Preparation method of shape memory reversible bionic adhesion material

Abstract

The invention relates to a preparation method of a shape memory reversible bionic adhesion material, and belongs to the technical field of bionic materials. The method comprises the following steps: preparing a male die from PVC gel, and copying to obtain a PDMS female die; mixing the shape memory polymer matrix, the curing agent and the toughening copolymer to form an epoxy resin precursor; and curing in a PDMS (Polydimethylsiloxane) female die by a template method to obtain the adhesive material with the microstructure array. The material can realize reversible adhesion switching under thermal stimulation through a buckling lodging mechanism: when the material is heated to a temperature above a glass-transition temperature, the microstructure is softened, buckled and lodged, so that the contact area is increased, and strong adhesion is generated; after cooling, hardening and keeping the state; and the shape is recovered by heating again, so that low-energy-consumption desorption is realized. The process is simple and convenient, and the material has high adhesion strength, quick response, long service life and good adaptability and can be widely applied to the fields of intelligent robots, precision control, flexible electronics and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biomimetic materials, in particular to a preparation method of shape memory reversible biomimetic adhesive material. BACKGROUND

[0002] In recent years, with the rapid development of intelligent robots, flexible electronics and wearable devices, there is an increasing demand for new materials with controllable and reversible adhesive properties. Traditional adhesion methods mainly rely on chemical adhesives or physical structure adsorption. The former, such as commonly used strong glue, is often difficult to remove and cannot be reused after use. The latter, such as suction cup structure, can achieve reversible adhesion to a certain extent, but it has high requirements for surface smoothness and cleanliness, and its performance decreases significantly in rough or complex environments. For example, CN112919129A discloses a biomimetic adhesion and release device based on a pneumatic push rod structure and a polydimethylsiloxane adhesive material, which can achieve adhesion, handling and release of industrial products such as printed circuit boards. However, its structure is bulky, has poor surface adaptability, and has limited application range. Some studies have proposed reversible adhesion methods using electrostatic or magnetic principles, which can achieve on-off control through external fields, but often have poor selectivity for adhesion surfaces, slow response speed, high energy consumption, and insufficient environmental adaptability. These existing technologies have not been able to well balance the reversible adhesion material between fast response, low energy consumption and long cycle life, especially in terms of reliability and adaptability in complex environmental conditions, which still needs to be improved. SUMMARY

[0003] The purpose of the present application is to overcome the deficiencies in the background art, and to provide a preparation method of shape memory reversible biomimetic adhesive material, which can achieve fast and controllable adhesion state switching through thermal stimulation, has high adhesion strength, long cycle life and good environmental adaptability, and significantly improves the comprehensive performance and application range of reversible biomimetic adhesive material.

[0004] The present application adopts the following technical solutions: A preparation method of shape memory reversible biomimetic adhesive material, comprising the following steps: Step one, PVC base convex mold preparation: mix PVC powder, 1,2-cyclohexane dicarboxylic acid diisononyl ester and tetrahydrofuran to form a PVC gel precursor, fix a silicon template on the bottom of a culture dish, pour the PVC gel precursor and vacuum degassing, and then peel off the PVC base convex mold after heating and curing; Step two, PDMS concave mold preparation: configure PDMS precursor with PDMS base material and curing crosslinking agent at a mass ratio of 10:1, pour it on the PVC base convex mold after stirring and degassing, vacuum treatment to make the precursor fully fill the microstructure gap, and then peel off the PDMS concave mold after heating and curing; Step three, SMP material preparation: preheat the shape memory polymer matrix material to reduce the viscosity, add curing agent and toughening copolymer and stir until completely dissolved to form an epoxy resin precursor; Step four, biomimetic adhesive material preparation: after degassing the epoxy resin precursor, pour it into a PDMS concave mold, vacuum treatment to make the resin fully fill the micropores, and after stage heating and curing, cool and peel off to obtain a shape memory polymer-based biomimetic adhesive material with a microstructure array.

[0005] As a further scheme of the present application: the mass ratio of PVC powder, 1,2-cyclohexane dicarboxylic acid diisononyl ester and tetrahydrofuran in step one is 1:(0.5-1.5):(5-15), and the curing condition is 60℃ for 48 hours.

[0006] As a further scheme of the present application: the shape memory polymer matrix material in step three is bisphenol A diglycidyl ether, the curing agent is 4,4'-diaminodiphenyl methane, the toughening copolymer is poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), and the mass ratio of shape memory polymer matrix material:curing agent:toughening copolymer is 100:(10-30):(5-20).

[0007] As a further scheme of the present application: the stage heating and curing condition in step four is 100℃ for 2 hours, and then 120℃ for 4 hours.

[0008] As a further scheme of the present application: the shape memory polymer-based biomimetic adhesive material has a microstructure array on the surface, and the reversible switching of the adhesive state is realized through thermal stimulation.

[0009] As a further scheme of the present application: the unit structure of the microstructure array is any one of columnar, mushroom-shaped or wedge-shaped structure, the height is 10-200μm, the diameter is 5-50μm, and the aspect ratio is 1-10.

