Bridged columnar array structure for biomimetic structural adhesive and preparation method thereof

Abstract

The present application discloses a bridged columnar array structure for bionic adhesives and a preparation method. In the present technical solution, the bridge is connected between adjacent columns containing a support layer, and the direction of the bridge is arranged according to a certain rule. The existence of this structure improves the strength of the column, reduces stress concentration at the contact interface, and makes the column resistant to lodging. When subjected to lateral friction, it is more conducive to maintaining the stability of the column, reducing the degree of bending of the column, and improving the adhesion and friction of the column. More importantly, by selecting a directional connection, the anisotropic friction performance of the bionic structure adhesive can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of bionic adhesives, and in particular to a bridged columnar array structure and a preparation method for bionic structural adhesives. Background Art

[0002] Adhesion is indispensable in production and life, and reversible adhesion is widely used in daily life, health, industry, national defense and military industries. Many animals in nature, such as geckos and spiders, can crawl on various surfaces, and the adhesion generated by their soles plays a vital role. The adhesion of these organisms mainly depends on the structure of their soles rather than the chemical properties, so this type of adhesion is called structural adhesion. Structure has a wide range of application prospects in human society. For example: in aerospace, it can provide on-orbit maintenance and life extension services for spacecraft, capture or dock non-cooperative targets, and can also be used for space debris disposal; in the field of chip manufacturing, reversible adhesion can achieve non-destructive and pollution-free transfer of semiconductor components; in health, reversible adhesive materials can be used to tightly adhere sensors to the skin surface to monitor human health, while ensuring breathability and easy peeling from the skin surface to relieve pain. There are even huge application prospects in robotics, national defense, military and other fields.

[0003] High adhesion and high friction are prerequisites for organisms to obtain strong adhesion capabilities, so a biomimetic adhesive pad with direction-dependent friction was developed by imitating gecko bristles. The design of the tilted micropillar array structure to produce directional friction significantly reduces the effective modulus of the surface, thereby improving structural compliance and better interface integrity when in contact with the substrate. For example, the tilted and gradient fiber arrays fabricated by Professor Wang Zhengzhi of Wuhan University showed about 700% shear force in the tilted direction compared with the opposite direction, but poor adhesion in the normal direction. Directional friction depends not only on the tilted micropillars, but also on the asymmetric geometry of the ends on the vertical pillars. Micropillars with triangular geometry exhibit different shear forces in relative directions. Micropillars with asymmetric spade-shaped terminals also provide anisotropic shear forces determined by the overhang position, where the force sliding along the overhang is higher than that sliding in the reverse direction. The anisotropic friction in the above cases is mainly based on the difference in friction forces in relative directions due to the tilted pillars or the asymmetry of the pillar ends. Therefore, it is still challenging to design a vertically arranged bionic array with a symmetrical end structure and to realize a bionic columnar array with high adhesion, high friction and programmable friction direction. Summary of the invention

[0004] In view of this, the present application provides a bridged columnar array structure and a preparation method for a bionic structural adhesive, which can improve adhesion and friction performance.

[0005] In a first aspect, the present application provides a bridged columnar array structure for a bionic structural adhesive, comprising a support layer on which a plurality of columns arranged in an array are stacked, adjacent columns are connected by bridges, and extension directions of the bridges are regularly distributed.

[0006] Optionally, the shape of the bridge is one or a combination of a cuboid, a spindle, a candied haws-shaped body, a smooth cylinder, a cylinder containing a porous structure, a tubular cylinder with a hollow interior, a cylinder with a porous structure on the outside and a solid interior; the material of the bridge is any one or a combination of rubber, gel, carbon, silicon, cellulose, resin, metal, and ceramic.

[0007] Optionally, the height of the bridge is smaller than the height of the column, the bridge is connected to the supporting layer by any one of a suspended connection, a single-bridge connection, and a multi-bridge connection or a combination thereof, and the width of the bridge is smaller than the diameter of the column.

[0008] Optionally, the pillars are selectively connected, connected in a single direction, connected in all directions, or locally connected, or a combination of several of the functions.

[0009] Optionally, the material of the column is any one or a combination of natural rubber, artificial rubber, polyurethane, polyimide, polyolefin, polylactic acid, polycaprolactone, hydrogel, aerogel, and oil gel.

