阅读说明：本技术 一种用于可控性液滴运输的特殊浸润性表面及其制备方法 (Special wettability surface for controllable liquid drop transportation and preparation method thereof ) 是由 刘慧� 张莉 罗欢 毛庆辉 于 2021-09-16 设计创作，主要内容包括：本发明属于材料制备技术领域,公开了一种用于可控性液滴运输的特殊浸润性表面及其制备方法。制备方法包括：S1.将PDMS加入THF与DMF的混合溶剂中,超声至完全溶解,得到疏水涂层液；S2.将PMMA和PDMS加入THF与DMF的混合溶剂中,超声至完全溶解,得到超疏水涂层液；S3.在基底表面设计液滴运输路径,将所述基地划分为第一区域和第二区域,所述第一区域对应所述液滴运输路径；S4.将所述疏水涂层液喷涂在所述第一区域上,将所述超疏水涂层液喷涂在所述第二区域上,得到用于可控性液滴运输的特殊浸润性表面。制备方法简单、成本低,且制备得到特殊浸润性表面可实现持续、稳定、可控的液体运输。(The invention belongs to the technical field of material preparation, and discloses a special wettability surface for controllable liquid drop transportation and a preparation method thereof. The preparation method comprises the following steps: s1, adding PDMS into a mixed solvent of THF and DMF, and performing ultrasonic treatment until the PDMS is completely dissolved to obtain a hydrophobic coating liquid; s2, adding PMMA and PDMS into a mixed solvent of THF and DMF, and performing ultrasonic treatment until the PMMA and PDMS are completely dissolved to obtain super-hydrophobic coating liquid; s3, designing a liquid drop transportation path on the surface of a substrate, and dividing the substrate into a first area and a second area, wherein the first area corresponds to the liquid drop transportation path; and S4, spraying the hydrophobic coating liquid on the first area, and spraying the super-hydrophobic coating liquid on the second area to obtain the special wettability surface for controllable liquid drop transportation. The preparation method is simple and low in cost, and the prepared special wettability surface can realize continuous, stable and controllable liquid transportation.)

1. A preparation method of a special wettability surface for controllable liquid drop transportation is characterized by comprising the following steps:

s1, adding PDMS into a mixed solvent of THF and DMF, and performing ultrasonic treatment until the PDMS is completely dissolved to obtain a hydrophobic coating liquid;

s2, adding PMMA and PDMS into a mixed solvent of THF and DMF, and performing ultrasonic treatment until the PMMA and PDMS are completely dissolved to obtain super-hydrophobic coating liquid;

s3, designing a liquid drop transportation path on the surface of a substrate, and dividing the substrate into a first area and a second area, wherein the first area corresponds to the liquid drop transportation path;

and S4, spraying the hydrophobic coating liquid on the first area, and spraying the super-hydrophobic coating liquid on the second area to obtain a special wettability surface for controllable liquid drop transportation, wherein the spraying is carried out by adopting an electrostatic spinning device.

2. The method according to claim 1, wherein the mass ratio of THF to DMF in the mixed solvent of THF and DMF is 1: 1.

3. The method according to claim 2, wherein in step S1, the mass ratio of the PDMS to the mixed solvent of THF and DMF is (1-4): 20.

4. the method according to claim 2, wherein in step S2, the mass ratio of the PMMA, the PDMS and the mixed solvent of the THF and the DMF is (1-3): (1-3): 20.

5. the method according to claim 2, wherein in step S2, the mass ratio of the PMMA, the PDMS, and the mixed solvent of THF and DMF is 1: 1: 20.

6. the method of claim 1, wherein in step S3, the substrate is selected from one of fabric, glass, titanium sheet, paper, and wood.

7. The method according to claim 1, wherein in step S4, the electrospinning device has a voltage of 15V, a flow rate of 0.05 to 0.5mL/h, and a take-up distance of 15 cm.

8. The production method according to claim 1, wherein in step S4, the electrospinning device has a voltage of 15V, a flow rate of 0.5mL/h, and a take-up distance of 15 cm.

9. A special wettability surface for controllable liquid drop transportation prepared by the preparation method of any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of material preparation, and relates to a special wettability surface for controllable liquid drop transportation and a preparation method thereof.

