Electrochromic artificial muscle operating in air and preparation and application thereof

Abstract

This invention relates to an electrochromic artificial muscle that operates in air, its preparation, and its application. The core layer is made of carbon nanotube yarn, and a vanadium oxide nanowire layer is uniformly wrapped around the core layer. Polymethyl methacrylate (PMMA) serves as the electrolyte and a protective layer, encapsulating the core-skin composite yarn structure. This invention solves the problems of electrochemical artificial muscles being limited to electrolytic cell manipulation, the unstable connection between the electrolyte layer and the active layer during stretching, and the single-function problem of electrochemical artificial muscles, thus facilitating the preparation of multifunctional electrochemical artificial muscles.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of artificial muscle, in particular to an electrochromic artificial muscle operating in air and its preparation and application. BACKGROUND

[0002] In recent years, artificial muscles with high flexibility and high elasticity have been widely used in advanced fields such as biomedical devices and bionic robots. Traditional artificial muscles cannot meet people's higher demands due to poor controllability, high driving voltage and other reasons. Electrochemical artificial muscles based on ion-polymer-composite materials are widely used in artificial muscles due to their light weight, simple manufacturing, low cost and low driving voltage. However, in practical applications, it is often necessary to output large energy and be able to independently and stably operate to cause high actuation response. How to realize the stretch cycle stability and multifunctionality of the existing artificial muscle has become the focus of a series of researches.

[0003] Stretchable electrolyte as an important component of flexible devices plays an indispensable role in many fields such as fashion and camouflage. For traditional electrochemical artificial muscle devices, the contact between electrolyte and active electrode during stretching has always been a difficulty. Seeking a new electrolyte preparation method is one of the effective ways to solve this problem. Therefore, it has high research significance and commercial value to prepare a stretchable electrolyte by a new method of hot pouring and rapid cooling. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an electrochromic artificial muscle operating in air and its preparation and application. The present application solves the problem that electrochemical artificial muscle is limited to electrolytic cell operation, realizes the operation of electrochemical artificial muscle in air, solves the problem of unstable connection between electrolyte layer and active layer of electrochemical artificial muscle during stretching, realizes the long-term stability of electrochemical artificial muscle operation, and solves the problem of single functionality of electrochemical artificial muscle, which is beneficial to the preparation of multifunctional electrochemical artificial muscle.

[0005] The preparation method of the electrochromic artificial muscle of the present application comprises:

[0006] (1) mixing 1-butyl-3-methyl imidazole tetrafluoroborate BMIM:BF4 and a solvent to obtain an electrolyte, then dissolving polymethyl methacrylate PMMA in the electrolyte to obtain a gel electrolyte;

[0007] (2) constructing a composite electrochromic yarn with a skin-core structure, wet twisting to obtain an electrochromic artificial muscle yarn with a spiral structure; and (3) hot pouring the gel electrolyte onto the electrochromic artificial muscle yarn with a spiral structure, cooling to obtain the electrochromic artificial muscle.

[0008] Preferably, the solvent in step (1) is propylene carbonate PC; the concentration of the electrolyte is 0.8-1.2 M.

[0009] Preferably, the mass fraction of polymethyl methacrylate PMMA in the gel electrolyte in step (1) is 5-20 wt%.

[0010] Further preferably, the mass fraction of polymethyl methacrylate PMMA in the gel electrolyte is 12-17 wt%.

[0011] Preferably, the composite electrochromic yarn with a core-sheath structure in step (2) is a carbon tube yarn as a core layer, vanadium oxide nanowires as a sheath layer, and wrapped on the core layer.

[0012] Preferably, the composite electrochromic yarn with a core-sheath structure in step (2) is specifically: slowly adding V2O5NWs into an aqueous solution containing ions to form a flocculation state, and using a carbon tube yarn to wrap a layer of V2O5NWs to construct a composite electrochromic yarn with a core-sheath structure.

[0013] The aqueous solution containing ions refers to an aqueous solution with a certain ion concentration; the winding is wet winding.

