Spider-silk-like cellulose gel fibers and methods of making and using the same

Abstract

The application discloses a kind of imitative spider silk cellulose gel fibers and its preparation method and application, method includes: using DMAc to activate cellulose powder and obtain activated cellulose powder;Activated cellulose powder is added in DMAc / LiCl solvent and dissolved, and obtain cellulose solution;Using microfluidic equipment, cellulose solution is injected into deionized water and solidified, and washing is obtained cellulose gel fiber;Cellulose gel fiber is soaked in PVA-PAA precursor liquid, and then placed under ultraviolet lamp irradiation, then freeze and thaw, and obtain cellulose / PVA / PAA hydrogel fiber;Cellulose / PVA / PAA hydrogel fiber is pre-stretched, then soaked in CuSO4 solution, and then washed with deionized water after soaking, and obtain imitative spider silk cellulose gel fiber.The imitative spider silk cellulose gel fiber provided by the application has strong toughness, flexible conductivity and environmental resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer flexible conductive materials technology, and specifically relates to a spider silk-inspired cellulose gel fiber, its preparation method and application. Background Technology

[0002] Hydrogel fibers, characterized by their three-dimensional cross-linked polymer network structure and high water content, have attracted widespread attention as fundamental building blocks for next-generation flexible and bio-integrated electronic devices. Their inherent flexibility, ionic conductivity, and ability to be woven into fabrics give them unique advantages in wearable strain sensors, implantable bioelectronic devices, soft robots, and tissue engineering scaffolds. Unlike traditional rigid conductors or hydrophobic elastomers, hydrogel fibers maintain continuous ionic conductivity pathways even during large deformations, enabling seamless integration with dynamic biological tissues and accurately converting physiological mechanical signals into electrical signals. This synergistic effect of mechanical flexibility and ionic functionality makes hydrogel fibers a key interface material in human-computer interaction, continuous health monitoring, and regenerative medicine. However, most hydrogel fibers typically possess only a relatively simple network structure and low internal cross-linking density, resulting in fragile mechanical properties that fail to meet practical application requirements. The high water content that imparts flexibility and conductivity to hydrogels also plasticizes the polymer network, leading to weak intermolecular forces, low strength, and poor toughness. Furthermore, this water-rich environment makes it prone to water loss under dry conditions and freezing at low temperatures, resulting in severe losses of elasticity, conductivity, and structural integrity. These problems are particularly pronounced in fiber structures, as their ultra-high specific surface area accelerates unfavorable environmental exchange processes. Therefore, achieving both high mechanical robustness (including strength, toughness, and fatigue resistance) and environmental stability in continuously fabricated hydrogel fiber systems remains a core challenge in the field of advanced functional materials.

[0003] To overcome these limitations, extensive research has been conducted on the microstructure design and fabrication of hydrogel fibers. Traditional hydrogel fibers are typically prepared through simple extrusion or molding, resulting in low tensile strength and brittle fracture. To improve their mechanical properties, researchers have drawn on design strategies from composite materials and dual-network hydrogels. For example, introducing nanofillers such as cellulose nanofibers (CNFs) can achieve reinforcement; embedding CNFs into a polyvinyl alcohol matrix plasticized with deep eutectic solvent (DES) can produce eutectic gel fibers with a tensile strength of 37.3 MPa and an electrical conductivity of 0.543 S / m. However, while these methods can improve strength, they often fail to simultaneously meet the requirements of high toughness (i.e., the ability to absorb energy before fracture) and large elongation. Furthermore, environmental stability remains an issue. Traditional hydrogels are prone to freezing near 0°C, and water evaporates rapidly in low-humidity environments, severely limiting their application range. Although lowering the freezing point with high-concentration salts or using ionic liquids as a continuous phase can improve environmental adaptability, these typically introduce new problems such as poor biocompatibility, liquid leakage, or decreased mechanical properties. Therefore, there is an urgent need for a holistic design strategy that can synergistically optimize the hierarchical structure of fibers from the molecular to the macroscopic scale, so as to decouple and synergistically improve mechanical properties and environmental stability. Summary of the Invention

[0004] Objective: In order to overcome the shortcomings of the existing technology, the present invention provides a spider silk-like cellulose gel fiber, its preparation method and application.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows: In a first aspect, a method for preparing spider silk-inspired cellulose gel fibers is provided, comprising: Cellulose powder was activated using N,N-dimethylacetamide (DMAc) to obtain activated cellulose powder. The activated cellulose powder was dissolved in DMAc / LiCl solvent to obtain a cellulose solution; A cellulose solution was injected into deionized water using a microfluidic device to coagulate, and then washed to obtain cellulose gel fibers. Cellulose gel fibers were soaked in a polyvinyl alcohol (PVA)-polyacrylic acid (PAA) precursor solution and then irradiated under a UV lamp. After irradiation, the cellulose gel fibers were frozen and thawed to obtain cellulose / PVA / PAA hydrogel fibers. Fiber cellulose / PVA / PAA hydrogel fibers are stretched to obtain pre-stretched fiber cellulose / PVA / PAA hydrogel fibers. Pre-stretched cellulose / PVA / PAA hydrogel fibers were immersed in CuSO4 solution and then rinsed with deionized water to obtain spider silk-like cellulose gel fibers.

