Micro-nano composite bi-pass aluminum oxide film with heterogeneous wettability as well as preparation method and application of micro-nano composite bi-pass aluminum oxide film

Abstract

The invention discloses a micro-nano composite bi-pass aluminum oxide film with heterogeneous wettability as well as a preparation method and application of the micro-nano composite bi-pass aluminum oxide film. The preparation method comprises the following steps: carrying out single-side protection on a super-amphiphilic micro-nano composite aluminum oxide film, and then removing the aluminum oxide film on the unprotected side; etching to remove the unreacted aluminum substrate and aluminum oxide barrier layer to obtain a bi-pass aluminum oxide film; then hydroxylation modification is carried out to obtain a hydroxylated alumina membrane, and finally interface wettability adjustment is carried out to prepare the heterogeneous wettability micro-nano composite bi-pass alumina membrane. The prepared micro-nano composite bi-pass aluminum oxide film has a self-assembled micron hole in one side, a three-dimensional interpenetrating nano hole in a bulk phase and a nano hole structure in the other side, and the intrinsic wettability of the micro-nano composite bi-pass aluminum oxide film is a super-amphiphilic interface. And finally, accurate wettability regulation and control and heterogeneous wettability construction are realized through chemical and physical wettability modification strategies, the super-amphiphilic through-hole aluminum oxide can be changed into a Janus aluminum oxide film, and the film has an asymmetric conical structure gradient.

Description

Technical Field

[0001] This invention belongs to the field of materials chemistry technology, specifically relating to a micro / nano composite double-pass alumina film with heterogeneous wettability, its preparation method, and its application. Background Technology

[0002] In recent years, the creation of specific functional membrane materials by altering the micro- and nano-structure of interfaces has attracted extensive research. Aluminum substrates, due to their advantages such as lightweight, abundant reserves, high thermal conductivity, and excellent processability, have enormous application prospects in heat transfer and heat dissipation equipment, electronic devices, medical devices, aerospace, and other fields.

[0003] There are many traditional methods for preparing alumina thin films, such as secondary anodizing, sol-gel method, vapor deposition, coating method, hydrothermal method, and high-temperature annealing method. These methods involve complex processes, high energy consumption, and high manufacturing costs. For example, vapor deposition requires atomizing aluminum at high temperatures and depositing it on a substrate to react with oxygen; this process is energy-intensive and complex. The sol-gel method requires spin coating, which results in significant material waste.

[0004] Traditionally, porous alumina films are prepared through a multi-step anodizing process. In 1995, MASUDA et al. first invented a two-step oxidation method (Science, 1995, 268, 1466-1468) to prepare large-area, highly ordered honeycomb-structured porous alumina film materials. In 2006, Woo Lee et al. invented a rapid anodizing method (Nature Materials, 2006, 5, 741-747) to prepare ordered porous alumina films. Furthermore, published patents such as CN110241450A, CN109518249A, CN1614102A, CN1222943A, and CN1614102A mainly provide methods for preparing ordered or disordered porous alumina structures. However, the porous alumina films prepared by the above methods do not possess superamphiphilic, superaphiphilic, or heterotrophic wettability.

[0005] Furthermore, the porous alumina films prepared by the disclosed methods are single-pore structures, and there are few reports on dual-pore alumina films with tunable wettability, which limits their in-depth application in sensing, medicine, catalysis, separation and other fields. Summary of the Invention

[0006] The main objective of this invention is to provide a micro / nano composite double-pass alumina film with heterogeneous wettability and its preparation method, so as to overcome the shortcomings of the prior art.

[0007] Another object of the present invention is to provide the application of the aforementioned heterogeneous wettability micro / nano composite double-pass alumina film.

[0008] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a method for preparing a micro / nano composite dual-channel alumina film with heterogeneous wettability, comprising: Provides superamphiphilic micro / nano composite alumina films; The superamophilic micro-nano composite alumina film is protected on one side, and then the alumina film on the unprotected side is removed. Etching removes the unreacted aluminum substrate and the aluminum oxide barrier layer to obtain a double-pass aluminum oxide film; The double-pass alumina film is modified by hydroxylation to obtain a hydroxylated alumina film; The interfacial wettability of the hydroxylated alumina film was adjusted to obtain a micro / nano composite dual-channel alumina film with heterogeneous wettability.

[0009] This invention also provides a micro / nano composite double-pass alumina membrane with heterogeneous wettability prepared by the aforementioned method.

[0010] In some embodiments, the heterogeneous wettability micro-nano composite double-channel alumina film is asymmetric, with one side surface having a macroporous structure of self-assembled nanofibers and three-dimensional interpenetrating nanochannels, and the opposite side surface having a microporous structure.

[0011] The embodiments of the present invention also provide the application of the aforementioned heterogeneous wettability micro-nano composite double-pass alumina membrane in the fields of catalysis, sensing, liquid transport and separation, medicine, microfluidics or water treatment.

