Thermoelectric hydrogels enhanced by the synergistic effect of zwitterionic and polar solvents, their methods and applications

Abstract

This invention belongs to the technical field of thermoelectric materials and functional polymer materials, specifically relating to a thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents, its method, and applications. The thermoelectric hydrogel is obtained by polymerizing a precursor solution to form a gel matrix, followed by immersion in an immersion solution to introduce a potassium ferrocyanide / potassium ferrocyanide redox couple. The precursor solution is prepared by mixing acrylamide, N-isopropylacrylamide, dimethyl sulfoxide, N,N-dimethylformamide, 1-ethyl-3-methylimidazolium tetrafluoroborate, the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide, the crosslinking agent N,N'-methylenebisacrylamide, a photoinitiator, and deionized water. This invention prepares a thermoelectric hydrogel with high mechanical strength, high ductility, and a high Seebeck coefficient, and also exhibits good temperature resistance.

Description

Technical Field

[0001] This invention belongs to the technical field of thermoelectric materials and functional polymer materials, specifically relating to thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents, their methods and applications. Background Technology

[0002] Low-grade heat energy is widely distributed in nature and in waste heat generated by industrial production, but its monitoring and utilization are quite difficult. If this heat energy can be collected in a reasonable way, it will create huge economic benefits.

[0003] Currently, among the many technologies that convert thermal energy into electrical energy, thermoelectric cells have attracted much attention due to their unique advantages. For example, those based on p-type redox couples (e.g., [Fe(CN)6]) 3- / 4- The quasi-solid-state hydrogel thermal battery constructed using this technology has advantages such as environmental friendliness and low cost. However, existing thermoelectric chemical batteries still face some key challenges that urgently need to be addressed in practical applications:

[0004] Firstly, its mechanical properties are inadequate: traditional hydrogels are relatively fragile and cannot withstand large deformations, resulting in generally low mechanical strength. Flexible devices often require materials with good flexibility and mechanical strength to adapt to various complex working environments, and this deficiency greatly limits its application in the field of flexible devices.

[0005] Secondly, the thermoelectric conversion efficiency is low: due to the conventional entropy difference of ions in aqueous solution, the Seebeck coefficient of the traditional potassium ferricyanide system is generally low, resulting in insufficient output power of the thermal battery, which is difficult to meet the power supply needs of practical applications.

[0006] Third, insufficient temperature resistance: Conventional hydrogels are prone to water loss and hardening or phase change in high-temperature environments (temperatures exceeding 80°C), making them unsuitable for working environments with high-temperature heat sources such as engine surfaces, thus limiting their application range in high-temperature scenarios.

[0007] Therefore, there is an urgent need to develop a thermoelectric hydrogel with high mechanical strength, high ductility, high Seebeck coefficient, and good temperature resistance to improve the application efficiency of thermoelectric chemical batteries and expand their practical application range. Summary of the Invention

[0008] To address the shortcomings of the existing technologies, this invention provides thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents, along with their methods and applications, to solve the problems of poor mechanical properties, low thermoelectric conversion efficiency, and insufficient temperature resistance in existing hydrogels.

[0009] The first aspect of this invention provides a thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents. This thermoelectric hydrogel is obtained by polymerizing a precursor solution to form a gel matrix, followed by immersion in an immersion solution to introduce a potassium ferrocyanide / potassium ferrocyanide redox couple, wherein:

[0010] The precursor solution is prepared by mixing acrylamide AM, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, crosslinking agent, photoinitiator, and deionized water. The mass ratio of acrylamide AM to deionized water is 1:8–20, the mass ratio of N-isopropylacrylamide NIPAM to deionized water is 1:20–100, and the mass ratio of dimethyl sulfoxide DMF is... The mass ratio of MSO to deionized water is 1:1 to 4; the mass ratio of N,N-dimethylformamide (DMF) to deionized water is 1:1 to 3; the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to deionized water is 1:20 to 100; the mass ratio of zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to deionized water is 1:4 to 12; the mass ratio of crosslinking agent to deionized water is 1:500 to 2000; and the mass ratio of photoinitiator to deionized water is 1:500 to 2000.

[0011] The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water, and the concentrations of potassium ferricyanide K3[Fe(CN)6] and potassium ferrocyanide K4[Fe(CN)6] in the soaking solution are 0.1-0.4M, respectively.

[0012] Preferably, the crosslinking agent is N,N'-methylenebisacrylamide (BIS), and the photoinitiator is Irgacure 184.

