High-conductivity low-creep polyelectrolyte elastomer as well as preparation method and application thereof

Abstract

The invention relates to a high-conductivity low-creep polyelectrolyte elastomer as well as a preparation method and application thereof. The high-conductivity low-creep polyelectrolyte elastomer is polymerizable ionic liquid directly synthesized by hydroxyl ionic liquid and alkenyl-containing acyl chloride compounds through one-step reaction; the obtained ionic liquid is mixed with a neutral chain segment, a photoinitiator and a cross-linking agent are added to form a precursor solution, free radical polymerization is initiated by ultraviolet light to obtain the polyelectrolyte elastomer, and the obtained polyelectrolyte elastomer has no obvious creep deformation under 1000 times of cyclic stretching and shows excellent mechanical stability; the high-conductivity low-creep polyelectrolyte elastomer can be used for preparing a flexible ionizing pressure sensor, the capacitance peak value of the prepared flexible ionizing pressure sensor is kept stable in 2000 cycle tests, and excellent low-drift performance is shown.

Description

Technical Field

[0001] This invention relates to the field of flexible pressure sensor technology, and in particular to a high-conductivity, low-creep polyelectrolyte elastomer, its preparation method, and its application. Background Technology

[0002] Flexible pressure sensors have significant application value in fields such as flexible electronic skin, wearable medical devices, and human-computer interaction. Among them, ionomer pressure devices have attracted much attention due to their high sensitivity and large range. Existing solutions often use composite materials such as hydrogels / ionomers / polyelectrolyte elastomers, and introduce microstructures on their surfaces. During the application of pressure, the electrodes gradually come into contact with the microstructures on the surface of the composite material to form a double-layer capacitance. As the pressure increases, the double-layer capacitance further increases, thereby achieving pressure sensing.

[0003] However, hydrogels / ionogels are prone to signal drift under constant or high pressure. On the one hand, the viscoelastic properties of the gel cause the strain of the surface microstructure of the composite material to increase over time under constant pressure, thus the sensor response under constant pressure will change slowly over time, a phenomenon known as creep. On the other hand, the microscopic migration of small molecule solvents within the gel, edge leakage, and changes in water content caused by ambient temperature and humidity can alter the dielectric constant and ionic conductivity, further amplifying zero-point drift. Simultaneously, ionogels and electrodes often rely on physical adsorption or weak interactions for adhesion. Under cyclic compression / stretching, micro-slippage and local debonding occur at the interface, further introducing noise and zero-point drift, making it difficult to achieve long-term accurate characterization of pressure signals and weakening the accuracy and repeatability of long-term pressure measurements.

[0004] Therefore, it is urgent to systematically suppress drift and interface slip problems from two core dimensions: material optimization and interface design. On the one hand, under constant load, it is necessary to suppress the viscoelastic creep behavior of materials and the risk of solvent leakage to the greatest extent, and screen out polyelectrolyte elastomer materials with both low drift characteristics and high conductivity through multi-parameter synergistic control. On the other hand, it is necessary to construct an electrode-pressure-sensitive layer interface structure with excellent stability and shear resistance, so as to significantly improve the zero-point stability and cycle operation consistency of the sensor, and finally realize the fabrication of a flexible sensor with high conductivity, low creep and high robustness. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-conductivity, low-creep polyelectrolyte elastomer.

[0006] Another technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned high-conductivity, low-creep polyelectrolyte elastomer.

[0007] Another technical problem to be solved by the present invention is to provide the application of the above-mentioned high conductivity and low creep polyelectrolyte elastomer, based on which a stable and shear-resistant electrode-pressure-sensitive layer interface is formed by in-situ polymerization with a gold electrode.

[0008] To solve the above-mentioned technical problems, the technical solution proposed by the present invention is as follows:

[0009] A method for preparing a high-conductivity, low-creep polyelectrolyte elastomer, comprising the following specific steps:

[0010] (I) Polymerizable ionic liquids can be directly synthesized from hydroxyl-based ionic liquids and alkenyl-containing acyl chloride compounds through a one-step reaction;

[0011] (II) The obtained ionic liquid is mixed with neutral segments, and a photoinitiator and a crosslinking agent are added to form a precursor solution. The high-conductivity, low-creep polyelectrolyte elastomer is obtained by UV-initiated free radical polymerization.

