Double-layer MXene membrane multi-stimulation response actuator and preparation method and application thereof

Abstract

The invention discloses a double-layer MXene film multi-stimulation response actuator and a preparation method and application thereof, the double-layer MXene film multi-stimulation response actuator is composed of an active layer of an MXene / bacterial cellulose BC composite film and an inert layer with a large thermal expansion coefficient, so that the double-layer MXene film multi-stimulation response actuator is bent and deformed when subjected to humidity and photo-thermal stimulation. The deformation degree of the actuator can be changed by changing the content of Mxene, and the application effect of the actuator is enriched. The multi-stimulation response actuator can generate quick response under stimulation of light, heat and humidity, shows a good actuating effect, can avoid the problem of falling off, can adapt to complex environments, and has huge application potential in the fields of multi-stimulation response robots, artificial muscles, cell scaffolds, micromanipulators and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of actuators, and particularly relates to a bilayer MXene film multiple stimulus-responsive actuator, a preparation method thereof, and an application thereof. Background Art

[0002] Intelligent actuators can convert other forms of energy into mechanical deformation from external stimuli such as heat, light, electricity, magnetism, solvents, pH value, and humidity. Intelligent actuators based on multiple stimulus-responsive materials have shown great application potential in many fields such as artificial intelligence and soft robotics.

[0003] Actuators made of different driving materials have different response mechanisms to each stimulus, and the actuators will deform due to multiple mechanisms, including thermal expansion / contraction, changes in the degree of humidity adsorption, or changes in molecular structure. Although multi-stimulus responsiveness can be obtained by mixing different functional fillers, the mixing often leads to poor performance due to the low doping percentage of the fillers, and increasing the doping percentage may cause filler aggregation, ultimately having a negative impact on the shape memory performance and mechanical properties of the material. Therefore, it is highly desirable but also challenging to develop a new type of homogeneous polymer material that exhibits multi-stimulus response behavior. Summary of the Invention

[0004] Aiming at the defects involved in the background art, the purpose of the present invention is to provide a bilayer MXene film multiple stimulus-responsive actuator and a preparation method thereof.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] In a first aspect, the present invention provides a bilayer MXene film multiple stimulus-responsive actuator, which is composed of an active layer of an MXene / bacterial cellulose BC composite film (MBC) and an inert layer with a large coefficient of thermal expansion, so that it bends and deforms under humidity and photothermal stimuli.

[0007] Further, the multiple stimulus response is formed by bonding the active layer and the inert layer together.

[0008] Further, the MXene in the MXene / bacterial cellulose BC composite film is Ti3C2T x .

[0009] Furthermore, the MXene / bacterial cellulose BC composite film is formed by mixing an MXene colloid and a bacterial cellulose dispersion, modifying with dopamine, and vacuum filtering to form a film.

[0010] Further, the mass ratio of MXene to bacterial cellulose BC is 0.3 to 1.5:1.

[0011] Further, the inert layer with a relatively large coefficient of thermal expansion refers to an inert layer with a coefficient of thermal expansion of (30 - 300)×10- 6 / °C.

[0012] Furthermore, the inert layer is any one of polyimide tape (PI) and polyester tape.

[0013] Further, the thickness of the MXene / bacterial cellulose BC composite membrane is 15 - 20 μm; the thickness of the inert layer is 30 - 40 μm.

[0014] Further, when the multi-stimulus responsive actuator is stimulated by humidity, it bends from one side of the active layer to the side of the inert layer; when stimulated by near-infrared photothermal, it bends from one side of the inert layer to the side of the active layer.

[0015] In a second aspect, the present invention also discloses a preparation method of a double-layer MXene film multi-stimulus responsive actuator, including the following steps:

[0016] Step 1), homogenize and defoam the bacterial cellulose fibrils to obtain a uniform bacterial cellulose dispersion (BCNF);

[0017] Step 2), add MXene colloid to the bacterial cellulose dispersion and mix, add dopamine for modification, and use Tris to adjust the pH to 7.5 - 8.5;

[0018] Step 3), stir the mixture in Step 2 at room temperature for 4 hours, and perform vacuum filtration using a filter membrane;

[0019] Step 4), obtain the MXene / bacterial cellulose BC composite membrane after drying;

[0020] Step 5), bond the MXene / bacterial cellulose BC composite membrane obtained in Step 4 with the inert layer, and cut it into a target shape to obtain a multi-stimulus responsive multi-stimulus responsive actuator.