[0012] Compared with the prior art, the beneficial effects of the present invention include: The preparation method provided by this invention uses an aluminum plate as a substrate. First, a super-amphiphilic interface with regularly self-assembled micropores and three-dimensional interpenetrating nanopores is prepared. Second, the prepared alumina film structure is effectively and precisely protected by controlling the type and concentration of the polymer solution. Third, by adjusting the etching solution concentration, etching time, and reaction temperature, a micro / nano composite dual-channel alumina film can be prepared through unreacted aluminum sheet removal and barrier layer etching steps. This micro / nano composite dual-channel alumina film has a self-assembled micropore structure on one side, a three-dimensional interpenetrating nanopore structure in bulk, and a nanopore structure on the other side, with intrinsic wettability as a super-amphiphilic interface. Finally, through chemical and physical wettability modification strategies, precise control of wettability and construction of heterogeneous wettability are achieved, transforming the super-amphiphilic through-hole alumina into a Janus alumina film, which possesses an asymmetric conical structural gradient. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a macroporous side structure diagram of the micro-nano composite double-pass alumina film prepared in Example 1 of the present invention; Figure 2 This is a three-dimensional interpenetrating nanoporous phase structure diagram of the micro-nano composite double-pass alumina film prepared in Example 1 of the present invention; Figure 3 This is a diagram of the pore side structure of the micro-nano composite double-pass alumina film prepared in Example 1 of the present invention; Figure 4 This is a schematic diagram of the contact angle of water on the macropore side of the micro-nano composite double-pass alumina membrane prepared in Example 1 of the present invention. Figure 5 This is a schematic diagram of the contact angle of the macropore side of the micro-nano composite double-pass alumina film prepared in Example 1 of the present invention with diiodomethane. Figure 6 This is a schematic diagram of the contact angle of water on the pore side of the micro-nano composite double-pass alumina membrane prepared in Example 1 of the present invention. Figure 7 This is a schematic diagram of the contact angle of water on the macropore side of the heterogeneous wettability micro-nano composite double-pass alumina membrane prepared in Example 2 of the present invention. Detailed Implementation

[0015] The application of superamphilic, superhydrophobic, or heterowetting membranes (Janus membranes) in catalysis, sensing, medicine, separation, water treatment, electrode materials, and smart device assembly has attracted increasing attention.

[0016] Given that the porous alumina films prepared by the above-mentioned existing methods do not have superamphiphilic, superhydrophobic, or heterosporous wettability, and are all single-channel pore structures, after long-term research and a large number of experiments, the inventors of this case have proposed this technical solution, which mainly provides a method for preparing micro-nano composite double-channel alumina films with heterosporous wettability.

[0017] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0018] As one aspect of the technical solution of the present invention, the method for preparing a micro / nano composite dual-channel alumina film with heterogeneous wettability includes: Provides superamphiphilic micro / nano composite alumina films; The superamophilic micro-nano composite alumina film is protected on one side, and then the alumina film on the unprotected side is removed. Etching removes the unreacted aluminum substrate and the aluminum oxide barrier layer to obtain a double-pass aluminum oxide film; The double-pass alumina film is modified by hydroxylation to obtain a hydroxylated alumina film; The interfacial wettability of the hydroxylated alumina film was adjusted to obtain a micro / nano composite dual-channel alumina film with heterogeneous wettability.

[0019] This invention can construct different wettability gradients according to application needs, ranging from superhydrophilic to superhydrophobic, while the micropore side is hydrophilic and the macropore side can be constructed from superhydrophilic to superhydrophobic.

[0020] In some embodiments, the preparation method specifically includes: The aluminum plate substrate is placed in a solvent for ultrasonic cleaning. The ultrasonically cleaned aluminum substrate is placed in a third etching solution for activation treatment. A single-step anodizing process was performed on the activated aluminum substrate to obtain an ultra-amphiphilic micro-nano composite alumina film.

[0021] In some specific embodiments, the preparation method of the heterogeneous wettability micro / nano composite dual-channel alumina film includes the following steps: 1) Place the aluminum plate substrate in a solvent for ultrasonic cleaning; 2) Place the ultrasonically cleaned aluminum substrate obtained in step 1) into the third etching solution for activation treatment; 3) Perform single-step anodizing on the activated aluminum substrate obtained in step 2) to obtain an ultra-amphiphilic micro-nano composite alumina film; 4) Protect the superamophilic micro / nano composite alumina film obtained in step 3) on one side; 5) Remove the aluminum oxide film on the unprotected side of the material obtained in step 4) using chemical or physical methods; 6) Use the first etching solution to remove the unreacted aluminum substrate from the material obtained in step 5); 7) Use the second etching solution to remove the alumina barrier layer from the material obtained in step 6), the purpose of which is to change the single-pass film into a double-pass film; 8) The material obtained in step 7) is hydroxylated to facilitate subsequent chemical modification.

[0022] 9) Adjust the interface wettability of the micro-nano composite double-channel alumina film obtained in step 8).

[0023] In some preferred embodiments, in step 1), the ultrasonic cleaning time is 10 to 60 minutes; the ultrasonic cleaning is used to remove organic contaminants and attached particulate matter from the surface of the aluminum substrate, and the removal effect is better within the specified time.

[0024] In some preferred embodiments, in step 1), the solvent is selected from one or more of acetone, ethanol, and deionized water; the solvent can more effectively remove organic pollutants and attached particulate matter.

[0025] In some preferred embodiments, in step 2), the third etching solution used is an aqueous solution of hydrochloric acid, an aqueous solution of sulfuric acid, an aqueous solution of phosphoric acid, or an aqueous solution of sodium hydroxide, etc.

[0026] Furthermore, the concentration of the third etching solution used is 0.1–2 mol / L.

[0027] In some preferred embodiments, in step 2), the activation treatment temperature is 0.1–100°C.

[0028] In some preferred embodiments, in step 2), the activation treatment time is 0.1 to 60 minutes.

[0029] In some preferred embodiments, in step 3), the electrolyte used for the single-step anodizing is an aqueous solution of oxalic acid, an aqueous solution of sulfuric acid, an aqueous solution of phosphoric acid, a mixed solution of oxalic acid and water and ethanol, or a mixed solution containing ammonium fluoride and ethylene glycol, etc.

