Hydrophobic surface as well as preparation method and application thereof

Abstract

The invention provides a hydrophobic surface as well as a preparation method and application thereof, and the preparation method comprises the following steps: sequentially carrying out cleaning treatment, amination modification treatment and bromine modification treatment on the surface of a substrate; mixing a perfluoroalkyl methacrylate monomer and a catalyst with deoxygenated water, and uniformly dispersing to obtain an emulsion polymerization solution; putting the substrate subjected to the surface pretreatment into an emulsion polymerization solution so as to carry out emulsion polymerization reaction on the surface of the substrate; and after the reaction is finished, taking out the substrate, and then sequentially cleaning and drying the substrate to obtain the hydrophobic surface. The hydrophobic surface, especially the super-hydrophobic surface, provided by the invention shows excellent hydrophobicity (super-hydrophobicity), extremely high stability, excellent antifouling performance and the like under various extreme conditions (such as different acidity, alkalinity or heating conditions).

Description

Technical Field

[0001] The invention relates to a hydrophobic surface and a preparation method and application thereof, belonging to the technical field of functional materials. Background Art

[0002] Super-hydrophobic surfaces have many excellent properties in the air, such as anti-adhesion, anti-fouling, anti-icing, surface self-cleaning and anti-corrosion. The traditional method for preparing super-hydrophobic surfaces usually includes two steps: first, the surface is covered with a hydrophobic material, and then the surface microstructure is constructed. Among them, the first step can be achieved by the self-assembly of hydrophobic particles, such as chemical deposition, layer-by-layer deposition, colloidal self-assembly, phase separation and electrostatic spinning. The second step of constructing the surface microstructure needs to be achieved by etching process or plasma treatment. However, the above method not only requires the assistance of advanced equipment such as nano-imprinting machines, etching machines and electrostatic spinning, but also the manufacturing process is extremely complicated and has many limitations. For many application fields of fine chemicals, such as the inner surface of capillaries and irregular micro-size substrates with irregular surface morphology, it is difficult to prepare a super-hydrophobic surface with high stability by the above method. In addition, the above method mostly uses volatile organic solvents to dissolve hydrophobic materials, which is often harmful to the environment and human health. Finally, the hydrophobicity of the super-hydrophobic surface prepared by the above method cannot be regulated, and its application in the micro-industrial field is limited.

[0003] Therefore, how to simply and efficiently prepare a hydrophobic surface and make its surface hydrophobicity adjustable has become a technical problem that urgently needs to be solved in this field. Summary of the invention

[0004] In order to solve the above-mentioned shortcomings and deficiencies, an object of the present invention is to provide a method for preparing a hydrophobic surface.

[0005] Another object of the present invention is to provide a hydrophobic surface, which is prepared by the above-mentioned method for preparing the hydrophobic surface.

[0006] Another object of the present invention is to provide applications of the above-mentioned hydrophobic surface in the fields of oil-water separation, self-cleaning surface, antifouling surface, antifreeze surface, metal corrosion, battery, membrane engineering, microfluidics or droplet manipulation.

[0007] In order to achieve the above objectives, on the one hand, the present invention provides a method for preparing a hydrophobic surface, wherein the preparation method comprises:

[0008] S1 surface pretreatment: cleaning, amino modification and bromine modification are performed on the surface of the substrate in sequence;

[0009] S2 emulsion polymerization liquid preparation: perfluoroalkyl methacrylate monomer and catalyst are mixed with deoxygenated water and dispersed uniformly to obtain emulsion polymerization liquid;

[0010] S3: Preparation of hydrophobic surface: placing the substrate obtained in S1 after surface pretreatment into an emulsion polymerization solution to perform an emulsion polymerization reaction on the surface of the substrate;

[0011] S4 post-treatment: After the reaction is completed, the substrate is taken out, and then the substrate is cleaned and dried in sequence to obtain the hydrophobic surface.

[0012] As a specific embodiment of the preparation method described above of the present invention, when the substrate is a non-metallic substrate, the cleaning treatment in S1 includes: firstly cleaning the substrate with deionized water and ethanol in sequence, and then immersing the substrate in a Piranha solution;

[0013] Preferably, the Piranha solution is a mixed solution prepared by hydrogen peroxide and concentrated sulfuric acid with a volume fraction of hydrogen peroxide being 15-30% (based on the total volume of the mixed solution);

[0014] Also preferably, the soaking is soaking at 70-120° C. for 1-3 h, more preferably, the soaking is soaking at 80° C. for 2 h;

[0015] When the substrate is a metal substrate, such as gold, iron, etc., the cleaning process in S1 includes: firstly immersing the substrate in a cleaning solution, taking out the substrate and cleaning it with anhydrous ethanol, and finally drying the substrate in an inert atmosphere, such as nitrogen or argon;

[0016] Also preferably, the cleaning solution is a mixed solution prepared by hydrogen peroxide, ammonia water and deionized water in volume fractions of 10-20%, 10-20% and 60-80% respectively (wherein the volume fractions are calculated based on the total volume of the mixed solution);

[0017] Also preferably, the substrate is immersed in the cleaning solution at a temperature of 70-90° C. for 0.5-2 h, and even more preferably, the substrate is immersed in the cleaning solution at a temperature of 70° C. for 1 h.