[0006] The spider silk-inspired cellulose gel fiber (SCAF) provided by the present invention has a multi-level structure that simulates the polymer chain orientation and metal coordination crosslinking mechanism of natural spider silk. This allows the fiber to effectively disperse stress when subjected to tension, thereby maintaining flexibility while possessing excellent tensile strength and overcoming the defects of traditional cellulose materials being brittle.

[0007] In some embodiments, the activation treatment of cellulose powder using DMAc solvent to obtain activated cellulose powder includes: The filter paper is crushed to obtain cellulose powder. The cellulose powder is then added to DMAc at a certain mass ratio and stirred continuously at room temperature. During the crushing process, an intermittent operation mode can be adopted (such as pausing once every 1 to 2 minutes) to avoid overheating of the equipment and thermal degradation of the sample. After stirring, the mixture is centrifuged at 8000 to 10000 rpm for 10 to 15 minutes to remove the supernatant and retain the precipitated cellulose powder. To further remove residual solvent, the centrifugation and washing steps can be repeated 1 to 2 times as needed. The settled cellulose powder was placed in an oven for drying. After drying, it was taken out and cooled to room temperature to obtain activated cellulose powder.

[0008] In some embodiments, the method for preparing the DMAc / LiCl solvent includes: First add DMAc to the round-bottom flask, then stir and add 8-10 wt% LiCl; Turn on the heating device and continuously heat and stir the solution in the round-bottom flask. DMAc evaporates and condenses and refluxes in the condenser until the solution in the round-bottom flask changes from turbid to transparent. Stop heating and allow the solution in the round-bottom flask to cool to room temperature to obtain the DMAc / LiCl solvent.

[0009] In some embodiments, dissolving the activated cellulose powder in a DMAc / LiCl solvent to obtain a cellulose solution includes: Add activated cellulose powder to DMAc / LiCl solvent and stir under nitrogen protection at room temperature or 80-100°C until the solution becomes transparent or translucent to obtain a cellulose solution. If dissolution is incomplete, a small amount of DMAc can be added or the dissolution time can be extended (usually 2-12 hours).

[0010] In some embodiments, the step of injecting a cellulose solution into deionized water using a microfluidic device for coagulation and washing to obtain cellulose gel fibers includes: The defoamed cellulose solution was loaded into a microfluidic device, and the outlet of the microfluidic device was submerged 1-2 cm below the surface of the deionized water. Set a suitable extrusion flow rate, start the microfluidic device, extrude the cellulose solution, and solidify it into fibers in deionized water; The coagulated fibers were collected and dispersed in deionized water for washing. The mixture was allowed to stand at room temperature for washing, with the deionized water changed periodically. Washing continued for 3-5 days until no white precipitate was detected in the washed deionized water using AgNO3, or until the conductivity of the washed deionized water was confirmed to be <5 μS / cm using a conductivity meter. The purified cellulose gel fibers can be stored in deionized water (for short-term storage at 4℃) or subjected to further post-processing.

[0011] In some embodiments, the step of soaking the cellulose gel fibers in a PVA-PAA precursor solution and then irradiating them under a UV lamp; after irradiation, freezing and thawing the cellulose gel fibers to obtain cellulose / PVA / PAA hydrogel fibers includes: PVA is added to deionized water, heated to 90-95℃ and stirred until the solution is clear to obtain a PVA solution; After the PVA solution cools to room temperature, add acrylic acid, crosslinking agent and photoinitiator and stir thoroughly to obtain a PVA-PAA precursor solution with bubbles; place the PVA-PAA precursor solution with bubbles in a vacuum drying oven to degas or let it stand until the bubbles are eliminated to obtain the PVA-PAA precursor solution. The cellulose gel fibers were thoroughly soaked in the PVA-PAA precursor solution. After soaking, the cellulose gel fibers were removed and placed under a UV lamp to initiate acrylic acid polymerization. After irradiation, the cellulose gel fibers are frozen and then thawed at room temperature. The freezing and thawing process is repeated 1 to 5 times to obtain cellulose / PVA / PAA hydrogel fibers.

[0012] In some embodiments, stretching the cellulose / PVA / PAA hydrogel fibers to obtain pre-stretched cellulose / PVA / PAA hydrogel fibers includes: Cellulose / PVA / PAA hydrogel fibers are stretched to 50% strain at a constant rate and held at 50% strain for a period of time to orient and stabilize the polymer chains along the stretching direction, thus obtaining pre-stretched cellulose / PVA / PAA hydrogel fibers.

[0013] In some embodiments, the step of immersing pre-stretched cellulose / PVA / PAA hydrogel fibers in a CuSO4 solution and rinsing them with deionized water to obtain spider silk-like cellulose gel fibers includes: A CuSO4 solution was prepared using a mixture of deionized water and glycerol as a solvent. Pre-stretched cellulose / PVA / PAA hydrogel fibers were immersed in CuSO4 solution and left to stand in the dark to allow the CuSO4 to settle. 2+It diffuses into the interior of cellulose / PVA / PAA hydrogel fibers and forms coordination bonds with carboxyl and hydroxyl groups; After soaking, rinse the surface with deionized water to remove unbonded Cu. 2+ Spider silk-like cellulose gel fibers were obtained.

