A multi-stimulation bidirectional actuated composite film and its preparation method

Abstract

This invention discloses a multi-stimulation bidirectional actuation composite film and its preparation method. The multi-stimulation bidirectional actuation composite film comprises upper and lower films; the lower film is cast from a polyvinylidene fluoride solution, and the upper film is prepared by mixing and dissolving graphene and polydimethylsiloxane in a solution, followed by casting. During the preparation process, the two films naturally adhere to form the composite film. The composite film of this invention has advantages such as fast response speed, large deformation range, excellent mechanical properties, low cost, and simple preparation. The actuator prepared from the composite film of this invention has broad applications in the field of biomimetic soft robots.

Description

Technical Field

[0001] This invention relates to a type of thin film in the field of novel intelligent actuators, specifically to a multi-stimulation bidirectional actuation composite thin film and its preparation method. Background Technology

[0002] In recent years, novel intelligent actuators have shown promising applications in soft robotics and biomimetic devices due to their non-contact deformation, remote control, and bio-adaptability. Currently, based on a wide range of actuation materials such as shape memory polymers, liquid crystal elastomers, magnetic composites, conductive polymers, and carbon-based materials, actuators capable of responding to various external stimuli, such as those driven by light, temperature, humidity, electric fields, magnetic fields, and organic solvents, have been developed. Actuators typically employ a bilayer structure. The thermal expansion and contraction of the constituent materials, as well as the swelling effect of organic solvents, cause volume changes. The difference in volume between the two layers leads to reversible bending deformation, thereby producing temperature- and organic solvent-driven actuation effects.

[0003] However, most actuators employ a single-layer actuation strategy, where one layer undergoes significant deformation for actuation, while the other layer remains unresponsive as an inert layer. This limits the bending deformation direction of soft actuators, restricting their ability to achieve deformation in only one direction. Furthermore, the fabrication methods for many soft actuators are currently complex, resulting in relatively thin actuators that are difficult to manufacture, hindering their practical application. Therefore, there is an urgent need to explore new approaches to achieve bidirectional bending and improve mechanical performance, obtaining actuators that balance deformation range, response speed, and superior mechanical properties. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing a multi-stimulation bidirectional actuation composite film and its preparation method. Addressing the limitations of most actuators in bending direction and poor mechanical properties, this invention employs a dual-layer driving strategy, overcoming the limitations of unidirectional bending and achieving a wider range of deformation. Simultaneously, the actuator also exhibits fast response time and excellent mechanical properties.

[0005] The technical solution of the present invention is as follows:

[0006] I. A multi-stimulation bidirectional actuation composite film

[0007] The multi-stimulation bidirectional actuation composite film includes an upper film and a lower film, which are stacked together. The upper and lower films undergo different degrees of deformation under the influence of organic solvents, light, and temperature, resulting in bidirectional bending deformation of the composite film.

[0008] In other words, using light, temperature, and organic solvents as excitation sources, the composite film exhibits a swelling difference under the influence of organic solvents, resulting in a bidirectional response. The graphene in the composite film heats up under light, causing a difference in expansion under temperature. Specifically, when exposed to organic solvents, the two layers of the film swell to different degrees, resulting in bending. Furthermore, the bending deformation can vary in direction and degree depending on the different swelling levels of the two layers in the same organic solvent. When the ambient temperature rises, the different thermal expansion levels of the two layers also cause 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.

[0009] The upper film is composed of a mixture of graphene and polydimethylsiloxane.

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

[0011] The lower film is polyvinylidene fluoride.

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

[0013] II. A method for preparing a multi-stimulation bidirectional actuated composite film

[0014] 1) Mix polyvinylidene fluoride powder and dispersant evenly, then ultrasonically defoam and inject into a customized mold. Then place in a high-temperature oven and let stand at high temperature to promote the volatilization of dispersant, so that polyvinylidene fluoride can be cured into a film to obtain the upper film.

[0015] 2) Mix the polydimethylsiloxane main component agent, graphene and solvent evenly, then add the polydimethylsiloxane curing agent and mix evenly again and heat to remove the solvent. Then place the mixture in an ultrasonic device for defoaming treatment. Inject the defoamed mixture into a custom mold with the prepared lower film, place it in a high temperature oven and let it stand at high temperature to accelerate curing and molding. After drying, the two films will naturally bond together to obtain a multi-stimulation bidirectional actuation composite film.