[0014] Preferably, the humidity of the wet twisting in step (2) is 45-80% RH.

[0015] Preferably, the electrochromic artificial muscle yarn with a spiral structure in step (3) is arranged in a parallel structure or a ring structure in sequence.

[0016] Preferably, the temperature of the hot pouring in step (3) is 80-120℃; the cooling temperature is 10-40℃.

[0017] Further preferably, the temperature of the hot pouring is 90-110℃; the cooling temperature is 15-35℃.

[0018] The step (3) is specifically: the gel electrolyte needs to be formed in a flowing state in an environment of 90-110℃, and the prepared electrochromic artificial muscle yarn with a spiral structure is arranged in a certain order, and then the gel electrolyte is quickly hot-poured and cooled to construct an electrochromic artificial muscle.

[0019] Further, the gel electrolyte is placed in an oven at 90-110℃, and first, the electrochromic artificial muscle yarn with a spiral structure is arranged in a parallel structure or a ring structure in sequence. Then the gel electrolyte is quickly hot-poured and cooled to construct an electrochromic artificial muscle.

[0020] The electrochromic artificial muscle yarn containing a spiral structure in step (3) includes: one CNT spiral yarn and one or more V2O5NWs / CNT electrochromic artificial muscle yarns.

[0021] Further, the gel electrolyte is hot-cast onto a CNT spiral yarn and one or more V2O5NWs / CNT electrochromic artificial muscle yarns arranged in a predetermined order, and then cooled to obtain electrochromic artificial muscle.

[0022] An electrochromic artificial muscle prepared by the method of the present invention.

[0023] The electrochromic artificial muscle is composed of carbon nanotube yarn as the core layer, vanadium oxide nanowires as the skin layer uniformly wrapped around the core layer, and polymethyl methacrylate as the electrolyte and protective layer wrapping the core-skin composite yarn structure.

[0024] The present invention relates to the application of the electrochromic artificial muscle in the fields of sensing, wearable devices, smart healthcare, camouflage, or military applications.

[0025] The electrochromic artificial muscle of this invention comprises: carbon nanotube yarn as the core layer, vanadium oxide nanowires as the skin layer uniformly wrapped around the core layer, and polymethyl methacrylate as the electrolyte and protective layer wrapping the core-skin composite yarn. The method includes: dispersing vanadium oxide nanowires to form a vanadium oxide nanowire dispersion; using a wet winding method to tightly bond the skin layer and core layer to obtain a core-skin electrochromic yarn; then, using a wet twisting method to twist the core-skin electrochromic yarn into a helical structure for the electrochromic artificial muscle yarn; finally, using a hot casting and rapid cooling method to construct an electrochromic artificial muscle capable of stable operation in air.

[0026] Advantages

[0027] (1) This invention uses wet winding and wet twisting techniques to prepare tightly entangled electrochromic artificial muscle yarns. The electrochromic artificial muscle yarns with a spiral structure arranged in a certain order are constructed into multifunctional artificial muscles through a hot casting and rapid cooling electrolyte molding method. The resulting electrochromic artificial muscles have excellent color-changing and actuation synchronous dual response performance, making them widely applicable in fields such as sensing, wearables, smart medical care, camouflage, and even military industry. (2) The method of this invention is simple and suitable for mass production. It realizes the air operation stability and multifunctionality of electrochromic artificial muscles, expanding their application in multiple fields. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation process of the electrochromic artificial muscle spiral yarn in this invention;

[0029] Figure 2 Image 'ac' is a scanning electron microscope image of the surface of the electrochromic artificial muscle yarn prepared in Example 1.

[0030] Figure 3 The image shows the performance test results of the electrochromic artificial muscle yarn prepared in Example 1.

[0031] Figure 4 This is a schematic diagram of the electrochromic artificial muscle prepared in Example 1;

[0032] Figure 5 The image shows the ultraviolet-visible spectrum of the electrochromic artificial muscle prepared in Example 1.

[0033] Figure 6 The graph shows the performance test results of the electrochromic artificial muscle contraction stroke prepared in Example 1.