[0014] In a second aspect, a spider-silk-like cellulose gel fiber prepared according to the method for preparing spider-silk-like cellulose gel fiber according to any one of the first aspects is provided, wherein the spider-silk-like cellulose gel fiber comprises an interpenetrating network structure formed by cellulose, PVA, and PAA, and Cu 2+ The coordination bond structure formed with carboxyl and hydroxyl groups and the stable and fixed orientation of polymer chains.

[0015] Thirdly, the method for preparing spider silk-like cellulose gel fibers as described in any one of the first aspects provides an application of the spider silk-like cellulose gel fibers prepared by the method described in the first aspect in the monitoring of human physiological mechanical signals in flexible electronic devices.

[0016] Beneficial effects: The spider silk-like cellulose gel fiber, its preparation method, and its application provided by this invention have the following advantages: 1. The present invention utilizes cellulose dissolution and regeneration to form an interpenetrating network structure with PVA and PAA, combined with pre-stretched orientation and copper ions (Cu). 2+ Coordination crosslinking was used to prepare SCAF, which has both high strength and high toughness, achieving excellent mechanical properties and flexibility of gel fibers. 2. The SCAF provided by this invention not only possesses the hydrophilicity and biocompatibility of cellulose-based materials, but also endows them with conductivity through the introduction of ion coordination, enabling them to be used as a sensitive element in wearable sensors. At the same time, the fiber forms a stable physical and chemical cross-linked structure during the preparation process, and its structural stability under complex environments (such as different humidity and temperature changes) is enhanced by treatment in a solvent system (a mixture of deionized water and glycerol), exhibiting good environmental tolerance. 3. Optimized activation and dissolution processes (such as the DMAc / LiCl system) were adopted during the preparation process, which effectively improved the solubility and reactivity of cellulose. The regeneration process used deionized water as the coagulation bath and washing medium, avoiding the large-scale use of organic solvents, which is in line with the principles of green chemistry. In addition, by precisely controlling parameters such as extrusion speed, coagulation conditions, stretch ratio and ion crosslinking time, the microstructure and macroscopic properties of the fiber were precisely controlled, ensuring the consistency and repeatability of the product. Attached Figure Description

[0017] Figure 1 This is a SEM image of the spider silk-like cellulose gel fiber according to an embodiment of the present invention; Figure 2The infrared spectrum of the spider silk-like cellulose gel fiber according to an embodiment of the present invention; Figure 3 This is a comparison diagram of the tensile properties of spider silk-inspired cellulose gel fiber and cellulose gel fiber according to an embodiment of the present invention. Figure 4 This is a stretching cycle curve of the spider silk-like cellulose gel fiber according to an embodiment of the present invention; Figure 5 This is a step-like sensing curve of the spider silk-inspired cellulose gel fiber according to an embodiment of the present invention. Figure 6 This is a constant strain sensing cycle curve of the spider silk-inspired cellulose gel fiber according to an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] Example 1: The preparation method of the spider silk-inspired cellulose gel fiber provided in this example includes: Cut the filter paper into small pieces of about 5mm in size to facilitate subsequent pulverization. Then, place the shredded filter paper in a high-speed blender and pulverize it at high speed until you obtain fine cellulose powder with uniform particle size.

[0021] The obtained filter paper powder was slowly added to DMAc at a mass ratio of 1:100 (i.e., 1g of cellulose powder to 100g of DMAc solvent). Continuous stirring was maintained during the addition process to prevent powder agglomeration. Subsequently, the mixture was continuously stirred using a magnetic stirrer at room temperature (approximately 25°C) for 24 hours to ensure sufficient DMAc penetration and pretreatment and activation of the cellulose. After stirring, the mixture was transferred to centrifuge tubes and centrifuged at 8000 rpm for 15 minutes to ensure complete solid-liquid separation. After centrifugation, the supernatant (DMAc solvent) was removed, retaining the settled cellulose powder at the bottom.

[0022] The resulting moistened cellulose powder was transferred to a vacuum oven and dried at 60°C for 24 hours to completely remove residual DMAc solvent. After drying, the sample was removed and cooled to room temperature to obtain activated cellulose powder. The obtained powder was then stored in a desiccator in a sealed container to prevent moisture absorption from affecting subsequent experiments.

[0023] Assemble a standard reflux condenser, including a round-bottom flask, condenser, and thermostatic heating device, ensuring unobstructed circulation of condensate to prevent solvent evaporation loss. Secure the apparatus to a magnetic stirring plate and add an appropriate amount of stir bar for later use.