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

[0017] In step 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 step 2), the solvent is cyclohexane, n-hexane, N,N-dimethylformamide, or tetrahydrofuran, and the stirring time for both stirring sessions is 30 min, and the stirring 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°C, the ultrasonic treatment time is 20 min, the high-temperature standing temperature is 60°C, and the time is 24 h.

[0020] III. Application of a Multi-Stimulation Bidirectional Actuation Composite Film

[0021] The application of the multi-stimulation bidirectional actuation composite film in circuits, artificial muscles, environmental pollution monitoring sensors, and soft robots.

[0022] IV. A circuit

[0023] The circuit includes a multi-stimulation bidirectional actuation composite film, which undergoes bidirectional bending under the influence of organic solvents, light, and temperature, causing the circuit to be in different on / off states.

[0024] V. A biomimetic soft robot

[0025] The biomimetic soft robot includes a multi-stimulation bidirectional actuation composite film.

[0026] Preferably, the customized mold is a thin groove made of glass plate and polyimide tape. The number of layers of the composite film is adjusted by adjusting the number of layers of polyimide tape. When preparing the upper film, a suitable mold needs to be made by increasing the number of tape layers after the lower film is made.

[0027] Preferably, the multi-stimulation bidirectional actuated composite film can bend and deform in two directions when responding to organic solvent stimulation. It adopts a dual-layer actuation strategy, in which both the upper and lower layers swell. When the upper film swells more than the lower film, it bends downward, and when the lower film swells more than the upper film, it bends upward. The composite film also deforms when it comes into contact with organic gas.

[0028] Preferably, the multi-stimulation bidirectional actuated composite film has a large bending range, and under the stimulation of organic solvents, when the aspect ratio of the sample is 12 / 5, it can achieve a bending radius of -90°. ° Up to 120 ° The deformation within the angular range can reach a maximum of 630 when the sample aspect ratio is 20 / 5. ° The deformation.

[0029] Preferably, the multi-stimulation bidirectional actuation composite film has a fast response time, and the shortest time to achieve maximum deformation under the stimulation of n-hexane is only 1.88s.

[0030] Preferably, the multi-stimulation bidirectional actuation composite film has excellent mechanical properties and can stably lift an object up to 180 times its own weight when stimulated by n-hexane.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention designs a multi-stimulation bidirectional actuation composite film. This composite film can achieve rapid temperature-induced bending deformation in two directions under the stimulation of an organic solvent, and possesses excellent mechanical properties. It overcomes the problems of weak mechanical properties and limitations in bending direction caused by the ultra-thin structure of soft actuators. This invention has low manufacturing cost and a simple process, and the resulting composite film simultaneously possesses a large bending range, fast response time, and excellent mechanical properties. Therefore, the multi-stimulation bidirectional actuation composite film can support various motion applications, such as the flowering and withering of water lilies. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the operation of a multi-stimulation bidirectional actuated composite film.

[0034] Figure 2 This is a photograph of the multi-stimulation bidirectional actuation composite film prepared in this invention.

[0035] Figure 3 A scanning electron microscope image of the cross-section of a multi-stimulus bidirectional actuated composite film.

[0036] Figure 4 Photographs showing variations of flowers made from the composite film prepared according to the present invention.

[0037] Figure 5 Circuit diagram and working photograph of a bidirectional switching circuit that can indicate environmentally specific organic solvents, made from the composite thin film prepared according to the present invention.

[0038] Figure 6 A photograph of an artificial wing made from the composite film prepared according to the present invention flapping.

[0039] Figure 7 Photograph of a graphene-based bidirectional actuation composite film lifting a heavy object.

[0040] Figure 8 An image of an artificial joint in motion, created from the composite film prepared according to the present invention.

[0041] Figure 9 The image shows the bending response of a composite film with a graphene mass fraction of 2% prepared according to the present invention under the stimulation of organic solvent, temperature, and light. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to specific embodiments.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] A method for preparing a multi-stimulation bidirectional actuated composite film, the method comprising the following steps:

[0048] 1) Mix polyvinylidene fluoride powder with dispersant and stir evenly for 60 minutes at a speed of 1500 rpm. After ultrasonic defoaming for 20 minutes, pour the mixture into a custom mold and place it in a high-temperature oven at 60°C for 2 hours to promote the volatilization of the dispersant and allow the polyvinylidene fluoride to solidify into a film to obtain the upper film. The dispersant is N,N-dimethylformamide, N-methylpyrrolidone, or dimethylthionite.

