TWI672398B - Amphiphobic structure and method for manufacturing the same - Google Patents

Abstract

The method for forming an oil-water double-drain structure provided by the present disclosure comprises: (i) performing a first anodization etching on a substrate in a solution of a halogen salt to form a micro-concave structure; and (ii) in acetic acid, oxalic acid, lemon a second anodization etching of the micro-concave structure in an acid or a combination of the above to form a plurality of nanopores on the surface of the micro-concave structure, wherein the micro-concave structure has an average roughness (Ra) of 500 nm to 1500 nm between.

Description

Oil-water double-sparse structure and its forming method

The disclosure relates to oil-water double-sparing structure.

The oil-water double-sparing structure (the contact angle between water and oil is greater than 90°) is widely used in industry and people's livelihood. According to Young's Equation, the droplets form a contact angle on the surface of the solid. When the contact angle is >90°, the liquid is less likely to adhere to the solid surface and is easily separated. When the surface energy of the liquid is smaller, the surface energy of the solid needs to be smaller to reach a large contact angle. The surface energy of water is 72.3 mN/m. The oil phase is represented by hexadecane and its surface energy is 27.5 mN/m. The surface energy of common edible oils is between 25 and 35 mN/m. Therefore, in the oil-water double-drain structure, the technical threshold of the oleophobic surface is higher than the technical threshold of the hydrophobic surface.

In addition, the oil-water double-drain structure also needs to consider the sliding angle of the oil droplets on the surface of the structure, otherwise the oil droplets will condense on the surface of the structure and it is difficult to remove. At present, most of the oil-water double-drain structure has a sliding angle of more than 5 degrees, or even more than 10 degrees. In summary, there is a need for a new oil-water double-drain structure to simultaneously take into account the large contact angle with water, the large contact angle with oil, and the small sliding angle of oil droplets on the surface of the structure.

The oil-water double-sparing structure provided by an embodiment includes: micro a moire structure; and a plurality of nanopores located on the surface of the micro-concave structure, wherein the micro-concave structure has an average roughness (Ra) of between 500 nm and 1500 nm.

The method for forming an oil-water double-drain structure provided by an embodiment includes: (i) performing a first anodization etching on a substrate in a solution of a halogen salt to form a micro-concave structure; and (ii) in acetic acid, A second anodization etching of the micro-concave structure is performed in a solution of oxalic acid, citric acid, or a combination thereof to form a plurality of nanopores on the surface of the micro-concave structure, wherein the average roughness (Ra) of the micro-concave structure is between Between 500 nm and 1500 nm.

Fig. 1 is a SEM photograph of a micron uneven structure in an embodiment.

Fig. 2 is a SEM photograph of a nanopore on the side wall surface of the micro-concave structure in an embodiment.

An embodiment of the present invention provides a method for forming an oil-water double-drain structure, comprising: (i) performing a first anodization etching on a substrate in a solution of a halogen salt to form a micro-concave structure. In one embodiment, the substrate is an aluminum sheet. In one embodiment, the halogen salt comprises NaCl, NaF, NaBr, KCl, KBr, or a combination thereof, and the concentration of the halogen salt is between 0.04 M and 0.08 M. If the concentration of the halogen salt is too high, the voltage cannot be increased to the voltage required for etching. If the concentration of the halogen salt is too low, sufficient conductivity cannot be provided and the current density is too small to meet the roughness requirement. In an embodiment, the voltage of the first anodization etch is between 4V and 8V. If the voltage of the first anodization etch is too high, too much substrate is etched into the electrolyte causing the substrate to become too thin to affect the structural strength. If the voltage of the first anodization etch is too low, the generation of the etching reaction or the reaction may be too slow to cause the process to be too long. In one embodiment, the first anodization etch has a current density between 0.02 A/cm ² and 0.03 A/cm ² . If the current density of the first anodization etch is too high, it means that too high a voltage will etch too much substrate into the electrolyte causing the substrate to become too thin. If the current density of the first anodization etching is too low, it means that the voltage is too low, and the generation of the etching reaction or the reaction may be too slow to make the process too long. Because in the same oxidized etching system, the voltage is positively correlated with the current density at the same electrolyte concentration and temperature. In an embodiment, the temperature of the first anodization etch is between 10 ° C and 30 ° C. If the temperature of the first anodization etch is too high, it is dangerous. If the temperature of the first anodization etch is too low, the reaction will be too slow and the process will be too long. In one embodiment, the first anodization etch is between 1 hour and 3 hours. If the first anodization etch is too long, etching too much of the substrate into the electrolyte causes the substrate to become too thin. If the time of the first anodization etching is too short, insufficient etching may not form a surface micro-concave structure having a sufficient roughness.

