Thermoplastic polyurethane elastomers, ionic gels and methods of making the same

Abstract

The application discloses a kind of thermoplastic polyurethane elastomer and ionic gel and its preparation method.A simple and efficient Michael addition reaction and ester ammonolysis reaction are used to prepare diamino chain extender containing amide and tertiary amine groups.The thermoplastic polyurethane elastomer material prepared using the chain extender contains amide groups, which provides additional hydrogen bonding sites, resulting in excellent mechanical properties.In addition, after the side chain of the polyurethane elastomer is modified by quaternization, the obtained quaternary ammonium salt group can act as a binding site for electrostatic force. After the ionic liquid [EMIM] [HSO4] is doped into the polyurethane elastomer, an ionic gel with excellent mechanical properties can be obtained, which can also be used as a strain sensor. The above method provides a way for the preparation of thermoplastic polyurethane elastomer and ionic gel.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing an ion gel based on thermoplastic polyurethane elastomer. Background Technology

[0002] Ionogels are a novel type of gel material characterized by the use of ionic liquids as their dispersion medium. This material combines several advantages of ionic liquids, including excellent ionic conductivity, electrochemical stability, low volatility, and outstanding flame retardancy. Inheriting the excellent conductivity of ionic liquids, ionogels show great application potential in electronic devices, such as ionic skin and flexible electronic devices. Despite the broad application prospects of ionogels in these fields, their mechanical properties are generally poor, such as lower tensile strength, toughness, and modulus, due to the plasticizing effect of ionic liquids causing the polymer to tend towards a viscous flow state rather than an elastic state. This limits their application in a wider range of fields. Existing reported ionogel materials typically do not possess high strength and elongation at break; therefore, it is necessary to design ionogel materials with high strength and elongation at break. Summary of the Invention

[0003] The present invention aims to provide a thermoplastic polyurethane elastomer and an ion gel, including their preparation methods and the application of the ion gel in strain sensors. The thermoplastic polyurethane elastomer provided by the present invention is based on a novel diamino chain extender. This chain extender contains amide groups and tertiary amine groups. The amide groups can serve as hydrogen bonding sites, while the tertiary amine groups can be converted into quaternary ammonium salt groups through a quaternization reaction, serving as electrostatic bonding sites. The resulting polyurethane elastomer exhibits excellent mechanical properties, self-healing ability, and recyclability. By introducing ionic liquids containing hydrogen bonding sites through hydrogen bonding and electrostatic forces, the resulting ion gel material exhibits superior mechanical properties, strain sensing performance, and high electrical conductivity. The present invention successfully prepared the diamino chain extender through a simple reaction process and further synthesized the thermoplastic polyurethane elastomer using this chain extender. High-performance ion gel materials can also be prepared through a simple doping step.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A diamino chain extender containing both an amide group and a tertiary amine group; the amide group provides hydrogen bonding sites for the polymer; and the tertiary amine group is capable of quaternization to form a quaternary ammonium salt.

[0006] The structural formula of the diamino chain extender of the present invention is as follows:

[0007]

[0008] Where n is 1 to 10.

[0009] This invention discloses a method for preparing the above-mentioned diamino chain extender, comprising the following steps: preparing a chain extender precursor using methyl acrylate and N,N-dimethylethylenediamine as raw materials; and then preparing a diamino chain extender using the chain extender precursor and ethylenediamine as raw materials.

[0010] As an example, the present invention provides a method for preparing a diamino chain extender, comprising the following steps:

[0011] (1) Methyl acrylate and N,N-dimethylethylenediamine are reacted at room temperature for 8–15 h to obtain the precursor of the chain extender; preferably, after the reaction is completed, methanol and methyl acrylate are removed by vacuum distillation to obtain the precursor of the chain extender, the chemical structure of which is as follows:

[0012] ;

[0013] (2) The chain extender precursor and ethylenediamine are reacted at room temperature to 50°C for 18 to 30 h to obtain a diamino chain extender; preferably, after the reaction is completed, methanol and ethylenediamine are removed by vacuum distillation to obtain the diamino chain extender 3,3'-((2-(dimethylamino)ethyl)imino)bis(N-(2-aminoethyl)propionamide) (DEAAP), whose chemical structural formula is as follows:

[0014] .

[0015] This invention discloses a thermoplastic polyurethane elastomer, wherein the raw materials for preparing the thermoplastic polyurethane elastomer include diisocyanate, the above-mentioned diamino chain extender, diol, and haloalkanes.

[0016] In this invention, the diol is a macromolecular diol, and the halogenated alkane includes bromoalkane; the diisocyanate includes, but is not limited to, one or more of isoflurane diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

[0017] In this invention, the molar ratio of the diisocyanate to the diol is (5-2):1; the molar ratio of the haloalkane to the diamino chain extender is (1.8-2.2):1.

