Preparation method of electric-temperature dual stimulation deformation reversible composite material driver

Abstract

The invention relates to the technical field of flexible stimulation response self-drivers, in particular to a preparation method of an electricity-temperature dual stimulation deformation reversible composite material driver, which comprises the following steps: firstly, carrying out chemical modification and solution ultrasonic dispersion on conductor particles to improve interface cohesiveness and improve interface bonding between a conductor and a polymer; melting, blending and compounding polyethylene vinyl acetate free radical double-group coupling by using a double-screw mixer to prepare a shape memory hemicrystalline and carbon-carbon single bond net-shaped cross-linked molecular network structure; uniformly doping and embedding conductor unit particles into a molecular network to construct a conductive three-dimensional network, and forming a conductive blend with a bicontinuous phase structure; and finally, thermally pressing the conductive blend to initiate a macromolecular free radical cross-linking reaction to prepare the electric-temperature dual-stimulation deformation reversible composite material driver with a conductive-semi-crystalline-cross-linked three-dimensional network structure. According to the invention, electric and thermal dual stimulation reversible deformation response of the shape memory composite material can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible stimulus-responsive self-actuators, and in particular to a method for preparing an electrical-temperature dual-stimulation deformation reversible composite material actuator. Background Art

[0002] Stimuli-responsive polymers refer to a class of polymers whose molecular structure or state changes under external environmental stimulation (temperature, light, pH, electricity, magnetic field, etc.). With the development of bionics and materials science, intelligent polymer actuators that can sense and respond to external stimuli have shown good application prospects in the fields of soft robots, sensing and remote control.

[0003] However, most stimulus-responsive materials can only respond to a single external stimulus and have only one-way deformation (i.e., the deformation is irreversible). They are greatly restricted in the application fields of biomedical implant tissue scaffolds, self-driven folding aerospace structures, artificial muscles, etc. It is imperative to develop flexible materials with dual or multiple stimulus deformation responsiveness. Shape memory polymer materials with reversible deformation function can move reversibly and autonomously under external stimulation without external mechanical energy, and are increasingly attracting attention. They have potential application value in the field of lightweight flexible actuators. With the diversification of intelligent drive application scenarios, the requirements for remote control, local and instantaneous high controllability are becoming stronger and stronger, and deformation modes triggered by non-thermal energy have received high attention.

[0004] Therefore, in order to solve the above problems, the present application proposes a method for preparing an electrical-temperature dual stimulation deformation reversible composite material actuator. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings existing in the prior art, and a method for preparing an electric-temperature dual-stimulation deformation reversible composite material actuator is proposed. By introducing conductive particles, the internal resistance Joule heat of the composite material triggers the mutual transformation of the reversible phase crystallization and the cross-linked network when power is turned on, thereby realizing the electric and thermal dual-stimulation reversible deformation response of the shape memory composite material; the deformation reversible composite material prepared by the invention can not only be deformed by temperature drive, but also can remotely trigger the composite material to undergo reversible shape memory deformation effect under electrical stimulation.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing an electric-temperature dual stimulation deformation reversible composite material actuator comprises the following steps:

[0008] Step 1: First, the conductor particles are chemically modified and ultrasonically dispersed to improve the interface adhesion and improve the interface bonding between the conductor and the polymer;

[0009] Step 2, using a twin-screw mixer to melt-blend composite polyethylene vinyl acetate free radical double radical coupling to prepare a shape memory semi-crystalline and carbon-carbon single bond mesh cross-linked molecular network structure;

[0010] Step 3: uniformly doping and embedding conductor unit particles into the molecular network structure to construct a conductive three-dimensional network, thereby forming a dual-continuous phase structure conductive blend;

[0011] Step 4: Finally, hot pressing the conductive blend to induce a macromolecular free radical cross-linking reaction, enhance the orientation structure and density of the multi-walled carbon nanotubes, and prepare an electric-temperature dual-stimulation deformation reversible composite actuator with a conductive-semi-crystalline-cross-linked three-dimensional network structure.

[0012] Preferably, in step 1, the conductor particles are multi-walled carbon nanotubes with high thermal conductivity, and the thermal conductivity of the multi-walled carbon nanotubes is greater than 10W / mK; the modification process of the conductor particles is as follows: the multi-walled carbon nanotubes are added to a potassium hydroxide aqueous solution with a solution concentration of 25-40wt% for activation treatment at 400-450°C for 60 minutes, followed by ultrasonic dispersion for 30 minutes, sealed and heated in a 160°C stainless steel high-pressure furnace for 2 hours, and finally the solution is filtered, the multi-walled carbon nanotubes are rinsed with distilled water and ethanol until neutral, and placed in a 50°C oven for drying for 8 hours to constant weight to obtain modified multi-walled carbon nanotubes.

