Preparation method of temperature-stimulated deformation reversible response soft robot polymer

Abstract

The present application relates to the technical field of soft robot polymer, in particular to a preparation method of temperature stimulation deformation reversible response soft robot polymer, comprising the following steps: firstly, using linear semi-crystalline polymer polyvinyl acetate and peroxide initiator benzoyl peroxide to carry out solution blending polymerization as the soft robot polymer matrix; using particle leaching method to prepare holes in the semi-crystalline polymer, adjusting the particle size parameters of the pore forming agent to design the three-dimensional pore structure characteristics and pore morphology; finally, the linear molecules are bonded and bridged to form a soft robot polymer with a crosslinked network and a crystalline network structure. The soft polymer is prepared by constructing and regulating the three-dimensional porous structure, the complex pore stress distribution of the porous structure aims to realize high driving strain, and then the driving strain of the deformation soft intelligent porous driving material is regulated and improved, so that the driving performance is adjustable and the driving multifunction is realized.

Description

Technical Field

[0001] This invention relates to the field of soft robot polymer technology, and specifically to a method for preparing a temperature-stimulated deformation-reversible soft robot polymer. Background Technology

[0002] Today, porous polymers have significant potential applications across various fields. For example, they can be used to reduce impact damage, create flexible and intelligent porous actuating materials, generate highly sensitive porous sensing materials with significant structural changes and transmit clear electrical signals under minimal pressure, and develop porous adsorbent materials that autonomously transport liquids. Furthermore, porous structures provide gas and liquid permeability, offering excellent solutions for optimizing stimulus-response functionality. Research has found that the actuating strain of porous polymers is much greater than that of solids and non-porous structures. This may be related to the complex stress distribution in open-pore polymers under compression. Considering the pore as a simple spring, compression along a longer path generates higher spring energy. Anisotropic pore structures undergo significant changes along the high pore length direction. Additionally, the mechanical response deformation mechanisms of low-strain and high-strain pores differ; the stress interactions of bending, torsion, and buckling of pore walls in different directions give porous polymers a greater deformation actuating capacity compared to solid materials.

[0003] Developing porous polymers with stimulus-responsive reversible deformation capabilities not only allows for continuous, reciprocating contraction-expansion motion, but also provides lightweight, soft, superelastic, highly compressible, and sponge-like reversible contraction and expansion. However, controlling the flexible structure and design of stimulus-responsive reversible porous polymers to construct deformation space and achieve different driving performances and degrees of reversible deformation to cope with complex driving environments remains a challenge. Summary of the Invention

[0004] The purpose of this invention is to address the problem of small actuation deformation faced by intelligent bionic soft robots in the prior art. It proposes a method for preparing a temperature-stimulated deformation reversible soft robot polymer. By designing and preparing a temperature-stimulated soft robot polymer with a three-dimensional pore structure, the pore structure is precisely controlled from the structural design perspective, thereby improving and controlling the bidirectional stretching-contraction actuation performance of the porous polymer and further expanding the cutting-edge applications in the field of next-generation flexible actuators.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing a temperature-stimulated deformation-reversible soft robot polymer involves solution blending and polymerization of linear semi-crystalline polyethylene vinyl acetate and benzoyl peroxide as the soft robot polymer matrix. A particle leaching method is used to create pores in the semi-crystalline polymer system, and the particle size parameters of the pore-forming agent are adjusted to design the three-dimensional pore structure characteristics and pore morphology. Finally, the linear molecules undergo a bonding and bridging reaction to form an entangled network crosslinked with a crystalline network structure, resulting in a soft robot polymer with temperature-stimulated deformation-reversible response.

[0007] This invention uses a micro-crosslinked network and semi-crystalline region structure as a matrix to construct a deformation space by controlling the macroscopic three-dimensional channel structure, thereby improving driving performance and enabling multi-functional driving.

[0008] Preferably, the solution blending polymerization process is as follows: a quantitative amount of polyethylene vinyl acetate copolymer and 8 wt% benzoyl peroxide are dissolved in xylene, and the mixture is magnetically stirred at a constant speed in a sealed container at 90 °C for 12 h until the polyethylene vinyl acetate and the initiator benzoyl peroxide are completely dissolved in xylene, thereby obtaining a polymer-initiator mixture.

[0009] Preferably, the particle leaching method involves adding glucose particles to a polyethylene vinyl acetate polymer mixture and magnetically stirring at a constant speed for 6 hours in a fume hood at 80 °C. To obtain intact pore walls with uniform pore distribution and no large-area fractures, it is necessary to control the stirring speed and stir thoroughly. The xylene solvent evaporates slowly, so that the glucose particles do not easily accumulate at the bottom of the cup, and finally a uniformly dispersed polymer-initiator-glucose particle mixture is obtained.