[0030] In some preferred embodiments, in step 3), the concentration of the electrolyte is 0.1 to 2.0 mol / L.

[0031] In some preferred embodiments, in step 3), the single-step anodizing time is 0.01 to 24 hours.

[0032] In some preferred embodiments, step 3) specifically includes: lowering the electrolyte temperature to below 10°C, using the activated aluminum substrate as the anode and graphite as the cathode, performing single-step constant-current anodizing with an oxidation current of 0.1–3.5 A and an oxidation time of 0.01–24 h; during the anodizing process, the electrolyte temperature is gradually increased at a rate of 1–10°C / min. This single-step variable-temperature anodizing method solves the technical problem of traditional methods requiring multiple steps to construct micro / nano composite structures. The method is simple and can be used for large-scale fabrication.

[0033] Furthermore, step 3) includes a washing and drying process following the single-step anodizing reaction.

[0034] In some preferred embodiments, in step 4), the method of unilateral protection includes at least one of vapor deposition, polymer coating, interface modification, etc., but is not limited to this.

[0035] In some preferred embodiments, in step 4), the polymer solution used for polymer coating includes any one or more combinations of polymethyl methacrylate solution, polydimethylsiloxane solution, polyethylene terephthalate solution, polyvinylidene fluoride solution, polystyrene solution, and polyvinyl chloride solution, but is not limited to these. This invention uses polymers to protect the micro / nano structure from subsequent reactions that could damage the superamphilic micro / nano composite alumina film.

[0036] Furthermore, the concentration of the polymer solution is 1–30 wt%.

[0037] Furthermore, after the polymer coating is completed, the process should also include drying and curing the polymer, wherein the drying temperature is 100-200°C and the curing time is 1-24 hours.

[0038] In some preferred embodiments, in step 5), the method for removing the alumina film on the unprotected side in the preparation method can be a physical method or a chemical method.

[0039] Furthermore, the physical method may include at least one of mechanical stripping, grinding, and laser marking. The chemical method may include at least one of etching with an inorganic etching solution and dissolution with an organic solution. The inorganic etching solution used is any one or a combination of oxalic acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, sodium hydroxide solution, and potassium hydroxide solution. The organic solution used is any one or a combination of diiodomethane, n-hexane, dichloromethane, formamide, dimethyl sulfoxide, n-hexadecane, ethylene glycol, glycerol, silicone oil, toluene, acetone, and cyclopentanone, but is not limited to these.

[0040] Furthermore, step 5) should also include washing and drying after removing the unprotected alumina film.

[0041] In some preferred embodiments, the preparation method includes: performing a first etching with a first etching solution to remove unreacted aluminum substrate, and performing a second etching with a second etching solution to remove aluminum oxide barrier layer, thereby obtaining a dual-pass aluminum oxide film.

[0042] Further, in step 6), the first etching solution includes any one or more combinations of oxalic acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, hydrochloric acid solution, sodium hydroxide solution, potassium hydroxide solution, copper chloride solution, copper sulfate solution, tin chloride solution, etc., but is not limited to these.

[0043] Further, in step 6), the concentration of the first etching solution is 0.1–3 mol / L.

[0044] Furthermore, in step 6), the temperature of the first etching solution is 25–200°C.

[0045] Furthermore, in step 6), the first etching time is 0.1 to 72 hours, and the solution system needs to be stirred to ensure solution homogeneity.

[0046] In some preferred embodiments, in step 7), the second etching solution includes any one or more combinations of oxalic acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, hydrochloric acid solution, sodium hydroxide solution, potassium hydroxide solution, hydrogen peroxide solution, etc., but is not limited to these.

[0047] Furthermore, in step 7), the temperature of the second etching solution is 25–200°C.

[0048] Furthermore, in step 7), the second etching time is 0.1 to 72 hours, and the solution system needs to be stirred to ensure solution uniformity.

[0049] In some preferred embodiments, step 8) specifically includes: hydroxylating the double-pass alumina film by plasma treatment, grafting hydroxyl functional groups to obtain a hydroxylated alumina film.

[0050] Further, in step 8), the alumina film obtained is grafted with hydroxyl functional groups using a plasma cleaning machine. The atmosphere of the plasma treatment includes an air atmosphere or an oxygen atmosphere. The plasma treatment time is 0.1 to 360 min, and the plasma treatment power is 100 to 600 W.

[0051] In some preferred embodiments, step 8) specifically includes: hydroxylating the double-pass alumina film with a hydrogen peroxide solution. Specifically, the alumina film obtained in step 8) is hydroxylated with a hydrogen peroxide solution. The temperature of the hydrogen peroxide solution is 0–100°C, and the hydroxylation modification time, i.e., the treatment time, is 0.1–24 h.

[0052] In some preferred embodiments, step 9) specifically includes: adjusting the interfacial wettability of the hydroxylated alumina film using at least one of the following methods: sol-gel method, polymer grafting method, electrodeposition method, vapor deposition method, and immersion method.

[0053] Furthermore, the methods for adjusting the interface wettability described in step 9) include sol-gel method, polymer grafting, electrodeposition, vapor deposition, immersion method, etc., thereby achieving the transformation from superamphiphilic to superhydrophobic, or the construction of heterogeneous wettability, etc.

