A high-strength, self-healing phase-change bionic adhesion surface with dual switchable solid / liquid adhesion

Abstract

The present invention discloses a high-strength, self-healing solid / liquid dual-switchable adhesion phase-change bionic adhesion surface, belonging to the technical field of functional materials. This surface constructs a precise microcavity array structure on a PDMS flexible substrate through femtosecond laser technology and fills it with a phase-change material, paraffin wax, to achieve flexible switching between solid and liquid adhesion. At the same time, this surface has excellent self-healing ability and can quickly restore its adhesion performance after being damaged, thus meeting the complex and variable application requirements.

Description

Technical Field

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

[0002] Intelligent surfaces, especially those that can switch adhesion according to needs, have received extensive attention in recent years. These surfaces have shown great potential in fields such as 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 body surface structures, providing inspiration for the design of artificial intelligence surfaces. However, existing solid-liquid universal adhesion surfaces still face many challenges in performance, such as insufficient solid adhesion strength, poor liquid adhesion persistence, and weak scratch resistance. Therefore, it is particularly important to develop an intelligent surface with both high-strength solid adhesion, stable liquid adhesion, and good self-healing ability. Summary of the Invention

[0003] The present invention provides a phase change bionic adhesion surface with high strength and self-healing solid / liquid dual-switchable adhesion. This surface constructs a precise microcavity array structure on a PDMS flexible substrate through femtosecond laser technology and fills it with a phase change material, paraffin wax, to achieve flexible switching between solid and liquid adhesion. At the same time, this surface has excellent self-healing ability and can quickly recover its adhesion performance after being damaged, thus meeting the complex and changeable application requirements.

[0004] The object of the present invention can be achieved by the following technical solutions:

[0005] A phase change bionic adhesion surface with high strength and self-healing solid / liquid dual-switchable adhesion, which is formed by constructing a precise microcavity array structure on a PDMS flexible substrate through femtosecond laser technology and filling it with a phase change material, paraffin wax, and then curing.

[0006] Furthermore, the melting point of the paraffin wax is 50°C. Paraffin wax belongs to a phase change material, and its melting point distribution range is approximately 50 - 100°C. By selecting paraffin wax 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.

[0007] More specifically, it includes the following preparation steps:

[0008] (1) Construction of the microcavity array: Utilizing the high-precision and high-energy density characteristics of femtosecond laser, micro-nano processing is carried out on the PDMS flexible substrate to construct a microcavity array with specific diameter, depth, and spacing. These microcavities, as containers for storing and releasing the phase change material, play a crucial role in the adhesion performance.

[0009] (2) Filling and curing of phase change material: Heat the phase change material paraffin to the liquid state and use pressure or vacuum-assisted technology to fill it into the PDMS microcavity array. After the paraffin cools and solidifies, a stable composite structure is formed with the PDMS substrate, providing a material basis for subsequent adhesion switching.

[0010] Further, a concentric circle laser scanning path is adopted for femtosecond laser. The microcavity edges obtained by scanning in this path mode are complete and flat, which is beneficial to the realization of the adhesion switching mechanism and self-healing ability.

[0011] Further, the diameter of the microcavity is 500 μm, the depth is 480 μm, and the edge spacing is 100 μm; the filling amount of paraffin is 20 mg / cm 2 . By precisely controlling the geometric parameters of the microcavity and the filling amount of paraffin, high-strength adhesion to solids can be achieved, and the adhesion strength can reach 142 kPa, meeting the requirements of various application scenarios.

[0012] It should be noted in detail that the above surface has a flexible switching mechanism and self-healing ability for solid and liquid adhesion, specifically:

[0013] 1) Adhesion switching mechanism: Locally heat the adhesion surface through the electrothermal sheet to melt the paraffin in the microcavity, thereby changing the adhesion characteristics 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, realizing stable adhesion and release of the liquid.

[0014] 2) Realization of self-healing ability: When the adhesion surface is damaged by scratches or the like, heat it again to melt the paraffin and fill the damaged area, and then cool and solidify to achieve self-healing. This process not only restores the integrity of the surface but also retains the original adhesion performance.

[0015] The beneficial effects of the present invention:

[0016] (1) High-strength solid adhesion: By precisely controlling the geometric parameters of the microcavity and the filling amount of paraffin, the present invention achieves high-strength adhesion to solids, and the adhesion strength can reach 142 kPa, meeting the requirements of various application scenarios.

[0017] (2) Stable liquid adhesion: At room temperature, a stable low-adhesion interface is formed between the solid paraffin and the liquid, realizing reliable adhesion and release of the liquid. At the same time, after repeated use for many times, the liquid adhesion performance can still remain stable.

[0018] (3) Excellent self-healing ability: Utilizing the phase change characteristics of paraffin, the present invention realizes rapid self-healing of scratches and other damages on the adhesion surface, extending the service life of the surface.

[0019] (4) Wide 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. Description of the Drawings

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] Figure 1 is the overall manufacturing flow chart of the present invention;

[0022] Figure 2 is a schematic diagram of the self-healing process of the present invention;

[0023] Figure 3 is the adhesion strength of adhering different objects in Example 2;

[0024] Figure 4 is the contact angle and rolling angle of the droplet within 20 cycles in Example 3;

[0025] Figure 5 is the influence of different pore sizes and paraffin perfusion amounts on the adhesion strength;

[0026] Figure 6 is the influence of different pre-tightening forces on the adhesion strength;

[0027] Figure 7 is the SEM micrograph of the micropores obtained by using different laser scanning paths. Detailed Embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1

[0030] A high-strength, self-healing solid / liquid dual-switchable adhesion phase-change bionic adhesion surface, comprising the following preparation steps:

[0031] (1) Construction of the microcavity array: Utilize the high-precision and high-energy density characteristics of femtosecond laser to perform micro-nano processing on the PDMS flexible substrate to construct a microcavity array with specific diameter, depth and spacing;

[0032] (2) Infusion and curing of phase change material: Heat the phase change material paraffin to the liquid state and use pressure or vacuum-assisted technology to infuse it into the PDMS microcavity array. After the paraffin cools and solidifies, a stable composite structure is formed with the PDMS substrate.