[0013] Preferably, the concentration of the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA in the precursor solution is 0.3–0.9 M.

[0014] A second aspect of this invention provides a method for preparing a thermoelectric hydrogel based on the synergistic enhancement of zwitterions and polar solvents, comprising the following steps:

[0015] S1. Prepare the precursor solution at room temperature;

[0016] S2. Pour the precursor solution obtained in step S1 into a polytetrafluoroethylene mold and carry out ultraviolet light polymerization under a nitrogen atmosphere to obtain a gel matrix. The ultraviolet light polymerization reaction is carried out at an intensity of 100 mW / cm². 2 The exposure time is 10–30 minutes;

[0017] S3. The gel matrix obtained in step S2 is soaked in the soaking solution for 1 to 6 hours and then taken out. The soaked gel matrix is ​​then washed with deionized water for 3 minutes to obtain a thermoelectric hydrogel. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water and stirring at room temperature for 1 hour.

[0018] Preferably, step S1 specifically includes:

[0019] S11. Mix dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and deionized water, and stir for 30 minutes to obtain a polar solvent.

[0020] S12. Acrylamide AM, N-isopropylacrylamide NIPAM, crosslinking agent and polar solvent are mixed and stirred for 3 hours to obtain the initial precursor solution, wherein the crosslinking agent is N,N'-methylenebisacrylamide BIS.

[0021] S13. Add zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to the initial precursor solution, stir for 1-6 h, then add photoinitiator and stir for 1-6 h to obtain the target precursor solution.

[0022] Preferably, the prepared thermoelectric hydrogel has a Seebeck coefficient ≥15.534mV / K and a tensile stress ≥39.3kPa.

[0023] The third aspect of this invention provides the application of thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents. The thermoelectric hydrogels are prepared by a method based on the synergistic enhancement of zwitterionic and polar solvents and are suitable for thermoelectric materials and devices, and sensing and monitoring fields.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention addresses the problem that hydrogels in existing thermoelectrochemical batteries struggle to balance mechanical and electrochemical performance by introducing the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propionic)ammonium hydroxide SBMA and a polar solvent made of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF).

[0026] 2. This invention introduces 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], which generates a synergistic water-locking effect with polar solvents, thereby endowing the thermoelectric hydrogel with excellent dehydration resistance, so that the prepared thermoelectric hydrogel can maintain its electrochemical and mechanical properties for a long time even without encapsulation.

[0027] 3. This invention introduces 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], enabling the negatively charged sulfonate group in the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA to exert a strong electrostatic anchoring effect, thereby effectively immobilizing free EMIM. + Ions, and also promote the anion BF4 - The heat diffuses freely towards the cold end, further amplifying the heat diffusion effect.

[0028] 4. This invention uses acrylamide AM and N-isopropylacrylamide NIPAM as the polymer backbone, introduces dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) to regulate the polymer molecular chain arrangement, and enhances intermolecular interactions through the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to regulate the ionic solvation structure, thereby achieving a synergistic improvement in the mechanical and electrochemical properties of the thermoelectric hydrogel.

[0029] 5. The thermoelectric hydrogel prepared by this invention has good electrochemical and mechanical properties, and has good application prospects in the fields of thermoelectric materials and devices, and sensing and monitoring. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram illustrating the structural principle of the thermoelectric hydrogel in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram illustrating the thermoelectric working principle of the thermoelectric hydrogel in an embodiment of the present invention.

[0033] Figure 3 This is a scanning electron microscope image of the thermoelectric hydrogel in an embodiment of the present invention;

[0034] Figure 4The Fourier transform infrared spectra of the thermoelectric hydrogel and the pure acrylamide PAM hydrogel in the embodiments of the present invention are shown below.

[0035] Figure 5 This is a voltage-current density curve of the thermoelectric hydrogel prepared in Example 1 of the present invention;

[0036] Figure 6 This is a voltage-power density curve of the thermoelectric hydrogel prepared in Example 1 of the present invention;

[0037] Figure 7 This is a comparison of the tensile fracture stress-strain curves of the thermoelectric hydrogel prepared in Example 1 of the present invention and the pure acrylamide PAM hydrogel. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] The first aspect of this invention provides a thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents. This thermoelectric hydrogel is obtained by polymerizing a precursor solution to form a gel matrix, followed by immersion in an immersion solution to introduce a potassium ferrocyanide / potassium ferrocyanide redox couple, wherein:

