A conductive dendritic composite gel, its preparation method and application
By depositing metallic tin dendrites in situ in the hydrogel to construct conductive pathways, the balance between conductivity and mechanical properties of conductive hydrogels is solved, achieving efficient improvement in both conductivity and mechanical properties, which is suitable for wearable flexible strain sensors.
Patent Information
- Application Number
- CN202411703870.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2044-11-26
AI Technical Summary
Existing conductive hydrogels struggle to balance conductivity and mechanical properties. Hydrophobic fillers tend to agglomerate, leading to uneven distribution. Additives increase system complexity, and rigid fillers affect tensile properties, while ionic conductive fillers have low efficiency.
Using hydrogel as the matrix, conductive pathways are constructed by in-situ deposition of metallic tin dendrites. The hydrophilicity of the hydrogel attracts tin ions to form a three-dimensional metallic dendrite network, which is combined with a flexible gel to improve conductivity and mechanical properties.
Significant improvements in conductivity and mechanical properties have been achieved. The conductive dendritic composite gel exhibits good toughness and conductivity, making it suitable for wearable flexible strain sensors.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the technical field of polymer materials, specifically to a conductive dendritic composite gel, its preparation method, and its application. Background Technology
[0002] With the rise and widespread application of flexible smart devices, the development of flexible wearable devices has received increasing attention. Hydrogels, as three-dimensional soft materials composed of polymers and water, are considered reliable matrix materials for flexible devices due to their properties similar to human tissue and good biocompatibility. Currently, conductive hydrogels are mainly classified into two types: ionicly conductive and electronically conductive. Common strategies to improve the conductivity of gels include using conductive polymers or adding conductive fillers. However, these electronically conductive fillers usually need to be dispersed in the desired gel precursor solution and undergo additional ultrasonic treatment before polymerization and crosslinking. Therefore, the above methods have the following shortcomings:
[0003] 1) Hydrophobic fillers tend to agglomerate in aqueous precursor solutions, leading to uneven filler distribution and weakened polymer matrix-filler interactions; 2) Adding additives such as cellulose nanofibers, polydopamine, and surfactants to promote filler dispersion further complicates the system; 3) Some conductive fillers may interfere with the polymerization process, and their rigidity can worsen the tensile properties of the hydrogel. Although ionic conductive fillers generally do not have these problems, existing conductive hydrogels often suffer from low efficiency.
[0004] Therefore, how to construct a simple and efficient pathway within the gel without compromising its mechanical properties remains an important problem that urgently needs to be solved. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention proposes a conductive dendritic composite gel, its preparation method, and its application. This invention uses a hydrogel as a matrix and deposits metallic tin dendrites in situ within the gel to construct conductive pathways, thereby preparing a conductive dendritic composite gel.
[0006] In this design, the hydrophilicity of the hydrogel framework attracts tin ions, thereby promoting the in-situ deposition of tin dendrites. Simultaneously, the three-dimensional metal dendrite network effectively provides conductive pathways, improving the gel's conductivity. Furthermore, the coupling between the rigid metal dendrites and the flexible gel significantly enhances the mechanical properties of the dendritic composite gel.
[0007] The technical solution of the present invention is as follows:
[0008] A method for preparing a conductive dendritic composite gel includes the following steps:
[0009] 1) The vinyl monomer, photoinitiator, and crosslinking agent are ultrasonically dispersed in water to obtain a polymer prepolymer solution, which is then subjected to ultraviolet light (365nm) to initiate a polymerization reaction to form a hydrogel;
[0010] The vinyl monomer is selected from: 2-acrylamido-2-methylpropanesulfonic acid (AMPS), acrylamide (AM), [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide (SBAA), 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonate inner salt (SBMA), dimethyl-(4-vinylphenyl)propanesulfonate ammonium (DVBAPS) or 3-(1-(4-vinylbenzyl)-1H-imidazol-3-onthium)propane-1-sulfonate (VBIPS), etc., preferably 3-(1-(4-vinylbenzyl)-1H-imidazol-3-onthium)propane-1-sulfonate (VBIPS);
[0011] The photoinitiator is selected from: 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959), 2-hydroxy-2-methyl-1-phenylpropanone (1173), 2-methyl-1-[4-methylthiophenyl]-2-morpholino-1-propanone (907), 1-hydroxycyclohexylbenzophenone (184) or 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide (TPO), preferably 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959);
[0012] The crosslinking agent is selected from molecules containing two or more double bonds, such as N,N-dimethylacrylamide (DMAA) and N,N-methylenebisacrylamide (MBA).
[0013] In the preferred polymer prepolymer solution, the content of vinyl monomer is 1-8 mmol / mL, the content of photoinitiator is 0.1-1 wt%, and the content of crosslinking agent is 0.05-2 wt%.