[0012] Preferably, the preparation method of the above-mentioned high-conductivity, low-creep polyelectrolyte elastomer includes the following specific steps:

[0013] (1) The product obtained by reacting the first reactant with the second reactant is processed to obtain a first monomer containing an ionic group, wherein the first reactant is an imidazole salt or quaternary ammonium salt with hydroxyl substitution, the cationic part of which is an imidazole cation or quaternary ammonium cation with hydroxyl, and the anionic part is one of hexafluorophosphate, trifluoromethanesulfonate or bis(trifluoromethanesulfonyl)imide (e.g., 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide); the second reactant is an alkenyl acyl chloride compound (e.g., acryloyl chloride); the reaction is a nucleophilic substitution reaction or a nucleophilic addition reaction;

[0014] (2) The first monomer containing an ionic group is mixed with a neutral segment to obtain a mixed solution, wherein the neutral segment is an acrylic monomer, a vinyl ester monomer or an olefin monomer (e.g., methyl acrylate);

[0015] (3) Add crosslinking agent and photoinitiator to the mixed solution to obtain the precursor of polyelectrolyte elastomer, and carry out photopolymerization reaction on the precursor solution to obtain polyelectrolyte elastomer.

[0016] Preferably, in the preparation method of the above-mentioned high-conductivity, low-creep polyelectrolyte elastomer, the first monomer is prepared by the following method: the first reactant is slowly added dropwise to a solution of an alkene-containing acyl chloride compound placed in an ice bath environment, and then stirred under nitrogen. The product obtained from the reaction is dissolved in dichloromethane, extracted with water in a separatory funnel, and the lower layer liquid is collected. After repeated extraction 3 times, anhydrous sodium sulfate is added for drying, and after standing, the upper layer liquid is poured off. The dichloromethane is removed by vacuum evaporation at room temperature to obtain the first monomer.

[0017] Preferably, in the above-mentioned method for preparing high-conductivity, low-creep polyelectrolyte elastomer, the molar ratio of the alkenyl chloride compound solution to the first reactant is (1.0-1.8):1.

[0018] Preferably, in the preparation method of the above-mentioned high conductivity and low creep polyelectrolyte elastomer, the stirring conditions under nitrogen atmosphere are: stirring at 0-1°C for 1.5-2 hours, followed by heating to room temperature and stirring for 5 hours, and finally stirring at 40°C-50°C for 12-24 hours.

[0019] Preferably, in the above-mentioned method for preparing high-conductivity, low-creep polyelectrolyte elastomer, 2,6-di-tert-butyl-4-methylphenol is added to the first monomer to prevent the first monomer from oxidizing at room temperature and pressure.

[0020] Preferably, in the above-mentioned method for preparing the high-conductivity, low-creep polyelectrolyte elastomer, the mass ratio of 2,6-di-tert-butyl-4-methylphenol to the first monomer is (1-5):1000.

[0021] Preferably, in the above-mentioned method for preparing high-conductivity, low-creep polyelectrolyte elastomer, the total molar ratio of photoinitiator to first monomer and neutral segment is (0.1-1):100; the total molar ratio of crosslinking agent to first monomer and neutral segment is (0.5-15):100; and the molar ratio of first monomer to neutral segment is 1:(0.5-5).

[0022] Preferably, in the above-mentioned method for preparing high-conductivity, low-creep polyelectrolyte elastomer, the crosslinking agent is 1,6-hexanediol diacrylate, and the initiator is 2-hydroxy-2-methylphenylacetone.

[0023] Preferably, in the above-mentioned method for preparing high-conductivity, low-creep polyelectrolyte elastomer, the photopolymerization reaction conditions in step (3) are irradiation under a 30W, 365nm ultraviolet lamp for 30min-1h.

[0024] A high-conductivity, low-creep polyelectrolyte elastomer is prepared by the above method.

[0025] The aforementioned high-conductivity, low-creep polyelectrolyte elastomer, after 1000 cyclic stretching cycles at 250 kPa, showed a peak strain displacement on the 1000th cycle that differed from the peak strain displacement on the 1st cycle by no more than 1%.

[0026] The above-mentioned high-conductivity, low-creep polyelectrolyte elastomer is used in the in-situ polymerization of gold electrodes to form a stable and shear-resistant electrode-pressure-sensitive layer interface.

[0027] The above-mentioned high-conductivity, low-creep polyelectrolyte elastomers are used in the fabrication of flexible ionized pressure sensors.

[0028] Preferably, in the above application, the flexible ionized pressure sensor is a low-drift flexible ionized sensor.