[0010] As a further scheme of the present application: the microstructure of the shape memory polymer-based biomimetic adhesive material buckles and collapses above the glass transition temperature, forming the maximum contact area with the contact surface; and the microstructure hardens and fixes below the glass transition temperature, realizing strong adhesion through intermolecular forces.

[0011] The present application has the advantages that: the preparation method is simple and efficient, the material structure is stable and reliable, and the adhesive state switching response is fast; in addition, the microstructure design based on the buckling and collapse mechanism and the thermal response characteristics of SMP significantly improve the reversible adhesion performance and cycle life of the material, and broaden the application range of biomimetic adhesive materials in robot grasping, precision manipulation and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1is the preparation flowchart of the embodiment of the present application.

[0013] Figure 2 is the schematic diagram of the microstructure of the SMP adhesive material prepared by the embodiment of the present application.

[0014] Figure 3 is the working principle diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0015] The present application is further described below in conjunction with the drawings of the specification, but the present application is not limited to the following embodiments.

[0016] A preparation method of a shape memory reversible bionic adhesive material, the preparation method comprising the following steps: The step one is PVC base male die preparation: as shown in the following figure: Figure 1 As shown in the following a-d figure, first, the mold of the silicon wafer, beaker, tweezers, medicine spoon and other experimental supplies for preparing the shape memory polymer adhesive material are cleaned in batches in an ultrasonic cleaner and dried in a forced air drying oven for standby use; second, 1g of PVC powder, 1g of DINCH and 15g of tetrahydrofuran are placed in a conical flask and stirred for 48h to form a PVC gel precursor, then the silicon mold (female die) is fixed on the bottom of a culture dish, an appropriate amount of PVC gel precursor is poured on top of it and vacuum degassing is performed for 10min to make the solution fully enter the micro-pores inside the silicon mold under negative pressure conditions, then it is placed in a heating box for solidification at 60℃ for 48h to make the tetrahydrofuran organic solvent gradually volatilize, as the organic solvent volatilizes, the volume of the PVC gel also shrinks, at the same time, DINCH not only has the function of plasticizing PVC but also has certain oiliness, which can reduce the bonding force between the PVC gel and the silicon mold when the volume of the PVC gel shrinks; then the solidified PVC gel is peeled off from the silicon mold, after cutting and cleaning, the PVC base male die is obtained.

[0017] The step two is PDMS female die preparation: as shown in the following e-h figure, Figure 1 First, the PDMS base material and the curing crosslinking agent are configured into a PDMS precursor in a mass ratio of 10:1, second, the PDMS precursor is stirred at 800rpm for 5min, then it is placed in a vacuum drying oven for 10min of degassing, then the PVC base male die obtained in the step one is fixed in a culture dish, and the degassed PDMS precursor is poured on the PVC base male die, vacuum is drawn in the vacuum drying oven to make the PDMS precursor fully enter the microstructure gap of the PVC base male die, then the culture dish is placed in a heating box for heating and solidification at 100℃ for 40min to form a silica gel elastomer, finally the silica gel elastomer is peeled off from the PVC base male die to form a PDMS female die.

[0018] The step three is the preparation of the SMP material: as shown in the following figure:Figure 1 As shown in FIGS. 1-16, taking bisphenol A diglycidyl ether matrix SMP as an example, the SMP described in the patent is not limited to bisphenol A diglycidyl ether matrix, and materials with shape memory properties are within the protection scope of the patent. First, bisphenol A diglycidyl ether 1-16 is preheated in a blast drying oven at 60°C for 2h to reduce the viscosity of the epoxy resin and increase its fluidity, then 100:20:10 bisphenol A diglycidyl ether is weighed into a beaker, then preheated at 500 rpm and 100°C on a magnetic stirrer, then the corresponding mass ratio of curing agent 4,4'-diaminodiphenyl methane and toughening copolymer poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) is added, and stirring is continued until the curing agent is completely dissolved to form an epoxy resin precursor.

[0019] The step four is the preparation of the epoxy resin-based shape memory biomimetic adhesive material: as shown in FIGS. 1-16, Figure 1 As shown in FIGS. 1-16, first, the uniformly stirred epoxy resin precursor in step three is placed in a vacuum drying oven at 100°C for 10 min to remove bubbles, second, the PDMS concave mold in step two is fixed on a culture dish and the epoxy resin casting precursor is placed above the PDMS concave mold, then it is placed in a vacuum drying oven at 100°C for 10 min to make the epoxy resin fully enter the internal micropores of the concave mold; then it is sealed and placed in a heating oven at 100°C for 2h and 120°C for 4h, after curing, the culture dish is taken out and slowly cooled to room temperature, finally the cured epoxy resin is peeled off from the PDMS concave mold, cut and washed to obtain the shape memory polymer-based biomimetic adhesive material. The structure is photographed by SEM electron microscope as shown in FIGS. 1-16. Figure 2

