Durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film, and preparation method therefor

Abstract

The present invention belongs to the field of super-hydrophobic surface technology, and discloses a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film and a preparation method therefor. The preparation method is as follows: adding an epoxy silane coupling agent into an organic solvent; after stirring and mixing well, adding an amine curing agent and distilled water to the mixture; stirring and adding micron-sized solid particles and hydrophobic nano silicon dioxide particles; continuing stirring to obtain a hydrophilic layer solution; adding a hydrophobic modifier and a hydrophilic nano silicon dioxide particles into the solvent to obtain a hydrophobic layer solution; coating a pretreated substrate surface with the hydrophilic layer solution, and performing heating treatment at 60° C. to 80° C. for 10-50 min; then coating the surface with the hydrophobic layer solution, and performing heating treatment at 100° C. to 140° C. for 50-90 min to obtain the durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film. The preparation method of the present invention is simple, and the super-hydrophobic surface of the obtained composite film has strong mechanical durability and a good industrial application prospect.

Claims

1. A method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film, characterized in that this method comprises the following steps: (1) adding an epoxy silane coupling agent into an organic solvent; after stirring and mixing well, adding an amine curing agent and distilled water; stirring for about 20-50 min and adding micron-sized solid particles and hydrophobic nano SiO.sub.2 particles; continuing stirring for about 1-3 hours to obtain a hydrophilic layer solution; (2) adding a hydrophobic modifier and a hydrophilic nano SiO.sub.2 particles into a second solvent, and stirring and mixing to obtain a hydrophobic layer solution; and (3) coating a pretreated substrate surface with the hydrophilic layer solution prepared in the step (1), performing heating treatment at about 60° C. to 80° C. for about 10-50 minutes; coating the surface with the hydrophobic layer solution obtained in the step (2), performing heating treatment at about 100° C. to 140° C. for about 50-90 minutes.

2. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the epoxy silane coupling agent in the step (1) refers to an organosilane compound containing an epoxy group and at least one group selected from a methoxy group, an ethoxy group, a chloro group, and an acetoxy group; the organic solvent is at least one of methanol, ethanol, and isopropyl alcohol.

3. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the amine curing agent described in the step (1) is at least one of octadecylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine.

4. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the micron-sized solid particles in the step (1) are at least one of micron-sized silicon dioxide, aluminum oxide, zinc oxide, and corundum.

5. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the parts by weight of each material in the step (1) are as follows: about 2-5 parts of the epoxy silane coupling agent, about 20-50 parts of organic solvent, about 0.5-3 parts of the amine curing agent, about 0.5-3 parts of the distilled water, about 0-0.5 part of the micron-sized solid particles, and about 0.2-0.6 part of the hydrophobic nano SiO.sub.2 particles.

6. The method of preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the temperature is maintained in the range about 25° C. to 40° C. during the preparation of the hydrophilic layer solution in the step (1).

7. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the hydrophobic modifier in the step (2) is at least one of hexamethyldisilazane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, methyltrimethoxysilane, and methyltriethoxysilane; the second solvent is at least one of methanol, ethanol, propylene glycol, isopropanol, isobutanol, butanol, glycerin, and tetrahydrofuran.

8. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the parts by weight of each material in the step (2) are as follows: about 2-6 parts of the hydrophobic modifier, about 10-50 parts of the second solvent, and about 0.05-0.3 part of the hydrophilic nano SiO.sub.2 particles.

9. The method for preparing a durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film according to claim 1, characterized in that: the substrate in the step (3) is selected from glass, iron, copper, aluminum, and cement; the pretreatment comprises ultrasonic cleaning in a mixture of ethanol and acetone followed by washing with deionized water and drying.

10. A durable hydrophilic-super-hydrophobic bipolar self-cleaning composite film, made in accordance with method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 and 2 are schematic diagrams showing a covalent bonding reaction between a hydrophilic layer and a substrate and a covalent bonding reaction between a hydrophilic layer and a hydrophobic layer of the present disclosure when the substrate is glass;

(2) FIG. 3 is a schematic structural diagram of the hydrophilic-super-hydrophobic self-cleaning composite film of the present disclosure when the substrate is glass;

(3) FIG. 4 is a scanning electron micrograph of a hydrophilic-super-hydrophobic self-cleaning composite film obtained in Example 1 of the present disclosure;

(4) FIG. 5 is a graph showing the results of contact angle test of the hydrophilic-super-hydrophobic self-cleaning composite film obtained in Example 1 of the present disclosure; and

(5) FIG. 6 is a graph showing the relationship between durability and wettability of the hydrophilic-super-hydrophobic self-cleaning composite film obtained in Example 1 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) The present disclosure will be further described in detail below with reference to examples and accompanying drawings, but the embodiments of the present disclosure are not limited thereto. It will be appreciated that the examples presented herein may include more or fewer steps and materials.

Example 1

(7) (1) A glass slide was placed in a beaker so as to be placed in an ultrasonic cleaner to get cleaned ultrasonically at about 70 Hz in turn with ethanol, acetone and deionized water for about 20 min, and was finally taken out to be blown dry by a dryer to get ready for use.

