A design method of multifunctional hydrogel based on rare earth-starch system
By combining rare earth element europium ions, starch, and silver nanowires, a multifunctional hydrogel with excellent mechanical properties and photoelectric sensing function was prepared, which solved the problem of poor mechanical properties of traditional hydrogels and expanded their application range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING UNIV OF SCI & TECH
- Filing Date
- 2024-12-20
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional hydrogels have poor mechanical properties and limited functionality, which restricts their application in biomedicine, sensors and flexible electronics.
By combining rare earth element europium ions with starch and silver nanowires, and adding acrylamide and polyvinyl alcohol, a multifunctional hydrogel with a three-dimensional network structure is formed, which enhances mechanical properties and realizes photoelectric sensing channels.
A hydrogel with a stretching length of up to 13.7 times was prepared, exhibiting good electrical sensing performance and fast response capability, with a sensing sensitivity of 9.02 and a dynamic response time of 52ms, making it suitable for fluorescence sensing and wearable devices.
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Figure CN122255507A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a design method for multifunctional hydrogels based on a rare earth-starch system, belonging to the field of polymer materials. Background Technology
[0002] Hydrogels are polymeric materials with a three-dimensional network structure that can absorb and retain large amounts of water while exhibiting unique flexibility and plasticity. Multifunctional hydrogels combining fluorescence, conductivity, and other functional properties show great potential in fields such as biomedicine, sensors, flexible electronics, and smart materials. However, the preparation of traditional hydrogels typically requires complex chemical modifications or expensive synthetic raw materials, and most suffer from insufficient mechanical strength, unstable conductivity, and limited functionality, which restricts their further widespread application. Therefore, the design and development of hydrogels based on natural polymeric materials has become a research hotspot.
[0003] Starch, as a renewable, low-cost, and easily processed natural polymer material, has attracted much attention due to its abundant sources and environmental friendliness. Starch is classified into amylose and amylopectin based on its structure. During gelatinization, it swells with water molecules, exposing more hydroxyl groups, which interact with the hydroxyl groups in PVA to form hydrogen bonds, enhancing the mechanical properties of the hydrogel. Furthermore, rare earth elements are widely used in optical materials, catalysts, and electronic devices due to their unique optical, electrical, and magnetic properties. In particular, europium ions (Eu3+), as a rare earth element, possess excellent fluorescence properties, making them valuable in optical sensing, bioimaging, and anti-counterfeiting labeling.
[0004] In the development of multifunctional hydrogels, combining starch with rare earth elements not only endows the hydrogels with excellent fluorescence properties, but also achieves a multifunctional synergistic effect by adding other functional components, such as conductive materials. For example, acrylamide can serve as a crosslinking monomer to provide the three-dimensional network structure of the hydrogel; polyvinyl alcohol, due to its flexibility and film-forming properties, can effectively improve the mechanical strength of the hydrogel; silver nanowires (AgNWs), as a highly efficient conductive material, possess excellent electrical conductivity, mechanical flexibility, and optical transparency. Therefore, by combining starch, rare earth ions, and other functional components, multifunctional hydrogels with both fluorescence and conductivity can be designed. Summary of the Invention
[0005] To address the shortcomings of existing rare earth hydrogel technologies, the present invention aims to provide a multifunctional hydrogel with dual sensing channels, while overcoming the poor mechanical properties of traditional small molecule rare earth hydrogels.
[0006] The europium ion-potato starch-silver nanowire-acrylamide hydrogel studied in this invention can achieve a stretching length of up to 13.7 times its own length, while also exhibiting excellent electrical sensing performance. The sensing sensitivity (GF) reaches 9.02, the dynamic response time reaches 52 ms, and the cycling performance is stable. It also possesses good human-computer interaction performance and, in terms of fluorescence sensing, can respond rapidly to the external ionic environment. The significant meaning of this invention lies in solving the problem that most rare-earth luminescent hydrogels have poor mechanical properties and only offer one optical signal sensing method. It prepares a rare-earth-doped hydrogel that meets application requirements and has excellent performance, while also providing technical support for fluorescence sensors and wearable and electronic skin applications, showing broad application prospects.
[0007] To achieve the above objectives, the technical solution of the present invention is as follows.