[0021] Further, the concentration of the MXene colloid is 5 mg / mL; the concentration of the bacterial cellulose dispersion is 1 mg / mL.

[0022] In a third aspect, the present invention provides a use of a double-layer MXene film multi-stimulus responsive actuator as an intelligent actuator.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. In the present invention, the ability of bacterial cellulose to absorb moisture and swell is utilized to cause bending in a humidity environment; the excellent photothermal conversion ability of Mxene is utilized, and under photothermal stimulation, straightening is caused due to the dehydration of Mxene upon heating and the reverse thermal expansion and contraction of the inert layer; realizing the response of the actuator to humidity and infrared light stimulation.

[0025] 2. The actuator prepared by the present invention has a fast response speed, large deformation, a reversible, repeatable, and controllable deformation process.

[0026] 3. The preparation process of the present invention is simple, can be prepared on a large scale, has a low price, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the purpose, technical solution, and beneficial effects of the present invention, the following drawings are provided for illustration:

[0028] Figure 1 SEM images of MBC / PI-2 actuators at different magnifications in the examples;

[0029] Figure 2 XPS images of MBC / PI-2 actuators in the examples, a: C 1s, b: O 1s;

[0030] Figure 3 Bending angles of four actuators in the examples under different humidity environments;

[0031] Figure 4 Optical images of the bending of MBC / PI-2 actuators under near-infrared light irradiation in the examples;

[0032] Figure 5 Bending angles of four actuators in the examples under near-infrared radiation in a relative humidity environment of 60%;

[0033] Figure 6 Cyclic braking effect of MBC / PI-2 actuators in the examples in a relative humidity environment of 60%. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The technical solutions in the embodiments of the present invention will be clearly described below in conjunction with the drawings of the present invention.

[0035] MXene, known as a group of transition metal carbides or nitrides analogues, is a new type of two-dimensional material. Due to its high electrical conductivity, superior thermal conductivity, excellent photothermal conversion efficiency, and good hydrophilicity, it has been considered as a preferred material for preparing multi-stimulus responsive actuators. Bacterial cellulose (BC) has excellent hydrophilicity and water-induced swelling, making it highly sensitive to humidity changes and capable of responding quickly to humidity changes. Secondly, it has an ultrafine network structure composed of nanofibers with a diameter of 3-4 nm assembled into fiber bundles with a diameter of 20-50 nm, which has high strength and flexibility, and can also minimize the negative impact of foreign insulating substances on the electrical conductivity of MXene, ensuring that the soft robots made from it have excellent durability and stability.

[0036] A double-layer MXene film multi-stimulus responsive actuator of the present invention, the multi-stimulus responsive actuator includes an MXene / bacterial cellulose BC composite film (MBC) active layer and an inert layer with a large thermal expansion coefficient; the active layer and the inert layer are bonded together to form a multi-stimulus responsive actuator, so that it bends and deforms under humidity and photothermal stimuli.

[0037] The principle by which the actuator of the present invention can achieve multi-stimulus response is as follows:

[0038] When light irradiates on the film, the excellent photothermal effect of the MXene material comes into play. It can convert light energy into heat energy, causing the temperature to rise. Not only will the inert layer with a large thermal expansion coefficient expand, but the increase in temperature will also accelerate the evaporation of water in the moisture-absorbing MBC film, causing the actuator to bend towards the MBC film side. Since bacterial cellulose with abundant oxygen-containing functional groups adsorbs many water molecules, and BC has a strong response to humidity, it quickly absorbs water and swells in a humid environment, causing the actuator to bend towards the inert layer side when the light stops / temperature drops. The deformation degree of the actuator can be changed by changing the Mxene content in the MBC.