[0054] Further, in step 9), the modifier used in the polymer grafting method includes any one or more combinations of perfluorododecyltrichlorosilane, (3-aminopropyl)trimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, butyltrichlorosilane, octyltrichlorosilane, hexadecyltrichlorosilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, methyltrichlorosilane, 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, allyltrichlorosilane, allyltriethoxysilane, trichloro(phenylethyl)silane, and (6-phenylhexyl)trichlorosilane, but is not limited to these.

[0055] Further, in step 9), the diluent used in the polymer grafting method includes any one or more combinations of methanol, ethanol, acetone, hexanol, isopropanol, diiodomethane, n-hexane, dichloromethane, formamide, dimethyl sulfoxide, n-hexadecane, ethylene glycol, glycerol, silicone oil, toluene, cyclopentanone, etc., but is not limited to these.

[0056] Furthermore, in step 9), the mass fraction of the modifier used in the polymer grafting method is 1~100%, that is, the modifier is used as a solute and the diluent is used as a solvent. When the two are mixed in different proportions, the mass fraction of the modifier is 1~100%, the purpose of which is to construct heterogeneous wettability.

[0057] Further, in step 9), the modification temperature of the polymer grafting method is 25~500℃, and the modification time is 0.1~24h.

[0058] In summary, the preparation method of the present invention is simple to operate, can be mass-produced, and can achieve super-spreading or super-hydrophobicity of various organic and inorganic liquids on the membrane. In addition, it can achieve directional transport of specific substances through pores.

[0059] As another aspect of the technical solution of the present invention, it also relates to a micro-nano composite double-pass alumina film with heterogeneous wettability prepared by the aforementioned method.

[0060] In some embodiments, the heterogeneous wettability micro-nano composite double-channel alumina film has an asymmetric structure, that is, one side surface has a macroporous structure of self-assembled nanofibers and the bulk phase has three-dimensional interpenetrating nanochannels, while the opposite side surface has a microporous structure.

[0061] Furthermore, the heterogeneous wettability micro / nano composite double-channel alumina membrane exhibits superwetting properties on the macropore side and hydrophilic properties on the micropore side. Specifically, the macropore side exhibits superwetting properties with various liquids such as water and diiodomethane, with a measured contact angle of approximately 0°. This is due to the presence of three-dimensional capillary forces, which cause the gas-liquid-solid three-phase contact line to continuously diffuse towards the edge, thus achieving superwetting. The micropore side exhibits hydrophilic properties because the presence of nanopores, under the action of capillary forces, causes droplets to wet.

[0062] Furthermore, the pore size of the nanochannel is 10–300 nm.

[0063] Furthermore, the pore size of the macroporous structure is 0.5–5 μm.

[0064] Furthermore, the pore size of the micropore structure is 10–300 nm.

[0065] Furthermore, the diameter of the nanofibers constituting the macroporous structure is 10–200 nm.

[0066] Furthermore, the thickness of the heterogeneous wettability micro-nano composite double-pass alumina film is 15–30 μm.

[0067] Furthermore, the porosity of the side with the large pores is approximately 60-70%.

[0068] Furthermore, the porosity of the side with the small holes is approximately 60-70%.

[0069] Another aspect of the present invention provides the application of the aforementioned heterogeneous wettability micro / nano composite dual-channel alumina membrane in fields such as catalysis, sensing, liquid transport and separation, medicine, microfluidics, or water treatment.

[0070] Using the above technical solution, the preparation method provided by this invention uses an aluminum plate as a substrate. First, by controlling the concentration of the reaction solution, the anodizing time, and the reaction temperature, a super-amphiphilic micro / nano composite alumina film structure can be prepared through a single-step anodizing process. This oxide film can prepare a super-amphiphilic interface with regularly self-assembled micron-pores and three-dimensional interpenetrating nanopore structures. Second, the prepared alumina film structure is effectively and precisely protected by adjusting the type and concentration of the polymer solution. Furthermore, by adjusting the etching solution concentration, etching time, and reaction temperature, a micro / nano composite double-pass alumina film can be prepared through unreacted aluminum sheet removal and barrier layer etching steps. This micro / nano composite double-pass alumina film has a self-assembled micron-pore structure on one side, a three-dimensional interpenetrating nanopore structure in bulk, and a nanopore structure on the other side, with intrinsic wettability being a super-amphiphilic interface. Finally, through chemical and physical wettability modification strategies, precise control of wettability and construction of heterogeneous wettability are achieved, transforming the super-amphiphilic through-hole alumina into a Janus alumina film, which possesses an asymmetric conical structural gradient.

[0071] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0072] In this invention, the preparation methods are all conventional methods unless otherwise specified; the raw materials used can be obtained from publicly available commercial sources unless otherwise specified; and the percentages are all mass percentages unless otherwise specified.

[0073] Example 1 The preparation method of the superamphilic micro / nano composite double-pass alumina film in this embodiment includes the following steps: 1) Physical pre-cleaning: Cut the aluminum plate with a purity of 99.999% into appropriate shapes and ultrasonically clean it for 30 minutes each with acetone, ethanol and deionized water. 2) Substrate activation: The ultrasonically cleaned aluminum plate substrate obtained in step 1) is placed in a 1.0 mol / L sodium hydroxide aqueous solution and activated at 20°C for 1 minute. After removal, it is rinsed with deionized water 1 to 2 times.

[0074] 3) Anodizing: With the assistance of a circulating condenser, the temperature of the 0.5 mol / L phosphoric acid aqueous solution was reduced to 10 ℃; the activated aluminum plate substrate obtained in step 2) was used as the anode, and a graphite sheet was used as the cathode for constant current anodizing with an oxidation current of 2.0 A; the temperature was gradually increased during the oxidation process, the oxidation time was 10 min, and the electrolyte temperature was 72 ℃ at the end, with a heating rate of 6.2 ℃ / min.

