Thin film capable of regulating, controlling, subdividing or directionally collecting liquid drops as well as preparation method and application of thin film

Abstract

The invention discloses a thin film capable of regulating and controlling subdivision or directional collection of liquid drops and a preparation method and application thereof.The thin film sequentially comprises a base film layer and a hydrophobic layer from bottom to top, a plurality of shear marks are arranged on the thin film at intervals, the shear marks penetrate through the thin film, and the shear marks can be warped or closed along with change of stress of the thin film. The thin film can realize switching between subdivision and directional transportation of liquid drops.

Description

Technical Field

[0001] The present invention belongs to the technical field of droplet processing, and particularly relates to a film capable of controlling the subdivision or directionally collecting droplets, and a preparation method and application thereof. Background Art

[0002] The ability to subdivide a given volume of liquid into smaller units—creating a spray—is of great significance in fields such as agriculture, coatings and paints, internal combustion engines, mining and waste disposal, medicine, and meteorology. The transformation from a large liquid volume to a small droplet form occurs when the liquid is affected by gravity as it falls, surface tension is disrupted by impact, or bubbles within the droplet burst. In industrial applications, this process is typically achieved through an atomizer, which applies a high relative velocity between the liquid to be atomized and the surrounding gas. These techniques typically involve different instabilities (such as Rayleigh-Plateau, Rayleigh-Taylor, and Kelvin-Helmholtz) that result in liquid spraying and sheet-like breakup, and may also involve electrostatic or ultrasonic instabilities. Existing research methods include using a mesh structure to atomize droplets by impacting the mesh, resulting in the propagation of some liquid as droplets up to 1,000 times smaller than the original droplets. However, such mesh structures cannot achieve directional droplet movement and collection, failing to meet diverse requirements. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a film capable of controlling the subdivision or directional collection of droplets, as well as a preparation method and application thereof, wherein the film can switch between subdivision and directional transport of droplets.

[0004] The above technical objectives of the present invention are achieved through the following technical solutions:

[0005] A film capable of controlling the subdivision or directionally collecting droplets comprises, from bottom to top, a base film layer and a hydrophobic layer. The film is provided with a plurality of cuts at intervals, the cuts running through the film, and the cuts can warp or close as the force applied to the film changes.

[0006] Preferably, the cut is a linear cut, the length of the cut is 1-5 mm, the horizontal spacing between multiple cuts is 0.1-1.0 mm, and the vertical spacing between multiple cuts is 0.1-1.0 mm. This structure can disperse the stress generated during cyclic stretching to the entire film, thereby avoiding stress concentration.

[0007] Preferably, the length of the cut is 1.6 mm to 3.2 mm.

[0008] Preferably, the warping angle of the cut is 0-85°.

[0009] Definition of warping angle: After a linear cut is introduced into the film, the film will deform under uniaxial tension, causing the cut to open. The rigid units around the cut (uncut parts) rotate out of the plane due to unbalanced force, forming a warping angle. The warping angle increases nonlinearly with the increase of the stretching degree. The length of the cut is measured as L. c The distance between the horizontal cuts is δ, the distance between the vertical cuts is b, and the maximum tilting angle is θ max , let R1=L c / δ,R2=L c / b, then θ max =tan -1 [(R1R2-R2) / 2R1].

[0010] Preferably, the spacing between the cuts in the transverse direction is the same as the spacing between the cuts in the longitudinal direction.

[0011] Preferably, the transverse spacing between the cuts is 0.15 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm or 1.0 mm, and the longitudinal spacing between the cuts is 0.15 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm or 1.0 mm.

[0012] Preferably, the base film layer includes at least one of a polyimide film, a PE film and a PET film.

[0013] Preferably, the base film layer is made of a polyimide film.

[0014] Preferably, a metal support layer is further provided between the base film layer and the hydrophobic layer.

[0015] Preferably, the metal support layer comprises a copper film layer and a silver film layer stacked sequentially from bottom to top.

[0016] Preferably, the copper film layer has a thickness of 50-300 nm.

[0017] Further preferably, the thickness of the copper film layer is 100 nm.

[0018] Preferably, the hydrophobic layer is a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer.

[0019] Preferably, the contact angle of the surface of the hydrophobic layer is greater than or equal to 150°.