[0039] Example 1

[0040] Ti3C2T x - Synthesis of Ti3C2T-MXene colloid: First, 2 g of LiF powder was slowly added to 40 mL of 9M HCl hydrochloric acid and continuously stirred for 30 minutes. Subsequently, 2 g of Ti3AlC2 powder was slowly added to the etching solution and stirred at 35 °C for 48 hours. The etching product was washed (5000 rpm, 10 minutes) until the pH value of the supernatant was 5-7. Then the precipitate was redispersed in 20 mL of deionized water and ultrasonically treated in a nitrogen gas stream in a water bath (maintained below 4 °C) for 1 hour, and then centrifuged at 3000 rpm for 20 minutes to obtain a Ti3C2T colloid solution with a concentration of 5 mg / mL in the supernatant. x colloid solution.

[0041] Synthesis of BCNF: BC was homogenized with a high-pressure homogenizer at a pressure level of 100 MPa and degassed in water for more than 25 cycles to obtain a uniform 1 mg / mL BCNF dispersion.

[0042] MBC membrane preparation: 0.05 g dopamine was added to 30 ml of 1 mg / mL BCNF solution and ultrasonicated for 10 min to obtain an aqueous dispersion. x The colloidal solution was added dropwise to the aqueous dispersion, and then an appropriate amount of Tris was added to make the solution pH about 8.5. The mixture was stirred at 30°C for more than 4 hours, and 15 mL of the mixture was filtered to form an MBC membrane, which was dried at room temperature. x The amount of colloidal solution added is based on the mass ratio of Ti3C2T x : BC conversion was 1:3, 1:1, and 3:2, and three MBC films were obtained, which were named MBC-1, MBC-2, and MBC-3 respectively.

[0043] Preparation of multi-stimulus responsive actuators: Cut the PI tape into the same size as the MBC film (0.5*2cm), and fully bond it with the above-mentioned MBC-1, MBC-2, and MBC-3 in turn to finally obtain multi-stimulus responsive actuators, which are marked as MBC / PI-1, MBC / PI-2, and MBC / PI-3, respectively.

[0044] Comparative Example 1

[0045] 0.05 g dopamine was added to 30 ml of 1 mg / mL BCNF solution, and ultrasonic treatment was performed for 10 minutes to obtain an aqueous dispersion. Then, an appropriate amount of Tris was added to make the solution pH about 8.5, and the reaction was stirred at 30°C for more than 4 hours. 15 mL of the mixed solution was filtered to form a membrane, and dried at room temperature to obtain a BC membrane.

[0046] The PI tape was cut into the same size as the BC film (0.5*2cm) and fully bonded to the BC film to finally obtain an actuator, named BC / PI.

[0047] Comparative Example 2

[0048] 0.05 g dopamine was added into 10 ml of 5 mg / mL Ti3C2T x The colloidal solution was ultrasonicated for 10 minutes to obtain an aqueous dispersion, and then an appropriate amount of Tris was added to make the solution pH about 8.5. The reaction was stirred at 30°C for more than 4 hours, 5 mL of the mixed solution was filtered to form a membrane, and dried at room temperature to obtain a MXene membrane.

[0049] The PI tape was cut into the same size (0.5 * 2 cm) as the MXene film and fully bonded to the MXene film, and finally an actuator named MXene / PI was obtained. Since there is no embedding of BCNF in the MXene / PI actuator, its mechanical properties are poor and it is prone to breakage during preparation.

[0050] Among them, the SEM of MBC / PI-2 is as Figure 1 shown, indicating that the thickness of the MBC film of MBC / PI-2 is about 18 μm, showing a slight stacking phenomenon, which may be due to the adhesion of the phenolic hydroxyl groups of dopamine. In the middle of the layer, the stacked flaky structure is MXene, and the filamentous skeleton is BCNF, similar to "steel bars" embedded between MXene nanosheets, forming a dense and ordered layered structure. The PI tape layer in MBC / PI-2 is uniform in texture and has a relatively large thickness of about 50 μm, indicating that it provides the necessary support and mechanical strength for the multi-stimulus response actuator.

[0051] The XPS of MBC / PI-2 is as Figure 2 shown, indicating that the MBC film mainly contains hydroxyl (-OH) functional groups, making it have humidity response characteristics.

