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

Abstract

The present invention discloses a preparation method of a bionic intelligent wetting surface with anisotropy and multi-excitation, comprising the following steps: Step 1: preparing three material systems for printing; including material A, material B, and material C; Step 2: gradient surface preparation: S1: using a single-material extrusion 3D printing method, depositing material A on a substrate to form a plurality of spaced-apart uniform magnetically responsive hydrophobic layers; S2: using a gradient material extrusion 3D printing method, distributing material B and material C in a gradient pattern on the substrate to form a plurality of temperature-responsive non-uniform hydrophilic layers, wherein the temperature-responsive non-uniform hydrophilic layer is located between two adjacent uniform magnetically responsive hydrophobic layers, and the ratio of material B to material C is distributed in a gradient manner, wherein the ratio of material B to material C changes from 90% material B: 10% material C to 10% material B: 90% material C, and post-processing is performed by photocuring.

Description

Technical Field

[0001] The present 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 a wide range of fields, including microfluidics, bioassays, medical testing, printing, and oil-water separation. The anisotropic wetting behavior of material surfaces plays a crucial role in liquid transport and guidance. The fascinating world of nature provides an excellent model for the construction of wettable interfaces. Many natural biomaterial surfaces, such as rice leaves, butterfly wings, waterfowl feathers, and pitcher plants, exhibit gradient and dynamic anisotropic superwettability, primarily due to the unique microstructure and chemical composition of the surfaces.

[0003] Currently, the preparation methods for biomimetic 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.). They are mainly carried out according to two preparation ideas, namely, constructing anisotropic geometric structures on the solid surface or chemically modifying the surface based on the constructed geometric structures. With the continuous development of technology and the gradual expansion of application fields, wettability surfaces with a single performance can no longer meet the needs, and 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 biomimetic 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 precisely control the micro / nano multi-scale hierarchical structure and the heterogeneous distribution of multi-component materials during the preparation process. This has gradually become the main difficulty in controlling the formation of surfaces / interfaces. With the help of 3D printing technology, a variety of substances with different wetting properties are introduced into 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. Controlling the transformation of the anisotropic wetting properties of the interface will help improve the directional transport of droplets. This provides a new approach for the preparation and design of biomimetic structured surfaces and expands the current applications 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 propose a preparation method of a bionic intelligent wetting surface with anisotropy and multi-excitation.

[0006] A method for preparing a biomimetic intelligent wetting surface with anisotropy and multi-excitation comprises the following steps:

[0007] Step 1: Prepare three material systems for printing;

[0008] Material A: 67wt.%~92wt.% polydimethylsiloxane mixture mixed with 8wt.%~33wt.% magnetic responsive nanoparticles, showing hydrophobic properties;

[0009] Material B: Acrylamide is mixed with 1 wt.% to 5 wt.% of a photoinitiator to form an acrylamide mixture, and then 8 wt.% to 92 wt.% of the acrylamide mixture is mixed with magnetically responsive particles to form an acrylamide mixture with magnetically responsive particles. 5 wt.% to 30 wt.% of a thickener is mixed with the acrylamide mixture with magnetically responsive particles to form a hydrophilic material.

[0010] Material C: N-isopropylacrylamide and a photoinitiator are prepared in a ratio of 1 wt.% to 5 wt.% to form an N-isopropylacrylamide mixture. 8 wt.% to 92 wt.% of acrylamide is mixed with magnetically responsive nanoparticles to form an acrylamide mixture with magnetically responsive particles. The N-isopropylacrylamide mixture and the acrylamide mixture with magnetically responsive particles are mixed and a thickener accounting for 5 wt.% to 30 wt.% of the total weight is added to form a hydrophilic material.

[0011] Step 2: Gradient surface preparation:

[0012] S1: Using a single-material extrusion 3D printing method, material A is deposited on a substrate to form multiple uniform magnetically responsive hydrophobic layers with intervals.

[0013] S2: Using a gradient material extrusion 3D printing method, materials B and C are distributed 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 to material C is distributed in a gradient pattern, where the ratio changes from 90% material B:10% material C to 10% material B:90% material C. Post-processing is performed using photocuring.

[0014] Preferably, the printing parameters for depositing material A on the substrate are: printing speed 1~10mm / s, printing layer thickness of about 0.2~0.3mm, printing thickness of about 0.6~0.8mm, printing width of a single uniform magnetic responsive hydrophobic layer of about 1mm~3mm, and the width of the interval between two adjacent uniform magnetic responsive hydrophobic layers of 50~300μm; after printing, heat curing treatment at 80~95℃ for 2h~4h.