[0049] 2) Mix the polydimethylsiloxane main component, graphene, and solvent evenly. Then add the polydimethylsiloxane curing agent and mix again. Heat at 80℃ to remove the solvent. Stir for 30 minutes each time, at 1500 rpm. Next, place the mixture in an ultrasonic device for defoaming for 20 minutes. Inject the defoamed mixture into a custom mold with a pre-made lower film. Place it in a high-temperature oven at 60℃ for 24 hours to accelerate curing. After drying, the two films naturally bond together to obtain a multi-stimulation bidirectional actuated composite film. The solvent is cyclohexane, n-hexane, N,N-dimethylformamide, or tetrahydrofuran. The mass ratio of the polydimethylsiloxane main component to the curing agent is 10:1.

[0050] Applications of a multi-stimulation bidirectional actuation composite film in circuits, artificial muscles, environmental pollution monitoring sensors, and soft robots.

[0051] A circuit comprising a multi-stimulation bidirectional actuation composite film, which undergoes bidirectional bending under the influence of organic solvent / light / temperature, causing the circuit to be in different on / off states.

[0052] A biomimetic soft robot, comprising a multi-stimulation bidirectional actuation composite film.

[0053] In this embodiment, a method for preparing a multi-stimulation bidirectional actuated composite film includes the following steps: First, a lower film is prepared by adding 1g of polyvinylidene fluoride (PVDF) powder to 10mL of N,N-dimethylformamide. After stirring at 1500rpm, the mixture is ultrasonically treated to obtain a PVDF solution. This solution is then injected into a mold made of a glass plate and polyimide high-temperature resistant tape. The mold is placed in a high-temperature oven at 60°C to promote the volatilization of the dispersant and allow the PVDF to solidify into a film, thus completing the preparation of the upper film. Next, the upper film is prepared by weighing and mixing the main component of polydimethylsiloxane and graphene. Cyclohexane is added as a solvent, and the mixture is stirred in a magnetic stirrer for 30 minutes. Then, an appropriate amount of polydimethylsiloxane curing agent is weighed and added to the mixture, wherein the mass ratio of the main component to the curing agent is 10:1. The mixture is stirred and heated at 80°C until the cyclohexane is almost completely evaporated. Finally, the mixture is placed in an ultrasonic device for defoaming treatment and allowed to stand to obtain a mixed solution of graphene and polydimethylsiloxane. The mixed solution is injected into a mold with a polyvinylidene fluoride (PVDF) film attached, and the glass plate is placed in a high-temperature drying oven (60°C) to dry. After drying, the two films naturally bond together, and the double-layer film preparation is complete. Figure 2 As shown, the lower layer of the prepared composite film is transparent. Figure 3 The scanning electron microscope image shown shows that the thickness of the lower film is 21 μm and the thickness of the lower film is 155 μm, indicating good contact.

[0054] In this embodiment, a water lily-shaped actuator was designed and fabricated, such as... Figure 4 As shown, the petals are composed of a multi-stimulation, bidirectional actuation composite film. When stimulated with 30 μl of dichloromethane, they can bend upwards to simulate the blooming state of a water lily; when stimulated with 30 μl of N,N-dimethylformamide, they can bend downwards to simulate the wilting state of a water lily. In addition, the water lily-shaped actuator also bends upwards under infrared light and high temperature stimulation. Ultimately, this achieves the switching between the blooming and wilting states of the water lily-shaped actuator.

[0055] The composite film only exhibits bending in the second bending direction under the stimulation of specific organic solvents. A bidirectional switching circuit was designed and fabricated to indicate specific organic solvents in the environment. Based on the excellent mechanical properties and bidirectional bending characteristics of the composite film, a biomimetic bird wing flapping model with artificial muscle function was designed and fabricated. For example, under the stimulation of n-hexane, the artificial wing exhibits an upward flapping motion, and returns to its initial position during the evaporation of n-hexane; under the stimulation of N,N-dimethylformamide, the artificial wing exhibits a downward flapping motion, and returns to its initial position during the evaporation of N,N-dimethylformamide. Figure 5As shown, the circuit consists of parallel red and green LEDs, a power supply, a single-pole switch, contact electrodes, and a bidirectional switch. When temperature and light stimuli occur in the environment, the bidirectional switch bends in the first bending direction, connecting the circuit on the green LED side. When a specific organic solvent comes into contact with the composite film, the bidirectional switch bends in the second bending direction, connecting the circuit on the red LED side, illuminating the red light and thus indicating the presence of a specific organic solvent in the environment.

