Preparation method of bionic intelligent wetting surface with anisotropy and multi-excitation

Abstract

The invention discloses a preparation method of a bionic intelligent wetting surface with anisotropy and multi-excitation. The preparation method comprises the following steps: step 1, preparing three material systems for printing; comprising a material A, a material B and a material C, and 2, gradient surface preparation: S1, depositing the material A on a substrate by adopting a single-material extrusion type 3D printing method to form a plurality of uniform magnetic response hydrophobic layers which are distributed at intervals, and S2, distributing the material B and the material C on the substrate in a gradient mode by adopting a gradient material extrusion type 3D printing method to form a plurality of temperature response non-uniform hydrophilic layers, the temperature response non-uniform hydrophilic layer is located between two adjacent uniform magnetic response hydrophobic layers, the ratio of the material B to the material C is gradually distributed, the change ratio of the material B to the material C is from 90% of the material B to 10% of the material C to 10% of the material B to 90% of the material C, and post-treatment is carried out in a photocuring mode.

Description

Technical Field

[0001] The invention relates to the technical field of wettable surface preparation, and in particular to a method for preparing a bionic intelligent wettable surface with anisotropy and multi-excitation. Background Art

[0002] Directed liquid transport and manipulation have important applications in many fields, including microfluidics, bioassays, medical testing, printing, and oil-water separation technology. The anisotropic wetting behavior of material surfaces has important applications in liquid transport and guidance. The wonderful nature provides an excellent reference for the construction of wettable interfaces. Many natural biological material surfaces, such as rice leaves, butterfly wings, water bird feathers, and pitcher plants, all show gradient and dynamic anisotropic superwetting properties, which is mainly caused by the special microstructure and chemical composition distribution of the surface.

[0003] Nowadays, the preparation methods of bionic anisotropic wetting interface materials can be roughly divided into two categories, namely top-down methods (nanoimprinting, photolithography, template method and etching method, etc.) and bottom-up methods (layer-by-layer self-assembly method, wrinkling method and deposition method, etc.), which are mainly carried out according to two preparation ideas, namely, constructing anisotropically arranged geometric structures on the solid surface or chemically modifying the surface on the basis of constructing geometric structures. With the continuous development of technology and the gradual expansion of application fields, wettability surfaces with single properties can no longer meet the needs, and they are gradually tending towards material interfaces with diversified functions, strong adaptability and high stability. Based on this, more preparation materials and preparation methods are constantly being developed to obtain bionic intelligent wetting surfaces.

[0004] Although some of the above-mentioned traditional manufacturing technologies can be used to prepare anisotropic wetting surfaces, it is still difficult to accurately control the micro / nano multi-scale hierarchical structure and the heterogeneous distribution of multi-component materials during the preparation process, which has gradually become the main difficulty in the process of controlling surface / interface formation. With the help of 3D printing technology, a variety of substances with different wetting properties are introduced in the manufacturing process, and the multifunctional component materials are integrated in a coordinated and orderly manner. In addition, the array gradient structure of the sample surface is designed and reprocessed in combination with laser processing technology to control the transformation of the anisotropic wetting properties of the interface, which will help improve the directional transport of droplets. This provides a new way for the preparation and design of bionic structured surfaces and expands the current application of wettable surfaces. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the existing intelligent wetting surface has relatively single characteristics, and to provide a method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation.

