Sa / rgo hollow double-helix hydrogel fiber and preparation method and application thereof

Abstract

The present application belongs to the technical field of hydrogel fibers, and relates to a SA / RGO hollow double-helix hydrogel fiber as well as a preparation method and application thereof. The present application adopts sodium alginate and reduced graphene oxide as main raw materials, mixes the sodium alginate and the reduced graphene oxide (RGO) to prepare a sodium alginate / reduced graphene oxide (SA / RGO) hydrogel fiber with a hollow structure, so that the required water amount of the hydrogel fiber is reduced and high-efficiency response is achieved when the hydrogel fiber is stimulated by an external stimulus, then the spiral structure is controlled and shaping is realized through twisting and re-spiraling, and energy storage is simultaneously performed. In addition, the prepared SA / RGO hydrogel fiber has good cycle stability in application. The SA / RGO hollow hydrogel fiber provided by the present application can be applied to smart windows as a flexible driver, or applied to seawater desalination, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel fiber technology, and relates to an SA / RGO hollow double helix hydrogel fiber, its preparation method and application, especially to an SA / RGO hollow double helix hydrogel fiber with dual light / water response, its preparation method and its application in flexible actuators. Background Technology

[0002] Hydrogels are a class of highly elastic and flexible materials that change volume upon exposure to humidity, exhibiting expansion or contraction. Simultaneously, hydrogels can convert external stimuli into energy, which can then be transformed into hydrogel actuators capable of mechanical motion. Compared to traditional mechanical actuators, hydrogel actuators can more easily achieve complex mechanical deformations by utilizing responses to external stimuli. Therefore, in recent years, they have been widely used as flexible actuators in artificial muscles, biomimetic robots, and many other flexible actuation materials. The structures of these materials can be broadly classified into three categories: one-dimensional fibers, two-dimensional membranes, and three-dimensional gels. Among these, fiber actuators have attracted researchers' attention due to their actuation behavior similar to that of real muscles. Furthermore, inspired by the movement of plant tendrils, twisting fiber polymer chains in a specific direction to create a helical structure further enhances their performance. Currently, environmentally responsive fibers with helical structures have become a hot topic in flexible actuator research.

[0003] However, the high standardization requirements of helical geometry coupled with a lack of corresponding control technologies, along with the demanding spinning technology, limit the responsiveness of fiber actuators to complex environments. Therefore, developing a highly efficient fiber actuator capable of easily controlling the helical structure and exploring its potential applications is crucial. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an SA / RGO hollow double helix hydrogel fiber, its preparation method and application. The SA / RGO hollow double helix hydrogel fiber has high efficiency and dual light / water response characteristics, which can overcome the problems of limited control over the helical geometry in the manufacturing method of helical microfibers, high requirements for spinning technology, and insufficient response of fiber actuators to complex environments in application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing SA / RGO hollow double helix hydrogel fibers includes the following steps:

[0007] S1. Reduced graphene oxide powder is added to deionized water and ultrasonically pulverized to obtain a reduced graphene oxide aqueous solution. Then, sodium alginate (SA) aqueous solution is added to the reduced graphene oxide (RGO) aqueous solution and allowed to stand at room temperature for 12 hours to prepare a uniformly mixed SA / RGO spinning solution.

[0008] S2. Hollow SA / RGO hydrogel fibers can be obtained by wet spinning using a coaxial needle, CaCl2 aqueous solution as the core solution, and the SA / RGO spinning solution as the shell solution.

[0009] S3. Fix both ends of the hollow SA / RGO hydrogel fiber on a twisting machine and twist it in the Z-twist direction. Then, automatically twist it through U-shaped folding to obtain a spiral structure hydrogel fiber.

[0010] S4. The double helix hydrogel fiber is wound onto a thin rod in the S-twist or Z-twist direction, and the two ends are fixed. After the winding structure is stable, it is removed to obtain a spring-shaped SZ-twist or ZZ-twist double helix hydrogel fiber. The double helix hydrogel fiber is a light / water dual-responsive SA / RGO hollow double helix hydrogel fiber.

[0011] Furthermore, the fixed time is 30 minutes.

[0012] Furthermore, in step S1, the concentration of the reduced graphene oxide aqueous solution is 0.2wt%~0.3wt%, and the concentration of the sodium alginate aqueous solution is 4.0wt%.

