High-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel as well as preparation method and application thereof
By constructing a high-toughness conductive polyvinyl alcohol/polyacrylamide/carboxymethyl cellulose hydrogel with a multi-interpenetrating network structure, the problem of insufficient toughness and fatigue resistance of existing hydrogels is solved, enabling the application of high-performance flexible sensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF JINAN
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-10
AI Technical Summary
Existing polyvinyl alcohol/polyacrylamide conductive hydrogels suffer from insufficient toughness and poor fatigue resistance, resulting in unsatisfactory sensing performance.
A multi-layer interpenetrating network structure was constructed by physical crosslinking of polyvinyl alcohol microcrystals, chemical crosslinking of polyacrylamide, and coordination crosslinking of carboxymethyl cellulose and metal ions. The ionic bonds formed by the carboxyl groups in carboxymethyl cellulose and metal ions are used as "sacrificial bonds" to break preferentially during deformation, while the covalent network of polyacrylamide maintains the integrity of the material.
It achieves high tensile strength, high elongation at break and excellent fatigue resistance, solving the problem of insufficient mechanical properties of traditional hydrogels. At the same time, it has good electrical conductivity and is suitable for flexible sensor applications.
Smart Images
Figure CN121824992A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of hydrogel preparation, and particularly relates to a high-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel and a preparation method and application thereof. BACKGROUND
[0002] In recent years, wearable smart devices have been widely used in human motion detection, human health detection, electronic skin, super capacitors and soft touch panels. Wearable sensors have attracted much attention in recent years due to their light weight, high flexibility and easy stretching. Smart wearable devices have improved the requirements for mechanical deformation of sensor substrates, such as simple bending, stretching, twisting, etc. Traditional rigid sensors are generally composed of an elastic substrate and a conductive filler, which may cause inaccurate and untimely signal transmission during deformation, and due to the limited stretching performance, the deformation recovery speed is slow and the deformation recovery efficiency is low.
[0003] Therefore, flexible design of wearable sensors is the mainstream development direction today. A large number of research results have proved the feasibility of plastic substrates, paper-based, textile-based materials as flexible substrates applied in wearable sensors, but there are still a series of problems, such as large difference in mechanical properties and human skin, affecting the wearing comfort of the sensor and the accuracy of human motion detection. In addition, the above flexible materials also have poor adhesion, cannot closely adhere to the human surface, and are easy to fall off. With the continuous deepening of the research on high polymer materials, it is found that hydrogel materials have a wide application prospect in the field of flexible sensors due to their good flexibility, elasticity and plasticity. As a three-dimensional network structure material composed of polymer chains through cross-linking and entanglement, hydrogel has a loose porous structure, and often contains a large amount of water. This water content similar to human tissue gives it good biocompatibility, and the flexibility of hydrogel can minimize the mechanical mismatch with biological tissues, which is ideal for wearable flexible sensors. However, the mechanical properties and conductive properties are not coordinated, and the fatigue resistance is insufficient, which makes it difficult to meet the long-term monitoring requirements, and seriously hinders its application in building high-performance flexible electronic devices.
[0004] Currently, a new type of double network hydrogel has been reported using polyvinyl alcohol and polyacrylamide, in which polyvinyl alcohol is cross-linked by reversible covalent interaction to form the first heavy network, and polyacrylamide is cross-linked by chemical cross-linking to form the second heavy network. The polyvinyl alcohol network has excellent ductility and flexibility, while the polyacrylamide provides higher strength and stability, and this double network structure greatly enhances the mechanical properties of the hydrogel. However, the traditional polyvinyl alcohol / polyacrylamide double network hydrogel still has problems such as insufficient toughness, poor fatigue resistance, and the like, resulting in unsatisfactory sensing performance. Therefore, reasonable design of polyvinyl alcohol / polyacrylamide-based conductive hydrogel is an important strategy for constructing high-performance flexible strain sensors. SUMMARY
[0005] In order to solve the above technical problems, the purpose of the present application is to provide a high-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel and its preparation method and application, in order to solve the problem of insufficient mechanical properties such as insufficient toughness and poor fatigue resistance of the existing polyvinyl alcohol / polyacrylamide conductive hydrogel.
[0006] A method for preparing a high-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel, comprising the following steps: Step one, polyvinyl alcohol is added to deionized water, and is dissolved by stirring under water bath heating to obtain a polyvinyl alcohol solution with a mass fraction of 2wt%-5wt%; Step two, carboxymethyl cellulose is added to the polyvinyl alcohol solution obtained in step one and is fully stirred to obtain a polyvinyl alcohol / carboxymethyl cellulose mixed solution; Step three, acrylamide is added to the mixed solution obtained in step two and is fully stirred to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose mixed solution; Step four, conductive metal salt, cross-linking agent and initiator are added to the mixed solution obtained in step three, and are fully stirred and placed in a mold, and are polymerized and molded at high temperature, and after cooling to room temperature, are placed in a refrigerator and frozen and then thawed to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel.
[0007] Further, the heating temperature in step one is 80℃-95℃.