[0029] Preferably, in the above application, the high-conductivity, low-creep polyelectrolyte elastomer is used as the pressure-sensitive layer to prepare a flexible ionized pressure sensor.

[0030] Preferably, in the above application, based on the polyelectrolyte elastomer, the gold electrode is treated with a silane solution containing thiol groups and acrylic double bond groups to achieve chemical bonding between the elastomer and the electrode, thereby constructing a stable and shear-resistant electrode-pressure-sensitive layer interface. The resulting flexible ionized pressure sensor exhibits no significant signal drift under multiple cycles.

[0031] Preferably, in the above application, the specific steps for chemical bonding between the pressure-sensitive layer and the lower electrode in the flexible ionized pressure sensor are as follows:

[0032] ① Prepare a first solution of silane reagent containing thiol groups and a second solution of silane reagent containing acrylic acid double bond groups. Both solutions are prepared at a volume ratio of deionized water: ethanol: reagent = 45±5v%: 45±5v%: 10±2v%. The pH value is adjusted by adding acetic acid to make it acidic (pH<7).

[0033] ②Immerse the polyimide film with gold deposited on its surface (as a flexible substrate) into the first solution, and after the treatment is completed, wash it with ethanol and deionized water in sequence;

[0034] ③Immerse the gold-film polyimide film treated in step ② further into the second solution, and after the treatment is completed, wash it with ethanol and deionized water in sequence.

[0035] ④ The precursor solution is injected into the surface of the treated gold electrode, and an in-situ polymerization reaction is initiated under ultraviolet light irradiation to form a pressure-sensitive layer that is chemically bonded to the gold electrode.

[0036] Preferably, in the above application, in step ①, the ratio of deionized water: ethanol: reagent is 4.5: 4.5: 1.

[0037] Preferably, in the above application, the first solution in step ① is γ-mercaptopropyltriethoxysilane, and the second solution is 3-(methacryloyloxy)propyltrimethoxysilane.

[0038] Preferably, in the above application, the pH of the first and second solutions after adding acetic acid in step ① is 2.8 to 3.3.

[0039] Preferably, in the above application, the time for immersing the polyimide film with gold film deposited on its surface in the first solution in step ② is 5 to 10 minutes.

[0040] Preferably, in the above application, the time for immersing the polyimide film with gold film deposited on its surface in the second solution in step ③ is 30 to 50 minutes.

[0041] Preferably, in the above application, step ④ involves fixing the treated gold electrode onto a glass slide using double-sided polyimide tape, placing a grooved PDMS structure on its surface to control the thickness of the pressure-sensitive layer; subsequently, the precursor is injected into the groove and covered with a glass slide, and the precursor undergoes in-situ polymerization under ultraviolet light irradiation, thereby forming a pressure-sensitive layer on the surface of the gold electrode that is chemically bonded to it.

[0042] Preferably, in the above application, the groove thickness of the φ-shaped PDMS structure in step ④ is 100-200 μm.

[0043] A flexible ionized pressure sensor comprises, from top to bottom, an upper electrode layer, a spacer layer, the aforementioned pressure-sensitive layer, a silane layer containing acrylic double bond groups, a silane layer containing thiol groups, and a lower electrode layer. The pressure-sensitive layer is chemically bonded to the lower electrode layer through the silane layer containing acrylic double bond groups, the silane layer containing thiol groups, and the lower electrode layer to form a bonded structure.

[0044] The aforementioned flexible ionized pressure sensor features low drift and high robustness.

[0045] Preferably, in the above-mentioned flexible ionized pressure sensor, the upper electrode layer and the lower electrode layer are composed of 20 nm of chromium and 100 nm of gold deposited on the surface of a 20 μm polyimide film by magnetron sputtering technology.

[0046] Preferably, in the above-mentioned flexible ionized pressure sensor, the upper surface of the pressure-sensitive layer has a microstructure, while the lower surface does not. The microstructure is formed by injecting a precursor into a polyvinyl alcohol film with a microstructure on its surface and surrounded by PDMS gaskets at its edges. The polyvinyl alcohol film is prepared by mixing polyvinyl alcohol particles and water at a mass ratio of 1:10, and then injecting the solution into the surface of 10,000-grit sandpaper and drying it.

[0047] Preferably, in the above-mentioned flexible ionized pressure sensor, the spacer layer is made of 100µm double-sided polyimide tape and processed into a U-shaped structure by laser cutting.