[0013] Further, in step S2, the wet spinning process is specifically operated as follows: using a 30 G / 21 G coaxial needle, a 4 wt% CaCl2 aqueous solution as the core solution, and SA / RGO spinning solution as the shell solution, the SA / RGO spinning solution is injected into a 10 ml syringe, and the injection pump squeezes the SA / RGO spinning solution from the coaxial needle into the coagulation bath at a rate of 50 μl / min through the catheter. Finally, the fibers solidified in the coagulation bath are collected to obtain hollow SA / RGO hydrogel fibers.

[0014] Furthermore, in step 3, the twist rate is 5000-6000 rpm and the diameter is 70-80 μm.

[0015] Furthermore, the diameter of the helical hydrogel fiber is 100~110μm.

[0016] The present invention also provides an SA / RGO hollow double helix hydrogel fiber prepared by the above preparation method.

[0017] The present invention also provides an application of the above-mentioned SA / RGO hollow double helix hydrogel fiber in a flexible actuator.

[0018] Compared with existing technologies, this invention uses sodium alginate and reduced graphene oxide (RGO) as the main raw materials. Sodium alginate and RGO are mixed to form sodium alginate / reduced graphene oxide (SA / RGO) hydrogel fibers with a hollow structure. This reduces the amount of water required for the hydrogel fibers to respond to external stimuli and achieves a highly efficient response. The helical structure is then controlled and shaped by twisting and rewinding, while simultaneously storing energy. Furthermore, the resulting SA / RGO double-helix hydrogel fibers exhibit good cycle stability during application. Specific technical effects are manifested in the following aspects:

[0019] (1) Fully utilize the excellent thermal conductivity of RGO to improve the photothermal response of SA / RGO double helix hydrogel fibers. The hollow structure of SA / RGO hydrogel fibers can accelerate the fiber expansion or contraction process and improve the water response efficiency of the fibers.

[0020] (2) The method of twisting SA / RGO hydrogel fibers and then spiraling them is simple and effective. The spiral structure can be controlled by controlling the twist and twist direction, which saves the preparation cost. Attached Figure Description

[0021] Figure 1 A schematic diagram of the preparation process of SA / RGO hollow double helix hydrogel fibers;

[0022] Figure 2 (a) is a scanning electron microscope (SEM) image of the SA / RGO hydrogel fiber prepared by wet spinning according to the present invention; (b) is a scanning electron microscope (SEM) image of the cross section of the hollow SA / RGO hydrogel fiber prepared by wet spinning according to the present invention; (c) is a SEM image of the SA / RGO hydrogel fiber after twisting treatment; (d) is a SEM image of the SA / RGO double helix hydrogel fiber after twisting and then twisting into a helical structure by U-folding.

[0023] Figure 3 (a) is a schematic diagram of SZ twisted SA / RGO hydrogel fiber obtained by S-type winding; (b) shows the elongation and contraction of the fiber actuator under light and water response of S-type winding; (c) is a schematic diagram of ZZ twisted SA / RGO hydrogel fiber obtained by Z-type winding; (d) shows the elongation and contraction of the fiber actuator under light and water response of Z-type winding.

[0024] Figure 4 This is a shrinkage cycle diagram of the SA / RGO hollow double helix hydrogel fiber prepared in Example 3 of the present invention under different water response cycles;

[0025] Figure 5 The shrinkage cycle diagram of the SA / RGO hollow double helix hydrogel fiber prepared in Example 3 of the present invention under different light conditions and different number of cycles;

[0026] Figure 6 The infrared absorption spectra of the SA double helix hydrogel fiber obtained in Example 4 and the SA / RGO hollow double helix hydrogel fiber prepared in Example 3 are shown.

[0027] Figure 7 The graphs show the light absorption rates of the SA double helix hydrogel fiber obtained in Example 4 and the SA / RGO hollow double helix hydrogel fiber prepared in Example 3 at different wavelengths. Detailed Implementation

[0028] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0029] 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 equivalent alterations or modifications also fall within the scope defined by the claims of this application.

[0030] Figure 1 The preparation process of the SA / RGO hollow double helix hydrogel fiber of the present invention is shown. First, hydrogel fibers are obtained by wet spinning, and then twisted, U-folded and wound to obtain spring-shaped SA / RGO hollow double helix hydrogel fibers.