[0041] The precursor solution is prepared by mixing acrylamide AM, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, crosslinking agent, photoinitiator, and deionized water. The mass ratio of acrylamide AM to deionized water is 1:8–20, the mass ratio of N-isopropylacrylamide NIPAM to deionized water is 1:20–100, and the mass ratio of dimethyl sulfoxide DMF is... The mass ratio of MSO to deionized water is 1:1 to 4; the mass ratio of N,N-dimethylformamide (DMF) to deionized water is 1:1 to 3; the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to deionized water is 1:20 to 100; the mass ratio of zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to deionized water is 1:4 to 12; the mass ratio of crosslinking agent to deionized water is 1:500 to 2000; and the mass ratio of photoinitiator to deionized water is 1:500 to 2000.

[0042] The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water, and the concentrations of potassium ferricyanide K3[Fe(CN)6] and potassium ferrocyanide K4[Fe(CN)6] in the soaking solution are 0.1-0.4M, respectively.

[0043] It should be noted that, for ease of explanation, the term "thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents" will be abbreviated as "thermoelectric hydrogel" in this article.

[0044] In this application, the crosslinking agent is N,N'-methylenebisacrylamide (BIS), and the photoinitiator is Irgacure 184.

[0045] Preferably, the concentration of the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA in the precursor solution is 0.3–0.9 M.

[0046] This invention uses acrylamide AM and N-isopropylacrylamide NIPAM as the polymer backbone, introduces dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) to regulate the polymer molecular chain arrangement, and enhances intermolecular interactions through the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to regulate the ionic solvation structure, thereby achieving a synergistic improvement in the mechanical and electrochemical properties of the thermoelectric hydrogel.

[0047] In this invention, the sulfonate and hydrophilic groups in the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA can form ion-dipole interactions and hydrogen bonds with the amide groups in the polymerization network, thereby enhancing the network cohesive energy and improving mechanical stability. At the same time, the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA can also change the ion solvation structure, adjust the entropy difference of the redox couple, and improve the Seebeck coefficient.

[0048] A second aspect of this invention provides a method for preparing a thermoelectric hydrogel based on the synergistic enhancement of zwitterions and polar solvents, comprising the following steps:

[0049] S1. Prepare the precursor solution at room temperature.

[0050] In this application, step S1 specifically includes:

[0051] S11. Mix dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and deionized water, and stir for 30 minutes to obtain a polar solvent.

[0052] This invention uses a mixture of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) as a polar solvent, which can effectively improve the ordered arrangement of molecular chains in the polymer network, so that the load is shared by more molecular chains, the force transmission between chain segments is more efficient, and the tensile strength and elastic modulus are significantly improved, thereby achieving the purpose of improving the mechanical properties of thermoelectric hydrogels.

[0053] S12. Acrylamide AM, N-isopropylacrylamide NIPAM, crosslinking agent and polar solvent are mixed and stirred for 3 hours to obtain the initial precursor solution, wherein the crosslinking agent is N,N'-methylenebisacrylamide BIS.

[0054] S13. Add zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to the initial precursor solution, stir for 1-6 h, then add photoinitiator and stir for 1-6 h to obtain the target precursor solution.

[0055] S2. Pour the precursor solution obtained in step S1 into a polytetrafluoroethylene mold and carry out ultraviolet light polymerization under a nitrogen atmosphere to obtain a gel matrix. The ultraviolet light polymerization reaction is carried out at an intensity of 100 mW / cm². 2 The exposure time is 10 to 30 minutes.

[0056] S3. The gel matrix obtained in step S2 is soaked in the soaking solution for 1 to 6 hours and then taken out. The soaked gel matrix is ​​then washed with deionized water for 3 minutes to obtain a thermoelectric hydrogel. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water and stirring at room temperature for 1 hour.

[0057] In this invention, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] serves as a thermoelectric ion, playing multiple roles in the thermoelectric hydrogel prepared by this invention: Firstly, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] reacts with [Fe(CN)6]... 3- / 4- There is a significant dual synergistic effect between the two components, which significantly enhances the overall Seebeck coefficient. Furthermore, with optimized concentration, the system can generate a higher thermal voltage. Secondly, there is a synergistic water-locking effect between 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] and the polar solvent. This synergistic effect endows the thermoelectric hydrogel with excellent dehydration resistance, maintaining its electrochemical and mechanical properties even under unencapsulated conditions for a long time, thus significantly improving its temperature resistance. Finally, in the microstructure of the thermoelectric hydrogel, the negatively charged sulfonate groups in the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA exert a strong electrostatic anchoring effect, effectively immobilizing free EMIM. + Ions, while promoting the anion BF4 - The free migration towards the cold end, this selective ion transport mechanism, further amplifies the thermal diffusion effect, superimposing the macroscopic polarization potential on the redox potential, and significantly expanding the effect of thermal diffusion.