[0048] Preferably, the above-mentioned flexible ionized pressure sensor is constructed by the following method:

[0049] (I) The upper and lower electrodes are formed by sequentially depositing a chromium layer and a gold layer on a polyimide film, and the deposition method is a physical vapor deposition method (e.g., magnetron sputtering or electron beam evaporation, etc.);

[0050] (II) The spacer layer is made of double-sided polyimide tape or silicone and is processed into a U-shaped structure by laser cutting.

[0051] (III) The pressure-sensitive layer is composed of the above-mentioned high-conductivity, low-creep polyelectrolyte elastomer, one side of which is connected to the gold electrode by chemical bonding, and the other side has a microstructure.

[0052] Preferably, in the above-mentioned flexible ionized pressure sensor, the microstructure is not limited to being fabricated by molding, photolithography, thermal embossing, laser engraving, or micro / nano 3D printing.

[0053] Technical effect

[0054] The aforementioned high-conductivity, low-creep polyelectrolyte elastomer exhibits excellent mechanical stability with no significant creep under 1000 cycles of tensile testing. Its preparation method is simple and time-efficient; the corresponding ionic liquid can be prepared in a single reaction step. In-situ polymerization of the polyelectrolyte elastomer and gold electrode is achieved by treating the gold electrode with a silane solution containing thiol and acrylic double bond groups, constructing a stable, shear-resistant electrode-pressure-sensitive layer interface. The high-conductivity, low-creep flexible sensor prepared from the polyelectrolyte elastomer showed no significant creep under constant normal pressure stimulation, and the capacitance peak remained stable during 2000 normal pressure cycles. The flexible ionized pressure sensor with low drift and high robustness, prepared through interfacial chemical bonding between the polyelectrolyte elastomer and the gold film, showed no significant signal drift during normal pressure and shear stress coupled cyclic testing, and the capacitance peak remained stable during 2000 cycles, demonstrating excellent low-drift and anti-slip performance. Specifically:

[0055] (1) Using covalently cross-linked polyelectrolyte elastomer as pressure-sensitive layer, it effectively suppresses the deformation accumulation caused by viscoelasticity under constant pressure, achieving high conductivity, low creep and low drift; polyelectrolyte elastomer does not contain free solvent, which can avoid solvent leakage and volatilization, and significantly improve environmental stability.

[0056] (2) The chemical bonding interface between the electrode and the pressure-sensitive layer is constructed sequentially by thiol-gold bond, silane coupling and double bond polymerization, which effectively reduces interface micro-slippage and local debonding and enhances cycle consistency.

[0057] (3) By designing the molecular composition, crosslinking density and side chain polarity, the dielectric constant and modulus can be synergistically tunable, achieving higher sensitivity and wider range while maintaining flexibility. Attached Figure Description

[0058] Figure 1 This is a structural diagram of the high-conductivity, low-creep, and highly robust flexible sensor.

[0059] In the figure: 1-polyimide film; 2-gold film; 3-spacer layer; 4-pressure-sensitive layer; 5-silane layer containing acrylic double bond groups; 6-silane layer containing thiol groups.

[0060] Figure 2 The impedance test results of high-conductivity, low-creep polyelectrolyte elastomers at different temperatures are presented.

[0061] Figure 3 The results are the creep test results of the high-conductivity, low-creep polyelectrolyte elastomer.

[0062] Figure 4 The results are the sensitivity test results of the high-conductivity, low-creep flexible sensor.

[0063] Figure 5 The results are the signal drift test results of the high-conductivity, low-creep flexible sensor under dynamic and static superposition conditions.

[0064] Figure 6 The results are the signal drift test results of the high-conductivity, low-creep flexible sensor under normal pressure.

[0065] Figure 7 The results are the signal drift test results of the high-conductivity, low-creep, and high-robust flexible sensor under normal and shear stress coupling.

[0066] Figure 8 The results show the signal drift of the high-conductivity, low-creep flexible sensor under normal and shear stress coupling.

[0067] Figure 9 The results show the signal drift test of the PVA@H3PO4-based flexible sensor under constant normal pressure.

[0068] Figure 10 The results are the signal drift test results under normal pressure cycling of the PVA@H3PO4-based flexible sensor.

[0069] Figure 11 The results are the signal drift test results of the PVA@H3PO4-based flexible sensor under dynamic and static superposition conditions. Detailed Implementation

[0070] The preparation method and application of the high-conductivity, low-creep polyelectrolyte elastomer of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0071] Example 1

[0072] Preparation of monomers containing ionic groups: 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was used as the first reactant.