[0010] Preferably, the solvent ratio of the polyethylene vinyl acetate polymer to the xylene organic solvent is 1:5, the mass percentage ratio of the polyethylene vinyl acetate polymer to the glucose particles is 1:6, and the particle sizes of the glucose particles are 50 μm, 110 μm, 160 μm, and 450 μm, respectively.

[0011] Preferably, the pore-forming process is as follows: the polymer-initiator-glucose particle mixture is poured into a cuboid mold and placed in an 80 ℃ high-temperature vacuum oven for 24 h to allow the organic solvent to slowly and completely evaporate. Then, it is placed in a 60 ℃ oven for 8 h to remove the residual solvent and obtain a polymer-initiator-glucose particle composite material block.

[0012] Preferably, the bridging reaction process is as follows: the prepared composite material block is placed in a vacuum tube furnace for bridging reaction. After the reaction is completed, the polymer-initiator-glucose particle composite material block is taken out and soaked in distilled water at 35 ℃ for 48 h to dissolve the glucose particles. During this period, the distilled water is replaced 5-6 times to obtain temperature-stimulated soft robot polymers with different pore structure characteristics, namely P-50, P-110, P-160 and P-450.

[0013] Preferably, the bridging reaction temperature is 300 °C, the reaction time is 5 h, and the nitrogen flow rate is 80 mL / min; the four different pore densities are 0.1865 g / cm³. 3 0.1775 g / cm 3 0.1529 g / cm 3 and 0.1434 g / cm 3 .

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] 1. This invention makes a beneficial exploration in the preparation method. By adjusting the size of the pore-forming particles to control different pore structures and pore sizes, it designs and prepares temperature-stimulated soft robot polymers with adjustable driving strain, adjustable structure, and flexible structure, which can meet different driving requirements in the field of thermal braking intelligent soft materials.

[0016] 2. This invention achieves lightweighting of polymers (density less than 0.15 g / cm³) by controlling the pore structure. 3 ) and flexibility (stiffness less than 0.2 N / mm) 2 It also has a direct effect on increasing the driving strain (increasing the strain by 5%), and the constructed soft robot polymer has reversible deformation stability.

[0017] 3. The method of adjusting pore size using particle leaching to achieve different bidirectional driving performance has not been explored by other researchers and belongs to an unexplored field. The pore structure control method of this invention is simple, mild, ingenious, and low-cost, and it is easy to prepare controllable pore size and porosity, thus achieving multifunctional driving. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of the present invention;

[0019] Figure 2 This is a schematic diagram of the bidirectional reversible drive and recovery cycle curves of the thermomechanical analysis (TMA) of the sample in Example 1 of the present invention (①-② drive contraction, ②-③ recovery expansion).

[0020] Figure 3 The graphs show the bidirectional driving performance of samples with different pore structure characteristics in Examples 1 and 4 of this invention under three cycles of cooling and heating.

[0021] Figure 4 The graphs show the bidirectional driving performance curves and deformation-driven-recovery performance comparisons of samples with different pore structure characteristics in Examples 1 and 4 of this invention under 10 cycles of cooling-heating.

[0022] Figure 5 These are three-dimensional X-ray tomography (3D X-ray μCT) images of different pore structure features in samples 1, 2, 3, and 4 of this invention. Detailed Implementation

[0023] To better understand the present invention, the following embodiments are further illustrations of the present invention.

[0024] This invention uses a cross-linked semi-crystalline network molecular structure as the polymer matrix. By precisely designing and controlling the macroscopic three-dimensional pore structure characteristics and pore morphology, it achieves improved bidirectional stretching-contraction driving performance, tunable structure, and multifunctional driving capabilities for soft robots.

[0025] Example 1:

[0026] A method for preparing a temperature-stimulated deformation reversible responsive soft robot polymer involves dissolving 10 g of linear semi-crystalline polyethylene vinyl acetate and 0.87 g of peroxide initiator benzoyl peroxide in 50 mL of xylene. The mixture is then magnetically stirred at a constant speed in a sealed container at 90 °C for 12 h until both the polyethylene vinyl acetate polymer and the initiator benzoyl peroxide are completely dissolved in the xylene, yielding a polymer-initiator mixture. 60 g of glucose particles with a particle size of 50 μm are added to the polymer-initiator mixture, and the mixture is magnetically stirred at a constant speed at 80 °C in a fume hood for 6 h to obtain a uniformly dispersed polymer-initiator-glucose particle mixture. The polymer-initiator-glucose particle mixture is poured into a cuboid mold and placed in a high-temperature vacuum oven at 80 °C for 24 h to allow the organic solvent to slowly and completely evaporate. Subsequently, it is placed in a 60 °C oven for 8 h to remove residual solvent, yielding a polymer-initiator-glucose particle composite material block. The prepared composite material is then placed in a 300 mL container. The bridging reaction was carried out in a vacuum tube furnace at ℃ for 5 hours. After the reaction was completed, the polymer-initiator-glucose particle composite material was soaked in distilled water at 35 ℃ for 48 hours to dissolve the glucose particles, thus obtaining the temperature-stimulated soft robot polymer P-50.

