Ionic conductive elastomer, preparation method thereof and ionizing pressure sensor

Abstract

The invention relates to the technical field of flexible sensors, in particular to an ionic conductive elastomer, a preparation method thereof and an ionizing pressure sensor. The preparation method of the ionic conductive elastomer comprises the following steps: (a) mixing an alkenyl-containing ionic liquid, an elastomer matrix-containing solution, a disulfide bond-containing cross-linking agent and a nanofiller to obtain a precursor solution; (b) uniformly mixing the precursor solution with an initiator, carrying out orientation treatment, then initiating a polymerization reaction, and drying to obtain the ionic conductive elastomer, the orientation treatment comprises the step of applying an orientation electric field or a shearing force to the uniformly mixed solution. The prepared ionic conductive elastomer has the characteristics of high resilience, low hysteresis and low creep deformation, also has efficient and stable ion transmission capability, self-repairing capability and multi-dimensional force decoupling capability, and has a wide application prospect in the field of ionizing pressure sensors.

Description

Technical Field

[0001] This invention relates to the field of flexible sensor technology, and in particular to an ion-conductive elastomer, its preparation method, and an ionized pressure sensor. Background Technology

[0002] With the rapid development of flexible electronics, wearable devices, and intelligent robots, the demand for high-performance flexible sensors capable of accurately sensing physical signals such as pressure and deformation has become increasingly urgent. Among various sensor types, ionized pressure sensors have become a research hotspot in this field due to their advantages such as simple structure, high sensitivity, and ability to detect static pressure. Their working mechanism mainly relies on the change in the interfacial electric double layer caused by the microstructural changes of the key sensitive material—the ion-conducting elastomer—under pressure. Therefore, the intrinsic properties of the ion-conducting elastomer, as the core of the sensor, directly determine the sensor's core indicators, such as sensitivity, detection limit, response speed, stability, and durability.

[0003] To meet the demands of high-performance sensor development, ion-conductive elastomer materials must possess high resilience, low hysteresis, and low creep. High resilience ensures that the sensor can quickly and almost completely recover to its initial shape and electrical state after pressure unloading, which is fundamental for achieving rapid response and high-precision, repeatable measurements. Low hysteresis reflects the low energy dissipation of the material during loading and unloading cycles, directly determining the consistency and reliability of the sensor's output signal in cyclic testing, and is key to achieving high-precision measurements. Low creep refers to the small tendency of the material's deformation to increase over time under constant stress. This characteristic ensures the stability of the sensor's readings during long-term static pressure measurements, avoiding signal drift.

[0004] Currently, the mainstream methods for preparing ion-conductive elastomers typically employ a physical blending strategy, incorporating ionic liquids or salts into traditional elastomer substrates (such as silicone rubber and polyurethane) to impart ionic conductivity. However, this approach presents a fundamental contradiction: while the ionic liquid, acting as a plasticizer, imparts ionic conductivity, it significantly weakens the interactions between polymer chains, leading to over-plasticization of the substrate. This disrupts the integrity of the elastomer network, reduces chain segment movement resistance, and macroscopically manifests as a decrease in material modulus, increased permanent deformation, severely impaired resilience, and significant mechanical hysteresis and creep behavior. Sensors prepared from ion-conductive elastomers obtained in this way struggle to balance high sensitivity with excellent dynamic mechanical stability, and are prone to performance degradation and signal distortion during long-term cyclic use.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an ion-conductive elastomer, its preparation method, and an ionized pressure sensor. The ion-conductive elastomer of this invention not only has high resilience, low hysteresis, and low creep characteristics, but also has efficient and stable ion transport capabilities and self-healing capabilities, as well as multi-dimensional force decoupling capabilities, which can meet the development needs of high-performance sensors.

[0007] The first aspect of this invention provides a method for preparing an ion-conducting elastomer, comprising the following steps: (a) A precursor solution is obtained by mixing an alkenyl-containing ionic liquid, an elastomer-containing matrix solution, a disulfide-containing crosslinking agent, and a nanofiller; Based on the total mass of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-containing crosslinking agent, and the nanofiller being 100%, the amounts of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-containing crosslinking agent, and the nanofiller are 20%~50%, 42.5%~79.4%, 0.1%~2.5%, and 0.5%~5%, respectively. (b) The precursor solution is mixed with the initiator and oriented, then a polymerization reaction is initiated, and the mixture is dried to obtain an ion-conductive elastomer; The orientation process includes applying a directional electric field or a shear force to the homogeneously mixed solution.

[0008] In a specific embodiment of the present invention, the elastomer matrix includes at least one selected from thermoplastic polyurethane, ethylene-vinyl acetate elastomer, and styrene block copolymer. Further, in the solution containing the elastomer matrix, the mass concentration of the elastomer matrix is ​​5% to 30%.

[0009] In a specific embodiment of the present invention, the solvent in the solution containing the elastomer matrix includes at least one of acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0010] In a specific embodiment of the present invention, the raw materials for preparing the alkenyl-containing ionic liquid include: an alkenyl-containing zwitterionic salt and a lithium salt; the alkenyl-containing zwitterionic salt includes at least one of 1-carboxymethyl-3-vinylimidazolium chloride, 1-sulfopropyl-3-vinylimidazolium inner salt, and 1-(carboxymethyl)-3-vinyl-1H-imidazolium bromide; the lithium salt includes at least one of lithium bis(trifluoromethanesulfonylimide), lithium bis(fluorosulfonylimide), lithium tetrafluoroborate, and lithium hexafluorophosphate.