[0020] The method for preparing a film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps: cutting spaced cuts on a base film layer, then cleaning and drying the base film layer and immersing the base film layer in a hydrophobic agent to form a hydrophobic layer on the surface, and then cleaning and drying to obtain the film.

[0021] Preferably, the method for preparing the film capable of controlling the subdivision or directionally collecting droplets comprises the following steps:

[0022] (1) depositing a first metal onto the surface of the base film layer by a sputtering device to form a first metal support layer;

[0023] (2) using the material sputtered in step (1) as a cutting object, cutting it to form spaced cuts, wherein the cuts penetrate the base film layer and the first metal support layer, and then cleaning and drying;

[0024] (3) placing the dried material in step (2) in a soluble salt solution containing a second metal ion for immersion, so that the second metal ion is deposited on the surface of the first metal support layer to form a second metal support layer, and then washing and drying;

[0025] (4) Immersing the dried material in step (3) in a hydrophobic agent to form a hydrophobic layer on the surface of the second metal support layer, and then washing and drying to obtain the film.

[0026] Preferably, in step (1), the base film constituting the base film layer is ultrasonically cleaned in alcohol, acetone and isopropyl alcohol solutions in sequence before sputtering.

[0027] Preferably, in step (1), the sputtering target used for the sputtering is a copper target.

[0028] Preferably, in step (2), the equipment used for cutting is a paper cutter or a laser cutter with an accuracy of less than 0.01 mm.

[0029] Preferably, in step (2), the cleaning is performed by ultrasonic cleaning in alcohol, acetone, isopropanol and water in sequence, and the drying is performed under an inert gas flow.

[0030] Preferably, in step (3), the soluble salt solution is an AgNO3 solution, the concentration of the soluble salt solution is 0.005-0.02 mol / L, and the immersion time is 30-100 s. Silver nitrate and copper undergo a replacement reaction to form a silver film layer on the copper film layer. The thickness of the silver film layer ranges from 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the resulting silver film has an uneven rough surface. Its micro-nano rough structure is one of the necessary conditions for preparing a superhydrophobic surface.

[0031] Further preferably, in step (3), the concentration of the soluble salt solution is 0.01 mol / L, and the soaking time is 45 s.

[0032] Preferably, in step (3), the material dried in step (2) is first acid-leached to remove the oxide film on the surface, then washed with water, and then immersed in the soluble salt solution.

[0033] Preferably, in step (3), the acid leaching uses an HCl solution with a concentration of 0.005-0.02 mol / L, and the acid leaching time is 5-30 seconds.

[0034] Further preferably, in step (3), the acid leaching uses an HCl solution with a concentration of 0.01 mol / L, and the acid leaching time is 45 seconds.

[0035] Preferably, in step (3), the cleaning is performed by rinsing with water, and the drying is performed under an inert gas flow.

[0036] Preferably, in step (4), the hydrophobic agent is a dichloromethane solution containing 0.0005-0.002 mol of 1H,1H,2H,2H-perfluorodecanethiol.

[0037] Further preferably, in step (4), the hydrophobic agent is a dichloromethane solution containing 1H,1H,2H,2H-perfluorodecanethiol, and the concentration of the 1H,1H,2H,2H-perfluorodecanethiol in the hydrophobic agent is 0.001 mol / L. The silver on the silver film layer can form a covalent bond with the thiol group of the 1H,1H,2H,2H-perfluorodecanethiol, thereby making the resulting superhydrophobic layer more stable and less likely to fall off.

[0038] Preferably, in step (4), the cleaning is performed using dichloromethane, and the drying is performed by placing the surface of the sample at room temperature to dry the surface.

[0039] The application of the film capable of controllably subdividing or directionally collecting droplets as described above in droplet subdivision or droplet transportation.

[0040] Preferably, the cut is in a closed state in a natural state, so that the film can be used for directional movement and collection of droplets. Stress can be applied to the film to cause the cut to warp, so that the film can be used for droplet subdivision.

[0041] The beneficial effects of the present invention are:

[0042] (1) The film of the present invention that can be controlled to subdivide or directionally collect droplets can switch between the closed and open cuts by changing the force on the film, thereby realizing the switch between the directional movement and collection of droplets and the subdivision of droplets, thereby meeting different needs.