[0024] Weigh 92g of DMAc into a clean, dry round-bottom flask. Under magnetic stirring, slowly add 8g of LiCl (8wt%) in portions to avoid localized high concentrations that could lead to clumping or uneven dissolution. Continuous stirring should be maintained during the addition process to ensure the LiCl is fully dispersed in the solvent. After all the LiCl has been added, turn on the heating device and heat the solution to 100°C, then stir continuously under reflux. During this process, DMAc continuously evaporates and condenses under the action of the condenser, maintaining a stable solution volume and promoting the complete dissolution of anhydrous LiCl. Reflux stirring should be maintained for 4 hours until the solution changes from cloudy to a slightly yellowish, clear, and transparent solution.

[0025] Stop heating and allow the solution to cool naturally to room temperature to obtain a homogeneous and stable DMAc / LiCl solvent. To avoid moisture absorption, store the obtained solution in a dry environment in a sealed container for subsequent experiments.

[0026] Add approximately 0.75 g of activated cellulose powder to approximately 50 mL of prepared DMAc / LiCl solvent. Under nitrogen protection, mechanically stir at room temperature (avoid vigorous stirring to prevent bubble formation) for 12 hours. Observe the changes in the solution during the dissolution process: the cellulose gradually swells, the viscosity of the system increases, and it eventually becomes a semi-transparent homogeneous cellulose solution.

[0027] The degassed cellulose solution was loaded into a glass syringe and fixed to a syringe pump. A flat-tipped needle was attached to the syringe, and the outlet was submerged 1 cm below the surface of the deionized water coagulation bath. The flow rate was set to 68 mL / min, the syringe pump was started, and the continuous and uniform extrusion of the cellulose solution was observed. The solution initially coagulated in the coagulation bath and was then collected.

[0028] The collected fibers were loosely placed in a large volume of deionized water and washed at room temperature. The deionized water was changed every 12 hours, and the washing was continued for 3 days. The washing water was checked with AgNO3 solution until no white precipitate was found, indicating that the completely purified cellulose gel fibers (CF) were obtained. The purified cellulose gel fibers can be stored in deionized water at 4°C for short-term storage.

[0029] PVA was added to deionized water and heated to 90°C with stirring until it dissolved and became transparent. After the PVA solution was cooled to room temperature, acrylic acid, crosslinking agent and photoinitiator were added. After stirring for 2 hours, the precursor solution with bubbles was placed in a vacuum drying oven to degas for 30 minutes until the bubbles were completely eliminated, thus obtaining the PVA-PAA precursor solution.

[0030] Cellulose gel fibers were immersed in a PVA-PAA precursor solution to allow the precursor solution to enter the structure of the cellulose gel fibers. After 48 hours, the fibers were removed and placed under a UV lamp to initiate acrylic acid polymerization. The fibers were then frozen in a low-temperature environment (-20°C). After the gel was completely frozen, it was removed and placed at room temperature to thaw. The freezing and thawing process was repeated once to obtain cellulose / PVA / PAA hydrogel fibers (CAF1).

[0031] Cellulose / PVA / PAA hydrogel fibers were fixed on a uniaxial stretching machine, and the initial gauge length L0 of the fibers was marked. The fibers were stretched to 1.5L0 (i.e., 50% strain) at a constant rate of 10 mm / min and held at this strain state for 2 hours to allow the polymer chains to orient and stabilize along the stretching direction. The fibers were kept at room temperature during the stretching process to avoid surface drying. Pre-stretched cellulose / PVA / PAA hydrogel fibers were obtained.

[0032] Prepare a 1 mol / L CuSO4 solution using a mixture of deionized water and glycerol in a volume ratio of 1:1. Completely immerse the pre-stretched cellulose / PVA / PAA hydrogel fibers in this solution and allow them to soak in the dark for 48 hours to allow the CuSO4 to fully absorb the solution. 2+ It fully diffuses into the fiber interior and forms coordination bonds with carboxyl and hydroxyl groups. After soaking, remove the fiber and gently rinse the surface with deionized water to remove unbound free Cu. 2+ This yields spider-silk-inspired cellulose gel fibers. These spider-silk-inspired cellulose gel fibers comprise an interpenetrating network structure formed by cellulose, PVA, and PAA, and Cu... 2+ The coordination bond structure formed with carboxyl and hydroxyl groups and the stable and fixed orientation of polymer chains.

[0033] Example 2: The preparation method of the spider silk-like cellulose gel fiber provided in this example includes: The filter paper was cut into small pieces approximately 10mm in size to facilitate subsequent pulverization. The shredded filter paper was then placed in a high-speed blender and pulverized at high speed until a fine cellulose powder with uniform particle size was obtained. The pulverization process was conducted intermittently, pausing every 1 minute to prevent overheating of the equipment and thermal degradation of the sample.

[0034] The obtained filter paper powder was slowly added to DMAc at a mass ratio of 1:100 (i.e., 1g of cellulose powder to 100g of DMAc solvent). Continuous stirring was maintained during the addition process to prevent powder agglomeration. Subsequently, the mixture was continuously stirred using a magnetic stirrer at room temperature (approximately 25°C) for 24 hours to ensure sufficient DMAc penetration and pretreatment and activation of the cellulose. After stirring, the mixture was transferred to centrifuge tubes and centrifuged at 10,000 rpm for 10 minutes to ensure complete solid-liquid separation. After centrifugation, the supernatant (DMAc solvent) was removed, retaining the settled cellulose powder at the bottom. To further remove residual solvent, the centrifugation and washing steps were repeated once.

