High-strength and self-healing type solid / liquid dual switchable adhesion phase change bionic adhesion surface

Abstract

The invention discloses a high-strength and self-healing type solid / liquid dual switchable adhesion phase change bionic adhesion surface, and belongs to the technical field of functional materials. According to the surface, a precise microcavity array structure is constructed on a PDMS flexible substrate through a femtosecond laser technology, and a phase change material paraffin is injected, so that flexible switching between solid adhesion and liquid adhesion is realized. Meanwhile, the surface has excellent self-healing capability, and the adhesion performance can be quickly recovered after the surface is damaged, so that the complex and variable application requirements are met.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials, and in particular relates to a high-strength, self-healing solid / liquid dual switchable adhesion phase-change bionic adhesion surface. Background Art

[0002] Smart surfaces, especially those that can switch adhesion according to demand, have received widespread attention in recent years. These surfaces have shown great potential in the fields of robotic grasping, soft grippers, microfluidic control, and biological detection. In nature, many organisms such as octopuses, geckos, and tree frogs achieve switchable adhesion to solids and liquids through their unique surface structures, providing inspiration for the design of artificial intelligence surfaces. However, the existing solid-liquid universal adhesion surfaces still have many challenges in performance, such as insufficient solid adhesion strength, poor liquid adhesion durability, and weak scratch resistance. Therefore, it is particularly important to develop a smart surface that has both high-strength solid adhesion, stable liquid adhesion, and good self-healing ability. Summary of the invention

[0003] The present invention provides a high-strength, self-healing solid / liquid dual switchable phase-change bionic adhesion surface, which uses femtosecond laser technology to construct a precise microcavity array structure on a PDMS flexible substrate and injects phase-change material paraffin to achieve flexible switching of solid and liquid adhesion. At the same time, the surface has excellent self-healing ability and can quickly restore adhesion performance after being damaged, thereby meeting complex and changing application requirements.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A high-strength, self-healing solid / liquid dual switchable adhesion phase-change bionic adhesion surface, which is constructed by femtosecond laser technology on a PDMS flexible substrate with a precise microcavity array structure, and then filled with phase-change material paraffin and solidified.

[0005] Furthermore, the melting point of the paraffin is 50° C. Paraffin is a phase change material with a melting point distribution range of about 50-100° C. By selecting paraffin with a melting point of 50° C., which is slightly higher than room temperature, it can help to quickly realize the adhesion switching mechanism and self-healing ability.

[0006] More specifically, the method comprises the following preparation steps: (1) Construction of microcavity arrays: Using the high precision and high energy density characteristics of femtosecond lasers, micro-nano processing is performed on the PDMS flexible substrate to construct microcavity arrays with specific diameters, depths, and spacing. These microcavities serve as containers for storing and releasing phase change materials, and play a vital role in adhesion performance.

[0007] (2) Injection and curing of phase change material: Heat the phase change material paraffin to liquid state and inject it into the PDMS microcavity array using pressure or vacuum assisted technology. After the paraffin cools and solidifies, it forms a stable composite structure with the PDMS substrate, providing a material basis for subsequent adhesion switching.

[0008] Furthermore, a concentric circle laser scanning path is used during femtosecond laser scanning. The microcavity edge obtained by scanning in this way is complete and smooth, which is beneficial to the realization of adhesion switching mechanism and self-healing ability.

[0009] Furthermore, the diameter of the microcavity is 500 μm, the depth is 480 μm, the edge spacing is 100 μm, and the amount of paraffin injected is 20 mg / cm 2 By precisely controlling the geometric parameters of the microcavity and the amount of paraffin wax injected, high-strength adhesion to solids can be achieved, with an adhesion strength of up to 142kPa, meeting the needs of a variety of application scenarios.

[0010] It should be explained in detail that the above surface has a flexible switching mechanism of solid and liquid adhesion and self-healing ability, specifically: 1) Adhesion switching mechanism: The adhesive surface is locally heated by the electric heater to melt the paraffin in the microcavity, thereby changing the adhesion properties of the surface. In the solid adhesion mode, the melted paraffin can fill the gap between the microcavity and the solid surface, forming a tight adhesion connection; while in the liquid adhesion mode, a low-adhesion interface is formed between the solid paraffin at room temperature and the liquid, achieving stable adhesion and release of the liquid.