[0011] In a specific embodiment of the present invention, the crosslinking agent containing disulfide bonds includes at least one of bis(2-methacryloyl)oxyethyl disulfide and 3,3'-disulfide bis(sulfosuccinimide propionate).

[0012] In a specific embodiment of the present invention, the nanofiller includes at least one of cellulose nanofibers, nanomolecular sieves, MXene nanosheets, graphene oxide nanosheets, nanovermiculite, and nanoclay.

[0013] In a specific embodiment of the present invention, in step (b), the mass of the initiator is 0.1% to 1% of the mass of the alkenyl-containing ionic liquid in the precursor solution. Further, the initiator includes at least one of a photoinitiator and a thermal initiator.

[0014] In a specific embodiment of the present invention, when the directional electric field is applied, the field strength is 5~20V / cm and the processing time is 10~30min.

[0015] In a specific embodiment of the present invention, when applying shear force, shear force is provided by scraping the solution with a scraper, and the scraping speed is 1~10cm / s.

[0016] In a specific embodiment of the present invention, the polymerization reaction is initiated by ultraviolet light irradiation or heating. Further, the polymerization reaction time is 1-30 minutes.

[0017] The second aspect of the present invention provides an ion-conducting elastomer, which is prepared by the method for preparing the ion-conducting elastomer provided in the first aspect of the present invention.

[0018] A third aspect of the present invention provides an ionized pressure sensor, comprising the ion-conducting elastomer provided in the second aspect of the present invention.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for preparing ion-conductive elastomers provided by this invention yields ion-conductive elastomers with a dual-network structure of interpenetrating covalent and physical crosslinks. The covalently crosslinked network formed by the elastomer matrix provides a creep-resistant framework structure. The physical crosslinked network, formed by in-situ polymerization of alkenyl-containing ionic liquids, provides continuous channels for ion transport and forms dynamic crosslinking points through weak interactions such as electrostatic forces between polymer chains. The introduction of a disulfide-bonded crosslinking agent allows one end of its molecular chain to copolymerize with the alkenyl-containing ionic liquid, while the other end can react with or form physical entanglements with the elastomer matrix segments, endowing the material with intrinsic self-healing capabilities. The nanofiller surface has abundant binding sites, which can act as dynamic physical crosslinking points through physical interactions such as hydrogen bonding and electrostatic forces. Under external field induction, the nanofiller can form anisotropic orientation structures, not only endowing the material with significant mechanical reinforcement but also achieving decoupling sensing capabilities for multidimensional forces. The ion-conductive elastomer prepared by this invention has high resilience, low hysteresis, and low creep characteristics, as well as efficient and stable ion transport capability, self-healing capability, and multi-dimensional force decoupling capability, and has broad application prospects in the field of ion-electrode pressure sensors. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0021] The first aspect of this invention provides a method for preparing an ion-conducting elastomer, comprising the following steps: (a) A precursor solution is obtained by mixing an alkenyl-containing ionic liquid, an elastomer-containing matrix solution, a disulfide-containing crosslinking agent, and a nanofiller; Based on the total mass of alkenyl-containing ionic liquid, elastomer matrix, disulfide-containing crosslinking agent, and nanofiller as 100%, the amounts of alkenyl-containing ionic liquid, elastomer matrix, disulfide-containing crosslinking agent, and nanofiller are 20%~50%, 42.5%~79.4%, 0.1%~2.5%, and 0.5%~5%, respectively. (b) The precursor solution and the initiator are mixed evenly, oriented, and then the polymerization reaction is initiated and dried to obtain an ion-conductive elastomer; Orientation treatment includes applying a directional electric field or a shear force to a homogeneously mixed solution.

[0022] The method for preparing ion-conductive elastomers provided by this invention produces ion-conductive elastomers with a dual-network structure of interpenetrating covalent and physical crosslinks. This endows the material with the ability to maintain structural integrity and prevent permanent deformation under large deformation and high-frequency cyclic stretching, ensuring dynamic stability of mechanical properties. The covalent crosslinked network formed by the elastomer matrix provides a creep-resistant framework structure. The polyionic liquid, formed by in-situ polymerization of alkenyl-containing ionic liquids, constitutes a physical crosslinked network, providing continuous channels for ion transport and forming dynamic crosslinking points through weak interactions such as electrostatic forces between polymer chains. The introduction of a disulfide-bonded crosslinking agent allows one end of its molecular chain to copolymerize with the alkenyl-containing ionic liquid, while the other end can react with or form physical entanglements with the elastomer matrix segments, endowing the material with intrinsic self-healing capabilities. The nanofiller surface has abundant binding sites, which can act as dynamic physical crosslinking points through physical interactions such as hydrogen bonding and electrostatic forces. Under external field induction, the nanofiller can form anisotropic orientation structures, not only endowing the material with significant mechanical enhancement effects but also achieving decoupled sensing capabilities for multidimensional forces. Under minute deformation, a large number of reversible dynamic bonds in the system break and recombine, causing changes in the local electric field and ion transport path, thereby significantly increasing the capacitance change rate and improving sensitivity.

[0023] In a specific embodiment of the present invention, the raw materials for preparing the alkenyl-containing ionic liquid include: an alkenyl-containing zwitterionic salt and a lithium salt with a sterically hindered anion. The alkenyl-containing ionic liquid is prepared by an ion exchange method, the specific preparation method including but not limited to: mixing the alkenyl-containing zwitterionic salt and the lithium salt in a certain proportion and continuously stirring to obtain the alkenyl-containing ionic liquid. The molar ratio of the alkenyl-containing zwitterionic salt to the lithium salt is 1:1. The ionic liquid forms because the lithium salt with the sterically hindered anion breaks the intermolecular hydrogen bonds of the zwitterionic salt with the sterically hindered cation, thereby lowering the melting point and making it a liquid at room temperature.

