part of the surface of the laser processed armor microstructure 2. The scanning electron microscope pictures of the silicon wafer microstructure surface before and after the transfer of the laminated flower-like microstructure 6 are shown in the attached figure. Fig.10 As shown, the left picture shows the surface morphology before transfer. The surface morphology of the recessed area processed before transfer is obvious. The right picture shows the surface morphology after transfer. After transfer, a stacked flower-like microstructure 6 appears in the recessed area of ​​the surface. There is a certain gap between the stacked flower-like microstructure 6 and the armor microstructure 2, which provides conditions for the formation of the liquid-gas interface necessary for the superoleophobic surface.

[0047] The pictures of the droplets on the surface of the laminated flower-like microstructure 6 before and after transfer are shown in the attached figure. Fig.11 As shown, before transfer, corn oil and soybean oil are dropped on the surface, and the image of the droplets on the surface of the armor microstructure after silanization is 20, and the contact angle of the oil on the surface is less than 120°; after the transfer of the laminated flower-like microstructure, corn oil and soybean oil are dropped on the surface, and the image of the droplets on the surface of the armor microstructure modified with the laminated flower-like microstructure is 21, and the contact angles formed by the oil droplets on the surface are greater than 140°, achieving super oleophobic properties of the surface.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0049] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A superoleophobic surface with an armor-laminated microstructure, characterized in that: It includes an armor microstructure and a laminated microstructure; there are microgrooves between adjacent armor microstructures, and a laminated microstructure is arranged in the microgrooves, and there is a certain gap between the laminated microstructure and the armor microstructure; and the laminated microstructure is not higher than the armor microstructure; the lower ends of the armor microstructure and the microgrooves are both provided with a base; the armor microstructure is used to withstand force and wear, and the laminated microstructure is used to achieve a super oleophobic function. Specifically, oil is placed above the armor microstructure and the laminated microstructure, and the edge of the top layer of the laminated microstructure limits the oil from spreading downward along the laminated microstructure, so that the oil can only spread a limited distance on the armor microstructure, thereby preventing the oil from contacting a partial area of ​​the microgrooves.

2. The super oleophobic surface with armor-laminated microstructure according to claim 1, characterized in that: The laminated microstructure is composed of a plurality of laminated lamellar units, and there are certain gaps between the lamellar units.

3. The super oleophobic surface with armor-laminated microstructure according to claim 1, characterized in that: The armor microstructure is micro-protrusions or micro-ridges.

4. The super oleophobic surface with armor-laminated microstructure according to claim 1, characterized in that: The method for preparing a laminated microstructure comprises the following steps: preparing a lamellar structure, interstitial material and a binder, dispersing the prepared lamellar structure, interstitial material and binder into a solution, and dripping the solution into a microporous template to obtain a laminated microstructure; Alternatively, a laminated microstructure can be obtained by in-situ growth through chemical reaction.

5. The super oleophobic surface with armor-laminated microstructure according to claim 4, characterized in that: First, the laminated microstructure is spread on a supporting plate, and then water or oil is spread on the liquid film supporting plate to form a liquid film, so that the liquid film on the liquid film supporting plate contacts the laminated microstructure laid on the supporting plate, thereby forming a liquid film surface with the laminated microstructure attached; or first prepare a solution that can react with a specific gas to generate a solid substance, spread the solution on the liquid film supporting plate, introduce a reaction gas to react on the liquid film surface to generate a laminated microstructure, thereby forming a liquid film surface with the laminated microstructure attached; then, the armor microstructure surface is placed horizontally, the liquid film of the liquid film supporting plate is facing downward and the surface is kept horizontal, and the liquid film supporting plate is moved to make the laminated microstructure attached to the liquid film contact the armor microstructure surface; the laminated microstructure on the liquid film is transferred to the micro grooves between the armor microstructures by vibration.

6. The super oleophobic surface with armor-laminated microstructure according to claim 5, characterized in that: The bonding performance between the laminated microstructure and the substrate is improved by increasing the temperature.

7. The super oleophobic surface with armor-laminated microstructure according to claim 6, characterized in that: The temperature is raised to 200-500°C and maintained for 10 minutes to 2 hours.

8. The super oleophobic surface with armor-laminated microstructure according to claim 5, characterized in that: Before the laminated microstructure contacts the liquid film, a small amount of solder can be applied to one end of the laminated microstructure or solder can be placed on the base below the microgroove. After the laminated microstructure is transferred, the laminated microstructure and the base below the microgroove are brazed by heating.

9. The super oleophobic surface with armor-laminated microstructure according to claim 5, characterized in that: Vibration is generated by vertical reciprocating movement, and the reciprocating movement frequency is greater than 3Hz.

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