[0027] Example 2:

[0028] A method for preparing a temperature-stimulated deformation reversible soft robot polymer involves dissolving 10 g of linear semi-crystalline polyethylene vinyl acetate and 0.87 g of peroxide initiator benzoyl peroxide in 50 mL of xylene. The mixture is then magnetically stirred at a constant speed in a sealed container at 90 °C for 12 h until both the polyethylene vinyl acetate polymer and the initiator benzoyl peroxide are completely dissolved in the xylene, yielding a polymer-initiator mixture. 60 g of glucose particles with a particle size of 110 μm are added to the polymer-initiator mixture, and the mixture is magnetically stirred at a constant speed at 80 °C in a fume hood for 6 h to obtain a uniformly dispersed polymer-initiator-glucose particle mixture. The polymer-initiator-glucose particle mixture is poured into a cuboid mold and placed in a high-temperature vacuum oven at 80 °C for 24 h to allow the organic solvent to slowly and completely evaporate. Subsequently, it is placed in a 60 °C oven for 8 h to remove residual solvent, yielding a polymer-initiator-glucose particle composite material block. The prepared composite material is then placed in a 300 mL container. The bridging reaction was carried out in a vacuum tube furnace at ℃ for 5 hours. After the reaction was completed, the polymer-initiator-glucose particle composite material was soaked in distilled water at 35 ℃ for 48 hours to dissolve the glucose particles, thus obtaining the temperature-stimulated soft robot polymer P-110.

[0029] Example 3:

[0030] A method for preparing a temperature-stimulated deformation-reversible soft robot polymer involves dissolving 10 g of linear semi-crystalline polyethylene vinyl acetate and 0.87 g of peroxide initiator benzoyl peroxide in 50 mL of xylene. The mixture is then magnetically stirred at a constant speed in a sealed container at 90 °C for 12 h until both the polyethylene vinyl acetate polymer and the benzoyl peroxide initiator are completely dissolved in the xylene, yielding a polymer-initiator mixture. 60 g of glucose particles with a particle size of 160 μm are added to the polymer-initiator mixture, and the mixture is magnetically stirred at a constant speed at 80 °C in a fume hood for 6 h to obtain a uniformly dispersed polymer-initiator-glucose particle mixture. The polymer-initiator-glucose particle mixture is poured into a cuboid mold and placed in a high-temperature vacuum oven at 80 °C for 24 h to allow the organic solvent to slowly and completely evaporate. Subsequently, it is placed in a 60 °C oven for 8 h to remove residual solvent, yielding a polymer-initiator-glucose particle composite material block. The prepared composite material is then placed in a 300 mL container. The bridging reaction was carried out in a vacuum tube furnace at ℃ for 5 hours. After the reaction was completed, the polymer-initiator-glucose particle composite material was soaked in distilled water at 35 ℃ for 48 hours to dissolve the glucose particles, thus obtaining the temperature-stimulated soft robot polymer P-160.

[0031] Example 4:

[0032] A method for preparing a temperature-stimulated deformation-reversible soft robot polymer involves dissolving 10 g of linear semi-crystalline polyethylene vinyl acetate and 0.87 g of peroxide initiator benzoyl peroxide in 50 mL of xylene. The mixture is then magnetically stirred at a constant speed in a sealed container at 90 °C for 12 h until both the polyethylene vinyl acetate polymer and the benzoyl peroxide initiator are completely dissolved in the xylene, yielding a polymer-initiator mixture. 60 g of glucose particles with a particle size of 450 μm are added to the polymer-initiator mixture, and the mixture is magnetically stirred at a constant speed at 80 °C in a fume hood for 6 h to obtain a uniformly dispersed polymer-initiator-glucose particle mixture. The polymer-initiator-glucose particle mixture is poured into a cuboid mold and placed in a high-temperature vacuum oven at 80 °C for 24 h to allow the organic solvent to slowly and completely evaporate. Subsequently, the mixture is placed in a 60 °C oven for 8 h to remove residual solvent, yielding a polymer-initiator-glucose particle composite material block. The prepared composite material is then placed in a 300 mL container. The bridging reaction was carried out in a vacuum tube furnace at ℃ for 5 hours. After the reaction was completed, the polymer-initiator-glucose particle composite material was soaked in distilled water at 35 ℃ for 48 hours to dissolve the glucose particles, thus obtaining the temperature-stimulated soft robot polymer P-450.