[0008] Further, the content of carboxymethyl cellulose in the mixed solution in step two is 0.01g / ml-0.03g / ml, and the stirring time is 3h-5h.
[0009] Further, the content of acrylamide in the mixed solution in step three is 0.1g / ml-0.3g / ml.
[0010] Further, the concentration of metal ions in the mixed solution in step four is 0.05 mol / L-0.5 mol / L, the mass of the crosslinking agent is 0.15 %-0.2 % of the mass of acrylamide, and the mass of the initiator is 0.8 %-1 % of the mass of acrylamide.
[0011] Further, according to the preparation method in claim 1, the crosslinking agent is N,N'-methylenebisacrylamide (MBA) or N-hydroxymethyl acrylamide.
[0012] Further, according to the preparation method in claim 1, the initiator is potassium persulfate (KPS) or ammonium persulfate (APS).
[0013] Further, the high-temperature polymerization temperature in step four is 40 ℃-60 ℃, and the holding time is 3 h-5 h.
[0014] Further, the freezing condition in step four is freezing at a temperature of-30 ℃ to-10 ℃ for 20 h, and then thawing at room temperature.
[0015] The application further provides a high-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel prepared based on the above preparation method. 3 The ion conductivity is 1-3 S / m, the tensile strength is 90-160 kPa, the toughness is 0.15-0.6 MJ / m
[0016] The application further provides that the high-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel can be applied to monitoring human motion signals as a flexible strain sensor.
[0017] The application has the following beneficial effects: 1. The application constructs a multiple interpenetrating network structure composed of physical crosslinking of polyvinyl alcohol microcrystals, chemical crosslinking of polyacrylamide, and coordination crosslinking of carboxymethyl cellulose and metal ions.
[0018] 2. The application benefits from the ionic bonds formed between the carboxyl groups in the carboxymethyl cellulose and the metal ions as "sacrificial bonds", which can effectively dissipate a large amount of energy when deformation occurs, while the polyacrylamide covalent network maintains the integrity of the material.
[0019] 3. The polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel prepared in the present application has good electric conductivity and can be well applied to flexible sensors. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 The electron microscope (SEM) image of the hydrogel prepared for Example 1 of the present application.
[0021] Figure 2 The impedance spectrum of the hydrogel in Example 1 of the present application.
[0022] Figure 3 The tensile stress-strain curve of the hydrogel in Example 1 of the present application.
[0023] Figure 4 The toughness and Young's modulus graph of the hydrogel in Example 1 of the present application.
[0024] Figure 5 The relative resistance change curve of the hydrogel sensor in Example 1 of the present application during the cyclic bending process at the finger part. DETAILED DESCRIPTION
[0025] Example 1 Polyvinyl alcohol was added to deionized water, and dissolved by stirring under water bath heating to obtain a polyvinyl alcohol solution with a mass fraction of 2.5 wt%; 0.015 g / ml of carboxymethyl cellulose powder was added to the polyvinyl alcohol solution, and stirred for 5 h to obtain a polyvinyl alcohol / carboxymethyl cellulose mixed solution; 0.3 g / ml of acrylamide was added to the solution and stirred for 10 min to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose; calcium chloride powder with a calcium ion concentration of 0.3 mol / L was added to the solution, followed by 0.17 % of crosslinking agent N,N'-methylene bisacrylamide and 0.84 % of initiator potassium persulfate based on the mass of acrylamide, and the solution was fully stirred and placed in a mold, polymerized and shaped at 50 °C for 4 h, cooled to room temperature, and then placed in a refrigerator at -20 °C for 20 h and then thawed to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel. The target product polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel was prepared based on the above preparation method, which has a porous and dense three-dimensional network structure( Figure 1 ), an ionic conductivity of 2.236 S / m( Figure 2 ), a tensile strength of 142 MPa( Figure 3 ), a toughness and Young's modulus of 0.585 MJ / m 3 and 14.63 kPa( Figure 4 ).
[0026] Application of polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel in flexible strain sensor: The prepared flexible sensor was fixed on different parts of the volunteer's body to demonstrate its practical application in wearable health monitoring. As shown in Fig. 6, finger joint bending monitoring: the sensor was longitudinally attached to the metacarpophalangeal joint of the index finger. As the finger was bent at different angles, the sensor was stretched, and its resistance changed regularly, stably outputting a resistance response signal synchronized with the movement cycle. Figure 5
[0027] Example 2 Polyvinyl alcohol was added to deionized water, and the solution was dissolved by stirring under water bath heating to obtain a polyvinyl alcohol solution with a mass fraction of 2 wt%; 0.01 g / ml of carboxymethyl cellulose powder was added to the polyvinyl alcohol solution, and the mixture was stirred for 4 h to obtain a polyvinyl alcohol / carboxymethyl cellulose mixed solution; 0.1 g / ml of acrylamide was added to the solution and stirred for 10 min to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose solution; 0.05 mol / L of zinc chloride powder was added to the solution, followed by 0.15% of crosslinking agent N,N'-methylene bisacrylamide and 0.8% of initiator ammonium persulfate based on the mass of acrylamide, and the mixture was stirred and then poured into a mold, and polymerized at 40 °C for 3 h. After cooling to room temperature, the mixture was placed in a refrigerator at -10 °C for 20 h and then thawed to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel. Based on the above preparation method, the target product polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel was prepared, which had a porous and dense three-dimensional network structure, an ionic conductivity of 1 S / m, a tensile strength of 90 kPa, and a toughness and Young's modulus of 0.15 MJ / m 3 and 10 kPa.