[0075] 4) Wash the material obtained from the oxidation in step 3) repeatedly with deionized water three times, rinse with ethanol once, and then dry with N2 to obtain an ultra-amphiphilic micro-nano composite alumina film.

[0076] 5) Coat one side of the material obtained in step 4) with a 5 wt% polymethyl methacrylate solution and then bake it in an oven at 170°C for 60 min.

[0077] 6) Immerse the material obtained in step 5) in a 1 mol / L potassium hydroxide solution for 10 min to remove the aluminum oxide film on the other side.

[0078] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L copper chloride solution at 25°C for 2 h to remove the unreacted aluminum layer.

[0079] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L 50℃ phosphoric acid solution for 40 min to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0080] 9) The material obtained in step 8) is treated with plasma at 300W power for 2 minutes in an air atmosphere to attach hydroxyl groups to the surface of the film.

[0081] 10) Place the material obtained in step 9) into a vacuum vessel, add a few drops of 20 wt% perfluorododecyltrichlorosilane (diluent is methanol) to the bottom of the vacuum vessel, and place it in an oven at 150°C for 3 hours.

[0082] The micro / nano composite dual-channel alumina film material prepared by the above method simultaneously possesses a three-dimensional interpenetrating nanopore structure with micron-sized self-assembled macropores and bulk phase on one side, and a nanopore structure on the other side. SEM characterization of its micron-sized self-assembled pores is as follows: Figure 1 As shown, the bulk structure diagram of the three-dimensional interpenetrating nanopores is as follows: Figure 2 As shown, the surface morphology of the small hole side structure is as follows: Figure 3 As shown in the figure above, the dual-channel membrane is a three-dimensional, interlocking, cone-shaped through-hole structure with barbed edges. Furthermore, the interface of the micro / nano composite dual-channel alumina membrane exhibits superamionicity with both water and diiodomethane. A schematic diagram of the contact angle between the macropore side and water is shown below. Figure 4 As shown in the diagram, the contact angle of diiodomethane is as follows: Figure 5 As shown in the diagram. The contact angle of the small hole side with water is shown in the diagram. Figure 6 As shown in the diagram. After plasma treatment and wettability control strategies, the wettability on the micropore side remains unchanged, while the macropore side of the membrane changes from superhydrophilic to superhydrophobic. A schematic diagram of the contact angle of the macropore side with water is shown below. Figure 7 As shown.

[0083] Example 2 The preparation method of a superhydrophobic micro / nano composite double-pass alumina film in this embodiment includes the following steps: 1) Physical pre-cleaning: Cut the aluminum plate with a purity of 99.999% into appropriate shapes and ultrasonically clean it for 30 minutes each with acetone, ethanol and deionized water. 2) Substrate activation: The ultrasonically cleaned aluminum plate substrate obtained in step 1) is placed in a 1.0 mol / L sodium hydroxide aqueous solution and activated at 20°C for 1 minute. After removal, it is rinsed with deionized water 1 to 2 times.

[0084] 3) Anodizing: With the assistance of a circulating condenser, the temperature of the 0.5 mol / L phosphoric acid aqueous solution was reduced to 5 ℃; the activated aluminum plate substrate obtained in step 2) was used as the anode and a graphite sheet was used as the cathode for constant current anodizing with an oxidation current of 2.5 A; the temperature was gradually increased during the oxidation process, the oxidation time was 8 min, the electrolyte temperature was 78 ℃ at the end, and the heating rate was 9.1 ℃ / min.

[0085] 4) Wash the material obtained from the oxidation in step 3) repeatedly with deionized water three times, rinse with ethanol once, and then dry with N2 to obtain an ultra-amphiphilic micro-nano composite alumina film.

[0086] 5) Coat one side of the material obtained in step 4) with a 5 wt% polymethyl methacrylate solution and then bake it in an oven at 200°C for 120 min.

[0087] 6) Immerse the material obtained in step 5) in a 1 mol / L sodium hydroxide solution for 20 min to remove the alumina film on the other side.

[0088] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L tin chloride solution at 50°C for 2 hours to remove the unreacted aluminum layer.

[0089] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L 60℃ phosphoric acid solution for 30 min to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0090] 9) The material obtained in step 8) is treated with plasma at 200W power for 5 minutes in an air atmosphere to attach hydroxyl groups to the surface of the film.

[0091] 10) Place the material obtained in step 9) into a vacuum vessel, and drop a few drops of 20 wt% perfluorododecyltrichlorosilane (diluent is acetone) into the bottom of the vacuum vessel, and place it in an oven at 150°C for 3 hours.

[0092] The heterogeneous wettability micro / nano composite dual-channel alumina film material prepared by the above method simultaneously possesses a three-dimensional interpenetrating nanopore structure with micron-sized self-assembled macropores and bulk phase on one side, and a nanopore structure on the other side. The macropore-side structure, characterized by SEM, can be found at [reference needed]. Figure 1 As shown, the bulk three-dimensional nano-interpenetrating pores can be referenced. Figure 2 As shown, the small hole side structure can be referenced. Figure 3 As shown in the diagram. Through a wettability control strategy, the wettability on the micropore side remains unchanged, while the macropore side of the membrane changes from superhydrophilic to superhydrophobic. A schematic diagram of the contact angle of the macropore side with water can be found in the reference diagram. Figure 7 As shown.