[0033] Performance testing

[0034] 1. Thermomechanical Analysis - Bidirectional Reversible Drive Performance Testing

[0035] Test examples 1 and 4 yielded thermomechanical curves of bidirectional driving performance of samples with different pore structure characteristics under three cooling-heating cycles. The test results are as follows: Figure 3 As shown, the different bidirectional reversible driving and recovery strains are mainly attributed to different pore structures. P-50, with the smallest pore size, exhibits stronger bidirectional reversible driving performance (>5%) and shape recovery performance (>98%). Test results are as follows... Figure 4 The results show 10 long-term, highly repeatable bidirectional reversible actuation and recovery cycle curves, demonstrating the stability and repeatability of the temperature-stimulated soft robot polymer reversible deformation actuation of the present invention. Figure 4 Generally, the first drive-recovery cycle usually results in poor deformation response performance and cannot reflect the true bidirectional reversible drive state. However, after the first heating-cooling cycle, the reversible driven contraction-recovery expansion performance tends to stabilize and becomes more stable with the increase of thermomechanical cycle number. This may be because the first heating-cooling cycle is equivalent to annealing and eliminating thermal history, which is related to the material's own crystallization behavior.

[0036] 2. Three-dimensional X-ray tomography test

[0037] Test Examples 1, 2, 3, and 4 yielded three-dimensional X-ray tomography (3D X-ray μCT) images with different pore structure characteristics, as shown below. Figure 5As shown, the brown area in the CT scan image represents the pore wall, and it can be seen that the pore size gradually decreases (from...). Figure 5 (a to 5d). For example... Figure 5 As can be seen from Example 4, the sponge-like polymer has a relatively loose pore framework structure with significantly larger pore sizes. Figure 5 As can be seen from d, the polymer of Example 1 has a dense pore framework structure with the smallest pore size.

[0038] In summary, this invention constructs a diverse deformation space for temperature-stimulated soft robot polymers by regulating the macroscopic pore structure characteristics, controlling the heat transfer path, improving the bidirectional reversible stretch-contraction driving performance, and further expanding the cutting-edge applications in the field of next-generation flexible self-driving.

[0039] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a temperature-stimulated deformation-reversibly responsive soft robot polymer, characterized in that: A solution blending polymerization of linear semi-crystalline polyethylene vinyl acetate and peroxide initiator benzoyl peroxide was used as the polymer matrix for soft robots. Pores were created in the semi-crystalline polymer system using particle leaching, and the three-dimensional pore structure characteristics and pore morphology were designed by adjusting the particle size parameters of the pore-forming agent. Finally, the linear molecules bonded and bridging each other to form an entangled network crosslinked with a crystalline network structure, resulting in a soft robot polymer with reversible temperature-induced deformation response. The solution blending polymerization process is as follows: a quantitative amount of polyethylene vinyl acetate copolymer and 8 wt% benzoyl peroxide are dissolved in xylene, and the mixture is magnetically stirred at a constant speed in a sealed container at 90°C for 12 hours until the polyethylene vinyl acetate and the initiator benzoyl peroxide are completely dissolved in xylene to obtain a polymer-initiator mixture. The particle leaching method involves adding glucose particles to a polymer-initiator mixture and magnetically stirring at a constant speed in a fume hood at 80°C for 6 hours. By controlling the stirring speed, the xylene solvent slowly evaporates, making it difficult for glucose particles to accumulate at the bottom of the cup, and finally obtaining a uniformly dispersed polymer-initiator-glucose particle mixture. The ratio of polyethylene vinyl acetate to xylene organic solvent is 1:5, the mass percentage ratio of polyethylene vinyl acetate to glucose particles is 1:6, and the particle size of the glucose particles is 50μm-450μm. The pore-forming process is as follows: the polymer-initiator-glucose particle mixture is poured into a cuboid mold and placed in an 80°C high-temperature vacuum oven for 24 hours to allow the organic solvent to slowly and completely evaporate. Then, it is placed in a 60°C oven for 8 hours to remove the residual solvent and obtain a polymer-initiator-glucose particle composite material block.

2. The method for preparing a temperature-stimulated deformation reversible soft robot polymer according to claim 1, characterized in that: The bridging reaction process is as follows: the prepared composite material block is placed in a vacuum tube furnace for bridging reaction. After the reaction is completed, the polymer-initiator-glucose particle composite material block is taken out and soaked in 35°C distilled water for 48 hours to dissolve the glucose particles. During this period, the distilled water is replaced 5-6 times to obtain temperature-stimulated soft robot polymers with different pore structure characteristics.

3. The method for preparing a temperature-stimulated deformation reversible soft robot polymer according to claim 1, characterized in that: The bridging reaction temperature was 300℃, the reaction time was 5h, and the nitrogen flow rate was 80mL / min.

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