[0031] Example 1

[0032] Step 1: Weigh 0.040 g of RGO powder and add it to 20 ml of deionized water to prepare RGO aqueous solution. Weigh 0.417 g of sodium alginate powder and add it to 10 ml of deionized water to prepare SA aqueous solution. Add the RGO aqueous solution to the SA aqueous solution while stirring, and then sonicate for 1 h to make RGO evenly dispersed in the solution. Then let it stand for 12 h to remove small air bubbles in the mixed solution to obtain SA / RGO spinning solution.

[0033] Step 2: Weigh 2.083 g of anhydrous calcium chloride and add it to 50 ml of deionized water. Stir thoroughly to dissolve the anhydrous calcium chloride in the deionized water to obtain an anhydrous calcium chloride aqueous solution. Using a 30 G / 21 G coaxial needle, with the above CaCl2 aqueous solution as the core solution and SA / RGO spinning solution as the shell solution, inject the SA / RGO spinning solution into a 10 ml syringe. The syringe pump extrudes the spinning solution from the coaxial needle into the coagulation bath at a rate of 50 µl / min through the catheter. Finally, collect the fibers that have solidified in the coagulation bath to obtain hollow SA / RGO hydrogel fibers.

[0034] Step 3: Take a SA / RGO hydrogel fiber, fix both ends to a twisting machine, and twist it in the Z-twist direction at 6000 rpm to a diameter of 70 μm. Then, automatically twist the twisted fiber into a helical structure with a diameter of 100 μm by U-folding.

[0035] Step 4: Wind the double helix hydrogel fiber from Step 3 onto a thin rod in an S-twist or Z-twist direction, fix both ends for 30 minutes, and remove it after the winding structure has stabilized to obtain a spring-shaped SZ-twist or ZZ-twist SA / RGO hollow double helix hydrogel fiber.

[0036] Example 2

[0037] Step 1: Weigh 0.050 g of RGO powder and add it to 20 ml of deionized water to prepare RGO aqueous solution. Weigh 0.417 g of sodium alginate powder and add it to 10 ml of deionized water to prepare SA aqueous solution. Add the RGO aqueous solution to the SA aqueous solution while stirring, and then sonicate for 1 h to make RGO evenly dispersed in the solution. Then let it stand for 12 h to remove small air bubbles in the mixed solution to obtain SA / RGO spinning solution.

[0038] Step 2: Weigh 2.083 g of anhydrous calcium chloride and add it to 50 ml of deionized water. Stir thoroughly to dissolve the anhydrous calcium chloride in the deionized water to obtain an anhydrous calcium chloride aqueous solution. Using a 30 G / 21 G coaxial needle, with the above CaCl2 aqueous solution as the core solution and SA / RGO spinning solution as the shell solution, inject the SA / RGO spinning solution into a 10 ml syringe. The syringe pump extrudes the spinning solution from the coaxial needle into the coagulation bath at a rate of 50 μl / min through the catheter. Finally, collect the fibers that have solidified in the coagulation bath to obtain hollow SA / RGO hydrogel fibers.

[0039] Step 3: Take a SA / RGO hydrogel fiber, fix both ends to a twisting machine, and twist it in the Z-twist direction at 6000 rpm to a diameter of 75 μm. Then, automatically twist the twisted fiber into a helical structure with a diameter of 105 μm by U-folding.

[0040] Step 4: Wind the double helix hydrogel fiber from Step 3 onto a thin rod in an S-twist or Z-twist direction, fix both ends for 30 minutes, and remove it after the winding structure has stabilized to obtain a spring-shaped SZ-twist or ZZ-twist SA / RGO hollow double helix hydrogel fiber.

[0041] Example 3

[0042] Step 1: Weigh 0.060 g of RGO powder and add it to 20 ml of deionized water to prepare RGO aqueous solution. Weigh 0.417 g of sodium alginate powder and add it to 10 ml of deionized water to prepare SA aqueous solution. Add the RGO aqueous solution to the SA aqueous solution while stirring, and then sonicate for 1 h to make RGO evenly dispersed in the solution. Then let it stand for 12 h to remove small air bubbles in the mixed solution to obtain SA / RGO spinning solution.