[0058] The structural principle of the thermoelectric hydrogel prepared by this invention is as follows: Figure 1 As shown. By Figure 1It is known that the zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide (SBMA) and N-isopropylacrylamide (NIPAM) polymerize to form a network. After solvent exchange, potassium ferricyanide (K3) [Fe(CN)6] and potassium ferrocyanide (K4) [Fe(CN)6] are immersed in the thermoelectric hydrogel. The ions are dispersed within the aqueous network and interact with the hydration environment surrounding the polymer chains. The polar atoms on the polymer chains, such as N and O, form a stable solvation microenvironment with water molecules and ferricyanide anions through electrostatic interactions and hydrogen bonding / hydration, allowing the ions to remain mobile within the network but confined to the gel channels. Under a temperature gradient, the ions and redox couples inside the gel undergo thermo-induced migration and distribution differences, thereby generating ion concentration and potential differences at both ends, achieving a thermoelectric response. At the same time, the thermosensitive properties of N-isopropylacrylamide (NIPAM) and the strong hydration / charge properties of the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) jointly regulate the intensity of ion transport and thermal response.

[0059] Figure 2 This is a schematic diagram illustrating the thermoelectric working principle of the thermoelectric hydrogel in an embodiment of the present invention. Figure 2 It is known that under the action of a temperature gradient, the ferricyanide / ferrous cyanide redox couple undergoes a reversible redox reaction, generating a potential difference that can be used to continuously power the load equipment.

[0060] Figure 3 This is a scanning electron microscope image of the thermoelectric hydrogel prepared according to the present invention. Figure 3 It is known that the thermoelectric hydrogel prepared by this invention has a three-dimensional cross-linked network with uniformly distributed microporous structure on its surface, which can provide a good ion channel for improving electrochemical performance.

[0061] Furthermore, the present invention also performed Fourier transform infrared spectroscopy analysis on the thermoelectric hydrogel prepared according to this method and the traditional pure acrylamide PAM hydrogel, such as... Figure 4 As shown. By Figure 4 It can be seen that, compared with pure acrylamide PAM hydrogel, the hydrogen bond-related absorption band in the thermoelectric hydrogel prepared by this method is significantly broadened and accompanied by peak position shift. At the same time, the intensity of some characteristic peaks changes, indicating that the intermolecular interaction in the system is enhanced and the chain segment motion is more constrained. This proves that the thermoelectric hydrogel prepared by this method has a more stable and denser composite network structure.

[0062] In this application, the prepared thermoelectric hydrogel has a Seebeck coefficient ≥15.534mV / K and a tensile stress ≥39.3kPa.

[0063] It should be noted that the acrylamide AM, zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] and photoinitiator used in this application were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., N,N'-methylenebisacrylamide BIS and deionized water were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and potassium ferricyanide K3 [Fe(CN)6] and potassium ferrocyanide K4 [Fe(CN)6] were purchased from Tianjin Damao Technology Co., Ltd.

[0064] The third aspect of this invention provides the application of thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents. The thermoelectric hydrogels are prepared by a method based on the synergistic enhancement of zwitterionic and polar solvents and are suitable for thermoelectric materials and devices, and sensing and monitoring fields.

[0065] Based on the aforementioned method for preparing thermoelectric hydrogels based on the synergistic enhancement of zwitterions and polar solvents, the present invention conducted the following experiments to prepare thermoelectric hydrogels based on the synergistic enhancement of zwitterions and polar solvents.

[0066] Example 1

[0067] I. Prepare raw materials:

[0068] (1) Precursor solution raw materials: Acrylamide AM, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, crosslinking agent N,N'-methylenebisacrylamide BIS, photoinitiator Irgacure 184, and deionized water, wherein the mass ratio of acrylamide AM to deionized water is 1:10, and the mass ratio of N-isopropylacrylamide NIPAM to deionized water is 1:10. The mass ratio of dimethyl sulfoxide (DMSO) to deionized water is 1:2; the mass ratio of N,N-dimethylformamide (DMF) to deionized water is 1:1; the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to deionized water is 1:20; the mass ratio of zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to deionized water is 1:4; the mass ratio of crosslinking agent N,N'-methylenebisacrylamide (BIS) to deionized water is 1:500; and the mass ratio of photoinitiator Irgacure 184 to deionized water is 1:500.