[0043] (2) The deformation of the film structure of the present invention is achieved through the cut marks, and the material itself will not be damaged before being stretched to the maximum angle. Therefore, it can be compatible with materials with high stiffness, poor toughness and poor cyclic stretchability, avoiding material yielding or breaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of a cross section of a film according to Example 1 of the present invention;

[0045] Figure 2 Schematic diagram of the upper surface of the film of Example 1 of the present invention;

[0046] Figure 3 This is a superimposed real shot of the directional movement of droplets when the film of Example 2 of the present invention is used in a droplet impact test;

[0047] Figure 4 This is a real shot of the film of Example 2 of the present invention being used in a droplet impact test when the Weber number is equal to 52;

[0048] Figure 5 This is a photo of the film of Example 2 of the present invention being used in a droplet impact test when the Weber number is equal to 71;

[0049] Figure 6 This is a curve diagram showing the change of the dimensionless rebound velocity of the droplet as a function of the impact velocity when the film of Example 2 of the present invention is used in a droplet impact test.

[0050] Figure 7 This is a graph showing the change in the critical velocity of a droplet as a function of the tilting angle of the cut when the film of Example 2 of the present invention is used in a droplet impact test.

[0051] Reference numerals:

[0052] 100. Base film layer; 200. Copper film layer; 300. Silver film layer; 400. Hydrophobic layer; 500. Cutting mark. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to specific embodiments.

[0054] Example 1:

[0055] Thin films that can be controlled to subdivide or collect droplets in a directional manner, such as Figure 1 and Figure 2As shown, the film comprises, from bottom to top, a base film layer 100, a metal support layer and a hydrophobic layer 400, a plurality of cuts 500 are arranged at intervals on the film, the cuts 500 penetrate the film, and the cuts 500 can warp or close as the force on the film changes. The length of the cuts 500 is 1.6 mm, the horizontal spacing between the cuts 500 is 0.15 mm, and the vertical spacing between the cuts 500 is 0.15 mm. The base film layer 100 is composed of a polyimide film, and the metal support layer comprises, from bottom to top, a copper film layer 200 and a silver film layer 300 stacked in sequence, the thickness of the copper film layer 200 is 100 nm, and the hydrophobic layer 400 is a 1H, 1H, 2H, 2H-perfluorodecanethiol hydrophobic layer, and the contact angle of the surface of the hydrophobic layer 400 is 150°.

[0056] The method for preparing the film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps:

[0057] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropyl alcohol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface. A copper target was loaded into a sputtering device. Copper atoms or ions were deposited on the surface of the polyimide base film layer under the action of discharge to form a 100 nm thick copper film layer 200;

[0058] (2) Cutting the cut 500 using the sputtered material in step (1) as the cutting object, and drawing a drawing according to the size data of the cut 500, wherein the length of the cut 500 is 1.6 mm, the horizontal spacing between the cuts 500 is 0.15 mm, and the vertical spacing between the cuts 500 is 0.15 mm. Leave 2 cm at both ends of the film as a fixed part, and import the drawing into a commercial paper cutter or laser cutter with an accuracy of less than 0.01 mm to cut the cut 500 through the base film layer 100 and the copper film layer 200;

[0059] (3) The cut material in step (2) was ultrasonically cleaned in alcohol, acetone, isopropyl alcohol, and deionized water for 15 minutes, respectively, and then dried under a nitrogen flow;

[0060] (4) immersing the dried polyimide copper film in step (3) in a 0.01 mol / L HCl solution for 10 seconds to remove the oxide film on the surface, quickly rinsing it with deionized water three times, and then immersing it in a 0.01 mol / L AgNO3 solution for 45 seconds to deposit silver nanostructures on the surface of the material to obtain a silver film layer 300. The thickness of the silver film layer is in the range of 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the generated silver film has an uneven rough surface, so that a polyimide-copper-silver film is formed. The film is rinsed with deionized water three times and dried under a nitrogen flow;

[0061] (5) Immersing the film dried in step (4) in a dichloromethane solution containing 0.001 mol / L 1H,1H,2H,2H-perfluorodecanethiol for 30 minutes to graft a fluorinated self-assembled monolayer on the surface, thereby forming a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer 400 on the surface of the silver film layer 300;

[0062] (6) The film obtained in step (5) was washed with dichloromethane five times and allowed to stand at room temperature to completely dry its surface to obtain a film.