[0034] Figure 7 The image shows a digital photograph of the color change and actuation of the electrochromic artificial muscle prepared in Example 1.

[0035] Figure 8 This is a schematic diagram of the annularly arranged electrochromic artificial muscle with a special device structure prepared in Example 1;

[0036] Figure 9 This is a photograph of the annularly arranged electrochromic artificial muscle with a special device structure prepared in Example 1.

[0037] Figure 10 The annularly arranged electrochromic artificial muscle with a special device structure prepared in Example 1 is applied to the color change of artificial prostheses and to drive digital photography. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims. Details of the reagents used in the experiment are as follows: V₂O₅ (99.95%) was purchased from Sigma-Aldrich; propylene carbonate (PC, 99%), polymethyl methacrylate (PMMA) granules, and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM:BF4) were purchased from China Pharmaceutical Chemical Reagent Co., Ltd. Carbon nanotube yarn was purchased from Chengdu Organic Chemical Co., Ltd. All materials were used without further purification.

[0039] Example 1

[0040] 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM:BF4) was dissolved in propylene carbonate (PC) to prepare a BMIM:BF4 / PC electrolyte of a certain concentration (1M). Polymethyl methacrylate (PMMA) was dissolved in the electrolyte to obtain a BMIM:BF4 / PC / PMMA gel electrolyte, wherein the mass fraction of PMMA was 15wt%. Next, V2O5NWs / CNT electrochromic artificial muscle fibers were prepared by wet winding. Then, V2O5NWs / CNT electrochromic artificial muscle yarn with a helical structure was prepared by wet twisting at a humidity of 65% RH. Finally, the gel electrolyte was allowed to flow at 100°C and hot-cast onto the electrochromic artificial muscle yarn. The ambient temperature was then rapidly cooled to 25°C, thus constructing an air-controllable electrochromic artificial muscle.

[0041] like Figure 1 A schematic diagram of the preparation process for electrochromic artificial muscle spiral yarn;

[0042] Figure 2 A scanning electron microscope image of the surface of the electrochromic artificial muscle spiral yarn prepared;

[0043] Figure 3 The image shows the performance test results of the prepared electrochromic artificial muscle yarn.

[0044] Figure 4 A schematic diagram of an electrochromic artificial muscle prepared by hot casting and rapid cooling of a PMMA gel electrolyte with a mass fraction of 15 wt%. The electrochromic artificial muscle is made by hot casting of a PMMA electrolyte, consisting of a CNT spiral yarn and a V2O5NWs / CNT electrochromic artificial muscle yarn arranged in parallel.

[0045] Figure 5 The UV-Vis spectrum of the prepared electrochromic artificial muscle at ±4V.

[0046] Figure 6 The graph shows the contractile stroke performance of the prepared electrochromic artificial muscle under a +4V voltage.

[0047] Figure 7 Digital photographs showing the color change and actuation of the prepared electrochromic artificial muscle at ±4V voltage;

[0048] Figure 8 The diagram shows the annular electrochromic artificial muscle with a special device structure. The electrochromic artificial muscle is made by arranging one CNT spiral yarn and six V2O5NWs / CNT electrochromic artificial muscle yarns in a ring and hot-casting PMMA electrolyte.

[0049] Figure 9 The image shows the actual product of the annularly arranged electrochromic artificial muscle with a special device structure. The electrochromic artificial muscle is made by arranging one CNT spiral yarn and six V2O5NWs / CNT electrochromic artificial muscle yarns in a ring, and then hot-casting PMMA electrolyte.

[0050] Figure 10 The resulting electrochromic artificial muscles, with a special device structure arranged in a ring, are intended for use in color-changing artificial limbs and driving digital photographs.