[0018] As a specific embodiment of the preparation method described above of the present invention, the amination modification treatment in S1 includes: firstly immersing the cleaned substrate in an amination modification solution to perform an amination modification treatment on the surface of the substrate, taking out the substrate after the modification and washing it with anhydrous ethanol, and finally drying the substrate in an inert atmosphere, such as nitrogen;

[0019] Preferably, the amino-modified solution is an alcohol solution containing aminosilicone and / or its isomers;

[0020] More preferably, in the amination-modified solution, the volume fraction of aminosilicone and / or its isomers is 4%-6% based on the total volume of the amination-modified solution;

[0021] Also preferably, the temperature of the amination modification treatment is 20-30°C.

[0022] The present invention does not make specific requirements on the duration of the amination modification treatment in S1, and can be reasonably adjusted according to the actual needs of the on-site operation, as long as the purpose of the present invention can be achieved. For example, in some specific embodiments of the present invention, the duration of the amination modification treatment in S1 is 30 minutes, that is, the soaking time is 30 minutes, and the temperature of the amination modification treatment is room temperature.

[0023] In S1 of some specific embodiments of the present invention, the amino-modified solution is an ethanol solution of 3-aminopropyltriethoxysilane (APTES), which is prepared by dissolving 3-aminopropyltriethoxysilane in ethanol.

[0024] As a specific embodiment of the preparation method described above of the present invention, the bromine modification treatment in S1 includes: firstly immersing the substrate after the amino modification treatment in an active bromine modification solution to perform bromine modification treatment on the surface of the substrate, taking out the substrate after the bromine modification treatment and washing it with anhydrous ethanol, and finally drying the substrate in an inert atmosphere, such as nitrogen atmosphere;

[0025] Preferably, the solute of the active bromine modified solution comprises 2-bromoisobutyryl bromide and triethylamine, wherein the molar concentration of 2-bromoisobutyryl bromide is 40-45 mol / L, and the molar concentration of triethylamine is 35-40 mol / L based on the total volume of the active bromine modified solution;

[0026] Also preferably, the temperature of the bromine modification treatment is room temperature. The present invention does not make specific requirements on the time of the bromine modification treatment in S1, and can be reasonably adjusted according to the actual needs of the on-site operation, as long as the purpose of the present invention can be achieved. For example, in some specific embodiments of the present invention, the time of the bromine modification treatment in S1 is 30 minutes, that is, the soaking time is 30 minutes. In addition, the solvent in the active bromine modified solution can be any anhydrous solvent, such as dichloromethane and anhydrous ethanol.

[0027] In some embodiments of the present invention, the active bromine-modified solution is prepared by dissolving 0.42 mol of triethylamine and 0.37 mol of 2-bromoisobutyryl bromide in 10 mL of dichloromethane in sequence.

[0028] In the present invention, the substrate obtained after the bromine modification treatment can be stored in an inert atmosphere, such as nitrogen.

[0029] As a specific embodiment of the preparation method described above of the present invention, the dissolved oxygen content in the deoxygenated water in S2 is less than 0.1 mg / L;

[0030] Preferably, the deoxygenated water is prepared by a method comprising the following steps:

[0031] Freezing ultrapure water into ice in a temperature environment not higher than -20°C and then thawing it at 15-25°C, repeating the freezing and thawing process multiple times to obtain the deoxygenated water;

[0032] More preferably, the number of repetitions is no less than 3 times.

[0033] As a specific embodiment of the preparation method described above of the present invention, in S2, the perfluoroalkyl methacrylate monomer is one or more of 2,2,2-trifluoroethyl methacrylate, 2-(perfluorooctyl)ethyl methacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl methacrylate and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate, etc., or a combination thereof;

[0034] Preferably, in the emulsion polymer of S2, the volume fraction of the perfluoroalkyl methacrylate monomer is in the range of 0.1%-5% based on the total volume of the emulsion polymer, and more preferably, the volume fraction of the perfluoroalkyl methacrylate monomer is greater than 2% and less than or equal to 5%;

[0035] Also preferably, the catalyst comprises cuprous ions, and the concentration of the cuprous ions is 0.01-0.02 mol / L based on the total volume of the emulsion polymer solution;

[0036] More preferably, the emulsion polymer solution further comprises a stabilizer, and the concentration of the stabilizer is 0.02-0.03 mol / L based on the total volume of the emulsion polymer solution.

[0037] In the present invention, dissolving the catalyst in the emulsion polymerization liquid can accelerate the process of the emulsion polymerization reaction in step S3. The cuprous ions used as the catalyst can be provided by any cuprous salt that can be dissolved in the emulsion polymerization liquid. For example, in some embodiments of the present invention, the cuprous salt used is cuprous bromide; in addition, the present invention does not make specific requirements on the specific material of the stabilizer, and it can be reasonably selected and adjusted according to the actual needs of the on-site operation. For example, in some specific embodiments of the present invention, the stabilizer is 2,2'-bipyridine.