[0069] (2) Raw materials for the soaking solution: potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water. The concentrations of potassium ferricyanide K3[Fe(CN)6] and potassium ferrocyanide K4[Fe(CN)6] in the soaking solution are 0.4M.

[0070] II. Preparation of thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents

[0071] S1. Prepare the precursor solution at room temperature, specifically as follows:

[0072] S11. Mix dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and deionized water, and stir for 30 minutes to obtain a polar solvent.

[0073] S12. Acrylamide AM, N-isopropylacrylamide NIPAM, crosslinking agent N,N'-methylenebisacrylamide BIS and polar solvent are mixed and stirred for 3 hours to obtain the initial precursor solution.

[0074] S13. Add zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to the initial precursor solution, stir for 6 h, then add photoinitiator Irgacure184, stir for 6 h to obtain the target precursor solution;

[0075] S2. Pour the precursor solution obtained in step S1 into a polytetrafluoroethylene mold and carry out ultraviolet light polymerization under a nitrogen atmosphere to obtain a gel matrix. The ultraviolet light polymerization reaction is carried out at an intensity of 100 mW / cm². 2 The exposure time is 30 minutes;

[0076] S3. The gel matrix obtained in step S2 is soaked in the soaking solution for 6 hours and then taken out. The soaked gel matrix is ​​then washed with deionized water for 3 minutes to obtain a thermoelectric hydrogel. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water and stirring at room temperature for 1 hour.

[0077] In this experiment, the current density, voltage, and power density of the thermoelectric hydrogel prepared in Example 1 were tested under a temperature gradient of 50 K, and voltage-current density curves and voltage-power density curves were plotted, as shown below. Figure 5-6 As shown. By Figure 5-6 It can be seen that, under a temperature gradient of 50K, the maximum open-circuit voltage of the thermoelectric hydrogel prepared in Example 1 of this invention reaches 82.12mV, and the short-circuit current density rises to approximately 74.36A / m.2 The maximum power density increased to approximately 1516.9 mW / m³. 2 .

[0078] In addition, by Figure 5 As can be seen from the voltage-current density curves, the thermoelectric hydrogel prepared in this invention possesses good ohmic contact characteristics and stable charge transport capabilities, enabling it to generate stable electrical output under temperature difference driving, and exhibiting excellent thermoelectric conversion performance. Figure 6 The voltage-power density curves show that the thermoelectric hydrogel prepared in this invention has high effective output capacity and energy conversion efficiency. These results further confirm that the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA matrix introduced in this invention effectively ensures high ion selectivity, thereby maximizing the thermal diffusion effect; simultaneously, the introduced high-concentration potassium ferrocyanide / potassium ferrocyanide redox couple also provides strong thermoelectric motive force and abundant charge carriers, effectively reducing internal resistance.

[0079] In addition, the thermoelectric hydrogel prepared in Example 1 of this invention and the traditional pure acrylamide PAM hydrogel were tested for tensile fracture properties in this experiment, and the results are as follows: Figure 7 As shown. By Figure 7 It can be seen that the stress-strain curve of pure acrylamide PAM hydrogel is generally low, and it fractures at approximately 200% strain with a fracture stress of about 1 kPa, indicating low mechanical strength and poor ductility. In contrast, the thermoelectric hydrogel prepared in Example 1 of this invention exhibits a significantly higher stress response during stretching, with a stress reaching 50.4 kPa and a strain of 802%, demonstrating excellent stretchability and fracture resistance. This comparative result shows that the thermoelectric hydrogel prepared in this invention has superior ductility and mechanical strength compared to pure acrylamide PAM hydrogel. Furthermore, it further confirms the superiority of the thermoelectric hydrogel and its preparation method based on the synergistic enhancement of zwitterionic and polar solvents provided in this invention.

[0080] Example 2

[0081] I. Prepare raw materials:

[0082] (1) Precursor solution raw materials: Acrylamide AM, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, crosslinking agent N,N'-methylenebisacrylamide BIS, photoinitiator Irgacure 184, and deionized water, wherein the mass ratio of acrylamide AM to deionized water is 1:8, and the mass ratio of N-isopropylacrylamide NIPAM to deionized water is 1:8. The mass ratio of dimethyl sulfoxide (DMSO) to deionized water is 1:1; the mass ratio of N,N-dimethylformamide (DMF) to deionized water is 1:1; the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to deionized water is 1:20; the mass ratio of zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to deionized water is 1:4; the mass ratio of crosslinking agent N,N'-methylenebisacrylamide (BIS) to deionized water is 1:500; and the mass ratio of photoinitiator Irgacure 184 to deionized water is 1:500.