[0013] Preferably, in step 2, the melt blending and compounding is to feed thermoplastic polyethylene vinyl acetate polymer particles and benzoyl peroxide in a mass percentage of 10:100 into a twin-screw mixer for melt blending and compounding for 3 minutes; the polyethylene vinyl acetate polymer is composed of 18wt% vinyl acetate; the temperatures of three zones of the twin-screw mixer are preheated to 90°C, 95°C, and 100°C, and balanced for 5 minutes to ensure uniform temperature in the machine cavity, the average number average molecular weight of the polyethylene vinyl acetate polymer is 2000, and the melting point is 87°C; the average number average molecular weight of the peroxide initiator benzamide peroxide is 242.23, and the melting point is 104°C-106°C.

[0014] Preferably, in step 3, the conductive three-dimensional network is constructed by slowly feeding the modified multi-walled carbon nanotubes into the polyethylene vinyl acetate and benzoyl peroxide blend through the feeding port of a twin-screw mixer, and melt-blending them at a speed of 10 rpm for 10 minutes. The conductor particles are evenly dispersed in the uniformly mixed polymer network by relying on the pressure and shear force of the twin-screw mixer, and a cylindrical long strip with a diameter of 3 mm is obtained through melt-extrusion-cooling. The mass percentage content of the multi-walled carbon nanotubes in the conductive blend is 0.1wt%-0.5wt%.

[0015] Preferably, in step 4, the hot pressing method is: covering the dual-continuous phase structure conductive blend with upper and lower layers of polytetrafluoroethylene film release paper, clamping the outer layer with metal plates in a sandwich shape and sending it into a hot press for peroxide cross-linking reaction, the hot pressing temperature is 130°C, the pressure is 10MPa, and the hot pressing time is 20min, to produce an electric-temperature dual-stimulation deformation reversible composite actuator with a thickness of about 0.1-1mm.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention introduces multi-walled carbon nanotubes as conductive particles into a semi-crystalline-network cross-linked reversible dynamic molecular network to ingeniously prepare a flexible intelligent composite material actuator with electro-reversible deformation and thermo-reversible deformation characteristics. In addition to providing a method of directly triggering polymer deformation by temperature stimulation and heating, the present invention can also provide an indirect heating method for applications that cannot be directly thermally triggered. Multi-walled carbon nanotubes are uniformly embedded in the polymer molecular network, and the reversible deformation of the polymer is triggered by electrical stimulation using the principle of internal resistance heating of the polymer. This method is highly controllable (i.e., remote, local, and instantaneous stimulation deformation), and due to the low heat transfer coefficient of the polymer, it will not transfer too much heat to the surrounding environment. It has great application potential in the fields of self-expanding and self-folding aerospace structures, biomedical implanted stent tissues, flexible actuators and sensors.

[0018] 2. The carbon nanotubes in the present invention are a kind of carbon nanomaterial with outstanding performance in many aspects. The present invention combines multi-walled carbon nanotubes with semi-crystalline-net-shaped cross-linked reversible dynamic molecular networks as conductive phases and deformation reversible phases, which can make the electric-temperature dual stimulation composite material actuator have better deformation reversible responsiveness, better mechanical strength, flexibility and electrical activity, higher conductive behavior and low resistance and other excellent properties. In addition, the method of chemical functionalization modification and ultrasonic-assisted solution mixing of multi-walled carbon nanotubes in the present invention makes the multi-walled carbon nanotubes uniformly dispersed in the polymer network, improves the compatibility of different components in the blend, and is the key to the electric-temperature dual stimulation composite material actuator having excellent deformation reversible shape memory performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a cycle curve diagram of the temperature-stimulated deformation reversible driving performance of Example 1 of the present invention;

[0020] Figure 2 This is a comparison diagram of strain-temperature cycle curves of different multi-walled carbon nanotube contents in Examples 1, 2, and 3 of the present invention;

[0021] Figure 3 Schematic diagram of the reversible deformation response to dual stimulation of electricity and temperature according to Example 1 of the present invention. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0023] Embodiment 1:

[0024] A preparation method of an electric-temperature dual-stimulation deformation reversible composite material actuator, wherein a certain amount of multi-walled carbon nanotubes are added to a potassium hydroxide aqueous solution with a solution concentration of 25-40wt%, and after slowly stirring at 400-450°C for 60min, the solution is placed in an ultrasonic disperser for ultrasonic dispersion for 30min, and then placed in a 160°C stainless steel high-pressure furnace for sealing and heating for 2h; after filtering the solution, the multi-walled carbon nanotubes are rinsed with distilled water and ethanol until neutral, and placed in a 50°C oven for drying for 8h to constant weight to obtain modified multi-walled carbon nanotubes. 15g of polyethylene vinyl acetate polymer, 10wt% benzamide peroxide and 0.1wt% of multi-walled carbon nanotubes are sequentially fed into a small twin-screw mixer, and the mixture is mixed in an inner circulation at a speed of 10rpm for 10min. The mixed extrudate is collected and cooled to room temperature, and then the mixed extrudate is placed in a hot press for peroxide cross-linking reaction, and the hot pressing temperature is 130°C to prepare an electric-temperature dual-stimulation deformation reversible composite material actuator film EB with a thickness of about 0.1-1mm. 10 C 0.1 .