[0018] This invention provides a method for preparing the above-mentioned thermoplastic polyurethane elastomer, comprising the following steps:

[0019] Preparation of prepolymer: In the presence of a catalyst, macromolecular diol and diisocyanate are reacted at 75-90℃ for 0.5-2 h to obtain isocyanate-terminated polyurethane prepolymer;

[0020] Polymer preparation: Polyurethane prepolymers capped with diamino chain extender isocyanate were reacted at room temperature for 10–15 h to obtain the polymer;

[0021] Quaternization reaction of thermoplastic polyurethane elastomer: react bromoalkanes with polymers at 40℃~60℃ for 10~15 h to obtain thermoplastic polyurethane elastomer; preferably, the obtained polymer solution is precipitated in diethyl ether and washed, and then dried to obtain thermoplastic polyurethane elastomer material.

[0022] In the above technical solution, the weight-average molecular weight of the macromolecular diol is 1000 g mol. -1 ~3000 g mol -1 2000 g mol is preferred. -1 The molar ratio of the diisocyanate to the macromolecular diol is (4-3):1; the R value, i.e., the molar ratio of isocyanate to (hydroxyl + amino group), is 1.2:1.

[0023] In the above technical solutions, the molar ratio of bromoalkane to diamino chain extender is 2:1.

[0024] In the above technical solutions, the selected macromolecular diols include, but are not limited to, one or more of polycaprolactone diol, polytetrahydrofuran, polycarbonate diol, and polyethylene glycol.

[0025] In the above technical solutions, the selected diisocyanates include, but are not limited to, one or more of isoflurane diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

[0026] Preferably, the macromolecular diol is polycaprolactone diol (PCL).

[0027] Preferably, the diisocyanate is isoflurone diisocyanate (IPDI), whose chemical structural formula is as follows:

[0028]

[0029] This invention discloses a thermoplastic polyurethane elastomer-based ionogel material, the raw materials for which include the aforementioned thermoplastic polyurethane elastomer and an ionic liquid; preferably, the ionic liquid includes 1-ethyl-3-methylimidazolium hydrogen sulfate.

[0030] The thermoplastic polyurethane elastomer and ionic liquid of the present invention are used to prepare a thermoplastic polyurethane elastomer-based ionogel material.

[0031] Preferably, the mass ratio of thermoplastic polyurethane elastomer to ionic liquid is 1: (0.1 to 0.4).

[0032] This invention discloses the application of the above-mentioned diamino chain extender in the preparation of polyurethane materials; or the application of the above-mentioned thermoplastic polyurethane elastomer-based ionogel material in the preparation of functional materials; preferably, the functional materials include ion skin and flexible electronic devices, strain sensors, etc.

[0033] This invention discloses a strain sensor, the raw materials for which are prepared, including the above-mentioned thermoplastic polyurethane elastomer-based ionogel material.

[0034] As an example, the present invention also provides a method for preparing a thermoplastic polyurethane-based ionogel material: the thermoplastic polyurethane elastomer obtained above is heated and stirred with the ionic liquid 1-ethyl-3-methylimidazolium hydrogen sulfate at 70-90°C for 3-5 h to obtain a thermoplastic polyurethane-based ionogel material; further, the obtained ionogel solution is then coated onto a mold and dried to obtain the ionogel material; for example, the ionogel solution is dried at 80°C for 12 h, and then vacuum dried at 60°C for 24 h to obtain the ionogel material.

[0035] The chemical structural formula of the ionic liquid 1-ethyl-3-methylimidazolium hydrogen sulfate is as follows:

[0036]

[0037] By adopting the above technical solution, the present invention has the following advantages:

[0038] This invention successfully prepared a novel thermoplastic polyurethane elastomer by introducing amide groups as hydrogen bonding sites and quaternary ammonium salt groups as electrostatic bonding sites into the side chain. Furthermore, an ionogel with excellent mechanical properties was prepared by doping with ionic liquids. For the synthesis of the diammonium chain extender, the simple and efficient Michael addition reaction and ammonolysis of the ester were selected. These two reactions have advantages such as high atom utilization and fast reaction rate, and are relatively simple to purify. The prepared thermoplastic polyurethane elastomer material exhibits good mechanical properties, self-healing, and recyclability due to the hydrogen bonding forces between the amide groups. The ionogel material prepared from this thermoplastic polyurethane elastomer also exhibits good mechanical properties, mainly high tensile strength, excellent elongation at break, and outstanding toughness. In addition, this ionogel material has been successfully applied to strain sensing. This invention provides a novel approach for the preparation of thermoplastic polyurethane elastomers and high-toughness ionogels. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the appearance of the ion gel prepared in Example 4 of the present invention.

[0040] Figure 2The proton nuclear magnetic resonance spectrum of the diamino chain extender DEAAP prepared in Example 2 of this invention ( 1 Schematic diagram of H NMR.

[0041] Figure 3 This is a schematic diagram of the electrospray ionization mass spectrometry (ESI-MS) of the diamino chain extender DEAAP prepared in Example 2 of the present invention.

[0042] Figure 4 This is a schematic diagram of the Fourier transform infrared (FT-IR) spectrum of the diamino chain extender DEAAP prepared in Example 2 of the present invention.