[0051] Example 2

[0052] 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM:BF4) was dissolved in propylene carbonate (PC) to prepare a BMIM:BF4 / PC electrolyte of a certain concentration (0.8M). Polymethyl methacrylate (PMMA) was dissolved in the electrolyte to obtain a BMIM:BF4 / PC / PMMA gel electrolyte, wherein the mass fraction of PMMA was 12wt%. Next, V2O5NWs / CNT electrochromic artificial muscle fibers were prepared by wet winding. Then, V2O5NWs / CNT electrochromic artificial muscle yarn with a helical structure was prepared by wet twisting at a humidity of 50% RH. Finally, the gel electrolyte was allowed to flow at 90°C and hot-cast onto the electrochromic artificial muscle yarn. The ambient temperature was then rapidly cooled to 25°C, thus constructing an air-controllable electrochromic artificial muscle.

[0053] Compared to Example 1, the electrochemical reaction rate slows down and the current decreases due to the reduced electrolyte concentration; the mass fraction of PMMA in the electrolyte decreases, reducing the strength of the gel electrolyte and resulting in poorer cycle stability during electrochemical testing; simultaneously, the reduced humidity during wet twisting leads to a decrease in the bonding force of the core-shell structure, and the reduced melting temperature of the electrolyte leads to poorer electrolyte fluidity and poorer contact between the active electrode and the electrolyte; however, the prepared air-operable electrochromic artificial muscle still meets the requirements of good contact between the electrolyte and the active electrode, good cycle stability, and multifunctionality during artificial muscle operation.

[0054] Example 3

[0055] 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM:BF4) was dissolved in propylene carbonate (PC) to prepare a BMIM:BF4 / PC electrolyte of a certain concentration (1.2M). Polymethyl methacrylate (PMMA) was dissolved in the electrolyte to obtain a BMIM:BF4 / PC / PMMA gel electrolyte (PMMA mass fraction 17wt%). Next, V2O5NWs / CNT electrochromic artificial muscle fibers were prepared using a wet winding method. Then, V2O5NWs / CNT electrochromic artificial muscle yarn with a helical structure was prepared using a wet twisting method at a humidity of 80% RH. Finally, the gel electrolyte was allowed to flow at 110°C and hot-cast onto the electrochromic artificial muscle yarn. The ambient temperature was then rapidly cooled to 35°C, thus constructing an air-controllable electrochromic artificial muscle. Compared to Example 1, the increased electrolyte concentration leads to a faster electrochemical reaction rate and a larger current, resulting in poorer cycle stability. The increased mass fraction of PMMA in the electrolyte reduces the fluidity of the gel electrolyte, leading to decreased cycle stability and driving performance during electrochemical testing. Simultaneously, the increased melting and cooling temperatures of the electrolyte slow down the molding speed and reduce the contact between the active electrode and the electrolyte. However, the prepared air-operable electrochromic artificial muscle still meets the requirements of good contact between the electrolyte and the active electrode, good cycle stability, and multifunctionality during artificial muscle operation.

[0056] Example 4

[0057] 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM:BF4) was dissolved in propylene carbonate (PC) to prepare a BMIM:BF4 / PC electrolyte of a certain concentration (0.8M). Polymethyl methacrylate (PMMA) was dissolved in the electrolyte to obtain a BMIM:BF4 / PC / PMMA gel electrolyte (PMMA mass fraction 17wt%). Next, V2O5NWs / CNT electrochromic artificial muscle fibers were prepared using a wet winding method. Then, V2O5NWs / CNT electrochromic artificial muscle yarn with a helical structure was prepared using a wet twisting method at a humidity of 50% RH. Finally, the gel electrolyte was allowed to flow at 110°C and hot-cast onto the electrochromic artificial muscle yarn. The ambient temperature was then rapidly cooled to 15°C, thus constructing an air-controllable electrochromic artificial muscle. Compared to Example 1, the electrochemical reaction rate slows down and the current decreases due to the reduced electrolyte concentration; the increased mass fraction of the electrolyte PMMA leads to poorer fluidity of the gel electrolyte, resulting in decreased cycle stability and driving performance during electrochemical testing; the increased electrolyte melting temperature slows down the electrolyte molding speed and reduces the contact between the active electrode and the electrolyte; and the reduced humidity during wet twisting reduces the bonding force of the core-shell structure. However, the prepared air-operable electrochromic artificial muscle still meets the requirements of good contact between the electrolyte and the active electrode, good cycle stability, and multifunctionality during artificial muscle operation.