[0024] The alkenyl-containing ionic liquid of this invention forms a polyionic liquid through in-situ polymerization in the presence of an elastomer matrix, thereby constructing a dual-network structure with interpenetrating covalent and physical crosslinks. The polyionic liquid formed by the in-situ polymerization of the alkenyl-containing ionic liquid constitutes the physical crosslink network, providing not only a continuous conduction path for ion transport but also forming dynamic crosslinking points through weak interactions such as electrostatic interactions between polymer chains. Specifically, the ionic liquid can form numerous reversible ionic and hydrogen bonds with the groups on the surface of the nanofiller, and construct disulfide bonds and other dynamic interactions through copolymerization with a crosslinking agent containing disulfide bonds, thus enabling the material system to possess excellent energy dissipation and self-healing capabilities.

[0025] In a specific embodiment of the present invention, based on the total mass of the alkenyl-containing ionic liquid, elastomer matrix, disulfide-bonded crosslinking agent, and nanofiller being 100%, the amount of alkenyl-containing ionic liquid is 20% to 50%, specifically 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any combination thereof. Controlling the amount of alkenyl-containing ionic liquid within the above range helps to construct an ionicly conductive elastomer that possesses ionic conductivity, mechanical properties, and self-healing capabilities. If the amount of alkenyl-containing ionic liquid is too high, the relative content of the elastomer matrix is ​​insufficient, weakening the covalently crosslinked backbone structure that plays a role in creep resistance, thus leading to a decrease in the material's flexibility, elasticity, and other mechanical properties. If the amount of alkenyl-containing ionic liquid is too low, it is difficult to form a continuous polyionic liquid physical crosslinking network, not only reducing ionic conductivity but also decreasing the number of sites in the material that can participate in dynamic interactions, thereby affecting its energy dissipation capacity and self-healing efficiency.

[0026] In a specific embodiment of the present invention, the raw materials for preparing the alkenyl-containing ionic liquid include: an alkenyl-containing zwitterionic salt and a lithium salt; the alkenyl-containing zwitterionic salt includes at least one selected from 1-carboxymethyl-3-vinylimidazolium chloride, 1-sulfonyl-3-vinylimidazolium inner salt, and 1-(carboxymethyl)-3-vinyl-1H-imidazolium bromide; the lithium salt includes at least one selected from lithium bis(trifluoromethanesulfonylimide), lithium bis(fluorosulfonylimide), lithium tetrafluoroborate, and lithium hexafluorophosphate. The lithium salt with a sterically hindered anion disrupts the intermolecular hydrogen bonds of the zwitterionic salt with a sterically hindered cation, thereby lowering the melting point and resulting in a liquid state at room temperature.

[0027] In a specific embodiment of the present invention, the elastomer matrix includes at least one of thermoplastic polyurethane (TPU), ethylene-vinyl acetate (EVA) elastomer, and styrene block copolymer. The styrene block copolymer includes any one of styrene-butadiene-styrene block copolymer (SBS) and styrene-ethylene-butene-styrene block copolymer (SEBS).

[0028] The covalently cross-linked network formed by the elastomer matrix of this invention provides a creep-resistant skeletal structure for the material. Simultaneously, by utilizing a solution containing the elastomer matrix, uniform dispersion and support of alkenyl-containing ionic liquids, disulfide-bonded cross-linking agents, and nanofillers can be achieved, resulting in a dual-network structure with interpenetrating covalent and physical cross-links through in-situ polymerization.

[0029] In a specific embodiment of the present invention, based on the total mass of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-bonded crosslinking agent, and the nanofiller being 100%, the amount of the elastomer matrix is ​​42.5% to 79.4%, specifically within the range of 42.5%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 79.4%, or any combination thereof. Controlling the amount of the elastomer matrix within the above range helps to construct an ion-conductive elastomer that possesses both ionic conductivity and mechanical properties. When the amount of the elastomer matrix is ​​too high, the relative content of the alkenyl-containing ionic liquid is low, leading to a decrease in the ionic conductivity of the material and a reduction in the number of sites that can participate in dynamic interactions. Consequently, the energy dissipation capacity and self-healing efficiency of the material decrease, making it difficult to fully utilize the advantages of the dynamic network. When the amount of the elastomer is too low, the covalently crosslinked backbone structure is weakened, resulting in a decrease in the material's flexibility, elasticity, and other mechanical properties.

[0030] In a specific embodiment of the present invention, the mass concentration of the elastomer matrix in the solution containing the elastomer matrix is ​​5% to 30%, specifically it can be 5%, 10%, 15%, 20%, 25%, 30% or any combination thereof.

[0031] This invention employs a template method to prepare an interpenetrating double network. The elastomeric polymer in the covalently cross-linked network should dissolve to form a continuous physical gel template with a microscopic phase-separated structure. The specific type of elastomer is not limited to the elastomers proposed in this invention; any conventionally soluble linear elastomer can be used. The mass concentration of the elastomer matrix in the solution is preferably 5% to 30%. When the concentration is below 5%, the elastomer network is too loose; when the concentration is above 30%, the network is too dense, which is detrimental to the penetration and in-situ polymerization of alkenyl-containing ionic liquids and nanofillers. Controlling the mass concentration of the elastomer matrix solution within the above range makes it easier to form an interpenetrating double continuous structure with controllable phase region size, thereby optimizing the balance between mechanical and electrical properties.

