CN114345663B

CN114345663B - Preparation method of PDMS-based high-adhesion superhydrophobic surface

Info

Publication number: CN114345663B
Application number: CN202111587540.0A
Authority: CN
Inventors: 栗大超; 陈浩; 李小平
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2021-12-23
Filing date: 2021-12-23
Publication date: 2023-05-30
Anticipated expiration: 2041-12-23
Also published as: CN114345663A

Abstract

The invention provides a preparation method of a PDMS-based high-adhesion superhydrophobic surface, which comprises the following steps: (1) pretreatment of sand paper: ultrasonically cleaning sand paper, drying and fixing the sand paper at the bottom of a culture dish; (2) preparing a PDMS surface having a microstructure: pouring the PDMS prepolymer solution into a culture dish, vacuum degassing, transferring into an oven for solidification, cooling to room temperature, and stripping with sand paper to obtain the PDMS surface with a microstructure; (3) fluorination treatment: carrying out surface fluorination treatment on the surface of the PDMS microstructure in a vacuum environment at 80-100 ℃ by adopting a vapor deposition method, so as to obtain a super-hydrophobic PDMS surface with high adhesion; the PDMS super-hydrophobic surface with high adhesion prepared by the method has excellent hydrophobic performance, not only shows higher static contact angle, but also has higher contact angle hysteresis and high adhesion.

Description

Preparation method of PDMS-based high-adhesion superhydrophobic surface

Technical Field

The invention relates to the technical field of super-hydrophobic surface preparation, in particular to a preparation method of a high-adhesion super-hydrophobic surface based on PDMS.

Background

Wettability is one of the important properties of a material surface, typically a surface with a contact angle less than 90 ° is referred to as a hydrophilic surface, a surface with a contact angle greater than 90 ° is referred to as a hydrophobic surface, and a superhydrophobic surface is a special surface with a static contact angle of water over 150 ° on the surface. The superhydrophobic surface can be classified into a low-adhesion superhydrophobic surface and a high-adhesion superhydrophobic surface according to the difference of the adhesion properties of the surface to water drops. Compared with the low-adhesion superhydrophobic surface, the high-adhesion surface is one of the hot spot fields of current research due to the wide application of the surface in the directions of liquid drop collection, liquid transportation, biochemical analysis, cell culture and the like.

The superhydrophobic high-adhesion surface can be realized by constructing a micro-nano structure on the surface and introducing low-surface-energy chemical components. At present, a plurality of methods for preparing the high-adhesion superhydrophobic surface, such as a sol-gel method, a chemical etching method, a laser etching method, a template method, an electroplating method and the like, have the problems of complicated operation process, high cost, difficulty in considering superhydrophobic property and adhesion and the like.

PDMS (polydimethylsiloxane) has the advantages of good mechanical property, strong biocompatibility, easiness in processing and molding and the like, and is widely applied to the fields of flexible electronic devices and microfluidic chips. Research on how to construct a high adhesion surface based on PDMS, and effectively apply the PDMS to droplet manipulation, has a very high application prospect.

Disclosure of Invention

The invention aims to provide a preparation method of a PDMS-based high-adhesion superhydrophobic surface.

In order to solve the technical problems, the technical scheme of the invention is as follows:

the preparation method of the PDMS-based high-adhesion superhydrophobic surface comprises the following specific steps:

(1) Pretreatment of sand paper: ultrasonically cleaning sand paper, drying and fixing the sand paper at the bottom of a culture dish;

(2) Preparing a PDMS surface having a microstructure: pouring the PDMS prepolymer solution into a culture dish, vacuum degassing, transferring into an oven for solidification, cooling to room temperature, and stripping with sand paper to obtain the PDMS surface with a microstructure;

(3) And (3) fluorination treatment: and (3) carrying out surface fluorination treatment on the PDMS microstructure surface in a vacuum environment at 80-100 ℃ by adopting a vapor deposition method, so as to obtain the super-hydrophobic PDMS surface with high adhesion.

Preferably, in the method for preparing the PDMS-based high-adhesion superhydrophobic surface, the sand paper in the step (1) is 600 mesh waterproof sand paper.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the reagent used for ultrasonic cleaning in the step (1) is absolute ethanol, and the ultrasonic time is 5 minutes.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the PDMS prepolymer solution in the step (2) is obtained by mixing a PDMS preset agent and a curing agent, wherein the mass ratio of the PDMS preset agent to the curing agent is 10:1. The PDMS preset agent and the curing agent are both commercial products.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the curing temperature in the step (2) is 60 ℃, and the reaction time is 4 hours.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the characteristic dimension of the PDMS surface having the microstructure in the step (2) is 8-80 μm.