[0043] Figure 5 The thermoplastic polyurethane elastomer prepared in Example 4 of this invention: (a) before quaternization modification; (b) after quaternization modification. 1 Schematic diagram of H NMR.

[0044] Figure 6 This is a schematic diagram of the high-resolution X-ray electron spectroscopy (XPS) of the thermoplastic polyurethane elastomer prepared in Example 4 of the present invention.

[0045] Figure 7 This is an FT-IR schematic diagram of the diamino chain extender prepared in Example 2 and the thermoplastic polyurethane elastomer prepared in Example 8 of the present invention (IPDI and PCL).

[0046] Figure 8 This is an FT-IR schematic diagram of the thermoplastic polyurethane elastomer prepared in Example 4 of the present invention.

[0047] Figure 9 This is a schematic diagram of X-ray diffraction (XRD) of the thermoplastic polyurethane elastomer prepared in Example 4 of the present invention.

[0048] Figure 10 The stress-strain curves of the thermoplastic polyurethane elastomers prepared in Examples 3 to 5 of the present invention are shown.

[0049] Figure 11 The stress-strain curve of the fracture energy test for the thermoplastic polyurethane elastomer prepared in Example 4 of the present invention.

[0050] Figure 12 The stress-strain curves of the thermoplastic polyurethane elastomer prepared in Example 4 of the present invention under cyclic tensile stress at different strains are shown.

[0051] Figure 13 The stress-strain curve of the thermoplastic polyurethane elastomer prepared in Example 4 of this invention after three cycles of recycling is obtained by uniaxial tensile testing.

[0052] Figure 14The stress-strain curves of the thermoplastic polyurethane elastomer prepared in Example 4 of this invention under uniaxial tensile stress at different repair times are shown.

[0053] Figure 15 The ion gel prepared by [EMIM][HSO4] and Example 8 of this invention 1 Schematic diagram of H NMR.

[0054] Figure 16 This is an FT-IR schematic diagram of the thermoplastic polyurethane elastomer [EMIM][HSO4] prepared in Example 4 and the ion gel prepared in Example 8 of the present invention.

[0055] Figure 17 This is a schematic diagram of the ultraviolet (UV-vis) spectra of the thermoplastic polyurethane elastomer prepared in Example 4 and the ion gel prepared in Example 8 of the present invention.

[0056] Figure 18 The uniaxial tensile stress-strain curves are for the ionogels prepared in Examples 7-9 of this invention.

[0057] Figure 19 The stress-strain curves of the ion gel prepared in Example 8 of this invention under cyclic stretching at different strains are shown.

[0058] Figure 20 The following are schematic diagrams of (a) electrochemical impedance spectroscopy (EIS) and (b) ionic conductivity histograms of the ion gels prepared in Examples 7-9 of this invention.

[0059] Figure 21 This is a schematic diagram of the sensitivity coefficient (GF) of the ion gel prepared in Example 8 of the present invention.

[0060] Figure 22 The diagram shows the relative resistance changes of the ion gel prepared in Example 8 of this invention under (a) 5 cycles of different strains and (b) 100 cycles of cyclic stretching with 50% strain.

[0061] Figure 23 This is a schematic diagram of the sensing performance of the ion gel prepared in Example 8 of the present invention.

[0062] Figure 24 The mechanical properties of the ionogel prepared in Example 8 of this invention are compared with those of a similar polyurethane-based ionogel. Detailed Implementation

[0063] This invention develops a novel diamino chain extender, DEAAP. Polyurethane elastomers prepared using this chain extender contain amide and tertiary amine groups. A one-step quaternization reaction yields polyurethane elastomers with quaternary ammonium salts on the side chains. These polyurethane elastomers exhibit excellent mechanical properties, including high tensile strength, excellent elongation at break, and good toughness. The material also exhibits high fracture energy in terms of damage resistance. Furthermore, ionogel materials were prepared using this polyurethane elastomer as a substrate. In this process, the amide groups act as hydrogen bonding sites, while the quaternary ammonium salt groups act as electrostatic bonding sites. By adding the ionic liquid [EMIM][HSO4], the prepared ionogel exhibits high tensile strength and elongation at break, providing an innovative solution for the preparation of ionogel materials.

[0064] In this invention, the thermoplastic polyurethane elastomer is prepared from the following raw materials:

[0065] Chain extender: the above-mentioned diamino chain extender;

[0066] Diisocyanates: one or more of isoflurone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate;

[0067] Macromolecular diols: one or more of polycaprolactone diol, polytetrahydrofuran, polycarbonate diol, and polyethylene glycol;

[0068] Bromoalkanes: One of 1-bromohexane, 1-bromopropane, and 1-bromododecane.

[0069] As is common knowledge, thermoplastic polyurethane elastomers are prepared in the presence of solvents and catalysts (such as dibutyltin dilaurate).

[0070] In the thermoplastic polyurethane elastomer of the present invention, the polymer backbone contains amide groups as hydrogen bonding sites; the side chains contain quaternary ammonium salt groups as electrostatic bonding sites.

[0071] In the thermoplastic polyurethane elastomer-based ionogel material of the present invention, the ionic liquid 1-ethyl-3-methylimidazolium hydrogen sulfate is bonded to the polymer through hydrogen bonding and electrostatic forces.