Next, (ii) the micro-concave structure is subjected to a second anodization etching in a solution of acetic acid, oxalic acid, citric acid, or a combination thereof to form a plurality of nanopores on the surface of the micro-concave structure. The second anodization etch further increases the roughness of the micro-concave structure. For example, the center line average roughness (Ra) of the micro-concave structure is between 500 nm and 1500 nm. If the average roughness of the center line of the micro-concave structure is too small, the sliding angle of the oil droplets which are not easily slid on the surface is large, and even the oil droplets may stick to the surface. If the center line average roughness of the micro-concave structure is too large, it means that the etching time is too long to cause the substrate to become thin and affect the structural stability. In step (ii), the concentration of acetic acid, oxalic acid, citric acid, or a combination thereof is between 0.1 M and 0.5 M. If the concentration of acetic acid, oxalic acid, citric acid, or a combination thereof is too low, the conductivity is insufficient and the current density cannot be adjusted to a desired range. If the concentration of acetic acid, oxalic acid, citric acid, or a combination thereof is too high, a saturated solution is formed, and a solute is precipitated during etching to affect the process. It is worth noting that if a strong acid such as phosphoric acid is used in step (ii), a columnar nano column will be formed and a nanopore cannot be formed. In an embodiment, the voltage of the second anodization etch is between 30V and 80V. If the voltage of the second anodization etching is too high, the pore walls of the nanopore will collapse and form a columnar structure, and the process risk is increased, which is not suitable for the system. If the voltage of the second anodization etch is too low, the density of the nanopore formation will be too low to affect the total volume of the nanopore. In one embodiment, the second anodization etch has a current density between 0.005 A/cm ² and 0.015 A/cm ² . If the current density of the second anodization etching is too high, the pore walls of the nanopore will collapse and form a columnar structure. If the current density of the second anodization etch is too low, the density of the nanopore formation will be too low to affect the total volume of the nanopore. In an embodiment, the temperature of the second anodization etch is between 10 ° C and 30 ° C. If the temperature of the second anodization etch is too high, the current density is too large to destroy the micro-structure of the first anodization etch. If the temperature of the second anodization etch is too low, the density of the nanopore formation will be too low to affect the total volume of the nanopore. In one embodiment, the second anodization etch is between 1 hour and 3 hours. If the second anodization etching time is too long, the pore walls of the nanopore will collapse and form a columnar structure. If the second anodization etching time is too short, the density of the nanopore formation will be too low to affect the total volume of the nanopore.

The second anodization etching of step (ii) forms a nanopore on the surface of the micro-concave structure. In one embodiment, the nanopore has a diameter between 10 nm and 60 nm. If the diameter of the hole is too small, sufficient air bubbles cannot accumulate underneath, resulting in a large contact area between the oil droplet and the surface, which affects the sliding of the oil droplet. If the diameter of the nanopore is too large, the pore walls of the nanopore will collapse and form a columnar structure. In one embodiment, if the depth of the nanopore is between 2 nm and 35 nm and the depth of the nanopore is too small, the nanopore is insufficient to accumulate sufficient air bubbles. If the depth of the hole is too large, it means that the current is too much associated with the hole, and the diameter of the hole is too large, causing the hole wall of the nano hole to collapse and form a columnar structure.