[0058] Example 5

[0059] 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM:BF4) was dissolved in propylene carbonate (PC) to prepare a BMIM:BF4 / PC electrolyte of a certain concentration (1.2M). Polymethyl methacrylate (PMMA) was dissolved in the electrolyte to obtain a BMIM:BF4 / PC / PMMA gel electrolyte (PMMA mass fraction 12wt%). Next, V2O5NWs / CNT electrochromic artificial muscle fibers were prepared using a wet winding method. Then, V2O5NWs / CNT electrochromic artificial muscle yarn with a helical structure was prepared using a wet twisting method at a humidity of 80% RH. Finally, the gel electrolyte was allowed to flow at 90°C and hot-cast onto the electrochromic artificial muscle yarn. The ambient temperature was then rapidly cooled to 35°C, thus constructing an air-controllable electrochromic artificial muscle. Compared to Example 1, the increased electrolyte concentration leads to a faster electrochemical reaction rate and a larger current, resulting in poorer cycle stability. The decreased PMMA mass fraction in the electrolyte reduces the strength of the gel electrolyte, further degrading cycle stability during electrochemical testing. Simultaneously, the decreased melting temperature and increased cooling temperature of the electrolyte reduce its fluidity and slow its molding speed, leading to poorer contact between the active electrode and the electrolyte. However, the prepared air-operable electrochromic artificial muscle still meets the requirements of good contact between the electrolyte and the active electrode, good cycle stability, and multifunctionality during artificial muscle operation.

Claims

1. A method for preparing electrochromic artificial muscle, comprising: Step (1) Mix 1-butyl-3-methylimidazolium tetrafluoroborate and solvent to obtain an electrolyte, and then dissolve polymethyl methacrylate (PMMA) in the electrolyte to obtain a gel electrolyte; Step (2) Construct a composite electrochromic yarn with a core-sheath structure, wet twist it to obtain a spiral electrochromic artificial muscle yarn, namely V2O5 NWs / CNT electrochromic artificial muscle yarn. The specific method for constructing the core-sheath structure of the composite electrochromic yarn is as follows: V2O5 NWs are added to an aqueous solution containing ions to form a flocculated state, and carbon nanotube (CNT) yarn is used to wind the V2O5 NWs to construct the core-sheath structure of the composite electrochromic yarn. Step (3) The gel electrolyte is hot-cast onto the electrochromic artificial muscle yarn containing a spiral structure and cooled to obtain electrochromic artificial muscle.

2. The preparation method according to claim 1, characterized in that, In step (1), the solvent is propylene carbonate (PC); the concentration of the electrolyte is 0.8-1.2 M; and the mass fraction of polymethyl methacrylate (PMMA) in the gel electrolyte is 5-20 wt%.

3. The preparation method according to claim 1, characterized in that, In step (2), the composite electrochromic yarn with a core-shell structure consists of carbon nanotube (CNT) yarn as the core layer and vanadium oxide nanowires (V2O5 NWs) as the sheath layer wrapped around the core layer.

4. The preparation method according to claim 1, characterized in that, The humidity of the wet twisting process in step (2) is 45-80% RH.

5. The preparation method according to claim 1, characterized in that, In step (3), the helical electrochromic artificial muscle yarns are arranged in parallel or ring-shaped order.

6. The preparation method according to claim 1, characterized in that, The electrochromic artificial muscle yarn containing a spiral structure in step (3) includes: one CNT spiral yarn and one or more V2O5 NWs / CNT electrochromic artificial muscle yarns.

7. The preparation method according to claim 1, characterized in that, The temperature for hot casting in step (3) is 80-120℃; the cooling temperature is 10-40℃.

8. An electrochromic artificial muscle prepared by the method of claim 1.

9. The application of the electrochromic artificial muscle of claim 8 in the fields of sensing, wearable devices, smart healthcare, camouflage, and military industry.

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