A graphene-based bidirectional actuation composite film and applications thereof

Abstract

The application discloses a bidirectional actuation composite film based on graphene and application thereof. The composite film mainly comprises two layers of films; the lower layer is polyvinylidene fluoride, and the upper film is composed of graphene and polydimethylsiloxane. The composite film has the advantages of fast response speed, large deformation range, excellent mechanical performance, low cost, simple preparation and the like. The composite film can respond to various stimulations such as organic solvents, temperature and light. The composite film can be made into a bidirectional switch circuit with an organic solvent indicating function to indicate the specific organic solvent existing in the environment due to the reverse bending direction of the composite film to the specific organic solvent. In addition, the excellent mechanical performance of the composite film can support the application of the composite film as an artificial joint and bionic animal motion.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of novel intelligent actuators, and particularly relates to a graphene-based bidirectional actuation composite film and application thereof. BACKGROUND

[0002] Based on abundant actuation materials such as shape memory polymers, liquid crystal elastomers, conductive polymers and carbon-based materials, actuators capable of responding to different external stimuli are developed. Compared with traditional mechanical actuators, the actuators have flexible deformation, remote control and biological adaptability, and can realize bionic movements such as swimming and crawling. At present, actuators based on carbon-based materials have some application explorations in simple bionic movements due to the advantages of simple preparation method, low process cost and high biocompatibility, and have wide application prospects in environmental pollution indication and soft robot fields.

[0003] However, most of the current actuators are based on single-layer actuation strategy, which limits the application of the actuators due to the single deformation direction of the actuators. At the same time, most of the current actuators have some deficiencies in environmental pollution indication application due to the small and insignificant deformation degree. In addition, the thickness of the actuator is too small, which leads to very weak load bearing and poor mechanical properties, which seriously restricts the in-depth application of the actuator in the field of artificial muscles. Therefore, it is urgent to explore new ways to realize bidirectional bending and improve mechanical properties, to obtain an actuator that takes into account the deformation range, response speed and excellent mechanical properties, and to research the application method of the actuator for indicating specific organic solvents in the environment and as artificial joints and bionic animal movements. SUMMARY

[0004] The application aims to solve the above problems in the prior art, and provides a graphene-based bidirectional actuation composite film and application thereof. The application provides a bidirectional switch circuit for indicating specific organic solvents in the environment based on the bidirectional composite film and an application method of the composite film as artificial joints and bionic animal movements, aiming at the deficiencies of most actuators in environmental pollution indication application and the problem of poor mechanical properties restricting the application of the actuators in the field of artificial muscles.

[0005] One kind of graphene-based bidirectional actuation composite film

[0006] The graphene-based bidirectional actuation composite film comprises an upper film and a lower film, and the upper film and the lower film are arranged in layers. The upper film and the lower film are deformed to different degrees under the action of organic solvents, light or temperature, so that the composite film is deformed in two directions.

[0007] That is, under the action of organic solvents, the composite film produces a swelling difference, and produces a bidirectional response under the stimulation of organic solvents. The graphene in the composite film generates heat under the action of light, so that the composite film produces a swelling difference under the action of temperature. Specifically, when contacting the organic solvent, the swelling degrees of the two layers of films are different, thereby producing a bending action, and different bending deformations in different directions and degrees can be produced according to the different swelling degrees of the two layers of films to the same organic solvent; when the ambient temperature rises, the thermal expansion degrees of the two layers of films are different, thereby producing a bending action; when infrared light is irradiated, the graphene in the composite film produces a photothermal effect, resulting in a temperature rise, a thermal expansion difference value, and a bending action, thereby realizing the feedback to the external stimulation.

[0008] Preferably, the graphene-based bidirectional actuation composite film can obtain two-directional bending deformations in response to the stimulation of organic solvents, adopts a double-layer actuation strategy, and the upper and lower layers both swell. When the swelling of the upper layer of film is greater than that of the lower layer of film, the composite film bends downward, and when the swelling of the lower layer of film is greater than that of the upper layer of film, the composite film bends upward. In addition, the composite film also deforms when contacting the organic gas.

[0009] The upper layer of film is mixed from graphene and polydimethylsiloxane.

[0010] The mass ratio of the mixture of polydimethylsiloxane and graphene to graphene is 100:2-15.

[0011] The lower layer of film is polyvinylidene fluoride.