[0072] As an example, the present invention provides a method for preparing a diamino chain extender, comprising the following steps:

[0073] (1) Methyl acrylate was dissolved in methanol, and then a methanol solution of N,N-dimethylethylenediamine was added dropwise at room temperature. After the addition was complete, the reaction continued at room temperature for 12 h. After the reaction was completed, methanol and methyl acrylate were removed by vacuum distillation to obtain the precursor of the chain extender, whose chemical structure is as follows:

[0074]

[0075] (2) The precursor of the chain extender was dissolved in methanol solvent, and then a methanol solution of ethylenediamine was slowly added dropwise at 40°C. After the addition was complete, the reaction was allowed to proceed at 40°C for 24 hours. After the reaction was completed, methanol and ethylenediamine were removed by vacuum distillation to obtain the diamine chain extender 3,3'-((2-(dimethylamino)ethyl)imino)bis(N-(2-aminoethyl)propionamide) (DEAAP), whose chemical structure is as follows:

[0076]

[0077] This invention provides a method for preparing a thermoplastic polyurethane elastomer, comprising the following steps:

[0078] Preparation of the prepolymer: A macromolecular diol was vacuum-stirred at 120°C to remove moisture, followed by the addition of a solution of diisocyanate and dibutyltin dilaurate in N,N-dimethylformamide (DMF). The reaction was carried out at 85°C for 1 h. This yielded an isocyanate-terminated polyurethane prepolymer.

[0079] Preparation of thermoplastic polyurethane elastomer: DMF solution of diamino chain extender was added to prepolymer solution at room temperature and the reaction was continued at room temperature for 12 h.

[0080] Quaternization reaction of thermoplastic polyurethane elastomer: Brominated alkanes are added to the obtained polymer solution and reacted at 50°C for 12 hours. Subsequently, the obtained polymer solution is precipitated in diethyl ether, washed, and dried to obtain the thermoplastic polyurethane elastomer material.

[0081] To better understand the content of this invention, the following description, in conjunction with specific implementation methods, further illustrates the content of this invention. However, the scope of protection of this invention is not limited to the following embodiments. The reagents used in this invention are existing products, and the specific preparation operations and performance tests are conventional techniques. For example, the addition of raw materials is a conventional operation in the field.

[0082] Example 1

[0083] Methyl acrylate (8.610 g) was dissolved in 10 mL of methanol in a round-bottom flask; simultaneously, N,N-dimethylethylenediamine (3.472 g) was dissolved in 20 mL of methanol in a constant-pressure funnel. The methanol solution of N,N-dimethylethylenediamine was added dropwise at room temperature; after the addition was complete, the reaction was allowed to continue at room temperature for 24 h. After the reaction was completed, methanol and methyl acrylate were removed by vacuum distillation (60 °C), and heating was continued until no more bubbles were generated, at which point the chain extender precursor was obtained.

[0084] Example 2

[0085] Anhydrous ethylenediamine (19.232 g) was dissolved in 20 mL of methanol in a round-bottom flask; simultaneously, 10.406 g of the chain extender precursor was dissolved in 30 mL of methanol and placed in a constant-pressure funnel. The methanol solution of the chain extender precursor was added dropwise at room temperature; after the addition was complete, the reaction was allowed to continue at 40 °C for 24 h. After the reaction was complete, methanol and ethylenediamine were removed by vacuum distillation (80 °C), and heating continued until no more bubbles were generated, at which point the diamino chain extender DEAAP was obtained.

[0086] Example 3

[0087] Prepolymerization reaction: PCL (8.0 g, 2000 g mol) -1 The solution was placed in a three-necked flask and heated to 120°C with vacuum stirring for 1 h to remove moisture. Then, the reaction temperature was set to 85°C. Simultaneously, IPDI (2.7 g) and two drops of DBTDL were dissolved in 30 ml of dry DMF, and this solution was added to the three-necked flask. The reaction was continued at 85°C for 1 h, with nitrogen continuously purging throughout the process.

[0088] Chain extension reaction: After the prepolymerization reaction was completed, the temperature was set to 25℃, and DEAAP (1.9 g) was dissolved in 100 ml of dry DMF and then added to a three-necked flask. The reaction was carried out at 25℃ for 12 h, with nitrogen gas continuously injected during the reaction.

[0089] Quaternization reaction: The temperature was raised to 50°C, 1-bromohexane (2.0 g) was added, and the reaction was maintained for 12 hours. After the reaction was completed, the sample was dropped into diethyl ether to precipitate, followed by washing three times. After drying, a thermoplastic polyurethane elastomer product was obtained.

[0090] Molding: Dissolve 0.5 g of thermoplastic polyurethane elastomer sample in 1.5 ml of DMF, then coat the polymer solution into a PTFE mold with dimensions of 4 cm × 2 cm × 0.1 cm (length × width × thickness). Dry at 80°C for 12 h, then vacuum dry at 60°C for 24 h to obtain a thermoplastic polyurethane elastomer film.