[0093] Example 3 The preparation method of a superhydrophobic micro / nano composite double-pass alumina film in this embodiment includes the following steps: 1) Physical pre-cleaning: Cut the aluminum plate with a purity of 99.999% into appropriate shapes and ultrasonically clean it for 30 minutes each with acetone, ethanol and deionized water. 2) Substrate activation: The ultrasonically cleaned aluminum plate substrate obtained in step 1) is placed in a 1.0 mol / L sodium hydroxide aqueous solution and activated at 20°C for 1 minute. After removal, it is rinsed with deionized water 1 to 2 times.

[0094] 3) Anodizing: The temperature of the 0.5 mol / L phosphoric acid aqueous solution was reduced to 5 ℃ with the assistance of a circulating condenser; the activated aluminum plate substrate obtained in step 2) was used as the anode and a graphite sheet was used as the cathode for constant current anodizing with an oxidation current of 2.5 A; the temperature was gradually increased during the oxidation process, the oxidation time was 15 min, the electrolyte temperature was 76 ℃ at the end, and the heating rate was 4.7 ℃ / min.

[0095] 4) Wash the material obtained from the oxidation in step 3) repeatedly with deionized water three times, rinse with ethanol once, and then dry with N2 to obtain an ultra-amphiphilic micro-nano composite alumina film.

[0096] 5) Coat one side of the material obtained in step 4) with a 5 wt% polymethyl methacrylate solution and then bake it in an oven at 200°C for 200 min.

[0097] 6) Immerse the material obtained in step 5) in a 1 mol / L potassium hydroxide solution for 30 min to remove the aluminum oxide film on the other side.

[0098] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L copper chloride solution at 100℃ for 2 hours to remove the unreacted aluminum layer.

[0099] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L phosphoric acid solution at 60℃ for 35 min to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0100] 9) The material obtained in step 8) is treated with plasma at 200W power for 15 minutes in an air atmosphere to attach hydroxyl groups to the surface of the film.

[0101] 10) Place the material obtained in step 9) into a vacuum vessel, add a few drops of 30 wt% perfluorododecyltrichlorosilane (diluent is n-hexane) to the bottom of the vacuum vessel, and place it in an oven at 150°C for 2 h.

[0102] The heterogeneous wettability micro / nano composite dual-channel alumina film material prepared by the above method simultaneously possesses a three-dimensional interpenetrating nanopore structure with micron-sized self-assembled macropores and bulk phase on one side, and a nanopore structure on the other side. The macropore-side structure, characterized by SEM, can be found at [reference needed]. Figure 1 As shown, the bulk three-dimensional nano-interpenetrating pores can be referenced. Figure 2 As shown, the small hole side structure can be referenced. Figure 3 As shown in the diagram. Through a wettability control strategy, the wettability on the micropore side remains unchanged, while the macropore side of the membrane changes from superhydrophilic to superhydrophobic. A schematic diagram of the contact angle of the macropore side with water can be found in the reference diagram. Figure 7 As shown.

[0103] Example 4 The preparation method of a superhydrophobic micro / nano composite double-pass alumina film in this embodiment includes the following steps: 1) Physical pre-cleaning: Cut the aluminum plate with a purity of 99.999% into appropriate shapes and ultrasonically clean it for 30 minutes each with acetone, ethanol and deionized water. 2) Substrate activation: The ultrasonically cleaned aluminum plate substrate obtained in step 1) is placed in a 1.0 mol / L sodium hydroxide aqueous solution and activated at 20°C for 1 minute. After removal, it is rinsed with deionized water 1 to 2 times.

[0104] 3) Anodizing: With the assistance of a circulating condenser, the temperature of the 0.5 mol / L phosphoric acid aqueous solution was reduced to 5 ℃; the activated aluminum plate substrate obtained in step 2) was used as the anode, and a graphite sheet was used as the cathode for constant current anodizing with an oxidation current of 2.5 A; the temperature was gradually increased during the oxidation process, the oxidation time was 13 min, the electrolyte temperature was 80 ℃ at the end, and the heating rate was 5.8 ℃ / min.

[0105] 4) Wash the material obtained from the oxidation in step 3) repeatedly with deionized water three times, rinse with ethanol once, and then dry with N2 to obtain an ultra-amphiphilic micro-nano composite alumina film.

[0106] 5) Coat one side of the material obtained in step 4) with a 5 wt% polymethyl methacrylate solution and then bake it in an oven at 200°C for 300 min.

[0107] 6) Immerse the material obtained in step 5) in a 1 mol / L sodium hydroxide solution for 35 min to remove the alumina film on the other side.

[0108] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L copper chloride solution for 2.5 h to remove the unreacted aluminum layer.

[0109] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L 60℃ phosphoric acid solution for 60 min to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0110] 9) The material obtained in step 8) is treated with plasma at 250W power for 30 minutes in an air atmosphere to attach hydroxyl groups to the surface of the film.

[0111] 10) Place the material obtained in step 9) into a vacuum vessel, and drop a few drops of 50 wt% perfluorododecyltrichlorosilane (diluted solvent is dichloromethane) into the bottom of the vacuum vessel, and place it in an oven at 150°C for 2 h.

[0112] The heterogeneous wettability micro / nano composite dual-channel alumina film material prepared by the above method simultaneously possesses a three-dimensional interpenetrating nanopore structure with micron-sized self-assembled macropores and bulk phase on one side, and a nanopore structure on the other side. The macropore-side structure, characterized by SEM, can be found at [reference needed]. Figure 1 As shown, the bulk three-dimensional nano-interpenetrating pores can be referenced. Figure 2 As shown, the small hole side structure can be referenced. Figure 3 As shown in the diagram. Through a wettability control strategy, the wettability on the micropore side remains unchanged, while the macropore side of the membrane changes from superhydrophilic to superhydrophobic. A schematic diagram of the contact angle of the macropore side with water can be found in the reference diagram. Figure 7 As shown.