[0083] (2) Raw materials for the soaking solution: potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water. The concentrations of potassium ferricyanide K3[Fe(CN)6] and potassium ferrocyanide K4[Fe(CN)6] in the soaking solution are 0.4M.

[0084] II. Preparation of thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents

[0085] S1. Prepare the precursor solution at room temperature, specifically as follows:

[0086] S11. Mix dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and deionized water, and stir for 30 minutes to obtain a polar solvent.

[0087] S12. Acrylamide AM, N-isopropylacrylamide NIPAM, crosslinking agent N,N'-methylenebisacrylamide BIS and polar solvent are mixed and stirred for 3 hours to obtain the initial precursor solution.

[0088] S13. Add zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to the initial precursor solution, stir for 6 h, then add photoinitiator Irgacure184, stir for 6 h to obtain the target precursor solution;

[0089] S2. Pour the precursor solution obtained in step S1 into a polytetrafluoroethylene mold and carry out ultraviolet light polymerization under a nitrogen atmosphere to obtain a gel matrix. The ultraviolet light polymerization reaction is carried out at an intensity of 100 mW / cm². 2 The exposure time is 30 minutes;

[0090] S3. The gel matrix obtained in step S2 is soaked in the soaking solution for 6 hours and then taken out. The soaked gel matrix is ​​then washed with deionized water for 3 minutes to obtain a thermoelectric hydrogel. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water and stirring at room temperature for 1 hour.

[0091] Example 3

[0092] I. Prepare raw materials:

[0093] (1) Precursor solution raw materials: Acrylamide AM, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, crosslinking agent N,N'-methylenebisacrylamide BIS, photoinitiator Irgacure184 and deionized water, wherein the mass ratio of acrylamide AM to deionized water is 1:20, and the mass ratio of N-isopropylacrylamide NIPAM to deionized water is 1:1. The mass ratio of dimethyl sulfoxide (DMSO) to deionized water is 1:4; the mass ratio of N,N-dimethylformamide (DMF) to deionized water is 1:3; the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to deionized water is 1:100; the mass ratio of zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to deionized water is 1:12; the mass ratio of crosslinking agent N,N'-methylenebisacrylamide (BIS) to deionized water is 1:2000; and the mass ratio of photoinitiator Irgacure 184 to deionized water is 1:2000.

[0094] (2) Raw materials for the soaking solution: potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water. The concentrations of potassium ferricyanide K3[Fe(CN)6] and potassium ferrocyanide K4[Fe(CN)6] in the soaking solution are 0.1M.

[0095] II. Preparation of thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents

[0096] S1. Prepare the precursor solution at room temperature, specifically as follows:

[0097] S11. Mix dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and deionized water, and stir for 30 minutes to obtain a polar solvent.

[0098] S12. Acrylamide AM, N-isopropylacrylamide NIPAM, crosslinking agent N,N'-methylenebisacrylamide BIS and polar solvent are mixed and stirred for 3 hours to obtain the initial precursor solution.

[0099] S13. Add zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to the initial precursor solution, stir for 1 h, then add photoinitiator Irgacure184, stir for 1 h to obtain the target precursor solution;

[0100] S2. Pour the precursor solution obtained in step S1 into a polytetrafluoroethylene mold and carry out ultraviolet light polymerization under a nitrogen atmosphere to obtain a gel matrix. The ultraviolet light polymerization reaction is carried out at an intensity of 100 mW / cm². 2 The exposure time is 10 minutes;

[0101] S3. The gel matrix obtained in step S2 is soaked in the soaking solution for 1 hour and then taken out. The soaked gel matrix is ​​then washed with deionized water for 3 minutes to obtain a thermoelectric hydrogel. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water and stirring at room temperature for 1 hour.

[0102] Comparative Example 1

[0103] Unlike Example 3, in Comparative Example 1, the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA was not added when preparing the precursor solution; at the same time, in preparing the precursor solution, step S13 was as follows: 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] was added to the initial precursor solution and stirred for 1 h, followed by the addition of photoinitiator Irgacure184 and stirring for 1 h to obtain the target precursor solution.