[0091] Examples 4-5

[0092] By changing the molar ratio of IPDI to PCL while keeping R at 1.2, and following the same steps and conditions as in Example 3, different thermoplastic polyurethane elastomers were obtained. The numbers, components, and contents of all the prepared thermoplastic polyurethane elastomers are shown in Table 1.

[0093] Table 1 Raw material consumption amounts for different polyurethane elastomer examples

[0094]

[0095] After thermoplastic polyurethane elastomer evaporates and forms a film, such as Figure 1 As shown, this is an APU. 3.5 A photograph of a thermoplastic polyurethane elastomer.

[0096] Example 6

[0097] 0.5 g of thermoplastic polyurethane elastomer was dissolved in 1.5 ml of DMF, and 0.05 g of ionic liquid [EMIM][HSO4] was added. The mixture was heated and stirred at 80 °C for 4 h. The solution was then coated into a PTFE mold with dimensions of 4 cm × 2 cm × 0.1 cm (length × width × thickness). After drying at 80 °C for 12 h and under vacuum at 60 °C for 24 h, an ionogel membrane was obtained.

[0098] Examples 7-9

[0099] By varying the amount of ionic liquid added, while adhering to the same steps and conditions as in Example 6, different ionic gels were obtained. The numbers, components, and contents of all prepared ionic gels are shown in Table 2.

[0100] Table 2 Raw material usage amounts for different ionogel examples

[0101]

[0102] After thermoplastic polyurethane elastomer evaporates and forms a film, such as Figure 1 As shown, this is an APU. 3.5 / 30 Actual image of the ion gel.

[0103] Example 10

[0104] The structure of the diamino chain extender DEAAP was characterized using the following methods:

[0105] like Figure 2 As shown, DEAAP was characterized by proton nuclear magnetic resonance spectroscopy. Assigning and integrating all the characteristic peaks of DEAAP confirmed its successful synthesis. Figure 3 As shown, DEAAP was analyzed by electrospray ionization mass spectrometry. The results showed that the mass-to-charge ratio of its most abundant peak was 317.27, which differed from the predicted molecular weight of 316.26 by exactly one proton, further confirming the successful preparation of DEAAP. Furthermore, as... Figure 4 As shown, Fourier transform infrared spectroscopy analysis of DEAAP was performed at 3284 cm⁻¹. -1 The NH stretching vibration peak of DEAAP can be found at 1639 cm⁻¹. -1 The peak at 1546 cm⁻¹ belongs to the stretching vibration absorption peak of C=O in amides.-1 The absorption peak at that position belongs to the characteristic spectrum of the amide II band of CN and NH. The above analysis confirms the successful preparation of the chain extender DEAAP.

[0106] Example 11

[0107] For thermoplastic polyurethane elastomers (in the form of APU) 3.5 Taking a sample as an example, structural characterization is performed using the following method:

[0108] like Figure 5 As shown, the thermoplastic polyurethane elastomer (APU) was analyzed by proton nuclear magnetic resonance spectroscopy. 3.5 The characteristic peaks were assigned. Furthermore, comparison with the unquaternized sample revealed a change in the chemical shift of the methyl H atom bonded to the N atom on the quaternary ammonium salt group, confirming the successful modification of the quaternary ammonium salt. Figure 6 As shown, high-resolution X-ray electron spectroscopy was used to study the APU. 3.5 Narrow-scan peak analysis of the nitrogen element yielded a quaternization degree Q of 23.6%. Figure 7 As shown, Fourier transform infrared spectroscopy was used to analyze the raw materials and APU. 3.5 Comparing the products reveals that the product at 2250 cm... -1 The absence of characteristic peaks for isocyanate at this location indicates successful material preparation. For example... Figure 8 As shown, at 3300 cm -1 The characteristic peak of the NH stretching vibration of amides is located at 1552 cm⁻¹. -1 The characteristic peak of the bending vibration of NH is at 1730 cm⁻¹. -1 and 1645 cm -1 The peaks at these locations correspond to the stretching vibrations of the ester carbonyl and amide carbonyl groups, respectively. The above analysis demonstrates the properties of the thermoplastic polyurethane elastomer APU. 3.5 The successful preparation of [the substance / method / etc.]. On the other hand, such as... Figure 9 As shown, X-ray diffraction was used to examine the APU. 3.5 Analysis of the sample revealed no crystallization peaks of PCL, but instead a representative amorphous diffraction peak at approximately 20°, indicating that the chain extender DEAAP inhibited the crystallization tendency of PCL.