[0038] As a specific embodiment of the preparation method described above in the present invention, S2 comprises: adding a perfluoroalkyl methacrylate monomer liquid into deoxygenated water at a certain volume fraction, and shaking it in an ultrasonic instrument for a period of time, such as 10 minutes, etc., to disperse it into an emulsion to obtain the emulsion polymer solution.

[0039] As a specific embodiment of the preparation method described above of the present invention, wherein, in S3, the emulsion polymerization reaction is carried out under a sealed and inert atmosphere, such as nitrogen;

[0040] Preferably, the temperature of the emulsion polymerization reaction is mainly room temperature, and the time is 1-12 hours. More preferably, the time of the emulsion polymerization reaction is 8-12 hours.

[0041] In S3 of the preparation method described above, the greater the volume fraction of the perfluoroalkyl methacrylate monomer, the longer the reaction time, and the higher the hydrophobicity of the surface of the obtained hydrophobic surface sample. Thus, the present invention can control the density and morphology of the surface polymer particles generated by controlling / adjusting the volume fraction of the perfluoroalkyl methacrylate monomer, that is, the density and reaction time of the perfluoroalkyl methacrylate monomer droplets, thereby controlling the hydrophobicity of the hydrophobic surface and obtaining a hydrophobic surface with different hydrophobicity and adjustable hydrophobicity. In the present invention, the time of the emulsion polymerization reaction is controlled to be 8-12h and the volume fraction of the perfluoroalkyl methacrylate monomer is greater than 2% and less than or equal to 5%, so as to prepare a super hydrophobic surface.

[0042] As a specific embodiment of the preparation method described above of the present invention, in S3, the substrate with surface pretreatment obtained in S1 is placed vertically in an emulsion polymerization liquid and an emulsion polymerization reaction is carried out on the surface of the substrate to prepare a hydrophobic surface with a hydrophobicity gradient on the surface of the substrate. Since the concentration of the perfluoroalkyl methacrylate monomer in the emulsion polymerization liquid will form a concentration gradient under the action of an external force field, such as a gravity field, the substrate with surface pretreatment obtained in S1 is slowly placed vertically in the emulsion polymerization liquid and an emulsion polymerization reaction is carried out on the surface of the substrate, so that a hydrophobic surface with a hydrophobicity gradient can be prepared on the surface of the substrate.

[0043] The present invention does not make any specific requirements on the shape and material of the substrate, and can be reasonably selected according to the actual needs of the site operation, as long as the purpose of the present invention can be achieved. For example, when the present invention intends to produce a hydrophobic surface with a hydrophobicity gradient, a long strip substrate can be used.

[0044] As a specific embodiment of the preparation method described above of the present invention, in S4, the cleaning includes cleaning with water and ethanol in sequence.

[0045] The present invention does not make specific requirements on the temperature and time of drying in the above-mentioned preparation method S4, drying in the cleaning process in S1, drying in the amination modification process in S1, and drying in the bromine modification process in S1. Reasonable selection and adjustment can be made according to the actual needs of the on-site operation, as long as the purpose of drying can be achieved.

[0046] On the other hand, the present invention also provides a hydrophobic surface, wherein the hydrophobic surface is prepared by the above-mentioned method for preparing the hydrophobic surface.

[0047] As a specific embodiment of the hydrophobic surface described above in the present invention, the hydrophobic surface is a super hydrophobic surface.

[0048] On the other hand, the present invention also provides applications of the above-mentioned hydrophobic surface in the fields of oil-water separation, self-cleaning surface, antifouling surface, antifreeze surface, metal corrosion, battery, membrane engineering, microfluidics or droplet manipulation.

[0049] The invention prepares a hydrophobic surface with different hydrophobicities and controllable hydrophobicity through surface-initiated emulsion polymerization. In the preparation process, the surface of a substrate is firstly subjected to a cleaning treatment, an amination modification treatment and a bromination modification treatment in sequence, so as to graft amino groups on the surface of the substrate and then graft bromine on the amino groups, thereby completing the preparation of a surface initiator; then, a perfluoroalkyl methacrylate monomer is mixed with deoxygenated water and dispersed evenly to obtain an emulsion polymerization liquid; then, the substrate to which the surface initiator has been attached is placed in the emulsion polymerization liquid, and the perfluoroalkyl methacrylate monomer droplets dispersed in the emulsion polymerization liquid diffuse to the surface of the substrate, and a free radical polymerization reaction of the perfluoroalkyl methacrylate monomer attached to the surface of the substrate is initiated under the action of the surface initiator and a catalyst to generate hydrophobic polymer solid particles, and a hydrophobic surface or even a super-hydrophobic surface can be obtained by controlling the reaction time and the concentration of the monomer droplets.