[0006] The method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation comprises the following steps: Step 1: Prepare three material systems for printing; Material A: 67wt.%~92wt.% polydimethylsiloxane mixture mixed with 8wt.%~33wt.% magnetic responsive nanoparticles, showing hydrophobic properties; Material B: acrylamide is mixed with 1wt.%~5wt.% of a photoinitiator to form an acrylamide mixture, and then 8wt.%~92wt.% of the acrylamide mixture is mixed with magnetic responsive particles to form an acrylamide mixture with magnetic responsive particles, and 5wt.%~30wt.% of a thickener is mixed with the acrylamide mixture with magnetic responsive particles to present hydrophilic properties; Material C: N-isopropyl acrylamide and a photoinitiator are prepared in a ratio of 1wt.% to 5wt.% to form an N-isopropyl acrylamide mixture, 8wt.% to 92wt.% of acrylamide is mixed with magnetic responsive nanoparticles to form an acrylamide mixture with magnetic responsive particles, the N-isopropyl acrylamide mixture and the acrylamide mixture with magnetic responsive particles are mixed and a thickener accounting for 5wt.% to 30wt.% of the total weight is added, which is hydrophilic; Step 2: Gradient surface preparation: S1: Using a single-material extrusion 3D printing method, material A is deposited on a substrate to form multiple uniform magnetically responsive hydrophobic layers distributed at intervals. S2: A gradient material extrusion 3D printing method is used to distribute material B and material C on the substrate in a gradient pattern to form multiple temperature-responsive non-uniform hydrophilic layers. The temperature-responsive non-uniform hydrophilic layer is located between two adjacent uniform magnetically responsive hydrophobic layers. The ratio of material B and material C is distributed in a gradient pattern, wherein the ratio of material B and material C changes from 90% material B: 10% material C to 10% material B: 90% material C, and post-processing is performed by photocuring.

[0007] Preferably, the printing parameters for depositing material A on the substrate are: printing speed 1~10mm / s, printing layer thickness is about 0.2~0.3mm, printing thickness is about 0.6~0.8mm, the printing width of a single uniform magnetic response hydrophobic layer is about 1mm~3mm, and the interval width between two adjacent uniform magnetic response hydrophobic layers is 50~300μm; after printing, heat curing treatment is carried out at 80~95℃ for 2h~4h.

[0008] Preferably, the printing parameter ranges of material B and material C are: printing speed 5~20mm / s, printing layer thickness 0.2~0.4mm, printing thickness 0.6~0.8mm, and the printing width of a single temperature-responsive non-uniform hydrophilic layer is 1mm~3mm, and both are post-processed by photocuring.

[0009] Preferably, the method further comprises S3: using a laser etching method to process the surface micro-nano structure of the surface prepared above.

[0010] Preferably, the surface micro-nano structure morphology includes but is not limited to a lotus leaf papillae-like structure, a cactus thorn-like cone structure, a duck tongue-like structure imitating the mouth edge of a pitcher plant, and the like.

[0011] Preferably, an ultraviolet nanosecond laser is used for surface scanning laser processing, the laser processing power is 1W~5W, the laser scanning speed is 100~500mm / s, and the laser processing frequency is 5~20kHz.

[0012] The beneficial effects of the present invention include: The existence of anisotropic structures can effectively control the morphology of droplets and facilitate the directional transport of droplets; Under different stimulation conditions, water droplets will present different shapes on the smart wetting surface, thus exacerbating Directed movement of droplets. Applying a magnetic field can change the surface to a hydrophobic direction, which is beneficial to the transfer of droplets. Increasing the temperature can cause the thermosensitive material to shrink and drain water, causing the surface to change to a hydrophobic direction. Due to the gradient distribution of the thermosensitive material, the hydrophobic property also presents a gradient characteristic, which enables the droplets to transfer to the side with relatively weaker hydrophobic property. Using gradient 3D printing technology and heterogeneous material composition system, we prepare smart surfaces with material gradient and structural gradient, which produce morphological changes and wettability changes under different stimulus responses. Through the synergistic effect of the dual gradient of material-structure and multiple stimuli, we achieve the directional movement of droplets. The present invention mixes and distributes magnetically responsive particles and thermosensitive hydrogel materials with two elastomeric materials with different wetting properties. First, the two materials are arranged in a staggered manner in lines using an extrusion gradient 3D printing manufacturing method, wherein the magnetically responsive particles are evenly distributed in the two materials, and the thermosensitive material is distributed in a gradient pattern in the extrusion line of one of the materials. Subsequently, a laser etching method is combined to realize the manufacture of a surface micro-nano bionic structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below.