[0073] (1) Under nitrogen atmosphere, 7.34 g of acryloyl chloride was placed in an ice bath at 0-1 °C, and 22.04 g of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt solution was slowly added dropwise while stirring gently. The mixture was stirred at 0-1 °C for 1.5 hours, then heated to room temperature and stirred for 5 hours. Finally, it was stirred at 40 °C for 12 hours to ensure complete reaction. After the reaction, the product was dissolved in dichloromethane, poured into a separatory funnel, and extracted with water. The lower layer was collected. After repeated extraction three times, anhydrous sodium sulfate was added for drying. After standing, the upper layer was poured off, and the dichloromethane was removed by vacuum evaporation at room temperature to obtain the first monomer containing the ionic group.

[0074] (2) Add 0.013g of 2,6-di-tert-butyl-4-methylphenol to the first monomer containing the ionic group to prevent the monomer containing the ionic group from being oxidized at room temperature and pressure.

[0075] Example 2

[0076] Preparation of high-conductivity, low-creep polyelectrolyte elastomers:

[0077] (1) The first monomer containing ionic groups obtained in Example 1 was mixed with methyl acrylate at a molar ratio of 1:2, and crosslinking agent 1,6-hexanediol diacrylate and photoinitiator 2-hydroxy-2-methylphenylacetone (initiator 1173) were added. The amount of crosslinking agent was 8% of the total molar amount of the monomer containing ionic groups and methyl acrylate, and the amount of photoinitiator was 0.5% of the total molar amount of the monomer containing ionic groups and methyl acrylate. The mixture was stirred evenly at room temperature to obtain a precursor solution.

[0078] (2) A PDMS sheet with a thickness of 200um is die-cut into a groove of 3cm×0.5cm, and bonded to a glass slide after plasma treatment; the precursor solution is injected into the groove, covered with another glass slide, and irradiated under a 30W, 365nm ultraviolet lamp for 1h.

[0079] (3) After irradiation, the upper glass slide is removed to obtain a polyelectrolyte elastomer with high conductivity and low creep.

[0080] Example 3

[0081] Fabrication of flexible sensors based on high-conductivity, low-creep polyelectrolyte elastomers:

[0082] (1) Prepare a solution by mixing polyvinyl alcohol particles with water at a mass ratio of 1:10, drop it onto the surface of 10,000-grit sandpaper and dry it, then peel it off to obtain a polyvinyl alcohol film with microstructure.

[0083] (2) A PDMS sheet with a thickness of 100μm is die-cut into a 1cm*1cm groove, and bonded to a glass slide after plasma treatment; the precursor solution described in Example 2 is injected into the groove, and another glass slide with a microstructure PVA film on its surface is used to cover it. The slide is then placed under a 30W, 365nm ultraviolet lamp for 1 hour to complete the curing.

[0084] (3) After curing, remove the upper glass slide and peel off the pressure-sensitive layer; use a laser cutter to cut a 100μm thick double-sided polyimide film into a U-shaped groove as a spacer layer, and assemble the upper electrode-spacer layer-pressure-sensitive layer-low electrode from top to bottom to obtain a high-conductivity, low-creep flexible sensor.

[0085] Example 4

[0086] Constructing the electrode-pressure-sensitive layer interface:

[0087] (1) Mix 45% by volume each of deionized water and ethanol with 10% by volume of (3-mercaptopropyl)triethoxysilane and stir until homogeneous at room temperature; place the pH meter electrode into the solution and slowly add 99.5% pure acetic acid to adjust the pH to 3.0. Immerse the gold-coated polyimide film on the surface for 5 minutes, and then wash it three times each with ethanol and deionized water.

[0088] (2) Mix deionized water, ethanol and 3-(trimethoxysilyl)propyl methacrylate in a volume ratio of 45%:45%:10%, and adjust the pH to 3.0 with acetic acid (99.5%) as above. Soak the polyimide film treated in step (1) for 40 minutes, and then wash it with ethanol and deionized water three times in sequence.

[0089] (3) Fix the treated polyimide film with gold coating onto a glass slide, and place a 100 μm thick PDMS groove in the shape of a square on it; inject the precursor solution of Example 2 into the groove, and cover it with another glass slide with a microstructured polyvinyl alcohol film; irradiate it under a 30W, 365nm ultraviolet lamp for 1 hour.

[0090] (4) After curing, remove the upper glass slide and PDMS groove to obtain the chemically bonded electrode-pressure-sensitive layer interface.