[0035] The resulting moistened cellulose powder was transferred to a vacuum oven and dried at 60°C for 24 hours to completely remove residual DMAc solvent. After drying, the sample was removed and cooled to room temperature to obtain activated cellulose powder. The obtained powder was then stored in a desiccator in a sealed container to prevent moisture absorption from affecting subsequent experiments.

[0036] Assemble a standard reflux condenser, including a round-bottom flask, condenser, and thermostatic heating device, ensuring unobstructed circulation of condensate to prevent solvent evaporation loss. Secure the apparatus to a magnetic stirring plate and add an appropriate amount of stir bar for later use.

[0037] Weigh 90g of DMAc into a dry, clean round-bottom flask. Under magnetic stirring, slowly add 10g of LiCl (10wt%) in portions to avoid localized high concentrations that could lead to clumping or uneven dissolution. Continuous stirring should be maintained during the addition process to ensure the LiCl is fully dispersed in the solvent. After all the LiCl has been added, turn on the heating device and heat the solution to 120°C, then stir continuously under reflux. During this process, DMAc continuously evaporates and condenses under the action of the condenser, maintaining a stable solution volume and promoting the complete dissolution of anhydrous LiCl. Reflux stirring should be maintained for 3 hours until the solution changes from turbid to a homogeneous, transparent solution.

[0038] Stop heating and allow the solution to cool naturally to room temperature to obtain a homogeneous and stable DMAc / LiCl solvent. To avoid moisture absorption, store the obtained solution in a dry environment in a sealed container for subsequent experiments.

[0039] Add approximately 0.75 g of activated cellulose powder to approximately 100 mL of prepared DMAc / LiCl solvent. Under nitrogen protection, stir magnetically at 80 °C (avoid vigorous stirring to prevent bubble formation) for 2 hours to extend the dissolution time. Observe the changes in the solution during the dissolution process: the cellulose gradually swells, the viscosity of the system increases, and it eventually becomes a transparent homogeneous cellulose solution.

[0040] The degassed cellulose solution was loaded into a glass syringe and fixed to a syringe pump. A flat-tipped needle was attached to the syringe, and the outlet was submerged 2 cm below the surface of the deionized water coagulation bath. The flow rate was set to 68 mL / min, the syringe pump was started, and the continuous and uniform extrusion of the cellulose solution was observed. The solution initially coagulated in the coagulation bath and was then collected.

[0041] The collected fibers were loosely placed in a large volume of deionized water and washed at room temperature. The deionized water was changed every 12 hours, and the washing was repeated for 4 consecutive days. The conductivity was confirmed to be 4 μS / cm using a conductivity meter, indicating that the cellulose gel fibers were completely purified. The purified cellulose gel fibers underwent further post-processing.

[0042] PVA was added to deionized water and heated to 95°C with stirring until it dissolved and became transparent. After the PVA solution was cooled to room temperature, acrylic acid, crosslinking agent and photoinitiator were added. After stirring for 2 hours, the precursor solution with bubbles was allowed to stand for 2 hours until the bubbles were completely eliminated, thus obtaining the PVA-PAA precursor solution.

[0043] Cellulose gel fibers were immersed in a PVA-PAA precursor solution to allow the precursor solution to enter the structure of the cellulose gel fibers. After 48 hours, the fibers were removed and placed under a UV lamp to initiate acrylic acid polymerization. The fibers were then frozen in a low-temperature environment (-20°C). After the gel was completely frozen, it was removed and placed at room temperature to thaw. The freezing and thawing process was repeated 3 times to obtain cellulose / PVA / PAA hydrogel fibers (CAF3).

[0044] Cellulose / PVA / PAA hydrogel fibers were fixed on a manual stretching table, and the initial gauge length L0 of the fibers was marked. The fibers were stretched to 1.5L0 (i.e., 50% strain) at a constant rate of 10 mm / min and held at this strain for 2 hours to allow the polymer chains to orient and stabilize along the stretching direction. The fibers were kept at room temperature during the stretching process to prevent surface drying. Pre-stretched cellulose / PVA / PAA hydrogel fibers were obtained.

[0045] Prepare a 1 mol / L CuSO4 solution using a mixture of deionized water and glycerol in a volume ratio of 1:1. Completely immerse the pre-stretched cellulose / PVA / PAA hydrogel fibers in this solution and allow them to soak in the dark for 48 hours to allow the CuSO4 to fully absorb the solution. 2+ It fully diffuses into the fiber interior and forms coordination bonds with carboxyl and hydroxyl groups. After soaking, remove the fiber and gently rinse the surface with deionized water to remove unbound free Cu. 2+ This yields spider-silk-inspired cellulose gel fibers. These spider-silk-inspired cellulose gel fibers comprise an interpenetrating network structure formed by cellulose, PVA, and PAA, and Cu... 2+The coordination bond structure formed with carboxyl and hydroxyl groups and the stable and fixed orientation of polymer chains.