[0014] The polymerization reaction was carried out at room temperature for 0.5–12 hours.
[0015] 2) Soak the hydrogel obtained in step 1) in stannous chloride solution to obtain a hydrogel rich in stannous ions;
[0016] The preferred concentration of stannous chloride solution is 0.05–6 mol / L, and the soaking time is 2–48 h;
[0017] In the preparation of stannous chloride solution, to prevent the hydrolysis of stannous ions, anhydrous stannous chloride is first dissolved in hydrochloric acid (1-10 mol / L), and then diluted with water to the required concentration.
[0018] 3) External electrodes were attached to both ends of the tin-rich hydrogel obtained in step 2), and a voltage was applied to induce in-situ dendrite deposition. After that, the hydrogel was soaked in deionized water and dialyzed to remove free Sn. 2+ Ions were used to obtain a conductive dendritic composite gel.
[0019] The external electrode is a tin electrode, the applied voltage range is 1 to 10V, and the energizing time is 1 to 10 minutes;
[0020] The dialysis soaking time in deionized water is 12 to 60 hours, and the deionized water is changed multiple times during the soaking process.
[0021] This invention relates to the conductive dendritic composite gel prepared by the above-described preparation method.
[0022] The conductive dendritic composite gel of this invention can be used as a wearable flexible strain sensor. For example, the conductive dendritic composite gel is connected to an electrochemical workstation at both ends by copper tape and wires. At the same time, 3M VHB tape is used to encapsulate both sides of the gel to realize the construction of a flexible strain sensor.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0024] 1. The conductive dendritic composite gel provided by this invention exhibits good mechanical toughness (2.3 MJ / m) due to the combination of its soft matrix and rigid dendritic conductive network. 3 It also exhibits good crack passivation ability and high fracture toughness (720kJ / m). 2 This is beneficial for the long-term daily use of conductive gel.
[0025] 2. The 3D conductive dendrite network constructs excellent conductive pathways within the gel, enabling the conductive composite gel to exhibit outstanding conductivity (12.5 S / m), which can be used as a sensor to detect and identify human movement. Attached Figure Description
[0026] Figure 1 : Schematic diagram of the preparation of the conductive dendritic composite gel of the present invention.
[0027] Figure 2 : A schematic diagram of the structure of the flexible strain sensor prepared by the present invention.
[0028] Figure 3 Swelling kinetics curves and appearance photos of gels with different molecular structures in stannous chloride solution in Examples 1 to 4.
[0029] Figure 4 Swelling kinetics curves of the gels in Examples 1, 5, 6 and 7 in stannous chloride solutions of different concentrations.
[0030] Figure 5 Dendrite growth of gels soaked in stannous chloride solutions of different concentrations under different voltages in Examples 1, 5, 6 and 7.
[0031] Figure 6 Examples 1, 5, 6, and 7 show the gels formed after in-situ dendrite deposition induced under different concentrations of stannous chloride solution, and the removal of excess Sn by soaking in water. 2+ Photographs of the appearance of the ion-derived dendritic composite gel.
[0032] Figure 7 Tensile curves, Young's modulus, and tensile toughness of the dendritic composite gel and pure gel prepared in Example 1 and Comparative Example 1.
[0033] Figure 8 Fracture toughness of dendritic composite gels and pure gels prepared in Example 1 and Comparative Example 1. The inset shows the changes of notched dendritic composite gels under different strains.
[0034] Figure 9 Comparison of the electrical conductivity of the dendritic composite gel prepared in Example 1 and Comparative Example 1 with that of the pure gel.
[0035] Figure 10 Example 1 shows the resistance change of a sensor based on dendritic composite gel under different strains.
[0036] Figure 11 Example 1: The sensor based on dendritic composite gel is worn on a finger, and the resistance changes caused by different gestures. Detailed Implementation
[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following description is only the most preferred embodiment of the present invention and should not be regarded as a limitation on the scope of protection of the present invention.
[0038] Example 1
[0039] First, 1.22 g (4 mmol) of VBIPS monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 0.97 mL of deionized water, and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm UV light for 4 h to polymerize and obtain pVB hydrogel. Then, the hydrogel was immersed in a 2 mol / L stannous chloride solution for 24 h to fully absorb Sn. 2+ Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0040] The above-mentioned conductive dendritic composite gel can be used as a wearable flexible strain sensor. The steps are as follows: the two ends of the prepared dendritic composite gel are connected to the electrochemical workstation through copper tape and wires. At the same time, 3M VHB tape is used to encapsulate both sides of the gel to realize the construction of the flexible strain sensor.