[0032] In a specific embodiment of the present invention, the solvent in the solution containing the elastomer matrix includes at least one selected from acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide. The specific type of solvent is determined by its solubility in the elastomer matrix.

[0033] In a specific embodiment of the present invention, the crosslinking agent containing disulfide bonds includes at least one of bis(2-methacryloyl)oxyethyl disulfide and 3,3'-disulfide bis(sulfosuccinimide propionate).

[0034] In a specific embodiment of the present invention, based on the total mass of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-containing crosslinking agent, and the nanofiller as 100%, the amount of the disulfide-containing crosslinking agent is 0.1% to 2.5%, specifically 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, or any combination thereof. When the amount of the disulfide-containing crosslinking agent is too high, the dynamic crosslinking density of the system is too large, which restricts the movement of polymer chain segments and reduces the flexibility of the material; when the amount of the disulfide-containing crosslinking agent is too low, it is difficult to form a sufficient number of dynamic covalent crosslinking points in the system, resulting in insufficient self-healing ability.

[0035] In a specific embodiment of the present invention, the nanofiller includes at least one selected from cellulose nanofibers, nanomolecular sieves, MXene nanosheets, graphene oxide nanosheets, nanovermiculite, and nanoclay. Further, the average particle size of the nanofiller is 5-100 nm, specifically within the range of 5 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, or any combination thereof.

[0036] The nanofiller of the present invention has abundant functional groups (such as -OH, -COOH, etc.) on its surface, which can not only improve mechanical properties, but also generate strong interfacial interactions with zwitterionic groups, lithium salts, etc., further dissipating energy and promoting ion dissociation and transport.

[0037] In a specific embodiment of the present invention, based on the total mass of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-bonded crosslinking agent, and the nanofiller as 100%, the amount of nanofiller is 0.5% to 5%, specifically 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof. When the amount of nanofiller is too high, it is easy for it to aggregate in the elastomer matrix, impairing the mechanical properties of the material and hindering ion conduction pathways; when the amount of nanofiller is too low, there is a lack of sufficient binding sites to form dynamic physical crosslinking points such as hydrogen bonds and electrostatic forces with the polymer, and the multidimensional force decoupling ability is insufficient.

[0038] In a specific embodiment of the present invention, step (a) involves preparing the precursor solution by adding an alkenyl-containing ionic liquid, a disulfide-bonded crosslinking agent, and a nanofiller to a solution containing an elastomer matrix, stirring, and then ultrasonically treating the solution to obtain a homogeneous precursor solution. The ultrasonic treatment can be performed under conventional ultrasonic conditions, which will not be elaborated upon here.

[0039] In a specific embodiment of the present invention, in step (b), the mass of the initiator is 0.1% to 1% of the mass of the alkenyl-containing ionic liquid in the precursor solution, specifically within the range of 0.1%, 0.3%, 0.5%, 0.8%, 1%, or any combination thereof. Further, the initiator includes at least one of a photoinitiator and a thermal initiator.

[0040] In specific embodiments of the present invention, the photoinitiator includes, but is not limited to, any one or more of photoinitiator 1173, photoinitiator 184, and photoinitiator 2959; the thermal initiator includes, but is not limited to, any one or more of organic peroxide initiators and azo initiators.

[0041] In a specific embodiment of the present invention, the polymerization reaction is initiated by ultraviolet light irradiation or heating. Further, the polymerization reaction time is 1-30 minutes. In actual operation, a suitable initiation method is selected based on the type of initiator, ensuring that polymerization can be initiated.

[0042] In a specific embodiment of the present invention, the specific operation method for applying the directional electric field is to use a high-voltage polarizer to connect two parallel electrodes placed one above the other, place the mold containing the solution between the electrodes, and set the electric field strength according to the electrode spacing. The field strength is 5~20V / cm, specifically it can be 5V / cm, 8V / cm, 10V / cm, 12V / cm, 15V / cm, 18V / cm, 20V / cm or any combination thereof; the processing time is 10~30min, specifically it can be 10min, 15min, 20min, 25min, 30min or any combination thereof.

[0043] In a specific embodiment of the present invention, when applying shear force, the shear force is provided to the solution by the scraper on the automatic scraper. The scraping speed is set to 1~10cm / s, specifically 1cm / s, 3cm / s, 5cm / s, 8cm / s, 10cm / s or any combination thereof.

[0044] Under the action of the electric or shear force field described above in this invention, the nanofiller aligns in an orientation, forming electrical / mechanical anisotropy. When the resulting ion-conductive elastomer is used in a pressure sensor, its ion transport and deformation differ under external force stimulation (normal and shear forces), resulting in different electrical signals and achieving decoupling from multidimensional forces.

[0045] In specific embodiments of the present invention, the drying method includes, but is not limited to, vacuum drying.

[0046] The second aspect of the present invention provides an ion-conducting elastomer, which is prepared by the method for preparing the ion-conducting elastomer provided in the first aspect of the present invention.

[0047] A third aspect of the present invention provides an ionized pressure sensor, comprising the ion-conducting elastomer provided in the second aspect of the present invention.

[0048] The ionized pressure sensor derived using the ion-conductive elastic system of this invention exhibits excellent sensitivity, wide measurement range, fast response, low hysteresis, long cycle life, and multidimensional force decoupling capability, meeting the demands of next-generation high-performance flexible sensing technology. Specifically, its sensitivity can reach >10 kPa. -1 The range can be 0.01~3000kPa, the response time can be ≤1ms, the signal drift rate can be ≤0.5%, it can be stably cycled >50000 times, and it has multi-dimensional force decoupling capability.