[0113] Example 5 The difference between this embodiment and Embodiment 1 is that: 5) Coat one side of the material obtained in step 4) with a 5 wt% polydimethylsiloxane solution and then bake it in an oven at 100°C for 24 hours.

[0114] 6) Immerse the material obtained in step 5) in sodium hydroxide solution for 35 min to remove the aluminum oxide film on the other side.

[0115] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in 0.1 mol / L copper sulfate solution at 200℃ for 0.1 h to remove the unreacted aluminum layer.

[0116] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 1 mol / L 50℃ phosphoric acid solution for 40 min to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0117] 9) The material obtained in step 8) is treated with plasma at 300W power for 15 minutes in an oxygen atmosphere to attach hydroxyl groups to the surface of the film.

[0118] 10) Place the material obtained in step 9) into a vacuum vessel, and drop a few drops of 80 wt% (3-aminopropyl)trimethoxysilane (diluent is formamide) into the bottom of the vacuum vessel, and place it in an oven at 150°C for 2 h.

[0119] The macroporous side of the alumina film prepared in this embodiment is hydrophilic.

[0120] Example 6 The difference between this embodiment and Embodiment 1 is that: 5) Coat one side of the material obtained in step 4) with a 5 wt% polyethylene terephthalate solution and then bake it in an oven at 150°C for 20 hours.

[0121] 6) Immerse the material obtained in step 5) in sodium hydroxide solution for 35 min to remove the aluminum oxide film on the other side.

[0122] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 3 mol / L copper sulfate solution at 25°C for 72 h to remove the unreacted aluminum layer.

[0123] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in 1 mol / L sulfuric acid solution at 25℃ for 1 hour to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0124] 9) The material obtained in step 8) is treated with plasma at 250W power for 30 minutes in an oxygen atmosphere to attach hydroxyl groups to the surface of the film.

[0125] 10) Place the material obtained in step 9) into a vacuum vessel, add a few drops of 100 wt% perfluorododecyltrichlorosilane to the bottom of the vessel, and place it in an oven at 120°C for 3 hours.

[0126] Example 7 The difference between this embodiment and Embodiment 1 is that: 5) Coat one side of the material obtained in step 4) with a 5 wt% polyvinylidene fluoride solution, and then bake it in an oven at 200°C for 60 min.

[0127] 6) Remove the aluminum oxide film on the other side by mechanical peeling of the material obtained in step 5).

[0128] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 2 mol / L copper chloride solution at 25°C for 2 hours to remove the unreacted aluminum layer.

[0129] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 2 mol / L sodium hydroxide solution at 100℃ for 10 min to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0130] 9) The double-pass alumina film obtained in step 8) is hydroxylated by hydrogen peroxide solution at a temperature of 100°C for 12 h.

[0131] 10) Place the material obtained in step 9) into a vacuum vessel, add a few drops of 1 wt% perfluorododecyltrichlorosilane (dimethyl sulfoxide as diluent) to the bottom of the vacuum vessel, and place it in a 200°C oven for 3 h.

[0132] Example 8 The difference between this embodiment and Embodiment 1 is that: 5) Coat one side of the material obtained in step 4) with a 5 wt% polystyrene solution and then bake it in an oven at 100°C for 100 min.

[0133] 6) Remove the aluminum oxide film on the other side of the material obtained in step 5) by laser marking.

[0134] 7) Wash the material obtained in step 6) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 2 mol / L oxalic acid aqueous solution at 80°C for 24 h to remove the unreacted aluminum layer.

[0135] 8) Wash the material obtained in step 7) three times with deionized water, rinse once with ethanol, and then dry with N2. Then soak it in a 3 mol / L hydrogen peroxide solution at 200℃ for 0.1 h to remove the barrier layer, thereby transforming the single-pass alumina film into a double-pass structure.

[0136] 9) The double-pass alumina film obtained in step 8) is hydroxylated using a hydrogen peroxide solution at a temperature of 100°C for 0.5 h.

[0137] 10) Place the material obtained in step 9) into a vacuum vessel, and drop a few drops of 10 wt% 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (diluted with ethanol) into the bottom of the vacuum vessel, and place it in an oven at 200°C for 0.5 h.

[0138] In addition, the inventors of this case also conducted experiments with other raw materials and conditions listed in this specification, referring to Examples 1-8, and similarly obtained micro-nano composite double-pass alumina films with heterogeneous wettability.

[0139] It should be understood that the above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformations or equivalent substitutions fall within the scope of protection of the present invention.

Claims

1. A method for preparing a micro / nano composite dual-channel alumina film with heterogeneous wettability, characterized in that, include: Provides superamphiphilic micro / nano composite alumina films; The superamophilic micro-nano composite alumina film is protected on one side, and then the alumina film on the unprotected side is removed. Etching removes the unreacted aluminum substrate and the aluminum oxide barrier layer to obtain a double-pass aluminum oxide film; The double-pass alumina film is modified by hydroxylation to obtain a hydroxylated alumina film; The interfacial wettability of the hydroxylated alumina film was adjusted to obtain a micro / nano composite dual-channel alumina film with heterogeneous wettability.