(8) (2) 3 parts by weight of γ-glycidyloxypropyltrimethoxysilane were added to a beaker containing about 32 parts of an ethanol solution to undergo magnetic stirring in a water bath at a constant temperature of about 30° C. for 1 h; the beaker was taken out of the water bath, 1 part of deionized water and then 1 part of octadecylamine were added to the beaker, and the beaker continued to be stirred in a water bath at a constant temperature until the solid was completely dissolved; the beaker was taken out of the water bath, and about 0.2 part of micron-sized silicon dioxide particles and about 0.4 part of hydrophobic nano silicon dioxide particles (Aladdin Reagent) were added to the beaker, which then continued to be stirred at a constant temperature for about 2 h.

(9) (3) 4 parts of hexamethyldisilazane were added to the beaker by a measuring cylinder, about 10 parts of an ethanol solution and about 0.05 part of hydrophilic nano silicon dioxide particles with a particle size of 7-40 nm (Aladdin Reagent) were then added to the beaker, and the beaker was magnetically stirred for about 30 min.

(10) (4) The solution prepared in the step (2) was dripped on the cleaned glass slide that, after the coating film was uniform, was then placed in an oven to get dried at about 80° C. for about 30 min to evaporate the ethanol, thereby obtaining a hydrophilic film layer.

(11) (5) After the glass slide prepared in the step (4) was taken out, the solution prepared in the step (3) was also applied to the hydrophilic film layer by a drip coating method, and then the sample was placed in an oven at about 140° C. to get dried for about 80 min, thereby obtaining the hydrophilic-super-hydrophobic bipolar composite film of this example. Under such conditions, the ethanol on the surface of the sample volatilized, and the dehydration condensation between the hydrophilic layer and the substrate and between the hydrophilic layer and the hydrophobic layer formed a covalent bond, enhancing the ability of the super-hydrophobic surface to resist external forces.

(12) A scanning electron micrograph of the hydrophilic-super-hydrophobic self-cleaning composite film obtained in this example was shown in FIG. 4; and the contact angle test results thereof were shown in FIG. 5.

(13) The durability and the wettability of the hydrophilic-super-hydrophobic self-cleaning composite film obtained in this example were tested according to the following specific test steps: Durability was tested by sanding: A sample was placed on a sandpaper of about 1200 mesh and tested at a wear distance of about 17 cm each under a weight of about 20 g. Wettability: The contact angle was measured by a contact angle meter of Dataphysics OCA 2.0, and the rolling angle was measured by a laboratory-made device. The contact angle and the rolling angle were measured after every 5 wear tests. The contact angle and the rolling angle were tested at 5 different points of the sample each time, and the average was taken as the test result.

(14) The relationship between the durability and the wettability of the obtained hydrophilic-super-hydrophobic self-cleaning composite film was shown in FIG. 6.

(15) From the above results, it can be seen that the super-hydrophobic surface prepared by the present disclosure could withstand about 180 times of friction loss while maintaining its super-hydrophobicity. During the friction test, the contact angle of the surface changed from 166° to the final 150°, and the rolling angle changed from the initial 2° to a small change in the friction test, and then to being rapidly over about 90° after being subjected to about 180 times of wear, indicating that there was a strong bonding force between the coating and the substrate, which was broken after a certain abrasion, such that the coating was detached from the surface to result in loss of the super-hydrophobicity of the surface.

Example 2

(16) (1) An aluminum sheet that had been subjected to surface blasting was placed in a beaker so as to be placed in an ultrasonic cleaner to get cleaned ultrasonically at about 60 Hz in turn with ethanol, acetone and deionized water for about 10 min, and then it was taken out to be blown dry by a dryer to get ready for use.

(17) (2) 5 parts by weight of 3-(2,3-epoxypropoxy)propyltriethoxysilane were added to a beaker containing 32 parts of an ethanol solution to undergo magnetic stirring in a water bath at a constant temperature of about 35° C. for about 1 h; the beaker was taken out of the water bath, about 0.5 part of deionized water and then 2 parts of octadecylamine were added to the beaker, and the beaker continued to be stirred in a water bath at a constant temperature; the beaker was taken out, about 0.6 part of hydrophobic nano silicon dioxide particles were added to the beaker, and the beaker continued to be stirred at a constant temperature for about 2 h.

(18) (3) 4 parts of hexamethyldisilazane were added to the beaker by a measuring cylinder, about 10 parts of an ethanol solution and about 0.1 part of hydrophilic nano silicon dioxide particles with a particle size of about 7-40 nm were then added to the beaker, and the beaker was magnetically stirred for about 30 min.

(19) (4) The solution prepared in the step (2) was dripped on the cleaned aluminum sheet that, after the coating film was uniform, was then placed in an oven to get dried at about 80° C. for about 30 min to evaporate the ethanol, thereby obtaining a hydrophilic film layer.