[0041] Example 2
[0042] First, 1.11 g (4 mmol) of SBMA monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 1.08 ml of deionized water, and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm ultraviolet light for 4 h to polymerize and obtain pSB hydrogel. Then, the hydrogel was immersed in a 2 mol / L stannous chloride solution for 24 h to fully absorb Sn. 2+ Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0043] Example 3
[0044] First, 0.28 g (4 mmol) of AM monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 1.91 ml of deionized water and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm ultraviolet light for 4 h to polymerize and obtain pAM hydrogel. Then, the hydrogel was immersed in a 2 mol / L stannous chloride solution for 24 h to fully absorb Sn. 2+ Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0045] Example 4
[0046] First, 0.83 g (4 mmol) of AMPS monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 1.23 ml of deionized water and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm ultraviolet light for 4 h to polymerize and obtain pAMPS hydrogel. Then, the hydrogel was immersed in a 2 mol / L stannous chloride solution for 24 h to fully absorb Sn. 2+Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0047] Example 5
[0048] First, 1.22 g (4 mmol) of VBIPS monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 0.97 ml of deionized water, and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm UV light for 4 h to polymerize and obtain pVB hydrogel. Then, the hydrogel was immersed in a 0.5 mol / L stannous chloride solution for 24 h to allow for sufficient absorption of Sn. 2+ Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0049] Example 6
[0050] First, 1.22 g (4 mmol) of VBIPS monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 0.97 ml of deionized water, and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm ultraviolet light for 4 h to polymerize and obtain pVB hydrogel. Then, the hydrogel was immersed in a 1 mol / L stannous chloride solution for 24 h to fully absorb Sn. 2+ Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0051] Example 7
[0052] First, 1.22 g (4 mmol) of VBIPS monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBA were dispersed in 0.97 ml of deionized water, and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm ultraviolet light for 4 h to polymerize and obtain a hydrogel. Then, the hydrogel was immersed in a 4 mol / L stannous chloride solution for 24 h to fully absorb Sn. 2+Ions. Further, by connecting tin electrodes to both ends of the gel after soaking and equilibration, and controlling the voltage to 10V, dendrites are induced to deposit in situ within the gel. Finally, after applying the current for 3 minutes, the gel is immersed in a large amount of deionized water for dialyzing to obtain a conductive dendrite composite gel.
[0053] Comparative Example 1
[0054] First, 1.22 g (4 mmol) of VBIPS monomer, 0.01 g of photoinitiator 2959, and 0.003 g of crosslinking agent MBAA were dispersed in 0.97 ml of deionized water and then sonicated for 10 min to obtain a polymer precursor solution. Next, the polymer precursor solution was injected into a mold using a syringe and irradiated under 365 nm ultraviolet light for 4 h to initiate polymerization, yielding a pVB hydrogel. Finally, the prepared hydrogel was immersed in a large amount of deionized water to remove unreacted small molecules within the gel.
[0055] The gel samples prepared in Examples 1 to 7 and Comparative Example 1 were tested, and the test results are as follows: Figures 1 to 11 As shown below, in conjunction with Figures 1 to 11 Explanation:
[0056] Figure 1 The diagram shows the preparation of the conductive dendritic composite gel based on the present invention. After the hydrogel is soaked in stannous chloride solution, the in-situ deposition of tin ions in the gel network is induced by an external electrode. Finally, the dendritic gel is soaked in deionized water for dialyzing to remove free ions and obtain the conductive dendritic composite gel.
[0057] Figure 2 This is a schematic diagram of the strain sensor fabricated by encapsulating a conductive dendritic composite gel. Specifically, the gel is encapsulated on both sides using VHB double-sided adhesive to achieve better adhesion between the gel and the human body and longer-lasting water retention.
[0058] Figure 3 The figures show the swelling kinetics curves and gel photographs of hydrogels with different molecular structures in stannous chloride solution in Examples 1 to 4. The pVB gel exhibits more obvious swelling characteristics in stannous chloride solution due to the strong anti-polyelectrolyte effect, the pAMPS gel shrinks due to its polyelectrolyte effect, while the pAM gel does not show obvious volume change in stannous chloride solution due to its nonionic properties.
[0059] Figure 4 The swelling kinetics curves of pVB hydrogels in Examples 1, 5, 6 and 7 in stannous chloride solutions of different concentrations are shown. The swelling rate of the gel increases synchronously with the increase of solution concentration, which is consistent with the law of gel anti-polyelectrolyte effect. The swelling rate reaches up to 900% in the solution with a concentration of 4M.
[0060] Figure 5The figures show the dendrite growth of pVB hydrogels soaked in stannous chloride solutions of different concentrations under different voltages in Examples 1, 5, 6 and 7. The gel soaked in high-concentration stannous chloride solution showed the fastest dendrite growth in the early stage because more salt ions induced rapid dendrite nucleation inside the gel.