In one embodiment, the above method further comprises (iii) modifying the surface of the nanopore and the micro-convex structure with fluorinated decane. The above fluorinated decane has a carbon number of n, a number of fluorine atoms of between 2n-3 and 2n+1, and n of between 8 and 12. If the carbon number of the fluorinated decane is too small, since there is not enough position to engage the F atom, the functional group having a low surface energy cannot provide a poor sliding angle, and the sliding angle becomes large, so that the oil droplet is not easily slipped. If the carbon number of the fluorinated decane is too large, it is difficult to hydrolyze to form an OH functional group, and a strong covalent bond with the metal surface cannot be formed. If the F atom of fluorinated decane is too small, a functional group having a low surface energy cannot be provided. If the F atom of the fluorinated decane is too large, it means that the carbon number must be increased and there is a problem that hydrolysis is difficult. In one embodiment, the fluorinated decane may be 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (FDS) or 1H, 1H, 2H, 1H, 2H, 2H, 2H, 2H-Tetrafluoro-triethoxydecane (1H, 1H, 2H, 2H-Perfluorodecyltriethoxysilane, FAS).

The oil-water double-drain structure formed by the above method has an area of a nanopore volume/oil-water double-pore structure of between 800 nm ³ /(300 nm×300 nm) and 250,000 nm ³ /(300 nm×300 nm). The above-mentioned hole volume is the total volume of the nano-holes per unit area (calculated by AFM measurement). If the volume of the pores per unit area of the oil-water double-drain structure is too small, sufficient air bubbles cannot be accumulated, so that the contact area of the oil droplets with the surface is large and the sliding of the oil droplets is affected. If the volume of the pores per unit area of the oil-water double-drain structure is too large, the pore walls of the nano-holes may collapse and form a columnar structure so that bubbles cannot be accommodated in the form of holes.

In one embodiment, the oil-water double-drain structure has a contact angle of more than 90° to water and general edible oil, and the sliding angle of 5 to 27 μL of edible oil (such as soybean salad oil or olive oil) may be less than 5°. (eg as low as 3.1°).

Generally, when the rough surface of the double sparse surface contacts the oil film, the surface energy difference tends to separate the oil from the double sparse surface. However, when small oil droplets (particle size nm~μm) are aggregated into larger oil droplets (>μm), the rough surface becomes the resistance of oil droplet polymerization. However, the nanopore of the present disclosure contains air to reduce the contact area of the oil film, and the surface modified low surface energy material can separate the oil film from the double surface.

The above and other objects, features and advantages of the present invention will become more apparent and understood.

Example

Example 1 (micron concave-convex structure)

An aluminum piece having an area of 2 cm × 6 cm and a thickness of 1 mm was taken, immersed in ethanol and ultrasonically shaken for 10 minutes. The aluminum piece was taken out, washed with deionized water, immersed in acetone and ultrasonically shaken for 10 minutes. The aluminum sheet was taken out and naturally dried at room temperature for use.

Connecting the pre-treated aluminum sheet to the anode of the DC power supply The pole is the platinum electrode. The anode and cathode were placed in 0.06 M NaCl, the two electrodes were 2 cm apart in solution, and the NaCl solution was slowly stirred with magnets during the first anodization etching.

A voltage of 4 V was applied to the electrodes for the first anodization etching, and the energization times were 5, 10, 15, 20, 30, 40, 50, 60, 120, and 180 minutes, respectively. The above temperature not higher than 30 ℃, while magnitude regulated voltage (not more than 8V) to maintain a current density at 0.02 ~ 0.03A / ^2, between the end of the reaction cm aluminum foil with deionized water after sonicated for 10 minutes to remove surface The oxide was then dried at a temperature of 120 ° C for 2 hours.