[0052] The bending angles of MBC / PI-1, MBC / PI-2, MBC / PI-3, and BC / PI were tested under different humidity conditions, and the test results are as Figure 3 , BC / PI has the largest bending angle, while the bending angles of MBC / PI-1, MBC / PI-2, and MBC / PI-3 decrease with the increase of the Mxene ratio. It shows that BC / PI has the best humidity response performance.

[0053] The states of MBC / PI-2 before and after irradiation with an 808 nm near-infrared lamp are as Figure 4 shown. It can be seen from Figure 4 that under 808 nm near-infrared irradiation, the bending angle of the strip is significantly restored, reflecting its sensitive response performance to near-infrared light.

[0054] The MBC / PI-1, MBC / PI-2, MBC / PI-3, and BC / PI actuators show significant photothermal mechanical responses to near-infrared radiation, as Figure 5 shown. When the response time is specified as within 2 seconds of infrared irradiation, the recovery time is 10 seconds. Among them, the BC / PI actuator has the worst photothermal stimulation response performance. Among the three MBC / PI actuators, MBC / PI-2 has the best actuation performance. At a relative humidity of 60%, the bending angle of the actuator changes from 40° to the left to -20° to the right within 2 seconds. This is because in MBC / PI-2, the MXene nanosheets have excellent photothermal effects and the mixing ratio of MXene and BCNF is optimal.

[0055] The stability of the repeated response of the MBC / PI-2 actuator at a light intensity of 25 mW / cm 2 is as follows. As shown, the performance of the actuator hardly changes under multiple repeated responses. Due to the large differences in the wet expansion and thermal expansion properties of the MBC film and the PI film, a dual-mechanism synergistic effect is generated, and the resulting actuator can produce reversible bouncing bending deformation under low-power near-infrared light driving. Figure 6 ​

Claims

1. A double-layer MXene film multiple stimulus-responsive actuator, characterized in that, The multi-stimulus responsive actuator is composed of an active layer of MXene / bacterial cellulose BC composite film and an inert layer with a large coefficient of thermal expansion, enabling it to bend and deform under humidity and photothermal stimuli.

2. The actuator according to claim 1, characterized in that, The MXene in the MXene / bacterial cellulose BC composite membrane is Ti3C2T x .

3. The actuator according to claim 1, characterized in that, The MXene / bacterial cellulose BC composite film is prepared by mixing MXene colloid and bacterial cellulose dispersion, modifying with dopamine, and vacuum filtration to form a film.

4. The actuator according to claim 1, wherein The mass ratio of MXene to bacterial cellulose BC is 0.3 - 1.5:

1.

5. The actuator according to claim 1, characterized in that, An inert layer with a relatively large coefficient of thermal expansion refers to an inert layer with a coefficient of thermal expansion of (30 - 300)×10- 6 / °C.

6. The actuator according to claim 1, characterized in that, The inert layer is any one of polyimide tape and polyester tape.

7. The actuator according to claim 1, characterized in that, The thickness of the MXene / bacterial cellulose BC composite film is 15 - 20 μm; the thickness of the inert layer is 30 - 40 μm.

8. The actuator according to claim 1, characterized in that, When the multi-stimulus responsive actuator is stimulated by humidity, it bends from the side of the active layer to the side of the inert layer; when stimulated by near-infrared photothermal, it bends from the side of the inert layer to the side of the active layer.

9. A method for preparing an actuator according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1), homogenize and defoam the bacterial cellulose fibrils to obtain a uniform bacterial cellulose dispersion; Step 2), add MXene colloid to the bacterial cellulose dispersion and mix, add dopamine for modification, and use Tris to adjust the pH to 7.5 - 8.5; Step 3), stir the mixture in Step 2 at room temperature for 4 hours, and perform vacuum filtration using a filter membrane; Step 4), obtain the MXene / bacterial cellulose BC composite film after drying; Step 5), bond the MXene / bacterial cellulose BC composite film obtained in Step 4 with the inert layer, and cut it into the target shape to obtain the actuator.

10. Use of an actuator as claimed in any one of claims 1 - 8 as an intelligent driver.

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