CN101748461B - Super-hydrophobic and super-oleophobic surface preparation technology - Google Patents

Abstract

The invention discloses a super amphiphobic surface preparation technology. In the invention, the aluminum or aluminum alloy sheet is subjected to two-step electrochemical treatment, and then modified with perfluorooctadecyltrichlorosilane or perfluoropolymethacrylate, and the obtained surface has superamphiphobic property. The surface is super-repellent to aqueous solutions with a pH value of 0-14 and various oil droplets, and the contact angle to water is 171°C, and the rolling angle is less than 1°C. All kinds of oil droplets except perfluoropolymer liquid exhibit superphobic properties, and their contact angles with the surface are all greater than 150°, and the rolling angles are generally less than 10°. The surface can also be placed in the air for a long time and still maintain its superamphiphobic properties.

Description

A super amphiphobic surface preparation technology

technical field

The invention relates to a super-amphiphobic surface preparation technology, which is a preparation method for producing a super-amphiphobic surface on the surface of aluminum or aluminum alloys for water, aqueous solutions of different pH values and most oil liquids, and in particular to a super-amphiphobic surface with both super-amphiphobic properties. Hydrophobic, superoleophobic, and superhydrophobic properties of polymer liquids under heated melting conditions, and superamphiphobic surfaces with long-term stability and robustness.

Background technique

Surface wettability is an important characteristic of solid surfaces, which is mainly determined by the chemical composition and microstructure of the solid surface. Since some surfaces with special wettability have extensive and important uses in the fields of production, life and basic research, the preparation of superhydrophobic and superoleophobic surfaces has attracted more and more attention in recent years, and more and more literatures have been published. Such surfaces with special wetting properties prepared by different methods have been reported. However, in these literatures, the reports on superhydrophobicity account for the vast majority, but the reports on superoleophobic surfaces are very few. Generally speaking, if a surface is oleophobic, it must also be hydrophobic. However, a hydrophobic or even superhydrophobic surface may not necessarily achieve oleophobicity, let alone superoleophobicity. In general practical experiments, according to the analysis of surface free energy, the reason is that to make a solid surface lyophobic, the surface tension of the surface must be less than a quarter of that of the liquid. This is easier to achieve for hydrophobic or even super-hydrophobic surfaces, because the surface free energy of water is relatively high at 72.8mN/m, and for most oily liquids with relatively low surface free energy, the general surface tension is far away. If it is less than this value, the surface tension required to achieve surface oleophobicity or even super oleophobicity is very small, probably only about a few gallons per meter. A super-oleophobic surface must have super-hydrophobic properties at the same time, therefore, the super-oleophobic surface will have more extensive and practical uses. So far, people have prepared some oleophobic or super-oleophobic surfaces by some methods, for example, people such as Tsujii have reported a preparation method of super-oleophobic surfaces (Angew. 36, 1011), Jiang Lei et al. reported super-amphiphobic carbon nanotube films in "Applied Chemistry" in 2001 (Li, H.J. et al. Angew. Chem. Int. Ed. 2001, 40, 1743.). Recently, Tuteja et al. published research results on the design and preparation of super-oleophobic surfaces in "Science" (Tuteja, A.; et al.Science 2007, 318, 1618), Gao, Di et al. prepared a porous The silicon surface, after being modified with perfluorosilane, exhibits superoleophobic properties. There are few related patents that have been seen. Chinese patent CN 101330165A discloses an underwater super-oleophobic polymer membrane with a bionic structure and a preparation method thereof. Nevertheless, these preparation methods still have great defects, such as the contact angle of some oils with very low surface energy (about 20mN/m) can only reach about 120° to 130°, and the substrates are mostly limited to silicon On-chip, the cost of the preparation process is relatively expensive, and the surface robustness closely related to practical applications has not been investigated. Therefore, the preparation of a super-oleophobic surface that is suitable for actual needs and can be applied has important theoretical and practical significance, and it is also a huge challenge for us.