[0008] A multifunctional hydrogel based on a rare earth-starch system, wherein the hydrogel is formed by deionized water (79.3 wt%), acrylamide (15.8 wt%), wheat starch / potato starch / corn starch (2.3 wt%), polyvinyl alcohol (0.79 wt%), silver nanowires (1.5 wt%), and doped europium ions.
[0009] The present invention discloses a design method for a multifunctional hydrogel based on a rare earth-starch system, the specific steps of which are as follows:
[0010] (1) Dissolve polyvinyl alcohol and wheat starch in deionized water in sequence, heat at 95°C to gelatinize for 1.5 hours, and then mix thoroughly on a magnetic stirrer.
[0011] (2) Add acrylamide and silver nanowires, and stir until no bubbles are generated;
[0012] (3) Add crosslinking agent N,N'-methylenebisacrylamide, catalyst ammonium persulfate and initiator tetramethylethylenediamine and stir until uniform;
[0013] (4) Transfer the solution to a mold and place it in an oven at 50°C for 5 hours to allow it to fully polymerize into a gel;
[0014] (5) Immerse the formed hydrogel in a 0.1 mol / L rare earth solution for 10 min to obtain a multifunctional hydrogel of rare earth-starch system as described in this invention.
[0015] Replace wheat starch with potato starch or corn starch, and repeat steps (1-5).
[0016] Compared with the prior art, the beneficial effects of the present invention are:
[0017] 1. This invention provides a multifunctional hydrogel based on a rare earth-starch system. Compared to the limitation of traditional rare earth hydrogels which only have an optical sensing channel, the multifunctional hydrogel provided by this invention has both photoelectric and optical sensing channels, greatly expanding the application range of rare earth hydrogels. Furthermore, the rare earth hydrogel provided by this invention exhibits excellent ultraviolet photoluminescence properties, can respond to the external ionic environment, and also has excellent conductivity, with a GF reaching 9.02 and a dynamic response time of 52ms. It also has good strain cycle stability and human-computer interaction performance.
[0018] 2. This invention provides a multifunctional hydrogel based on a rare earth-starch system. Compared with traditional rare earth hydrogels based on small molecules, the rare earth hydrogel based on a high molecular weight starch network provides a stronger network and exhibits better mechanical properties, with an elongation of up to 13.7 times its own length. Attached Figure Description
[0019] Figure 1 Tensile curves of three multifunctional hydrogels of rare earth-starch system: (a) wheat starch; (b) potato starch; (c) corn starch.
[0020] Figure 2 Sensitivity curves of three multifunctional hydrogels of the rare earth-starch system: (a) wheat starch; (b) potato starch; (c) corn starch; (d) sensitivity of different starch groups.
[0021] Figure 3 Fluorescence intensity curves of three multifunctional hydrogels in the rare earth-starch system were obtained.
[0022] Figure 4 Different strain cycles of the multifunctional hydrogel of the rare earth-starch system: (a) large strain; (b) small strain; (c) dynamic response.
[0023] Figure 5 Human-computer interaction diagrams for the prepared multifunctional hydrogel of rare earth-starch system: (a) elbow joint, (b) finger joint, (c) blinking.
[0024] Figure 6 The metal ion fluorescence quenching pattern of the prepared rare earth-starch system multifunctional hydrogel. Detailed Implementation
[0025] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.
[0026] This invention provides a multifunctional hydrogel based on a rare earth-starch system. The hydrogel is formed by doping europium ions into a starch-based hydrogel composed of deionized water (79.3 wt%), acrylamide (15.8 wt%), starch (2.3 wt%), polyvinyl alcohol (0.79 wt%), and silver nanowires (1.5 wt%). The starch selected is potato starch, wheat starch, or corn starch.