[0063] Example 2:

[0064] A film capable of controlling the subdivision or directionally collecting droplets comprises, from bottom to top, a base film layer, a metal support layer, and a hydrophobic layer. The film is provided with a plurality of cuts at intervals, the cuts running through the film, and the cuts can warp or close as the force on the film changes. The length of the cuts is 1.6 mm, the horizontal spacing between the cuts is 0.3 mm, and the vertical spacing between the cuts is 0.3 mm. The base film layer is composed of a polyimide film, and the metal support layer comprises, from bottom to top, a copper film layer and a silver film layer stacked in sequence, the thickness of the copper film layer being 100 nm. The hydrophobic layer is a 1H, 1H, 2H, 2H-perfluorodecanethiol hydrophobic layer, and the contact angle of the hydrophobic layer surface is 155°.

[0065] The method for preparing the film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps:

[0066] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropanol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface. A copper target was loaded into a sputtering device, and copper atoms or ions were deposited on the surface of the polyimide base film layer under the action of discharge to form a 100 nm thick copper film layer.

[0067] (2) Cutting the material sputtered in step (1) as the cutting object, and drawing a drawing according to the size data of the cut, wherein the length of the cut is 1.6 mm, the spacing between the cuts is 0.3 mm in the horizontal direction, and the spacing between the cuts is 0.3 mm in the vertical direction. Leave 2 cm at both ends of the film as a fixed part, and import the drawing into a commercial paper cutter or laser cutter with an accuracy of less than 0.01 mm for cutting, and the cut passes through the base film layer and the copper film layer;

[0068] (3) The cut material in step (2) was ultrasonically cleaned in alcohol, acetone, isopropyl alcohol, and deionized water for 15 minutes, respectively, and then dried under a nitrogen flow;

[0069] (4) immersing the dried polyimide copper film in step (3) in a 0.01 mol / L HCl solution for 10 seconds to remove the oxide film on the surface, quickly rinsing it with deionized water three times, and then immersing it in a 0.01 mol / L AgNO3 solution for 45 seconds to deposit silver nanostructures on the surface of the material to obtain a silver film layer. The thickness of the silver film layer is in the range of 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the generated silver film has an uneven rough surface, so that a polyimide-copper-silver film is formed. The film is rinsed with deionized water three times and dried under a nitrogen flow;

[0070] (5) immersing the film dried in step (4) in a dichloromethane solution containing 0.001 mol / L 1H,1H,2H,2H-perfluorodecanethiol for 30 minutes to graft a fluorinated self-assembled monolayer on the surface, thereby forming a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer on the surface of the silver film;

[0071] (6) The film obtained in step (5) was washed with dichloromethane five times and allowed to stand at room temperature to completely dry its surface to obtain a film.

[0072] Example 3:

[0073] A film that can be controlled to subdivide or directionally collect droplets. The film comprises, from bottom to top, a base film layer, a metal support layer, and a hydrophobic layer. Multiple cuts are arranged at intervals on the film, and the cuts penetrate the film. The cuts can warp or close as the force on the film changes. The length of the cuts is 3.2 mm, the spacing between the cuts is 0.5 mm in the horizontal direction, and the spacing between the cuts is 0.5 mm in the vertical direction. The base film layer is composed of a polyimide film, and the metal support layer comprises, from bottom to top, a copper film layer and a silver film layer stacked in sequence. The thickness of the copper film layer is 100 nm. The hydrophobic layer is a 1H, 1H, 2H, 2H-perfluorodecanethiol hydrophobic layer, and the contact angle of the hydrophobic layer surface is 158°.

[0074] The method for preparing the film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps:

[0075] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropanol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface. A copper target was loaded into a sputtering device, and copper atoms or ions were deposited on the surface of the polyimide base film layer under the action of discharge to form a 100 nm thick copper film layer.