[0028] Example 3 The polyvinyl alcohol was added to deionized water, and stirred and dissolved under water bath heating to obtain a polyvinyl alcohol solution with a mass fraction of 5 wt%; 0.03 g / ml of carboxymethyl cellulose powder was added to the polyvinyl alcohol solution, and stirred for 4 h to obtain a polyvinyl alcohol / carboxymethyl cellulose mixed solution; 0.3 g / ml of acrylamide was added to the solution and stirred for 10 min to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose; magnesium ions with a concentration of 0.5 mol / L were added to the solution in the form of magnesium chloride powder, and then 0.2% of a crosslinking agent N-hydroxymethyl acrylamide and 1% of an initiator ammonium persulfate based on the mass of the acrylamide were added, and the solution was fully stirred and placed in a mold, and then polymerized and formed at 60°C for 5 h, and after cooling to room temperature, the solution was placed in a refrigerator and frozen at -30°C for 20 h, and then thawed to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel. The target product polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel was prepared based on the above preparation method, and had a porous and dense three-dimensional network structure, an ionic conductivity of 3 S / m, a tensile strength of 160 kPa, and a toughness and Young's modulus of 0.6 MJ / m 3 and 15 kPa.
[0029] The above examples are merely examples for clearly illustrating the present application, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. All the embodiments do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.
Claims
1. A process for the preparation of a high-toughness electrically conductive polyvinyl alcohol / polyacrylamide / carboxymethylcellulose hydrogel, characterized in that, The method comprises the following steps: Step one, polyvinyl alcohol is added to deionized water, and stirred and dissolved under heating to obtain a polyvinyl alcohol solution; Step two, carboxymethyl cellulose is added to the polyvinyl alcohol solution obtained in step one, and stirred to obtain a polyvinyl alcohol / carboxymethyl cellulose mixed solution; Step three, acrylamide is added to the mixed solution obtained in step two, and stirred to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose mixed solution; Step four, a conductive metal salt, a crosslinking agent and an initiator are added to the mixed solution obtained in step three, and stirred, and then placed in a mold, polymerized and molded at high temperature, and then cooled to room temperature, and then placed in a refrigerator and frozen, and then thawed to obtain a polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel.
2. The production method according to claim 1, characterized by, In step one, the heating temperature is 80-95 ℃, and the mass fraction of the polyvinyl alcohol solution is 2 wt%-5 wt%.
3. The preparation method according to claim 1, characterized in that, In step two, the content of carboxymethyl cellulose in the mixed solution is 0.01 g / ml-0.03 g / ml, and the stirring time is 3 h-5 h.
4. The method of claim 1, wherein, In step three, the content of acrylamide in the mixed solution is 0.1 g / ml-0.3 g / ml, and the stirring time is 10-20 min.
5. The preparation method according to claim 1, characterized in that, In step four, the metal ion concentration in the mixed solution is 0.05 mol / L-0.5 mol / L, the mass of the crosslinking agent is 0.15%-0.2% of the mass of acrylamide, and the mass of the initiator is 0.8%-1% of the mass of acrylamide.
6. The method of claim 1, wherein, The conductive metal salt is calcium chloride, zinc chloride or magnesium chloride.
7. The preparation method according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide (MBA) or N-hydroxymethyl acrylamide.
8. The method of claim 1, wherein, The initiator is potassium persulfate (KPS) or ammonium persulfate (APS).
9. The method of claim 1, wherein, In step four, the high-temperature polymerization temperature is 50 ℃-70 ℃, and the holding time is 3 h-5 h.
10. The method of claim 1, wherein, In step four, the freezing condition is that the temperature is-30 ℃--10 ℃, and the freezing time is 10-30 h, and then the sample is thawed at room temperature.
11. A high toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel prepared by the method of any one of claims 1 to 10, characterized in that, The hydrogel has a multiple interpenetrating network structure composed of physical cross-linking of polyvinyl alcohol microcrystals, chemical cross-linking of polyacrylamide and coordination cross-linking of carboxymethyl cellulose and metal ions. The unique structure design realizes the entanglement and synergistic effect between different polymer chains. The obtained polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel has a porous and dense three-dimensional network structure, an ionic conductivity of 1-3 S / m, a tensile strength of 90-160 kPa, a toughness of 0.15-0.6 MJ / m 3 2, and a Young's modulus of 10-15 kPa.
12. The high-toughness conductive polyvinyl alcohol / polyacrylamide / carboxymethyl cellulose hydrogel according to claim 11 can be applied to monitoring human motion signals as a flexible strain sensor.