[0027] This invention provides a method for designing multifunctional hydrogels based on a rare earth-starch system. The specific steps of this method are as follows:
[0028] To minimize experimental error, the raw materials were weighed using a 0.01 g electronic balance. 0.1 g-0.5 g (0.1 g, 0.2 g, 0.3 g, 0.4 g, 0.5 g) of wheat starch and 0.1 g of polyvinyl alcohol were added to 10 ml of deionized water and heated in a water bath at 95 °C for 1.5 h to gelatinize. The mixture was then stirred until homogeneous. Next, the mixture was placed on a magnetic stirrer, and 2 g of acrylamide and 1 mg-5 mg (1 mg, 2 mg, 3 mg, 4 mg, 5 mg) of five different amounts of silver nanowires were added. 0.025 g of ammonium persulfate (APS) initiator and 0.003 g of N,N-methylenebisacrylamide (MBA) crosslinking agent were added to the mixed solution. 10 μL of tetramethylethylenediamine (TEMED) was added as a catalyst using a pipette. After thorough mixing, the mixture was ultrasonically degassed to ensure the solution was free of bubbles. The solution was transferred to a mold and placed in an oven at 50°C for 5 hours to allow it to fully gel. Finally, the formed hydrogel was immersed in 0.1 mol / L rare earth Eu solution. 3+ 10 min in solution to ensure Eu 3+ In the hydrogel, uniform distribution and Eu 3+ The formation of the complex yields a multifunctional hydrogel based on a rare earth-starch system as described in this invention.
[0029] The present invention provides another implementation method for designing multifunctional hydrogels based on rare earth-starch systems. The specific steps of the method are as follows: The raw materials are weighed using a 0.01g-0.5g (0.1g, 0.2g, 0.3g, 0.4g, 0.5g) electronic balance to reduce experimental errors. 0.1g-0.5g (0.1g, 0.2g, 0.3g, 0.4g, 0.5g) potato starch and 0.1g polyvinyl alcohol are added to 10ml of deionized water and placed in a water bath at 95℃ for gelatinization for 1.5h, and stirred evenly. Then, the mixture is removed and placed on a magnetic stirrer. 2g acrylamide and 1mg-5mg (1mg, 2mg, 3mg, 4mg, 5mg) of five different amounts of silver nanowires are added. 0.025g ammonium persulfate (APS) initiator and 0.003g N,N-methylenebisacrylamide (MBA) crosslinking agent are added to the mixed solution, and 10μL tetramethylethylenediamine (TEMED) is added as a catalyst using a pipette. After thorough stirring, the mixture is subjected to ultrasonic degassing to ensure that there are no bubbles in the solution. The solution was transferred to a mold and placed in an oven at 50°C for 5 hours to allow it to fully gel. Finally, the formed hydrogel was immersed in a 0.1 mol / L rare earth Eu3+ solution for 10 minutes to ensure the Eu3+ content was within acceptable limits. 3+ In the hydrogel, uniform distribution and Eu 3+ The formation of the complex yields a multifunctional hydrogel based on a rare earth-starch system as described in this invention.
[0030] The present invention provides another method for designing a multifunctional hydrogel based on a rare earth-starch system. The raw materials are weighed using a 0.01 g electronic balance to reduce experimental error. 0.1 g-0.5 g (0.1 g, 0.2 g, 0.3 g, 0.4 g, 0.5 g) of corn starch and 0.1 g of polyvinyl alcohol are added to 10 ml of deionized water and heated in a water bath at 95°C for 1.5 h to gelatinize. The mixture is then stirred until homogeneous. Next, it is placed on a magnetic stirrer, and 2 g of acrylamide and 1 mg-5 mg (1 mg, 2 mg, 3 mg, 4 mg, 5 mg) of five different amounts of silver nanowires are added. 0.025 g of ammonium persulfate (APS) initiator and 0.003 g of N,N-methylenebisacrylamide (MBA) crosslinking agent are added to the mixed solution. 10 μL of tetramethylethylenediamine (TEMED) is added as a catalyst using a pipette. After thorough stirring, the mixture is ultrasonically degassed to ensure that there are no air bubbles in the solution. The solution was transferred to a mold and placed in an oven at 50°C for 5 hours to allow it to fully gel. Finally, the formed hydrogel was immersed in a 0.1 mol / L rare earth Eu3+ solution for 10 minutes to ensure the Eu3+ content was within acceptable limits. 3+ In the hydrogel, uniform distribution and Eu 3+ The formation of the complex yields a multifunctional hydrogel based on a rare earth-starch system as described in this invention.
[0031] The multifunctional hydrogel of the rare earth-starch system prepared above was tested step by step as follows:
[0032] 1. Tensile tests were performed on the prepared hydrogel using a single-column mechanical testing machine.