[0010] Optionally, the support layer is a solid structure or a porous structure or a combination of the two, and the pillars, bridges and support layer are processed at one time or processed separately and then bonded together.

[0011] Optionally, the material of the pillar, the material of the bridge, and the material of the support layer are the same or different, and the modulus of the materials are the same or different; when the materials are different, the interfaces are firmly bonded.

[0012] Optionally, the end of the column structure is one or a combination of circular, polygonal, irregular polygonal, spatula-shaped, mushroom-shaped or pit-shaped.

[0013] In a second aspect, the present application provides a method for preparing the above-mentioned bridged columnar array structure, comprising the following steps:

[0014] Step 1: pouring the prepared material into a structured array pit template to form it, and peeling the solidified array from the template to obtain an unbridged columnar bionic structure adhesive;

[0015] Step 2: Spin-coat the material solution for preparing the bridge onto the adhesive obtained in step 1, control the number of bridges by solution concentration and rotation speed, control the orientation direction of the bridge by stretching, and obtain a bridged columnar bionic structure adhesive after inverted curing.

[0016] The bridge columnar array structure and preparation method for biomimetic structural adhesive provided above, the bridge structure for biomimetic structural adhesive, the connection between adjacent columns can improve the strength of the column, reduce the stress concentration at the contact interface, and make the column resistant to lodging. More importantly, by selecting directional connection, the anisotropic friction performance of the biomimetic structural adhesive can be achieved. In particular, for the column array with a high aspect ratio, the degree of column bending will be reduced when subjected to friction, which is beneficial to improve adhesion and friction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0018] Figure 1 It is a schematic diagram of the overall structure of Example 1 of the present invention.

[0019] Figure 2 This is a SEM image of the overall structure of Example 1 of the present invention.

[0020] Figure 3 This is a cross-sectional SEM image of a single bridge body in Example 1 of the present invention.

[0021] Figure 4 It is a schematic diagram of the front and side surfaces of the overall structure of Example 2 of the present invention.

[0022] Figure 5 It is a schematic top view of the overall structure of Example 3 of the present invention.

[0023] The components in the figure are marked as follows:

[0024] 1- bridge, 2- support layer, 3- column. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0026] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0029] A bridged columnar array structure for a bionic adhesive, characterized in that adjacent columns in a column array 3 structure containing a support layer 2 are connected by bridges 1, and the directions of the bridges 1 are arranged according to a certain rule.

[0030] A method for preparing a bridged columnar array structure for a biomimetic adhesive, characterized in that it comprises the following steps:

[0031] Step 1: pouring the prepared material into a structured array pit template to form it, and peeling the solidified array from the template to obtain an unbridged columnar bionic structure adhesive;

[0032] Step 2: Spin-coat the material solution for preparing the bridge onto the adhesive obtained in step 1, control the number of bridges by solution concentration and rotation speed, control the orientation direction of the bridge by stretching, and obtain a bridged columnar bionic structure adhesive after inverted curing.

[0033] The shape of the bridge 1 can be one or a combination of a rectangular parallelepiped, a spindle, a candied haws-shaped body, a smooth cylinder, a cylinder with a porous structure, a tubular cylinder with a hollow interior, a cylinder with a porous structure on the outside and a solid interior; the material can be any one or a combination of rubber, gel, carbon, silicon, cellulose, resin, metal, and ceramic.

[0034] The height of the bridge 1 is less than that of the column 3, and the bridge is connected to the support layer 2 or is suspended, connected by a single bridge or multiple bridges, or any one or a combination of the above connection methods; the width of the bridge 1 is less than the diameter of the column.

[0035] The bridge 1 dynamically changes its own modulus and the magnitude of the interaction force with the pillar 3 material under the action of one or more stimuli such as light, heat, magnetism, electricity, and solvent.

[0036] The bridge 1 can be selectively connected in the columns 3 of the array, and can be connected in a single direction, in all directions, or in a partial connection, or in any combination of several functions.

[0037] The column 3 structure and the column body 3 material can be any one or a combination of natural rubber, artificial rubber, polyurethane, polyimide, polyolefin, polylactic acid, polycaprolactone, hydrogel, aerogel, and oil gel.

[0038] The support layer 2 can be a solid structure or a porous structure or a combination of the two. The pillars 3, the bridge 1 and the support layer 3 can be processed at one time or processed separately and then bonded together.