[0012] The thickness ratio of the upper layer of film to the lower layer of film is 10:1-2.

[0013] Two, a preparation method of a graphene-based bidirectional actuation composite film

[0014] 1) The polyvinylidene fluoride powder is mixed with a dispersant and stirred uniformly, then ultrasonic defoaming is performed, and then the mixture is injected into a customized mold, and then placed in a high-temperature oven to stand at high temperature to promote the volatilization of the dispersant, so that the polyvinylidene fluoride is cured into a film to obtain an upper layer of film.

[0015] 2) The polydimethylsiloxane main component agent, graphene and solvent are stirred uniformly, then the polydimethylsiloxane curing agent is added and stirred again, and then heated to remove the solvent. Then, the mixture is placed in an ultrasonic device for defoaming treatment, and then the defoaming treated mixture is injected into a customized mold with a prepared lower layer of film, and then placed in a high-temperature oven to stand at high temperature to accelerate curing and molding. After drying, the two layers of films are naturally bonded to obtain a graphene-based bidirectional actuation composite film.

[0016] In the 1), the dispersant is N,N-dimethylformamide, N-methylpyrrolidone or dimethyl sulfide.

[0017] In the 1), the stirring time is 60 min, the rotation speed is 1500 rpm, the ultrasonic treatment time is 20 min, the high-temperature standing temperature is 60℃, and the time is 2 h.

[0018] In the 2), the solvent is cyclohexane, n-hexane, N,N-dimethylformamide or tetrahydrofuran, and the stirring time is 30 min and the rotation speed is 1500 rpm.

[0019] The mass ratio of the polydimethylsiloxane main component agent to the curing agent is 10:1, the heating temperature for removing the solvent is 80℃, the ultrasonic treatment time is 20 min, the high-temperature standing temperature is 60℃, and the time is 24 h.

[0020] Preferably, the customized mold is a thin groove made of a glass plate and a polyimide tape, and the number of layers of the composite film is adjusted by adjusting the number of layers of the polyimide tape. When preparing the upper layer film, a mold with appropriate number of layers of the tape is prepared by increasing the number of layers of the tape after the lower layer film is prepared.

[0021] Three, an application of a graphene-based bidirectional actuation composite film

[0022] The graphene-based bidirectional actuation composite film is applied to circuits, artificial muscles, environmental pollution monitoring sensors, and soft robots.

[0023] Four, a circuit

[0024] The circuit comprises the graphene-based bidirectional actuation composite film, and the graphene-based bidirectional actuation composite film produces bidirectional bending under the action of an organic solvent / illumination / temperature, so that the circuit is in different on-off states.

[0025] Five, a bionic soft robot

[0026] The bionic soft robot comprises the graphene-based bidirectional actuation composite film.

[0027] Preferably, the graphene-based bidirectional actuation composite film has a large bending range. Under the stimulation of an organic solvent, when the length-width ratio of the sample is 12 / 5, a deformation range of -90 ° to 120 ° degrees can be achieved, and when the length-width ratio of the sample is 20 / 5, a maximum deformation of 630 ° can be obtained.

[0028] Preferably, the graphene-based bidirectional actuation composite film has a fast response time, and the shortest time for achieving maximum deformation under the stimulation of n-hexane is only 1.88s.

[0029] Preferably, the graphene-based bidirectional actuation composite film has excellent mechanical properties, and can stably lift a weight of 180 times its own weight under the stimulation of n-hexane.

[0030] The present application is based on a composite film that exhibits two bending directions under different stimuli, and is extended to various applications. Based on the characteristics that the composite film only exhibits bending in the second bending direction under the stimulation of a specific organic solvent, a bidirectional switch circuit capable of indicating a specific organic solvent in the environment is designed and prepared. Based on the excellent mechanical properties and bidirectional bending characteristics of the composite film, a bionic bird artificial wing waving model with artificial muscle effect is designed and prepared.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The present application designs a graphene-based bidirectional actuation composite film, which can achieve rapid bending deformation in two directions under the stimulation of light, temperature and organic solvent, and has excellent mechanical properties. Based on the above characteristics, a bidirectional switch circuit capable of indicating a specific organic solvent in the environment is prepared, which can realize the alarm of specified organic pollution in the environment. Due to its excellent mechanical properties, it can also support more flexible and bidirectional waving of bird artificial wing waving movement. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a working schematic diagram of the graphene-based bidirectional actuation composite film.