[0109] Example 12

[0110] The mechanical properties of thermoplastic polyurethane elastomers are characterized using the following methods:

[0111] Take the above-mentioned thermoplastic polyurethane elastomer, place both ends of the material on the tensile testing machine fixture, and apply a tensile test at a speed of 50 mm / min. -1 Stretch at a certain speed and observe its tensile properties. For example... Figure 10As shown, with the increase of hard segment content, the tensile strength of thermoplastic polyurethane elastomer increases from 12.6 MPa to 43.1 MPa. In this structural design, the chain extender introduces additional amide groups, which, together with urethane and urea bonds, can provide a large number of hydrogen bond donors and acceptors. Due to the strong intermolecular hydrogen bonding between the hard segments, these hydrogen bonds act as sacrificial bonds during stretching, dissipating energy through breakage and recombination. Because APU... 3.5 It exhibited optimal toughness, therefore further analysis was conducted. Notched tensile tests were performed to assess the elastomer's tolerance to defects and damage. Figure 11 As shown, calculations were performed using the Greensmith method, and the results indicate that the APU... 3.5 Even with a 1 mm notch, the elastomer exhibits a fracture energy as high as 110.5 kJ / m². -2 To characterize the APU 3.5 To assess the fatigue resistance of the sample, cyclic tensile tests were further conducted. The tensile strength was measured at 50 mm / min. -1 Cyclic tensile tests were performed on the specimen at different strains using a certain rate. For example... Figure 12 As shown, the hysteresis loop gradually increases with increasing tensile strain, indicating that higher strain leads to greater energy dissipation. This suggests that during stretching, hydrogen bonds break and are sacrificed to dissipate energy. The mechanical parameters of thermoplastic polyurethane elastomers with different hard segment ratios are shown in Table 3.

[0112] Table 3 Comparison of uniaxial tensile data for thermoplastic polyurethane elastomers

[0113]

[0114] For thermoplastic polyurethane elastomers (in the form of APU) 3.5 Taking a sample as an example, a recyclability performance test was conducted.

[0115] The crosslinking of the thermoplastic polyurethane elastomer sample was achieved through hydrogen bonding rather than covalent bonding, indicating that the sample still possesses a linear structure and can be dissolved or melted. Therefore, a recycling experiment was conducted on the elastomer sample. First, the APU sample... 3.5 After being chopped and dissolved in ethanol, the solution is then recoated into a polytetrafluoroethylene mold, and a transparent film is prepared by solvent evaporation. After each recycling, a uniaxial tensile test is performed again to obtain the stress-strain curve. Figure 13 As shown, even after three recycling cycles, its stress recovery rate can still reach 80%. Therefore, the APU 3.5 It demonstrated good recycling capabilities.

[0116] For thermoplastic polyurethane elastomers (in the form of APU) 3.5 Taking this as an example, a self-healing performance test was conducted.

[0117] Thermoplastic polyurethane elastomers possess self-healing capabilities due to the dynamic effects of hydrogen bonds within hard domains. However, the dynamic process of hydrogen bond breakage and reformation often occurs at high temperatures, thus requiring relatively high temperatures to achieve the elastomer's self-healing process. First, a sample is uniformly cut at its center, and then the cuts are aligned. Next, it is heated at 80°C for different times, and uniaxial tensile tests are performed to obtain the corresponding stress-strain curves. (The text abruptly ends here.) Figure 14 As shown, after heating the sample at 80℃ for 36 hours, its stress-strain curve has essentially recovered to its initial state, indicating that the sample has completed the self-healing process. Even when the strain reaches 1000%, it still did not fracture; therefore, the APU... 3.5 The sample exhibited excellent self-healing ability.

[0118] Example 13

[0119] For thermoplastic polyurethane-based ionogels (with APU) 3.5 Taking 30 samples as an example, structural characterization was performed using the following method:

[0120] Using proton nuclear magnetic resonance spectroscopy, the ionic liquid [EMIM][HSO4] and the ion gel APU were compared. 3.5 A comparison of / 30 revealed that [EMIM] + The active hydrogen atoms on the polymer matrix showed a significant shift, indicating the formation of hydrogen bonds between the cations of the ionic liquid [EMIM][HSO4] and the polymer. Further characterization of the ionic liquid and ionic gel was performed using FT-IR. Figure 16 As shown, 3152 cm -1 The CH stretching vibration on the imidazole ring shifts to a lower wavenumber to 3151 cm⁻¹. -1 This also proves that there are hydrogen bonds between the active hydrogen on the imidazole ring and the polymer. On the other hand, the original location at 1022 cm⁻¹... -1 The stretching vibration peak at S=O shifts to a higher wavenumber of 1653 cm⁻¹. -1 This indicates that S=O acts as a hydrogen bond acceptor, forming hydrogen bonds with the polymer. Finally, the original location at 1730 cm⁻¹... -1 and 1646 cm -1 The C=O stretching vibration peaks of the ester and amide bonds at the ester bond and amide bond respectively shifted to higher wavenumbers, reaching 1731 cm⁻¹. -1 and 1653 cm -1 This indicates that the carbonyl group on the polymer acts as a hydrogen bond acceptor, and hydrogen bonds exist between it and the ionic liquid. At 835 cm⁻¹ -1 The peak at that location belongs to the stretching vibration peak of SO in [EMIM][HSO4], but in APU 3.5In / 30, the peak shifts to a higher wavenumber of 857 cm⁻¹. -1 This indicates that [HSO4] - Electrostatic interactions occurred with the quaternary ammonium salt on the polymer molecules. The above characterization demonstrates the interaction between the ionic liquid [EMIM][HSO4] and the polymer APU. 3.5 There are hydrogen bonds and electrostatic interactions between them. Additionally, such as... Figure 17 As shown, characterization of the transparency of the ion gel reveals that its transparency in the visible light range is not significantly different from that of thermoplastic polyurethane elastomer, indicating that the ion liquid and the polymer have good compatibility.