(20) (5) After the aluminum sheet prepared in the step (4) was taken out, the solution prepared in the step (3) was also applied to the hydrophilic film layer by a drip coating method, and then the sample was placed in an oven at about 140° C. to get dried for about 60 min, thereby obtaining the hydrophilic-super-hydrophobic bipolar composite film of this example. Under such conditions, the ethanol on the surface of the sample volatilized, and the dehydration condensation between the hydrophilic layer and the substrate and between the hydrophilic layer and the hydrophobic layer formed a covalent bond, enhancing the ability of the super-hydrophobic surface to resist external forces.

Example 3

(21) (1) An iron sheet that had been subjected to surface blasting was placed in a beaker so as to be placed in an ultrasonic cleaner to get cleaned ultrasonically at about 60 Hz in turn with ethanol, acetone and deionized water for about 10 min, and then it was washed with a mixed solution (pH=about 12) of sodium hydroxide and sodium nitrite as an alkali washing solution, and finally taken out to be blown dry by a dryer to get ready for use.

(22) (2) 2 parts by weight of γ-glycidyloxypropyltrimethoxysilane were added to a beaker containing about 32 parts of an ethanol solution to undergo magnetic stirring in a water bath at a constant temperature of about 30° C. for about 1 h; the beaker was taken out of the water bath, 3 parts of deionized water and then 1 part of triethylenetetramine were added to the beaker, and the beaker continued to be stirred in a water bath at a constant temperature until the solid was completely dissolved; the beaker was taken out, about 0.2 part of hydrophobic nano silicon dioxide particles were added to the beaker, and the beaker continued to be stirred at a constant temperature for about 2 h.

(23) (3) 4 parts of hexamethyldisilazane were added to the beaker by a measuring cylinder, about 10 parts of an ethanol solution and 0.1 part of hydrophilic nano silicon dioxide particles with a particle size of about 7-40 nm were then added to the beaker, and the beaker was magnetically stirred for about 30 min.

(24) (4) The solution prepared in the step (2) was dripped on the cleaned iron sheet that, after the coating film was uniform, was then placed in an oven to get dried at about 80° C. for about 30 min to evaporate the ethanol, thereby obtaining a hydrophilic film layer.

(25) (5) After the iron sheet prepared in the step (4) was taken out, the solution prepared in the step (3) was also applied to the hydrophilic film layer by a drip coating method, and then the sample was placed in an oven at about 140° C. to get dried for about 60 min, thereby obtaining the hydrophilic-super-hydrophobic bipolar composite film of this example. Under such conditions, the ethanol on the surface of the sample volatilized, and the dehydration condensation between the hydrophilic layer and the substrate and between the hydrophilic layer and the hydrophobic layer formed a covalent bond, enhancing the ability of the super-hydrophobic surface to resist external forces.

Example 4

(26) (1) A copper sheet that had been subjected to surface blasting was placed in a beaker so as to be placed in an ultrasonic cleaner to get cleaned ultrasonically at about 60 Hz in turn with ethanol, acetone and deionized water for about 10 min, and then it was washed with a mixed solution (pH=about 12) of sodium hydroxide and sodium nitrite as an alkali washing solution, and finally taken out to be blown dry by a dryer to get ready for use.

(27) (2) 3.1 parts by weight of 2-(3,14-epoxycyclohexyl)ethyltrimethoxysilane were added to a beaker containing about 32 parts of an ethanol solution to undergo magnetic stirring in a water bath at a constant temperature of about 30° C. for about 1 h; the beaker was taken out of the water bath, 1 part of deionized water and then 3 parts of hexamethylenediamine were added to the beaker, and the beaker continued to be stirred in a water bath at a constant temperature until the solid was completely dissolved; the beaker was taken out, about 0.3 part of hydrophobic nano silicon dioxide particles were added to the beaker, and the beaker continued to be stirred at a constant temperature for about 2 h.

(28) (3) 4 parts of hexamethyldisilazane were added to the beaker by a measuring cylinder, about 10 parts of an ethanol solution and about 0.05 part of hydrophilic nano silicon dioxide particles with a particle size of about 7-40 nm were then added to the beaker, and the beaker was magnetically stirred for about 30 min.

(29) (4) The solution prepared in the step (2) was dripped on the cleaned copper sheet that, after the coating film was uniform, was then placed in an oven to get dried at about 80° C. for about 30 min to evaporate the ethanol, thereby obtaining a hydrophilic film layer.

(30) (5) After the copper sheet prepared in the step (4) was taken out, the solution prepared in the step (3) was also applied to the hydrophilic film layer by a drip coating method, and then the sample was placed in an oven at about 140° C. to get dried for about 60 min, thereby obtaining the hydrophilic-super-hydrophobic bipolar composite film of this example. Under such conditions, the ethanol on the surface of the sample volatilized, and the dehydration condensation between the hydrophilic layer and the substrate and between the hydrophilic layer and the hydrophobic layer formed a covalent bond, enhancing the ability of the super-hydrophobic surface to resist external forces.

(31) The above examples are exemplary embodiments of the present disclosure, but the embodiments of the present disclosure are not limited thereto, and any other alterations, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present disclosure should all be equivalent replacements and included in the scope of protection of the present disclosure.