[0025] Embodiment 2:

[0026] A preparation method of an electric-temperature dual-stimulation deformation reversible composite material actuator, wherein a certain amount of multi-walled carbon nanotubes are added to a potassium hydroxide aqueous solution with a solution concentration of 25-40wt%, and after slowly stirring at 400-450°C for 60min, the solution is placed in an ultrasonic disperser for ultrasonic dispersion for 30min, and then placed in a 160°C stainless steel high-pressure furnace for sealing and heating for 2h; after filtering the solution, the multi-walled carbon nanotubes are rinsed with distilled water and ethanol until neutral, and placed in a 50°C oven for drying for 8h to constant weight to obtain modified multi-walled carbon nanotubes. 15g of polyethylene vinyl acetate polymer, 10wt% benzamide peroxide and 0.5wt% of multi-walled carbon nanotubes are sequentially fed into a small twin-screw mixer, and the mixture is mixed in an inner circulation at a speed of 10rpm for 10min. The mixed extrudate is collected and cooled to room temperature, and then the mixed extrudate is placed in a hot press for peroxide cross-linking reaction, and the hot pressing temperature is 130°C to prepare an electric-temperature dual-stimulation deformation reversible composite material actuator film EB with a thickness of about 0.1-1mm. 10 C 0.5 .

[0027] Embodiment 3:

[0028] A method for preparing an electric-temperature dual-stimulation deformation reversible composite material actuator, wherein a certain amount of multi-walled carbon nanotubes is added to a potassium hydroxide aqueous solution with a solution concentration of 25-40wt%, and after slowly stirring at 400-450°C for 60min, the solution is placed in an ultrasonic disperser for ultrasonic dispersion for 30min, and then placed in a 160°C stainless steel high-pressure furnace for sealed heating for 2h; after filtering the solution, the multi-walled carbon nanotubes are rinsed with distilled water and ethanol until neutral, and placed in a 50°C oven for drying for 8h to constant weight to obtain modified multi-walled carbon nanotubes. 15g of polyethylene vinyl acetate polymer and 10wt% of benzamide peroxide are fed into a small twin-screw mixer in sequence, and the mixture is mixed in an inner circulation at a speed of 10rpm for 10min. The mixed extrudate is collected and cooled to room temperature, and then the mixed extrudate is placed in a hot press for peroxide cross-linking reaction, and the hot pressing temperature is 130°C to prepare an electric-temperature dual-stimulation deformation reversible composite material actuator film EB with a thickness of about 0.1-1mm. 10 C0.

[0029] The electrical-temperature dual-stimulation deformation reversible composite materials of Examples 1-3 were cut into dumbbell-shaped films with a length of 10 mm and a width of 2 mm. The temperature-driven deformation reversible shape memory performance cycle curve was tested by a thermomechanical analyzer (TMA). Figure 1 , 2 As shown; the schematic diagram of reversible deformation response under dual stimulation of electricity and temperature is shown in Figure 3 shown.

[0030] from Figure 1 It can be seen that under the condition of constant external stress of 0.1MPa, the sample EB10 C 0.1 They exhibit elongation deformation during cooling and contraction deformation recovery during heating, and maintain long-term high repeatability and reversible deformation under long-term heating-cooling stimulation cycles; Figure 2 The effect of composite actuators without multi-walled carbon nanotubes and with different contents of multi-walled carbon nanotubes of 0.1wt% and 0.5wt% on the reversibility of deformation after temperature stimulation is shown. Under the action of a constant external force, as the temperature changes, the composite material shows strain elongation when the temperature drops and strain contraction when the temperature rises. When the mass fraction of multi-walled carbon nanotubes is 0.1wt%, the driving strain and recovery rate reach 3.4% and 99.8% respectively. During the cooling process of the polymer melt, some polymers maintain a disordered structure and will become an amorphous solid. The polymer composite actuator of the present invention is composed of multiple linear molecular bridges that are bonded and cross-linked to form a network structure and crystalline regions. Its molecular chains will rearrange, showing a cooling-deformation phenomenon. Figure 3 Display sample EB 10 C 0.1 As for the bending mobility after electrical stimulation, under the stimulation of 10V voltage, the film is driven to open within 5s, and when the voltage stimulation is turned off, the film recovers its shape within 20s, and exhibits long-term reversible deformation under the condition of continuous on-off cycle. The essence of the electro-deformation of the present invention is the electro-resistance Joule heat-heat-triggered deformation.