[0050] The preparation method provided by the present invention abandons the volatile organic solvents, special substrates and complex modification equipment that must be used in the existing conventional methods, and combines the surface morphology construction process and the surface hydrophobic modification process into one, so that the required hydrophobic surface or even super-hydrophobic surface can be controllably prepared in an aqueous environment and on a flat substrate; and the hydrophobic surface (especially the super-hydrophobic surface, that is, the surface with a contact angle greater than 150°) prepared by the present invention shows excellent hydrophobicity (super-hydrophobicity), extremely strong stability and excellent anti-fouling performance under various extreme conditions (such as different acidity, alkalinity or heating conditions). BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A process flow chart of a method for preparing a hydrophobic surface provided in an embodiment of the present invention.

[0053] Figure 2 This is a schematic diagram of the structure of the experimental device used in Example 1-Example 2 of the present invention.

[0054] Figure 3 This is a schematic diagram of the structure of the experimental device used in Example 3 of the present invention.

[0055] Figure 4a-4e The contact angle image and optical image of the super-hydrophobic surface with controllable hydrophobic gradient obtained in Example 3 of the present invention.

[0056] Figure 5a The super hydrophobic surface with a contact angle of 164.7° provided in Example 3 of the present invention (corresponding to Figure 4a ), Figure 5b for Figure 5a Enlarged SEM image of the boxed area. Figure 5c The super hydrophobic surface with a contact angle of 164.7° provided in Example 3 of the present invention (corresponding to Figure 4a )EDS image of fluorine element.

[0057] Figure 6 The super hydrophobic surface provided in Example 1 of the present invention is 3 The contact angle changes were measured by a contact angle meter in the pH range of 0-14 after being stored for 2 h under NaCl) and high temperature (air atmosphere, temperature is 120°C) conditions.

[0058] Figure 7a-7c This is a diagram of the antifouling performance experimental process of the hydrophobic surface in Test Example 3 of the present invention.

[0059] Description of main figures:

[0060] 1. Emulsion polymerization liquid;

[0061] 2. Conical reaction bottle;

[0062] 3. Nitrogen cylinder;

[0063] 4. Silicon substrate after surface pretreatment;

[0064] 5. Long cylindrical bottle. DETAILED DESCRIPTION

[0065] It should be noted that the term "comprises" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0066] "Scope" disclosed in the present invention is given in the form of lower limit and upper limit. It can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e. any lower limit can be combined with any upper limit to form a range. For example, for a specific parameter, a range of 60-120 and 80-110 is listed, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and the maximum range values ​​listed are 3, 4 and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.

[0067] In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in the present invention, and "0-5" is just an abbreviation of these numerical combinations.

[0068] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0069] In the present invention, unless otherwise specified, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0070] In the present invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0071] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the attached table, drawings and examples. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0072] Example 1

[0073] This embodiment provides a super hydrophobic surface, which is prepared by a preparation method comprising the following specific steps, wherein the process flow chart of the preparation method and the structural schematic diagram of the experimental device used are respectively as shown in Figure 1 and Figure 2 As shown, from Figure 1 and Figure 2 It can be seen that the preparation method comprises:

[0074] S1 surface pretreatment: firstly, the surface of the silicon substrate is cleaned, then the surface of the cleaned silicon substrate is subjected to amino modification, and finally the surface of the substrate subjected to amino modification is subjected to bromine modification to complete the preparation of the surface initiator;

[0075] The cleaning treatment specifically includes: cleaning the silicon substrate with deionized water and ethanol in sequence, and then immersing the cleaned silicon substrate in a Piranha solution, maintaining the temperature at 80° C. for 2 hours, wherein the Piranha solution is a mixed solution prepared according to a volume fraction of 30% hydrogen peroxide and a volume fraction of 70% concentrated sulfuric acid;

[0076] The amination modification treatment specifically includes: firstly immersing the cleaned silicon substrate in an amination modification solution for 30 minutes at room temperature to perform an amination modification treatment on the surface of the silicon substrate, after the modification is completed, taking out the silicon substrate and washing it with anhydrous ethanol, and finally drying the silicon substrate in a nitrogen atmosphere;

[0077] The amination-modified solution is an ethanol solution of 3-aminopropyltriethoxysilane (APTES), and the volume fraction of 3-aminopropyltriethoxysilane is 5% based on the total volume of the amination-modified solution;

[0078] The bromine modification treatment specifically includes: firstly immersing the silicon substrate after the amino modification treatment in an active bromine modification solution at room temperature for 30 minutes to perform bromine modification treatment on the surface of the silicon substrate, taking out the silicon substrate after the bromine modification treatment and washing it with anhydrous ethanol, and finally drying the silicon substrate in a nitrogen atmosphere, and storing the silicon substrate after the bromine modification treatment in a nitrogen atmosphere;

[0079] The active bromine modified solution is prepared by dissolving 0.42 mol of triethylamine and 0.37 mol of 2-bromoisobutyryl bromide in 10 mL of dichloromethane in sequence.

[0080] Preparation of S2 deoxygenated water: Freeze ultrapure water at -20°C, take it out, and then thaw it at room temperature. Repeat the freezing and thawing process 3 times to obtain deoxygenated water.