[0033] A rectangular hydrogel (30mm × 2mm × 10mm) was clamped in a mechanical testing machine for a tensile test. The initial distance between the two clamps of the tensile testing machine was 10mm, and the tensile speed was kept constant at 40mm / min. The test was stopped when the hydrogel broke. The test results are as follows. Figure 1 As shown in (ac), when different amounts of starch were added (0.1g-0.5g), the stretching length first increased and then decreased with increasing addition. The multifunctional rare-earth-starch hydrogel exhibited the best stretching properties when the starch content was 0.3g. Among different systems using wheat, potato, and corn starch, potato starch showed better stretching properties. Further testing was conducted using the aforementioned starch content of 0.3g.
[0034] 2. The sensitivity of the prepared hydrogel was tested using a single-column mechanical testing machine and a Keithley 2400 digital source meter.
[0035] A rectangular hydrogel (30mm × 2mm × 10mm) was connected to both ends with copper wires, which were then connected to a Keithley 2400 digital source meter. The connected hydrogel was then clamped onto a mechanical testing machine for a tensile test. The initial distance between the two clamps of the tensile testing machine was 10mm, and the tensile speed was kept constant at 40mm / min. The test was stopped when the hydrogel broke during the tensile process.
[0036] During the stretching process, the resistance change of the hydrogel sensor was recorded using a Keithley digital source meter. The relative change in resistance is defined as follows:
[0037] ΔR / R0=(R-R0) / R0
[0038] Where R0 and R are the original resistance at 0% strain and the real-time resistance at a certain strain, respectively.
[0039] Sensitivity (measurement factor, GF) is defined as follows:
[0040] GF=(ΔR / R0) / ε
[0041] Where ε is the applied strain. Figure 2 The addition of silver nanowires at concentrations ranging from 1 mg to 5 mg to the hydrogel affected its tensile strength and sensing sensitivity. From (ac), a common conclusion was drawn: when the silver nanowire content was 2 mg, the tensile strength and sensitivity were optimal. Figure 2 (d) shows that the highest sensitivity for potato starch is 9.02. Further testing was conducted using 2 mg of silver nanowires.
[0042] 3. The fluorescence intensity of the multifunctional hydrogel of the rare earth-starch system was tested using an Agilent Cary Eclipse fluorescence spectrophotometer.
[0043] The fluorescence intensity of the prepared rare-earth-starch hydrogel was measured using an Agilent Cary Eclipse fluorescence spectrophotometer at an excitation wavelength of 365 nm. The test results are as follows: Figure 3 As shown, the fluorescence intensity of three different starches was compared at the optimal starch content (0.3g) and silver nanowire content (2mg). The results showed that potato starch had the highest fluorescence intensity. Further testing was conducted using potato as the starch type.
[0044] 4. Cyclic testing of rare earth-starch-based multifunctional hydrogels was conducted using a Keithley 2400 digital source meter and a stepper.
[0045] A rectangular hydrogel (30mm × 2mm × 10mm) was connected to both ends with copper wires, which were then connected to a Keithley 2400 digital source meter. The connected hydrogel was then fixed to the stepper. In the cyclic tensile test, the hydrogel was stretched to a set value (100-500%) at a speed of 60mm / min, and then returned to its original length at the same speed. Each stretch length was repeated three times. The test results are as follows: Figure 4 As shown in (a), the hydrogel sensor can maintain stable and repeatable operation under a maximum stretch of 800%, transmitting a stable electrical signal. The hydrogel is then stretched to a set value (1%-9%) at a speed of 60 mm / min, and then returned to its original length at the same speed, with each stretch length repeated three times. Figure 4 As shown in (b), the hydrogel sensor can maintain stable and repeatable operation under a minimum stretch of 1%, transmitting a stable electrical signal. After stretching the hydrogel by 15%, the force was immediately unloaded, and its response time was observed. As shown in Figure (c), the stretch release response time of the hydrogel is 52 ms.
[0046] 3. Human-computer interaction testing of rare earth-starch-based multifunctional hydrogels was conducted using a Keithley 2400 digital source meter.