The first anodized etched aluminum sheet was analyzed by a scanning electron microscope (SEM). When the first anodizing etching time is 20 minutes, the surface portion of the aluminum sheet is oxidized to a micron (1 to 10 μm) grade uneven structure. When the first anodization etching time was increased to 40 minutes, the ratio of the microstructure of the micron (1 to 10 μm) grade was more than that of the first anodization etching time of only 20 minutes. When the first anodizing etching time is 60 minutes, most of the surface has formed a micron-scale uneven structure. When the first anodizing etching time was 180 minutes, the uneven structure in which the surface was completely etched into a micron order was obtained, and the SEM photograph thereof is shown in Fig. 1. The aluminum sheet after 180 minutes of the first anodizing etching was analyzed by atomic force microscopy (AFM), and the roughness minimum square roughness and roughness (Rq)=799 nm, the center line average roughness (Ra)=628 nm, and the highest point of the surface were observed. The distance between the lowest points is 2.8 microns.

Example 2 (micron concave-convex structure + nano hole)

The aluminum sheet subjected to the first anodization etching in Example 1 for 180 minutes was bonded to the anode of the DC power supply, and the cathode was a platinum electrode. Anode and cathode Placed in 0.3 M oxalic acid and the two electrodes are 1 cm apart in solution.

60 volts (V) was applied to the electrodes for a second anodization etch with energization times of 20, 40, 60, and 120 minutes, respectively. During the second anodizing etching, the temperature rises, and the temperature of the reaction bath is controlled to be no higher than 30 ° C. After the second anodizing etching, the aluminum sheet is vortexed with deionized water for 10 minutes to remove oxides on the surface, and then placed. Dry at 120 ° C for 120 minutes.

The second anodized etched aluminum sheet was analyzed by SEM. When the second anodization etching time is 20 minutes, holes of a nanometer grade (10 nm to 30 nm in diameter) are etched on the uneven structure on the surface of the aluminum sheet. When the second anodization etching time was increased to 40 minutes, the nanopores had more results than the second anodization etching time of only 20 minutes. When the second anodizing etching time is 60 minutes, most of the surface has formed nanopores. When the second anodizing etching time is 120 minutes, the surface of the uneven structure can be completely etched into nanopores. The aluminum flakes after the second anodization etching for 120 minutes were analyzed by AFM, and the roughness Rq=1076 nm, Ra=867 nm, and the distance between the highest point and the lowest point of the surface was 3.6 μm.

The aluminum sheet after the second anodization etching for 120 minutes is immersed in 0.5 wt% of 1H, 1H, 2H, 2H-perfluorodecafluoro-decanedioxane (FDTS) in n-hexane solution, and ultrasonically After shaking for 60 minutes, it was dried at room temperature for 10 minutes, and then dried at a temperature of 120 ° C for 60 minutes to graft the above fluorinated decane onto the aluminum sheet.

The aluminum sheet after grafting of fluorinated decane was analyzed by SEM, and it was found that the surface morphology of the aluminum sheet before and after grafting of fluorinated decane was similar. After the grafting of fluorinated decane, the surface of the aluminum sheet maintains a micron (1~10μm) grade of concave-convex structure and nano-structure on the concave-convex structure. Grade (10~30nm diameter) holes. At the same time, the surface of the side wall of the uneven structure observed by the cross section has a nanopore, as shown in the SEM photograph of Fig. 2. The surface of the aluminum sheet before and after grafting of the FDTS was analyzed by energy dispersive spectroscopy (EDS), and it was found that the percentage of F atoms increased from ~0% before grafting to 6.28% after grafting.

The aluminum sheet grafted with FDTS was analyzed by AFM, and the average depth of the hole of the nanometer grade (diameter 10-20 nm) was measured to be 2.7 nm, the average diameter of the pore was 15 nm, and the void volume/area of the aluminum sheet was 3021 nm ³ / ( 300 nm × 300 nm). The contact angle of the surface of the aluminum sheet after grafting FDTS to water and grape seed oil was 150° and 144°, respectively. For the measurement method, refer to Langmuir 2000, 16, 5754-5760 or Colloids and Surfaces B: Biointerfaces 161 (2018). 324-330.