[0031] In summary, the electric-temperature dual-stimulation deformation reversible composite actuator prepared by the present invention can trigger the mutual transformation of reversible phase crystallization and cross-linked network through the internal resistance Joule heat of the composite material when power is turned on and heated, thereby realizing reversible and reciprocating flexible deformation of the shape memory composite material triggered by both electrical and temperature stimulation, and has broad application prospects in the fields of flexible actuators, biomedicine, soft robots, etc.

[0032] The description and practice disclosed in the present invention are easy to think and understand for ordinary technicians in the technical field, and several improvements and modifications can be made without departing from the principles of the present invention. Therefore, modifications or improvements made without departing from the spirit of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an electric-temperature dual stimulation deformation reversible composite actuator, characterized in that: The steps include: Step 1: First, the conductor particles are chemically modified and ultrasonically dispersed to improve the interface adhesion and improve the interface bonding between the conductor and the polymer; Step 2, using a twin-screw mixer to melt-blend composite polyethylene vinyl acetate free radical double radical coupling to prepare a shape memory semi-crystalline and carbon-carbon single bond mesh cross-linked molecular network structure; Step 3: uniformly doping and embedding conductor unit particles into the molecular network structure to construct a conductive three-dimensional network, thereby forming a dual-continuous phase structure conductive blend; Step 4: Finally, hot pressing the conductive blend to induce a macromolecular free radical cross-linking reaction, enhance the orientation structure and density of the multi-walled carbon nanotubes, and prepare an electric-temperature dual-stimulation deformation reversible composite actuator with a conductive-semi-crystalline-cross-linked three-dimensional network structure.

2. The method for preparing an electric-temperature dual stimulation deformation reversible composite material actuator according to claim 1, characterized in that: In step 1, the conductor particles are multi-walled carbon nanotubes with high thermal conductivity; the modification process of the conductor particles is: adding the multi-walled carbon nanotubes to a potassium hydroxide aqueous solution with a solution concentration of 25-40wt% for activation treatment at 400-450°C for 60 minutes, then ultrasonically dispersing for 30 minutes, sealing and heating in a 160°C stainless steel high-pressure furnace for 2 hours, finally filtering the solution, rinsing the multi-walled carbon nanotubes with distilled water and ethanol until neutral, and drying in a 50°C oven for 8 hours to constant weight to obtain modified multi-walled carbon nanotubes.

3. The method for preparing an electric-temperature dual stimulation deformation reversible composite material actuator according to claim 1, characterized in that: In step 2, the melt blending and compounding is to feed thermoplastic polyethylene vinyl acetate polymer particles and benzoyl peroxide with a mass percentage of 10:100 into a twin-screw mixer for melt blending and compounding for 3 minutes; the polyethylene vinyl acetate polymer is composed of 18wt% vinyl acetate; wherein the temperatures of the three zones of the twin-screw mixer are preheated to 90°C, 95°C, and 100°C, and balanced for 5 minutes to ensure uniform temperature in the machine cavity.

4. The method for preparing an electric-temperature dual stimulation deformation reversible composite material actuator according to claim 2, characterized in that: In step 3, the conductive three-dimensional network is constructed by slowly feeding the modified multi-walled carbon nanotubes into the polyethylene vinyl acetate and benzoyl peroxide blend through the feeding port of a twin-screw mixer, and melting and blending them at a speed of 10 rpm for 10 minutes. The conductor particles are evenly dispersed in the uniformly mixed polymer network by relying on the pressure and shear force of the twin-screw mixer. After melt-extrusion-cooling, a cylindrical long strip with a diameter of 3 mm is obtained to obtain a dual-continuous phase structure conductive blend; the mass percentage of the multi-walled carbon nanotubes in the conductive blend is 0.1wt%-0.5wt%.

5. The method for preparing an electric-temperature dual stimulation deformation reversible composite material actuator according to claim 1, characterized in that: In step 4, the hot pressing method is: cover the dual-continuous phase structure conductive blend with upper and lower layers of polytetrafluoroethylene film release paper, clamp the outer layer with metal plates in a sandwich shape and send it into a hot press for peroxide cross-linking reaction. The hot pressing temperature is 130°C, the pressure is 10MPa, and the hot pressing time is 20min to produce an electric-temperature dual-stimulation deformation reversible composite actuator with a thickness of 0.1-1mm.

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