[0081] S3 Preparation of emulsion polymerization liquid: 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate monomer liquid is added to deoxygenated water at a volume fraction of 5% (based on the total volume of the emulsion polymerization liquid), and the mixture is dispersed into an emulsion by oscillating in an ultrasonic instrument for 10 minutes, followed by adding 0.015 mol / L cuprous bromide and 0.025 mol / L 2,2'-bipyridine to obtain the emulsion polymerization liquid; wherein the volume fraction of the perfluoroalkyl methacrylate monomer, the concentration of cuprous bromide and the concentration of 2,2'-bipyridine are all calculated based on the total volume of the emulsion polymerization liquid.

[0082] Preparation of S4 super-hydrophobic surface: The silicon substrate 4 after surface pretreatment is placed flat in the conical reaction flask 2, and then the emulsion polymerization liquid 1 is added into the conical reaction flask 2 to immerse the silicon substrate 4 after surface pretreatment, and then nitrogen is introduced into the conical reaction flask 2 through the nitrogen bottle 3 to carry out emulsion polymerization reaction on the surface of the substrate under a sealed and nitrogen atmosphere, wherein the reaction temperature is room temperature and the time is 12 hours.

[0083] S5 post-treatment: After the reaction is completed, the silicon substrate is taken out, cleaned with water and ethanol in sequence and dried to obtain a super-hydrophobic surface.

[0084] 5 μL of deionized water was placed on the super-hydrophobic surface obtained in Example 1 of the present invention, and the contact angle of the water droplet was measured by a contact angle meter to be as high as 169.7°±1.3°, and the contact angle hysteresis measured by the difference between the advancing angle (advancing contact angle) and the receding angle (receding contact angle) was 0.7°±0.3°. The super-hydrophobic surface obtained in Example 1 of the present invention has such a large contact angle and ultra-low contact angle retardation in the air, proving that it has excellent super-hydrophobicity.

[0085] Example 2

[0086] This embodiment provides a series of hydrophobic surfaces, which are prepared by a preparation method comprising the following specific steps, wherein the process flow chart of the preparation method and the structural schematic diagram of the experimental device used are respectively as shown in Figure 1 and Figure 2 As shown, from Figure 1 and Figure 2 It can be seen that the preparation method comprises:

[0087] S1 surface pretreatment: firstly, the surface of the silicon substrate is cleaned, then the surface of the cleaned silicon substrate is subjected to amino modification, and finally the surface of the substrate subjected to amino modification is subjected to bromine modification to complete the preparation of the surface initiator;

[0088] The cleaning treatment specifically includes: cleaning the silicon substrate with deionized water and ethanol in sequence, and then immersing the cleaned silicon substrate in a Piranha solution, maintaining the temperature at 80° C. for 2 hours, wherein the Piranha solution is a mixed solution prepared according to a volume fraction of 30% hydrogen peroxide and a volume fraction of 70% concentrated sulfuric acid;

[0089] The amination modification treatment specifically includes: firstly immersing the cleaned silicon substrate in an amination modification solution for 30 minutes at room temperature to perform an amination modification treatment on the surface of the silicon substrate, after the modification is completed, taking out the silicon substrate and washing it with anhydrous ethanol, and finally drying the silicon substrate in a nitrogen atmosphere;

[0090] The amination-modified solution is an ethanol solution of 3-aminopropyltriethoxysilane (APTES), and the volume fraction of 3-aminopropyltriethoxysilane is 5% based on the total volume of the amination-modified solution;

[0091] The bromine modification treatment specifically includes: firstly immersing the silicon substrate after the amino modification treatment in an active bromine modification solution at room temperature for 30 minutes to perform bromine modification treatment on the surface of the silicon substrate, taking out the silicon substrate after the bromine modification treatment and washing it with anhydrous ethanol, and finally drying the silicon substrate in a nitrogen atmosphere, and storing the silicon substrate after the bromine modification treatment in a nitrogen atmosphere;

[0092] The active bromine modified solution is prepared by dissolving 0.42 mol of triethylamine and 0.37 mol of 2-bromoisobutyryl bromide in 10 mL of dichloromethane in sequence.

[0093] Preparation of S2 deoxygenated water: Freeze ultrapure water at -20°C, take it out, and then thaw it at room temperature. Repeat the freezing and thawing process 3 times to obtain deoxygenated water.

[0094] S3 Preparation of emulsion polymerization liquid: 2.5% and 0.1% volume fractions (based on the total volume of the emulsion polymerization liquid) of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate monomer liquid are added to deoxygenated water respectively, and the mixture is dispersed into an emulsion by shaking in an ultrasonic instrument for 10 minutes, followed by adding 0.015 mol / L cuprous bromide and 0.025 mol / L 2,2'-bipyridine to obtain the emulsion polymerization liquid; wherein the volume fraction of the perfluoroalkyl methacrylate monomer, the concentration of cuprous bromide and the concentration of 2,2'-bipyridine are all calculated based on the total volume of the emulsion polymerization liquid.