Preferably, the preparation method of the PDMS-based high-adhesion superhydrophobic surface, wherein the vapor deposition method in the step (3) is as follows: and (3) placing the PDMS surface with the microstructure obtained in the step (2), an open heat conduction container, a heating plate and a power supply together in a vacuum dryer, then dripping 100 mu L of fluorosilane reagent on the open container, and vacuumizing for 1 hour.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the surface with the microstructure of the PDMS surface obtained in the step (2) is upward, the open heat-conducting container is placed on a heating plate, and the fluorosilane reagent is dripped into the open heat-conducting container.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the material of the open heat-conducting container is tin foil, the heating sheet is a PTC heating sheet with constant temperature of 100 ℃, the power supply is a 12V direct current lithium battery, and the fluorosilane reagent is perfluorodecyl trichlorosilane, perfluorooctyl trichlorosilane or hexamethyldisilazane.

Preferably, in the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the contact angle of the high-adhesion superhydrophobic PDMS surface in the step (3) is 162.2 °, and the water drop with the size of 35 μl can be adsorbed maximally.

The beneficial effects are that:

according to the preparation method of the PDMS-based high-adhesion superhydrophobic surface, the prepared high-adhesion PDMS superhydrophobic surface has excellent hydrophobicity, not only shows a higher static contact angle, but also has higher contact angle hysteresis and high adhesion; the operation is simple, no complex equipment is needed, no dangerous chemical reagent such as strong acid and alkali is needed, and the method is suitable for batch production; in addition, the PDMS has the characteristics of biocompatibility, no toxicity and the like, can be well attached to a rigid surface or a flexible surface, and can be widely applied to wearable equipment and industrial robots.

Drawings

FIG. 1 is a flow chart of a preparation method of a PDMS super-hydrophobic surface with high adhesion;

FIG. 2 is an electron micrograph of a PDMS surface having a microstructure according to the present invention;

FIG. 3 is a schematic diagram of an experimental set-up for the fluorination treatment of the present invention;

FIG. 4 is an electron micrograph of a highly adherent superhydrophobic PDMS surface prepared according to the present invention;

FIG. 5 is a static contact angle of a water droplet on a highly adherent superhydrophobic PDMS surface prepared according to the present invention;

FIG. 6 is a morphology of water droplets at different positions when the surface of the highly adhesive super-hydrophobic PDMS prepared according to the present invention is curved;

fig. 7 is a graph of the test of adsorption of water droplets of different volumes on the surface of the highly adhesive superhydrophobic PDMS prepared according to the present invention.

Detailed Description

The following describes in further detail the embodiments of the present invention with reference to the drawings and examples.

Example 1

Fig. 1 is an experimental flow chart for preparing a PDMS superhydrophobic surface with high adhesion according to the present invention, which comprises the following steps:

(1) Pretreatment of sand paper:

cutting 600 mesh sand paper into 5cm x5cm size, cleaning with absolute ethanol as solvent in ultrasonic cleaner for 5min, and removing surface lipid and organic matters. And then washing the sand paper by using deionized water to remove the absolute ethyl alcohol remained on the surface, and naturally drying the sand paper at room temperature. The dried sandpaper was then placed with its rough surface facing up and secured to the bottom of the petri dish with double sided tape for use.

(2) Preparing a PDMS surface having a microstructure:

and taking the pretreated sand paper as a template. Presetting agent of PDMS: mixing the curing agents (Sylgard 184 curing agents) according to the mass ratio of 10:1, stirring until the bubbles are uniformly poured into a sand paper culture dish, pumping out the bubbles by using a vacuum pump, and heating the culture dish in an oven at 60 ℃ for 4 hours after the bubbles disappear, so that the PDMS is cured and molded. And after the solidified PDMS is cooled, tearing off the PDMS covered on the sand paper by using tweezers to obtain the microstructure surface opposite to the sand paper. Fig. 2 is an SEM image of a PDMS surface having a microstructure, and it can be seen from fig. 2 that the PDMS surface topography having a microstructure consists of smooth interconnected ridges and micro-scale pores, which illustrates that sandpaper is an effective template for preparing a microstructured PDMS surface.