[0011] 2) Realization of self-healing ability: When the adhesive surface is damaged by scratches, the paraffin is melted and fills the damaged area by heating again, and then cooled and solidified to achieve self-healing. This process not only restores the integrity of the surface, but also retains the original adhesion performance.

[0012] Beneficial effects of the present invention: (1) High-strength solid adhesion: By precisely controlling the geometric parameters of the microcavity and the amount of paraffin injected, the present invention achieves high-strength adhesion to solids. The adhesion strength can reach 142 kPa, meeting the needs of various application scenarios.

[0013] (2) Stable liquid adhesion: At room temperature, a stable low-adhesion interface is formed between solid paraffin and liquid, achieving reliable adhesion and release of the liquid. At the same time, the liquid adhesion performance can remain stable after repeated use.

[0014] (3) Excellent self-healing ability: By utilizing the phase change characteristics of paraffin wax, the present invention achieves rapid self-healing of scratches and other damages on the adhesion surface, thereby extending the service life of the surface.

[0015] (4) Broad application prospects: The bionic adhesion surface provided by the present invention has broad application potential in the fields of intelligent robots, wearable devices, biomedical engineering, etc., and can promote the rapid development of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings.

[0017] Figure 1 It is the overall manufacturing flow chart of the present invention; Figure 2 is a schematic diagram of the self-healing process of the present invention; Figure 3 is the adhesion strength of different objects in Example 2; Figure 4 are the contact angle and rolling angle of the droplet within 20 cycles in Example 3; Figure 5 The effect of different pore sizes and the amount of paraffin injected on the adhesion strength; Figure 6 The effect of different preload forces on adhesion strength; Figure 7 SEM images of micropores obtained using different laser scanning paths. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Embodiment 1

[0020] A high-strength, self-healing solid / liquid dual switchable adhesion phase-change bionic adhesion surface, comprising the following preparation steps: (1) Construction of microcavity arrays: Using the high precision and high energy density characteristics of femtosecond lasers, micro-nano processing is performed on a PDMS flexible substrate to construct a microcavity array with a specific diameter, depth, and spacing; (2) Injection and curing of phase change material: Heat the phase change material paraffin to liquid state and inject it into the PDMS microcavity array using pressure or vacuum assisted technology. After the paraffin cools and solidifies, it forms a stable composite structure with the PDMS substrate.

[0021] Figure 1 The whole process from PDMS substrate preparation, femtosecond laser micro-nano processing, phase change material infusion and curing to the final product formation is demonstrated in detail.

[0022] Figure 2 The whole process of self-healing of the bionic adhesion surface through heating-cooling process after scratch damage and the surface morphology after healing are demonstrated.

[0023] Embodiment 2

[0024] In order to demonstrate the potential of the present invention in practical applications, the bionic adhesive surface was applied to the grasping system of an intelligent robot. The bionic adhesive surface was used as the robot's grasping finger, and the surface was heated and cooled by controlling the electric heater to switch between solid and liquid adhesion. In the experiment, the robot successfully grasped and released objects of various materials and shapes, including metal blocks, plastic bottles, and glass cups. At the same time, during the grasping process, the bionic adhesive surface showed good flexibility and adaptability, and was able to fit closely to the surface of the object and maintain a stable grasping force. Figure 3 The adhesion strength of different objects (glass, plastic, iron, paper and dimethyl silicone) is shown. This application example fully demonstrates the application prospect and potential of the present invention in the field of intelligent robots.

[0025] Embodiment 3

[0026] The performance changes of the biomimetic adhesive surface after multiple cycles of liquid adhesion and release were observed. The water droplets were repeatedly attached to the surface and released, and the interfacial contact angle and rolling angle were recorded after each cycle. The results showed (respectively Figure 4 (a) and (b) in the figure), even after multiple cycles, the liquid adhesion performance of the bionic adhesion surface remains stable without obvious performance degradation.

[0027] Embodiment 4

[0028] In order to further optimize the performance of the biomimetic adhesion surface, the parameters of the microcavity array were adjusted. The diameters of the microcavities were 100 μm, 200 μm, 300 μm, 400 μm, 450 μm, 500 μm and 550 μm, and different amounts of liquid (0, 4 mg / cm 2 , 8mg / cm 2 , 12mg / cm 2 、16mg / cm 2 , and 20mg / cm 2 ) of paraffin. Figure 5 As shown, the solid adhesion strength and liquid adhesion performance of the bionic adhesion surface under different parameters were compared through testing (where (a) shows the relationship between the microcavity diameter and the adhesion strength, and (b) shows the relationship between the paraffin perfusion amount and the adhesion strength).