[0095] Preparation of S4 series hydrophobic surface: Place the silicon substrate 4 after surface pretreatment flat in the conical reaction flask 2, then add the emulsion polymerization liquid 1 into the conical reaction flask 2 until the silicon substrate 4 after surface pretreatment is immersed, and then introduce nitrogen into the conical reaction flask 2 through the nitrogen bottle 3 to carry out emulsion polymerization reaction on the surface of the substrate in a sealed and nitrogen atmosphere, wherein the reaction temperature is room temperature.

[0096] S5 post-treatment: After the reaction is completed, the silicon substrate is taken out, cleaned with water and ethanol in sequence and dried to obtain a series of hydrophobic surfaces.

[0097] In this embodiment, the volume fraction of the perfluoroalkyl methacrylate monomer was selected as 2.5 vol.% and 0.1 vol.%, respectively, and the reaction time was 2 h, 4 h and 8 h, respectively. After the reaction was completed, six surfaces with different hydrophobicity were prepared. The reaction conditions in this embodiment and the water drop contact angle data of the hydrophobic surface measured by the contact angle meter are shown in Table 1 below.

[0098] Table 1 Contact angle data of hydrophobic surface corresponding to different monomer concentrations and different reaction times

[0099] 2h 4h 8h 2.5vol.% 118° 133° 161.5° 0.1vol.% 92.1° 111.6° 127.1°

[0100] As can be seen from Table 1 above, Example 2 of the present invention prepared hydrophobic surfaces with different hydrophobicity by controlling the concentration of perfluoroalkyl methacrylate monomer and the reaction time, and as the concentration of perfluoroalkyl methacrylate monomer and the reaction time increase, the hydrophobicity of the obtained hydrophobic surface becomes higher. When the volume fraction of the perfluoroalkyl methacrylate monomer is 2.5 vol.%, and the reaction time is 8 h, the water droplet contact angle of the obtained hydrophobic surface is as high as 161.5°, indicating that it has excellent super hydrophobicity.

[0101] Example 3

[0102] This embodiment provides a hydrophobic surface with a hydrophobicity gradient, which is prepared by a preparation method comprising the following specific steps, wherein the process flow chart of the preparation method and the structural schematic diagram of the experimental device used are respectively as shown in Figure 1 and Figure 2 As shown, from Figure 1 and Figure 3 It can be seen that the preparation method comprises:

[0103] S1 surface pretreatment: firstly, the surface of the silicon substrate is cleaned, then the surface of the cleaned silicon substrate is subjected to amino modification, and finally the surface of the substrate subjected to amino modification is subjected to bromine modification to complete the preparation of the surface initiator;

[0104] The cleaning treatment specifically includes: cleaning the silicon substrate with deionized water and ethanol in sequence, and then immersing the cleaned silicon substrate in a Piranha solution, maintaining the temperature at 80° C. for 2 hours, wherein the Piranha solution is a mixed solution prepared according to a volume fraction of 30% hydrogen peroxide and a volume fraction of 70% concentrated sulfuric acid;

[0105] The amination modification treatment specifically includes: firstly immersing the cleaned silicon substrate in an amination modification solution for 30 minutes at room temperature to perform an amination modification treatment on the surface of the silicon substrate, after the modification is completed, taking out the silicon substrate and washing it with anhydrous ethanol, and finally drying the silicon substrate in a nitrogen atmosphere;

[0106] The amination-modified solution is an ethanol solution of 3-aminopropyltriethoxysilane (APTES), and the volume fraction of 3-aminopropyltriethoxysilane is 5% based on the total volume of the amination-modified solution;

[0107] The bromine modification treatment specifically includes: firstly immersing the silicon substrate after the amino modification treatment in an active bromine modification solution at room temperature for 30 minutes to perform bromine modification treatment on the surface of the silicon substrate, taking out the silicon substrate after the bromine modification treatment and washing it with anhydrous ethanol, and finally drying the silicon substrate in a nitrogen atmosphere, and storing the silicon substrate after the bromine modification treatment in a nitrogen atmosphere;

[0108] The active bromine modified solution is prepared by dissolving 0.42 mol of triethylamine and 0.37 mol of 2-bromoisobutyryl bromide in 10 mL of dichloromethane in sequence.

[0109] Preparation of S2 deoxygenated water: Freeze ultrapure water at -20°C, take it out, and then thaw it at room temperature. Repeat the freezing and thawing process 3 times to obtain deoxygenated water.

[0110] S3 Preparation of emulsion polymerization liquid: 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate monomer liquid is added to deoxygenated water at a volume fraction of 5% (based on the total volume of the emulsion polymerization liquid), and the mixture is dispersed into an emulsion by oscillating in an ultrasonic instrument for 10 minutes, followed by adding 0.015 mol / L cuprous bromide and 0.025 mol / L 2,2'-bipyridine to obtain the emulsion polymerization liquid; wherein the volume fraction of the perfluoroalkyl methacrylate monomer, the concentration of cuprous bromide and the concentration of 2,2'-bipyridine are all calculated based on the total volume of the emulsion polymerization liquid.