Engineering metal materials aluminum and its alloys are widely used in navigation, aerospace, pipeline transportation and many other fields, such as the shell of radar and aircraft, the cabin of ships and submarines, etc., even in daily life. the use of. How to construct superhydrophobic, especially superoleophobic surfaces on engineering metal aluminum and its alloys has become a promising research hotspot. From the current literature, there is no simple and practical method for preparing various types of water, aqueous solutions, and various oils at the same time. Therefore, the aluminum-based superoleophobic The surface provides a very important practical preparation method, which is very promising for industrial development and production.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a super-amphiphobic surface.

In the invention, the aluminum or aluminum alloy sheet is subjected to two-step electrochemical treatment, and then modified with perfluorooctadecyltrichlorosilane or perfluoropolymethacrylate, and the obtained surface has superamphiphobic property.

A super-amphiphobic surface preparation technology is characterized in that the method comprises the following steps in sequence:

First, ultrasonically clean aluminum or aluminum alloy sheets with acetone, ethanol, and deionized water;

Then use the sodium sulfate aqueous solution as the electrolyte solution, use the cleaned aluminum or aluminum alloy sheet as the anode, and the lead plate as the cathode, and perform electrochemical etching reaction at a current density of 5-15mA/ ^cm2 at room temperature for 2-4 hours, and clean ,dry;

Then use the sulfuric acid aqueous solution as the electrolyte, the aluminum or aluminum alloy sheet as the anode, and the lead plate as the cathode, oxidize at 0-10°C for 5-30 minutes at a voltage of 50-100V, clean and dry;

Finally, the n-hexane solution of perfluorooctadecyltrichlorosilane or the trifluorotrichloroethane solution of perfluoropolymethacrylate is spin-coated on the surface of aluminum or aluminum alloy sheet, and kept at 80°C to 120°C for 1 ~3 hours to obtain a superamphiphobic surface.

The concentration of the sodium sulfate aqueous solution in the present invention is 0.01-0.1M.

The concentration of the n-hexane solution of perfluorooctadecyltrichlorosilane or the trifluorotrichloroethane solution of perfluoropolymethacrylate in the present invention is 0.1-1 wt%.

The invention overcomes many major defects that the superhydrophobic surface is relatively fragile, not resistant to mechanical action, and has poor long-term stability, which makes it difficult to be practical. In addition, the present invention also aims to overcome the fact that most superhydrophobic surfaces in the past are only superphobic to water or aqueous solutions, and it is difficult to show lyophobicity or even superphobicity to oily liquids with much lower surface energy.

The aluminum or aluminum alloy superamphiphobic surface of the present invention can be stable for a long time, and can still maintain superphobic properties well after mechanical bending and deformation. In addition, it can superphobic paraffin, polyethylene glycol and other oils that are melted by solids under heating. Liquid droplets, and when condensed by water vapor, the spherical droplets adhere to the surface without wetting and can easily fall. The preparation method of the surface is simple, practicable, easy to realize industrial production, and has unique super-hydrophobic properties. Superphobic properties and surface stability and robustness.

Pure water, salt solution, and acid or alkali are dropped onto the aluminum or aluminum alloy superamphiphobic surface prepared in this way to measure the contact angle. The contact angles are all greater than 170°, and the rolling angles are all less than 1°. The acid used is hydrochloric acid, the salt solution used is sodium chloride solution, the alkali is sodium hydroxide solution, and the pH value range of the solution used for measurement is 0-14.

The contact angles of various oil droplets (except perfluoropolymer liquids) were measured on the superamphiphobic surface. The contact angles were all greater than 150°, and most of the rolling angles were less than 10°. The oil liquid used is all kinds of oil with surface energy ranging from 20mN/m to 50mN/m, from edible oil, lubricating oil, ionic liquid to silicon oil and crude oil just extracted from the oil field.

The contact angle of molten paraffin and polyethylene glycol (molecular weight is 2000) is measured on the super-phobic surface under heating conditions, and the contact angles are all greater than 160°. The solid paraffin and solid polyethylene glycol have melting temperatures of 57-63°C and 51°C respectively, and the surface heating temperature reaches more than 70°C.

Spray water vapor on the super-repellent surface at a temperature lower than room temperature. After a period of time, the condensed water cannot wet the surface and can only gather on the surface in spherical droplets of different sizes, which can easily fall off.

The superamphiphobic surface can still maintain its superphobic properties after being placed in the air for a long time (more than one year), and the surface structure and superphobicity hardly change after repeated bending and surface friction.