Example 3 (Micro-concave structure of a large area (17 cm × 17 cm) substrate + nano hole)

Take aluminum sheet with an area of 17cm × 17cm and a thickness of 1mm, immersed in a mixture of sodium gluconate (5g / L) and NaOH (10g / L) 1:1 for 10 minutes, taken out and rinsed with water, then impregnated HNO ₃ (68~70%): H ₂ O = 1:1 for 10 minutes, taken out and rinsed with water.

The pre-treated aluminum sheet is attached to the anode of the DC power supply, and the cathode is a platinum electrode. The anode and cathode were placed in 0.06 M NaCl, the two electrodes were 2 cm apart in solution, and the NaCl solution was slowly stirred with magnets during the first anodization etching.

A voltage of 4 V was applied to the electrodes for the first anodization etching, and the energization time was 120 minutes. The above temperature is not higher than 30 ° C, and the voltage is regulated (not more than 8 V) to maintain the current density between 0.02 and 0.03 A/cm ² . After the reaction is finished, the aluminum sheet is vortexed with deionized water for 10 minutes to remove the surface. The oxide was then dried at a temperature of 120 ° C for 2 hours. After the first anodization etching, the micro-concave structure is formed on the surface of the aluminum sheet.

The first anodized aluminum sheet after 120 minutes was connected to the anode of the direct current power supply, and the cathode was a platinum electrode. The anode and cathode were placed in 0.3 M oxalic acid and the two electrodes were 1 cm apart in solution.

60 volts (V) was applied to the electrode for a second anodization etch with an energization time of 120 minutes. During the second anodizing etching, the temperature rises and the temperature of the reaction bath is controlled to be no higher than 30°. In the second anodic oxide etch after 30 minutes, the regulation of the maximum current density is not greater than 0.03A / cm ^2. After the second anodizing etch, the aluminum flakes were vortexed with deionized water for 10 minutes to remove oxides on the surface, which were then dried at a temperature of 120 ° C for 120 minutes. After the second anodization etching, a nanopore hole is formed on the surface of the micro-concave structure.

The aluminum piece after the second anodization etching for 120 minutes was immersed in a 0.5 wt% FDTS hexane solution, and oscillated with ultrasonic waves for 60 minutes, and then dried at room temperature for 10 minutes, and then at a temperature of 120 ° C. The above fluorinated decane was grafted onto an aluminum sheet by drying for 60 minutes.

The contact angle of the surface of the aluminum sheet after grafting FDTS to water and grape seed oil was measured at 143° and 125°, respectively. For the measurement method, refer to Langmuir 2000, 16, 5754-5760 or Colloids and Surfaces B: Biointerfaces 161 (2018). ) 324-330.

Example 4 (micro-concave structure of a large area (17 cm × 42 cm) substrate + nano hole)

Similar to Example 3, the difference was that the substrate area of Example 4 was increased to 17 cm x 42 cm. First anodizing etching (forming micro-concave structure), second yang The conditions of the extreme oxidation etching (formation of nanopores) and the grafting of the fluorine-containing decane are the same as those of the third embodiment, and will not be described herein.

The contact angles of the surface of the aluminum sheet after grafting FDTS to water and grape seed oil were measured at 148° and 143°, respectively. For the measurement method, refer to Langmuir 2000, 16, 5754-5760 or Colloids and Surfaces B: Biointerfaces 161 (2018). ) 324-330.

Example 5

The test pieces prepared in Examples 1-4 were subjected to a sliding angle test of the oil phase. Take soy salad oil as test oil. Place the test piece flat on the test, then place a drop of soy salad oil (5~27μL) on the surface, then slowly lift the test piece side until the oil drop slides, then calculate the sliding angle. (Measured by dynamic contact angle meter, model VCA OPTIMA XE, brand AST Products, Inc.). The smaller the above sliding angle, the better the oleophobic effect of the test piece. The sliding angle of Example 1 was >45° maximal due to its lack of nanopores and ungrafting of FDTS. The sliding angle of Embodiment 2 can be as small as 3.1°, and the sliding angle (5°) of Embodiment 3 is similar to the sliding angle (5°) of Embodiment 4, showing that the above process can be applied to a large-area substrate, and The process-shaped structure has good oleophobic properties.