[0091] Example 5

[0092] Fabrication of flexible sensors with high conductivity, low creep, and high robustness:

[0093] A 100µm thick double-sided polyimide film is cut into a U-shaped groove using a laser cutting machine. Then, the electrode-pressure-sensitive layer interface, spacer layer, and upper electrode are assembled sequentially from bottom to top to obtain the desired result. Figure 1The flexible sensor shown features high conductivity, low creep, and high robustness.

[0094] Specifically, the flexible sensor consists of, from top to bottom, an upper electrode layer, a spacer layer 3, a pressure-sensitive layer 4, a silane layer 5 containing acrylic double bond groups, a silane layer 6 containing thiol groups, and a lower electrode layer. The lower electrode layer and the pressure-sensitive layer are bonded together chemically to form a bonded structure. The polyimide film 1 and the gold film 2 constitute the upper electrode layer / lower electrode layer. The upper electrode layer and the lower electrode layer are symmetrically arranged. The pressure-sensitive layer 4 and the silane layer 5 containing acrylic double bond groups are connected by CC. The silane layer 5 containing acrylic double bond groups and the silane layer 6 containing thiol groups are connected by Si-O. The silane layer 6 containing thiol groups and the gold film 2 of the lower electrode layer are connected by Au-S. Thus, the pressure-sensitive layer and the lower electrode layer form an integral structure through the silane layer 5 containing acrylic double bond groups and the silane layer 6 containing thiol groups.

[0095] Example 6

[0096] Fabrication of a flexible sensor based on PVA@H3PO4:

[0097] 1g of polyvinyl alcohol (PVA) particles were added to 9g of deionized water and stirred at 90℃ for 2 hours until completely dissolved. After the PVA solution cooled to room temperature, 825μL of phosphoric acid was added, and stirring continued at room temperature for another 2 hours. The resulting solution was then poured onto 10000-grit sandpaper and cured at 55℃ for 2 hours. After curing, the PVA@H3PO4 film was peeled off the sandpaper and cut into 1cm*1cm sheets as pressure-sensitive layers. Finally, the bottom electrode, PVA@H3PO4 film, spacer layer, and top electrode were stacked sequentially from bottom to top to assemble a flexible sensor based on PVA@H3PO4.

[0098] Example of effect

[0099] 1. Impedance testing at different temperatures

[0100] Electrochemical impedance spectroscopy was performed on the high-conductivity, low-creep polyelectrolyte elastomer prepared in Example 2. The conductivity change was measured within the test temperature range, and the test results are as follows: Figure 2 As shown.

[0101] Figure 2 Test results show that as the temperature increases, the impedance of polyelectrolyte elastomers gradually decreases, while the conductivity increases accordingly, exhibiting an exponential growth trend.

[0102] 2. Creep test

[0103] The high-conductivity, low-creep polyelectrolyte elastomer prepared in Example 2 was subjected to cyclic tensile testing at 250 kPa, and the results are as follows: Figure 3 As shown.

[0104] Figure 3 The test results show that under cyclic tensile stress of 250 kPa, the peak strain change of the high-conductivity, low-creep polyelectrolyte elastomer does not exceed 0.1%, and no obvious creep phenomenon occurs, indicating stable performance.

[0105] 3. Sensitivity Test

[0106] The sensitivity of the high-conductivity, low-creep flexible sensor prepared in Example 3 was tested, and the results are as follows: Figure 4 As shown.

[0107] Figure 4 The test results show that the sensitivity is 4.15 kPa in the 0–300 kPa range. -1 The value is 2.55 kPa in the 300–700 kPa range. -1 The value is 0.67 kPa in the 700–1000 kPa range. -1 It covers a wide measurement range while maintaining high responsiveness with segmented resolution, balancing high sensitivity at low pressures with measurability at high pressures.

[0108] 4. Signal drift test under dynamic and static superposition.

[0109] The high-conductivity, low-creep flexible sensor prepared in Example 3 was subjected to signal drift tests under dynamic and static superposition conditions. The results are as follows: Figure 5 As shown.

[0110] Figure 5 The test results show that when a normal pressure of 400 kPa is applied to the flexible sensor for 1 hour, and the pressure fluctuates triangularly within a range of 50 kPa above and below, the sensor signal remains stable under the superposition of dynamic and static conditions. This result indicates that the sensor has strong anti-interference capability under the superposition of periodic and static pressures, can stably respond to changes in external pressure, and does not exhibit significant signal drift.