Promising uses of the invention:

1. The superamphiphobic surface of the present invention has the characteristics of non-sticking to water, non-sticking acid and non-sticking alkali, and can be used for antifouling and anticorrosion on the surface of metal aluminum and its alloys.

2. The superamphiphobic surface of the present invention can be used on water vehicles such as various ships or underwater submarines, which can reduce water resistance, increase driving speed, and reduce noise. It is especially suitable for navigating in various sea environments, and can prevent the corrosion of various sea salts on the hull and the adhesion of sea baths and oil substances to the hull, thereby greatly improving the navigation speed and reducing energy consumption and maintenance costs for the hull.

3. The super-amphiphobic surface material of the present invention can be used for the outer surface of some important equipment placed outdoors for a long time and needs to be waterproof, acid rain-proof, corrosion-proof and covered with ice and snow, which can greatly reduce corrosion, improve service life, and reduce losses caused by ice and snow coverage .

4. The superamphiphobic surface material of the present invention has a super strong repelling effect on aviation lubricating oil, and is expected to be used in the lubrication of space component materials, thereby effectively preventing lubricating oil from crawling.

5. The superamphiphobic surface of the present invention has the characteristics of superhydrophobic, superacid and alkaliphobic, and the characteristics, stability and firmness of superphobic various oils, so it can be used to prepare crude oil for transportation, lubricating oil, corrosive Pipelines for liquids, and storage containers.

6. The superamphiphobic surface of the present invention has the superphobic properties of aqueous emulsions, and can be used for chemical analysis and the delivery and storage of some precious emulsion-like reagents and medicines without loss in ultra-micro liquids.

7. The base material of the superamphiphobic surface of the present invention is aluminum or aluminum alloy material, which has long been widely used as the material of living utensils in daily life, so the present invention can greatly improve the functions and added value of these aluminum-based daily necessities.

8. The superphobic surface of the aluminum base and its alloys of the present invention is difficult for water vapor to wet under low temperature condensation, and can be used as anti-frosting and icing materials in refrigerators, freezers, other refrigeration systems and air-conditioning equipment, greatly improving the efficiency of equipment.

The present invention has the following characteristics:

1. The prepared superamphiphobic surface has a hierarchical structure of suspended microstructure and nanowire structure. The surface is modified by perfluorinated low surface energy substances to show superhydrophobicity, and it is resistant to water and aqueous solutions (including salt solution, strong acid solution, strong alkali solution) have a contact angle greater than 170° and a rolling angle less than 1°. At the same time, it exhibits superoleophobicity, superoleophobicity to various oils (except perfluoropolymer liquid) with surface energy in the range of 20mN/m to 50mN/m, and the contact angle to oil is generally greater than 150°, and The rolling angle is very small, ranging from 3° to 10°.

2. The prepared superamphiphobic surface can be superphobic to molten paraffin, polyethylene glycol and other droplets at a temperature much higher than normal temperature.

3. The prepared superamphiphobic surface has good firmness, and can withstand mechanical deformation, and can be bent and deformed without destroying its surface structure and superhydrophobic and superoleophobic properties.

5. The prepared superamphiphobic surface can be placed in the air for a long time (greater than 1 year) without changing its superhydrophobic and superoleophobic properties.

6. The prepared super-amphiphobic surface is non-wetting to water vapor in a high-humidity environment, has ultra-small adhesion to droplets formed by condensation and can easily fall off, and can prevent frosting and freezing to a certain extent.

7. The prepared superamphiphobic surface has a simple preparation process, and a mature electrochemical treatment method is adopted. No complicated equipment is required, the technical operability is good in repeatability, and it is easy for mass preparation and industrial production.

8. The prepared superamphiphobic surface is made of metal aluminum or aluminum alloy used in engineering and daily life, so it has a wide range of applications, and has broad application prospects in the fields that require hydrophobicity and oleophobicity in industrial fields and daily life. Especially those practical fields that require superhydrophobicity and superoleophobicity.