Comparative example 1

Similar to Example 2, the difference was that the second anodically etched electrolyte was changed to 0.3 M phosphoric acid. The surface of the micro-structure after grafting FDTS exhibits a nano-columnar structure rather than a nano-porous hole, so the air cannot be coated. The contact angle of the test oil droplet on the surface is >125°, but the oil droplet still cannot slide down when the angle of the test piece is inclined to >45°.

Comparative example 2

Similar to Example 2, the difference is that FDTS is replaced by polyvinylidene fluoride-hexafluoro A propylene copolymer (poly(vinylidene fluoride-co-hexafluoro-propylene, CAS. No.: 9011-17-0, Aldrich), the oil droplets have a sliding angle of >30° on the above surface.

The present disclosure has been disclosed in the above several embodiments, but it is not intended to limit the disclosure, and any one skilled in the art can make any changes and refinements without departing from the spirit and scope of the disclosure. Therefore, the scope of protection of this disclosure is subject to the definition of the scope of the patent application.

Claims (12)

An oil-water double-drain structure comprises: a one-micron concave-convex structure; and a plurality of nano-holes located on a surface of the micro-concave structure, wherein the micro-concave structure has a roughness of between 500 nm and 1500 nm. The oil-water double-drain structure according to claim 1, wherein the nano-holes have a diameter of between 10 nm and 60 nm, and the nano-holes have a depth of between 2 nm and 35 nm. For example, in the oil-water double-sparing structure described in claim 1, the area of the pore volume/oil-water double-sparse structure is between 800 nm ³ / (300 nm × 300 nm) and 250,000 nm ³ / (300 nm × 300 nm). The oil-water double-sparse structure according to claim 1, further comprising the nano-holes modified by the fluorinated decane and the surface of the micro-convex structure. The oil-water double-sparing structure according to claim 4, wherein the fluorinated decane has a carbon number of n, the number of fluorine atoms is between 2n-3 and 2n+1, and n is between 8 and 12. . A method for forming an oil-water double-drain structure, comprising: (i) performing a first anodization etching on a substrate in a solution of a halogen salt to form a one-micron concave-convex structure; and (ii) in acetic acid, oxalic acid, citric acid Or a combination of the above combinations, the second anodizing structure is subjected to a second anodization etching to form a plurality of nanopores on the surface of the micro-concave structure, wherein the micro-concave structure has an average roughness (Ra) of 500 nm to Between 1500nm. The method for forming an oil-water double-drain structure according to claim 6, wherein the halogen salt of the step (i) comprises NaCl, NaF, NaBr, KCl, KBr, or a combination thereof, and the concentration of the halogen salt is From 0.04M to 0.08M. The method for forming an oil-water double-drain structure according to claim 6, wherein the first anodizing etching voltage of the step (i) is between 4V and 8V, and the current density is between 0.02A/cm ² and 0.03. A / cm ^2, between 10 deg.] C to a temperature between 30 ℃, and over a period of between 1-3 hours. The method for forming an oil-water double-sparse structure according to claim 6, wherein the concentration of acetic acid, oxalic acid, citric acid, or a combination thereof in the step (ii) is between 0.1 M and 0.5 M. The method for forming an oil-water double-drain structure according to claim 6, wherein the voltage of the second anodization etching in the step (ii) is between 30V and 80V, and the current density is between 0.005A/cm ² and 0.015. A / cm ^2, between 10 deg.] C to a temperature between 30 ℃, and over a period of between 1-3 hours. The method for forming an oil-water double-drain structure according to claim 6 further includes (iii) modifying the surface of the nano-holes and the micro-convex structure with fluorinated decane. The method for forming an oil-water double-drain structure according to claim 11, wherein the fluorinated decane has a carbon number of n, the number of fluorine atoms is between 2n-3 and 2n+1, and n is between 8 and Between 12.