[0046] Example 3: The preparation method of the spider silk-inspired cellulose gel fiber provided in this example includes: The filter paper was cut into small pieces approximately 8mm in size to facilitate subsequent pulverization. The shredded filter paper was then placed in a high-speed blender and pulverized at high speed until a fine cellulose powder with uniform particle size was obtained. The pulverization process was conducted intermittently, pausing every 2 minutes to prevent overheating of the equipment and thermal degradation of the sample.

[0047] The obtained filter paper powder was slowly added to DMAc at a mass ratio of 1:100 (i.e., 1g of cellulose powder to 100g of DMAc solvent). Continuous stirring was maintained during the addition process to prevent powder agglomeration. Subsequently, the mixture was continuously stirred using a magnetic stirrer at room temperature (approximately 25°C) for 24 hours to ensure sufficient DMAc penetration and pretreatment and activation of the cellulose. After stirring, the mixture was transferred to centrifuge tubes and centrifuged at 9000 rpm for 13 minutes to ensure complete solid-liquid separation. After centrifugation, the supernatant (DMAc solvent) was removed, retaining the settled cellulose powder at the bottom. To further remove residual solvent, the centrifugation and washing steps were repeated twice.

[0048] The resulting moistened cellulose powder was transferred to a vacuum oven and dried at 60°C for 24 hours to completely remove residual DMAc solvent. After drying, the sample was removed and cooled to room temperature to obtain activated cellulose powder. The obtained powder was then stored in a desiccator in a sealed container to prevent moisture absorption from affecting subsequent experiments.

[0049] Assemble a standard reflux condenser, including a round-bottom flask, condenser, and thermostatic heating device, ensuring unobstructed circulation of condensate to prevent solvent evaporation loss. Secure the apparatus to a magnetic stirring plate and add an appropriate amount of stir bar for later use.

[0050] Weigh 92g of DMAc into a dry, clean round-bottom flask. Under magnetic stirring, slowly add 8g of LiCl (8wt%) in batches to avoid localized high concentrations that could lead to clumping or uneven dissolution. Continuous stirring should be maintained during the addition process to ensure the LiCl is fully dispersed in the solvent. After all the LiCl has been added, turn on the heating device and heat the solution to 110°C, then stir continuously under reflux. During this process, DMAc continuously evaporates and condenses under the action of the condenser, maintaining a stable solution volume and promoting the complete dissolution of anhydrous LiCl. Reflux stirring time should be controlled at 2 hours until the solution changes from turbid to a homogeneous, transparent solution.

[0051] Stop heating and allow the solution to cool naturally to room temperature to obtain a homogeneous and stable DMAc / LiCl solvent. To avoid moisture absorption, store the obtained solution in a dry environment in a sealed container for subsequent experiments.

[0052] Add approximately 0.75 g of activated cellulose powder to approximately 75 mL of prepared DMAc / LiCl solvent. Under nitrogen protection, stir magnetically at 100 °C (avoid vigorous stirring to prevent bubble formation), and add a small amount of DMAc. Observe the changes in the solution during the dissolution process: the cellulose gradually swells, the viscosity of the system increases, and it eventually becomes a transparent homogeneous cellulose solution.

[0053] The degassed cellulose solution was loaded into a glass syringe and fixed to a syringe pump. A flat-tipped needle was attached to the syringe, and the outlet was submerged 2 cm below the surface of the deionized water coagulation bath. The flow rate was set to 68 mL / min, the syringe pump was started, and the continuous and uniform extrusion of the cellulose solution was observed. The solution initially coagulated in the coagulation bath and was then collected.

[0054] The collected fibers were loosely placed in a large volume of deionized water and washed at room temperature. The deionized water was changed every 12 hours, and the washing was repeated for 5 consecutive days. The conductivity was confirmed to be 2 μS / cm using a conductivity meter, indicating that completely purified cellulose gel fibers (CF) were obtained. The purified cellulose gel fibers underwent further post-processing.

[0055] PVA was added to deionized water and heated to 95°C with stirring until it dissolved and became transparent. After the PVA solution was cooled to room temperature, acrylic acid, crosslinking agent and photoinitiator were added. After stirring for 2 hours, the precursor solution with bubbles was allowed to stand for 2 hours until the bubbles were completely eliminated, thus obtaining the PVA-PAA precursor solution.

[0056] Cellulose gel fibers were immersed in a PVA-PAA precursor solution to allow the precursor solution to enter the structure of the cellulose gel fibers. After 48 hours, the fibers were removed and placed under a UV lamp to initiate acrylic acid polymerization. The fibers were then frozen in a low-temperature environment (-20°C). After the gel was completely frozen, it was removed and placed at room temperature to thaw. The freezing and thawing process was repeated 5 times to obtain cellulose / PVA / PAA hydrogel fibers (CAF5).

[0057] Cellulose / PVA / PAA hydrogel fibers were fixed on a manual stretching table, and the initial gauge length L0 of the fibers was marked. The fibers were stretched to 1.5L0 (i.e., 50% strain) at a constant rate of 10 mm / min and held at this strain for 2 hours to allow the polymer chains to orient and stabilize along the stretching direction. The fibers were kept at room temperature during the stretching process to prevent surface drying. Pre-stretched cellulose / PVA / PAA hydrogel fibers were obtained.