[0034] Figure 2 It is a circuit diagram and working photo of the bidirectional switch circuit capable of indicating a specific organic solvent in the environment prepared from the composite film according to the present application.

[0035] Figure 3 It is a photo of the artificial wing waving prepared from the composite film according to the present application.

[0036] Figure 4 It is a photo of the graphene-based bidirectional actuation composite film lifting a weight.

[0037] Figure 5 It is a photo of the artificial joint movement prepared from the composite film according to the present application.

[0038] Figure 6 It is a photo of the bending response of the composite film prepared from the graphene with a mass fraction of 2% according to the present application under the stimulation of organic solvent, temperature and light. DETAILED DESCRIPTION

[0039] The present invention will now be described in further detail with reference to specific embodiments.

[0040] In order to present the technical solution of the present invention more clearly and completely in the specific implementation process, the present invention will be clearly and completely described below with reference to specific examples. The described examples are only a part of the examples of the present invention, and cannot represent all the examples.

[0041] Unless otherwise specified, all materials and reagents used in the examples are commercially available or can be obtained by those skilled in the art using well-known methods. Specific experimental methods and operating conditions are generally performed according to standard process conditions, those described in the manual, or those recommended by the manufacturer.

[0042] like Figure 1 As shown, the composite film comprises an upper film (G@PDMS) and a lower film (PVDF), which are stacked together. The upper and lower films deform to different degrees under the influence of organic solvents, light, and temperature, resulting in bidirectional bending deformation of the composite film. Specifically, using light, temperature, and organic solvents as excitation sources, the composite film generates a swelling difference under the influence of organic solvents, producing a bidirectional response. The graphene in the composite film heats up under light, causing a difference in expansion under temperature. Specifically, when in contact with an organic solvent, the two films swell to different degrees, resulting in bending. The bending deformation can occur in different directions and degrees depending on the different swelling degrees of the two films with the same organic solvent. When the ambient temperature rises, the two films expand to different degrees, resulting in bending. When irradiated with infrared light, the graphene in the composite film generates a photothermal effect, leading to a temperature increase and a difference in thermal expansion, resulting in bending, thus achieving feedback to external stimuli.

[0043] The upper film is composed of a mixture of graphene and polydimethylsiloxane (PDMS). The mass ratio of the PDMS / PDMS mixture to graphene is 100:2-15. The lower film is polyvinylidene fluoride (PVDF). The thickness ratio of the upper film to the lower film is 10:1-2.

[0044] A method for preparing a graphene-based bidirectional actuation composite film, the method comprising the following steps:

[0045] 1) Polyvinylidene fluoride powder is mixed with a dispersant and stirred uniformly for 60 min at a speed of 1500 rpm, then treated with ultrasonic defoaming for 20 min, and then injected into a customized mold, and then placed in a high-temperature oven at a high temperature of 60℃ for 2h to promote the volatilization of the dispersant and make the polyvinylidene fluoride solidify into a film to obtain an upper film; the dispersant is N,N-dimethylformamide, N-methylpyrrolidone or dimethyl sulfourea.

[0046] 2) Polydimethylsiloxane main component agent, graphene and solvent are stirred uniformly, then polydimethylsiloxane curing agent is added and stirred again, and the solvent is removed by heating at a temperature of 80℃, the stirring time is 30 min and the stirring speed is 1500 rpm, then the mixture is placed in an ultrasonic device for defoaming treatment for 20 min, and then the defoaming treated mixture is injected into a customized mold with a prepared lower film, and then placed in a high-temperature oven at a high temperature of 60℃ for 24h to accelerate solidification and molding, and the two films are naturally bonded after drying to obtain a graphene-based bidirectional actuation composite film. The solvent is cyclohexane, n-hexane, N,N-dimethylformamide or tetrahydrofuran, and the mass ratio of polydimethylsiloxane main component agent to curing agent is 10:1.

[0047] The application of a graphene-based bidirectional actuation composite film in circuits, artificial muscles, environmental pollution monitoring sensors and soft robots.

[0048] A circuit containing a graphene-based bidirectional actuation composite film, which produces bidirectional bending under the action of organic solvents / illumination / temperature, so that the circuit is in different on-off states.

[0049] A bionic soft robot containing a graphene-based bidirectional actuation composite film.