[0076] (2) Cutting the material sputtered in step (1) as the cutting object, and drawing a drawing according to the size data of the cut, wherein the length of the cut is 3.2 mm, the spacing between the cuts is 0.5 mm in the horizontal direction, and the spacing between the cuts is 0.5 mm in the vertical direction. Leave 2 cm at both ends of the film as a fixed part, and import the drawing into a commercial paper cutter or laser cutter with an accuracy of less than 0.01 mm for cutting, and the cut passes through the base film layer and the copper film layer;

[0077] (3) The cut material in step (2) was ultrasonically cleaned in alcohol, acetone, isopropyl alcohol, and deionized water for 15 minutes, respectively, and then dried under a nitrogen flow;

[0078] (4) immersing the dried polyimide copper film in step (3) in a 0.01 mol / L HCl solution for 10 seconds to remove the oxide film on the surface, quickly rinsing it with deionized water three times, and then immersing it in a 0.01 mol / L AgNO3 solution for 45 seconds to deposit silver nanostructures on the surface of the material to obtain a silver film layer. The thickness of the silver film layer is in the range of 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the generated silver film has an uneven rough surface, so that a polyimide-copper-silver film is formed. The film is rinsed with deionized water three times and dried under a nitrogen flow;

[0079] (5) immersing the film dried in step (4) in a dichloromethane solution containing 0.001 mol / L 1H,1H,2H,2H-perfluorodecanethiol for 30 minutes to graft a fluorinated self-assembled monolayer on the surface, thereby forming a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer on the surface of the silver film;

[0080] (6) The film obtained in step (5) was washed with dichloromethane five times and allowed to stand at room temperature to completely dry its surface to obtain a film.

[0081] Example 4:

[0082] A film capable of controlling the subdivision or directionally collecting droplets comprises, from bottom to top, a base film layer, a metal support layer, and a hydrophobic layer. The film is provided with a plurality of cuts at intervals, the cuts running through the film, and the cuts can warp or close as the force on the film changes. The length of the cuts is 3.2 mm, the horizontal spacing between the cuts is 0.7 mm, and the vertical spacing between the cuts is 0.7 mm. The base film layer is composed of a polyimide film, and the metal support layer comprises, from bottom to top, a copper film layer and a silver film layer stacked in sequence, the thickness of the copper film layer being 100 nm. The hydrophobic layer is a 1H, 1H, 2H, 2H-perfluorodecanethiol hydrophobic layer, and the contact angle of the hydrophobic layer surface is 161°.

[0083] The method for preparing the film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps:

[0084] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropanol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface. A copper target was loaded into a sputtering device, and copper atoms or ions were deposited on the surface of the polyimide base film layer under the action of discharge to form a 100 nm thick copper film layer.

[0085] (2) Cutting the material sputtered in step (1) as the cutting object, and drawing a drawing according to the size data of the cut, wherein the length of the cut is 3.2 mm, the spacing between the cuts is 0.7 mm in the horizontal direction, and the spacing between the cuts is 0.7 mm in the vertical direction. Leave 2 cm at both ends of the film as a fixed part, and import the drawing into a paper cutter or laser cutter with an accuracy of less than 0.01 mm on the market for cutting, and the cut passes through the base film layer and the copper film layer;

[0086] (3) The cut material in step (2) was ultrasonically cleaned in alcohol, acetone, isopropyl alcohol, and deionized water for 15 minutes, respectively, and then dried under a nitrogen flow;

[0087] (4) immersing the dried polyimide copper film in step (3) in a 0.01 mol / L HCl solution for 10 seconds to remove the oxide film on the surface, quickly rinsing it with deionized water three times, and then immersing it in a 0.01 mol / L AgNO3 solution for 45 seconds to deposit silver nanostructures on the surface of the material to obtain a silver film layer. The thickness of the silver film layer is in the range of 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the generated silver film has an uneven rough surface, so that a polyimide-copper-silver film is formed. The film is rinsed with deionized water three times and dried under a nitrogen flow;

[0088] (5) immersing the film dried in step (4) in a dichloromethane solution containing 0.001 mol / L 1H,1H,2H,2H-perfluorodecanethiol for 30 minutes to graft a fluorinated self-assembled monolayer on the surface, thereby forming a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer on the surface of the silver film;

[0089] (6) The film obtained in step (5) was washed with dichloromethane five times and allowed to stand at room temperature to completely dry its surface to obtain a film.