[0043] Step 2: Weigh 2.083 g of anhydrous calcium chloride and add it to 50 ml of deionized water. Stir thoroughly to dissolve the anhydrous calcium chloride in the deionized water to obtain an anhydrous calcium chloride aqueous solution. Using a 30 G / 21 G coaxial needle, with the above CaCl2 aqueous solution as the core solution and SA / RGO spinning solution as the shell solution, inject the SA / RGO spinning solution into a 10 ml syringe. The syringe pump extrudes the spinning solution from the coaxial needle into the coagulation bath at a rate of 50 μl / min through the catheter. Finally, collect the fibers that have solidified in the coagulation bath to obtain hollow SA / RGO hydrogel fibers. Figure 2 (a) is a scanning electron microscope image of the SA / RGO hydrogel fiber prepared by the above wet spinning method. It can be seen from the image that the surface of the hydrogel fiber is covered with a layer of RGO particles, which are uneven and relatively rough. Figure 2 (b) is a scanning electron microscope image of the cross-section of SA / RGO hydrogel fiber. It can be seen from the image that the obtained fiber has a hollow structure.

[0044] Step 3: Take a SA / RGO hydrogel fiber, fix both ends to a twisting machine, and twist it in the Z-twist direction at 6000 rpm with a diameter of 80 μm. Figure 2 (c) is a SEM image of the twisted SA / RGO hydrogel fibers. It can be seen that after twisting, the diameter of a single hydrogel fiber decreases and a significant twist angle is observed on the surface. The twisted fibers are then automatically twisted into a helical structure with a diameter of 110 μm through U-folding. Figure 2 As shown in (d), a single twisted fiber will tend to untwist due to mechanical instability when its two ends are not fixed. When it is folded in a U-shape, it will automatically twist together to form a spiral structure in order to overcome internal stress.

[0045] Step 4: Wind the double helix hydrogel fiber from Step 3 onto a thin rod in an S-twist or Z-twist direction, fix both ends for 30 minutes, and remove it after the winding structure has stabilized to obtain a spring-shaped SZ-twist or ZZ-twist SA / RGO hollow double helix hydrogel fiber. Figure 3 (a) and (c) show the response mechanisms of SZ-twist and ZZ-twist double-helix hydrogel fibers, while (b) and (d) show the dual water and heat response processes of the double-helix hydrogel fibers. As can be seen from the figures, under simulated light source irradiation, the length of the S-twist double-helix fiber increases significantly, while the length of the Z-twist double-helix fiber decreases. After the light source is turned off and the temperature drops, both fibers slowly recover. Under the action of water mist, the S-twist double-helix fiber gradually shortens, while the Z-twist double-helix fiber gradually lengthens; when the humidifier is turned off, both fibers return to their original state. This demonstrates that the SA / RGO double-helix hydrogel fiber actuator prepared in this invention exhibits excellent dual light and water response performance. Furthermore, Figure 4 , 5 The figure shows the light / water response shrinkage cycle diagram of SA / RGO hydrogel fiber. It can be seen from the figure that SA / RGO hydrogel fiber can still maintain its original properties after multiple light and water cycles, which demonstrates its good cycle stability.

[0046] Example 4 (Comparative Example)

[0047] Step 1: Weigh 0.417 g of sodium alginate powder and add it to 10 ml of deionized water to prepare SA aqueous solution. Stir ultrasonically for 1 h to evenly disperse the sodium alginate powder in the deionized water. Then let it stand for 12 h to remove small air bubbles in the mixed solution to obtain SA spinning solution.

[0048] Step 2: Weigh 2.083 g of anhydrous calcium chloride and add it to 50 ml of deionized water. Stir thoroughly to dissolve the anhydrous calcium chloride in the deionized water to obtain an anhydrous calcium chloride aqueous solution. Using a 30 G / 21 G coaxial needle, with the above CaCl2 aqueous solution as the core solution and SA spinning solution as the shell solution, inject the SA spinning solution into a 10 ml syringe. The syringe pump extrudes the spinning solution from the coaxial needle into the coagulation bath at a rate of 50 μl / min through the catheter. Finally, collect the fibers that have solidified in the coagulation bath to obtain hollow SA hydrogel fibers.

[0049] Step 3: Take a single SA hydrogel fiber and fix both ends to a twisting machine. Twist the fiber in a Z-twist direction at 6000 rpm to a diameter of 80 μm. Then, automatically twist the twisted fiber into a helical structure with a diameter of 110 μm by U-folding.

[0050] Step 4: Wind the double helix hydrogel fiber from Step 3 onto a thin rod in an S-twist or twist direction, fix both ends for 30 minutes, and remove it after the winding structure has stabilized to obtain a spring-shaped SZ-twist or ZZ-twist SA double helix hydrogel fiber.