[0015] Preferably, the printing parameter ranges of materials B and 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. Both materials are post-processed by light curing.

[0016] Preferably, the method further includes S3: processing the surface micro-nano structure of the surface prepared above by using a laser etching method.

[0017] Preferably, the surface micro-nanostructure morphology includes but is not limited to a lotus leaf papilla-like structure, a cactus thorn-like cone-shaped structure, a pitcher plant pitcher plant-like duck tongue-shaped structure, and the like.

[0018] 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.

[0019] The beneficial effects of the present invention include:

[0020] The presence of anisotropic structures can effectively control the morphology of droplets and facilitate the directional transport of droplets;

[0021] Under different excitation conditions, water droplets will show different shapes on the smart wetting surface, thereby exacerbating

[0022] The directional movement of droplets, the application of a magnetic field can make the surface change to a hydrophobic direction, which is conducive to the transfer of droplets; increasing the temperature can make the thermosensitive material shrink and drain water, making the surface change to a hydrophobic direction. Due to the gradient distribution of the thermosensitive material, the hydrophobicity also presents a gradient feature, which enables the droplets to transfer to the side with relatively weaker hydrophobicity.

[0023] By utilizing gradient 3D printing technology and heterogeneous material composition systems, smart surfaces with material and structural gradients are prepared. These surfaces produce morphological and wettability changes in response to different stimuli. Through the synergistic effect of the dual material-structure gradient and multiple stimuli, directional movement of droplets is achieved.

[0024] The present invention mixes and distributes magnetically responsive particles and thermosensitive hydrogel materials with two elastomeric materials with different wettability properties. First, the two materials are arranged in a staggered line using an extrusion gradient 3D printing manufacturing method. The magnetically responsive particles are evenly distributed in the two materials, and the thermosensitive material is distributed in a gradient pattern in the extrusion lines of one of the materials. Subsequently, a laser etching method is combined to realize the manufacture of surface micro-nano bionic structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the embodiments.

[0026] Figure 1 Schematic diagram of the distribution of uniform magnetically responsive hydrophobic layer and temperature-responsive non-uniform hydrophilic layer;

[0027] Figure 2 Schematic diagram of the overall wetting performance transformation under temperature excitation conditions of the present invention;

[0028] Figure 3 Schematic diagram of the wettability change and droplet transfer caused by temperature excitation along the material gradient direction of the present invention. DETAILED DESCRIPTION

[0029] The present invention provides a design and preparation method for anisotropic and wettability gradient smart surfaces with multi-stimulus responses. To clarify and clarify the technical solutions and effects of the present invention, the present invention is further described below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0030] According to the material composition of the designed smart surface, three material systems need to be prepared for printing. 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, and nanoclay lithium magnesium silicate, and is hydrophilic.

[0031] The preparation method of the bionic intelligent wetting surface with anisotropy and multi-excitation includes the following steps: Step 1: Preparation of the material system, according to the material composition of the designed intelligent surface, three kinds of

[0032] The material system used for printing;

[0033] 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;

[0034] Material B: Acrylamide (PAM) is mixed with 1 wt.% to 5 wt.% of a photoinitiator to form an acrylamide mixture. Subsequently, 8 wt.% to 92 wt.% of the acrylamide mixture is mixed with Co powder to form an acrylamide mixture with magnetic responsive particles. 5 wt.% to 30 wt.% of nanoclay lithium magnesium silicate is mixed with the acrylamide mixture with magnetic responsive particles to improve printability.

[0035] Material C: N-isopropylacrylamide (NIPAM) and a photoinitiator are prepared at a ratio of 1 wt.% to 5 wt.% to form an N-isopropylacrylamide mixture. 8 wt.% to 92 wt.% of acrylamide is mixed with Co powder to form an acrylamide mixture with magnetically responsive particles. The N-isopropylacrylamide mixture and the acrylamide mixture with magnetically responsive particles are mixed and nanoclay lithium magnesium silicate is added at a total weight ratio of 5 wt.% to 30 wt.% to improve printability.

[0036] After being stirred evenly using a magnetic stirrer, the materials are loaded into the printing syringe and mixed using a planetary stirrer for the next step of printing.