Detailed ways

Example 1

1. Use acetone, ethanol, and deionized water to ultrasonically clean the aluminum sheet (99.9%) sample (80mm×20mm×2mm) in order to remove the grease on the sample, and then dry it for use;

2. Use 0.03M sodium sulfate aqueous solution as the electrolytic solution for the aluminum sheet processed in the previous step, the aluminum sheet as the anode, and the lead plate as the cathode, with a voltage of 4V and a current density of 7mA/ ^cm2 under constant current, and oxidize at room temperature for 4 hours. The reacted sample was ultrasonically cleaned with ethanol and deionized water in sequence, and dried in the air;

3. Use 1M sulfuric acid aqueous solution as the electrolyte, the aluminum sheet as the anode, and the lead plate as the cathode for the sample after the electrochemical oxidation treatment in the previous step, and rapidly oxidize it at a constant temperature of 10°C and a voltage of 60V for 10 minutes. Then use ethanol and deionized water to ultrasonically clean the aluminum sheets sequentially, and dry them in the air;

4. Spin-coat 0.5% n-hexane solution of perfluorooctadecyltrichlorosilane on the surface of the dried aluminum sheet for chemical modification, and after natural drying, keep it in an oven for 2 hours at 120°C to obtain an aluminum sheet super amphiphobic surface.

The superamphiphobic surface has a double microstructure of 2-15 micron platform protrusions and densely grown alumina nanowires.

The static contact angle values of the superamphiphobic surface to aqueous solutions with different pH values are all greater than 170°C.

The contact angle, rolling angle and surface energy data of the surface to water, emulsion and various oils are shown in Table 1.

Table 1: Surface energies of water, emulsions, various oils, and contact angles and rolling angles on superamphiphobic surfaces

The superamphiphobic surface remains superamphiphobic to water and crude oil after repeated bending.

The superamphiphobic surface shows superphobicity with heated and melted polyethylene glycol and paraffin liquids, and the contact angles are all greater than 160°C.

After being placed in the air for one year, the super-amphiphobic surface still maintains super-hydrophobic and super-oleophobic properties. The contact angle values for water and n-hexadecane are shown in Table 2.

Table 2: Superamphiphobic surface placement time and contact angle values in air

placement time Contact angle with water (°) Contact angle with n-hexadecane (°) 30 days 171.3 158.6 60 days 171.2 158.5 90 days 171.3 158.7 120 days 171.2 158.4 150 days 171.4 158.3 180 days 171.3 158.2 210 days 171.3 158.4 240 days 171.2 158.6 270 days 171.3 158.3 300 days 171.2 158.5 330 days 171.2 158.6 360 days 171.3 158.3

The super-amphiphobic surface is under the condensed steam atmosphere, and the water vapor condenses on the surface as small water droplets, which are easy to blow off and have very little adhesion. The frost formed is also easy to remove from the surface.

Example 2

1. Use acetone, ethanol, and deionized water to ultrasonically clean the aluminum alloy sheet (the Al content is about 97%, and the rest is Mg, Si, etc.) (80mm×20mm×2mm) to remove the grease on the sample and dry it in the air ;

2. Use 0.05M sodium sulfate aqueous solution as the electrolyte solution for the aluminum alloy sheet cleaned in the previous step, the aluminum alloy sheet as the anode, and the lead plate as the cathode, the voltage is 5V, the current density is 8mA/ ^cm2 , and the electrochemical The etching reaction was 3.5 hours. The reacted aluminum alloy sheet is ultrasonically cleaned with ethanol and deionized water in sequence;

3. Use 1M sulfuric acid aqueous solution as the electrolyte for rapid anodic oxidation of the aluminum alloy sheet after the electrochemical etching treatment in the previous step. The aluminum foil is used as the anode and the lead plate is used as the cathode. A voltage of 70V is applied at a constant temperature of 5°C, and the reaction time is 15 minutes. Then use ethanol and deionized water to ultrasonically clean the aluminum alloy sheets after the reaction in turn, and dry them in the air;

4. Spin-coat 0.5% trichlorotrifluoroethane solution of perfluoropolymethyl methacrylate onto the surface of the dried aluminum sheet for chemical modification, and after drying, keep it in an oven for 3 hours at 120°C to obtain aluminum Alloy sheet superamphiphobic surface.