[0061] Figure 6 The images show the appearance of the gels after soaking in stannous chloride solutions of different concentrations and inducing in-situ dendrite deposition in Examples 1, 5, 6 and 7, and the dendrite composite gels after final soaking in water to remove free ions.
[0062] Figure 7 The tensile curves, statistical Young's modulus, and tensile toughness of the dendritic composite gel and pure gel prepared in Example 1 and Comparative Example 1 are shown. The dendritic composite gel based on this invention has a modulus of 0.6 MPa and a tensile toughness as high as 2.3 MJ / m. 3 Compared to dendrite-free pure gel, the tensile toughness was significantly improved.
[0063] Figure 8 The fracture toughness of the dendritic composite gels prepared in Example 1 and Comparative Example 1, as well as the pure gel, is shown in the illustrations. The notched dendritic composite gel is photographed under different strains. The fracture toughness of the dendritic composite gel based on this invention is 1334 J / m. 2 Compared with the dendritic-free gel prepared in Comparative Example 1, the fracture toughness is significantly improved, and the illustration shows that the dendritic composite gel has crack passivation ability.
[0064] Figure 9 The conductivity of the dendritic composite gel and the pure gel prepared in Example 1 and Comparative Example 1 is compared. The dendritic composite gel based on the present invention has excellent conductivity due to the introduction of conductive dendritic network, with a conductivity as high as 12.5 S / m.
[0065] Figure 10 The resistance change of the sensor based on dendritic composite gel in Example 1 under different strains is shown. There are obvious resistance changes under both small and large strains. The signal has good stability after five cycles, which proves the high sensitivity and wide range detection capability of the sensor.
[0066] Figure 11 As shown in Example 1, when the sensor based on dendritic composite gel is worn on a finger, the resistance changes according to different hand gestures show that the five fingers have obvious signal differences under different hand gestures. This can effectively detect and identify changes in human limbs, demonstrating the potential of the sensor in the future application of wearable devices.
[0067] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.
[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A method for preparing a conductive dendritic composite gel, characterized in that, The steps include: 1) The vinyl monomer, photoinitiator, and crosslinking agent are ultrasonically dispersed in water to obtain a polymer prepolymer solution, which is then subjected to ultraviolet light irradiation to initiate a polymerization reaction to form a hydrogel; The vinyl monomer is selected from: 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide, 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, dimethyl-(4-vinylphenyl)propanesulfonate ammonium or 3-(1-(4-vinylbenzyl)-1H-imidazol-3-onium)propane-1-sulfonate; The photoinitiator is selected from: 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, 2-hydroxy-2-methyl-1-phenylpropanone, 2-methyl-1-[4-methylthiophenyl]-2-morpholino-1-propanone, 1-hydroxycyclohexylbenzophenone or 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide; The crosslinking agent is selected from: N,N-dimethylacrylamide or N,N-methylenebisacrylamide; 2) Soak the hydrogel obtained in step 1) in stannous chloride solution to obtain a hydrogel rich in stannous ions; 3) External electrodes were attached to both ends of the tin-rich hydrogel obtained in step 2), and a voltage was applied to induce in-situ dendrite deposition. After that, the hydrogel was soaked in deionized water and dialyzed to remove free Sn. 2+ Ions were used to obtain a conductive dendritic composite gel.
2. The method for preparing the conductive dendritic composite gel as described in claim 1, characterized in that, Step 1) In the polymer prepolymer solution, the content of vinyl monomer is 1-8 mmol / mL, the content of photoinitiator is 0.1-1 wt%, and the content of crosslinking agent is 0.05-2 wt%.
3. The method for preparing the conductive dendritic composite gel as described in claim 1, characterized in that, In step 1), the polymerization reaction is carried out at room temperature for 0.5 to 12 hours.
4. The method for preparing the conductive dendritic composite gel as described in claim 1, characterized in that, In step 2), the concentration of stannous chloride solution is 0.05–6 mol / L, and the soaking time is 2–48 h.
5. The method for preparing the conductive dendritic composite gel as described in claim 1, characterized in that, In step 3), the external electrode is a tin electrode, the applied voltage range is 1 to 10V, and the energizing time is 1 to 10 minutes.
6. The method for preparing the conductive dendritic composite gel as described in claim 1, characterized in that, In step 3), the dialysis soaking time in deionized water is 12 to 60 hours, and the deionized water is changed multiple times during the soaking process.
7. The conductive dendritic composite gel prepared by the preparation method according to any one of claims 1 to 6.
8. The application of the conductive dendritic composite gel as described in claim 7 as a wearable flexible strain sensor.