[0037] Step 2. Design and preparation of gradient material surface:

[0038] 1) Using a single-material extrusion 3D printing method, deposit material A on Figure 1 The strips shown in Figure 1 are labeled as uniform magnetically responsive hydrophobic layers. The printing speed is 1-10 mm / s, the layer thickness is approximately 0.2-0.3 mm, the thickness is approximately 0.6-0.8 mm, the width is approximately 1-3 mm, and the strip spacing is approximately 50-300 μm. After printing, the film is thermally cured at 95°C for 2 hours.

[0039] 2) Using gradient material extrusion 3D printing method, material B and material C are distributed in a gradient pattern. Figure 1 The interval strip region 2 shown is recorded as a temperature-responsive non-uniform hydrophilic layer. The ratio of material B to material C is linearly gradient 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 range of the two materials is: printing speed 5-20mm / s, printing layer thickness 0.2-0.4mm, printing thickness 0.6-0.8mm, and printing width 1mm-3mm. Both materials are post-processed by light curing.

[0040] Step 3. Using laser processing technology, the prepared surface is roughened to create structures resembling lotus leaf papillae, cactus thorn cones, and the duckbill-like structure of the pitcher plant's mouth, referencing biological surface morphology and structural characteristics. The surface is then cleaned with anhydrous ethanol and deionized water. Surface wettability is tested using a contact angle meter.

[0041] The designed smart wetting surface has the wetting state changes under multiple excitation conditions, the effect is as follows Figure 3 As shown, specifically:

[0042] In the initial state, since regions 1 and 2 are divided into hydrophobic and hydrophilic states, the droplet will tend to the hydrophilic side, which is state 1.

[0043] When the anisotropic surface is stimulated by a magnetic field, the effect of the magnetic Fe3O4 particles causes the surface to become rougher overall, and region 1 transforms toward superhydrophobicity, transitioning to state 2.

[0044] When the anisotropic surface is subjected to temperature stimulation, the overall wettability of region 2 changes from a hydrophilic state to a hydrophobic state due to the shrinkage and drainage function of PNIPAM 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. 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.

[0045] When the anisotropic surface is simultaneously subjected to the dual excitation of magnetic field and temperature, 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, and then changes to state 4.

Claims

1. A method for preparing a biomimetic intelligent wetting surface with anisotropy and multi-stimulation, characterized by: 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 1 wt.% to 5 wt.% of a photoinitiator to form an acrylamide mixture, and then 8 wt.% to 92 wt.% of the acrylamide mixture is mixed with magnetically responsive particles to form an acrylamide mixture with magnetically responsive particles. 5 wt.% to 30 wt.% of a thickener is mixed with the acrylamide mixture with magnetically responsive particles to form a hydrophilic material. Material C: N-isopropylacrylamide and a photoinitiator are prepared in a ratio of 1 wt.% to 5 wt.% to form an N-isopropylacrylamide mixture. 8 wt.% to 92 wt.% of acrylamide is mixed with magnetically responsive nanoparticles to form an acrylamide mixture with magnetically responsive particles. The N-isopropylacrylamide mixture and the acrylamide mixture with magnetically responsive particles are mixed and a thickener accounting for 5 wt.% to 30 wt.% of the total weight is added to form a hydrophilic material. Step 2: Gradient surface preparation: S1: Using a single-material extrusion 3D printing method, material A is deposited on the substrate to form multiple uniform magnetically responsive hydrophobic layers with intervals. S2: Using a gradient material extrusion 3D printing method, materials B and C are distributed 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 to material C is distributed in a gradient pattern, where the ratio changes from 90% material B:10% material C to 10% material B:90% material C. Post-processing is performed using photocuring.

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

3. The method for preparing a biomimetic intelligent wetting surface with anisotropy and multi-stimulation according to claim 1, characterized in that: The printing parameter ranges of materials B and C are: 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 light curing.

4. The method for preparing a biomimetic intelligent wetting surface with anisotropy and multi-stimulus according to claim 1, characterized in that: The method further includes S3: performing surface micro-nanostructure processing on the prepared surface by using a laser etching method.

5. The method for preparing a biomimetic intelligent wetting surface with anisotropy and multi-stimulation according to claim 4, characterized in that: The surface micro-nano structure includes a lotus leaf mastoid structure, a cactus thorn cone structure and a duck tongue structure imitating the rim of a pitcher plant.

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

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