[0050] A control method for a graphene-based bidirectional actuation composite film, which has two directions of bending, and under the stimulation of temperature, the thermal expansion degree of the upper film with main components of graphene and polydimethylsiloxane is greater than that of the lower film with main components of polyvinylidene fluoride, and the composite film bends towards the lower film, which is called the first deformation direction. At the same time, under the stimulation of light, the graphene generates heat due to the photothermal effect, causing the temperature of the composite film to rise, and its deformation is the same as the temperature stimulation, which is also the first bending direction. Under the stimulation of different organic solvents, the composite film will bend in the opposite direction, which is called the second bending direction. Here, a double-layer actuation strategy is applied, and the swelling degrees of the upper film and the lower film to different organic solvents are different. When the swelling of the upper film is greater than that of the lower film, the composite film bends towards the first bending direction, and when the swelling of the upper film is less than that of the lower film, the composite film bends towards the second bending direction.

[0051] Example 1

[0052] A preparation method of a graphene-based bidirectional actuation composite film, the specific steps are as follows: first, prepare the lower film, add 1 g of polyvinylidene fluoride powder into 10 mL of N,N-dimethylformamide, stir and then ultrasonic treatment to obtain a polyvinylidene fluoride solution, inject into a mold made of a glass plate and a polyimide high-temperature-resistant adhesive tape, and place in a high-temperature oven at 60°C to solidify the polyvinylidene fluoride into a film, and the upper film preparation is completed. Then prepare the upper film, mix the main component agent of polydimethylsiloxane and graphene, add cyclohexane as the solvent, and stir for 30 minutes. Then add an appropriate amount of the curing agent of polydimethylsiloxane into the mixture, and the mass ratio of the main component agent to the curing agent is 10:1, and stir and heat at 80°C until the cyclohexane is almost completely evaporated. Then place the mixture in an ultrasonic device for defoaming treatment and then stand to obtain a mixed solution of graphene and polydimethylsiloxane. Inject the mixed solution into the mold attached with the polyvinylidene fluoride film, and place the glass plate in a high-temperature drying oven (60°C) for drying. After drying, the two layers of films are naturally bonded, and the double-layer film preparation is completed.

[0053] Based on the fact that the composite film only exhibits the bending characteristic in the second bending direction under the stimulation of a specific organic solvent, a bidirectional switch circuit capable of indicating the specific organic solvent in the environment is designed and prepared. Based on the excellent mechanical properties and bidirectional bending characteristics of the composite film, a bionic bird artificial wing waving model with artificial muscle function is designed and prepared. The composite film only exhibits the bending characteristic in the second bending direction under the stimulation of a specific organic solvent, and the bidirectional switch circuit capable of indicating the specific organic solvent in the environment is designed and prepared, and based on the excellent mechanical properties and bidirectional bending characteristics of the composite film, a bionic bird artificial wing waving model with artificial muscle function is designed and prepared. For example, under the stimulation of n-hexane, the artificial wing exhibits an upward waving motion, and during the volatilization of n-hexane, the artificial wing returns to the initial position; under the stimulation of N,N-dimethylformamide, the artificial wing exhibits a downward waving motion, and during the volatilization of N,N-dimethylformamide, the artificial wing returns to the initial position.

[0054] As shown in Figure 2 The circuit is composed of parallel red and green light-emitting diodes, a power supply, a single-pole switch, contact electrodes, and a bidirectional switch, wherein the bidirectional switch is formed by combining copper foil and the composite film. The two contact electrodes are made of copper foil. When temperature and light stimulation appear in the environment, the bidirectional switch bends in the first bending direction, connecting the circuit on one side of the green diode. When a specific organic solvent contacts the composite film, the bidirectional switch bends in the second bending direction, connecting the circuit on one side of the red diode, and the red light is on, realizing the indication of the specific organic solvent in the environment.

[0055] As shown in Figure 3 , the bionic bird artificial wing waving model with artificial muscle effect is composed of a bird body and an artificial wing. The bird body is cut from card paper according to a customized shape. The artificial wing is composed of a composite film and a paper wing, the paper wing is cut from card paper according to a customized shape, and the composite film is cut to form a connecting part of the bird body and the paper wing. The bionic bird artificial wing waving model is made by bonding the composite film, the paper wing and the bird body with glue. The composite film in the artificial wing waving model bends up and down under the stimulation of different organic solvents, and at the same time, due to its excellent mechanical properties, it can further drive the paper wing to move, realizing the action of simulating the up and down waving of bird wings.