[0111] S4 Preparation of a hydrophobic surface with a hydrophobicity gradient: The emulsion prepared in S3 is allowed to stand in a cylindrical long bottle 5 for 24 hours, and the perfluoroalkyl methacrylate monomer therein forms a concentration gradient under the action of gravity. Then, the rectangular silicon substrate 4 after surface pretreatment is slowly placed vertically into the cylindrical long bottle 5 containing the emulsion, and then nitrogen is introduced into the cylindrical long bottle 5 through the nitrogen bottle 3 to carry out an emulsion polymerization reaction on the surface of the silicon substrate under a sealed and nitrogen atmosphere, wherein the reaction time is controlled to be 8 hours.

[0112] S5 post-treatment: After the reaction is completed, the silicon substrate is taken out, and is cleaned and dried with water and ethanol in sequence to obtain a hydrophobic surface with a hydrophobicity gradient.

[0113] Five 5 μL deionized water drops were placed at different lateral positions on the hydrophobic surface prepared in Example 3 of the present invention, and the contact angle measured from left to right using a contact angle meter showed an obvious downward trend, as shown in FIG. Figure 4a-4e As shown, from Figure 4a-4eAs can be seen from the figure, the contact angles from left to right are 164.7°, 158.5°, 149.3°, 130.8° and 117.7°, respectively. The change in contact angle proves that Example 3 of the present invention has prepared a hydrophobic surface with a controllable hydrophobic gradient.

[0114] Test Example 1

[0115] This test example is respectively for the super hydrophobic surface with a contact angle of 164.7° provided in Example 3 of the present invention ( Figure 4a ) were subjected to SEM analysis and EDS analysis, and the obtained SEM images are shown in Figure 5a and Figure 5b As shown, the EDS image of the fluorine element on the super hydrophobic surface is as follows Figure 5c As shown. Figure 5a It can be seen that the substrate surface is covered with a large number of particles; Figure 5b The enlarged SEM image in the middle shows that the average size of the particles is around a few hundred nanometers; Figure 5c The distribution of fluorine elements on the hydrophobic surface is shown in the figure. The above morphological characteristics of the super-hydrophobic surface indicate that the hydrophobic mechanism of the super-hydrophobic surface is as follows: a substrate with a surface initiator attached is placed in an emulsion polymerization liquid, and the perfluoroalkyl methacrylate monomer droplets dispersed in the emulsion polymerization liquid diffuse to the surface of the substrate, and under the action of the surface initiator and the catalyst, a free radical polymerization reaction of the perfluoroalkyl methacrylate monomer attached to the surface of the substrate is initiated to generate hydrophobic polymer solid particles, thereby making the hydrophobic surface have excellent hydrophobicity. Based on this, the present invention can prepare hydrophobic surfaces with different hydrophobicities and hydrophobic surfaces with a hydrophobic gradient by changing the density of the perfluoroalkyl methacrylate monomer and maintaining the density difference.

[0116] Test Example 2

[0117] This test example tests the surface stability of the super-hydrophobic surface prepared in Example 1 of the present invention, specifically comprising: firstly, the super-hydrophobic surface prepared in Example 1 is placed in a high salinity (3 mol / m 3 The samples were stored under the conditions of NaCl) and high temperature (air atmosphere, temperature 120°C) for 2 hours, and then the contact angle was measured by contact angle meter in the pH range of 0-14. The experimental results are shown in the figure. Figure 6 As shown. Figure 6 It can be seen that after the super-hydrophobic surface prepared in Example 1 of the present invention is treated under the above extreme conditions, its contact angle is still greater than 165°, and the contact angle hysteresis is less than 1°, which indicates that the super-hydrophobic surface has excellent surface stability.

[0118] Test Example 3

[0119] This test example is for the super hydrophobic surface with a contact angle of 164.7° provided in Example 3 of the present invention ( Figure 4a ) to conduct surface antifouling test, such as Figure 7a As shown in FIG. 1 , a superhydrophobic surface contaminated with kaolin powder is first placed on a disk to form an inclined surface, such as Figure 7b-7c As shown, water drops are dripped from the high end of the inclined surface. Since the surface has super hydrophobicity, the water drops roll down smoothly along the inclined surface and remove the kaolin dirt from the surface, and the surface is restored to cleanliness. This shows that the super hydrophobic surface prepared in Example 3 of the present invention has excellent self-cleaning ability.

[0120] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the protection scope of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other and with each other, and with each other.

Claims

1. A method for preparing a hydrophobic surface, characterized in that: The preparation method comprises: S1 surface pretreatment: cleaning, amino modification and bromine modification are performed on the surface of the substrate in sequence; S2 emulsion polymerization liquid preparation: perfluoroalkyl methacrylate monomer and catalyst are mixed with deoxygenated water and dispersed uniformly to obtain emulsion polymerization liquid; S3: Preparation of hydrophobic surface: placing the substrate with surface pretreatment obtained in S1 into an emulsion polymerization solution to perform an emulsion polymerization reaction on the surface of the substrate; S4 post-treatment: After the reaction is completed, the substrate is taken out, and then the substrate is cleaned and dried in sequence to obtain the hydrophobic surface.