[0029] Embodiment 5

[0030] In this embodiment, we focus on the effect of solid preload on the adhesion performance of biomimetic adhesion surface. Solid preload refers to the preload applied to the adhesion surface by external pressure or mechanical device during the adhesion process to enhance the contact and adhesion strength between it and the solid surface.

[0031] A pressure sensor was used to apply different sizes of solid preload to the bionic adhesion surface, and then its adhesion strength was measured. The test results show that the solid preload has a significant effect on the adhesion performance of the bionic adhesion surface. Within a certain range, as the solid preload increases, the adhesion strength of the bionic adhesion surface gradually increases. This is because the preload can cause the bionic adhesion surface to fit more closely to the solid surface, increase the contact area and the number of contact points, and thus improve the adhesion. However, when the solid preload exceeds a certain threshold, the increase trend of the adhesion strength gradually slows down, and may even decrease (e.g. Figure 6 As shown in the figure, the adhesion strength under the preload of 50kPa, 100kPa, 150kPa, 200kPa, 250kPa, 300kPa, and 350kPa was tested respectively). This is because excessive preload may cause deformation or damage to the bionic adhesion surface, destroy its microcavity structure and the distribution of phase change materials, thereby reducing the adhesion performance. Therefore, in practical applications, it is necessary to reasonably control the size of the solid preload according to the specific usage scenarios and requirements to obtain the best adhesion effect.

[0032] Embodiment 6

[0033] The concentric circle laser scanning path and the unidirectional scanning path were used to perform micro-nano processing on the PDMS flexible substrate, and the formed microcavity structure was observed, such as Figure 7 As shown, i is a concentric circle laser scanning path, ii and iii are unidirectional scanning paths. It can be seen from the SEM image below that the edge of the microcavity structure obtained by the concentric circle laser scanning path is complete and smooth.

[0034] The above specific implementation method part specifically introduces the analytical method involved in the present invention. It should be noted that the above introduction is only to help those skilled in the art better understand the method and ideas of the present invention, rather than limiting the relevant content. Without departing from the principle of the present invention, those skilled in the art may also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications shall also fall within the scope of protection of the present invention.

Claims

1. A high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface, characterized in that: The surface is constructed by constructing a microcavity array structure on a PDMS flexible substrate using femtosecond laser technology, and then filled with paraffin and solidified; The working method of the phase change bionic adhesion surface is as follows: 1) Adhesion switching: by locally heating the adhesion surface, the paraffin in the microcavity melts, thereby changing the adhesion properties of the surface; 2) Self-healing: When the adhesion surface is damaged, the paraffin is melted and fills the damaged area by heating it again, and then cooled and solidified to achieve self-healing.

2. A high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 1, characterized in that: The preparation method specifically comprises the following preparation steps: (1) Construction of microcavity arrays: Using the high precision and high energy density characteristics of femtosecond lasers, micro-nano processing is performed on a PDMS flexible substrate to construct a microcavity array; (2) Injection and solidification of phase change material: Heat the paraffin wax to a liquid state and inject it into the PDMS microcavity array. After the paraffin wax cools and solidifies, it forms a stable composite structure with the PDMS substrate.

3. A high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 1 or 2, characterized in that: The melting point of the paraffin wax is 50°C.

4. A high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 1 or 2, characterized in that: The microcavity has a diameter of 500 μm, a depth of 480 μm, and an edge spacing of 100 μm.

5. A high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 2, characterized in that: In step (1), the femtosecond laser is scanned using a concentric circle laser scanning path.

6. A high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 2, characterized in that: The method of injecting the phase change material in step (2) is to use pressure or vacuum assisted technology.

7. The high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 1, characterized in that: When the adhesion is switched, a pre-pressure is applied to the adhesion surface by external pressure or mechanical means.

8. The high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 1, characterized in that: When adhesion is switched, the contact area and the number of contact points are increased to adjust the contact and adhesion strength between the solid surface and the solid surface.

9. The high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 7, characterized in that: The range of applied pre-pressure is 250-350 kPa.

10. The high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 1, characterized in that: The phase-change bionic adhesion surface is applied in the fields of intelligent robots, wearable devices, and biomedical engineering.

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