Example 3

1. Use acetone, ethanol, and deionized water to ultrasonically clean the aluminum alloy (the Al content is about 97%, the rest is Mg, Si, etc.) (80mm×20mm×2mm) to remove the surface grease, and then dry it for use ;

2. Take the aluminum alloy sheet cleaned in the previous step, use 0.1M sodium sulfate aqueous solution as the electrolyte solution, the aluminum alloy sheet as the anode, and the lead plate as the cathode, at a voltage of 8V and a current density of 15mA/cm ² , electrochemically etch at room temperature React for 2.5 hours. The reacted aluminum alloy sheet is ultrasonically cleaned with ethanol and deionized water in sequence, and dried in the air;

3. Use 1M sulfuric acid aqueous solution as the electrolyte for the rapid anodic oxidation reaction of the aluminum alloy sheet after the electrochemical etching reaction in the previous step. The aluminum alloy sheet is used as the anode and the lead plate is used as the cathode. Apply a voltage of 100V at a constant temperature of 3°C for anodic oxidation. The reaction time was 8 minutes. Then use ethanol and deionized water to ultrasonically clean the aluminum alloy sheets after the reaction in turn, and dry them in the air;

4. Spin-coat 1% n-hexane solution of perfluorooctadecyltrichlorosilane on the surface treated in the previous step for chemical modification. After natural drying, keep it in an oven for 3 hours at 120°C to obtain an aluminum alloy sheet superamphiphobic surface.

Example 4

1. Use acetone, ethanol, and deionized water to ultrasonically clean the aluminum sheet (80mm×20mm×2mm) in order to remove the surface grease, and then dry it for use;

2. Put the aluminum sheet cleaned in the previous step, use 0.08M sodium sulfate aqueous solution as the electrolyte solution, the aluminum sheet as the anode, and the lead plate as the cathode, the voltage is 6V, the current density is 10mA/cm ² under constant current, at room temperature Surface electrochemical etching reaction for 3 hours. The reacted aluminum sheet is ultrasonically cleaned with ethanol and deionized water in sequence, and dried in the air;

3. Use 1M sulfuric acid aqueous solution as the electrolyte for the rapid oxidation reaction of the aluminum sheet after the electrochemical etching treatment in the previous step. The aluminum sheet is used as the anode, and the lead plate is used as the cathode. Apply 80V voltage at a constant temperature of 5°C, and the reaction time is 20 minutes. . Then ultrasonically clean with ethanol and deionized water in sequence, and dry in the air;

4. Spin-coat 0.1% trichlorotrifluoroethane solution of perfluoropolymethyl methacrylate onto the surface of the electrochemically treated aluminum sheet for chemical modification, and keep it in an oven at 120°C for 2 hours after natural drying. That is, the superamphiphobic surface of the aluminum sheet is obtained.

Claims (3)

1. A super-amphiphobic surface preparation technology is characterized in that the method comprises the following steps successively: First, ultrasonically clean aluminum or aluminum alloy sheets with acetone, ethanol, and deionized water; Then use the sodium sulfate aqueous solution as the electrolyte solution, use the cleaned aluminum or aluminum alloy sheet as the anode, and the lead plate as the cathode, and perform electrochemical etching reaction at a current density of 5-15mA/ ^cm2 at room temperature for 2-4 hours, and clean ,dry; Then use the sulfuric acid aqueous solution as the electrolyte, the aluminum or aluminum alloy sheet as the anode, and the lead plate as the cathode, oxidize at 0-10°C for 5-30 minutes at a voltage of 50-100V, clean and dry; Finally, the n-hexane solution of perfluorooctadecyltrichlorosilane or the trifluorotrichloroethane solution of perfluoropolymethacrylate is spin-coated on the surface of aluminum or aluminum alloy sheet, and kept at 80°C to 120°C for 1 ~3 hours to obtain a superamphiphobic surface. 2. preparation technology as claimed in claim 1 is characterized in that the concentration of sodium sulfate aqueous solution is 0.01～0.1M. 3. The preparation technology as claimed in claim 1, characterized in that the concentration of the n-hexane solution of perfluorooctadecyltrichlorosilane or the trifluorotrichloroethane solution of perfluoropolymethacrylate is 0.1～1wt %