Background

The directional delivery of water flow is a common phenomenon in nature, and has great significance for various natural organisms and various applications such as microfluidic systems, ink-jet printing, liquid delivery and the like. Wettability, which is a fundamental property of solid surfaces, is determined by surface chemistry and topography and can in principle proceed from super-wettability to non-wettability. Inspired by the existing natural structure, the artificial bionic surface is constructed in a chemical heterogeneous structure or chemical gradient mode, so that the directional diffusion of liquid is controlled.

To direct and control droplet movement, chemically heterogeneous surfaces are generally created by building hydrophilic regions on a superhydrophobic surface, with a significantly non-uniform composition or distribution across the surface. Including the construction of biological coatings using photolithographic or inkjet printing methods, uv-enhanced chemical decomposition on superhydrophobic nanowire surfaces, uv-initiated surface photografting, inkjet layer patterned superhydrophobic surfaces, and laser treatment of superhydrophobic nanostructured surfaces. Although these techniques can provide good control over the directional spreading of the droplets, continuous delivery of the liquid remains challenging because of the difficulty in avoiding stagnation of the droplets during movement due to the presence of hydrophilic regions.

Disclosure of Invention

The invention aims to provide a preparation method of a special wettability surface for controllable liquid drop transportation, the special wettability surface realizes controllable transportation of liquid drops by utilizing surface wettability differences of different areas, and the continuity is good.

The invention provides the following technical scheme:

a preparation method of a special wettability surface for controllable liquid drop transportation comprises the following steps:

s1, adding PDMS into a mixed solvent of THF and DMF, and performing ultrasonic treatment until the PDMS is completely dissolved to obtain a hydrophobic coating liquid;

s2, adding PMMA and PDMS into a mixed solvent of THF and DMF, and performing ultrasonic treatment until the PMMA and PDMS are completely dissolved to obtain super-hydrophobic coating liquid;

s3, designing a liquid drop transportation path on the surface of a substrate, and dividing the substrate into a first area and a second area, wherein the first area corresponds to the liquid drop transportation path;

and S4, spraying the hydrophobic coating liquid on the first area, and spraying the super-hydrophobic coating liquid on the second area to obtain a special wettability surface for controllable liquid drop transportation, wherein the spraying is carried out by adopting an electrostatic spinning device.

Further, in the mixed solvent of THF and DMF, the mass ratio of THF to DMF is 1: 1.

Further, in step S1, the mass ratio of the PDMS to the mixed solvent of THF and DMF is (1-4): 20.

further, in step S2, the mass ratio of the PMMA, the PDMS, and the mixed solvent of the THF and the DMF is (1-3): (1-3): 20.

further, in step S2, the mass ratio of the PMMA, the PDMS, and the mixed solvent of THF and DMF is 1: 1: 20.

further, in step S3, the substrate is selected from one of fabric, glass, titanium sheet, paper, and wood.

Further, in step S4, the voltage of the electrostatic spinning device is 15V, the flow rate is 0.05-0.5 mL/h, and the receiving distance is 15 cm.

Further, in step S4, the voltage of the electrospinning device was 15V, the flow rate was 0.5mL/h, and the take-up distance was 15 cm.

The invention also provides the special wettability surface for controllable liquid drop transportation prepared by the preparation method.

The invention has the beneficial effects that:

the surface prepared by the method has the advantages of good mechanical property and stable chemical property, and the preparation process is simple and convenient without subsequent treatment, thereby saving time and energy; the substrate is universal and can be constructed on the surfaces of various substrates; the raw materials are low in cost, easy to obtain, free of fluorine and suitable for the requirement of environment-friendly development; the simple combination of the hydrophobic and super-hydrophobic modes on a single surface realizes continuous, stable and controllable liquid transportation, and the special wettability surface can be sprayed on any form of substrate, so that the bonding force between the surface and the substrate is good, and a new thought is provided for developing a microfluidic device and continuously controlling the mobility of liquid drops.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein the content of the first and second substances,

FIG. 1 is an SEM image (a) of the surface of a PDMS hydrophobic coating prepared in example 1 of the present invention, an SEM image (b) of the surface of a PMMA coating prepared in example 2, and an SEM image (c) of the surface of a PDMS/PMMA superhydrophobic coating prepared in example 3;