[0121] Example 14

[0122] The mechanical properties of thermoplastic polyurethane-based ionogels were characterized using the following methods:

[0123] Take the above ionogel, place both ends of the material on the tensile testing machine fixture, and apply pressure at 50 mm / min. -1 Stretch at a certain speed and observe its tensile properties. For example... Figure 18 As shown, with the increase of the ionic liquid [EMIM][HSO4] content, the strength of the ionogel gradually decreased, and the toughness also gradually decreased. From the addition amount of 0 to 40 wt%, the toughness decreased from 187.1 MJ / m. -3 Gradually decreased to 68.5 MJ m -3 This is because the incorporation of ionic liquids disrupts the original hard-domain crosslinking through hydrogen bonding with the polymer backbone. Furthermore, the addition of ionic liquids also plasticizes the polymer, further reducing its strength and toughness. Therefore, the fluidity between polymer chains increases, manifested as a gradual increase in elongation at break. However, the ionic liquid content cannot be increased further beyond 40 wt%, because the material's energy dissipation capacity decreases when the ionic liquid content reaches a certain level. When the ionic liquid content reaches 30 wt%, its toughness reaches 78.6 MJ / m². -3 To gain a deeper understanding of the mechanical properties of ionogels, cyclic tensile measurements were performed under different cyclic strains. Using APU... 3.5 For example, / 30 Figure 19As shown, under the initial strain of 100%, all samples only undergo elastic deformation because the dynamic cross-linking network remains intact, and the ionogel can recover to its initial state driven by entropy. With increasing strain, the hysteresis area of ​​these curves increases significantly. This is because large deformation disrupts dynamic interactions such as hydrogen bonds and electrostatic forces, leaving insufficient time to rebuild these dynamic bonds. The figure also shows that the hysteresis area is proportional to the strain, indicating that more energy is dissipated at higher strains, thus preventing damage to the ionogel material. The mechanical parameters of ionogels with different ionic liquid contents are shown in Table 4.

[0124] Table 4 Comparison of uniaxial tensile data of thermoplastic polyurethane elastomers

[0125]

[0126] Example 15

[0127] The electrical properties and sensing characteristics of thermoplastic polyurethane-based ionogels were characterized using the following methods:

[0128] Electrochemical impedance spectroscopy measurements were performed using an electrochemical workstation (CS350, corrtest). An ionogel membrane and two symmetrical stainless steel electrodes (Φ=14 mm) were assembled before testing. The test frequency range was 1Hz-100kHz. Figure 20 As shown in the figure, the electrochemical impedance spectroscopy of the ionogels with different ion liquid contents reveals that the bulk impedance gradually decreases with increasing ion liquid content. On the other hand, as the amount of ion liquid added increases from 10 wt% to 40 wt%, the conductivity increases from 1.15 × 10⁻⁶. -3 S m -1 Increased to 47.29×10 -3 S m -1 Considering the combined effects of mechanical and electrical properties, an APU will be selected subsequently. 3.5 / 30 is used for sensing characterization.

[0129] For thermoplastic polyurethane-based ionogels (with APU) 3.5 Sensing performance was tested using 30 samples as an example.

[0130] The sensing performance of the ion gel was tested using an LCR digital bridge tester (TH2830, Changzhou Tonghui Electronics). The ion gel of this invention was taken, and copper wires were connected to both ends of each wire. The other end of the copper wires was connected to the testing instrument, and the ion gel was assembled into a wearable sensor to detect changes in resistance. To characterize the sensitivity of the sensor, such as... Figure 21As shown, the change in resistance signal was monitored within the strain range of 0-100%, and linear fitting was performed. The calculated sensitivity coefficient was 0.64, indicating that the strain sensor has good sensing sensitivity and is suitable for signal monitoring and transmission. Cyclic tensile tests were conducted on the strain sensor under different strain conditions, and its resistance signal was measured. Figure 22 As shown in Figure a, the resistance signal exhibits a slight decay with increasing strain, consistent with the hysteresis observed in the cyclic tensile test results mentioned earlier. This indicates that the fatigue resistance of the material can influence its application in strain sensors to some extent. The material underwent over 100 cyclic tensile tests at 50% strain, and its resistance signal was monitored. Figure 22 As shown in Figure b, the signal value exhibits some decay in the initial stage of cyclic stretching. However, with the increase in the number of stretching cycles, the resistance signal change value generally shows a stable trend, demonstrating the stability of signal transmission. Figure 23 As shown, the strain sensor was fixed to the wrist, fingers, elbow, and knee joints of the human body, and all transmitted signals with high recognition accuracy. This indicates that the ionogel can be used to monitor human motion signals in real time in the field of strain sensor applications. The above demonstrates that the ionogel material invented in this paper has good stability and sensitivity as a strain sensor.