[0104] Comparative Example 2

[0105] Unlike Example 3, in Comparative Example 2, N-isopropylacrylamide (NIPAM) was not added when preparing the precursor solution. Meanwhile, in preparing the precursor solution, step S12 was as follows: acrylamide AM, crosslinking agent N,N'-methylenebisacrylamide (BIS), and a polar solvent were mixed and stirred for 3 hours to obtain the initial precursor solution.

[0106] Performance testing: thermoelectric performance testing and mechanical performance testing.

[0107] In this experiment, the thermoelectric hydrogel sample used for performance testing was rectangular, with dimensions of 50 mm × 20 mm × 2 mm.

[0108] Thermoelectric performance testing: Thermoelectric performance was characterized using a custom-designed measurement system equipped with a heating stage to establish a temperature gradient, with the cold end at room temperature and the hot end at 110°C. A Keithley 2450 source meter was used for electrical data acquisition. After thermal stabilization, the thermoelectric electromotive force generated across the thermoelectric hydrogel was recorded. The Seebeck coefficient (Se) was calculated based on the linear relationship between the induced potential difference and the applied temperature gradient (Se = -ΔV / ΔT). Tests were conducted at room temperature.

[0109] Mechanical performance testing: The thermoelectric hydrogel was subjected to tensile testing using a universal testing machine at an ambient temperature of 298K and a relative humidity of 50% at a loading rate of 50mm / min.

[0110] The thermoelectric hydrogels prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The thermoelectric performance test data are recorded in Table 1, and the mechanical performance test data are recorded in Table 2.

[0111]

[0112]

[0113] As can be clearly seen from Tables 1 and 2, the thermoelectric hydrogels prepared in Examples 1-3 are significantly superior to those prepared in Comparative Examples 1-2 in both thermoelectric and mechanical properties. Specifically, the thermoelectric hydrogel prepared in Comparative Example 1, due to the absence of the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA, cannot achieve a synergistic effect with 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4]. Consequently, the prepared thermoelectric hydrogel not only has the lowest level of thermoelectric and mechanical properties but also exhibits a highly significant difference compared to the thermoelectric hydrogels prepared in Examples 1-3. The thermoelectric hydrogel prepared in Comparative Example 2, due to the absence of N-isopropylacrylamide (NIPAM), cannot interact with the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA). As a result, although the prepared thermoelectric hydrogel has better thermoelectric and mechanical properties than the thermoelectric hydrogel prepared in Comparative Example 1, it still shows a significant difference compared to the thermoelectric hydrogels prepared in Examples 1-3.

[0114] Furthermore, Tables 1 and 2 clearly show that as the content of the zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and N-isopropylacrylamide NIPAM gradually increases, the prepared thermoelectric hydrogel exhibits significant improvement and optimization in both thermoelectric and mechanical properties, as seen in Examples 1 and 2. Conversely, when the content of the zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and N-isopropylacrylamide NIPAM gradually decreases, the prepared thermoelectric hydrogel shows a gradual decline in both thermoelectric and mechanical properties, as seen in Example 3. Therefore, it can be concluded that the introduction and content of the zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and N-isopropylacrylamide NIPAM have a crucial impact on the comprehensive thermoelectric and mechanical properties of the thermoelectric hydrogel.

[0115] In this invention, the polar solvent composed of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and deionized water can induce controllable microphase separation in the polymer network during gelation, promoting the aggregation of polymer chains to form continuous dense wall layers and a porous honeycomb structure. This highly ordered arrangement allows the mechanical load applied externally to be shared by more molecular chains, thereby significantly enhancing the tensile strength and toughness of the thermoelectric hydrogel. Secondly, the strong hydrogen bonds and dipole interactions formed between N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and the polymer network optimize the internal chemical environment. The induced highly porous structure not only provides abundant low-resistance channels for rapid ion migration but also effectively improves thermoelectric properties. Therefore, the performance characterization results of the thermoelectric hydrogels prepared in Examples 1-3 show that with the gradual increase of the content of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), the thermoelectric and mechanical properties of the prepared thermoelectric hydrogels exhibit a significant optimization trend.

[0116] Furthermore, this invention also uses 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] as the main source of mobile ions during thermal diffusion. Due to the special cation anchoring effect of the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA matrix, the larger cation EMIM... + The negatively charged sulfonate groups in the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA are tightly adsorbed and stably fixed by strong electrostatic interactions, while the smaller anion BF4... -Unimpeded, the charge can freely migrate towards the cold end under the temperature gradient, resulting in a large charge separation on a macroscopic scale. This polarization electric field and the thermoelectric potential of the redox couple have a synergistic superposition effect, thereby significantly increasing the overall Seebeck coefficient to an extremely high level. Therefore, the thermoelectric performance characterization results of the thermoelectric hydrogels prepared in Examples 1-3 show that with the gradual increase of the content of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], the thermoelectric performance of the prepared thermoelectric hydrogels shows a clear trend of optimization.