[0090] Example 5:

[0091] A film that can be controlled to subdivide or directionally collect droplets. The film comprises, from bottom to top, a base film layer, a metal support layer, and a hydrophobic layer. Multiple cuts are arranged at intervals on the film, and the cuts penetrate the film. The cuts can warp or close as the force on the film changes. The length of the cuts is 3.2 mm, the horizontal spacing between the cuts is 0.9 mm, and the vertical spacing between the cuts is 0.9 mm. The base film layer is composed of a polyimide film, and the metal support layer comprises, from bottom to top, a copper film layer and a silver film layer stacked in sequence. The thickness of the copper film layer is 100 nm. The hydrophobic layer is a 1H, 1H, 2H, 2H-perfluorodecanethiol hydrophobic layer, and the contact angle of the hydrophobic layer surface is 169°.

[0092] The method for preparing the film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps:

[0093] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropanol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface. A copper target was loaded into a sputtering device, and copper atoms or ions were deposited on the surface of the polyimide base film layer under the action of discharge to form a 100 nm thick copper film layer.

[0094] (2) Cutting the material sputtered in step (1) as the cutting object, and drawing a drawing according to the size data of the cut, wherein the length of the cut is 3.2 mm, the spacing between the cuts is 0.9 mm in the horizontal direction, and the spacing between the cuts is 0.9 mm in the vertical direction. Leave 2 cm at both ends of the film as a fixed part, and import the drawing into a commercial paper cutter or laser cutter with an accuracy of less than 0.01 mm for cutting, and the cut passes through the base film layer and the copper film layer;

[0095] (3) The cut material in step (2) was ultrasonically cleaned in alcohol, acetone, isopropyl alcohol, and deionized water for 15 minutes, respectively, and then dried under a nitrogen flow;

[0096] (4) immersing the dried polyimide copper film in step (3) in a 0.01 mol / L HCl solution for 10 seconds to remove the oxide film on the surface, quickly rinsing it with deionized water three times, and then immersing it in a 0.01 mol / L AgNO3 solution for 45 seconds to deposit silver nanostructures on the surface of the material to obtain a silver film layer. The thickness of the silver film layer is in the range of 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the generated silver film has an uneven rough surface, so that a polyimide-copper-silver film is formed. The film is rinsed with deionized water three times and dried under a nitrogen flow;

[0097] (5) immersing the film dried in step (4) in a dichloromethane solution containing 0.001 mol / L 1H,1H,2H,2H-perfluorodecanethiol for 30 minutes to graft a fluorinated self-assembled monolayer on the surface, thereby forming a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer on the surface of the silver film;

[0098] (6) The film obtained in step (5) was washed with dichloromethane five times and allowed to stand at room temperature to completely dry its surface to obtain a film.

[0099] Example 6:

[0100] A film capable of controlling the subdivision or directionally collecting droplets comprises, from bottom to top, a base film layer, a metal support layer, and a hydrophobic layer. The film is provided with a plurality of cuts at intervals, the cuts running through the film, and the cuts can warp or close as the force on the film changes. The length of the cuts is 3.2 mm, the spacing between the cuts is 1.0 mm in the horizontal direction, and the spacing between the cuts is 1.0 mm in the vertical direction. The base film layer is composed of a polyimide film, and the metal support layer comprises, from bottom to top, a copper film layer and a silver film layer stacked in sequence, the thickness of the copper film layer being 100 nm. The hydrophobic layer is a 1H, 1H, 2H, 2H-perfluorodecanethiol hydrophobic layer, and the contact angle of the hydrophobic layer surface is 172°.

[0101] The method for preparing the film capable of controlling the subdivision or directionally collecting droplets as described above comprises the following steps:

[0102] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropanol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface. A copper target was loaded into a sputtering device, and copper atoms or ions were deposited on the surface of the polyimide base film layer under the action of discharge to form a 100 nm thick copper film layer.

[0103] (2) Cutting the material sputtered in step (1) as the cutting object, and drawing a drawing according to the size data of the cut, wherein the length of the cut is 3.2 mm, the spacing between the cuts is 1.0 mm in the horizontal direction, and the spacing between the cuts is 1.0 mm in the vertical direction. Leave 2 cm at both ends of the film as a fixed part, and import the drawing into a commercial paper cutter or laser cutter with an accuracy of less than 0.01 mm for cutting, and the cut passes through the base film layer and the copper film layer;

[0104] (3) The cut material in step (2) was ultrasonically cleaned in alcohol, acetone, isopropyl alcohol, and deionized water for 15 minutes, respectively, and then dried under a nitrogen flow;