[0056] like Figure 6 As shown, the biomimetic bird wing flapping model with artificial muscle function consists of a bird body and artificial wings. The composite film in the artificial wing flapping model bends up and down under the stimulation of different organic solvents. At the same time, due to its excellent mechanical properties, it can further drive the paper wings to move, realizing the action of simulating the up and down flapping of bird wings.

[0057] like Figure 7 As shown, the double-layer actuator can stably lift an object 180 times its own weight under the stimulation of hexane, demonstrating the superior mechanical properties of the composite film. Simultaneously, a biomimetic bird wing flapping model was created by combining the composite film, paper wings, and the bird's body. The model consists of a bird's body and artificial wings. Both the bird's body and paper wings are cut from cardboard according to a customized shape. The artificial wings are formed by bonding the paper wings to the composite film with adhesive. Finally, the artificial wings are bonded to the bird's body to form the model, as shown. Figure 6 As shown, when the biomimetic bird wing flapping model is exposed to different types of organic solvents, it can be driven to perform continuous reversible bending motions of up and down flapping, similar to the flapping of a bird's wings during flight.

[0058] like Figure 8 As shown, the artificial joint model mimicking human movement consists of a human body, an artificial shoulder joint, and an artificial hip joint. The human body is made of cardboard cut to a customized shape, while the artificial shoulder and hip joints are both formed from composite films cut to a customized shape and then assembled using adhesive. When the artificial joints are exposed to organic solvents, light, or temperature stimuli, they bend and drive the human body to perform designated movements.

[0059] A method for preparing a graphene-based bidirectional actuated composite film includes the following steps: First, a lower film is prepared using the same method as in Example 1. Next, an upper film is prepared by weighing and mixing the main component of polydimethylsiloxane and graphene, ensuring that the graphene accounts for 2% of the total mass of the polydimethylsiloxane and graphene mixture. Cyclohexane is added as a solvent, and the mixture is stirred for 30 minutes. Then, an appropriate amount of polydimethylsiloxane curing agent is weighed and added to the mixture, with a main component to curing agent mass ratio of 10:1. The mixture is stirred and heated at 80°C until the cyclohexane is almost completely evaporated. The mixture is then subjected to defoaming treatment using an ultrasonic device and allowed to stand to obtain a mixed solution of graphene and polydimethylsiloxane. This mixed solution is injected into a mold with a polyvinylidene fluoride film attached, and a glass plate is placed in a high-temperature drying oven (60°C) to dry. After drying, the two films naturally bond together, resulting in a bilayer film with a graphene concentration of 2%.

[0060] like Figure 9 As shown, a bilayer film with a graphene concentration of 2% can exhibit bending responses to organic solvents, temperature, and light stimulation. Furthermore, it bends in different directions under the stimulation of different organic solvents.

[0061] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a multi-stimulation bidirectional actuated composite film, characterized in that, The preparation method includes the following steps: 1) Mix polyvinylidene fluoride powder with dispersant until uniform, then defoam by ultrasonication and inject into mold. Then let stand at high temperature to promote the volatilization of dispersant and allow polyvinylidene fluoride to solidify into film to obtain upper film. 2) Stir the polydimethylsiloxane main component agent, graphene and solvent evenly, then add the polydimethylsiloxane curing agent and stir evenly again and heat to remove the solvent. Then place the mixture in an ultrasonic device for defoaming treatment. Inject the defoamed mixture into a mold with the prepared lower film, let it stand at high temperature to accelerate curing and molding, and dry to obtain a multi-stimulation bidirectional actuation composite film. The multi-stimulation bidirectional actuated composite film exhibits bending deformation in two directions in response to organic solvent stimulation. The mass ratio of the mixture to graphene is 100:2-15; The thickness ratio of the upper film to the lower film is 10:1-2.

2. The method for preparing a multi-stimulation bidirectional actuation composite film as described in claim 1, characterized in that, In step 1), the dispersant is N,N-dimethylformamide, N-methylpyrrolidone, or dimethylthionylurea.

3. The method for preparing a multi-stimulation bidirectional actuated composite film as described in claim 1, characterized in that, In step 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.

4. The method for preparing a multi-stimulation bidirectional actuated composite film as described in claim 1, characterized in that, In step 2), the solvent is cyclohexane, n-hexane, N,N-dimethylformamide, or tetrahydrofuran, and the stirring time for both stirring sessions is 30 min, and the stirring speed is 1500 rpm.

5. The method for preparing a multi-stimulation bidirectional actuation composite film as described in claim 1, characterized in that, 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°C, the ultrasonic treatment time is 20 min, the high-temperature standing temperature is 60°C, and the time is 24 h.

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