2. The preparation method according to claim 1, characterized in that: When the substrate is a non-metallic substrate, the cleaning process in S1 includes: firstly cleaning the substrate with deionized water and ethanol in sequence, and then immersing the substrate in a Piranha solution; Preferably, the Piranha solution is a mixed solution prepared by hydrogen peroxide and concentrated sulfuric acid with a volume fraction of hydrogen peroxide being 15-30%; Also preferably, the soaking is soaking at 70-120° C. for 1-3 hours; When the substrate is a metal substrate, the cleaning process in S1 includes: firstly immersing the substrate in a cleaning solution, taking out the substrate and cleaning it with anhydrous ethanol, and finally drying the substrate in an inert atmosphere; Also preferably, the cleaning solution is a mixed solution prepared by hydrogen peroxide, ammonia water and deionized water in volume fractions of 10-20%, 10-20% and 60-80% respectively; Also preferably, the substrate is immersed in the cleaning solution at a temperature of 70-90° C. for 0.5-2 h.

3. The preparation method according to claim 1 or 2, characterized in that: The amination modification treatment in S1 includes: firstly immersing the cleaned substrate in an amination modification solution to perform an amination modification treatment on the surface of the substrate, taking out the substrate after the modification and washing it with anhydrous ethanol, and finally drying the substrate in an inert atmosphere; Preferably, the amino-modified solution is an alcohol solution containing aminosilicone and / or its isomers; More preferably, in the amination-modified solution, the volume fraction of aminosilicone and / or its isomers is 4%-6% based on the total volume of the amination-modified solution; Also preferably, the temperature of the amination modification treatment is 20-30°C.

4. The preparation method according to claim 1 or 2, characterized in that: The bromine modification treatment in S1 includes: firstly immersing the substrate after the amino modification treatment in an active bromine modification solution to perform bromine modification treatment on the surface of the substrate, taking out the substrate after the bromine modification treatment and washing it with anhydrous ethanol, and finally drying the substrate in an inert atmosphere; Preferably, the solute of the active bromine modified solution comprises 2-bromoisobutyryl bromide and triethylamine, wherein the molar concentration of 2-bromoisobutyryl bromide is 40-45 mol / L, and the molar concentration of triethylamine is 35-40 mol / L; Also preferably, the temperature of the bromine modification treatment is room temperature.

5. The preparation method according to claim 1 or 2, characterized in that: The dissolved oxygen content in the deoxygenated water in S2 is less than 0.1 mg / L; Preferably, the deoxygenated water is prepared by a method comprising the following steps: Freezing ultrapure water into ice in a temperature environment not higher than -20°C and then thawing it at 15-25°C, repeating the freezing and thawing process multiple times to obtain the deoxygenated water; More preferably, the number of repetitions is no less than 3 times.

6. The preparation method according to claim 1 or 2, characterized in that: In S2, the perfluoroalkyl methacrylate monomer includes one or a combination of 2,2,2-trifluoroethyl methacrylate, 2-(perfluorooctyl)ethyl methacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl methacrylate and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate; Preferably, in the emulsion polymer of S2, the volume fraction of the perfluoroalkyl methacrylate monomer is in the range of 0.1%-5% based on the total volume of the emulsion polymer, and more preferably, the volume fraction of the perfluoroalkyl methacrylate monomer is greater than 2% and less than or equal to 5%; Also preferably, the catalyst comprises cuprous ions, and the concentration of the cuprous ions is 0.01-0.02 mol / L based on the total volume of the emulsion polymer solution; More preferably, the emulsion polymer solution further comprises a stabilizer, and the concentration of the stabilizer is 0.02-0.03 mol / L based on the total volume of the emulsion polymer solution.

7. The preparation method according to claim 1, characterized in that: In S3, the emulsion polymerization reaction is carried out under sealed and inert atmosphere conditions; Preferably, the emulsion polymerization reaction time is 1-12 h, more preferably, the emulsion polymerization reaction time is 8-12 h.

8. The preparation method according to claim 1 or 7, characterized in that: In S3, the substrate with the surface pre-treated obtained in S1 is placed vertically into an emulsion polymerization solution and an emulsion polymerization reaction is performed on the surface of the substrate to obtain a hydrophobic surface with a hydrophobicity gradient on the surface of the substrate.

9. A hydrophobic surface, characterized in that The hydrophobic surface is prepared by the method for preparing a hydrophobic surface according to any one of claims 1 to 8; Preferably, the hydrophobic surface is a superhydrophobic surface.

10. Application of the hydrophobic surface according to claim 9 in oil-water separation, self-cleaning surface, antifouling surface, antifreeze surface, metal corrosion, battery, membrane engineering, microfluidics or droplet manipulation.

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