[0020] The working principle of the present application is: SMP realizes reversible shape memory effect through thermodynamic regulation, when the temperature is higher than the glass transition temperature (Tg), the molecular chain is disentangled and can be plastically deformed into a temporary shape by mechanical force; when the temperature is cooled to below Tg, the molecular chain rearranges and fixes the deformation; when the temperature is heated to above Tg again, the material restores the original shape. According to the above characteristics of the epoxy resin-based SMP, the present application designs an SMP adhesive system with a gecko-like microstructure based on SMP, and the principle is shown in FIGS. 1-16. Figure 2 As shown in FIGS. 1-16, when the temperature is below Tg, the material modulus is large, and it is difficult to form effective contact area with the contact surface, as shown in FIG. 1a; when the temperature rises above Tg, the microstructure softens to a rubber state, and under the pre-pressure, the microstructure buckles and lays down to adhere to the rough surface of the substrate, maximizing the contact area, as shown in FIG. 1b; after cooling to below Tg, the microstructure hardens to a glass state, and forms strong adhesion with the substrate through intermolecular forces (adhesion mode), as shown in FIG. 1c. Figure 3 Figure 3 Figure 3 ​​​As shown in Fig. 2c; when detached, heating makes the microstructure restore the initial shape, the contact area decreases sharply, and low-energy consumption separation (detachment mode) is realized, as shown in Fig. 2d. This dynamic regulation mechanism not only replicates the passive adaptability of gecko adhesion, but also endows the material with environmental response ability through temperature-driven active deformation, providing a new strategy for intelligent grabbing, reversible packaging, etc. Figure 3

[0021] The present application has the advantages of excellent adhesion performance and rapid and reversible state switching, integrates a buckling and lodging microstructure based on shape memory polymer, and is used to realize efficient regulation of material surface adhesion force. The thermal stimulation response mechanism realizes intelligent switching and recovery of the adhesion state. The present application has the advantages of simple stimulation mode (only a heat source is needed), reversible adhesion on various surfaces (smooth / rough), high adhesion strength, long cycle life, and self-adaptation to the environment.

[0022] Finally, it should be noted that the above-mentioned is only a specific embodiment of the present application. Obviously, the present application is not limited to the above-mentioned, and there are many variations, such as the shape, size, shape memory material type and its ratio of the microstructure. All the variations that can be directly derived or thought of from the disclosed content by those skilled in the art should be considered as the protection scope of the present application.​

Claims

1. A method for preparing a shape memory reversible biomimetic adhesive material, characterized in that, The method comprises the following steps: Step 1: PVC base convex mold preparation: PVC powder, 1,2-cyclohexane dicarboxylic acid diisononyl ester and tetrahydrofuran are mixed and stirred to form a PVC gel precursor, a silicon template is fixed on the bottom of a culture dish, the PVC gel precursor is poured and vacuum degassed, and after heating and curing, the PVC base convex mold is obtained by peeling off; Step 2: PDMS concave mold preparation: PDMS base material and curing crosslinking agent are configured in a mass ratio of 10:1 to form a PDMS precursor, which is stirred and degassed, then poured on the PVC base convex mold, vacuum treated to make the precursor fully fill the microstructure gap, and heated and cured to form a PDMS concave mold after peeling off; Step 3: SMP material preparation: the shape memory polymer base material is preheated to reduce the viscosity, the curing agent and the toughening copolymer are added and stirred until completely dissolved to form an epoxy resin precursor; Step 4: Bionic adhesive material preparation: the epoxy resin precursor is degassed and poured on the PDMS concave mold, vacuum treated to make the resin fully fill the micropores, and after stage heating and curing, the shape memory polymer base bionic adhesive material with a microstructure array is obtained by cooling and peeling off.

2. The method of claim 1, wherein: In step 1, the mass ratio of PVC powder, DINCH and tetrahydrofuran is 1:(0.5-1.5):(5-15), and the curing condition is 60℃ for 48 hours.

3. The method of claim 1, wherein: In step 3, the shape memory polymer base material is bisphenol A diglycidyl ether, the curing agent is 4,4'-diaminodiphenyl methane, and the toughening copolymer is poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), and the mass ratio of the shape memory polymer base material, the curing agent and the toughening copolymer is 100:(10-30):(5-20).

4. The method of claim 1, wherein: In step 4, the stage heating and curing condition is 100℃ for 2 hours, and then 120℃ for 4 hours.

5. The method of claim 1, wherein: The shape memory polymer base bionic adhesive material has a microstructure array on the surface, and the adhesion state can be reversibly switched by thermal stimulation.

6. The method of claim 5, wherein: The unit structure of the microstructure array is any one of columnar, mushroom-shaped or wedge-shaped structure, the height is 10-200μm, the diameter is 5-50μm, and the aspect ratio is 1-10.

7. The method of claim 1, wherein: The microstructure of the shape memory polymer base bionic adhesive material buckles and collapses above the glass transition temperature, forming the maximum contact area with the contact surface, and the microstructure hardens and fixes below the glass transition temperature, realizing strong adhesion through intermolecular forces.

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