[0117] In summary, this invention solves the problems of poor mechanical properties, low thermoelectric conversion efficiency, and insufficient temperature resistance of hydrogels in the prior art by introducing dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-isopropylacrylamide (NIPAM), 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], and the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA). A thermoelectric hydrogel with high mechanical strength, high ductility, and a high Seebeck coefficient is prepared, and it also exhibits good temperature resistance.

[0118] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents, characterized in that, This thermoelectric hydrogel is obtained by polymerizing a precursor solution to form a gel matrix, followed by immersion in an immersion solution to introduce a potassium ferrocyanide / potassium ferrocyanide redox couple, wherein: The precursor solution is prepared by mixing acrylamide AM, N-isopropylacrylamide NIPAM, dimethyl sulfoxide DMSO, N,N-dimethylformamide DMF, 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA, crosslinking agent, photoinitiator, and deionized water. The mass ratio of acrylamide AM to deionized water is 1:8–20, the mass ratio of N-isopropylacrylamide NIPAM to deionized water is 1:20–100, and the mass ratio of dimethyl sulfoxide DMF is... The mass ratio of MSO to deionized water is 1:1 to 4; the mass ratio of N,N-dimethylformamide (DMF) to deionized water is 1:1 to 3; the mass ratio of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to deionized water is 1:20 to 100; the mass ratio of zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) to deionized water is 1:4 to 12; the mass ratio of crosslinking agent to deionized water is 1:500 to 2000; and the mass ratio of photoinitiator to deionized water is 1:500 to 2000. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water, and the concentrations of potassium ferricyanide K3[Fe(CN)6] and potassium ferrocyanide K4[Fe(CN)6] in the soaking solution are 0.1-0.4M, respectively.

2. The thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide (BIS), and the photoinitiator is Irgacure 184.

3. The thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents according to claim 1, characterized in that, The concentration of the zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide SBMA in the precursor solution is 0.3–0.9 M.

4. A method for preparing thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents, characterized in that, The method for preparing the thermoelectric hydrogel based on the synergistic enhancement of zwitterions and polar solvents as described in any one of claims 1-3 comprises the following steps: S1. Prepare the precursor solution at room temperature; S2, pouring the precursor solution prepared in step S1 into a polytetrafluoroethylene mold, and performing ultraviolet photopolymerization under a nitrogen atmosphere to obtain a gel matrix, wherein the ultraviolet photopolymerization is performed at an illumination intensity of 100 mW / cm 2 and an exposure time of 10 to 30 min; S3. The gel matrix obtained in step S2 is soaked in the soaking solution for 1 to 6 hours and then taken out. The soaked gel matrix is ​​then washed with deionized water for 3 minutes to obtain a thermoelectric hydrogel. The soaking solution is prepared by mixing potassium ferricyanide K3[Fe(CN)6], potassium ferrocyanide K4[Fe(CN)6] and deionized water and stirring at room temperature for 1 hour.

5. The method for preparing a thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents according to claim 4, characterized in that, Step S1 is as follows: S11. Mix dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and deionized water, and stir for 30 minutes to obtain a polar solvent. S12. Acrylamide AM, N-isopropylacrylamide NIPAM, crosslinking agent and polar solvent are mixed and stirred for 3 hours to obtain the initial precursor solution, wherein the crosslinking agent is N,N'-methylenebisacrylamide BIS. S13. Add zwitterionic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide SBMA and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] to the initial precursor solution, stir for 1-6 h, then add photoinitiator and stir for 1-6 h to obtain the target precursor solution.

6. The method for preparing a thermoelectric hydrogel based on the synergistic enhancement of zwitterionic and polar solvents according to claim 4, characterized in that, The prepared thermoelectric hydrogel has a Seebeck coefficient ≥15.534mV / K and a tensile stress ≥39.3kPa.

7. The application of thermoelectric hydrogels based on the synergistic enhancement of zwitterionic and polar solvents, characterized in that, The thermoelectric hydrogel is prepared by the method of any one of claims 4-6 based on the synergistic enhancement of zwitterionic and polar solvents, and is applicable to the fields of thermoelectric materials and devices, and sensing and monitoring.

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