[0056] As shown in Figure 4 , the double-layer actuator can stably lift a weight 180 times its own weight under the stimulation of n-hexane, indicating that the composite film has superior mechanical properties. At the same time, the bionic bird artificial wing waving model is made by combining the composite film, the paper wing and the bird body. The model is composed of a bird body and an artificial wing, the bird body and the paper wing are cut from card paper according to a customized shape, the artificial wing is formed by bonding the paper wing and the composite film with glue, and finally the artificial wing and the bird body are bonded to form the model, as shown in Figure 3 . When the bionic bird artificial wing waving model is exposed to different types of organic solvents, it can drive the artificial wing to perform continuous reversible bending motion of up and down waving, similar to the flapping of bird wings when flying.

[0057] As shown in Figure 5 , the artificial joint model simulating human motion is composed of a human body, an artificial shoulder joint and an artificial hip joint. Among them, the human body is cut from card paper according to a customized shape, the artificial shoulder joint and the artificial hip joint are both cut from composite film according to a customized shape, and are combined by glue bonding. When the artificial joint is stimulated by organic solvents or light, temperature, etc., it will bend and drive the human body to perform specified movements.

[0058] A preparation method of a graphene-based bidirectional actuation composite film, the specific steps are as follows: first, prepare the lower film, the preparation method is the same as that of example one. Then prepare the upper film, mix the main component agent of polydimethylsiloxane and graphene by weighing, the weighing requirement is that the mass ratio of graphene to the mixture of polydimethylsiloxane and graphene is 2%, after adding cyclohexane as a solvent, stir the mixture for 30 minutes. Then take an appropriate amount of curing agent of polydimethylsiloxane and add it into the mixture, wherein the mass ratio of the main component agent to the curing agent is 10:1, stir and heat under the condition of 80℃ until the cyclohexane is almost completely evaporated. Then place the mixture in an ultrasonic device for defoaming treatment, and then stand still to obtain a mixed solution of graphene and polydimethylsiloxane. Inject the mixed solution into a mold attached with a polyvinylidene fluoride film, and place a glass plate into a high-temperature drying box (60℃) for drying, after drying, the two films are naturally bonded, and a double-layer film with a graphene concentration of 2% can be obtained.

[0059] As shown in Figure 6 The double-layer film with a graphene concentration of 2% can produce bending response to organic solvent, temperature and light stimulation. And under the stimulation of different organic solvents, different directions of bending are produced.

[0060] The above examples are only used to help understand the method of the present application and its core idea. It should be noted that for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A graphene-based bidirectional actuation composite film, characterized in that, The composite film comprises an upper film and a lower film, the upper film and the lower film are arranged in a laminated manner; the upper film and the lower film are deformed to different degrees under the action of an organic solvent, or an organic solvent, light and temperature, so that the composite film is bent in two directions; Under the stimulation of temperature, the composite film bends in the direction of the lower film, which is called the first bending direction; under the stimulation of light, the deformation is also the first bending direction; under the stimulation of different organic solvents, the swelling degrees of the upper film and the lower film to different organic solvents are different, when the swelling of the upper film is greater than that of the lower film, the composite film bends in the first bending direction, when the swelling of the upper film is less than that of the lower film, the composite film bends in the second bending direction; The upper film is composed of graphene and polydimethylsiloxane; The mass ratio of the mixture of polydimethylsiloxane and graphene to graphene is 100:2-15; The lower film is polyvinylidene fluoride; The thickness ratio of the upper film to the lower film is 10:1-2.

2. Use of a graphene-based bidirectional actuation composite film according to claim 1, characterized in that, The application of the graphene-based bidirectional actuation composite film in circuits, artificial muscles, environmental pollution monitoring sensors and soft robots.

3. A circuit, characterized by The circuit comprises the graphene-based bidirectional actuation composite film of claim 1, and the graphene-based bidirectional actuation composite film is bent in two directions under the action of an organic solvent, or an organic solvent, light and temperature, so that the circuit is in different on-off states.

4. A biomimetic soft robotic device, comprising: The bionic soft robot comprises the graphene-based bidirectional actuation composite film of claim 1.

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