[0058] Prepare a 1 mol / L CuSO4 solution using a mixture of deionized water and glycerol in a volume ratio of 1:1. Completely immerse the pre-stretched cellulose / PVA / PAA hydrogel fibers in this solution and allow them to soak in the dark for 48 hours to allow the CuSO4 to fully absorb the solution. 2+ It fully diffuses into the fiber interior and forms coordination bonds with carboxyl and hydroxyl groups. After soaking, remove the fiber and gently rinse the surface with deionized water to remove unbound free Cu. 2+ This yields spider silk-inspired cellulose gel fibers (SCAF), whose SEM images are referenced. Figure 1 The spider-silk-inspired cellulose gel fiber comprises an interpenetrating network structure formed by cellulose, PVA, and PAA, and Cu... 2+ The coordination bond structure formed with carboxyl and hydroxyl groups and the stable and fixed orientation of polymer chains.

[0059] like Figure 2 Fourier transform infrared spectra of the spider silk-inspired cellulose gel fibers prepared in Examples 1 and 3 were obtained. The results showed that the infrared spectra of CAF1, CAF5, and SCAF prepared in Example 3 were within the range of 2925 cm⁻¹. -1 A significant peak is observed at 1640 cm⁻¹, corresponding to the CH stretching vibration, indicating the successful introduction of PVA and PAA. In the SCAF spectral curve, the peak at 1640 cm⁻¹ is significant. -1 The decreased intensity of the peak indicates a reduction in water content, suggesting that the water solvent has been partially replaced by glycerol. At 1100 cm⁻¹ -1 The intensity peak at a certain point belongs to the antisymmetric stretching vibration, confirming the successful introduction of CuSO4. These spectral characteristics collectively indicate that a three-dimensional interpenetrating network structure was successfully constructed within the material by introducing different polymers, achieving homogeneous composite at the molecular level.

[0060] Figure 3 The figure shows a comparison of the tensile properties of the cellulose gel fiber (CF) and the spider silk-like cellulose gel fiber prepared in Example 3. As shown in the figure, the maximum tensile stress and strain of the spider silk-like cellulose gel fiber with a multi-network structure are much higher than those of the pure cellulose gel fiber. Its stress is about 70,400% of that of the cellulose gel fiber, its strain is about 400% of that of the cellulose gel fiber, its Young's modulus is about 67,800% of that of the cellulose gel fiber, and its toughness is about 982,500% of that of the cellulose fiber.

[0061] Figure 4The tensile cycling performance curves of SCAF prepared in Example 3 show a significant decrease in stress only after the 10th cycle (from 21.80 MPa to 20.73 MPa) in the 30 consecutive loading and unloading cycles of the SCAF hydrogel fiber. This is mainly attributed to the irreversible damage of some crystalline regions. In subsequent cycles (cycles 20-30), the stress gradually increases from 20.73 MPa to 22.07 MPa, which is attributed to the formation of strain-induced orientation crystals.

[0062] Figure 5 The strain gradient sensing curve for the SCAF prepared in Example 3 shows that the rate of change of resistance (ΔR / R0) of the SCAF increases with the strain gradient, followed by a stable plateau at constant strain. Once the pressure is released, the resistance quickly returns to the initial baseline. The abrupt transition at strain initiation and release indicates rapid response and recovery times. Throughout the process of progressively loading strain (from 0% to 50%) and subsequently unloading to the initial state, the rate of change of resistance exhibits excellent stability at each step.

[0063] Figure 6 The figure shows the cyclic experimental curves of the SCAF constant strain sensor prepared in Example 3. The strain sensor prepared by SCAF maintains a stable rate of change of resistance during 1000 tensile cycles, indicating that SCAF has excellent tensile strain sensing stability.

[0064] Example 4: This example provides an application of spider silk-inspired cellulose gel fiber in the monitoring of human physiological mechanical signals in flexible electronic devices.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing spider silk-inspired cellulose gel fibers, characterized in that, include: Cellulose powder was activated using DMAc to obtain activated cellulose powder. The activated cellulose powder was dissolved in DMAc / LiCl solvent to obtain a cellulose solution; A cellulose solution was injected into deionized water using a microfluidic device to coagulate, and then washed to obtain cellulose gel fibers. Cellulose gel fibers were soaked in PVA-PAA precursor solution and then irradiated under a UV lamp. After irradiation, the cellulose gel fibers were frozen and thawed to obtain cellulose / PVA / PAA hydrogel fibers. Fiber cellulose / PVA / PAA hydrogel fibers are stretched to obtain pre-stretched fiber cellulose / PVA / PAA hydrogel fibers. Pre-stretched cellulose / PVA / PAA hydrogel fibers were immersed in CuSO4 solution and then rinsed with deionized water to obtain spider silk-like cellulose gel fibers.