[0049] In a specific embodiment of the present invention, the ion-conducting pressure sensor includes two electrode layers and an ion-conducting elastomer layer disposed between the two electrode layers, wherein the ion-conducting elastomer layer is made of an ion-conducting elastomer.

[0050] Example 1 This embodiment provides a method for preparing an ion-conducting elastomer, including the following steps: (1) Take 1-carboxymethyl-3-vinylimidazolium chloride (0.01mol, 1.88g) and lithium bis(trifluoromethanesulfonylimide) (0.01mol, 2.87g) and stir continuously at room temperature for 1h to obtain an alkenyl-containing ionic liquid.

[0051] (2) Add 2g of thermoplastic polyurethane (TPU, Covestro 1035AU) to 8g of acetone, heat to 40°C and stir until TPU dissolves to obtain a solution containing elastomer matrix with a TPU mass concentration of 20%.

[0052] (3) Take 3.37g of the solution containing the elastomer matrix obtained in step (2), then add 0.3g of the ionic liquid containing the alkenyl group obtained in step (1), then add 0.006g of bis(2-methacryloyl)oxyethyl disulfide and 0.02g of cellulose nanofibers (Shenzhen Qihong New Materials Co., Ltd., product model: C-CNC 04), stir for 60min, and then sonicate for 30min to obtain the precursor solution.

[0053] (4) Add 0.0015g of photoinitiator 1173 to the precursor solution obtained in step (3), mix evenly in the dark to obtain a mixture; then use an automatic film scraper to scrape the mixture into a film, with the scraper providing shear force and the scraping speed being 5cm / s. Then, polymerize the mixture under a 365nm wavelength ultraviolet lamp for 10min, and then place the polymerized material in a 60℃ vacuum oven to dry until the solvent is removed, to obtain an ion-conductive elastomer with a sample thickness of 1mm and a width of 100×100mm.

[0054] Example 2 This embodiment provides a method for preparing an ion-conducting elastomer, including the following steps: (1) Mix 1-sulfopropyl-3-vinylimidazolium salt (0.01 mol, 2.16 g) and lithium difluorosulfonylimide (0.01 mol, 1.87 g) and stir continuously at room temperature for 2 h to obtain an alkenyl-containing ionic liquid.

[0055] (2) Add 1g of ethylene-vinyl acetate elastomer (EVA, Taisox EVA 7360M) to 19g of N,N-dimethylformamide, heat to 80°C and stir until EVA dissolves to obtain a solution containing elastomer matrix with EVA mass concentration of 5%.

[0056] (3) Take 15.88g of the solution containing the elastomer matrix obtained in step (2), then add 0.2g of the ionic liquid containing the alkenyl group obtained in step (1), then add 0.001g of bis(2-methacryloyl)oxyethyl disulfide and 0.005g of nano molecular sieve (Aladdin reagent, SBA-15), stir for 30min, and then sonicate for 60min to obtain the precursor solution.

[0057] (4) Add 0.0001g of photoinitiator 184 to the precursor solution obtained in step (3), mix evenly in the dark to obtain a mixture; then use an automatic film scraper to scrape the mixture into a film, with the scraper providing shear force and the scraping speed being 1cm / s. Then, polymerize under a 365nm wavelength ultraviolet lamp for 30min, and then place the polymerized material in an 80℃ vacuum oven to dry until the solvent is removed, to obtain an ion-conductive elastomer with a sample thickness of 1mm and a width of 100×100mm.

[0058] Example 3 This embodiment provides a method for preparing an ion-conducting elastomer, including the following steps: (1) Mix 1-carboxymethyl-3-vinylimidazolium chloride (0.01 mol, 1.88 g) and lithium tetrafluoroborate (0.01 mol, 0.93 g) and stir continuously at room temperature for 1.5 h to obtain an alkenyl-containing ionic liquid.

[0059] (2) Add 3g of styrene-butadiene-styrene block copolymer (SBS, YH SBS 1401 (YH-792)) to 7g of acetonitrile, heat to 50℃ and stir until SBS dissolves to obtain a solution containing an elastomer matrix with an SBS mass concentration of 30%.

[0060] (3) Take 1.417g of the solution containing the elastomer matrix obtained in step (2), then add 0.5g of the ionic liquid containing the alkenyl group obtained in step (1), then add 0.025g of 3,3'-dithiobis(sulfosuccinimide propionate) and 0.05g of MXene nanosheets (Xianfeng Nano, catalog number: 102475), stir for 40min, and then sonicate for 40min to obtain the precursor solution.

[0061] (4) Add 0.005g of photoinitiator 2959 to the precursor solution obtained in step (3), mix evenly in the dark to obtain a mixture; then pour the mixture into a polytetrafluoroethylene mold, apply a directional electric field with a field strength of 20V / cm, apply the electric field for 10min, then polymerize under a 365nm wavelength ultraviolet lamp for 1min, and then place the polymerized material in a 60℃ vacuum oven to dry until the solvent is removed, to obtain an ion-conductive elastomer with a sample thickness of 1mm and a width of 100×100mm.

[0062] Example 4 This embodiment provides a method for preparing an ion-conducting elastomer, including the following steps: (1) Take 1-carboxymethyl-3-vinylimidazolium chloride (0.01mol, 1.88g) and lithium hexafluorophosphate (0.01mol, 1.52g) and stir continuously at room temperature for 2h to obtain an alkenyl-containing ionic liquid.