[0051] Figure 6 The figures show the infrared absorption spectra of the SA double-helix hydrogel fiber obtained in Example 4 and the SA / RGO hollow double-helix hydrogel fiber prepared in Example 3 of this application. As can be seen from the figures, the absorption peak of C-OH is at 1405 cm⁻¹. -1 The slender, narrow peaks at 3200 cm -1 -3400 cm -1 The broad peak at 1024 cm⁻¹, the latter being the hydroxyl peak after hydrogen bond association, is wider due to the influence of hydrogen bonding; -1 The absorption peak at [value] is attributed to the asymmetric stretching vibration of COC and is a characteristic absorption peak for identifying ester groups; while the absorption peak at 1595 cm⁻¹ is [value]. -1 The absorption peak at this point is generated by the CC stretching vibration. After adding RGO, the absorption peak here becomes stronger and sharper, and the presence of RGO in SA / RGO is proved by comparison. Figure 7 The graphs show the light absorption rate curves of the SA double-helix hydrogel fiber obtained in Example 4 and the SA / RGO hollow double-helix hydrogel fiber prepared in Example 3 at different wavelengths. By comparing the SA light absorption curves with the SA / RGO light absorption curves, it can be clearly seen that the SA light absorption rate is extremely unstable and generally low, while the SA / RGO light absorption rate is not only much higher than that of SA but also remains relatively stable at over 80%, essentially achieving full absorption of the background light source. This is because the addition of RGO makes the originally smooth and transparent SA surface rough and opaque. When light shines on the SA / RGO surface, the high porosity of RGO gives it a strong ability to capture light, greatly reducing the light transmittance and reflectance. This results in an average light absorption rate of up to 89.8% for SA / RGO across the entire spectrum, promoting the photoresponse performance of the SA / RGO hollow double-helix hydrogel fiber.

Claims

1. A method for preparing SA / RGO hollow double helix hydrogel fibers, characterized in that, Includes the following steps: S1. Reduced graphene oxide powder is added to deionized water and ultrasonically pulverized to obtain a reduced graphene oxide aqueous solution. Then, sodium alginate aqueous solution is added to the reduced graphene oxide aqueous solution and allowed to stand at room temperature for 12 hours to prepare a uniformly mixed SA / RGO spinning solution. S2. Hollow SA / RGO hydrogel fibers can be obtained by wet spinning using a coaxial needle, CaCl2 aqueous solution as the core solution, and the SA / RGO spinning solution as the shell solution. S3. Fix both ends of the hollow SA / RGO hydrogel fiber on a twisting machine and twist it in the Z-twist direction. Then, automatically twist it through U-shaped folding to obtain a double helix structure hydrogel fiber. S4. The double helix hydrogel fiber is wound onto a thin rod in the S-twist or Z-twist direction, and the two ends are fixed. After the winding structure is stable, it is removed to obtain a spring-shaped SZ-twist or ZZ-twist double helix hydrogel fiber. The double helix hydrogel fiber is a light / water dual-responsive SA / RGO hollow double helix hydrogel fiber.

2. The preparation method according to claim 1, characterized in that, In step S1, the concentration of the reduced graphene oxide aqueous solution is 0.2wt%~0.3wt%, and the concentration of the sodium alginate aqueous solution is 4.0wt%.

3. The preparation method according to claim 1, characterized in that, In step S2, the wet spinning process is specifically operated as follows: using a 30 G / 21 G coaxial needle, a 4 wt% CaCl2 aqueous solution as the core solution, and SA / RGO spinning solution as the shell solution, the SA / RGO spinning solution is injected into a 10 ml syringe. The syringe pump extrudes the SA / RGO spinning solution from the coaxial needle into the coagulation bath at a rate of 50 μl / min through a catheter. Finally, the fibers solidified in the coagulation bath are collected to obtain hollow SA / RGO hydrogel fibers.

4. The preparation method according to claim 1, characterized in that, In step 3, the fibers are twisted in the Z-twist direction at a twist rate of 5000-6000 rpm, resulting in a fiber diameter of 70-80 μm.

5. SA / RGO hollow double helix hydrogel fibers prepared by the preparation method according to any one of claims 1-4.

6. The application of the SA / RGO hollow double helix hydrogel fiber as described in claim 5 in a flexible actuator.

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