FIG. 2 is a graph of the surface static contact angle of a PDMS hydrophobic coating prepared in example 1 of the present invention (graph a), a PMMA coating prepared in example 2 (graph b), and a PDMS/PMMA superhydrophobic coating prepared in example 3 (graph c);

FIG. 3 is SEM images of the surfaces (particle morphology) of three PDMS/PMMA superhydrophobic coatings obtained in example 3;

FIG. 4 is a diagram of the transport of droplets in a specially wetted surface prepared in example 4 of the present invention;

FIG. 5 is an SEM image of the surface (part of fiber and part of particles) of the PDMS/PMMA superhydrophobic coating in comparative example 1 of the invention;

FIG. 6 is an SEM image of the surface (pure fiber) of the PDMS/PMMA superhydrophobic coating in comparative example 2 of the invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes or modifications can be made by those skilled in the art after reading the teaching of the present invention, and equivalents also fall within the scope of the claims of the present application.

Example 1: preparation of PDMS hydrophobic coating surface

Weighing 1g of PDMS, 10g of THF and 10g of DMF (mass ratio of 1: 10) and mixing and adding into a beaker, performing ultrasonic treatment at 40 ℃ to completely dissolve the PDMS, obtaining a hydrophobic coating liquid, using a cotton fabric as a substrate, designing a liquid drop transportation path on the surface of the substrate, and spraying the hydrophobic coating liquid on the transportation path through an electrostatic spinning device, wherein the electrostatic spraying conditions are that the voltage is 15V, the flow rate is 0.5mL/h, the receiving distance is 15cm, so as to obtain a PDMS hydrophobic coating surface, and an SEM picture is shown in figure 1(a), wherein the surface presents a gel layer and has no rough structure. The static contact angle is 121.7 ° as shown in fig. 2 (a).

Example 2: preparation of PMMA coating (Uniform particle) surface

Weighing 1g of PMMA, 10g of THF and 10g of DMF (mass ratio of 1: 10) and mixing and adding into a beaker, carrying out ultrasonic treatment at 40 ℃ to completely dissolve the PMMA to obtain a hydrophobic coating liquid, using cotton fabric as a substrate, designing a liquid drop transportation path on the surface of the substrate, and spraying the hydrophobic coating liquid on the transportation path through an electrostatic spinning device under the conditions of 15V voltage, 0.5mL/h flow and 15cm receiving distance to obtain a PMMA coating surface, wherein the surface is covered by a layer of uniform particles as shown in an SEM picture (figure 1 (b). The static contact angle was 151.8 ° as shown in fig. 2 (b). This demonstrates that the PMMA composition can be used to build a uniform particle structure by electrostatic spraying techniques.

Example 3: PDMS/PMMA super-hydrophobic coating (homogeneous particle) surface

Weighing 1g of PMMA, 1g of PDMS, 10g of THF and 10g of DMF (mass ratio of 1: 10) and adding into a beaker, and performing ultrasonic treatment at 40 ℃ to completely dissolve the PMMA and the PDMS to obtain the super-hydrophobic coating liquid. Continuously spraying the super-hydrophobic coating liquid on the cotton fabric substrate by an electrostatic spinning device under the electrostatic spraying condition that the voltage is 15V, the flow control is 0.05mL/h, 0.1mL/h and 0.5mL/h, the receiving distance is 15cm, and obtaining three different PDMS/PMMA super-hydrophobic coating surfaces.

Wherein, the SEM image of the surface of the PDMS/PMMA superhydrophobic coating obtained with the flow control of 0.5mL/h is shown in figure 1(c), and the static contact angle is shown in figure 2 (c). As can be seen from fig. 1(c) and fig. 2(c), the surface of the PDMS/PMMA superhydrophobic coating also presents a layer of uniform particles, and the contact angle is further increased to 164.8 °, which shows that the addition of the PDMS component further reduces the surface energy of the system and improves the superhydrophobic performance compared with the surface of the PMMA coating.