[0047] To evaluate the practical performance of rare-earth-starch-based multifunctional hydrogels as strain sensors, the hydrogel was connected to a Keithley 2400 digital source meter using copper wire and attached to a joint or skin movement area of the human body, undergoing repeated bending and unfolding movements. The test results are as follows: Figure 5 As shown, Figure 5It is a diagram of electrical signals transmitted when a person makes the movements of bending their arm, fingers, and blinking. Because the hydrogel undergoes repeated deformation during this process, it transmits repetitive and stable electrical signals.
[0048] 4. The fluorescence quenching experiment of metal ions on rare earth-starch-based multifunctional hydrogels was carried out using an Agilent Cary Eclipse fluorescence spectrophotometer.
[0049] Since metal ions can substitute for rare earth ions in rare earth complexes, thereby causing fluorescence quenching of rare earth ions, seven different metal ions were selected for fluorescence quenching experiments. 0.1 mol / L Na₂SO₄ solutions were prepared for each. + Fe 3+、 K + Ga 2+ Mg 2+ Al 3+ Mn 2+ Seven different metal ion solutions were used. The prepared rare earth hydrogel was immersed in each solution for 1 minute, then removed and the metal ion solution on the surface of the hydrogel was wiped clean. Fluorescence intensity was measured using an Agilent Cary Eclipse fluorescence spectrophotometer at an excitation wavelength of 365 nm. The test results are as follows: Figure 6 As shown, control is a hydrogel that has not been soaked in a metal ion solution, and it can be seen that Na + The quenching of fluorescence is the weakest, while Fe... 3+ It is the strongest, exhibiting almost complete fluorescence quenching to the naked eye. Metal ion fluorescence quenching provides hydrogel sensors with more optical sensing methods.
Claims
1. A multifunctional hydrogel based on a rare earth-starch system, characterized in that, The hydrogel comprises 79.3 wt% deionized water, 15.8 wt% acrylamide, 2.3 wt% starch, 0.79 wt% polyvinyl alcohol, and 1.5 wt% silver nanowires, forming a starch-based hydrogel doped with europium ions.
2. The multifunctional hydrogel based on the rare earth-starch system according to claim 1, characterized in that, The starch used is potato starch, wheat starch, or corn starch.
3. The multifunctional hydrogel based on the rare earth-starch system according to claim 1, characterized in that, The starch used is potato starch.
4. The multifunctional hydrogel of the rare earth-starch system according to any one of claims 1-3, characterized in that, This rare-earth-starch system multifunctional hydrogel was prepared by the following method, the specific steps of which are as follows: (1) Dissolve polyvinyl alcohol and wheat starch in deionized water in sequence, heat at 95°C to gelatinize for 1.5 hours, and then mix thoroughly on a magnetic stirrer. (2) Add acrylamide and silver nanowires, and stir until no bubbles are generated; (3) Add crosslinking agent N,N'-methylenebisacrylamide, catalyst ammonium persulfate and initiator tetramethylethylenediamine and stir until uniform; (4) Transfer the solution to a mold and place it in an oven at 50°C for 5 hours to allow it to fully polymerize into a gel; (5) Immerse the formed hydrogel in a 0.1 mol / L rare earth solution for 10 min to obtain a multifunctional hydrogel of rare earth-starch system.
5. The multifunctional hydrogel of the rare earth-starch system according to any one of claims 4, characterized in that, Replace wheat starch with potato starch or corn starch.
6. The multifunctional hydrogel of the rare earth-starch system according to claim 3, characterized in that, The rare earth solution is rare earth Eu. 3+ Solution.
7. A design method for multifunctional hydrogels based on a starch-based system, characterized in that, The design method is as follows: starch and polyvinyl alcohol are heated to 95°C and gelatinized for 1.5 hours, then mixed thoroughly on a magnetic stirrer. Acrylamide and silver nanowires are added and stirred until no bubbles are generated. Next, N,N'-methylenebisacrylamide, ammonium persulfate catalyst, and tetramethylethylenediamine initiator are added and stirred thoroughly. The solution is transferred to a mold and placed in an oven at 50°C for 5 hours to fully polymerize into a gel. Finally, the formed hydrogel is immersed in a 0.1 mol / L rare earth solution for 10 minutes to obtain a multifunctional hydrogel of rare earth-starch system.
8. The design method for multifunctional hydrogels based on the α-starch system according to claim 7, characterized in that, The rare earth solution is rare earth Eu. 3+ Solution.