2. The preparation method according to claim 1, characterized in that: The method of unilateral protection includes at least one of vapor deposition, polymer coating, and interface modification; Preferably, the polymer solution used for the polymer coating includes any one or more combinations of polymethyl methacrylate solution, polydimethylsiloxane solution, polyethylene terephthalate solution, polyvinylidene fluoride solution, polystyrene solution, and polyvinyl chloride solution; particularly preferably, the concentration of the polymer solution is 1-30 wt%. Particularly preferred is that after the polymer coating is completed, the process further includes drying and curing the polymer, wherein the drying temperature is 100-200°C and the curing time is 1-24 hours.

3. The preparation method according to claim 1, characterized in that, include: Remove the aluminum oxide film on the unprotected side using physical or chemical methods; Preferably, the physical method includes at least one of mechanical peeling, grinding, and laser marking; Preferably, the chemical method includes at least one of inorganic etching solution etching and organic solution dissolution; particularly preferably, the inorganic etching solution used includes any one or a combination of oxalic acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, sodium hydroxide solution, and potassium hydroxide solution; particularly preferably, the organic solution used includes any one or a combination of diiodomethane, n-hexane, dichloromethane, formamide, dimethyl sulfoxide, n-hexadecane, ethylene glycol, glycerol, silicone oil, toluene, acetone, and cyclopentanone.

4. The preparation method according to claim 1, characterized in that, include: A first etching solution is used to perform a first etching to remove the unreacted aluminum substrate, and a second etching solution is used to perform a second etching to remove the aluminum oxide barrier layer, thereby obtaining a double-pass aluminum oxide film. Preferably, the first etching solution includes any one or more combinations of oxalic acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, hydrochloric acid solution, sodium hydroxide solution, potassium hydroxide solution, copper chloride solution, copper sulfate solution, and tin chloride solution; Preferably, the concentration of the first etching solution is 0.1–3 mol / L; Preferably, the temperature of the first etching solution is 25–200°C; Preferably, the etching time for the first etching is 0.1 to 72 hours; Preferably, the second etching solution includes any one or more combinations of oxalic acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, hydrochloric acid solution, sodium hydroxide solution, potassium hydroxide solution, and hydrogen peroxide solution; Preferably, the temperature of the second etching solution is 25–200°C; Preferably, the second etching time is 0.1 to 72 hours.

5. The preparation method according to claim 1, characterized in that, include: The double-pass alumina film is modified by hydroxylation through plasma treatment, grafting hydroxyl functional groups to obtain a hydroxylated alumina film; preferably, the plasma treatment atmosphere includes an air atmosphere or an oxygen atmosphere, the plasma treatment time is 0.1 to 360 min, and the plasma treatment power is 100 to 600 W. And / or, the preparation method includes: hydroxylating the double-pass alumina film with a hydrogen peroxide solution, preferably, the temperature of the hydrogen peroxide solution is 0-100°C, and the hydroxylation time is 0.1-24 h.

6. The preparation method according to claim 1, characterized in that, include: The interfacial wettability of the hydroxylated alumina film is adjusted by at least one of the following methods: sol-gel method, polymer grafting method, electrodeposition method, vapor deposition method, and immersion method. Preferably, the modifier used in the polymer grafting method includes any one or more combinations of perfluorododecyltrichlorosilane, (3-aminopropyl)trimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, butyltrichlorosilane, octyltrichlorosilane, hexadecyltrichlorosilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, methyltrichlorosilane, 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, allyltrichlorosilane, allyltriethoxysilane, trichloro(phenylethyl)silane, and (6-phenylhexyl)trichlorosilane. Preferably, the diluent used in the polymer grafting method includes any one or more combinations of methanol, ethanol, acetone, hexanol, isopropanol, diiodomethane, n-hexane, dichloromethane, formamide, dimethyl sulfoxide, n-hexadecane, ethylene glycol, glycerol, silicone oil, toluene, and cyclopentanone. Preferably, the mass fraction of the modifier used in the polymer grafting method is 1-100%; Preferably, the modification temperature of the polymer grafting method is 25~500℃, and the modification time is 0.1~24h.

7. The preparation method according to claim 1, characterized in that, include: The aluminum plate substrate is placed in a solvent for ultrasonic cleaning. The ultrasonically cleaned aluminum substrate is placed in a third etching solution for activation treatment. A single-step anodizing process was performed on the activated aluminum substrate to obtain an ultra-amphiphilic micro-nano composite alumina film.

8. A micro / nano composite double-pass alumina membrane with heterogeneous wettability prepared by any one of claims 1-7.

9. The micro / nano composite double-pass alumina membrane with heterogeneous wettability according to claim 8, characterized in that: The heterogeneous wettability micro-nano composite double-channel alumina film is asymmetrical, with one side surface having a macroporous structure of self-assembled nanofibers and three-dimensional interpenetrating nanochannels, and the opposite side surface having a microporous structure. Preferably, the pore size of the nanochannel is 10–300 nm; Preferably, the pore size of the macroporous structure is 0.5–5 μm; Preferably, the pore size of the micropore structure is 10–300 nm; Preferably, the diameter of the nanofibers is 10–200 nm; And / or, the heterogeneous wettability micro-nano composite double-channel alumina membrane exhibits superwetting properties on the side with large pores and hydrophilic properties on the side with small pores; And / or, the thickness of the heterogeneous wettability micro-nano composite double-pass alumina film is 15–30 μm.

10. The application of the heterogeneous wettability micro / nano composite dual-channel alumina membrane as described in claim 8 or 9 in the fields of catalysis, sensing, liquid transport and separation, medicine, microfluidics or water treatment.

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