[0014] Figure 1 Schematic diagram of the distribution of uniform magnetically responsive hydrophobic layer and temperature-responsive non-uniform hydrophilic layer; Figure 2 It is a schematic diagram of the overall wetting performance transformation under temperature excitation conditions of the present invention; Figure 3 It is a schematic diagram of the change of wetting properties and droplet transfer caused by temperature excitation along the material gradient direction of the present invention. DETAILED DESCRIPTION

[0015] The present invention provides a design and preparation method of anisotropic and wettability gradient smart surface with multi-stimulus response. In order to make the technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] According to the material composition of the designed smart surface, three material systems for printing need to be prepared. Material system A is composed of polydimethylsiloxane (PDMS) and Co powder, and is hydrophobic. Material system B is composed of acrylamide (PAM), photoinitiator, Co powder and nanoclay lithium magnesium silicate, and is hydrophilic. Material system C is composed of N-isopropylacrylamide (NIPAM), photoinitiator, Co powder, nanoclay lithium magnesium silicate, and is hydrophilic.

[0017] The preparation method of the bionic intelligent wetting surface with anisotropy and multi-excitation comprises the following steps: Step 1: Preparation of the material system, according to the material composition of the designed intelligent surface, three kinds of The material system used for printing; Material A: 67wt.%~92wt.% polydimethylsiloxane mixture (PDMS and curing agent are prepared in a mass ratio of 10:1) mixed with 8wt.%~33wt.% Co powder, showing hydrophobic properties; Material B: Acrylamide (PAM) is mixed with 1wt.%~5wt.% photoinitiator to form an acrylamide mixture, and then 8wt.%~92wt.% of the acrylamide mixture is mixed with Co powder to form an acrylamide mixture with magnetic responsive particles, and 5wt.%~30wt.% nanoclay lithium magnesium silicate is mixed with the acrylamide mixture with magnetic responsive particles to present hydrophilic properties to increase printability; Material C: N-isopropylacrylamide (NIPAM) and a photoinitiator are prepared in a ratio of 1wt.% to 5wt.% to form an N-isopropylacrylamide mixture, 8wt.% to 92wt.% of acrylamide is mixed with Co powder to form an acrylamide mixture with magnetic responsive particles, the N-isopropylacrylamide mixture and the acrylamide mixture with magnetic responsive particles are mixed and nanoclay lithium magnesium silicate is added at a total weight ratio of 5wt.% to 30wt.% to increase printability; After being stirred evenly with a magnetic stirrer, the materials are loaded into a printing syringe and mixed with a planetary stirrer for the next step of printing. Step 2. Design and preparation of gradient material surface: 1) Using a single-material extrusion 3D printing method, deposit material A on Figure 1 The interval strip area 1 shown is recorded as a uniform magnetic responsive hydrophobic layer. The printing speed is 1-10 mm / s, the printing layer thickness is about 0.2-0.3 mm, the printing thickness is about 0.6-0.8 mm, the printing width is about 1 mm-3 mm, and the strip interval width is about 50-300 μm. After printing, it is heat-cured at 95°C for 2 hours. 2) Using the gradient material extrusion 3D printing method, material B and material C are distributed in a gradient pattern. Figure 1 The interval strip area 2 shown is recorded as a temperature-responsive non-uniform hydrophilic layer, the ratio of material B and material C is linearly distributed, and the mass ratio of the two materials changes linearly from 90wt.% material B: 10wt.% material C to 10wt.% material B: 90wt.% material C. The printing parameter ranges of the two materials are: printing speed 5~20mm / s, printing layer thickness 0.2~0.4mm, printing thickness 0.6~0.8mm, printing width 1mm~3mm, and both are post-processed by light curing; Step 3. Using laser processing technology, refer to the morphological and structural characteristics of biological surfaces, process the surface prepared above to form a lotus leaf papilla structure, a cactus thorn cone structure, a duck tongue structure of the mouth of a pitcher plant, etc., to roughen the surface. Then, use anhydrous ethanol and deionized water to clean the surface. Use a contact angle meter to test the surface wettability.

[0018] The designed smart wetting surface has wetting state changes under multiple excitation conditions, and the effects are as follows Figure 3 As shown, specifically: In the initial state, since regions 1 and 2 are divided into hydrophobic and hydrophilic states, the droplet will tend to be hydrophilic, which is state 1.

[0019] When the anisotropic surface is stimulated by a magnetic field, the effect of the magnetic Fe3O4 particles causes the surface to become rougher as a whole, and region 1 changes toward superhydrophobicity, transforming into state 2.