[0111] 5. Pressure signal drift test

[0112] Pressure signal drift tests were performed on the high-conductivity, low-creep flexible sensor prepared in Example 3, and the results are as follows: Figure 6 As shown.

[0113] Figure 6 The test results show that when a normal pressure of 400 kPa is continuously applied to the flexible sensor for 1 hour, the sensor’s capacitive response increases from 12.685 nF to 12.810 nF, with a drift rate of 0.985%. This indicates that the sensor maintains low drift output under steady-state high-pressure conditions and is suitable for long-term continuous monitoring.

[0114] 6. Cyclic stability test

[0115] Cyclic stability tests were conducted on the flexible sensor with high conductivity, low creep, and high robustness prepared in Example 5, and the results are as follows: Figure 7 As shown.

[0116] Figure 7 The test results show that after 2000 cycles of testing under a coupled load of 500 kPa normal pressure and 136 kPa shear stress, the capacitive response of the flexible sensor does not change significantly, and the output is stable and repeatable, indicating that the device has cyclic reliability with resistance to interface slippage and high robustness.

[0117] In summary, the polyelectrolyte elastomer described in this invention exhibits excellent mechanical stability with no significant creep under 1000 cycles of tensile testing; the flexible ionized pressure sensor prepared with it maintains a stable peak capacitance during 2000 cycles of testing, demonstrating excellent low drift performance.

[0118] Comparative Example

[0119] 1. Cyclic stability test

[0120] The sensitivity of the high-conductivity, low-creep flexible sensor prepared in Example 3 was tested for cyclic stability, and the results are as follows: Figure 8 As shown.

[0121] Figure 8 The test results show that after the flexible sensor under a coupled load of 500 kPa normal pressure and 136 kPa shear stress for 2000 cycles, its capacitance response fluctuated significantly, with the fluctuation range between 2 and 3 nF. This phenomenon indicates that under long-term shear stress, significant slippage occurred between the pressure-sensitive layer and the lower electrode.

[0122] 2. Stability testing of flexible sensors based on PVA@H3PO4

[0123] The flexible sensor based on PVA@H3PO4 prepared in Example 6 was subjected to signal drift tests under constant pressure, cyclic pressure, and dynamic and static superposition conditions. The test results are as follows: Figure 9 , Figure 10 , Figure 11 As shown.

[0124] Figure 9 The test results show that when a normal pressure of 400 kPa is applied continuously for 1 hour, the capacitive response of the sensor increases from 1.882 μF to 6.480 μF, with a drift rate of 244.315%. Figure 10The test results show that after 2000 cycles of testing under a normal pressure of 500 kPa, the capacitance response first increases due to liquid leakage, and then decreases due to solvent evaporation. Figure 11 The test results show that when a normal pressure of 400 kPa is applied for 700 seconds and the pressure fluctuates triangularly within the range of ±50 kPa, the capacitance response shows obvious drift. In summary, the sensor exhibits obvious capacitance response fluctuations under different pressure conditions.

[0125] 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 a high-conductivity, low-creep polyelectrolyte elastomer, characterized in that: The specific steps are as follows: (I) Polymerizable ionic liquids can be directly synthesized from hydroxyl-based ionic liquids and alkenyl-containing acyl chloride compounds through a one-step reaction; (II) The obtained ionic liquid is mixed with neutral segments, and a photoinitiator and a crosslinking agent are added to form a precursor solution. The high-conductivity, low-creep polyelectrolyte elastomer is obtained by UV-initiated free radical polymerization.

2. The method for preparing the high-conductivity, low-creep polyelectrolyte elastomer according to claim 1, characterized in that: The specific steps are as follows: (1) The product obtained by reacting the first reactant with the second reactant is processed to obtain a first monomer containing an ionic group, wherein the first reactant is an imidazole salt or a quaternary ammonium salt with hydroxyl substitution, the cationic part of which is an imidazole cation or a quaternary ammonium cation with a hydroxyl group, and the anionic part is one of hexafluorophosphate, trifluoromethanesulfonate or bis(trifluoromethanesulfonyl)imide; the second reactant is an acyl chloride compound containing an alkenyl group; the reaction is a nucleophilic substitution reaction or a nucleophilic addition reaction; (2) The first monomer containing ionic groups is mixed with a neutral segment to obtain a mixed solution, wherein the neutral segment is an acrylic monomer, a vinyl ester monomer or an olefin monomer; (3) Add crosslinking agent and photoinitiator to the mixed solution to obtain the precursor of polyelectrolyte elastomer, and carry out photopolymerization reaction on the precursor solution to obtain polyelectrolyte elastomer.