[0063] (2) Add 1g of styrene-ethylene-butene-styrene block copolymer (SEBS, TAIPOL 6150) to 9g of dimethyl sulfoxide, heat to 80°C and stir until SEBS dissolves to obtain a solution containing an elastomer matrix with a SEBS mass concentration of 10%.

[0064] (3) Take 5.58g of the solution containing the elastomer matrix obtained in step (2), then add 0.4g of the ionic liquid containing the alkenyl group obtained in step (1), then add 0.012g of 3,3'-dithiobis(sulfosuccinimide propionate) and 0.03g of nano vermiculite (Maclean reagent, V885843), stir for 60min, and then sonicate for 60min to obtain the precursor solution.

[0065] (4) Add 0.0012g of photoinitiator 1173 to the precursor solution obtained in step (3), mix evenly in the dark to obtain a mixture; then pour the mixture into a polytetrafluoroethylene mold, apply a directional electric field with a field strength of 5V / cm, apply the electric field for 30min, then polymerize under a 365nm wavelength ultraviolet lamp for 20min, and then place the polymerized material in an 80℃ vacuum oven to dry until the solvent is removed, to obtain an ion-conductive elastomer with a sample thickness of 1mm and a width of 100×100mm.

[0066] Example 5 group This example group refers to the preparation method of Example 1, with the only difference being: the amount of solution containing the elastomer matrix and ionic liquid containing the alkenyl group in step (3) are different, and the amount of photoinitiator 1173 in step (4) is different. The rest are the same as in Example 1. The specific differences are as follows: Example 5a: The amount of solution containing the elastomer matrix was 3.87 g, the amount of alkenyl-containing ionic liquid was 0.2 g, and the amount of photoinitiator 1173 was 0.001 g; Example 5b: The amount of solution containing the elastomer matrix was 2.37 g, the amount of alkenyl-containing ionic liquid was 0.5 g, and the amount of photoinitiator 1173 was 0.0025 g; Example 5c: The amount of solution containing the elastomer matrix was 4.12 g, the amount of alkenyl-containing ionic liquid was 0.15 g, and the amount of photoinitiator 1173 was 0.00075 g; Example 5d: The amount of solution containing the elastomer matrix was 2.12 g, the amount of ionic liquid containing alkenyl groups was 0.55 g, and the amount of photoinitiator 1173 was 0.00275 g.

[0067] Example 6 group The preparation method of this example group is the same as that of Example 1, except that the amount of solution containing elastomer matrix and nanofiller in step (3) is different. The rest are the same as in Example 1. The specific differences are as follows: Example 6a: The amount of solution containing the elastomer matrix was 3.445 g, and the amount of cellulose nanofibers was 0.005 g; Example 6b: The amount of solution containing the elastomer matrix was 3.22 g, and the amount of cellulose nanofibers was 0.05 g; Example 6c: The amount of solution containing the elastomer matrix was 3.46 g, and the amount of cellulose nanofibers was 0.002 g; Example 6d: The amount of solution containing the elastomer matrix was 3.17g, and the amount of cellulose nanofibers was 0.06g.

[0068] Example 7 group This example group refers to the preparation method of Example 1, with the only difference being: the mass concentration of the solution containing the elastomer matrix in step (2) is different, and the amount of solution containing the elastomer matrix in step (3) is different. The rest are the same as in Example 1. The specific differences are as follows: Example 7a: The mass concentration of the solution containing the elastomer matrix was 5%, and the amount of the solution containing the elastomer matrix was 13.48 g; Example 7b: The mass concentration of the solution containing the elastomer matrix was 30%, and the amount of the solution containing the elastomer matrix was 2.25g; Example 7c: The mass concentration of the solution containing the elastomer matrix was 2%, and the amount of the solution containing the elastomer matrix was 33.7g; Example 7d: The mass concentration of the solution containing the elastomer matrix was 33%, and the amount of the solution containing the elastomer matrix was 2.04g.

[0069] Example 8 group The preparation method of this embodiment group is the same as that of Example 1, except that the orientation treatment parameters in step (4) are different. The rest are the same as those of Example 1. The specific differences are as follows: Example 8a: The film scraping speed is 10 cm / s; Example 8b: The film scraping speed is 0.1 cm / s; Example 8c: The film scraping speed is 15 cm / s.

[0070] Example 9 group This example group refers to the preparation method of Example 3, the only difference being that the orientation treatment parameters in step (4) are different, and the rest are the same as in Example 3. The specific differences are as follows: Example 9a: Electric field strength is 10V / cm; Example 9b: Electric field strength is 1 V / cm; Example 9c: The electric field strength is 30V / cm.

[0071] Comparative Example 1 Comparative Example 1 provides a method for preparing an ion-conducting elastomer, comprising the following steps: (1) Add 2g of thermoplastic polyurethane (TPU, Covestro 1035AU) to 8g of acetone, heat to 40°C and stir until TPU dissolves to obtain a solution containing elastomer matrix with a TPU mass concentration of 20%.

[0072] (2) Take 3.46g of the solution containing the elastomer matrix obtained in step (1), add 0.308g of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), stir for 60min, and then sonicate for 30min to obtain a homogeneous solution.

[0073] (3) Pour the uniform solution into a polytetrafluoroethylene mold, and then place it in a vacuum oven at 60°C to dry until the solvent is removed, so as to obtain an ion-conductive elastomer with a sample thickness of 1 mm and a width of 100×100 mm.