[0105] (4) immersing the dried polyimide copper film in step (3) in a 0.01 mol / L HCl solution for 10 seconds to remove the oxide film on the surface, quickly rinsing it with deionized water three times, and then immersing it in a 0.01 mol / L AgNO3 solution for 45 seconds to deposit silver nanostructures on the surface of the material to obtain a silver film layer. The thickness of the silver film layer is in the range of 10 nanometers to 10 microns. Due to the different activities of the reaction sites, the generated silver film has an uneven rough surface, so that a polyimide-copper-silver film is formed. The film is rinsed with deionized water three times and dried under a nitrogen flow;

[0106] (5) immersing the film dried in step (4) in a dichloromethane solution containing 0.001 mol / L 1H,1H,2H,2H-perfluorodecanethiol for 30 minutes to graft a fluorinated self-assembled monolayer on the surface, thereby forming a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer on the surface of the silver film;

[0107] (6) The film obtained in step (5) was washed with dichloromethane five times and allowed to stand at room temperature to completely dry its surface to obtain a film.

[0108] Comparative Example 1: (Compared to Example 2, the only difference is that the film does not contain a metal support layer and a hydrophobic layer)

[0109] A film is a polyimide film with multiple cuts arranged at intervals. The cuts penetrate the film and can warp or close as the force on the film changes. The length of the cuts is 1.6 mm, the spacing between the cuts is 0.3 mm in the horizontal direction, and the spacing between the cuts is 0.3 mm in the vertical direction.

[0110] A method for preparing the film as described above comprises the following steps:

[0111] (1) The polyimide film was ultrasonically cleaned in alcohol, acetone, and isopropanol solutions for 15 minutes to remove impurities, oil stains, and oxides on the surface;

[0112] (2) Cutting the material processed in step (1) as the cutting object, drawing a drawing according to the size data of the cut, wherein the length of the cut is 1.6 mm, the spacing between the cuts is 0.3 mm in the horizontal direction, and the spacing between the cuts is 0.3 mm in the vertical direction. 2 cm is left at both ends of the film as a fixed part, and the drawing is introduced into a commercial paper cutter or laser cutter with an accuracy of less than 0.01 mm for cutting, and the cut passes through the polyimide film;

[0113] (3) The cut material in step (2) is ultrasonically cleaned in alcohol, acetone, isopropyl alcohol and deionized water for 15 minutes respectively, and then dried under nitrogen flow.

[0114] A silver film with a rough structure is the first step in preparing a super-hydrophobic surface, otherwise it is impossible to further react and form a hydrophobic layer on it; if the silver film is directly plated on the film surface without using a copper film, there will be no rough structure (the rough structure is produced by the different activity of the reaction sites in the displacement reaction); if only a polyimide film is used in Comparative Document 1, the droplets will stick to the film when they hit the film, and there will be no directional movement or subdivision.

[0115] Test example:

[0116] The two ends of the film prepared in Example 2 were fixed on both sides of the stretching machine, and a camera was fixed at the side view angle to record the change of the tilting angle of the cutting unit under different strains, and at the same time record the morphology of the droplet after it hits the film. Figure 2 As shown, the length of the cut is L c The distance between the horizontal cuts is δ, the distance between the vertical cuts is b, and the maximum tilting angle is θ max , let R1=L c / δ,R2=L c / b, then θ max =tan -1 [(R1R2-R2) / 2R1].

[0117] Test findings:

[0118] 1. When the tilt angle is controlled to 30°, use the syringe pump to set the flow rate to 0.5 ml min -1 To generate droplets of uniform volume, the droplet diameter range is set to 1.8-5.5mm, and the droplet diameter is larger than the length of the cut. The injection needle is fixed on the z-axis precision lifting platform, and the impact height is adjusted to make the droplet impact the film speed range 0-0.5m·s -1 When the droplet moves in one direction toward the tilt of the structural unit, the actual motion picture is shown in Figure 3 In order to increase the contrast, silica sol droplets were used as the shooting object. Figure 3 It can be seen that the droplets will not be subdivided and can be collected in a targeted manner.