3. The method for preparing the high-conductivity, low-creep polyelectrolyte elastomer according to claim 2, characterized in that: The total molar ratio of the photoinitiator to the first monomer and the neutral segment is (0.1-1):100; the total molar ratio of the crosslinking agent to the first monomer and the neutral segment is (0.5-15):100; the molar ratio of the first monomer to the neutral segment is 1:(0.5-5); the first monomer is prepared by the following method: the first reactant is slowly added dropwise to a solution of an olefinic acyl chloride compound placed in an ice bath environment, and then stirred under nitrogen. The product obtained by the reaction is dissolved in dichloromethane, extracted with water in a separatory funnel, and the lower layer liquid is collected. After repeated extraction, anhydrous sodium sulfate is added for drying, and after standing, the upper layer liquid is poured off. Dichloromethane is removed by vacuum evaporation at room temperature to obtain the first monomer.

4. The method for preparing the high-conductivity, low-creep polyelectrolyte elastomer according to claim 3, characterized in that: The molar ratio of the alkenyl chloride-containing compound solution to the first reactant is (1.0–1.8):1; the stirring conditions under nitrogen atmosphere are: stirring at 0–1°C for 1.5–2 hours, followed by heating to room temperature and stirring for 5 hours, and finally stirring at 40–50°C for 12–24 hours.

5. A high-conductivity, low-creep polyelectrolyte elastomer, characterized in that: It is prepared by the method described in any one of claims 1-4.

6. The application of the high-conductivity, low-creep polyelectrolyte elastomer of claim 5 in the in-situ polymerization of gold electrodes to form a stable and shear-resistant electrode-pressure-sensitive layer interface.

7. The application of the high-conductivity, low-creep polyelectrolyte elastomer of claim 5 in the fabrication of a flexible ionized pressure sensor.

8. The application according to claim 7, characterized in that: The high-conductivity, low-creep polyelectrolyte elastomer is used as the pressure-sensitive layer to prepare a flexible ionized pressure sensor. The specific steps for the chemical bonding between the pressure-sensitive layer and the lower electrode are as follows: ① Prepare a first solution of silane reagent containing thiol groups and a second solution of silane reagent containing acrylic acid double bond groups. Both solutions are prepared at a volume ratio of deionized water: ethanol: reagent = 45±5v%: 45±5v%: 10±2v%, and the pH value is adjusted by adding acetic acid to make it acidic. ②Immerse the polyimide film with gold deposited on its surface into the first solution, and after the treatment is completed, wash it with ethanol and deionized water in sequence; ③Immerse the gold-coated polyimide film treated in step ② further into the second solution, and after the treatment is completed, wash it with ethanol and deionized water in sequence. ④ The precursor solution is injected into the treated gold electrode surface, and an in-situ polymerization reaction is initiated under ultraviolet light irradiation to form a pressure-sensitive layer that is chemically bonded to the gold electrode.

9. A flexible ionized pressure sensor, characterized in that: From top to bottom, it consists of an upper electrode layer, a spacer layer, a pressure-sensitive layer as described in claim 8, a silane layer containing acrylic double bond groups, a silane layer containing thiol groups, and a lower electrode layer. The pressure-sensitive layer is formed by chemically bonding the silane layer containing acrylic double bond groups, the silane layer containing thiol groups, and the lower electrode layer to form a bonded structure.

10. The flexible ionized pressure sensor according to claim 9, characterized in that: It is constructed using the following method: (I) The upper and lower electrodes are formed by sequentially depositing a chromium layer and a gold layer on a polyimide film, and the deposition method is physical vapor deposition. (II) The spacer layer is made of double-sided polyimide tape or silicone and is processed into a U-shaped structure by laser cutting. (III) The pressure-sensitive layer is composed of the high-conductivity, low-creep polyelectrolyte elastomer of claim 6. One side of the layer is connected to the gold electrode by chemical bonding, and the other side has a microstructure. The microstructure is formed by injecting a precursor into a polyvinyl alcohol film with a microstructure on the surface and a PDMS gasket around the edge. The polyvinyl alcohol film is prepared by mixing polyvinyl alcohol particles and water at a mass ratio of 1:10, and then injecting the solution into the surface of 10,000-grit sandpaper and drying it.

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