[0074] Comparative Example 2 Comparative Example 2 provides a method for preparing an ion-conducting elastomer, comprising the following steps: (1) Add 2g of thermoplastic polyurethane (TPU, Covestro 1035AU) to 8g of acetone, heat to 40°C and stir until TPU dissolves to obtain a solution containing elastomer matrix with a TPU mass concentration of 20%.

[0075] (2) Take 3.39g of the solution containing the elastomer matrix obtained in step (1), add 0.302g of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to it, then add 0.02g of cellulose nanofibers, stir for 30min, and then sonicate for 60min to obtain a homogeneous solution.

[0076] (3) Pour the uniform solution into a polytetrafluoroethylene mold, and then place it in a vacuum oven at 60°C to dry until the solvent is removed, so as to obtain an ion-conductive elastomer with a sample thickness of 1 mm and a width of 100×100 mm.

[0077] Comparative Example 3 Comparative Example 3 follows the same preparation method as Example 1, except that the amount of each component in step (3) is different. The rest is the same as in Example 1. The specific differences are as follows: The amount of solution containing the elastomer matrix was 3.44 g, the amount of alkenyl ionic liquid was 0.306 g, the amount of bis(2-methacryloyl)oxyethyl disulfide was 0.006 g, and the amount of cellulose nanofibers was 0 g.

[0078] Experimental Example To compare and illustrate the performance differences of ion-conducting elastomers from different embodiments and comparative examples, the ion-conducting elastomers prepared in different embodiments and comparative examples were tested as follows, and the test results are shown in Table 1.

[0079] 1. Ionic conductivity: Cut the sample into circular pieces with a diameter of 15 mm and a thickness of 1 mm, sandwich them between two stainless steel gaskets with a diameter of 15 mm, and use an electrochemical workstation to measure the electrochemical impedance spectroscopy. The ionic conductivity is then calculated using the formula. ,in L For sample thickness, R For the impedance being tested, A This represents the sample cross-sectional area.

[0080] 2. Electrochemical stability window: Cut the sample into a circular piece with a diameter of 15 mm and a thickness of 1 mm, sandwich it between two stainless steel gaskets with a diameter of 15 mm, and use an electrochemical workstation to test the linear sweep voltammetry curve. Record the potential before the current shows a significant increase as the electrochemical stability window.

[0081] 3. Tensile strength: Referring to the international standard ISO 527-2:2012, the sample was formed on a 1BB dumbbell mold and tensile test was performed using a universal mechanical testing machine. The maximum tensile stress was recorded as the tensile strength.

[0082] 4. Elongation at break: Referring to the international standard ISO 527-2:2012, the sample was formed on a 1BB dumbbell mold and tensile test was performed using a universal mechanical testing machine. The strain at the point of fracture was recorded as the elongation at break.

[0083] 5. Elastic Modulus: Referring to the international standard ISO 527-2:2012, the sample was molded on a 1BB dumbbell-shaped mold and subjected to tensile testing using a universal testing machine. The slope of the stress-strain curve during the elastic deformation stage was calculated, which is the elastic modulus. ,in For stress, In response to the situation.

[0084] 6. Hysteresis: Referring to the international standard ISO 527-2:2012, the sample was formed on a 1BB dumbbell mold and tensile test was performed using a universal mechanical testing machine; the hysteresis is defined as the percentage of strain when the stress is zero under a loading-unloading cycle at 100% elongation; the lower the hysteresis, the better the material's resilience. 7. Self-healing: After the sample is cut flat, the broken ends are rejoined. After being placed at room temperature for 24 hours, the tensile mechanical properties of the sample before and after cutting are tested according to the international standard ISO 527-2:2012. The self-healing rate = (tensile strength after cutting) / (initial tensile strength) × 100%; 8. Cyclic durability performance: In accordance with the international standard ISO 527-2:2012, the sample is molded on a 1BB dumbbell mold and subjected to tensile testing using a universal mechanical testing machine; the durability test is performed by loading-unloading cycles at 100% elongation. When the stress decreases by more than 10% from the initial stress at 100% elongation, the cycle is stopped and the current number of cycles is recorded; the more cycles, the better the material durability.

[0085] Table 1 Performance test results of different ion-conductive elastomers

[0086] The test results above show that, in the preferred embodiments of the present invention, the ion-conductive elastomer sample has a certain ion conductivity and an electrochemical stability window higher than 5V, and has a low hysteresis rate and good cycle durability, and can be used as a sensitive layer for ionized pressure sensors.

[0087] Furthermore, ion-conducting elastomers prepared in different embodiments and comparative examples were used as the sensitive layer to fabricate an ionized pressure sensor. The specific fabrication method included: stacking an upper electrode, a sensitive layer, and a lower electrode; then, after leading out wires, encapsulating the sensor with two 20μm thick, plasma-treated silicone rubber films to obtain the sensor under test; wherein both the upper and lower electrodes were polyimide films plated with metallic copper. The sensor under test was subjected to the following tests, and the test results are shown in Table 2.