[0119] 2. When the droplet diameter range is set to 1.8-5.5mm, the tilt angle is greater than 30° or the speed of the droplet hitting the film is greater than 0.47m·s -1 When the droplet is divided into smaller units, the number and size of subdivisions are only related to the Weber number of the droplet. Figure 4 When the Weber number of the droplet is equal to 52, one droplet is subdivided into 32 smaller droplets; Figure 5 When the Weber number of the droplet is equal to 71, one droplet is subdivided into 53 smaller droplets.

[0120] 3. Take the cut length l = 1.6mm, the drop radius R = 1.95mm, and the tilt angle φ = 30° to calculate the tangential component (Ut) of the rebound velocity under different impact velocities (Ui), and make Ut dimensionless with respect to Ui, as follows: Figure 6 It is an image of Ut / Ui changing with Ui, Figure 6 It can be seen that as the impact velocity increases to the critical velocity (UTC), the tangential component of the rebound velocity gradually increases, and the speed of the directional motion of the droplet increases. This shows that increasing the speed can convert more kinetic energy in the vertical direction into the horizontal direction, which is beneficial to the transportation of droplets. When the speed is greater than the critical speed, the droplets will be subdivided.

[0121] 4. Take the cut length L = 1.6mm, the droplet radius R = 1.95mm, R / L = 1.22, and calculate the curve of the critical speed (UTC) changing with φ under different cut tilting angles (φ), as shown in the figure below. Figure 7 As shown in the figure, as the tilting angle increases, the critical speed gradually decreases. Therefore, according to actual needs, the actual size of the droplet is designed under the same ratio as the implementation case, that is, R / L = 1.22. Based on the current experimental data, the droplet can be directed to move to the subdivided transformation.

[0122] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A film capable of controlling the subdivision or directionally collecting droplets, characterized in that: The film includes a base film layer and a hydrophobic layer from bottom to top. A plurality of cuts are arranged at intervals on the film. The cuts penetrate the film. The cuts can warp or close as the force applied to the film changes.

2. The film capable of controlling the subdivision or directionally collecting droplets according to claim 1, characterized in that: The cuts are linear cuts, the length of the cuts is 1-5 mm, the horizontal spacing between the multiple cuts is 0.1-1.0 mm, and the vertical spacing between the multiple cuts is 0.1-1.0 mm.

3. The thin film capable of controlling the subdivision or directionally collecting droplets according to claim 1, characterized in that: The base film layer includes at least one of a polyimide film, a PE film and a PET film.

4. The film capable of controlling the subdivision or directionally collecting droplets according to claim 1, characterized in that: A metal support layer is further provided between the base film layer and the hydrophobic layer.

5. The film capable of controlling the subdivision or directionally collecting droplets according to claim 4, characterized in that: The metal support layer includes a copper film layer and a silver film layer stacked in sequence from bottom to top.

6. The thin film capable of controlling the subdivision or directionally collecting droplets according to claim 1, characterized in that: The hydrophobic layer is a 1H,1H,2H,2H-perfluorodecanethiol hydrophobic layer.

7. The film capable of controlling the subdivision or directionally collecting droplets according to claim 1, characterized in that: The contact angle of the surface of the hydrophobic layer is greater than or equal to 150°.

8. The method for preparing a thin film capable of controlling the subdivision or directionally collecting droplets according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: cutting the base film layer to form spaced cuts, then cleaning and drying the base film layer, immersing the base film layer in a hydrophobic agent to form a hydrophobic layer on the surface, and cleaning and drying the base film to obtain the film.

9. The method for preparing a thin film capable of controlling the subdivision or directionally collecting droplets according to claim 8, characterized in that: The following steps are involved: (1) depositing a first metal onto the surface of the base film layer by a sputtering device to form a first metal support layer; (2) using the material sputtered in step (1) as a cutting object, cutting it to form spaced cuts, wherein the cuts penetrate the base film layer and the first metal support layer, and then cleaning and drying; (3) placing the dried material in step (2) in a soluble salt solution containing a second metal ion for immersion, so that the second metal ion is deposited on the surface of the first metal support layer to form a second metal support layer, and then washing and drying; (4) Immersing the dried material in step (3) in a hydrophobic agent to form a hydrophobic layer on the surface of the second metal support layer, and then washing and drying to obtain the film.

10. Use of the film capable of controllably subdividing or directionally collecting droplets according to any one of claims 1 to 7 in droplet subdivision or droplet transport.

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