[0039] The materials of the pillar 2, bridge 1 and support layer 2 can be the same or different, and the moduli of the materials can be the same or different; when the materials are different, the interfaces are firmly bonded.

[0040] The pillar 3 structure, the pillar 3, the bridge 1, and the supporting layer 2 can be processed at one time or processed separately and then bonded together.

[0041] The ends of the pillar 3 structures can be designed to be circular, polygonal, irregular polygonal, spatula-shaped, mushroom-shaped or pit-shaped, or a combination of several of them.

[0042] The following are three specific embodiments:

[0043] Embodiment 1:

[0044] like Figure 1 Figure 2 and Figure 3 In the bionic structural adhesive shown, bridge 1 is selectively connected in the column 3 array containing support layer 2. Bridge 1 is connected in a single direction in the column array, with a width of 15 microns and a height of 25 microns. It is made of silicone rubber. The bridge, column and support layer are firmly connected, and the modulus of the bridge, column and support layer is the same. Support layer 2 is a solid structure that is aligned vertically and horizontally and is made of silicone rubber. Column 3 is made of silicone rubber, with a circular cross-sectional shape, a diameter of 50 microns and a height of 50 microns. The column array is squarely stacked with a spacing of 10 microns.

[0045] Adhesion and friction tests were performed using a homemade adhesion test device under a load of 1 mN using a ruby ​​with a diameter of 5 mm as a contact probe.

[0046] like Figure 4 As shown, the columnar bionic structure adhesive with single-direction bridging has adhesion force of 0.8 mN, friction force in the direction perpendicular to the bridge is 1.0 mN, and friction force in the direction parallel to the bridge is 1.8 mN.

[0047] Columnar biomimetic structure adhesive without bridging: adhesion 0.5 mN, friction 0.8 mN.

[0048] The adhesion and friction of the columnar bionic structure adhesive with a single-direction bridge are significantly greater than those of the columnar bionic structure adhesive without a bridge, and the friction in the direction parallel to the bridge is significantly higher than the friction in the direction perpendicular to the bridge. The bridge connection improves the strength of the column, making it less likely to bend, reduces the direct adhesion of the column and the collapse of the column, reduces stress concentration, and is conducive to the improvement of friction and adhesion performance. At the same time, due to the single-direction bridge connection, the bending degree of the column in the parallel and perpendicular directions to the bridge is different, showing anisotropy in friction performance. Therefore, this structure has far-reaching significance in adhesion theory and bionic applications.

[0049] Embodiment 2:

[0050] like Figure 5 In the bionic structural adhesive shown, bridge 1 is selectively connected in the column 3 array containing the support layer 2. Bridge 1 is suspended in a single direction in the column array, with a width of 15 microns and a height of 12.5 microns. It is made of silicone rubber. The bridge, column and support layer are firmly connected. The column and support layer have the same modulus, and the modulus of the bridge is twice the modulus of the column and support layer. Support layer 2 is a solid structure that is neatly arranged vertically and horizontally, and is made of silicone rubber. The column 3 is made of silicone rubber, with a circular cross-sectional shape, a diameter of 50 microns, and a height of 50 microns. The column array is squarely stacked with a spacing of 10 microns.

[0051] Adhesion and friction tests were performed using a homemade adhesion test device under a load of 1 mN using a ruby ​​with a diameter of 5 mm as a contact probe.

[0052] Columnar bionic structure adhesive with single-direction bridging: Adhesion 1.0 mN, Friction 1.5 mN in the perpendicular bridge direction, Friction 2.4 mN in the parallel bridge direction,

[0053] Columnar biomimetic structure adhesive without bridging: adhesion 0.5 mN, friction 0.8 mN.

[0054] The adhesion and friction of the columnar bionic structure adhesive with a single-direction bridge are significantly greater than those of the columnar bionic structure adhesive without a bridge, and the friction in the direction parallel to the bridge is significantly higher than the friction in the direction perpendicular to the bridge. The bridge connection improves the strength of the column, making it less likely to bend, reduces the direct adhesion of the column and the collapse of the column, reduces stress concentration, and is conducive to the improvement of friction and adhesion performance. At the same time, due to the single-direction bridge, the degree of bending of the column in the direction parallel and perpendicular to the bridge is different, showing anisotropy in friction performance. Therefore, this structure has far-reaching significance in adhesion theory and bionic applications.