2. The method for preparing spider silk-like cellulose gel fibers according to claim 1, characterized in that, The activation treatment of cellulose powder using DMAc solvent to obtain activated cellulose powder includes: The filter paper was crushed to obtain cellulose powder. The cellulose powder was added to DMAc and stirred continuously at room temperature. After stirring, the mixture was centrifuged at 8000-10000 rpm for 10-15 min, the supernatant was removed, and the precipitated cellulose powder was retained. The settled cellulose powder was placed in an oven for drying. After drying, it was taken out and cooled to room temperature to obtain activated cellulose powder.

3. The method for preparing spider silk-like cellulose gel fiber according to claim 1, characterized in that, The preparation method of the DMAc / LiCl solvent includes: First add DMAc to the round-bottom flask, then stir and add 8-10 wt% LiCl; Turn on the heating device and continuously heat and stir the solution in the round-bottom flask. DMAc evaporates and condenses and refluxes in the condenser until the solution in the round-bottom flask changes from turbid to transparent. Stop heating and allow the solution in the round-bottom flask to cool to room temperature to obtain the DMAc / LiCl solvent.

4. The method for preparing spider silk-like cellulose gel fiber according to claim 1, characterized in that, The step of dissolving activated cellulose powder in DMAc / LiCl solvent to obtain a cellulose solution includes: Activated cellulose powder is added to DMAc / LiCl solvent and stirred under nitrogen protection at room temperature or 80~100℃ until the solution becomes transparent or translucent, thus obtaining a cellulose solution.

5. The method for preparing spider silk-like cellulose gel fiber according to claim 1, characterized in that, The method of injecting a cellulose solution into deionized water using a microfluidic device for coagulation and washing to obtain cellulose gel fibers includes: The defoamed cellulose solution was loaded into a microfluidic device, and the outlet of the microfluidic device was submerged 1-2 cm below the surface of the deionized water. Set the extrusion flow rate, start the microfluidic device, extrude the cellulose solution, and solidify it into fibers in deionized water; The coagulated fibers are collected and dispersed in deionized water for washing. The water is left to stand at room temperature for washing, and the deionized water is changed regularly. The washing is continued for 3 to 5 days until no white precipitate is detected in the washed deionized water using AgNO3, or the conductivity of the washed deionized water is confirmed to be <5μS / cm using a conductivity meter, thus obtaining cellulose gel fibers.

6. The method for preparing spider silk-like cellulose gel fiber according to claim 1, characterized in that, The process involves soaking cellulose gel fibers in a PVA-PAA precursor solution and then irradiating them under a UV lamp. After irradiation, the cellulose gel fibers are frozen and thawed to obtain cellulose / PVA / PAA hydrogel fibers, comprising: PVA is added to deionized water, heated to 90-95℃ and stirred until the solution is clear to obtain a PVA solution; After the PVA solution cools to room temperature, acrylic acid, crosslinking agent and photoinitiator are added and stirred to dissolve, resulting in a PVA-PAA precursor solution with bubbles. The PVA-PAA precursor solution with bubbles is placed in a vacuum drying oven for degassing or allowed to stand until the bubbles are eliminated, thus obtaining the PVA-PAA precursor solution. Cellulose gel fibers were immersed in PVA-PAA precursor solution; After soaking, the cellulose gel fibers were removed and placed under a UV lamp to initiate acrylic acid polymerization. After irradiation, the cellulose gel fibers are frozen and then thawed at room temperature. The freezing and thawing process is repeated 1 to 5 times to obtain cellulose / PVA / PAA hydrogel fibers.

7. The method for preparing spider silk-like cellulose gel fiber according to claim 1, characterized in that, The stretching of cellulose / PVA / PAA hydrogel fibers to obtain pre-stretched cellulose / PVA / PAA hydrogel fibers includes: Cellulose / PVA / PAA hydrogel fibers are stretched to a strain of 50% and held at that strain to orient and stabilize the polymer chains along the stretching direction, thus obtaining pre-stretched cellulose / PVA / PAA hydrogel fibers.

8. The method for preparing spider silk-like cellulose gel fiber according to claim 1, characterized in that, The process of immersing pre-stretched cellulose / PVA / PAA hydrogel fibers in CuSO4 solution, followed by rinsing with deionized water to obtain spider silk-like cellulose gel fibers includes: A CuSO4 solution was prepared using a mixture of deionized water and glycerol as a solvent. Pre-stretched cellulose / PVA / PAA hydrogel fibers were immersed in CuSO4 solution and left to stand in the dark to allow the CuSO4 to settle. 2+ It diffuses into the interior of cellulose / PVA / PAA hydrogel fibers and forms coordination bonds with carboxyl and hydroxyl groups; After soaking, rinse the surface with deionized water to remove unbonded Cu. 2+ Spider silk-like cellulose gel fibers were obtained.

9. A spider-silk-like cellulose gel fiber prepared by the method according to any one of claims 1 to 8, characterized in that, The spider silk-like cellulose gel fiber contains an interpenetrating network structure formed by cellulose, PVA, and PAA, and Cu... 2+ The coordination bond structure formed with carboxyl and hydroxyl groups and the stable and fixed orientation of polymer chains.

10. The application of the spider silk-like cellulose gel fiber prepared by the method of any one of claims 1 to 8 in the monitoring of human physiological mechanical signals in flexible electronic devices.

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