[0020] When the anisotropic surface is stimulated by temperature, the overall wettability of region 2 changes from a hydrophilic state to a hydrophobic state because PNIPAM has the function of shrinking and draining water after reaching the critical solution temperature. At the same time, due to the gradient distribution of PNIPAM, the wettability of region 2 shows a gradient change in the gradient distribution direction, and the water droplets move from the side with high PNIPAM content to the side with low PNIPAM content. Figure 2 As shown, this is state 3.

[0021] When the anisotropic surface is subjected to dual excitation of magnetic field and temperature at the same time, region 1 as a whole changes from a hydrophobic state to a superhydrophobic state, and region 2 as a whole changes from a hydrophilic state to a hydrophobic state, thus changing to state 4.

Claims

1. A method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation, characterized in that: The steps include: Step 1: Prepare three material systems for printing; Material A: 67wt.%~92wt.% polydimethylsiloxane mixture mixed with 8wt.%~33wt.% magnetic responsive nanoparticles, showing hydrophobic properties; Material B: acrylamide is mixed with 1wt.%~5wt.% of a photoinitiator to form an acrylamide mixture, and then 8wt.%~92wt.% of the acrylamide mixture is mixed with magnetic responsive particles to form an acrylamide mixture with magnetic responsive particles, and 5wt.%~30wt.% of a thickener is mixed with the acrylamide mixture with magnetic responsive particles to present hydrophilic properties; Material C: N-isopropyl acrylamide and a photoinitiator are prepared in a ratio of 1wt.% to 5wt.% to form an N-isopropyl acrylamide mixture, 8wt.% to 92wt.% of acrylamide is mixed with magnetic responsive nanoparticles to form an acrylamide mixture with magnetic responsive particles, the N-isopropyl acrylamide mixture and the acrylamide mixture with magnetic responsive particles are mixed and a thickener accounting for 5wt.% to 30wt.% of the total weight is added, which is hydrophilic; Step 2: Gradient surface preparation: S1: Using a single-material extrusion 3D printing method, material A is deposited on a substrate to form multiple uniform magnetically responsive hydrophobic layers distributed at intervals. S2: A gradient material extrusion 3D printing method is used to distribute material B and material C on the substrate in a gradient pattern to form multiple temperature-responsive non-uniform hydrophilic layers. The temperature-responsive non-uniform hydrophilic layer is located between two adjacent uniform magnetically responsive hydrophobic layers. The ratio of material B and material C is distributed in a gradient pattern, wherein the ratio of material B and material C changes from 90% material B: 10% material C to 10% material B: 90% material C, and post-processing is performed by photocuring.

2. The method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation according to claim 1, characterized in that: The printing parameters of material A deposited on the substrate are: printing speed 1~10mm / s, printing layer thickness is about 0.2~0.3mm, printing thickness is about 0.6~0.8mm, the printing width of a single uniform magnetic responsive hydrophobic layer is about 1mm~3mm, and the interval width between two adjacent uniform magnetic responsive hydrophobic layers is 50~300μm; after printing, heat curing treatment is carried out at 80~95℃ for 2h~4h.

3. The method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation according to claim 1, characterized in that: The printing parameter ranges of materials B and C are as follows: printing speed 5~20mm / s, printing layer thickness 0.2~0.4mm, printing thickness 0.6~0.8mm, and printing width of a single temperature-responsive non-uniform hydrophilic layer 1mm~3mm. Both materials are post-processed by photocuring.

4. The method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation according to claim 1, characterized in that: The method also includes S3: using a laser etching method to process the surface micro-nano structure of the surface prepared above.

5. The method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation according to claim 4, characterized in that: The surface micro-nano structure morphology includes but is not limited to a lotus leaf papillae-like structure, a cactus thorn-like cone structure, a pitcher plant-like duck tongue-like structure, and the like.

6. The method for preparing a bionic intelligent wetting surface with anisotropy and multi-excitation according to claim 4, characterized in that: An ultraviolet nanosecond laser is selected for surface scanning laser processing, the laser processing power is 1W~5W, the laser scanning speed is 100~500mm / s, and the laser processing frequency is 5~20kHz.

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