(3) And (3) fluorination treatment:

as shown in fig. 3, the PDMS surface having the microstructure was placed in a vacuum dryer, and 100 μl of perfluorodecyl trichlorosilane was dropped into an open container made of tin foil using a dropper, then the open container was placed on a PTC heating plate having a constant temperature of 100 ℃, and after switching on a 12V direct current lithium battery switch connected to the PTC heating plate, vacuum was applied by a vacuum pump and maintained for 1 hour, to obtain a superhydrophobic PDMS surface having high adhesion. Fig. 4 is an SEM image of a highly adhered PDMS superhydrophobic surface, and it can be seen from fig. 4 that the highly adhered PDMS superhydrophobic surface is formed into a uniform and dense micro-nano structure, and this particular structure determines that it has superior surface wettability and adhesion.

The static contact angle of the high-adhesion superhydrophobic PDMS surface prepared in example 1 was measured using a contact angle measuring instrument. As shown in fig. 5, the static contact angle reached 162.2 °, showing excellent hydrophobicity. In the test, 5. Mu.L of water drops are dripped on the surface of the super-hydrophobic PDMS with the specification of 50mmx20mm, and the surface is tested for 5 times at different positions, and the average value is taken as a static contact angle.

The ability of the highly adherent superhydrophobic PDMS surface prepared in example 1 above to adsorb water droplets in different forms was tested. Fig. 6 shows that 5 water droplets of 5 μl were distributed on the curved superhydrophobic PDMS surface, and as can be seen from fig. 6, neither the water droplets were dropped nor too much shape change occurred, indicating that the superhydrophobic PDMS surface of high adhesion had some adhesion to the water droplets.

The ability of the highly adhered superhydrophobic PDMS surface prepared in example 1 above to adsorb water droplets when it was inverted was tested, as shown in fig. 7, by sequentially adding water droplets (2 μl each) to the highly adhered superhydrophobic PDMS surface using a syringe until the droplets could not adhere to the surface and fall. After the last drop addition and drop, the volume of the previous drop of suspension was noted as the volume of its largest adhering drop. It can be seen that the prepared super-hydrophobic PDMS with high adhesion can be adhered with water drops with the volume of 35 mu L at maximum, and the super-strong adhesion is shown.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. A preparation method of a PDMS-based high-adhesion superhydrophobic surface is characterized by comprising the following steps: the method comprises the following specific steps:

(1) Pretreatment of sand paper: carrying out ultrasonic cleaning on 600-mesh waterproof abrasive paper, and fixing the waterproof abrasive paper at the bottom of a culture dish after drying;

(2) Preparing a PDMS surface having a microstructure: pouring a PDMS prepolymer solution into a culture dish, wherein the PDMS prepolymer solution is obtained by mixing a PDMS preset agent and a curing agent, the mass ratio of the PDMS preset agent to the curing agent is 10:1, transferring the PDMS preset agent to an oven for curing after vacuum degassing, the curing temperature is 60 ℃, the reaction time is 4 hours, and peeling off the PDMS prepolymer after cooling to room temperature to obtain a PDMS surface with a microstructure, wherein the characteristic size is 8-80 mu m;

(3) And (3) fluorination treatment: carrying out surface fluorination treatment on the PDMS surface with the microstructure in a vacuum environment at 80-100 ℃ by adopting a vapor deposition method, so as to obtain a super-hydrophobic PDMS surface with high adhesion, wherein the contact angle of the super-hydrophobic PDMS surface with high adhesion is 162.2 degrees, and water drops with the size of 35 mu L can be adsorbed maximally, and the specific method comprises the following steps: and (3) placing the PDMS surface with the microstructure obtained in the step (2), an open heat conduction container, a heating plate and a power supply together in a vacuum dryer, then dripping 100 mu L of fluorosilane reagent on the open container, vacuumizing and keeping for 1 hour, wherein the open heat conduction container is made of tinfoil, the heating plate is a constant temperature PTC heating plate at 100 ℃, the power supply is a 12V direct current lithium battery, and the fluorosilane reagent is perfluorodecyl trichlorosilane, perfluorooctyl trichlorosilane or hexamethyldisilazane.

2. The method for preparing the PDMS-based high adhesion superhydrophobic surface according to claim 1, wherein: the reagent used for ultrasonic cleaning in the step (1) is absolute ethyl alcohol, and the ultrasonic time is 5 minutes.

3. The method for preparing the PDMS-based high adhesion superhydrophobic surface according to claim 1, wherein: the surface of the PDMS with the microstructure obtained in the step (2) is upwards provided with the microstructure, the opening heat conduction container is placed on the heating plate, and the fluorosilane reagent is dripped into the opening heat conduction container.