[0033] Figure 1 It details the whole process from the preparation of the PDMS substrate, femtosecond laser micro-nano processing, infusion and curing of the phase change material to the formation of the final product.

[0034] Figure 2 It shows the whole process of self-healing of the bionic adhesion surface after being scratched and damaged through the heating-cooling process and the surface morphology after healing.

[0035] Example Two

[0036] To demonstrate the potential of the present invention in practical applications, the bionic adhesion surface is applied to the grasping system of an intelligent robot. The bionic adhesion surface is used as the grasping finger of the robot, and by controlling the electrothermal sheet to heat and cool the surface, the switching between solid and liquid adhesion is realized. In the experiment, the robot successfully grasped and released various objects with different materials and shapes, including metal blocks, plastic bottles, and glass cups, etc. At the same time, during the grasping process, the bionic adhesion surface showed good flexibility and self-adaptability, and could closely adhere to the object surface and maintain a stable grasping force. As Figure 3 shown are the adhesion strengths to different objects (glass, plastic, iron, paper, and dimethyl silicone). This application example fully demonstrates the application prospects and potential of the present invention in the field of intelligent robots.

[0037] Example Three

[0038] The performance changes of the bionic adhesion surface after multiple liquid adhesion and release cycles were observed. By repeatedly adhering and releasing water droplets to the surface, the interfacial contact angle and rolling angle after each cycle were recorded. The results show (in figures (a) and (b) in Figure 4 respectively) that even after multiple cycles, the liquid adhesion performance of the bionic adhesion surface still remains stable and there is no obvious performance decline.

[0039] Example Four

[0040] To further optimize the performance of the bionic adhesion surface, the parameters of the microcavity array were adjusted. Microcavities with diameters of 100μm, 200μm, 300μm, 400μm, 450μm, 500μm, and 550μm were respectively prepared, and different amounts (0, 4mg / cm 2 , 8mg / cm 2 , 12mg / cm 2 , 16mg / cm 2 , and 20mg / cm2 Paraffin wax as described in Figure 5 As shown, the solid adhesion strength and liquid adhesion performance of the bionic adhesion surface under different parameters were tested and compared (where Figure (a) shows the relationship between the microcavity diameter and the adhesion strength, and Figure (b) shows the relationship between the paraffin perfusion amount and the adhesion strength).

[0041] Example Five

[0042] In this example, we focused on studying the influence of solid pre-tightening force on the adhesion performance of the bionic adhesion surface. Solid pre-tightening force refers to the pre-pressure applied to the adhesion surface through external pressure or mechanical devices during the adhesion process to enhance the contact and adhesion strength between it and the solid surface.

[0043] Different magnitudes of solid pre-tightening force were applied to the bionic adhesion surface using a pressure sensor, and then its adhesion strength was measured. The test results show that the solid pre-tightening force has a significant influence on the adhesion performance of the bionic adhesion surface. Within a certain range, as the solid pre-tightening force increases, the adhesion strength of the bionic adhesion surface also gradually increases. This is because the pre-tightening force can prompt the bionic adhesion surface to fit more closely to the solid surface, increasing the contact area and the number of contact points, thereby improving the adhesion force. However, when the solid pre-tightening force exceeds a certain threshold, the increasing trend of the adhesion strength gradually slows down and may even decrease (as Figure 6 shown, the adhesion strengths under pre-tightening forces of 50 kPa, 100 kPa, 150 kPa, 200 kPa, 250 kPa, 300 kPa, and 350 kPa were tested respectively). This is because excessive pre-tightening force may cause deformation or damage to the bionic adhesion surface, destroying its microcavity structure and the distribution of the phase change material, thereby reducing the adhesion performance. Therefore, in practical applications, it is necessary to reasonably control the magnitude of the solid pre-tightening force according to specific usage scenarios and requirements to obtain the best adhesion effect.

[0044] Example Six

[0045] Micro-nano processing was carried out on a PDMS flexible substrate using two methods: concentric circle laser scanning path and unidirectional scanning path respectively, and the formed microcavity structure was observed. As Figure 7 shown, i is the concentric circle laser scanning path, and ii and iii are unidirectional scanning paths. It can be seen from the following SEM images that the edge of the microcavity structure obtained by the concentric circle laser scanning path is complete and flat.

[0046] The above specific implementation manners have specifically introduced the analysis 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 idea of the present invention, rather than a limitation on the relevant content. Without departing from the principle of the present invention, those skilled in the art can also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications should also fall within the protection scope 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 microcavity has a diameter of 500 μm, a depth of 480 μm, and an edge spacing of 100 μm; Femtosecond laser was performed using a concentric circle laser scanning path; 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 2, characterized in that: The method of injecting the phase change material in step (2) is to use pressure or vacuum assisted technology.

5. 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.

6. 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.

7. The high-strength, self-healing solid / liquid dual switchable adhesion phase change bionic adhesion surface according to claim 5, characterized in that: The range of applied pre-pressure is 250-350 kPa.

8. 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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