[0055] Embodiment 3:

[0056] like Figure 5 In the bionic structural adhesive shown, bridge 1 is selectively connected in the column 3 array containing support layer 2. Bridge 1 is regionally locally oriented in the column array, with a width of 15 microns and a height of 25 microns. It is made of silicone rubber. The bridge, column and support layer are firmly connected, and the modulus of the bridge, column and support layer is the same. Support layer 2 is a solid structure that is aligned vertically and horizontally and is made of silicone rubber. Column 3 is made of silicone rubber, with a circular cross-sectional shape, a diameter of 50 microns and a height of 50 microns. The column array is squarely stacked with a spacing of 10 microns.

[0057] Adhesion and friction tests were performed using a homemade adhesion test device under a load of 1 mN using a ruby ​​with a diameter of 5 mm as a contact probe.

[0058] Columnar bionic structural adhesive with regional local bridging: Adhesion 0.8 mN, friction in the direction perpendicular to the bridge 1.0 mN, friction in the direction parallel to the bridge 1.8 mN,

[0059] Columnar biomimetic structure adhesive without bridging: adhesion 0.5 mN, friction 0.8 mN.

[0060] The adhesion and friction of the columnar bionic structure adhesive with regional local bridging are significantly greater than those of the columnar bionic structure adhesive without bridging, and the friction in the direction parallel to the bridge is significantly higher than the friction in the direction perpendicular to the bridge. The bridge connection improves the strength of the column, making it less likely to bend, reduces the direct adhesion of the column and the collapse of the column, reduces stress concentration, and is conducive to the improvement of friction and adhesion performance. At the same time, due to the bridging in a single direction, the bending degree of the column in the direction parallel and perpendicular to the bridge is different, showing anisotropy in friction performance. Therefore, this structure has far-reaching significance in adhesion theory and bionic applications.

[0061] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing a bridged columnar array structure for a biomimetic structural adhesive, characterized in that: The bridged columnar array structure comprises a support layer, on which a plurality of columns arranged in an array are stacked, adjacent columns are connected by a bridge in a single direction, the bridge is connected to the support layer as a single bridge, the extension direction of the bridge is regularly distributed, the width of the bridge is smaller than the diameter of the column, the height of the bridge is smaller than the height of the column, and the material of the column, the material of the bridge, and the material of the support layer are the same; The preparation method of the bridged columnar array structure comprises: Step 1: pouring the prepared material into a structured array pit template to form the structured array, peeling the solidified array from the template to obtain an unbridged columnar bionic structure adhesive; Step 2: Spin-coat the material solution for preparing the bridge onto the unbridged columnar bionic structure adhesive obtained in step 1, control the number of bridges by solution concentration and rotation speed, control the orientation direction of the bridge by stretching, form a single-direction bridge, and obtain a bridged columnar bionic structure adhesive after inverted curing.

2. The method for preparing a bridged columnar array structure for a biomimetic structural adhesive according to claim 1, characterized in that: In the bridge columnar array structure, the shape of the bridge is one or a combination of a rectangular parallelepiped, a spindle, a candied haws-shaped body, a smooth column, a column with a porous structure, a tubular column with a hollow interior, a column with a porous structure on the outside and a solid interior; the material of the bridge is any one or a combination of rubber, gel, and resin.

3. The method for preparing a bridged columnar array structure for a biomimetic structural adhesive according to claim 1, characterized in that: In the bridged columnar array structure, the material of the columns is any one or a combination of natural rubber, artificial rubber, polyurethane, polyimide, polyolefin, polylactic acid, polycaprolactone, hydrogel, aerogel, and oil gel.

4. The method for preparing a bridged columnar array structure for a biomimetic structural adhesive according to claim 1, characterized in that: In the bridged columnar array structure, the support layer is a solid structure or a porous structure or a combination of the two, and the columns, bridges, and support layers are processed at one time or processed separately and then bonded together.

5. The method for preparing a bridged columnar array structure for a biomimetic structural adhesive according to claim 1, characterized in that: In the bridge columnar array structure, the ends of the column structures are in the shape of a circle, a polygon, an irregular polygon, a spatula, a mushroom or a pit, or a combination of the shapes.

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