[0131] This invention develops a novel diamine chain extender, DEAAP. Polyurethane elastomers prepared using this chain extender contain amide and tertiary amine groups. A one-step quaternization reaction yields polyurethane elastomers with quaternary ammonium salts on the side chains. These polyurethane elastomers exhibit excellent mechanical properties, including high tensile strength, excellent elongation at break, and good toughness. The material also exhibits high fracture energy in terms of damage resistance. Figure 24 (See below for references in the figure) As shown, APU 3.5 The / 30 sample exhibited higher values ​​in strength and elongation at break than other polyurethane-based ionogel materials reported in the literature. Further, using this polyurethane elastomer as a substrate, ionogel materials were prepared. In this process, amide groups acted as hydrogen bonding sites, while quaternary ammonium salt groups acted as electrostatic bonding sites. By adding the ionic liquid [EMIM][HSO4], the prepared ionogel exhibited high tensile strength and elongation at break, providing an innovative solution for the preparation of ionogel materials.

[0132] [1] TL Chen, G. Ye, HW Wu, SY Qi, GR Ma, Y. Zhang, Y. Zhao, J. Zhu, XD Gu, N. Liu Adv. Funct. Mater. 2022, 32, 2206424.

[0133] [2] B. C. Zhao, J. Q. Yan, F. Long, W. Qiu, G. Q. Meng, Z. C. Zeng,H. Huang, H. Wang, N. B. Lin, X. Y. Liu Adv. Sci. 2023, 10 , e2300857.

[0134] [3] X. Wen, J. H. Xu, H. B. Wang, Z. L. Du, S. Wang, X. Cheng Polym. Eng. Sci. 2022, 62 , 3132-3143.

[0135] [4] J. H. Xu, H. Wang, X. Wen, S. Wang, H. B. Wang ACS Appl. Mater. Interfaces 2022, 14 , 54203-54214.

[0136] [5] J. H. Xu, H. Wang, X. S. Du, X. Cheng, Z. L. Du, H. B. Wang ACS Applied Materials Interfaces 2021, 13 , 20427-20434.

[0137] [6] Y. L. Fang, H. L. Cheng, H. He, S. Wang, J. M. Li, S. Z. Yue, L.Zhang, Z. L. Du, J. Y. Ouyang Adv. Funct. Mater. 2020, 30 , 2004699.

[0138] [7] Y. L. Zhao, H. L. Cheng, Y. X. Li, J. C. Rao, S. Z. Yue, Q. J.Le, Q. Qian, Z. Liu, J. Y. Ouyang J. Mater. Chem. A 2022, 10 , 4222-4229.

[0139] [8] YP Li, Y. Jin, WH Zeng, HY Jin, X. Shang, R. Zhou ACS Applied Materials Interfaces 2023, 15 , 35469-35482.

[0140] [9] FY Ou, T. Xie, XZ Li, ZC Zhang, C. Ning, L. Tuo, WYPan, CS Wang, XY Duan, QH Liang, W. Gao, ZQ Li, SL Zhao Mater. Horiz. 2024, 11 , 2191-2205.

[0141]

[10] HB Wang, JH Xu, KJ Li, Y. Dong, ZL Du, S. Wang J. Mater. Chem. B 2022, 10 , 1301-1307.

[0142] The examples described above are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above examples. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention are still considered to be within the scope of protection of the present invention.

Claims

1. A diamino chain extender characterized in that, The diamino chain extender contains an amide group and a tertiary amine group; the structural general formula of the diamino chain extender is as follows: ； Wherein, n is 1.

2. The process for the preparation of the diamino chain extender of claim 1, characterized in that, The chain extender precursor is prepared from methyl acrylate and N,N-dimethylethylenediamine; then the diamino chain extender is prepared from the chain extender precursor and ethylenediamine.

3. A thermoplastic polyurethane elastomer characterized in that, The raw materials for preparing the thermoplastic polyurethane elastomer include diisocyanate, the diamino chain extender of claim 1, dihydric alcohol and halogenated alkane.

4. The thermoplastic polyurethane elastomer according to claim 3, wherein, The molar ratio of the diisocyanate to the dihydric alcohol is (5-2):1; the molar ratio of the halogenated alkane to the diamino chain extender is (1.8-2.2):

1.

5. A thermoplastic polyurethane elastomer based ionic gel material characterized in that, The raw materials for preparing the thermoplastic polyurethane elastomer-based ionic gel material include the thermoplastic polyurethane elastomer of claim 3 and ionic liquid.

6. The thermoplastic polyurethane elastomer-based ionic gel material of claim 5, wherein, The mass ratio of the thermoplastic polyurethane elastomer to the ionic liquid is 1:(0.1-0.4).

7. The use of the diamino chain extender of claim 1 in preparing polyurethane materials; or the use of the thermoplastic polyurethane elastomer-based ionic gel material of claim 5 in preparing functional materials.

8. A strain sensor, the raw materials for preparing which include the thermoplastic polyurethane elastomer-based ionic gel material of claim 5.

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