[0088] 1. Sensitivity: Referring to the group standard T / QGCML 4624-2024 "Calibration Test Method for Flexible Thin Film Pressure Sensors", the electrical signal of the sensor under different pressures was tested. The pressure was applied using a universal electromechanical apparatus, and the electrical signal was acquired using an LCR digital bridge. Sensitivity was defined as S = ( C / C0) / P, where C represents the change in capacitance after applying a given pressure. P represents the pressure difference; 2. Measurement Range: Refer to the group standard T / QGCML 4624-2024 "Calibration Test Method for Flexible Thin Film Pressure Sensors" to test the electrical signal of the sensor under different pressures. The pressure is applied by a universal electromechanical instrument, and the electrical signal is acquired by an LCR digital bridge. The measurement range is defined as the minimum and maximum pressure at which the sensor generates a response electrical signal. 3. Response time: Refer to the group standard T / QGCML 4624-2024 "Calibration and Test Method of Flexible Thin Film Pressure Sensor" to test the electrical signal of the sensor under a fixed pressure (100kPa). The pressure is applied by a universal electromechanical machine, and the electrical signal is acquired by an LCR digital bridge. The response time is defined as the duration for a complete response to be generated in the electrical signal-time curve after the pressure is applied. 4. Signal drift rate: Refer to He, Y., Cheng, Y., Yang, C. et al. Creep-free polyelectrolyte elastomer for drift-free iontronic sensing. Nat. Mater. 23,1107–1114 (2024). https: / / doi.org / 10.1038 / s41563-024-01848-6. The signal drift rate is the percentage change in capacitance value from the initial value after 1 hour at a given pressure of 100 kPa. A lower drift rate indicates more stable sensor performance. 5. Cycle life: Refer to He, Y., Cheng, Y., Yang, C. et al. Creep-free polyelectrolyte elastomer for drift-free iontronic sensing. Nat. Mater. 23,1107–1114 (2024). https: / / doi.org / 10.1038 / s41563-024-01848-6. The cycle life test involves loading and unloading cycles under a pressure of 100 kPa. When the rate of change of the response capacitance value from the initial response capacitance value exceeds 10%, the cycle is stopped, and the current cycle number is recorded. The more cycles, the longer the sensor's cycle life. 6. Multidimensional force decoupling: Reference, Xu Decheng, Wang Haonan, Feng Yanlai, et al. Design and application research of capacitive three-dimensional force flexible tactile sensor [J]. Journal of Jilin Normal University (Natural Science Edition), 2024(4). The multidimensional force decoupling capability (%) is to apply pure normal pressure (1N) and shear force with the same normal component (45° to the normal, 1.41N) respectively, and test the sensor signal change rate. The higher the change rate, the more obvious the signal difference is generated in the normal and tangential directions due to the anisotropy of mechanics / electricity, which is conducive to the decoupling and identification of multidimensional forces.

[0089] Table 2 Performance test results of different sensors

[0090] The test results above show that the ion-conductive pressure sensor obtained by using the ion-conductive elastic system within the preferred range of the present invention has good sensitivity and wide range, and has significant advantages in response time, signal drift, cycle life and multidimensional force decoupling.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an ion-conducting elastomer, characterized in that, Includes the following steps: (a) A precursor solution is obtained by mixing an alkenyl-containing ionic liquid, an elastomer-containing matrix solution, a disulfide-containing crosslinking agent, and a nanofiller; Based on the total mass of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-containing crosslinking agent, and the nanofiller being 100%, the amounts of the alkenyl-containing ionic liquid, the elastomer matrix, the disulfide-containing crosslinking agent, and the nanofiller are 20%~50%, 42.5%~79.4%, 0.1%~2.5%, and 0.5%~5%, respectively. (b) The precursor solution is mixed with the initiator and oriented, then a polymerization reaction is initiated, and the mixture is dried to obtain an ion-conductive elastomer; The orientation process includes applying a directional electric field or a shear force to the homogeneously mixed solution.

2. The preparation method according to claim 1, characterized in that, It has at least one of the following characteristics: (1) The elastomer matrix includes at least one of thermoplastic polyurethane, ethylene-vinyl acetate elastomer and styrene block copolymer; (2) In the solution containing the elastomer matrix, the mass concentration of the elastomer matrix is ​​5%~30%; (3) In the solution containing the elastomer matrix, the solvent includes at least one of acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that, The raw materials for preparing the alkenyl-containing ionic liquid include: alkenyl-containing zwitterionic salts and lithium salts; The alkenyl-containing zwitterionic salt includes at least one of 1-carboxymethyl-3-vinylimidazolium chloride, 1-sulfopropyl-3-vinylimidazolium inner salt, and 1-(carboxymethyl)-3-vinyl-1H-imidazolium bromide; The lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, and lithium hexafluorophosphate.

4. The preparation method according to claim 1, characterized in that, It has at least one of the following characteristics: (1) The crosslinking agent containing disulfide bonds includes at least one of bis(2-methacryloyl)oxyethyl disulfide and 3,3'-disulfide bis(sulfosuccinimide propionate); (2) The nanofiller includes at least one of cellulose nanofibers, nano molecular sieves, MXene nanosheets, graphene oxide nanosheets, nano vermiculite and nano clay.

5. The preparation method according to claim 1, characterized in that, In step (b), the mass of the initiator is 0.1% to 1% of the mass of the alkenyl-containing ionic liquid in the precursor solution; The initiator includes at least one of a photoinitiator and a thermal initiator.

6. The preparation method according to claim 1, characterized in that, When applying the directional electric field, the field strength is 5~20V / cm, and the processing time is 10~30min.

7. The preparation method according to claim 1, characterized in that, When applying shear force, a shear force is provided by scraping the solution with a scraper, and the scraping speed is 1~10cm / s.

8. The preparation method according to claim 1, characterized in that, Polymerization reactions are initiated by ultraviolet light irradiation or heating; The polymerization reaction takes 1 to 30 minutes.

9. An ion-conducting elastomer, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. An ionized pressure sensor, characterized in that, Includes the ion-conductive elastomer as described in claim 9.

Images