FIG. 3 is a SEM comparison of the surfaces of the three PDMS/PMMA superhydrophobic coatings, wherein (a) is a SEM of the surface of the PDMS/PMMA superhydrophobic coating obtained by controlling the flow rate to be 0.05 mL/h; (b) the figure is an SEM image of the surface of a PDMS/PMMA super-hydrophobic coating obtained by controlling the flow rate to be 0.1 mL/h; (c) the figure is an SEM image of the surface of a PDMS/PMMA superhydrophobic coating obtained by controlling the flow at 0.5 mL/h. According to FIG. 3, in the electrostatic spraying condition, when the flow rate is 0.05mL/h, 0.1mL/h and 0.5mL/h, the diameter of the obtained PDMS/PMMA particles is gradually increased, which means that the increase of the flow rate (spinning speed) of the electrostatic spinning device can improve the superhydrophobic performance of the finally obtained PDMS/PMMA superhydrophobic coating.

Example 4: preparation of special wettability surface (PDMS/PMMA super-hydrophobic coating is granular) for controllable liquid drop transportation

Step 1, weighing 1g of PDMS, 10g of THF and 10g of DMF (mass ratio of 1: 10), mixing, adding into a beaker, and performing ultrasonic treatment at 40 ℃ to completely dissolve the PDMS, thereby obtaining the hydrophobic coating liquid.

And 2, taking the cotton fabric as a substrate, and spraying the hydrophobic coating liquid on the substrate through an electrostatic spinning device under the electrostatic spraying condition that the voltage is 15V, the flow is 0.5mL/h, and the receiving distance is 15 cm.

And 3, weighing 1g of PMMA, 1g of PDMS, 10g of THF and 10g of DMF (mass ratio of 1: 10) and adding into a beaker, and performing ultrasonic treatment at 40 ℃ to completely dissolve the PMMA, the PDMS, the THF and the DMF to obtain the super-hydrophobic coating liquid.

And 4, covering the substrate obtained in the step 2 (the part covered by the pattern template is the pre-designed liquid drop transportation path) by using a pattern template with a liquid drop transportation path, then electrostatically spraying the PDMS/PMMA mixed solution under the conditions of 15V of voltage, 0.5mL/h of flow and 15cm of receiving distance, and removing the pattern template after spraying to obtain the special wettability surface with the liquid drop transportation path, namely the special wettability surface for controllable liquid drop transportation.

The water droplets are released from the beginning of the transportation path of the water droplets in the special wettability surface for controllable liquid droplet transportation obtained in example 4, and the transportation of the water droplets is observed, and as a result, as shown in fig. 4, the graphs (a) to (c) in fig. 4 show the transportation process of the water droplets, it can be seen that the water droplets can be continuously transported along the designed path based on the wettability difference.

Comparative example 1: PDMS/PMMA mixed coating (part of fiber, part of particle) surface

Weighing 3g of PMMA, 3g of PDMS, 10g of THF and 10g of DMF (mass ratio of 3: 10) and adding into a beaker, and performing ultrasonic treatment at 40 ℃ to completely dissolve the PMMA and the PDMS to obtain the super-hydrophobic coating liquid. And (3) spraying the super-hydrophobic coating liquid on a cotton fabric substrate by using an electrostatic spinning device, wherein the electrostatic spraying condition is that the voltage is 15V, the flow is 0.5mL/h, the receiving distance is 15cm, so that a PDMS/PMMA mixed coating is obtained, the coating contains both fibers and particles, and an SEM image is shown in figure 5.

Comparative example 2: PDMS/PMMA hybrid coating (pure fiber) surface

Weighing 4g of PMMA, 4g of PDMS, 10g of THF and 10g of DMF (mass ratio of 2: 5) into a beaker, and performing ultrasonic treatment at 40 ℃ to completely dissolve the PMMA, the PDMS, the THF and the DMF to obtain the super-hydrophobic coating liquid. And (3) spraying the super-hydrophobic coating liquid on a cotton fabric substrate by using an electrostatic spinning device, wherein the electrostatic spraying condition is that the voltage is 15V, the flow is 0.5mL/h, the receiving distance is 15cm, so that the surface of the PDMS/PMMA mixed coating is obtained, the coating is fibrous, and an SEM image is shown in figure 6.

While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.